| 摘要 |
810,703. Extruding tubes. S.A.S. LAVORAZIONE MATERIE PLASTICHE (L.M.P.) DI M.I. COLOMBO & C. March 1, 1957 [March 22, 1956], No. 6886/57. Class 87(2). Tubes of thermoplastic material are extruded by causing the material heated to its softening point to travel through a tubular shaping passage 17, cooling the outer surface of the tube within a terminal section 17a of the passage to cause at least partial setting while maintaining the inner surface in a softened condition, and guiding the inner surface over a polished support 15a while further cooling the tube from the outside to remove heat from the inner surface and to solidify it. In the figure a core 15 is supported by a spider 14 in a bore through casings 12, 13 to confine a tubular passage 17 having an inlet 18 and an outlet section 17a. A restriction 17d may be provided on the portion 17c of passage 17 to oppose the flow of material and thus avoid the formation of voids by the blades of the spider 14. Electric heating means 27, 32 are provided to heat the outer and inner walls of an intermediate section 17b of the tubular passage 17 and a cooling jacket 22 surrounds the outlet section 17a. A core extension 15a has a polished outer surface to support and guide an extruded tube T issuing from the tubular passage 17. The external layers of this tube are set by coming into contact with the cooled surface 20, which is highly polished, while the internal layers remain fluid until cooled, while supported on extension 15a, by water sprayed from nozzles 40. The lower nozzles may be replaced by a trough of water in which the extruded tube is partly immersed. The radial thickness of section 17a is inwardly enlarged, thus admitting of a slight shrinking of the tube T upon cooling of its external surface by the surface 20 and also' affording a supplementary clearance to which a certain quantity of still fluid material can flow. |
