GB923716A - A forming or impacting machine - Google Patents

Abstract

923,716. Forging hammers. GENERAL DYNAMICS CORPORATION. July 5, 1961 [Oct. 31, 1960], No. 24256/61. Class 83 (4). A power hammer has its ram 126 connected with means 122 for compressing a gas in chamber 130 during the retraction stroke, the compressed gas being used to perform the subsequent working stroke. The ram is of rectangular plan shape, Fig. 2 (not shown), and is guided by segmental bushes 140 co-operating with four guide rods 36 extending between a bolster 50 and a cross-head 38. The latter carries an inner cylinder 120 which co-operates with outer cylinder 122 secured to the ram, to define the pressure chamber 130 which has a gas-filling pipe 138. Bolster 50 has depending therefrom a closed cylinder 58 containing a stationary piston 72 which divides the cylinder into chambers 74, 80 with filling ports 78, 84 respectively, for pressure gas. Ram 126 carries a top tool 142 co-operating with a die 112 on the bolster. The ram is raised mechanically by hooks 194 on endless chains 188 driven through toothed gearing and a flywheel by an electric motor 180, Fig. 2 (not shown). The speed of the motor or the gear ratio is variable for varying the impact rate of the hammer and the vertical position of the chain 188 is adjustable for varying the stroke. Guide rods 36 pass through bearing blocks 32 on frame members 10 of welded construction secured to a baseplate 12. In operation, the hooks 194 engage spring-loaded shock-absorbing plungers 210 of the ram 126 and raise it to its upper limit, thereby compressing the gas in chamber 130. Continued rotation of the chains 188 causes the hooks to release the ram which descends rapidly and presses the workpiece in die 112. Simultaneously the reaction in chamber 130 causes the bolster 50 to be raised slightly but upon impact and also due to the pressure in chamber 80, the bolster moves downwardly whereby a stationary ejector rod 114 removes the workpiece from the die. In another embodiment, Fig. 7 (not shown), the chains 188 are mounted on brackets carried by the bolster and the cylinder 58 is open at its lower end. In a further embodiment, Fig. 8, the ram 280 is raised by hydraulic or pneumatic pressure admitted to telescopic chambers 312 through large passages 316 which are subsequently opened by automatically controlled valves to cause a quick downstroke of the ram and simultaneous upstroke of the bolster 232.