Tubular film die assembly - has annular melt nozzle and external film cooling system with radial channels having air flow controlled by valves in channel

摘要

A die assembly used for mfg. blown tubular plastic film comprises: (i) a die head with inner and outer components; (ii) an annular orifice between the components for melt extrusion; (iii) an arrangement for introducing air into the tube for inflation; and (iv) an outer tube cooling system. The outer cooling system surrounds the annular nozzle and distributes air through an annular gap and nozzle close to the melt orifice. The cooling system consists of an assembly divided into segments forming radially aligned channels and connected to a cool air supply. Independently controllable valves are positioned in the radial channels to vary air flow in dirrerent segments. USE/ADVANTAGE - For prodn. of tubular film. Reduces thickness variation of the film to prevent build up of thickness errors in a single plane when the tube is coiled up.