METHOD FOR MACHINING TOOTHINGS, AS WELL AS TOOTHING MACHINE AND CONTROL PROGRAM FOR SAME

Abstract

The invention relates to a method for machining toothings, which method uses a disk-shaped, toothed tool that is rotationally driven about its axis of rotation and has a geometrically defined cutting edge. The tool teeth are produced from a base material, are provided, at least on the tooth flanks, with a coating that improves wear resistance, and have machining surfaces facing an end face of the tool, said machining surfaces being re-ground from time to time when the tool is reconditioned, wherein after at least one regrinding, use of the tool is resumed and continued with regions of the machining surfaces formed along the cutting edges from the base material.

Claims

1. Method for machining toothings, for which a disk-shaped and toothed tool (5) is used, which is driven rotationally about its axis of rotation and has a geometrically defined cutting edge, the tool teeth (4) of which are made of a base material and are provided with a coating that improves wear resistance at least on the tooth flanks, and also have rake surfaces (5, 5′) facing an end face of the tool, which are reground from time to time in the scope of reconditioning the tool, characterized in that the use of the tool is resumed and continued after at least one regrinding with regions of the rake surfaces formed in any case along the cutting edges from the base material.

2. Method according to claim 1, in which the continued use takes place on the same toothing machine (100) as the use before regrinding.

3. Method according to claim 1 or 2, in which a machine control for continued use automatically receives information about the depth of removal during resharpening.

4. Method according to claim 1 in which the continued use is carried out without intermediate measurement of a first toothing machined after resumption.

5. Method according to claim 1 in which the regrinding is carried out on a regrinding station coupled via a tool changer with a toothing machine on which the previous or continued use is carried out.

6. Method according to claim 1 in which the regrinding is carried out in the tool clamping of a toothing machine (100) on which the previous and/or continued use takes place.

7. Method according to claim 6, in which the regrinding tool is fed from a direction (Y) tangential to a radial infeed movement (X1) of the toothing machining.

8. Method according to claim 1 in which the rake surface is reground by performing an especially horizontal grinding stroke movement (H).

9. Method according to claim 6 in which a swivel angle (A1) of the tool axis orientation remains unchanged between use in machining and regrinding.

10. Method according to claim 6 in which the tool has a non-zero head rake angle and a swivel angle (A1) for the tool axis orientation is set to the head rake angle for regrinding.

11. Method according to claim 6 in which, before regrinding, a probing of the tool is carried out with the regrinding tool semi-automatically or automatically.

12. (canceled)

13. (canceled)

14. (canceled)

15. (canceled)

16. (canceled)

17. Method according to claim 6 in which at least one machine axis (Y3) actively moving the regrinding tool is used for the relative positioning of the regrinding tool to the tool to be reground.

18. Method according to claim 6 in which at least one machine axis (X1, Y1, Z1) actively moving the tool to be reground is used for relative positioning between the reground tool and the tool.

19. Method according to claim 6 in which predominantly radially extending grinding grooves are produced on the tool and rotary movements of the tool and regrinding tool are matched to one another to produce predominantly radially extending grinding grooves on the tool.

20. Method according to claim 6 in which the tool to be reground and the grinding region of the regrinding tool overlap in two non-contiguous regions (KB, NKB) when viewed in projection on the tool disk plane during regrinding.

21. Method according to claim 20, in which during regrinding, one end face plane of the tool and the grinding plane of the regrinding tool are brought slightly out of parallelism so that the grinding tool has grinding contact only in one (KB) of the non-contiguous regions.

22. Method according to claim 1 for machining toothing, to which a disk-shaped and toothed tool driven in rotation about its axis of rotation and having a geometrically defined cutting edge is used, the tool teeth of which have rake surfaces facing an end face of the tool, which are reground from time to time, the use of the tool being resumed and continued after regrinding, wherein the method is characterized in that resharpening is carried out already on or before reaching a wear mark width of 1.6 mm for PM-HSS tools, and before or on reaching a wear mark width of 0.08 mm for carbide tools.

23. Control program for a toothing machine which, when executed on the machine controller of the toothing machine, controls the toothing machine to perform a process according to claim 1.

24. Toothing machine (100) with a workpiece spindle (C1) for the rotatably drivable bearing of a workpiece carrying a toothing, a tool spindle (B1) for the rotatably driven bearing of a disk-shaped and toothed tool with a geometrically defined cutting edge and with machine axes (X1, Y1, Z1) for the relative positioning of tool and workpiece as well as a machine control for the control of the toothing machining performed with the tool, characterized in that the machine control has a control program according to claim 23 and/or has movement means (41, 42, 44) which, when actuated, brings a regrinding tool for regrinding the rake surfaces (5) of the tool teeth (4) into grinding engagement with the tool.

25. Toothing machine according to claim 24, in which the moving means have at least one machine axis (Y2, Y3) which can changeably adjust the location or orientation of an axis of rotation of the regrinding tool.

Description

[0050] Further features, details and advantages of the invention can be found in the following description with reference to the accompanying drawings, in which

[0051] FIG. 1 shows a toothing machine with an integrated regrinding arrangement,

[0052] FIG. 2 shows a tool to be reground in the form of a skiving wheel in the step cut,

[0053] FIG. 3 shows schematically a regrinding engagement matching a step cut,

[0054] FIG. 4 shows schematically an engagement suitable for a non-zero head rake angle,

[0055] FIG. 5 shows positioning arrangements and grinding stroke possibilities, still outside of engagement,

[0056] FIG. 6 represents the variant represented in FIG. 5 in engagement,

[0057] FIG. 7 shows an alternative arrangement possibility to FIG. 5,

[0058] FIG. 8 shows another different arrangement possibility,

[0059] FIG. 9 shows a schematic arrangement for machining without tool step cut, and

[0060] FIG. 10 represents an arrangement possibility in a variant of a pick-up solution.

[0061] The tool machine shown in FIG. 1 is a machine 100 designed for a skiving machining with one skiving wheel S. On the workpiece side, the machine 100 has a tool table 80 rotatably driven in the machine bed 90, in which a workpiece to be machined not shown in FIG. 1, for example with an internal toothing to be machined, can be rotatably clamped around the workpiece sided machine axis of rotation C1.

[0062] On the tool side, the machine 100 has a linear machine axis X1 for a positioning movement of the tool radially with respect to the workpiece, an axis Z1 for a movement of the tool along the axial direction of the table axis C1, and an axis Y1 for a tangential relative movement between tool and workpiece. These linear axes X1, Z1 are perpendicular to each other and are realized by a slide arrangement 70, where a linear slide 72 for the X1 movement carries a vertical slide 74 for the Z1 movement. The tool head 78 carrying the tool S, which in this embodiment also carries a CNC drive as direct drive for tool rotation with axis of rotation B1, is movable with a linear slide 76 for the tangential movement Y1. However, the tangential slide 76 is rotatably mounted on the vertical slide 74 with swivel axis A1, so that its slide movement is horizontal only in the setting shown in FIG. 1, and is otherwise inclined relative to the Z1 axis by the adjusted swivel angle A1.

[0063] In addition, the machine 100 has a further movement system with which a regrinding tool N can be brought into regrinding machining engagement with the skiving wheel S clamped in the tool clamping of the tool head 78, wherein the linear axes and axes of rotation on the tool side can also be used for production of the regrinding engagement. In the represented exemplary embodiment, the regrinding tool N, which is in this exemplary embodiment in the form of a cup wheel, is movable in a tangential direction Y orthogonal to the X1-Z1 plane. It can thus be introduced laterally into the machining region with respect to the radial direction X1. This movability in Y-direction is realized by a double slide 41, 42, of which the lower slide 41 is intended for positioning with axis Y3, while the upper slide 42 is intended for the grinding stroke movement. In addition, a regrinding spindle 44, which carries the regrinding tool N and drives rotationally about the axis D1, is pivotally arranged in a plane orthogonal to the Y direction (the swivel axis is marked A2), so that an angle between the axial direction of the axis of rotation D1 and the axis Z1 (C1) can be adjusted in a plane parallel to the X1-Z1 plane.

[0064] Also conceivable are variants in which the Y1 axis (possibly in combination with Z1) of the tool head 78 is used for the grinding stroke movement and, if necessary, axes on the grinding head such as Y2 are then saved. It is also conceivable to have an additional axis X2 of the grinding head parallel to the X1 direction.

[0065] If the skiving wheel S with its coated teeth has now reached a certain wear due to the machining of the workpieces, the rake surfaces of the skiving wheel S are reground.

[0066] This is described in the following for a skiving wheel S, which is ground in step cut (see also FIG. 2) and has a non-zero head rake angle. In this case the regrinding tool N is swiveled to the step cutting angle of the skiving wheel S with swivel axis A2. The swivel axis A1 of the skiving wheel S is swiveled to the head rake angle of the skiving wheel S. In this adjustment, a center line of rake surface 5 to be reground (in indexing method) is horizontal in the 90° position with respect to the radial axis X1, facing the face of the regrinding tool N. In the grinding stroke movement (axis Y2, see also FIGS. 5, 6)), the machining region then moves along the rake surface 5 during the grinding stroke, wherein the orientation of the grinding region of the cup wheel N coincides with the orientation of the rake surface 5, so that the rake surface 5 can be ground off by an intended removal. It is understood that the Z1 axis of the skiving wheel S can be used for the height adjustment of the machining engagement and the infeed, while the XY machine axes are used for positioning. In addition to the rake surfaces 5, when using a tool S as shown in FIG. 2, its side-faces 6 can also be reground.

[0067] Due to the lateral feed of the regrinding tool N with respect to the radial axis X1, competing space requirements on the machine side are avoided. In addition, due to the parallelism of grinding stroke and feed direction of the tracking tool, vibrations during regrinding are largely avoided. When all rake surfaces 5 have been reground in this way, one after the other in indexing machining, the regrinding tool N is retracted and the toothing machining by the skiving wheel S can be resumed and continued.

[0068] The changes in the machine axis adjustments required for further machining due to the changed skiving wheel shape resulting from regrinding (smaller diameter, smaller height) are automatically calculated by the machine control. The machine control has the necessary information for this from the tool layout stored in it and knowledge of the removal carried out during resharpening about the axis positions of the machine axes used for this.

[0069] In alternative embodiments, however, the grinding stroke could also take place in the X1 machine direction (see also FIG. 7), if, for example, regrinding is carried out on the face of the tool which is closest (0° position, e.g. for internal toothings) or furthest (180° position, e.g. for external toothings) to the main machine column (70). In this case it would be preferable to leave the swivel axis adjustment of the tool head 78 adjusted to the machining axis cross angle. For example, if the workpiece machining is that of internal toothings, where work is done in the zero° position, in the 180° position, you could adjust to twice the opposite axis cross angle to set the rake surface 5 horizontally. However, it is also conceivable not to change the axis cross angle in this way or to leave it in the position for machining. It could then be provided that the grinding head (44) is provided with a further swivel axis; it is also conceivable to use strongly conical lateral surfaces on a grinding disk not configured as a cup wheel. In the case without a head rake angle, radially horizontally running rake surfaces would then have to be reground; if a head rake angle is available, the regrinding contact could be maintained, for example, by an additional movement of the machine axis Z1. For this purpose, when using a cup wheel, axis A2 (FIG. 1) could be swiveled to the head rake angle; in this case, the swivel axis A2 of the regrinding head adjusts the same orientation of the surface to be ground in the machining engagement.

[0070] In this variant, it would be preferable to perform the regrinding on the face of tool S that is closest to the main machine column (slide arrangement 70) in order to avoid space competition with the workpiece table 80. This is particularly important when machining internal toothings, since in this case it is not necessary to swivel in via the swivel axis A1 of the tool head 78. In the case of an external toothing, regrinding would have to be performed in the 180° position if you do not want to swivel in via the swivel axis A1. In the 180° position, more favorable conditions of the available installation space are often present. Particularly if the skiving wheel S does not have a head rake angle, it can also be considered to draw the rotational movement of the regrinding tool N via the spindle carrying the workpieces during machining (in a constellation similar to FIG. 1 the machine table 80) and to perform the grinding stroke via the radial axis X1. This variant is also conceivable with a head angle unequal to zero by drawing on the radial axis X1 for the grinding stroke and by drawing on a coordinated offset of the engagement region (relative to the 0° position) with superimposed movements Y1 and Z1.

[0071] Via the existing machine axes of the arrangement represented in FIG. 1, on the one hand for the skiving wheel S and on the other hand for the resharpening tool N, superimposed variants can also be designed in which the grinding stroke is carried out in a diagonal direction (i.e. with X and Y directional components). In this case, the swivel angle (A1 axis) of the skiving wheel S is preferably adjusted to match the desired head rake angle in dependence on the grinding stroke direction and the angle adjusted for the regrinding tool N.

[0072] Depending on the dimensions of the regrinding tool N used, it is also possible to dispense with the realization of a grinding stroke completely, that is, if a rake surface 5 is already completely covered. The regrinding would then be a plunge-cut grinding.

[0073] For exact determination of the relative location between the skiving wheel S and the regrinding tool N, it is possible to touch the skiving wheel S with the regrinding tool N in the axial direction as well as in the circumferential direction, in order to establish the exact relative height position as well as relative angular location of the teeth of the tool S to the grinding tool N. This is particularly indicated after changing the machining tool S and/or regrinding tool N. This is because swiveling in of the grinding head 78 makes it possible to leave the tool S at the machining axis cross angle. However, the angular location of the tool teeth 4 may already be known due to the preceding machining and monitoring of machine axis B1. For contact detection, noise detection can be considered, as well as monitoring of the machine axes, for example, by means of a change in torque on the tool or workpiece spindle (B1/C1). Visual recognition methods such as sparking could also be used.

[0074] This type of probing is also preferred if the regrinding tool N itself has been subjected to a pulling procedure. It can run fully automatically, i.e. the machine 100 carries out the probing independently, or under rough prepositioning by an operator semi-automatically or alternatively software-guided, if the operator controls the probing via the machine control panel. A purely manual variant by probing through axis movements using hand control is also conceivable.

[0075] If, for example, skiving wheels are worked with, which do not have a step cut, a continuous method for regrinding can be used in addition to the intermittent method. If realized, for example, with a cup wheel as the regrinding tool, the skiving wheel would be swiveled in to an angle (A1) of 0°, i.e. adjusted for substantially horizontal rake surfaces or left in such an already adjusted adjustment. A continuous rotation of the skiving wheel is realized via axis B1. When using a cup wheel, a preferred layout (see FIG. 9) results in an overlap region in two non-contiguous regions of the skiving wheel. Here, it is preferred that a minimal deviation of parallelism between the grinding surfaces of the regrinding tool and the grinding surfaces of the skiving wheel ensures that only in one of the non-contiguous regions (KB) a grinding machining takes place, while in the other region (NKB) there is no contact due to this slight deviation (for example, the regrinding tool is ground in the order of a few hundredths of a degree, e.g. 0.01 to 0.03° deviating from zero, so that in the other overlap region NKB there is a lift-off between the regrinding tool and the skiving wheel and thus no contact occurs anymore). This small deviation in the parallelism of the two planes could also be achieved via the swivel axis (A1) of the skiving wheel. In this case it is again possible to effect the rotatory movement of the regrinding tool via the C1 workpiece spindle. Otherwise, the non-parallelism can also be adjusted via the swivel axis A2 of the regrinding tool.

[0076] If it is ensured in this way that regrinding is carried out in only one (KB) of the two overlap regions, substantially radial grinding grooves can be produced, which are considered to be advantageous.

[0077] In a concrete example (here: head rake angle zero) the cutting speed of the cup wheel could be 30 m/s, and at a rotational speed of 1/s revolutions of the skiving wheel with, for example, a skiving wheel diameter of 200 mm with a resulting skiving wheel circumferential speed of 0.63 m/s it could be achieved that the grinding grooves deviate only a few degrees from the radial direction (skiving wheel system with skiving wheel center), in the concrete calculation example even only by 1.2°. As already mentioned above, a swivel angle adjustment in the range of +−0.01 to 0.03° can be sufficient, depending on the diameter of the cup wheel. The grinding direction should preferably point towards the center of the reground tool.

[0078] If head rake angles of non-zero degrees are to be produced, the rake surfaces could also be ground in the form of calottes, but with a slightly curved surface in the radial direction. As an alternative to the above-mentioned matching, an additional swivel axis of the tool head 78, not shown in FIG. 1, could also be achieved to generate head rake angles unequal to zero degrees.

[0079] In principle, a comparatively flat cup could also be used as these cup wheels, or even a moon disk. In comparison to a full cylindrical disk, only a narrow region is used with a cup wheel, which is then correspondingly easier and more accurate to dress, which brings advantages in dressing the regrinding tool.

[0080] In principle, the generation of grinding grooves in a predominantly tangential direction is also conceivable, although this is less preferred to the variant with grinding grooves running predominantly in a radial direction. However, such a variant also allows regrinding with the lateral surfaces of grinding disks (the skiving wheel has no step cut for this purpose) over a plurality of teeth according to the continuous method. In this case, the A1 swivel axis for the skiving wheel can be adjusted to a corresponding angle to achieve a rake angle deviating from zero, the regrinding wheel is swiveled in to an angle of 90° (but not with the A2 axis, but with an additional swivel axis with which the axis of rotation D1 of the regrinding tool is swiveled in horizontally and parallel to the Y2 direction. A head rake angle unequal to zero can then be set via this axis or alternatively via the A1 axis), the Z1 axis is used for height adjustment and infeed, and the available linear axes orthogonal to the Z1 direction for mutual positioning.

[0081] FIG. 2 shows the shape of a skiving wheel S which could be used on the machine 100 represented in FIG. 1. The design of the tool teeth 4 formed in step cut can be clearly recognized with the rake surfaces 5 formed in step cut. The tool S shown in FIG. 2 also has a non-zero head rake angle 5, the rake surfaces are also inclined with respect to the radial direction. Due to the available machine axes shown in FIG. 1, for example, it is possible to adjust the orientation of the rake surfaces 5 to match the grinding region of a cup-shaped grinding disk, for example.

[0082] FIG. 3 clarifies the engagement situation when regrinding a cutting wheel S3 with a regrinding tool N3 in the form of a cup-shaped grinding wheel. It can be recognized that the axes of rotation of cutting wheel S3 and regrinding tool N3 are swiveled in on each other to match the step cut angle α, once for a right-handed and once for a left-handed cutting layout.

[0083] FIG. 4 schematically shows a variant in which a cutting wheel S4 not provided with step cut is reground by a rotating cylindrical grinding disk N4. Here you can see how the relative angular location of the respective axes of rotation is set to match a head rake angle of the cutting wheel S4. A grinding stroke movement is indicated by the arrow on both sides. However, it could also be considered, for example, to make a compensation movement in the direction of the cutting wheel axis and to couple this with the grinding stroke. Cylindrical regrinding tools such as N4 could also be used for a step cut, although not in the regrinding position shown in FIG. 4, but in a position rotated at 90° to the cutting wheel axis (which is an interim position between the 0° position close to the skiving head and the 180° position far from the skiving head), possibly with offset.

[0084] The schematic representation in FIG. 5 shows a positioning and grinding stroke variant of the machine shown in FIG. 1 or other machines with corresponding movement axes. Here a grinding stroke movement perpendicular to the radial infeed axis X1 of the toothing machine is provided. FIG. 6 then shows how the cup-shaped grinding disk N5 covers almost the entire rake surface 5′. Within the scope of the grinding stroke indicated by the double arrow, the entire rake surface 5′ is reground. Furthermore, the direction of rotation of the regrinding tool N5 is shown. It can be recognized that in the grinding engagement region the rotary grinding movement runs from its direction predominantly radially (with respect to the axis of rotation of the cutting wheel) to the rake surface 5′, with a grinding direction towards the center of the tool.

[0085] FIGS. 7 (radial and in the direction of axis X1) and 8 (diagonal) show alternative grinding stroke directions or positionings of regrinding tool to cutting wheel. A rake face 5′ is (still) re-ground, which is in the region of a parallel to the stroke direction H passing through the center of the cutting wheel. Again, the main component of the rotatory grinding movement is 5′ parallel to the radial direction of the rake surface; the grinding direction is according to the preferred shaping towards the center of the tool.

[0086] Even in cases where the regrinding tool is clamped onto the machine table (C1), a grinding stroke in different directions, uniaxial (e.g. X1 or Y1) or also superimposed (X1 and Y1), for example diagonally, is conceivable.

[0087] FIG. 9 shows a situation in which the cutting wheel S9 has no step cut. Here, regrinding is carried out in a continuous method, in the position represented in FIG. 9, with cutting wheel S9 and a cup-shaped regrinding tool N9. You can see two regions, KB and NKB, where there is an overlap due to this positioning. In the exemplary embodiment shown, however, not both regions KB and NKB are reground, but a grinding contact only exists in region KB, due to a slight inclination of the wheel planes of the cutting wheel S9 and the cup wheel N9. The respective rotational speeds are coordinated with each other in such a way that in the contact area KB grinding grooves are generated, which essentially, in any case with a predominant directional component in relation to the axis of rotation of the tool, run radially on the rake surfaces. Here too, the grinding direction is directed towards the center of the tool.

[0088] FIG. 10 schematically illustrates a pick-up solution. A skiving wheel S10 is represented, which cuts a workpiece WS with an internal toothing. The workpiece is clamped on a pick-up spindle P1. A regrinding tool N10 is clamped on another pick-up spindle P2 and is used to regrind the cutting wheel W10. This is done by positioning along the Y axis.

[0089] As can be seen from the above, the invention is not limited to the realization as specifically represented in the examples above. Rather, the individual features of the above description as well as the following claims, individually and in combination, can be essential for the realization of the invention in its different embodiments.