EP3351313B1 - Method and device for pressure rolling - Google Patents

Description

The invention relates to a method for pressure rolling, in particular a vehicle wheel, wherein a workpiece is set in rotation about an axis of rotation by means of a spindle and at least one outer roller is set on an outside of the workpiece by means of an external support, an axially extending jacket region of the workpiece being formed with thinning of the material is, according to the preamble of claim 1.

The invention further relates to a device for pressure rolling with a spindle, which is driven by a drive rotating about an axis of rotation and designed to hold a workpiece, at least one outer roller, which is rotatably mounted on an external support, which is axially and radially for delivery to the workpiece can be moved relative to the axis of rotation, and at least one inner roller, which can be set on an inner side of the workpiece opposite the outer roller, according to the preamble of claim 10.

In the case of vehicle wheels in particular, preferably made of an aluminum material, these are pressed against a central chuck. The spinning chuck, also called spinning tool, represents the negative shape of the inner geometry of the rim of a vehicle wheel. A change in the rim usually also requires a change in the spinning chuck, which is costly. Manufacture of vehicle wheels or other pressed parts with an inner contour is therefore often only economical for large quantities.

A method for pressure rolling with an increased flexibility in the shaping is from the EP 2 210 682 B1 known. In this known method, a variable mandrel with a conical outer contour is provided as the chuck. Of the Mandrel is arranged concentrically to the axis of rotation. By axially adjusting the mandrel, a variable inner diameter can be provided at the respective forming zone. However, this procedure is limited to certain internal contours.

From the DE 35 45 506 A1 a tool for the pressure rolling of hollow cylindrical workpieces is known. Simultaneously with the delivery of outer rollers on an outer contour of the tube workpiece, inner rollers are fed to an outer contour with an inner roller carrier. A fixed distance is specified between the outer roller and the inner roller, which specifies the circumference of an ironing roll and the wall thickness of the tubular workpiece to be formed.

A similar procedure is out of the US 3,287,951 known. An outer roller and an associated inner roller are arranged on a common roller carrier. The outer roller can be adjusted via a mechanical adjusting mechanism so that the distance between the inner roller and the outer roller can be adjusted at the beginning of the forming process.

A generic state of the art is based on the WO 2012/042221 A1 forth. On a hollow cylindrical workpiece, a single forming roller is fed on one side and two counter bearing rollers on the opposite workpiece side. A pressing with a constant wall thickness or a projection pressing with a predetermined wall thickness reduction is carried out, which depends on the predetermined projection angle.

The invention is based on the object of specifying a method and a device for pressing rollers, with which a particularly high dimensional variety of workpieces can be generated flexibly and efficiently.

The object is achieved on the one hand by a method with the features of claim 1 and on the other hand by a device with the features of claim 10. Preferred embodiments of the invention are specified in the respective dependent claims.

The method according to the invention is characterized in that, by means of a CNC control, the inner support with the inner roller and the outer support with the outer roller are moved radially and axially to one another individually when the jacket region is formed, with a defined wall thickness profile with different wall thicknesses between the at least one on the jacket region Outer role and the at least one inner role is formed.

A basic idea of the invention is to depart from a predetermined pressing tool, which specifies a negative shape of an inner contour of the workpiece, and to provide at least one inner roller for shaping the inner contour. The inner roller is not moved in a straight line parallel to the outer roller, but the inner roller is mounted on an inner support which can be moved axially and radially to the axis of rotation independently of the outer support. In this way, an almost unlimited variety of shapes can be created without having to convert a pressing tool.

Furthermore, according to the invention, a CNC control is provided with which the inner support with the inner roller and the outer support with the outer roller can be moved independently of one another. A free contour course can be set on the inside and outside of the workpiece. Furthermore, by means of a relative adjustment of the outer roller to the assigned inner roller, the effective shaping gap and thus a wall thickness profile can be formed in the axial jacket area of the workpiece to be shaped with a high degree of freedom in shaping.

With the method, workpieces can be produced efficiently even in small numbers or even individual workpieces, since complex production of a rigid mandrel is not necessary. Rather, the contour is freely adjusted to one another by appropriate control of the rollers.

According to the invention, it is provided that the at least one inner roller and the at least one associated outer roller are moved radially and axially with respect to one another in order to form the jacket region. As a result, an individual course of the inner contour and outer contour as well as an intermediate wall thickness course can be set almost arbitrarily. According to a finding of the invention, the wall thickness is not only determined by a radial distance between the inner roller and the outer roller. Particularly in the case of an ironing press roll in which the jacket area is compared to an original starting thickness is reduced, the inner role or the outer role of the other role axially ahead or lagging. As a result, an abutment function is also created in an axial direction, which can be essential for an accurate stretching.

According to a further embodiment variant of the invention, it is preferred that the workpiece is clamped on the spindle, with a free space in a central area remaining radially inside the jacket area. This jacket area is designed so large that at least one inner roller can be delivered to an inner contour of the jacket area. For this purpose, the workpiece is preferably clamped on one side on the spindle, for example by means of a three- or multi-jaw chuck. Other clamping mechanisms can be used, for example also with an axial clamping element or counter-holding element, which is attached to or through a central opening on a hub area of the workpiece.

According to a further method variant according to the invention, it is advantageous for the workpiece to be clamped on a partial area of the outer circumference. The workpiece can be centered on the spindle from the outside using appropriate clamping jaws.

According to a development of the invention, it is preferred that the workpiece is provided with a clamping and / or centering aid before the pressure rolling. In the chuck used, centering is preferably provided for centering the workpiece during the clamping process. For this purpose, a corresponding centering aid can be attached to the workpiece, which is cast on in particular in cast wheels. This can be carried out, for example, by means of projections or stop edges that these support the torque transmission from the chuck to the workpiece.

According to a preferred development, it is provided according to the invention that the clamping and / or centering aid is removed from the workpiece after the pressure rolling. This can be done in particular by simple machining. This can also be done with a separate machine, such as a lathe, or the pressure rolling device itself with an additional cutting tool.

For a particularly gentle clamping, it is provided according to a preferred embodiment variant of the invention that an internal clamping device is provided, by which a hub area of the workpiece is covered. This is because the deformation of the wheel preferably begins in the immediate vicinity of a radially running hub area of the workpiece. These can be a star or rim spokes on certain vehicle rims. The clamping device has a relatively large, plate-like clamping surface, by means of which the specially designed and preformed hub area is covered and protected.

In principle, the method according to the invention can be used to form any workpiece with an axially extending, tubular jacket region. According to a development of the invention, it is particularly preferred that the casing area is designed as a rim bed of a vehicle wheel with at least one hump, which is formed as a thickening in the course of the wall thickness. It is further preferred to form a cast preform into a rim blank, which is then further processed to the finished wheel, in particular by machining.

With the method according to the invention, a largely weight-optimized vehicle wheel can be produced in which the wall thickness profile of the rim base is adapted to the actual load on the vehicle wheel during operation. Areas with low loads are formed with a small wall thickness, while heavily loaded areas are formed with a correspondingly large wall thickening. In addition, a hump, that is to say a bead for fixing the tire to the rim base, can also be formed in a simple manner by thickening the wall along the rim base. The hump represents a radially outwardly projecting annular elevation on the rim well.

It is particularly advantageous that the inner roller and the outer roller are simultaneously moved relative to one another in the radial and axial directions in order to form a hump and / or horn region. The side rim flanges can also be shaped in a corresponding manner. Other and different inner rollers with a modified and adapted outer contour can also be used to form the rim flanges. The same applies to the use of contoured outer rollers to form the rim flanges. Thanks to the freely programmable interior and External rollers also make it possible to gradually shape the rim contour, so that higher work hardening and / or structural changes are brought about in specific areas of the rim. This enables increases in stability and / or weight reductions on the workpiece.

The device for pressure rolling according to the invention is characterized in that the CNC control is designed for the individual movement of the at least one inner support with the inner roller and the at least one outer support with the outer roller during the pressure rolling of a workpiece, the at least one inner roller and the at least one assigned outer roller can be moved radially and axially relative to one another when the jacket region is formed.

The device according to the invention can be used in particular to carry out the method described above. The advantages described above can be achieved.

A preferred embodiment of the device according to the invention consists in that several inner rollers and outer rollers are provided, one inner roller being assigned to one outer roller. A plurality of inner rollers, preferably three inner rollers, are preferably arranged on a common roller carrier. Compared to this common roller carrier or inner support, the individual inner rollers can be pivotably adjustable relative to the axis of rotation. In this way, a targeted shaping of the different contour areas of the workpiece can be achieved. Depending on the application, in a further preferred embodiment, axially and / or radially adjustable inner rollers or inner supports can be provided separately.

According to a development of the device according to the invention, it is preferred that a clamping device for clamping the workpiece is arranged on the spindle, with a free space in a central region remaining radially inside the jacket region of the workpiece. The at least one inner support can be moved into this free space, so that an inner contour of the jacket region of the workpiece can be formed by the at least one inner roller.

For highly efficient production, it is preferred according to one embodiment of the invention that a control device with a data memory is provided, in which data records for moving the inner roller and the outer roller are stored for different workpiece shapes. In this way, the machine operator can call up the desired data record for a specific workpiece design. Different workpieces can thus be efficiently produced on one spinning roll device without a complex conversion. The device with the control device is provided via a remote data connection, in particular an Internet connection. In this way, new or updated data records for existing or new workpieces can be transferred to the machine's data memory. The device according to the invention can thus be provided for highly flexible use in Industry 4.0 projects.

Furthermore, particularly good contouring can be achieved according to a development of the invention in that at least one of the rollers is provided with an auxiliary drive for rotating the roller. Both the inner rollers and the outer rollers can be provided with a respective roller drive. As a result, the inner and / or outer rollers can be accelerated before they come into contact with the material of the rotating workpiece to be formed. This counteracts baking on the rollers and / or increased wear of the rollers. In a preferred embodiment, the roller drive is designed with a freewheel or speed control device which enables the peripheral speed of the roller to be automatically adapted to the component.

An ejector, in particular an axially adjustable ejector, can be used to eject from the tensioning device. The ejection is preferably carried out as a controlled movement. The device for pressure rolling is preferably designed as a vertical machine with a hanging or alternatively upright spindle, so that workpiece centering is made easier. In the version with a vertically hanging spindle, the counter holder of the clamping device can also take on the function of loading and unloading.

The inner and / or outer supports are preferably designed as independently controllable supports that are only synchronized electrically. The outer roller is preferably set at an angle of 0 to 15 ° to the axis of rotation during the inner rollers are preferably set from 0 to 45 ° and participate in the forming over a preferably significantly larger roller radius. The outer and inner rollers are preferably fed via two linear cross supports. Alternatively, the use of at least two inner rollers on the cross support can be dispensed with by simultaneously moving or starting the rollers using a wedge slide.

Fig. 1:

eine Teilquerschnittsansicht einer erfindungsgemäßen Vorrichtung beim Formen eines Fahrzeugrades in einem Anfangsstadium;

Fig.2:

eine Teilquerschnittsansicht der Vorrichtung von Fig. 1 beim Herstellen eines Fahrzeugrades in einem Endstadium;

Fig. 3:

eine Teilquerschnittsansicht einer weiteren Vorrichtung beim Herstellen eines Fahrzeugrades in einem Anfangsstadium und

Fig. 4:

eine Teilquerschnittsansicht der Vorrichtung von Fig. 3 beim Herstellen eines Fahrzeugrades in einem Endstadium.

The invention is described below with reference to preferred exemplary embodiments, which are shown schematically in the drawings. The drawings show:

Fig. 1:

a partial cross-sectional view of a device according to the invention when molding a vehicle wheel in an initial stage;

Fig. 2:

a partial cross-sectional view of the device of Fig. 1 in the manufacture of a vehicle wheel in a final stage;

Fig. 3:

a partial cross-sectional view of another device in the manufacture of a vehicle wheel in an initial stage and

Fig. 4:

a partial cross-sectional view of the device of Fig. 3 in the manufacture of a vehicle wheel in a final stage.

A device 10 according to the invention for pressure rolling Fig. 1 has a spindle 12 driven in rotation via a drive, not shown. The spindle 12 rotates about a central axis of rotation 13, which runs horizontally in the illustrated example. In the same way, the spindle 12 can be directed vertically with the axis of rotation 13, a workpiece 5 then resting on the spindle 12 or being clamped on an overhead spindle 12 in the case of a hanging spindle arrangement.

Via a plate-shaped clamping device 14 with axially acting clamping claws 16 attached to the spindle 12, a workpiece 5 can be connected to the spindle 12 in a detachable and rotationally fixed manner and centrally to the axis of rotation 13. The workpiece 5 is a preform of a vehicle wheel in the illustrated embodiment. The preform is preferably made from a metal material by casting or forging manufactured. The rotationally symmetrical workpiece 5 has an essentially radially running hub area 6 with a central opening 4 and an essentially axially extending drum-shaped jacket area 7. With the clamping claws 16, the workpiece 5 is fastened on one side on its outer circumference to the spindle 12.

After clamping, the spindle 12 is set in rotation with the workpiece 5. Preferably three outer rollers 20, of which only one outer roller 20 is shown, are fed radially to the outside of the jacket region 7 of the workpiece 5 by means of external supports, not shown. At the same time, an inner support 40 with three inner rollers 30, which are offset by 120 ° to one another, is fed into a central free space within the drum-shaped jacket region 7. The inner rollers 30 are initially placed adjacent to the radial hub area 6 on an inside of the jacket area 7.

The inner support 40 has a central and conical center support 42, on the outside of which linear guides 44 for slides 46 are arranged. Roll holders 48 are pivotably mounted on the linearly movable carriage 46. The inner rollers 30 are rotatably supported in the pot-like roller holders 48 via roller bearings. The inner rollers 30 can be pivoted via the pivotable roller holder 48 during the pressure rolling process and can be moved radially and / or axially by means of the slide 46 and the inner support 40. In a corresponding manner, the outer rollers 20 can be pivoted on an external support (not shown) and can be mounted so that they can move radially and axially.

The outer roller 20 and the inner roller 30 are moved via a CNC control and actuators, not shown, based on stored data for shaping the desired workpiece 5 Fig. 2 it can be seen that the jacket region 7 of the workpiece 5 can be formed into a rim bed with a hump 8, which represents a thickening in the wall thickness profile of the jacket region 7. The final-shaped jacket area 7 is elongated relative to the jacket area 7 of the starting workpiece 5 and thinned with respect to the wall thickness. Almost any external contour and an internal contour can be generated with the device 10 according to the invention.

The second embodiment according to the Figures 3 and 4th corresponds essentially to the structure of the first device 10 according to the invention according to FIGS Figures 1 and 2nd .

In contrast to the first embodiment, the device 10 according to FIG Fig. 3 a modified inner roller 30 with an annular radial projection 32 and an abutment section 34 adjacent in the front region is provided. The radially protruding radial projection 32 on the inner roller 30 can be used to form an inner contour along the inside of a jacket region 7 of the workpiece 5 in cooperation with the radially externally acting outer roller 20. The front abutment portion 34 can be used to form a rim flange at the free end of the molded rim well, as shown in FIG Fig. 4 is shown. The abutment section 34 can in particular be designed as a negative shape of the inner contour of the rim flange and for absorbing the forming forces of the outer roller 20. In a corresponding manner, different outer rollers 20 with an adapted outer contour can be delivered to the jacket area 7. In particular, an outer roller 20 can have an outer contour corresponding to the desired shape of the rim flange to be shaped.

In addition, in the second embodiment according to FIGS Figures 3 and 4th for clamping the workpiece 5 in addition to the previously described clamping device 14 with axially movable clamping claws 16 for clamping the workpiece 5 on the radial outside, an axially movable counter-holder 18 is also provided. Particularly after an initial contouring of the jacket area 7, the counter-holder 18 can be pressed axially into the central free space of the drum-shaped jacket area 7 against the hub area 6 of the workpiece 5. As a result, additional axial clamping and centering of the workpiece can take place at least during an end stage of the pressure rolling process. The counterholder 18 can have a plate-shaped contact element 19 which is adapted to a contouring of the hub area 6 of the workpiece 5.

With the device 10 according to the invention and the method that can be carried out thereon, workpieces 5 with a large variety of shapes of a wall area 7 can be formed without conversion measures.

For the first time, this process enables repeated, step-by-step pressure rolling until the final end geometry or complete structural change has been achieved.

Preference is given to pressure casting cast wheels at temperatures up to 400 ° C. Heat treatment of the wheels can immediately follow the spinning process.

In addition, the process can also be used for the cold forming of aluminum forged wheels, as well as for steel wheels.

The use of a special programming interface or the use of offline programming support software is also preferred in order to be able to create the complex programs more easily and quickly, and to check and optimize them before use by simulation.

Alternatively, a combination of flexible inner rollers with a partially acting short mandrel is also possible.

Claims (14)

1. Method for spin forming, in particular for spin forming a vehicle wheel,
   wherein a workpiece (5) is set in rotation about an axis of rotation (13) by means of a spindle (12), and at least one outer roller (20) is positioned by means of an outer support at an outer side of the workpiece (5),
   wherein, with material thinning, an axially extending lateral region (7) of the workpiece (5) is shaped, and

   - wherein at least one inner roller (30) is positioned at an inner side of the workpiece (5) by means of an inner support (40), which is displaceable axially and radially relative to the axis of rotation (13) independently of the outer support,

   - at least one outer roller (20) is positioned, wherein an inner roller (30) is associated with each outer roller (20), and

   - a defined shaping gap is formed between the outer roller (20) and the associated inner roller (30),

   characterized in that
   the inner support (40) with the inner roller (30) and the outer support with the outer roller (20) are displaced individually by means of a CNC control unit when shaping the lateral region (7),
   wherein at the lateral region (7) a defined wall thickness profile with different wall thicknesses between the at least one outer roller (20) and the at least inner roller (30) is formed.
2. Method according to claim 1
   characterized in that
   the at least one inner roller (30) and/or the at least one outer roller (20) are positioned with an angle to the axis of rotation (13).
3. Method according to claim 1 or 2,
   characterized in that
   the workpiece (5) is clamped on the spindle (12), wherein a free space remains in a central region radially inside the lateral region (7).
4. Method according to any one of claims 1 to 3,
   characterized in that
   clamping of the workpiece (5) takes place at a part-region of the outer circumference.
5. Method according to any one of claims 1 to 4,
   characterized in that
   the workpiece (5) is provided with a clamping and/or centering aid before spin forming.
6. Method according to claim 5,
   characterized in that
   the clamping and/or centering aid is removed from the workpiece (5) after spin forming.
7. Method according to any one of claims 1 to 6,
   characterized in that
   an internal clamping device (14) is provided, by which a hub region (6) of the workpiece (5) is covered.
8. Method according to any one of claims 1 to 7,
   characterized in that
   the lateral region (7) is shaped as a rim base of a vehicle wheel with at least one hump (8), which is formed as a thickening in the wall thickness profile.
9. Method according to claim 8,
   characterized in that
   in order to form a hump (8) and/or flange regions, the inner roller (30) and the outer roller (20) are simultaneously displaced relative to one another in the radial and in the axial direction.
10. Device for spin forming by a method according to any one of claims 1 to 9, having

    - a spindle (12) which can be driven in rotation via a drive about an axis of rotation (13) and is configured to hold a workpiece (5),

    - at least one outer roller (20), which is rotatably mounted on an outer support, which is displaceable axially and radially relative to the axis of rotation (13) in order to position it at the workpiece (5), and

    - at least one inner roller (30), which can be positioned at an inner side of the workpiece (5) opposite the outer roller (20), and

    - wherein the at least one inner roller (30) is rotatably mounted on an inner support (40), which is mounted to be displaceable axially and radially relative to the axis of rotation (13) independently of the outer support,

    - a CNC control unit for individually displacing the at least one inner support (40) with the inner roller (30) and the at least one outer support with the outer roller (20),

    characterized in that

    - the CNC control unit is adapted for individually displacing the at least one inner support (40) with the inner roller (30) and the at least one outer support with the outer roller (20) when shaping one workpiece (5), in particular a vehicle wheel, according to a method according to any one of the claims 1 to 9, wherein the at least one inner roller (30) and the at least one outer roller (20) can be displaced radially and axially to each other when shaping the lateral region (7).
11. Device according to claim 10,
    characterized in that
    several inner rollers (30) and outer rollers (20) are provided, each inner roller (30) being associated to one outer roller (20).
12. Device according to claim 10 or 11,
    characterized in that
    a clamping device (14) for clamping the workpiece (5) is arranged on the spindle (12), wherein a free space remains in a central region radially inside the lateral region (7) of the workpiece (5).
13. Device according to any one of the claims 10 to 12,
    characterized in that
    there is provided a control device having a data memory, in which data sets for the displacement of the inner roller (30) and the outer roller (40) for different workpiece shapes are stored.
14. Device according to any one of claims 10 to 13,
    characterized in that
    at least one of the rollers (20, 30) is provided with an auxiliary drive for driving the roller (20, 30) in rotation.

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