US3019752A - Apparatus for making wheel covers - Google Patents

Description

Feb. 6, 1962 G. A. LYON APPARATUS FOR MAKING WHEEL COVERS Original Filed Nov. 5, 1956 2 Sheets-Sheet 1 Geozye A/beri 57012 b117, 7& kwzfl atent 3,iii,752 Patented Feb. 6, 1952 3,019,752 APPARATUS FOR MAKING WHEEL COVERS George Albert Lyon, Detroit, Mich, assignor to Lyon incorporated, Detroit, Mich, a corporation of Delaware Original application Nov. 5, 1956, Ser. No. 620,289. Divided and this application Sept. 2, 1958, Ser. No. 758,244

2 Claims. (Cl. 113-49) The present invention relates to improvements in apparatus for making wheel covers and more particularly covers drawn in thin sheet metal.

The present application is a division of my application Serial No. 620,289 filed November 5, 1956.

As heretofore made, drawn sheet metal covers have involved substantial Waste in scrap material. This has of course resulted in a cost factor reflected in the price at which such wheel covers could be supplied to the purchasers.

The problem that has heretofore been deemed to make inevitable substantial scrap loss has been that of uniform drawing in of the material of the polygonal and generally square blank of material in producing the circular drawn contours of the cover profile, some of which and most generally adjacent the outer margin have been fairly deep. It has heretofore been thought necessary to have a substantial flat flange margin about the drawn area of the blank for hold-down purposes in order to avoid uneven drawing in of the blank and thus wrinkling or buckling of the drawn contours adjacent to the drawing area periphery. The hold-down flanges has then been trimmed off to the extent necessary to provide the desired marginal flange structure of the completed cover and more particularly the retaining finger structure. In this connection, reference is made to my Patents No. 2,707,449 issued May 3, 1955, No. 2,807,226 issued September 24, 1957, in which in the initial phases of the method the use of a blank providing a hold-down flange entirely around the blank and then trimming away of unneeded portions of the flange is alluded to.

I have discovered how to improve the method in my patents referred to by the substantial elimination of trim scrap except for the corner portions of the blank from which the retaining flange or finger structure of the cover is derived.

It is accordingly an important object of the present invention to provide an improved apparatus for drawing sheet metal blanks into wheel covers with greatly minimized scrap losses.

Another object of the invention is to provide an improved apparatus for drawing sheet metal wheel covers from polygonal blanks wherein the corner portions of the blank are utilized for deriving therefrom retaining flange structure and according to which there is minimized tendency of the corner portions of the blank to wrinkle and distort incident to circular drawing of the body portion of the cover.

A further object of the invention is to provide an improved apparatus for drawing circular covers in polygonal sheet metal blanks and wherein substantial portions of the mill cut ends or edges of the blank are retained in the flange structure of the cover margin on which are provided the cover retaining means.

Yet another object of the invention is to provide an improved apparatus for drawing circular sheet metal covers in such closely dimensioned blanks that trimming is eliminated in at least a substantial portion of the periphery of the blank.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is an outer side elevational view of a wheel structure embodying features of the invention;

FIGURE 2 is an enlarged fragmentary radial sectional detail view taken substantially on the line II-II of FIG- URE 1;

FIGURE 3 is a fragmentary radial sectional detail view taken substantially on the line III--III of FIG- URE 1;

FIGURE 4 is a more or less schematic, fragmentary sectional detail view taken in a radial plane through a die apparatus for practicing the method of the present invention; and

FIGURE 5 is a sectional view similar to FIGURE 4 but showing the die means in the position of the respective elements thereof at the completion of a drawing stroke.

Referring first to FIGURES 1, 2 and 3, a wheel cover 15 embodying features of the invention is constructed and arranged to be applied to the outer side of a vehicle wheel in press-on, pry-off relation, such a wheel comprising a disk spider wheel body 17 supporting a tire rim 18 of the multi-flange, drop center type adapted to support a pneumatic tire 19 which may be of the tubeless type or may be a tire and tube assembly, as preferred. An intermediate generally radially inwardly facing and axially extending annular flange 20 of the tire rim merges with a generally radially outwardly and then axially outwardly turned terminal flange 21, and provides a seat for the tire 19.

The wheel cover 15 comprises preferably a one-piece sheet metal circular drawn member having self-retaining means for engagement with the wheel. To this end, the cover is preferably made from thin, cold work hardenable material such as brass or stainless steel sheet, a suitable material in practice comprising 301 nickel stainless steel which may be of about .018: inch thickness. Such stainless steel has a normal hardness of about 69 to 72 on the Rockwell B scale which, of course, is fairly soft. However, this material is readily cold workable to a hardness that must be measured on the Rockwell C scale, namely, approximately spring steel hardness and resultant resiliency.

Centrally the cover 15 may be variously contoured, being shown herein as provided with a fairly small axially outwardly projecting crown dome 22 having a radially outwardly extending contoured annular portion 23 thereabout leading into a generally axially outwardly projecting annular large rib-like portion 24, all such central portions of the cover overlying the wheel body 17. About the annular rib body portion 24 is a deeply axially inwardly inset or dished intermediate portion 25 of a diameter substantially to overlie the juncture between the tire rim and the wheel body. At its radially inner side the dished portion 25 provides a generally axially outwardly and radially inwardly sloping or oblique annular wall portion 27 while at its radially outer side there is a generally radially and axially outwardly sloping or oblique annular outer marginal cover portion 28 that is dimensioned to overlie the tire rim 18.

On its outer marginal terminus the annular cover marginal portion 28 has a generally radially outwardly turned bead-like finishing and reinforcing formation 29 provided with an underturned generally radially inwardly extending flange 50 from which extends a series of preferably four cover retaining concealed resiliently flexible retaining finger extensions 31. These extensions are actually axially inwardly extending flanges of substantial segmental width and of circumferentially arcuate form disposed on ao aree h si into short individual retaining fingers 33 which are of course connected for mutual resilient coaction in the finger extension flange 31 of which they form a part.

Each of the retaining fingers 33 has a turned generally radially and outwardly oblique short and stiff gripping terminal 34 normally extending to a diameter slightly larger than the inside face diameter of the intermediate flangelt) and engageable in resiliently tensioned radially inwardly deflected edgewise generally biting relation against the inside face of the intermediate flange 20. By preference, the short stiff terminal flanges 34 are subdivided by shallow notches 35 into a plurality of tips providing substantial numbers of sharp. corners that bite 'into the surface of the intermediate flange and hold the cover against turninga Y In applying the cover to the outer side of the Wheel, a valve stem 37 is registered with a valve stem aperture 33in the dished intermediate portion of the cover and the cover then pressed inwardly which causes the still retaining finger terminals 34 to cam axially inwardly alongthe inside face of the intermediate flange 20 and by radially inward compression as the terminal hange is ,flexed, the individual retaining fingers 33 radially inwardly develop substantial resilient radially outward thrust on the biting tips of the retaining-terminals to so grip the intermediate flange as to hold'the cover against unintentionalaxial displacement. Removal of the cover can be effected by applying'a pry-off tool behind the 'underturned'flange and applying pry-off force for slidably'dislodging the retaining finger terminals 34from the tire rim.

In addition to the improved retaining finger construction, an important feature of thepresent cover resides in that all of the edges between and including the sides of the finger extension flanges 31 are substantially free from sharp fins or burrs or cutting points so that the present cover is safer to handle than would otherwise be the case. Herein this is attained by having all of such edges comprise 'mill out or straight sheared and draw worked rather than die cut. Such millcut edges are initially substantially smooth and burr free, and the working and stretching of such edges in the course of drawing the cover further aids in smoothing the edges. On the other hand, the edges of the retaining finger terminals 34 are die cut and thus fairly sharp and even possibly containing burrs since these are if anything an asset for wheel .t'lange gripping, biting cover retaining engagement.

According to the present invention, production of the improved cover is effected by drawing the same in blanks of minimal dimensions so that the only trimming necessary is in the formation of the retaining fingers 33. To

,this end, a flatsheet metal blank B which may be initially of right angular polygonal shape and preferably substantially square, although it may vary asmall fraction of an inch through one transverse direction as compared with the transverse direction normal thereto, is initially drawn in drawing die apparatus as shown by way of example in FIGURES 4 and 5. The drawing die apparatus includes a lower or stationary circular die member 40 adapted to be mounted on the anvil of a punch press and having slidably encircling the same a hold-down ring die member 41 normally spring urged upwardly to at least the elevation of the upwardmost projection contour of the stationary or fixedly mounted central circular die structure 40.

Gperably coactive with the lower die assembly 4t 41 a is an upper reciprocably supported punch die assembly including three relatively and jointly movable portions or sections including a hold-down outer ring die portion 42., a central crown shaping punch die portion 43 and an intermediate dishing die ring portion 44. The press, of course, has means for actuating the upper die assembly relative to the lower die assembly in' drawing and separating strokes, as is customary with dies of this general ty e. a 1 I ln following the steps of the method of the instant invention, the closely dimensioned blank Bis centered upon the lower'die assembly 40, 41, with the margin of the blank lying'upon the upraised hold-down or marginal clamping die ring member or portion 41 as shown in dash' outline in FIGURE 4 representing a section midway between adjacent corners ofthe polygonal blank B. initially, the hold-down ring punch die portion or member 42 is driven under pressure thrustclampingly against the blank margin, thereby causing an annular draw ring rib 45 projecting upwardly from the upper clamping surface of the annular ring die member 41 adjacent to but spaced radially outwardly from the inner periphery of such ring die'member to work the overlying marginal material of the blank into a complementary annular working groove 4-7 in the opposing clamping face of the hold-down ring member 42. As the punch press pressure continues on the hold-down ring die member 42, the marginal portion ofthe blank is carried below the ridge of an annular upstanding dishing and 'drawrib' 48 on the lower fixed die portion 40. As the marginal portion'of the blank is wrapped down about the'dishing rib 48, it is'drawn inwardly over the draw ring rib 45 and reversel'y past a rounded contour annularvdepending draw ring rib 49 on the inner margin of the hold-down face of the hold-down ring die member 42. 'Such drawing of the margin of the blank continues uniformly until a clamping surface 50 on the'inner periphery ofthe hold-down ring 42 runnirig as a continuation of the inner side of the draw ring 'rib 49 and complementary to the radially outer side surface of the dishing rib 48 clamps the interposed drawn "and shaped portion'of the'blank' against the dishing rib.

Duringthis phase of the drawing process, substantial pressure is maintained on the clamped margin sufficient to assure uniform, wrinkle-free work hardening'of the blank margin which, however,"at the completion or" this phase is drawn into its calculated limit, and especially with respect to the narrowest dimensions of the margin with respect to the drawing diameter, that is, at themid-points of the sides of the polygonal blank, as best seen in full lines in FIGURE 4. t

While the marginal drawing and working of the blank is progressing, but preferably close to or at completion of such marginal drawing and working, the central portion of the blank is drawn and worked into'the' crown formation 22, 23 as shown in FIGURE 4, between the central punch die portion 43 and the central portion of the lower die portion 40, which for this purpose are appropriately circularly contoured as shown, with the lower die portion 49 centrally generally depressed orcavitated for the purpose. This causes the central portion ofthe blank to be stretched and drawn and generally work hardened. At the conclusion of-this' central'or crown drawing, an annular undrawn portion of the blankis stretched between the crest of the dishing rib 48 and the central portion of the die assembly wherein the crown portion of the blank is now clamped. Such'stretched intermediate portion of the blank'is under the intermediate punch die portion 44.

As the final step in the initial drawing of the blank, the ring punch member 44 is driven down against'the intermediate portion of the blank so that an annular depending drawing nose portion 51- of the ring punch die'mernber draws the intermediateportion of the blank into-a coinplementary groove 52 in the lower stationary die member 40 shaped to provide the drawn annular rib formation -24 of the cover and to shape the annular 'portion'27 at the radially inner side of the dished portion 25 of the cover.

In shaping the divergent wall flange or panel 2! of the cover, the radially outer side of the dishing and drawing rib or nose 51 of the punch die ring coacts with the radially inner side of the annular upstanding drawing rib 48. In doing so, the marginal portion of the blank is drawn inwardly over the radially outer side of the drawing rib 4S and stretched and work hardened, with the extremity of the marginal flange further drawn in until at the original straight sides of the blank the edge is drawn over the radially outer side of the draw ring or rib 45 as best seen in FIGURE 5.

By reason of the large annular area of the blank margin engaged between the opposin radially outer surface of the draw rib 48 and the drawing punch ring surface 50 as well as between the opposing surfaces of the relatively sinuously shaped draw rib 45 and the draw groove 47 as Well as the draw rib 49 there is a quite smooth, wrinklefree, uniformly work hardening drawing in action over the crest of the upstanding draw rib 48 and into the draw groove 52 incident to drawing, punching action of the annular punch ring 44. The resulting shape of the blank 13 is shown in FIGURE 5. Everything inside of the circular drawn perimeter of the cover shape in the blank, inclusive of the intermediate side edges of the blank which run into such perimeter at E are of the utmost smoothness and uniformity, with the corners of the blank margin having the sides thereof curved toward the intermediate edge portions E, and at least those portions of the corners contiguous the drawn perimeter and which during the drawing were gripped between the hold-down ring die members 41 and 42 remaining substantially smooth and without distortion or strain ripples. In fact, it has been found that even those portions of the corners that remain outside of the perimeter of the hold-down die ring 42 show only quite minor draw strain ripples and actually far less than where the drawing is efiected with a Wider blank so that there is continuous trim material in the margin outwardly from the drawn circular perimeter. This is apparently due to the substantial freedom of the corner material to draw in and attain the curved-in side shape of the corners as depicted.

Following the initial drawing as described, the drawn blank is subjected to further draw press operations, and die shaping to complete the finished cover 15. Upon completion of the cover shape, it is ready for polishing and buifing and plating, as desired, or any other preferred finish.

It will be understood that modifications and variations may be eifected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In drawing die apparatus for shaping flat thin sheet metal blanks of minimal size into smooth wrinkle-free circular wheel cover form, a lower circular die assembly having an outer marginal draw rib projecting upwardly to a substantial height and of convexly curved radial crosssectional contour on its radially outer side and crest, said lower die assembly having radially inwardly from said draw rib a circular forming portion defining with the radially inner side of said draw rib an annular generally V-shaped groove of substantial depth opening upwardly, a clamping die ring member encircling said draw rib and having yieldable means supporting the die ring member normally at an elevation at least as high as the crest of said draw rib so as to receive freely upon the upper surface of the die ring member the margins of a sheet metal blank to be formed; an upper die assembly having a holddown ring axially aligned with said clamping die ring member and engageable therewith to grip the margin of the blank, said hold-down ring having a concave forming surface complementary to the convexly curved radially outer side of said draw rib and being of an inside diameter above said concave forming surface about the same as the diameter of the draw rib crest, the upper die assembly having a central forming portion axially aligned with the circular forming portion of the lower die assembly and of an outside diameter about equal to the inside diameter of said groove, said upper die assembly including a dishing rib punch die ring having a circular nose generally complementary to said groove and being mounted in relative reciprocal relation between and to both of said central forming portion and said hold-down ring of the upper die assembly; and means for actuating said die assemblies for relative sheet metal blank drawing and separating strokes and in a sequence wherein the circular and central portions of the die assemblies are driven into drawing relation to the central portion of the blank and said clamping ring member and said hold-down ring are driven together in blank -margin-gripping relation and axially downwardly relative to said draw rib until said concave forming surface presses the outer marginal portion of the blank onto said radially outer curved forming surface of the draw rib, said actuating means being operative after the central portions and said ring members of the die assemblies have completed their drawing strokes to drive said dishing die ring into said groove to thereby draw the portion of the blank overlying the groove into said groove and work the marginal portion of the blank between said radially outer draw rib surface and said complementary concave forming surface inwardly toward and over the crest of the draw ring.

2. A drawing die apparatus as defined in claim 1, wherein said clamping ring and hold-down ring members have annular complementary draw ring ribs, one of which merges with said concave forming surface, and through and past which the margins of the blank are worked as the marginal portion of the blank is drawn by said dishing die ring between said concave forming surface and said draw rib surface as specified.

References Cited in the file of this patent UNITED STATES PATENTS 294,698 Stiles Mar. 4, 1884 368,526 Fowler Aug. 16, 1887 798,530 Rehfuss et al. Aug. 29, 1905 1,772,914 Rode Aug. 12, 1930 1,838,302 Evans Dec. 29, 1931 1,884,708 Jeneson Oct. 25, 1932 2,064,160 Hochreiter et al. Dec. 15, 1936 2,316,346 Lyon Apr. 13, 1943 2,358,984 Lyon Sept. 26, 1944 2,429,062 Johansen Oct. 14, 1947 2,601,625 Peterson et al. June 24, 1952 2,807,226 Lyon Sept. 24, 1957 OTHER REFERENCES Ser. No. 366,470, Kammerling (A.P.C.) published May 11, 1943.

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