GB557439A - Improvements in presses especially for shaping sheet metal - Google Patents

Abstract

557,439. Cupping-presses. ABBEY, A. A. (Bliss Co., E. W.). Aug. 6, 1942, No. 11020. [Class 83 (iv)] The draw ring or blank holder 16 of a cupping press has pressure applied to it at each corner by independently adjustable hydraulic means. Lugs 56 at the corners of the holder are connected to rods 55 guided at 58 and connected to pistons in cylinders 54 each connected by a fluid link to cylinders 35 with pistons each operated by a cam 41 on the press crankshaft. Each link pipe connecting the pairs of cylinders has connected to it a pressure limiting vessel 65 containing a piston 67 loaded by a spring 72 under a pressure adjustable by a screw 74 and disc 70. Leakage from the fluid links is made good from a common reservoir 60 communicating with each cylinder 35 through a valve controlled passage controlled by solenoids and a limit switch 63 from a cam 64 so that the valves close just prior to the commencement of the pressure stroke. Further changes in pressure or stroke may be obtained by varying the relative diameters of the two cylinders in any link, by adjusting the rods 55 in the lugs 58 and by adjusting the position of the cylinders 35 on the frame at 80, Fig. 4. Cyclical variations in pressure may be obtained by shaping the periphery 77 of the cams for instance to reduce the pressure between the beginning and end of the stroke. The drawing is counterbalanced by an air cylinder 32. If the press is to be used as a triple action press further cams and fluid links are provided for the additional drawing operation.