JPH0322032B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of forming an insulated joint (IJ) of a rubber-plastic power cable, and more particularly to forming an edge cut portion.

[About insulated connections] An example is shown in FIG.

10 is a conductor connection part; 12 is a cable insulation layer; 14 is a cable outer semiconducting layer; 16 is a reinforcing insulating layer.

18 is an inner semiconductive layer of the edge cut portion provided directly above the reinforcing insulating layer 16; 20 is an edge cut insulating layer; 22 is an outer semiconductive layer of the edge cut portion provided on the edge cut portion insulating layer 20.

[Prior Art and Problems] The following methods are available for manufacturing the above-mentioned insulated connection portion by batch molding.

That is, (1) the reinforcing insulating layer 16 is made of uncrosslinked PE or the like, (2) the inner semiconducting layer 18 is made of a shrunk semiconductive heat shrink tube, and (3) the edge insulating layer 20 is made of uncrosslinked insulating tape, (4) the outer semiconducting layer 22 is made of a shrunken semiconductive heat shrink tube, and (5) the outer semiconducting layer 22 is molded all at once. .

・Problem: As shown in FIG.
(inner electrode part) falls in the direction of the conductor, reducing the electrical performance of the connection part.

[Prior art that solved the above problem] Semiconductive partially heat-shrinkable tube 18 described below
It has been proposed to construct the inner semiconducting layer 18 using 0 (see Japanese Patent Application No. 62-140418).

[1] About the semiconductive partially heat-shrinkable tube 180: As shown in FIG. 5, it consists of a thick part 26, a tapered part 28, and a thin part 30, and the whole is made of semiconductive polyolefin-based material such as cross-linked PE. Constructed from materials.

The thick portion 26 and the tapered portion 28 are made of heat shrink tubes.

In the thin portion 30, only the distal end portion 32 is made of a non-shrinkable (or hardly shrinkable) tube, and the portion 34 is heat-shrinkable.

Note that the entire thin portion 30 may be non-shrinkable (or hardly shrinkable).

The inner diameter a of the thin portion 30 is made equal to the outer diameter b (FIG. 3) of the reinforcing insulating layer 16.

[2] How to use the partially heat-shrinkable tube 180: (1) As shown in Figure 6a, the reinforcing insulating layer 16 (outer diameter b) is constructed by extrusion or tape wrapping.
The above-mentioned partial heat shrink tube 180 is attached on top.

After determining the position of the tip portion 32, that is, the inner electrode, the remaining portion is heated and shrunk.

(2) Next, as shown in Figure 6b, the edge insulating layer 2
0 with uncrosslinked PE tape, cover the outside with a semiconductive heat-shrinkable tube 220, and heat-shrink it to form the outer semiconductive layer 2.
2.

(3) Then, the reinforcing insulating layer 16, the inner semiconducting layer 18, the edge insulating layer 20, the outer semiconducting layer 2
2 is collectively molded, and the state shown in FIG. 3 is completed.

(4) During bulk molding, even if the reinforcing insulating layer 16 is softened by heating, the tip portion 32 of the semiconductive partially heat-shrinkable tube 180 does not shrink or hardly shrinks, so it does not shrink as shown in FIG. does not occur.

[Problem to be solved by the invention] As shown in FIG. 7, the outer diameter c of the cable sheath 15
may be larger than the outer diameter b of the reinforcing insulating layer 16.

Configuring the reinforcing insulating layer 16 (extrusion mold, etc.)
When doing so, the partial heat shrink tube 180 must be moved over the cable sheath 15.

However, as described above, the inner diameter a of 32 of the partially heat-shrinkable tube 180 is made equal to the outer diameter b of the reinforcing insulating layer 16 (smaller than the outer diameter c of the cable sheath 15).

Therefore, it cannot be moved onto the cable sheath 15.

[Object of the Invention] The inner semiconductive layer 18 of the edge cut portion is constructed using a heat-shrinkable tube, but as shown in FIG. without falling in the direction of the conductor, and
As mentioned above, the outer diameter c of the cable sheath 15 is
The present invention is made applicable to cases where the outer diameter b of the reinforcing insulating layer 16 is larger than that of the reinforcing insulating layer 16.

[Means for Solving the Problems] As shown in Figures 1a to 2b, (1) The distal end portion 42 and the main body 40, which are made separately in advance, are fused together to form an edge cut portion. (2) The tip portion 42 is molded with non-stretched semiconductive polyolefin, and the inner diameter is the same as that of the reinforcing insulating layer 1.
It is characterized by being a ring-shaped ring having an outer diameter equal to the outer diameter of No. 6 with an expanded diameter.

[Explanation] [1] Regarding IJ contraction tube 182: This is shown in Figure 1a.

It consists entirely of semi-conductive heat shrink tubing.

The inner diameter d of the tip 42 and the inner diameter e of the main body 40
are both larger than the outer diameter c of the cable sheath 15.

[2] How to make the IJ shrink tube 182: (1) The main body 40 is made by a known method using, for example, a stretched semiconductive polyolefin tape (FIG. 1b).

(2) The tip portion 42 is made by molding non-stretched semiconductive polyolefin separately from the main body 40 and is machined so that the inner diameter matches the outer diameter b of the reinforcing insulating layer 16.
(first
b).

(3) As shown in FIG. 1c, using a mandrel 44, the main body 40 and the distal end portion 42 are mold-fused and integrated.

Small diameter portion 4 of the mandrel 44 used at this time
The outer diameter of 6 is equal to the inner diameter of the tip 42. However, the inner diameter of the large diameter portion 48 is
It is sufficient that the diameter is larger than the outer diameter c of No.5.

(4) As shown in FIG. 1d, the diameter of the distal end portion 42 is expanded by a known method to make its inner diameter d larger than the outer diameter c of the cable sheath 15.

In the manner described above, the IJ contraction tube 182 shown in FIG. 1a is made.

[3] Formation of the inner semiconductive layer 18: (1) As mentioned above, since the inner diameter of the IJ contraction tube 182 is larger than the outer diameter c of the cable sheath 15, when forming the reinforcing insulating layer 16, It can be moved.

After forming the reinforcing insulating layer 16, the IJ shrink tube 182 is moved onto the reinforcing insulating layer 16, as shown in FIG. 2a.

(2) Heat and shrink the entire IJ shrink tube 182 (Figure 2b).

At that time, the tip portion 42 also has the reinforcing insulating layer 16
It contracts until it comes into close contact with the .

(3) After that, as in the conventional case, the edge cutting portion insulating layer 20 and the outer semiconducting layer 22 are formed and molded all at once.

At that time, the remaining shrinkage rate of the tip portion 42 is 0%.
(does not shrink further), so it does not fall into the reinforcing insulating layer 16.

[Effects of the invention] (1) The heat-shrinkable tube constituting the inner semiconductive layer of the edge cut portion is made by fusing the tip portion, which was made separately, and the main body, which is the other portion, into one piece. The tip part is made by molding unstretched semiconductive polyolefin into a ring shape whose inner diameter is equal to the outer diameter of the reinforcing insulating layer, and the diameter of the tip part is expanded by heating. Even though it is in a state where it can deform inward (in the direction of decreasing the inner diameter), when it is heat-shrinked and brought into close contact with the reinforcing insulator, the remaining shrinkage rate becomes zero, and it will not shrink further. I can't.

Therefore, when the reinforcing insulator is molded together with the uncrosslinked reinforcing insulator, even if the reinforcing insulator becomes soft, there is no possibility that the reinforcing insulator will sink into the reinforcing insulator.

Therefore, a molded insulated connection portion with stable electrical characteristics can be formed.

(2) Even when the outer diameter of the cable sheath is larger than the outer diameter of the reinforcing insulator, the insulating connection part can be formed without problems by the batch molding method using a heat-shrinkable tube.

[Brief explanation of drawings]

1a to 2b relate to an embodiment of the present invention, FIG. 1a is an explanatory diagram of the IJ contraction tube 182 used, and FIGS. 1b to 1d sequentially show a method of manufacturing the IJ contraction tube 182. Explanatory diagram, Part 2a
Figures 2b and 2b are explanatory diagrams sequentially showing usage conditions of the IJ contraction tube 182, and Fig. 3 is a general explanatory diagram of the insulated connection part. FIG. 4 and the following are related to the prior art. FIG. 4 is an explanatory diagram of the problem, FIG. 5 is an explanatory diagram of the partially heat-shrinkable tube 180 used, and FIG.
Figures 6 and 6b are explanatory diagrams showing the process order of IJ formation using a partially heat-shrinkable tube 180, and Figure 7 is an explanatory diagram of conventional problems. 10: Conductor connection part, 12: Cable insulation layer, 1
4: Cable external semiconductive layer, 16: Reinforcement insulating layer,
18: Inner semiconducting layer of edge cutting part, 20: Insulating layer of edge cutting part, 22: Outer semiconducting layer of edge cutting part, 32:
Tip portion, 40: Main body, 42: Tip portion, 44: Mandrel, 46: Small diameter portion, 48: Large diameter portion, 18
0: Semi-conductive partial heat shrink tube, 182: IJ
Shrink tube, 220: semiconductive heat shrink tube.

Claims (1)

[Claims] 1. An inner semiconductive layer of the edge cut portion, an edge cut portion insulating layer, and an outer semiconductive layer of the edge cut portion are provided on an uncrosslinked reinforcing insulating layer, and are collectively molded to form an insulating connection portion. In the method for forming a power cable insulated connection part, the inner semiconducting layer of the edge cutting part is formed by shrinking a heat shrinkable tube, wherein the heat shrinking tube forming the inner semiconducting layer of the edge cutting part comprises: The distal end, which was made separately, and the main body, which constitutes the other parts, are fused and integrated, and the distal end is molded from unstretched semiconductive polyolefin, and the inner diameter is covered with a reinforcing insulating layer. A method for forming an insulated connection part of a power cable, which is a ring-shaped part with an expanded diameter equal to the outer diameter of the power cable.