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:
Jan. 24, 1978
Filed:
Nov. 18, 1976
Applicant:
Inventor:
Masayoshi Usui, Numazu, JA;
Assignee:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C21D / ;
U.S. Cl.
CPC ...
148 / ; 148 / ;
Abstract
A steel blank pipe is first subjected to the step of cutting off the hair crack layer portion including the black skin layer of the inner peripheral wall surface of the blank pipe. Thereafter, the steel blank pipe is repetitively subjected to the process of dilation or drawing of the length and the process of annealing within a non-oxidizing hearth.