Abstract: An air ring for supplying cooling air to a hot extruded plastic film after extrusion from an annular extrusion die has an annular body surrounding the emerging tubular plastic film. The annular body has an annular plenum chamber receiving air from an external source. A circumferentially extending series of separate air passages receives air from the plenum chamber and extends radially inwardly to respective separate orifices adjacent to and surrounding the tubular film. Separate adjustors individually control the air flow from the plenum chamber to respective air passages and associated orifices, whereby air flow from each orifice impinges on a discrete circumferentially extending portion of the tubular film substantially independently of air flow from other orifices. Each adjustor controls air flow to only one orifice. The plenum chamber also supplies air through an annular passage in the annular body to an annular orifice adjacent to and surrounding the tubular film.

Abstract: An air ring for supplying cooling air to a hot extruded plastic film after the film has been extruded from an annular extrusion die at an elevated temperature, has an annular body which in use surrounds the hot tubular plastic film after the film has left the extrusion die, said annular body having an annular plenum chamber to which air is supplied from an external source. A circumferentially extending series of separate air passages communicates with the plenum chamber for receiving cooling air therefrom and extending radially inwardly to respective separate orifices which in use of the air ring are adjacent to and surround the hot tubular film.