Patent ID: 6602064
Filing Date: 2003-08-05
Classification: B29B,B29C,B29K

Abstract:
A polymer processing apparatus comprising:an extruder having a barrel constructed to house a pair of twin polymer processing screws mounted therein, the extruder constructed and arranged to drive the screws counter-rotationally and to convey polymeric material within a polymer processing space in a downstream direction; and a blowing agent injection port fluidly communicating with the barrel and connectable to a source of blowing agent for introducing a blowing agent into the polymeric material in the polymer processing space, wherein the polymer processing screws include a blowing agent injection section having a series of full, unbroken flights, the blowing agent injection section being positioned adjacent the blowing agent injection port when the polymer processing screws are mounted within the barrel, and the full, unbroken flights are arranged to periodically block the blowing agent injection port as the polymer processing screws rotate within the barrel.