Ntn Corporation

Kenji Ouwa

Kazuhiko Yoshida

Hiroyuki Uchida

Kazuho Mimura

A shaft part is formed with a rolling groove () on which rolling elements () roll. At least the rolling groove () is induction hardened with no generation of black colored oxidized scale after the induction hardening. A surface of the induction hardened rolling groove () is used 'as is' as a rolling surface. The surface roughness Ra of the induction hardened surface 'as is' of the rolling groove () is less than 1.0. The ratio of effective hardened depth of a hardened layer is between 0.15 and 0.45.

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Hiroshima, Japan

Kenji Ouwa