JPH0328126B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing insulated connections for rubber-plastic power cables.

[Conventional technology]

When three-phase power cables are used to form a three-phase power transmission line, a cross bond is used to ground the cable to prevent induced circulating current from flowing in the outer conductive layer (or outer shielding layer) of the power cable. It is well known that, for this reason, when connecting each power cable, a so-called insulated connection part is used in which the outer conductive layer is cut off in the middle.

FIG. 2 shows an example of a conventional insulated connection part for a rubber/plastic power cable, in which an external conductive layer 5 is provided on the periphery of a rubber/plastic insulating coating layer 2 at the connection part of both cables 1, 1'. , 5' are cut off in the middle. On the other hand, for the edge cutting, a pre-formed edge cutting unit 4 is used in consideration of stabilizing the electrical characteristics of the part and improving workability.

[Problem that the invention seeks to solve]

By the way, the edge cutting unit 4 includes an electrode ring-shaped element 41 which is a conductive rubber/plastic molded body and has one side edge formed with a predetermined roundness, and the ring-shaped element 4
An insulating rubber/plastic molded body 42 provided on the periphery of the base plate 1 is used. When the edge cutting unit 4 is made of an electrode ring-shaped element 41 and an insulating rubber/plastic molded body 42 that are uncrosslinked (or unvulcanized), the insulating properties will be reduced during the subsequent heating and pressure treatment. Although the rubber/plastic molded body 42 is successfully fused to the insulating coating layer 2, the ring-shaped electrode element 41
Thermal deformation was severe and the electrical properties were likely to be insufficient. On the other hand, the ring-shaped element 4 for the electrode
In consideration of the prevention of thermal deformation of 1, the edge cutting unit 4 is made of a ring-shaped electrode element 41 and an insulating rubber.
The plastic molded body 42 is crosslinked (or vulcanized)
In the case of using the insulating rubber, although thermal deformation of the electrode right ring element 41 is eliminated,
The plastic molded body 42 and the insulating coating layer 2 were not properly bonded (fused together), and voids were created between them, resulting in insufficient electrical properties.

As described above, it cannot be said that the electrical characteristics of this type of insulated connection portion manufactured by conventional means are necessarily sufficient, and improvement thereof has been desired.

[Means for solving problems]

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the drawbacks of the prior art and to provide a method useful for producing electrically superior insulated connections for rubber-plastic power cables.

That is, the gist of the present invention is a ring-shaped element for an electrode, which is a crosslinked (or vulcanized) conductive rubber/plastic molded body, and one side edge of which is molded with a predetermined roundness. , an insulating rubber layer provided on the periphery of the ring-shaped electrode element so as to cover at least one side edge of the element;
An edge cutting unit made of a plastic molded body is inserted over the circumference of the insulating coating layer of the cable connection part, and then these are heated to fuse and integrate both the edge cutting unit and the insulating coating layer. In this case, the edge cutting unit is made of a highly cross-linked (or highly vulcanized) material in the area where it contacts the electrode ring element of the insulating rubber/plastic molded body, and a low cross-linked (or highly vulcanized) material in the area where it contacts the insulating coating layer. The point is that it uses a material made of a material with a low degree of vulcanization.

In the above, there is a specific example in which the insulating rubber/plastic molded body has a high degree of crosslinking (or high vulcanization) in the vicinity of the electrode ring-shaped element, and a low degree of crosslinking (or low vulcanization) in the vicinity of the insulating coating layer. As a means, for example, an uncrosslinked (or unvulcanized) ring-shaped element for the electrode containing a prepared cross-linking agent (or cross-linking agent) and a ring-shaped element for the electrode of an edge cutting unit made of an insulating rubber/plastic molded body are used. A specified metal electrode is inserted into the element, and in this state it is placed in an induction coil to cause the metal electrode to generate heat, thereby heating the edge cutting unit from the electrode ring element side and at the same time insulating it. There is a method in which the temperature is appropriately controlled on the outside of the rubber/plastic molded body.

〔Example〕

Next, an embodiment of the present invention will be explained with reference to FIGS. 1 and 2. A cross-linked polyethylene insulated power cable (CV cable) to be connected
1, 1', 10, and 10' are connected by a conductor connecting tube 101, and an insulating coating layer 2 is formed on the circumference thereof by wrapping a polyethylene tape containing a crosslinking agent or extruding a polyethylene compound containing a crosslinking agent. Thereafter, an edge cutting unit 400, which will be described later, is inserted over the circumference of the insulating coating layer 2.

Here, the edge cutting unit 400 is explained in detail. It is a crosslinked conductive polyethylene molded body, and is a ring-shaped element for an electrode in which one side edge 401 of itself is molded with a predetermined roundness. 40
2, and an insulating polyethylene molded body 403 provided on the circumference of the element 402 so as to cover the ring-shaped element 402, and the ring-shaped element 402 for electrode of the crosslinked insulating polyethylene molded body 403
A region 404 in contact with the insulating coating layer 2 is made of a material with a high degree of crosslinking (gel fraction 40% or more), and a region 405 in contact with the insulating coating layer 2 is made of a material with a low degree of crosslinking (gel fraction 0 to 20%). In addition, in the insulating polyethylene molded body 403, the ring-shaped electrode element 4
The degree of crosslinking is gradually changed from the side in contact with 02 to the side in contact with insulating coating layer 2, and the degree of crosslinking is increased to 80% by heat during crosslinking treatment of insulating coating layer 2, which will be described later.
A crosslinking agent sufficient to obtain the above gel separation is mixed in advance into the whole.

Next, after wrapping the polyethylene tape 2' containing a crosslinking agent around the circumference of the insulating coating layer 2 until its outer diameter becomes the same as the outer diameter of the edge cutting unit 400, the end of the outer conductive layer 100 of one cable 1 is wrapped. Insulating polyethylene molded body 4 of the edge cutting unit 400 from above the circumference
A conductive polyethylene tape containing a crosslinking agent is wrapped around the circumference of 03 to form an external conductive layer 5,
A conductive polyethylene tape containing a crosslinking agent is wrapped around the end of the outer conductive layer 100' of the other cable 1' and around the end of the electrode ring element 402 of the insulating unit 400 to form the outer conductive layer. form 5'.

Thereafter, the whole is heated and pressurized to fuse and integrate the insulating coating layers 2, 2', the edge cutting unit 400, and the outer conductive layers 5, 5' and to crosslink them (gel fraction 80% or more). .

Next, the whole is cooled, and further the outer conductive layers 5, 5'
This work is completed by forming a metal shielding layer (not shown) on the circumference as necessary.

〔Effect of the invention〕

According to the manufacturing method of this embodiment carried out as described above, the edge cutting unit includes a ring-shaped electrode element 402 made of a cross-linked conductive polyethylene molded body, and a ring-shaped element 402 for covering the ring-shaped element 402. The insulating polyethylene molded body 403 is provided on the periphery of the element 402 in this manner, and the vicinity 404 of the insulating polyethylene molded body 403 in contact with the electrode ring-shaped element 402 is made of a material with a high degree of crosslinking. Since the area 405 in contact with the coating layer 2 is made of a material with a low degree of crosslinking, the electrode ring-shaped element 402 is In addition to preventing thermal deformation of
The welding of the insulating polyethylene molded body 3 to the insulating coating layer 2 can also be carried out very successfully, and therefore an insulated connection part for a crosslinked polyethylene power cable having excellent electrical properties can be produced very smoothly.

As described above, the present invention solves the above-mentioned conventional difficulties and provides a method for manufacturing an electrically superior insulated joint for rubber/plastic power cables, and its industrial value is extremely large. I can say it.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an edge cutting unit used in an embodiment of the method for manufacturing an insulated joint for a rubber/plastic power cable according to the present invention, and Fig. 2 is an explanatory diagram for manufacturing an insulated joint for this kind of rubber/plastic power cable. It is an explanatory diagram of a method. 1,1'...Cable, 10,10'...Conductor, 10
0,100'...Outer conductive layer of the cable, 101...
Conductor connection tube, 2, 2'...Insulating coating layer, 4,400
...Edge cutting unit, 41,402...Ring-shaped element for electrode, 42...Insulating rubber/plastic molded body,
403...Insulating polyethylene molded body, 5,5'...
Outer conductive layer of the connection.

Claims (1)

[Claims] 1. A ring-shaped element for an electrode, which is a molded body of cross-linked (or vulcanized) conductive rubber or plastic, with one side edge thereof having a predetermined roundness. , an edge cutting unit consisting of an insulating rubber/plastic molded body provided on the periphery of the ring-shaped electrode element so as to cover at least one side edge of the element is attached to the insulating coating of the cable connection part. When the edge cutting unit and the insulating coating layer are inserted over the circumference of the layer and further heated to fuse and integrate both the edge cutting unit and the insulating coating layer, a The area in contact with the ring-shaped element is made of a material with a high degree of crosslinking (or high vulcanization), and the area in contact with the insulating coating layer is made of a material with a degree of low crosslinking (or low vulcanization). A method of manufacturing an insulated joint for a rubber/plastic power cable. 2. The gel fraction of the insulating rubber/plastic molded body near the electrode ring element is 40% or more, and the gel fraction of the insulating rubber/plastic molded body near the insulating coating layer is 20% or less. A method of manufacturing an insulated connection for a rubber-plastic power cable according to claim 1, using a certain edge cutting unit.