JPH01155250A - Nondestructive inspection for wire and cable - Google Patents

Abstract

PURPOSE:To increase the reliability of a product without providing a specific inspection process and to prevent a wasteful production after the occurrence of a fault, by a method wherein an extraneous substance or the like in an insulator is detected simultaneously with manufacture of a wire or a cable by using a CT device. CONSTITUTION:A conductor 2 from a conductor feeder 1 passes along a running loop and is coated with a polyethylene insulator 5 in sections of an inner-layer extruder 3 and an outer-layer extruder 4. Then, it passes through a heating crosslinking tube 6, a cooling tube 7 and a caterpillar 8 and is wound up as a product by a winder 9. In this case, a radiation applying element 22 which rotates while moving in the direction of running of a cable C coated with the insulator 5 and running, and a radiation detecting element 23 detecting a radiation transmitted through the insulator 5, are provided. By this constitution, a radiographic section signal of the insulator 5 can be taken through the full length of the running cable C, and the presence of an extraneous substance in the insulator 5 can be detected directly by processing this signal.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for non-destructively inspecting electric wires and cables for non-destructively inspecting foreign substances in insulators while manufacturing electric wires and cables. .

<Conventional technology> Conventionally, in the case of electric wires and cables, such as Cv cables,
For quality control, we inspect for concentricity, outer diameter abnormalities, external damage abnormalities, etc., as well as foreign objects, voids (bubbles), scratches, etc. in the insulators. This is not done midway through the process, but is generally done in a separate inspection process for the finished product.

One way to do this is, for example, by taking a sample of the product and checking its insulator properties through a withstand voltage test, a corona discharge test, and the like.

<Problems to be Solved by the Invention> However, the above-mentioned inspection methods have some insufficiencies.

This is because the above-mentioned withstand voltage test, corona discharge test, etc. do not detect the presence of specific minute foreign objects, voids, scratches, etc. in the insulator, and they are often overlooked.

However, in the case of Cv cables, etc., once they are installed, they can be used for about 30 years, so minute foreign objects, voids, scratches, etc. can cause discharge due to long-term energization. There was considerable concern that this could lead to dielectric breakdown in the worst case.

The present invention has been made in view of such conventional problems, and its characteristic point is that a CT device (CT scanner) The purpose of the present invention is to provide a method for non-destructive testing of electric wires and cables, which detects foreign objects, voids, flaws, etc. in the insulation at the same time as manufacturing electric wires and cables.

To explain the present invention more specifically, the present invention provides an electric wire/cable manufacturing apparatus in which the surroundings of running electric wires/cables are coated with an insulator. , a sealed radiation shielding chamber, and a radiation irradiation unit built into the shielding chamber, facing each other perpendicularly to the axial direction of the electric wires/cables, and rotating while moving in the running direction of the electric wires/cables. The present invention provides a non-destructive inspection method for electric wires and cables, in which a CT device equipped with a radiation detector and a radiation detector is installed to simultaneously detect foreign objects in an insulator while manufacturing electric wires and cables.

In other words, according to the present invention, foreign matter in the insulator, voids,
It is possible to inspect for flaws directly and over the entire length of electric wires and cables.

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

In this manufacturing equipment system, a conductor 2 such as a stranded wire sent out from a conductor feeder 1 passes through a running loop and is passed through two sets of an inner layer extruder 3 and an outer layer extruder 4. A polyethylene insulator 5 is coated, then guided to a cross-linking tube 6, cross-linked by heating, further guided to a cooling tube 7, cooled, passed through a tension caterpillar 8, and wound by a winder 9 as a product. It is wound up.

Heating in the bridging cylinder 6 is performed by a bridging electric heater 10 and a high temperature pump 11 for heat circulation, and cooling in the cooling cylinder 7 is performed by a heat exchanger 12 and a low temperature pump 13 for heat exchange.
It will be held in

In such an electric wire/cable manufacturing equipment system, in the method of the present invention, the CT device A for insulator inspection is installed at the three locations shown in the figure (■ between the cooling extraction hole and the tensigon caterpillar;
It shall be installed at at least one location between the tension caterpillar and the winding machine (in the middle of the cooling cylinder). The number of units installed in the CT apparatus and the combination of sections may be selected as appropriate.

FIG. 2 shows an example of a specific method of installing the CT equipment WA.

In other words, in this case, a radiation shielding chamber 21 made of lead or the like is sealed around the running cable C coated with the insulator 5.
A radiation irradiation unit 22 such as an X-ray radiation irradiation unit 22 is provided therein, which faces each other perpendicularly to the axial direction of the cable C and rotates while moving in the running direction of the cable C.
A radiation detection section 23 for detecting radiation transmitted through the insulator 5 is arranged.

Here, the moving speed of the pair of radiation irradiation unit 22 and radiation detection unit 23 is set to be the same as the running speed of cable C, and when the cable C is rotated for 360 m, the same part of the cable insulator 5 is orbited. do it like this. Of course, 360°
Set it so that it returns to its original position after completing one rotation. Note that this pair of radiation irradiation section 22 and radiation detection section 2
3 schematically shows the case of - pairs in the same figure, but in reality, it is preferable to shorten the detection time by using a set of many pairs.

With this configuration, over the entire length of the running cable C (
To be more precise, it is possible to collect tomographic cross-sectional signals (information) of the insulator 5 intermittently from the movement strokes of the radiation irradiation unit 22 and the radiation detection unit 23, and by appropriately processing this signal, the The presence of foreign objects, voids, scratches, etc. can be directly detected.

For example, it can be visually observed using a CRT or the like.

Further, through computer processing, it is also possible to generate an alarm signal and automatically stop the manufacturing equipment when foreign objects, voids, scratches, etc. are detected. In other words, it is possible to quickly deal with the occurrence of cable defects due to the presence of foreign objects, voids, scratches, and the like.

FIG. 3 shows another example of the method of installing the above-mentioned CT apparatus.

In this case, since two stations are installed, the tomographic cross-section signal at the same location of cable C may be collected twice, or the second station may detect the next part that was left undetected by the first station. That's possible. This two-time sampling can improve detection accuracy. Furthermore, by having multiple cables share different detection areas, the detection area can be expanded and a more complete cable length inspection can be performed. Of course, if necessary, it is also possible to use three or more series.

The effect of this multiple installation can be obtained in the same way by installing in multiple sections as described above.

<Effects of the Invention> As is clear from the above explanation, according to the method for non-destructive testing of electric wires and cables of the present invention, a CT device can be installed during the process after insulation coating in electric wire and cable manufacturing equipment. Therefore, it is possible to detect foreign objects, voids, scratches, etc. in the insulation at the same time as manufacturing electric wires and cables.
The following advantages can be obtained.

■There is no need to set up a special inspection process to check insulator properties as in the past.

■Since the entire length of the cable can be checked instead of the conventional sample test, the reliability of the product can be greatly improved.

■In the case of insulator failures caused by conventional withstand voltage tests and corona discharge tests, the specific cause is unknown; however, it is possible to specifically identify foreign objects, voids, scratches, etc. by visual inspection.
Easily investigate the cause of defects in the manufacturing process and take various countermeasures.

■If an unnecessary insulator is detected due to the occurrence of foreign objects, voids, scratches, etc., the manufacturing process can be stopped immediately, so wasteful production after defects can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing an example of a manufacturing equipment system for electric wires and cables for carrying out the method of the present invention, and Figs. 2 and 3 are schematic explanatory diagrams showing how to install a CT device. It is. In the figure, A...CT device, C...cable, 21...radiation shielding room, 22...radiation irradiation section, 23...radiation detection section, patent applicant Fujikura Electric Cable Co., Ltd. Figure 2 Figure 3

Claims (1)

[Claims] In electric wire/cable manufacturing equipment, there is a sealed radiation shielding chamber around the running electric wire/cable after it has been coated with insulation, and a radiation shielding chamber built into the shielding chamber and arranged perpendicular to each other with respect to the axial direction of the electric wire/cable. A CT device equipped with a radiation irradiation unit and a radiation detection unit that face each other and rotate while moving in the running direction of the wires/cables is installed to simultaneously detect foreign objects in the insulation while manufacturing the wires/cables. A method for non-destructive testing of electric wires and cables.