GB1092869A - Hydraulic system for dies - Google Patents

Abstract

1,092,869. Forging presses. DI-DRO ENGINEERING CO. Sept. 21, 1965, No. 40170/65. Heading B3Q. An hydraulic cushion for a crank type press includes a piston 22 slidable in cylinder 10 in a fixed bolster 20 beneath a spring balanced die 24, the underside of the piston being supplied by a valve 16 either with low pressure fluid from a tank 12 or with high pressure fluid from a booster 14. Before a stamping operation on a blank 26 commences, fluid is supplied to the piston from the tank 12 via line 38, conduits 54, 48 and 46, and line 36. A solenoid operated valve 18 then operates to direct high pressure air from a cock 76 to the booster 14, the air causing a composite piston 70, 68 to rise to force fluid under high pressure through line 44. A valve spool 110 is urged upwardly against its spring bias to cut off the connection between conduits 46 and 54 and to permit the fluid to pass through a check valve 107 to the piston 22. The die 24 is thus raised so that during stamping, the fluid cushions the stamping force while causing the die 24 to be forced downwardly. This causes a rise in pressure in the cylinder 10 resulting in the valve spool 110 being forced downwardly. The fluid under pressure is vented to the tank 12 and can pass through a clock valve 62. The normal tank pressure in the cylinder 10 serves to strip a finished workpiece from the die. A number of such pistons 22 can be provided for the die 24, and an upper die ring 29 can similarly be provided with pistons, a second hydraulic system being provided for them. The pistons for the die or die ring may be divided into two groups controlled independently by separate hydraulic circuits. In place of the booster 14 a piston and cylinder assembly may be used, a piston being movable with the ram of the press to produce a high pressure in the operating fluid.