Hitachi Powdered Metals Co., Ltd.

Nissan Motor Company Limited

Hiromasa Imazato

Koichiro Yokoyama

Akira Fujiki

Hiroyuki Ishikawa

Tsutomu Uemura

Hiroshi Sugihara

Shinichi Umino

In a process for manufacturing composite sintered machine components, the composite sintered machine component has an approximately cylindrical inner member and an approximately disk-shaped outer member, the inner member has pillars arranged in a circumferential direction at equal intervals and a center shaft hole surrounded by the pillars, and the outer member has holes corresponding to the pillars of the inner member and a center shaft hole corresponding to the center shaft hole of the inner member. The process comprises compacting the inner member and the outer member individually using an iron-based alloy powder or an iron-based mixed powder so as to obtain compacts of the inner member and the outer member, tightly fitting the pillars of the inner member into the holes of the outer member, and sintering the inner member and the outer member while maintaining the above condition so as to bond them together.

Process for manufacturing composite sintered machine components

In a process for manufacturing composite sintered machine components, the composite sintered machine component has an approximately cylindrical inner member and an approximately disk-shaped outer member, the inner member has pillars arranged in a circumferential direction at equal intervals and a center shaft hole surrounded by the pillars, and the outer member has holes corresponding to the pillars of the inner member and a center shaft hole corresponding to the center shaft hole of the inner member and connected to the holes. The process comprises compacting the inner member and the outer member individually using an iron-based alloy powder or an iron-based mixed powder so as to obtain compacts of the inner member and the outer member, tightly fitting the pillars of the inner member into the holes of the outer member, and sintering the inner member and the outer member while maintaining the above condition so as to bond them together. A circumferential side surface facing a circumferential direction of the pillar of the inner member and a circumferential side surface facing a circumferential direction of the hole of the outer member are interference fitted at 0 to 0.03 mm of the interference. A radial side surface facing a radial direction of the pillar of the inner member and a radial side surface facing a radial direction of the hole of the outer member are fitted so as to be one of being interference fitted at not more than 0.01 mm of the interference and being through fitted.

The invention relates to a method of preparing a composite sintered body having inner and outer portions fitted with each other. The method includes the steps of: (a) preparing an inner powder compact; (b) preparing an outer powder compact; (c) fitting the inner and outer powder compacts with each other so as to prepare a composite powder compact; and (d) sintering the composite powder compact so as to prepare the composite sintered body. The inner and outer powder compacts are respectively selected such that, during the step (d), the amount of growth of the inner powder compact becomes greater than that of the outer powder compact. Each of the inner and outer composite powder compacts is made of one member selected from the group consisting of a wax-type segregation prevention powder mixture and a metal-soap-type segregation prevention powder mixture. At least one of the inner and outer composite powder compacts is made of the wax-type segregation prevention powder. According to the method, the mechanical property of each of the inner and outer portions of the composite sintered body is not limited, and the bonding strength between the inner and outer portions is substantially high.

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Matsudo, Japan

Hiromasa Imazato