| 摘要 |
PURPOSE:To prevent generation of a bitten flaw, and to simplify a manufacturing process by rolling a pipe to a fixed diameter in a stage of the final side of a drawing process, in a manufacturing method of a welded pipe, having each process of forming, welding, drawing and cutting. CONSTITUTION:In a forming process, a heated skelp 1 is formed to a circular- arcuate shape by a forming roll 11 of a welding machine 10, and in a welding process, the edge of the skelp 1 is butted and welded by a welding roll 12, and in a drawing process, a welded pipe 2 is drawn and rolled to a size near a final product by an elliptical hole die of vertical rolls 13, 15... and horizontal rolls 14, 16..., also finished to the final produce size by a completely round hole die of horizontal rolls 22A, 24A and a vertical roll 23A, and in a cutting process, said pipe is cut to a prescribed length by a rotary hot saw 30. In this way, a welded pipe having no bitten flaw is obtained, and the manufacturing process is simplified.
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