HIGH-ACCURACY PRODUCTION OF SINTERED MATERIAL FORMED WITH HOLLOW HOLE

摘要

PURPOSE:To produce sintered body having a hollow hole of high inside surface accuracy by providing a bulging part corresponding to a thick-walled part to the outside circumference of a core rod to be used for production of the sintered material having the hollow hole provided with the thick-walled part on the outside part. CONSTITUTION:A lower punch 3 is inserted into the molding cavity C of a molding 1 and the core rod 4 with a main shaft 4A faced upward is inserted into a through-hole 3a thereof. Raw material powder for sintering is then put into the cavity C and the main shaft 4A is inserted into the through-hole 2a of an upper punch 2 so that the powder is compacted by the punches 2, 3 and the molding A1 having the thick-walled part 10'a is formed. The bulging part 4b is provided on both sides in the diametral direction to the part of the rod 4 corresponding to the thick-walled part 10'a to form said part into an approximately elliptical shape and therefore the elliptical recess is formed on the inside surface of the molding A1. The molding A1 is thereafter sintered, then the thick-walled part 10'a expands more largely than the other part and bulges therefore toward the inside to make round the elliptical recess. The sintered material having the hollow hole of high accuracy is thus obtd.