| 摘要 |
<p>In a machine for the formation of helical lock-seam tubing, guide rollers (24A, 25B) are arranged to locate superposed metal strips (9, 11) in laterally staggered relative positions in such a manner that the strips can be passed through forming and clinching means whilst in the overlapped state, whereby finished tubing has a locked seam with each of the walls joined in the seam being formed by multiple layers of metal strip.</p> |
