JPS60160311A - Mold jointing process of power 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 [Technical Field] The present invention relates to an improvement in a mold joint construction method used for connecting rubber/plastic insulated electrical cables.

[Prior art]

Generally, when connecting a Cv cable or the like, a mold joint method is used in which the insulator of the connection part is molded in a mold. This construction method consists of the following steps. First, after connecting conductors, an internal semiconducting layer is formed around their outer peripheries. Next, a mold is placed to surround the conductor connection part and the insulating layer parts on both sides of the conductor connection part, and after injecting resin for forming the connection part insulator into the mold using an extruder, the resin is solidified and the mold is closed. remove. Next, a tape for an external semiconducting layer is wrapped around the outer periphery of the molded insulator thus produced, and finally the whole is pressurized and heated to crosslink the molded insulator.

Although the mold joint portion is formed as described above, the conventional method has the following problems. In other words, there may be a seam on the surface of the mold insulator that follows the seam of the mold, and if the outer semiconducting layer is coated and crosslinked as is, the outer semiconducting layer will dig into the seam. As a result, protrusions of the outer semiconducting layer are generated. This protrusion becomes a factor that significantly reduces the withstand voltage characteristics of the connection portion.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the problems of the prior art as described above, it is an object of the present invention to provide a mold joint construction method that does not generate protrusions on the external semiconducting layer. The mold joint construction method of the present invention is achieved by providing an uncrosslinked insulating thin layer on the outer periphery of a molded insulator that is formed so as to span the conductor connection part and the insulating layers on both sides thereof, and then applying an external semiconducting layer. It is characterized in that it is provided with a polyurethane resin, and then crosslinked.

〔Example〕

The drawings show a mold joint part in the process of being manufactured by the method of the present invention. An embodiment of the present invention will be described below with reference to this figure.

Reference numeral 1 indicates the conductor of the cable to be connected, 2.3.4 indicates the internal semiconducting layer and insulating layer formed in sequence on the outer periphery, respectively.
This is the outer semiconducting layer. For connection, first, the conductor 1 is compressed and connected using the sleeve 5, and an internal semiconductive layer 6 for the connection portion is provided on the outer periphery of the conductor 1. Next, a mold (not shown) is placed over the insulating layer 6.3, and after filling the molten resin and solidifying it, the mold is removed to form the mold insulator 7. do. Everything up to this point is the same as before. In this embodiment, an uncrosslinked insulating thin layer 8 is provided around the outer periphery of the molded insulator 7 using a crosslinking agent, and then an outer conductive layer 9 is provided, and then the whole is pressurized. If this is done, the uncrosslinked insulating thin layer 8 will be softened once during crosslinking, so if there is a seam in the molded insulator 7, it will sink into the seam and form a cushion. It plays the role of preventing the outer semiconducting layer 9 from digging into the seam portion. Therefore, according to this method, even if there is a seam in the molded insulator, the occurrence of protrusions on the outer semiconducting layer can be eliminated. In addition, in the conventional construction method, if the interface between the mold insulator 7 and the insulating layer 3 were to peel off at the slope rising edge A, the external semiconducting layer could sink into this area and form a protrusion. ,
If the uncrosslinked insulating thin layer 8 is provided as in this embodiment, this problem can also be solved.

The material of the uncrosslinked thin insulating layer 8 is preferably the same as that of the mold insulator 7. This uncrosslinked insulating thin layer 8
is integrated with the mold insulator 7 after crosslinking, and there is no clear interface as shown in the figure.

In the above embodiment, the molded insulator was formed by a so-called extrusion method in which molten resin was injected into the mold, but the present invention is not limited to this. For example, insulating tape is laminated around the conductor connection part. It is generally applicable to methods in which the insulator is solidified within the mold, such as a method in which the insulating material is solidified within the mold, such as a method in which the insulator is rolled up, a mold is placed on the outer periphery, and the laminated tape is melted and integrated. There is no particular limitation, and in addition to the tape wrapping method, a heat shrink sleeve method can also be used.

〔Effect of the invention〕

As explained above, according to the present invention, an uncrosslinked insulating thin layer is provided around the outer periphery of the molded insulator, and then an outer semiconducting layer is provided. Since the seam is filled with the uncrosslinked insulating thin layer, no protrusion of the external semiconducting layer is generated, which has the advantage of greatly improving the reliability of the mold joint.

[Brief explanation of the drawing]

The drawings are half-cut cross-sectional views of the mold joint part in the process of manufacturing according to an embodiment of the construction method of the present invention.
... Connection sleeve, 6 ... Internal semiconducting layer, 7
. . . Molded insulator, 8 . . . Uncrosslinked insulating thin layer, 9 . . . External semiconducting layer.

Claims (1)

[Claims] The method is characterized in that an uncrosslinked insulating thin layer is provided on the outer periphery of a molded insulator formed so as to span the conductor connection portion and the insulating layers on both sides thereof, and then an outer semiconducting layer is provided, and then crosslinking is performed. Mold joint construction method for power cables.