Apparatus for producing foamed plastic insulated wires

摘要

An extrusion apparatus and method for producing foamed resin coatings on a wire. A foaming agent and molten resin are poured into a supply portion of an extruding screw and cylinder apparatus. The screw in the supply portion is tapered in the down stream direction. The screw and cylinder apparatus portion adjacent to the supply portion is arranged to blend the resin and foaming agent and has a lower coefficient of extrusion than the supply portion. The metering portion of the screw and cylinder apparatus is adjacent and down stream of the blend portion and has a higher coefficient of extrusion than the blend portion.