EP2498932B1 - Rolling tool, device for and method of manufacturing convex toothing and gear - Google Patents

Description

The invention relates to a rolling tool for producing a spherical toothing on a gear by transverse rollers, in particular for at least partially compressing the teeth of the gear, with a tool body having radially outwardly projecting tool teeth for meshing engagement in the toothing of the gear to be rolled, wherein the tool teeth in the area of the tooth flanks are executed in the axial direction at least partially hollow ball.

For running gears, it is customary, in order to achieve good running properties, to install toothing modifications in the form of arcuate crowns over the tooth width. In general, it is known that disadvantageous contact patterns, for example edge beams, that is, that the contact region of the flanks only occurs in the edge region of the toothing, which can lead to locally excessive pressure at the contact regions, can be avoided by means of crowned teeth. Furthermore, edge beams cause unfavorable noise behavior of the teeth. An additional advantage of crowned gears is that parallelism errors of the shafts on which the wheels are mounted can be compensated.

Breitenballigkeiten can be applied for example in the course of hard fine machining of the teeth, such as by honing or grinding. Can be dispensed with due to lower quality requirements of the teeth on a hard fine machining, it would be advantageous to produce a width crowning in the course of the preparation of the teeth before the heat treatment.

From the DE 1 652 654 A a method for crowning the toothing of gears is known, according to which the axis of the workpiece with respect to the rolling tool on the one hand performs a rotational movement about the rolling axis and on the other hand a wobbling movement of the rolling axis along the path of a cone whose tip is in the rolling axis, said Circulating speed of the workpiece to the rolling axis and the speed of the additional wobbling differ. The workpiece is clamped to carry out the process between two grain tips, which are eccentric with respect to the rolling axis on the shells of two cones, the top of which lies in the rolling axis. After completion of the main deformation process, the pivotally mounted rolling head can be swung out with the value of the desired crown in one or more directions from its zero position on the rolling axis. It is thus possible a radial crowning of the toothing or a longitudinal crowning, that is, axial crowning, the teeth to produce. The disadvantage of this is that an additional wobbling motion is performed, whereby precision gears are difficult or impossible to produce.

From the DE 2 060 579 A is a gear-like rolling tool for chipless fine machining of the toothed tooth flanks of gears with internal or external teeth, in particular of front or bevel gears, known by forming by means of a surface pressure between the tooth flanks of the tool and the workpiece causing contact pressure. The rolling tool itself has a crowned toothing in order to create a relatively small contact zone in order to achieve the necessary surface pressure with a small external contact force. The production of a width crowning on a gear is not described therein.

From the DE 32 19 674 A1 a ratchet-shaped tool for cold rolling a crowning gear is known, with a tool carrier and a tool insert mounted thereon. The latter has a toothing produced by linear grinding and arching of the tool insert, the tooth shape of which is complementary to the tooth form of the crowning toothing. The preparation of the tool insert can be done in such a way that it generates on a flat, flat plate-shaped insert blank with flat major surfaces by linear grinding a toothing with straight teeth and then attached to the rack so that the desired for working with the tool , Complementary to a crowned tooth shape of the teeth results. The disadvantage of this is that the tool in the continuous Production process of a gear production is only conditionally applicable and that on the one hand it is difficult to obtain a toothing, which has low tolerances by the necessary bends in the tool, on the other hand, the tool insert itself suffers from the constant bending stress, even if the material has elastic properties.

The WO 2008/116243 A1 , which forms the basis for the preamble of claim 1, describes a method for machining a toothing on an outer circumference or an inner circumference of a workpiece made of pressed and sintered powder metal, with a rolling carried out at the toothing rolling with two rotatable shaping rollers, one in the toothing having the workpiece engaging toothed form, wherein the two Formwalzräder are mutually at least approximately constant center distance between their Formwalzradachsen rotatably arranged in a common support frame. Next describes the WO 2008/116243 A1 a device for carrying out the method.

The JP 2008-049384 A describes a method of forming a gear with teeth having a crown.

From the DE 19 66 067 A1 a device for non-cutting machining of gears by rolling on a gear-like or rack-like tool is known, wherein the tool relative to the workpiece performs a longitudinal feed, the direction lies in a plane which is parallel to the two rolling circles of tool and workpiece tangent through the contact point of the rolling circles extending plane, wherein the occurring smallest axial distance between the tool and the workpiece is dimensioned so that a tool and workpiece radially directed pressure component occurs, whereby a relatively small force is spent for the drive of the feed, while the radial force in is essentially absorbed by support elements for the tool and workpiece.

It is an object of the invention to provide a way with which a breitballige gearing can be made on a gear.

According to the invention this is achieved by the rolling tool mentioned above, in which a plurality of hollow-balled areas are arranged one behind the other on the tooth flanks in the axial direction, as well as by the method in which the compaction is carried out with rolling tools according to the invention.

Due to the hohlballige execution of the tooth flanks of the tool teeth, that is, by their concave inwardly curved surfaces, it is possible to attach the Breitenballigkeit to the gear to be produced in the course of the compression process of sintered gears by cross rolling, so that reaches a tact time neutral machining for the production of Breitenballigkeit becomes. There are arbitrary waveforms of the crown can be represented, so for example circular arc shapes, segmented shapes of circular arcs and lines, etc. It is also advantageous that the entire tooth, that is, the tooth root, the tooth flank and the tooth head is rolled, so that a consistent surface finish the finished gear can be achieved. Thus, the formation of the width crowning in the course of so-called hard fine machining or by a separate operation can be omitted. So it can be so-called "net shape" gears without post-processing with good running properties are possible.

Due to this multitracking of the rolling tool, i. the several hollow-balled areas one behind the other, a simultaneous processing of multiple gears is made possible. On the other hand, it is thus possible to carry out different processing steps of the processing of the toothing with only one rolling tool in a single gear.

In general, the advantage is achieved that relatively easy arbitrary waveforms can be generated by the rollers. For example, the shape of the crown can also fulfill polynomial functions in addition to the forms mentioned above. It is thus possible, for example, to perform the crowning progressively, that is to say that the curvature to the edge of the toothing, that is to say to the end faces of the toothed wheels, is increased. This has the particular advantage that at low load already almost the entire gear width has contact with the mating gear. If the load is subsequently increased, the progressive shape contributes insignificantly to the increase in the contact surface, but very efficiently prevents the edge of the toothed wheel from becoming the contact surface, thus creating a so-called edge support would. Since one edge is a strong non-linearity, the avoidance of edge beams causes a favorable noise behavior of the gear.

For explanation, it should be noted that the term Breitenballigkeit a crown in the axial direction of the teeth of a gear is understood.

The hollow-bulbous region may have at least two mutually different radii of curvature in the radial direction in order to obtain a better contact pattern of the toothed wheel. It is advantageous if a web is formed between two adjacently arranged regions. It can thus improve the directional stability when rolling gears of multiple gears.

At least two of the plurality of hollow-crowned regions may have a mutually different, concave curvature in the axial direction, as a result of which the width crowning of the toothing of the toothed wheel can achieve greater accuracy with respect to its geometry, since a smaller deformation dimension is made possible by processing in several individual steps.

In particular, the sequence of different concave curved, hollow-spherical areas is designed such that the radius of curvature of the hollow crowning increases between the individual processing steps, so that in the successive areas of material in the edge region, ie in the edge region, ie the transition between the end face and the toothing of the gear, can be spent, whereby the strength can be increased in this edge region.

At least two of the plurality of hollow-crowned regions may differ in diameter at least in the apex region of the concave curvature. It is thus in turn the compression process in itself better adjustable. In particular, the diameter variation is formed such that the diameter of the rolling tool in the apex region of the hollow-crowned regions increases from one region to the next region, by which the densities in this region can be increased. However, it is also possible that, conversely, the diameter decreases from one area to the next area,

so that a relaxation zone between two individual compression steps is formed, before again follows an area with a larger diameter, and thus higher densities can be achieved at least in the surface region of the toothing of the gear.

The design of the rolling tool with a separate compression area ensures that tool production can be simplified. In addition, the rolling time is practically not extended or insignificantly. Another advantage is that if the compacting range of the tool breaks, the more expensive rolling tool for producing the crowning can be used further. The latter is more expensive, in particular, since these tools are usually produced by grinding on CNC profile grinding machines. This tool design is also suitable for producing a width crowning of the tooth flanks on helical gears by the gear to be produced is held axially immovable.

According to an embodiment variant of the rolling tool in which the compression region is separated from the shaping region for forming the crown of the toothing of the gear to be produced, it is provided that the two regions are separated by a third region having a smaller diameter than the two adjoining regions. This intermediate area supports the "threading" during the transfer of the gear from the compaction tool in the region of the forming tool, whereby this transfer smooth and gear-saving, that is gentle for the toothing to be produced, can be done.

It is also possible in this variant of the invention that the compression region is multi-track and has a width in the axial direction, which is a multiple of the width of the gear to be compressed in the same direction. It can thus at the same time a plurality of gears, that is, the teeth of the gears are compressed, so that the degree of utilization of the area for the shaping of the Breitenballigkeit can be increased, which is particularly advantageous because this shape allows a shorter cycle time compared to the compression process. On the other hand, it is also possible to form the compression process in several stages, wherein the gear changes sequentially from one track to the other track by simply moving, again here Variants are possible, with relaxation areas or variants with increasing diameter of the compaction tool.

There is a possibility that the rolling tools are used in the apparatus for rolling the teeth of a gear described below.

For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

Fig. 1

einen Ausschnitt aus einer Walzvorrichtung für Zahnräder in Seitenansicht;

Fig. 2

ein Walzwerkzeug gemäß einer ersten Ausführungsvariante der Erfindung;

Fig. 3

einen Schnitt durch einen Werkzeugzahn des Walzwerkzeuges nach Fig. 2 geschnitten gemäß III - III in Fig. 2;

Fig. 4

eine Draufsicht auf einen Schnitt durch einen Werkzeugzahn einer Ausführungsvariante des erfindungsgemäßen Walzwerkzeuges;

Fig. 5

eine Draufsicht auf einen Schnitt durch einen Werkzeugzahn einer weiteren Ausführungsvariante der Erfindung;

Fig. 6

ein Walzwerkzeug mit getrennten Bereichen der Verdichtung und der Formgebung der Balligkeit;

Fig. 7

eine Ausführungsvariante einer Walzvorrichtung in Null-Stellung;

Fig. 8

die Walzvorrichtung nach Fig. 7 mit eingeschwenkter Walzspindel;

Fig. 9

eine Ausführungsvariante einer Walzvorrichtung in Null-Stellung;

Fig. 10

die Walzvorrichtung nach Fig. 9 mit eingeschwenktem Walzschlitten;

Fig. 11

einen Schnitt durch einen Zahn eines Zahnrades in Draufsicht.

Each shows in a schematically simplified representation:

Fig. 1

a section of a rolling device for gears in side view;

Fig. 2

a rolling tool according to a first embodiment of the invention;

Fig. 3

a section through a tool tooth of the rolling tool after Fig. 2 cut according to III - III in Fig. 2 ;

Fig. 4

a plan view of a section through a tool tooth of a variant of the rolling tool according to the invention;

Fig. 5

a plan view of a section through a tool tooth of a further embodiment of the invention;

Fig. 6

a rolling tool with separate areas of compaction and shaping of the crown;

Fig. 7

a variant of a rolling device in the zero position;

Fig. 8

the rolling device after Fig. 7 with pivoted-in roller spindle;

Fig. 9

a variant of a rolling device in the zero position;

Fig. 10

the rolling device after Fig. 9 with pivoted roller carriage;

Fig. 11

a section through a tooth of a gear in plan view.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to the new situation mutatis mutandis when a change in position.

Fig. 1 shows a detail of a device 1 for rolling the teeth of a gear as known from the prior art. This device 1 comprises two gear-like running rolling tools 2, which are rotatably held in a respective holding device 3, in particular rolling carriage. These holding devices 3 are each arranged on their own carriage spindles 4.

The rolling tools 2, that is, their teeth are in meshing engagement with the toothing of a toothed wheel to be produced 5. The gear 5 itself is preferably formed of a sintered material by a sintering process and already has a rough contour of the toothing.

During the rolling process, both the rolling tools 2 and the gear 5 rotate, for which purpose at least one of the rolling tools 2 can be driven. But it is also possible that both rolling tools 2 are driven, or there is the possibility that the second rolling tool 2 is a follower, and the drive is transmitted from the first rolling tool 2 via the gear 5 to this rolling tool 2. On the other hand, there is the possibility that gear 5 itself is driven and the two rolling tools 2 are only so-called follower.

In Fig. 2 one of the rolling tools 2 is shown in side view. This rolling tool 2 consists of a tool body 6, the radially outwardly projecting tool teeth 7 for the meshing engagement in the toothing of the gear to be rolled 5 (FIG. Fig. 1 ) having.

How out Fig. 3 it can be seen that a cross section through a tool tooth 7 according to the section III - III in Fig. 2 shows, this tool tooth 7 hollow ball executed with an inwardly facing, concave curvature 8. In this case, this curvature 8 is complementary to the convex curvature of the produced crown of the tooth flanks of the toothing of the gear 5 to be produced. This hollow crowning preferably extends from a tooth root 9 into a tooth head 10 of the tool toothing of the rolling tool 2 (FIG. Fig. 2 ). It is thus possible, by transverse rolls to produce a crowning of the tooth flanks in the gear 5 to be produced, wherein at the same time a compression of the sintered gear can take place or is thus depending on the curvature 8, a material displacement and thus a compression of preferred areas, such as the edge regions , the toothing of the gear 5, ie in the region of the transition from the end faces to the tooth flanks achievable.

The hollow crowning, that is, the curvature 8, may have very different geometrical configurations. In the simplest case, this is how in Fig. 3 shown, circular arc-shaped. But there is also the possibility that this curvature 8 is composed of different areas, for example areas with different radii of curvature. These areas with different radii of curvature can be interrupted by rectilinear areas.

Furthermore, there is generally the possibility of forming the hollow crowning with different radii of curvature in their curvature profile in order to be able to produce toothed wheels 5 which have a better contact pattern or it is therefore also possible to be able to compensate for inaccuracies in the tooth flanks. For example, the curvature in the center region of the tooth flanks may have a greater radius of curvature than in at least one of the two edge regions of the tooth flanks, or vice versa. There are also finer gradations with more than two different radii of curvature possible.

Fig. 4 shows a section through a tool tooth 7 of a variant of a rolling tool according to the invention 2. This tool tooth 7 is divided into three areas 11 to 13, whereby three tracks are formed. It is thus possible three gears 5 ( Fig. 1 ) at the same time a rolling treatment for producing a crown in the tooth flank area to edit.

Of course, more than three such areas 11 to 13 can be arranged on the rolling tool 2.

On the other hand, it is possible, as in Fig. 5 which also shows a tooth 7 in cross-section and top view of a variant of the rolling tool 2 shows that these regions 11, 12 are formed differently on the rolling tool 2. For example, as shown, the region 11 in a crown region 14 of the bend 8 may have a smaller diameter 15 than a crown region 16, which in this case has a diameter 17 which is greater than the diameter 15. It is thus possible the compression and / or formation of the crown in the region of the tooth flanks of the toothed wheel 5 (FIG. Fig. 1 ) to suspend different, consecutive processing steps, so for example as in Fig. 5 shown to carry out a two-stage compaction, in a first compaction step, the gear 5 is cross-rolled in the region 11 and in a second compaction step with further compression in the area 12th

On the other hand, it is possible, as in Fig. 5 indicated by dashed lines, that the two regions 11, 12 differ in terms of their curvature 8, that is, the radius of curvature, wherein in the region 11, the curvature 8 has a smaller radius than a curvature 18 of the region 12. It is also possible in this embodiment in that the two bends 8, 18 are not circular-arc-shaped as shown, but that they have other geometric characteristics, such as different radii of curvature within at least one of the bends 8, 18, etc., as described above.

Of course, in the context of the invention, there is also the possibility that the regions 11, 12 are reversed, so that the gear 5 (FIG. Fig. 1 ) first passes through the region 12 with the larger diameter, whereby a corresponding compression and shaping takes place, then this gear 5 passes through the region 11, wherein in this region 11 due to the smaller diameter 15, compared to the diameter 17 of the region 12, a relaxation the compression zone is possible, and then another area connects, in Fig. 5 not shown, which has a larger diameter compared to the diameter 15 and thus a next compression step takes place, wherein this diameter may also be greater than the diameter 17 of the region 12th

How far out Fig. 5 can be seen, the areas 11 to 13 may be separated from each other by webs 19.

Fig. 6 shows a variant of the rolling tool 2, wherein this rolling tool is designed in three parts, with a first part 20, a middle, second part 21 and a third part 22, which connects to the second part 21. The part 20 is formed as a compression region 23, with the exclusive compression of the gear 5 (FIG. Fig. 1 ) in the region of the toothing, that is the tooth roots and / or tooth flanks and / or tooth heads takes place. With the middle region, which has a smaller diameter compared to the parts 20 and 22, the transfer of the meshing gear 5 during the operation of the device 1 (FIG. Fig. 1 ), ie with rolling tools 2 running, is made easier by the compression area 23 of the part 20 on the part 22. The part 22 in turn forms a region 24 of the rolling tool 2, in which ultimately the width crowning of the teeth of the toothing of the toothed wheel 5 (FIG. Fig. 1 ) will be produced. In an embodiment variant, it is possible to dispense with this middle part 21, so that therefore the compression region 23 directly adjoins the region 24 for producing the crowning. All parts, ie the parts 20 to 22 or 20 and 22, radially outwardly projecting on the tool body 6, the tool teeth with the tool teeth. 7

The tool part 22, that is, the tool teeth 7, as described above, be executed.

It is, although the multipart form is preferred for the reasons mentioned above, also possible that this rolling tool 2 after Fig. 6 is formed in one piece.

There is also the possibility that the compression region 23 also has more than one track, so that at the same time a plurality of gears 5 (FIG. Fig. 1 ) can be subjected to a compression process of the toothing.

The FIGS. 7 and 8 show a first embodiment of the device 1 for rolling the teeth and produce a width crowning of the gear 5. Dabei Rolling spindles 24, on which the rolling tools 2 are arranged, from the in Fig. 7 shown zero position, in which the axes of these rolling spindles 24 and the axis of the gear 5 are aligned colinearly, are pivoted by an angular amount in a vertical plane, as is apparent from Fig. 8 is apparent, so that this colinearity between the axes is no longer present. The gear 5 remains unchanged with respect to its axis. At the same time the rolling tools 2 are mitverschwenkt with the rolling spindles 24, as is made Fig. 8 is apparent. It can thus be achieved over the pivoting range, a different curvature of the width crowning of the toothing of the gear 5. The pivoting range can be, for example, up to 12 °, in particular between 0 ° and 9 °.

Alternatively or in addition to this pivoting of the rolling spindles 24 show the FIGS. 9 and 10 a variant of the device 1, in which the holding devices 3 are formed in several parts and rolling carriage 26 which in the holding devices 3 according to arrows 27 from the zero position in a pivoted-in a horizontal plane position ( Fig. 10 ) are pivotable. The rolling spindles 24 themselves are mitverschwenkt in this plane with respect to the axis of the gear 5, which remains unchanged. Also with this embodiment, a corresponding width crowning of the teeth of the toothing of the gear 5 can be achieved, wherein the extent of this width crowning over the adjustment angle of the rolling carriage 26 with respect to the zero position ( Fig. 9 ) can be adjusted. The two rolling carriages 26 have convex surfaces on their rear side remote from the toothed wheel 5, which surfaces can slide on concave surfaces of the tool holder of the holding device 3 for pivoting. A corresponding spindle drive or the like can of course also be provided.

There are also combinations of the two variants conceivable, so that therefore the rolling spindles 25 can be pivoted both in a horizontal and in a vertical plane.

In Fig. 11 Finally, a cross section through a tooth 28 of the toothing of the gear 5 is shown, this tooth 28 has the width crowning and this Breitenballigkeit has a progressive course, starting from a crest region 29 in the direction on end surfaces 30 the radius of curvature of the crown increases, whereby the above-mentioned effects are achieved.

There are also several curvatures of the width crowning possible, so that therefore the curvature gradually or continuously in the direction of the end faces 30, starting from the apex portion 29 from increasing.

The embodiments show possible embodiments of the device 1 and the rolling tool 2, wherein it should be noted that the invention is not limited to the specifically illustrated embodiments thereof, but also various combinations of the individual embodiments are mutually possible and this variation possibility due to the teaching to technical action by objective invention in the skill of those working in this technical field expert.

For the sake of order, it should finally be pointed out that in order to better understand the structure of the device 1 and of the rolling tool 2, these or their components have been shown partially unevenly and / or enlarged and / or reduced in size.

REFERENCE NUMBERS

1

contraption

2

rolling tool

3

holder

4

carriage spindle

5

gear

6

tool body

7

tool tooth

8th

curvature

9

tooth root

10

addendum

11

Area

12

Area

13

Area

14

apex region

15

diameter

16

apex region

17

diameter

18

curvature

19

web

20

part

21

part

22

part

23

compression region

24

roller spindle

25

Area

26

roller carriage

27

arrow

28

tooth

29

apex region

30

face

Claims (9)

1. A rolling tool (2) for producing a convex toothing on a gear (5) by means of a transverse rolling process, particularly for compressing the toothing of the gear (5) at least in certain areas, with a tool body (6) featuring tool teeth (7) that protrude radially outward and mesh with the toothing of the gear (5) to be rolled, wherein the tool teeth (7) are at least in certain areas realized concave in the axial direction in the region of the tooth flanks, characterized in that several concave regions (11 to 13) are arranged on the tooth flanks behind one another in the axial direction.
2. The rolling tool according to claim 1, characterized in that the concave region has at least two different curvature radii in the radial direction.
3. The rolling tool (2) according to claim 1 or 2, characterized in that a web (19) is respectively formed between two adjacently arranged regions (11 to 13).
4. The rolling tool (2) according to one of the claims 1 to 3, characterized in that at least two of the several concave regions (11 to 13) have a different concave curvature (8, 18) in the axial direction.
5. The rolling tool (2) according to one of the claims 1 to 4, characterized in that at least two of the several concave regions (11 to 13) have a different diameter (15, 17) at least in the apex (14, 16) of the concave curvature (8, 18).
6. The rolling tool (2) according to one of claims 1 to 5, characterized in that the tool body (6) features in the axial direction a compression region (23) and a separate region (24) for producing the convexity on the toothing of the gear (5).
7. The rolling tool (2) according to claim 6, characterized in that the compression region (23) and the separate region (24) for producing the convexity on the toothing of the gear are separated from one another by a third region that has a smaller diameter than the two adjacent regions (23, 24).
8. The rolling tool (2) according to claim 6 or 7, characterized in that the compression region (23) is realized with multiple tracks and has a width in the axial direction that amounts to a multiple of the width of the toothing of the gear (5) to be compressed referred to the same direction.
9. A method for compressing the toothing of a gear (5) at least in certain areas by means of a transverse rolling process, in which the toothing meshes with tool teeth (7) of a tool toothing of two rolling tools (2), characterized in that the compression by means of rolling tools (2) is carried out in accordance with one of the claims 1 to 8.

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