Improvements in or relating to the manufacture of tubes of plastic material, and more particularly of polyamides

摘要

A tube 3 of polyamide or other thermoplastic material extruded from a die 1 is cooled in a passage 5 which has the same cross-section as the tube. On the inner wall of the passage is a groove 8, which is inclined to the axial direction of the passage and extends to the ends of the latter, and to which is fed a liquid lubricant and coolant. The groove is in two parts which are of opposite hands and extend from a central supply passage 10. The groove may have the section shown in Fig. 3. The wall of the passage may be of poly-tetrafluoroethylene or polymonochlorotrifluoroethylene, to prevent sticking. The passage may be immersed in a tank of water.