JPH0843355A - Cable inspection device - Google Patents

Abstract

PURPOSE:To provide a cable inspecting device which senses whether the conductors of a cable are in the condition likely to sever through application of the principle of eddy-current flaw detecting inspection and which ensures the preventive maintenance by prevention of conductors from severance. CONSTITUTION:A cable inspection device is equipped with a core 2 having a diameter approx. equal to the diameter of each of the conductors 4 constituting a cable 6 and a coil 1 which is wound on the core 2. Current is fed to the coil 1 so that a magnetic flux is generated around the core 2, which is moved relatively as creeping on the surface of the cable 6, and the change in the eddy current Ic in each conductor 4 generated by the magnetic energization effect of the core 2 is sensed by the change in the voltage of the coil 1 associated with the change in the magnetic flux PSIc of the core 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable inspection device used for checking whether or not there is a defect in a cable formed by twisting a plurality of conducting wires together.

[0002]

2. Description of the Related Art When a plurality of wires are twisted together to check for defects such as disconnection or short-circuit of a conductor wire, conventionally, as described in Japanese Utility Model Laid-Open No. 60-27371, There is known a technique of detecting whether or not the conducting state is confirmed when a voltage is applied to both ends of the conducting wire.

[0003]

By the way, in the above-mentioned prior art, although a defect can be detected when the conductor wire forming the cable is completely broken, the conductor wire is in a state just before the break, for example, When the wire is twisted or in a semi-disconnected state, it cannot be detected, so that there is a problem that the disconnection of the conductive wire cannot be prevented in advance. That is, such a conventional technique is effective as a means for investigating the cause of an accident or failure involving a cable, but it is not possible to find out by regular inspection or the like whether or not the conductor of the cable is easily broken. Therefore, for preventive maintenance to prevent accidents and failures, it is necessary to have a technique that can reliably detect a defect (twist or half-break) just before the break of the cable conductor.

The present invention has been made in view of the above circumstances, and an object thereof is to detect whether or not a conductor wire forming a cable is easily broken and to prevent the conductor wire from breaking. It is to provide a cable inspection device capable of preventing preventive maintenance.

[0005]

In order to achieve the above-mentioned object, the present invention comprises a core around which a coil is wound, and in which the core is energized to generate a magnetic flux in the core, The cable is moved relatively along the surface of the cable, and the change in the eddy current generated in the portion of the conductor of the cable excited by the magnetic flux is detected from the change in the voltage of the coil. Further, it is more preferable that the diameter of the core is set to be substantially equal to the diameter of the conducting wire, or the diameter of the coil is set to be substantially equal to the diameter of the cable.

[0006]

By applying the principle of eddy current flaw detection, which detects the presence or absence of a defect in the conductor based on the change in the eddy current of the conductor arranged in the alternating magnetic field, the core around which the coil is wound is moved relative to the surface of the cable. By checking the coil voltage while moving the wire, it is possible to detect the twisted portion or the half-breakage portion of the conductor wire from the change of the eddy current of the conductor wire, and the breakage of the conductor wire can be prevented.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an operation explanatory view showing a first embodiment of a cable inspection apparatus according to the present invention. In this inspection apparatus, a coil 1 connected to an AC power source (not shown) is wound around a core 2. Then, the deviation that the voltage of the coil 1 deviates from the reference value can be detected by the detector 3. Further, reference numeral 4 in the drawing denotes a conductor wire, 5 denotes an insulator covering the conductor wire 4, and 6 denotes a cable formed by twisting a plurality of conductor wires 4 together.

When checking the presence or absence of a defect in the cable 6 by using the above-mentioned inspection device, the coil 1 is energized and the core 2 is turned on.
In the state in which the magnetic flux is generated, the core 2 is relatively moved along the surface of the cable 6 as shown by the arrow. At this time, an eddy current is generated in a portion of the conductor wire 4 of the cable 6 that is excited by the core 2, and this eddy current affects the magnetic flux of the core 2. That is, when the core 2 passes through the normal portion of the conductor 4, the eddy current Ia is present in this normal portion.
Occurs, and the magnetic flux of the core 2 becomes Ψa, but if there is a defective portion 7 in which a part of the conducting wire 4 is twisted, semi-broken, or broken, the eddy current Ia in the normal portion is present in this defective portion 7. Since an eddy current Ib different from that is generated, the magnetic flux of the core 2 changes to ψb when passing through the defect portion 7, and the voltage of the coil 1 also changes accordingly. Therefore, if the detector 3 detects the deviation of the coil voltage from the reference value, it is determined that the core 2 is passing the defective portion 7 of the cable 6 when the deviation is equal to or more than a predetermined value. Since the determination can be made, it is possible to easily detect a twisted portion or a semi-opened portion of the conductor wire 4 of the cable 6 which cannot be detected by the conventional continuity test.

As described above, according to this embodiment, the cable 6
Since it is possible to detect a defect (twist or half-breakage) immediately before the breakage of the conductor wire 4 that constitutes the cable 6, the breakage of each conductor wire 4 can be prevented in advance by performing a periodic inspection or the like, and the cable 6
Therefore, preventive maintenance can be achieved, so that an accident or a failure due to the disconnection of the conducting wire 4 can be avoided.

FIG. 2 is an operation explanatory view showing a second embodiment of the cable inspection apparatus according to the present invention, and the portions corresponding to those in FIG. 1 are designated by the same reference numerals.

The inspection apparatus shown in FIG. 2 differs from the above-mentioned embodiment in that the diameter of the core 2 is set to be substantially equal to the diameter of the conductor wire 4. By doing so, it is possible to intensively excite one conductor wire 4 with the magnetic flux of the core 2 generated by energizing the coil 1, so that the eddy current generated in this conductor wire 4 is Ic (normal When the magnetic flux of the core 2 is changed from Ψc (magnetic flux when passing through the normal part) to Ψd, Ψc becomes Ψ.
The magnetic flux change to d becomes large and the voltage of the coil 1 is greatly changed, so that the deviation of the coil voltage detected by the detector 3 shows a large value. Therefore, when the core 2 is relatively moved along the surface of the cable 6 as shown by the arrow, a significant change appears in the detector 3 when passing through the defective portion 7, and the defective portion The detection of 7 becomes extremely easy.

FIG. 3 is a characteristic diagram showing the correlation between the core diameter and the detection sensitivity of the cable inspection device according to the present invention. Specifically, a specific defective portion of the cable 6 is detected by various cores 2 having different diameters. It shows the deviation of the coil voltage obtained at the time. In the figure, the core diameter D1 is equal to the diameter of one conductor in the cable having the defective portion, and the coil voltage deviation V1 is the detection value obtained when a core having a diameter D1 is used. Shows.

As is clear from FIG. 3, the closer the core diameter of the inspection device is to the diameter of the conducting wire having the defective portion, the larger the deviation of the coil voltage corresponding to the defective portion, and the higher the detection sensitivity. Recognize.

FIG. 4 is an operation explanatory view showing a third embodiment of the cable inspection apparatus according to the present invention, which is an example in which the present invention is applied to the inspection of the tail cord of an elevator.
The same reference numerals are given to the portions corresponding to. The tail cord 8 shown in the figure is a wide band-shaped body in which a plurality of cables 6 formed by twisting a plurality of conducting wires 4 are arranged side by side and covered with a sheath 9.

The inspection apparatus shown in FIG. 4 is largely different from the first and second embodiments in that the diameter of the coil 1 is set to be substantially equal to the diameter of the cable 6. That is,
When the coil 1 is energized, the magnetic flux Ψ is generated in the core 2, but at the same time, the weak magnetic flux ψ is also generated from the coil 1 itself.
If the diameter D2 of the coil 1 is set to be substantially equal to the diameter of the cable 6, this magnetic flux ψ will excite the cable 6 without waste, and the detection sensitivity will increase. Further, in the present embodiment, the bottom surface of the coil 1 is arranged in the same plane as the bottom surface of the core 2, so that the core 2 is placed on the sheath 9 of the tail cord 8.
Since the inclination of the core 2 which is a concern when sliding the wire is prevented, the change of the eddy current due to the variation of the relative distance between the core 2 and the conductive wire 4 can be avoided, and the defective portion of the conductive wire 4 can be prevented. Only changes in eddy current that can be seen can be reliably detected.

FIG. 5 is a characteristic diagram showing the correlation between the coil diameter and the detection sensitivity of the cable inspection apparatus according to the present invention. Specifically, a specific defective portion of the cable 6 is detected by various coils 1 having different diameters. It shows the deviation of the coil voltage obtained at the time. In the figure, the coil diameter D2 is equal to the diameter of the cable having the defective portion, and the coil voltage deviation V2 indicates the detection value obtained when the coil having the diameter D2 is used.

As is clear from FIG. 5, the closer the coil diameter of the inspection device is to the diameter of the cable having the defective portion, the larger the deviation of the coil voltage corresponding to the defective portion, and the higher the detection sensitivity. Recognize.

FIG. 6 is a characteristic diagram showing the correlation between the frequency of the alternating current flowing in the coil of the cable inspection apparatus according to the present invention and the detection sensitivity. Specifically, the frequency is from 5 kHz to 3 kHz.
It shows the deviation of the coil voltage obtained when a specific defect of the tail code of the elevator is detected by setting it to a predetermined value between 00 kHz.

As is apparent from FIG. 6, if the frequency of the alternating current flowing through the coil is set to a predetermined value larger than 10 kHz, preferably 100 kHz or more, good detection sensitivity can be obtained. It is suitable for the defect inspection of the conducting wire.

[0021]

As described above, the cable inspection device according to the present invention applies the principle of the eddy current flaw detection, and moves the core wound with the coil relatively along the surface of the cable. Since the change of the eddy current of the conductor wire that composes is captured by the change of the coil voltage, if there is a defective portion such as a twist or a half disconnection that is easily broken, the defective portion can be detected. It is possible to prevent disconnection of the conductor wire and preventive maintenance of the cable can be achieved, and it is possible to avoid an accident or a failure due to the disconnection of the conductor wire of the cable.

[Brief description of drawings]

FIG. 1 is an operation explanatory diagram showing a first embodiment of a cable inspection device according to the present invention.

FIG. 2 is an operation explanatory diagram showing a second embodiment of the cable inspection device according to the present invention.

FIG. 3 is a characteristic diagram showing the correlation between the core diameter and the detection sensitivity of the cable inspection device according to the present invention.

FIG. 4 is an operation explanatory view showing the third embodiment of the cable inspection device according to the present invention.

FIG. 5 is a characteristic diagram showing the correlation between the coil diameter and the detection sensitivity of the cable inspection device according to the present invention.

FIG. 6 is a characteristic diagram showing a correlation between a frequency of an alternating current flowing through a coil of the cable inspection device according to the present invention and detection sensitivity.

[Explanation of symbols]

 1 Coil 2 Core 3 Detector 4 Conductor 6 Cable 7 Defect 8 Tail code Ia to Id Eddy current Ψa to Ψd, Ψ, ψ Magnetic flux

Claims (5)

[Claims] 1. A cable inspection device for detecting the presence or absence of defects in a conductor wire of a cable formed by twisting a plurality of conductor wires, comprising: a core around which a coil is wound, and the coil is energized to generate a magnetic flux in the core. In the generated state, the core is moved relatively along the surface of the cable, and the change in the eddy current generated in the portion of the conductor wire excited by the magnetic flux is changed from the change in the voltage of the coil. A cable inspection device characterized by being configured to detect. 2. The cable inspection device according to claim 1, wherein the diameter of the core is set to be substantially equal to the diameter of one conductor in the cable. 3. The cable inspection device according to claim 1 or 2, wherein the diameter of the coil is set to be substantially equal to the diameter of the cable. 4. The cable inspection device according to claim 3, wherein one end surface of the coil and one end surface of the core are substantially flush with each other. 5. The cable inspection device according to claim 3, wherein when the cable is a tail cord of an elevator, the frequency of the alternating current flowing through the coil is set to a predetermined value larger than 10 kHz. .