JPS6431902A - Metallic mold for compacting - Google Patents

Abstract

PURPOSE:To compact a seal ring without developing any crack to abutment part by arranging projected parts corresponding to notchings of key-step part toward radius direction at one end of the abutment part of inner circumference of a die and outer circumference of a core and fitting upper and lower punches to this. CONSTITUTION:In compacting a metallic mold for the seal ring 1 composing of the die 2 having shape at free-state of the seal ring, the core 3 and the upper and lower punches 4, 5, the projected parts 21, 31 corresponding to the notchings of the key step part toward radius direction at the one end of the abutment part of the inner circumference of the die 2 and the outer circumference of the core 3 are arranged and the compacting metallic mold, which the upper and lower punches 4, 5 are fitted with it as slidable, is formed. Raw material powder is compressed to compact by using this metallic mold to make raw green compact, and raw sintered compact is produced in an end thermic gas sintering furnace and re-compressed with a correcting metallic mold to remove strain. Next, center part C of the abutment part is cut, to make the seal ring 1, and then, the development of crack to the abutment part is prevented.