Sanyo Seiki Co. Ltd.

Kiyomasa Hoshi

Kenichi Harano

Electro-unite tubes having different plate thicknesses or different diameters are breakdown-formed without changing the upper rolls and the lower rolls of the breakdown pass rolls each time. Each of breakdown pass rolls 12 includes an upper roll 12a having a convex curved surface and a lower roll 12b opposed to the upper roll 12a, the lower roll 12b being provided with a V-shaped concave portion 13. A gap is maintained between a metal band plate 11 and the deepest portion D in the concave portion 13, and the metal band plate 11 is in local contact with the lower roll 12b. The upper roll 12a can be moved up and down, and the distance between the end of the curved surface of the upper roll 12a and the deepest portion D in the concave portion 13 is adjusted depending upon the plate thickness and the diameter of the electro-unite tube to determine the curvature (R.sub.1 or R.sub.2) for forming the metal band plate 11.

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Nagoya, Japan

Kiyomasa Hoshi