CONTRACTING METHOD AND CONTRACTING JIG OF ROLLED STEEL PIPE, AND EXTENDING METHOD AND EXTENDING JIG OF ROLLED STEEL PIPE

摘要

PROBLEM TO BE SOLVED: To provide a contracting method and the like for a rolled steel pipe facilitating the diameter change of contraction or extension of the rolled steel pipe.;SOLUTION: This contracting method comprises a contracting jig arrangement process for arranging a contracting jig 10 having a receiving part 12 with a width larger than the contracted outer diameter of the rolled steel pipe 1 for receiving the rolled pipe 1 from above and a retaining part 11 arranged under the receiving part 12 and having a narrow width substantially corresponding to the contracted outer diameter of the rolled steel pipe 1; a rolled steel pipe arrangement process for arranging the rolled steel pipe 1 above the contracting jig 10; and a dropping process for successively dropping the rolled steel pipe 1 to the receiving part 12 and retaining part 11 from above the contracting jig 10.;COPYRIGHT: (C)2002,JPO