Title:
METHOD FOR PRODUCING STEEL PIPE
Document Type and Number:
WIPO Patent Application WO/2014/188599
Kind Code:
A1
Abstract:
This method for producing a steel pipe (P) includes: a molding step for molding a steel plate into a cylindrical shape by means of a bending press method in which the steel plate is reduced by means of a punch (2), which has an outer peripheral surface having an arc-shaped cross section at the tip, in a manner so that both ends in the widthwise direction of the steel plate face each other; a welding step for abutting and welding the ends in the widthwise direction of the steel plate; and a tube expansion step for performing tube expansion from the inside of the steel pipe using a tube expander (11) at which are disposed in the peripheral direction a plurality of tube-expanding dies (16) having an outer peripheral surface that has an arc-shaped cross section. The tube expansion R ratio, which is the ratio of the radius of curvature of the outer peripheral surface of the tube expansion dies to the target radius of the inner surface of the steel pipe, and the punch R ratio, which is the ratio of the radius of curvature of the outer peripheral surface of the punch tip to the target radius of the inner peripheral surface of the steel pipe, are both less than 1, and the tube expansion R ratio and the punch R ratio satisfy a predetermined conditional formula. As a result, it is possible to produce a steel pipe having high circularity without causing crack damage to the tube expansion dies.
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Inventors:
MIWA TOSHIHIRO (JP)
Application Number:
PCT/JP2013/064525
Publication Date:
November 27, 2014
Filing Date:
May 24, 2013
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
B21D39/20; B21D5/01
Foreign References:
| JPS59183943A | 1984-10-19 | |||
| JP2001113316A | 2001-04-24 | |||
| JP2010167440A | 2010-08-05 | |||
| JPH0394936A | 1991-04-19 | |||
| JPS59183943A | 1984-10-19 | |||
| JPS61147930A | 1986-07-05 |
Other References:
See also references of EP 3006133A4
Attorney, Agent or Firm:
SAKAI, HIROAKI (JP)
Hiroaki Sakai (JP)
Hiroaki Sakai (JP)
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