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. 05, 2024
Filed:
May. 15, 2020
Mitsubishi Steel Mfg. Co., Ltd., Tokyo, JP;
Hironobu Sayama, Ichihara, JP;
Toru Hirokane, Ichihara, JP;
MITSUBISHI STEEL MFG. CO., LTD., Tokyo, JP;
Abstract
A method includes, providing a tubular member () used for a hollow spring, and applying the compressive residual stress to at least a portion of an inner surface of the steel tube by applying the compressive force to at least a portion of an outer surface of the tubular member () from a circumferential direction, and a fatigue life of the tubular member () is prolonged by applying the compressive residual stress to the inner surface of the tubular member (). Applying the force to the outer surface of the tubular member () includes pressing the tubular member () with a die (). The die () has a pressing surface () shaped such that the compressive force can be applied to at least the portion of the outer surface of the tubular member () from the circumferential direction.