초록 ▼

An extruder screw mechanism has a barrel that is heated by heating coils, an internal screw, and a cylindrical melt sleeve having a plurality of circumferentially spaced, axially extending, radial slots there through located between the external barrel and the internal screw. Another embodiment of t

An extruder screw mechanism has a barrel that is heated by heating coils, an internal screw, and a cylindrical melt sleeve having a plurality of circumferentially spaced, axially extending, radial slots there through located between the external barrel and the internal screw. Another embodiment of the extruder has a barrel and an internal screw, with the internal screw having either a single central axial bore or a plurality of internal axial bores. The internal screw is provided with a plurality of external threads, with the threads each having a curved starting portion with a helix angle that has a finite value and gradually increases along an initial portion of the screw until the threads are substantially linear and parallel to the axis of the screw along the melting portion of the screw; a related embodiment has threadless portion separating the linear threads from the curved upstream threads. Circumferentially spaced, axially extending, radial slots extend from the outer surface of the screw along the melt section portion of the screw radially inwardly to an associated axial bore for removing melted polymer as it forms between solid polymer and a heated surface.

대표청구항 ▼

1. An extruder comprising:a screw having an outer surface, central axis, and upstream and downstream ends; a melting section having a barrel having an inner surface surrounding and enclosing said screw; said screw having an internal axial bore therein; said screw further including a plurality of cir

1. An extruder comprising:a screw having an outer surface, central axis, and upstream and downstream ends; a melting section having a barrel having an inner surface surrounding and enclosing said screw; said screw having an internal axial bore therein; said screw further including a plurality of circumferentially spaced external threads extending outwardly from said outer surface of said screw along a portion of said screw with said threads including linear thread portions which are substantially parallel to the central axis of said screw and which have an outer edge closely facing said inner surface of said barrel and wherein the portion of said outer surface from which the linear thread portions extend is of outwardly flaring shape so that the radial dimension of the linear thread portions decreases from an upstream portion to a downstream of the linear thread portions.