METHOD FOR MAKING ELBOW Russian patent published in 2000 - IPC

FIELD: machine engineering, possibly manufacture of elbow pipe for different pipeline system. SUBSTANCE: method comprises steps of placing thin-wall blank in two symmetrically arranged metallic mandrels of bending apparatus; using mandrels with cores. In the result blank is embraced along its whole length by outer and inner diameters. Mandrels with cores are turned relative to axis spaced from outer diameter of tubular blank by distance equal to one-two thickness values of blank. Simultaneously central portion of blank is flattened and blank is bent. At mutual turning of mandrels blank is fixed by its outer diameter in direction normal relative to bending plane. Then flattened and bent portion of blank is expanded by applying inner pressure. EFFECT: lowered cost of process for making elbow pipe, enhanced quality of it. 3 dwg