Method for generating a toothed workpiece and control program, tools and tooth-cutting machine suitable therefor

Abstract

The invention relates to a method for generating a workpiece (3) having a second tooth system (2) incorporated into a first tooth system (1) having a specified tooth system geometry, wherein a first generative processing engagement, intersecting the second tooth system in the kinematics of the generating skiving, is made on the workpiece, which is in particular oversized in relation to the specified tooth system geometry, in particular on a transition from the first to the second tooth system, and then a second processing engagement, matching the specified tooth system geometry, in the kinematics of the generating skiving is carried out on the transition and a remaining oversize is in particular removed while doing so. The invention further relates to tools and to tooth-cutting machines suitable therefor.

Claims

1. Method for generating a workpiece (3) having a second toothing (2) incorporated into a first toothing (1) having a predefined toothing geometry, wherein a first machining operation that generates the second toothing in the kinematics of skiving by means of cutting is carried out on the workpiece which still has an oversize (Δ) relative to the predefined toothing geometry at a transition from the first to the second toothing, and then a second machining operation which matches the predefined toothing geometry is carried out in the kinematics of skiving at the transition and thereby remaining oversize is removed.

2. Method according to claim 1, wherein the first machining operation ceases at the transition so as to have an axial cutting direction component directed toward the transition and the second machining operation has an axial cutting direction component aligned to said cutting direction component.

3. Method according to claim 1 wherein the oversize is at least 6 μm and/or at most 1.6 mm.

4. Method according to claim 1 wherein the oversize present before the first machining operation is carried out extends over the full toothing width of the first toothing (1) and is removed in the second machining operation.

5. Method according to claim 1 wherein the first and the second machining operation is carried out by the same rotationally driven tool shaft (C2, CW).

6. Method according to claim 1 wherein a tool-side operating region of the first machining operation differs from the tool-side operating region of the second machining operation.

7. Method according to claim 1 wherein the first machining operation is carried out in a one-flank process.

8. Method according to claim 1 wherein the second machining operation is carried out in a two-flank process.

9. Method according to claim 1 wherein workpiece clamping of the workpiece is maintained between the first and the second machining operation.

10. Method according to claim 1 wherein the position and/or orientation of the workpiece rotational shaft (C, C′) remains unchanged between the first and the second machining operation.

11. Method according to claim 1 wherein a toothing machining process for providing the workpiece subjected to the first machining operation is carried out in the kinematics of the skiving using the same tool-side operating region as that of the second machining operation.

12. Method according to claim 11 wherein the workpiece, in the region of the first toothing, has an inner edge with the inner edge having a burr thereon, wherein the inner edge is deburred by means of an operating region which is movement-coupled to the tool-side operating region of the first and/or second machining operation.

13. Method according to claim 1 wherein deburring is carried out on an outgoing end of the first toothing after the second machining operation.

14. Control program for a toothing machine, which program, when executed on the toothing machine, controls the toothing machine in order to carry out a method according to claim 1.

Description

(1) Further features, details and advantages of the invention can be found in the following description with reference to the accompanying drawings, in which

(2) FIG. 1 is a schematically simplified view of a sectional view of an internal toothing taken orthogonally to the workpiece shaft,

(3) FIG. 2 schematically illustrates tooth flank machining processes in a sectional view A-A from FIG. 1,

(4) FIG. 3 schematically illustrates a tooth root machining process using sectional views B-B from FIG. 1,

(5) FIG. 4 shows a tandem tool,

(6) FIG. 5 shows a triple tool,

(7) FIG. 6 shows a skiving machine, and

(8) FIGS. 7 and 8 illustrate a different machine concept to that in FIG. 6.

(9) FIG. 1 schematically shows a cross section of an internal toothing 3. The left-hand flanks of the workpiece teeth 4 are denoted by 5, and the right-hand flanks are denoted by 6. Furthermore, the tooth head of the internal toothing 3 is denoted by 7 and the tooth root of the internal toothing is denoted by 8.

(10) However, the internal toothing 3 is not uniform over its axial length, but instead has a first toothing 1 and a second toothing 2 introduced into the first toothing 1, which second toothing is not shown in FIG. 1.

(11) An example of a toothing geometry of the internal toothing 3 on the tooth flanks can be seen in FIG. 2d, in which the first toothing 1 is shown in the axially lower region, and the second toothing 2 introduced therein is shown in the upper region. Dotted lines in FIG. 2d show the geometry of a pre-toothing, and this corresponds to the solid lines in FIG. 2a, in which in turn the toothing geometry of the first and second toothing that is to be generated is shown in dotted lines.

(12) In one embodiment of the invention, the workpiece is generated or the second toothing is incorporated into the first toothing as follows:

(13) First, a pre-toothing for the first toothing, which still has an oversize Δ on the left-hand and right-hand tooth flank, is generated by means of skiving, in this case in a two-flank process using a first skiving wheel 11, the cutting edges of which are denoted by 12. This is achieved, for example, in a plurality of roughing passes having axial advancement in FIG. 2a from top to bottom in the kinematics of the skiving, in which the rotational axis of the skiving wheel is at an axis intersection angle to the rotational axis of the internal toothing 3 (helical gear system principle).

(14) In the next step, the second toothing 2 is introduced by means of a second skiving wheel 13, the cutting edges of which are denoted by 14. Whereas previously (FIG. 2a) a two-flank process was preferably used, this introduction is preferably carried out in a one-flank process, first on the one flank (FIG. 2b) and then on the other flank (FIG. 2c). This creates a burr 16 at the run-out of the second toothing. This burr-generating operation in FIGS. 2b and 2c corresponds to the first machining operation. The skiving wheel 13 for the first machining operation is in this case designed differently to the skiving wheel 11 which generates the pre-toothing of the toothing geometry of the first toothing. However, at least in this embodiment, part of a multiple tool, such as a tandem or triple tool, is coaxial to the skiving wheel 11.

(15) The skiving wheel 13 and the axis intersection angle set in the first machining operation are selected so as to match the type of second toothing. Unlike that shown in FIG. 2, this could also be conical and in particular represent a deposit introduced into the first toothing.

(16) In a further machining step, the (remaining) oversize Δ is removed from the first toothing by means of a skiving wheel which is designed for the machine shaft controls used for generating the first toothing having the predefined toothing geometry. In this embodiment, this skiving wheel is the same skiving wheel 11 which was also used in the step shown in FIG. 2a for generating the pre-toothing which matches the tooth geometry except for the oversize Δ.

(17) Naturally, no machining process is carried out in the region of the second toothing 2, since no material is present in this region in the corresponding advancement position. However, as a result of the machining in the transition from the second toothing to the first toothing, the burr 16 is also eliminated by the removal of the oversize Δ. In this example this second machining operation is again carried out in a two-flank process.

(18) This machining method is time-optimized to the extent that no finishing passes in the production of the pre-toothing have to be carried out before the second machining operation; one or more final removing passes in the finishing can be carried out in the second machining operation in an additionally axially shorter region in which burr removal occurs simultaneously. Overall, this results in correspondingly short machining times for the operations themselves.

(19) If, as in one preferred embodiment, the toothing pre-machining process (FIG. 2a), the first machining operation (FIG. 2b, c) and the second machining operation (FIG. 2d) are also carried out in the same clamping of the internal toothing 3 and in particular using different operating regions of a multiple tool, this results in a comparatively very short total machining time and satisfactory toothing quality of the internal toothing 3.

(20) FIG. 3 also shows how the root 8 of the internal toothing 3 can be machined according to a similar procedure, as shown in FIG. 2, namely when the difference between the first toothing and the second toothing also changes in the root 8 of the internal toothing. During the pre-machining for the first toothing 1, an oversize Δ.sub.F can remain in the root region, which oversize is only removed in the region of the first toothing in the second machining operation (FIG. 3c) after the root of the second toothing 2 is machined in the first machining operation (FIG. 3b). In turn, the burr in the root region that is produced in the first machining operation is in this case eliminated in the second machining operation. However, types of introduced second toothing in which, for example, the functional surfaces of the second toothing only have to act on the flanks, and the internal toothing 3 in the root region is uniform, are also conceivable. In this case as well, an oversize Δ.sub.F could be left in the region of the foot 8, which oversize is removed in the second machining operation.

(21) The removals described in FIGS. 2a and 3a are carried out in this case in the context of a same (preparatory) step, and FIGS. 2d and 3c also correspond to the same machining operation. The illustration in FIG. 3b (root machining of the second toothing 2) is a simplified representation of the fact that, when the second toothing is generated in a one-flank process, the root machining could be generated from the machining processes, corresponding to FIGS. 2b and 2c, which are carried out respectively in a one-flank process and also include the root region. In principle, however, it could also be conceivable for the second toothing to be machined in a two-flank process, but the one-flank machining process allows more flexible operation with the options of separate tangential movements and/or additional rotations and, inter alia, also allows deeper cuts in the tooth root to be dispensed with. In one embodiment, the first machining operation can therefore also be limited to the tooth flanks. Conversely, in a different embodiment, the second toothing could also only extend in the root region.

(22) In order to simplify the illustrations in FIGS. 2 and 3, the regions of the relevant cut that have not yet been machined, i.e. those below the cutting edges, are also shown as if a material removal has already taken place, although this only takes place in these regions after further advancement.

(23) In one variant not shown in the figures, a finish-machining process of the first toothing 1 could be generated even before the introduction of the second toothing 2, without leaving an oversize Δ. The burr generated in the first machining operation for the incorporation of the second toothing 2 in the first toothing 1 would then be removable by means of an idle stroke of the first skiving wheel 11 in the region of the transition between the first and second toothing (second machining operation purely deburring).

(24) FIG. 4 shows a tandem tool 40 which has a first skiving wheel 41 and a second skiving wheel 42. The skiving wheels 41 and 42 are rigidly interconnected and have the same rotational axis CW. Using the first skiving wheel 41, the first toothing having the predefined tooth geometry can be generated, for example an impeller toothing. Using the second skiving wheel 42, the second toothing can be introduced into the first toothing. In the relevant machining process, the tool rotational axis CW is at an axis intersection angle to the workpiece rotational axis. In order to avoid collisions, for the machining of external toothings the external diameter D2 of the skiving wheel 42 is smaller than the root diameter D1f of the first skiving wheel 41. For the machining of internal toothings, D2 is preferably no greater than 0.9 D1f. D2 is preferably no greater than 0.8 D1f, in particular no greater than 0.6 D1f. Even values of up to 0.4 D1f or 0.3 D1f for D2 are conceivable, even if small chip curves are formed when using correspondingly small skiving wheels. In order to avoid this, in particular D2 can be at least 40% of D1f, in particular at least 60% of D1f, even 80% or more of D1f, for external toothings. In a further preferred variant, the modules of the first skiving wheel 41 and of the second skiving wheel 42 are substantially the same, and preferably differ by no more than 20%, more preferably no more than 10%, in particular no more than 5%.

(25) The axial distance L12 between the cutting edges of the second skiving wheel 42 and the first skiving wheel 41 is selected so as to be sufficiently large to prevent a risk of collision with the first skiving wheel 41 for the axis intersection angle set for the first machining operation. However, this distance L12 is preferably no greater than 2.4 D2f, in particular no greater than 2.0 D2f, and in particular no greater than 1.6 D2f. This reduces the risk of vibrations occurring during the first machining operation and during the introduction of the second toothing into the first toothing of the workpiece.

(26) As already explained above, however, separate skiving wheels 41, 42 could also be used for this implementation, for example on two provided tool spindles or in the tool change on a tool spindle.

(27) FIG. 5 shows a triple tool 50 which has a first skiving wheel 51 and a second skiving wheel 52, the arrangement of which can be the same as that of the skiving wheels 40 and 41 in FIG. 4. However, in contrast to the tandem tool in FIG. 4, a deburring disc 53 is also arranged axially from the second skiving wheel 52.

(28) With regard to the diameter D3 of the deburring disc 53, the same relationships apply between D3 and D2f as for the relationships between D2 and D1f explained above with reference to FIG. 4.

(29) The axial dimension L3 of the deburring disc 53 is in this case selected to be so small that the deburring disc 53 can be inserted into a groove provided on the workpiece, for example, and can deburr burrs from toothing edges on the groove. For this purpose, the axial distance L23 is selected to be sufficiently large, namely greater than the distance from the end of the toothing that is near the machining to the groove or to the provided working region of the deburring disc 53. Optionally, the distance L23 can also be greater than the wheel width of the machined toothing, and the end of the first toothing at which the movement ceases could then also be deburred by means of the deburring disc 53.

(30) The terms “tandem tool” or “triple tool” mean a combination tool comprising at least the two skiving wheels or additionally the deburring disc, but additional, in particular further coaxial tools can also be part of the combination tool. However, pure tandem or pure triple tools having just the second or third tools are also conceivable.

(31) The tandem tool from FIG. 4 or the triple tool from FIG. 5 could be clamped, for example, in the tool clamping means of a skiving machine 100 shown in FIG. 6. The skiving machine 100 is controlled via a control system, shown schematically by 99, in order to carry out a method according to any of the method aspects explained above. For this purpose, the skiving machine 100 has, on the workpiece side, a workpiece spindle 70 arranged on a machine bed 80, which spindle is in this case designed as a vertical spindle. On the tool side, a radial carriage 61 which can be moved in the radial advancement direction X relative to the machine bed 80 is provided, on which carriage an axial carriage 62 movably mounted relative thereto in the axial direction Z pivotably supports a tangential carriage 63, on which the tool head having the tool spindle shaft C2 is arranged. The pivot shaft A is in this case parallel to the radial shaft X and allows the tool spindle shaft C2 and thus the tool rotational shaft CW to pivot in the Y-Z plane, in order to set the axis intersection angle Σ between the tool rotational axis and workpiece rotational axis of a workpiece clamped on the workpiece spindle 70, which workpiece can be an internally or externally toothed workpiece (or even a workpiece having both internal and external toothing).

(32) The machine shown in FIG. 6 is a CNC-controlled machine comprising individual drives for the movement axes shown. However, simpler machine variants on which the methods can be executed are also conceivable; for example, the tangential carriage 63 could be dispensed with and the tool head could be arranged so as to be able to pivot relative to the axial carriage 62 without tangential displaceability. The pivot shaft A would also not have to be a motor-adjusted machine shaft, provided that different axis intersection angles can be determined.

(33) In a further example of a different design of a toothing machine, for example, the concept of a pick-up machine comprising a suspended workpiece spindle 70′ can be used, which spindle is mounted, for example, so as to be axially displaceable (Z′) and can be displaced in a tangential direction between a first machining position shown in FIG. 7 for generating the first toothing or the second machining operation and a second machining position (FIG. 8) for introducing the second toothing. In this variant, a first tool spindle having a tool spindle shaft C2a supports a skiving wheel 41′ for generating the first toothing (pre-toothing and second machining operation), and a second tool spindle having a rotational shaft C2b supports a second skiving wheel 42′ for the incorporation of the second toothing (first machining operation).

(34) The invention is not limited to the variants described in the above examples, but instead the features of the above description and the following claims may be essential, individually and in combination, for implementing the invention in its different embodiments.