Hitachi Chemical Company, Ltd.

Hitachi Powdered Metals Co., Ltd.

Resonac Corporation

Tomoyuki Kohida

Satoshi Onodera

Katsuhiko Ueda

Junichi Ichikawa

Tomoaki Arakawa

Kenzou Morita

Kensuke Nakata

Go Hagimoto

Kenzo Morita

Shuichi Aoki

Method of forming a compact based on the press forming method provides a compact having high density and not having cracking or surface roughness in a product and without compact adhesion to press forming mold wall occurring, including steps: filling raw material powder in a cavity formed by an outer mold and lower punch, or outer mold and lower punch and core rod, pressing and forming raw material powder between an outer punch and lower punch, and extracting the compact obtained out of the outer mold by the lower punch, wherein a lubricating film of a press forming mold lubricant containing oil as main component is formed on at least part of outer mold inner surface, or outer mold inner surface and core rod outer circumferential surface before filling the raw material powder in the cavity, and press forming so that compact density ratio is not less than 93%.

Method for forming molded article by press molding

The present invention provides a sintered body and a production method therefor in which effects of pores remaining at a surface of the sintered body can be avoided without removing the pores by machining and plastic working, thereby obtaining strength equivalent to that of ingot materials. The sintered member comprises: a hardness distribution in which hardness contiguously varies from a surface to an inner portion; a Vickers hardness value of 730 or less at the surface; the maximum hardness of which portion exists in a region of 150 to 300 &#x3bc;m from the surface; wherein the maximum hardness is a Vickers hardness value of 600 or more.

Sintered member, pinion gear for starters, and production method therefor

A production method for a sintered member includes preparing a raw powder, compacting the raw powder into a green compact having pores at the surface thereof, and sintering the green compact into a sintered compact. The production method also includes sealing the pores exposed at the surface of the sintered compact by at least one of plastically deforming and melting the surface of the sintered compact. The production method further includes forging the sintered compact by using a lubricant after the sealing.

Production method for sintered member

A sintered gear comprises: plural tooth portion having a tooth flank and a tooth bottom land; a high density area formed over entire surface of the tooth portion, the high density area having a density of 7.6 Mg/mor more and formed with a depth of 1 mm or more from the surface; a low density area formed in deeper area than the high density area, the low density area having a density of 7.3 Mg/mor less; and an intermediate area formed between the high density area and the low density area, the intermediate area having a density gradient in which the density is gradually decreased from the high density area to the low density area.

Production method for sintered gear

Growing community of inventors

Matsudo, Japan

Tomoyuki Kohida