AIR COOLING RING FOR PLASTIC FILM

摘要

A dual flow air ring (10) is used to cool the exterior surface of thermoplastic tube (40) after the plastic is extruded from an annular die (20). The surface of the wall forming the divider between the upstream and downstream flow paths which confronts the extruded tube (40) is shaped to include a region of decreasing diameter in the direction of tube travel so that the flow path for air issuing from the lower discharge (37) formed between the extruded tube (40) and the surface is caused to converge. This converging flow stabilizes the tube (40) thereby permitting more vigorous cooling and consequently higher production rates.