GB901251A - Improvements in precision forging methods and apparatus - Google Patents

Abstract

901,251. Forging. CAVANAGH, D. A. July 8, 1959, No. 23411/59. Class 83 (4). A method of precision forging comprises heating a portion of a workpiece 19 by electric resistance heating whilst surrounded by a die 12, cutting off the heating current and then forging the heated portion to the shape defined by the die cavity 38. The workpiece is first upset under a pressure P1 applied by an hydraulic ram 28 and, after opening heating switch 27, an additional hydraulic force is applied to the ram to complete the forging, Fig. 6 (not shown). The apparatus of this embodiment is similar to that described in Specification 851,407. The anvil 22 and die 12 are insulated at 55 from the bed 54 and the brush 29 is contained in an insulated member 51. In another embodiment, Fig. 7 (not shown), both ends of a long workpiece are forged simultaneously. In a further embodiment for forging a poppet valve, Fig. 9, in a die 80, the head 81 of an hydraulic ram 75 carries a support 82 for a transversely slidable carriage 84, moved by an hydraulic motor, having two anvil heads 85, 86, Fig. 11 (not shown), used respectively for the heating and the forging step. The electrode head 85 is made of beryllium-copper alloy. Coolant is circulated through passages 95 in the die-holder 79 and through passages 96, 98 in the support 82. The contact end of a workpiece is preferably ground smooth before forging. References are made to the forging of brass and steel, particularly high temperature resistant steel.