| 摘要 |
When helically winding sheet or band material without core in order to obtain tubes (12) having essentially a square cross-section, the continuously fed band (1) is periodically bent by an inner angle of the cross-section. The band (1) is guided during folding along a convex guiding surface (13) of which the inlet edge is situated in the feed plane of the band. In order to avoid hindering the subsequent feed of the band (1) and of the section already formed of the tube up to the next folding point, the centripetal guiding of the band (1) is interrupted when the outlet edge of the guiding surface (3) is reached. |
