APPARATUS AND METHOD FOR FORMING STEEL PIPE USING THREE-POINT BENDING PRESS FORMING

摘要

PROBLEM TO BE SOLVED: To propose a method for forming a steel pipe that allows a maximum diameter of a producible steel pipe to be enlarged without requiring equipment modification of an existing press machine, in production of the steel pipe using a three-point bending press method (bending press method).SOLUTION: The method for forming a steel pipe is provided in which a raw steel sheet is formed into a substantially cylindrical shape via: a first-half forming process of performing three-point press bending a plurality of times from one widthwise edge of the raw steel sheet toward a widthwise center; latter-half forming process of performing three-point press bending a plurality of times from the other widthwise edge toward the widthwise center; and final forming process of performing three-point press bending on the widthwise center portion. In the method for forming a steel pipe, the first-half forming process is divided into a preceding forming process performed before the latter-half forming process and into a following forming process performed after the latter-half forming, and a forming range in the preceding forming process is set to be more than 0.17 and less than 0.46 times a steel plate width.