JPS5568121A - Manufacture of large size square steel pipe - Google Patents

Abstract

PURPOSE: To cheaply manufacture the large size square steel pipe through the mass production, by cutting the material steel sheet after the straightening work into a specified length, by uniformly cutting both edges, by bending the material at the specified position, by forming the material into approximate square steel pipe, by applying the press work, and by welding the butt joint during the transportation.

CONSTITUTION: The steel sheet is uncoiled from the coil and is straightened with the leveler; after that, the sheet is successively cut into the specified length, and at the same time, both edges are uniformly cut; the bending work is applied by the press to the positions 16W19 equivalent to four corners of the square pipe. The degree of this bending work is specified as follows; the angle A of the corners 16, 19, is made about 92 degrees and the angle C of the corners 17, 18, is made about 115 degrees; and the sheet is formed into an approximate square pipe 13, which is then sent to the forming roll with the conveyer roller; where, the corners 17, 18, are pressed to 90 degrees, and the butt joint is successively welded with the high frequency welder during the transportation. Next, the straightening is carried out by the straightening press, etc., and the large size square steel pipe 14 is obtained. According to this method, the process can be made continuous and simple, and the cost can be reduced.

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