Patent GB-1223167-A (GB)
Title: Hammer with hydraulic coupling
IPC: F15B11/08
Filed: 1968-10-11
Abstract: 1,223,167. Hammer with an hydraulic coupling. LANGENSTEIN & SCHEMANN A.G. 11 Oct., 1968 [6 Nov., 1967], No. 48297/68. Heading B3H. An hydraulic hammer comprises a drivable tup 1 and a co-operating mating tup 16, an hydraulic return system 3 operatively connected to the drivable tup, a free-drive piston 2 disposed in a chamber, a piston 32 disposed in a piston 25 and cylinder unit 10 connected to to the free piston 2, an hydraulic coupling 6 connecting the said chamber to the hydraulic return system 3, the hydraulic coupling including a first valve 8 connecting the said chamber to a low-pressure fluid in an accumulator 24, and a second valve 5 connected to the cylinder unit 10 for maintaining the pressure in the said cylinder when the pistons are in a first position whereby upon actuation of both the valves 8 and 5 the pistons are moved to respective second positions to thereby operate the hydraulic return system 3 and in turn the drivable tup 1. To activate the hammer the compression chamber 27 is filled with compressed gas and closed off. The main pump 38 is then activated to continually supply pressurized liquid through the line 7, no pressurized liquid being fed through the press line 51. The pressurized liquid holds the free piston 2 in its uppermost position against the pressure of the gas in the compression chamber 27 by acting via the hydraulic return system 3 to hold the drivable tup 1 in its retracted position. To execute a hammer blow a solenoid valve 43 is operated so as to open the impact valve 8 against the pressure of a spring 45. With the impact valve 8 open, the cylinder space of the cylinder and piston arrangement 4 and the cylinder space of the hydraulic return system 3 are connected with the accumulator 24. By operating the solenoid valve 43, the dump valve 5 is closed so that the coupling 6 now constitutes a closed system. With the impact valve 8 open and the coupling 6 closed, the gas in the compression chamber 27 drives the free piston 2 and, via the coupling, 6, the drivable tup 1 downwards. At the same time the piston 3 displaces liquid through the impact valve 8 into the accumulator 24. The movable valve element 35 of the impact valve 8 is held open by the flow of liquid passing across it but drops as soon as the drivable tup 1 ceases its movement on impact. With the dropping of the valveelement 35, the dump valve 5 is opened and the coupling space 29 is connected to the accumulator 24. Thus the tup 1 is relieved of the gas pressure when springing back after impact and can be moved back by the liquid flowing into the cylinder of the hydraulic return system 3. At the same time, pressurized liquid from the main pump 38 is fed into the cylinder and piston arrangement 4 and drives the free piston 2 back. The mating tup 16 is coupled with the drivable tup 1 through an hydraulic feedback arrangement 63. The feedback arrangement has two branches 64 comprising a coupling rod 12 attached at one end to the drivable tup 1 and whose other end does duty as a movable plunger 13. The movable plunger extends into a coupling chamber 14. As the drivable tup 1 is dropped the pressure is raised in the coupling chambers 14 which raises the feedback arrangement 63 which in turn raises the mating tup 16. For pressing operations the free piston 2 is held in its extended position by the closure of the impact valve 8 and a one-way valve 37. The hammer is then operated in the manner of a normal press.