Nippon Steel Corporation

Shigeru Uchida

Kazuo Watanabe

Kenzo Sawada

Minoru Kawaharada

Seiji Otomo

Mitsuo Hashimoto

Kousaku Ozawa

Masatoshi Ayagaki

Composite roll for rolling and process for producing the same

In a press-rolling process for producing a metal tubular product, which comprises a pipe-forming procedure in which a square metal billet is fed into a rolling mill which consists of a pair of pressing rolls which have semi-circular grooves forming circular shape and which is provided with a plug held in the center line of the circular shape, according to the present invention, the press-rolling process is characterized in that a cavity is formed in the center portion of the forward surface of the billet before the pipe-forming procedure, the diameter of the cavity corresponding to 70% or more but less than 100% of the diameter of the plug and the volume of the cavity being equal to or more than the volume of a portion of the plug located in the inserting side of the billet from the axial center of the rolling mill.

Press-rolling process for producing a metal tubular product

Growing community of inventors

Futtsu, Japan

Shigeru Uchida