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. 13, 1984
Filed:
Apr. 29, 1981
Yoshito Tsuyama, Kitakyushu, JP;
Yasumi Shimazaki, Munakata, JP;
Kazutoshi Kakita, Kitakyushu, JP;
Toshio Hirokawa, Kimitsu, JP;
Nippon Steel Corporation, Tokyo, JP;
Abstract
In the manufacturing of a spiral pipe, there is first determined a maximum curvature which should be imparted to a strip of pipe forming material in order that a desired residual moment will be imparted to the finished pipe after the strip bent to the maximum curvature is allowed to spring back from the bent condition, which maximum curvature is determined based on the thickness, Young's modulus and yield stress of the strip, the desired curvature of the finished pipe, and the residual moment to be imparted to the finished pipe. By adjusting the position of three rows of forming rolls positioned at the apexes of a triangle, the flat strip is continuously bent into a spiral that has the thus determined maximum curvature. Then, the spirally formed strip is allowed to spring back toward its unbent shape to the diameter of the finished pipe, being stopped in the expansion due to the springback if it reaches the finished pipe diameter before completing springback or being expanded if it completes springback before it reaches the finished pipe diameter. Finally, the seam of the formed strip is welded when the strip is at the desired diameter of the finished pipe.