METHOD AND DEVICE FOR FORMING STEEL BY THREE-POINT PRESS BENDING Russian patent published in 2018 - IPC B21D5/01 B21C37/08 

FIELD: moulding.

SUBSTANCE: invention relates to a method of forming a steel pipe of a steel sheet to give it a cylindrical shape, in which first the first half is molded by the method of multiple three-point press bending in the direction from one edge of the original steel sheet to the center of this sheet, then the forming of the second half by the method of three-point press bending in the direction from the other edge of the steel sheet along the width to the center of the sheet and the final molding by the three-point press bending of the central part of the steel sheet in width. Forming the first half is divided into preliminary molding, which is carried out before forming the second half, and subsequent molding, which is carried out after the molding of the second half, and the ratio of the width of the preforming region to the width of the steel sheet is set in a range from greater than 0.17 to less than 0.46.

EFFECT: as a result, it is possible to increase the maximum permissible diameter of the produced steel pipe without any modifications to the available bending press.

4 cl, 10 dwg, 1 tbl