GB1075923A - Precision stamping press - Google Patents

Abstract

1,075,923. Punching. HYDREL A.G. April 9, 1965 [April 10, 1964], No. 15231/65. Heading B3W. In a punch press the tool is mounted in a piston 7 which slides inside a second piston 8 in an hydraulic cylinder 9. The relative movement between the pistons is limited by shoulders thereon and springs 25 bias the piston 7 towards the top of the piston 8. An extension 7a of the piston extends through a top plate 10 of the press frame and carries a yoke 15. Between the plate 10 and the yoke 15 are two pneumatic piston and cylinder units 11, 12 and two compression springs 13, 14. An hydraulically operated piston 5 ejects the punched-out part. The highest position of the yoke 15 is limited by a stop 18 manually adjusted by a screw 17. The lowest position of the yoke is limited by a stop 19 threaded into a cylinder 20 which can be rotated for coarse adjustment by a motor 23 and for fine adjustment by a hand wheel 21. The working stroke is effected by admitting hydraulic fluid to the cylinder space 9a. When the pressure is relieved the piston 7 is raised by the pneumatic cylinders 11 and 12 assisted by the springs 13 and 14. The piston 8 acts as a hold-down on the working stroke and as a stripper on the return stroke. For precision stamping it is necessary to reverse the movement of the cutter accurately at a chosen point and the Specification states that this can also be achieved by micro-switches (30), Fig. 3 (not shown), actuated by tripping pins mounted on the piston units 5, 7, 8 and controlling hydraulic valves in the circuit. An electronic delay timer prevents the piston 5 ejecting the punched-out part until the piston 7 has risen. The work material is also lifted from the die by a projection on the bottom of the piston 7 so that when the punched-out part is pushed out of the die it can be removed mechanically or by an air blast.