US2297625A - Forming die - Google Patents

Description

FORMING DIE Filed Nov. 1, 1959 MIL 5 Rn Y fiww N 2 fm m J Patented Sept. 29, 1942 FORMING DIE Edwin H. Kotcher, Detroit, Mich., assignor to The Murray Corporation of America, Detroit, Mich., a corporation of Delaware Application November 1, 1939, Serial No. 302,419

3 Claims.

My invention relates to forming dies for sheet metal, and particularly to a set of dies employed for drawing a sloping surface in a recessed element, more particularly, the sloping surface at one end of a bathtub.

In the pressed metal art for working sheet metal to produce a bath tub, difllculty has always been experienced when attempting to produce a sloping end on the wall of the tub. Dies have been designed heretofore which telescope longitudinally of each other for attempting to produce a sloping tub end as the die was moved downwardly. The concentration of the large downward pressure at the corner of one of the die sections which was to be moved normal thereto would cause tremendous unit pressure which would overwork the metal being drawn, thereby producing thin, distorted, and ruptured walls. It was for this reason that sheet metal bath tubs were produced with vertical walls at both ends, or were made of two or more stampings which were welded together.

In practicing my present invention, I construct a female die portion, the contour of the entire bottom of which is formed to the shape of the bottom of the tub to be drawn. At the end of the male die portion which is to form the sloping surface, I provide a slide disposed angularly to the downward path of movement of the die and to the sloping surface to be produced. The end of the slide is projected downwardly to be substantially in the plane of the lower comer of the die body. Resistance means, such as fluid, springs, and the like, may be employed to offer resistance against retractive movement of the slide conforming to the amount of pressure required to produce the drawing operation. Adjustable means regulates the pressure so that no more than the amount of energy required to actually draw the metal is utilized in retaining the slide against the retractive movement. In view of the slope of the slide at an angle to the downward movement of the die body and at a favorable angle to the slope of the tub Wall, the pressure required to retract the die is materially reduced over that when the die is divided to be moved normal to the movement of the die during the drawing operation.

Accordingly, the main objects of my invention are: to provide a set'of dies which efliciently draw metal to form a receptacle having a sloping end; to provide a male die for drawing a recess in a metal sheet which has a slide in one end which is retractable in a path at an acute angle to the path of movement of the die; to provide a male die for drawing a recess in sheet metal having the shape of said recess, and having one end wall mounted as a slide, at an acute angle to the path of the die movement and the sloping surface, for producing a sloping surface in the wall of the recess; to dispose a slide in one end of a die at an acute angle to the path of movement to the die and provide resistance means for opposingthe slide retraction as the die is moved downwardly to perform a drawing operation, to provide an adjustment for the resistance means of the slide so as to vary the pressure of the slide during its retractive movement; and in general, to provide a set of dies for drawing sheet metal to form a receptacle, having a sloping side, such as for a bath tub, which is simple in construction, positive in operation, and economical of manufacture.

Other objects and features of novelty of my invention will be either specifically pointed out or will become apparent when referring, for a better understanding of my invention, to the following description taken in conjunction with the accompanying drawing, wherein:

Figure l is a sectional view of a set of dies for drawing a recess in a sheet of metal, embodying features of my invention;

Fig. 2 is a sectional view of the die set illustrated in Fig. 1, taken on the line 1-! thereof;

Fig. 3 is a plan view of the die set illustrated in Fig. 1; and,

Fig. 4 is a sectional view of the stamping drawn by the die set illustrated in the foregoing figures.

While the principle of operation of the set of dies embodying my invention may be employed in any metal drawing operation for forming a receptacle having a sloping side wall, for the purpose of illustration the die set hereinafter described is employed for drawing a sloping wall in one end of a sheet metal bath tub. The female die ID is recessed to conform to the shape of the tub while the male die II has the bottom surface l2 and rear surface I3 shaped to mate with the recess in the die It. A slide I4 is mounted in the male die II, the lower edge of which is disposed above the corner [5 of the die body.

illustrated in Fig. 1, the end 22 of the slide is substantially in the plane of the corner 23 of the die H so that upon the initial drawing of the metal the two corners operate simultaneously.

The female die III is preferably bolted to the base of a press, while the male die II is bolted to the movable head thereof. A clamping block 24 has an aperture 25 through which the die H operates and suitable pressure means, not herein illustrated, forces the block downwardly upon the initial movement of the head against the edges 26, of the metal sheet to securely clamp the sheet before the corners 22 and 23 of the die H contact and begin the drawing operation. The slide II on the end of the dies ll produce the drawing of the metal forming the sloping wall 21 of the tub. The angular position of the slide is such that a minimum amount of resistance is offered to its retractive movement against the pressure of the spring I8 as the die H moves downwardly. This angular position is the resultant of the direction of the path of movement of the die and the direction of the slope of the wall of the tub.

By providing a pressure a fluid, spring pressure, or the like, which is adjustable, the proper While I have illustrated the die as having a slide which is spring pressed, it is to be understood that a cylinder and piston may be employed, or other means utilized. for controlling the amount of pressure on the slide. Suitable valves may be employed for regulating the fluid pressure so that the resistance offered to the retra-ctive movement of the slide may be accurately adjusted. By having the toe I 5 of the male die ll form one corner at the bottom of the tub, the shape of the tub is accurately duplicated and strain is thereby eliminated from the end 22 of the slide. A further advantage of employing a slide above the end I5 of the die resides in the open space provided about the slide which permits the air, which would otherwise be trapped, to escape from between the sheet of metal and the male die. It was necessary heretofore to provide vent openings in similar large dies to relieve the pressure of air built up ahead tub and hence avoids an objectionable gap in the die set at the sides of the tub beyond the inner end of the slide, which would otherwise result if the angle of inclination were not sufllcient to enable the inner end of the slide to clear the top of the opposite end of the tub. It will be obvious that, in order to simultaneously iron the entire periphery of the tub, the angle of movement of the slide from the vertical must at least equal, but be opposite to, the angle of inclination of the end wall of the tub from the vertical.

While I'have described and illustrated but a singl embodiment of my invention, it; will be apparent to those skilled in the art, that various changes, omissions, additions, and substitutions may be made therein without departing from the spirit and scope of my invention, as set forth in the accompanying claims.

What I claim is:

1. A set of dies relatively movable vertically for drawing a bath tub having a sloping end wall, including, a female die having a recess the shape of the outer contour of the tub, a male die corresponding in shape to said tub except for the sloping wall portion which is recessed, a sloping wall die portion mounted in the recess of the male die for movement at an angle disposed between a normal to the sloping wall and an angle to the vertical substantially equal to that of the sloping wall but on the opposite side of the vertical from the sloping wall.

2. A set of dies relatively movable vertically for drawing a bath tub having a sloping end wall, including, a female die having a recess the shape of the outer contour of the tub, a male die portion corresponding in shape to said tub except for the sloping wall portion which is omitted, a sloping wall die portion for said male'die, means for mounting said die portion on said male die for movement at an angle disposed between an angle to the vertical substantially equal to that of the sloping wall on the side of a vertical away from the sloping wall and an angle from the horizontal formed by a line extending from the bottom edge of the sloping wall of the tub to the top edge of the opposite end of the tub.

3. A set of dies for drawing a bath tub having side walls and a sloping end wall extending between said side walls, including, a female die having a recess the shape of the outer contour of the tub, a male die corresponding in shape to said tub except for the sloping wall portion which is recessed, and a sloping wall die portion of the full width of said sloping wall and mounted in the recess of the male die for movement at an angle to the direction of movement between the male and female dies, said angle and the length of the sloping die portion being such that the entire end opposite to the end which engages the sloping wall extends beyond the top edge of the tub at the end of the drawing operation, and said angle being opposite to and at least as great as the angle of said sloping wall from said direction of movement.

EDWIN H. KOTCHER.

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