MANUFACTURE OF POWDER SINTERED SEAL

摘要

PURPOSE: To facilitate molding of a powder sintered seal and engraving of a seal character by a method wherein a powdery compacted material for seal formed by pressure molding for which binding strength of binder is used, is sintered. CONSTITUTION: Raw material powder 1 is formed by mixing 100 pts. wt; of Ti powder of 30μaverage particle diameter as sinterable powder and 0.5-20vol.% of 5wt.% of PVA aqueous solution to the sinterable powder as a binder. The raw material powder 1 is filled in a cavity 14 of a mold 13, and a cover of a closed box 5 is closed. The mold 13 is vibrated by operating a vibrator, and compressed air is fed simultaneously from a compressed air feed pipe 7 to form a powder molded body for seal. An electric current is conducted to a heater 16 of a heating frame 15 to heat the mold 13 and the mold is evacuated simultaneously from an evacuating pipe 8 to obtain a powdery compacted material for seal. A seal character is engraved on the powdery compacted material for seal. So called removal of binder wherein the binder is removed by decomposition by heating is carried out. Successively sintering wherein the sinterable powder is bonded to each other by heating to be compacted, is carried out.