US2176738A - Method and apparatus for making metallic receptacles - Google Patents

Description

Oct. 17, 19 39. w, LARK 2,176,738

METHOD AND APPARATUS FOR MAKING METALLIC RECEPTACLES Filed Nov. 7, 1935 :s Sheets-Sheet 1 .17, 1939. w, CLARK 2,176,738

METHOD AND APPARATUS FOR MAKING METALLIC RECEPTACLES Filed Nov. '7, 1935 3 Sheets-Sheet 2 w/Q M/M ww mm. mm

INVENTOR 3 Sheets-Sheet 5 H. W. CLARK METHOD AND APPARATUS FOR MAKING METALLIC RECEPTACLES Oct. 17, 1939.

Filed Nov. '7, 1935 I Patented Oct. 17, 1939 PATET orice METHOD AND APPARATUS FOR MAKING METALLIC RECEPTACLES Harold W. Clark, Alliance, Ohio, assignor to The Steel Sanitary Company, Alliance, Ohio, a corporation of Ohio Application November '1, 1935, Serial No. 48,664

' m I 4 Claims.

This invention'relates to the manufacture of metalreceptacles and,'in particular, to receptacles made by the deep drawing of sheet steel.

' The invention will be disclosed as applied to the 5' manufacture of bath tubs from sheet steel, but it will be apparent that other articles of like nature may beproduced by the same method and apparatus, or with only slight modifications thereof.

, While it has been proposed heretofore to make bath tubs by deep drawing a single steel sheet,

. so far as I am aware, this result has never been obtained commercially, at least on a practical basis. ."While it is probably possible to draw a tub of conventional design from a single steel sheet, the amount of waste involved by the excessive scrap produced is so great as to rule out this possibility commercially. It has also been proposed heretofore to produce bath tubs by forming a plurality of tub sections and welding them together. This method has not met with wide success because of the cost of welding the several joints and the problems introduced by the necessity for enameling thereover.

I haveinvented a method of making bath tubs by joining only two sectionsby a circumferential seam or joint. This reducesthe amount of welding necessary to a minimum. The invention also makes it possible todraw the two tub sections fromsingle sheets without forming an excessive amount of scrap, In accordance with my invention, I ,draw'a steel sheet through a suitably shaped die ring by'means of a punch press and restrain the flow of the metal adjacent the edge of' the sheet over the draw ring to insure proper shaping of the resulting section without the formation of wrinkles, folds or scratches. A

present preferred embodiment of the invention and a preferred practice thereof are illustrated 40 in the accompanying drawings, although it is to be understood that the invention may be otherwise embodied and practiced within the scope of my broader claims. In the drawings:

Figure l is a longitudinal sectional View through the punch and die of my invention;

Figure 2 is a transverse sectional view thereof;

Figure3 is a plan view of the draw ring;

Figure 4 is .a longitudinal sectionthrough the tub section produced by the apparatus of Figures 1 through 3;

' Figure 5 is a view similar to Figure 1 showing the apparatus for forming the other tub section;

and

' Figure 6 is a side elevation of the two sections ready tobe joined together by welding.

bolster adapted to support the dies through 10' which the sheet is drawn, and at least two vertic'ally movable slides adapted to operate in succession.

A bottom spacer H), which is a box-shaped casting open at the top and bottom, is adapted to rest on the bolster. The plane of the upper surface thereof is indicated by the line H. A draw ring I2 is secured to the bottom spacer 10. As best shown in Figure 3, the draw ring is substantially rectangular in outline and has an opening 13 therein rounded at one end, the edge of the opening being curved at the sides and rounded end thereof, as shown at M. The upper surface of the draw ring I2 is provided with ribs, tongues or splines [5 extending along the sides and rounded end of the opening 13. The purpose of these splines will become apparent as the description of the appartus proceeds.

A pressure pad I6 is reciprocable within the bottom spacer ill by means of pneumatic cylinders I? having pistons 18 slidable therein on which the pad rests. The supply of air to the cylinders I1 is controlled by any suitable form of valve, indicated diagrammatically at I9. The

upper surface of the pad I5 is concave, as shown at 20, to assist in shaping a metal sheet being drawn to the final contour desired in the finished product. The pad l6, adjacent the right-hand end as shown in Figures 1 and 3, is provided with a transverse groove 21, the purpose of which will be explained shortly.

A blank holder ring 22 is mounted on one of the slides of the press, specifically that which descends first. The slide on which the blank holder ring is supported is indicated diagrammatically at 23 in Figure 2. The blank holder ring is simply a heavy plate or slab with an opening therein conforming generally to the outline of that in the draw ring 12. The undersurface of the blank holder ring has grooves 24 therein 5 adapted to overlie the ribs or splines 55 on the draw ring l2. It will be apparent that if a steel sheet is laid across the draw ring i2 while the blank holder ring 22 is elevated, the cooperating ribs or splines and grooves will serve to grip the 5 Since 8 sheet 30 adjacent its edges.

edge of the plate, as indicated in Figures 1 and 2 and retard flow of the metal sheet therebetween as the central portion thereof is pressed inwardly and downwardly.

A punch 25 is mounted on an extension 26 secured to the other slide of the press, viz., that which descends last. The punch 25 is shaped to produce the desired contour of the finished tub section. A removable plate or shoe 2'! is secured to the lower face of the punch to. permit the latter to be employed for making tub sections of different lengths. This feature is disclosed and claimed in my copending application Serial No. 260,577,-filed March 8, 1939, which application is a division of this application. The plate 21 has a rib or spline 28 adapted to cooperate with the groove 2| in the pad "5 for the same purpose as the ribs and grooves in the draw ring and blank holder. It will be observed that the sides of the punch are convex outwardly, as shown at 29. The resulting tub section has a similar contour which is desirable in that it prevents reverse buckling such as is experienced due to expansion and contraction when enameling a tube having a flat or plane side wall. By curving the side wall of the tub, any bucking that may occur takes place in one direction only and is not reversible, with the result that the enamel coating is not fractured. This feature is disclosed and claimed in my copending application Serial No. 260,576, filed March 8, 1939, which application is a division of this application.

The operation of the apparatus already described will probably be apparent but will nevertheless be reviewed briefly. The toggle press is first operated so as to withdraw the punch 25 and the blank holder ring 22. A steel sheet, such as that shown at 30, is laid across the draw ring l2. The press is then operated so as to cause the blank holder ring 22 to descend and grip the The pad I6 is then raised to the position shown in chain lines, by manipulation of the vlave 13. The press is then operated so as to cause the punch 25 to descend and progressively shape the sheet from the flat condition, through the intermediate stage shown in dotted lines in Figure 1, to the final form shown in solid lines in Figure 1. As the punch descends and deforms the sheet, the edges and central portion thereof are stretched and deformed and there is actually some flow of the edges of the sheet between the draw ring and the blank holder ring. The cooperating splines and grooves on these parts, however, limit the inward flow of the sheet edges so that the deformation caused by the parts is largely taken up by the elongation of the central portion of the sheet. This makes it possible to employ as drawing stock a fiat sheet having the minimum dimensions sufficient to form a tub so that the waste due to scrap is correspondingly reduced. At the same time, the center portion of the blank is smoothly shaped to the desired contour. The pad I5 assists in giving the proper form to the finished tub section, being depressed against the air pressure in the cylinders IT by the punch 25 as the latter descends. The spline 28 and the groove 2! act in the same manner as the splines and grooves on the draw ring and blank holder ring, to limit flow of the sheet longitudinally of the punch and pad. While some flow occurs, the deformation is permitted largely by the stretching of the center part of the sheet.

The finished tub section on removal from the 4. The end of the section is then trimmed off along the chain line 3| and the edges of the section sheared and flanged upwardly as shown The method and apparatus above described, with some slight modification, may also be employed to form the drain end of a tub such as indicated at 33 in Figure 6, the finished bell end being shown at 34 in the same figure. Figure 5 illustrates the apparatus which I prefer to employ for forming drain ends for tubs. This apparatus corresponds generally to that of Figures 1 through 3, including a bottom spacer 35, a draw ring 36 secured thereto, a pad 31 reciprocable within the spacer 35 on pneumatic cushions, a blank holder ring 38, a punch 39, anda punch extension 4!]. The draw ring 36 is similar to that shown at I2 but is of substantially U-shape in plan, being open at one end. The blank holder ring is closed and the punch extension 40 is recessed at 4| to receive the inner cross member thereof. The draw ring and blank holder ring are provided with splines and grooves 42 and '33, as already described. The punch 39 differs from the punch 25 so as to givethe finished drain end of the tub the proper shape. The pad 31 is provided with a filler 44. The inner end of the punch, furthermore, is inclined as at 45. As

a result, the inner end of the blank or flat sheet is bent upwardly around the inclined end of the punch. This construction of the pad filler and punch serves the same purpose as the rib 28 and groove 26 of the punch and pad of Figure 1 except that the construction of Figure 5 exerts a greater force restraining flow of the metal stock around the punch.

The operation of the modified'form of apparatus shown in Figure 5 is similar to that already described, the only difference being that the center portion of the inner end of the sheet of stock is bent upwardly around the punch as the latter initially engages the sheet. On'removal at 46. I find that this method prevents fracture of the metal which occurred when it was attempted to deform the material surrounding the hole before punching the hole itself. This feature is disclosed and claimed in my copending application Serial No. 260,575, filed March 8, 1939', which application is a division of this application.

While it is quite possible to form tub sections in a single pressing operation as described above, I have found that the operation can be somewhat facilitated by making it in two stages and annealing the partly formed sections after the first operation at a temperature of between 1300 and 1400" F.

After the tube sections shown in Figure 6 have been produced, they are ready for joining, for example, by electric welding and, after the welded joint has been ground down, the finished tub can be enameled in the usual manner.

It will be apparent from the foregoing description that the invention provides a simple and highly practical method of making tubs or other similar receptacles from flat sheet metal by forming two sections each in a single operation if desired, and joining them together. As before stated, the method and apparatusdisclosed make possible the accomplishment of this result with a minimum of scrap material and dies, thus reducing the cost of the finished product.

Although I have illustrated and described but one preferred embodiment of the apparatus and practice of the method, apparatus and procedure other than that described may be employed without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. Apparatus for making an open ended receptacle blank comprising a die ring, a punch reciprocable therethrough, a yieldable pressure pad against which said punch is adapted to advance, and a filler on the pad efiective in cooperation with the punch to bend the edge of a sheet adapted to form the open end of the blank at an angle to the bottom thereof.

2. Apparatus for drawing a sheet metal receptacle blank having an open end comprising a "draw ring, a punch re'ciprocable therethrough,

and means for bending upwardly the edge of a sheet adjacent the portion thereof adapted to form the bottom of said blank at the open end,

7 said means including a yieldable pressure pad against which the punch is adapted to advance, whereby to restrain inward slippage of said edge.

3. In a method of making an open-ended blank adapted to constitute one end of a receptacle such as a bath tub, the steps including drawing a substantially flat sheet through a draw ring, after bending the edge of the portion of the sheet adapted to form the bottom of the blank at the open end thereof at an angle to the general plane of said bottom, gripping the bent edge to limit slippage thereof, and restraining slippage of the metal adjacent the other edges of the sheet to a lesser degree.

4. Apparatus'for drawing a sheet metal blank having an open end adapted to form one end of a receptacle such as a bath tub, said apparatus comprising a draw ring, a punch reciprocable therethrough, a pressure pad within and below said ring and cooperating with said punch as the latter advances through said ring, and a filler on said pad so disposed relative to said punch as to bend upwardly the edge of the portion of a sheet adapted to form the bottom of the blank at the open end thereof to a substantial angle to the general plane of said bottom.

HAROLD W. CLARK.

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