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:
Apr. 19, 2022
Filed:
Jun. 08, 2018
Nippon Steel Corporation, Tokyo, JP;
Kouji Yamane, Tokyo, JP;
Kazuhiro Shimoda, Tokyo, JP;
Yuji Inoue, Tokyo, JP;
Shusuke Shimooka, Tokyo, JP;
Yuichi Yamanari, Tokyo, JP;
Nippon Steel Corporation, Tokyo, JP;
Abstract
A method for producing a seamless metal pipe includes the steps of: preparing a billet having a diameter (B); heating the billet; forming, in a center part of a rear end of the heated billet, a hole including four grooves extending in an axial direction of the billet, the grooves each having a groove width (D) satisfying Formula (1), a groove height (H) satisfying Formula (2), and a groove depth (L) satisfying Formula (3); and subjecting the billet provided with the hole to piercing-rolling from a front end thereof by means of a piercing machine. By this means, the generation of burrs and internal defects at the rear end of a hollow shell after piercing-rolling can be suppressed.0.12≤≤0.25  (1)0.10≤≤0.20  (2)0.05≤1/≤0.10  (3)