EP4247580A1

EP4247580A1 - Method for machining a toothing and tool designed therefor, and control program and tooth honing machine therefor

Info

Publication number: EP4247580A1
Application number: EP21815961.4A
Authority: EP
Inventors: Silvan RIEDERER; Johannes BROGNI
Original assignee: Gleason Switzerland AG
Current assignee: Gleason Switzerland AG
Priority date: 2020-11-20
Filing date: 2021-11-16
Publication date: 2023-09-27
Also published as: JP2024500629A; DE102020007110A1; WO2022106420A1

Abstract

The invention relates to a method for machining a toothing (2) on a workpiece, in which method the workpiece toothing is brought into material-removing machining engagement with a toothed tool (10; 10'), particularly in the form of an internally toothed honing ring, rotationally driven about its toothing rotational axis (CIO) which is at a non-zero axis crossing angle to the workpiece toothing rotational axis, the workpiece toothing being rotationally driven about its toothing axis (C2) and an engagement region being formed, and abrasive material removal with geometrically undefined cutting edge thus being carried out. The extent and/or axial position of the engagement region changes in accordance with the rotational position of the tool. The invention also relates to a honing tool for carrying out the method, to a control program for carrying out the method and to a tooth honing machine.

Description

PROCEDURE FOR MACHINING A GEAR AND THE TOOL DESIGNED FOR IT, AS WELL AS THE CONTROL PROGRAM AND GEAR HONING MACHINE

THEREFORE

The invention relates to a method for machining gearing on a workpiece, in which the workpiece gearing is driven in rotation about its gearing axis, forming an engagement area in material-removing machining engagement with a toothed gearing rotary axis, which is at a non-zero cross-axis angle to the workpiece gearing axis of rotation, in particular in the form of an internally toothed honing ring, is brought under abrasive material removal with a geometrically undefined cutting edge.

Such methods, also known as gear honing, are of course well known to those skilled in the art; For example, Figure 17.3-1 on page 592 of the textbook "Innovative Gear Manufacturing", Thomas Bausch, third edition, shows the intervention of a tool in the form of an internally toothed honing ring for hard fine machining of a gear-shaped one workpiece. The width of the internal toothing of the honing ring is dimensioned sufficiently large to still cover the full width of the workpiece toothing despite the set cross axis angle. Accordingly, the gear honing can be carried out in a pure plunge honing, i.e. it can only be subjected to a radial feed without changing the axial relative position. In a variant of the so-called longitudinal honing, which is also known, an oscillating axial movement is superimposed on the radial feed movement.

Compared to other hard fine machining processes for gears that have already been produced during soft machining and then hardened, such as profile grinding or generating grinding with a grinding worm, gear honing usually offers a higher surface quality that can be achieved. Gear honing is therefore used as an alternative to grinding hard fine machining using profile or grinding worms, or as an additional final machining step.

Since the machining engagement between the honing tool and gearing is usually carried out at comparatively high speeds and usually several workpiece teeth are in mesh with the tool at the same time, gear honing is a comparatively quick process in terms of machining time.

The invention is based on the object of further developing a method of the type mentioned at the outset in a way that combines a satisfactory surface quality of the tooth flanks with a satisfactorily small deviation from the desired target geometry.

This object is achieved by the invention from a procedural point of view by a development of the method of the type mentioned at the outset, which is essentially characterized in that the extension and/or axial position of the engagement area changes depending on the rotational position of the tool.

Due to the change in the engagement area according to the invention as a function of the tool rotational position, a high-frequency change in the load conditions occurring in a predetermined machined area of the tool toothing is achieved at the usual high speeds. Surprisingly, it turned out that this influencing of the forces occurring in the gear honing process leads to reasonable machining qualities in terms of target geometry and surface quality.

In a preferred embodiment, it is provided that the dependency on the rotational position is brought about by a deviation, incorporated into the tool, from a homogeneous expansion of its toothing. In other words, there is a deviation of the Tool gearing of a particularly axial and/or radial uniform design over the dimensioning of the tool. The change is therefore not only linked to the tool rotation, but is mechanically positively coupled to it via the tool design. The change can be brought about particularly advantageously via the deviation from the homogeneous expansion of the tool teeth, which homogeneous expansion corresponds to the usual regular extent of the tool teeth over the full width of the toothing tool, and in particular does not require any additional machine axis movements. For example, a conventionally manufactured and pre-profiled honing stone could be machined to remove material by removing areas of the toothing introduced into it, or at least modifying it in such a way that these areas no longer represent working areas of the honing stone. For example, the toothing introduced could be turned diagonally laterally, so that the effective width of the tool toothing is reduced, or other empty areas are created in the toothing introduced. For example, the tooth height can also change, for example via an eccentric design, so that an at least partially continuous change in meshing takes place via the different tooth heights when the workpiece is rotated.

In a preferred embodiment, the change includes an axial displacement of the engagement area. For example, the engagement area shifts axially as the tool rotates continuously. In this context, it is particularly preferred that this displacement movement is continuous. The position of the initial engagement area, which is restored at least after a full rotation of the tool, is then effected by a displacement movement, which returns in a reciprocal manner after a reversal point has been reached. The displacement motion can be, for example, but not limited to, a sinusoidal motion. Alternatively or additionally, the change in the extent can include a radial change in the engagement area, for example via the tooth height modification of the honing tool caused by an eccentric design, for example.

In a particularly preferred embodiment, the axial extent of the toothing of the tool is less than the axial extent of the envelope curve of the axial extents superimposed over a full revolution of the tool. This means that the effective width of the tool teeth at an azimuthal point also determines the axial extent of the current engagement area, which is, however, smaller in axial extent than the entire (enveloping) engagement area resulting from a full tool rotation. The toothing, which is narrower than the width of a honing ring, for example, leads, viewed in the passage through the machining zone in a tool rotation, a pendulum movement, which causes a change in the intervention area on a very short time scale. In this context, it is provided that the tool speed during machining is greater than 600 rpm, preferably greater than 900 rpm, in particular greater than 1200 rpm, but certainly also higher than 1500 rpm.

The displacement movement could also be overlaid with an additional reciprocal relative movement of tool and workpiece that is preferably at least twice as low in frequency, for example as in longitudinal honing.

In a particularly preferred embodiment, the axial extent of the tool toothing is less than the quotient of the width of the workpiece toothing and the cosine of the axis crossing angle, in particular by a factor of at least 1.2, preferably at least 1.4, in particular at least 1.6 less. This reduces the size of the area affected by meshing on the forces in the gear honing process (fewer active teeth are in the honing process at the same time) compared to conventional meshing. This is particularly useful for helical gears that tend to have a larger helix angle and is particularly independent of the size ratio between the honing tool and the workpiece, which otherwise influences the degree of wrap. To put it simply, the abrasive removal of material on the workpiece teeth that are still engaged is less influenced by the influences of the workpiece teeth that are no longer engaged according to the invention. This reduces the process forces and thus also reduces the risk of a honing stone breakage. However, an expected lower service life of the honing stone is at least partially compensated by the lower process forces compared to the conventional honing process and thus the effects that increase the service life.

The above-mentioned aspects are also disclosed by the invention as an independently advantageous teaching independently of a change in the extent and/or the axial position of the engagement area as a function of the tool's rotational position. The invention thus also relates to a method according to the preamble of claim 1, which is essentially characterized in that the effectively effective toothing width of the honing tool is less than that of its envelope over a full tool rotation, and / or is less than the quotient of the width of the Workpiece toothing and cosine of the crossed axis angle.

In one possible design, the invention provides that the ratio of the effective width of the tool toothing to the module of the machined toothing is less than 16, preferably less than 12, in particular less than 8. In a further embodiment, it is additionally and/or alternatively considered to use the interaction in particular of a helical toothing and the axis cross angle to reduce the wrap by the toothing of the honing stone having azimuthal gaps. This is particularly effective in the case of larger axis crossing angles.

In another preferred embodiment, it is provided that the axial extension of the envelope curve is greater than the quotient of the width of the workpiece toothing and the cosine of the axis crossing angle, in particular by a factor of at least 1.01, preferably at least 1.05, in particular at least 1.10 . As a result, the entire toothing width can be machined in a relative positioning of the tool to the workpiece. It goes without saying, however, that despite this design, additional machine axis movements can be carried out, either with regard to specially directed corrections, or, for example, an additional superimposition of a machine axis movement as in conventional longitudinal honing.

In a further preferred embodiment, it is provided that the working area of the tool, viewed axially, includes the front edge(s) of the tool toothing. This and/or the reduction in wrap explained above can also advantageously contribute to reducing a cumulative pitch error of the toothing subjected to the method. On the one hand, this ensures a larger range of applications for the method, including gearings with undesirably high cumulative pitch errors, without the method or method preparation becoming more complex and/or more laborious. In particular, it is not absolutely necessary to have to determine the cumulative pitch error on the gearing to be machined, for example as disclosed in DE 4321448 A1, or to eliminate the cumulative pitch error "with the opposite sign" of the coupling of the rotary axes of the tool and workpiece as a disturbance variable, which is particularly determined in this way , such as is described in DE 4317306. The electronic coupling of tool and workpiece rotation can thus take place as with conventional gear honing in order to ensure the imaging process, i.e. that, for example, the internal gearing of the honing ring, taking into account the rotary movement between tool and workpiece, corresponds exactly to the counter-contour of the workpiece to be machined according to NC-controlled electronic coupling Workpiece gear profile corresponds.

In a preferred embodiment, the axial extent of the engagement area in a snapshot is less than the engagement area corresponding to an envelope curve over a full tool revolution or the total axial extent of the engagement area on a time scale defined by the time of the tool revolution. In a further preferred embodiment, it is provided that the axial extension of the envelope curve is greater than the quotient of the width of the workpiece teeth and the cosine of the axis crossing angle, in particular by a factor of at least 1.01, preferably at least 1.05, in particular at least 1.10 . This configuration therefore combines the advantages of conventional longitudinal honing with the advantages achieved according to the invention.

In a further embodiment in this regard, it is preferably provided that the frequency of a reciprocal second changing movement due to the second change and the frequency of the changing movement due to the change are at least a factor of 2, preferably at least 4, in particular at least 8 apart.

In a further preferred embodiment it is provided that the number of teeth of the toothing of the workpiece and the tool have a non-divisible ratio. This symmetrizes the overall machining process, since individual teeth of the workpiece gearing are always being machined by other teeth on the tool.

In a further preferred embodiment, it is provided that during machining synchronous and counter-rotation (in analogy to milling with a geometrically defined cutting edge), i.e. the relationship between cutting caused by the axis crossing angle and the (axial) displacement movement corresponding to a fast feed, without changing the direction of rotation alone alternate tool rotation.

In terms of device technology, the invention provides a honing tool for executing a method according to one of the aforementioned aspects, and control software for executing a method according to one of the aforementioned aspects, as well as a gear honing machine with such a honing tool and/or such a control.

The machine axes of the gear honing machine can be arranged in the manner known to those skilled in the art of conventional gear honing machines. A honing tool, particularly preferably an internally toothed honing ring with the properties according to one of the aspects described above, can be arranged in the tool holder. The machine control has control commands that control the gear honing machine to carry out a method according to one of the aspects mentioned above.

Further features, details and advantages result from the following description of exemplary embodiments with reference to the accompanying figures, of which 1A shows an internally toothed honing ring and an externally toothed workpiece in a machining engagement during a first day of rotation of the honing ring.

1B shows the honing ring and the workpiece from FIG. 1A in the machining engagement in a different rotation position of the honing ring,

Fig. 1C shows the honing ring and the workpiece of Fig. 1A in yet another day of rotation of the honing ring,

Fig. 2 shows the arrangement of a toothed working area in the honing ring in an unrolled representation,

Fig. 3 shows another honing ring with tooth height modification, and

FIG. 4 shows an enlarged portion of FIG. 3. FIG.

As can be seen from the perspective view of FIG. 1A, a work wheel, which is provided with external teeth 2, is gear-honed by a honing ring 10. However, the toothed working area 4 of the honing ring 10 (see FIG. 2) does not extend over the full axial width 102 of the honing ring, but only over a smaller width 42. The arrangement of the toothed working area 4 in the azimuthal direction is not constant, but changes approximately in the manner of a sinusoidal shape depending on the rotational position of the honing ring 10. The toothed machining area does not extend into the remaining areas 6 of the honing ring 10. In terms of manufacturing technology, this could be realized, for example, by first manufacturing and profiling the honing ring 10 in a conventional manner over the full width 102 and then turning the toothing of the areas 6 by lateral diagonal turning in a turning operation.

In FIG. 1A, the rotational position of the honing ring is that in which the toothed working area 4 is to the right as viewed in FIG. 1A, as indicated by the A in FIG. Accordingly, only the workpiece teeth located near the right-hand side of the workpiece in Fig. 1A are in the machining engagement, which can thus proceed undisturbed by process forces, which would otherwise take place through machining engagement of the workpiece teeth to the left of it, if the working area-free area 6 of the honing ring 10 with the toothing were also there 4 provided.

In FIG. 1B, on the other hand, the rotational position of the honing ring 10 is such that the toothed working area 4 is arranged in the left-hand end area of the honing ring 10, as is also indicated by the reference symbol B in FIG. At this moment, only the workpiece teeth facing the honing ring are engaged near the left workpiece front side. Accordingly, within a workpiece rotation, the engagement area oscillates essentially between the engagement areas illustrated in FIGS. 1A and 1B, the axial position of the engagement area thus changes on a time scale that currently corresponds to one tool revolution. Due to the toothing-free areas 6 on the honing ring 10, toothing areas of the workpiece that face the honing ring are not in machining engagement during the current machining operation.

In the illustration of FIG. 1C, the rotational position is such that the working area 4 is arranged approximately in the central area of the honing ring 10.

The sinusoidal shape of the toothed working area 4 on the inside of the honing ring is only an exemplary embodiment, a grid of the toothed area 4 could also be designed differently, for example sinusoidal with more than just one oscillation per circumference, it could be designed with multiple threads, for example the The toothed working area 4 and the non-working area 6 alternate in stripe patterns, e.g. in stripes (4-6-4-6) alternating at an angle of e.g. 10° or more to the plane orthogonal to the tool axis of rotation, which extend diagonally across the inside of the honing ring .

In Fig. 3 another embodiment of the invention is shown. In the case of the honing ring 10' used here, the height h of the teeth 4 changes over the circumference of the honing wheel. This is achieved, for example, by an eccentric design when manufacturing the honing wheel toothing 4 . It can be seen in the representation of Fig. 3 that in the area 4 'the toothing has a tooth height h (Fig. 4), which extends over a range of slightly more than 180 ° with this (full) tooth height h, to then for example in the 4" range to be continuously reduced down to a 4'" range in which no more gearing needs to be formed at all. It goes without saying that the type of variation is not limited to the example shown in FIG. 3; for example, the tooth height could also continuously decrease and increase again over the entire azimuthal range. In abrasive engagement with rotation of the honing ring 10', starting from the area 4', the tooth height and, accordingly, the extension (radial) of the engagement area are in a continuous or stepped manner.

Also with this design, which could also be combined with the axial modification of the exemplary embodiment in FIGS. 1 and 2, the machining forces change in quick succession, coupled to the speed of the honing ring 10'. Since the tooth height increases continuously or in stages, the full torque of the drive spindle also acts on the respective sub-segment for the current tooth height. In this way, a pitch error in the pre-toothing can be effectively counteracted. In one embodiment of the method, one can also think of using two honing rings, in particular clamped in a common tool holder, with one or both of the honing rings being modified according to the invention. A modified honing ring could be used for initial honing of a workpiece with the aim of bringing a cumulative pitch error below a specified threshold, for example. Further processing to the final infeed depth could then be carried out with a (also unmodified) honing ring with homogeneous teeth.

However, the toothing 4, 4' can also already be matched to the final geometry of the workpiece toothing, so that the full honing can be carried out with a single honing ring 10, 10'.

The invention is therefore not limited to the exemplary embodiments illustrated in the above description with reference to the figures or without reference to figures; rather, the individual features of the following claims and the above description can be essential individually and in combination for the implementation of the invention in its various embodiments be.

Claims

EXPECTATIONS

1 . Method for machining gearing (2) on a workpiece, in which the workpiece gearing is driven in rotation about its gearing axis (C2) while forming an engagement area in material-removing machining engagement with a gearing gearing axis of rotation (C10 ) rotationally driven tool (10; 10'), in particular in the form of an internally toothed honing ring, is brought under abrasive material removal with a geometrically undefined cutting edge, characterized in that the extent and/or axial position of the engagement area changes depending on the rotational position of the tool.

2. The method as claimed in claim 1, in which the dependency on the rotational position is brought about by a deviation, incorporated into the tool, from an in particular axial and/or radial uniform design via the dimensioning of the tool (4).

3. The method as claimed in claim 1 or 2, in which the change comprises an axial displacement of the engagement region and/or the change in expansion comprises the radial expansion of the engagement region.

4. The method according to claim 3, wherein the displacement movement/radial expansion change is continuous.

5. The method according to any one of the preceding claims, in which the axial extent (42) of the tool teeth (4) is less than the axial extent (102) of the envelope curve of the superimposed axial extents over a full revolution of the tool.

6. The method according to any one of the preceding claims, in which the axial extent (42) of the tool toothing is less than the quotient of the width of the workpiece toothing and the cosine of the axis crossing angle, in particular by a factor of at least 1.2, preferably at least 1.4, in particular at least 1.6 lower.

7. The method according to claim 5 or 6, in which the axial extent of the envelope curve is greater than the quotient of the width (42) of the workpiece toothing and the cosine of the axis crossing angle, in particular by a factor of at least 1.01, preferably at least 1.05, in particular at least 1.10 greater.

8. The method as claimed in one of the preceding claims, in which the working area of the tool also includes the axially viewed end edge(s) (44) of the tool toothing.

9. The method according to any one of the preceding claims, wherein the axial extension of the engagement area in a snapshot is less than the engagement area corresponding to an envelope curve over a full tool rotation.

10. The method as claimed in one of the preceding claims, in which the change in the engagement area is superimposed on a second change which is brought about by an axial, in particular reciprocal, relative movement of the tool and the workpiece.

11. The method as claimed in claim 10, in which the frequency of a reciprocal second changing movement due to the second change and the frequency of the changing movement due to the change are at least a factor of 2, preferably at least 4, in particular at least 8 apart.

12. The method according to any one of the preceding claims, wherein the number of teeth of the toothing of the workpiece and tool have a non-divisible ratio to each other.

13. The method according to any one of claims 1 to 12, in which during machining alternating and counter-rotation without changing the direction of rotation solely by the tool rotation.

14. Honing tool, in particular internally toothed honing ring, for carrying out a method according to one of the preceding claims.

15. Honing tool, in particular as an internally toothed honing ring according to claim 14, in which the toothing changes in comparison to two of its azimuthally spaced by one or multiple pitch rotational positions, in particular with regard to axial extent, axial position and/or tooth height of the toothing.

16. A control program which, when executed on a controller of a gear honing machine, controls the machine to carry out a method according to any one of claims 1 to 13.

17. Gear honing machine, with a rotationally drivable tool holder for receiving a honing tool, a rotationally drivable workpiece holder for receiving a workpiece, a machine axis for creating the axis crossing angle between the axes of rotation, and a controller that has a control program according to claim 16 and/or a honing tool according to claim 14 or 15.