| 摘要 |
<p>Plastics tubing is wound onto a mandrel under controlled speed over a guide shoe. Prior to passage over the shoe one side of the tubing is heat softened. The other side of the tubing is heat softened whilst in the mandrel so that in the wound tube the heat softened side of adjacent turns are in bonding contact. In an illustrated embodiment, the tubing is fed from an extruder via a tensioner which stores a length of tubing. The length in the tensioner is monitored and the mandrel speed controlled to ensure a constant length and thus constant feeding tension. The shoe pref. is in the form of a fixed part spiral which urges the tubing over the mandrel surface. The selective heating of opposite sides of the tubing prevents distortion, i.e. twisting, but maintains a good bond. Solar heating panel arrays can be made.</p> |
