US3344646A - Method for making thin metal sheet tapered receptacles - Google Patents

Description

Oct. 3, 1967 J. 1.. MOL-LER METHOD FOR MAKING THIN METAL SHEET TAPERED RECEPTACLES Original Filed March 15, 1961 FIG.3

2 Sheets-Sheet l INVENTOR JENS L. MOLLER 44M. am-

HIS ATTORNEY J. L. MOLLER 3,344,646

METHOD FOR MAKING THIN METAL SHEET 'IAPERED RECEPTACLES Get. 3, 1967 2 Sheets-Sheet 2 Original Filed March 15, 1961 INVENTOR JENS L. MULLER BY 6M QM FIG."

HIS ATTORNEY United States Patent Cfiiice 3,344,646 METHOD FOR MAKING THIN METAL SHEET TAPERED RECEPTACLES Jens L. Moller, Henrico, Va., assignor to Reynolds Metals Company, Richmond, Va., a corporation of Delaware Original application Mar. 15, 1961, Ser. No. 95,957, now Patent No. 3,182,482, dated May 11, 1965. Divided and this application Oct. 6, 1964, Ser. No. 401,924

Claims. (Cl. 72-348) ABSTRACT OF THE DISCLOSURE This disclosure relates to a method for making cupshaped container bodies from a sheet of metallic foil or the like wherein the sheet of metallic foil is drawn between a female die member having a surface surrounding the cavity thereof and a male punch member which draws the sheet of metal into the cavity to form a cup-shaped receptacle while the outer peripheral portion of the sheet is still being held between a press plate and the surrounding surface of the female die member, the resulting side wall means of the receptacle being continuously stroked by flexible means carried by one of the die members during the drawing of the sheet of material to prevent the formation of wrinkles in the side wall means of the resulting receptacle.

This application is a divisional patent application of its parent copending patent application Ser. No. 95,957, filed Mar. 15, 1961, having issued as United States Letters Patent No. 3,182,482 on May 11, 1965, and assigned to the same assignee to whom this divisional patent application is assigned.

This invention relates to the manufacture of receptacles from relatively thin metal sheets, and is particularly directed to the press drawing of tapered side wall receptacles without the formation of wrinkles. In its more specific aspect it concerns the manufacture of such receptacles from aluminum or aluminum alloys in thin or foil-like sheets.

For the sake of brevity, whenever the word aluminum is used in this application in a broad sense, it is intended to refer to aluminum and its alloys which are proper for this type of manufacture.

When a thin sheet of aluminum or similar metal is rawn into the form of a relatively deep, tapered receptacle, the side wall structure of the receptacle is wrinkled, and particularly so along any curved portions of the side wall structure. One of the reasons for this wrinkling action is that the side wall forming portion of the thin sheet is pulled under tension between the relatively large leading mouth of the die member and the relatively small leading face of the punch member. This pull between the relatively large perimeter of the die mouth and the relatively'small perimeter of the punch leading face inherently produces wrinkles because the larger area of the sheet which surrounds the mouth of the die contracts over the die mouth into the narrower side wall of the receptacle, and becomes wrinkled during such contracting process.

For example, when a relatively thin sheet of aluminum of 0.010 inch thickness is drawn into a substantially square, deep receptacle with rounded corners, and with tapered sides, the side walls are wrinkled, particularly along the rounded corners. As a further detailed example, such a substantially square receptacle has been made, which is 5.830 inches between the top straight inside rim edges, 5.330 inches between the straight bottom edges. The corners are circularly rounded with a radius of 1.000 inch along the rim top, and the depth of the receptacle is 2.25 inches from the top of the rim to the 3,344,646 Patented Oct. 3, 1967 lowest part of the bottom edge. A very pronounced wrinkling etfect has been produced, particularly along the rounded corners, as the flat sheet is pulled down (or up as the case may be) over the rounded mouth corners of the die.

The above indications of size, thickness of sheet, shape and taper of receptacle are given to indicate only in a general way the nature and scope of the invention.

According to this invention, means are provided to prevent the formation of such wrinkles in this general type of receptacle, and it is among the objects of this invention to provide methods and products in which such wrinkling of the side wall of the receptacle is prevented.

Other objects and advantages will become apparent as the description proceeds with reference to the accompanying drawings, in which:

FIGURE 1 is a diagrammatic representation of the die press with the punch and die separated.

FIGURE 2 is a similar view with the punch and die brought together.

FIGURE 3 is a cross section of the receptacle produced by the press of FIGURES 1 and 2.

FIGURE 4 is a perspective view of the receptacle shown in FIGURE 3.

FIGURE 5 is a cross section of another embodiment of the receptacle produced by a similar press.

FIGURE 6 is a top view of the receptacle shown in FIGURE 5.

FIGURE 7 is a top view of a cover for the receptacle of FIGURE 5.

FIGURE 8 is a cross section of the cover shown in FIGURE 7 taken along the line 8-8 of FIGURE 7.

FIGURE 9 is an enlarged cross section of the edge of the cover shown in FIGURES 7 and 8 after the edge has been curled over the edge of the receptacle shown in FIGURES 5 and 6.

FIGURE 10 is a top view of another embodiment of a receptacle which may be produced without wrinkles.

FIGURE 11 is a cross section taken along the line 11-11 of FIGURE 10.

FIGURE 12 is an enlarged cross section of a portion of stacked receptacles and covers of type shown in FIG- URES 5 to 8.

FIGURE 13 is an enlarged cross section along the line 1313 of FIGURE 6.

FIGURE 14 is an enlarged cross section of a portion of FIGURE 2.

FIGURE 15 is an enlarged cross section showing the ring in unfiexed condition.

A drawing die press may include a die member 20 and a punch member 22. Means are provided for moving these members relatively toward and away from each other, such as plunger rods 24, which move the die member downwardly when the punch member is below the die member. As is well known, the members 20 and 22 may be inverted, with the punch above and the die below.

The punch member '22 is surrounded by a press plate 2 6 which is resiliently suported by the rods 28 which pass through the base plate 30 and which engage spring constructions, well known, which move the press plate 26 up to the position shown in FIGURE 1, and allow the press plate 26 to be moved down by the flat surface 32 of the combined press plate and leading die edge plate 34 of the die 20.

The punch 36 is slightly tapered and is secured to an untapered portion or plate 38, which supports the tapered punch 36 on the base plate 30.

A knock out pad or plate 40 is placed in the upper cavity of the die 20, and is actuated by the plunger 42 at the proper time to knock out the receptacle after it has been formed in the press.

The members so far described in connection with the press are shown in dotted lines, since they may be of any Well known construction suitable for the purposes herein set forth.

The press may be of any desired size and may produce receptacles of any desired shape, in accordance with the disclosure of this application. For example, the press of this type may produce substantially square, slightly tapered, receptacles of the shape and size herein shown and described in connection with FIGURES 3 to 6.

The press so far described may be provided with means cooperating with the slight taper of the punch and die members to prevent formation of wrinkles in the sheet being drawn, as it passes over the curved, relatively large leading perimeter 48 of the die mouth, in cooperation with the relatively small curved perimeter 50 of the punch leading face 52.

The means for preventing formation of wrinkles may take the form of a flexible ring 54, made of nylon or Teflon, which is embedded in one of the die or punch members, and which is illustrated as being located in the die member. This ring 54 provides a flexible work stroking surface, which strokes the work or thin sheet blank 56 just after it has been pulled inwardly around the curved perimeter 48 of the die mouth.

Preferably the ring 54 is U-s-haped, with the open end 58 directed in the press closing direction, and with the inner leg 60 being resiliently bendable inward during the drawing operation, as is shown in FIGURES 2 and 14. The ring 54 is embedded in a groove 61 formed in the wall 62 of the die member, which wall would have been gently tapered, as indicated at 63, FIGURE 15, to match the tapered wall 64 of the punch 36, except for the addition of the resilient ring 54. The leg 60 bulges inward toward the center of the die at its open end 58, as shown in FIGURES 1 and 15, extending slightly inward at 45, FIGURE 15, from the tapered surface 46- of the die member, so as to produce the stroking action which eliminates the wrinkles which otherwise would have been produced in the receptacle. One or more radial bores 67 extend to the outer surface of the press and permit air to enter into and discharge from the interior of the ring 54.

In the case of a substantially square receptacle, with rounded corners, as previously described, the flexible ring 54 is particularly effective where it is embedded around the corners of the working faces of the die or punch and where the wrinkling action is particularly pronounced as in the case of such a square receptacle.

The wall of the ring 54 was approximately inch wide at the top 68, 1 inches high along the side 69, A inch thick at each leg 60 and 60a, and inch thick at 6911, FIGURE 15, for the size of receptacle of FIG- URES 3 and 4. The unflexed legs 60 and 60a were 1% inches apart at 58a.

When square receptacles of the character and size hereinbefore described were drawn in a press of the character shown in FIGURES 1 and 2, but without the ring 54, and with the previous solid tapered inner surface of the die, the receptacles had a very pronounced wrinkled construction at the corners. However, when such a press was provided with the flexible ring 54, to embody this invention, then the receptacles drawn by such a press were wrinkle free throughout the entire side wall construction, as well as throughout the remainder of the wall construction of the receptacle. This wrinkle free result was, it is believed, due to the stroking action of the flexible ring 54, which acted upon the receptacle wall immediately after it had been drawn around curved edge 48 of the die mouth.

Receptacles formed by the die drawing press shown in FIGURES 1 and 2 were substantially of the character shown in FIGURES 3 and 4 in which the sheet of aluminum was of 0.010 inch in thickness and was drawn into a substantially square deep receptacle with rounded corners 70 and with tapered side walls 72. The receptacles were 5.830 inches between the straight inside rim edges of the receptacle and were 5.330 inches between the straight bottom edges as indicated by the lines a and b respectively in FIGURES 3 and 4. The corners were circularly rounded with a radius 1.000 inch, as indicated by radius line 0 in FIGURE 4. The depth of the receptacles was 2.25 inches from the top of the rim to the lowest part of the bottom edge as indicated by line d in FIGURE 3. It is understood that, in general use, the receptacle shown in FIGURES 3 and 4 is inverted, so that the rim is at the top instead of at the bottom as shown in the FIGURES 3 and 4.

Receptacles of slightly different shape, with or without covers, can also be drawn with wrinkle free side walls (except where purposely indented) as shown in FIG- URES 5 to 9. The receptacles shown in FIGURES 5 and 6 have substantially the same sheet thickness and dimensions as the receptacles of FIGURES 3 and 4. However, the bottom is tapered slightly upward and is provided with beads or grooves 82 and 84 along the rim and near the center respectively of the bottom. Two pairs of indentations 86 are formed on opposite sides of the receptacles. These indentations make the receptacles easily withdrawn from a stack into which they can be stacked, when each receptacle is rotated 90 alternately as the receptacles are stacked, so the indentations 86 are alternately at different sides of the stock. The die and punch members of the press for producing the receptacles of FIGURES 5 and 6 are substantially the same as shown in FIGURES 1 and 2, except the punch and die members are modified to produce the beads or grooves 82 and 84, the sloping bottom 80, and the indentations 86, as will be apparent to those skilled in the art. The covers 90 shown in FIGURES 7, 8 and 9 are of a size to permit them to be laid over the rims 92 of the receptacles of FIG- URES 5 and 6. The rims 94, of the covers 90, rest on the rim 92 of the receptacles. The rim edge 96 of the rim 94 can be curled around the rim 92 as indicated in FIGURE 9. The covers 90 are provided with a bead or groove 98, slightly spaced from the perimeter of the cover for strengthening purposes. The cover is also drawn downwardly at 99 into the shape of a shallow pan.

The receptacles and covers of FIGURES 5 to 8 can can be stacked, as indicated in FIGURE 12. The stacks of the receptacles and of the covers can be aligned with each other, as shown in FIGURE 12, or they can be placed in separate stacks, as desired.

In the embodiment of FIGURES l0 and 11, the taper of the previously described receptacles is decreased one half, as compared to the taper of the receptacles of FIG- URES 3 to 6. The distance between the straight side rim edges, as indicated by the line f in FIGURE 11, is 5.830 inches, and the distance between the straight bottom edges, as indicated by the line g in FIGURE 11, is 5.580 inches. The bead 82a is substantially similar to the bead 82 previously described, and the indentations 86a are substantially the same as the indentations 86 previously described. There are two pairs of indentations 86a on opposite sides of the receptacle for alternate locations along the sides of the stack, as previously described. Corrugations 100 are formed in the sides of the receptacles for strengthening purposes. Otherwise the shape, dimensions, and sheet thickness are substantially the same as previously described, with the exception of the reduced taper.

In the case of the receptacles shown in FIGURES l0 and 11, and because of the reduced taper of the side walls, the blank before being drawn in the press is coated with a vinyl type of enamel or lacquer of well known type which produces a slippery surface, during the drawing operation. Because of this, the resilient ring 54 can be omitted from the press and the reduced taper and slippery surface provide means for preventing the formation of wrinkles in the material being drawn.

The invention is not limited to the sizes and shapes of the receptacles or to the thickness of the sheet being used, and such sizes, shapes and thicknesses can be varied proportionally with the teachings of the examples given, as will now be apparent to those skilled in the art. Receptacles of many rectangular shapes, as well as oblong, circular and irregular shapes, sizes and wall thicknesses can be used. Depths of receptacle as much as 50% of the horizontal area or the like can be used. The taper can be varied within the teachings of this invention. Many different types of surface lubricants may be used for the embodiments of FIGURES 10 and 11.

While the form of the invention has been shown, as required by the statutes, many other forms can be used, all coming within the scope of the claims which follow.

What is claimed is:

1. The method of preventing the formation of wrinkles during the drawing of a receptacle from a relatively thin sheet of metal which comprises the steps of drawing said sheet between a female die member having a surface surrounding the cavity thereof and a punch member while a press plate cooperates with said surface of said die member to hold said sheet of metal thereagainst with said sheet of metal spanning said cavity whereby said members draw said sheet of metal into said cavity and form a cup-shaped receptacle with the outer peripheral portion of said sheet still being held between said press plate and said surface of said die member, and additionally stroking the resulting side wall means of said receptacle While said receptacle is being drawn between said members by flexible stroking means to prevent formation of wrinkles in said receptacle.

2. A method according to claim 1, in which said stroking is performed by said flexible stroking means being carried by one of said members.

3. A method according to claim 1, tacle is substantially rectangular.

4. A method according to claim 1, in which said receptacle is slightly tapered.

5. A method according to claim 1, in which said receptacle is substantially rectangular and slightly tapered.

in which said recep- References Cited UNITED STATES PATENTS 2,342,858 2/ 1944 Hansen 723 13 3,031,993 5/1962 Gerard et a1 72-465 3,250,419 5/1966 OBrien et a1 221-1 RICHARD J. HERBST, Primary Examiner. R. D. GREFE, Assistant Examiner.

Claims (1)

1. THE METHOD OF PREVENTING THE FORMATION OF WRINKLES DURING THE DRAWING OF A RECEPTACLE FROM A RELATIVELY THIN SHEET OF METAL WHICH COMPRISES THE STEPS OF DRAWING SAID SHEET BETWEEN A FEMALE DIE MEMBER HAVING A SURFACE SURROUNDING THE CAVITY THEREOF AND A PUNCH MEMBER WHILE A PRESS PLATE COOPERATES WITH SAID SURFACE OF SAID DIE MEMBER TO HOLD SAID SHEET OF METAL THEREAGAINST WITH SAID SHEET OF METAL SPANNING SAID CAVITY WHEREBY SAID MEMBERS DRAW SAID SHEET OF METAL INTO SAID CAVITY AND FORM A CUP-SHAPED RECEPTACLE WITH THE OUTER PERIPHERAL PORTION OF SAID SHEET STILL BEING HELD BETWEEN SAID PRESS PLATE AND SAID SURFACE OF SAID DIE MEMBER, AND ADDITIONALLY STROKING THE RESULTING SIDE WALL MEANS OF SAID RECEPTACLE WHILE SAID RECEPTACLE IS BEING DRAWN BETWEEN SAID MEMBERS BY FLEXIBLE STROKING MEANS TO PREVENT FORMATION OF WRINKLES IN SAID RECEPTACLE.

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