JPH0362479A - Manufacture of cable connecting part - Google Patents

Abstract

PURPOSE:To improve voltage-resistance characteristics by spindly forming an uncrosslinked mold insulator on the outer circumference of a conductor connecting part over cable insulators, then providing a thermally shrinkable material layer having gas permeability, and heating and crosslinking the connecting part in a pressurized inert gas. CONSTITUTION:The end parts of CV cables are peeled and exposed to connect the conductors to each other, and a mold insulator 13 consisting of polyethylene containing a crosslinking agent is spindly formed on this conductor connecting part 11 over cable insulators 12. A thermally shrinkable press layer 14 having gas permeability is provided thereon, and the connecting part is put into a crosslinking furnace 15 in this state, and heated and crosslinked while blowing an inert gas A such as dried nitrogen gas. Hence, the moisture content in the mold insulator can be reduced to improve voltage resistance characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention 1 (Industrial Application Field) The present invention relates to a method of manufacturing a cable connection part, and particularly relates to a method of manufacturing a cable connection part suitable for bridging a molded insulator of a Cv cable. .

(Prior art) Conventionally, when manufacturing the connection part of Cv cable,
The following method was used.

That is, as shown in FIG. 3, the ends of the cables to be connected are stripped off, the exposed conductors are connected to each other by a conventional method, and a cable insulator 2.
2, a molded insulator 3 made of polyethylene containing a cross-terminating agent is formed, and a gas-impermeable presser tape 4 such as Kapton tape is wrapped thereon, and in this state, it is placed in a cross-linking pot 5. In order to prevent deformation during heating, a method has been adopted in which the material is filled with an inert gas A such as dry nitrogen gas and heated and crosslinked while being pressurized by gas pressure.

(Problems to be Solved by the Invention) In the conventional crosslinking method described above, moisture generated from the mold insulator due to crosslinking of polyethylene and decomposed gas of the crosslinking agent are removed from the gas-impermeable presser tape 4 on the outside of the mold insulator. There was a problem in that because of the presence of , it was not released to the outside and remained inside the mold insulator, causing a decrease in withstand voltage characteristics. Furthermore, even if moisture from the polyethylene and crosslinking agent decomposition gas were to pass through the holding tape and be released to the outside, they would quickly become saturated within the crosslinking pot, resulting in the problem of remaining inside the mold insulator.

The present invention was made to solve these problems, and an object of the present invention is to provide a method for manufacturing a cable connection part that reduces the moisture content inside the molded insulator and improves the withstand voltage characteristics. shall be.

[Structure of the Invention] (Means for Solving the Problems) A method for forming a cable connection portion of the present invention includes forming an uncrosslinked molded insulator in a spindle shape on the outer periphery of a conductor connection portion and spanning the cable insulator; The method is characterized in that a gas-permeable heat-shrinkable material layer is provided on the mold insulator, and then heated and crosslinked while pressurizing and blowing an inert gas.

The method of forming a cable connection part of the present invention is particularly suitable for forming a connection part of a C■ cable.

In this case, the mold insulator is a polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, dicumyl peroxide, t-butyl It is formed by a known tape winding method, extrusion method, etc. using a composition containing a crosslinking agent such as peroxide.

In addition to CV cables, the present invention can also be applied to other rubber/plastic insulated cables that employ the same heat-crosslinking method.

(Function) A gas-permeable heat shrink material layer is provided in place of the conventional holding tape layer, and heating crosslinking is performed under a stream of pressurized inert gas, so moisture from the mold insulator and crosslinking agent decomposition are prevented. The gas is easily released to the outside of the mold insulation, and less moisture remains inside the mold insulation.

(Example) Next, one embodiment of the present invention will be described using the drawings.

In the present invention, Cv to be connected as shown in FIG.
The ends of the cable are stripped in steps, the exposed conductors are connected using a conventional method, and a molded insulator 13 made of polyethylene containing a crosslinking agent is placed on the conductor connection portion 11, spanning the cable insulator 12, using a known extrusion method or the like. Form into a spindle shape by tape winding method.

On top of this, it has gas permeability such as porous heat shrink tube,
In addition, a heat-shrinkable pressing layer 14 is provided, and in this state, the crosslinking pot 1 is
5, and dry inert gas A such as nitrogen gas at a gas pressure of 9.5 kg/cd G and a flow rate of 0.5 to 1.
Heating and crosslinking are carried out under conditions of 0/1 inch while blowing away.

The moisture content in the molded insulator of the cable connection portion thus obtained was as shown in the graph of FIG.

On the other hand, the moisture content in the molded insulator that was heat-crosslinked under the same conditions as in the example except that Kapton tape was used instead of the heat-shrinkable pressing layer 14 and that pressurized nitrogen gas was simply filled and heated. was as shown in the figure.

As can be seen from this graph, in this example,
We were able to reduce the moisture content in the molded insulator to less than half of the conventional level.

In addition, in the above example, the case where the present invention was applied to the manufacture of the connection part of a cV cable was explained, but the present invention is not limited to such an example, and the present invention is not limited to such an example. It can be similarly applied to forming connections for other rubber/plastic cables.

[Effects of the Invention] As explained above, according to the method of the present invention, a gas-permeable heat-shrinkable material layer is provided on the mold insulator, and cross-linking is performed by heating in a pressurized inert gas stream, so that cross-linking is not possible. Moisture and cross-linking agent decomposition gas that sometimes occur inside the mold insulator are easily released outside the mold insulator, reducing the moisture content in the mold insulator, suppressing the occurrence of water trees, poke trees, etc., and improving the withstand voltage characteristics. will improve.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a cable connection part for explaining an embodiment of the method of the present invention, Fig. 2 is a graph showing the moisture content in the molded insulator of the cable connection part, and Fig. 3 is a conventional method. FIG. 3 is a longitudinal cross-sectional view of a cable connection section for explaining. 11... Conductor connection part 12... Cable insulator 13...
...Mold insulator 15...Crosslinked pot 14... Gas permeable, heat-shrinkable pressing layer and

Claims (1)

[Claims] An uncrosslinked molded insulator is formed in the shape of a spindle on the outer periphery of the conductor connection section, spanning the cable insulator, and a gas-permeable heat-shrinkable material layer is provided on the molded insulator, and the insulation is heated under a stream of pressurized inert gas. A method for manufacturing a cable connection part, characterized by heating and crosslinking the cable connection part.