SU1007561A3 - Apparatus for insulating cable articles by extruding vulcanizable polyoleffins - Google Patents

Abstract

1480632 Extrudate lubrication DAINICHI NIHON DENSEN KK and MITSUBISHI PETROCHEMICAL CO Ltd 22 Aug 1974 [22 Aug 1973] 36918/74 Heading B5A [Also in Division H1] An electric cable conductor 11 is sheathed with an extruded cross-linked polyolefin during passage through the constant section circular outlet bore of a heated extrusion die 3a, which effects curing of the polyolefin, and degradation of the polyolefin in the outlet bore is prevented by a lubricant continuously introduced along a tapering inlet 3c to the outlet bore, to the surface 3c of which lubricant is continuously supplied at a location upstream of the downstream end of the tapering inlet 3c. The lubricant may be supplied to the inlet 3c through a porous sintered metal surface, or through an annular slit 8, e.g. of 0À005 to 1 mm. thickness, which is located between 10 mm. downstream of the upstream end of inlet 3c, and 2 mm. upstream of its downstream end. The slit 8 is defined between die members 3a, 3b, clamped together by a member 4, at a seal 5. The inlet 3c is of 50 to 200 mm. length and the circular bore of die 3a is of 1 to 50 m. length, and preferably 5 to 30 m. length, and may be defined by a plurality of assembled shorter die pieces. The die 3a is heated electrically, or by a hot oil jacket, e.g. to 200‹ to 300‹ C., and the cured sheathing issues from the die directly into a pressurized water cooling device (not shown). Various polyolefins and curing agents are specified, and the lubricants are of specified properties and may be these described in Specification 1,380,942. The example relates to the simultaneous extrusion of an insulating sheathing of polyethylene, between inner and outer semiconducting layers of ethylene-vinyl acetate copolymer containing carbon black.

Description

The invention relates to electrical engineering, in particular to cable technology and can be used in the manufacture of cable, in particular high-voltage, insulation from vulcanizable polyolefins, for example, polyethylene.

Known devices for applying insulation to cable products made of vulcanizable polyolefins by extruding material and then vulcanizing it in an elongated part of the CO matrix.

A disadvantage of the known device is the roughness of the insulation surface, which is a consequence of the disruption of the material flow when it expires from the matrix.

to the conical device, the transition from the elongated part of the matrix and the cooling device located after the elongated part of the matrix, a channel in the matrix body, communicating with the annular recess on the inner surface of the matrix, designed to supply material on the inner surface of the matrix, facilitating the flow of the extrudable material, I ring recess made on the conical part of the matrix.

The drawing shows an extruder head with an elongated die, section.

The device comprises an extruder head 1, an extrudable material 2, a mandrel 3, a die 4, a cable core 5, an annular groove 6 in the die body, a channel 7 for supplying material facilitating the flow of the extrudable material, a cylindrical die portion 8, a conical die portion 9, a heating device 10, the cooling device ΐ1.

The device operates as follows *.

The cable core 5 passes through and enters the cylindrical part of the matrix. In the gap formed by the mandrel 3 and the conical surface 9 of the matrix, the material 2 is fed by the extruder, which moves in the gap between the mandrel and the matrix.

Upon transition from the conical part to the cylindrical part 8, turbulence occurs in the material 2. Material facilitating the flow of mass 2 is fed through channel 7 to the annular groove 6 and falls on the interface between the mass 2 and the conical surface 9 of the matrix. Due to the fact that the material ^ facilitating the flow of the extrudable material, it is fed to the zone of distortion of the mass flow 2, the friction of the mass on the matrix walls in this zone is significantly reduced, which leads to equalization of the flow and improve the surface quality of the insulating layer. In section 10, the extrudable material is heated and vulcanized, and in section 11, the cable is subjected to intensive cooling under the pressure of water in the cooling device 11.

A device is known comprising an extruder head, a mandrel and a matrix with a conical and elongated cylindrical part, as well as a device for heating the elongated part of the matrix and cooling the product when the latter exits the matrix, a forming coagent is applied to the inner surface of the elongated part of the matrix, region! the flow of material along the elongated part of the matrix. The specified coagent is fed into an annular groove made in the cylindrical part of the matrix adjacent to the part G2 J.

The disadvantage of this is that with the conical part toward the cylindrical flow: the material changes direction, as a result of which layers with a slowed flow along the walls of the matrix are formed in the transition zone from the conical part to the cylindrical. As a result of this, said layers undergo neper; EVA and partially burning, which leads to a decrease in electrical strength.

The aim of the invention is to improve the quality of insulation.

This goal is achieved by the fact that in the device containing the extruder head and the mandrel placed in it and a matrix with an elongated cylindrical part and a conical part, a heating device

VNIIIPI Order 2164/78

Circulation 701 Subscription

Branch of the PPP Patent, Uzhgorod, Project 4,

Claims (1)

DEVICE FOR APPLYING INSULATION ON CABLE PRODUCTS BY EXTRUDING VULCANIZED POLYOLEFINS, containing an extruder head and a mandrel placed therein. and a matrix with an elongated cylindrical part and a conical part, a device for heating the elongated part of the matrix and a cooling device located after the elongated part of the matrix, a channel in the matrix body in communication with the annular recess on the inner surface of the matrix, designed to supply material to the inner surface of the matrix , facilitating the flow of extrudable material, characterized in that, in order to improve the quality of insulation by optimizing the flow of mate. rial in the matrix, an annular undercut is made in the conical part of the matrix. ) 07561 Y || 1 »1111111111NNS 1 1007561