METHOD OF MAKING CLOSED SHAPES WITH RECTANGULAR CROSS SECTION AND WITH CONNECTION LINE ON FLAT SURFACE OF ONE OF ITS FLANGES FROM SHEET MATERIAL Russian patent published in 1995 - IPC

FIELD: metal pressure forming. SUBSTANCE: method comprises steps of forming a shape by several transitions with subsequent operations of free and forced bending of flanges, being drawn together, and forced bending of lateral flanges; at the last transition with the forced bending of the flanges, being drawn together, bending these flanges along a radius with their convex surface, turned to outside; at the last transition with the formed bending of the lateral flanges subjecting these flanges to additional bending relative to dimensions of a ready shape up to taking away a gap between the flanges, being drawn together; then performing welding of the flanges with formation of anew flange, having a welded seam, upon welding operation acting upon the convex surfaces of the flanges by a pressure in order to level their edges, being welded, by the same height; after welding performing final shaping of the shape by unbending its lateral flanges up to dimensions of the ready shape and making a flat surface of the new flange with the welded seam; determining a bending value of the flanges, being drawn together, in a welding zone according to a relation, given in a description of the invention. EFFECT: enhanced quality of closed shapes. 1 cl, 4 dwg, 1 tbl