Title:
PRODUCTION METHOD FOR SEAMLESS METAL TUBE
Document Type and Number:
WIPO Patent Application WO/2015/141211
Kind Code:
A1
Abstract:
A 4-roll skew rolling mill, which is configured from large-diameter cone-type main rolls (1, 1') disposed either to the left and right of each other or above and below each other, so as to face each other with a pass line (X-X) therebetween, and small-diameter secondary rolls (7, 7') disposed between the facing main rolls, and either above and below each other or to the left and right of each other, so as to also face each other with the pass line therebetween, is used to bore and roll a solid billet such that the skew angle (β) and the intersection angle (γ) of the main rolls, and the skew angle (β') and the intersection angle (γ') of the secondary rolls are maintained within the ranges 5˚≤「β,β'」≤25˚, 3˚≤「γ,γ'」≤35˚, and 10˚≤「β+γ,β'+γ'」≤55˚. It is preferable that the diameter (d0) of the solid billet and the diameter (d) and the wall thickness (t) of the bored hollow piece satisfy the relationship 1.5≤-ψr/ψθ≤4.5 (with the caveat that ψr =1n(2t/d0), and ψθ =1n{2(d-t)/d0}). As a result, a thin-walled hollow piece can be produced, with a high working ratio, from a billet of a material which is difficult to work.
Inventors:
HAYASHI CHIHIRO (JP)
Application Number:
PCT/JP2015/001439
Publication Date:
September 24, 2015
Filing Date:
March 16, 2015
Export Citation:
Assignee:
NIPPON STEEL & SUMITOMO METAL CORP (JP)
International Classes:
B21B19/04; B21B27/02
Foreign References:
| JPH07155807A | 1995-06-20 | |||
| JPS6431505A | 1989-02-01 | |||
| JPH0270338A | 1990-03-09 | |||
| JPS594905A | 1984-01-11 |
Other References:
See also references of EP 3120942A4
Attorney, Agent or Firm:
ASCEND IP LAW FIRM (JP)
アセンド patent business corporation (JP)
アセンド patent business corporation (JP)
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