Apparatus For Forming Wheel Rims

Abstract

A process and apparatus for forming a drop center wheel rim wherein a substantially rectangular piece of metal is shaped into a cylindrical blank and the central portion thereof is engaged and progressively urged inwardly by pressure applying medium to form the drop center or well of the wheel rim. The partially formed wheel rim is then subjected to the action of first-stage male and female dies to further form the wheel rim and is then subjected to the action of male and female finishing dies to completely form the wheel rim. The process and apparatus permits wheel rims to be formed while minimizing, if not elimination, any tendency of the cylindrical blank to thin at areas known to be subjected to stress. The process and apparatus also permits the formation of wheel rims with reduced requirements as to space and time.

Description

SUMMARY OF THE INVENTION

Heretofore, most wheel rims have been produced primarily in a rolling operation in which the metallic blanks are shaped. Experience has indicated that the production of conventional drop center wheel rims sometimes results in thinning of the material during the shaping operation. It is, of course, desirable to produce wheel rims that are of uniform thickness and that do not have deficient thickness dimensions at areas subjected to stress. Conventional wheel forming installation requires substantial space and therefore requires a substantial amount of time to completely form a wheel rim from a blank of material.

It is therefore an object of this invention to provide a process and apparatus for producing a wheel rim which is formed in a manner to minimize the occurrence of thinning of material during the shaping steps. The apparatus system used in carrying out the process, requires substantially less space than that of conventional systems and requires substantially less time to completely finish a wheel rim than the conventional rolling system.

BRIEF DESCRIPTION OF THE FIGS. OF THE DRAWING

FIG. 1 is a diagrammatic illustration of an apparatus system used in carrying out the steps of the process,

FIG. 2 is a top plan view of the drop center forming device with certain parts that are broken away from clarity,

FIG. 3 is a fragmentary perspective view of a portion of the drop center forming device with a cylindrical blank positioned prior to entry into the device,

FIG. 4 is a fragmentary perspective view of a portion of the drop center forming device,

FIG. 5 is a diagrammatic perspective view illustrating the male and female die members of the first-stage die device,

FIG. 6 is a fragmentary cross-sectional view of the first-stage die device fragmentarily illustrating portions of the male and female die elements in a partially closed position and engaging a partially formed wheel rim,

FIG. 7 is a fragmentary cross-sectional view of the first-stage die device similar to FIG. 6, but illustrating the male and female die elements in the fully closed condition,

FIG. 8 is a fragmentary cross-sectional view of the second-stage die device with the die elements thereof in a partially closed condition engaging the partially formed wheel rim,

FIG. 9 is a fragmentary cross-sectional view similar to FIG. 8 but illustrating the second-stage die elements in the fully closed position to completely form the wheel rim,

FIG. 10 is a cross-sectional view of a modified form of the second-stage die elements similar to FIG. 9 but illustrating a modification thereof, and

FIG. 11 is a perspective view similar to FIG. 4 illustrating a modified form of the drop-center forming device.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and more specifically to FIG. 1, it will be seen that the apparatus system, designated generally by the reference numeral 10, for carrying out the process is thereshown. The present process and apparatus system contemplates the continuous production of wheel rims which are generally known in the trade as drop center wheel rims. Such wheel rims are adapted for use on agricultural vehicles as well as other kinds of vehicles.

In the present process, wheel rims are formed from metallic blanks. It has been found that thinning of material has been held to a minimum due to forming process versus rolling process. The entire apparatus system utilized in carrying out the process is relatively compact compared to the conventional rolling system and the production of a wheel rim may therefore be carried out in a relatively short time as compared to the conventional rolling system.

In the present process and apparatus system, as illustrated in FIG. 1, the metallic blanks from which the wheel rims are formed are unwound from a coil of sheet steel 11, which may be supported in close proximity to an edger and feed roll device 12. The edger and feed roll device has suitable rolls therein which engage the longitudinal edges of the strip of metallic material to shape the same into relatively smooth contour. This edging step is desirable, especially when the edges of the strip of the material have not been finished and have burrs and other roughened surface areas. The rolls of the edger device also function as feed rolls to convey the strip to a shear device where the strip of material is cut into a rectangular blank 13 of predetermined size. In this regard, the size of the blank will be determined by the size of the wheel rim to be formed. The width of the blank 13 will correspond generally to the axial dimension of the wheel rim while the length of the blank will correspond generally to the largest circumferential dimension of the wheel rim.

The rectangular blank B is thereafter conveyed to a coiler and welding jig 14 when the rectangular blank B is coiled into cylindrical configuration and the abutting ends thereof are welded together to form the cylindrical blank C. It is pointed out that the cylindrical blank C has an axial dimension only slighter greater than the axial dimension of the finished wheel rim and the longitudinal dimension of the cylinder corresponds generally to the diameter of the large diametrical portion of the wheel rim.

The cylindrical blank C is then conveyed to a drop-center forming device 15 where the central portion of the cylindrical blank C is deflected uniformly inwardly to form the drop center of the finished wheel rim. Thereafter, the partially formed wheel is then directed to the first-stage die device 16 where the partially formed wheel rim is further shaped into partially finished condition and is finally directed to a finishing die device 17 wherein the partially formed wheel rim is completely formed. The partially formed wheel rim which results from the shaping step by the drop-center forming device is designated by the reference character D while the partially formed wheel rim produced by the first-stage die device is designated by the reference character E. The finished wheel rim is designated by the reference character W.

Referring now to FIG. 1 and 9, it will be seen that the finished wheel rim W includes a cylindrical drop center portion 18 which constitutes a substantial portion of the overall axial dimension of the wheel rim W. It will be noted, however, that the drop center portion 18 is offset slightly axially although in other wheel rims, the drop center portion may be centrally located. The drop center portion 18 is interconnected to shoulders 19 by interconnecting portions 20. It will be noted that the interconnecting portions 20 flare outwardly from the drop center portion, while the shoulders 19 are substantially cylindrical and are therefore substantially coaxially disposed with respect to the drop center portion. Shoulders 19 are connected to flanges 20 which extend radially from the shoulders and terminate in beads 21 which in the embodiment shown in FIG. 9 are slightly rolled.

One of the most important features of the present invention is the formation of the drop center with respect to the cylindrical blank C. It is pointed out above, the cylindrical blank C has a central portion thereof uniformly reduced in diameter in an unheated forming step and reference is now made to FIGS. 2, 3 and 4 where the drop-center forming device 15 is thereshown.

The drop-center forming device 15 includes a housing 22 which is provided with a centrally located opening 23 therein, the opening being of a size to accommodate the cylindrical blank C in loose fitting relation therein. The drop-center forming device is provided with a cylindrical segmented die 24 which defines the cylindrical opening 23 interiorly of the housing 22. The cylindrical segmented die 24 is comprised of a plurality of identical surface die elements 25 which are of substantially parallelogram configuration. It will be noted that these surface die elements 25 are oriented so that the longitudinal edge 26 of one die element is positioned in proximal relation with a longitudinal edge of an adjacent element. It will be noted that these longitudinal edges are obliquely arranged. Each die element 26 also includes an upper edge 27 and a lower edge 28.

The segmented die 24 also includes a plurality of similar liner die elements 29 of parallelogram configuration and identical in construction to the surface die elements 25. It will be noted that the liner die elements are obliquely oriented but oppositely oriented from the surface die elements 25 and each includes longitudinal edges 30, an upper edge 31, and a lower edge 32.

A plurality of support members 33 are provided, each including a vertically oriented plate 34 having a boss or sleeve 35 having an opening 36 therein. Each plate 34 has a mounting block 37 integrally formed with the inner end thereof. Each surface die element 25 and its associated liner die element 29 is pivotally connected to one of the mounting blocks 37 by pivot.

In the embodiment shown, the surface die elements and liner die elements are pivotally connected to every other mounting block 37. Each mounting block 37 has an inwardly projecting upper lip 39 integrally formed therewith and an inwardly projecting lower lip 40 integrally formed therewith. The lower surface of the upper lip defines a camming surface 41 and the upper surface of the lower lip 40 defines a camming surface 42. The camming surface 41 engages the upper edges of the surface and liner die elements while the lower camming surface 42 is engageable with the lower edges of the surface and liner die elements.

The sleeve 35 of each support member 33 is pivotally connected by pivot pin 43 to a link 44. Each link 44 is pivotally connected by pivot 45 to a lever 46 which is pivotally mounted on the housing by pivot pin 47. Elongate links 48 pivotally interconnect the outer end portions of adjacent levers by pivot pins 49. It will be noted that each link 44 and each lever 46 constitutes a toggle type linkage interconnecting each support member 33. Thus by shifting the toggle linkage, the support members 33 are shifted radially inwardly and outwardly with respect to the opening 23.

Suitable vertically oriented guide pins 50 are positioned on opposite sides of each plate 34 of each support member 33 to facilitate guiding of the plate in its inward and outward movement. A pair of vertically oriented guide rollers 51 is positioned on the opposite sides of each plate 34 to assist in guiding the support members in its movement.

Means are provided for operating the toggle linkage and this means includes a pair of double acting hydraulic piston and cylinder units 52, each comprising a cylinder having a piston axially movable therein which is connected to a piston rod 54. Each hydraulic cylinder is pivotally mounted to a mounting plate 55 by means of a pivot 56, each plate 55 being secured to the housing 22 and projecting outwardly therefrom.

The piston rod 54 of each hydraulic piston and cylinder unit is pivotally connected by means of a pivot 57 to one end of an elongate bell crank or lever 58. The lever 58 is pivotally connected by pivot 59 to a mounting plate 60 which is also secured to the housing 22. Each lever 58 has a plurality of links 61 pivotally secured thereto by pivots 62 and these links 61 are also pivotally connected to certain of the levers 46 by pivot 63. With this arrangement, extension and retraction of the hydraulic piston and cylinder units causes actuation of the toggle linkage and thus inward and outward shifting movement of the support members 33.

It is pointed out that the cylindrical segmented die 24 is shiftable between an expanded retracted position and contracted inward position. When the segmented die 24 is in the expanded retracted position, as viewed in FIG. 3, the support members will be retracted and the surface die elements will have their longitudinal edges spaced apart. The liner die elements will also have their adjacent longitudinal edges spaced apart. However, as the toggle linkage is actuated to shift the support members radially inwardly, the die elements will pivot about their respective pivot pins 38 by coaction with the camming surfaces of the mounting blocks. Thus the segmented cylindrical die will engage the central portion of the cylindrical blank C and progressively deform the same inwardly in a uniform fashion to form the drop center portion of the wheel rim. Although the cylindrical blank C will be in a substantially unheated condition, the pressures created by the segmented die does generate some heat and a suitable coolant is supplied through a conduit 64 which is connected in communicating relation with a circular discharge pipe 65 positioned above the segmented die to discharge a liquid coolant upon the die. It will be noted that the pivotal connections of the toggle linkage, actuating levers and piston and cylinder units are all vertically disposed so that the movements of the interconnected parts are horizontally about vertical axes.

It will be seen that after the drop center portion of the wheel rim has been formed, the end portions of the partially formed wheel rim are of cylindrical configuration. This partially formed wheel rim is then conveyed to the first-stage die device illustrated in FIGS. 5, 6 and 7. The first-stage die device includes a pair of male die members 66 which are of similar configuration and a pair of female die members 67 also of similar configuration with respect to each other. The female die members are urged into embracing relation with respect to the exterior of the partially formed wheel rim D. Then the male elements 66 are urged into opposite ends of partially formed wheel rim D.

Means are provided for shifting the die members between open and closed positions and to this end it will be seen that each male die member 66 is secured to one end of an elongate ram 68. The outer end of each ram 68 is pivotally connected to an arm 69 by pivot 70. The other end of each arm 69 is pivotally connected by pivot 71 to an arm structure 72 which is secured to a revolvable vertical post 73. It will therefore be seen that by revolving the posts 73 about their vertical longitudinal axes, the rams 68 will be extended and retracted to thereby move the male die members toward and away from each other.

The means for revolving each post 73 comprises a pair of double acting hydraulic piston and cylinder units 74 each including a cylinder 75 having a piston movable therein to which is connected a piston rod 76. The piston rods 76 are connected to arms 77 which are secured to the associated post 73. An elongate drag link 78 is pivotally connected at its ends to arms 79 carried by the posts 73. The drag link aids in the uniform action of the male die element during retraction and extension thereof between open and closed positions.

The female die members 67 are also each connected to one end of an elongate ram 80, the other end of the ram 80 being pivotally connected to an arm 81 by a pivot 82. The arm 81 is pivotally connected by a pivot 83 to an arm 84 which is rigidly affixed to a revolvable vertical post 85. The posts 85 are each revolved by hydraulic piston and cylinder unit 86 comprised of a hydraulic cylinder 87 having a piston rod 88 secured to the piston thereof. The piston rod is secured to an arm 89 which is secured to the post 85. A drag link 90 is also pivotally connected at each end to an arm 91 secured to the post 85. It will therefore be seen by extending and retracting the piston rod of each piston and cylinder unit, the posts 85 will be revolved and will shift the rams 80 toward and away from each other.

Means are also provided for releasably locking the female die members in their closed position. Each female die member is provided with a locking mechanism 92 although only one such locking mechanism is illustrated in FIG. 5. It is understood that a locking mechanism will be provided for the other female die member. The locking mechanism 92 for each female die member comprises a locking bar 93 which is pivotally mounted by pivot 94 to the support structure which supports the first-stage die device. The locking bar 93 is therefore mounted for horizontal swinging movement about a substantially vertical axis. A coil spring 95 bears against the locking bar 93 and against a bearing member 96 which is secured to the supporting structure for the first-stage die device. Thus the locking bar 93 is constantly urged inwardly against the associated female die member.

The locking bar 93 also has an elongate cam member 97 secured thereto and projecting inwardly therefrom. When the female die members are in the retracted position, the locking bar 93 wild urge against the side surface 67a of the female die member. As the female die member is moved inwardly, into the fully closed position, the end edge of the locking bar will engage the rear surface 67b of the female die member to lock the female die member against retracted movement.

Referring to the sequence of FIG. 5, the female members 67 close first grasping partially formed wheel rim D, also allowing locks 97 to close. Then male die members 66 advance to the closed position. They then return releasing locks 97 to permit female members 67 to return to the starting position. Male die members 66 are also retracted prior to the female die members and when the male die members are retracted, the male die members urge the cam members in a direction to pivot the locking bars 93 out of engaging relation with respect to the female die members thus allowing retraction thereof.

It is pointed out that the finishing or second-stage die members are identical to the first-stage die members but for the respective die faces of the male and female die members. Therefore, the actuating mechanism associated with the finishing die device is identical to that of the first-stage die device and a detailed description thereof is thought to be unnecessary.

Referring again to FIGS. 5, 6 and 7, it will be seen that each die male element 66 has a die face 98 comprised of a flat surface 99 which confronts the corresponding face on the other male die member. The die face 98 also includes the surface 100 which together with the other male die member corresponds to the inner surface of the drop center portion. The die face 98 includes a die surface 101 which flares outwardly from the surface 100 and further includes surface 102 which also flares outwardly but is more axially disposed than surface 100. Surface 103 is continuous with die surface 102 but flares more radially than the die surface 102. Die face 98 also includes surface 104 which is shouldered as at 140 so that the ends of the partially formed wheel rim engage thereagainst.

It will be noted that each female die member 67 has a die face 105 which comprises substantially one-half of the exterior surface of the partially finished wheel rim. Die face 105 includes a die surface 106 which corresponds to the exterior surface of the drop center portion. Die surfaces 107 flare outwardly from the surface 106 and match with surface 101 of die faces 98. Die surface 108 are continuous with die surfaces 107 and flare outwardly therefrom and cooperate in matching relation with die surfaces 102 of the die faces 98. Die face 105 also includes die surface 109 which mates with die surface 103 and terminates in die surfaces 110 which are substantially cylindrical in configuration. It will be noted that the die surfaces 100 of the male die members have slightly different axial dimensions since in the embodiment shown the drop center portion is axially offset.

Referring now to FIGS. 8 and 9, it will be seen that the finishing die device 17 includes male die members 111 and female die members 112. As pointed out above the finishing die device is identical in construction to the first-stage die device except for the die faces of the respective male and female die members. In this regard, it will be noted that the male die members 111 each include a die face 113 having confronting circular surfaces 114. Each die face 113 also includes a die surface 115 which is of cylindrical configuration and which is continuous with die surface 116 that flares outwardly from the die surface 115. Die surface 117 extends substantially axially from die surface 116 and is continuous with a substantially radial die surface 118. An arcuate die surface 119 is continuous with each radial die surface 118 and terminates in a shoulder that defines a slight recess 120.

Each female die member 112 includes a die face 121 which includes a cylindrical surface 122 which matches or mates with surfaces 115 of die faces 113. Surface 122 of each die face 121 is continuous with die surfaces 123 which flare outwardly and which mate with surfaces 116 of the male die elements. Surfaces 124 extend substantially axially from the surfaces 123 and each terminates in a substantially radial surface 125 which mates with the associated radial surface 118. Surface 125 is continuous with an arcuate surface 126 of concave configuration and terminates in cylindrical surfaces 127. It will be noted that the arcuate surface 119 which is of convex configuration does not exactly mate with the associated arcuate concave surface 26 so that a small recess 127 is defined. It is felt that this recess permits the formation of the arcuate bead of the wheel rim with these match metal dies. It will also be noted that the surfaces 115 of the male die members are of different axial length to accommodate the axially offset drop center portion of the wheel rim. It will be noted that the embodiment illustrated in FIG. 10 of the finishing die device is identical to that illustrated in FIGS. 8 and 9 except that the arcuate surface 119a extends outwardly to the adjacent shoulder so there is no recess 120 defined as in the embodiment. That arcuate surface 119a cooperates with the arcuate surface 125a so that a recess 126a is provided in the manner of the embodiment of the dies of FIGS. 8 and 9. However, the omission of the recess 120 allows the arcuate bead to project more radially from the flange with less of an outward convexity than the embodiment of FIG. 9.

Referring now to FIG. 11, it will be seen that a slightly modified form of the cylindrical segment and die is thereshown. This modified cylindrical segmented die is designated generally by the reference numeral 24a and is positioned interiorly of the housing 22 and inwardly of the opening 23. This segmented die also includes a plurality of similar surface die elements 25a each having an upper edge 27a and a lower edge 28a. Each die element 25a has a plurality of generally rectangular obliquely arranged projecting teeth 26a extending from opposite edge surfaces thereof. These teeth mate with the recesses 26b defined by the teeth of the adjacent die element.

The liner die elements 29a is also identical to those shown in the embodiment of FIGS. 2, 3 and 4. The surface and liner die elements are pivotally connected to their associated support members by pivot pins 38a and expansion and retraction of the segmented die is identical to that of the embodiments of FIGS. 2, 3 and 4, except that the teeth of each surface die element shifts into and out of snug fitting relation with respect to the associated recesses 26b of the adjacent surface die elements. This arrangement will permit the segmented cylindrical die to be expanded and contracted in the manner of the embodiment of FIGS. 2, 3 and 4.

Referring again to FIG. 7, it will be noted that the shoulders 140 on the male die members 66 engage the axial ends of the partially formed wheel rim thus causing upsetting of the rim as the male die members move to the completely closed position. This occurs before the female die members 67 are moved into mating relation with respect to the male die members. Thus by upsetting or deforming the partially formed wheel rim prior to completely shaping or forming of the same (by the coaction of the male and female die members), thinning of the material of the partially formed wheel rim is held to a minimum.

It is also felt that by upsetting the partially formed wheel rim prior to completely shaping the various portions thereof also improves the grain of molecular crystalline structure thereof of the metal. It is when the male and female die members of FIG. 7 are in the completely closed condition, that the upset or deformed portions of the partially formed rim structure are then permanently formed or shaped into the configuration illustrated by FIG. 8 of the drawing. It has been found that if the rim structure is formed without upsetting thereof, then thinning of the material sometimes occurs and this is undesirable. However, not only does the first-stage die device minimize thinning but is so arranged and constructed to improve the grain structure of the metal.

From the foregoing description, it will be seen that I have provided a novel process and apparatus system which permits the formation of the drop center wheel rims without the necessity of heating. It has been found that in my process, that there is absolutely no thinning of the thickness dimension of the cylindrical blank when the blank is shaped to form the drop center portion of the wheel rim. It is pointed out above, by utilizing an unheated system, the grain crystalline structure of the metal is improved as compared to that of a rolling operation. The apparatus system may be compactly arranged and the process may be continuously and quickly carried out.

Thus it will be seen that I have provided a novel process and apparatus system which is not only of simple and inexpensive construction, but one which functions in a more efficient manner than any heretofore known comparable system.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the various parts without departing from the scope of my invention.

Claims

I claim:

1. Apparatus system for continuously forming drop center wheel rims, comprising:

a drop-center forming device for receiving and supporting a cylindrical blank, and comprising a generally cylindrical segmented die mechanism shiftable between an expanded retracted position and an advanced contracted position, said die mechanism including a plurality of substantially identical die elements, a plurality of shiftable support members supporting said die elements, adjacent die elements when in the expanded retracted position having adjacent edges spaced from each other whereby said die elements are disposed out of engaging relation with respect to the cylindrical blank, and when shifted to the advanced contracted position adjacent edges of adjacent die elements engaging each other whereby said die elements engage the central exterior circumferential portion only of the cylindrical blank to deform the central portion of the cylinder uniformly inwardly and to shape the cylinder into a partially formed wheel rim including a pair of cylindrical end portions of substantially the same diameter, a cylindrical reduced central portion of substantially uniform diameter, and intermediate tapered portions interconnecting the central cylindrical portion with the end portions, the reduced central portion corresponding to the drop center of the finished wheel rim, and means for shifting said support members between advanced and retracted positions;

a first-stage die device engaging the inner and outer surfaces of the partially formed wheel rim to deform each cylindrical end portion into a shoulder portion and a flange portion;

a finishing die device engaging the inner and outer surfaces of the partially formed wheel rim to deform each shoulder portion into substantially coaxial relation with respect to said drop center portion, and to deform each flange portion to extend substantially radially from its associated shoulder portion.

2. The apparatus system as defined in claim 1 wherein said means for shifting said support members include a plurality of toggle linkages each being connected to one of said support members, and piston and cylinder units connected with said toggle linkages for shifting the support members between expanded and retracted positions.

3. The apparatus system as defined in claim 1 wherein said die elements each have a plurality of teeth formed along adjacent edges thereof, the teeth on one die element being shiftable into mating relation with the teeth on the adjacent die element when the die elements are in the advanced contracted position.

4. The apparatus system as defined in claim 1 wherein said first-stage die device and said finishing die device each includes a pair of similar male die members each having a die face and each being inserted into the partially formed wheel rim, and a pair of similar female die members each having a die face, the die face of said female die members embracing the exterior surface of the partially formed wheel rim.

5. The apparatus system as defined in claim 1 and means for supporting and moving a strip of metallic material through a predetermined path of travel, a cutting mechanism in the path of travel of the strip and being operable to cut the strip into a rectangular sheet of predetermined size, means for coiling the sheet into cylindrical configuration, and means for coiling the sheet into cylindrical configuration, and means for welding the abutting ends of the coil sheet together to form the same into the cylindrical blank prior to positioning the same in said drop-center forming device.

6. In an apparatus system for continuously forming drop center wheel rims, comprising:

a drop-center forming device for receiving and supporting a cylindrical blank, and comprising a generally cylindrical segmented die mechanism shiftable between an expanded retracted position and an advanced contracted position, said die mechanism including a plurality of substantially identical die elements, a plurality of shiftable support members supporting said die elements, adjacent die elements when in the expanded retracted position having adjacent edges spaced from each other whereby said die elements are disposed out of engaging relation with respect to the cylindrical blank, and when shifted to the advanced contracted position adjacent edges of adjacent die elements engaging each other whereby said die elements engage the central exterior circumferential portion only of the cylindrical blank to deform the central portion of the cylinder uniformly inwardly and to shape the cylinder into a partially formed wheel rim including a pair of cylindrical end portions of substantially the same diameter, a cylindrical reduced central portion of substantially uniform diameter, and intermediate tapered portions interconnecting the central cylindrical portion with the end portions, the reduced central portion corresponding to the drop center of the finished wheel rim, and means for shifting said support members between advanced and retracted positions.

7. The apparatus system as defined in claim 6 wherein said means for shifting said support members include a plurality of toggle linkages each being connected to one of said support members, and piston and cylinder units connected with said toggle linkages for shifting the support members between expanded and retracted positions.

8. The apparatus system as defined in claim 6 wherein said die elements each have a plurality of teeth formed along adjacent edges thereof, the teeth on one die element being shiftable into mating relation with the teeth on the adjacent die element when the die elements are in the advanced contracted position.

9. The apparatus system defined in claim 1 wherein said finishing die device includes a pair of male die members and a pair of female die members, each female die member having a die face provided with annular arcuate recess therein adjacent the marginal portion thereof coacting with said male die members to form an annular arcuate roll back bead integral with each shoulder portion of the wheel rim.