TUBE BENDING METHOD Russian patent published in 1995 - IPC

FIELD: metal pressure forming. SUBSTANCE: method comprises steps of flattening a tube blank, bending its flattened portion and expanding it by an inner pressure. The flattening operation is being performed until making a gap between parallel walls no more, than 1.5 of a thickness value of the tube. Rounded portions are being remained on edges, the portions having radius, consisting 5...10 thickness values of walls of the tube. Such method eliminates a possibility of cracking formation at flattening operation and ripples at bending operations. EFFECT: enhanced quality of the article, enlarged manufacturing possibilities. 1 cl, 5 dwg, 1 tbl