JPH03108288A - Forming method for cable connection section - Google Patents

Abstract

PURPOSE:To improve the work efficiency at the time of surface treatment and improve the adhesive property between cable insulators, a mold insulator and an outside semiconductor layer by applying required surface treatment to tapered sections and cylinder sections of pencil-shaped tip sections of cable insulators to be connected by a conductor. CONSTITUTION:The end section of a cable insulator 1 to be connected by a conductor is peeled in steps to form a pencil-shaped tip section constituted of a taper section 1a and a cylinder section 1b. The surface of the taper section 1a is polished in the peripheral direction with a polishing fabric, the surface of the cylinder section 1b is roughened in the axial direction by cutting, then an insulating mold 5 and an outside semiconductor layer 8 are formed. No finish machining is applied to the cylinder section 1b, thus the work efficiency at the time of surface treatment is improved, the adhesive property between the mold 5 and the layer 8 is improved by the rough surface of the cylinder section 1b, the circular irregularity on the surface by the polishing direction of the taper section 1a serves as the barrier in the edgewise direction, and the dielectric breakdown strength of a connection section is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method of forming a rubber-plastic cable connection.

(Prior Art) Conventionally, the connection portion of a crosslinked polyethylene insulated cable has been formed by the following method.

That is, as shown in the figure, first, the end of the cable to be connected is stripped off in stages, the exposed end of the cable insulator 1 is cut into the shape of a pencil tip, and the conductor 2 is compressed and connected using the conductor sleeve 3. The reason why the end of the cable insulator is cut into the shape of a pencil tip is to improve adhesion to the molded insulator and prevent electric field concentration from occurring at this part.

In addition, if the interface between the cable insulator cut into the shape of a pencil tip and the molded insulator is uneven or if the adhesion is insufficient, electrical stress will be concentrated in this area. The portion 1b and the tapered surface 1a cut into the shape of a pencil tip are further smoothed using sandpaper.

Next, an inner semiconducting layer 4 is formed on the outer periphery of the conductor sleeve 3 between the inner semiconducting layers 7 of both cables, and then a molded insulator on the spindle is formed between the cylindrical parts of the insulators 1 of both cables at this conductor connection part. 5 is molded, and further an outer semiconducting layer 6 is formed thereon, spanning between the outer semiconducting layers of both cables.

(Problem to be Solved by the Invention) However, in such a conventional method of forming a connection portion, the pencil tip-like portion of the cable insulator is first polished with coarse sandpaper and then further polished with fine sandpaper. Therefore, there was a problem in that it took a lot of time to finish both the cylindrical part and the penciled tapered surface of the cable insulator.

Furthermore, if the cylindrical part of the cable insulator is finished too smoothly, the adhesion with the molded insulator may deteriorate, creating voids at the adhesive interface, and the semiconducting layer of the cylindrical part may If particles of the abrasive material enter the formed portion, they may act as foreign substances on the mold insulator, resulting in a decrease in dielectric breakdown strength.

The present invention has been developed to address these issues, thereby increasing work efficiency when treating the surface of penciled cable insulation, and improving the adhesion of the cable insulation to the molded insulation and outer semiconducting layer. Our goal is to provide a method for forming cable connections that has improved properties and dielectric breakdown strength.

[Structure of the Invention] (Means for Solving the Problems) The method of forming the cable connection part of the present invention involves stripping the rubber/plastic cable to be connected and cutting the exposed end of the cable insulator into a pencil tip shape. In the method for forming a cable connection part, the method includes forming a spindle-shaped insulating mold on the outer periphery of the conductor, and then forming an outer semiconducting layer on the outer periphery of the cable insulator. After polishing the surface of the tip-shaped tapered part in the circumferential direction using coated abrasive paper, and roughening the cylindrical part following the tapered part by cutting it in the axial/linear direction of the cable using a cutting blade, The method is characterized in that the insulating mold and the outer semiconducting layer are formed.

When polishing the surface of the pencil tip-shaped tapered part of the cable insulator in the circumferential direction using coated abrasive paper, the final finish can be polished using coated abrasive paper of approximately No. 600. preferable.

Further, as the cutting blade used for cutting the cylindrical part following the taper part, a hard, blunt blade such as the back side of a saw blade or a piece of glass is suitable.

(Function) According to the present invention, the outer periphery of the cylindrical portion of the cable insulator is not finished with coated abrasive paper, but is easily roughened with a cutter, so that workability is improved.

In addition, since this part has a rough surface, it improves the adhesion between the cable insulator, the mold insulator, and the outer semiconducting layer, and also prevents abrasive particles from adhering to it, which reduces the dielectric breakdown strength of this part. Not at all.

On the other hand, since the pencil-tip tapered surface of the cable insulator is polished in the circumferential direction, this creates an annular unevenness on the surface, and this annular unevenness acts as a barrier against dielectric breakdown in the longitudinal direction. This also improves the dielectric breakdown strength of the connection portion.

Note that groove-like unevenness remains in the length direction on the outer periphery of the cylindrical part of the cable insulator, but this does not pose a problem in terms of dielectric breakdown because there is no longitudinal electric field in this part. .

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

In the present invention, as shown in the figure, first, the terminal end of the cable to be connected is stripped off and the exposed end of the cable insulator 1 is cut into the shape of a pencil tip using a conventional method. Next, the tapered surface 1a of this penciled insulator is polished in the circumferential direction using fine sandpaper from 240 grit to 320 grit sandpaper, then 400 grit sandpaper, and finally, the same process is performed using 600 grit sandpaper. Finish by polishing in the circumferential direction.

On the other hand, the surface of the cylindrical portion 1b of the cable insulator is roughened by cutting in the axial direction of the cable using the back side of a saw blade or a piece of glass.

At this time, in order to avoid damaging the cable outer semiconducting layer 8, the cable outer semiconducting layer 8 of the cable insulator 1 is
Make sure to cut from the side toward the conductor 2. These scraps after polishing and cutting should be carefully removed as they affect the breaking strength.

Next, the conductor 2 is connected using the conductor sleeve 3, and the inner semiconductive layer 4 is formed by winding a semiconductive rubber tape between the inner semiconductive layers 7 of the cable.

Furthermore, a spindle-shaped molded insulator 5 is molded between the insulators of both cables on the outer periphery of the aforementioned conductor connection part, and a semiconducting layer is formed on the outer periphery of the spindle-shaped molded insulator 5 to be electrically connected to the outer semiconductive layer 8 of the cable. The outer semiconducting layer 6 is formed by heat-shrinking a heat-shrinkable tube and making it tightly sealed.

The dielectric breakdown strength of the cable connection portion thus formed was 810 kV or more. On the other hand, if both the penciled tapered part and the cylindrical part of the cable insulator are finished with a saw blade, groove-like unevenness will remain on the surface in the axial direction, so it will be extremely sensitive to the electric field along the tapered part. In this case, the dielectric breakdown strength of the cable connection is 4
The voltage dropped to 50 kV, and dielectric breakdown occurred along the axis of the tapered portion.

[Effects of the Invention] As explained above, according to the method of the present invention, the surface of the cylindrical portion of the cable insulator is simply finished to a rough surface, which simplifies the work and shortens the work time. By making it a flat surface, the adhesion with the cable insulator and the outer semiconductive layer is also improved.

Furthermore, because coated abrasive paper is not used to finish the cylindrical part of the cable insulator, a peeling layer of abrasive material does not adhere to the surface. This improves the breaking strength of the cable connection.

[Brief explanation of drawings]

The drawing is a longitudinal sectional view of a cable connection section for explaining the method of the present invention and the conventional method. 1...-...Cable insulator 1a...
- Penciled tapered part 1b of cable insulator... Cylindrical part 2 of cable insulator...
...Conductor 3...Sleeve 4...Inner semiconducting layer 5...Mold insulator 6... ...outer semiconducting layer

Claims (1)

[Claims] (1) Strip the rubber/plastic cable to be connected, cut the end of the exposed cable insulator into a pencil tip shape, connect the conductor, form a spindle-shaped insulation mold around the outer periphery, and then In the method for forming a cable connection part in which an outer semiconductive layer is formed to reach a cable semiconductive layer, the surface of the pencil tip-shaped tapered part of the cable insulator is polished in the circumferential direction using abrasive cloth, and the taper A method for forming a cable connection part, characterized in that the insulating mold and the outer semiconductive layer are formed after the cylindrical part following the part is roughened by cutting in the axial direction of the cable using a cutting blade.