Patent GB-520833-A (GB)
Title: Improvements in or relating to stamps, hammers and the like
IPC: B21J7/44
Filed: 1938-10-31
Abstract: 520,833. Power hammers. MASSEY, Ltd., B. & S., and MASSEY, H. F. Oct. 31, 1938, Nos. 31514 and 33285. [Class 83 (iv)] Drop hammers have a one-way acting crank or eccentric connected directly to the tup by a belt or indirectly by a column of oil and having automatic means to connect the crank with a driving-member after each blow of the tup and to disconnect it at the end of the lift. Means are provided to arrest the crank in this position also fluid pressure means to vary the force of the blow. The tup 3, Fig. 1, is raised by a belt passing over pulleys 14, 15 and connected to a crank 13 maintained in the position shown by a detent 29 with the driving-pawl 26 held out of engagement with the continuously driven wheel 25 by a cam 28. Also connected to the tup by a rod 6 is a piston 5 in. a cylinder connected to a chamber 7 supplied with constant pressure air at 10 through a non-return valve 11. A non-return valve 8 allows air to pass to the chamber on the lifting-stroke and permits the force of the blow to be varied by a valve 9. The cylinder and piston may be reversely arranged. A valve controlling a part leading to the cylinder below the piston provides for cushioning the blow when required. When a blow is to be struck the treadle 30 is employed to remove the detent 29. In a modification the frame is suspended as described in Specification 497,826, so that the tup and anvil move towards one another with equal momenta. The pulley over which the belt passes is mounted on an axle running on rollers in a slot in the frame so that the vertical movement of the latter is not affected by the belt and this pulley is connected to the pulley on the fixed part of the framing by a substantially horizontal link. In a further hammer of the double drive type the tup 3, Fig. 6, moves in guides in a frame 1b and has a controlling piston &c. 51 similar to that described with reference to Fig. 1, and the frame 1b is suspended as described in the first Specification, but the tup is raised by ropes 55 attached at each end to the tup and passing over blocks on the tops of rams 54 raised in cylinders by a ram 46 forced downwards in a cylinder by links 48 connected to the driving-crank 13. A non-return valve 60 and a control valve 61 are provided in the port leading through swivel-jointed piping 58 to the rams 54. By closing the valve 61 the tup may be sustained in its raised position and the valve is actuated through a link 70 and a lost motion device 72 from the detent 29 so that the crank 13 is free to move before the valve is opened. A small pump 63 is rendered momentarily operative at the beginning of each drop of the tup by a cam 3a and valve 67 to make good leakage in the oil link. In a further modification the twin rams 54 are dispensed with and the oil is admitted below the piston 74, Fig. 10, corresponding to the piston 51, Fig. 6. To prevent air leaking past the piston to the oil cylinder 76 the piston has a port 77 leading at 78 to the atmosphere. In a further modification the ram 46 is replaced by a ram 91, Fig. 11, actuated by a crank 13b driven from a continuously rotating wheel 18a through a band brake 81 carried by the crank and tightened by a cord 86 wrapped several times round a sleeve 87 driven by the wheel 18a and tightened by a lever carried by the crank and engaged by a cam 89. The lever may act on the cord through a pilot clutch. In a further modification the ram 46, Fig. 6, is replaced by a doubleacting piston the other end of the cylinder serving to provide tup sustaining and blow regulating means.