JPH088021B2 - Non-destructive inspection method for electric wires and cables - Google Patents

Description

TECHNICAL FIELD The present invention relates to a non-destructive inspection method for electric wires / cables for non-destructively inspecting foreign substances in an insulator while manufacturing electric wires / cables. .

<Prior art> Conventionally, in the case of electric wires / cables such as CV cables,
As quality control, we are inspecting for concentricity ratio, outer diameter abnormality, abnormality of external damage, etc., as well as foreign matter in the insulator, voids (air bubbles), scratches, etc. It is not performed in the middle of the process, but in general, the finished product is subjected to a separate inspection process.

As the method, for example, a sample of the product is taken out and the insulator characteristic is checked by a withstand voltage test or a corona discharge test.

<Problems to be Solved by the Invention> However, the inspection method as described above has an insufficient aspect.

This is because the presence of specific minute foreign matter, voids, scratches, etc. in the insulator is not known in the dielectric strength test or corona discharge test, and is often overlooked.

However, in the case of CV cables, etc., once they are laid, they can be used for as long as 30 years, so minute foreign matter, voids, scratches, etc. may cause electric discharge due to long-term charging. There was sufficient concern, and in the worst case, there was a risk of dielectric breakdown.

The present invention has been made in view of such conventional problems, and a feature thereof is that a CT device (CT scanner) is provided during a process after covering an insulator in a wire / cable manufacturing device. It is intended to provide a non-destructive inspection method for electric wires / cables, which is installed while manufacturing electric wires / cables and at the same time detecting foreign matter, voids, and scratches in the insulator.

<Means for Solving Problems and Actions Thereof> To more specifically show the present invention, the present invention provides a method for manufacturing an electric wire / cable in which a periphery of a traveling electric wire / cable after being covered with an insulator is provided. A closed radiation shielded room, and a radiation irradiator installed in the shielded room, which face each other orthogonally to the axial direction of the electric wire / cable and rotate while moving in the traveling direction of the electric wire / cable. This is a non-destructive inspection method for electric wires / cables in which a CT device equipped with a radiation detector is installed to simultaneously detect foreign substances in the insulator while manufacturing the electric wires / cables.

That is, according to the present invention, foreign matter in the insulator, voids, scratches, etc. directly and over the entire length of the electric wire / cable,
Can be inspected.

<Example> FIG. 1 shows an example of an electric wire / cable manufacturing system for carrying out the method of the present invention.

In this manufacturing apparatus system, the conductor 2 such as a stranded wire sent from the conductor sending machine 1 passes through the running loop and is connected to the two inner layer extruders 3 and the outer layer extruder 4 parts, for example, with a crosslinking agent. The polyethylene insulator 5 is covered, and thereafter, it is guided to a bridge cylinder 6, heat-crosslinked, further guided to a cooling cylinder 7, cooled, and passed through a tension caterpillar 8.
The product is wound up by the winding machine 9 as a product.

The heating in the bridging cylinder 6 is performed by the electric heating heater 10 for bridging and the high temperature pump 11 for heat circulation, and the cooling in the cooling cylinder 7 is performed by the heat exchanger 12 and the low temperature pump 13 for heat exchange. .

In such an electric wire / cable manufacturing apparatus system, in the method of the present invention, the CT apparatus A for inspecting an insulator is provided at three positions (between the cooling cylinder outlet and the tension caterpillar, as shown in the figure).
Tension caterpillar-winder, mid-cooling tube,)). At that time
The number of CT devices A to be installed and the combination of sections may be appropriately selected.

FIG. 2 shows an example of a specific installation method of the CT device A.

That is, in this case, the radiation shielding chamber 21 made of lead or the like is sealed around the running cable C in which the insulator 5 is destroyed.
And a radiation irradiating section 22 for X-rays and the like, which face each other in the orthogonal direction to the axial direction of the cable C and rotate while moving in the traveling direction of the cable C, and the insulator 5. A radiation detector 23 for detecting the transmitted radiation therein is arranged.

Here, the moving speeds of the pair of the radiation irradiating section 22 and the radiation detecting section 23 are set to be the same as the traveling speed of the cable C, and when the cable C is rotated 360 °, the cable insulator 5
Try to orbit the same part of. Of course, it is set to return to the original position after one 360 ° rotation. The pair of the radiation irradiating unit 22 and the radiation detecting unit 23 are schematically shown as one set in the same figure, but in reality, as a set of many pairs, the detection time can be shortened. It should be set to.

With this configuration, the tomographic cross-section signal (information) of the insulator 5 can be collected over the entire length of the traveling cable C (to be precise, intermittently from the moving stroke of the radiation irradiation unit 22 and the radiation detection unit 23). It is possible to directly detect the presence of foreign matter, voids, scratches and the like in the insulator 5 by appropriately processing this signal. For example, it can be visually observed by CRT or the like. Further, by the computer processing, when a foreign substance, a void, a scratch or the like is detected, an alarm signal can be generated and the manufacturing apparatus can be automatically stopped. That is, it is possible to promptly deal with the occurrence of a cable defect due to the presence of foreign matter, voids, scratches, and the like.

FIG. 3 shows another example of the installation method of the CT apparatus A.

In this case, since two stations are installed, the tomographic cross-section signal at the same location of the cable C is sampled twice, or the next portion left after being detected in the first station is detected in the second station. It is possible. In these two collections,
The detection accuracy can be improved. Moreover, if different detection areas are assigned to the respective stations, the detection area can be expanded and a more complete cable full length inspection can be performed. Of course, if necessary, the number of stations may be three or more.

The effect of this multiple installation can be obtained in the same manner by the installation in a plurality of sections described above.

<Effects of the Invention> As is apparent from the above description, according to the non-destructive inspection method for electric wires / cables of the present invention, the CT apparatus is installed in the step after the insulation coating in the electric wire / cable manufacturing apparatus. Therefore, while manufacturing electric wires / cables, it is possible to detect foreign matter, voids, scratches, etc. in the insulator at the same time.
The following advantages are obtained.

There is no need to provide a special inspection process to check the insulation characteristics as in the past.

Since it is possible to check the entire length of the cable instead of the conventional sample test, the reliability of the product can be significantly improved.

In the case of a defective insulator by a conventional withstand voltage test or corona discharge test, while the specific cause is unknown, since foreign particles, voids, and specific properties such as scratches are possible by visual inspection, etc.,
It should be possible to easily investigate the cause of defects in the manufacturing process and take various measures.

When it is detected that no insulator is needed due to the generation of foreign matter, voids, scratches, etc., it is possible to immediately stop the manufacturing process, etc., so that wasteful production after occurrence of defects can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of an electric wire / cable manufacturing apparatus system for carrying out the method of the present invention, and FIGS. 2 to 3 are schematic explanatory views showing a method of installing a CT apparatus. . In the figure, A ... CT device, C ... Cable, 21 ... Radiation shielded room, 22 ... Radiation irradiation part, 23 ... Radiation detection part,

Claims (1)

[Claims] 1. In a wire / cable manufacturing apparatus, a radiation shielded room that is sealed around a traveling wire / cable after being covered with an insulator, and a radiation shielded room that is incorporated in the shielded room and is arranged in the axial direction of the wire / cable. , A CT device equipped with a radiation irradiation unit and a radiation detection unit that face each other orthogonally and rotate while moving in the traveling direction of the electric wire / cable is installed.
A non-destructive inspection method for electric wires and cables, which detects foreign substances and the like in the insulator at the same time while manufacturing the cable.