Patent ID: 6488399
Filing Date: 2002-12-03
Classification: B29B,B29C

Abstract:
A plasticating apparatus of the type having a heated barrel with an axial length wherein solid material is introduced through an inlet port and exits as a molten material through an outlet port, the heated barrel having an inner-wall and a screw rotatably supported therein, the screw having a core and at least one helical flight extending along its length defining a helical channel with the inner wall, said screw including at least a feed section cooperating with said inlet port, an intermediate melt section, and a metering section cooperating with said outlet port, the improvement comprising:a longitudinal portion in at least one of said screw sections, the longitudinal portion having a plurality of advancing grooves with each having at least one closed-end, said advancing grooves being arranged in a noncontinuous helix cut in the screw core in said helical channel of the screw, said plurality of advancing grooves being dimensioned to receive said material therein as the material is conveyed through said channel to said outlet port; and said longitudinal portion further having a plurality of noncontinuous retracting grooves traversing several advancing grooves, the retracting grooves forming a reverse helical path compared with the helical path of said flight, each retracting groove passing through the helical flight not more than two times so that some molten resin can back flow and recirculate within said longitudinal portion.