Method for producing a removal of material on a tooth end edge and device designed therefor

Abstract

The invention relates to a method for producing a removal of material on a tooth end edge of a workpiece toothing with a rotationally driven chamfering tool in a machining operation brought about by controlled axial machine movements between the chamfering tool and the likewise rotationally driven workpiece toothing, wherein material is removed with a geometrically undefined cutting edge and the removal takes place in a coordinated action between a profiling, in particular, an alterable profiling, of the chamfering tool and a machine control used for the machining operation, performed in dependence on predetermined parameters that are characteristic of the removal of material to be produced.

Claims

1. A method for producing a chamfer by removal of material on a tooth end edge of a workpiece toothing (W) with a rotationally driven chamfering tool (6a, 6b) in a machining operation brought about by controlled axial machine movements between the chamfering tool and the likewise rotationally driven workpiece toothing, characterized in that material is removed with a geometrically undefined cutting edge, and the removal takes place in a coordinated action between a profiling of the chamfering tool and an axial machine control used for the machining operation, performed in dependence on predetermined parameters that are characteristic of the chamfer to be produced, wherein the chamfering tool is a first chamfering tool (6a), and the chamfer produced therewith is a first chamfer on a flank of a tooth gap, and wherein a second chamfer, characterized by different parameters is produced on the other flank of the tooth gap with a second chamfering tool (6b) that is different from the first chamfering tool.

2. The method according to claim 1, wherein the machining operation is a skiving machining operation, and the chamfering tool is helical in shape.

3. The method according to claim 1 wherein the coordinate action comprises dressing that alters the profile of the chamfering tool.

4. The method according to claim 3, wherein the control parameters of the axial machine control are at least partially recalculated in a manner at least partially overlapping in time with the dressing.

5. The method according to claim 1, wherein the first and second chamfers are produced in chronological succession.

6. The method according to claim 1, wherein both the chamfering tools are driven by the same drive.

7. The method according to claim 1 wherein the characterizing parameters for the first and/or second chamfers contain a predetermined shape.

8. The method according to claim 1 wherein the characterizing parameters of the first and/or second chamfers contain one or more boundary conditions for the first and/or second chamfers.

9. The method of claim 1 wherein said profiling comprises an alterable profiling.

Description

(1) Other features, details, and advantages of the invention arise from the following description with reference to the accompanying drawings, in which:

(2) FIG. 1 illustrates a chamfering device in a perspective view;

(3) FIG. 2 schematically illustrates the machining operations on a right flank (FIG. 2A) and left flank (2B) of a workpiece toothing;

(4) FIG. 3 illustrates a view of a dressing operation between a dressing roller and a chamfer screw; and

(5) FIG. 4 illustrates an explanatory sectional view of the assigning of operation regions of the dresser, the chamfer screw, and the workpiece toothing.

(6) FIG. 1 depicts a perspective view of a chamfering machine 100. The machine 100 bears, on one side of a machine bed 1 thereof, a workpiece spindle 8 on which a workpiece W—which, in this embodiment, is helically toothed—is clamped. Provided on the opposite, workpiece-side side of the machine bed 1 is a radial slide 2, which is plate-shaped in this embodiment and via an axis of movement X of which the axial distance between the workpiece axis—designated axially with W.sub.2—and the tool axis can be set, wherein the workpiece axis of rotation is designated as a machine axis of rotation with C and the tool axis of rotation is designated as a machine axis of rotation with B1. The radial slide 2 has set thereon a transverse slide 3, which has a tower-shaped design in the present embodiment and an axis of movement Y that runs transversely—in this embodiment, orthogonally—to the radial axis X. The slides 2 and 3 thus form a cross-slide assembly.

(7) A lifting slide 4, an axis of movement Z of which has a component in the direction of the workpiece axis W.sub.2 and, in this embodiment, runs parallel thereto is arranged on the side of the transverse slide 3 that faces the workpiece W. The lifting slide 4, in turn, has arranged thereon a tool head 5 equipped with a drive that, in this embodiment, is designed as a direct drive, i.e., with another rotary degree of rotational freedom A. The axis of rotation A is provided so as to be parallel to the radial infeed axis X in this embodiment.

(8) The tool head 5 is designed such that a chamfering tool 6a, 6b, which removes material with a geometrically undefined cutting edge and is rotationally driven here by the direct drive, is arranged on the left and right side with respect to the extension seen along the radial axis X. The chamfering tools 6a, 6b are made in the form of dressable grinding worms.

(9) As is better shown in FIG. 2, the two dressing worms 6a, and 6b are each provided for single-flank grinding. Thus, the chamfering screw 6a on the tooth end edge of the right flanks (blunt edge) of the helical toothing produces the desired chamfer shape (see FIG. 2a), whereas the other chamfer screw 6b is provided in order to produce the chamfers on the tooth end edges of the left flanks (sharp edge) of the workpiece (see FIG. 2b).

(10) With work being done on the blunt edges (FIG. 2a), a pivot angle A.sub.A (=90°-A in FIG. 2A) of, in this embodiment, more than 20° incline is set via the axial machine control. The machining is also performed eccentrically; here, the site of machining is offset by at least one tooth gap width relative to a parallel, going through the workpiece axis W.sub.2, to the radial axis X in the tangential direction Y.

(11) Ideally, the shadow casting of the opposing flank on the tooth flank to be machined is used for viewing the maximum eccentricity of the tool operation point and the maximum rotation of the tooth flank to be machined out from the machine center in order to produce a maximum chamfer angle on a tooth flank in such a manner that only just no shadow is cast by the opposing flank on the tooth flank to be machined, wherein the direction of the light in order to produce the cast shadow runs parallel to the radial axis of the machine.

(12) With abrasive chamfering of the sharp edge (FIG. 2B), however, a pivot angle A.sub.B (=90°-A in FIG. 2B) of less than 12° is set, preferably less than 8°, in particular, less than 4°. In particular, the tool axis of rotation (with a vertical workpiece axis W1) may run almost horizontally. It is also provided with this machining that the chamfer screw 6b works almost centrically, with a tangential offset of—in this embodiment—less than one tooth gap width.

(13) As is can be seen further in FIG. 1, a dressing device 12, which is depicted schematically in FIG. 3, is arranged between the workpiece spindle 8 and the tool side. The dressing device 12 in this embodiment has a dressing roller 13, which can rotate about an axis of rotation B2 that is provided, for example, parallel to the axis of movement Z. The workpiece-side axes of movement X, Y, Z and A can be used to bring a chamfer screw into a dressing operation with the dressing roller 13.

(14) Though not depicted in the drawings, two dressing rollers 13a, 13b are also provided in this embodiment, one of which is provided for dressing the chamfer screw 6a provided for the blunt edge and one of which is provided for the chamfer screw 6b provided for the sharp edge. The respectively mating regions are depicted in FIG. 4, in which, as seen in the section, the shape of the chamfer on the sharp edge is depicted bottom left and the shape of the chamfer on the blunt edge is depicted bottom right, in each case with a section on the toothing, whereas the upper section of FIG. 4 depicts the profile-producing profile of the respective dressing rollers in a section through the chamfer screw.

(15) Instead of or in addition to the profile-dressing dressing rollers, however, the dressing device could also be designed for shape dressing. When non-dressable grinding worms are used as chamfering tools, the dressing unit 12 may also be forgone, or still provided in order to for the machine to still offer the options of both dressable and non-dressable grinding tools to be chamfered.

(16) A chamfering operation with the chamfering machine 100, then, proceeds by way of example as follows:

(17) First, the toothing data on the workpiece to be provided with a chamfer is determined, including the parameters characterizing the chamfer. Examples of such chamfering characterizations are the shape of the chamfer, for example, ZKM, the chamfer angle, and the chamfer width, wherein, for example, the distance of the new oblique edge formed by the chamfer from the tooth end surface as measured at the orthogonal to the tooth end surface may be used as the chamfer width. The chamfer extends to the foot region and is, for example, comma-shaped. An alternative chamfer shape that would also be conceivable is, for example, a chamfer that tapers in the direction of the foot region of the tooth gap, but disappears before the foot region.

(18) The process design with the tool design, i.e., in this case, the determination of the profile for the chamfer screws 6a, 6b is now done in accordance with this toothing and chamfer data in a coordinated action with the axial machine controls provided for the process for the respective machining operation of the chamfer screws 6a, 6b, taking into account the above-mentioned influences.

(19) Provided that only individual workpieces having one chamfer are provided, the profile of the chamfer screws could be produced for that purpose, for example, separately outside of the machine by shape dressing. If, however, larger workpiece batches are to be machined, the chamfer screws would need to be reprofiled after a number of, for example, 50 to 100 chamfer processes. In this case, the above-described dressing rollers are preferably fabricated according to the tool design made.

(20) In the process itself, then, the tool axes are delivered by the machine control according to the process design made, thus bringing the chamfer screws 6a, 6b successively in a single-flank machining operation with the workpiece.

(21) The work then preferably follows the work sequence below: First, a chamfer is made with the chamfer screw 6a on the blunt edge on the upper side of the workpiece W facing the viewer in FIG. 1. Then, the chamfer screw 6a is removed from use, and instead the chamfer screw 6b is brought into engagement with the sharp edge at the upper side of the workpiece.

(22) After the chamfers on the upper side have been produced, the chamfers on the underside of the workpiece facing away from the viewer in FIG. 1 are produced accordingly. For this purpose, the tool head 5 is rotated relative to the machining on the upper side by 180°, so that, in turn, the correct relation of operation conditions between the chamfer screws 6a, 6b and the blunt edge/sharp edge of the helical toothing is restored.

(23) It would also be possible to alter this design. Thus, first, the chamfer screw 6a could work first on the upper side and then on the underside, and the chamfer screw 6b could then be used, as one example.

(24) The machining operation itself is a skiving machining operation, in which the chamfer screws 6a, 6b and the workpiece W rotate relative to one another in a synchronized manner. This is preferably achieved by CNC axial machine control, which controls both the workpiece and tool axes of rotation C, B1.

(25) After a number of iterations of machining, the tool head 5 is pivoted into a dressing position.

(26) If, now that a workpiece batch has been machined, a second batch of workpieces that has different chamfer parameters from those of the first batch is to be chamfered, which leads to another tool design, same may be initiated by exchanging the dressing rollers 13 that are designed for the profiling according to the new chamfer parameters. With the new dressing rollers 13′, the chamfer screws 6a, 6b can now be reprofiled before machining is started, so that no tool change needs to be done on the tool head 5 despite there being a batch change.

(27) If, however, the difference in the chamfer parameters is sufficiently small to be able to continue without changing the profile of the dressing worms, then the coordinated action is performed by altering the axial machine controls, and the dressing worm experiences additional movements reflecting this coordinated action with respect to the previous axial machine movements.

(28) The invention is not limited to the specific embodiments described in the examples above. Rather, the individual features of the description above and of the claims below may be essential for implementing the invention in the embodiments thereof.