DRAWING ROLLING METHOD BY MANDREL MILL

WIPO Patent Application WO/2006/104146

A1

A drawing rolling method by a mandrel mill by which overfill and underfill can be prevented through combination of one kind of grooved rolling rolls. Outside diameter of a hollow shell is set such that the ratio (outer circumferential length of the hollow shell/outer circumferential length of a naked lead pipe on a finishing stand exit side) becomes 1.1 or above when Cr content of the naked lead pipe is 10% or above, and set such that the ratio becomes less than 1.1 when Cr content of the naked lead pipe is less than 10%. Grooved profile of grooved rolling rolls provided, respectively, in first and second stands are set such that the grooved circumferential length dependent on a plurality of grooved rolling rolls provided in the first stand of the mandrel mill satisfies expression (1), the grooved circumferential length dependent on a plurality of grooved rolling rolls provided in the second stand satisfies expression (2), and the grooved circumferential lengths of the first and second stands satisfy expression (3). Drawing rolling of the naked lead pipe is thus carried out using the mandrel mill.

Yamane, Akihito c/o SUMITOMO METAL INDUSTRIES LTD. (5-33, Kitahama 4-chome, Chuo-k, Osaka-shi Osaka 41, 54100, JP)

PCT/JP2006/306292

October 05, 2006

March 28, 2006

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SUMITOMO METAL INDUSTRIES, LTD. (5-33, Kitahama 4-chome Chuo-k, Osaka-shi Osaka 41, 54100, JP)
Yamane, Akihito c/o SUMITOMO METAL INDUSTRIES LTD. (5-33, Kitahama 4-chome, Chuo-k, Osaka-shi Osaka 41, 54100, JP)

B21B17/04; B21B27/02; B21B17/00; B21B27/02

Hirose, Shoichi (Tozan Building, 4-2 Nihonbashi Honcho 4-chom, Chuo-ku Tokyo 23, 10300, JP)

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