| 摘要 |
Appts. for forming a blown film comprises an inflation forming die having a circular slit, an air ring surrounding the slit provided with an air-flow passage leading to an air ejecting slit, the air ejecting slit being defined by an outer lip having a tapered surface, the inner dia. there of increasing in the direction of withdrawal of a cylindrical film extruded through the circular slit, and an inner lip disposed closes to the die than the outer lip. The air press. is reduced in the space between the inner lip and the cylindrical film inwardly of the air ejecting slit by an air suction passage one end of which opens in the space and the other end of which opens in the air flow passage in the air ring.
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