Patent GB-399052-A (GB)
Title: Improvements in and relating to drop hammers
IPC: B21J7/24
Filed: 1932-12-17
Abstract: 399,052. Power hammers. HUGHES, R. M., 72, Cannon Street, London.-(Pneumatic Drop Hammer Co.; 123, Heath Street, Boston, U.S.A.) Dec. 17, 1932, No. 35856. [Class 83 (iv).] A drop hammer comprises a hammer and anvil each mounted to reciprocate in the frame, fluid pressure means operable jointly to lift the hammer and to depress the anvil against constant fluid pressure tending to raise the anvil and means for exhausting the fluid pressure thereby allowing the hammer to fall and the anvil to rise so as to meet in a predetermined zone with substantially equal momentum. The hammer 15 is lifted by a rod 22 and piston 23 actuated in the hammer cylinder 24 by fluid admitted through conduit 34 and valve 42 from the port 37 in the valve block 35 and falls when valve 42 is rotated to put conduit 34 in communication with exhaust valve 47. The anvil 16 is actuated by piston rod 62 and piston 67 in anvil cylinder 71 and is normally held in lowered position by fluid admitted simultaneously to the underside 82 of piston through the continuously open conduit 80 and to the topside 94 of piston through conduit 93 and valve 91, the anvil making its upstroke when valve 91 and exhaust valve 95 are rotated to allow escape of fluid from topside 94 of anvil cylinder. Contact of the hammer on its upstroke with the beam 12 is prevented by a dashpot cylinder 48 supplied with fluid through a branch 54 of the conduit 34 ; the dashpot piston 50 is lifted by an adjustable sleeve 56 on the piston rod 22 and the fluid trapped between piston 50 and cylinder cover 26 escapes through a passage 58. An adjustable screw in the wall of passage 58 controls the action of the dashpot. Hammer cylinder operating valve 42 and anvil cylinder operating valve 91 are operated in unison by a vertical rod 113 which is actuated to effect the fall of the hammer by a fluid cylinder 131, Fig. 3, controlled by a valve 148 and hand-lever 149 or otherwise, the piston 132 carrying a rod 134 with projection 135 engaging a roller on a head keyed to valve rod 113. The hammer starts to fall but the exhausting of the topside of the anvil cylinder is delayed until exhaust valve 95 by means of its valve rod 158 is rotated by a projection 161 on hammer 15 engaging cam 159 on rod 158, the shorter time of ascent of the anvil being sufficient for the anvil to acquire the necessary momentum from the fluid under the anvil piston. Valves 42 and 91 are reopened to fluid supply immediately before the impact by another projection 155 on hammer engaging cam 153 on valve rod 113 so that the cylinders come into action immediately on the rebound. The rate of fall of the hammer is controlled by varying the degree of opening of the hammer cylinder exhaust valve 47 by means of an operating rod 171 controlled by a handle 173 and the rate of rise of the anvil is co-ordinated therewith by passing some of the fluid escaping from the hammer cylinder by means of a pipe 190 to a cylinder 191, Fig. 12, actuating an adjustable spring- loaded piston valve 176 which varies the area of a window 185 in the valve casing 174 thus controlling the escape of fluid from the anvil cylinder through the exhaust port 102. Pressure is maintained in the topside 94 of the anvil cylinder in the interval between the closing of valve 91 to inlet port 88 and the opening of valve 95 to exhaust by fluid passing from port 88 through byepass 96 via valve 95, pipe 97 and conduit 98 to the topside of anvil cylinder. Valve rod cams 153, 159 are adjustable simultaneously to vary the plane of impact of hammer and anvil by connecting them rotatably to arms 167, 168 carried by a collar 163 adjustably secured along a fixed vertical rod 164. The lift of the hammer is varied by adjusting the sleeve 56 on the hammer lift rod 22 and scale and index devices may be provided for varying the relative setting of the cams 153, 159. The nut 191 securing the hammer piston to the rod 22 is locked by a split sleeve and clamp screws 202. Specification 342,024 is referred to.