JPS5731410A - Manufacture of square steel pipe clad with dissimilar metal - Google Patents

Abstract

PURPOSE: To bring a sheet of a dissimilar metal into tight contact with a mother blank pipe so as to obtain a beautiful, clad square steel pipe, by employing an upper roll, a lower roll and a side roll having a breadth a little smaller than a breadth of the outer shape of the square steel pipe, for rolling a round steel pipe clad with a dissimilar metal.

CONSTITUTION: A round clad pipe 1, made by coating a mother blank material 2 with a thin sheet 3 of a dissimilar metal, is gradually roll-formed into a square shape by several stages of forming rolls installed in a roll forming machine; hereby, a square steel pipe 8 is finally obtained. A squaring roll is installed at the final stage of forming rolls of the roll formig machine; the breadth of the squaring rolling roll is made a little smaller than the length of a side of the square steel pipe 8; the squaring rolling roll is arranged so as to apply somewhat heavy rolling pressure to each plane of four sides of the square steel pipe 8. A clearance part 6 is provided in each corner part. Hereby, floating ad wrinkling caused by a spring back phenomenon due to the elasticity of the thin sheet of the dissimilar metal, thermal expansion, elongation, etc., are concentrated into the clearance part 6 so as to form a wrinkle 7.

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