US20110039479A1

US20110039479A1 - Dressing tool

Info

Publication number: US20110039479A1
Application number: US12/853,365
Authority: US
Inventors: Peter Beyer
Original assignee: MEISTER ABRASIVES AG
Current assignee: MEISTER ABRASIVES AG
Priority date: 2009-08-11
Filing date: 2010-08-10
Publication date: 2011-02-17
Also published as: DE102010025677A1; CH701596B1; CH701596A1

Abstract

A dressing tool (100, 200, 300, 400, 500) for conditioning of grinding bodies, especially ceramically bonded grinding bodies, the dressing tool (100, 200, 300, 400, 500) comprising a base body which bears a self-supporting function coating (120, 220, 320, 420, 520) which defines the working region of the dressing tool, the function coating (120, 220, 320, 420, 520) comprising a porous bonding matrix (121, 221, 321, 421, 521) which is uniformly penetrated with grains of hard material (122, 222, 322, 422, 522), is characterized in that in the porous bonding matrix (121, 221, 321, 421, 521) there are additionally embedded reinforcing elements (130, 230, 330, 430, 530) of a hard material for stabilizing the function coating (120, 220, 320, 420, 520).

Description

TECHNICAL DOMAIN

The invention relates to a dressing tool for conditioning of grinding bodies, especially ceramically bonded grinding bodies, the dressing tool comprising a base body which bears a self-supporting function coating which defines the working region of the dressing tool, the function coating comprising a porous bonding matrix which is uniformly penetrated with grains of hard material. Furthermore the invention relates to use of the dressing tool.

PRIOR ART

Grinding tools or grinding bodies wear in operation depending on the grinding method and material pairing over time and therefore at certain intervals must be profiled and sharpened with a dressing tool. Profiling is defined especially as forming of the grindingbody, i.e. producing a defined tool profile. For example, the geometry of the grinding coating is transferred into a prescribed form, and axial eccentricities and concentricity errors are corrected. In sharpening, a defined microtopography is produced, i.e. especially impurities and blunt grinding grains are removed from the grinding bodies so that sharp grinding grains are exposed and thus sufficient grain projections are produced. Depending on the material of the grinding bodies, profiling takes place at the same time with sharpening (for example in ceramically bonded grinding bodies) or after profiling an additional sharpening process (for example in grinding bodies with metal or artificial resin bonding) is carried out.
To dress grinding bodies, for example ceramically bonded grinding bodies with cubic boron nitride (CBN), galvanically tipped or metal-bonded diamond dressing tools are conventionally used. In galvanically bonded diamond dressing tools a base body in one working region is tipped with a layer of diamond grains, which are then attached to the surface of the base body by a galvanic coating, for example of nickel metal. These diamond dressing tools have relatively high wear resistance, but due to the single-layer tipping cannot be reworked when the diamond monolayer wears and must therefore be regularly stripped of the nickel and retipped in a cost-intensive and time-consuming process.
In metal-bonded diamond dressing tools the diamond grains are dispersed in several layers in a metal matrix which is located on the base body. Dressing tools of this type likewise have a relatively high wear resistance and can be reprofiled and sharpened. Especially metal-bonded diamond dressing tools can however produce surface topographies on the grinding body which often cause undesirable run-in behavior with respect to surface roughness on the workpiece to be machined in later use in the grinding process. The shape holding quality is moreover limited and these dressing tools must therefore be reprofiled relatively often and resharpened even more often; this is in turn expensive and time-consuming.
Possible alternatives to galvanically tipped or metal-bonded diamond dressing tools have also been diamond dressing tools with ceramic bonding. The journal IDR (Industrie Diamanten Rundschau: issue 39 (2005); pp. 38-42) for example discloses ceramically bonded dressing tools for grinding tools of cubic boron nitride (CBN) which have a function coating with diamond grains in a porous bonding matrix. Currently available ceramically bonded dressing tools however generally are not entirely satisfactory with respect to service life and shape holding quality in order to be used economically in series application.
As before, there is therefore a demand for an improved dressing tool which is optimized especially for conditioning or dressing of ceramically bonded grinding bodies, for example ceramically bonded grinding bodies with cubic boron nitride (CBN).

DESCRIPTION OF THE INVENTION

The object of the invention is to devise a dressing tool which belongs to the initially named technical domain, which can be repeatedly conditioned and which additionally enables production of optimized surface topographies on the grinding bodies to be machined, with improved shape holding quality.
This object is achieved by the features of claim 1. As claimed in the invention in the porous bonding matrix there are additionally embedded reinforcing elements of a hard material for stabilizing the function coating.
The function coating of the dressing tool as claimed in the invention is made especially self-supporting. In other words, this means that the function coating is mechanically stable, especially regardless of the base body. But it would therefore be fundamentally conceivable to omit a base body which bears the function coating in the dressing tool as claimed in the invention. But this makes little sense for practical and economic reasons. The self-supporting function coating differs from the coating as is present in galvanically tipped grinding wheels, with the same contact surface between the base body and coating or function coating, especially by a more voluminous structure penetrated by pores.
A hard material is defined in this connection as especially substances with a Mohs hardness of at least 8.5, especially at least 9.5. Preferred examples are diamond, diamond-based composite materials and/or cubically crystalline boron nitride (CBN). But fundamentally other substances are conceivable as hard materials, such as for example silicon carbide, aluminum oxide, boron carbide, tungsten carbide, vanadium carbide, titanium carbide, titanium nitride and/or zirconium dioxide.
Reinforcing elements here are especially shaped elements of a hard material. Reinforcing elements compared to grains of hard material in the bonding matrix have especially different geometrical shapes and sizes.
As has been shown, a combination of a porous bonding matrix penetrated with grains of hard material and reinforcing elements of a hard material which are located in it yields an especially advantageous function coating for dressing tools. This function coating shows especially very good free-cutting properties. Grinding bodies which are worked by the dressing tools as claimed in the invention have hardly any noticeable run-in behavior. The latter can be attributed especially to optimum surface roughness of the grinding bodies worked with the dressing tools as claimed in the invention.
Moreover, with a suitable configuration of the function coating as claimed in the invention it is possible to achieve a self-sharpening effect so that the wear and dressing properties are kept constant in the working of a grinding body. This yields especially improved shape holding quality and the dressing tool contour remains constant over a relatively long time. In other words, the dressing tools as claimed in the invention show greatly reduced susceptibility to rounding. Thus, the interval to reprofiling of the dressing tool itself is significantly prolonged compared to conventional dressing tools.
Fundamentally the layout of the dressing tool as claimed in the invention enables repeated reworking to restore profile fidelity. This is possible without economically unfavorable retipping, as in conventional dressing tools, by the manufacturer, or with a corresponding set-up, even by the customer himself.
The combination of a porous bonding matrix penetrated with hard material grains and reinforcing elements of hard material as claimed in the invention moreover yields efficient dissipation of the heat which arises in the dressing of a grinding body. This protects both the dressing tool and also the grinding body.
As has been shown, with the dressing tool as claimed in the invention it is also possible to dress grinding bodies with relatively large diameter even in high-precision CNC controlled dressing with spot contact between the dressing tool and grinding body. Thus, the dressing tools as claimed in the invention can be used more flexibly for the most varied applications.
Altogether the dressing tool as claimed in the invention with improved shape holding quality enables production of optimized surface topographies on the grinding body to be worked and at the same time the dressing tool as claimed in the invention can be conditioned several times. Especially time and money can be saved in the dressing of grinding bodies as result of the configuration of the dressing tool as claimed in the invention.
Advantageously the porous bonding matrix has a pore volume of 10-80%, preferably 30-50%, more preferably 35-45%. In combination with the reinforcing elements as claimed in the invention the free-cutting properties and the surface topographies of the grinding bodies which are worked by the dressing tools as claimed in the invention can thus be optimized.
But it is also fundamentally possible to provide a pore volume of less than 10% or of more than 80%. In these cases however the free-cutting properties or surface topographies of the grinding bodies worked by the dressing tools as claimed in the invention can be diminished.
In particular, the porous bonding matrix comprises an inorganic oxide material, preferably the inorganic oxide material containing Al₂O₃, ZrO₂, SiO₂, Fe₂O₃and/or ZnO. It can also be advantageous to make the porous bonding matrix in the form of a mixture of different inorganic oxide materials. In another advantageous version the porous bonding matrix consists solely of one or more inorganic oxide materials. Inorganic oxide materials and especially the aforementioned representatives have proven especially feasible since they have relative high stability and compared to a plurality of materials are chemically relatively inert even at elevated temperatures. At the same time, with these materials porous bonding matrices penetrated with hard material grains, especially diamond grains, can be economically implemented. On the one hand the pore volume can be easily monitored and on the other effective embedding of the reinforcing elements is enabled.
The porous bonding matrix however does not necessarily consist of an inorganic oxide material. Depending on the application, it can also be advantageous if the porous bonding matrix comprises an inorganic nonoxide material, especially a carbide and/or a nitride, and especially preferably the inorganic nonoxide material containing SiC, B₄C, Si₃N₄, TiC, Fe₃C, TiN and/or WC. In particular, the porous bonding matrix can also consist exclusively of the inorganic nonoxide material. Thus the spectrum of material for the bonding matrix is extended and can be matched to special requirements. Carbides and nitrides as inorganic nonoxide material have proven especially suitable since as in the inorganic oxide materials porous bonding matrices penetrated with hard material grains, especially diamond grains, can be economically produced. In this case the pore volume can be easily monitored and on the other, effective embedding of the reinforcing elements can be implemented.
It can however also be advantageous to produce the porous bonding matrix from a combination of an inorganic oxide material and an inorganic nonoxide material. The inorganic oxide material and the inorganic nonoxide material are advantageously one or more of the aforementioned representatives. Thus the mechanical properties of the bonding matrix can be adapted to special requirements in a more dedicated manner. As has been shown, in a combination of an inorganic oxide material and an inorganic nonoxide material it is also possible to implement porous matrixes mixed with hard material grains and to effectively embed the reinforcing elements.
But it is also fundamentally possible to provide other materials for the bonding matrix. But under certain circumstance the aforementioned advantages can disappear.
In one especially advantageous embodiment the porous bonding matrix contains a metallic phase and/or an intermetallic phase, preferably the metallic phase and/or the intermetallic phase containing Cu, Sn, Zn, Fe, Co, Ni, Ag, Cr, V, Zr, Mn and/or Al as metals. In this connection an intermetallic phase is defined especially as an essentially homogenous compound of two or more metals, the lattice structure of the intermetallic phase differing especially from the lattice structures of the constituent metals.
Due to the metallic phase and/or the intermetallic phase wetting and adhesion between the bonding matrix and the reinforcing elements can be improved. At the same time the grain holding forces between the hard material grains and the bonding matrix can be increased. Altogether the function coating can thus be optimized mechanically by a bonding matrix with a metallic phase and/or an intermetallic phase without the wear resistance of the function coatings being reduced compared to conventional dressing tools. This applies especially in combination with one or more of the aforementioned inorganic oxide materials and inorganic nonoxide materials.
A porous bonding matrix with a metallic phase and/or intermetallic phase is however not critically necessary. It is also possible to provide other additives in the porous bonding matrix instead of the metallic phase and/or the intermetallic phase or to completely omit the metallic phase and/or the intermetallic phase.
In particular, the metallic phase and/or intermetallic phase in the porous bonding matrix has a volumetric proportion of 5-60%. These volumetric proportions have proven especially advantageous with respect to mechanical optimization of the porous bonding matrix.
But fundamentally volumetric proportions smaller than 5% or volumetric proportions larger than 60% are possible. The positive effects associated with the metallic phase and/or intermetallic phase are however reduced under certain circumstances.
Advantageously the porous bonding matrix has an open pore structure. An open pore structure is especially a structure of the porous bonding matrix in which adjacent pores in the bonding matrix at least partially communicate with one another. Thus the free-cutting properties of the function coating can be improved.
But it is also fundamentally possible to provide a closed pore structure or mixture of a closed and an open pore structure.
The function coating is produced especially advantageously by a sintering process. In function coatings produced in this way, especially good cohesion of the bonding matrix, high grain holding forces between the hard material grains and the bonding matrix, and effective embedding of the reinforcing elements can be implemented.
Moreover the sintering process allows especially economical production of the function coating, at the same time sufficient precision being enabled in the monitoring of the pore volume in the bonding matrix.
Fundamentally the function coating can however also be produced by other production methods known to one skilled in the art.
The grain size of the hard material grains is especially 20-600 μm, preferably 80-100 μm. Hard material grains with these grain sizes can be stably embedded into the bonding matrix and in interplay with the above described materials and reinforcing elements yield a durable function coating which moreover has good free-cutting properties. Grain sizes of 80-100 μm have proven optimum.
But it is also fundamentally possible to provide grain sizes smaller than 20 microns or grain sizes larger than 600 μm. But the aforementioned advantages are eliminated under certain circumstances.
Advantageously the hard material grains are present in the form of diamond grains, preferably the volumetric proportion of the diamond grains being 30-40%. Diamond grains are suitable due to their outstanding hardness, mechanical durability and relatively high chemical inertness.
But fundamentally it is also conceivable to provide other hard material grains from other hard materials in addition to or instead of hard material grains from diamond.
A volumetric proportion of 30-40% has proven suitable especially in combination with the aforementioned materials for the bonding matrix and a pore volume of 10-80%, preferably 30-50%, further preferably 35-45%.
The volumetric proportion of the diamond grains can however also be less than 30%, but this reduces the dressing performance under certain circumstances. Volumetric proportions larger than 40% yield hardly any additional benefit and are especially less economical.
Advantageously the function coating is structured with several layers. This means especially that the function coating has several layers of hard material grains located on top of one another. In other words, the hard material grains are advantageously dispersed in several layers in the function coating. The individual layers of the function coating lie on top of one another especially with respect to the direction perpendicular to the contact surface of the function coating with a base body. In a rotationally symmetric base body the individual layers thus lie on top of one another especially in the radial direction. A function coating with a multilayer structure enables especially repeated regrinding of the dressing tool as claimed in the invention. In particular, in combination with the reinforcing elements multilayer function coatings may also be convincing with respect to wear resistance and cutting properties.
But fundamentally it is also possible to provide a single-layer function coating. Here however the potential with respect to repeated regrinding of the dressing tool is reduced. Thus however one of the advantages as claimed in the invention in a porous structure which is advantageous in terms of application engineering would be partially eliminated.
As has been ascertained, the minimum thickness of the function coating preferably corresponds at least five times, especially preferably at least ten times, to an average grain diameter of the hard material grains. In one especially preferred embodiment the minimum thickness of the function coating corresponds at least thirty times to the average hard material grain diameter. The average hard material grain diameter is defined especially as the average of all diameters of the hard material grains contained in the function coating. The thickness of the function coating is measured especially in one direction perpendicular to the contact surface of the function coating with the base body. In a rotationally symmetrical base body the thickness is measured especially in the radial direction. The indicated minimum thickness on the one hand enables repeated regrinding of the dressing tool as claimed in the invention. On the other hand, it has been shown that the function coating, especially in combination with the reinforcing elements, has especially high wear resistance with simultaneously good cutting properties.
But fundamentally also smaller thicknesses can be provided, in any case the potential of regrinding being reduced and in any case the wear resistance decreasing.
The reinforcing elements are preferably present as elongated or cuboidal rods, preferably the ratio of the length of the cuboidal rod to thickness and/or width of the cuboidal rod having a value of 2-7. The rods can be rounded especially in the end-side region and/or can have a shape adapted to the edge shape and/or the shape of one side surface of the function coating. Thus the rods can be arranged directly bordering the edge region and/or side surface of the function coating; this best reinforces the especially exposed regions of the function coating.
The maximum length of the reinforcing elements in one preferred embodiment is at least equal to half the thickness of the function coating. The thickness of the function coating is measured especially in the direction perpendicular to the contact surface between the base body and the function coating, as mentioned above. The reinforcing elements are preferably arranged perpendicular to the contact surface between the base body and the function coating.
The reinforcing elements especially preferably have a maximum length which is at least twice, preferably five times, the average diameter of the hard material grains present in the bonding matrix.
With reinforcing elements formed in this way the stability and shape holding quality of the function coating, especially in interplay with the above described pore volume and materials, can be significantly improved in an especially economical manner.
Depending on the application, under certain circumstances it can also be advantageous to provide other configurations and arrangements of the reinforcing elements. Fundamentally for example reinforcing elements in the form of thin laminae with three, four or even more corners are conceivable, and individual or all grains can also be made rounded. Rounded particles, for example hemispherical and/or spherical particles, can also be fundamentally used as reinforcing elements. The reinforcing elements can also be arranged obliquely or parallel to the contact surface between the base body and function coating.
In one especially advantageous embodiment the reinforcing elements except for inevitable impurities consist solely of diamond. For this reason, especially high reinforcement and shape holding quality of the function coating are achieved. But materials other than diamond are also conceivable.
Thus the reinforcing elements can also consist especially of composite materials, especially the composite material containing diamond and a metallic phase. Preferably the diamond in the composite material has a proportion by weight of 80-90% and the metallic phase has a proportion by weight of 10-20%.
These reinforcing elements, for example, depending on the composition and structure of the bonding matrix, in the embedding in the bonding matrix can entail advantages and/or improve the stability of the function coating.
The composite material can also have a different composition and fundamentally reinforcing elements without diamond, for example of cubic boron nitride, are possible.
It can also be advantageous to provide different reinforcing elements of different materials. Thus for example reinforcing elements which consist solely of diamond except for inevitable impurities can be combined with reinforcing elements of composite material, for example of diamond and a metallic phase.
Especially preferably the reinforcing elements are located bordering one edge and/or one side surface of the function coating. In this way the sites of the function coating or of the dressing tool which are especially exposed during dressing are optimally reinforced. The reinforcing elements are especially molded to the edge shape and/or the shape of the side surface.
In one preferred embodiment the base body is made rotationally symmetrical with respect to the axis of rotation and is present especially as a disk, ring and/or in a pot shape. Thus the dressing tool as claimed in the invention can be used for rotational working of grinding bodies; this is an especially effective version of dressing. The base body advantageously consists of a metal, such as for example stainless steel. The use of base bodies of stainless steel yields high strength and chemical inertness relative to a host of cooling lubricants.
In a wheel as the base body the function coating is attached especially to the outer jacket of the wheel. But it is also possible to arrange the function coating in the face-side regions of the wheel additionally or instead of mounting on the outer edge.
In a base body in the form of a ring the function coating can be fundamentally present on the outer jacket and/or inner jacket of the ring Likewise it is possible to arrange the function coating on face-side regions of the ring in addition to or instead of attachment to the outer jacket.
For pot-shaped base bodies the function coating can be located for example on the outer surface and/or the inner surface of the pot-shaped base body.
The reinforcing elements with their longitudinal middle axes are preferably located in the radial direction of the base body. Alignment of the reinforcing elements achieves optimum shape holding quality and wear resistance of the function coating with a minimum number of reinforcing elements; this reduces production costs. This applies especially in use with reinforcing elements in the form of elongated and/or cuboidal rods.
Fundamentally the reinforcing elements however can also be located obliquely and/or perpendicular to the radial direction of the base body. It is also possible to align different reinforcing elements in the function coating with their longitudinal middle axes in different directions.
In another preferred version the reinforcing elements are advantageously additionally anchored in the base body. In this way the connection between the function coating and the base body can be additionally improved; this benefits the shape holding quality and wear resistance of the dressing tool as claimed in the invention. The reinforcing elements can be located for example in holes, grooves, and/or recesses in the base body and thus they have especially a high-precision location relative to the base body.
But it is also possible to provide the reinforcing elements only in the function coating. This reduces for example the length of the reinforcing elements; this cuts production costs.
Other advantageous embodiments and combinations of features will become apparent from the following detailed description and totality of claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are used in explanation of the embodiment.

FIG. 1 shows a top view of the face side of the first dressing tool as claimed in the invention with a rotationally symmetrical base body and a function coating which has been reinforced by reinforcing elements;

FIG. 2 shows a cross section through the dressing tool from FIG. 1 along line A-A;

FIG. 3 shows a detail view from FIG. 2 (region of the dashed circle in FIG. 2), which shows the edge region of the base body of the dressing tool from FIG. 1 without the function coating;

FIG. 4 shows a detail view from FIG. 2 (region of the dashed circle in FIG. 2), which shows the edge region of the dressing tool from FIG. 1 with the function coating;

FIG. 5 shows a top view of the face side of the second dressing tool as claimed in the invention with a rotationally symmetrical base body and a function coating which has been reinforced by reinforcing elements;

FIG. 6 shows a cross section through the dressing tool from FIG. 5 along line B-B;

FIG. 7 shows a detail view from FIG. 6 (region of the dashed circle in FIG. 6), which shows the edge region of the dressing tool from FIG. 5;

FIG. 8 shows a cross section through the dressing tool from FIG. 5 along line C-C;

FIG. 9 shows a top view of the face side of the third dressing tool as claimed in the invention with a rotationally symmetrical base body and a function coating which has been reinforced by reinforcing elements;

FIG. 10 shows a cross section through the dressing tool from FIG. 9 along line D-D;

FIG. 11 shows a detail view from FIG. 10 (region of the dashed circle in FIG. 10), which shows the edge region of the dressing tool from FIG. 9;

FIG. 12 shows a detail view of the edge region of a fourth dressing tool as claimed in the invention in cross section;

FIG. 13 shows a detail view of the edge region of a fifth dressing tool as claimed in the invention in cross section.

Fundamentally the same parts are provided with the same reference numbers in the figures.

EMBODIMENTS OF THE INVENTION

A first dressing tool 100 as claimed in the invention is shown in FIGS. 1-4. It has a base body 110 of stainless steel which is made as a truncated cone-shaped disk with a large circular face side 111 and a small circular face side 112 which is arranged plane-parallel to it (in FIG. 1 covered by the larger face side 111). The diameter of the base body 100 measures for example roughly 100 mm. The two circular face sides 111, 112 are connected by way of an essentially conically made jacket surface 113 (see FIG. 2). The base body 110 or the truncated cone-shaped disk are made rotationally symmetrical with respect to the axis of rotation 116 or the longitudinal middle axis of the base body 110, which axis is perpendicular to the two face sides 111, 112.
Along the axis of rotation 116 a central cylindrical bore 115 extends continuously from the large face side 111 to the small face side 112. The central bore 115 is used especially to accommodate the drive axle of a machine tool. Around the central bore 115 there are several cylindrical attachment bores 117 at regular intervals on a circle which is concentric to the central bore 115 or to the axis of rotation 116. The attachment bores 117 are used to fix the base body for example in a machine tool using fastening screws. The diameter of the attachment bores 117 is incrementally widened in the section facing the large face side 111 so that the screw heads of the attachment screws can be placed underneath the plane of the large face side 111 in the base body 110.
FIG. 3 shows the configuration of the base body 110 in the edge region or in the region of the jacket surface 113, enlarged (region of the dashed circle in FIG. 2), for illustration of the configuration of the base body 110 the other elements of the dressing tool 100 described below not being shown. A representation corresponding to FIG. 3 with the other elements is shown in FIG. 4.
In the region of the jacket surface 113 bordering the larger face side 111 a groove 118 which runs peripherally completely around the base body is made in the latter. The peripheral groove 118 has a rectangular profile and is open in the radial direction of the base body 110 and toward the large side 11. In the peripheral groove 118 several cuboidal depressions 119 are made at regular intervals in the radial direction in the base body 110. The cuboidal depressions 119 have for example a depth of 0.5-2 mm in the radial direction.
In the peripheral groove 118 there is an annular function coating 120 with a rectangular cross section. The function coating 120 projects in the radial direction out of the groove 118 and is roughly flush with the large face side 111 of the base body 110.
The function coating 120 consists of a porous matrix 121 with a plurality of hard material grains 122 dispersed in it. The porous matrix 121 for example has a pore volume of 40% and consists for example of Al₂O₃with a metallic phase of for example Cu which relative to the porous matrix 121 has a volumetric proportion of for example 30%. The hard material grains 122 are present for example in the form of diamond grains and at an average grain size of for example 91 μm have a volumetric proportion of for example 36%. The thickness 124 of the function coating 120 and of the porous matrix 121 in the radial direction or perpendicular to the contact surface with the base body 110 measures for example roughly 3.5 mm; this is roughly 38 times the average grain diameter of the hard material grains 122.
The function coating 120 is applied to the base body 110 for example in a known sintering press.
In each of the several cuboidal depressions 119 one reinforcing element 130 at a time in the form of elongated diamond rods is anchored in the base body 110. The reinforcing elements present with their end sections in the cuboidal depressions 119 or the cuboidal diamond rods project with their longitudinal center axes in the radial direction away from the base body 110 and are embedded roughly in the middle in the function coating 130. The ends 131 of the reinforcing elements 130 facing away from the base body 110 directly border the outer jacket surface 123 of the function coating 120 and are molded onto the course of the outer jacket surface 123. In other words, the ends 131 of the reinforcing elements 130 facing away from the base body 110 are roughly flush with the outer jacket surface 123 of the function coating 120.
The reinforcing elements 130 for example have a width and a thickness of roughly 0.4 mm each. The length of the reinforcing elements 130 in the radial direction measures for example roughly 4 mm. The length of the reinforcing elements 130 is thus larger than the total thickness 124 of the function coating 120 or of the porous bonding matrix 121. The reinforcing elements 130 consist of diamond, for example, except for inevitable impurities.
FIGS. 5-8 show a second dressing wheel 200 as claimed in the invention. It has a base body 210 which except for the edge area is made essentially the same as the first base body 110 of the first dressing tool 100 and accordingly has a large face side 211, a small face side 212, a conical jacket surface 213, a central bore 215, an axis of rotation 216 and several attachment bores 217 which are all made like the corresponding elements in the first base body.
In contrast to the base body 110 of the first dressing tool 100, the base body 210 of the second dressing tool 200 however does not have a peripheral groove in a region of the jacket surface 213 bordering the large face side 211. Instead, for the base body 210 of the second dressing tool 200 there is a peripheral projecting flange 218 with a rectangular cross section. Continuous rectangular grooves 219 which run in the direction parallel to the axis of rotation 216 completely through the flange 218 are made at regular intervals in the flange 218. The grooves 219 are thus open in the direction to the large face side 211 and also in the direction to the small face side 210 and in the radial direction.
In each of the rectangular grooves 219 one reinforcing element 230 at a time in the form of an elongated cuboidal diamond rod is anchored in the base body 210. The reinforcing elements 230 present with their end sections in the rectangular grooves 219 or the cuboidal diamond rods project with their longitudinal middle axes in the radial direction away from the base body 210.
The reinforcing elements 230 of the second dressing tool 200 for example have the same dimensions as the reinforcing elements 130 of the first dressing tool 100 and consist for example likewise of diamond.
The regions between the reinforcing elements 230 are filled with a function coating 220 in the second dressing tool 200, with which the reinforcing elements 230 are each embedded in the function coating 220 with two opposite sides. The individual sections of the function coating 220 are present in the form of annular segments with a rectangular profile. The reinforcing elements 230 and sections of the function coating 220 together form a continuous ring which surrounds the base body 210, with a rectangular profile. The thickness of the function coating 220 measured in the direction of the axis of rotation 216 corresponds essentially to the thickness of the reinforcing elements 230 measured in the same direction.
The function coating 220 of the second dressing tool 200 likewise has a porous matrix 221 with hard material grains 222 dispersed in it. The porous matrix 221 and the hard material grains 222 of the function coating 220 of the second dressing tool 200 are made for example essentially the same as the porous matrix 121 and the hard material grains 122 of the function coating 120 of the first dressing tool 100.
FIGS. 9-11 show a third dressing tool 300 as claimed in the invention. It has a base body 310 which is present in the form of an essentially cylindrical disk which is made rotationally symmetrical around the axis of rotation 316. The thickness of the base body 310 or of the disk, measured in the direction parallel to the axis of rotation 316, tapers conically with respect to the cross sectional plane E which is perpendicular to the axis of rotation 316 first incrementally from the central region of the base body 310 in the radial direction and conically in a region farther to the outside.
The central cylindrical bore 315 extends along the axis of rotation 316 through the base body 310. The central bore 315 is used especially for holding the drive axis of a machine tool.
FIG. 11 shows the configuration of the third dressing tool 300 in the edge region, enlarged (region of the dashed circle in FIG. 10).
Several cuboidal depressions 319 are made in the radial direction in the base body 310 at regular intervals in the jacket surface 313 of the base body 310 which is perpendicular to the cross sectional plane E. The cuboidal depressions 319 in the radial direction for example have a depth of 0.5-2 mm.
There is an annular function coating 320 on the jacket surface 313. The function coating 320 in the region of the jacket surface 313 has a rectangular cross section which in the radial direction passes into a section which tapers in a wedge shape. The function coating 320 is made as a rounded edge 323 in the region which is outermost in the radial direction.
The function coating 320 consists of a porous matrix 321 with a plurality of hard material grains 322 which are dispersed in it. The porous matrix 321 has for example a pore volume of 40% and consists for example of Al₂O₃with a metallic phase of for example Cu which has a volumetric proportion of for example 30% compared to the porous matrix 321. The hard material grains 322 are present for example in the form of diamond grains and at an average grain size of for example roughly 91 μm have a volumetric portion of for example roughly 36%. The thickness 324 of the function coating 320 or of the porous matrix 321 in the radial direction or perpendicular to the jacket surface 313 or contact surface with the base body 310 measures for example roughly 3.5 mm; this corresponds roughly to 38 times the average diameter of the hard material grains 322.
In each of the several cuboidal depressions 319 one reinforcing element 330 at a time in the form of elongated diamond rods is anchored in the base body 310. The reinforcing elements 330 present with their end sections in the cuboidal depressions 319 or the cuboidal diamond rods project with their longitudinal center axes in the radial direction away from the base body 310 and are embedded roughly in the middle in the function coating 330. The ends 331 of the reinforcing elements 330 facing away from the base body 310 directly border the rounded edge 323 of the function coating 320 and are molded onto the form of the rounded edge 323. In other words, the ends 331 of the reinforcing elements 330 facing away from the base body 310 are roughly flush with the rounded edge 323 of the function coating 320.
The reinforcing elements 330 for example have a width and a thickness of roughly 0.4 mm each, as in the first dressing tool. The length of the reinforcing elements 330 in the radial direction measures for example roughly 4 mm which is greater than the thickness 324 of the function coating 320 or of the porous bonding matrix. The reinforcing elements 330 consist of diamond, for example, except for inevitable impurities.
FIG. 12 shows a detail view of a fourth dressing tool 400 as claimed in the invention. The base body 410 of the fourth dressing tool 400 is made essentially the same as the base body 110 of the first dressing tool 100 from FIG. 1. In contrast, in the fourth dressing tool 400 however cuboidal depressions are not made in the peripheral groove 418.
In the peripheral groove 418 there is an annular function coating 420 with a rectangular cross section, as in the first dressing tool 100 as well as the fourth dressing tool 400. The function coating 420 projects in the radial direction out of the groove 418 and is roughly flush with the large face side 411 of the base body 410.
The function coating 420 of the fourth dressing tool 400 likewise has a porous matrix 421 with hard material grains 422 dispersed in it. The porous matrix 421 and the hard material grains 422 of the function coating 420 of the fourth dressing tool 400 are made for example essentially the same as the porous matrix 121 and the hard material grains 122 of the function coating 120 of the first dressing tool 100.
In the function coating 420 of the fourth dressing tool 400 several reinforcing elements 430 in the form of elongated cuboidal diamond rods are embedded. The reinforcing elements 430 are aligned with their longitudinal middle axes in the radial direction. In contrast to the first dressing tool 100, the reinforcing elements 430 of the fourth dressing tool 400 are however not anchored in the base body 410, but spaced apart from it. The reinforcing elements 430 are arranged laterally in the function coating 420 and with their ends 431 facing away from the base body 410 directly in the corner region of the function coating 420 border the outer jacket surface 423 of the function coating 420 and are molded to the shape of the outer jacket surface 423. The side surface of the reinforcing elements which is located perpendicular to the ends 431 facing away is arranged in the plane of the large face side 411 bordering the boundary surface of the function coating 420.
Thus the reinforcing elements 430 in the fourth dressing tool 400 are each surrounded on four sides by the porous matrix 421 or the function coating 420 and reinforce especially one of the edges of the function coating 420 which face away from the base body 410.
The reinforcing elements 430 of the fourth dressing tool 400 are made shorter than the reinforcing elements 130 of the first dressing tool 100, but for example have the same thicknesses and widths as the reinforcing elements 130 of the first dressing tool 100 and consist for example likewise of diamond.
FIG. 13 shows a detail view of a fifth dressing tool 500 as claimed in the invention. The base body 500 of the fifth dressing tool is essentially identical to the fourth dressing tool 400 from FIG. 12. In the peripheral groove 518 of the fifth dressing tool 500 in the same manner as in the fourth dressing tool 400 there is a function coating 520 with a porous matrix 521 and hard material particles 522 dispersed in it. The porous matrix 521 and the hard material grains 522 of the function coating 520 of the fifth dressing tool 500 are made for example essentially the same as the porous matrix 121 and the hard material grains 122 of the function coating 120 of the first dressing tool 100.
In the function coating 520 of the fifth dressing tool 500 several reinforcing elements 530 in the form of elongated cuboidal diamond rods are embedded roughly in the center. The reinforcing elements 530 are aligned with their longitudinal middle axes in the radial direction. In contrast to the fourth dressing tool 400, the reinforcing elements 530 of the fifth dressing tool 500 are however spaced on all sides away from the boundary surfaces of the function coating 520. Thus the reinforcing elements 530 are completely embedded in the function coating 520 and in the porous matrix 521. In other words, the reinforcing elements 530 are surrounded on all sides by the function coating 520 and the porous matrix 521.
In a first practical test the fourth dressing tool 400 as claimed in the invention from FIG. 12 was used for profiling of a ceramically bonded CBN grinding wheel in a grain size of 46 microns with a setpoint profile inner radius of 0.15+0.05 mm. Even after 60 profiled tools no significant wear on the dressing tool as claimed in the invention occurred. All CBN grinding wheels dressed with the fourth dressing tool 400 as claimed in the invention had comparably high quality and showed especially no undesirable run-in behavior in subsequent grinding processes. In other words, the CBN grinding wheels could be fully used directly after dressing.
For comparison purposes, a first dressing tool not according to the invention was produced which had essentially the same structure as the fourth dressing tool 400 as claimed in the invention, but did not have any reinforcing elements 430 or elongated cuboidal diamond rods. The dressing tool not according to the invention was then subjected to the same practical test as the fourth dressing tool 400 as claimed in the invention. It was shown that in the dressing tool not according to the invention after 30 profiled grinding bodies the wear of the dressing tool contour is outside of the allowable tolerance of 0.05 mm on the profile radius.
In a second practical test the second dressing tool 200 as claimed in the invention from FIGS. 5-8 was used for profiling a ceramically bonded sintered corundum wheel of grain size F100 and dimension 84×40×24 mm. In radial cutting of a groove an edge radius of 0.12 mm was obtained. The ceramically bonded sintered corundum disk worked with the second dressing tool 200 as claimed in the invention did not show any undesirable run-in behavior in a subsequent grinding process either.
For comparison purposes, a second dressing tool not according to the invention was produced which had essentially the same structure as the second dressing tool 200 as claimed in the invention, but did not have any reinforcing elements 230 or elongated cuboidal diamond rods. After an analogous profiling application as in the second practical test, in the second dressing tool not according to the invention an edge radius of 0.48 mm is established. The wear resistance of the second dressing tool 200 as claimed in the invention is then quadrupled compared to the second dressing tool not according to the invention.
As has been shown, the dressing tools 200, 400 used in the practical tests were able to be repeatedly re-ground without problems.
The above described embodiments should be understood solely as illustrative examples which can be optionally modified within the framework of the invention.
Thus the dressing tools 100, 200, 300, 400, 500 designed for rotary dressing of grinding bodies can fundamentally also be made in a version for vertical dressing. In this case for example rotationally symmetrical base bodies can be omitted and instead plate-shaped base bodies can be used.
It is likewise possible for dressing tools 100, 200, 300, 400, 500 to provide base bodies of a different shape 110, 210, 310, 410, 510 which are adapted to the respective application of the dressing tool. For example, pot-shaped base bodies with a cylindrical driving shaft are conceivable, the function coatings for example being located on the edge and/or the jacket surface of the pot-shaped base body or at any angle between 0 and 90°.
Likewise the function coatings 120, 220, 320, 420, 520 in different regions can also have different outside diameters, the different regions for example being connected by way of one or more steps, edges, and/or rounded transition regions. Here especially in the region of all the steps, edges, and/or rounded transition regions there can be correspondingly adapted reinforcing elements which reinforce these especially exposed sites.
But it is also possible for dressing tools 100, 200, 300, 400, 500 in addition to the existing function coatings 120, 220, 320, 420, 520 to provide other function coatings on the base bodies 110, 210, 310, 410, 510 which can likewise be reinforced especially with reinforcing elements.
The function coatings 120, 220, 320, 420, 520 instead of or in addition to the diamond grains 122, 222, 322, 422, 522 can also contain other hard material grains, especially also with different grain diameters.
For all the dressing tools 100, 200, 300, 400, 500 in addition to the existing reinforcing elements 130, 230, 330, 430, 530 there can be other reinforcing elements in the function coatings 120, 220, 320, 420, 520. The other reinforcing elements can be located for example next to and/or between the existing reinforcing elements 130, 230, 330, 430, 530.
Especially for all dressing tools 100, 200, 300, 400, 500 it is also possible to provide differently shaped reinforcing elements and/or reinforcing elements of different materials. It is also conceivable to arrange some or all reinforcing elements 130, 230, 330, 430, 530 in the nonradial direction, for example with their longitudinal middle axes parallel to the axes of rotation 116, 216, 316. This is of course also possible for other reinforcing elements.
As has been shown, the porous bonding matrix 121, 221, 321, 421, 521 of the dressing tools 100, 200, 300, 400, 500 in addition or instead of the inorganic oxide material can also contain an inorganic nonoxide material. In this way the porous bonding matrix can be adapted for example to specific requirements or to special material combinations of the dressing tool and grinding body. Likewise the metallic phase in the porous bonding matrices 121, 221, 321, 421, 521 can also be omitted or there are other or additional metals in the metallic phase.
In summary, it can be maintained that novel dressing tools have been devised which can be re-profiled and which are characterized especially by improved shape holding quality compared to conventional dressing tools. Due to the complex interplay between the porous bonding matrix which is penetrated with hard material grains and the reinforcing elements located in it, at the same time optimized surface topographies can be produced on the grinding bodies to be worked, so that they essentially no longer have any disadvantageous run-in behavior.

Claims

1. Dressing tool for conditioning of grinding bodies, especially ceramically bonded grinding bodies, the dressing tool comprising a base body which bears a self-supporting function coating which defines the working region of the dressing tool, the function coating comprising a porous bonding matrix which is uniformly penetrated with grains of hard material, characterized in that in the porous bonding matrix there are additionally embedded reinforcing elements of a hard material for stabilizing the function coating.

2. Dressing tool as claimed in claim 1, wherein the porous bonding matrix has a pore volume of 10-80%, preferably 30-50%, more preferably 35-45%.

3. Dressing tool as claimed in claim 1, wherein the porous bonding matrix comprises an inorganic oxide material, preferably the inorganic oxide material containing Al₂O₃, ZrO₂, SiO₂, Fe₂O₃and/or ZnO.

4. Dressing tool as claimed in claim 1, wherein the porous bonding matrix comprises an inorganic nonoxide material, especially a carbide and/or a nitride, and especially preferably the inorganic nonoxide material containing SiC, B₄C, Si₃N₄, TiC, Fe₃C, TiN and/or WC.

5. Dressing tool as claimed in claim 4, wherein the porous bonding matrix consists of a combination of inorganic oxide material and inorganic nonoxide material.

6. Dressing tool as claimed in claim 1, wherein the porous bonding matrix contains a metallic phase and/or an intermetallic phase, preferably the metallic phase and/or the intermetallic phase containing Cu, Sn, Zn, Fe, Co, Ni, Ag, Cr, V, Zr, Mn and/or Al.

7. Dressing tool as claimed in claim 6, wherein the metallic phase and/or intermetallic phase in the porous bonding matrix has a volumetric proportion of 5-60%.

8. Dressing tool as claimed in claim 1, wherein the porous bonding matrix has an open pore structure.

9. Dressing tool as claimed in claim 1, wherein the function coating is produced by a sintering process.

10. Dressing tool as claimed in claim 1, wherein the grain size of the hard material grains is 20-600 μm, preferably 80-100 μm.

11. Dressing tool as claimed in claim 1, wherein the hard material grains are present in the form of diamond grains, preferably the volumetric proportion of the diamond grains being 30-40%.

12. Dressing tool as claimed in claim 1, wherein the function coating is built up in several layers.

13. Dressing tool as claimed in claim 1, wherein the minimum thickness of the function coating corresponds at least five times, especially preferably at least ten times, to an average grain diameter of the hard material grains.

14. Dressing tool as claimed in claim 1, wherein the reinforcing elements are present as elongated or cuboidal rods, preferably the ratio of the length of the cuboidal rod to thickness and/or width of the cuboidal rod having a value of 2-7.

15. Dressing tool as claimed in claim 1, wherein the reinforcing elements consist solely of diamond, except for inevitable impurities.

16. Dressing tool as claimed in claim 1, wherein the reinforcing elements consist of a composite material, especially the composite material containing diamond and a metallic phase.

17. Dressing tool as claimed in claim 16, wherein the diamond in the composite material has a proportion by weight of 80-90% and the metallic phase has a proportion by weight of 10-20%.

18. Dressing tool as claimed in claim 1, wherein the reinforcing elements are located bordering one edge and/or one side surface of the function.

19. Dressing tool as claimed in claim 1, wherein the base body is made rotationally symmetrical with respect to the axis of rotation and is present especially as a disk and/or ring, especially preferably the base body consisting of metal.

20. Dressing tool as claimed in claim 19, wherein the reinforcing elements with their longitudinal middle axes are located in the radial direction of the base body.

21. Dressing tool as claimed in claim 1, wherein the reinforcing elements are additionally anchored in the base body.

22. Use of a dressing tool as claimed in claim 1, for conditioning of grinding bodies, preferably ceramically bonded grinding bodies and especially preferably grinding bodies of cubic boron nitride.