METHOD FOR MACHINING A TOOTH FLANK REGION OF A WORKPIECE TOOTH ARRANGEMENT, CHAMFERING TOOL, CONTROL PROGRAM HAVING CONTROL INSTRUCTIONS FOR CARRYING OUT THE METHOD, AND GEAR-CUTTING MACHINE

Abstract

The invention relates to a method for machining a tooth edge formed between a tooth flank and an end face (2b) of the workpiece tooth arrangement (3), by means of a tool tooth arrangement (13), in which method the tooth arrangements (3, 13) rotate about their respective tooth arrangement rotational axes (C, B) in mutual rolling coupling, wherein the two tooth arrangement rotational axes (C, B) are substantially parallel to each other and the machining is carried out over a plurality of workpiece rotations, and wherein a first relative movement (Z) between the workpiece tooth arrangement (3) and the tool tooth arrangement (13), parallel to the workpiece rotational axis, is carried out and the position of the envelope (28) of the tool tooth rolling positions (29i) is shifted relative to the engagement position of said envelope with the tooth flank of the workpiece tooth arrangement in the plane (X-Y) orthogonal to the workpiece rotational axis (C), transversely to the profile of the workpiece tooth arrangement, by means of a second relative movement (V), which in particular is varied according to the movement state of the first relative movement. The invention also relates to a chamfering tool, to a control program having control instructions for carrying out the method, and to a gear-cutting machine.

Claims

1. Method for machining a tooth edge formed between a tooth flank and an end face (2b) of the workpiece tooth arrangement (3), by means of a tool tooth arrangement (13), in which method the tooth arrangements (3, 13) rotate about their respective tooth arrangement rotational axes (C, B) in mutual rolling coupling, characterized in that the two tooth arrangement rotational axes (C, B) are substantially parallel to each other and the machining is carried out over a plurality of workpiece rotations, and wherein a first relative movement (Z) between the workpiece tooth arrangement (3) and the tool tooth arrangement (13), parallel to the workpiece rotational axis, is carried out and the position of the envelope (28) of the tool tooth rolling positions (29i) is shifted relative to the engagement position of said envelope with the tooth flank of the workpiece tooth arrangement in the plane (X-Y) orthogonal to the workpiece rotational axis (C), transversely to the profile of the workpiece tooth arrangement, by means of a second relative movement (V), which is varied according to the movement state of the first relative movement.

2. Method according to claim 1, for machining a tooth edge formed between a tooth flank and an end face (2b) of a workpiece tooth arrangement (3), by means of a tool tooth arrangement (13), in which method the tooth arrangements (3, 13) rotate in rolling coupling about their respective tooth arrangement axes (C, B), and in which the machining on the tooth flank region creates a new tooth arrangement surface, in which the machining is carried out over a plurality of workpiece rotations, wherein a first relative movement (Z) with a directional component parallel to the workpiece rotational axis is carried out between the workpiece tooth arrangement (3) and the tool tooth arrangement (13), and the position of the envelope (28) of the tool tooth rolling positions (29i) is shifted relative to the engagement position of said envelope with the tooth flank of the workpiece tooth arrangement as seen in projection onto the plane (X-Y) orthogonal to the workpiece rotational axis (C), transversely to the profile of the workpiece tooth arrangement, by means of a second relative movement (V), which is varied according to the movement state of the first relative movement, and as a result, material is removed along a cutting surface during one pass of a respective workpiece rotation, wherein the shape of the new tooth arrangement surface is composed of the end regions of the cutting surfaces of the plurality of workpiece rotations.

3. Method according to claim 1, in which a transverse movement (Q) of the workpiece tooth arrangement and/or tool tooth arrangement running transversely to the center distance axis of the rotational axes contributes to the second relative movement.

4. Method according to claim 3, in which the transverse movement (Q) comprises an additional rotation (ΔC) of the workpiece tooth arrangement.

5. Method according to claim 3, in which the transverse movement comprises a movement of a linear machine axis (Y) whose directional component orthogonal to the workpiece rotational axis and orthogonal to the center distance axis (X) predominates over the respective directional component along these axes.

6. Method according to claim 1 in which the tooth edge in the tooth base of the workpiece tooth arrangement is also machined.

7. Method according to claim 1 in which a radial movement (ΔX) of the workpiece and/or the tool tooth arrangement running in the direction of the center distance axis of the rotational axes contributes to the second relative movement.

8. Method according to claim 3 wherein a chamfer (8) is produced on the tooth edge during machining and in which the shape of the chamfer (8) in the tooth base is effected by adjusting the radial movement according to the movement state of the first relative movement, and the shape of the material removal at the tooth edge in the tooth flank region is determined by adjusting the transverse movement according to the movement state of the first relative movement and the movement state of the radial movement.

9. Method according to claim 4 in which the profile of the material removal in the tooth height direction is determined by superimposing the transverse movement contributions from the additional rotation (ΔC) and the linear machine axis movement (ΔX, ΔY).

10. Method according to claim 1 comprising a further machining pass, said further machining pass being an identical or phase-shifted coupling of the first and second relative movement, but with a movement control carried out with a reverse movement direction of the first relative movement.

11. Method according claim 1 in which the rotational speed at the tooth tip of the workpiece is at least 10 m/min.

12. Method according to claim 1 in which a chamfer (8) is produced on the tooth edge during machining.

13. Method according to claim 1 in which the profile of the tool tooth arrangement is substantially that of the counter-tooth arrangement of the workpiece tooth arrangement with respect to the rolling coupling.

14. Method according to claim 1 which is carried out using a single-flank method, wherein other tooth flank(s) is/are machined following the machining of one tooth flank on one of the respective tooth gap(s) of the workpiece.

15. Method according to claim 14, in which the machining of the other tooth flank(s) is carried out with the same tool and/or in the same clamping process as the one tooth flank.

16. Method according to claim 1 in which the tooth thickness of the tool tooth arrangement is reduced when compared to the tooth thickness required for the rolling coupling for two-flank machining.

17. Method according to claim 1 in which the dimension (h) of the tool tooth arrangement along the tool rotational axis is less than 1.5 cm.

18. (canceled)

19. Chamfering tool (10) for machining a tooth edge formed between a tooth flank and the end face of a workpiece tooth arrangement, with machining carried out substantially with tooth arrangement rotational axes parallel to each other in mutual rolling coupling and in the form of a tool tooth arrangement with machining surfaces formed by the tooth flanks of the tool tooth arrangement for machining according to the method of claim 2.

20. Control program having control instructions which, when executed on a gear-cutting machine, controls the machine for carrying out a method according to claim 1.

21. Gear-cutting machine (100) having at least one workpiece spindle for rotatingly driving a workpiece tooth arrangement about its workpiece rotational axis (C), and at least one tool spindle for rotatingly driving a tool tooth arrangement about its rotational axis (C), at least one first machine axis (Z) which allows for a first relative movement between the workpiece tooth arrangement and tool tooth arrangement, parallel to the workpiece rotational axis, characterized by a control device (99) having control instructions for carrying out a method according to claim 1.

Description

[0049] Further features, details, and advantages of the invention can be found in the following description with reference to the accompanying drawings, in which

[0050] FIG. 1 shows a gear-shaped tool and a tooth arrangement machined by the tool;

[0051] FIG. 2 shows a section of the workpiece with a produced chamfer;

[0052] FIG. 3a is an explanatory view for producing the chamfer;

[0053] FIG. 3b shows an enlarged section from FIG. 3a;

[0054] FIG. 4 shows a momentary position during a retreating movement;

[0055] FIG. 5 shows an envelope shifted with respect to a workpiece tooth profile;

[0056] FIG. 6a, 6 are explanatory views of single-flank machining;

[0057] FIG. 7 is a representation of a comparatively thin tool tooth arrangement;

[0058] FIG. 8a, b are schematic representations of the machining of hard-to-reach tooth edges; and

[0059] FIG. 9 schematically shows a chamfering unit.

[0060] FIG. 1 is a perspective view of a workpiece 2 having an already manufactured internal tooth arrangement 3. In this embodiment, the internal tooth arrangement 3 is straight-toothed but it is also possible to machine helical tooth arrangement, as well as external tooth arrangements.

[0061] The machining operation shown in FIG. 1 takes place on the lower end face 2b of the workpiece 2; in this embodiment, the tooth edges of the substantially involute teeth 4 of the internal tooth arrangement 3 are to be provided with a chamfer on the end edge 2b. It goes without saying that a further chamfering process can then also be carried out on the other end face 2a. However, the method is also suitable for rollable non-involute workpiece tooth arrangements.

[0062] Machining is carried out with a tool tooth arrangement 13. For this purpose, a disc-shaped tool 10 is provided in this embodiment, which is externally toothed with the tool tooth arrangement 13. In this embodiment, the tool tooth arrangement 13 is the counter-tooth arrangement of the internal tooth arrangement 3. This means that, when the workpiece 2 and the tool 10 mesh with each other in synchronous rolling coupling, the teeth 14 of the tool tooth arrangement 13 immerse into the tooth gaps formed between the teeth 4 of the internal tooth arrangement 3 and roll off on the workpiece tooth flanks. The envelope of the rolling positions of the tool teeth 14 reflects the substantially involute profile on the tooth flank of the workpiece tooth 4. If, as in preferred method embodiments, machining is carried out using the single-flank process, the tooth thicknesses of the tool teeth 14 can also be designed to be thinner than is required for a contacting two-flank rolling engagement. As can also be seen from FIG. 1, no axis intersection angle is provided between the rotational axes C of the workpiece tooth arrangement 3 and B of the tool tooth arrangement 13; the rotational axes B and C run in parallel. The further axes X, Y, and Z, which are shown as a coordinate system in FIG. 1, can be realized partially or entirely as linear machine axes of a machine tool (not depicted), such as Z (feed, parallel to C), X radial axis (center distance direction), Y tangential direction.

[0063] The relative position between the tool tooth arrangement 13 and the workpiece tooth arrangement 3 shown in FIG. 1 is substantially the situation at the start of machining. Before the start of machining, the edges 6 set between the end face 2b of the workpiece 2 and the adjacent tooth flanks of the teeth 4 are still sharp-edged, for example, in a shape similar to that resulting from a previous method for producing the internal tooth arrangement 3, for example, by gear skiving, gear hobbing or gear shaping or other shaping methods, wherein primary burrs formed during the machining to produce tooth arrangements have possibly already been removed.

[0064] The objective of the tooth edge machining of this embodiment and numerous preferred method embodiments is the formation of a chamfer 8 at the location of the former tooth edge 6, as is shown, for example, in the illustration of FIG. 2. For the purpose of an enlarged illustration, FIG. 2 shows only the region of a tooth gap 5 near the base and the region of a tool tooth 14 near the tip.

[0065] A preferred example for producing the chamfer 8 will now be described with reference to FIG. 3a. An axial relative movement moves the workpiece tooth arrangement 13 by Δz above the height level of the lower end face 2b of the workpiece tooth arrangement 3, as seen axially. In addition, the envelope of the tool tooth rolling positions is shifted by an amount in the tangential direction Y that corresponds to a chamfer width w which in this embodiment, for example, is 0.3 mm, due to an additional rotation ΔC of the workpiece relative to the phase position of the synchronized rolling coupling, for example. As a result, a sharp edge 19, which is provided between the end face 12 of the tool 10 and the machining surface 18 formed by the tooth flank surface of the tool tooth arrangement 13 on the tool 10, cuts off material on the end face 2b of the workpiece 2 while executing the rolling movement of the rolling engagement. In this case, the cutting movement is substantially in the plane orthogonal to the rotational axis C. It ends at a distance from the former tooth edge 6 in the size of the chamfer width w. By repeating this process with the tool 10 immersed in an axially deeper manner, but with a reduced shift by ΔY, the next cut in the next rotation only extends to w-ΔY, and so on, as can be seen in FIG. 3a. This thus results in a removal in slices of different cutting depths in the tangential direction and thus also of different extensions in the flank normal direction. At the end of the axial movement when the axial penetration depth is reached at the level of the desired chamfer depth d, the shift is again at zero and in this embodiment of a realization of the transverse movement via an additional rotation ΔC, the phase position of the synchronous rolling coupling is reached again.

[0066] If the shifting movement were only to be effected via linear machine axes, the phase position of the synchronous rolling coupling would be maintained during machining, and the effect of the removal in slices is achieved by a corresponding shift of the envelope via machine axis settings, for example, via the tangential axis Y. It is also conceivable for the radial axis X to act or contribute. In addition, combinations of axis movements X, Y; X, ΔC; Y, ΔC; X, Y, ΔC can be used. An involvement of the radial axis is preferred if a base chamfer is also to be created, as shown in FIG. 2.

[0067] Preferably, and as in this example, the axial movement will take place by way of a continuous feed movement with an adjustable feed rate per workpiece rotation. In the embodiment shown, for example, a workpiece speed of 1000 rpm and a feed rate per workpiece rotation of 0.02 mm is set. For producing the chamfer shown in FIG. 3 with, for example, a chamfer width of approximately 0.3 mm and a chamfer depth d of also approximately 0.3 mm corresponding to a chamfer angle of approximately 45°, 15 workpiece rotations are carried out (for the sake of simplicity, FIG. 3 and the enlarged detail in FIG. 3a only show a smaller number of stages of the removal in steps and in slices).

[0068] For smoothing the surface of the chamfer 8, the edge 19 of the tool tooth arrangement 13 is in this embodiment once again guided along the chamfer 8. For this purpose, the movement direction is reversed in the axial direction and the relationship between the shifting of the envelope and the current axial immersion depth is maintained, but preferably a phase shift by a is preferably provided in the range [90°-270°]. It would also be possible to work with a lower feed rate during the emerging movement than during the immersion movement. A momentary situation of this smoothing retreating movement is shown in FIG. 4.

[0069] FIG. 5 shows again how the envelope 28 is offset from the individual rolling positions 29i in relation to its zero position, which corresponds to the profile of the workpiece tooth flank, due to the shifting movement.

[0070] FIGS. 6a and 6b once again show shifting movements as well as the single-flank method selected in preferred method embodiments (right and left flank are not chamfered simultaneously but one after the other but in this example with the same tool).

[0071] FIG. 7 is a plan view and a side view of a chamfering tool. From the latter, it can be seen that the disk thickness h of the tool tooth arrangement in this embodiment is only 3 mm. The chamfering wheel shown in FIG. 7 has 40 teeth with a module of 2 and an engagement angle of 20°. It goes without saying that the tooth arrangement data, such as the number of teeth or the disk thickness, can also assume other values.

[0072] Due to the tooth arrangement axis of the tool tooth arrangement being aligned parallel to the tooth arrangement axis of the workpiece tooth arrangement, chamfering wheels with a comparatively thin design are also well suited for machining hard-to-reach tooth edges, such as in the situation schematically shown in FIG. 8a, in which a workpiece 2′ has two different external tooth arrangements 3′ and the lower end face of the upper tooth arrangement 3′a only has a small axial distance from the upper end face of the lower tooth arrangement 3′b. In FIG. 8b, the tool is in the form of a tandem tool that carries two tool tooth arrangements. The one tool tooth arrangement 13′a is used for chamfering the workpiece tooth arrangement 3′a and the second tool tooth arrangement 13′b is used for chamfering the other workpiece tooth arrangement 3′b.

[0073] It can also be seen from FIG. 8a, b that the presented method can also be used to chamfer external tooth arrangements similar to the chamfered internal tooth arrangement 3 described with reference to FIG. 1.

[0074] It is also understood that, even though FIG. 1 shows the chamfering method for a straight tooth arrangement, the method can be used to chamfer helical tooth arrangement as well. In this case, the tool tooth arrangement could be designed to match the rolling engagement with parallel axes as helical tooth arrangements to match the helix angle of the workpiece tooth arrangement. Alternatively, narrow, in particular conical, but still straight-toothed tool tooth arrangements can be taken into consideration.

[0075] A chamfering unit 100 shown in FIG. 9 is capable of positioning the tool rotational axis B using three linear axes X, Y, Z, realized via corresponding carriage arrangements 110, 130, 120, relative to the workpiece rotational axis C (C parallel to B). The axis movements X, Y, Z, B, C are NC-controlled via controller 99. For an alternative, simpler design, the carriage 130 could also be omitted.

[0076] The chamfering unit 100 schematically shown in FIG. 9 could be integrated into a gear-cutting machine whose tool-side main spindle carries a tool that produces the workpiece tooth arrangement, such as a skiving wheel, a hob or a gear shaping wheel. Then the chamfering could still be carried out in the same workpiece clamping process as the main machining, or also at another location, transported by an appropriate automation, such as a ring loader, gripper or a double spindle arrangement, from the location of the main machining to the location of the chamfering. However, the chamfering unit can be designed as an independent chamfering machine and the workpieces can be received by a workpiece automation, also from a plurality of gear-cutting machines, which deliver the tooth arrangements already produced for supplementary tooth machining.

[0077] In particular, if the main machining and the supplementary machining are not carried out in the same clamping process of the workpiece, it is provided that the (chamfering) machining unit also has means for centering, such as non-contact centering sensors, in order to determine the in-phase relative rotational position for the synchronous rolling coupling.

[0078] Moreover, the invention is not limited to the embodiments shown in the previous examples. Rather, the individual features of the above description and the following claims may be essential, individually and in combination, for implementing the invention in its different embodiments.