Extrusion apparatus for tubular thermoplastic films including two

Abstract

An apparatus for cooling a tubular polymer film material which is being extruded, and more particularly, an apparatus for extruding tubular thermoplastic films including two tandem spaced air rings for controlling the cooling rate and production speeds of the thermoplastic films during extrusion thereof. Moreover, there is also disclosed a method for the cooling of an extruded tubular thermoplastic film material through the utilization of a tandem air ring cooling structure. An adjustable annular shroud is positioned intermediate the first and second air rings so as to allow for the inducement of external air immediately upstream of the first air ring, and which will permit the induced air and air from the first air ring to substantially egress through an annular gap provided between the shroud and the second or tandem air ring, thereby creating a vacuum which will draw the tubular film material into contact with the surface of the second or tandem air ring, and allow for an improved cooling due to the air added by the second air ring.