Wheel disc for a vehicle wheel, manufacturing method and vehicle wheel

Abstract

The present invention relates to a wheel disc for vehicle wheels, in particular for passenger cars, manufactured by flow forming, which has an elongated disc transition surface 20, which is subsequently provided with ventilation holes 30 and a radially outer disc edge. All ventilation holes 30 are located in the transition surface 20 and are attached by punching or cutting. In order to improve the competitiveness of vehicle wheels made of steel or of other materials, in particular suitable for cold forming, compared to cast vehicle wheels made of aluminum, according to the invention the transition surface (20) is provided with some changes in the material thickness generated during flow forming by the displacement of the tool, which, viewed radially, results in a wave structure on the surface facing the tool during flow forming. The surface provided with the wave structure can in particular form the invisible inside of the vehicle wheel, but can also form the visible side. Furthermore, the opposite side can also be provided with a wave structure.

Description

[Technical field]

[0001] The invention relates to a vehicle wheel, in particular a wheel disc for passenger cars, having a wheel disc body manufactured from a metal preform by flow forming with a tool against a spin chuck, the wheel disc body having a radially inner connecting flange provided with several bolt holes and a central hub hole, an elongated disc transition surface subsequently provided with ventilation holes and a radially outer disc edge, the transition surface having a material thickness which varies at least partially several times when viewed radially, all ventilation holes being attached by punching or cutting between a first inner ring part generated during flow forming, arranged between the connecting flange and the transition surface, and a second outer ring part generated during flow forming, arranged between the transition surface and the disc edge. The invention further relates to a method for manufacturing a wheel disc for a vehicle wheel, in particular for a passenger car, comprising the steps of: a) flow forming a metal preform on a flow forming machine against a spin chuck by means of at least one spinning roller as a tool; b) generating in the flow forming step a connection flange, a disc transition surface and a disc edge on the wheel disc body, wherein the transition surface in the flow forming step is at least partially provided with a material thickness that varies several times when viewed in the radial direction; c) generating a first inner ring portion between the connection flange and the transition surface and a second outer ring portion between the transition surface and the disc edge; and d) punching or cutting air holes in a subsequent processing step in the transition surface. [Background technology]

[0002] Metallic vehicle wheels can be produced in various ways. Aluminum wheels are often produced as cast wheels, partly also as integral cast wheels with wheel disc and wheel rim. For steel wheels, on the other hand, it is customary to first produce the wheel disc and the wheel rim on separate production lines, which are then connected to each other in a suitable manner, for example by a welded joint. Many methods exist as manufacturing methods for the wheel disc, on the one hand, and for the wheel rim, on the other hand. The present invention is primarily directed to a steel wheel disc and a manufacturing method for such a steel wheel disc, but also to a correspondingly assembled vehicle wheel consisting of a wheel disc and a wheel rim connected to the wheel disc.

[0003] In principle, it is known to use the flow forming method for the manufacture of wheel discs from metal preforms. Here, the starting blank is clamped, usually in the region of the hub connection flange, on the spin chuck of a flow forming machine, after which, while the spin chuck rotates, the preform is deformed into the specified or desired final shape for the wheel disc using a suitable tool, in particular a rotating spinning roller. By way of example, reference is made to DE 2156551 A1. Wheel discs manufactured accordingly have a relatively smooth surface, in particular on the side facing the spin chuck, and can also have a material thickness that, due to the stretching achieved during flow forming, decreases uniformly in the radial direction, for example from the inside to the outside.

[0004] In the manufacture of wheel rims it is commonly known to provide a reduced material thickness in certain areas of the wheel rim by stretching or thinning those areas.

[0005] A method for manufacturing a wheel disc produced by flow forming, and in particular a wheel disc for a commercial vehicle wheel, is known from WO 2015 / 159231 A1, in which a local elevation is provided in the spin chuck for realizing a local change in the material thickness in the wheel disc or in the wheel disc preform, which generates a corresponding local change in the material thickness of the wheel disc during the flow forming of the wheel disc. The change realized in the material thickness is only local, which is why different material thicknesses result in the circumferential direction on a certain pitch circle. The specific task of WO 2015 / 159231 A1 is to realize a material saving in the manufacture of the corresponding vehicle wheel, with the advantage of a weight reduction, which can be realized, for example, by air vents in low stress areas or areas that are removed later. Therefore, in this prior art, the emphasis is on wheel discs for commercial vehicle wheels, in which the air vents are punched out later and a significant minimization of the material thickness is already performed in advance during the manufacture of the wheel disc. This allows a wheel disc of a particular wheel size to be manufactured from a starting blank having a smaller diameter.The material thickness change is realized only where a corresponding ridge or recess is provided for the spin chuck.

[0006] Aluminum wheels manufactured using casting methods offer a variety of design options. However, cast aluminum wheels have structural disadvantages due to the significant amount of energy required for the manufacture of aluminum wheels. The same applies to forged aluminum wheels. Steel wheels or vehicle wheels manufactured from metal blanks by deformation may have a better overall energy balance in this respect, but have the disadvantage of fewer design options. Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to improve the competitiveness of vehicle wheels made of steel or of other materials, particularly suitable for cold forming, in comparison with cast vehicle wheels made of aluminium, in particular of steel wheel discs, i.e. by means of an economical and competitive manufacturing method for the wheel discs, which improves the design freedom in positioning the wheel discs as well as the air vents, while at the same time providing high stiffness and load-bearing capacity of the wheel disc. [Means for solving the problem]

[0008] This object is realized in its widest application by a wheel disc, characterized in that the transition surface between the inner and outer ring parts (18) has several changes in material thickness produced during flow forming by the displacement of the tool, which, viewed in the radial direction, results in a wave structure on the surface facing the tool during flow forming. Due to the material thickness which varies several times in the radial direction, while, viewed in the circumferential direction, the material thickness remains constant or almost constant on the pitch circle in the wave structure, the wheel disc with the wave structure produced during flow forming can be better and more variably adapted by suitable positioning of the wave structure to the expected loads that arise when a vehicle wheel provided with such a wheel disc is mounted on a vehicle. The wave structure caused by the change in material thickness allows to obtain a larger material thickness in areas subjected to higher stresses than in areas subjected to lower stresses, the change in material thickness being produced by moving the tool relative to the spin chuck, which in this respect can also be repeatedly adapted and changed at low cost and with a high degree of design freedom.

[0009] According to a first advantageous design, the outer disk edge of the wheel disk receives or has an edge that is or can be formed as a rim flange during flow forming or can be connected to the wheel rim so that the rear side of the preform facing the spin chuck can be used as the viewing side of the wheel disk by flow forming into a wheel disk. The corresponding wheel disk therefore has a wave structure that is exclusively created by moving the tool, i.e. on the rear or inner side of the subsequent wheel disk, away from the spin chuck.

[0010] In principle, it is particularly advantageous in a wheel disc according to the invention if the transition surface, at least on the upper side of the preform facing the tool during flow forming, on the manufactured disc of the wheel receives or has a wave structure with more than three crests and troughs therebetween, even better more than five crests and troughs therebetween, in particular more than seven troughs and crests therebetween. Depending on the size of the wheel disc, a much larger number of troughs and crests can be generated or present on the transition surface, for example even 14 to 20 (or more) changes between trough and crest, and furthermore one or more troughs and / or crests can also be provided or generated in other areas of the wheel disc, in particular in the radially inner or radially outer ring portion.

[0011] Preferably, most or all of the crests and troughs have a radius of curvature, and more preferably adjacent crests and troughs have different radii of curvature and / or the trough has a larger radius of curvature than the crest. However, individual troughs and crests may also have radii of curvature equal to each other. All radii of curvature may be equal to each other, even if a transition region with troughs and crests having different radii of curvature provides a clearly better match to the expected vehicle wheel loads. The size of the radii of curvature of the troughs may preferably increase in the radial direction from the radially inner to the radially outer.

[0012] Due to an alternative or additional design of the wheel disc, the rear transition surface facing the spin chuck during flow forming can have, at least in part, a non-uniform wavy surface or wave structure, as viewed in the radial direction, which can consist of only wave troughs generating thickness variations or can also have alternating wave troughs and wave crests, which respectively result in different material thicknesses.

[0013] In all of the above-mentioned designs of the wheel disc, it is possible or particularly advantageous for the vent holes in the transition surface to have at least two different or differently arranged hole profiles, which together form a pattern area that is repeated at least once more in the circumferential direction, preferably at least three times. Unlike conventional vehicle wheels with hole profiles that are regularly repeated in the circumferential direction, the wheel disc according to the invention can have these hole profiles in such a way that the hole pattern, which is generated with several different hole profiles that are combined with each other, is repeated several times in the circumferential direction. This, in combination with the wave structure of the wheel disc in the transition surface, results in a greatly improved load-bearing capacity and stiffness of the vehicle wheel, the regularity of the pattern area preventing additional imbalances. It is particularly advantageous if each pattern area has several vent holes with different outer profiles and intermediate struts between the vent holes with a varying material thickness. The variation in material thickness of the intermediate struts between the vent holes is here caused by the wave structure that the wheel disc according to the invention undergoes during flow forming even before the vent holes are punched or cut. The intermediate strut then allows for a further improvement of the wheel disc, or of the vehicle wheel on which it is provided, with regard to the loads occurring during driving.

[0014] Alternatively or additionally, each pattern area can have at least one partial section partially forming a transition surface, which section is adjacent to the inner ring part, is not interrupted by the vents and has a material thickness that varies in the radial direction, which creates, in the circumferential direction, intermediate areas with vents and more or less clear areas without vents, which can not only realize any style but at the same time, together with the wave structure, further improve the load-bearing capacity and stiffness of the wheel disc.

[0015] For each design of the wheel disc according to the invention, the ventilation holes of the transition surface can have at least two different hole profiles or differently arranged hole profiles, and bridge webs with a radially varying material thickness are arranged between adjacent hole profiles, where the variation in material thickness of the bridge webs is also produced by a wave structure, and the wheel disc is given according to the invention by deformation during flow forming.

[0016] There are various design options for the bridge webs, whose geometry and path are actually determined by punching or cutting the air holes. According to one design, the bridge webs can have at least partially constant width over the partial extension length. Alternatively or additionally, several bridge webs can run parallel to one another or bend towards one another and / or cross one another and / or the bridge webs can be designed as rounded curves, straight struts and / or asymmetric struts. Due to the respective geometry and path of the bridge webs as the remaining area between the air holes, a divergent basic structure is realized between the air holes and at the same time a divergent basic structure between the hub connection flange and the outer disk edge, whereby the bending stiffness and the load-bearing capacity are improved with a wave structure that allows this as a priority.

[0017] The arrangement of bridge webs preferably satisfies the requirement of a circumferentially repeating hole pattern or pattern area, however, each hole pattern itself can be configured irregularly to create a bioengineered support structure, the favorable effect of which on load-bearing capacity and bending stiffness is further improved due to the change in material thickness provided in accordance with the present invention during deformation.

[0018] In designs with bridge webs, several vent holes formed by different hole contours are particularly advantageous when they form a hole window group together with the associated bridge web, the group including window areas having peripheral contours corresponding to round holes, triangular holes with rounded corners, or square holes with rounded corners.

[0019] In addition to the wavy structure of the wheel disc transition surface, it may be advantageous if at least the inner ring portion has a wavy structure with at least one material thickness that varies radially, preferably with only one wave trough on the surface that faces the tool during flow forming, the inner ring portion being preferably integrated into the transition surface via a transition curve that is provided with a crest. In this design, it is particularly advantageous if the inner ring portion has a wavy structure with one wave trough or two wave troughs between the connection flange and the transition surface.

[0020] Wheel discs with a wave structure can primarily form so-called semi-full-surface wheels and can be combined accordingly with a wheel rim, which then also has an outer rim flange in the usual way. However, it is particularly preferred that the wheel disc is designed as a full-surface wheel disc with a rim flange, and more preferably the outer ring part of the wheel disc receives or has a ring zone with a surface that is planar on the viewing side, preferably aligned perpendicular to the rotation axis of the wheel disc or vehicle wheel, and / or has a radial length in the radial direction of at least 25 mm, 28 mm, 32 mm or 35 mm, depending on the wheel size, and / or has a radial length that is greater than 1 / 20 of the wheel disc diameter, particularly preferably greater than 1 / 16 or 1 / 15 of the wheel disc diameter, depending on the wheel size. The ring zone, which is already evident on the wheel disc, can improve the aerodynamic properties of a vehicle wheel equipped with such a wheel disc due to its extent in the radial direction, since it can minimize the turbulence in the radial outer zone of the vehicle wheel. Here too, depending on the possible design, the ring zone can have at least one crest, preferably both a crest and a trough, but it can also be designed so that there is no change in material thickness and therefore has a constant thickness when viewed in the radial direction.

[0021] The above mentioned object is also achieved by a method according to the invention, characterized in that the transition surface between the inner and outer ring parts undergoes several changes in the material thickness produced during flow forming by the displacement of the tool, which, viewed in radial direction, results in a wave-like structure on the surface facing the tool during flow forming, and in a subsequent method step all ventilation holes are installed by punching or cutting at least two mutually different hole contours or differently arranged hole contours between the inner and outer ring parts, the arrangement of the ventilation holes and the remaining basic structure on the wheel disc body form a pattern area on the transition surface, which area is repeated in the circumferential direction at least once more, preferably at least three times.

[0022] The method according to the invention therefore combines the manufacture of a wheel disc with a wave structure and the placement or formation of air vents using a wave structure with different hole contours, and therefore pattern areas.

[0023] An advantageous variant of the method provides that several ventilation holes having mutually different outer contours are provided in each pattern area, and intermediate struts having a varying material thickness are brought between the ventilation holes, so that adjacent to the inner ring portion, at least one partial section is generated which is not blocked by the ventilation holes and which partially has a varying material thickness.

[0024] In order to be able to form in a particularly advantageous way, as a result of the method according to the invention, a wheel disc with a constant or almost constant material thickness in the circumferential direction and with a corrugated structure varying several times in the radial direction and to adapt it to the loads, the control of the method during production can be carried out in such a way that the pattern areas of the ventilation holes, the bridge webs or intermediate struts and the respective part sections are determined iteratively in several steps, in a first step the basic pattern area with the ventilation hole contour is developed from the parameters of stiffness and load-bearing capacity required for the vehicle wheel, the contour is analyzed in at least one further step for feasibility, in a further step, before the production of the wheel disc, the arrangement and contour of the ventilation holes as well as the changes in material thickness between the ring section and the position, shape and alignment of the bridge webs or intermediate webs resulting in the corrugated structure are optimized with respect to the vehicle wheel weight and stiffness. Such an iterative process allows the production of a wheel disc for a vehicle wheel which leaves maximum design freedom with respect to styling and at the same time is optimized for the expected loads.

[0025] The wheel disc according to the invention or the wheel disc produced according to the invention by flow forming in combination with the hole contours arranged in the patterned area is used in particular for vehicle wheels for passenger cars. It is also particularly advantageous here if the wheel disc is connected to the wheel rim in such a way that the front side visible in the assembled state of the vehicle wheel on the vehicle consists of the visible side of the lateral part of the wheel disc body which is pressed against the spin chuck during flow forming or in the flow forming step. The wave structure is then preferably exclusively on the inside of the wheel disc in the wheel rim and thus faces the vehicle and the vehicle brakes. It is also particularly advantageous in the case of vehicle wheels, in which the wheel disc forms a fully formed rim flange, the rim part is connected to the rear side of the wheel disc, preferably in the region of the planar outer ring part, so that if the wheel disc is designed for a full-surface vehicle wheel, it is preferably offset radially outwards with respect to the outer transition curve to the outer ring part. Here too, the aerodynamics of the vehicle wheel can be improved if the wheel disc on the outer ring portion has a ring zone with a flat surface, preferably aligned perpendicular to the axis of rotation of the vehicle wheel, where the ring zone has a radial length of a few centimeters, preferably greater than at least 25 mm, 28 mm or 32 mm depending on the wheel diameter, or even greater than at least 35 mm in the radial direction, and / or if the ring zone has a radial length greater than 1 / 20 of the wheel disc diameter, preferably greater than 1 / 16 of the wheel disc diameter, or more preferably greater than 1 / 15 of the wheel disc diameter. The radial length of the flat outer ring portion may be in the range of about 10% to 30% of the total radial length of the inner ring portion, the transition surface and the outer ring portion together.

[0026] Further variants and advantages of the wheel disc according to the invention or of a vehicle wheel comprising a wheel disc according to the invention result from the drawings and the following description of the embodiment variants of the wheel disc and / or vehicle wheel shown in the drawings. [Brief description of the drawings]

[0027] [Figure 1] 3 is a cross-sectional view of a vehicle wheel according to the invention, which has a wheel disc according to the invention according to a variant of the first embodiment, in addition to a diagrammatically shown wheel hub cap and a diagrammatically shown brake profile. [Diagram 2] 1 is a schematic and highly simplified view of the basic procedure for making a wheel disc according to the invention; [Diagram 3] FIG. 2 is a cross-sectional view similar to FIG. 1, but without the hubcap and brake profile. [Figure 4] 4 is a cross-sectional profile of a wheel disc according to the invention according to a variant of the embodiment according to FIGS. 1 and 3, in an enlarged cross-sectional view. [Figure 5A] 2 is the vehicle wheel of FIG. 1 in a front perspective view. [Figure 5B] 2 is the vehicle wheel of FIG. 1 in a rear perspective view. [Figure 6A] 4 is a wheel disc for a vehicle wheel according to a variant of the second embodiment, in a plan view. [Figure 6B] 1 is a wheel disc for a vehicle wheel according to a variant of the third embodiment, in a plan view; [Figure 6C] 13 is a wheel disc for a vehicle wheel according to a variant of the fourth embodiment, in a plan view. [Figure 7] 5 is a cross-sectional profile of a wheel disc according to the invention according to a variant of the fifth embodiment, similar to FIG. 4, in an enlarged cross-sectional view. [Figure 8A] 1 is a vehicle wheel having a wheel disc according to the invention according to a variant of the fifth embodiment, seen from the front, in a perspective view. [Figure 8B] 5 is a vehicle wheel according to a variant of the fifth embodiment seen from the rear in a perspective view. [Figure 9] 9 is a cross-sectional profile of a wheel disc according to the invention according to a variant of the sixth embodiment, similar to FIG. 8, in an enlarged cross-sectional view. [Figure 10A] 13 is a vehicle wheel with a wheel disc according to the invention according to a variant of the sixth embodiment, seen from the front, in a perspective view. [Figure 10B] 13 shows a vehicle wheel according to a variant of the sixth embodiment, seen from the rear, in a perspective view. [Figure 11] 13 is a schematic highly simplified cross-sectional profile of a vehicle wheel in a full face embodiment having a wheel disc according to a variant of the seventh embodiment, in an enlarged cross-sectional view. [Figure 12] 13 is a schematic highly simplified cross-sectional profile of a vehicle wheel of a semi-full embodiment having a wheel disc according to a variant of the eighth embodiment, in an enlarged cross-sectional view. [Figure 13] FIG. 13 is a front view of a wheel disc according to the invention according to a variant of the ninth embodiment, having bridge webs between the air holes in the air hole pattern area which are repeated several times. [Figure 14] FIG. 13 is an enlarged view of an area of ​​a vent hole pattern having straight bridge webs crossing each other between the vent holes. [Figure 15A] FIG. 13 is a close-up view of an area of ​​a vent hole pattern having straight and curved bridge webs between the vent holes. [Figure 15B] FIG. 13 is a close-up view of an area of ​​a vent pattern having straight, angled bridge webs between the vent holes. [Figure 15C] FIG. 13 is a close-up view of an area of ​​a vent hole pattern having straight and curved bridge webs between the vent holes. [Figure 15D] FIG. 13 is a close-up view of an area of ​​a vent pattern having serpentine bridge webs between the vent holes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] In figures 1 and 3, the reference number 1 denotes a vehicle wheel, in particular for passenger cars. It is an assembled vehicle wheel 1 consisting of a rim part 2 and a wheel disc 10. Preferably, both the rim part 2 and the wheel disc 10 consist of steel and both parts are connected to each other by a welded joint. However, the wheel disc can also consist of other formable materials, in particular cold-formable materials, including, for example, suitable light metal materials. In the case of a composite vehicle wheel, the rim can also consist of a different material than the wheel disc, for example of a light metal, the wheel disc being made of steel. The vehicle wheel 1 has a wheel axis 3 which coincides with the rotation axis of the wheel rim 2 and the wheel disc 10. The structural design of the wheel rim 2 is essentially irrelevant to the present invention. The vehicle wheel 1 forms a so-called full-surface wheel, since the wheel disc 10 already has an integral outer rim flange 21 which, at least in Europe, is usually part of the wheel rim in passenger cars. The wheel disc 10 is therefore designed in a full-surface shape and the wheel rim 2 is accordingly designed shortened without a rim flange. Also shown in FIG. 1 is a hub cap or centre cap 5 which can be used to cover a central inner connecting flange 11 on the wheel disc 10 which is common in vehicle wheels.

[0029] The vehicle wheel 1 is fastened in particular via a connection flange 11 of the wheel disc 10 to a wheel hub of a vehicle, such as a passenger car. The hub connection flange 11 therefore further has a central hub hole 12 and, on a pitch circle around the hub hole 12, several bolt holes 14 through which wheel bolts pass which are screwed into the vehicle hub. Passenger car wheels usually have 3 to 6 bolt holes. The substantially flat connection flange 11 of the wheel disc 10 merges radially outwardly into a (wheel) disc transition surface 20. The disc transition surface 20 curves outwardly and ends at the edge of the wheel disc 10 at a disc edge 21, which at the same time forms a rim flange due to the design of the vehicle wheel 1 as a full surface wheel. Correspondingly, the tire mounted on the vehicle wheel 1 is supported and lies radially inwardly on the wheel rim 2 between the disc edge 21, which at the same time forms a rim flange, and the inner rim flange 4, which is integrally formed on the wheel rim 2, as symbolically indicated by the double arrow 6 in FIG. 1. In principle, the length of the double arrow 6 corresponds to the tire width of a suitable tire. The designations "inner", "lower" or "rear" on the vehicle wheel usually refer to the side that is not visible in the mounting state of the vehicle wheel on the vehicle, while "outer" or "front" indicates the visible side. On the other hand, "radially inner" and "radially outer" refer to the radial extension starting from the wheel axis 3.

[0030] The curvature of the disc transition surface 20 of the wheel disc 10 is then determined in particular by the brake profile contour shown by the line 7, since the vehicle wheel must maintain a distance from this brake profile contour specified for the vehicle. During the manufacture of the wheel disc in a subsequent method step, the disc transition surface 20 is further provided with ventilation holes, which are generally indicated by the reference number 30 in figures 1 and 3. The ventilation holes 30 serve several purposes: they ensure weight reduction, allow sufficient cooling of the brakes and at the same time affect the appearance ("styling") of the vehicle wheel. The ventilation holes 30 are here arranged between the inner ring portion 15 and the outer ring portion 18. The range between the inner ring portion 15 and the outer ring portion 18 simultaneously forms the disc transition surface 20, and further a first transition curve 16 between the inner ring portion 15 and the radially inner starting point of the transition surface 20 and a second outer transition curve 17 between the radially outer end point of the transition surface 20 and the radially outer ring portion 18 are formed. The angles of transition curve 16 and transition curve 17 are selected such that transition surface 20 extends at an angle of approximately 12° to 25°, and preferably at an angle of approximately 16° to 18° relative to hub connection flange 11, as shown in the exemplary embodiment shown.

[0031] A special feature of the wheel disc 10 according to the invention, and also to the extent of all vehicle wheels 1 with which the wheel disc 10 is provided, lies in particular in the cross-sectional profiling of the transition surface 20 and in particular in the mounting and design options for the ventilation holes 30 that are made possible thereby. In figures 1 and 3 it has already been shown that the disc transition surface 20 on the inner or rear side 24 of the wheel disc 10 has a wave structure resulting in a change in material thickness, which was generated during the manufacture of the wheel disc 10 by flow forming. This wave structure forms one of the essential features for the invention, since the wave structure extends constantly concentrically along the entire circumference of the disc transition surface 20 and provides, in particular at the disc transition surface 20, when viewed in the radial direction, some changes in material thickness.

[0032] FIG. 2 is referred to in order to explain the basic principle of the flow forming method used during the manufacture of the wheel disc 10 according to the invention. FIG. 2 shows the procedure very diagrammatically. A metal preform, for example a round circuit board, is usually pre-contoured by a suitable pre-treatment step, if necessary by the formation of a central hub connection area with a central hole, and is then flow-pressed against the surface contour of a spin chuck 41, as shown, by a spinning roller, preferably consisting of a rotating spinning roller 40. Accordingly, the pre-contoured preform is held in place with a hold-down tool (not shown) here, preferably in the central inner area which will later form the hub connection flange 11. Thus, at the hub connection flange 11, the preform, as well as the subsequent wheel disc, can continue to have substantially the initial thickness of the preform, which for passenger cars is usually about 3 mm to 7 mm. During the subsequent flow forming, as shown, the spin chuck 41 rotates together with the preform on a suitable flow forming machine. Meanwhile, the tool 40 moves radially outward along the surface contour of the spin chuck 41, as indicated by the arrow B, and at the same time the distance between the spinning roller 40 and the spin chuck 41 can be adjusted, as indicated by the arrow V. The spatial surface contour of the spin chuck 41 corresponds to the spatial contour of the subsequent wheel disc 10. By adjusting the spinning roller 40 in the direction of the arrow V, the material thickness of the wheel disc 10 is provided with a wave structure, which is only shown in FIG. 2, in particular at the disc transition surface 20, and the maximum thinning of the area of ​​the wave structure with a minimum material thickness can be up to 40% of the initial material thickness of the preform. The wheel disc 10 that can be used to design a full-surface vehicle wheel is here designed completely, i.e. including the rim flange 21, and furthermore completely designed in that the free end of the preform is angled around the spin chuck 41 and pressed by the spinning roller 40.In this manufacturing method, the surface of the wheel disc 10 facing the spin chuck 41 obtains a smooth surface, which is a surface of even higher optical quality, and can therefore be used directly as a visible surface of the vehicle wheel. On the other hand, the wave structure is produced in the spin chuck 41 shown in Fig. 1 only on the surface or side facing the spinning roller 40 as a tool, which forms the rear or inner side of the wheel disc 10, since the spinning roller 40 as a tool is in the invisible inner area of ​​the vehicle wheel. The disc transition surface 20 is stretched at the same time by the thinning of the material thickness caused by the flow forming / flow pressure rolling and the wave structure.

[0033] For a better explanation of the wavy structure, reference is now made to Figures 4, 5A and 5B, which show, by way of example, the cross-sectional and spatial profiles of the wheel disc 10 in a schematic enlarged view. The wheel disc 10 is shown here only in half. As usual, the hub connection flange 11 has the hub holes 12 as well as a raised ring area 13 for the bolt holes 14, each designed as a hump. In its radially outermost area, the hub connection flange 11 merges into a radially inner ring portion 15, which in the exemplary embodiment shown runs pot-shaped relative to the hub connection flange 11 and bends obliquely upwards or forwards. The ring portion 15 extends substantially between the radially outermost support area of ​​the hub connection flange 11 on the hub, as shown at position a in Figure 4, and the start of a radially inner transition curve 16, which extends between the radially inner position b and the radially outer position c in Figure 4. This transition curve 16 is adjoined by a disk transition surface 20, whose wave structure is designed with (at least) a plurality of changes in material thickness according to the invention during flow forming. In the exemplary embodiment shown, the disk transition surface 20 extends at a substantially constant oblique angle from position c, and thus from the radially outer end area of ​​the inner transition curve 16, to a radially outer transition curve 17 extending between positions d and e in Fig. 4. This transition curve 17 is adjoined by an outer ring portion 18, which here integrally has an outer rim flange 21 which simultaneously forms the radially outer wheel disk end.

[0034] In the exemplary embodiment of FIG. 4, the wheel disc transition surface 20 has a wave-like structure with three wave troughs R5, R7, R9 and four wave crests R4, R6, R8, R10. At the wave troughs R5, R7, R9, the material thickness is the smallest compared to the adjacent zones, and at the wave crests R4, R6, R8, R10, the material thickness is the largest compared to the adjacent zones. In the exemplary embodiment shown, the transition surface 20 has a maximum material thickness at the wave crest R10 and a minimum material thickness at the wave crest R5. This is merely an example, since the number of wave troughs and crests, as well as the position and radius of curvature of the wave trough with the locally smallest material thickness and the wave crest with the largest local material thickness, may vary depending on the wheel size and the expected vehicle wheel load. At the same time, it is understood that the material thickness usually decreases uniformly from the center of the wave crest to the bottom of the wave trough. Therefore, the marking lines for the wave troughs and crests usually indicate in the figures the local position of the wave crest or wave trough and thus the minimum or maximum material thickness. The radially outer transition curve 17 is adjoined by a radially outer ring portion 18, which in the exemplary embodiment according to FIG. 4 extends essentially exactly perpendicular to the wheel axis 3 over a few centimetres, preferably more than 28 mm to 30 mm, preferably more than 35 mm, in particular more than 40 mm, and further has a constant material thickness between positions e and f. The outer ring portion 18 is then integrally formed on the wheel disc and ends radially outwardly at an outer rim flange 21 directly adjacent to position f. The part of the outer ring portion 18 extending perpendicular to the wheel axis forms a ring zone which can have a favourable effect on the overall aerodynamics and in particular can contribute to minimising the air resistance by the vehicle wheel, in particular if the radial length of the ring zone is at least 30 mm, or even at least 35 mm, or at least 1 / 20, more preferably at least 1 / 16 or 1 / 15 of the wheel size, a hubcap extending to the edge of the disc is not necessary. The depth of the offset between the ring zone 18 and the hub connecting surface 11 may be between about 30 mm and 110 mm depending on the wheel diameter as well as the braking profile of the vehicle for which the vehicle wheel is intended.The wheel diameter also determines the radial distance between positions a and f and thus the total radial length of the inner ring portion 15, the outer ring portion 18 and the transition surface 20, which may in particular be in the range of about 120 mm to about 200 mm. The ring zone 18 between positions e and f may then be configured with about 10-30% of the above mentioned radial distance, i.e. the total radial length between positions a and f.

[0035] Here, the radially inner transition curve 16 has a constant radius of curvature R3, and the radially outer transition curve 17 also has a constant radius of curvature R11, the radius of curvature R3 being smaller than the radius of curvature R11, while the material thickness of the transition bend 16 is significantly greater than the material thickness at the transition curve 17. Here, the inner ring portion 15 between positions a and b also has a wave trough R1 and a wave crest R2 generated during flow forming. On the other hand, the ring zone of the outer ring portion 18 has a constant thickness in the exemplary embodiment according to FIG.

[0036] The radii of curvature R5, R7, R9 of the wave bottoms preferably increase radially outward. The radially innermost radius of curvature R5 may be, for example, about 100 mm, the radius of curvature R7 may be 120 mm, and the radius of curvature R9 may be 150 mm. On the other hand, the radii of curvature R4, R6, R8, R10 of the wave bottoms may be identical to each other, may vary between larger and smaller radii, or may further increase radially, respectively. The radii of curvature may be, for example, in the range of 50 mm to 100 mm, but may also be smaller or larger. Generally, the radii of curvature of the wave tops are significantly smaller than the radii of curvature of the wave bottoms. The transition surface 20 may, for example, extend at an angle of about 16° to 18° with respect to the plane of the hub connection flange 11. The ring zone may also be provided with a wave bottom, or the wave bottom in the radially outer curvature curve 17 extends into the ring zone on the outer ring portion 18. The radially innermost radius of curvature R1 of the first wave trough is preferably relatively small, while the radius of curvature R2 of the first wave crest of the inner ring portion 15 is preferably large, especially larger than the radii of curvature of all other wave crests in the transition section 16. The ring portion 15 may subtend an angle of about 40° to 45° with the wheel axis.

[0037] Figures 5A and 5B show a variant of the first embodiment and how a vehicle wheel 1 with a wheel disc 10 contoured accordingly can be provided with ventilation holes. The front view in Figure 5A shows again that the visible side of the vehicle wheel 1, which is formed by the wheel disc 10 on the side of the preform facing the spin chuck during flow forming, has a high-quality smooth surface structure without indentations or grooves and can therefore be directly formed on the visible side of the vehicle wheel 1. On the other hand, the wavy structure produced according to the invention is only on the rear side of the wheel disc 10, as is readily apparent from Figure 5B, which rear side forms together with the vehicle wheel 1 the inside that is not visible in the rim 2. The wavy structure is shown in Figure 5B with concentric circles on the wheel disc of the vehicle wheel 1, exemplified by radii R5, R6, R7, R8 on the rear side of the wheel disc in Figure 5. In a subsequent step, the wheel disc 10 produced accordingly during flow forming is provided with an air vent 30, which has two different hole contours in the wheel disc, namely, on the one hand, an air vent 30 with hole contour 31 and a further air vent 30 with hole contour 32. The air vent 30 with hole contour 31 extends radially over a much larger length than the air vent 30 with hole contour 32. The air vent 30 with hole contour 31 extends, for example, over the entire radial extension range between crests R4 and R10. The basic shape of the hole contour 31 essentially corresponds to a trapezoid with rounded corners. On the other hand, the air vent 30 with hole contour 32 is even more radially outward and extends radially only in the range from crests R8 to R10. The basic shape of the hole contour 32 is essentially a triangle with rounded corners, the base or bottom side of which is radially outward and which extends essentially curvedly on a reference circle. The vent holes 30 having different hole contours 31, 32 can be punched or cut out with a suitable cutting tool. Relatively wide bridge contours or bridge webs remain between the vent holes having hole contours 31, 32, which are provided with reference numerals 41 and 42 in FIG. 5A and connect the outer ring part 18 to the inner ring part 15.Each of these bridge structures 41, 42 does not extend in the radial direction and has a change in material thickness due to the wave structure that guarantees a change in material thickness in the radial direction, which the wheel disc has received at the rear side, and which further leads to an improvement of the entire vehicle wheel in terms of load-bearing capacity and wheel stiffness. The vents with hole contours 31, 32 in Figures 5A, 5B are merely exemplary, since the wave structure substantially increases the variation in terms of the hole contour and the position and size of the vents 30. The vents with hole contours 31, 32 are arranged rotationally symmetrically when viewed in the circumferential direction. Thus, when viewed in the circumferential direction, the vents with hole contour 31 are repeated five times and the vents with hole contour 32 are repeated five times. If the wheel disc is divided into five subdivisions of equal size, each subdivision has a pattern area with a repeating arrangement of the vents with hole contours 31 and 32.

[0038] 6A, 6B, 6C show vehicle wheels with wheel discs, which, as in the previous exemplary embodiment, have a wave structure on the invisible rear side, given a completely different appearance by air vents with different air vent contours. FIG. 6A shows the vehicle wheel 101 in a plan view of the wheel disc 110. As in the previous exemplary embodiment, the wheel disc 110 has, from the radially inner side to the outer side, a hub hole 112, a hub connection flange 111, an inner ring portion 115, a radially further inner transition curve 116, a disc transition surface 120 provided with air vents 130, a radially outer ring portion 118 and an outer rim flange 121 adjacent to the radially outer ring portion 118. The wave structure on the rear side is not shown, but here, for example, can have eight wave crests and seven wave troughs as well. The ventilation holes 130 have nine different hole contours, which are indicated by the reference numbers 131, 132, 133, 134, 135, 136, 137, 138, 139. These are hole contours that have, in part, the same basic shape, but are mirror images of each other. This applies, for example, to the ventilation holes with hole contours 135 and 138, the hole contours 134 and 137, as well as the ventilation holes with hole contours 133-136. The pattern area formed by the ventilation holes 130 with hole contours 131-139 is repeated three times in the direction of rotation, as can be clearly seen by looking at FIG. 6A. The individual hole contours are preferably cut, since this is economically advantageous compared to punching. The very different geometries of the individual hole contours in turn result in a very arbitrary styling, with a relatively large and well-defined partial section 175 remaining of the wheel disc 110 not provided with ventilation holes and directly adjacent to the inner ring part 115. Furthermore, bridge structures remain between the individual vents with the hole contours 131-139 respectively, which structures do not extend in the radial direction but at the same time have a material thickness that varies due to the wave structure at the rear side. These bridge structures also have a surprisingly advantageous effect on the branching between the vents with the hole contours 131-139 in terms of stiffness and load-bearing capacity.

[0039] FIG. 6B shows a third exemplary embodiment of a vehicle wheel 201 according to the invention with a wheel disc 210 with ventilation holes 230, which again consists of ventilation holes with eight different ventilation hole contours 231-238. Here again, for example, ventilation holes with hole contours 237, 238 or 236 and 235 form sets in which the hole contours have the same basic shape, but are arranged mirror-symmetrically with respect to each other. Overall, the hole pattern with hole contours 231-238 is repeated five times in the direction of rotation, and between the individual ventilation holes, different bridge sections or bridge webs remain, whose material thickness varies radially, due to the wave structure that the wheel disc 210 undergoes during flow forming. These bridge structures then ensure a branching of the range of ventilation holes 231-138, leaving also five partial sections 275 further inwards, which do not have ventilation holes.

[0040] FIG. 6C shows a vehicle wheel 301 according to a fourth exemplary embodiment. Here, too, for example, the wheel disc 310 receives a wave-like structure with 11 crests and 10 troughs on the rear side not visible on the vehicle wheel 301 in the assembled state. The vent holes 330 are cut, for example by laser cutting, in the disc transition surface 320, which holes consist of seven different hole contours 331, 332, 333, 334, 335, 336, 337. The vent holes with the hole contours 331-337 form a pattern area that is repeated six times in the circumferential direction. The vent holes with the hole contours 333, 334 or 335, 336 have the same basic shape as each other, but are mirror symmetric. The axis of mirror symmetry can be placed, for example, through the centers of the vent holes 331, 332, and then the vent holes with the hole contour 337 are also assigned per pattern area, half to one pattern area and half to the other pattern area. Even with such a design of the vents with different hole contours 331-337, the rear wave structure ensures an improved stiffness and load-bearing capacity of the vehicle wheel 301. Furthermore, the vehicle wheel 301 forms partial sections 375 around the hub holes 312 and the inner ring portion, respectively, where no vents 330 are provided.

[0041] Formation of the wave structure on the invisible rear side of the wheel disc designs a preferred exemplary embodiment. With regard to improving bending stiffness and load-bearing capacity, the wave structure can also be generated on the front side of the wheel disc 410 during flow forming, as shown diagrammatically in Fig. 7. The wheel disc 410 is also designed for a so-called full-surface vehicle wheel and has, starting from the wheel axis 403, from radially inner to outer side: a hub hole 412, a hub connection flange 411 with a raised bolt hole 414, an inner ring portion 415 extending between positions a and b in Fig. 7, a radially inner transition curve 416 extending between positions b and c in Fig. 7, a wheel disc transition surface 420 extending between positions c and d, a radially outer transition curve 417 between positions d and e, and an outer ring portion 418 extending between positions e and f. The outer ring portion 418 is immediately followed by an outer rim flange 421. However, the outer rim flange 421 cannot be produced during flow forming with the same clamping as the rest of the wheel disc for manufacturing reasons, but must be bent separately in an intermediate step, before or after the vents are attached. During flow forming, the spinning roller acts on the front side of the wheel disc 410, which later forms the visible side, and therefore the upper side in FIG. 7. However, here too, a wave-like structure with several crests R3a, R5a, R7a and troughs R4a, R6a, R8a is generated during flow forming by moving the tool (spinning roller). The radially inner transition curve 416 has a radius R2a and the radially outer transition curve 417 has a radius R9a, which coincide with the crests at the same time. At the crests R3a, R5a, R7a, R9a the wheel disc 410 has a locally greater thickness, while at the troughs R4a, R6a, R8a it has a reduced, smaller material thickness, which may reach up to 60% of the starting stock thickness. In particular at the two transition curves 416, 417 the material thickness can be further reduced, as can the radially inner ring portion 415. The outer ring portion 418 has a length in the radial direction of at least 30 mm or 35 mm, preferably even more than 40 mm. The outer ring portion 418 extends perpendicularly to the axle 403, which helps to improve the aerodynamics.

[0042] Figures 8A and 8B show a vehicle wheel 401 with a corresponding wheel disc 410. The wheel rim 402 can essentially have any design suitable to support a tire of the required tire size between the rim flange 421, which is again welded to the rear side of the wheel disc 410 and forms an integral part of the wheel disc 410, and the rim flange 404, which is formed on the wheel rim 402. The wheel disc 410 of the vehicle wheel 401 is provided with ventilation holes 430, which, as in the first exemplary embodiment, have two different hole contours 431 or 432, the ventilation hole with hole contour 431 being repeated five times in the circumferential direction, as is the ventilation hole with hole contour 432. Now, since the visible side is provided with a wave structure, concentric rings appear on the visible side, which are generated by the wave structure and which ensure the change in material thickness, as shown in Figure 8 by the radii of curvature R4a, R5a, R6a, R7a, R8a, R9a.

[0043] 9, 10A, 10B show a wheel disc 510 or a vehicle wheel 501 with a wheel disc 510 according to a sixth exemplary embodiment. Here, reference is also made initially to the cross-sectional representation of the wheel disc 510 in FIG. 9. This wheel disc 510 is likewise manufactured by flow forming, starts from the wheel axis 503 and has a hub connection flange 511, an inner ring portion 515, a radially inner transition curve 516, a wheel disc transition surface 520, a radially outer transition curve, an outer ring portion 518 and a rim flange 521. Also depicted are positions a, b, c, d and e intended to indicate the respective bounding extents of the individual upper sections 515, 516, 520, 517, 518. In contrast to the two previous exemplary embodiments, both the lower front side of the wheel disc 510 in FIG. 9 and the upper rear or inner side of the wheel disc 510, respectively, are provided with a wave structure. This results in crests R6b, R10b and troughs R4b, R8b, R13b on the front side. On the rear side, crests R7b, R11b, R14b and troughs R5b, R9b, R12b are formed at the transition surface 520 during flow forming, respectively. Since the wave structure is present on both sides, zones with minimum material thickness occur at the transition surface 520 approximately in the range where the wave troughs meet, here for example in the range of the wave troughs R8b, R9b and R12b, R13b. In these ranges, the thinning during flow forming can be reduced to a maximum of 40% of the starting thickness or at least 60% of the starting thickness. Since the wave profile can only be generated on one side by moving the tool, in order to design the wave structure on both sides, it is also necessary to provide an inverted wave exit profile on the surface of the spin chuck. The radius of curvature of the crests R6b, R10b and the troughs R4b, R8b, R13b on the front side (bottom surface in FIG. 9) is preferably 3-6 times larger than the radius of curvature of the crests R7b, R11b and the troughs R5b, R12b on the rear side. For example, the radius R5b can be 100 mm, while the radius R13b is 600 mm. Here, too, the radius of curvature of the side facing the tool during flow forming can increase from the radially inner side to the radially outer side, so that the radius R5b is, for example, 50% smaller than the radius R12b.The crest R14b is located substantially at the radially outer transition curve 517, and the thinning of the material thickness can be particularly greater at the two transition curves 516, 517 than at the transition surface and in the outer ring portion 518. Here too, the outer ring portion 518 occurs as a ring zone, which extends perpendicularly to the wheel axis 503 for more than a few millimeters, for example more than 1 / 20 of the wheel size.

[0044] 10A and 10B show this again on a vehicle wheel 501 with a wheel disc 510 and a wheel rim 502 with an inner rim flange 504 connected to the rear side. The crests R6, R10 are formed and can be seen on the front side, while the rear side has a crest R7b with a trough R9b between them and a trough R12b further outward in the radial direction. The vent 530 with the trapezoidal hole contour 531 extends over almost the entire radial extension of the transition surface 520, in this respect over the range of several crests and troughs. On the other hand, the vent with the hole contour 532 has a smaller radial extension and is located further outward in the radial direction only in the range of the crests R11b and R15b and the troughs R12b, R13b. The bridge sections 541, 542 occurring between adjacent vents with the hole contours 531, 532 respectively have a corresponding change in material thickness and do not proceed in the radial direction.

[0045] 11 shows a further cross-sectional profile of a wheel disc 610 according to the invention for a vehicle wheel 601, shown only diagrammatically with a partially shown wheel rim 602. Here too, the wheel disc 610 has a wave-like structure on the inside, i.e. on the side where the wheel rim 602 is connected to the rear side of the outer ring part 618 via a welded connection, with wave crests R4c, R6c, R8c, R10c, R12c, R14c and R16c, respectively, being in the region of the disc transition surface 620 and wave troughs R5c, R7c, R9c, R11c, R13c, R15c, R17c, respectively, being formed between these crests.

[0046] The outer ring part 618, which at the same time forms a ring zone with an aerodynamic surface extending perpendicular to the wheel axis, further has a minimum crest R18c on the inside, the inner ring part 615 is also provided with troughs R1c and crests R2c, while the transition part 615 has only a minimally designed trough R3c between the adjacent crests R2c and R4c. The material thickness in the range of troughs and crests R2c-R4c is thicker than the actual starting thickness of the preform, as indicated by the solid line 650. The wheel disc 610 therefore has 14 changes between crests and troughs only in the transition area. Since the rim flange 621 is formed directly on the outer ring part 618, the vehicle wheel 601 is also a so-called "full vehicle wheel".

[0047] FIG. 12 shows a further exemplary embodiment of a vehicle wheel 701 with a wheel disc 710 according to the invention, which is connected to a rim 702 via a welded connection. Here, however, the rim 702 is a rim 702 designed in the usual way, with both rim flanges, and therefore also with an outer rim flange 705. The connection with the outer ring part 718 of the wheel disc 710 is made via an inwardly bent ring collar 760, which is at least partially welded to the rear side of the rim 702 and at the same time forms the radially outer end of the wheel disc. Here too, the transition surface 720 of the wheel disc 710 has a wave-like structure on the rear side, which forms the inside in the assembled state and has wave crests R3d, R5d, R7d, which are only shown here diagrammatically, and wave troughs R2d, R6d therebetween. On the other hand, the front side of the wheel disc 720 has a smooth, high-quality surface and is preferably used as the visible surface of the vehicle wheel without aftertreatment. However, it can also be painted or reprocessed in some other way.

[0048] Fig. 13 shows yet another exemplary embodiment of a vehicle wheel with a wheel disc 820 according to the invention. Here too, only the rear side of the wheel disc 810 is provided with a wavy structure with a number of alternating crests and troughs on one side (not shown), as described above. The transition surface 820 between the radially outer ring part 818, which forms a ring zone extending several centimetres perpendicular to the wheel axis (not shown) to improve aerodynamics, and the inner ring part 815, has five times the same pattern area 880, each with four ventilation holes 830 with different hole contours 831, 832, 833, 834. The hole contours 831, 834 have an approximately triangular basic shape, with their bases located radially outside the hole contour 831 or radially inside the hole contour 834, respectively. The hole contours 832 and 833 are identical to each other, but arranged in mirror-inversion. The individual vent holes 830 with the hole contours 831-834 are punched or cut out in a subsequent method step after the wave structure has been produced. The positioning is performed in such a way that bridge webs 841, 842 remain between adjacent vent holes with corresponding hole contours 831-834 and then cross each other. A single pattern area 880 is shown enlarged in FIG. 14. The entire pattern area 880 with four vent holes 830 with hole contours 831-834 extends over the extent of a very large trapezoidal vent hole, as indicated by the dashed line 890. Due to the concentric wave bottoms and crests, the bridge webs 841, 842 crossing each other have a change in material thickness on the inside, as does the wide extent of the wheel disc transition surface 820 that remains between the two pattern areas 880. The wave structure allows various design variants, especially with regard to the hole contours and the bridge webs that remain between the hole contours, since the change in material thickness simultaneously ensures additional reinforcement with respect to the loads that occur during operation. The vehicle wheel designer can choose from a number of different hole contours and then, via a suitable wave structure applied during flow forming, particularly to the transition surface 820, can influence the stiffness behavior of the wheel disc to such an extent that even multiple vent holes installed at irregular intervals from each other reach the profile required for stiffness and load bearing.

[0049] 15A-15D respectively show exemplary different designs of vents or bridge webs, relative to a practically uniform basic vent contour as shown in each case by the dashed line 990. In FIG. 15A, the respective bridge webs 941A are parallel to each other. The two central vents 930 have a strip-shaped hole contour 931 and the two side vents have irregular hole contours 932, 933, which are designed as a mirror image of each other. FIG. 15B shows a central straight bridge web 941A and two curved bridge webs 942, 943 for a wheel disc with the same size base window 990. The bridge webs are formed by cutting the hole contours 934A, 934B, 935, 936 for the vents accordingly.

[0050] 15C again shows straight-lined bridge webs 944, 945, 946 for a vent with a dashed basic shape 990, with the central bridge web 944 lying on a radial line, while the two bridge webs 945, 946 extend at an angle thereto or are bent. The bridge webs can be on a radial line or can deviate therefrom. A hole contour 937A, 937B, 938A, 938B is generated between the respective bridge web 944, 945, 946 and the non-cut-out area of ​​the wheel disc transition surface 920, which hole contour ensures any new styling of such a vehicle wheel. It goes without saying that the respective hole contour 937A, 937B, 938A, 938B is cut out during manufacturing so that the corresponding bridge web 944, 945, 946 remains.

[0051] Fig. 15D shows yet another exemplary embodiment, where hole contours 939A, 939B and 939C are cut out in the basic form 990 for the vent holes, which contours ensure that irregular bridge webs 947, 948 remain. Here too, the wave-like structure of concentric crests and troughs on the wheel disc surface 920 or the rear side of the bridge webs 947, 948 provides a corresponding reinforcement, which allows a multiplicity of variations with respect to the hole contours.

[0052] Many modifications will be apparent to the skilled person from the above description, which modifications fall within the scope of the appended claims. The number of crests and troughs per wave structure is merely an example in the respective exemplary embodiment. The same applies to the respective hole contours, which are essentially only intended to specify and explain how and by what the various ventilation holes can be fastened and provided on a wheel disc with a wave structure according to the invention, which ensures multiple changes in material thickness between the inner and outer ring parts.

Claims

1. 1. A vehicle wheel, in particular a wheel disc for a passenger car, having a wheel disc body manufactured from a metal preform by flow forming with a tool against a spin chuck, said wheel disc body comprising: a radially inner connecting flange (11) provided with several bolt holes (13) and a central hub hole (12); a drawn disc transition surface (20) followed by ventilation holes (30) and a radially outer disc edge, the transition surface (20) having a material thickness that varies at least partially several times when viewed in the radial direction, and all ventilation holes (30) being attached by punching or cutting between a first inner ring part (15) produced during flow forming, which is arranged between the connection flange (11) and the transition surface (20), and a second outer ring part (18) produced during flow forming, which is arranged between the transition surface (20) and the disc edge; In a wheel disc having The transition surface (20) between the inner ring portion (15) and the outer ring portion (18) has some variations in material thickness created during flow forming by the displacement of the tool, which, viewed in the radial direction, results in a wave structure on the surface facing the tool during flow forming. A wheel disc comprising:

2. The outer disc edge has an end designed as a rim flange (21) so that the rear side of the preform facing the spin chuck during flow forming can be used as the viewing side of the wheel disc, or The outer disk edge has an end connectable to a wheel rim such that the rear side of the preform facing the spin chuck during flow forming can be used as the viewing side of the wheel disk.

2. The wheel disc of claim 1 .

3. The transition surface has a wave structure with more than three crests (R4, R6, R8) and troughs (R5, R7, R9), preferably more than five crests and troughs, in particular more than seven crests and troughs, at least on the upper side of the preform facing the tool during flow forming.

2. The wheel disc of claim 1 .

4. The wave crests (R4, R6, R8) and the wave troughs (R5, R7, R9) have radii of curvature; The crests (R4) and troughs (R5) adjacent to each other preferably have different radii of curvature, and / or The wave bottoms (R5, R7, R9) have a larger radius of curvature than the wave crests (R4, R6, R8).

4. A wheel disc according to claim 3, characterized in that:

5. The transition surface (520) also has, at least in part, a wave structure on the rear side facing the spin chuck during flow forming, which generates a change in material thickness with wave troughs (R8b, R12b) and wave crests (R6b, R10b).

2. The wheel disc of claim 1 .

6. the ventilation holes of the transition surface have at least two different hole contours (31, 32) or differently arranged hole contours (133, 136; 134, 137), These hole contours are repeated at least once more in the circumferential direction, preferably at least Together they form a pattern area that is repeated three times.

2. The wheel disc of claim 1 .

7. Each pattern area is several vent holes with different hole contours (231-238); intermediate struts between said vent holes having varying material thickness; have 7. A wheel disc according to claim 6, characterized in that:

8. Each pattern area has at least one partial section (275) partially designing the transition surface, the section being adjacent to the inner ring portion, not interrupted by the vent holes, and having a material thickness that varies in the radial direction.

7. A wheel disc according to claim 6, characterized in that:

9. the ventilation holes of the transition surface have at least two different hole contours (31, 32; 831, 834) or differently arranged hole contours (832, 833), bridge webs (841, 842) having a radially varying material thickness are disposed between adjacent hole contours; 2. The wheel disc of claim 1.

10. 10. The wheel disc of claim 9, wherein said bridge web has an at least partially constant width over its partially extended length.

11. Several bridge webs (941; 945, 946) run parallel to each other or curve towards and / or across each other and / or characterized in that The bridge webs (942, 943) are designed as rounded curves, straight struts, and / or asymmetric struts.

10. A wheel disc according to claim 9.

12. Several vent holes formed by different hole contours together with the associated bridge web form a window-like hole group, the group including a window area having a peripheral contour (990) corresponding to a round hole, a triangular hole with rounded corners, or a square hole with rounded corners.

10. A wheel disc according to claim 9.

13. The inner ring portion (15) has a material thickness that varies in the radial direction, preferably having a wave structure with preferably only one wave trough (R1) on the surface facing the tool during flow forming. It is characterized by the fact that Preferably, said inner ring portion merges into said transition surface (20) via a transition curve (16), preferably having a wave base (R3).

2. The wheel disc of claim 1.

14. The inner ring portion between the connecting flange and the transition surface has a wave structure with one wave trough or two wave troughs.

14. A wheel disc according to claim 13, characterized in that

15. said wheel disc (10; 110; 410; 510; 610; 810) is designed as a full surface wheel disc having a rim flange (21), The outer ring portion (18; 118; 418; 518; 618; 818) preferably has a ring zone with a flat surface on the viewing side aligned perpendicular to the rotation axis (3) of the wheel disc. It is characterized by the fact that the ring zone has a length in the radial direction of at least 25 mm, 28 mm, 32 mm, or 35 mm, and / or preferably has a length in the radial direction that is greater than 1 / 20 of the wheel disc diameter, preferably greater than 1 / 16 or even 1 / 15 of the wheel disc diameter; 2. The wheel disc of claim 1.

16. The ring zone has at least one crest, preferably both a crest and a trough.

16. A wheel disc according to claim 15.

17. 1. A method for manufacturing a wheel disc for a vehicle wheel, in particular for a passenger car, comprising: flow forming the metal preform on a flow forming machine against a spin chuck using at least one spinning roller as a tool; In the flow forming step, a connecting flange, a disc transition surface, and a disc edge are produced on the wheel disc body, and the transition surface in the flow forming step is at least partially provided with a material thickness that varies several times when viewed in a radial direction; generating a first inner ring portion between the connecting flange and the transition surface and a second outer ring portion between the transition surface and the disc edge; punching or cutting vent holes in the transition surface in a subsequent processing step; A method comprising: the transition surface between the inner ring portion and the outer ring portion (18) undergoes several changes in material thickness produced during flow forming by the displacement of the tool, resulting in a wave structure, when viewed in the radial direction, on the surface facing the tool during flow forming; all vent holes are made by stamping or cutting at least two different hole profiles or differently positioned hole profiles between the inner ring portion and the outer ring portion; The arrangement of the vent holes and the remaining basic structure on the wheel disc body form a patterned area on the transition surface, which is repeated circumferentially at least one more time, preferably at least three times. A method characterized by:

18. Several vent holes having different outer contours are provided in each pattern area. It is characterized by the fact that Intermediate struts having varying material thickness are provided between the vent holes; at least one partial section adjacent to the inner ring portion, not blocked by the vent hole, and having a varying material thickness in part is generated; 18. The method of claim 17.

19. The pattern areas for the vents, bridge webs or intermediate struts, and partial sections are determined iteratively in several steps. It is characterized by the fact that In a first step, a basic pattern area with vent contours is developed from the stiffness and load-bearing parameters required for the vehicle wheel, and said contours are then evaluated for feasibility. and analyzed in at least one further step, In a further step, prior to the manufacturing of the wheel disc, the arrangement and the contour of the ventilation holes and the change in material thickness between the ring portion and the position, shape and alignment of the bridge web or intermediate web resulting in the wave structure are optimized with respect to vehicle wheel weight and stiffness.

18. The method of claim 17.

20. A vehicle wheel, in particular for a passenger car, having a wheel disc and a wheel rim, The wheel disc (10; 110; 210; 310; 610; 810) Designed according to any one of claims 1 to 16, and / or Produced according to the method of any one of claims 17 to 19 It is characterized by the fact that Preferably, the front side of the vehicle wheel as seen in an assembled state on the vehicle comprises the side of the wheel disc body that is pressed against the spin chuck during or in the flow forming step. Vehicle wheel.

21. said wheel disc (10; 110; 210; 310; 410; 510; 610; 810) forming a fully formed rim flange; a rim portion is connected to the rear side of the wheel disc in the area of ​​the outer disc edge or the outer ring portion, radially outwardly offset relative to the outer transition curve to the outer ring portion 21. A vehicle wheel according to claim 20, characterized in that

22. The wheel disc (10; 110; 210; 310; 410; 510; 610; 810) on the outer ring portion preferably has a ring zone with a flat surface aligned perpendicular to the rotation axis of the vehicle wheel. It is characterized by the fact that the ring area has a length in the radial direction of at least 28 mm, 32 mm, or 35 mm, and / or preferably has a radial length greater than 1 / 20 of the wheel disc diameter, preferably greater than 1 / 16 or 1 / 15 of the wheel disc diameter; 22. A vehicle wheel according to claim 21.

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