FLOW-FORMING MACHINE AND FORMING METHOD FOR PRODUCING A WHEEL

Abstract

The invention relates to a flow-forming machine and a forming method for producing a wheel having a rim from a workpiece, with a spinning mandrel, the outside of which is configured for forming the rim, a counter-mandrel, wherein the workpiece is clamped on the spinning mandrel or the counter-mandrel, a rotary drive and at least one compression roller, which can be advanced against the workpiece for forming the rim. According to the invention, it is provided that the spinning mandrel has a sleeve-like perimeter element, which can be displaced axially during forming. A controller is provided, by means of which, while the rim is being formed, the at least one compression roller and the perimeter element of the spinning mandrel can be displaced axially relative to the workpiece in a coordinated manner.

Claims

1. A flow-forming machine for producing a wheel, in particular a vehicle wheel, having a rim, from a workpiece, comprising a spinning mandrel, the outside of which is configured for forming the rim, a counter-mandrel, which can be displaced axially relative to the spinning mandrel, wherein the workpiece is clamped on the spinning mandrel and/or the counter-mandrel, a rotary drive for the rotational driving of spinning mandrel and counter-mandrel with the clamped workpiece and at least one compression roller, which can be advanced against the workpiece axially and radially for forming the rim, wherein the spinning mandrel has a sleeve-like perimeter element, which can be displaced axially to the workpiece during forming, the spinning mandrel has a main support, on which the perimeter element is mounted in an axially slideable manner, on a free front side of the main support a front element is arranged, wherein a radial hub or a drop center can be clamped axially between the spinning mandrel with the front element and the counter-mandrel, and a controller is provided, by means of which, while the rim is being formed, the at least one compression roller and the perimeter element of the spinning mandrel can be displaced axially relative to the workpiece in a coordinated manner.

2. The flow-forming machine according to claim 1, wherein the sleeve-like perimeter element is configured in a conical shape at least in part, wherein the perimeter element tapers towards a free end.

3. The flow-forming machine according to claim 1, wherein in a region of the perimeter element, a forming region is arranged, which is configured for forming a rim flange on the rim.

4. The flow-forming machine according to claim 2, wherein for forming an axial undercut region on the rim the controller is configured for the relative axial displacement of the at least one compression roller and the perimeter element, so that the at least one compression roller initially engages on a first diameter region of the conical perimeter element, next engages on a second diameter region of the perimeter element, which is smaller than the first diameter region, and then engages on a third diameter region of the perimeter element, which is larger than the second diameter region.

5. The flow-forming machine according to claim 3, wherein for the axial sliding of the perimeter element on the main support at least one adjusting element, in particular an adjusting cylinder or a spindle drive, is provided.

6. The flow-forming machine according to claim 3, wherein the front element is fitted on the main support in such a way that it can be replaced.

7. A forming method for producing a wheel, in particular a vehicle wheel, having a rim, from a workpiece, in which the workpiece is clamped on a spinning mandrel, the outside of which is configured for forming the rim, and/or a counter-mandrel, the clamped workpiece is set in rotation by a rotary drive and at least one compression roller is advanced against the rotating workpiece axially and radially, wherein the rim is formed, wherein the spinning mandrel has a sleeve-like perimeter element, which is displaced axially while the rim is being formed, the spinning mandrel has a main support, on which the perimeter element is slid axially, on a free front side of the main support a front element is arranged, wherein a radial hub or a drop center of the workpiece is axially clamped between the spinning mandrel with the front element and the counter-mandrel, and while the rim is being formed, the at least one compression roller and the perimeter element of the spinning mandrel are displaced axially relative to the workpiece in a coordinated manner.

8. The forming method according to claim 7, wherein multiple compression rollers are advanced against the workpiece in an even distribution around the perimeter of the workpiece and with an axial offset relative to each other.

9. The forming method according to claim 7, wherein while the rim is being formed, the at least one compression roller and the perimeter element are axially displaced differently.

10. The forming method according to claim 7, wherein for forming an axial undercut region on the rim the at least one compression roller initially engages on a first diameter region of the conical perimeter element, next the at least one compression roller engages on a second diameter region of the perimeter element, which is smaller than the first diameter region, and then the at least one compression roller engages on a third diameter region of the perimeter element, which is larger than the second diameter region.

11. The forming method according to claim 7, wherein a perimeter element is used, the axial length of which is smaller than the rim that is to be formed, and with the perimeter element, wheels with different axial lengths of the rim are formed.

12. The forming method according to claim 7, wherein during forming the workpiece is set in rotation about a vertical axis of rotation.

Description

[0028] The invention is explained in more detail below with reference to preferred exemplary embodiments, which are illustrated schematically in the attached drawings. In the drawings, the figures show the following:

[0029] FIG. 1: a cross-sectional view of an essential part of a flow-forming machine according to the invention; and

[0030] FIG. 2: a cross-sectional view of a vehicle wheel produced according to the invention;

[0031] FIGS. 3a to 3c: cross-sectional views through a workpiece during various forming steps according to a variant of the invention;

[0032] FIGS. 4a to 4c: cross-sectional views through a workpiece in various forming steps according to a further variant of the invention;

[0033] FIGS. 5a to 5d: cross-sectional views through a workpiece in various forming steps according to a further variant of the invention;

[0034] FIGS. 6a to 6e: cross-sectional views through a workpiece in various forming steps according to a further variant of the invention.

[0035] A flow-forming machine 10 according to the invention has a spinning mandrel 20 and an opposite counter-mandrel 12, between which a workpiece 5 with a disc-shaped hub region 6 having a central centering hole and a perimeter region 7 that is to be shaped is axially clamped. The counter-mandrel 12 and the spinning mandrel 20 are each rotatably mounted by means of a drive flange 16 and 17 and are connected to a rotary drive (not illustrated), preferably each to a separate rotary drive, wherein the spinning mandrel 20, the counter-mandrel 12 and the clamped workpiece 5 can be driven in a rotary manner around a vertical, central axis of rotation 2 during forming.

[0036] The spinning mandrel 20 has a central main support 22, on the free end of which a ring- or disc-shaped front element 24 is releasably attached by means of screws. The front element 24, like the opposite counter-mandrel 12, which is provided with a forming surface 14, is adapted to the shape of the workpiece 5 that is to be clamped. In the event of a change of design of the workpiece 5, in particular of the hub region 6, the counter-mandrel 12 and the front element 24 can easily be released by means of the screw connections and replaced by appropriately adapted new elements. On the forming surface 14, a first rim flange 56 of a vehicle wheel 50 that is to be produced can be fashioned.

[0037] Furthermore, the spinning mandrel 20 has a sleeve-like perimeter element 30, which is mounted in an axially slideable manner on the main support 22. For the purpose of sliding, the perimeter element 30 is attached to a slide element 28, which is axially slideable by means of an adjusting cylinder (not illustrated) along the axis of rotation 2 between an extended starting position and a retracted end position, which is illustrated in FIG. 1. The perimeter element 30 has in its front or upper region an external conical surface 32, which tapers upwards. In a bottom end or central region, a forming region 34 is configured, which is designed for fashioning a second rim flange 58 on the vehicle wheel 50.

[0038] For forming the vehicle wheel 50 from the workpiece 5, multiple compression rollers 40, only one of which is indicated in diagrammatic form, are advanced against the perimeter region 7 of the workpiece 5 radially. The perimeter element 30 of the spinning mandrel 20 here is in the upper starting position, so that it acts as a counter bearing for the compression roller 40 engaging on the workpiece 5. The compression roller 40 is adjusted axially and to a certain extent also radially to form a rim region, wherein a wall thickness of the perimeter region 7 is thinned and rolled out to form the rim region. By means of a controller, as a function of the movement of the compression roller 40 the sleeve-like, conical perimeter element 30 is displaced axially, so that the desired internal diameter region is always provided at the desired position as a counter bearing for the compression roller 40. Depending on an intended length of the rim region, the perimeter element 30 remains stationary in an axial direction, so that during a further displacement of the compression roller 40 the material of the workpiece 5 is formed in the forming region 34 and thus the second rim flange 58 is flow-formed in the hub region 6, corresponding to the first rim flange 56.

[0039] In FIG. 1, to illustrate the flexibility of the flow-forming machine 10 according to the invention in wheel production, a total of three different lengths of the vehicle wheel 50 are indicated in diagrammatic form. The spinning mandrel 20 is thus to a large extent independent of the vehicle wheel 50 to be fashioned and can be employed for different axial lengths and internal contours. Only the electronic controller has to be adapted to the production without the need for any mechanical conversion work on the flow-forming machine 10.

[0040] In FIG. 2, in highly diagrammatic form, a further shape of a vehicle wheel 50 is shown, which can be produced according to the invention. The vehicle wheel 50 has a disc-shaped hub 52 and a drum-like rim 60, which are arranged in a substantially rotationally symmetrical manner relative to a wheel axis 51. In the region of the hub 52, a central hole 54 and further holes can be provided, depending on the design.

[0041] The rim 60 is provided with a rim well 62, which extends from a first rim flange 56 to a second rim flange 58. In a central section of the rim well 62, a drop-center region 64 is fashioned. The drop-center region 64 represents a radial narrowing in the rim well 62 and thus an undercut region 70, which is shown in diagrammatic form particularly clearly in FIG. 2. The drop-center region 64 can also have different dimensions and a different arrangement and can in particular be arranged closer to the freely projecting second rim flange 58.

[0042] The drop-center region 64 has two slightly oblique lateral flanks 66 running in a substantially radial direction, which extend as far as an approximately cylindrical base 68. The vehicle wheel 50 with the rim 60 and the drop-center region 64 can be produced by a method according to the invention with an appropriately conically configured perimeter element 30 as a counter bearing for externally engaging compression rollers 40. The perimeter element 30 in this case is axially displaced by means of a controller and appropriate adjusting element as a function of the position of the compression roller 40 to provide the appropriate diameter region.

[0043] According to the method variant of FIGS. 3a to 3c, a pot-shaped workpiece 5 with a radial hub region 6 and a drum-like perimeter region 7 is shaped by the method according to the invention into a flow-formed wheel blank according to FIG. 3b or into the finished wheel according to FIG. 3c, with an intermediate step, e.g. a wheel blank before turning, being illustrated in FIG. 3b.

[0044] In the method variant according to FIGS. 4a to 4c a workpiece 5 is used, which is Y-shaped in a half cross-section and which has a radial hub region 6 and a drum-like perimeter region 7 extending to both sides of the radial hub region 6. In this method variant, a flow-forming machine can be used in which the counter-mandrel is configured identically or largely identically with the spinning mandrel and has a displaceable perimeter element.

[0045] In the method variant according to FIGS. 5a to 5d, a disc-shaped workpiece 5, also known as a round blank, is provided as the starting workpiece. This is shaped into an intermediate shape according to FIG. 5b by turning and partially splitting. The radial hub region 6 and a V-shaped perimeter region 7 are fashioned at this stage. The workpiece 5 is then finally shaped into the vehicle wheel 50 with a drop center via the intermediate step according to FIG. 5c.

[0046] According to the further method variant of FIGS. 6a to 6e, a tubular workpiece 5, which forms the perimeter region 7, can be used as the starting workpiece. The workpiece 5 here can be clamped by a counter-mandrel, which is configured as a radial chuck, for instance as a four-jaw chuck. The spinning mandrel can thus be employed for processing the entire radial inside of the workpiece 5. According to FIG. 6e, a wheel 50 is achieved which consists only of the drum-like rim 60. Where a hub region is desired, this can be produced separately and attached to the rim 60 for instance by welding, in particular friction welding, or by screwing.

[0047] According to a further method variant, a tubular workpiece 5 according to FIG. 6a with flared regions on both sides can be held via a spinning mandrel according to the invention in a double-sided configuration and the drop center produced first by pressing or profiling, so that this region is used for axial holding or securing against axial sliding or for torque transmission for the subsequent flow-forming process with axial sliding of the sleeve-like perimeter elements.