Title:
METHOD FOR MANUFACTURING SEAMLESS SQUARE STEEL TUBE
Document Type and Number:
WIPO Patent Application WO/2020/189140
Kind Code:
A1
Abstract:
The objective of the present invention is to provide a method for manufacturing a seamless square steel tube with which it is possible to obtain a seamless square steel tube having a corner portion S value equivalent to those in the past, while reducing an equipment load. In this method for manufacturing a seamless square steel tube by piercing a billet to obtain a cylindrical starting material pipe, and hot rolling the cylindrical starting material pipe using a fixed form rolling mill provided with a plurality of square molding stands to form a square cylinder: a number n of the square molding stands in the fixed form rolling mill is at least equal to three; and an outer diameter reduction ratio Δr1 of a first square molding stand, an outer diameter reduction ratio Δr2 of a second square molding stand, and an outer diameter reduction ratio R of all the square molding stands satisfy formulas (1) and (2). (1) (Δr1+Δr2)/R≥0.70 (2) Δr2-0.01≤Δr1≤Δr2+0.01
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Inventors:
YOSHIDA TATSUYA (JP)
Application Number:
PCT/JP2020/006235
Publication Date:
September 24, 2020
Filing Date:
February 18, 2020
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
B21B17/08; B21B17/14; B21C37/15
Foreign References:
| JP2001353520A | 2001-12-25 | |||
| JPH04224022A | 1992-08-13 | |||
| JPH11123452A | 1999-05-11 | |||
| JPH08164416A | 1996-06-25 | |||
| JPH10263626A | 1998-10-06 | |||
| JPH11104711A | 1999-04-20 |
Attorney, Agent or Firm:
SUGIMURA Kenji (JP)
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