| 摘要 |
Apperatus to produce the tubes, for lost mould shaping of concrete, winds spiral coils of strips with a complex structure. The strip material has at least one outer layer, impermeable to water, of a thermoplastic material which can be fused to adjacent layers at a suitable temperature, through heat that softens the plastics for fusion bonding. The heater has a temperature control, with heat measurements at one or more layers of at least one of the strips at the entry into the strip spiral winding stage. |
