US2304582A - Die for drawing sheet metal articles - Google Patents

Description

Dec. 8, 1942. G. A, LYON 2,304,582

DI'E FOR DRAWING SHEET METAL ARTICLE Original Filed March 26, 1940 5 Sheets-Sheet l gag-TE Geosw: 1444mm? Ira/v.

Patented Dec. 8, 1942 2,304,582 DIE FOR DRAWING SHEET METAL ARTICLES George Albert Lyon, Allenhurst, N. J.

Original application M arch 26, 1940, Serial No.

326,037. Divided and this application September 16, 1940, Serial No. 356,960

1 Claim.

This invention relates to an automobile wheel construction and, more particularly, to a die for drawing a wheel cover or hub cap.

The subject matter of this application constitutes a division of my copending application .Serial No. 326,037, filed March 26, 1940.

An object of this invention is to provide an improved and member or hub cap for an automobile wheel.

Another object of this invention is to provide improved die construction for making an automobile wheel hub cap in such a way that there will be less waste of metal than heretofore.-

Another object of this invention is ,to provide an improved die for making an automobile wheel hub cap or cover in such a manner that fewer operations are required in the fabrication of the article.

In accordance with the general features of this invention, there is provided a drawing die for forming a hub cap, and whereby the hub cap is first drawn to an intermediate form having a crown portion surrounded by a cylindrical wall; the free edge of the cylindrical wall being then trimmed to eliminate any irregularities produced by the drawing operation and then curled to form a beaded edge. The die also includes mechanism for bulging out the portion of the cylindrical wall next to the crown portion to give the hub cap its final shape and in which final operation the beaded edge is positively prevented by means in the die from being drawn into an irregular shape so that no additional straightening or trimming operations are necessary.

In previous drawing apparatus for making hub caps of the type to which this invention relates, it has been the practice to perform the bulging out operation before curling the edge of the metal and without preventing the formation of irregularities in the edge of the metal. As a consequence, it has heretofore been necessary to perform a second trimming operation after the bulging operation and before the curling of the edge of the metal into a bead. The present die construction eliminates any such second trimming operation.

Other objects and features of this invention will more fully appear from the following detailed description taken in connection with the accompanying drawings which illustrate several embodiments thereof, and in which:

Figure 1 is a fragmentary vertical cross sectional view taken through a wheel construction showing my novel wheel hub cap applied thereto;

simplified die for drawing a cover.

Figure 2 is a front view, on a reduced scale, of the construction shown in Figure 1;

Figure 3 is a cross sectional view taken through a metal blank after it has been subjected to the first operation performed by my novel drawing die;

Figure 4 is a cross sectional view illustrating a further operation that is performed on the wheel cover shown in Figure 3 by my novel die construction;

Figures 5, 6, '7, 8, and 9 are fragmentary cross sectional views illustrating progressive or successive steps performed by my novel die in the formation of the hub cap shown in certain of these views also illustrating the apparatus employed in performing the steps or operations;

Figure 10 is a fragmentary cross sectional view similar to Figure 5 showing a modified form of apparatus for performing the operation illustrated in Figure 5; and

Figure 11 is a cross sectional view through a die set and blank of my present invention for carrying out the initial step in the formation of the hub cap when it is desired to make a hub cap without simultaneously making a wheel cover disk.

As shown on the drawings:

The reference character ill designates generally a conventional drop center tire rim, including the usual side flanges II and a base flange l2, to which is riveted, welded, or otherwise secured, a spider or body member l3 which has a central depression or bolt access opening l4, defined by a lateral wall l5 terminating in a bolt flange Hi. This bolt be secured in the usual way, such as by cap screws or bolts, to a suitable circular support or hub of the automobile.

As is well known to those skilled in the automobile wheel art, it is common practice to provide a detachable closure member for concealing these bolts. A closure or cap member constructed in accordance with the features of this invention is shown in Figures 1 and 2 and is designated generally by the reference character 26. The closure member, as I shall describe more in detail hereinafter, is adapted to have a snap-on coaction with a plurality of lateral projections or bumps IS on the wall l5 of the wheel body part I3. These projections may, if it is so desired, be attached to this body part, although the preferable way of providing them is to depress spaced portions Figures 1 and 2,.

flange I6 is adapted to of the body part at the time that the body or spider part is being fabricated.

Each of these projections I3 is of relatively narrow width and of a predetermined height for coaction with a flexible skirt 2| on the hub cap or cover member 20. While any suitable number of projections may be used, I have found that satisfactory results may be obtained by using four equidistantly spaced projections.

The hub cap is made from a single sheet or piece of metal and, in addition to the skirt 2 I, includes a dome or crown portion 22 connected to the skirt 2| by a turned under margin 23, which defines a shoulder adapted to seat on the outer face of the wheel body member l3, as shown in Figure 1. Also, the innermost extremity or edge of the flexible skirt 23 is curled into a small wirelike bead 25 for enhancing the tension of the rear edge of the cap, particularly when this edge is sprung into hub cap retaining cooperation with the spaced projections IS.

The dome portion 22 of the hub cap is resilient to the extent that it is like a spring in that it is capable of resisting impact blows and, moreover, will enable slight indentations therein to be snapped or pressed outwardly by manual pressure on the inner side of the indentation.

The skirt 2|, by reason of its extending in a generally axial direction, has its greatest flexibility at its inner edge 25. Moreover, when this skirt is in a sprung condition on the wheel, it does not materially affect the remaining portions of the hub cap by reason of the fact that it emanates from a shoulder 23 on the cap which is held and seated tightly against an outerface of the wall of the body part |3.

The shoulder 23 is between the flexible dome and flexible skirt and by reason of its being located at the turned and channeled section of the margin of the cap is relatively rigid o that it can withstand without distortion or buckling the pressure of a pry-oil tool inserted between the edge of the shoulder and the adjoining wheel body. In the application of the hub cap to the wheel, it is flrst brought to a position in which the bead 25 rests against the protuberances l9 at points spaced axially outwardly of the final point or contact between the bead 25 and the protuberances IS. The hub cap is then forced bodily axially inwardly and snapped into place, the portions of the bead 25 in contact with the protuberances i9 and the adjacent portions of the skirt 2| of the hub cap are deflected radially inwardly during this operation, while the intermediate portions of the head 25 and skirt 2| spring radially outwardly. In its final position, shown in Figure 1, the head 25 and the skirt 2| of the hub cap are in the above described flexed position, thereby tightly and flexibly binding the edge under tension to the body part of the wheel so as to detachably retain the hub cap on the wheel. This coaction is of such a magnitude that it requires the use of a pry-off tool, such as a screw driver, as well as considerable pressure. to remove the cap from the wheel; this removal being effected by inserting the edge of the screw driver between the relatively rigid lateral shoulder 23 of the cap and the wheel body member l3, and prying the cap outwardly.

The wheel construction, as illustrated in Figure 1, is also provided with a wheel cover disk 21 having an inner part 23 overlying the wheel body I3 and an outer part 23 overlying a portion of the rim III. The wheel cover disk 21 is retained in place on the wheel by its axially inner edge which fits in under and is secured by the turned-under margin 23 of the hub cap 20. If desired, the wheel cover disk 21 may also be held in place by. a frictional engagement of its outer marginal edge 30 with the axially inner surface or the side flange H of therim l0.

In Figures 3 to 8 of the drawings, I have illustrated the novel operation in the making of the hub cap 20 and the wheel cover disk 21 illustrated in Figures 1 and 2. More particularly, both the hub cap 20 and the wheel cover disk 21 are blanked from a single piece of metal stock 32. The first operation in the forming of the hub cap 20 and the wheel disk 21 comprises taking a circular blank of suitable size and drawing it by one or more operations into the shape shown in cross section in Figure 3. It will be noted that this shape comprises a central rounded crown portion 33 joined by a cylindrical wall portion 34 to a wide rim or disk portion 35. The wall portion 34 has the same diameter as the skirt portion 2| of the finished hub cap, and the outer rim or disk portion 35 has approximately the same outside diameter and the same general configuration as the finished wheel cover disk 21.

After the blank 32 has been formed to the shape shown in Figure 3, it is divided into two parts by being out along a circle whose position is indicated in Figure 3 by the lines 36. The diameter of this circle is the same as the inside diameter of the finished wheel cover disk 21, and the wheel cover disk 21 is completely formed by shaping the severed disk portion to the flnal form shown in Figure 4.

The central portion of the partially formed blank shown in Figure 3, this central portion comprising the crown 33, the cylindrical wall 34, and the radially inner part of the disk 35 lying between the lines 33, is subjected to further operations and finally forms the finished hub cap 20. If it is desired to produce a hub cap 20 without producing a wheel cover disk 21, a circular sheet metal blank 31, considerably smaller than the blank 32 may be employed in making a partially formed hub cap similar to the central portion of the partially formed hub cap and wheel cover disk shown in Figure 3. In carrying out this alternative procedure, the blank 31, as shown in Figure 11, is placed in a suitable die set comprising a die 38, a punch 39, and a blank holder 40 connected to the punch by suitable springs 4|. The die 38 is formed with a central recess 42 into which the punch 39 is adapted to draw the blank 31, and the die 38 and the blank holder 40 are provided with a circular tongue 43 and groove 44 concentric with the recess 42 of the die. The tongue 43 and groove 44 provide a tortuous passage through which the edge of the blank 31 is drawn. This serves to more effectually hold the edge of the blank 31 and also to cold work, to an additional extent, that portion of the blank being drawn through the tortuous passage and to thereby enhance its physical. properties. When the stroke of the punch 39 is completed, the blank 31 has been drawn to the shape indicated by the dotted line 31' and has substantially the same shape as the portion of the member shown in Figure 3 and lying between the lines 36.

The partially formed hub cap, made by either of the operations described above, is then subjected to a further drawing operation, as illustrated in Figure 5. Figure 5 shows a portion of a die set generally similar to the die set shown in Figure 11 in that it comprises a die 46 having a central circular opening 41, a punch 43, and an annular blank holder 49 fitting around the punch 48 above the die 46. Since both sides of the die set are alike, one side only is illustratedin Figure 5. The principal differences between the die set illustrated in Figure 5 and the die set illustrated in Figure 11 are that, in the former die set, the aperture 41 inthe die 46 extends clear through the die so that the piece being worked upon can be discharged through the opening, and in that the blank holder 49 is provided with a lip 56 which is adapted to extend down into the die 46 inside of the cylindrical wall 34 of the blank being worked upon. It will be noted that the blank is formed with a fillet portion 45 between the cylindrical wall portion 34 and the relatively fiat rim portion 35 and that the fillet 45 is securely held, both on the outside and the inside, by the die 46 and the lip 50 of the blank holder 49.

The operation which is performed in the die set illustrated in Figure 5 consists of drawing all of the metal in the fillet 45 and in the flange 35 into an extension of the cylindrical wall 34, the metal being guided throughout its entire movement into the cylindrical wall formed by means of the die 46 and the blank holder 49. The movement of the metal is, of course, caused by the downward movement of the punch 48 in the conventional manner.

After the operation performed in the die set shown in Figure 5 has been completed, the blank has the shape shown in cross section in Figure 6 and consists entirely of a crown portion 33 and a cylindrical wall portion 34. The next operation is to trim the edge of the wall portion" 34 to exactly the proper length by making a cut 5| at the proper place. The cut 5| removes a small strip of waste 52 from the rim of the cylindrical portion 34 and eliminates any variation in length or irregularities in the edge of the work piece 3334.

The next operation in the formation of the hub cap is the curling of the edge of the cylindrical wall portion 34 to form a bead 22. This operation is carried out with a curling punch 53 and die-54 having the configuration shown in Figure 7. The edge of the cylindrical wall portion 34 is forced by the die 53 into an annular round bottomed roove or trough 55 in the die 54 and is thereby forced to curl around and form itself into the bead 22.

The next operation in the forming of the hub cap consists of bulging out the portion of the cylindrical wall 34 adjacent the crown portion 33 in order to form the edge portion of the dome 22 and the turned-under margin 23 of the finished hub cap shown in Figure 1. This operation is performed by the die setillustrated in Figures 8 and 9. This die set comprises an upper die member 55 whose under surface is formed with a round hollow 56 having the shape of the dome portion 22 of thefinished hub cap, a central lower die member 51 having its upper end shaped and positioned to hold the center of the crown portion 33 of the partially completed hub cap against the center of the hollow 56 in the upper die member, a plurality of outer lower die members 58 which together form a ring adapted to fit around the cylindrical wall portion 34 of the partially formed hub cap, a rubber expander 59 in the form of a ring fitting around the upper part of the central lower die member 51 and shaped to flt against the outer part of the crown portion 33 and the upper part of the wall portion 34 of the partially completed hub cap, and an annular outer lower die members 51 and 58 immediately below the rubber expander 59. It will be noted that the outer lower die members 58 are formed with an undercut 6| on their inner surfaces, this undercut accommodating the bead 22 and terminating in a shoulder 62 near the top. When the partially formed hub cap 333422 is placed in the dies, the bead 22 on its lower edge lies some distance below the shoulder 62 on the outer lower die members, as shown in Figure 8.

The die set shown in Figures 8 and 9 is operated by forcing-the upper die member 55, the central lower die member 51 and the outer lower die members 58 downwardly with respect to the compressor 60. This forces the rubber expander 59 down onto the compressor 60 and, since rubber is practically incompressible volumetrically, causes the expander 59-to bulge out laterally as shown in Figure 9. This bulging forces the upper portion of the cylindrical wall 34 out into the peripheral portion of the hollow 56 in the upper die member 55 and draws the bead 22 up against the shoulder 62 on the outer lower die members 58. The pressure applied is sufficient to pull the mad 22 up tightly against the shoulder 62 around its entire circumference. If any portion of the bead 22' should pull up against the shoulder 62 before any other portion, that first portion is stopped and prevented from pulling up further by the shoulder 62 until the other portions are pulled up into line. Thus, the bead 22 is formed compressor 66 fitting between the central and into a perfect circle irrespective of any small irregular ties that may occur during the drawing operation. This completes the formation of the hub cap 20, with the exception, of course, of such operations as polishing and embossing or painting ornamental or identifying features.

An alternative set of dies 64-65-66, shown in Figure 10, may be employed for carrying out the operations performed'by the dies shown in Figure 5. This alternative set of dies comprises an annular lower die member 64, a punch 65, and an annular blank holder 66 adapted to fit around -the pun h 65 and on top of the die 64. The die set 6465-66 is generally similar to the die set shown in Figur 5, but the lip 61 on the lower inner corner of the blank holder 66 is considerably th nner than the corresponding lip 50 on the other die set. This allows the side of the punch 65 to be made straight and of a constant diameter instead of having the upper portion of reduced diameter, as is the case with the punch 48 in the die set shown in Figure 5.

From the foregoing, it will be seen that I have provided a die for producing hub caps and wheel cover disks or for producing hub caps alone wh ch performs with less waste of material and fewer operations than previously known dies for producing these articles. It will therefore be apparent that my invention brings about a substantial reduction in the manufacturing cost of these articles. While I have disclosed only one principal way of carrying out the invention and two modifications thereof, it will, of course, be understood that I do not wish to be limited thereto. since many modifications may be made, and I, therefore, contemplate by the appended claim to cover all such modifications as fall within the true spirit and scope of my invention.

I claim as my invention:

A die set for drawing a sheet metal article, said die set comprising a die having an upper blank holding surface and a vertical surface connected to said blank holding surface by a fillet, a blank holder above said die and adapted to cooperate therewith to hold a blank on said blank holding surface. said blank holder having a lip extending down around said fillet and adapted to cooperate therewith for confining a fillet portion of said blank within a curved space having the same thickness as said blank, said lip having a substantial thickness at the bottom thereof and one side of said lip forming a continuation of one side of said blank holder, and a punch having a portion slidabie against said side of said blank holder and a portion extending under said lip and spaced from said die a distance equal to the thickness of said blank.

GEORGE ALBERT. LYON.

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