| 摘要 |
The present invention relates to a method and apparatus for the extrusion of tubular thermoplastic film which comprises extruding a melt of thermoplastic through an annular orifice to form a bubble or expanding cone terminating in a tube and while the expanding cone is still in a semi-molten condition, passing it through a prearranged cooling and shaping means comprising a plurality of air dispensing rings shaped in congruence with desired form of the expanding cone or film. Each air ring provides two converging or parallel air streams, each of which expands from the effluent port. The method and apparatus permits increased production speeds and minimized gauge variation in the expanded film.
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