METHOD OF PRODUCING CLOSED BENT SECTIONS Russian patent published in 1995 - IPC

FIELD: metal pressure forming. SUBSTANCE: method of producing closed bent sections, having asymmetrical cross section configuration, with one flange, turned inside of the section, and with other flange outside of the section; seven bending zones, forming five convex and two concave three-member portions, the last portions, being its second and seventh bending zones in direction from the flange to inside of the section, designed for use in ferrous metallurgy, tractor, transport and agricultural machine engineering, ship building industry, comprises steps of rotating an initial blank before profiling it and shaping it in rolls monotonically in a range of elasticity at each transition in direction of bending up the flange to inside of the section until achieving in the last transition a total rotation angle, whose value is being calculated according to a designed relation. EFFECT: enhanced quality of sections due to towered helical twisting of them relative to longitudinal axis at production process. 1 cl, 9 dwg, 2 tbl