GB1286558A - Deep-drawing press - Google Patents

Abstract

1286558 Stamping G BERG 8 Dec 1970 [10 Dec 1969] 58148/70 Heading B3Q A press in which a blank is drawn through a succession of dies by a number of telescopically arranged punches which also act as holddowns, comprises annular pistons for extending the punches and to some of which fluid pressure is applied in the return direction to reduce the hold-down force. As shown, there are four punches (5-8), Fig. 4 (not shown), and four dies (1-4), Fig. 1 (not shown), the punches being attached by piston-rods 14-17, Fig. 3, to annular pistons 10-13, the inner pair 11, 12 of which have rearwardly-extending valve-sleeves 20, 21, Fig. 2. An edge 27 on a housing 18 co-operates with ports 22, 23 in the sleeve 20, and an edge 25 on the sleeve 20 co-operates with a port 24 in the sleeve 21. Operation.-Pressure fluid supplied to one side of piston 10, through a side-port 19 in the casing 18, advances the four pistons together through the first die (1) and up to the second die (2) when port 22 is uncovered by the edge 27. A passage in the sleeve 20 leads from the port 22 to the second piston 11 and to the other side of piston 10 so as to continue advance of the pistons 11, 12 and 13 and reduce the force assimilable at the outer punch (5) for pressure on the second die. Similarly, when port 23 is uncovered, the pistons 12 and 13 continue to advance and the force available for holding by the punch 11 is reduced. Piston 13 advances alone when port 24 is uncovered by edge 25. The pistons 10, 11 and 12 are returned by piston 13 when pressure fluid is supplied through a port 40 in a central guide tube 39.