METHOD AND FORMING SYSTEM FOR PRODUCING A DRUM-SHAPED GEAR PART

Abstract

The invention relates to a method and a forming system for producing a gear part through a rotational forming. According to the invention provision is made in that in a preforming step a rotationally symmetrical workpiece is set into rotation about its center axis and, at least through axial feeding and passing of at least one forming roller, a stretch-flow forming is carried out, wherein a cylindrical circumferential wall with a defined target wall thickness is shaped which is smaller than a basic wall thickness of the workpiece. Subsequently, in a finish-forming step the preformed workpiece is clamped onto an inner mandrel with external toothing and set into rotation and at least one profiled toothed roller is fed radially, by which the cylindrical circumferential wall, whilst substantially maintaining the target wall thickness, is formed into the external toothing of the inner mandrel, wherein a drum-shaped toothed region with a splined toothing is shaped.

Claims

1. Method for producing a drum-shaped gear part through a rotational forming, wherein in a preforming step a rotationally symmetrical workpiece is set into rotation about its center axis and, at least through axial feeding and passing of at least one forming roller, a stretch-flow forming is carried out, wherein a cylindrical circumferential wall with a defined target wall thickness is shaped which is smaller than a basic wall thickness of the workpiece, and subsequently in a finish-forming step the preformed workpiece is clamped onto an inner mandrel with external toothing and set into rotation and at least one profiled toothed roller is fed radially, by which the cylindrical circumferential wall, whilst substantially maintaining the target wall thickness, is formed into the external toothing of the inner mandrel, wherein a drum-shaped toothed region with a splined toothing is shaped.

2. Method according to claim 1, wherein as basic workpiece a circular blank or a cup-shaped preform is used, in which a hub region is preformed.

3. Method according to claim 1, wherein the preforming step and/or the finish-forming step is carried out in several partial steps in the same workpiece clamping.

4. Method according to claim 1, wherein during the forming of the splined toothing the workpiece is held axially and/or radially in its edge region at the open end lying opposite a radially running hub region.

5. Method according to claim 4, wherein an axial holding takes place in a flexible manner, in particular in a pressure-dependent manner, wherein length or volume tolerances of the workpiece are compensated.

6. Method according to claim 1, wherein during radial profiling the at least one toothed roller is displaced axially or fed radially in at least two steps which are carried out in positions that are axially offset to each other.

7. Method according to claim 1, wherein in the edge region of the workpiece a reinforced region of greater material thickness is designed.

8. Method according to claim 1, wherein through forming or turning the hub region is weight- or strength-optimized.

9. Forming system, in particular for carrying out a method according to claim 1, having at least a first forming station which has a rotationally drivable main spindle, at least one forming roller that can be fed relatively axially and a first clamping element which is designed for clamping a workpiece on the main spindle, at least a second forming station which has a rotationally drivable inner mandrel with an external toothing, at least one toothed roller that can be fed relatively radially and a second clamping element which is designed for clamping the workpiece on the inner mandrel, and a handling station which is arranged between the first forming station and the second forming station and designed for transferring the workpiece after a preforming in the first forming station to the second forming station for finish-forming.

10. Forming system according to claim 9, wherein the first forming station is designed for spinning and flow forming and the second forming station is designed for profiling.

11. Forming system according to claim 9, wherein the main spindle of the first forming station and the inner mandrel of the second forming station are directed in parallel and vertically.

12. Forming system according to claim 9, wherein for clamping the workpiece on a first tool a first tailstock spindle is assigned to the main spindle and a second tailstock spindle is assigned to an externally toothed inner mandrel as second tool, wherein the first tailstock spindle and the second tailstock spindle are supported in an axially displaceable manner.

13. Forming system according to claim 9, wherein the main spindle, the inner mandrel, the first tailstock spindle and/or the second tailstock spindle are supported by means of a quick-changing means.

14. Forming system according to claim 9, wherein the handling station is designed for delivering the workpiece to be formed and for removing the finish-formed gear part.

15. Forming system according to claim 9, wherein by way of a synchronization transmission or a drive controlled in a rotationally synchronous manner the at least one toothed roller is driven in a rotation angle synchronous manner to the inner mandrel.

Description

[0029] The invention is explained further hereinafter by way of preferred embodiments illustrated schematically in the drawings, wherein show:

[0030] FIG. 1 a cross-sectional view of a rotationally symmetrical basic workpiece;

[0031] FIG. 2 a cross-sectional view of a drum-shaped gear part produced according to the invention;

[0032] FIG. 3 a perspective view of the gear part of FIG. 2;

[0033] FIG. 4 an enlarged detailed cross-sectional view of a splined toothing on the workpiece according to FIGS. 2 and 3;

[0034] FIG. 5 a perspective view of a forming system according to the invention;

[0035] FIG. 6 a top view of the forming system of FIG. 5;

[0036] FIG. 7 a front view of a second embodiment of a gear part produced according to the invention;

[0037] FIG. 8 a cross-sectional view of the gear part of FIG. 7;

[0038] FIG. 9 a front view of a third embodiment of a gear part produced according to the invention;

[0039] FIG. 10 a cross-sectional view of the gear part of FIG. 9;

[0040] FIG. 11 a front view of a fourth embodiment of a gear part produced according to the invention;

[0041] FIG. 12 a cross-sectional view of the gear part of FIG. 11;

[0042] FIG. 13 a front view of a fifth embodiment of a gear part produced according to the invention;

[0043] FIG. 14 a cross-sectional view of the gear part of FIG. 13;

[0044] FIG. 15 a front view of a sixth embodiment of a gear part produced according to the invention;

[0045] FIG. 16 a cross-sectional view of the gear part of FIG. 15;

[0046] FIG. 17 a perspective view of a further embodiment variant of a gear part produced according to the invention with circular recesses in the splined toothing; and

[0047] FIG. 18 a perspective view of a further embodiment variant of a gear part produced according to the invention with elongated holes in the splined toothing.

[0048] In FIG. 1 a basic workpiece 5 in the shape of a circular blank or plate, also referred to as workpiece 5, is illustrated. This has a radially running hub region 6 with a central recess. Arranged in a stepped manner with respect to the hub region 6 is a thickened circumferential region 7. The workpiece 5 can be produced by deep-drawing, forging, casting or in another suitable way.

[0049] In a non-depicted preforming step the workpiece 5 is clamped on a rotationally drivable main spindle and folded over axially by approximately 90 by means of at least one forming roller capable of being fed axially, wherein by way of a generally known stretch-flow forming process a basic wall thickness of the workpiece 5 is at the same time shaped to a defined target wall thickness of the desired cylindrical circumferential wall 14.

[0050] In a subsequent finish-forming step the workpiece 5 thus preformed is then finish-formed to a drum-shaped gear part 10 which is illustrated in FIGS. 2 and 3. In this finish-firming step a splined toothing 20 is formed into a toothed region 16 while the target wall thickness of the cylindrical circumferential wall 14 is substantially maintained. At an open end lying axially opposite the hub region 6 that did not undergo further forming the splined toothing 20 is bounded by an annular edge region 18.

[0051] The splined toothing 20 designed on the gear part 10 according to the invention is shown in FIG. 4. To shape the splined toothing 20 the workpiece 5 is clamped with the cylindrical circumferential wall 14 onto an inner mandrel with a corresponding external toothing and set into rotation. Afterwards, at least one profiled toothed roller is fed radially, by which the cylindrical circumferential wall 14 is formed or folded into the external toothing of the inner mandrel while the target wall thickness is substantially maintained. In doing so, recessed regions 22 and protruding regions 24 are developed that are connected to each other via obliquely directed flanks 26 in the illustrated embodiment. The protruding regions 24 can have a wall thickness t1, the flanks 26 a wall thickness t2 and the recessed regions 22 a wall thickness t3, which differ slightly from each other, in particular by a few tenths of a millimeter, while, within the meaning of the invention, the previously set target wall thickness is substantially maintained.

[0052] Thus, by way of the invention a weight-optimized gear part 10 can be produced, in which, as compared to a hub region 6 having a substantially unchanged wall thickness, a reduced wall thickness is set in a non-cutting manner on a cylindrical circumferential wall 14, into which the desired splined toothing 20 is then introduced.

[0053] A forming system 50 according to the invention is shown schematically in FIGS. 5 and 6. On a machine bed 52, preferably of multi-part design, a first forming station 60 and a second forming station 70 are arranged. Between the first forming station 60 and the second forming station 70 a handling station 80 with a multi-axial robot 82 is provided that has a gripping means 84 for gripping a workpiece and for transferring the workpiece from the first forming station 60 to the second forming station 70.

[0054] According to a generally known flow-forming machine the first forming station 60 is designed with a rotationally drivable main spindle that is provided for a vertical arrangement in the illustrated embodiment. Via a lateral delivery means 68, which can also be a multi-axial robot with gripping means, a basic workpiece is delivered laterally into the first forming station 60. By way of a first tailstock spindle the delivered basic workpiece is clamped axially on the main spindle with a forming mandrel that is cylindrical at least in some regions. Afterwards, the main spindle, together with the first tailstock spindle, is set into rotation and at least one forming roller is fed to the workpiece. The forming roller passes axially over a circumferential region of the basic workpiece so that a cylindrical circumferential wall with a defined, reduced wall thickness, also referred to as target wall thickness, is produced. The target wall thickness complies with the necessary strength conditions required for the splined toothing 20 to be formed in.

[0055] After this first preforming step in the first forming station 60 the clamping of the workpiece is released again and by means of the multi-axial robot 82 the workpiece is taken out of the first forming station 60 and transferred to the second forming station 70. In the second forming station 70 the preformed workpiece is clamped axially by means of a second tailstock spindle on an inner mandrel having an external toothing. A center axis of the workpiece and an axis of rotation of the inner mandrel are also directed vertically.

[0056] After clamping of the preformed workpiece this is set into rotation by the inner mandrel and at least one profiled toothed roller is then fed radially to the cylindrical circumferential wall of the workpiece. The profile of the toothed roller matches the profile of the external toothing on the inner mandrel in such a manner that the cylindrical circumferential wall is formed or, as it were, folded into the recesses of the external toothing of the inner mandrel. In doing so, the previously set target wall thickness remains largely unchanged.

[0057] On completion of the finish-forming step the ready-formed gear part 10 is removed laterally by a removal means 78 which can also have a multi-axial robot with a gripping means.

[0058] For the various drives, which are hydraulic or electric drives in particular, the forming system 50 according to the invention has a cooling and lubricating means 54 for cooling the hydraulic fluid and a hydraulic station 56. Furthermore, a control means 58 is provided which is arranged in the form of control cabinets.

[0059] By preference, the handling station 80 is provided with a door 86 so that the handling station is accessible for operating and maintenance purposes. Furthermore, on a front side of the forming station 50 an operating unit 59 with a monitor and an input terminal is preferably arranged.

[0060] In FIGS. 7 and 8 a second embodiment of a gear part 10 produced in accordance with the invention is illustrated, in which case in the hub region 6 elongated holes 31 running in the circumferential direction are introduced together with a central opening.

[0061] In the third embodiment of a gear part 10 produced in accordance with the invention and pursuant to FIGS. 9 and 10 impressions 32 are formed into the hub region. These can be designed in a radially directed manner and serve as an additional reinforcement of the hub region 6. The impressions 32 can be formed in before the preforming step or during clamping in the first forming station 60 by a correspondingly designed and shaped main spindle.

[0062] The fourth embodiment of a gear part 10 according to the invention and pursuant to FIGS. 11 and 12 also shows impressions 32 that are formed into the hub region 6 and shaped more distinctively as compared to the third embodiment.

[0063] In the fifth embodiment of a gear part 10 produced according to the invention and pursuant to FIGS. 13 and 14 a sleeve-shaped hub 34 is arranged in the hub region 6. The sleeve-shaped hub 34 can be designed on the basic workpiece by deep-drawing, casting or forging or in another way. Furthermore, for an additional weight optimization in the hub region 6 an annular formation 35 providing a further optimization in terms of weight and constructed space can be designed.

[0064] In the sixth embodiment pursuant to FIGS. 15 and 16 a connecting hub 38 directed inwards to the toothed region 16 is designed in the gear part 10 according to the invention. This can have a first section 41 of larger diameter and a second section 42 of smaller diameter that are connected to each other by a stepped region. In the cylindrical wall of the first section 41 cross bores or cross openings can be provided. On the internal side of the cylindrical second section 42 grooves can be designed that are configured to create a shaft-hub connection.

[0065] The connecting hub 38 with the first section 41 and the second section 42 can be shaped integrally with the basic workpiece e.g. by deep drawing or can alternatively be produced of two parts by welding, as illustrated in FIG. 16.

[0066] In addition to the specific design of the hub region 6 embodiment variants also reside in an alternative design of the splined toothing 20, as depicted in FIGS. 17 and 18. For instance in the splined toothing 20 according to the embodiment of FIG. 17 cross bores 44 are introduced which serve for the passage of transmission oil when used as clutch plate carrier.

[0067] Similarly, according to the embodiment pursuant to FIG. 18 axial elongated holes 46 can be introduced into the splined toothing 20. At the end of the splined toothing 20 facing away from the hub region 6 an edge region 18 with a material thickening can be designed for creating an annular reinforced region 19.

[0068] The embodiment variants of a gear part 10 produced in accordance with the invention and illustrated in FIGS. 7 to 18 can be combined with each other in any desired way in their design variants.