Patent ID: 6179461
Filing Date: 2001-01-30
Classification: B29C

Abstract:
An axially elongated extruder screw having a screw body including an axially extending extruding portion defined by a feed section at an inlet end of said screw, a metering section at an outlet end of said screw and a barrier section between said feed and metering sections, at least one helical primary flight extending about and coaxial with said screw body, said primary flight and said screw body cooperating to form a channel in said feed section for conveying resinous material from said feed to said barrier section; said barrier section further comprising:at least one helical secondary flight extending from said primary flight about said screw body, said screw body defining a helical first surface of revolution between said primary and secondary flights;at least one helical tertiary flight positioned between said primary and secondary flights and extending about said screw body, said screw body defining a second helical surface of revolution between said secondary and tertiary flights, and a third surface of revolution between said primary and tertiary flights, said second and third surfaces of revolution extending axially along said barrier section;each of said second and third surfaces of revolution define a series of circumaxially contiguous cam-like forms, each cam-like form being defined by a segment of said screw having a root, a crest, a first surface portion extending radially outwardly from said root to said crest in the direction of screw rotation, and a second surface portion extending radially inwardly from said crest to said root; and whereinsaid first surface of revolution is substantially planar and free from any surface undulations.