TECHNICAL FIELD OF THE INVENTION
- BACKGROUND OF THE INVENTION
The present invention relates to tube bending apparatus. Particularly, the present invention is directed to an improved portable tube bending apparatus.
Known tube bending apparatus typically comprise a mandrel and forming member components supported for relative angular displacement about a bending axis. The mandrel has a bending groove extending about the bending axis. A tube positioned between the mandrel and forming member is adapted to be bent during selected relative angular displacement of the mandrel and forming member about the bending axis. Relative angular displacement between the mandrel and forming member can be achieved in a number of different ways.
In some motor driven benders, the mandrel is mounted on a support and the forming member is mounted on the support for angular displacement relative to the mandrel and is so displaced by a motorized drive arrangement.
U.S. Pat. Nos. 5,022,249; 4,986,104; and 5,301,530 describe portable tube bending apparatus.
- SUMMARY OF THE INVENTION
The present inventors have recognized that a need exists to improve the aforementioned tube benders and to provide a tube bender that is lightweight and easily portable, that is of a simplified construction, and that can bend tubes to variable bend radii.
The invention provides an improved portable bending apparatus for bending tubes or other elongated workpieces.
According to the preferred embodiment, the portable bending apparatus includes a frame, a major gear, a forming member, a tube guide and a gear mechanism. The major gear is mounted rotatably to the frame about a bending axis. The major gear has gear teeth on an outer perimeter thereof. The forming member is fixed to a front side face of the major gear, the forming member having at least one arcuate forming surface and a restraint. The tube guide is mounted to the frame. The gear mechanism has an input connected to a geartrain connected to an output gear. The geartrain provides a speed reduction between the input and the output gear.
The input is configured to receive rotary input from a handheld motorized driver, such as a portable drill. Alternately, a dedicated, permanently attached electric motor can be mounted to the frame.
The output gear is enmesh with the gear teeth of the major gear. When a workpiece to be bent is placed on the tube guide, or in some cases simply held by the operator, and within the restraint and against the forming surface, and the input receives rotary motion from the handheld motorized driver, the restraint and the forming surface are driven to orbit about the bending axis and the forming surface bends the workpiece braced between the restraint and the tube guide, or braced between the restraint and the operators hand.
Preferably, the frame comprises a base bar, a vertical column, and an angular brace. The vertical column is fixed at a base end to the base bar and at an elevated end to a gear mechanism support plate. The angular brace is fixed at a base end to the base bar and at an elevated end to the vertical column. The tube guide is mounted to the base bar.
A strut can be attached to the frame and extends to a position to engage a body of the motorized driver. The strut is sufficiently rigid to resist reaction torque exerted by the input on the motorized driver. The strut can include a hook end configured to engage a handle of the motorized driver.
While the present invention is advantageous in connection with portable, motor driven tube benders, it will be appreciated that the invention is applicable to bending other workpieces such as rods.
BRIEF DESCRIPTION OF THE DRAWINGS
Numerous other advantages and features of the present invention will be become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.
FIG. 1 is a front elevational view of a tube-bending apparatus according to the invention, shown in an initial, tube-loaded orientation;
FIG. 2 is affront elevational view showing the apparatus of FIG. 1 in a final, tube-bent orientation;
FIG. 3 is a left side view of the apparatus of FIG. 2;
FIG. 4 is a right side view of the apparatus of FIG. 2;
FIG. 4A is a sectional view taken generally along line 4A-4A of FIG. 4;
FIG. 4B is a sectional view taken generally along line 4A-4A of FIG. 4 of an alternate arrangement;
FIG. 5 is a rear elevational view of the apparatus of FIG. 2; and
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 6 is a front perspective view of the apparatus of FIG. 2 with portions removed for clarity; and
While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred features of the invention. It will be understood, however, that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific form of the combination of features that are illustrated and described.
FIGS. 1 through 6 illustrate an exemplary form of the apparatus 20 of the present invention used to bend a tube T. The apparatus 20 is configured to be used with a portable motorized driver, such as a hand held drill 24. Alternately, a dedicated, permanently mounted electric motor can be used. The illustrated portable drill is a battery powered drill. FIG. 1 illustrates the apparatus in an initial position with the tube T to be bent loaded into the apparatus. FIGS. 2-6 illustrate the apparatus 20 after it has been moved into a final position and the tube T has been bent approximately 90 degrees.
The apparatus includes a frame 28 comprising a base bar 32, a vertical column 36, and an angular brace 38. The members 32, 36, 38 can be rectangular cross section members, solid or hollow. The members can be composed of steel or aluminum, or other material. The members 32, 36, 38 can be fastened together, cast together, welded together, or otherwise formed as a single unit. Four rubber feet 32 a can be mounted to the base bar to support the frame 28 off of a horizontal surface.
A tube guide 42 is fixed to the base bar 32, such as by fasteners 43. Fastening is advantageous in that different guides for different size conduits or tubes can be attached as desired. A main gear 50 and a gear mechanism 54 are mounted to the column 36. The main gear 50 is rotatably mounted to the column 36 by a bearing 55 about a bending axis 56. The vertical column 36 can include widened portions or plates 36 a, 36 b (FIG. 5) that are used to mount the gear mechanism 54 and the main gear 50. The portions 36 a, 36 b can also be fixed to the angular brace 38 for rigidity. A forming member or shoe 58 is fixed to the main gear 50. The shoe 58 can be fixed to the main gear 50 by use of fasteners or by welding. Fastening is advantageous in that different shoes for different size conduits or tubes can be attached as desired. Shoes can include one or more bending surfaces, for example for bending ½ inch, ¾ inch or 1 inch conduits.
The main gear 50 can include a bending angle scale 51 that indicates the degree of bending of a workpiece during operation of the apparatus.
A strut 62 (FIGS. 1 and 1A) is adjustably fastened to the angular brace 38. The strut 62 is preferably a sturdy steel or aluminum member. The strut 62 includes a U-shaped end portion 64 having a plastic covering 66, and a shank 67. The shank 67 can have a threaded region 68 that passes through a hole 72 (FIG. 2) through the angular brace 38. Nuts 74, 76 (FIG. 2) can selectively and fixedly locate the shank 67 on the angular brace 38. The U-shaped end portion is configured to engage a handle 24 a or other portion of the drill 24. A strap 64 a having a surface fastener such as a hook and loop fastening surface 64 b can be connected to one arm of the U-shaped end and can pass over the handle 24 a and attach to a hook and loop fastener 64 c adhered to the other arm of the U-shaped end. As an alternate to the threaded region 68 and the nuts 74, 76, cotter pins or quick release pins that penetrate through the shank 67 through selectable holes along a series of spaced apart holes could be used. Alternatively the angular brace 38 could have a threaded hole to receive the threaded region 68. In either case, the strut 62 is releasable to, adjustable toward and away from the handle 24 a so that the drill 24 can be supported from the apparatus 20.
The strut 62 resists opposite reaction torque on the drill handle 24 a exerted by the gear mechanism 54 due to the drill driving the apparatus 20 and bending the tube T. This reduces the exertion required by an operator of the drill 24 and avoids a sudden twisting torque on the operator's wrist. Also, the strut supports the drill handle 24 a vertically to resist the torque caused by gravity, i.e. the overhanging load of the weight of the drill about the drill chuck connection to the gear mechanism. This support also relieves the operator the exertion of holding up the drill.
The shoe 58 includes one or more forming surfaces. In the illustrated embodiment two forming surfaces 80, 82 are provided. The forming surfaces are generally oriented with a concavity facing away from the bending axis 56. The forming surface 80 is behind the forming surface 82 in FIG. 1 and also has a greater bending radius measured from the bending axis 56. The forming surface 80 can be sized to bend a larger diameter tube, such as a 1 inch tube, than the forming surface 82, such as a ¾ inch tube, since the bending radius is greater. Different forming surfaces can be provided to accommodate different sizes of tubing or other workpieces.
At an end of each bending surface 80, 82 a restraint 84, 86 is fixed to rotate with the bending surface 80, 82. Preferably, the restraints 84, 86 are formed in unitary fashion with the shoe 58. The restraints 84, 86 are open, hook-like portions (FIG. 4A) that allow easy loading and unloading of a tube into the restraint but underlies the loaded tube in a radial direction from the bending axis 56 to exert a radial inward bending force B (FIG. 2) on the tube as the shoe 58 orbits about the bending axis 56. The restraints 84, 86 include gripping teeth 87 formed therein for preventing axial slipping of the tube within the restraint during bending.
FIG. 6 illustrates the tube guide 42 includes a higher support groove 42 a in the foreground of FIG. 6 and a lower support groove 42 b behind the support groove 42 a.
Also, FIG. 6 illustrates the gear mechanism 54 having a cover removed for clarity. According to the exemplary embodiment, the gear mechanism 54 was salvaged from a POWERBLADE™ Cable Cutter Model 35-078 available from Ideal Industries Incorporated of Sycamore, Ill., USA. The mechanism includes a geartrain (not shown) within a housing 54 a. According to the preferred embodiment the turn ratio or reduction of the gear mechanism is 40:1. An input such as an input shaft 54 b is gripped by a chuck 24 b of the drill 24. The input shaft 54 b communicates rotary energy to the geartrain. The geartrain communicates rotary energy at a reduced speed to an output gear 54 c. The output gear 54 c is enmesh with gear teeth 50 a on the circumference of the main gear 50. According to the preferred embodiment, the overall turn ratio or reduction between the drill 24 and the main gear 50 is 360:1.
In operation, the shoe 58 is rotated to a start position as shown in FIG. 1. The tube is inserted beneath the selected bending surface 80, 82 and into the respective restraint 84, 86. The tube can be supported on the respective groove 42 a, 42 b of the tube guide 42. The tube is now loaded and ready for bending. The drill 24 is actuated to rotate the input shaft 54 b which drives the geartrain, which drives the output gear 54 c, which drives the main gear 50, which orbits the shoe 58 to the position shown in FIG. 2, or to any selected intermediate position between FIGS. 1 and 2 depending on the angular bend desired, wherein the drill on button is released to turn the drill off. Because an end of the tube was restrained in radial position by the respective restraint 84, 86 and a straight end of the tube was braced on the tube guide 42, the bending surface 80, 82 pressing against the top half of the tube conformed the tube to the contour of the bending surface 80, 82. The bent tube T can be unloaded from the apparatus 20.
As shown in the alternate section of FIG. 4B, the restraints 84, 86 can be hinged along lines 84 a, 86 a to open up by swinging about the directions 84 b, 86 b for conduit placement. The restraints are arranged to swing away from the main gear 50 to open. Latches (not shown) can be provided as needed to hold the restraints in the closed position.
The apparatus 20 provides a portable tube bending apparatus that is configured in an easy to use upright configuration. The apparatus can be driven by a portable electric drill that is also oriented in an easy to use orientation, inclined upwardly toward the user. The apparatus illustrated uses a minimal frame that can be supported and/or attached to scaffolding or lift baskets of construction equipment so that electrical work can proceed effectively at hard to access locations. For attaching to external supports, the base bar 32 can be a channel as shown in FIG. 3A wherein a side clamp member 120 is threaded into a side of the channel to clamp an external support member 124 within the channel. A block 126 can be fixed, fastened, or placed inside the channel to brace a backside of the support member 124. A plurality of side clamp members 120 can be provided spaced along a length of the base bar 32.
From the foregoing, it will be understood that numerous variations and modifications may be effected without departing from the true spirit and scope of the novel concept of the invention. It is to be understood that no limitation with respect to the specific method, apparatus, and product illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.