| 摘要 |
PURPOSE:To enable high-speed forming of a film by a method wherein an air chamber formed of upper-and lower-end openings of specified measure is provided round an airing opening, thereby the cooling efficiency being raised and a bubble produced being stabilized. CONSTITUTION:A melted tubelike film 2 is extruded from a round die 1, while the cooling air is blown from an airing opening 3 against the film and then made to rise along the outer surface of the film 2. Round the opening 3 is provided an air chamber 4 having upper- and lower-end openings 6 and 5. The diameter D2 of the upper- end opening 6 is fixed to be 1.1-2.5 times larger than the diameter d2 of the round die. The lower-end opening 5 has a peripheral wall equipped with air-sucking orifices 7 or air-sucking slits near the lower end, as well as the diameter D1 larger than the diameter d1 of the opening 3. By the provision of the above air chamber 4, the flow of cooling air, being prevented from being turbulent, is made to form almost a laminar flow, thereby the cooling efficiency being raised, a bubble 10 being stabilized and thus an inflation film being formed at a high speed. |
