| 摘要 |
Tubes, and those for packaging purposes in particular, are produced on equipment using a thermoplastic strip of film whose longitudinal edges are welded together; the film is formed into a tube by a belt and rollers wrapping it round a mandrel; the machine has a lower transporting band which is driven round in the mandrel and an upper band; the longitudinal edges of the film are overlapped between these two bands; the machine also has a heater acting on the top band, plus a pressure device and cooling arrangements. |
