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.

Date of Patent:
May. 10, 2016

Filed:

Dec. 18, 2012
Applicant:

Jfe Steel Corporation, Tokyo, JP;

Inventors:

Yusuke Fujii, Fukuyama, JP;

Toyohisa Shinmiya, Fukuyama, JP;

Yuji Yamasaki, Fukuyama, JP;

Kazuhiko Higai, Chiba, JP;

Assignee:
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
B21D 22/02 (2006.01); B21D 37/20 (2006.01); B30B 15/02 (2006.01); B30B 12/00 (2006.01); B21J 13/02 (2006.01);
U.S. Cl.
CPC ...
B21D 22/02 (2013.01); B21D 37/20 (2013.01); B21J 13/02 (2013.01); B30B 12/00 (2013.01); B30B 15/02 (2013.01); G01N 2203/0067 (2013.01);
Abstract

A prediction equation 'R/t≧(2R/t+(2R/t+1)ε)/2(1−(1+2R/t)ε)' is derived which predicts that bendability-dominated fracture will not occur when the critical surface strain εis not exceeded by a strain on the metal sheet surface causing the occurrence of ductility-dominated fracture that is obtained from the minimum curvature radius Rof a press-forming mold and the critical strain εin a plane strain region in a forming limit diagram. The minimum curvature radius Rof a mold required to prevent the occurrence of bendability-dominated fracture is estimated, and the mold is designed with a curvature radius that is not less than the curvature radius R.


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