METHOD OF PRODUCTION OF STEEL PIPE AND PRESSING DIE USED IN THIS METHOD Russian patent published in 2018 - IPC B21D5/01 

FIELD: technological processes.

SUBSTANCE: invention relates to a method for producing a steel pipe by bending a sheet material and a pressing die for carrying out the method. Curled sheet material is subjected to at least one bending operation in the widthwise direction of the sheet to form a preform having a U-shaped cross-sectional shape. Open pipe with a longitudinal gap between the side edges is formed by applying a bending force to the workpiece for the purpose of pressing, as a result of which the end surfaces of the side edges of the open pipe are connected to each other to form a steel pipe. Slightly curved portion having a slight bend compared to other areas or a non-bent portion that is not bent on at least a portion of the sheet material during bending and applying a bending force to a portion located from the center of the slightly curved portion or the non-curved portion in the direction of the edge portion of the sheet material at a distance of at least W/4, where W is the width of the sheet material, without restricting the slightly curved portion or the non-curved portion, in the process of pressing the blank to form an open tube. Press stamp includes two bending tools having a forming surface.

EFFECT: possibility to increase the efficiency of forming a steel pipe having a high roundness, with a relatively small bending force is a result of the invention.

10 cl, 15 dwg, 7 tbl, 9 ex