TUBE BENDING METHOD Russian patent published in 2003 - IPC

FIELD: plastic metal working, namely processes for bending thin-wall tubular blanks. SUBSTANCE: method comprises steps of flattening central portion of tubular blank, bending flattened portion and expanding flattened and bent portion for imparting to it toroidal shape; performing flattening operation simultaneously with bending flattened portion while tensioning it on mandrel; supplying controlled pressure inside blank; performing expanding of flattened and bent portion of blank to toroidal shape on mandrel at fixing end cylindrical parts relative to mandrel or in holder at fixing end cylindrical parts relative to said holder. EFFECT: simplified equipment and fitting for bending tubes, enlarged range of types and dimensions of articles formed from one type of tubular blanks. 4 dwg