US20050079812A1 - Tool, apparatus, and method for precision polishing of lenses and lens molds - Google Patents
Tool, apparatus, and method for precision polishing of lenses and lens molds Download PDFInfo
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- US20050079812A1 US20050079812A1 US10/963,189 US96318904A US2005079812A1 US 20050079812 A1 US20050079812 A1 US 20050079812A1 US 96318904 A US96318904 A US 96318904A US 2005079812 A1 US2005079812 A1 US 2005079812A1
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- polishing
- bladder
- mandrel
- tool
- compression
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
- B24B13/01—Specific tools, e.g. bowl-like; Production, dressing or fastening of these tools
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
- B24B13/06—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor grinding of lenses, the tool or work being controlled by information-carrying means, e.g. patterns, punched tapes, magnetic tapes
Definitions
- a polishing tool for correcting surface errors, and for polishing objects comprising a wide variety of materials and shapes including precision optical surfaces and injection mold inserts.
- This invention relates to tools, an apparatus, and a method for correcting figure errors, and for polishing a wide variety of materials and shapes including but not limited to precision optical surfaces, injection mold inserts, thin film coating dies, and the like.
- the method of the present invention provides for improving and further finishing of any surface, ranging from a relatively rough ground surface to a polished surface.
- the part being finished according to the present invention is measured with a coordinate measurement machine (CMM), a surface profilometer, an interferometer, microscope or some other measuring instrument capable of giving surface roughness and or profile data.
- CCM coordinate measurement machine
- the data from such measurement and analysis is then entered into a machine process-controlling computer that then manipulates the data into process parameters for improving or polishing the desired component by a polishing machine of the present invention.
- a polishing tool comprising an inflatable bladder is attached to and driven by the tool spindle of the polishing machine.
- the part to be improved or polished is placed into the work piece spindle of the polishing machine. If such part is not axially symmetrical, it may be held in a braked position in the work piece spindle, or held in a fixture on a table of the machine.
- the polishing tool is then compressed against and traversed in a path over the component.
- the polishing tool further comprises actuation means to extend and/or position and/or compress the inflatable bladder or other compliant part with respect to the part to be improved or polished.
- actuation means may comprise one or more linear actuating devices such as e.g., air operated or hydraulically operated cylinders.
- the present invention provides a method and apparatus for which the main goal is to polish out and remove defects left from a preceding grinding operation or to improve the accuracy of a workpiece such as a lens, mirror, insert for an injection mold, or coating die, such accuracy being relative to the intended use of the workpiece; and also to improve the economy of the polishing process.
- optical components also known as precision optics or optics generally, are typically mentioned as the workpiece.
- materials that may be finished using the method and apparatus of the present invention include, but are not limited to brittle amorphous materials such as e.g., glass, ceramics, infrared materials such as quartz, and the like.
- metals such as e.g., tool steel, stainless steel, and the like; crystalline materials such as e.g. silicon; and any other workpieces requiring high finish and form specifications.
- a polishing tool rotating around the axis thereof, is mounted to a robotic arm and is traversed by such arm across the lens surface, or alternatively, such tool is built into a computer numerically controlled (CNC) polishing machine.
- CNC computer numerically controlled
- a polishing suspension is applied, while the polishing tool is traversed across the lens surface through a predetermined typically computer controlled path.
- different volumes of material are abraded, or polished, from the lens surface.
- the robotic arm of the correction machine is programmed in such a way that the polishing tool is moved with different dwell times at different positions as such tool passes over the lens. Thus, when more material must be removed at a particular location, the dwell time is increased, and vice versa.
- the lens may be rotate around its axis, or be it may be fixed in specific positions if the robotic arm of the correction machine has such capability.
- the polishing tool wears quickly due to its small diameter, which results in the distinct disadvantages of a) typically very long polishing cycles; and b) because of quicker degradation of the small polishing foil it is much more difficult and costly to develop accurate corrective polishing routines.
- Another disadvantage is due to the small spot diameter of the tool. Material removal rates are typically very slow, since the performance is directly proportional to the size of the surfaces that are in contact during the polishing routine.
- MRF magnetorheological finishing
- U.S. Pat. Nos. 5,795,212, 6,106,380 deterministic magnetorheological finishing
- 5,839,944 apparatus deterministic magneto-rheological finishing
- 5,971,835 system for abrasive jet shaping and polishing of a surface using a magnetorheological fluid
- 6,506,102 system for magnetorheological finishing of substrates
- 6,267,651 and 6,309,285 magnetorheological finishing
- polishing suspension which contains particles that can be magnetized and therefore under the effect of strong electromagnets can be solidified.
- a polishing suspension is applied sequentially on the outside surface of a cylinder rotating around its horizontal axis.
- the polishing suspension is disposed in a thin band upon the outside surface of a rotating cylinder, and is conveyed to a location where a strong magnetic field is focused. This field is created by magnets surrounding both sides of the wheel. Under the influence of the magnetic field, the polishing suspension increases in viscosity until it is substantially an abrasive solid, thereby forming a stiff polishing body, which becomes the polishing tool.
- a lens may be polished by such solidified MRF fluid.
- the polishing suspension leaves the contact area of the lens and the magnetic field, and is then vacuumed/wiped off of the wheel and continuously recirculated.
- the lens rotates.
- the lens carrier with the lens can be placed by means of a tilting device and an assigned axis control at angles to the vertical axis.
- the edge of the lens touches the polishing tool, while with a small angle of inclination the center of the lens comes into contact with the polishing tool.
- the lens carrier is guided in such a way that it also can execute vertical movements.
- the angles of inclination are continually varied; such variation is accomplished with the use of virtual pivot point computer controlled motion that combines the two linear and one rotary axes and thus keeps the lens in consistent contact with the polishing tool.
- a spiral develops on the lens that is the trajectory of the point of contact between the solidified polishing suspension and the lens surface.
- the different material removals necessary for the correction of the lens geometry are implemented as follows:
- the dwell time of the point of contact on a certain area on the lens surface can be varied by appropriately controlling the courses of motion. Since the material removal is proportional to the dwell time, the desired corrections can be achieved.
- the polishing suspension in its “firmness” can be influenced by variation of the magnetic field strength. This further enables different material removal rates.
- a further correction option results by varying the depth of submergence of the lens into the polishing suspension.
- German patent DE003 1057 of R. Mandler the disclosure of which is incorporated herein by reference.
- the lens/mirror is polished conventionally and measured by interferometric means to map the surface and to determine how much material needs to be removed and from where.
- the lens is supported on a rotating holder with two degrees of movement, while the polishing wheel is supported with axial adjustment.
- the polishing wheel has a flexible rim inflated with a variable internal pressure to adjust the hardness of flexible rim/tire.
- Mandler relies upon changes in pressure on a polyurethane foil to impact removal rates and finishing qualities.
- Mandler can change the pressure during the process, such process does not have the ability to change to softer media, such as felt or other softer synthetic materials as is disclosed and claimed in this application.
- Mandler also discloses only a 3-axis process, whereas embodiments of the present invention include control and operation with respect to five or more axes.
- a polishing tool comprising a mandrel having a drive shank at a proximal end thereof, a threaded shank, a mandrel shank, and a flange at a distal end thereof; a solid elastic annular bladder comprising a bore, an outer surface, a lower surface, and an upper surface, said bladder disposed upon said mandrel with said lower surface of said bladder in contact with said flange of said mandrel and said mandrel shank passing through said bore in said bladder; a compression flange comprising a compression washer and a compression collar, said compression washer comprising a lower surface in contact with said upper surface of said bladder, and said compression collar comprising a bore slidingly engaged with said threaded shank of said mandrel; and a compression nut threadedly engaged with said threaded shank of said mandrel, wherein when said compression nut is tightened upon said threaded shank, said solid bladder is compressed
- a polishing tool comprising a mandrel having a drive shank at a proximal end thereof, a threaded shank, a mandrel shank, and a flange at a distal end thereof; a solid elastic annular bladder comprising a bore, an outer surface, a lower surface, and an upper surface, said bladder disposed upon said mandrel with said lower surface of said bladder in contact with said flange of said mandrel and said mandrel shank passing through said bore in said bladder; a compression flange comprising a compression washer and a compression collar, said compression washer comprising a lower surface in contact with said upper surface of said bladder, and said compression collar comprising a bore slidingly engaged with said threaded shank of said mandrel; a polishing band engaged with said outer surface of said bladder; and a compression nut threadedly engaged with said threaded shank of said mandrel, wherein when said compression nut is tight
- a polishing tool comprising a mandrel having a drive shank at a proximal end thereof, a threaded shank, a mandrel shank, and a flange at a distal end thereof; a solid elastic annular bladder comprising a bore, an outer surface, a lower surface, and an upper surface, said bladder disposed upon said mandrel with said lower surface of said bladder in contact with said flange of said mandrel and said mandrel shank passing through said bore in said bladder; and means for compressing said lower surface of said bladder toward said upper surface of said bladder, thereby causing said outer surface of said bladder to have an arcuate shape.
- the tools, apparatus, and method of the present invention are advantageous because they are simple and lower in cost compared to other approaches, and it can be adapted for the polishing of a variety of materials and shapes, particularly those objects having deeply concave shapes.
- articles of manufacture such as precision optics, injection mold inserts, and thin film coating dies can be polished with high precision at a high throughput and low cost.
- FIG. 1 is a schematic representation of one preferred polishing apparatus of the present invention
- FIG. 2A is a cross-sectional view of one preferred polishing tool of the present invention.
- FIG. 2B is a side elevation view of the polishing tool of FIG. 2A , in the process of polishing a convex lens;
- FIG. 3 is a cross-sectional view of another preferred embodiment of a polishing ring disposed upon the polishing tool of FIG. 2A ;
- FIG. 4 is a cross-sectional view of one preferred embodiment of a polishing ring disposed upon the polishing tool of FIG. 2A ;
- FIG. 5 is a flowchart depicting a method of assembly of the preferred polishing tool of FIG. 2A ;
- FIG. 6 is a flowchart depicting a method of preparing the preferred apparatus of FIG. 1 for a polishing operation.
- FIG. 7 is a flowchart of a complete method of polishing an optic using the apparatus and polishing tool of the present invention.
- FIG. 8A is a cross-sectional view of another preferred polishing tool of the present invention.
- FIG. 8B is a side elevation view of the polishing tool of FIG. 8A , in the process of polishing a concave lens;
- FIG. 9 is a schematic representation of another preferred polishing apparatus for polishing concave spheres, aspheres, convex spheres, or other conformal shapes;
- FIG. 10 is a first perspective view of another preferred polishing tool of the present invention comprising single cylinder actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished;
- FIG. 11 is a side elevation view of the polishing tool of FIG. 10 ;
- FIG. 12 is a top view of the polishing tool of FIG. 10 ;
- FIG. 13 is a second perspective view of the polishing tool of FIG. 10 , taken from the plate side of the polishing tool;
- FIG. 14 is a first perspective view of another preferred polishing tool of the present invention comprising twin cylinder actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished;
- FIG. 15 is a side elevation view of the polishing tool of FIG. 14 ;
- FIG. 16 is a top view of the polishing tool of FIG. 14 ;
- FIG. 17 is a second perspective view of the polishing tool of FIG. 14 , taken from the plate side of the polishing tool;
- FIG. 18A is a cross-sectional elevation view of the polishing tool of FIG. 14 , shown disengaged with a deeply concave object to be polished;
- FIG. 18B is a cross-sectional elevation view of the polishing tool of FIG. 14 , shown engaged from a deeply concave object to be polished;
- FIG. 19 is a perspective view of a first preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished;
- FIG. 20 is a perspective view of a second preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished;
- FIG. 21 is a perspective view of a third preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished;
- FIG. 22A and FIG. 22B are schematic representations of means for engaging a polishing foil of the polishing tools of FIGS. 10-13 and FIGS. 14-18B ;
- FIG. 23A is a perspective view of a solid bladder polishing tool of the present invention depicted in an uncompressed state
- FIG. 23B is a perspective view of a solid bladder polishing tool of the present invention depicted in a compressed state
- FIG. 24 is an exploded perspective view of the solid bladder polishing tool of FIG. 23A , exploded along the axis 23 A- 23 A;
- FIG. 25A is a side cross-sectional view of a solid bladder polishing tool of the present invention depicted in an uncompressed state, with the polishing foil absent;
- FIG. 25B is a side cross-sectional view of a solid bladder polishing tool of the present invention depicted in an compressed state, with the polishing foil absent;
- FIG. 26A is a side view of a solid bladder polishing tool of the present invention depicted in an uncompressed state.
- FIG. 26B is a side view of a solid bladder polishing tool of the present invention depicted in an compressed state.
- figure error is the measured global deviation from the desired surface shape e.g., a sphere, asphere or polynomial geometric shape.
- form error is a low frequency error.
- irregularity and power are the two specifications that need to be considered.
- Irregularity is the deviation from a perfect surface.
- Power is the resulting average surface dimensions e.g., radius of curvature.
- zonal enhancement is meant to indicate a correction of the figure error, which is located symmetrically or asymmetrically at one specific location (zone) on the work piece. For example, if a cylindrical disc was the workpiece, a zonal error would be in one sector of the disc, or in a specific band or ring on the disc, or other rotationally symmetrical part.
- the terms spot, high, mid- and low spatial frequencies in reference to errors in a surface to be polished are meant to indicate the following.
- Low spatial frequencies are errors that appear only once to a few times across a particular surface.
- Mid-spatial frequencies are errors that occur many times across a surface of a part, generally have a periodic spacing of between 80 microns and 3 mm, and are typically caused by cutter marks due to machine or tool vibrations.
- High spatial frequencies are errors that happen on a microscopic scale, which may appear thousands of times across the surface of a part, and have a periodic spacing of less than 80 microns.
- polishing when used in reference to a workpiece to be finished, is meant to indicate a chemo/mechanical process that ablates material from a surface.
- correction of form or form error modification correction, when used in reference to a workpiece to be finished, is meant to indicate the same as has been defined for figure error.
- figure when used in reference to a workpiece to be finished, is meant to indicate polishing in a correction for error in the figure and or form, which are the same.
- the term surface roughness when used in reference to a workpiece to be finished, is meant to indicate high frequency errors, which are typically the result of brittle fracture regime (e.g.microcracks).
- FIG. 1 is a schematic representation of one preferred polishing apparatus of the present invention.
- polishing apparatus 100 is configured for polishing convex spheres, aspheres, shallow concave spheres, or other conformal shapes.
- Polishing apparatus 100 comprises a base 102 that supports Y-axis linear slide 104 , the motion of which is bi-directional along Y-axis 105 (directed perpendicular to the plane of FIG. 1 ).
- Linear slide 106 the motion of which is bi-directional along X-axis 107 , is mounted upon Y-axis linear slide 104 .
- These linear slides 104 and 106 are both computer numerically controlled (CNC) positioning devices, providing programmable motion in the X-Y plane.
- CNC computer numerically controlled
- Workpiece spindle 108 is mounted upon linear slide 106 , such that the motion of spindle 108 is bidirectionally programmable along axis 109 , which is parallel to X-axis 107 . Thus spindle 108 is movable by computer control along axis 109 , depending on the requirements or the polishing process.
- Rotatable workpiece chucking device 110 is attached to end of workpiece spindle 108 .
- the workpiece 10 to be polished is engaged and held by chuck 110 and rotated by spindle 108 around the central rotary axis thereof.
- Apparatus 100 further comprises vertical slide 120 attached to polishing machine column 122 , which is joined to base 102 .
- the motion of vertical slide 120 is bi-directional along Z-axis 121 .
- Polishing tool spindle 124 is attached to the Z-axis slide 120 .
- the rotational speed (RPM) of this spindle is varied by the computer depending on the desired removal rate of material from workpiece 10 .
- Apparatus 100 further comprises a rotatable chucking device 126 attached to the end of polishing tool spindle 124 , in which polishing tool 128 of the present invention is inserted and rotated.
- Polishing tool 128 is provided in a variety of shapes, sizes, and materials (e.g. see polishing tool 200 of FIG. 2A and 2B ), as will be described subsequently in this specification.
- apparatus 100 further comprises a fluid delivery system 130 for delivery of a homogeneous liquid or a liquid slurry.
- delivery system 130 delivers a liquid containing finely divided solid particles, and as such is considered a slurry, a suspension, or a particulate dispersion.
- particles are preferably abrasive polishing particles with a hardness sufficient to wear a typical optical material such as e.g. glass.
- Such particles may comprise e.g., silica, alumina, ceria, diamond, and the like, and mixtures thereof.
- Many other hard, abrasive particulate materials such as e.g., carbides, nitrides, etc. will be apparent to those skilled in the art.
- delivery system 130 delivers a homogeneous liquid substantially free of solid particles.
- Suitable liquids may be e.g. water, water soluble oils or lubricants (such as e.g. glycerine), hydrocarbon oils, silicone oils, and the like. The selection of a particular homogeneous liquid or a particulate slurry will depend upon the particular optical part being polished, and upon the desired end results.
- slurry or fluid delivery system 130 comprises a reservoir (not shown), a slurry/fluid mixer 132 , and a slurry/fluid pump 134 .
- Slurry/fluid delivery system 130 is used to supply an abrasive slurry/fluid (not shown), which is delivered through conduit 136 and directed by nozzle 138 upon the polishing tool 128 and workpiece 110 , at the area of contact there between.
- FIG. 2A is a cross-sectional view of one preferred polishing tool of the present invention used in apparatus 100 of FIG. 1 , according to the methods of the present invention.
- polishing tool 200 comprises a main body or bladder mandrel 202 having a shank 201 at a proximal end 224 thereof, and a flange 211 at a distal end thereof, around which a bladder 204 is disposed and sealably engaged therewith.
- Compression washers 206 and 207 are disposed on both sides of bladder 204 , and are held in place by locking nuts 208 and 209 , respectively.
- Nuts 208 and 209 and washers 206 and 207 provide sealing means in that nuts 208 and 209 and washers 206 and 207 hold bladder 204 tightly against flange 211 of mandrel 202 .
- lips 246 and 248 of bladder 204 are disposed and held firmly in grooves 242 and 244 of mandrel 202 , so that bladder 204 is sealed to mandrel 202 .
- End 210 of mandrel 202 has an axial bore 212 disposed therein, which is connected to at least one radial bore 214 , or preferably a plurality of radial bores 214 extending to a cavity 216 disposed in the perimeter 218 of mandrel 202 .
- Such axial bore 212 and radial bores 214 form a continuous passageway such that cavity 216 is in communication with the atmosphere outside of tool 200 .
- axial bore 212 and radial bores 214 allow the cavity 216 to be filled and pressurized with a fluid delivered through inflation device 220 , which is disposed and sealed in axial bore 212 at the end 210 of mandrel 202 .
- Polishing tool 200 further comprises a ring assembly 230 of polishing material disposed around the outer perimeter of bladder 204 .
- FIG. 3 is a cross-sectional view of one preferred embodiment of a polishing ring disposed upon the polishing tool of FIG. 2A .
- ring assembly 230 is a dual ring assembly comprising a backer ring 232 of material, over which is disposed abrasive ring 234 comprised of a polishing medium adhered thereto. The resulting polishing ring assembly 230 is disposed around the perimeter of and contiguous with bladder 204 .
- backer ring 232 consists essentially of a band of poly(ethylene terephthalate) having a thickness of between about 50 microns and about 1000 microns, and a width of between about 2 millimeters and about 30 millimeters.
- Abrasive ring 234 is made of a material of sufficient structural strength to withstand the high shear and tensile forces during polishing, and to resist degradation through exposure to the polishing/lubricating fluid, such as e.g. polyurethanes of various durometers; and various types of felt, cork, and metal and/or resin bond diamond, alumina, and/or zirconium, with a multitude of different types of backings and patterns therein.
- Abrasive ring 234 preferably has a thickness of between about 1 millimeter and about 5 millimeters, and a width of between about 2 millimeters and about 30 millimeters.
- FIG. 4 is a cross-sectional view of another preferred embodiment of a polishing ring disposed upon the polishing tool of FIG. 2A .
- ring 230 simply comprises a single ring 236 of polishing material disposed around the perimeter of bladder 204 .
- the embodiment of FIG. 4 is used when ring 236 is of sufficient structural strength so as to be able to perform the particular polishing process without the use of a supporting ring disposed contiguously with such ring, as was depicted in FIG. 3 .
- single ring 236 consists essentially of polyurethane, and has a thickness of between about 1 millimeter and about 5 millimeters, and a width of between about 2 millimeters and about 30 millimeters.
- FIG. 2B is a side elevation view of the polishing tool of FIG. 2A , in the process of polishing a convex lens.
- polishing ring assembly 230 also known as the foil
- polishing tool 200 comprising polishing ring assembly 230 is rotated and engaged with lens 10 such that polishing ring assembly 230 provides a shearing and polishing action upon the surface of lens 10 . It will be apparent that the pressure that is applied to bladder 204 will determine the curvature and firmness of the outer surface of polishing ring assembly 230 during a polishing operation.
- bladder 204 has a shape and cross sectional profile that is substantially similar to that of a tire.
- Bladder 204 is preferably made of a compliant, flexible elastic material that is wrapped or attached at its periphery to the perimeter 218 of mandrel 202 .
- Suitable materials for bladder 204 are e.g., natural or synthetic rubber, silicone, or polyurethane, with a wall thickness of approximately 1 millimeter.
- the tire-shaped bladder 204 may have a variety of specific cross sectional shapes.
- polishing foil 203 is disposed around or applied to the bladder tool to act as the polishing medium.
- polishing foil 230 is made of polyurethane, and the abrasive polishing medium is provided in a liquid slurry that is pumped onto workpiece 10 and polishing foil 230 , as described previously.
- abrasive particles may be embedded in the polishing foil. Suitable abrasive particles include particles made by the Rhodes Corporation, or by the Minnesota Mining and Manufacturing Company (3M).
- abrasive particles in the shape of miniature pyramids of polishing medium such as e.g., alumina in varying grit sizes is used.
- polishing medium such as e.g., alumina in varying grit sizes
- foil 230 comprises a backer ring of poly(ethylene terephthalate) (PET) or similar material to allow softer polishing ring media to be used without tearing or pulling apart, yet maintaining the flexibility required for fine polishing.
- Bladder 204 of tool 200 is then inflated to a specific pressure depending on the polishing results desired.
- foil 230 is held in position upon bladder 204 by the expansion pressure of the bladder 204 being inflated; thus no adhesive or mechanism is required to bond foil 230 to bladder 204 .
- PET poly(ethylene terephthalate)
- the fluid may be selected so as to beneficially affect the polishing process.
- air is used as the bladder inflation fluid.
- a much more dense fluid i.e. a liquid, such as water is used as the bladder inflation fluid.
- the effective pressure of the outer wall of the bladder is a function of not only the inflation pressure, but also the rotational speed.
- Such rotational speed provides an additional pressure component due to the centrifugal force exerted by the fluid, in proportion to the square of the rotational speed.
- Such pressure is analogous to the pressure at the base of a column of liquid acted upon by gravity.
- a viscous liquid such as a hydraulic oil is used as a bladder inflation fluid.
- the viscosity of such a viscous liquid is preferably between about 10 centipoise and about 100,000 centipoise, and more preferably between about 20 centipoise and about 1000 centipoise.
- the higher viscosity of such fluid also affects the accuracy and removal rates of the polishing process, because at the contact area of the bladder with the workpiece, the bladder is deformed; hence the fluid disposed within the bladder must undergo viscous flow in this region.
- a higher viscosity fluid has a greater resistance to deformation, and also being non compressible and thus can provide a beneficial polishing effect.
- a viscous fluid provides vibration damping to the process, thereby rendering such process more precise, stable, and reliable.
- non-Newtonian fluids are used such as. e.g. a shear thinning fluid, or a shear thickening fluid.
- fluids for which the rheology may be varied by exposure to an electric or magnetic field may be used.
- inflation device 220 is a simple, inexpensive check valve.
- inflation device is a valve stem, commonly used for the inflation of tubeless tires.
- axial bore 212 is sealed, and mandrel 202 of tool 200 is provided with a second axial bore 222 disposed through the opposite end 224 of mandrel 202 .
- axial bore 212 is supplied with pressurized fluid from a fluid supply means (not shown) in real time during the polishing process.
- fluid supply means is commonly used as a coolant supply to a machine tool and is well known in the art of machine tools.
- the pressure within bladder 204 may be varied and/or pulsated during the polishing process, by the delivery or withdrawal of bladder inflation fluid as indicated by arrow 225 .
- machine tool many multi-axis CNC machine tools are known in the art, which can be suitably configured to use the polishing tool and the methods of the present invention.
- the particular configuration of machine tool will depend upon the material properties, size, and shape of the starting blank and the desired finished end product.
- the present invention is not limited only to the use of the machine tools described herein.
- such a machine tool could comprise from between two computer controlled axes up to as many as five or six computer controlled linear and/or rotary axes.
- polishing tool 200 and workpiece 10 to be polished are typically inserted into separate spindles 124 and 108 of a multi-axis CNC machine tool.
- Machine tool apparatus 100 could have a configuration as shown in FIG. 1 , or a configuration similar to that of a lathe, mill or some other customized arrangement of the axes, depending upon the part to be polished.
- Work piece spindle 108 may also be programmed to maintain constant surface speed and also to do zonal enhancements that are especially necessary when there are axial asymmetries in the part. It is to be understood that many different machine variations are possible, and that axes and spindles can be configured in a multitude of combinations/permutations to suit any workpiece shape that needs to be polished.
- the configuration of the different machine axes and spindles can be in any order as required to enable actuation of the polishing tool over the surface of the workpiece to be polished. Accordingly, all such configurations are to be considered within the scope of the present invention.
- the polishing slurry/fluid suspension is fed between the polishing tool 200 and the work piece 10 by slurry delivery system 130 .
- the axis traverse feedrates i.e. the velocities of the linear slides
- the workpiece rotational speed in revolutions per minute (RPM) and tool spindle rotational speed in RPM are adjusted via automated computer control.
- the pressure (and thus the “firmness”) of bladder 204 of polishing tool 200 is preset, and maintained constant during the polishing operation.
- a specific pretest is performed in order to characterize the polishing spot profile.
- spot profile is meant to indicate the indentation resulting from contacting a test workpiece with polishing tool 200 or 300 by moving the otherwise stationary test workpiece into contact with the polishing tool 200 or 300 , thus leaving a depression, indentation, or “footprint” in the part the test is performed in a standard manner, with the workpiece moved against the tool with a specified displacement for a specified period of time. The resulting volume of the indentation per unit time period it the material removal rate.
- the shape and size of the area produced when the polishing tool is pressed into the test piece for a given period of time is the spot profile.
- This spot profile is then used in the generation of the time dependent trajectory of the polishing tool over the surface of the workpiece that is required to achieve the desired polishing results.
- This time dependent trajectory is also known in the art as the tool path and dwell times used in polishing.
- the profile characterized, high, mid and low spatial features can be greatly improved through adjustments of the polishing variables, tool rpm, workpiece rpm, axes feedrates, and compression factor.
- the term compression factor is meant to indicate the compressive force applied by the polishing tool against the workpiece, such force being the combination of force due to bladder pressure, and force due to the trajectory of the tool against the workpiece.
- the work piece spindle 108 holds workpiece 10 , i.e. the optic or other part to be finished.
- Work piece spindle 108 , and/or polishing spindle 124 as described are attached to computer controlled linear or rotary slides 104 , 106 , 108 , and 120 so that any path or desired motion and dwell times of the polishing tool 200 over the workpiece 10 can be achieved.
- workpiece spindle 108 also acts as a servo controlled positioning axis, the motion of which may be controlled in coordination with the described linear and rotary motions such that any non-axially symmetric irregularities, zonal enhancements, in the workpiece 10 may be also corrected with the polishing method of the present invention.
- Polishing tool spindle 124 is controlled via a motor and spindle drive (not shown) such that the rotation speed in RPM is variable, and may be adjusted during the polishing process, depending on the process and workpiece requirements.
- the pre-machined (i.e. unfinished) workpiece may be measured with a surface profilometer, an interferometer, a CMM or any other type of measuring device capable of analyzing the geometric shape, in order to quantitatively define the basic starting condition of the workpiece.
- This information is required to begin the process of improving the components surface roughness, mid-spatial frequency (waviness) and figure.
- the acquired data on the workpiece is then communicated into the computer control on the machine. This information, along with the software built into the computer control, calculates the process parameters/motion control required giving the desired workpiece improvements.
- the polishing tool spot size and shape is either known based on a library of predetermined empirical parameters obtained experimentally, or it is analyzed through a series of tests.
- the polishing tool spot size and shape is then sent to the CNC controller. This data is the additional information needed to develop the required polishing tool path motion and speed, and spindle rotational and linear speeds to achieve the desired process results. It is to be understood that the polishing spot size may be affected by the size, shape, material properties, and fill pressure of the bladder, fluid type of the filled bladder, and the polishing foil material properties.
- FIG. 5 is a flowchart depicting a method of assembly of the preferred polishing tool of FIG. 2A in the apparatus of FIG. 1 .
- tool setup process 410 begins with step 412 , wherein polishing tool 200 sans polishing ring assembly 230 is fitted in holding chuck 126 of spindle 124 .
- polishing ring assembly or foil 230 is selected and fitted to bladder 204 of polishing tool 200 .
- Bladder 204 is inflated to hold polishing ring assembly 230 in place thereupon in step 416 .
- a measurement of the center height of polishing ring 230 is made with suitable measuring means such as e.g., a dial indicator, a caliper, a micrometer, and the like in step 418 .
- suitable measuring means such as e.g., a dial indicator, a caliper, a micrometer, and the like.
- tool setup process 410 is complete.
- an alignment fixture may be used to aid in proper position/alignment of the foil and or reinforcement ring
- FIG. 6 is a flowchart depicting a method of preparing the preferred apparatus of FIG. 1 for a polishing operation.
- apparatus or machine setup process 420 begins with step 422 , installing the completed polishing tool assembly 200 in chuck 126 of spindle 124 .
- Step 422 is performed in the event that tool 200 was removed from spindle 124 in order to make the measurement 418 of tool setup process 410 of FIG. 5 , or if tool 200 was setup separately from machine 100 .
- Machine setup process 420 continues with step 424 , in which the polishing tool dimensional data obtained in measurement step 418 is entered into the CNC process controller of machine 100 .
- the unfinished optic or other workpiece to be polished is then placed into holding chuck 110 of spindle 108 in step 426 .
- the data obtained from measurements made on the unfinished optic that have been described previously are also entered into machine 100 in step 428 .
- step 430 an analysis of the spot size/removal function of the polisher on the optic is performed, or such data from a previously described library of tool functions is entered into the CNC process controller.
- the CNC process controller is further programmed with polishing tool and polishing medium parametric data such as removal function, polishing spot size, polishing tool medium/material type, polishing tool dimensions/shape, polishing tool bladder pressure, optic/workpiece starting and finished dimensions, and polishing slurry type/composition.
- polishing tool and polishing medium parametric data such as removal function, polishing spot size, polishing tool medium/material type, polishing tool dimensions/shape, polishing tool bladder pressure, optic/workpiece starting and finished dimensions, and polishing slurry type/composition.
- the deterministic path of the polishing tool 200 on the optic 10 is calculated by such controller in step 434 .
- coordinate offsets will be established in all of the programmable axes 104 , 106 , 108 , and 120 , so as to provide the CNC controller of machine 100 the information/location of part 100 such machine 100 will begin the polishing process at the correct location on workpiece 10 .
- some test probing of the workpiece 10 and/or the polishing tool 200 may be implemented to confirm that such starting location is correct.
- FIG. 7 is a flowchart of a complete method of polishing an optic using the apparatus and polishing tool of the present invention.
- tool setup process 410 and machine setup process 420 are performed according to the foregoing descriptions of FIG. 5 and FIG. 6 .
- the optic polishing cycle is performed, wherein a computer developed path of polishing tool 200 upon workpiece 10 is performed.
- the workpiece spindle 108 and polisher spindle 124 are placed in rotary and linear motion along one or more of axes 105 , 107 , 109 , and 121 , depending on the desired results.
- the part may not be attached to a rotating spindle and may be held in a stationary position, while polishing tool is actuated over the surface thereof.
- machine 100 is provided with automatic tool changers, to change between multiple polishing tools during the process.
- multiple spindles are provided on machine 100 , wherein a first polishing tool on a first spindle performs part of the polishing operation, a second polishing tool on a second spindle performs part of the polishing operation, and so forth, to the extent that multiple tools and spindles are provided on machine 100 .
- polishing cycle 440 at such time when the spindles 108 and 124 have started, but before any motion of tool 200 along axes 105 , 107 , 109 , and 121 , there is provided and injection or pumping of a specific polishing slurry or other fluid at the contact location of polishing tool 200 with workpiece 10 , which enhances the polishing action or removal rates of material from workpiece 10 .
- the path of the polishing tool 200 over the workpiece 10 may include straight, linear, arcuate zigzag, sinusoidal, rotary, spiral, or other programmable motions so as to enhance the removal rate of material from workpiece 10 .
- polishing cycle 440 Upon completion of polishing cycle 440 , the machine 100 of FIG. 1 is stopped. Referring again to FIG. 7 , and continuing again with process 400 , the profile of the polished optic or other workpiece is measured in step 450 , according to methods previously described. A decision is made at step 455 , wherein if the optic 10 is acceptable against specifications, it proceeds through a step 490 of final measurement/quality control, and/or packaging, and shipping.
- steps are taken to prepare for another polishing cycle 440 .
- Such steps include step 460 , reprogramming of the CNC controller; optional step 470 of setting up/installing/and/or changing to a new polishing tool; and step 480 , calculation of a new deterministic path for the next polishing cycle 440 .
- the second polishing cycle then proceeds as previously described, and further iterations of steps 450 - 480 and 440 occur until the optic is polished to a condition that is acceptable against specifications, at which time step 490 is performed.
- polishing tool 300 comprises a mandrel 302 within which is disposed a groove 303 around the outer periphery of a flange 305 formed at one end of mandrel 302 .
- Tool 300 further comprises a dome-shaped bladder 304 , having a lip 307 that is disposed in groove 303 of mandrel 302 .
- Compression washer 306 is fitter over the shank 301 of mandrel 302 and disposed against lip 305 of bladder 304 .
- Locking nut 308 is threadedly engaged with a corresponding threaded portion of shank 301 , such that locking nut 308 compresses lip 305 of bladder 304 into groove 303 of mandrel 302 , thereby sealing bladder 304 to mandrel 302 .
- Bladder 304 sealed to flange 305 of mandrel 302 thus forms a cavity 316 therebetween.
- Suitable materials for bladder 304 are e.g., natural or synthetic rubber, silicone, or polyurethane.
- bladder 304 is formed such that bladder 304 fully encloses the outer surface 309 of the distal end of mandrel 302 .
- bladder 304 is conical, as indicated by dotted lines 311 .
- bladder 304 may have a parabolic shape, a hyperbolic shape, or combinations and transitions between hemispherical, conical (linear), hyperbolic, and parabolic surfaces at different radial zones along the surface of bladder 304 .
- bladder 304 may have a precisely hemispherical shape, a precisely conical shape, or a generally curved or domed shape formed by some combination of these various surface definitions. It will be apparent that even in the instance of a conically shaped bladder 304 , that such bladder will likely be formed with a slight radius at the apex of such cone.
- Mandrel 302 is further provided with an axial bore 312 disposed from the outer end 324 of shank 301 through the center of flange 305 , such that the outer end 324 of mandrel 302 is in communication with cavity 316 .
- Polishing tool 300 further comprises an inflation device 320 such as e.g., a check valve, or a tire valve stem, for providing a means to pressurize cavity 316 and maintain pressure therein, as previously described for tool 200 of FIG. 2A .
- Cavity 316 may be pressurized with any suitable fluid such as the liquids or gases previously described in this specification.
- axial bore 312 is connected during the polishing process to an adjustable pressure source, so that the pressure within cavity 316 may be varied in real time during the polishing operation, as described previously in this specification.
- polishing tool 300 further comprises a first ring or dome 332 of backing material disposed over the outer wall of bladder 304 , and a second ring or dome 334 of polishing material adhered to dome 332 , thereby forming a dual or composite ring or dome.
- polishing tool is thus used in substantially the same manner as described for polishing tool 200 of FIG. 2A previously in this specification, with polishing tool 300 being the preferred tool for the polishing of concave surfaces.
- FIG. 8B is a side elevation view of the polishing tool of FIG. 8A , in the process of polishing a concave lens.
- the axis of rotation of polishing tool 300 is preferably disposed at an obtuse angle 50 with respect to the axis of rotation of concave lens 20 , in order to achieve the desired contact between polishing surface 334 of toll 300 and concave surface 22 of lens 20 .
- FIG. 9 is a schematic representation of another preferred polishing apparatus for polishing concave spheres, aspheres, convex spheres, or other conformal shapes, such as lens 20 of FIG. 8B .
- apparatus 150 is in one embodiment substantially similar to apparatus 100 of FIG. 1 , with the main difference being provisions to contact the polishing tool with the concave surface of the workpiece.
- the first preferred provision is the use of tool 300 of FIG. 8A , having a hemispherical, domed, or conical shape.
- a second preferred provision is in apparatus 150 wherein a B axis 152 directed into/out of the plane of FIG.
- polishing tool spindle 124 is mounted, and upon which polishing tool spindle 124 is bidirectionally rotatable, as indicated by arcuate arrow 154 .
- Such a provision enables polishing tool 300 to be moved as indicated by arcuate arrow 156 into a position wherein the axis of rotation of polishing tool 300 is disposed at an obtuse angle 50 with respect to the axis of rotation of concave workpiece 20 , as indicated in FIG. 8B .
- Such motion enables the polishing foil 334 of polishing tool 300 to contact the concave surface of a workpiece such as a concave lens or an asphere without having another portion of the polishing tool colliding with such workpiece.
- the machine 100 of FIG. 1 , and the machine 150 of FIG. 9 that are provided to execute process 400 of FIG. 7 , using tools 200 of FIG. 2A and tool 300 of FIG. 8A may have many different configurations. Axes types, spindle types, layout, size, provision of an automatic tool changer, and overall cost are just a few of the variables that could affect the desired design. While only show two specific possible machine configurations and specific possible tooling configurations are described in this specification and shown in FIGS. 1 and 9 , it is to be further understood that many multi-axis CNC machine tools are known in the art, which can be suitably configured to use the polishing tools 200 and 300 and the process 400 of the present invention.
- the overall computerized polishing process 400 using the apparatus 100 and polishing tool 200 of the present invention has many distinct advantages over prior art figure/polishing enhancement techniques, which are as follows:
- the polishing tool further comprises actuation means to engage and/or extend and/or position and/or compress the inflatable bladder or other compliant part, and any polishing foil disposed thereupon, with respect to the part to be improved or polished.
- actuation means may comprise one or more linear actuating devices such as e.g., air operated or hydraulically operated cylinders.
- FIG. 10 is a first perspective view of one such preferred polishing tool of the present invention comprising single cylinder actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished.
- FIG. 11 is a side elevation view of the polishing tool of FIG. 10 ;
- FIG. 12 is a top view of the polishing tool of FIG. 10 ;
- FIG. 13 is a second perspective view of the polishing tool of FIG. 10 , taken from the plate side of the polishing tool.
- polishing tool 500 comprises a base 502 to which various components are affixed.
- base 502 comprises a rigid plate of material such as steel, aluminum, or fiber reinforced polymer.
- Other base materials and or structures, such as a frame structure may be suitable, with the operative requirement being that the base is rigid enough to hold components attached thereto in sufficiently precise dimensional relationships so as to enable the overall precision polishing operation to be performed; and that the base is provided with provisions to enable the attachment of components thereto.
- drive wheel 510 is operatively joined or attached to rotatable shaft 512 , which is disposed in a housing 514 joined to base 502 .
- Housing 514 is preferably joined to base 502 by threaded fasteners (not shown) engaged with tapped holes (not shown) therein, or by other suitable means.
- Rotatable shaft 512 is preferably disposed within means for enabling precise rotation, such as e.g., a bushing, or more preferably, bearings 516 .
- Tool 500 further comprises a polishing wheel 520 , which is joined to linkage 530 .
- Linkage 530 is operatively attached to actuating means 540 , such that actuating means 540 actuates linkage 530 , and thus moves polishing wheel 520 , as indicated by bidirectional arrow 599 .
- This motion of polishing wheel 520 serves to engage a polishing foil with a portion of the perimeters of polishing wheel 520 and drive wheel 510 ; such engagement will be described subsequently in this specification.
- actuating means 540 is a linear actuator, and in particular, actuating means 540 a pressure driven cylinder 542 .
- Linkage 530 in this embodiment is a clevis 532 that is operatively joined to cylinder rod 544 .
- Polishing wheel 520 is joined to clevis 532 by shoulder bolt 534 , which passes through a hole in the center of wheel 520 , and engages with nut 536 .
- the position of wheel 520 is preferably maintained constant within clevis 532 by the use of spacing washers 535 and 537 .
- polishing wheel 520 is provided with at least one bushing or bearing to minimize wear, friction and heat buildup, and to provide precise positional control in the event that polishing wheel is operated at high speeds.
- cylinder 542 is joined to base 502 at its proximal end by a shoulder bolt 547 , which passes through bracket 543 , and which is engaged with threaded hole 508 in base 502 .
- Cylinder 542 is properly spaced out from base 502 by the use of jig bushing 546 , through which bolt 547 also passes.
- Cylinder 542 is further joined to base 502 at its distal end by mounting nut 548 , which is threadedly engaged with the housing 545 of cylinder 542 , and also engaged with bracket 550 .
- Bracket 550 is fastened to the distal end 506 of base 502 by threaded fasteners 552 and 554 , which are engaged with tapped holes therein.
- Cylinder 542 is thus rigidly secured to base 502 , and thus in the operation of the tool 500 (to be described subsequently in this specification), cylinder 542 linearly actuates polishing wheel 520 as indicated by bidirectional arrow 599 .
- cylinder 542 is operatively connected to a pressurized fluid supply at ports 556 and 558 in the housing 545 thereof, preferably provided through flexible hoses (not shown).
- fluid supply is selectable and switchable, i.e. fluid pressure may be applied at port 556 and fluid vacuum may be applied at port 558 to actuate wheel 520 away from distal end 506 of base 502 and toward the work piece 112 (see FIG.
- pressurized fluid supply may provide a pressurized gas such as air (i.e. cylinder 542 is an air cylinder), or pressurized fluid supply may provide a pressurized liquid such as a hydraulic oil (i.e. cylinder 542 is a hydraulic cylinder).
- actuating means 540 may comprise suitable linear actuators other than fluid pressure driven cylinders; many other linear actuators, such as rodless cylinders, stepper motors and other electromechanical actuators are well known and are to be considered within the scope of the present invention. Such linear actuators may be further provided with position sensing means, and/or position control means, and communication means for control thereof by an external process controller.
- Tool 500 further comprises a polishing foil 680 (see FIG. 14 ), which is engaged with a portion of the perimeters of drive wheel 510 and polishing wheel 520 .
- Polishing foil 680 thus has the function of a drive belt, rotationally coupling drive wheel 510 and polishing wheel 520 as indicated by arrows 598 and 597 . (It will be apparent that the rotational direction could be the opposite of that depicted by arrows 598 and 597 .)
- polishing foil 680 is not shown in FIGS. 10-13 .
- Polishing foil 680 is shown in FIGS. 14-18B in the two-cylinder embodiment depicted therein.
- Polishing foil 680 is also shown in FIGS. 22A and 22B , for the purpose of illustrating the manner of engagement thereof with drive wheel 510 and polishing wheel 520 , and for illustrating the preferred properties of polishing foil 680 .
- FIG. 22A and FIG. 22B are schematic representations of means for engaging a polishing foil of the polishing tool 500 of FIGS. 10-13 .
- FIG. 22A depicts such engagement means in the retracted, or unengaged position
- FIG. 22B depicts such engagement means in the deployed, or engaged position. It is to be understood that the following description is also applicable to the polishing tool 600 of FIGS. 14-18B .
- polishing foil 680 comprises an assembly similar to that described for ring assembly 230 of tool 200 of FIGS. 2A, 2B , 3 , and 4 , having a belt 682 of material and an abrasive ring 684 .
- Belt 682 is formed of an elastic material.
- belt 682 consists essentially of a band of poly(ethylene terephthalate) having a thickness of between about 50 microns and about 2000 microns, and a width of between about 7 millimeters and about 125 millimeters.
- belt 682 consists essentially of elastomers such as e.g., gum rubbers, polyurethane, silicone and the like.
- elastomers such as e.g., gum rubbers, polyurethane, silicone and the like.
- Many other belt materials may be suitable, with the operative requirement being that belt 682 have sufficient elasticity to stretch when rod 544 of cylinder 542 is deployed as shown in FIG. 22B , and that the outer surface of belt 682 is engageable with the inner surface of abrasive ring 684 , either by friction, or by engagement features in the surfaces thereof, or by other means.
- the abrasive ring 684 of foil 680 is made of a material of sufficient structural strength to withstand the high shear and tensile forces during polishing, and to resist degradation through exposure to the polishing/lubricating fluid, such as e.g. polyurethanes of various durometers; water resistant high strength cloth materials, and various types of felt, cork, and metal.
- Abrasive ring 684 further comprises abrasive particles embedded therein, or coated on the outer surface thereof, such as e.g. resin bonded diamond, alumina, and/or zirconium and the like.
- Abrasive ring 684 may have an inner surface having different types of backings, and/or patterns for engagement with belt 682 .
- Abrasive ring 684 preferably has a thickness of between about 1 millimeter and about 5 millimeters, and a width of between about 7 millimeters and about 125 millimeters. Additional operative requirements of abrasive ring 684 are that it have a greater circumference than belt 682 , and that it is substantially inelastic, or significantly less elastic than belt 682 , in order to enable proper engagement therewith.
- belt 682 has been stretched at least slightly, and has been fitted such that belt 682 is engaged with portions of the perimeters of drive wheel 510 and polishing wheel 520 .
- Belt 682 is thus under some tension, and when drive wheel 510 rotates as indicated by arrow 597 , belt 682 is displaced as indicated by arrows 594 , thereby resulting in rotation of polishing wheel 520 as indicated by arrow 598 .
- abrasive ring 684 is not engaged with belt 682 , as indicated by gap 683 that is present between belt 682 and ring 684 .
- FIG. 22B when the rod 544 of cylinder 542 is deployed, polishing wheel 520 is displaced away from cylinder 542 .
- Belt 682 being of an elastic material, stretches to the extent required to accommodate such displacement of wheel 520 .
- Abrasive ring 684 is of a relatively inelastic material compared to belt 682 , has not stretched, and has instead become engaged with belt 682 by friction, and/or by engagement features disposed on the contiguous surfaces thereof.
- polishing foil 680 may be formed as a unitary structure in a manner similar to ring 230 of FIG. 4 as described previously, but having both the required properties of a drive belt for engagement with wheels or pulleys, and an abrasive belt for polishing or more substantial surface removal, as well as having the requisite elastic properties as previously described.
- the applicant believes that the belt and ring structure is preferred, as such components are more easily and inexpensively provided, and such structure enables simple and rapid changeover between belts comprised of various abrasive media, either manually, or by automatic tool changing means.
- polishing foil 680 may be provided with features known in drive belt art, such as grooves (not shown) on the inner surface thereof (mated with corresponding grooves in wheels 510 and 520 ); or teeth (not shown) on the inner surface thereof (mated with corresponding teeth in wheels 510 and 520 as is done with timing belts and pulleys); or knurling or other textures on the inner surface thereof.
- Drive wheel 520 may further be provided with rims extending radially outward from the edges thereof for improved belt retention, as is commonly done with drive pulleys.
- Polishing foil 680 may vary in length from about 4 inches for tools having pulleys on the order of 0.25-0.5 inches in diameter to about 50 inches for tools having pulleys on the order of 8 inches in diameter.
- the rotational speed of drive wheel 510 is provided such that the surface speed of polishing foil 680 is between about 2 and about 1000 inches per second, depending upon the particular polishing application.
- Polishing foil 680 may further comprise fiber reinforcements disposed therein, and may comprise woven or cloth-like material, provided that sufficient elasticity is provided as described herein.
- tool 500 further comprises a dowel pin 559 extending outwardly from and joined to base 502 by engagement with a threaded hole therein, or by an interference fit with a hole therein, or by other suitable means such as e.g. welding or adhesive.
- Dowel pin 559 is utilized to attach and/or stabilize tool 500 when it is engaged with drive means such as a CNC machine and used to polish an object. The details of such use will be described subsequently in this specification with reference to FIGS. 19-21 .
- Tool 500 is preferably used in a multi-axis CNC apparatus for the polishing of objects; however, tool 500 may be engaged with a variety of more simple or more complex drive means, and used for many other surface polishing or surface abrasion applications. In one embodiment, tool 500 may simply be provided with an air motor or electric motor attached thereto as drive means, and placed in contact with the object to be worked.
- tool 500 may be fabricated at a variety of scales, depending upon the particular application, and in particular, the size, shape, and degree of finishing required of the part to be worked.
- the diameters of drive wheel 510 and polishing wheel 520 may vary from about 0.25 inches to about 8 inches.
- the scale of the other components, i.e. base 502 , cylinder 542 , and linkage 530 would be sized as required to operate drive wheel 510 and polishing wheel 520 and the foil 680 engaged therewith.
- cylinder 542 may be provided with a bore of between about 0.1 inch and about three inches.
- polishing wheel 520 Although it appears in the embodiment shown in FIGS. 10-13 that the diameters of drive wheel 510 and polishing wheel 520 are approximately equal, this is not an operating requirement. To the contrary, in some applications, it is advantageous to either increase the rotational speed of polishing wheel 520 or decrease the speed of polishing wheel 520 with respect to drive wheel 510 , by providing polishing wheel 520 with a different diameter than drive wheel 510 .
- the ratio of polishing wheel diameter to drive wheel diameter may vary from as much as about 1:10 to about 10:1, depending upon the application.
- Polishing foil 680 may vary in width from about 0.25 to about 5 inches. The corresponding widths of drive wheel 510 and polishing wheel 520 thus vary in a similar manner in order to properly engage with and drive polishing foil 680 .
- the length of actuation stroke of means 540 may vary from about 0.1 inch to about 3 inches, depending upon the scale of tool 500 , and upon the degree of elasticity provided in polishing foil 680 .
- polishing wheel 520 is preferably provided with a generally arcuate surface 521 , and more preferably a spherical surface.
- Polishing foil 680 which is under tension from the action of actuation means 540 , conforms to this surface 521 as it wraps around the perimeter of polishing wheel 520 during a polishing operation. This wrapping action results in better tracking of polishing foil 680 on polishing wheel 520 .
- the radius of curvature and/or the curvature profile (spherical, elliptical, hyperbolic, etc.) of arcuate surface 521 partially determines the tool spot size during a polishing operation. Tool spot size has been described previously in this specification.
- wheel 520 is provided with a cavity 522 formed within the interior thereof, and a passageway 524 from the exterior of wheel 520 to cavity 522 .
- Cavity 522 may thus be pressurized with various fluids during a polishing operation, as described previously in this specification with reference to tool 200 of FIGS. 2 A and 2 B, and tool 300 of FIGS. 8A and 8B .
- Passageway 524 may be further provided with an inflation device, such as inflation device 220 of FIG. 2A .
- inflation device 220 is preferably a simple, inexpensive check valve.
- inflation device is a valve stem, or the inner workings thereof commonly used for the inflation of tubeless tires.
- inflation device may comprise a miniature check valve, such as one of many manufactured and sold by the Lee Company of Westbrook, Conn.
- Polishing wheel 520 may be formed of suitable elastomers such as rubber, polyurethane, or silicone, or a harder or higher durometer polymer. The selection of material for polishing wheel 520 will depend upon whether or not polishing wheel 520 is provided with a cavity therein for pressurization, the extent to which such cavity may be pressurized and thus deformed, and the desired tool spot size during the polishing operation. These variables have been described in detail in this specification with regard to tool 200 of FIGS. 2A and 2B , and are also generally applicable to polishing wheel 520 .
- polishing wheel 520 comprises a hub of solid material such as e.g.
- polishing wheel does not include a pressurizable cavity therein, and is instead a solid elastomeric material, it is preferable that such elastomeric material be of a durometer between about 10 and about 90, with the particular durometer depending upon the polishing application.
- polishing wheel may be formed with a plano (cylindrical) surface, or a convex surface.
- Polishing wheel 520 may also be formed with circumferential grooves on surface 521 , or axial grooves (such as e.g. a timing pulley), and/or a texture such as knurling. These various surfaces may be employed to improve the tracking and/or traction between polishing wheel 520 and foil 680 , thereby preventing slippage therebetween. These various surfaces may be further employed advantageously in that such surfaces may be used to cause high frequency vibrations of polishing wheel 520 and foil 680 against the part to be finished, thereby enhancing the polishing effect of tool 500 .
- FIG. 14 is a first perspective view of another preferred polishing tool of the present invention comprising twin cylinder actuation means to engage the polishing foil, and to extend and/or position the inflatable bladder or other compliant part, and the polishing foil disposed thereupon, with respect to the part to be improved or polished.
- FIG. 15 is a side elevation view of the polishing tool of FIG. 14 ;
- FIG. 16 is a top view of the polishing tool of FIG. 14 ;
- FIG. 17 is a second perspective view of the polishing tool of FIG. 14 , taken from the plate side of the polishing tool. It will be apparent that much of the structure of the embodiment depicted in FIGS. 14-17 is substantially the same as the embodiment depicted in FIGS.
- twin cylinder actuation means in the embodiment of FIGS. 14-17 . Accordingly, in the following description, only the twin cylinder actuation means will be described in detail, with the remaining structure and function of tool 600 of FIGS. 14-17 being as described for tool 500 of FIGS. 10-13 .
- tool 600 comprises base 602 , drive wheel 610 joined to shaft 612 , polishing wheel 620 , dowel pin 659 , and polishing foil 680 .
- Tool 600 further comprises actuation means 640 , which further preferably comprises a first linear actuator and a second linear actuator.
- the first linear actuator is preferably a cylinder 642
- the second linear actuator is preferably a cylinder 662 .
- First cylinder 642 is operatively connected to polishing wheel 620 by clevis 632 , and thus provides linear actuation of polishing wheel as indicated by bidirectional arrow 699 , in a manner similar to that described previously for tool 500 of FIGS. 10-13 .
- Second cylinder 662 is joined at the proximal end thereof by shoulder bolt 667 , which passes through bracket 663 and spacer 666 , and which is threadedly engaged with a tapped hole in base 602 .
- Second cylinder 662 also provides linear actuation of rod 664 and clevis 633 inwardly and outwardly from cylinder body 665 as indicated by bidirectional arrow 696 . Since cylinder 662 is rotatable about shoulder bolt 667 , this linear actuation of clevis 633 results in motion of the distal end of cylinder 642 , and clevis 632 and polishing wheel 620 along a generally arcuate path as indicated by bidirectional arrow 695 . This arcuate motion enables polishing wheel 620 and polishing foil 680 to be more effectively engaged with and compressed against the object to be polished, as will be subsequently explained with reference to FIGS. 18A and 18B .
- clevis 633 is joined to cylinder rod 664 and also to lock plate 670 by shoulder bolt 672 .
- Lock plate 670 is also joined to the body 645 of cylinder 642 , and lock plate is movably joined to base 602 by shoulder bolt 674 , which passes through slotted opening 676 in lock plate 670 .
- FIGS. 15A and 15B depicts the position of polishing wheel 620 with cylinder 662 fully retracted.
- FIG. 15B depicts the position of polishing wheel 620 with cylinder 662 fully deployed.
- lock plate 670 is displaced downwardly and outwardly resulting from the freedom of motion along slot 676 , resulting in the arcuate motion of polishing wheel 620 and foil 680 as indicated by arcuate arrow 695 . It will be apparent that many other combinations of a second linear actuator joined to a first linear actuator by a movable bracket, hinge, or other means can provide a suitable arcuate motion of polishing wheel 620 , and thus all such combinations of linear actuators are comprehended within the scope of the present invention.
- port hole 607 in plate 602 is depicted as being circular, port hole 607 may be oblong in the vertical direction, or of larger diameter. This variation in shape may be necessary because the arcuate motion of polishing wheel 620 as indicated by arrow 655 in FIG. 15B that results when cylinder 662 is deployed. This deployment and retraction of cylinder 662 causes the rod end of cylinder 642 to pivot up and down vertically as described previously.
- FIGS. 14-17 there is provided the tool of FIGS. 14-17 , but with a simple pivotable link (not shown) in place of cylinder 642 .
- a polishing foil 680 that is unitary in construction and that is elastic, such that polishing foil 680 is stretched over drive wheel 610 and polishing wheel 620 , and engaged therewith.
- first linear actuation means 640 comprising cylinder 642 is not provided.
- cylinder 642 provides the arcuate motion of polishing wheel 620 , with wheel 620 pivoting along an arcuate path defined by the rigid link (not shown) provided in lieu of cylinder 642 . (Substantially the same result could be obtained if cylinder 642 of tool 600 of FIG. 14 were locked in a fixed position, such that cylinder 642 would function as a rigid link.)
- FIG. 18A is a cross-sectional elevation view of the polishing tool of FIG. 14 , shown disengaged with a deeply concave object to be polished; and FIG. 18B is a cross-sectional elevation view of the polishing tool of FIG. 14 , shown engaged from a deeply concave object to be polished.
- FIG. 18A it can be seen that cylinder 662 is fully retracted as depicted in FIG. 15A , and that polishing wheel 620 and foil 680 are not in contact with object 112 , there being a gap 114 between the inner surface 116 of object 112 and polishing foil 680 .
- FIG. 18B it can be seen that when cylinder 662 is subsequently fully deployed as depicted in FIG. 15B , polishing wheel 620 and foil 680 move along an arcuate path and make contact with object 112 .
- the fluid pressure applied to cylinder 642 and to cylinder 662 are among the parameters that determine the amount of force applied by polishing wheel 620 and foil 680 to the object 112 , and which thus determine the tool spot size.
- Other parameters that determine such force and tool spot size are as described previously in this specification for tool 200 of FIGS. 2A and 2B , and tool 300 of FIGS. 8A and 8B .
- an apparatus for polishing objects comprising a computer numerically controlled (CNC) machine in which is fitted one of the tools of the present invention as depicted in FIGS. 10-18A .
- CNC computer numerically controlled
- FIGS. 19, 20 , and 21 Various embodiments of such apparatus are depicted in FIGS. 19, 20 , and 21 .
- FIG. 19 is a perspective view of a first preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished.
- FIG. 20 is a perspective view of a second preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished.
- FIG. 21 is a perspective view of a third preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished.
- CNC machine 1000 is similar to that depicted in polishing apparatus 100 of FIG. 1 , comprising a base 102 that supports Y-axis linear slide 104 , the motion of which is bi-directional along Y-axis 105 as indicated by arrow 999 .
- Linear slide 106 the motion of which is bi-directional along X-axis 107 as indicated by arrow 998 , is mounted upon Y-axis linear slide 104 .
- These linear slides 104 and 106 are both computer numerically controlled (CNC) positioning devices, providing programmable motion in the X-Y plane.
- CNC machine 1000 further comprises vertical slide 120 attached to polishing machine frame or plate 123 , which is joined to base 102 .
- the motion of vertical slide 120 is bi-directional along Z-axis 121 as indicated by arrow 997 .
- CNC machine 1000 is preferably provided with rotary axis 151 , which is mounted upon vertical slide 120 , and which is rotatable around B axis 152 (parallel to Z-axis 121 ) as indicated by bidirectional arrow 154 .
- Polishing tool spindle 124 is attached to rotary axis 151 .
- CNC machine 1000 further comprises a rotatable chucking device 126 attached to the end of polishing tool spindle 124 , in which the drive shaft 612 polishing tool 600 of the present invention is inserted and rotated.
- Polishing tool 600 is positionable in a variety of orientations, several of which are depicted in FIGS. 19-21 , depending upon the particular object to be polished.
- Polishing tool 600 is further affixed by a linkage (not shown), which attaches to pin 659 and which is joined to spindle 124 , thereby immobilizing base 602 and preventing overall rotation of tool 600 by spindle 124 .
- a linkage not shown
- apparatus 1010 comprises CNC machine 1000 further comprised of a work piece spindle 108 mounted upon linear slide 106 .
- the motion of spindle 108 is bidirectionally programmable along axis 109 , which is parallel to X-axis 107 .
- spindle 108 is movable by computer control along axis 109 , depending on the requirements or the polishing process.
- the motion of object 112 in the X-Y plane with respect to tool 600 is programmable, and is performed by slides 104 and 106 .
- Rotatable work piece chucking device 110 is attached to end of work piece spindle 108 .
- the work piece 112 to be polished is engaged and held by chuck 110 and rotated by spindle 108 around the central rotary axis 109 thereof as indicated by arrow 996 .
- This rotary motion of object 112 results in the surface motion thereof being orthogonal to the motion of the polishing foil 680 (see FIG. 14 ) of tool 600 . In this manner, such orthogonal motion of the object surface with respect to the foil substantially eliminates any “grooving” effect in the object surface by the polishing foil.
- apparatus 1020 comprises CNC machine 1000 further comprised of a work piece spindle 162 mounted upon linear slide 106 .
- Apparatus 1020 is similar to apparatus 1010 of FIG. 19 , with the differences being in the orientation of the object 112 and the use of various slides and spindles to provide the relative motion between tool 600 and object 112 .
- Spindle 162 is a vertically disposed spindle, the central axis 169 of which is parallel to Z-axis 121 .
- Rotatable work piece chucking device 164 is attached to end of work piece spindle 162 .
- the work piece 112 to be polished is engaged and held by chuck 164 and rotated by spindle 162 around the central rotary axis 169 thereof as indicated by arrow 995 .
- the motion of spindle 162 is bidirectionally programmable along the X axis 107 and the Y axis 105 , both of which are perpendicular to the central axis of rotation 169 of object 112 .
- rotary axis 151 and spindle 124 are rotated 90 degrees clockwise from their respective positions in FIG. 19 , and slide 120 is used to move tool 600 axially in the Z direction.
- apparatus 1030 is substantially the same as apparatus 1020 depicted in FIG. 20 in terms of components.
- Apparatus 1030 differs in setup in the position of spindle 162 on slide 106 , and in the extent of rotation of rotary axis 151 and spindle 124 , such rotation being about 30 degrees clockwise from their respective positions in FIG. 19 .
- spindle 162 is locked, thereby preventing rotation of object 114 , since object 114 is not axisymmetric.
- object 114 is an equilateral prism, which thus requires the rotation of rotary axis 151 and spindle 124 of about 30 degrees.
- prism 114 is moved in the X and Y directions by the motion of slides 106 and 104 respectively, thereby moving prism in the X-Y plane with respect to tool 600 .
- Tool 600 is moved in the Z-direction by slide 120 , thereby enabling the foil 680 (see FIG. 14 ) of tool 600 to traverse up and down the sloped face 115 of prism 114 .
- the CNC machine 1000 is programmed to articulate tool 600 over the surface 115 of object 114 in a more complex path in X-Y-Z space.
- tool 600 may be generally advanced along a linear path, but with a circular motion superimposed on such linear path.
- Such a tool path is known in the art as a trichordal path.
- such tool paths may include arcuate, zigzag, sinusoidal, or other combinations of motion so as to enhance the removal rate of material from object 114 , and to prevent the occurrence of any “grooving” effect in the object surface during the polishing thereof.
- CNC machines may have more or fewer linear and rotational actuators as required by the particular application.
- polishing methods described herein and depicted in FIGS. 5, 6 , and 7 for the operation of apparatus 100 of FIG. 1 and apparatus 150 of FIG. 9 , using tool 200 of FIG. 2A and tool 300 of FIG. 8A are readily adaptable to tool 500 of FIGS. 10-13 and tool 600 of FIGS. 14-17 , when such tools are fitted to apparatus 1010 , 1020 , or 1030 of FIGS. 19-21 respectively.
- such methods may in some embodiments only differ by the setups of the particular tools 500 and 600 , and in the additional control required of the linear actuating means, such as the fluid pressure provided to cylinder 542 (see FIG. 10 ) or cylinders 642 and 662 (see FIG. 14 ).
- actuation means that can increase the separation distance between two wheels, thereby providing increased tension of a belt engaged therewith; or that can increase the belt path length therearound (such as by an idler pulley), thereby providing increased tension of a belt engaged therewith, and that such actuation means are considered within the scope of the present invention. It will be apparent that there are many other apparatus configurations comprising actuation means that can adjust the position of a first wheel engaged to a second wheel by a belt, either along an arcuate path or a linear path or a combination thereof, and that such actuation means are also considered within the scope of the present invention.
- another tool may perform similar polishing operations as those tools shown in FIG. 2A - FIG. 4 and described herein.
- This tool shares the common principle of providing a force from within a flexible tool material which results in the formation of a curved surface of an elastomeric bladder.
- a polishing foil is disposed upon the bladder, and polishing of an object is performed by the tool at the point of contact of the foil on the curved surface with the surface of the object.
- FIG. 23A, 25A , and 26 A are a perspective view, a side cross-sectional view, and a side view, respectively, of a solid bladder polishing tool of the present invention depicted in an uncompressed state; and FIG. 24 is an exploded perspective view of the solid bladder polishing tool of FIG. 23A , exploded along the axis 23 A- 23 A.
- tool 700 comprises a main body or bladder mandrel 710 having a drive shank 712 at a proximal end 711 thereof, and a flange 718 at a distal end 719 thereof, upon which solid bladder 730 is disposed and engaged therewith.
- Mandrel 710 further comprises a bladder shank 714 extending upwardly from flange 718 , and a threaded shank 716 extending downwardly from drive shank 712 , joining bladder shank 714 at stop shoulder 715 .
- Solid bladder 730 has a generally annular shape and is fitted over mandrel 710 such that when assembled, bladder shank 714 of bladder mandrel 710 is disposed within inner bore 732 of solid bladder 730 .
- Upper surface 734 and lower surface 736 of solid bladder 730 are in contact with the lower surface 742 of compression washer 740 and upper surface 717 of flange 718 , respectively.
- Compression collar 750 is slid over drive shank 711 of mandrel 710 , and is positioned along mandrel 710 proximate to threaded shank 716 ; however, compression collar 750 is not engaged with the threads of threaded shank 716 .
- Nut 760 is engaged with the threads of threaded shank 716 of mandrel 710 , thereby applying an axial force against compression collar 750 , and compression washer 740 .
- nut 760 can be tightened so that compression washer 740 and flange 718 of mandrel 710 to apply a compressive force against solid bladder 730 as indicated by arrows 799 and 798 (see FIG. 25B ), thereby enabling the engagement of bladder 730 with polishing band 770 , as will be explained presently.
- polishing band 770 of tool 700 is not shown in FIG. 25A .
- FIGS. 24 and FIGS. 23B, 25B , and 26 B are a perspective view, a side cross-sectional view, and a side view, respectively, of a solid bladder polishing tool of the present invention depicted in a compressed state.
- FIGS. 25A and 25B and beginning with the tool 700 assembled in an uncompressed state as shown in FIG. 25A , nut 760 is tightened, driving compression washer 740 toward flange 718 of mandrel 710 , as indicated by arrows 799 and 798 .
- inner shoulder 755 of compression collar 750 is also driven toward stop shoulder 715 of mandrel 710 , as indicated by arrow 797 .
- Nut 760 is tightened, preferably by engaging a first wrench (not shown) with nut 760 and a second wrench (not shown) with a wrench flat 729 provided in stub 728 of mandrel 710 (see FIG. 26B ) until inner shoulder 715 seats upon stop shoulder 755 and is stopped thereby, as depicted in FIG. 25B .
- This feature of tool 700 enables a highly reproducible compressive force to be applied to solid bladder 730 when tool 700 is disassembled and reassembled.
- Solid bladder 730 is made of a highly elastic incompressible solid.
- Solid bladder preferably consists essentially of an elastomer having a Shore A durometer of between about 10 and about 90.
- Solid bladder 730 may be made of any suitable material which, when subjected to a compressive force, undergoes elastic deformation in a direction substantially orthogonal to such compressive force.
- solid bladder 730 may consist essentially of gum rubber, nitrile rubber, or polyurethane.
- solid bladder 730 may consist essentially of an elastomeric closed cell foam.
- solid bladder 730 is made of nitrile rubber having a Shore A durometer of about 40. Accordingly, when solid bladder 730 is compressed between compression washer 740 and flange 718 of mandrel 710 as indicated by arrows 799 and 798 , the outer surface 739 of solid bladder 730 bulges outwardly as indicated by arrows 796 .
- polishing band 770 is slid over solid bladder 730 . Polishing band 770 slides over uncompressed and/or semi-compressed solid bladder 730 with a generally loose sliding fit. When solid bladder 730 is compressed as indicated in FIG.
- solid bladder 730 expands radially outwardly as indicated by arrows 796 , and engages tightly with polishing band 770 , stretching polishing band 770 into the arcuate shape of outer surface 739 of solid bladder 730 (see FIG. 25B ).
- the outer surface 739 of solid bladder 730 assumes a generally arcuate shape simply due to the axial compression thereof, and the resulting radial expansion thereof. However, to achieve optimum polishing results of optics and the like, it is preferable that the arcuate surface 739 of compressed solid bladder 730 be ground or otherwise formed to a specified arcuate shape.
- tool 700 is assembled as just previously described, with solid bladder 730 in compression and polishing band 770 not fitted to solid bladder 730 .
- Setscrew 759 in compression collar 750 is fitted and tightened such that setscrew 759 engages in slot 713 in threaded shank 716 of mandrel 710 to the position indicated by engaged setscrew 759 A shown in phantom in FIG. 25B . This engagement of setscrew 759 in slot 713 prevents the rotation of compression collar 750 on mandrel 710 during grinding and during a polishing operation.
- arcuate surface 739 of solid bladder 730 is ground to a desired shape.
- arcuate surface 739 is ground to a spherical shape.
- solid bladder 730 may have an uncompressed radius 795 of about 3.1 inches, a thickness of about 1 inch, and when compressed, a spherical arcuate surface 739 with a radius of about 4 inches and a thickness of 0.75 inches. It is to be understood that this radius of about 4 inches describes the radius of curvature of the surface 739 in the x-z through y-z planes, with z being the central axis 23 A- 23 A (see FIG. 24 ) of tool 700 , rather than the radius 795 of solid bladder 730 .
- tool 700 is removed from the surface grinder machine for the fitting of a polishing band to surface 739 .
- setscrew 759 in compression collar 750 is loosened slightly to allow setscrew 759 to slide in the axial direction (along axis 23 A- 23 A) in slot 713 in threaded shank 716 of mandrel 710 .
- Nut 760 is then loosened, and setscrew 759 slides in slot 713 until setscrew 759 butts up against the upper end 721 of slot 713 .
- setscrew 759 fitted in compression collar 750 and engaged with upper end 721 of slot 713 further axial travel of compression collar 750 is stopped.
- solid bladder 730 remains in a state of semi-compression from that point on. Solid bladder 730 is thus preferably never totally released from its compression by compression washer 740 and flange 718 of bladder mandrel 710 after the finish grind is completed. A polishing band is then fitted around solid bladder 730 , and nut 760 is retightened, engaging polishing band 770 with solid bladder 730 , and forming polishing band 770 to the desired arcuate shape.
- setscrew 759 in compression collar 750 is tightened such that setscrew 759 engages in slot 713 in threaded shank 716 of mandrel 710 to the position indicated by engaged setscrew 759 A shown in phantom in FIG. 25B .
- compression collar 750 and compression washer 740 are provided as a single unitary part, i.e. as a compression flange 750 / 740 . Such a compression flange 750 / 740 is locked to said mandrel and prevented from rotation by engaged setscrew 759 A during operation.
- solid bladder 730 is highly compressed and thus frictionally engaged with flange 718 , compression washer 740 , and bladder shank 714 , solid bladder 730 and polishing band 770 engaged therewith are also prevented from slipping during the use of tool 700 for a polishing operation.
- polishing band 770 suitable materials for polishing band 770 are as described previously in this specification for the polishing tools described and shown in FIGS. 2A-4 .
- the terms “polishing foil” and “polishing band” are used interchangeably.
- a solid bladder 730 impregnated with abrasive particles such as e.g., diamond particles, such that the solid bladder performs both the function of deformability to some extent to define the spot size during polishing, and abrasiveness to effect material removal during polishing.
Abstract
A tool for polishing objects having a wide variety of materials and shapes including precision optical surfaces, injection mold inserts, and thin film coating dies. The tool has an elastic solid bladder with a curved surface, upon which is disposed an abrasive band. The curved bladder surface is produced by compressing the bladder between two parallel plates. The apparatus comprises a multi-axis computer controlled machine to which the tool is attached.
Description
- This application is a continuation-in-part of copending patent application U.S. Ser. No. 10/863,702, filed on Jun. 8, 2004, which is a continuation-in-part of copending patent application U.S. Ser. No. 10/439,833, filed on May 16, 2003, the disclosures of which are incorporated herein by reference.
- A polishing tool for correcting surface errors, and for polishing objects comprising a wide variety of materials and shapes including precision optical surfaces and injection mold inserts.
- This invention relates to tools, an apparatus, and a method for correcting figure errors, and for polishing a wide variety of materials and shapes including but not limited to precision optical surfaces, injection mold inserts, thin film coating dies, and the like. The method of the present invention provides for improving and further finishing of any surface, ranging from a relatively rough ground surface to a polished surface.
- Typically the part being finished according to the present invention is measured with a coordinate measurement machine (CMM), a surface profilometer, an interferometer, microscope or some other measuring instrument capable of giving surface roughness and or profile data. The data from such measurement and analysis is then entered into a machine process-controlling computer that then manipulates the data into process parameters for improving or polishing the desired component by a polishing machine of the present invention. One or more iterations of the process of the present invention may be required to achieve the desired results. In the preferred embodiment, a polishing tool comprising an inflatable bladder is attached to and driven by the tool spindle of the polishing machine. The part to be improved or polished, whether spherical, aspherical or parabolic in shape, is placed into the work piece spindle of the polishing machine. If such part is not axially symmetrical, it may be held in a braked position in the work piece spindle, or held in a fixture on a table of the machine. The polishing tool is then compressed against and traversed in a path over the component. Several variables are able to be controlled as process parameters, so that the desired finishing results are achieved.
- In another preferred embodiment, the polishing tool further comprises actuation means to extend and/or position and/or compress the inflatable bladder or other compliant part with respect to the part to be improved or polished. Such actuation means may comprise one or more linear actuating devices such as e.g., air operated or hydraulically operated cylinders.
- The present invention provides a method and apparatus for which the main goal is to polish out and remove defects left from a preceding grinding operation or to improve the accuracy of a workpiece such as a lens, mirror, insert for an injection mold, or coating die, such accuracy being relative to the intended use of the workpiece; and also to improve the economy of the polishing process.
- In the following specification, for the sake of linguistic simplification, only optical components, also known as precision optics or optics generally, are typically mentioned as the workpiece. However, it is to be understood that all lenses, spherical and aspherical, conformal optics, mirrors, plano shapes, injection mold components, coating dies, and other articles of manufacture that require highly polished accurate surfaces are also included in the description, and are to be considered as being within the scope of the present invention. Materials that may be finished using the method and apparatus of the present invention include, but are not limited to brittle amorphous materials such as e.g., glass, ceramics, infrared materials such as quartz, and the like. Also included are metals such as e.g., tool steel, stainless steel, and the like; crystalline materials such as e.g. silicon; and any other workpieces requiring high finish and form specifications.
- Currently, many optical lenses are made beginning with a “blank” starting part (such blank part being an approximately formed and generally roughly finished piece) in several processing steps. The process steps typically include fine grinding, followed by conventional polishing techniques wherein the surface roughness and surface accuracy of the lens is significantly improved. This prior art process is sufficient for many conventional low-precision lenses, but when the desired lens has a shape that is not spherical or plano and/or where such conventional methodologies cannot be applied e.g., aspherics, or where the lens has very high accuracy requirements, such prior art process is not sufficient. In such circumstances, the method and apparatus of the present invention is advantageous.
- In particular, several prior art procedures are known to the applicants as being used to fabricate precision optics. One of these procedures is known in the art as small spot tool polishing, wherein a pencil like polishing tool (typical 5 to 15 millimeters in diameter) is used, such tool comprising a polishing medium of polyurethane, felt, pitch or some other combination of polishing material bonded thereto, and typically known as a foil.
- In one specific embodiment of the small spot tool polishing process, a polishing tool, rotating around the axis thereof, is mounted to a robotic arm and is traversed by such arm across the lens surface, or alternatively, such tool is built into a computer numerically controlled (CNC) polishing machine. During the process a polishing suspension is applied, while the polishing tool is traversed across the lens surface through a predetermined typically computer controlled path. Depending on the correction geometry required, different volumes of material are abraded, or polished, from the lens surface. The robotic arm of the correction machine is programmed in such a way that the polishing tool is moved with different dwell times at different positions as such tool passes over the lens. Thus, when more material must be removed at a particular location, the dwell time is increased, and vice versa. During the polishing process, the lens may be rotate around its axis, or be it may be fixed in specific positions if the robotic arm of the correction machine has such capability.
- In the small spot procedure there are several disadvantages. The polishing tool wears quickly due to its small diameter, which results in the distinct disadvantages of a) typically very long polishing cycles; and b) because of quicker degradation of the small polishing foil it is much more difficult and costly to develop accurate corrective polishing routines. Another disadvantage is due to the small spot diameter of the tool. Material removal rates are typically very slow, since the performance is directly proportional to the size of the surfaces that are in contact during the polishing routine.
- Another known finishing/polishing procedure is known as magnetorheological finishing (MRF). With the use of the MRF process, marked improvements in surface roughness and accuracy can be achieved. In general, the MRF process produces better results than small spot polishing. Reference may be had e.g., to U.S. Pat. Nos. 5,795,212, 6,106,380 (deterministic magnetorheological finishing), 5,839,944 (apparatus deterministic magneto-rheological finishing), 5,971,835 (system for abrasive jet shaping and polishing of a surface using a magnetorheological fluid), 5,951,369, 6,506,102 (system for magnetorheological finishing of substrates), and 6,267,651 and 6,309,285 (magnetic wiper). The entire disclosure of each of these United States patents is hereby incorporated by reference into this specification.
- With the MRF procedure a polishing suspension is used, which contains particles that can be magnetized and therefore under the effect of strong electromagnets can be solidified. A polishing suspension is applied sequentially on the outside surface of a cylinder rotating around its horizontal axis. The polishing suspension is disposed in a thin band upon the outside surface of a rotating cylinder, and is conveyed to a location where a strong magnetic field is focused. This field is created by magnets surrounding both sides of the wheel. Under the influence of the magnetic field, the polishing suspension increases in viscosity until it is substantially an abrasive solid, thereby forming a stiff polishing body, which becomes the polishing tool. Thus within this area i.e., in the upper apex of the polishing tool, a lens may be polished by such solidified MRF fluid. As the wheel rotates the polishing suspension leaves the contact area of the lens and the magnetic field, and is then vacuumed/wiped off of the wheel and continuously recirculated.
- During the MRF polishing process, the lens rotates. The lens carrier with the lens can be placed by means of a tilting device and an assigned axis control at angles to the vertical axis. With a large angle of inclination, the edge of the lens touches the polishing tool, while with a small angle of inclination the center of the lens comes into contact with the polishing tool. Additionally the lens carrier is guided in such a way that it also can execute vertical movements. With a rotating lens, the angles of inclination are continually varied; such variation is accomplished with the use of virtual pivot point computer controlled motion that combines the two linear and one rotary axes and thus keeps the lens in consistent contact with the polishing tool. A spiral develops on the lens that is the trajectory of the point of contact between the solidified polishing suspension and the lens surface.
- The different material removals necessary for the correction of the lens geometry are implemented as follows: The dwell time of the point of contact on a certain area on the lens surface can be varied by appropriately controlling the courses of motion. Since the material removal is proportional to the dwell time, the desired corrections can be achieved. The polishing suspension in its “firmness” can be influenced by variation of the magnetic field strength. This further enables different material removal rates. A further correction option results by varying the depth of submergence of the lens into the polishing suspension.
- Although the MRF process has many attributes, such process also has some distinct disadvantages as follows: 1) Cost-effective polishing of deviations is limited to errors of less than 200 nanometers only. This is a result of the lack of “stiffness” of the magnetically stiffened polishing suspension and the ability to shear/polish features greater in magnitude. 2) There is a very high capital cost of entry into the MRF technology. The process entails very complex technology, which also increases the cost of operation. It is also necessary to continuously change the MRF polishing suspension, which is very expensive because of its proprietary nature. 3) Parts made of magnetic materials are not able to be polished with this process, as the workpiece will become magnetized and not release the magnetic process fluid. 4) Small concave parts cannot be polished due to the configuration and size of the MRF polishing wheel.
- Reference may be had to German patent DE003 1057 of R. Mandler, the disclosure of which is incorporated herein by reference. There is disclosed in such patent a method for polishing of lenses and mirrors for high resolution optics. The lens/mirror is polished conventionally and measured by interferometric means to map the surface and to determine how much material needs to be removed and from where. The lens is supported on a rotating holder with two degrees of movement, while the polishing wheel is supported with axial adjustment. The polishing wheel has a flexible rim inflated with a variable internal pressure to adjust the hardness of flexible rim/tire. Mandler relies upon changes in pressure on a polyurethane foil to impact removal rates and finishing qualities. Although as stated therein, the apparatus of Mandler can change the pressure during the process, such process does not have the ability to change to softer media, such as felt or other softer synthetic materials as is disclosed and claimed in this application. Mandler also discloses only a 3-axis process, whereas embodiments of the present invention include control and operation with respect to five or more axes.
- With the method and apparatus of the present invention, many of the disadvantages of the aforementioned techniques are non-existent, or rendered insignificant. It is therefore an object of this invention to provide an apparatus for precision polishing of objects comprising a wide variety of materials and shapes.
- It is a further object of this invention to provide a versatile and adjustable tool for precision polishing of objects comprising a wide variety of materials and shapes.
- It is another object of this invention to provide a method for precision polishing of objects comprising a wide variety of materials and shapes.
- It is an object of this invention to provide a method and apparatus for precision polishing of objects that is simple and has a low operating cost.
- It is an object of this invention to provide a method, a tool, and an apparatus that in having the ability to remove low, mid, and high spatial surface errors, reduces the requirements of the pre-fine grind tolerances, which in turn reduces the requirements of the fine grinding apparatus.
- It is an object of this invention to provide a method and apparatus for precision polishing of objects that has a high rate of material removal.
- It is an object of this invention to provide a tool for precision polishing of objects that has high longevity and stability of operation.
- It is an object of this invention to provide a method, a tool, and an apparatus that has the ability to perform polishing of object surfaces that are deeply concave in shape.
- In accordance with the present invention, there is provided a polishing tool comprising a mandrel having a drive shank at a proximal end thereof, a threaded shank, a mandrel shank, and a flange at a distal end thereof; a solid elastic annular bladder comprising a bore, an outer surface, a lower surface, and an upper surface, said bladder disposed upon said mandrel with said lower surface of said bladder in contact with said flange of said mandrel and said mandrel shank passing through said bore in said bladder; a compression flange comprising a compression washer and a compression collar, said compression washer comprising a lower surface in contact with said upper surface of said bladder, and said compression collar comprising a bore slidingly engaged with said threaded shank of said mandrel; and a compression nut threadedly engaged with said threaded shank of said mandrel, wherein when said compression nut is tightened upon said threaded shank, said solid bladder is compressed between said flange of said mandrel and said compression washer, causing said outer surface of said bladder to have an arcuate shape.
- In accordance with the present invention, there is provided a polishing tool comprising a mandrel having a drive shank at a proximal end thereof, a threaded shank, a mandrel shank, and a flange at a distal end thereof; a solid elastic annular bladder comprising a bore, an outer surface, a lower surface, and an upper surface, said bladder disposed upon said mandrel with said lower surface of said bladder in contact with said flange of said mandrel and said mandrel shank passing through said bore in said bladder; a compression flange comprising a compression washer and a compression collar, said compression washer comprising a lower surface in contact with said upper surface of said bladder, and said compression collar comprising a bore slidingly engaged with said threaded shank of said mandrel; a polishing band engaged with said outer surface of said bladder; and a compression nut threadedly engaged with said threaded shank of said mandrel, wherein when said compression nut is tightened upon said threaded shank, said solid bladder is compressed between said flange of said mandrel and said compression washer, causing said outer surface of said bladder to have an arcuate shape.
- In accordance with the present invention, there is provided a polishing tool comprising a mandrel having a drive shank at a proximal end thereof, a threaded shank, a mandrel shank, and a flange at a distal end thereof; a solid elastic annular bladder comprising a bore, an outer surface, a lower surface, and an upper surface, said bladder disposed upon said mandrel with said lower surface of said bladder in contact with said flange of said mandrel and said mandrel shank passing through said bore in said bladder; and means for compressing said lower surface of said bladder toward said upper surface of said bladder, thereby causing said outer surface of said bladder to have an arcuate shape.
- The tools, apparatus, and method of the present invention are advantageous because they are simple and lower in cost compared to other approaches, and it can be adapted for the polishing of a variety of materials and shapes, particularly those objects having deeply concave shapes. As a result of the invention, articles of manufacture such as precision optics, injection mold inserts, and thin film coating dies can be polished with high precision at a high throughput and low cost.
- The invention will be described by reference to the following drawings, in which like numerals refer to like elements, and in which:
-
FIG. 1 is a schematic representation of one preferred polishing apparatus of the present invention; -
FIG. 2A is a cross-sectional view of one preferred polishing tool of the present invention; -
FIG. 2B is a side elevation view of the polishing tool ofFIG. 2A , in the process of polishing a convex lens; -
FIG. 3 is a cross-sectional view of another preferred embodiment of a polishing ring disposed upon the polishing tool ofFIG. 2A ; -
FIG. 4 is a cross-sectional view of one preferred embodiment of a polishing ring disposed upon the polishing tool ofFIG. 2A ; -
FIG. 5 is a flowchart depicting a method of assembly of the preferred polishing tool ofFIG. 2A ; -
FIG. 6 is a flowchart depicting a method of preparing the preferred apparatus ofFIG. 1 for a polishing operation; and -
FIG. 7 is a flowchart of a complete method of polishing an optic using the apparatus and polishing tool of the present invention. -
FIG. 8A is a cross-sectional view of another preferred polishing tool of the present invention; -
FIG. 8B is a side elevation view of the polishing tool ofFIG. 8A , in the process of polishing a concave lens; -
FIG. 9 is a schematic representation of another preferred polishing apparatus for polishing concave spheres, aspheres, convex spheres, or other conformal shapes; -
FIG. 10 is a first perspective view of another preferred polishing tool of the present invention comprising single cylinder actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished; -
FIG. 11 is a side elevation view of the polishing tool ofFIG. 10 ; -
FIG. 12 is a top view of the polishing tool ofFIG. 10 ; -
FIG. 13 is a second perspective view of the polishing tool ofFIG. 10 , taken from the plate side of the polishing tool; -
FIG. 14 is a first perspective view of another preferred polishing tool of the present invention comprising twin cylinder actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished; -
FIG. 15 is a side elevation view of the polishing tool ofFIG. 14 ; -
FIG. 16 is a top view of the polishing tool ofFIG. 14 ; -
FIG. 17 is a second perspective view of the polishing tool ofFIG. 14 , taken from the plate side of the polishing tool; -
FIG. 18A is a cross-sectional elevation view of the polishing tool ofFIG. 14 , shown disengaged with a deeply concave object to be polished; -
FIG. 18B is a cross-sectional elevation view of the polishing tool ofFIG. 14 , shown engaged from a deeply concave object to be polished; -
FIG. 19 is a perspective view of a first preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished; -
FIG. 20 is a perspective view of a second preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished; -
FIG. 21 is a perspective view of a third preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished; -
FIG. 22A andFIG. 22B are schematic representations of means for engaging a polishing foil of the polishing tools ofFIGS. 10-13 andFIGS. 14-18B ; -
FIG. 23A is a perspective view of a solid bladder polishing tool of the present invention depicted in an uncompressed state; -
FIG. 23B is a perspective view of a solid bladder polishing tool of the present invention depicted in a compressed state; -
FIG. 24 is an exploded perspective view of the solid bladder polishing tool ofFIG. 23A , exploded along theaxis 23A-23A; -
FIG. 25A is a side cross-sectional view of a solid bladder polishing tool of the present invention depicted in an uncompressed state, with the polishing foil absent; -
FIG. 25B is a side cross-sectional view of a solid bladder polishing tool of the present invention depicted in an compressed state, with the polishing foil absent; -
FIG. 26A is a side view of a solid bladder polishing tool of the present invention depicted in an uncompressed state; and -
FIG. 26B is a side view of a solid bladder polishing tool of the present invention depicted in an compressed state. - The present invention will be described in connection with certain preferred embodiments, however, it will be understood that there is no intent to limit the invention to the embodiments described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
- For a general understanding of the present invention, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate identical elements. In describing the present invention, the following term(s) have been used in the description:
- As used herein, the term figure error (or form error) is the measured global deviation from the desired surface shape e.g., a sphere, asphere or polynomial geometric shape.
- As used herein, form error is a low frequency error. Traditionally in optics, irregularity and power are the two specifications that need to be considered. Irregularity is the deviation from a perfect surface. Power is the resulting average surface dimensions e.g., radius of curvature.
- As used herein, the term zonal enhancement is meant to indicate a correction of the figure error, which is located symmetrically or asymmetrically at one specific location (zone) on the work piece. For example, if a cylindrical disc was the workpiece, a zonal error would be in one sector of the disc, or in a specific band or ring on the disc, or other rotationally symmetrical part.
- As used herein, the terms spot, high, mid- and low spatial frequencies in reference to errors in a surface to be polished are meant to indicate the following. Low spatial frequencies are errors that appear only once to a few times across a particular surface. Mid-spatial frequencies are errors that occur many times across a surface of a part, generally have a periodic spacing of between 80 microns and 3 mm, and are typically caused by cutter marks due to machine or tool vibrations. High spatial frequencies are errors that happen on a microscopic scale, which may appear thousands of times across the surface of a part, and have a periodic spacing of less than 80 microns.
- As used herein, the term polishing, when used in reference to a workpiece to be finished, is meant to indicate a chemo/mechanical process that ablates material from a surface.
- As used herein, the term correction of form, or form error modification correction, when used in reference to a workpiece to be finished, is meant to indicate the same as has been defined for figure error.
- As used herein, the term figure, when used in reference to a workpiece to be finished, is meant to indicate polishing in a correction for error in the figure and or form, which are the same.
- As used herein, the term surface roughness, when used in reference to a workpiece to be finished, is meant to indicate high frequency errors, which are typically the result of brittle fracture regime (e.g.microcracks).
-
FIG. 1 is a schematic representation of one preferred polishing apparatus of the present invention. Referring toFIG. 1 , polishingapparatus 100 is configured for polishing convex spheres, aspheres, shallow concave spheres, or other conformal shapes.Polishing apparatus 100 comprises a base 102 that supports Y-axislinear slide 104, the motion of which is bi-directional along Y-axis 105 (directed perpendicular to the plane ofFIG. 1 ).Linear slide 106, the motion of which is bi-directional alongX-axis 107, is mounted upon Y-axislinear slide 104. Theselinear slides -
Workpiece spindle 108 is mounted uponlinear slide 106, such that the motion ofspindle 108 is bidirectionally programmable alongaxis 109, which is parallel to X-axis 107. Thusspindle 108 is movable by computer control alongaxis 109, depending on the requirements or the polishing process. Rotatableworkpiece chucking device 110 is attached to end ofworkpiece spindle 108. Theworkpiece 10 to be polished is engaged and held bychuck 110 and rotated byspindle 108 around the central rotary axis thereof. -
Apparatus 100 further comprisesvertical slide 120 attached to polishing machine column 122, which is joined tobase 102. The motion ofvertical slide 120 is bi-directional along Z-axis 121.Polishing tool spindle 124 is attached to the Z-axis slide 120. The rotational speed (RPM) of this spindle is varied by the computer depending on the desired removal rate of material fromworkpiece 10.Apparatus 100 further comprises arotatable chucking device 126 attached to the end of polishingtool spindle 124, in which polishing tool 128 of the present invention is inserted and rotated. Polishing tool 128 is provided in a variety of shapes, sizes, and materials (e.g. see polishingtool 200 ofFIG. 2A and 2B ), as will be described subsequently in this specification. - In summary, there are three linear and one rotary axis drives in this configuration, all of which are computer controlled to allow for a deterministic polishing process, to be described subsequently in more detail in this specification.
- Referring again to
FIG. 1 , in the preferred embodiment,apparatus 100 further comprises afluid delivery system 130 for delivery of a homogeneous liquid or a liquid slurry. In some embodiments,delivery system 130 delivers a liquid containing finely divided solid particles, and as such is considered a slurry, a suspension, or a particulate dispersion. Such particles are preferably abrasive polishing particles with a hardness sufficient to wear a typical optical material such as e.g. glass. Such particles may comprise e.g., silica, alumina, ceria, diamond, and the like, and mixtures thereof. Many other hard, abrasive particulate materials such as e.g., carbides, nitrides, etc. will be apparent to those skilled in the art. - In other embodiments,
delivery system 130 delivers a homogeneous liquid substantially free of solid particles. Suitable liquids may be e.g. water, water soluble oils or lubricants (such as e.g. glycerine), hydrocarbon oils, silicone oils, and the like. The selection of a particular homogeneous liquid or a particulate slurry will depend upon the particular optical part being polished, and upon the desired end results. - Referring again to
FIG. 1 , slurry orfluid delivery system 130 comprises a reservoir (not shown), a slurry/fluid mixer 132, and a slurry/fluid pump 134. Slurry/fluid delivery system 130 is used to supply an abrasive slurry/fluid (not shown), which is delivered throughconduit 136 and directed bynozzle 138 upon the polishing tool 128 andworkpiece 110, at the area of contact there between. -
FIG. 2A is a cross-sectional view of one preferred polishing tool of the present invention used inapparatus 100 ofFIG. 1 , according to the methods of the present invention. Referring toFIG. 2A , polishingtool 200 comprises a main body orbladder mandrel 202 having ashank 201 at aproximal end 224 thereof, and aflange 211 at a distal end thereof, around which abladder 204 is disposed and sealably engaged therewith.Compression washers bladder 204, and are held in place by lockingnuts Nuts washers washers hold bladder 204 tightly againstflange 211 ofmandrel 202. In the preferred embodiment,lips bladder 204 are disposed and held firmly ingrooves mandrel 202, so thatbladder 204 is sealed tomandrel 202. -
End 210 ofmandrel 202 has anaxial bore 212 disposed therein, which is connected to at least oneradial bore 214, or preferably a plurality ofradial bores 214 extending to acavity 216 disposed in the perimeter 218 ofmandrel 202. Suchaxial bore 212 andradial bores 214 form a continuous passageway such thatcavity 216 is in communication with the atmosphere outside oftool 200. Thusaxial bore 212 andradial bores 214 allow thecavity 216 to be filled and pressurized with a fluid delivered throughinflation device 220, which is disposed and sealed inaxial bore 212 at theend 210 ofmandrel 202. -
Polishing tool 200 further comprises aring assembly 230 of polishing material disposed around the outer perimeter ofbladder 204.FIG. 3 is a cross-sectional view of one preferred embodiment of a polishing ring disposed upon the polishing tool ofFIG. 2A . Referring toFIG. 3 ,ring assembly 230 is a dual ring assembly comprising abacker ring 232 of material, over which is disposedabrasive ring 234 comprised of a polishing medium adhered thereto. The resulting polishingring assembly 230 is disposed around the perimeter of and contiguous withbladder 204. In one preferred embodiment,backer ring 232 consists essentially of a band of poly(ethylene terephthalate) having a thickness of between about 50 microns and about 1000 microns, and a width of between about 2 millimeters and about 30 millimeters. -
Abrasive ring 234 is made of a material of sufficient structural strength to withstand the high shear and tensile forces during polishing, and to resist degradation through exposure to the polishing/lubricating fluid, such as e.g. polyurethanes of various durometers; and various types of felt, cork, and metal and/or resin bond diamond, alumina, and/or zirconium, with a multitude of different types of backings and patterns therein.Abrasive ring 234 preferably has a thickness of between about 1 millimeter and about 5 millimeters, and a width of between about 2 millimeters and about 30 millimeters. -
FIG. 4 is a cross-sectional view of another preferred embodiment of a polishing ring disposed upon the polishing tool ofFIG. 2A . Referring toFIG. 4 ,ring 230 simply comprises a single ring 236 of polishing material disposed around the perimeter ofbladder 204. The embodiment ofFIG. 4 is used when ring 236 is of sufficient structural strength so as to be able to perform the particular polishing process without the use of a supporting ring disposed contiguously with such ring, as was depicted inFIG. 3 . In one preferred embodiment, single ring 236 consists essentially of polyurethane, and has a thickness of between about 1 millimeter and about 5 millimeters, and a width of between about 2 millimeters and about 30 millimeters. -
FIG. 2B is a side elevation view of the polishing tool ofFIG. 2A , in the process of polishing a convex lens. Referring toFIGS. 2A and 2B , polishing ring assembly 230 (also known as the foil) is disposed around the outer perimeter ofbladder 204 and held in place whilebladder 204 is pressurized with a fluid. In operation, polishingtool 200 comprising polishingring assembly 230 is rotated and engaged withlens 10 such that polishingring assembly 230 provides a shearing and polishing action upon the surface oflens 10. It will be apparent that the pressure that is applied tobladder 204 will determine the curvature and firmness of the outer surface of polishingring assembly 230 during a polishing operation. - Referring again to
FIG. 2A , and in one preferred embodiment,bladder 204 has a shape and cross sectional profile that is substantially similar to that of a tire.Bladder 204 is preferably made of a compliant, flexible elastic material that is wrapped or attached at its periphery to the perimeter 218 ofmandrel 202. Suitable materials forbladder 204 are e.g., natural or synthetic rubber, silicone, or polyurethane, with a wall thickness of approximately 1 millimeter. - The tire-shaped
bladder 204 may have a variety of specific cross sectional shapes. Before inflatingbladder 204 with either air or some other fluid, polishing foil 203 is disposed around or applied to the bladder tool to act as the polishing medium. In one further embodiment, polishingfoil 230 is made of polyurethane, and the abrasive polishing medium is provided in a liquid slurry that is pumped ontoworkpiece 10 and polishingfoil 230, as described previously. Alternatively, abrasive particles may be embedded in the polishing foil. Suitable abrasive particles include particles made by the Rhodes Corporation, or by the Minnesota Mining and Manufacturing Company (3M). or it may actually be a product that has In a further embodiment, abrasive particles in the shape of miniature pyramids of polishing medium such as e.g., alumina in varying grit sizes is used. Such products will require that only water be added to wet the polishing medium (the dry powder.) - In another embodiment,
foil 230 comprises a backer ring of poly(ethylene terephthalate) (PET) or similar material to allow softer polishing ring media to be used without tearing or pulling apart, yet maintaining the flexibility required for fine polishing.Bladder 204 oftool 200 is then inflated to a specific pressure depending on the polishing results desired. In such an embodiment,foil 230 is held in position uponbladder 204 by the expansion pressure of thebladder 204 being inflated; thus no adhesive or mechanism is required to bondfoil 230 tobladder 204. Such a configuration enables a simple and rapid change of foil polishing media. - In operation of
apparatus 100 ofFIG. 1 , to which is fitted polishingtool 200 ofFIG. 2A , several factors will affect the accuracy and removal rates of the polishing process: the size and shape ofbladder 204, the composition of the polishing medium, the composition of the polishing slurry, and the pressure applied to thebladder 204 and also the type of fluid used to inflate the bladder. These latter variables are related to the tool itself (with the exception of slurry composition). Also affecting the accuracy and removal rates of the polishing process included in this invention are variables of the apparatus, such as e.g., example spindle speeds, axis feed rates and polisher path modifications. - It will be apparent that a variety of fluids may be used to pressurize
bladder 204 of polishingtool 200, and that the physical properties of such fluids, as well as the pressure of such fluids also will affect the accuracy and removal rates of the polishing process. The fluid may be selected so as to beneficially affect the polishing process. In one simple and thus preferred embodiment, air is used as the bladder inflation fluid. In another embodiment, a much more dense fluid, i.e. a liquid, such as water is used as the bladder inflation fluid. In such an embodiment, the effective pressure of the outer wall of the bladder is a function of not only the inflation pressure, but also the rotational speed. Such rotational speed provides an additional pressure component due to the centrifugal force exerted by the fluid, in proportion to the square of the rotational speed. Such pressure is analogous to the pressure at the base of a column of liquid acted upon by gravity. - In a further embodiment, a viscous liquid, such as a hydraulic oil is used as a bladder inflation fluid. The viscosity of such a viscous liquid is preferably between about 10 centipoise and about 100,000 centipoise, and more preferably between about 20 centipoise and about 1000 centipoise. The higher viscosity of such fluid also affects the accuracy and removal rates of the polishing process, because at the contact area of the bladder with the workpiece, the bladder is deformed; hence the fluid disposed within the bladder must undergo viscous flow in this region. Thus a higher viscosity fluid has a greater resistance to deformation, and also being non compressible and thus can provide a beneficial polishing effect. In yet another embodiment, the use of a viscous fluid provides vibration damping to the process, thereby rendering such process more precise, stable, and reliable. In further embodiments, non-Newtonian fluids are used such as. e.g. a shear thinning fluid, or a shear thickening fluid. In other embodiments, fluids for which the rheology may be varied by exposure to an electric or magnetic field may be used.
- Referring again to
FIG. 2A , in one embodiment,inflation device 220 is a simple, inexpensive check valve. In a preferred embodiment, inflation device is a valve stem, commonly used for the inflation of tubeless tires. In another embodiment,axial bore 212 is sealed, andmandrel 202 oftool 200 is provided with a second axial bore 222 disposed through theopposite end 224 ofmandrel 202. In such an embodiment,axial bore 212 is supplied with pressurized fluid from a fluid supply means (not shown) in real time during the polishing process. Such fluid supply means is commonly used as a coolant supply to a machine tool and is well known in the art of machine tools. Thus the pressure withinbladder 204 may be varied and/or pulsated during the polishing process, by the delivery or withdrawal of bladder inflation fluid as indicated by arrow 225. - It is to be understood that many multi-axis CNC machine tools are known in the art, which can be suitably configured to use the polishing tool and the methods of the present invention. The particular configuration of machine tool will depend upon the material properties, size, and shape of the starting blank and the desired finished end product. The present invention is not limited only to the use of the machine tools described herein. For example, such a machine tool could comprise from between two computer controlled axes up to as many as five or six computer controlled linear and/or rotary axes.
- Referring again to
FIG. 1 , polishingtool 200 andworkpiece 10 to be polished are typically inserted intoseparate spindles Machine tool apparatus 100 could have a configuration as shown inFIG. 1 , or a configuration similar to that of a lathe, mill or some other customized arrangement of the axes, depending upon the part to be polished.Work piece spindle 108 may also be programmed to maintain constant surface speed and also to do zonal enhancements that are especially necessary when there are axial asymmetries in the part. It is to be understood that many different machine variations are possible, and that axes and spindles can be configured in a multitude of combinations/permutations to suit any workpiece shape that needs to be polished. The configuration of the different machine axes and spindles can be in any order as required to enable actuation of the polishing tool over the surface of the workpiece to be polished. Accordingly, all such configurations are to be considered within the scope of the present invention. - During the polishing operation, the polishing slurry/fluid suspension is fed between the polishing
tool 200 and thework piece 10 byslurry delivery system 130. Depending on the results required, the axis traverse feedrates (i.e. the velocities of the linear slides), the workpiece rotational speed in revolutions per minute (RPM) and tool spindle rotational speed in RPM, and the tool path variation in three dimensional space are adjusted via automated computer control. - In one embodiment, the pressure (and thus the “firmness”) of
bladder 204 of polishingtool 200 is preset, and maintained constant during the polishing operation. Depending on the bladder shape, the bladder material properties, the bladder inflation pressure, and the hardness/density of polishingfoil 230, a specific pretest is performed in order to characterize the polishing spot profile. As used herein, the term spot profile is meant to indicate the indentation resulting from contacting a test workpiece with polishingtool polishing tool - Thus the shape and size of the area produced when the polishing tool is pressed into the test piece for a given period of time is the spot profile. This spot profile is then used in the generation of the time dependent trajectory of the polishing tool over the surface of the workpiece that is required to achieve the desired polishing results. This time dependent trajectory is also known in the art as the tool path and dwell times used in polishing. With the profile characterized, high, mid and low spatial features can be greatly improved through adjustments of the polishing variables, tool rpm, workpiece rpm, axes feedrates, and compression factor. As used herein, the term compression factor is meant to indicate the compressive force applied by the polishing tool against the workpiece, such force being the combination of force due to bladder pressure, and force due to the trajectory of the tool against the workpiece.
- Referring again to
FIG. 1 , thework piece spindle 108 holdsworkpiece 10, i.e. the optic or other part to be finished.Work piece spindle 108, and/or polishingspindle 124 as described are attached to computer controlled linear or rotary slides 104, 106, 108, and 120 so that any path or desired motion and dwell times of thepolishing tool 200 over theworkpiece 10 can be achieved. As described previously,workpiece spindle 108 also acts as a servo controlled positioning axis, the motion of which may be controlled in coordination with the described linear and rotary motions such that any non-axially symmetric irregularities, zonal enhancements, in theworkpiece 10 may be also corrected with the polishing method of the present invention.Polishing tool spindle 124 is controlled via a motor and spindle drive (not shown) such that the rotation speed in RPM is variable, and may be adjusted during the polishing process, depending on the process and workpiece requirements. - As was described previously, there are machine configurations for
apparatus 100 that can be provided, depending on the workpiece shape and size, and the desired finished workpiece results. The motions of these axes may be combined so as to not only provide straight, linear, or arcuate motions of thepolishing tool 200, but also to provide zigzag, sinusoidal, rotary or other programmable oscillations, in order to achieve the amount of material that is to be removed and to achieve the resulting surface quality. - Based on the configuration of the
machine 100, the spindles and linear and/or rotational slides thereof, and the type/form or the polishing tool(s) to be used, there are various steps required in the process of the present invention, which results not only in the polishing of the workpiece, but also the correction of the surface errors/form of the workpiece. - In general, the pre-machined (i.e. unfinished) workpiece may be measured with a surface profilometer, an interferometer, a CMM or any other type of measuring device capable of analyzing the geometric shape, in order to quantitatively define the basic starting condition of the workpiece. This information is required to begin the process of improving the components surface roughness, mid-spatial frequency (waviness) and figure. After the analysis, the acquired data on the workpiece is then communicated into the computer control on the machine. This information, along with the software built into the computer control, calculates the process parameters/motion control required giving the desired workpiece improvements.
- The polishing tool spot size and shape is either known based on a library of predetermined empirical parameters obtained experimentally, or it is analyzed through a series of tests. The polishing tool spot size and shape is then sent to the CNC controller. This data is the additional information needed to develop the required polishing tool path motion and speed, and spindle rotational and linear speeds to achieve the desired process results. It is to be understood that the polishing spot size may be affected by the size, shape, material properties, and fill pressure of the bladder, fluid type of the filled bladder, and the polishing foil material properties.
- A more detailed description of methods for using the polishing tools and the apparatus of the present invention will now be described. It is to be understood that the steps in the following descriptions are illustrative of some embodiments of methods, but that the order of the steps described herein may be changed, while still achieving substantially the same end results. Thus, such variations in the methods described herein are to be considered within the scope of the present invention.
- A first preferred step, based upon experience and knowledge of the finishing process and the previously described data obtained on the unfinished part, is to assemble and fit a polishing tool to the polishing apparatus.
FIG. 5 is a flowchart depicting a method of assembly of the preferred polishing tool ofFIG. 2A in the apparatus ofFIG. 1 . Referring toFIG. 5 ,FIG. 1 , andFIG. 2A ,tool setup process 410 begins withstep 412, wherein polishingtool 200 sans polishingring assembly 230 is fitted in holdingchuck 126 ofspindle 124. Subsequently instep 414, polishing ring assembly or foil 230 is selected and fitted tobladder 204 of polishingtool 200.Bladder 204 is inflated to hold polishingring assembly 230 in place thereupon instep 416. A measurement of the center height of polishingring 230 is made with suitable measuring means such as e.g., a dial indicator, a caliper, a micrometer, and the like instep 418. With steps 412-418 completed,tool setup process 410 is complete. Alternatively or additionally, an alignment fixture may be used to aid in proper position/alignment of the foil and or reinforcement ring - The overall preparation/setup of the polishing apparatus then follows.
FIG. 6 is a flowchart depicting a method of preparing the preferred apparatus ofFIG. 1 for a polishing operation. Referring toFIG. 6 , andFIG. 1 , apparatus ormachine setup process 420 begins withstep 422, installing the completed polishingtool assembly 200 inchuck 126 ofspindle 124. (Step 422 is performed in the event thattool 200 was removed fromspindle 124 in order to make themeasurement 418 oftool setup process 410 ofFIG. 5 , or iftool 200 was setup separately frommachine 100.) -
Machine setup process 420 continues withstep 424, in which the polishing tool dimensional data obtained inmeasurement step 418 is entered into the CNC process controller ofmachine 100. The unfinished optic or other workpiece to be polished is then placed into holdingchuck 110 ofspindle 108 instep 426. The data obtained from measurements made on the unfinished optic that have been described previously are also entered intomachine 100 instep 428. Instep 430, an analysis of the spot size/removal function of the polisher on the optic is performed, or such data from a previously described library of tool functions is entered into the CNC process controller. Instep 432, the CNC process controller is further programmed with polishing tool and polishing medium parametric data such as removal function, polishing spot size, polishing tool medium/material type, polishing tool dimensions/shape, polishing tool bladder pressure, optic/workpiece starting and finished dimensions, and polishing slurry type/composition. - With all of the relevant data programmed into the CNC process controller, the deterministic path of the
polishing tool 200 on the optic 10 is calculated by such controller instep 434. In performingmachine setup process 420, depending on the shape and size of theworkpiece 10, coordinate offsets will be established in all of theprogrammable axes machine 100 the information/location ofpart 100such machine 100 will begin the polishing process at the correct location onworkpiece 10. At this point, withmachine setup 420 complete, some test probing of theworkpiece 10 and/or thepolishing tool 200 may be implemented to confirm that such starting location is correct. Once the CNC controller ofmachine 100 has defined/confirmed the “part zero” or starting position of polishingtool 200 uponworkpiece 10, the polishing process may begin. -
FIG. 7 is a flowchart of a complete method of polishing an optic using the apparatus and polishing tool of the present invention. Referring toFIG. 7 ,tool setup process 410, andmachine setup process 420 are performed according to the foregoing descriptions ofFIG. 5 andFIG. 6 . Subsequently, instep 440, the optic polishing cycle is performed, wherein a computer developed path of polishingtool 200 uponworkpiece 10 is performed. As described previously, theworkpiece spindle 108 andpolisher spindle 124 are placed in rotary and linear motion along one or more ofaxes - In some circumstances, more than one bladder-polishing tool may be required to achieve the desired results in polishing
workpiece 10. Accordingly, in one embodiment (not shown),machine 100 is provided with automatic tool changers, to change between multiple polishing tools during the process. In another embodiment (not shown) multiple spindles are provided onmachine 100, wherein a first polishing tool on a first spindle performs part of the polishing operation, a second polishing tool on a second spindle performs part of the polishing operation, and so forth, to the extent that multiple tools and spindles are provided onmachine 100. - In the preferred embodiment of polishing
cycle 440, but not in all embodiments, at such time when thespindles tool 200 alongaxes tool 200 withworkpiece 10, which enhances the polishing action or removal rates of material fromworkpiece 10. As described previously, the path of thepolishing tool 200 over theworkpiece 10 may include straight, linear, arcuate zigzag, sinusoidal, rotary, spiral, or other programmable motions so as to enhance the removal rate of material fromworkpiece 10. - In performing polishing
cycle 440 ofprocess 400 ofFIG. 7 , there are several process parameters that will affect the removal rates and figure enhancement: -
- 1. The rotational speed of the
workpiece spindle 108 may be controlled to give the effect of constant surface speed ofworkpiece 10 similar to that of current CNC lathe technology, so as to maintain a constant removal rate of material from theworkpiece 10. Such control of spindle speed eliminates the effect of the decreasing or increasing diameter of the contact circle made by thepolishing tool 200 upon therotating workpiece 10, as it will be apparent that the surface speed at the extremity (i.e. maximum diameter) of the rotating workpiece is much greater than the surface speed near the center of the workpiece. As thepolishing tool 200 approaches the center of theworkpiece 10, the surface speed approaches zero; thus such a variation in surface speed may be compensated for by varying the rotational speed ofworkpiece spindle 108. - 2. The speed/position of
workpiece 10 may also be controlled so as to improve rotational asymmetries of the workpiece during the polishingcycle 440. For example, if there is an asymmetry that requires more removal in a specific area ofworkpiece 10, then the part spindle may slow or even stop in this area so as to allow more removal by polishingtool 200. Alternatively, the opposite situation may occur wherein less material removal is required and theworkpiece 10 may speed up during polishing in this area to minimize the removal. In other terms, the dwell time of thepolishing tool 200 upon theworkpiece 10 is adjusted to selectively decrease or remove rotational asymmetries. - 3. The “stiffness” of the polishing tool may be preset based upon the inflation pressure within the
bladder 204 oftool 200. Depending on how “hard” or “soft”bladder 204 is made by inflation pressure, the removal function oftool 200 will be affected. Typically a stiffer polishing tool (i.e. higher inflation pressure) will be used where higher removal functions are required such as in processes where form error modification ofworkpiece 10 is needed. Likewise, less inflation pressure will be applied tobladder 204 in a final finishing process where the best possible surface finish is required, at the expense of a lower material removal rate. In a further embodiment described previously, inflation pressure may be varied in real time during the polishingcycle 440. - 4. The compression factor may also be controlled in the polishing
cycle 440. Control of the compression factor is achieved through the CNC program wherein the path thepolishing tool 200 is moved in a less compressed or more compressed path (“tighter” or “looser path”) over the part, thereby affecting its removal function and rate. - 5. The tightness of the zigzag or circular motion of the
polishing tool 200 in its path over theworkpiece 10 may also be adjusted and varied throughout the polishingcycle 440. In one embodiment, the compression factor is held constant while the zigzag or circular motion of thepolishing tool 200 is varied. Circular and other motions such as e.g., zigzag, provide better surface finish i.e. polish without leaving artifacts from the tool/abrasive slurry in the surface i.e., grooving. - 6. The composition, Theological properties, PH, concentration, and flow rate of polishing slurry delivered to the polishing tool/workpiece during the process may be varied to affect removal rates and surface roughness.
- 7. The size, shape, and material properties of the
bladder 204 of polishingtool 200 significantly affects the process results and capabilities depending on theworkpiece 10 to be polished. - 8. The material that the bladder is wrapped with (the foil 230) is another variable, which will also affect the material removal and finishing characteristics during polishing
cycle 440. - 9. The physical properties of the fluid medium used to pressurize
bladder 204 oftool 200 may be varied. Such physical properties include specific gravity, shear viscosity, and extensional viscosity. Variation of such properties between the basic choice of a liquid or a gas is at least several orders or magnitude. However, there is significant variation between liquids, and there is opportunity for further control based on the use of non-Newtonian liquids, such as shear or extensional thickening liquids, shear or extensional thinning liquids, visco-elastic liquids, and/or magneto-rheological liquids.
- 1. The rotational speed of the
- Using variations of the process parameters described in 1-9 above, the removal rates, the surface roughness, mid spatial frequency errors and figure error will be optimized during polishing
cycle 440. Upon completion of polishingcycle 440, themachine 100 ofFIG. 1 is stopped. Referring again toFIG. 7 , and continuing again withprocess 400, the profile of the polished optic or other workpiece is measured instep 450, according to methods previously described. A decision is made atstep 455, wherein if the optic 10 is acceptable against specifications, it proceeds through astep 490 of final measurement/quality control, and/or packaging, and shipping. - If such optic is not acceptable against specifications, steps are taken to prepare for another polishing
cycle 440. Such steps includestep 460, reprogramming of the CNC controller;optional step 470 of setting up/installing/and/or changing to a new polishing tool; and step 480, calculation of a new deterministic path for thenext polishing cycle 440. The second polishing cycle then proceeds as previously described, and further iterations of steps 450-480 and 440 occur until the optic is polished to a condition that is acceptable against specifications, at whichtime step 490 is performed. - Included within the scope of the present invention is another embodiment of a polishing tool for the polishing of concave surfaces.
FIG. 8A is a cross-sectional view of such a preferred polishing tool. Referring toFIG. 8A , polishingtool 300 comprises amandrel 302 within which is disposed agroove 303 around the outer periphery of aflange 305 formed at one end ofmandrel 302.Tool 300 further comprises a dome-shapedbladder 304, having alip 307 that is disposed ingroove 303 ofmandrel 302.Compression washer 306 is fitter over theshank 301 ofmandrel 302 and disposed againstlip 305 ofbladder 304. Lockingnut 308 is threadedly engaged with a corresponding threaded portion ofshank 301, such that lockingnut 308 compresseslip 305 ofbladder 304 intogroove 303 ofmandrel 302, thereby sealingbladder 304 tomandrel 302.Bladder 304 sealed to flange 305 ofmandrel 302 thus forms acavity 316 therebetween. Suitable materials forbladder 304 are e.g., natural or synthetic rubber, silicone, or polyurethane. - Numerous other embodiments of
tool 300 are possible, whereinbladder 304 is formed such thatbladder 304 fully encloses theouter surface 309 of the distal end ofmandrel 302. In one embodiment,bladder 304 is conical, as indicated bydotted lines 311. In other embodiments,bladder 304 may have a parabolic shape, a hyperbolic shape, or combinations and transitions between hemispherical, conical (linear), hyperbolic, and parabolic surfaces at different radial zones along the surface ofbladder 304. Thusbladder 304 may have a precisely hemispherical shape, a precisely conical shape, or a generally curved or domed shape formed by some combination of these various surface definitions. It will be apparent that even in the instance of a conically shapedbladder 304, that such bladder will likely be formed with a slight radius at the apex of such cone. -
Mandrel 302 is further provided with anaxial bore 312 disposed from theouter end 324 ofshank 301 through the center offlange 305, such that theouter end 324 ofmandrel 302 is in communication withcavity 316.Polishing tool 300 further comprises aninflation device 320 such as e.g., a check valve, or a tire valve stem, for providing a means to pressurizecavity 316 and maintain pressure therein, as previously described fortool 200 ofFIG. 2A .Cavity 316 may be pressurized with any suitable fluid such as the liquids or gases previously described in this specification. In a further embodiment,axial bore 312 is connected during the polishing process to an adjustable pressure source, so that the pressure withincavity 316 may be varied in real time during the polishing operation, as described previously in this specification. - It will be apparent that in embodiments in which a relatively dense fluid, i.e. a liquid is used, and in which an elastic bladder is used, that the overall profile of the bladder, and therefore the spot size, can be varied as a function of polishing tool rotational speed. At relatively low rotational speed, a bladder with a substantially hemispherical shape will maintain such shape. As rotational speed is increased, the centrifugal force acting on the liquid contained in the bladder will deform the bladder into a flattened dome profile having a large radius of curvature near the center of the bladder, and a small radius of curvature near the
lip 303 of the bladder. Such a feature can be used in the process of the present invention, wherein the polishing spot size is rendered adjustable as a function of rotational speed. - Referring again to
FIG. 8A , polishingtool 300 further comprises a first ring ordome 332 of backing material disposed over the outer wall ofbladder 304, and a second ring ordome 334 of polishing material adhered todome 332, thereby forming a dual or composite ring or dome. In one embodiment, only a single ring or dome of material is used as the polishing medium, as described and shown forFIG. 4 . Polishing tool is thus used in substantially the same manner as described for polishingtool 200 ofFIG. 2A previously in this specification, with polishingtool 300 being the preferred tool for the polishing of concave surfaces.FIG. 8B is a side elevation view of the polishing tool ofFIG. 8A , in the process of polishing a concave lens. Referring toFIG. 8B , it can be seen that the axis of rotation of polishingtool 300 is preferably disposed at an obtuse angle 50 with respect to the axis of rotation ofconcave lens 20, in order to achieve the desired contact between polishingsurface 334 oftoll 300 andconcave surface 22 oflens 20. -
FIG. 9 is a schematic representation of another preferred polishing apparatus for polishing concave spheres, aspheres, convex spheres, or other conformal shapes, such aslens 20 ofFIG. 8B . Referring toFIG. 9 ,apparatus 150 is in one embodiment substantially similar toapparatus 100 ofFIG. 1 , with the main difference being provisions to contact the polishing tool with the concave surface of the workpiece. In order to accomplish this, the first preferred provision is the use oftool 300 ofFIG. 8A , having a hemispherical, domed, or conical shape. A second preferred provision is inapparatus 150 wherein aB axis 152 directed into/out of the plane ofFIG. 9 is provided, upon whichpolishing tool spindle 124 is mounted, and upon whichpolishing tool spindle 124 is bidirectionally rotatable, as indicated byarcuate arrow 154. Such a provision enables polishingtool 300 to be moved as indicated byarcuate arrow 156 into a position wherein the axis of rotation of polishingtool 300 is disposed at an obtuse angle 50 with respect to the axis of rotation ofconcave workpiece 20, as indicated inFIG. 8B . Such motion enables the polishingfoil 334 of polishingtool 300 to contact the concave surface of a workpiece such as a concave lens or an asphere without having another portion of the polishing tool colliding with such workpiece. - It is to be understood that the
machine 100 ofFIG. 1 , and themachine 150 ofFIG. 9 that are provided to executeprocess 400 ofFIG. 7 , usingtools 200 ofFIG. 2A andtool 300 ofFIG. 8A may have many different configurations. Axes types, spindle types, layout, size, provision of an automatic tool changer, and overall cost are just a few of the variables that could affect the desired design. While only show two specific possible machine configurations and specific possible tooling configurations are described in this specification and shown inFIGS. 1 and 9 , it is to be further understood that many multi-axis CNC machine tools are known in the art, which can be suitably configured to use thepolishing tools process 400 of the present invention. - The overall
computerized polishing process 400 using theapparatus 100 and polishingtool 200 of the present invention has many distinct advantages over prior art figure/polishing enhancement techniques, which are as follows: -
- 1. There are numerous options available with respect to size and shape of the bladder attached to the tool, such as a tire shape, hemisphere shape, domed shape, conical shapes, cylindrical shape, and the like. The shape of the bladder chosen depends on the part geometry and the desired process results. There are also options available in the choice of material composition and properties of the bladder. These options of size, shape, and material composition render the process of the present invention very versatile.
- 2. Bladder inflation pressure is easily adjusted before the process begins and for many polishing process requirements, no pressure modification is required during the polishing process. In the event that it is desirable to adjust bladder pressure during the polishing process, a polishing tool and apparatus can be made to provide such additional process versatility.
- 3. The method of inflating the bladder into the polishing foil makes replacement of the foil very simple, and typically no adhesive or mechanisms are required for attaching the foil to the bladder. Adhesive is only required to attach the foil to the PET ring.
- 4. In using the polishing tools of the present invention, many types of materials may be wrapped around the bladder, thus allowing for the use of a wide variety of polishing foil media. Polishing foils may be made of e.g. polyurethanes, felts, synthetics, corks, leathers, and many other materials, depending on the desired polishing results. The foils may be impregnated with cerium, diamond, alumina, pitch, etc.
- 5. The preferred method of placing the ring or foil upon the bladder also allows for modification of the shape of the foil or ring, i.e. the width, radius/contour or thickness thereof.
- 6. In the preferred embodiment, the poly(ethylene terephthalate) ring that the foil may be attached to has not only great strength but also long lasting flexibility, which greatly extend the life of the polishing tool.
- 7. The concept of the bladder tool allows for flexibility so that the polisher can conform to a variety of workpiece surface geometries and still maintain contact/polishing action upon such surfaces.
- 8. In contrast to small spot polishing tools, the bladder polisher of the present invention will last and hold its shape much longer in operation. A polishing ring of material, and not just single spot develops the spot in the polishing tool and the process of the present invention, so the polishing surface area of the tool is greatly increased.
- 9. The compression amount and spot size of the polishing tool can be easily adjusted by modifying the computer program to move the tool closer or further from the part in its path over such part.
- 10. Because of the variety of shapes and types of materials that the various components of the polishing tool can be made from, the polishing process of the present invention has the flexibility to repair figure errors in a workpiece, and also achieve the highest surface quality requirements of such workpiece.
- 11. In instances where the process may require one or more polishing tools to achieve the final results, this is easily accomplished with known machine tool automatic tool changing technology or multiple spindle technology, depending on the configuration of the particular machine.
- 12. The powerful computer control algorithms provide the machine operator with a variety of flexible programs which, depending on desired results, can be easily modified and implemented, such as e.g., zigzag, circular, orbital, elliptical tool paths.
- 13. Polishing of steels and other metallic components, especially those used in injection molds, and thin film coating dies can be done without the current technological limitations of prior art polishing processes.
- In another preferred embodiment, the polishing tool further comprises actuation means to engage and/or extend and/or position and/or compress the inflatable bladder or other compliant part, and any polishing foil disposed thereupon, with respect to the part to be improved or polished. Such actuation means may comprise one or more linear actuating devices such as e.g., air operated or hydraulically operated cylinders.
-
FIG. 10 is a first perspective view of one such preferred polishing tool of the present invention comprising single cylinder actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished.FIG. 11 is a side elevation view of the polishing tool ofFIG. 10 ;FIG. 12 is a top view of the polishing tool ofFIG. 10 ; andFIG. 13 is a second perspective view of the polishing tool ofFIG. 10 , taken from the plate side of the polishing tool. - Referring to
FIGS. 10-13 , polishingtool 500 comprises a base 502 to which various components are affixed. In the preferred embodiment,base 502 comprises a rigid plate of material such as steel, aluminum, or fiber reinforced polymer. Other base materials and or structures, such as a frame structure may be suitable, with the operative requirement being that the base is rigid enough to hold components attached thereto in sufficiently precise dimensional relationships so as to enable the overall precision polishing operation to be performed; and that the base is provided with provisions to enable the attachment of components thereto. - Toward the
proximal end 504 ofbase 502,drive wheel 510 is operatively joined or attached torotatable shaft 512, which is disposed in ahousing 514 joined tobase 502.Housing 514 is preferably joined tobase 502 by threaded fasteners (not shown) engaged with tapped holes (not shown) therein, or by other suitable means.Rotatable shaft 512 is preferably disposed within means for enabling precise rotation, such as e.g., a bushing, or more preferably,bearings 516. -
Tool 500 further comprises apolishing wheel 520, which is joined tolinkage 530.Linkage 530 is operatively attached to actuating means 540, such that actuating means 540 actuateslinkage 530, and thus moves polishingwheel 520, as indicated bybidirectional arrow 599. This motion of polishingwheel 520 serves to engage a polishing foil with a portion of the perimeters of polishingwheel 520 and drivewheel 510; such engagement will be described subsequently in this specification. - In the preferred embodiment depicted in
FIGS. 10-13 , actuating means 540 is a linear actuator, and in particular, actuating means 540 a pressure drivencylinder 542.Linkage 530 in this embodiment is aclevis 532 that is operatively joined tocylinder rod 544.Polishing wheel 520 is joined to clevis 532 byshoulder bolt 534, which passes through a hole in the center ofwheel 520, and engages withnut 536. The position ofwheel 520 is preferably maintained constant withinclevis 532 by the use ofspacing washers wheel 520 is provided with at least one bushing or bearing to minimize wear, friction and heat buildup, and to provide precise positional control in the event that polishing wheel is operated at high speeds. - Referring again to
FIGS. 10-13 ,cylinder 542 is joined tobase 502 at its proximal end by ashoulder bolt 547, which passes throughbracket 543, and which is engaged with threadedhole 508 inbase 502.Cylinder 542 is properly spaced out frombase 502 by the use ofjig bushing 546, through whichbolt 547 also passes.Cylinder 542 is further joined tobase 502 at its distal end by mountingnut 548, which is threadedly engaged with thehousing 545 ofcylinder 542, and also engaged withbracket 550.Bracket 550 is fastened to thedistal end 506 ofbase 502 by threadedfasteners -
Cylinder 542 is thus rigidly secured tobase 502, and thus in the operation of the tool 500 (to be described subsequently in this specification),cylinder 542 linearly actuates polishingwheel 520 as indicated bybidirectional arrow 599. To accomplish such actuation,cylinder 542 is operatively connected to a pressurized fluid supply atports housing 545 thereof, preferably provided through flexible hoses (not shown). Such fluid supply is selectable and switchable, i.e. fluid pressure may be applied atport 556 and fluid vacuum may be applied atport 558 to actuatewheel 520 away fromdistal end 506 ofbase 502 and toward the work piece 112 (seeFIG. 18A ), and fluid pressure may be applied atport 558 and fluid vacuum may be applied atport 556 to actuatewheel 520 towarddistal end 506 ofbase 502 and away from thework piece 112. Such fluid cylinder actuating devices are well known. In addition, the pressurized fluid supply (not shown) may provide a pressurized gas such as air (i.e.cylinder 542 is an air cylinder), or pressurized fluid supply may provide a pressurized liquid such as a hydraulic oil (i.e.cylinder 542 is a hydraulic cylinder). - It will be apparent that actuating means 540 may comprise suitable linear actuators other than fluid pressure driven cylinders; many other linear actuators, such as rodless cylinders, stepper motors and other electromechanical actuators are well known and are to be considered within the scope of the present invention. Such linear actuators may be further provided with position sensing means, and/or position control means, and communication means for control thereof by an external process controller.
-
Tool 500 further comprises a polishing foil 680 (seeFIG. 14 ), which is engaged with a portion of the perimeters ofdrive wheel 510 and polishingwheel 520.Polishing foil 680 thus has the function of a drive belt, rotationallycoupling drive wheel 510 and polishingwheel 520 as indicated byarrows arrows foil 680 is not shown inFIGS. 10-13 .Polishing foil 680 is shown inFIGS. 14-18B in the two-cylinder embodiment depicted therein. -
Polishing foil 680 is also shown inFIGS. 22A and 22B , for the purpose of illustrating the manner of engagement thereof withdrive wheel 510 and polishingwheel 520, and for illustrating the preferred properties of polishingfoil 680. -
FIG. 22A andFIG. 22B are schematic representations of means for engaging a polishing foil of thepolishing tool 500 ofFIGS. 10-13 .FIG. 22A depicts such engagement means in the retracted, or unengaged position, andFIG. 22B depicts such engagement means in the deployed, or engaged position. It is to be understood that the following description is also applicable to thepolishing tool 600 ofFIGS. 14-18B . - Referring to
FIG. 22A , it can be seen that engagement means 540 comprisingcylinder 542 is in the retracted position, as indicated by the short length ofcylinder rod 544 that is visible therein. In the embodiment depicted inFIG. 22A and 22B , polishingfoil 680 comprises an assembly similar to that described forring assembly 230 oftool 200 ofFIGS. 2A, 2B , 3, and 4, having abelt 682 of material and anabrasive ring 684. -
Belt 682 is formed of an elastic material. In one embodiment,belt 682 consists essentially of a band of poly(ethylene terephthalate) having a thickness of between about 50 microns and about 2000 microns, and a width of between about 7 millimeters and about 125 millimeters. In another embodiments,belt 682 consists essentially of elastomers such as e.g., gum rubbers, polyurethane, silicone and the like. Many other belt materials may be suitable, with the operative requirement being thatbelt 682 have sufficient elasticity to stretch whenrod 544 ofcylinder 542 is deployed as shown inFIG. 22B , and that the outer surface ofbelt 682 is engageable with the inner surface ofabrasive ring 684, either by friction, or by engagement features in the surfaces thereof, or by other means. - The
abrasive ring 684 offoil 680 is made of a material of sufficient structural strength to withstand the high shear and tensile forces during polishing, and to resist degradation through exposure to the polishing/lubricating fluid, such as e.g. polyurethanes of various durometers; water resistant high strength cloth materials, and various types of felt, cork, and metal.Abrasive ring 684 further comprises abrasive particles embedded therein, or coated on the outer surface thereof, such as e.g. resin bonded diamond, alumina, and/or zirconium and the like.Abrasive ring 684 may have an inner surface having different types of backings, and/or patterns for engagement withbelt 682. -
Abrasive ring 684 preferably has a thickness of between about 1 millimeter and about 5 millimeters, and a width of between about 7 millimeters and about 125 millimeters. Additional operative requirements ofabrasive ring 684 are that it have a greater circumference thanbelt 682, and that it is substantially inelastic, or significantly less elastic thanbelt 682, in order to enable proper engagement therewith. - The engagement of
belt 682 withabrasive ring 684 is now described. Referring again toFIGS. 22A ,belt 682 has been stretched at least slightly, and has been fitted such thatbelt 682 is engaged with portions of the perimeters ofdrive wheel 510 and polishingwheel 520.Belt 682 is thus under some tension, and whendrive wheel 510 rotates as indicated byarrow 597,belt 682 is displaced as indicated byarrows 594, thereby resulting in rotation of polishingwheel 520 as indicated byarrow 598. - As can be seen in
FIG. 22A , withrod 544 ofcylinder 542 retracted,abrasive ring 684 is not engaged withbelt 682, as indicated bygap 683 that is present betweenbelt 682 andring 684. Referring toFIG. 22B , when therod 544 ofcylinder 542 is deployed, polishingwheel 520 is displaced away fromcylinder 542.Belt 682, being of an elastic material, stretches to the extent required to accommodate such displacement ofwheel 520.Abrasive ring 684, however, being of a relatively inelastic material compared tobelt 682, has not stretched, and has instead become engaged withbelt 682 by friction, and/or by engagement features disposed on the contiguous surfaces thereof. - The rotation of
drive wheel 520 in such circumstances thus results in the displacement of abrasive ring as indicated byarrows 593. Essentially, the actuation ofcylinder 542 as indicated byarrow 599, in combination with the components attached thereto, acts as a clutch mechanism to engage and driveabrasive ring 684. - In another embodiment, polishing
foil 680 may be formed as a unitary structure in a manner similar to ring 230 ofFIG. 4 as described previously, but having both the required properties of a drive belt for engagement with wheels or pulleys, and an abrasive belt for polishing or more substantial surface removal, as well as having the requisite elastic properties as previously described. The applicant believes that the belt and ring structure is preferred, as such components are more easily and inexpensively provided, and such structure enables simple and rapid changeover between belts comprised of various abrasive media, either manually, or by automatic tool changing means. - In order to have good function as a drive belt engaged with wheels, polishing
foil 680 may be provided with features known in drive belt art, such as grooves (not shown) on the inner surface thereof (mated with corresponding grooves inwheels 510 and 520); or teeth (not shown) on the inner surface thereof (mated with corresponding teeth inwheels Drive wheel 520 may further be provided with rims extending radially outward from the edges thereof for improved belt retention, as is commonly done with drive pulleys. -
Polishing foil 680 may vary in length from about 4 inches for tools having pulleys on the order of 0.25-0.5 inches in diameter to about 50 inches for tools having pulleys on the order of 8 inches in diameter. The rotational speed ofdrive wheel 510 is provided such that the surface speed of polishingfoil 680 is between about 2 and about 1000 inches per second, depending upon the particular polishing application.Polishing foil 680 may further comprise fiber reinforcements disposed therein, and may comprise woven or cloth-like material, provided that sufficient elasticity is provided as described herein. - Referring once again to
FIGS. 10-13 ,tool 500 further comprises adowel pin 559 extending outwardly from and joined to base 502 by engagement with a threaded hole therein, or by an interference fit with a hole therein, or by other suitable means such as e.g. welding or adhesive.Dowel pin 559 is utilized to attach and/or stabilizetool 500 when it is engaged with drive means such as a CNC machine and used to polish an object. The details of such use will be described subsequently in this specification with reference toFIGS. 19-21 .Tool 500 is preferably used in a multi-axis CNC apparatus for the polishing of objects; however,tool 500 may be engaged with a variety of more simple or more complex drive means, and used for many other surface polishing or surface abrasion applications. In one embodiment,tool 500 may simply be provided with an air motor or electric motor attached thereto as drive means, and placed in contact with the object to be worked. - Thus
tool 500 may be fabricated at a variety of scales, depending upon the particular application, and in particular, the size, shape, and degree of finishing required of the part to be worked. The diameters ofdrive wheel 510 and polishingwheel 520 may vary from about 0.25 inches to about 8 inches. The scale of the other components, i.e.base 502,cylinder 542, andlinkage 530 would be sized as required to operatedrive wheel 510 and polishingwheel 520 and thefoil 680 engaged therewith. For example,cylinder 542 may be provided with a bore of between about 0.1 inch and about three inches. - Although it appears in the embodiment shown in
FIGS. 10-13 that the diameters ofdrive wheel 510 and polishingwheel 520 are approximately equal, this is not an operating requirement. To the contrary, in some applications, it is advantageous to either increase the rotational speed ofpolishing wheel 520 or decrease the speed ofpolishing wheel 520 with respect to drivewheel 510, by providingpolishing wheel 520 with a different diameter thandrive wheel 510. The ratio of polishing wheel diameter to drive wheel diameter may vary from as much as about 1:10 to about 10:1, depending upon the application. -
Polishing foil 680 may vary in width from about 0.25 to about 5 inches. The corresponding widths ofdrive wheel 510 and polishingwheel 520 thus vary in a similar manner in order to properly engage with and drive polishingfoil 680. - The length of actuation stroke of means 540 (indicated by arrow 599) may vary from about 0.1 inch to about 3 inches, depending upon the scale of
tool 500, and upon the degree of elasticity provided in polishingfoil 680. - Referring again to
FIGS. 10-13 , and in the preferred embodiment depicted therein, polishingwheel 520 is preferably provided with a generallyarcuate surface 521, and more preferably a spherical surface.Polishing foil 680, which is under tension from the action of actuation means 540, conforms to thissurface 521 as it wraps around the perimeter of polishingwheel 520 during a polishing operation. This wrapping action results in better tracking of polishingfoil 680 on polishingwheel 520. In addition, the radius of curvature and/or the curvature profile (spherical, elliptical, hyperbolic, etc.) ofarcuate surface 521 partially determines the tool spot size during a polishing operation. Tool spot size has been described previously in this specification. - Referring to
FIG. 12 , in a further embodiment,wheel 520 is provided with acavity 522 formed within the interior thereof, and apassageway 524 from the exterior ofwheel 520 tocavity 522.Cavity 522 may thus be pressurized with various fluids during a polishing operation, as described previously in this specification with reference totool 200 of FIGS. 2A and 2B, andtool 300 ofFIGS. 8A and 8B .Passageway 524 may be further provided with an inflation device, such asinflation device 220 ofFIG. 2A . In one embodiment,inflation device 220 is preferably a simple, inexpensive check valve. In a preferred embodiment, inflation device is a valve stem, or the inner workings thereof commonly used for the inflation of tubeless tires. Alternatively, inflation device may comprise a miniature check valve, such as one of many manufactured and sold by the Lee Company of Westbrook, Conn. -
Polishing wheel 520 may be formed of suitable elastomers such as rubber, polyurethane, or silicone, or a harder or higher durometer polymer. The selection of material for polishingwheel 520 will depend upon whether or not polishingwheel 520 is provided with a cavity therein for pressurization, the extent to which such cavity may be pressurized and thus deformed, and the desired tool spot size during the polishing operation. These variables have been described in detail in this specification with regard totool 200 ofFIGS. 2A and 2B , and are also generally applicable to polishingwheel 520. In the preferred embodiment, polishingwheel 520 comprises a hub of solid material such as e.g. a plastic, ferrous, or non-ferrous metal (optionally including a bearing or bushing), and an exterior portion of elastomer (optionally including a pressurizable cavity therein), upon the perimeter of which is engaged the polishing foil. In the embodiment wherein polishing wheel does not include a pressurizable cavity therein, and is instead a solid elastomeric material, it is preferable that such elastomeric material be of a durometer between about 10 and about 90, with the particular durometer depending upon the polishing application. - In other embodiments, and depending upon the particular object to be polished or otherwise finished, polishing wheel may be formed with a plano (cylindrical) surface, or a convex surface.
Polishing wheel 520 may also be formed with circumferential grooves onsurface 521, or axial grooves (such as e.g. a timing pulley), and/or a texture such as knurling. These various surfaces may be employed to improve the tracking and/or traction betweenpolishing wheel 520 andfoil 680, thereby preventing slippage therebetween. These various surfaces may be further employed advantageously in that such surfaces may be used to cause high frequency vibrations of polishingwheel 520 and foil 680 against the part to be finished, thereby enhancing the polishing effect oftool 500. -
FIG. 14 is a first perspective view of another preferred polishing tool of the present invention comprising twin cylinder actuation means to engage the polishing foil, and to extend and/or position the inflatable bladder or other compliant part, and the polishing foil disposed thereupon, with respect to the part to be improved or polished.FIG. 15 is a side elevation view of the polishing tool ofFIG. 14 ;FIG. 16 is a top view of the polishing tool ofFIG. 14 ; andFIG. 17 is a second perspective view of the polishing tool ofFIG. 14 , taken from the plate side of the polishing tool. It will be apparent that much of the structure of the embodiment depicted inFIGS. 14-17 is substantially the same as the embodiment depicted inFIGS. 10-13 , with the main difference being the provision of twin cylinder actuation means in the embodiment ofFIGS. 14-17 . Accordingly, in the following description, only the twin cylinder actuation means will be described in detail, with the remaining structure and function oftool 600 ofFIGS. 14-17 being as described fortool 500 ofFIGS. 10-13 . - Referring to
FIGS. 14-17 ,tool 600 comprisesbase 602,drive wheel 610 joined toshaft 612, polishingwheel 620,dowel pin 659, and polishingfoil 680.Tool 600 further comprises actuation means 640, which further preferably comprises a first linear actuator and a second linear actuator. The first linear actuator is preferably acylinder 642, and the second linear actuator is preferably acylinder 662.First cylinder 642 is operatively connected to polishingwheel 620 byclevis 632, and thus provides linear actuation of polishing wheel as indicated bybidirectional arrow 699, in a manner similar to that described previously fortool 500 ofFIGS. 10-13 . -
Second cylinder 662 is joined at the proximal end thereof byshoulder bolt 667, which passes throughbracket 663 andspacer 666, and which is threadedly engaged with a tapped hole inbase 602.Second cylinder 662 also provides linear actuation ofrod 664 andclevis 633 inwardly and outwardly fromcylinder body 665 as indicated bybidirectional arrow 696. Sincecylinder 662 is rotatable aboutshoulder bolt 667, this linear actuation ofclevis 633 results in motion of the distal end ofcylinder 642, andclevis 632 and polishingwheel 620 along a generally arcuate path as indicated bybidirectional arrow 695. This arcuate motion enables polishingwheel 620 and polishingfoil 680 to be more effectively engaged with and compressed against the object to be polished, as will be subsequently explained with reference toFIGS. 18A and 18B . - Referring again to
FIGS. 14-17 ,clevis 633 is joined tocylinder rod 664 and also to lockplate 670 byshoulder bolt 672.Lock plate 670 is also joined to thebody 645 ofcylinder 642, and lock plate is movably joined tobase 602 byshoulder bolt 674, which passes through slotted opening 676 inlock plate 670. Referring toFIGS. 15A and 15B in particular,FIG. 15A depicts the position of polishingwheel 620 withcylinder 662 fully retracted.FIG. 15B depicts the position of polishingwheel 620 withcylinder 662 fully deployed. It can be seen thatlock plate 670 is displaced downwardly and outwardly resulting from the freedom of motion alongslot 676, resulting in the arcuate motion of polishingwheel 620 and foil 680 as indicated byarcuate arrow 695. It will be apparent that many other combinations of a second linear actuator joined to a first linear actuator by a movable bracket, hinge, or other means can provide a suitable arcuate motion of polishingwheel 620, and thus all such combinations of linear actuators are comprehended within the scope of the present invention. - It is also noted that in the embodiment of
tool 600 depicted inFIG. 17 , althoughport hole 607 inplate 602 is depicted as being circular,port hole 607 may be oblong in the vertical direction, or of larger diameter. This variation in shape may be necessary because the arcuate motion of polishingwheel 620 as indicated by arrow 655 inFIG. 15B that results whencylinder 662 is deployed. This deployment and retraction ofcylinder 662 causes the rod end ofcylinder 642 to pivot up and down vertically as described previously. Since there is provided hydraulic fittings (not shown) connected tocylinder 642 throughholes cylinder 662 throughhole 607 has some significant amount of vertical travel, it may be necessary to enlarge or make oblong shapedhole 607, in order to provide operating clearance for such fittings and/or hose to move withinhole 607 whencylinder 662 is deployed. - In a further embodiment, there is provided the tool of
FIGS. 14-17 , but with a simple pivotable link (not shown) in place ofcylinder 642. In such an embodiment, there is preferably used a polishingfoil 680 that is unitary in construction and that is elastic, such that polishingfoil 680 is stretched overdrive wheel 610 and polishingwheel 620, and engaged therewith. Thus first linear actuation means 640 comprisingcylinder 642 is not provided. In the operation of such a tool,cylinder 642 provides the arcuate motion of polishingwheel 620, withwheel 620 pivoting along an arcuate path defined by the rigid link (not shown) provided in lieu ofcylinder 642. (Substantially the same result could be obtained ifcylinder 642 oftool 600 ofFIG. 14 were locked in a fixed position, such thatcylinder 642 would function as a rigid link.) -
FIG. 18A is a cross-sectional elevation view of the polishing tool ofFIG. 14 , shown disengaged with a deeply concave object to be polished; andFIG. 18B is a cross-sectional elevation view of the polishing tool ofFIG. 14 , shown engaged from a deeply concave object to be polished. Referring toFIG. 18A , it can be seen thatcylinder 662 is fully retracted as depicted inFIG. 15A , and that polishingwheel 620 and foil 680 are not in contact withobject 112, there being agap 114 between theinner surface 116 ofobject 112 and polishingfoil 680. Referring toFIG. 18B , it can be seen that whencylinder 662 is subsequently fully deployed as depicted inFIG. 15B , polishingwheel 620 and foil 680 move along an arcuate path and make contact withobject 112. - The fluid pressure applied to
cylinder 642 and tocylinder 662 are among the parameters that determine the amount of force applied by polishingwheel 620 and foil 680 to theobject 112, and which thus determine the tool spot size. Other parameters that determine such force and tool spot size are as described previously in this specification fortool 200 ofFIGS. 2A and 2B , andtool 300 ofFIGS. 8A and 8B . - In addition to the polishing tools described herein, and in accordance with the present invention, there is provided an apparatus for polishing objects comprising a computer numerically controlled (CNC) machine in which is fitted one of the tools of the present invention as depicted in
FIGS. 10-18A . Various embodiments of such apparatus are depicted inFIGS. 19, 20 , and 21. -
FIG. 19 is a perspective view of a first preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished.FIG. 20 is a perspective view of a second preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished.FIG. 21 is a perspective view of a third preferred polishing apparatus of the present invention comprising a polishing tool having actuation means to extend and/or position the inflatable bladder or other compliant part with respect to the part to be improved or polished. - Referring to
FIGS. 19-21 , each of the apparatus therein are described with respect to theorthogonal x axis 107,y axis 105, andz axis 121 depicted therein.CNC machine 1000 is similar to that depicted in polishingapparatus 100 ofFIG. 1 , comprising a base 102 that supports Y-axislinear slide 104, the motion of which is bi-directional along Y-axis 105 as indicated byarrow 999.Linear slide 106, the motion of which is bi-directional alongX-axis 107 as indicated byarrow 998, is mounted upon Y-axislinear slide 104. Theselinear slides -
CNC machine 1000 further comprisesvertical slide 120 attached to polishing machine frame orplate 123, which is joined tobase 102. The motion ofvertical slide 120 is bi-directional along Z-axis 121 as indicated byarrow 997.CNC machine 1000 is preferably provided withrotary axis 151, which is mounted uponvertical slide 120, and which is rotatable around B axis 152 (parallel to Z-axis 121) as indicated bybidirectional arrow 154.Polishing tool spindle 124 is attached torotary axis 151.CNC machine 1000 further comprises arotatable chucking device 126 attached to the end of polishingtool spindle 124, in which thedrive shaft 612polishing tool 600 of the present invention is inserted and rotated.Polishing tool 600 is positionable in a variety of orientations, several of which are depicted inFIGS. 19-21 , depending upon the particular object to be polished.Polishing tool 600 is further affixed by a linkage (not shown), which attaches to pin 659 and which is joined tospindle 124, thereby immobilizingbase 602 and preventing overall rotation oftool 600 byspindle 124. Thus only thedrive shaft 612 oftool 600 is rotatable byspindle 124, while the remainder oftool 600 is held in position relative to object 112 to be polished. - Referring now only to
FIG. 19 , and in the embodiment depicted therein,apparatus 1010 comprisesCNC machine 1000 further comprised of awork piece spindle 108 mounted uponlinear slide 106. The motion ofspindle 108 is bidirectionally programmable alongaxis 109, which is parallel to X-axis 107. Thusspindle 108 is movable by computer control alongaxis 109, depending on the requirements or the polishing process. The motion ofobject 112 in the X-Y plane with respect totool 600 is programmable, and is performed byslides - Rotatable work
piece chucking device 110 is attached to end ofwork piece spindle 108. Thework piece 112 to be polished is engaged and held bychuck 110 and rotated byspindle 108 around the centralrotary axis 109 thereof as indicated byarrow 996. This rotary motion ofobject 112 results in the surface motion thereof being orthogonal to the motion of the polishing foil 680 (seeFIG. 14 ) oftool 600. In this manner, such orthogonal motion of the object surface with respect to the foil substantially eliminates any “grooving” effect in the object surface by the polishing foil. - Referring now only to
FIG. 20 , and in the embodiment depicted therein,apparatus 1020 comprisesCNC machine 1000 further comprised of awork piece spindle 162 mounted uponlinear slide 106.Apparatus 1020 is similar toapparatus 1010 ofFIG. 19 , with the differences being in the orientation of theobject 112 and the use of various slides and spindles to provide the relative motion betweentool 600 andobject 112.Spindle 162 is a vertically disposed spindle, thecentral axis 169 of which is parallel to Z-axis 121. Rotatable workpiece chucking device 164 is attached to end ofwork piece spindle 162. Thework piece 112 to be polished is engaged and held bychuck 164 and rotated byspindle 162 around the centralrotary axis 169 thereof as indicated byarrow 995. - The motion of
spindle 162 is bidirectionally programmable along theX axis 107 and theY axis 105, both of which are perpendicular to the central axis ofrotation 169 ofobject 112. To provide motion oftool 600 toward and away fromobject 112 in the direction ofZ axis 121,rotary axis 151 andspindle 124 are rotated 90 degrees clockwise from their respective positions inFIG. 19 , and slide 120 is used to movetool 600 axially in the Z direction. - Referring now only to
FIG. 21 , and in the embodiment depicted therein,apparatus 1030 is substantially the same asapparatus 1020 depicted inFIG. 20 in terms of components.Apparatus 1030 differs in setup in the position ofspindle 162 onslide 106, and in the extent of rotation ofrotary axis 151 andspindle 124, such rotation being about 30 degrees clockwise from their respective positions inFIG. 19 . In addition,spindle 162 is locked, thereby preventing rotation ofobject 114, sinceobject 114 is not axisymmetric. In the embodiment depicted inFIG. 21 ,object 114 is an equilateral prism, which thus requires the rotation ofrotary axis 151 andspindle 124 of about 30 degrees. During the polishing operation,prism 114 is moved in the X and Y directions by the motion ofslides tool 600.Tool 600 is moved in the Z-direction byslide 120, thereby enabling the foil 680 (seeFIG. 14 ) oftool 600 to traverse up and down the slopedface 115 ofprism 114. - In a further embodiment, the
CNC machine 1000 is programmed to articulatetool 600 over thesurface 115 ofobject 114 in a more complex path in X-Y-Z space. For example,tool 600 may be generally advanced along a linear path, but with a circular motion superimposed on such linear path. Such a tool path is known in the art as a trichordal path. Alternatively, and as described previously for the embodiments ofFIGS. 1-9 , such tool paths may include arcuate, zigzag, sinusoidal, or other combinations of motion so as to enhance the removal rate of material fromobject 114, and to prevent the occurrence of any “grooving” effect in the object surface during the polishing thereof. - It will be apparent that many other apparatus configurations are possible in fitting the tools of the present invention to CNC machines to polish and/or grind and/or otherwise finish objects. Such CNC machines may have more or fewer linear and rotational actuators as required by the particular application.
- It will be further apparent that the polishing methods described herein and depicted in
FIGS. 5, 6 , and 7 for the operation ofapparatus 100 ofFIG. 1 andapparatus 150 ofFIG. 9 , usingtool 200 ofFIG. 2A andtool 300 ofFIG. 8A are readily adaptable totool 500 ofFIGS. 10-13 andtool 600 ofFIGS. 14-17 , when such tools are fitted toapparatus FIGS. 19-21 respectively. In general, such methods may in some embodiments only differ by the setups of theparticular tools FIG. 10 ) orcylinders 642 and 662 (seeFIG. 14 ). - It will be apparent that there are many other apparatus configurations comprising actuation means that can increase the separation distance between two wheels, thereby providing increased tension of a belt engaged therewith; or that can increase the belt path length therearound (such as by an idler pulley), thereby providing increased tension of a belt engaged therewith, and that such actuation means are considered within the scope of the present invention. It will be apparent that there are many other apparatus configurations comprising actuation means that can adjust the position of a first wheel engaged to a second wheel by a belt, either along an arcuate path or a linear path or a combination thereof, and that such actuation means are also considered within the scope of the present invention.
- In accordance with the present invention, another tool is provided that may perform similar polishing operations as those tools shown in
FIG. 2A -FIG. 4 and described herein. This tool shares the common principle of providing a force from within a flexible tool material which results in the formation of a curved surface of an elastomeric bladder. A polishing foil is disposed upon the bladder, and polishing of an object is performed by the tool at the point of contact of the foil on the curved surface with the surface of the object. Instead of using the force of a pressurized fluid within a cavity inside the bladder to produce the curved surface, there is provided an axial compressive force upon the bladder, which causes such bladder to be deformed outwardly orthogonally in the radial direction, thereby producing a curved surface that can be used for polishing in substantially the same manner as has been described herein for the tools shown inFIG. 2A -FIG. 4 . -
FIG. 23A, 25A , and 26A are a perspective view, a side cross-sectional view, and a side view, respectively, of a solid bladder polishing tool of the present invention depicted in an uncompressed state; andFIG. 24 is an exploded perspective view of the solid bladder polishing tool ofFIG. 23A , exploded along theaxis 23A-23A. Referring toFIGS. 23A, 24 , 25A, and 26A,tool 700 comprises a main body orbladder mandrel 710 having adrive shank 712 at aproximal end 711 thereof, and aflange 718 at adistal end 719 thereof, upon whichsolid bladder 730 is disposed and engaged therewith.Mandrel 710 further comprises abladder shank 714 extending upwardly fromflange 718, and a threadedshank 716 extending downwardly fromdrive shank 712, joiningbladder shank 714 atstop shoulder 715. -
Solid bladder 730 has a generally annular shape and is fitted overmandrel 710 such that when assembled,bladder shank 714 ofbladder mandrel 710 is disposed within inner bore 732 ofsolid bladder 730.Upper surface 734 andlower surface 736 ofsolid bladder 730 are in contact with thelower surface 742 ofcompression washer 740 andupper surface 717 offlange 718, respectively. -
Compression collar 750 is slid overdrive shank 711 ofmandrel 710, and is positioned alongmandrel 710 proximate to threadedshank 716; however,compression collar 750 is not engaged with the threads of threadedshank 716.Nut 760 is engaged with the threads of threadedshank 716 ofmandrel 710, thereby applying an axial force againstcompression collar 750, andcompression washer 740. Thusnut 760 can be tightened so thatcompression washer 740 andflange 718 ofmandrel 710 to apply a compressive force againstsolid bladder 730 as indicated byarrows 799 and 798 (seeFIG. 25B ), thereby enabling the engagement ofbladder 730 with polishingband 770, as will be explained presently. For the sake of simplicity of illustration, it is noted that polishingband 770 oftool 700 is not shown inFIG. 25A . - The assembly and preparation of
tool 710 for polishing use will now be described. Such assembly and preparation is best understood with reference toFIG. 24 andFIGS. 23B, 25B , and 26B, which are a perspective view, a side cross-sectional view, and a side view, respectively, of a solid bladder polishing tool of the present invention depicted in a compressed state. Referring toFIGS. 25A and 25B , and beginning with thetool 700 assembled in an uncompressed state as shown inFIG. 25A ,nut 760 is tightened, drivingcompression washer 740 towardflange 718 ofmandrel 710, as indicated byarrows inner shoulder 755 ofcompression collar 750 is also driven towardstop shoulder 715 ofmandrel 710, as indicated byarrow 797.Nut 760 is tightened, preferably by engaging a first wrench (not shown) withnut 760 and a second wrench (not shown) with a wrench flat 729 provided instub 728 of mandrel 710 (seeFIG. 26B ) untilinner shoulder 715 seats uponstop shoulder 755 and is stopped thereby, as depicted inFIG. 25B . This feature oftool 700 enables a highly reproducible compressive force to be applied tosolid bladder 730 whentool 700 is disassembled and reassembled. -
Solid bladder 730 is made of a highly elastic incompressible solid. Solid bladder preferably consists essentially of an elastomer having a Shore A durometer of between about 10 and about 90.Solid bladder 730 may be made of any suitable material which, when subjected to a compressive force, undergoes elastic deformation in a direction substantially orthogonal to such compressive force. For example,solid bladder 730 may consist essentially of gum rubber, nitrile rubber, or polyurethane. In a further embodiment,solid bladder 730 may consist essentially of an elastomeric closed cell foam. - In one preferred embodiment,
solid bladder 730 is made of nitrile rubber having a Shore A durometer of about 40. Accordingly, whensolid bladder 730 is compressed betweencompression washer 740 andflange 718 ofmandrel 710 as indicated byarrows outer surface 739 ofsolid bladder 730 bulges outwardly as indicated byarrows 796. Referring now toFIGS. 26A , at the beginning of final assembly oftool 700 for use in polishing, polishingband 770 is slid oversolid bladder 730.Polishing band 770 slides over uncompressed and/or semi-compressedsolid bladder 730 with a generally loose sliding fit. Whensolid bladder 730 is compressed as indicated inFIG. 26B ,solid bladder 730 expands radially outwardly as indicated byarrows 796, and engages tightly with polishingband 770, stretching polishingband 770 into the arcuate shape ofouter surface 739 of solid bladder 730 (seeFIG. 25B ). - The
outer surface 739 ofsolid bladder 730 assumes a generally arcuate shape simply due to the axial compression thereof, and the resulting radial expansion thereof. However, to achieve optimum polishing results of optics and the like, it is preferable that thearcuate surface 739 of compressedsolid bladder 730 be ground or otherwise formed to a specified arcuate shape. To perform such a forming process,tool 700 is assembled as just previously described, withsolid bladder 730 in compression and polishingband 770 not fitted tosolid bladder 730.Setscrew 759 incompression collar 750 is fitted and tightened such thatsetscrew 759 engages inslot 713 in threadedshank 716 ofmandrel 710 to the position indicated byengaged setscrew 759A shown in phantom inFIG. 25B . This engagement ofsetscrew 759 inslot 713 prevents the rotation ofcompression collar 750 onmandrel 710 during grinding and during a polishing operation. - The assembled
tool 700 is then fitted into a precision lathe or other surface grinding machine, andarcuate surface 739 ofsolid bladder 730 is ground to a desired shape. In one preferred embodiment for the polishing of optics,arcuate surface 739 is ground to a spherical shape. By way of illustration,solid bladder 730 may have anuncompressed radius 795 of about 3.1 inches, a thickness of about 1 inch, and when compressed, a sphericalarcuate surface 739 with a radius of about 4 inches and a thickness of 0.75 inches. It is to be understood that this radius of about 4 inches describes the radius of curvature of thesurface 739 in the x-z through y-z planes, with z being thecentral axis 23A-23A (seeFIG. 24 ) oftool 700, rather than theradius 795 ofsolid bladder 730. - After
surface 739 ofsolid bladder 730 is ground to the desired arcuate shape,tool 700 is removed from the surface grinder machine for the fitting of a polishing band to surface 739. To accomplish this,setscrew 759 incompression collar 750 is loosened slightly to allowsetscrew 759 to slide in the axial direction (alongaxis 23A-23A) inslot 713 in threadedshank 716 ofmandrel 710.Nut 760 is then loosened, andsetscrew 759 slides inslot 713 untilsetscrew 759 butts up against theupper end 721 ofslot 713. Withsetscrew 759 fitted incompression collar 750 and engaged withupper end 721 ofslot 713, further axial travel ofcompression collar 750 is stopped. - Therefore, even if
nut 760 is released further,solid bladder 730 remains in a state of semi-compression from that point on.Solid bladder 730 is thus preferably never totally released from its compression bycompression washer 740 andflange 718 ofbladder mandrel 710 after the finish grind is completed. A polishing band is then fitted aroundsolid bladder 730, andnut 760 is retightened, engagingpolishing band 770 withsolid bladder 730, and formingpolishing band 770 to the desired arcuate shape. Because of the provision ofinner stop 755 incompression collar 750, which stops againstshoulder stop 715,solid bladder 730 is compressed reproducibly to the same extent as when it was ground to the desired arcuate shape, and thus the curvature ofarcuate surface 739 and polishingband 770 disposed thereupon is accurately reproduced. - Referring again to
FIGS. 24 and 25 B, as a final step in the assembly oftool 700 with polishingband 770,setscrew 759 incompression collar 750 is tightened such thatsetscrew 759 engages inslot 713 in threadedshank 716 ofmandrel 710 to the position indicated byengaged setscrew 759A shown in phantom inFIG. 25B . In one preferred embodiment,compression collar 750 andcompression washer 740 are provided as a single unitary part, i.e. as acompression flange 750/740. Such acompression flange 750/740 is locked to said mandrel and prevented from rotation by engagedsetscrew 759A during operation. Sincesolid bladder 730 is highly compressed and thus frictionally engaged withflange 718,compression washer 740, andbladder shank 714,solid bladder 730 and polishingband 770 engaged therewith are also prevented from slipping during the use oftool 700 for a polishing operation. - It will be apparent that numerous other suitable means for locking the
compression collar 750 or the combinedcollar 750/washer 740 as acompression flange 750/740 to mandrel 710 can be provided alternatively or additionally, such as e.g. a pin passing throughcollar 750 and threadedshank 716, or the keying of theshank 716 and the bore ofcollar 750, and the disposition of a piece of keystock in a key slot in one ofshank 716 or the bore ofcollar 750. The arrangement depicted in the Figures herein is preferred, because it provides both rotational locking, and limited travel to maintain the bladder in semi-compression after precision grinding, while a polishing band is fit thereto. - In general, suitable materials for polishing
band 770 are as described previously in this specification for the polishing tools described and shown inFIGS. 2A-4 . As used herein, the terms “polishing foil” and “polishing band” are used interchangeably. In a further embodiment, rather than a polishing band, there is provided asolid bladder 730 impregnated with abrasive particles such as e.g., diamond particles, such that the solid bladder performs both the function of deformability to some extent to define the spot size during polishing, and abrasiveness to effect material removal during polishing. - It will be apparent that numerous other suitable means for compressing the
lower surface 736 toward theupper surface 734 ofsolid bladder 710 and causing theouter surface 739 of said bladder to have an arcuate shape may be provided. For example, one may provide a pin cam assembly, or an assembly wherein a compression collar is rotated a small angular displacement such as a quarter-turn, compressingbladder 730 and then locking in place. Such assemblies may make use of one or more springs. In another embodiment, compression may be provided by one or more coil springs disposed on a shank portion ofmandrel 710, with a circular disc and keepers engaged with such shank, in much the same way that valves are held in an automotive cylinder head. - It is, therefore, apparent that there has been provided, in accordance with the present invention, a tool for polishing objects comprising a wide variety of materials and shapes including precision optical surfaces and injection mold inserts. While this invention has been described in conjunction with preferred embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.
Claims (18)
1. A polishing tool comprising:
a) a mandrel having a drive shank at a proximal end thereof, a threaded shank, a mandrel shank, and a flange at a distal end thereof;
b) a solid elastic annular bladder comprising a bore, an outer surface, a lower surface, and an upper surface, said bladder disposed upon said mandrel with said lower surface of said bladder in contact with said flange of said mandrel and said mandrel shank passing through said bore in said bladder;
c) a compression flange comprising a compression washer and a compression collar, said compression washer comprising a lower surface in contact with said upper surface of said bladder, and said compression collar comprising a bore slidingly engaged with said threaded shank of said mandrel; and
d) a compression nut threadedly engaged with said threaded shank of said mandrel, wherein when said compression nut is tightened upon said threaded shank, said solid bladder is compressed between said flange of said mandrel and said compression washer, causing said outer surface of said bladder to have an arcuate shape.
2. The polishing tool as recited in claim 1 , wherein said arcuate shape of said bladder resulting from said solid bladder being compressed between said flange of said mandrel and said compression washer is further ground to a different arcuate shape.
3. The polishing tool as recited in claim 2 , wherein said different arcuate shape is a spherical shape.
4. The polishing tool as recited in claim 1 , wherein said solid elastic annular bladder consists essentially of an elastomer.
5. The polishing tool as recited in claim 4 , wherein said elastomer is selected from the group consisting of gum rubber, nitrile rubber, and polyurethane.
6. The polishing tool as recited in claim 4 , wherein said elastomer has a Shore A durometer of between about 10 and about 90.
7. The polishing tool as recited in claim 6 , wherein said elastomer has a Shore A durometer of about 40.
8. The polishing tool as recited in claim 1 , wherein said solid elastic annular bladder consists essentially of an elastomeric closed cell foam.
9. The polishing tool as recited in claim 1 , wherein said compression collar of said compression flange comprises an inner stop, and said mandrel comprises a shoulder stop, and wherein when said compression nut is tightened upon said threaded shank, said inner stop of said compression collar contacts said shoulder stop of said mandrel.
10. The polishing tool as recited in claim 1 , further comprising means for locking said compression flange to said mandrel.
11. The polishing tool as recited in claim 10 , wherein means for locking said compression flange to said mandrel comprises a setscrew in said compression collar engaged with said mandrel.
12. The polishing tool as recited in claim 1 , further comprising a polishing band engaged with said outer surface of said bladder.
13. The polishing tool as recited in claim 12 , wherein said polishing band comprises an outer surface impregnated with abrasive particles.
14. The polishing tool as recited in claim 13 , wherein said abrasive particles are selected from the group consisting of ceria, alumina, silica, diamond, and mixtures thereof.
15. A polishing tool comprising:
a) a mandrel having a drive shank at a proximal end thereof, a threaded shank, a mandrel shank, and a flange at a distal end thereof;
b) a solid elastic annular bladder comprising a bore, an outer surface, a lower surface, and an upper surface, said bladder disposed upon said mandrel with said lower surface of said bladder in contact with said flange of said mandrel and said mandrel shank passing through said bore in said bladder;
c) a compression flange comprising a compression washer and a compression collar, said compression washer comprising a lower surface in contact with said upper surface of said bladder, and said compression collar comprising a bore slidingly engaged with said threaded shank of said mandrel;
d) a polishing band engaged with said outer surface of said bladder; and
e) a compression nut threadedly engaged with said threaded shank of said mandrel, wherein when said compression nut is tightened upon said threaded shank, said solid bladder is compressed between said flange of said mandrel and said compression washer, causing said outer surface of said bladder and said polishing band to have an arcuate shape.
16. The polishing tool as recited in claim 15 , wherein said polishing band comprises an outer surface impregnated with abrasive particles.
17. A polishing tool comprising:
a) a mandrel having a drive shank at a proximal end thereof, a threaded shank, a mandrel shank, and a flange at a distal end thereof;
b) a solid elastic annular bladder comprising a bore, an outer surface, a lower surface, and an upper surface, said bladder disposed upon said mandrel with said lower surface of said bladder in contact with said flange of said mandrel and said mandrel shank passing through said bore in said bladder; and
c) means for compressing said lower surface of said bladder toward said upper surface of said bladder, thereby causing said outer surface of said bladder to have an arcuate shape.
18. The polishing tool as recited in claim 17 , wherein said means for compressing said lower surface of said bladder toward said upper surface of said bladder comprises a compression flange comprising a compression washer and a compression collar, said compression washer comprising a lower surface in contact with said upper surface of said bladder, and said compression collar comprising a bore slidingly engaged with said threaded shank of said mandrel; and a compression nut threadedly engaged with said threaded shank of said mandrel.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US10/963,189 US20050079812A1 (en) | 2003-05-16 | 2004-10-12 | Tool, apparatus, and method for precision polishing of lenses and lens molds |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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US10/439,833 US20050202754A1 (en) | 2003-05-16 | 2003-05-16 | Method, apparatus, and tools for precision polishing of lenses and lens molds |
US10/863,702 US20040229553A1 (en) | 2003-05-16 | 2004-06-08 | Method, apparatus, and tools for precision polishing of lenses and lens molds |
US10/963,189 US20050079812A1 (en) | 2003-05-16 | 2004-10-12 | Tool, apparatus, and method for precision polishing of lenses and lens molds |
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US10/863,702 Continuation-In-Part US20040229553A1 (en) | 2003-05-16 | 2004-06-08 | Method, apparatus, and tools for precision polishing of lenses and lens molds |
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US10/963,189 Abandoned US20050079812A1 (en) | 2003-05-16 | 2004-10-12 | Tool, apparatus, and method for precision polishing of lenses and lens molds |
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