METHOD FOR PRESS-MOLDING STEEL PIPE AND METHOD FOR PRODUCING STEEL PIPE

摘要

Provided are a method of press-forming a steel pipe with a small variation in a seam gap at butt welded portion and a method of manufacturing a steel pipe. In a method of press-forming a steel pipe by forming a steel plate by applying press bending to the steel plate a plurality of times, in accordance with a relationship obtained in advance between an additional pressing-down amount which is required further after a state that a predetermined seam gap is formed during applying press bending of a final time to an open seam pipe which is a material to be formed and the predetermined seam gap, forming with the additional pressing-down amount based on the relationship is applied to the open seam pipe from the state that the predetermined seam gap is formed during applying press bending of the final time to the open seam pipe which is the material to be formed.