Patent ID: 6062718
Filing Date: 2000-05-16
Classification: B29C

Abstract:
A flow circulation enhancing thermoplastic foam extrusion assembly comprising:a) a melt region structured to receive and melt a plurality of material pellets;b) an agent addition assembly structured to add a foaming agent to said material pellets;c) a mixing assembly structured to mix said melted material pellets and said foaming agent;d) a heat extraction region comprising:an elongate barrel, said barrel structured to receive said mixture of melted pellets and foaming agent therethrough and including at least one outlet defined therein,a heat extraction structure cooperatively disposed with said barrel and structured to draw heat from said barrel;an extrusion screw disposed in said barrel, said extrusion screw including at least one screw flight and being structured to urge said mixture of melted pellets and foaming agent towards said outlet of said barrel,said screw flight including at least one circulation channel defined therein and structured to receive quantities of said mixture of melted pellets and foaming agent therethrough so as to circulate said mixture of melted pellets and foaming agent, andat least a portion of said circulation channel including a flow through area smaller than an inlet area of said circulation channel so as to maximize a flow velocity and swell of said mixture of melted pellets and foaming agent from said circulation channel;e) a die structured to receive said mixture of melted pellets and foaming agent therethrough; andf) said melt region, said agent addition assembly, said mixing assembly and said heat extraction region being correspondingly defined and disposed relative to one another to achieve a flow of said mixture of melted pellets and foaming agent to said die.