US1893951A - Sheet metal press - Google Patents

Description

OI KUHNER SHEET METAL PRESS Filed Sept.

Jan. 10; 1933.

Patented Jan. 10, 1933 UNTED STATES OTTO K'HNER, OF GOPPINGEN, GERMANY SHEET METAL PRESS Applicatiomfiled September 3, 1930, Serial No.

My invention relates to sheet-metal presses, and more particularly to the blank holders of such presses. In my copending ap lication for patent of the United States, erial No. %48,676, filed April 30, 1930, I have described a press in which the blank holder is tted to slide in a cavity of the drawing slide against the action of an air cushion, as shown in Fig. 2 of my' said copending application. lt is an object of my invention to so design a device of this type that it is suitable for presses having a comparatvely wide drawing slide, `tor instance, presses for drawing mud guards for motorcars, window frames and the like. To this end, instead of arranging the blank holder in, I a'rrange it on the drawing slide, and provide means for entrappng a fluid cushion between the drawing slide and the blank holder.

In this manner not only the press may be designed for any width but I also dispense with the packing for guiding the blank holder in the drawing slide and furthermore I may provide some play between the blank holder and the drawing slide so that the blank holder is free to adapt itself to variations in the thickness of the blank material' and exert uniform pressure on the blank throughout.

' In the drawing a sheetmetal press embodying m invention is illustrated diagram'- matically y way of example, the drawing showing a 'partly'sectional elevation of the press. V

Referring now to the drawing, a s the main driving or crank shaft of the press, b are its pitmen, d is the drawing slide, and c are ball joints connecting the pitmen b with the drawing slide d. e is the drawing block, m is a blank, and f is the blank holder which engages the edge of the blank m and holds it down on the drawing block e. o, o are brackets extending from the sides of the blank holder f, and n, n are slide bars on which the brackets are guided. i Similar brackets p, p are provided on the sides of the drawing slide d extending through slots in the sides of the blank holder f and also guided on the bars n.

is a fiange projecting inwardly from the 7 blank holder f, and g are p'neumatic cylin- &79,433, and"in Germany September& 19539.

ders Secured on the fiange. Two cylinders are shown by way of example but obviously any number of cylinders may be provided. Each cylinder is equipped With a piston h and a pisten rod z' which extends through a bore and a packing Z in the fiange f', and m' is a spherica l joint at the lower end of each piston rod by which it is connected to the drawing slide d. Ic are passages .connecting the space below the piston I) in each cylinder g with a compressed-air reservoir, not shown.

In the position illustrated the drawing slide (Z is at the lowermost end of its stroke, and

the blank holder f is held on the edge of the blank by the pressure of the air below the pistons k. `When the'drawing slide d is reversed to move upwards the blank holder f is still held down on the ed 'e of the blank by the air pressure, although the pressure is somewhat reduced by the increase of Volume it has undergone. Finally the drawing' slide d engages below the flange f' and entrains the blank holder f. When the drawing slide is reversed for another downward stroke the 'blank holder f moves down with the drawing slide until it strikes the edge of the blank m on the drawing' block e and is arrested, while the drawing slide moves on, compressing the air below the pistons, dispelling it artly into the reservoir, no't shown, through t e passage k, and forging the blank m intothe shape indicated.

As shown, the drawing slide d is fitted into the blank holder f with someplay so that the blank holder is free to edge slightly if the ma- 35 terial of the blank is not of quite uniform thickness. Its edging is facilitated by the ball joints m'- at the lower ends of the piston rods z' It will be understood that the blank holder is not guided on the drawing slide but is guided on the bars n. Obviously, however, the guiding means must not interfere With its edging.

I wish itto be understood that I do not desire tobe limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.

In the claims afiixed to this specification'no selection of`-any particular modification of i the invention is intended to the exclusion of other modfications thereof and the right to v subsequently make claim to any modification not covered by these claims is expressly reserved.

I claim:

1. A sheet-metal press comprising a drawing slide, adapted to perform its operation in a single stage, means for reciprocating 30 said drawing slide, a blank holder surrounding said drawing slide, a cylinder on said blank holder, a piston in said cylincler, and a piston rod connecting said pisten to said drawing slide.

2. A sheet-metal press comprising a drawing slide, a blank holder so arranged on said drawing slide as 'w move freely within limits with respect to said drawing slide, means for reciprocating said drawing slide, and pneumatic means operatively conneeting said blank holder to said drawing slide.

3. A sheet-metal press comprising a drawing slide, means for reciprocating said drawing slide, a blank holder surrounding said drawing slide at a clearance'so as to move freely within limits with respect to said drawing slide, a cylinder on said blank holder, a piston in said cylinder, a piston rod on said piston, and a universal joint connecting said 0 piston rod to said drawing slide.

In testimony whereof I aflix' my signature.

"OTTO KlI-INER.

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