A PROCESS FOR PRODUCING ORIENTED PLASTIC TUBE

摘要

A start-up sequence for a continuous process for producing oriented plastic tube is disclosed. A variable diameter extruder (112) is started and is set to extrude a start-up diameter tube (220) which is significantly over the diameter of a pre-expansion tube diameter of the continuous process. The start-up diameter tube (220) is passed to and engaged by a first haul-off tractor (122). The start-up diameter tube (220) proceeds through to and over an upstream plug (128). The large, start-up diameter of the extruded tube (220) at start-up facilitates passage of the leading end of the start-up diameter tube (220) over a deflated, expandable portion (212) or a non-expandable portion (210) of a partly expandable plug (210, 212), depending on the arrangement of the expandable portion (212) and non-expandable portion (210). The tube is then reduced in diameter for the continuous process of diametral expansion and circumferential orientation to occur.