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:
Oct. 06, 1998
Filed:
Apr. 16, 1996
Applicant:
Inventors:
Assignee:
NKK Corporation, Tokyo, JP;
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
B21B / ; B21D / ;
U.S. Cl.
CPC ...
72 41 ; 72325 ; 72 97 ;
Abstract
A seamless steel tubular product is produced by hot-piercing an alloy-steel billet with a piercing plug to produce a hollow shell and then rolling the hollow shell. Prior to the hot-piercing, a steel sheet is joined to an end surface of the billet into which the plug is to be driven, such that the steel plate may not project beyond the periphery of the billet, the steel plate having a surface area (C) satisfying the equation: