Single die co-extrusion apparatus for insulation
AssigneeGeneral Cable Corporation
InventorEdward Stanley Swiatovy, Jr.
Life of this patent
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Abstract
This invention is a single die by which thermoplastic insulating compounds can be co-extruded without any die for the first layer. It makes possible the extrusion of a high-density solid polyethylene skin layer over a cellular polyethylene primary insulation. Such a combination is difficult or impossible to make with a conventional co-extrusion die having a wire guide tip, one combination tip/die and a secondary extrusion die.
Claims12
A single die for co-extrusion including in combination a tip having a wire passage extending lengthwise therethrough and tapering to a smaller diameter toward a discharge end of the passage at the forward end of the tip, an extrusion die surrounding a forward end portion of the tip and having an inside surface that confronts the tapered surface of the tip and that is spaced from the confronting surface of the tip to leave an annular passage between the confronting surfaces for the flow of plastic electrical insulating material through said annular passage, characterized by a melt flow separator extending into the space between said confronting surfaces and dividing said space into two passages, one of which has its sides converging to reduce the radial width of the passage along the entire portion of its length that confronts the flow separator, for different materials for forming superimposed layers of insulation, the melt flow separator extending for a portion and only a portion of the length of said annular passage, the melt flow separator terminating at its forward end at a location spaced back from the discharge end of the tip so that the separator cannot serve as an extrusion die for said tip, passages in communication with said two passages for supplying different insulating material to the upstream ends of each of said two passages on the different sides of the melt flow separator, and the extrusion die having a tapered passage therein extending beyond the tip and in which the superimposed layers of insulation are sized before discharge from the die.
A single die for co-extrusion including in combination a tip having a wire passage extending lengthwise therethrough and tapering to a smaller diameter toward a discharge end of the passage at the forward end of the tip, an extrusion die surrounding a forward end portion of the tip and having an inside surface that confronts the tapered surface of the tip and that is spaced from the confronting surface of the tip to leave an annular passage between the confronting surfaces for the flow of plastic electrical insulating material through said annular passage, characterized by a melt flow separator extending into the space between said confronting surfaces and dividing said space into two passages for different materials for forming superimposed layers of insulation, the melt flow separator extending for a portion and only a portion of the length of said annular passage, the melt flow separator terminating at its forward end at a location spaced back from the discharge end of the tip so that the separator cannot serve as an extrusion die for said tip, passages in communication with said two passages for supplying different insulating material to the upstream ends of each of said two passages on the different sides of the melt flow separator, and the extrusion die having a tapered passage therein extending beyond the tip and in which the superimposed layers of insulation are sized before discharge from the die, characterized by the forward end of the melt flow separator being spaced back from the forward end of the tip by a distance less than the radius of the tip face outward from the discharge end of the wire passage through the tip.
Dependencies are inferred from the claim text.