METHOD FOR PRESS-MOLDING STEEL PIPE AND METHOD FOR PRODUCING STEEL PIPE Russian patent published in 2018 - IPC B21D51/00 

FIELD: technological processes.

SUBSTANCE: group of inventions relates to a method of press-forming a steel pipe having a heavy wall thickness, particularly to a method of manufacturing a steel pipe by press bending. 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 after 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. Unconnected edges of the open seam pipe are then joined and sealed.

EFFECT: smallest gap between the open edges is provided by eliminating the spring.

3 cl, 6 dwg, 2 tbl