GB983403A - Forging hammer - Google Patents

Abstract

983,403. Forging. EUMUCO A.G. FUR MASCHINENBAU. June 12, 1961 [June 11, 1960], No. 21195/61. Heading B3H. An hydraulic forging hammer driven by a constant delivery pump 8 has a pressure liquid container 7 interposed between the pump and the working cylinder 5 and forming an oscillating system. The tup 2 is connected to a working piston 4 whose annular under surface 21b is open continuously to the container 7 filled exclusively with pressure liquid and which is charged by pump 8 through check valve 10, pipe 9 and pressure controller 22a. The pump draws from an oil tank 18 and has a safety valve 31 and a by-pass 11, 12 for use when the hammer is idling. A larger diameter free piston 23 with a throttle opening 24 is disposed above piston 4, and moves between fixed abutments. When the pressure in container 7 reaches a predetermined value, the pressure controller 22a actuates valve unit 14, 19 which admits pressure to chambers 28, 15, whereby the tup 2 descends to strike a blow. Shortly before impact the tup operates electric contacts which act through electro-hydraulic or electro-pneumatic means to reverse valve 14, 19. This places chamber 28 and pipe 25 in communication with exhaust pipe 17 and the tup rises due to rebound energy and the pressure on face 21b. Some of the liquid in chamber 15 is released through throttle aperture 24 but the pressure in this chamber causes piston 23 to move upwardly until it closes the outlet to pipe 25 and this piston then acts as a brake for the upward movement of the tup. It is stated that the length of the upstroke remains constant irrespective of the amount of rebound. In another embodiment, Fig. 1 (not shown), the piston 23 is omitted and separate inlet and exhaust valves control the pressure in chamber 15; excess pressure is prevented by a relief valve. A throttle valve may be fitted in the exhaust pipe.