JPH1032919A - Connection part structure of cv cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To unload air easily from a cable core side when performing extrusion and crosslinking simultaneously at the connection part of a CV cable. SOLUTION: With the connection part structure of a CV cable, the connection part of cables 1a and 1b where conductors 3a and 3b have already been connected into a mold and a connection part external semiconductive layer 7 that is externally fitted on the connection part are set, a melted resin is injected from an extruder via an injection port 7a, and then the resin is heated for forming an extrusion insulator 6. An air discharging part 8 is provided at the inside of the connection part external semiconductive layer 7 at a part where the connection part external semiconductive layer 7 is fitted on to discharge air in an extrusion. The air discharging part 8 is achieved by providing a groove in the longitudinal direction of the cable on the inner surface of the connection part external semiconductive layer 7, thus reducing the execution time of the connection part and improving the processability of extrusion forming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a connecting portion of a CV cable.

[0002]

2. Description of the Related Art CV (Crosslinked Polyethylene insul)
ated polyVinylchloride sheathed) If a cable is connected midway, a connection is formed at that point. This connection part is roughly classified into a prefabricated type, a tape wound type, a mold type, and an oil immersion type. Among them, the mold type is TM
J (Taping Molded Joint) and EMJ (ExtrusionMoldedJ
oint). In the case of the EMJ type, a method in which an extruder is carried into the site, a resin material (for example, polyethylene containing a cross-linking agent) is extruded in combination with an extrusion die to form an insulator, and then cross-linking is performed. And is used, for example, to connect a 275 kVCV cable. As described above, since the EMJ mold has the extrusion step and the cross-linking step, there is a problem that the construction time is long.

[0003] In order to shorten the construction time of the mold connecting portion, a block mold using a polyethylene block containing a crosslinking agent or a simultaneous mold in which an external semiconductive layer is provided in a mold to perform extrusion and crosslinking. Construction methods are being developed. This molding method requires a structure capable of discharging air at the interface in the melt molding step of the insulator. In particular, there is no means for effectively discharging air (or air in the mold) at the interface between the high-temperature crosslinking step block of the mold and the cable.

[0004]

However, according to the above-mentioned conventional block molding die or the molding method in which an external semiconductive layer is provided on the inner surface of the die, it is necessary to discharge air from the cable core side. When discharging from the cable core side, the interface between the external semiconductive layer of the connection part and the external semiconductive layer of the cable will be used. At the same time, electrical weaknesses (such as a decrease in insulation) must be prevented, but a practical structure for achieving this has not yet been proposed.

Accordingly, an object of the present invention is to provide a connection structure of a CV cable capable of facilitating air discharge from the cable core side when crosslinking is performed simultaneously with extrusion.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an extruder and a mold, which are used to deposit a molten resin in an external semiconductive layer which has been previously fitted to a connection portion of a CV cable. Inject and heat mold to form insulation reinforcement
In the connection portion of the V cable, the external semiconductive layer has an air discharge portion inside a portion externally fitted to the cable, so that a connection portion of the CV cable is provided.

According to this configuration, as the molten resin is injected from the extruder, the air in the outer semiconductive layer is discharged to the outside through the air discharge portion provided between the cable and the outer semiconductive layer. You. Therefore, with a simple structure, crosslinking can be performed at the same time as extrusion, so that the connection time can be reduced, the workability of extrusion molding can be improved, and the like. The air discharging portion may be configured to be at least one groove formed on an inner surface of both ends of the outer semiconductive layer.

According to this structure, the air discharge portion can be formed by forming the air discharge portion on the inner peripheral surface of the external semiconductive layer of the connection portion, and the simplest structure can be achieved. Therefore, the air discharge portion can be formed at the lowest cost. The air discharge unit may be an insulating sheet wound around or externally fitted to the cable and having slits provided at regular intervals in a circumferential direction.

According to this structure, since the air discharge portion can be formed using the connection portion external semiconductive layer having the conventional structure, it is not necessary to newly design and manufacture the connection portion external semiconductive layer.
In addition, if prepared according to the size of the cable and the external semiconductive layer of the connection portion, any cable and external semiconductive layer of the connection portion can be used. The air discharge unit is
Carbon fibers provided on inner surfaces of both ends of the outer semiconductive layer can be used.

According to this configuration, as the molten resin is injected from the extruder, the air in the outer semiconductive layer is discharged outside through the carbon fibers. Therefore, air can be exhausted at the time of heating the mold, and at the same time, there is no decrease in electrical performance. The air discharging portion is a two-layer structure of a high-melting-point semiconductive layer externally fitted to the cable and a low-melting-point semiconductive layer provided outside thereof, and is integrally formed at both ends of the external semiconductive layer. Can be provided.

According to this structure, the low-melting semiconductive layer is used when the external semiconductive layer is externally fitted to the cable and when the cable is extruded. A semiconductive layer is used. Thus, the air discharge and the cable fusion of the outer semiconductive layer are performed in a shared manner, and the air discharge and the cable fusion are reliably performed. It is preferable that the length of a portion of the air discharge portion overlapping the cable is 50 mm or more and 200 mm or less.

According to this structure, the air can be reliably discharged from the outer semiconductive layer when the molten resin is extruded, and the connection between the outer semiconductive layer and the cable can be surely performed. There is no.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the structure of a connecting portion of a CV cable according to the present invention (the cable portion is a front view).
It is. When connecting the ends of the cables 1a, 1b, the cables 1a, 1b are connected to the insulators 2a, 2b from the outer semiconductive layer.
(Cross-linked polyethylene, etc.) is exposed (the tip is processed into a conical shape like a pencil tip toward the conductor). Further, the central conductors 3a and 3b are exposed to a predetermined length. Conductor 3a
The conductor 3b is connected to the conductor 3b by a metal conductor sleeve 4. On the surface of the conductor sleeve 4, an inner semiconductive layer 5 is provided.

Further, insulators 2a and 2b, conductors 3a and 3b
The exposed portion of the conductor sleeve 4 and each surface of the conductor sleeve 4 are extruded by extrusion molding using an extruder and an extrusion die (not shown).
It is formed to be slightly thicker than the outer diameters of a and 1b. A connecting portion external semiconductive layer 7 is formed so as to cover the extruded insulator 6, the central portion thereof is thickly processed, and an injection port 7a for supplying polyethylene containing a crosslinking agent from an extruder is provided.

FIG. 2 shows the connection part external semiconductive layer 7 and the cable 1.
FIG. 2 is an enlarged cross-sectional view showing the arrangement state of a and 1b (however, a cable portion is a front view). Connection part external semiconductive layer 7
Is designed such that a predetermined length overlaps the cables 1a and 1b, and the connection portion external semiconductive layer 7
An air discharge portion 8 having a shape as shown in FIGS. Connection part external semiconductive layer 7
Uses a heat-shrinkable semiconductive polyolefin tube or molded tube, but heat shrinks only in the air discharge portions 8 at both ends.

The air discharge portion 8 can be processed into the connecting portion external semiconductive layer 7 or separately provided between the connecting portion external semiconductive layer 7 and the cables 1a and 1b.
The air discharge section 8 serves as an air discharge port when the extruded insulator 6 is formed by extrusion. FIG.
(A) is a diagram in which a groove 8a is provided in an inner peripheral surface of an end portion of a connection portion external semiconductive layer 7 in a longitudinal direction of a cable to form an air discharge portion 8. The grooves 8a are provided at regular intervals in the circumferential direction. (B) is an example in which the air discharge unit 8 is configured by a separate component, in which a slit 9b is provided in the cable longitudinal direction of a cylindrical (or wound around a cable) polyethylene sheet 9a (provided at regular intervals in the circumferential direction). Used) polyethylene sheet 8b. The polyethylene sheet 8b is inserted into the cables 1a and 1b at the portions overlapping the ends of the connection portion external semiconductive layer 7. (C) is an example in which a carbon fiber layer 8c is formed into a two-layer molded body in which an inner peripheral surface of an end of the connecting portion external semiconductive layer 7 is interposed. For example, by weaving long fibers as the carbon fiber layer 8c to form an inner surface layer, air during extrusion is reduced to an inner carbon fiber layer 8c.
discharged through c. (D) shows a high melting point semiconductive layer 10 (having a melting point of 12) inside the end of the connecting portion external semiconductive layer 7.
5 ° C.) and a low melting point semiconductive layer 1 provided on the surface thereof.
1 (melting point is about 90 ° C.), and an air discharge portion 8 having a two-layer structure is integrally formed at an end of the connection portion external semiconductive layer 7. In this structure, when covering the cable, the contracting force of the low melting point semiconductive layer 11 is used. (At this time, since the high melting point semiconductive layer 10 is not fused to the cable, the internal air during extrusion is reduced to the high melting point semiconductive layer. 10 through the gap inside).

Although four examples have been shown here, the present invention is not limited to this structure, and any structure may be used as long as the air in the connection portion external semiconductive layer 7 is discharged in accordance with the extrusion. There may be. The length of the air discharge section 8 is set as shown in FIG. That is, the connection portion external semiconductive layer 7
At the time of heat contraction, L ₁ extends from the tip of the connection portion external semiconductive layer 7 at the rising portion of the connection portion to the insulator 2a, 2b side.
= 200 mm or less, and L ₂ = 50 mm or more on the connection portion external semiconductive layer 7 side. In addition, 12 in FIG. 4 is a polyethylene material before crosslinking injected by an extruder.

Next, the connection procedure of the present invention will be described. First, the outer conductor 7 is set in a mold, and the polyethylene containing the cross-linking agent is extruded from the extruder in a molten state. After the extrusion is completed, the temperature of the heater provided in the mold is raised to a predetermined temperature, and the polyethylene containing the crosslinking agent is crosslinked to be molded. At this time, the air is discharged during the extrusion from the extruder, and the air is discharged from the groove of the air discharging portion 8 of the outer molding 7.
This is performed through a slit, a fiber structure, or the like.

[0019]

As described above, according to the present invention, since the air discharging portion is provided at the connecting portion between the external semiconductive layer of the connecting portion and the cable, the molten resin is injected from the extruder. The air in the outer semiconductive layer is discharged to the outside through the air discharge part. With this simple structure, cross-linking can be performed at the same time as extrusion, shortening the connection time,
The workability of extrusion molding can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a connection structure of a CV cable according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing an arrangement state of a connection portion external semiconductive layer and a cable.

3A and 3B are perspective views illustrating an example of the structure of an air discharge unit according to the present invention, wherein FIG. 3A is an example of a groove structure, FIG. 3B is an example of a sheet structure, FIG. D) is an example of a two-layer structure with high and low semiconductive layers.

FIG. 4 is an explanatory diagram illustrating an installation length of an air discharge unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1a, 1b Cable 2a, 2b Insulator 3a, 3b Conductor 4 Conductor sleeve 5 Inner semiconductive layer 6 Extrusion insulator 7 Connection part outer semiconductive layer 8 Air discharge part 8a Groove 8b Polyethylene sheet 8c Carbon fiber layer 9a Polyethylene sheet 9b Slit 10 High melting point semiconductive layer 11 Low melting point semiconductive layer

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masayuki Yamaguchi 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Power Systems Research Laboratory, Hitachi Cable, Ltd.

Claims (6)

[Claims] 1. A CV in which a molten resin is injected into an external semiconductive layer previously fitted to a connection portion of a CV cable by using an extruder and a mold, and is subjected to heating molding to form an insulation reinforcing portion.
In the connecting portion of the cable, the external semiconductive layer has an air discharging portion inside a portion fitted to the cable, wherein the outer semiconductive layer has an air discharging portion. 2. The CV cable connecting part structure according to claim 1, wherein said air discharging part is at least one groove formed on the inner surface of both ends of said outer semiconductive layer. 3. The CV according to claim 1, wherein the air discharge unit is an insulating sheet wound around or externally fitted to the cable and having slits provided at regular intervals in a circumferential direction. Cable connection structure. 4. The connection structure for a CV cable according to claim 1, wherein said air discharge portion is a carbon fiber provided on inner surfaces of both ends of said external semiconductive layer. 5. The air discharge section is a two-layer structure of a high melting point semiconductive layer externally fitted to the cable and a low melting point semiconductive layer provided outside thereof. The connecting part structure for a CV cable according to claim 1, wherein the connecting part is provided integrally at both ends. 6. The connection structure for a CV cable according to claim 2, wherein the air discharge portion has a length overlapping the cable of 50 mm or more and 200 mm or less.