Nippon Steel Corporation

Shingo Tanioka

Mikio Yamanaka

Yasushi Ishikawa

Yutaka Sadano

Toshikazu Nakagawa

Tetsuro Inomata

A method of diametrically contracting a cylindrical body, includes the steps of grasping the cylindrical body with a plurality of elongated grasping members, preparing a cylindrical drawing die having an opening at one end and a tapered inside peripheral surface, drawing the grasping members together with the cylindrical body into the drawing die, through the opening, and applying a compression force to the cylindrical body through the grasping members due to the passage along through the tapered inside peripheral surface, to thereby cause the cylindrical body to be diametrically contracted. During the drawing process, since the cylindrical body does not come into direct contact with the drawing die, neither scratches nor baking cracks are produced on the outside surface of the cylindrical body.

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Tokai, Japan

Shingo Tanioka