JPH0827262B2 - Corrosion degradation determination method for double-layer metal wire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining corrosion deterioration of a two-layer metal wire rod such as a galvanized steel stranded wire in which the core wire is covered with a dissimilar metal. It is possible to individually detect

[0002]

2. Description of the Related Art In a railway line 1 as shown in FIG. 5, which is laid for supplying electric power to an electric railway, a galvanized steel stranded wire comprises a catenary wire 2, a substitute trolley wire 3 and a support 4.
Widely used for branch lines, etc. Since this galvanized steel stranded wire is exposed to the outside air, it is necessary to periodically or as needed inspect the degree of corrosion and determine the replacement time in order to prevent a wire disconnection accident due to corrosion.

An eddy current flaw detection test method (Japanese Patent Laid-Open No. 2-54166) is known as a method for inspecting corrosion deterioration of metal wires. However, the inspection object of the conventional method is limited to those made of a single material such as aluminum only or copper only, and it cannot be used for those in which dissimilar metals are laminated such as galvanized steel stranded wire. There wasn't.

For this reason, a person who rides on a ladder, a tower, a maintenance vehicle, etc., visually inspects a galvanized steel stranded wire for corrosion and deterioration, visually approaches a line in a live or blackout state.

[0005]

The estimation of the replacement time of the galvanized steel stranded wire is based on the corrosion amount of the galvanized layer applied to the surface to prevent corrosion and the corrosion amount of the steel stranded wire portion which maintains the strength. It is necessary to make a comprehensive judgment. However, since the visual inspection method is judged by the external appearance, it is difficult to grasp the progress of corrosion to the inside, and it is easy to make an error in estimating the replacement time. For example, even if most of the galvanized layer on the surface remains, corrosion at one location goes deep inside, and the strength of the wire may be greatly reduced compared to galvanized steel. As a result of this misconception,
There were problems such as disconnection accidents and replacement of wires that were still fully usable. For this reason, the number of inspections has been increased to half a year or once a year, but proper management was difficult.

On the other hand, this visual inspection work is an aerial work for riding on a maintenance car or the like because it is necessary for a person to approach the galvanized steel stranded wire at a high position. It also takes time and effort to see. Furthermore, maintenance vehicle operators are also required, and since this galvanized steel stranded wire is installed at a considerable distance along the railway, it requires a lot of manpower and the work cost is very high. Was becoming.

Therefore, the object of the present invention is to provide a corrosion deterioration judging method capable of separately detecting the amount of remaining double-layer metal wire rod such as a galvanized steel wire after corrosion for each metal by a simple operation. And

[0008]

The method for determining corrosion deterioration of a two-layer metal wire provided by the present invention is an exciting means for generating an eddy current along a wire in which the outer periphery of a first metal is covered with a second metal. And move the detector that has a detection coil for magnetic field change due to this eddy current,

When there is no wire rod in the two-dimensional plane represented by the phase and the amplitude as shown in FIG. 1, the output when the phase detection is performed so that the maximum output is obtained with respect to the induced voltage generated in the detection coil. Is the origin c, the output of the wire rod without corrosion is point a, and the output of the wire rod of only the first metal from which the second metal on the outer periphery is peeled off is point b,

Points a and b for the wire to be detected for corrosion
Component in the direction orthogonal to the straight line connecting the two (corresponding to the first metal)
(The phase angle of the vector E in FIG. 1) and the component in the direction orthogonal to the straight line connecting the point b and the origin c (second
(Corresponding to the metal of), the phase is detected (the phase angle of the vector F in FIG. 1), and

Each detected output is compared with known reference data obtained, for example, as shown in FIG. 2, which is obtained by investigating the relationship between the remaining amount of the preliminarily metal and the output. The feature is that the amount of corrosion is calculated and displayed individually and used to estimate the wire replacement time.

[0012]

The method of the present invention applies the principle of the eddy current flaw detection test method for examining metal flaws and the like. In this eddy current flaw detection test method, an alternating magnetic field is applied to a test body to generate a vortex flow, the impedance of the test body is known from the size of the vortex flow, and the size of the scratch or the like is determined from this. Specifically, the induced voltage generated in the detection coil by the eddy current is phase-detected at a predetermined phase in order to extract only the signal component, and is used as a detection output. This phase detection is a predetermined phase in which the signal component has a maximum value at the same frequency as the frequency of the acting magnetic field, and for example, a half cycle (180
The gate of an FET (field effect transistor) is turned on / off by a positive / negative pulse signal which is inverted every (°), and the average value of the voltage passing through this gate is used as a detection output. This phase has a value peculiar to the material of the detector.

However, when a double-layer metal wire rod such as a galvanized steel stranded wire is inspected by such a general eddy current flaw detection test method, the phase at which the maximum output is obtained changes with the progress of corrosion, and the detection output The amplitude of does not correspond to the amount of corrosion and cannot be used.

FIG. 1 shows, as a vector in a two-dimensional plane represented by the X-axis and the Y-axis, how the phase at which the maximum output is obtained and its amplitude change as the corrosion of the galvanized steel wire progresses. .

In this figure, the output when the galvanized steel wire does not exist (air core) is taken as the zero value vector C at the origin c, and the phase detection output when the galvanized steel wire is new is on the X-axis. Is represented by the vector A. The dotted line a-b-c in the figure indicates the phase when the corrosion of the galvanized steel wire progresses only to the galvanized portion first and progresses to the wire portion of the steel after the galvanized portion has completely disappeared. It is the locus drawn by the tip of the vector D indicating the detection output. As the zinc plating layer decreases due to corrosion, the tip of the vector D of the phase detection output moves from point a to point b in the figure. When the galvanized layer disappears, the point b is reached. Furthermore, when the wire portion of the steel also decreases due to corrosion, the tip of the vector D moves toward the point c, which is the origin, and reaches the origin c when the wire portion of the steel disappears at all.

From the above relation, it is understood that the following law is established. When only the galvanized layer decreases, the tip of the vector D changes linearly from point a to point b,
The component in the direction orthogonal to this changing direction does not change. This component corresponds to steel strands whose volume does not change. Therefore, in order to represent this component, a perpendicular line from the origin c to the straight line connecting the points a and b is set as the iron axis E. As the steel strand decreases, the tip of the vector D changes linearly from the point b to the point c. This corresponds to the amount of steel strands, and this amount of change can be read from the projection of the vector D on the iron axis E.

The vector D moves from the point a to the point b as the volume of the galvanized layer decreases. In order to read this change in the galvanized layer, draw a straight line from point a parallel to the straight line connecting points b and c so that it will not be affected by changes in the volume of the steel strand, and draw a perpendicular line from the origin to this straight line. Zinc axis F. As can be seen from FIG. 1, the projection of the vector D on the zinc axis F shows the remaining amount of the galvanized layer.

That is, the component of the vector D indicating the phase detection output of the galvanized steel strand in the direction of the zinc axis F is proportional to the amount of zinc remaining, and the component of the vector D in the direction of the iron axis E remains. It is more proportional to the dose than steel. Although these proportional relationships are not linear, they can be converted into data as shown in FIG. 2 as having a certain relationship.

In order to obtain the component of the vector D in the iron axis E direction and the component of the zinc axis F direction, the induced voltage generated in the detection coil is phase-detected with the phase of the iron axis E and the phase of the zinc axis F, respectively. do it.

Then, the zinc axial direction component and the iron axial direction component thus taken out are collated with the corresponding data table of the abundance of the detection target metal and the detection output, which has been previously investigated. , Read the remaining amount of the galvanized layer and the stranded steel wire individually, and make a comprehensive determination of the replacement time of the galvanized steel stranded wire based on past accumulated data.

Corrosion of the galvanized layer and the steel stranded wire does not always progress stepwise as described above, but in many cases, the corrosion occurs in parallel at the same time. Therefore, the locus of the vector D is actually It will pass near the dotted line connecting the points abc. Even in this case, it has been confirmed by experiments with a large number of test bodies that the correspondence relationship between each detection output and the residual amounts of both metals is the same as in the case where corrosion progresses in stages.

Although the above description has been made with respect to a galvanized steel stranded wire, the method of the present invention can detect the phase detection output when only the coated metal is reduced, even if the wire is a combination of other kinds of metals. Also, if there is a law that the phase detection output when only the internal metal is reduced changes linearly on a two-dimensional plane that represents the phase and the amplitude, respectively, it can be similarly implemented.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention is to perform measurement based on the above-mentioned principle. Means for applying an alternating magnetic field for generating an eddy current at the time of measurement, coil structure for detecting changes in eddy current, and detection The coil output processing method can be arbitrarily selected within a range in which the above method can be implemented.

Next, a specific example will be described. FIG. 3 shows a configuration example of a detection circuit using a mutual induction type coil. In this circuit, L1 and L2 are primary coils connected in series, to which an exciting AC power source e of a predetermined frequency (1 KHz to 250 KHz) selected according to the wire to be inspected is connected. L3 and L4 are secondary-side detection coils connected in series and are arranged close to and located in the primary coils L1 and L2, respectively, and L1 and L3 and L2 and L4 form separate magnetic circuits. The secondary detection coils L3 and L4 are 2
It is bridge-connected to the resistors R1 and R2 and the balancing resistor R3. The output of this bridge circuit 5 is 2
Secondary detection coil L3, L4 midpoint and balancing resistor R
It is taken out from the movable contact 3 and output to the processing circuit 6. The processing circuit 6 generates a predetermined phase signal from the exciting AC power source e by a phase shift circuit (not shown), performs phase detection, and causes the display 7 to display the detection output.

In this structure, the magnetic circuit portions of the coils L1 and L3 are always in the air-core state, and the other coils L2 and L4 are used while being moved close to the galvanized steel stranded wire. The bridge circuit 5 is for adjusting the zero point, and when the coils L2 and L4 are not opposed to the stranded wire of galvanized steel, the balancing resistor R3 is adjusted to make its output zero. As a result, the phase detection output as shown in FIG. 1 is obtained.

After adjusting the zero point, when a coil of galvanized steel is inserted through the coils L2 and L4, the output changes according to the conditions shown in FIG. As described above, this output is obtained in the phase in which only the component in the zinc axis F direction (representing the residual amount of zinc) is extracted and in the phase in which only the component in the iron axis E direction (representing the residual amount of steel strand) is extracted. , Respectively, phase detection is performed. Each detection output is taken out separately and displayed on the display. For this display, for example, a dedicated meter is provided for zinc and steel stranded wire to display 0-100% (100% when there is no corrosion). This display shows the phase detection output,
It is also possible to display the actual amount of the remaining metal by making a correction based on the corresponding data of the phase detection output and the remaining amount obtained by the preliminary measurement. The prediction of the replacement time of the galvanized steel stranded wire will be made in light of past data, taking into account the overhead wire condition of the tested galvanized steel stranded wire.

FIG. 4 shows an example of the mechanical constitution of the detector for carrying out the method of the present invention. Reference numeral 7 denotes a sensor portion of the detector, in which the primary coils L1 and L2 and the secondary side detection coils L3 and L4 are provided in a box-shaped case 9 having two guide rollers 8 that run on a galvanized steel stranded wire. It is decorated. The sensor unit 7 is pulled by a long insulating rod 10 held by an inspector and runs on a galvanized steel stranded wire. Reference numeral 11 denotes a detector main body that an inspector can carry around by carrying it on his / her shoulder, and has an exciting AC power supply e, a transfer circuit, a phase detection circuit, a display, etc., and is connected to the sensor unit 7 by a retractable spiral wire 12. ing. This configuration greatly improves workability. Depending on the location, it is also possible for the inspector to carry out the corrosion deterioration inspection simply by walking under the overhead line without using a ladder, a tower, a maintenance car, or the like.

[0028]

According to the present invention, the corrosion state of a two-layer metal wire rod such as a galvanized steel stranded wire can be accurately grasped by a simple operation. Therefore, the maintenance method of the galvanized steel stranded wire can be shifted from the inaccurate time base maintenance by visual inspection, which has been conventionally adopted, to the accurate condition maintenance standard using equipment diagnostic equipment. As a result, the inspection cycle can be extended, the number of personnel inspecting the wire for galvanized steel each year can be reduced, and replacement of usable galvanized steel wires is eliminated, which reduces maintenance costs for the wires. be able to.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the method of the present invention showing a state in which the phase detection output of a double-layer metal wire changes due to corrosion during an eddy current test.

FIG. 2 is a diagram showing an example of the relationship between the residual amount of metal and the detection output.

FIG. 3 is a circuit diagram showing a specific example of a detection circuit for carrying out the method of the present invention.

FIG. 4 is an external configuration diagram of a detector of one specific example for carrying out the method of the present invention.

FIG. 5 is a perspective view showing a train track facility of an electric railway in which a galvanized steel stranded wire is used.

[Explanation of symbols]

A Vector showing phase detection output of wire without corrosion (tip is point a) B Vector showing phase detection output of wire with only first metal (point is b) C Phase without wire Detection output (referred to as origin c) D Vector showing phase detection output of wire rod in progress of corrosion E Vector having phase to obtain remaining amount of first metal (iron axis) F Obtaining remaining amount of second metal Vector (Zinc axis) with a certain phase 5 Sensor part of the detector L3, L4 Detection coil 6 Phase detection circuit (processing circuit) 7 Indicator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Goro Yokota, 1-13 13 Midodencho, Yamanouchi, Ukyo-ku, Kyoto Prefecture, Kyoto Electronics Co., Ltd. (56) Reference JP-A-63-212804 (JP, A) JP-A-59-40287 (JP, A)

Claims (1)

[Claims] 1. A detector having an exciting means for generating an eddy current in each metal and a detector having a coil for detecting a magnetic field change caused by the eddy current is moved along a wire rod in which an outer circumference of the first metal is covered with the second metal, In the two-dimensional plane that represents the output when the phase detection is performed so as to obtain the maximum output for the induced voltage generated in the detection coil, the output when there is no wire is the origin c, and the wire without corrosion is the wire. output when the point a, the output of the first metal only wires of peeling the second metal of the outer periphery and a point b of, with respect to wire corrosion detected, out corresponding to the second metal
The phase at which the component (corresponding to the first metal) in the direction orthogonal to the straight line connecting the points a and b at which the force is removed is obtained, and the first gold
The phase detection is performed at the phase at which the component (corresponding to the second metal) in the direction orthogonal to the straight line connecting the point b and the origin c where the output corresponding to the genus is excluded is obtained, And a corrosion deterioration determination method for a two-layer metal wire rod, which comprises individually calculating the amount of corrosion of the second metal.