Vorrichtung zur Herstellung von Schlauchfolien aus thermoplastischem Kunststoff

摘要

Tubular films of synthetic organic thermoplastic material are produced by extruding the heated material through an annular extrusion orifice to form a tubular film, drawing the film over a hollow mandrel in air-sealing relation therewith and thence over driven haul-off nip rolls to form a first enclosed air space between the mandrel and the die and a second enclosed air space between the rolls and the mandrel, and passing a coolant through the mandrel to cool the film while maintaining air flow between the first and second spaces so that the pressures in them remain approximately equal. As shown in Fig. 1, hot thermoplastic material 12 is forced by the worm 13 from the supply vessel 14 through the chamber 11 of the die 10 and out of the annular die orifice 15 to form a tubular film 16. The tubular film 16 is pulled over a hollow mandrel 17 and spreader arms 30 by driven nip rolls 33, 34 and is wound upon a core 35. The mandrel 17 has rounded shoulders 28 and is suspended from the die 10 by a tube 18 provided with holes 22 for supplying a cooling liquid to the interior of the mandrel and with a smaller coaxial tube 19 having a liquid outlet connection 20. Cooling liquid supplied through the inlet 21 flows down through the space 23 between the tubes 18 and 19 and into the mandrel through the holes 22 in the pipe 18. The cooling liquid flows out of the mandrel 17 through the ports 27 in the hollow plug 24 and up the pipe 19 to the outlet 20. The space 36 within the portion of the tubular film 16 extending between the mandrel and the die and the space 37 within the portion of the film extending between the mandrel and the nip rolls as in free communication with one another through the pipe 38 extending through the mandrel. The pressure in the two spaces being thereby equalized. The pressure in the spaces 36 and 37 may be maintained at atmospheric pressure by removing the threaded plug 40 from the top of the passage 39 in the die 10, but the spaces 36 and 37 are preferably cut off from communication with the atmosphere.