Apparatus for producing a spirally wound plastic article

Abstract

A strip of heated thermoplastic material is extruded from a die past first and second stations while the strip is drawn down between the die and the first station. Initial cooling of the strip is performed at the first station and further drawing down of the strip is effected between the first and second stations. The strip is thereafter guided through a plurality of spaced convolutions about a journaled cylindrical member driven at a peripheral speed substantially equal to the linear speed of the strip as it enters the second station. Substantial full cooling of the spiral strip is performed at the second station by a bath of cooling liquid through which the strip is linearly advanced and the strip is subsequently driven, at a linear speed substantially equal to the peripheral speed of the cylindrical member, from the second station into a third station in which the coiled strip is cradled between parallel rollers driven at peripheral speeds substantially equal to the linear advancing speed of the coiled strip. The cradled strip is subsequently annealed during its movement through the third station by both internal and external sprays of heated liquid thereon.