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:
Mar. 15, 1988
Filed:
Mar. 31, 1986
Applicant:
Inventors:
Shota Iwakura, Ibaraki, JP;
Yuuji Yoshitomi, Ibaraki, JP;
Takashi Naganawa, Ibaraki, JP;
Toshio Saitoh, Hitachi, JP;
Tatsuo Seki, Hitachi, JP;
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
B21D / ;
U.S. Cl.
CPC ...
72 61 ; 72 62 ; 72 54 ; 2942 / ;
Abstract
A method of relieving residual stress in a metal pipe comprises the steps of applying, by using a pressure medium, a low pressure to an interior of the metal pipe placed in dies, and applying, while preventing the buckling, an axial compression load to the pipe so as to effect a uniform plastic deformation of the entire metal pipe while maintaining the desired shape of the pipe, thereby relieving the residual stress in the metal pipe.