METHOD OF MANUFACTURING SEAMLESS TUBE

WIPO Patent Application WO/2004/103593

A1

A method of manufacturing a seamless tube, wherein miss-rolling such as defective biting is prevented from occurring by satisfying either of the expressions (1) to (3) below according to the range of roll diameter ratio of Dg/Dl and the occurrence of internal surface flaw resulting from the lowering of hot workability of the top part of a rolled material by properly suppressing a rotational forging effect and, for those parts other than the top part which are worked subsequent to the top part, also the internal surface flaw can be prevented from occurring without changing setting conditions for drilling and rolling. Thus, this manufacturing method can be widely used as a method for manufacturing excellent seamless tubes. Where Dg/D1 < 1.1, 23 ≤ N/(Df/100) ≤ 40 ... (1) Where 1.1 ≤ Dg/D1 < 1.5, 20 ≤ N/(Df/100) ≤ 44 ... (2) Where 1.5 ≤ Dg/D1 ≤ 1.8, 20 ≤ N/(Df/100) ≤ 48 ... (3)

Yamakawa, Tomio c/o Sumitomo Metal Industries Ltd. (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)
Shimoda, Kazuhiro c/o Sumitomo Metal Industries Ltd. (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)

PCT/JP2004/007216

December 02, 2004

May 20, 2004

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SUMITOMO METAL INDUSTRIES, LTD. (5-33, Kitahama 4-chome Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)
Yamakawa, Tomio c/o Sumitomo Metal Industries Ltd. (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)
Shimoda, Kazuhiro c/o Sumitomo Metal Industries Ltd. (5-33, Kitahama 4-chome, Chuo-ku, Osaka-sh, Osaka 41, 54100, JP)

B21B19/04; B21B19/00; (IPC1-7): B21B19/04

Mori, Michio (M. MORI PATENT OFFICE, Amagasaki Building 17-23, Higashinaniwa-cho 5-chome, Amagasaki-sh, Hyogo 92, 66008, JP)

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