Abstract:
Provided is a method for forming a steel pipe for forming a steel plate as raw material into a substantially cylindrical shape, by first half forming performing three-point bending-press a plurality of times from one plate width end portion of the steel plate as raw material toward a plate width center, second half forming performing three-point bending-press a plurality of times from the other plate width end portion toward the plate width center, and final forming performing the three-point bending-press on the plate width central portion, wherein the first half forming is divided into preceding forming performed before the second half forming and succeeding forming performed after the second half forming, and a ratio of a forming range in the preceding forming to the steel plate width is set in a range of more than 0.17 to less than 0.46. Thus, a producible maximum diameter of the steel pipe is enlarged without modifying the equipment of the existing pressing machine.