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:
Nov. 13, 2012
Filed:
Mar. 26, 2010
Akira Tange, Yokohama, JP;
Hideki Okada, Yokohama, JP;
Isao Sumiyoshi, Yokohama, JP;
Mitsuhiro Sugiyama, Yokohama, JP;
Akira Tange, Yokohama, JP;
Hideki Okada, Yokohama, JP;
Isao Sumiyoshi, Yokohama, JP;
Mitsuhiro Sugiyama, Yokohama, JP;
NHK Spring Co., Ltd., Yokohama-Shi, JP;
Abstract
A spring wire with hardness of 50 to 56 HRC is subjected to first and second shot peening processes within a warm working temperature range of 150 to 350° C. In the first shot peening process, the first shot of a shot size of 1.0 mm or more is used. In the second shot peening process, the second shot smaller in shot size than the first shot is used. Through these shot peening processes, compressive residual stress is imparted to the spring wire. The spring wire includes a residual stress increase part, residual stress peak part, and residual stress decrease part. In the residual stress decrease part, a part including the compressive residual stress magnitude of which is equivalent to the magnitude of the compressive residual stress at the surface of the spring wire exists at a position at a depth exceeding the permissible pit depth.