JPS60218714A - Method of producing rubber, plastic wire and 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] <Industrial Application Field> The present invention relates to a method for manufacturing a rubber or plastic electric wire couple that reduces shrinkage in the longitudinal direction of the insulator and improves dimensional stability. It is something.

<Background technology and its problems> Rubber and plastic electric wires - The fact that the cable has little shrinkage in the longitudinal direction of the insulator and good dimensional stability is that
P1 located at the connection or terminal part of electric wires/cables, where the initial state of construction is maintained and the insulation has shifted over time.
It has the advantage of not causing peeling or staining.

However, the dimensional stability of rubber, plastic cables manufactured by conventional conventional methods has generally been poor.

Therefore, the present inventor conducted various studies regarding the causes of shrinkage in the length direction of the insulator in conventional electric wires and cables.

First of all, conventional electric wires and cables are 7i outside the conductor! After coating 13 with an insulating layer of rubber or plastic by extrusion, it is usually manufactured by heating and crosslinking, and then cooling it, but in this crosslinking process, the temperature of the electric wire cable reaches 150 to 350°C, and after this, Cooled as above.

Tomohiro explains that in this cooling process, the temperature of the insulating layer of the wire/cable decreases from the outer layer side, so a temperature difference occurs between the inner layer side and the outer layer side of the insulating layer, and at a certain temperature It was confirmed that a distribution occurred.

This is schematically shown in FIG. 1.

The outer circumference of the conductor 1 is coated with S? and cool it down
The temperature distribution at each elapsed time after entering the temperature range is represented by straight lines and curves of t/ and -t/.

That is, immediately before entering the cooling process after heating crosslinking, the temperature of the outer layer of the insulator layer 2 is about the same as the crosslinking temperature a, but it is finally cooled to the same temperature l as the water temperature. At this time, when looking at the changes in the lines l'1 to l'4, there is a tendency that the outer side of the insulating layer 2 is cooled earlier than the inner layer side. This means that the outer periphery of the insulating layer 2 begins to solidify first, so stress is generated inside the insulating layer 2, and after the product breaks, residual stress is built up in the cable. It becomes Takyō＼.

When such wires and cables are used, the built-in residual stress is released due to the temperature rise during energization. Therefore, the insulator layer contracts in the length direction.

<Object of the Invention> The present invention has been made in view of the shrinkage phenomenon of insulators according to the prior art. That is, according to the purpose of the present invention, ζ is achieved by subjecting an insulator to an unprecedented special heat treatment after thermal crosslinking and before entering a cooling process by a conventional method, so that no residual stress is built up in the insulator layer. An attempt is made to provide a method for manufacturing nine electric wires/couples that eliminates shrinkage of the insulator in the longitudinal direction.

′<Summary of the Invention> To summarize, the present invention involves extruding an insulator around the outer periphery of a conductor, cross-linking it by heating, and then expanding the insulator layer in the radial direction (thickness direction) to adjust the temperature of the conductor side and the outer layer. In contrast, we applied thermogeography with a concave temperature distribution in which the temperature in the central part of the inner layer is low, and
After that, it is cooled by a conventional method.

A concrete example of this AJ7 is as shown in FIG. 2C. That is, in the insulating layer 2 covering the outer periphery of the conductor 1, the concave temperature distribution is represented by a curve, t, I/c. A heat treatment having this temperature distribution can be obtained, for example, by heating crosslinking, cooling for a short time, harvesting, and then heating for a short time. Due to this special heat treatment, the insulator, once cooled from the outer layer, is softened by collar heating, so that the stress that was intended to be built into the insulator layer 2 is released and no longer remains. Therefore, the number of wires can be reduced to 0, and the shrinkage in the length direction of the insulating layer 2 is extremely small.

At this time, in order to smoothly soften the outer layer of the insulator layer 2, it is preferable that the temperature of the conductor side and the outer layer be equal to or higher than the melting point of the insulator in the concave temperature distribution.

In addition, the straight tube in Figure 2 is a curve l! ~i6, i
l is the temperature distribution after thermal crosslinking, 12 is the temperature distribution after short-time cooling, is the concave temperature distribution formed by collar heating as described above, and iζ to i6 are after normal cooling. These are the respective temperature distributions.

<Example> Example Summer 3251o12 annealed copper stranded wire conductor with an inner semiconducting layer, a polyethylene insulating layer, and an outer semiconducting layer -4111%12,
Coated by extrusion to a thickness of 0.5 mm, using a continuous vulcanizer at a pressure of 6 ”g.
/an2, - Heat crosslinking at 200°C for 30 minutes.

It is then cooled at 25° C. for 10 minutes and then heated again at 200° C. for 110 minutes. After that, cool it using the normal cooling method and make the cable.

Example 1 100 2 Annealed copper stranded wire conductor with 1 m each of an inner semiconducting layer, a polyethylene insulating layer, and an outer semiconducting layer.

Extrusion coating was carried out to a thickness of 12 m and 0.5 m, and heat crosslinked in a continuous vulcanizer at a pressure of 6 K g/cm at 200° C. for 20 minutes. Then, cool at 25°C for 7 minutes,
Heat at 200°C for minutes. After this, the cable was cooled using the usual cooling method.

Example ■ A 100 wx” annealed copper stranded wire conductor with an inner semiconducting layer, a polyethylene insulating layer, and an outer semiconducting layer each having a thickness of 1B18, 0.5
Extrusion coated to B thickness, continuous vulcanizer, pressure 6Kg/an2
, 200°C for 20 minutes. It is then cooled at 25° C. for 7 minutes and then heated again at 200° C. for 7 minutes. After this, the cable was made by cooling it using a normal cooling method.

Comparative example ■ 325 m2 annealed copper stranded wire conductor with an inner semiconducting layer, a polyethylene insulating layer, and an outer semiconducting layer of 1 mm each, 12IE 1%
Extrusion coated to a thickness of 0.5 sm, continuous vulcanizer, pressure 6K
g/cm2s Heat crosslinking at 200°C for 40 minutes.

The cable was then cooled using a conventional cooling method.

Comparative example ■ 100m” annealed copper stranded wire conductor with inner semiconducting layer, polyethylene insulating layer, and outer semiconducting layer each 1 m512m%0.5
Extrusion coated to a thickness of ℃, and applied with a continuous vulcanizer to a voltage of θKg.
Heat crosslinking at 200°C for 40 minutes. The cable was then cooled (using a conventional cooling method) to form a cable.

In each of the above Examples and Comparative Examples, a 530 cm cable sample was taken and left at 180°C for 24 hours.
The dimensional changes of the extruded coating layer were measured and the results shown in Table 1 below were obtained.

Table 1 Shrinkage Properties From Table 1, it can be seen that the shrinkage rate of the extruded coating layer made of the insulating layer of the couple produced by the method of the present invention is significantly higher than that of the comparative cable made by the conventional method. I understand that it is small.

In the above embodiment, semiconducting layers are placed inside and outside the insulating layer.
Although the above-mentioned explanation was about a multi-layer coating layer, the present invention makes it possible to obtain similar results even when only the insulating layer or one of the semiconducting layers is omitted.

The same applies to electric wires.

<Effects of the Invention> According to the present invention, as is clear from the above description, in the method for manufacturing rubber or plastic electric wires/cables, an insulator is extruded and coated around the outer periphery of a conductor, and after cross-linking by heating, the radius of the insulator layer is Heat treatment is performed to create a concave temperature distribution in which the temperature in the center of the inner layer is lower than that of the conductor side and the outer layer, and then cooled by a conventional method. The material does not remain inside the material, and there is almost no shrinkage in the length direction even if the temperature rises due to energization during use. However, the dimensional stability is good, and the adhesion of the interface between the sealing mold resin and the wire/cable insulator may decrease at the connection or termination portion of the wire/cable. No peeling occurs at the interface, and the effect of significantly improving breakdown voltage can be obtained.

[Brief explanation of the drawing]

1st r1! ! J is an explanatory diagram schematically showing the temperature distribution over time in the insulating layer of an electric wire-cable according to the conventional method, and FIG. FIG. 2 is an explanatory diagram schematically showing temperature distribution. In the diagram, 1...conductor, 2...Φ insulator layer, '1~i6 fist...
Each straight line and curve of the temperature distribution.

Claims (2)

[Claims] (1) In a method of manufacturing a rubber or plastic electric wire-cable, in which a rubber or plastic insulating layer is extruded and coated on the outer periphery of a conductor, the disconnected wire member (M) is heated and crosslinked, and then cooled. , a rubber or plastic electric wire/couple characterized by applying heat treatment in the radial direction of the insulating layer and having a concave temperature distribution where the temperature in the center of the inner layer is lower than that of the conductor side and the outer layer. Production method. (2) In the concave temperature distribution, the temperature of the conductor side and the outer layer is higher than the melting point of the insulator □ The method for manufacturing a rubber or plastic electric wire snout cable according to claim 1 .