The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 07, 2007
Filed:
May. 24, 2002
Kazuya Wakita, Shizuoka-ken, JP;
Katsuyuki Ikei, Shizuoka-ken, JP;
Hisaaki Kura, Shizuoka-ken, JP;
NTN Corporation, Osaka, JP;
Abstract
A power transmission shaft having an improved strength and ensuring a stable torsion fatigue strength. The power transmission shaft has coupling members respectively provided on the opposite ends of an pipe part made of a steel material. The steel material includes 0.30-0.45% by weight of C, 0.05-0.35% by weight of Si, 1.0-2.0% by weight of Mn, 0.05% by weight or less of Al, 0.01% by weight or less of S, and the remainder (iron Fe and unavoidable impurities). The pipe part has an electro-unite portion that extends in the axial direction. The electro-unite portion and neighborhood thereof are hardened so as to have a Rockwell hardness HRC of 45 or more. Also, another power transmission shaft has coupling members integrally formed on opposite ends thereof. In addition, the shaft is formed from a steel element tube by a plastic working. The shaft has an inner diametrical surface which is subjected to a high-frequency induction hardening and tempering treatment to make the surface portion hardness of the inner diametrical surface to have a Rockwell hardness HRC of 35 or more.