GB1005517A - Improvements in or relating to power operated stamping machines - Google Patents

Abstract

1,005,517. Punching. NATIONAL CASH REGISTER CO. Jan. 14, 1964, No. 1634/64. Heading B3W. In an automatic blanking and piercing press in which the blanks are retained in the die until discharged by an ejector, the machine includes a reciprocable ram, an electrically driven power supply mechanism, a clutch normally engaged, actuating means powered by compressed air operable to disengage the clutch if more than one blank accumulates in the die, and an air pressure switch associated with the compressed air supply for the said actuating means, so that if the air supply fails the switch operates to disconnect the electricity supply from the said power supply mechanism. The strip 29 to be punched passes over a fixed punch 23 and is guided by a spring-loaded stripper plate 26. The punch co-operates with a die 2 in which slides an ejector 9. Ejector pins 15 rest on the ejector 9 and are of such a length that when the ejector is flush with the die, the upper ends of the pins are in contact with the under-face of a knock-out plate 11. Integral with the plate 11 is a rod 13 which abuts a knock-out bar 22 just before the die assembly 1 reaches its uppermost position on the upward stroke of the press. The die assembly 1 also includes piercing punches 18 which co-operate with die apertures 28 in the punch 23. The blank sheared out on the downward stroke of the press is retained in the die until discharged by the ejector, but if it is not ejected then on the next stroke of the press the additional thickness of a second blank entering the die raises the knock-out plate 11 so that its chamfered edge 12 actuates a plunger 21 which closes a micro-switch 19. When the switch closes it operates a solenoid controlling an airvalve in the circuit of a pneumatic cylinder which disengages a clutch between the ram and flywheel of the press. The power supply to the main press motor also passes through an airoperated switch which prevents the motor being started if there is no air pressure.