| 摘要 |
Hollow objects 14 can be formed by extruding a web 1 of thermoplastic material directly into a set of temperature controlled tempering rolls 2, 3 and 6, cooling upper and lower surface layers of the web by passage through the tempering rolls while maintaining the interior of the web in molten condition between said surface layers, feeding the partially cooled web 7 past a turning roll 8 onto a conveyor 10, and conveying the web to the entry of a thermoformer 15, the web 7 being allowed to remain on the conveyor 10 until the surface layer of the web which is in contact with the conveyor has been reheated by the molten interior of the web to a thermoformable temperature below that at which the web 7 will stick to the conveyor 10, the travel of the web 1 through the tempering rolls being controllable by adjusting the position of the tempering roll 6 to for example 6', and the travel of the web 7 on the conveyor being controllable by adjusting the position of the turning roll 8 to for example 8'. |
