Patent ID: 6752528
Filing Date: 2004-06-22
Classification: B29C

Abstract:
A plasticity apparatus comprising a heatable barrel having inlet and outlet openings; a rotating screw having a root, a helical flight disposed about the root defining a helical valley, said flight being disposed within and cooperating with an inner wall of said barrel; whereby particles of resinous material are introduced through said inlet opening to the helical valley extending along the axis of the screw to be plasticated by said screw and advanced toward said outlet opening; said screw comprising a feed section, a transition section, and a metering section in succession; said flight having a generally constant pitch in the feed and transition sections, said root defining a tapered terminus at a location between the transition and metering sections wherein an increase of the flight pitch begins and said tapered terminus defining a stepped change in said root having a length along said axis which is less than or greater than the length of the increased flight pitch; a portion of said root downstream of said stepped change in said root defining a shallow flight depth in the metering section.