JPS60128815A - Method of producing molding type connection unit for power cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates to crosslinked polyethylene insulated vinyl sheath milled connections.

C ■ When connecting cables, conventionally the ends of the cables are first stripped and then the conductors are connected with a conductor connecting tube, after which an internal semiconductive layer is formed, and then polyethylene containing a chemical crosslinking agent is applied. An insulating layer is created by winding Tezo, and after this insulating layer is melted and cross-linked, the surface is smoothed, and a tape- or tube-shaped external semiconductive layer is formed on top of it to form the connection part. .

In this conventional method, the adhesion between the insulating layer and the external semiconducting layer is generally insufficient, and minute interfacial defects tend to be formed, resulting in unstable insulation performance.

The object of the present invention is to eliminate the drawbacks associated with the above-mentioned prior art,
It is an object of the present invention to provide a method for manufacturing a molded connection part that has high insulation performance and can stabilize quality.

[Summary of the invention]

In the present invention, the heating temperature of the insulating reinforcing layer containing a chemical crosslinking agent at the connection part is set to be above the melting temperature of the insulating reinforcing material and below the crosslinking temperature, and after melt molding, a polyolefin-based external semiconductive layer is applied. The above object is achieved by subsequently melting and crosslinking the external semiconductive layer and the insulation reinforcing layer together at the crosslinking temperature of the insulation reinforcing layer material.

〔Example〕

FIG. 1 is a schematic cross-sectional view of a molded connection for a Cv cable formed by the method of the present invention.

In FIG. 1, the cable end 1 is subjected to step stripping treatment as shown, and then the conductor is connected with the conductor connecting tube 2. As shown in FIG. This method is similar to the conventional method in that an inner semiconducting layer 3 is then provided thereon, an insulating layer 4 made of polyethylene Teso containing a chemical crosslinking agent is further provided, and an outer semiconducting layer 5 is provided thereon.

According to the present invention, the insulating layer 4 is pre-molded by heating the polyethylene Teso at a temperature higher than its melting temperature and lower than its crosslinking temperature for a relatively short period of time after winding. After cooling, the surface of the preliminary mold is smoothed, and a tape or tube-shaped polyolefin semiconductive material is provided to form the external semiconductive layer 5, and then the whole is heated again at the crosslinking temperature of the insulating layer 4 to melt and crosslink it. . This heating is preferably carried out under pressure in order to prevent defects due to foaming or the like.

In the Mohr P type joint of the present invention formed in this manner, the adhesive pillars at the interface between the insulating layer 4 and the external semiconducting layer 5 are significantly improved, interface defects are minimized, and the fracture performance of the joint is significantly improved. improves.

FIG. 2 shows the adhesion strength at the interface between the insulating layer 4 and the external semiconducting layer 5 in the connection portion of the present invention in comparison with that in the conventional connection portion. As is clear from Figure 2, the interfacial adhesion strength of the conventional connection is 5 KF? On the other hand, in the connection portion of the present invention, it is in the range of 10Kp to 15Kp, and the degree of improvement is remarkable. Also, Figure 3 shows C■
This shows the relationship between the interfacial adhesion strength and breaking stress between the insulating layer and the external semiconducting layer at the connection part of the cable, and as is clear from this, the AC breakdown strength of the conventional connection part is about 10 KV/mm. On the other hand, that of the present application is about 15
The value exceeds KV/Ryu, and the degree of improvement is remarkable.

〔Effect of the invention〕

As described above, according to the present invention, the adhesiveness between the insulating layer and the external semiconducting layer interface is greatly improved by employing bulk crosslinking, thereby minimizing interface defects and thereby improving the fracture performance of the connection portion.

Further, defects can be further reduced by making the interface itself extremely smooth during pre-molding and shaping of the insulating layer.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a connecting portion formed according to the present invention;
FIG. 2 is a diagram showing the adhesive strength at the interface between the insulating layer and the external semiconducting layer in the connection part according to the present invention, and FIG. 3 is a diagram showing the relationship between the adhesive strength and the AC breakdown strength. □1...CV cable, 2...conductor connection pipe, 3...
...inner = 5- semiconducting layer, 4... insulating layer, 5... outer semiconducting layer. 6-

Claims (1)

[Claims] (1) Strip the end of the polyethylene insulated vinyl sheathed cable, connect the conductor with a conductor connection tube, provide an internal semiconductive layer on top of it, wrap it with polyethylene Teso containing a chemical crosslinking agent, and then The cross-linking polyethylene tape is heated to a temperature above the melting temperature and below the cross-linking temperature to melt it, and after cooling, the surface is smoothed and formed into a semiconductive material made of polyolefin material. A cross-linking method characterized by forming a layer, and then heating the cross-linked polyethylene molded layer and the semi-conductive layer to a cross-linking temperature and melting them all together to perform cross-linking to form an insulating layer and an external semi-conductive layer. A method for manufacturing a molded P-type joint for a polyethylene insulated vinyl sheath smear cable.