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:
Jul. 23, 2013
Filed:
Aug. 09, 2011
Kouichi Harada, Osaka, JP;
Tomio Yamakawa, Osaka, JP;
Kouichi Harada, Osaka, JP;
Tomio Yamakawa, Osaka, JP;
Nippon Steel & Sumitomo Metal Corporation, Tokyo, JP;
Abstract
Provided is a method for producing a seamless tube, in which after a starting material to be extruded has been heated to a heating temperature T [° C.] satisfying the relationship of Formula (1) or Formula (2) depending on the outside diameter d[mm] thereof, the starting material is hot extruded by providing a solid lubricating glass between the starting material to be extruded and a die, whereby a transverse flaw on the outer surface in the top portion of tube can be prevented when hot extrusion is performed by using a starting material for extrusion having low deformability at high temperatures. When d<200, T≦1250+1.1487×A−7.838×ln(t/t)−10.135×ln(d/d) . . . (1); when d≧200, T≦1219+1.1487×A−7.838×ln(t/t)−10.135×ln(d/d) . . . (2), where A=L/V×1000 [msec.]. V=(V+V×ρ)/2 [mm/sec], ρ=(t×(d−t))/(t×(d−t)), t: wall thickness of starting material to be extruded [mm], d: outside diameter of extruded tube [mm], t: wall thickness thereof [mm], L: length of approach portion of die along extrusion direction [mm], and V: ram speed [mm/sec].