GB260464A - Improvements in and relating to blank-holders for presses for drawing sheet metal - Google Patents

Abstract

260,464. Fitzpatrick, H. D., (Marquette Tool & Manufacturing Co.). Feb. 9, 1926. Cupping. - A multi-stage press for drawing sheet metal has means for positively locking one of the draw-rings during one stage of the drawing process, this draw-ring being released to function during its own operative stage by means connected to the draw-ring functioning during the preceding stage. The blank 14 is supported on a stationary cutting-die 12 and on a stationary drawing-die 11, concentric draw-rings 15, 16 being located between the cutting and drawing dies. The draw-ring 16 is supported by a member 50 carried by a cylinder 19 which telescopes over a stationary cylinder 20. A piston 26 in the cylinder 20 supports, by means of a piston-rod 28, a hollow member 36 having at its upper end a, plate 37 on which rest pins supporting the second stage draw-ring 15. The plate 37 has a central aperture provided with teeth adapted to co-operate with corresponding teeth on a member 39 swivel-mounted in the bed 10 of the press. The teeth on the members 37, 39 are in alignment during the first stage of the drawing process, but at a given point in the downstroke a cam-slot 58 in the member 50 rocks a pivoted arm 45 which, in turn, rocks the member 39 so that the teeth thereon register with grooves in the member 37. thereby allowing the latter to descend with the draw-ring 15 against fluid-pressure in the cylinder 20 to complete the drawing operation. The cam-faces 58 are detachable so that different ones may be substituted to vary the point at which the second stage of the drawing process commences.