Patent ID: 7357890
Filing Date: 2008-04-15
Classification: B29C

Abstract:
1. An apparatus for extruding a multilayered structure, comprising: a housing defining a bore extending along an axis through the housing, the bore having a first portion positioned upstream with respect to an extrusion direction and a second portion positioned downstream of the first portion with respect to the extrusion direction; an extruder screw comprising an outer surface and having a screw thread extending helically along the outer surface and terminating on an end portion of the extruder screw, at least the end portion of the extruder screw being disposed in the first portion of the bore of the housing so as to define a first annular space between the outer surface of the extruder screw and an inner surface of the bore, the screw thread cooperating with the first portion of the bore such that rotation of the extruder screw advances a first melt stream of polymer material in a generally helical fashion along the first annular space; a shearing rod connected to the extruder screw such that the shearing rod is rotated by rotation of the extruder screw, the shearing rod extending into the second portion of the bore so as to define a second annular space between an outer surface of the shearing rod and an inner surface of the second portion, the second annular space being connected to the first annular space for receiving the first melt stream therefrom; and the housing defining a plurality of circumferentially spaced, generally radial passages extending through the housing and each having an opening at the inner surface of the second portion of the bore for feeding a plurality of second melt streams of polymer material into the second annular space to join with the first melt stream therein, the shearing rod rotating with the extruder screw such that the first and second melt streams are swirled together by the shearing rod as the streams advance along the second annular space, thereby creating a multiplicity of layers of the polymer materials.