IMPROVEMENTS IN AND RELATING TO THE FORMATION OF HELICALLY WOUND LOCK-SEAM TUBING

摘要

In a method of producing helically-wound lock-seam tubing from a metal strip, by clinching together interlocking flanges formed at opposite margins of the strip, the central portion (1) of the strip is supported during clinching of the flanges in such a manner that the respective portions (1) of two adjacent helices wound to form the tubing are relatively radially displaced.