Tube bend section forming method - involves winding flat strip in spiral with beaded-over joint on inside

摘要

The method forms a bend in a tube made from a strip of flat material whose edges are secured together by a beaded-over joint. Folds are formed in the transverse direction of the tube. The tube is first formed by winding the strip in a spiral (1) and forming the joint (2) on the inside, after which the transverse folds (4) are formed.