Maillefer Sa

Dr. Beck & Co Ag

Eberhard Kertscher

Ulrich Hochstrasser

Harald Janssen

A mixture of substances is fed to an extruder and, after being homogenized and liquefied, is extruded on an electric conductor or as a pipe. To meet electric cable specifications, the insulating material used is a polyolefin, such as polyethylene, cross-linking of which is brought about by the addition of a silane, a free-radical generator, and a silanol condensation catalyst. After extrusion, cross-linking takes place in the presence of moisture. To facilitate penetration of the moisture and accelerate cross-linking, an agent capable of reducing the rate of crystallization of the polymer, such as vinyl acetate, is used as a further additive.

Manufacture of insulated electric conductors

A method of manufacturing insulated electric wire of the enamelled-wire type wherein an insulating sheath adhering to the wire is formed by extrusion of selected thermoplastics which are heated to a temperature above their melting-point, then pressed onto the wire while in a fluid state. The extrusion apparatus includes a gauging die with a compressing cone having an aperture angle of from 2.degree. to 20.degree., preferably 7.degree..

Method for manufacturing electric wire having wire-enamel-type insulation

An apparatus for manufacturing insulated electric wire of the enamelled-wire type wherein an insulating sheath adhering to the wire is formed by extrusion of selected thermoplastics which are heated to a temperature above their melting-point, then pressed onto the wire while in a fluid state. The extrusion apparatus includes a gauging die with a compressing cone having an aperture angle of from 2.degree. to 20.degree., preferably 7.degree..

Apparatus for manufacturing electric wire having wire-enamel-type

A method of extruding a thin sheath of plastic material about electric wire, utilizing a plastic material capable of being shaped by extrusion after having been heated in a screw extruder, this material exhibiting the technical characteristics required for enamel-type insulation after cooling, without necessitating subsequent treatment. An extrusion material containing at least one partially crystalline thermoplastic polycondensate wherein the crystallites have a melting-point above 170.degree. C. answers these requirements.

Method of manufacturing insulated electric wire of the enamelled-wire

An installation is provided for extruding plastic material comprising a screw extruder having a cylinder provided with a hopper near the rearward end of said cylinder and with an extrusion head secured to the forward end of said cylinder, and at least one pump having a delivery pipe connected to at least one port disposed in the wall of said cylinder for delivering an additional fluid product to said extruder through said port or ports during the extrusion operation, the inner surface of said cylinder including a zone provided with grooves extending downstream starting from said hopper over a limited distance, said port or ports opening out into one or more of said grooved zone, said grooved zone being followed by a smooth zone, the inside diameter of which is less than the maximum diameter measured from the bottoms of said grooves, and wherein said screw extruder is of essentially uniform dimensions at the point of said zone and the portion of said screw extruder immediately upstream thereof.

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Romanel, Switzerland

Eberhard Kertscher