Abstract: Apparatus for cooling a tubular thin film of thermoplastic resin in a melted state is described. The apparatus is capable of cooling the thin film from both the inside and the outside thereof while setting its diameter by interposing the film between the mandrel and an external circular coolant storage tank. The mandrel has a cylindrical shape and is connected with the lower side of a circular-shaped extruding die wherein the film is extruded downward from a circular slit in the die. The mandrel includes an air-injecting nozzle for injecting compressed air that maintains the shape of an upper bubble part of the thin film formed between the die and the mandrel. A coolant injecting nozzle which can inject the coolant toward the inner surface of the thin film is provided, the coolant injecting nozzle being formed into a single stage of circular slit or two or more stages of circular slits.

Abstract: Apparatus for cooling a tubular thin film of thermoplastic resin in a melted state is described. The apparatus is capable of cooling the thin film from both the inside and the outside thereof while setting its diameter by interposing the film between the mandrel and an external circular coolant storage tank. The mandrel has a cylindrical shape and is connected with the lower side of a circular-shaped extruding die wherein the film is extruded downward from a circular slit in the die. The mandrel includes an air-injecting nozzle for injecting compressed air that maintains the shape of an upper bubble pan of the thin film formed between the die and the mandrel. A coolant injecting nozzle which can inject the coolant toward the inner surface of the thin film is provided, the coolant injecting nozzle being formed into a single stage of circular slit or two or more stages of circular slits.