METHOD OF MAKING THE FLEXIBLE RETURN BENDS Russian patent published in 2014 - IPC B21D9/12 

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, particularly, to production of flexible return bands. First, skews are made at pipe billet ends, the filler being placed there inside and cylindrical shells being fitted at inlet end in symmetry about the smallest and the largest generating parts with OD equal to billet ID. Note here that the part of cylindrical shell is arranged in symmetry about the smallest generatrix and oriented primarily in meridional direction while the shell part is arranged in symmetry about the largest generatrix directed primarily in circumferential direction. The shell part arranged in symmetry about the largest generatrix directed primarily in meridional direction is made from the plate in length equal to (D+20) mm where D is billet OD, mm, width equal to (0.08D+18.25) mm, while the shell part is arranged in symmetry about the largest generatrix directed primarily in circumferential direction is made from the plate in length of 2.11D mm, in width equal to (0.25D+17.31) mm, and side skews parallel with billet skew on inlet end side.

EFFECT: higher quality, lower costs of the flexible return bends.

5 dwg, 1 ex