JP2003050234A - Eddy-current flaw detection testing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eddy-current flaw detection testing device capable of making an analysis required for flaw detection using many parameters while reducing noise components caused by lift-off, without needing to take a null state. SOLUTION: This eddy-current flaw detection testing device detects the change, generated by a discontinuous part around the surface, of an eddy current induced around the surface of a test object 22 by the AC magnetic field formed by an exciting coil 1a, by the change of the magnetic field detected by a detecting coil 2a, and detects the flaw of the test object 22 on the basis of the change. The device is provided with a means 25 for supplying an alternating current whose frequency is changed continuously or stepwise, to the exciting coil 1a, and detecting means 17a, 18a, 21 for detecting the change of the magnetic field generated by the discontinuous part around the surface, of the eddy current induced to the test object 22. The detecting coil 2a is formed by winding a conductor in triangular shape, setting a direction intersecting the center axis direction of the exciting coil 1a, as the center axis direction. One side of the triangle is disposed on the exciting coil 1a side, and the opposed apex of one side is disposed to be separated from the exciting coil 1a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a change in eddy current caused by a discontinuity near the surface of an eddy current induced near the surface of a test object made of a conductor by an alternating magnetic field formed by an exciting coil. The present invention relates to an eddy current flaw detection test apparatus for detecting flaws on a test object by detecting the output voltage of a detection coil due to the induced alternating magnetic field.

[0002]

2. Description of the Related Art Eddy current flaw testing is an inspection for material manufacturing in the steel industry, quality control at the product stage in rolling, forging, drawing of automobile parts, etc. for quality assurance,
In addition, it is performed in a wide range such as maintenance inspections of power plants and chemical plants and operation monitors. Eddy current testing
An AC magnetic field is generated by passing an AC current through an exciting coil placed close to the test surface, and the eddy current induced on the test surface by the AC magnetic field changes due to cracks on the test surface. Is used.
To detect the change in eddy current, the exciting coil is moved at a substantially constant speed on the surface to be tested and compared with the signal of a sound part where there is no crack or the like.

The eddy current density induced on the surface under test is
Depends on the magnetic field strength and the material under test (resistivity, permeability). When there is a crack such as a crack on the surface of the test object, the apparent resistance changes because the flow path of the eddy current occurs at the boundary between the flaw part and the normal part. Further, the change in the strength and direction of the magnetic field generated by the eddy current changes the magnetic field related to the system of the coil and the surface to be tested, so that the voltage induced in the detection coil changes. Since this voltage change can be detected as a change in amplitude and phase, the method of measuring the amplitude and phase of the terminal voltage of this coil and detecting flaws such as cracks existing on the surface of the test object based on the measurement results is an eddy current flaw test. It is called the law. In general, information related to flaws has two factors, that is, phase and amplitude. Therefore, theoretically, quantification of flaws and noise can be performed as compared with other radiation flaw detection test methods and ultrasonic flaw detection test methods. It is said that the distinctiveness with

FIG. 15 is a block diagram showing an example of the essential structure of a conventional eddy current flaw detector. This eddy current testing apparatus includes an oscillator 10 that oscillates a sine wave signal of frequency F, and a power amplifier 1 that amplifies the sine wave signal oscillated by the oscillator 10.
1 and the exciting coil 1 that is excited by the AC current of the frequency F output by the power amplifier 11 and output, and the eddy current generated near the surface of the test object 22 by this excitation. A detection coil 2 that detects an AC magnetic field and outputs an AC voltage, and an AC voltage that is output by the detection coil 2 are amplified, and an opposite phase voltage is added to the output voltage of the detection coil 2 in a healthy portion of the test target 22. An arithmetic unit 14 that adjusts the amplified voltage to a value near 0 to make it a null state and phase detectors 17 and 18 to which the AC voltage amplified by the arithmetic unit 14 is applied, respectively.

As shown in FIG. 16, an eddy current flaw detection probe comprising an exciting coil 1 and a detecting coil 2 comprises an annular exciting coil 1 and an annular detecting coil 2 having the same diameter as that of the exciting coil 1. The exciting coil 1 and the detecting coil 2 are coaxially arranged in parallel, and the surface of the detecting coil 2 opposite to the exciting coil 1 is used as a flaw detection surface.

When a flaw is present on the surface of the test object 22, an eddy current flows along the flaw. Therefore, when the eddy current flaw detection probe is moved from the flaw-free portion to the flaw-present portion, the eddy current The flow path morphology changes. As a result, the strength and direction of the magnetic field generated by the eddy current change, and the voltage (output) between the terminals of the detection coil 2 induced by this magnetic field changes. This voltage change can be usually detected as a change in the amplitude and phase of the AC voltage.

This eddy current flaw detection test apparatus also uses the oscillator 1
0 shifts the phase of the sine wave signal oscillated and gives it to the phase detectors 17 and 18, respectively, the sine wave signal oscillated by the oscillator 10, and the sine wave shifted by the phase shifter 15 In order for the arithmetic unit 14 to add a voltage signal whose amplitude and phase are changed by the instruction signal from the arithmetic unit 14 to the AC voltage from the detection coil 2 to make it into a null state based on the signal,
The balancer 16 provided to the arithmetic unit 14 and the phase detectors 17 and 1
Based on the A / D converters 19 and 20 for analog / digital conversion of the outputs of 8 and the digital signals output from the A / D converters 19 and 20, respectively, a flaw detection process near the surface of the test object 22 is performed. And a digital signal processing device 21.

In the null state, the calculator 14 determines whether the amplified voltage of the output voltage of the detection coil 2 is within a predetermined voltage near 0. If it is not within the predetermined voltage, the balancer 16 An instruction signal is output so as to change the amplitude and phase of the voltage signal applied to the arithmetic unit 14, and the amplified voltage obtained by adding the voltage signal from the balancer 16 to the output voltage of the detection coil 12 is within a predetermined voltage and is in a null state. This operation is repeated until. When the balancer 16 is in the null state, the balancer 16 locks the amplitude and phase at that time to be given to the arithmetic unit 14.

The operation of the eddy current flaw testing apparatus having such a structure will be described below. The power amplifier 11 is the exciting coil 1
An alternating current of frequency F is supplied to. The eddy-current flaw detection probe has an appropriate distance from the test object 22 in a state where the lower surface which is the flaw detection surface is opposed to the surface of the flat test object 22 such that the central axis of the exciting coil 1 is substantially orthogonal to the surface of the test object 22. An eddy current is induced near the surface of the test object 22 which is separated by the alternating magnetic field formed by the exciting coil 1. At the start of the flaw detection test, the calculator 14 sets the amplified voltage of the output voltage of the detection coil 2 in the null state in the sound part of the test target 22, and after the null state, outputs the detection coil 2. The voltage signal from the balancer 16 is added to the amplified voltage of the voltage and output.

The detection coil 12 detects an AC magnetic field formed by an eddy current having a frequency F and outputs an AC voltage having a frequency F. This AC voltage is amplified by the calculator 14 and given to the phase detectors 17 and 18, respectively. On the other hand, the sine wave signal oscillated by the oscillator 10 is phase-shifted by the phase shifter 15 by the phase shift due to the excitation coil 1, the test object 22, and the detection coil 2, and is given to the phase detector 17 as a reference voltage. The phase shifter 15 also includes the phase detector 1
A sine wave signal whose phase is displaced by 90 ° from the sine wave signal given to 7 is given to the phase detector 18 as a reference voltage.

The voltages detected and output by the phase detectors 17 and 18 are converted into digital signals by the A / D converters 19 and 20, respectively, and the digital signal processing device 21 makes the test target 22 based on these digital signals. Detects flaws near the surface of the. When a flaw exists near the surface of the test object 22, the phase of the AC voltage output by the detection coil 2 is displaced by θf, which is peculiar to the flaw. Therefore, as shown in FIG. 17A, the magnitude of the flaw signal is determined from the component S1 detected by the phase detector 17 and having a phase of 0 ° and the component S2 detected by the phase detector 18 and having a phase of 90 °. (S1 ² + S2 ² ) ^1/2 and the phase θf = tan ⁻¹ (S2 / S1) of the flaw signal can be obtained.

The flaw signal generally draws a semicircular vector diagram as shown in FIG. 17B according to the frequency F of the alternating current supplied to the exciting coil 1. When the frequency F is high, The phase θf peculiar to the flaw becomes small. At low frequency A, the effect of lift-off is largely included in the inductance component, at middle frequency B, the effect of lift-off is small, and at low frequency C, the effect of lift-off is largely included in the resistance component.

[0013]

When an eddy-current flaw detection test is conducted with the eddy-current flaw-detection test apparatus having such a configuration, the test object 2
The density of the eddy current induced near the surface of
2 changes due to the material change and the spatial relationship between the lift-off etc. exciting coil 1 and the test object 22 and does not depend only on flaws, so it is not possible to make an accurate judgment using only the two parameters of phase and amplitude. There is a problem. Even if the current supplied to the exciting coil 1 is constant, if the degree of spatial coupling between the exciting coil 1 and the test object 22 changes,
The magnetic field strength applied to the surface of the test object 22 changes,
If there is a factor that causes a local change in the resistivity and magnetic permeability of the test object 22, such as a local change in the material such as segregation of the test object 22 and a change in the surface hardness, an eddy current induced in the test object 22 is present. Changes locally.

Therefore, since the output voltage of the detection coil 2 is measured, whether the change in the output voltage is caused by the flaw or the change in the distance between the exciting coil 1 and the detection coil 2 and the surface of the test object 22 is considered. However, it was extremely difficult to determine whether or not it was due to a local material change near the surface of the test object 22.

Many proposals have been made to solve such problems. One of them is called a multi-frequency eddy current flaw detection method and is used for periodic inspection of steam generator thin tubes of nuclear power generation facilities. This method supplies a current having a plurality of frequency components to one exciting coil to induce an eddy current having a plurality of frequency components in a test object. Since the output voltage of the detection coil also has a plurality of frequency components, this output voltage is divided into voltages having individual frequencies by means of a filter or the like, and the amplitude and phase components of each voltage are collected to make the same. The parameter of the signal obtained from the flaw is increased, and more information can be obtained.

For example, a steam generator thin tube made of a Ni alloy is usually inserted and fixed in a hole provided in a vibration prevention plate called a baffle plate. Both ends are attached to the wall plate, and even if there are harmful flaws on the inner surface of the pipe where there are wall plates and baffle plates made of different materials, the signal from the wall plate or baffle plate is largely detected and the harmful flaws are not detected. The fine signal due to could not be detected by the usual method.

At present, for example, 200 kHz and 400
A flaw detection test is performed using two frequencies of kHz, and a signal due to a flaw on the inner surface of the pipe and a signal due to the baffle plate are discriminated. Furthermore, for example, when discriminating between a baffle plate and a flaw (possible with two frequencies), classifying a flaw, and quantitatively evaluating a flaw depth, four frequencies are used because the number of parameters is insufficient at two frequencies. ing. As described above, in the multi-frequency eddy current flaw detection method, it is necessary to increase the frequency to be used if more precise analysis accuracy and more discrimination items are targeted, and avoid increasing the size of the flaw detection test equipment and rising prices. There was a problem that I could not. Therefore,
Normally, up to 4 frequencies are only practically used.

Another proposal is called the pulse eddy current flaw test method, and when a DC pulse current is supplied to the exciting coil, the eddy current induced in the test object theoretically has an infinite frequency. With the columns, the output voltage of the detection coil can be decomposed into a voltage in an infinite frequency band, and a result equivalent to that obtained by performing a flaw detection test using an infinite test frequency can be obtained. However, since the exciting coil acts as an inductance load of the power amplifier to be connected, when a DC pulse is supplied to the exciting coil, the waveform becomes dull and only a finite frequency can be detected. Due to the difficulty and the difficulty of increasing the eddy current density, the depth information of the test object cannot be collected as expected, which is why it has not reached the practical level today. .

As described above, in the eddy current flaw detection test, two parameters of the amplitude and phase of the flaw signal voltage are used. However, the size of the flaw, the type of flaw and the depth direction of the test object in which the flaw exists. In order to carry out the analysis required for flaw detection, such as detecting the position of and the effect of lift-off, many parameters are required, and the analysis is not possible with two phases of single frequency and amplitude. This is possible, and the method described above as a method therefor has a problem that the flaw detection test apparatus becomes complicated and expensive.

On the other hand, in addition to the above-mentioned proposals for the current flowing through the exciting coil, there has also been proposed an improvement of the eddy current flaw detection probe including the exciting coil and the detecting coil. FIG. 18 is a schematic diagram showing an outline of an eddy current flaw detection probe published on page 131 of a summary of lectures by the Japanese Society for Nondestructive Inspection in Autumn 2000. This eddy current flaw detection probe includes an annular exciting coil 1a and a square annular detecting coil 2b, and detects one side of the detecting coil 2b in the diametrical direction of the exciting coil 1a inside the exciting coil 1a. The exciting coil 1a and the detecting coil 2b are arranged so that the central axis of the coil 2b is orthogonal to the central axis of the exciting coil 1a.
Are arranged.

FIG. 19 is an explanatory view for explaining the flow path of the eddy current generated on the surface of the test object 22. As shown in FIG. 19A, when there is no flaw on the surface of the test object 22, the eddy current on the surface of the test object 22 flows in the same circumferential direction as the winding direction of the exciting coil 1a. In this case, due to this eddy current, a magnetic field is hardly generated in the direction in which the detection coil 2b is linked, and therefore, an electromotive force is hardly generated in the detection coil 2b. Further, in this case, since the output of the detection coil 2b is substantially 0, even if the liftoff changes, the noise component due to this is hardly included in the output of the detection coil 2b, and the output is in the null state. You don't have to.

Further, as shown in FIG. 19B, when the surface of the test object 22 has a flaw, the eddy current flows along the flaw. When the detecting coil 2b is parallel to the longitudinal direction of the flaw, an eddy current flowing along the flaw causes a magnetic field in a direction interlinking with the detecting coil 2b, and an electromotive force is generated in the detecting coil 2b. For this reason, in the eddy current flaw detection probe described in the above-mentioned lecture summary, the output of the detection coil 2b contains almost no noise component, so that the flaw detection accuracy can be greatly improved.

However, this eddy current flaw detection probe has a problem that the output of the detection coil 2b still contains a noise component for the reason described below. In the eddy current flaw detection probe, since the exciting coil 1a is often a solenoid coil having a shorter length than the coil diameter, the magnetic field generated by the exciting coil 1a includes only a magnetic flux perpendicular to the surface of the test object 22. Instead of leaving, the magnetic flux bends to the outside of the exciting coil 1a as it moves away from the exciting coil 1a in the direction of the central axis thereof.

Therefore, as the distance from the exciting coil 1a increases, the magnetic field in the direction interlinking with the detecting coil 2b is present inside the detecting coil 2b, whereby a noise component corresponding to the change in lift-off is generated. 2b
Will be included in the output of. In addition, in order to reduce the above-mentioned noise component, there is a problem that the squareness between the central axis of the detection coil 2b and the central axis of the exciting coil 1a must be made strict in the manufacturing process. Further, as compared with the case where the longitudinal direction of the flaw is parallel to the detection coil 2b, when the longitudinal direction of the flaw is not parallel to the detection coil 2b, the output of the detection coil 2b is reduced, and the longitudinal length of the flaw is further increased. If the direction is perpendicular to the detection coil 2b, the flaw cannot be detected, and the flaw detection accuracy is low.

The Applicant has solved the above-mentioned problems, and in the magnetic field generated by the exciting coil, a component interlinking with the detecting coil is hardly contained inside the detecting coil, and the output of the detecting coil is Japanese Patent Application No. 2001-8296 proposes an eddy current flaw detection probe in which a noise component is reduced according to a change in contained lift-off, and an eddy current flaw detection probe capable of performing stable flaw detection irrespective of a flaw direction.

The present invention has been made under the background as described above, and in the first invention, the noise component according to the change of the lift-off included in the output of the detection coil is reduced,
It is an object of the present invention to provide an eddy-current flaw detection test device that does not need to be in a null state and can perform analysis required for flaw detection using a large number of parameters.

In the second invention, flaws can be detected stably regardless of the flaw direction, the null state is not required, and the analysis necessary for flaw detection is performed using a large number of parameters. It is an object of the present invention to provide an eddy-current flaw detection test device that is capable of In the third invention, it is possible to stably detect flaws regardless of the direction of the flaws, it is possible to detect the longitudinal direction of the flaws without requiring a null state, and use a large number of parameters. It is an object of the present invention to provide an eddy current flaw detection test device capable of performing an analysis required for flaw detection.

According to the fourth aspect of the present invention, flaws can be detected stably and accurately regardless of the flaw direction, no null state is required, and many parameters are used for flaw detection. It is an object of the present invention to provide an eddy current flaw testing device that can perform analysis. In the fifth invention, regardless of the direction of the flaw, it is possible to obtain an output voltage that accurately represents the nature of the flaw, improve the accuracy of flaw detection, and eliminate the need for a null state. It is an object of the present invention to provide an eddy current flaw testing device capable of performing analysis necessary for flaw detection using parameters.

[0029]

In the eddy current flaw detector according to the first aspect of the present invention, an eddy current induced near the surface of a test object made of a conductor by an alternating magnetic field formed by an exciting coil is discontinuous near the surface. The change caused by the presence of the portion is detected by the change in the magnetic field near the surface detected by the detection coil, and based on the change in the detected eddy current, in the eddy current flaw detection test device for performing flaw detection on the test object, the excitation A means for supplying an alternating current whose frequency changes continuously or stepwise to the coil, and a discontinuity near the surface of the eddy current induced near the surface of the test object by the alternating magnetic field formed by the exciting coil. A detecting means for detecting a change in the generated magnetic field, wherein the detecting coil has a conductor wound in a triangular shape with a direction intersecting with a central axis direction of the exciting coil as a central axis direction. In order to perform flaw detection on the test object based on the change detected by the detection means, one side of the triangle is arranged on the side of the excitation coil, and the opposite vertices of the side are arranged to be separated from the excitation coil. It is characterized by being done.

In this eddy current flaw detector, the change caused by the presence of the discontinuity near the surface of the eddy current induced near the surface of the test object made of a conductor by the alternating magnetic field formed by the exciting coil is detected. Detected by the change in the magnetic field near the surface detected by, and based on the detected change in the eddy current, the test object is flaw-detected. The supplying means supplies an alternating current whose frequency changes continuously or stepwise to the exciting coil, and the detecting means near the surface of the eddy current induced near the surface of the test object by the alternating magnetic field formed by the exciting coil. The change in the magnetic field caused by the discontinuity of is detected. The detection coil is formed by winding a conductor in a triangular shape with the direction intersecting the central axis direction of the exciting coil as the central axis direction. One side of the triangle is arranged on the side of the exciting coil, and the apex of the opposite side is the exciting coil. The test object is inspected based on the change detected by the detection means.

FIG. 20 is an explanatory view for explaining the direction of the magnetic field near the detection coil. Since the strength of the magnetic field formed by the exciting coil 1a changes in accordance with the change in lift-off,
If the detection coil is linked to its magnetic field, the voltage induced in the detection coil also changes, and this becomes a noise component. However, as shown in FIG. 20, the detection coil 2a having a triangular annular shape has its central axis direction orthogonal to the central axis direction of the exciting coil 1a, so that it almost interlinks with the magnetic field formed by the exciting coil 1a. do not do.

As a result, since the detection coil outputs almost no signal in the sound portion, the noise component according to the change in lift-off included in the output of the detection coil is reduced,
It is possible to realize an eddy-current flaw detection test device capable of performing analysis necessary for flaw detection using a large number of parameters without requiring a null state.

The eddy current flaw detector according to the second aspect of the present invention is caused by the presence of a discontinuity near the surface of the eddy current induced near the surface of the test object made of a conductor by the AC magnetic field formed by the exciting coil. The change is detected by the change in the magnetic field near the surface detected by the detection coil, based on the change in the detected eddy current, the flaw detection of the test object is performed, and the detection coil is in the central axis direction of the exciting coil. An eddy current flaw testing device, which is arranged on the central axis of the exciting coil so as to make the intersecting direction the central axis direction, and is designed to rotate about the central axis of the exciting coil. A means for supplying an alternating current whose frequency changes continuously or stepwise to the coil, and a discontinuity near the surface of the eddy current induced near the surface of the test object by the alternating magnetic field formed by the exciting coil. And a means for rotating the detection coil about the central axis, and based on the change detected by the detection means, flaw detection of the test object is performed. It is characterized by being present.

In this eddy current flaw detector, the change caused by the presence of the discontinuity near the surface of the eddy current induced near the surface of the test object made of a conductor by the AC magnetic field formed by the exciting coil is detected. Detected by the change in the magnetic field near the surface detected by, and based on the detected change in the eddy current, the test object is flaw-detected. The detection coil is arranged on the central axis of the exciting coil so that the direction intersecting with the central axis of the exciting coil is the central axis direction, and is configured to rotate about the central axis of the exciting coil. . The supplying means supplies an alternating current whose frequency changes continuously or stepwise to the exciting coil, and the detecting means near the surface of the eddy current induced near the surface of the test object by the alternating magnetic field formed by the exciting coil. The change in the magnetic field caused by the discontinuity of is detected. The rotating means rotates the detection coil about the center axis of the exciting coil, and the flaw detection of the test object is performed based on the change detected by the detection means.

Thus, the flaw can be detected stably regardless of the flaw direction, the null state is not required, and the analysis required for flaw detection can be performed using a large number of parameters. It is possible to realize a possible eddy current flaw testing device.

The eddy current flaw testing device according to the third aspect of the present invention is characterized by further comprising means for detecting the rotation angle of the detection coil.

Since this eddy current flaw detector has a means for detecting the rotation angle of the detection coil, the rotation angle at which the maximum output voltage is generated can be obtained during one rotation of the detection coil. By this, it is possible to detect the longitudinal direction of the flaw, it is possible to stably detect the flaw regardless of the direction of the flaw, and it is not necessary to set the null state,
It is possible to realize an eddy current flaw detection test device capable of performing analysis necessary for flaw detection using a large number of parameters.

In the eddy current flaw detector according to the fourth aspect of the present invention, the eddy current induced near the surface of the test object made of a conductor by the alternating magnetic field formed by the exciting coil is caused by the presence of the discontinuity near the surface. A eddy current flaw detection test device that detects a change based on the output voltage of each of a plurality of detection coils due to the alternating magnetic field induced by the eddy current, and performs flaw detection on the test object, in which the excitation coil has a continuous frequency. Means for supplying an alternating current that changes in a stepwise or stepwise manner, and a change in the magnetic field caused by the discontinuity near the surface of the eddy current induced near the surface of the test object by the alternating magnetic field formed by the exciting coil Detecting means for detecting the center of the exciting coil so that the plurality of different directions intersecting with the central axis of the exciting coil are different from each other. Yes by arranging on the shaft, characterized in that the detection means are no to perform flaw detection of the test object based on a change of the magnetic field detected.

In this eddy current flaw detector, the eddy current changes caused by the presence of a discontinuity near the surface of the eddy current induced near the surface of the test object made of a conductor by the alternating magnetic field formed by the exciting coil. Detected based on the output voltage of each of the plurality of detection coils due to the AC magnetic field induced in
Perform flaw detection on the test object. The supplying means supplies an alternating current whose frequency changes continuously or stepwise to the exciting coil, and the detecting means near the surface of the eddy current induced near the surface of the test object by the alternating magnetic field formed by the exciting coil. The change in the magnetic field caused by the discontinuity of is detected. The detection coil is arranged on the central axis of the exciting coil such that a plurality of different directions intersecting with the central axis direction of the exciting coil are set to the respective central axis directions, and the discontinuous portion detected by the detecting means. Based on the change of the magnetic field generated by, the test object is tested for flaws.

Thus, the flaw can be accurately detected by the detection coil substantially parallel to the flaw, and the flaw can be detected stably and accurately regardless of the direction of the flaw, and the null state can be obtained. It is possible to realize an eddy-current flaw detection test device capable of performing analysis necessary for flaw detection using a large number of parameters without requiring

The eddy current flaw detector according to the fifth aspect of the present invention further comprises a circuit for selecting the maximum output voltage among the output voltages of the plurality of detection coils, and the detection means has the output selected by the circuit. It is characterized in that the change of the magnetic field is detected based on the voltage.

In this eddy current flaw detector, the selecting circuit selects the maximum output voltage among the output voltages of the plurality of detecting coils, and the detecting means determines the maximum output voltage based on the output voltage selected by the selecting circuit. Since the change in the magnetic field is detected, by selecting the maximum output voltage, which is the output voltage of the detection coil that is closest to the parallel position with respect to the output voltage of multiple detection coils that cannot be placed in the detection coil, , Regardless of the direction of the flaw, it is possible to obtain an output voltage that accurately represents the nature of the flaw, improve the accuracy of flaw detection, do not need to be in the null state, and use many parameters. It is possible to realize an eddy current flaw detection test device capable of performing an analysis required for flaw detection.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings showing the embodiments thereof. Embodiment 1. FIG. 1 is a block diagram showing the configuration of essential parts of a first embodiment of an eddy current flaw detector test apparatus according to the present invention. As shown in FIG. 3A, this eddy-current flaw detection test device has a preset range (for example, 50 kHz to 500 kHz and a frequency ratio of 1 during a preset time (for example, 3 seconds)).
Sweep frequency (sweep)
p) (while continuously increasing or decreasing the frequency within a predetermined range), a sweep oscillator 25 (supplying means) that oscillates a sine wave signal, and power that amplifies the sine wave signal oscillated by the sweep oscillator 25. The amplifier 11 (supplying means), the AC current amplified by the power amplifier 11 and output, and the exciting coil 1a for exciting the vicinity of the surface of the test object 22 and the excitation coil 1a generated near the surface of the test object 22 by this excitation. A detection coil 2a for detecting an AC magnetic field due to an eddy current and outputting an AC voltage.

FIG. 2 shows the excitation coil 1a and the detection coil 2
It is a perspective view which shows the structural example of the principal part of the eddy current flaw detection probe comprised from a. The exciting coil 1a has a groove 32 having a width of 1 mm and a depth of 1.5 mm formed around the outer circumference of a polycarbonate annular member 31 having an outer diameter of 12 mm, an inner diameter of 6 mm and a thickness of 5 mm, and a copper wire is provided in the groove 32. A winding 33 having an outer diameter of 300 μm and covered with a polyimide resin is wound 120 times.

Further, the detection coil 2a is
Forming an equilateral triangle with one side slightly smaller than 6 mm,
A groove 42 having a width of 1 mm and a depth of 1 mm is provided on the outer periphery of a triangular member 41 made of polycarbonate having a thickness of 3 mm.
70μm outer diameter with copper wire coated with polyimide resin
The winding 43 is wound 100 times.

Although the exciting coil 1a has a circular ring shape, the shape is not limited to this, and needless to say, it may have another shape such as a square ring shape or a triangular ring shape.
Further, although the triangular member 41 has a regular triangular shape in the front view, the present invention is not limited to this, and it goes without saying that it may have an isosceles triangular shape in the front view, for example.

Such a detecting coil 2a is perpendicular to the exciting coil 1a, and one side of the detecting coil 2a is the exciting coil 1a.
Is inserted inside the annular member 31 until the lower surface of the detection coil 2a and the lower surface of the exciting coil 1a are aligned with each other. Needless to say, the exciting coil 1a and the detecting coil 2a are not limited to the above-described dimensions and materials, and may have other dimensions and materials.

This eddy current flaw detector also receives an AC voltage output from the detection coil 2a (FIG. 1) and amplifies the applied AC voltage and an AC voltage output from the amplifier 23 in phase. A phase detector 17a for detecting,
18a (means for detecting) and the phase of the sine wave signal oscillated by the sweep oscillator 25 are displaced, and the phase detector 17a,
18a, a phase shifter 15 and a phase detector 17a,
A for each analog / digital conversion of each output of 18a
A / D converters 19 and 20, and a digital signal processing device 21 (detection means) for detecting flaws near the surface of the test object 22 based on the digital signals output from the A / D converters 19 and 20, respectively. Is equipped with.

The operation of the eddy current flaw testing device having such a structure will be described below. In this eddy current flaw detection test apparatus, the sweep oscillator 25 causes the sweep oscillator 25 to set a preset range (5 seconds, for example, 3 seconds) as shown in FIG.
While sweeping the frequency at 0 kHz to 500 kHz and a frequency ratio of about 1 to 100),
Generates a sine wave signal. The power amplifier 11 amplifies the sine wave signal oscillated by the sweep oscillator 25 and supplies the amplified AC current to the exciting coil 1a.

The eddy-current flaw detection probe composed of the excitation coil 1a and the detection coil 2a is appropriately separated from the test subject 22 with the lower face which is the flaw detection face facing the surface of the flat test subject 22, for example. An eddy current is induced near the surface of the test object 22 by the alternating magnetic field formed by the exciting coil 1a. In this state, the eddy current flaw detection probe moves on the surface of the test object 22 at a substantially constant speed.

This eddy current is due to the frequency of the alternating current supplied to the exciting coil 1a, the material change of the test object 22, the spatial relationship between the lift-off etc. exciting coil 13 and the test object 22, and the vicinity of the surface of the test object 22. It changes depending on flaws such as cracks. When no flaw is present on the surface of the test object 22, an eddy current flows in the same direction as the winding direction of the exciting coil 1a on the surface of the test object 22, and a magnetic field is generated by the eddy current.

The detection coil 2a is arranged perpendicularly to the surface of the test object 22, and since the space inside the detection coil 2a becomes smaller as it moves away from the test object 22, the winding direction of the exciting coil 1a is different from that of the exciting coil 1a. Due to the eddy current in the same direction, a magnetic field interlinking with the detection coil 2a is hardly generated. Therefore, almost no electromotive force is generated in the detection coil 2a, and the output from the amplifier 23 becomes substantially zero.

When the lift-off changes, the strength of the magnetic field near the surface of the test object 22 generated by the exciting coil 1a changes, and thus the strength of the eddy current generated in the test object 22 changes. Although the strength of the magnetic field due to the eddy current also changes, the magnetic field due to the eddy current hardly interlinks with the detection coil 2a, so that almost no electromotive force is generated in the detection coil 2a and the output from the amplifier 23 is also generated. Still about 0
Becomes Therefore, the output of the detection coil 2a contains almost no noise component due to lift-off.

On the other hand, when there is a flaw on the surface of the test object 22, eddy current flows along the flaw, and the strength and direction of the magnetic field due to the eddy current are such that there is no flaw on the surface of the test object 22. Changes with respect to the strength and direction of the magnetic field due to the eddy current. Therefore, this magnetic field interlinks with the detection coil 2a, an electromotive force is generated in the detection coil 2a, and the output from the amplifier 23 changes.

The AC voltage amplified by the amplifier 23 is
It is given to the phase detectors 17a and 18a, respectively. On the other hand, the sine wave signal oscillated by the sweep oscillator 25 is phase-shifted by the phase shifter 15 by the phase shift due to the excitation coil 1a, the test target 22 and the detection coil 2a, and the schematic waveform of FIG. It is given to the phase detector 17a as a reference voltage as shown in the figure (the output voltage of the detection coil 2a is also the same). The phase shifter 15 also uses a sine wave signal whose phase is displaced by 90 ° from the sine wave signal given to the phase detector 17a as a reference voltage as shown in the schematic waveform diagram of FIG. 4B. It is given to the detector 18a.

The voltages detected and output by the phase detectors 17a and 18a are converted into digital signals by the A / D converters 19 and 20, respectively, and the digital signal processing device 21 makes the test target 22 based on these digital signals. Detects flaws near the surface of the. When a flaw exists near the surface of the test object 22, the phase of the AC voltage output by the detection coil 2a is displaced by θf which is peculiar to the flaw. Therefore, the digital signal processing device 21 is similar to that of FIG.
As shown in (a), the magnitude (S) of the flaw signal is calculated from the component S1 with a phase of 0 ° detected by the phase detector 17a and the component S2 with a phase of 90 ° detected by the phase detector 18a.
1 ² + S2 ² ) ^1/2 , and the phase of the flaw signal θf = t
An ⁻¹ (S2 / S1) can be obtained.

The digital signal processing device 21 records or outputs the flaw signal obtained by the above-described detection processing together with the timing signal (broken line) as shown in FIG. 4 (c). Further, since the digital signal processing device 21 can obtain amplitude and phase information for each frequency that continuously changes, it is possible to obtain an infinite number of parameters. Size, type,
It is possible to analyze the position in the depth direction of the test object in which flaws exist and the effect of lift-off.

In FIG. 3B, the frequency is continuously set to 50 kHz.
When swept from z to 500 kHz in 3 seconds,
It is a wave form diagram which showed the output signal of the amplifier 23 of the flaw signal of 0.3 mm in depth and 15 mm in length processed into the steel plate. The artificial flaw signal has substantially the same output value, and although it is not in the null state, the noise component according to the change in the lift-off included in the output of the detection coil 2a hardly occurs.
In the first embodiment, the frequency is continuously increased,
Although the number of times is one, it is also possible to continuously lower the frequency for flaw detection, and it is also possible to continuously repeatedly raise or lower the frequency for flaw detection. It is also possible to detect the flaw by repeatedly increasing and decreasing the frequency.

Embodiment 2. FIG. 5 is a block diagram showing a main configuration of an eddy current flaw detector test apparatus according to a second embodiment of the present invention. The eddy current flaw detection test apparatus includes an exciting coil 1a for exciting the vicinity of the surface of the test target 22 and a detection coil 2a for detecting an AC magnetic field due to an eddy current generated near the surface of the test target 22 by this excitation and outputting an AC voltage. It has and. The detection coil 2a is connected to a rotation shaft of a motor M (means for rotating) arranged coaxially with the excitation coil 1a so that the detection coil 2a can rotate about the central axis of the excitation coil 1a. It is configured. The motor M is rotationally driven by a motor drive circuit 24 whose drive is controlled by the digital signal processing device 21.

The detection coil 2a is connected to the rotary encoder R, and the rotary encoder R is connected to the digital signal processing device 21. The digital signal processing device 21 receives the output from the rotary encoder R and calculates the rotation angle of the detection coil 2a. Then, the amplifier 23 obtained while the detection coil 2a makes one revolution
The maximum output is extracted from the outputs from and the phase analysis is performed using this output. The analysis result is recorded and output together with the rotation angle of the detection coil 2a when the output was obtained. Other configurations and operations of the eddy current flaw testing device according to the second embodiment are similar to those of the eddy current flaw testing device described in the first embodiment. And its description is omitted.

In the second embodiment, the detection coil 2a has a triangular ring shape, but the present invention is not limited to this, and other shapes such as a ring shape or a square ring shape may be used. There is no end. Further, in the second embodiment, the detection coil 2a is configured to be rotatable around the central axis of the exciting coil 1a, but the present invention is not limited to this, and the detecting coil 2a is the center of the exciting coil 1a. It may have a configuration capable of swinging about an axis.

Embodiment 3. FIG. 6 is a block diagram showing a main configuration of an eddy current flaw detector according to a third embodiment of the present invention. This eddy current flaw detection test apparatus detects the excitation coil 1b that excites the vicinity of the surface of the test target 22 and three detections that detect an AC magnetic field due to the eddy current generated near the surface of the test target 22 by this excitation and output an AC voltage. Coils 3a, 3
b. 3c and.

FIG. 7 shows the excitation coil 1b and the detection coil 3
a, 3b. It is a perspective view showing an example of important section composition of a probe for eddy current inspection constituted by 3c. The dimensions of the annular member 31 are 10 mm in outer diameter, 6 mm in inner diameter, and 3 mm in thickness. The other structure of the exciting coil 1b is the same as the structure of the exciting coil 1a (FIG. 2) described in the first embodiment, and therefore, the same portions are denoted by the same reference numerals and the description thereof will be omitted.

Three detection coils 3a, 3b. 3c has a square ring shape, and is formed inside a square member 44, 44, 44 formed by winding a strip-shaped film having a width of 1 mm and a thickness of 50 μm into a square shape having a side length of 5 mm. , A thickness of 5 μm, a line width of 3 μm, a line spacing of 3 μm, and a number of turns of 100.

The film is made by sticking two polyimide films, and the windings 45, 45, 45 are
A copper foil having a thickness of 5 μm is adhered onto one of the polyimide films, and the copper foil is etched to form each of them. And the detection coils 3a, 3b, 3c are
This polyimide film and another polyimide film are attached so as to sandwich the windings 45, 45, 45, and are bent to form a square.

Detection coil 3 constructed in this way
a, 3b, 3c are superposed on each other such that the central portions of the upper sides of the detection coils 3a, 3b, 3c are located below in the order of the detection coils 3a, 3b, 3c. The center part of one side of the detection coil 3a, 3b, 3c
In the state that they are stacked on top of each other,
The detection coils 3a, 3b, 3c are arranged so as to be separated from each other by an angle of 60 °.

In the third embodiment, the detection coil 3
Although the overlapping order of the upper side of a, 3b, 3c is the same as the overlapping order of the lower side, the invention is not limited to this, and the upper side of the detection coils 3a, 3b, 3c is not limited to this. It is needless to say that the order of the overlapping of and the order of the overlapping of the lower side may be different. Further, although the number of detection coils is three in the third embodiment, the number of detection coils is not limited to this, and two detection coils may be used, or four or more detection coils may be used. . Further, in the third embodiment, the shape of the detection coil is a square ring, but it is not limited to this, and needless to say, it may be another shape such as a ring or a triangle.

The detection coils 3a, 3b and 3c are connected to amplifiers 23a, 23b and 23c (FIG. 6), respectively,
The amplifiers 23a, 23b, and 23c are connected to a selection circuit 29 (selection circuit) including a CPU, a memory, and the like. The outputs of the amplifiers 23a, 23b and 23c are converted into digital signals by an A / D converter (not shown) incorporated in the selection circuit 29 and given to the CPU. C
The PU determines which of the outputs of the amplifiers 23a, 23b, 23c has the maximum output, selects the maximum output, and supplies it to the phase detectors 17a, 18a.

FIG. 8 is a plan view showing the structure of the test object 22 used for the flaw detection test by the eddy current flaw detection test apparatus according to the third embodiment. The test object 22 was a steel plate having a rectangular parallelepiped shape in plan view, and 3 from the central portion (the portion indicated by A in the figure).
A flaw extending in the direction was provided. The flaw detection test was performed by scanning the eddy current flaw detection probe in the direction indicated by the arrow in the figure.

FIG. 9 shows the result of the flaw detection test. In the figure, the horizontal axis represents the position in the scanning direction, and the vertical axis represents the output voltage of the detection coil. The output voltage of the detection coil greatly changes not only in the central portion A but also before and after this portion. Therefore, it is understood that not only flaws extending in the direction parallel to the detection coil but also flaws extending in other directions are detected. Other configurations and operations of the eddy current flaw testing device according to the third embodiment are the same as the configurations and operations of the eddy current flaw testing device described in the first embodiment.
The same parts in the configuration are designated by the same reference numerals, and the description thereof will be omitted.

Fourth Embodiment FIG. 10 is a block diagram showing the main configuration of the eddy current flaw detector test apparatus according to the fourth embodiment of the present invention. This eddy current flaw detection test device is shown in FIG. 11 (a) according to the timing signal output from the reference time generator 26.
As shown in, during the set time (for example, 6 seconds),
Sweep oscillator 25a (supplying means) that oscillates a sine wave signal while increasing the frequency stepwise (for example, in 10 steps) within a set range (for example, 20 kHz to 200 kHz, preferably about 1 to 100 in frequency ratio).
A power amplifier 11 (supply means) for amplifying the sine wave signal oscillated by the sweep oscillator 25a;
The alternating current output by amplifying and outputting 1 is applied, and the test target 22
An exciting coil 1a for exciting the vicinity of the surface of the device and a detecting coil 2a for detecting an AC magnetic field due to an eddy current generated near the surface of the test object 22 by this excitation and outputting an AC voltage.

Since the structures of the exciting coil 1a and the detecting coil 2a are the same as the structures of the exciting coil 1a and the detecting coil 2a described in the first embodiment (FIG. 2), the description thereof will be omitted. This eddy current flaw detection test equipment is also provided with an AC voltage output from the detection coil 2a, an amplifier 23 for amplifying the AC voltage applied, and a phase detector 17a for phase-detecting the AC voltage output by the amplifier 23, respectively. 18a
(Means for detecting) and the phase of the sine wave signal oscillated by the sweep oscillator 25a are displaced, and the phase detectors 17a, 18
a and phase detectors 17a and 1a
A / which converts each output of 8a into analog / digital
A digital signal processing device 2 for detecting flaws near the surface of the test object 22 based on the digital signals output from the D converters 19 and 20 and the A / D converters 19 and 20, respectively.
1 (means for detecting).

The operation of the eddy current flaw testing device having such a configuration will be described below. In this eddy current flaw detector, the sweep oscillator 25a is set during the set time (for example, 6 seconds) by the timing signal output from the reference time generator 26, as shown in FIG. 11 (a). Range (2
A sine wave signal is oscillated while increasing the frequency stepwise (10 steps) at 0 kHz to 200 kHz. The power amplifier 11 amplifies the sine wave signal oscillated by the sweep oscillator 25a and outputs the amplified alternating current to the exciting coil 1a.
Supply to.

The eddy current flaw detection probe composed of the excitation coil 1a and the detection coil 2a is appropriately separated from the test object 22 with the lower surface as the flaw detection surface facing the surface of the flat test object 22, for example. Test target 2 in this state
The eddy current is induced in the vicinity of the surface of the test object 22 by the alternating magnetic field formed by the exciting coil 1a.

This eddy current is due to the frequency of the alternating current supplied to the exciting coil 1a, the material change of the test object 22, the spatial relationship between the exciting coil 13 such as lift-off coil 13 and the test object 22, and the vicinity of the surface of the test object 22. It changes depending on flaws such as cracks. When no flaw is present on the surface of the test object 22, an eddy current flows in the same direction as the winding direction of the exciting coil 1a on the surface of the test object 22, and a magnetic field is generated by the eddy current.

The detection coil 2a is arranged perpendicularly to the surface of the test object 22, and since the space inside the detection coil 2a becomes smaller with increasing distance from the test object 22, the winding direction of the exciting coil 1a is the same. Due to the eddy current in the direction, a magnetic field interlinking with the detection coil 2a is hardly generated. Therefore, almost no electromotive force is generated in the detection coil 2a, and the output from the amplifier 23 becomes substantially zero.

When the lift-off changes, the strength of the magnetic field near the surface of the test object 22 generated by the exciting coil 1a changes, and thus the strength of the eddy current generated in the test object 22 changes. Although the strength of the magnetic field due to the eddy current also changes, the magnetic field due to the eddy current hardly interlinks with the detection coil 2a, so that almost no electromotive force is generated in the detection coil 2a and the output from the amplifier 23 is also generated. Still about 0
Becomes Therefore, the output of the detection coil 2a contains almost no noise component due to lift-off.

On the other hand, when a flaw is present on the surface of the test object 22, when the eddy current flows along the flaw and the strength and direction of the magnetic field due to the eddy current are not present on the surface of the test object 22. Changes with respect to the strength and direction of the magnetic field due to the eddy current. Therefore, this magnetic field interlinks with the detection coil 2a, an electromotive force is generated in the detection coil 2a, and the output from the amplifier 23 changes.

The detection coil 2a detects an AC magnetic field formed by the eddy current and outputs an AC voltage. This AC voltage is amplified by the amplifier 23, and the phase detectors 17a, 1a, 1
8a respectively. On the other hand, the sine wave signal oscillated by the sweep oscillator 25a with respect to the timing signal output from the reference time generator 26 as shown in the schematic waveform diagram of FIG. The phase is displaced by the phase shifter 15a by the phase displacement by the detection coil 12, and the phase detector is used as a reference voltage as shown in the schematic waveform diagram of FIG. 12B (the output voltage of the detection coil 2a is also the same). 17a. The phase shifter 15a also uses a sine wave signal obtained by shifting the phase of the sine wave signal provided to the phase detector 17a by 90 ° as a reference voltage as shown in the schematic waveform diagram of FIG. It is given to the detector 18a.

The voltages detected and output by the phase detectors 17a and 18a are converted into digital signals by the A / D converters 19 and 20, respectively, and the digital signal processing device 21 operates as shown in FIG.
These digital signals are captured by the capture signal output from the reference time generator 26 as shown in the schematic waveform diagram of 2 (d), and the flaw detection process near the surface of the test object 22 is performed. When a flaw is present near the surface of the test object 22, the phase of the AC voltage output by the detection coil 12 is displaced by θf, which is peculiar to the flaw. Therefore,
As shown in FIG. 17A, the digital signal processing device 21 has a component S whose phase detected by the phase detector 17a is 0 °.
1 and the component S2 having a phase of 90 ° detected by the phase detector 18a, the magnitude of the flaw signal (S1 ² + S2 ² )
^1/2 , and the phase of the flaw signal θf = tan ⁻¹ (S2 /
S1) can be obtained.

Further, since the digital signal processing device 21 can obtain the information of the amplitude and the phase for each frequency that changes in a stepwise manner, it is possible to obtain an infinite number of parameters. , The size and type of the flaws described above, the position in the depth direction of the test object in which the flaws exist,
It is also possible to analyze the effects of lift-off and the like.

FIG. 11 (b) shows a flaw signal of 0.3 mm in depth and 15 mm in length machined in a steel plate when the frequency was raised stepwise from 20 kHz to 200 kHz in 10 steps in 6 seconds. 5 is a waveform diagram showing an output signal of the amplifier 23. FIG. Although not in the null state, a noise component included in the output of the detection coil 2a according to the change in lift-off is hardly generated. In the fourth embodiment,
Although the frequency is increased stepwise and the number of times is once, it is also possible to detect the flaw by decreasing the frequency stepwise, and to detect the flaw by repeatedly increasing or decreasing the frequency stepwise. Is also possible. It is also possible to detect the flaw by repeatedly increasing and decreasing the frequency stepwise.

Embodiment 5. FIG. 13 is a block diagram showing the main configuration of the fifth embodiment of the eddy current flaw detector test apparatus according to the present invention. The eddy current flaw detection test apparatus includes an exciting coil 1a for exciting the vicinity of the surface of the test target 22 and a detection coil 2a for detecting an AC magnetic field due to an eddy current generated near the surface of the test target 22 by this excitation and outputting an AC voltage. It has and. The detection coil 2a is connected to a rotation shaft of a motor M (means for rotating) arranged coaxially with the excitation coil 1a so that the detection coil 2a can rotate about the central axis of the excitation coil 1a. It is configured. The motor M is rotationally driven by a motor drive circuit 24 whose drive is controlled by the digital signal processing device 21.

The detecting coil 2a is connected to the rotary encoder R, and the rotary encoder R is connected to the digital signal processor 21. The digital signal processing device 21 receives the output from the rotary encoder R and calculates the rotation angle of the detection coil 2a. Then, the amplifier 23 obtained while the detection coil 2a makes one revolution
The maximum output is extracted from the outputs from and the phase analysis is performed using this output. The analysis result is recorded and output together with the rotation angle of the detection coil 2a when the output was obtained. Since other configurations and operations of the eddy current flaw testing device according to the fifth embodiment are similar to those of the eddy current flaw testing device described in the fourth embodiment, the same reference numerals are given to the same portions of the configuration. And its description is omitted.

Sixth Embodiment FIG. 14 is a block diagram showing a main configuration of an eddy current flaw detector according to a sixth embodiment of the present invention. This eddy current flaw detection test apparatus detects the excitation coil 1b that excites the vicinity of the surface of the test target 22 and three detections that detect an AC magnetic field due to the eddy current generated near the surface of the test target 22 by this excitation and output an AC voltage. Coil 3a,
3b. 3c and. Excitation coil 1b and detection coils 3a, 3b. 3c has the same structure as the excitation coil 1a and the detection coils 3a, 3b. Since the configuration is the same as that of 3c (FIG. 7), description thereof will be omitted.

The detection coils 3a, 3b, 3c are connected to amplifiers 23a, 23b, 23c (FIG. 14), respectively, and the amplifiers 23a, 23b, 23c are connected to a selection circuit 29 including a CPU and a memory. There is. Amplifier 2
The outputs of 3a, 23b, and 23c are converted into digital signals by an A / D converter (not shown) built in the selection circuit 29 and given to the CPU. The CPU determines which of the outputs of the amplifiers 23a, 23b, 23c is the maximum output, selects the maximum output, and supplies it to the phase detectors 17a, 18a. Other configurations and operations of the eddy current flaw testing device according to the sixth embodiment are the same as the configurations and operations of the eddy current flaw testing device described in the fourth embodiment, and therefore, the same parts are designated by the same reference numerals. And its description is omitted.

[0087]

According to the eddy current flaw detector according to the first aspect of the present invention, since the detection coil outputs almost no signal in the sound portion, the noise component according to the change in lift-off included in the output of the detection coil is reduced. However, it is possible to realize an eddy-current flaw detection test device that does not need to be in a null state and can perform analysis required for flaw detection using a large number of parameters.

According to the eddy-current flaw detector according to the second aspect of the present invention, it is possible to stably detect flaws regardless of the flaw direction, and it is not necessary to set the null state, and many parameters are utilized. It is possible to realize an eddy current flaw detection test device capable of performing an analysis required for flaw detection.

According to the eddy current flaw detector according to the third aspect of the present invention, the longitudinal direction of a flaw can be detected by obtaining the rotation angle when the maximum output voltage is generated during one rotation of the detection coil. The eddy current enables stable detection of flaws regardless of the flaw direction, does not require a null state, and can perform analysis necessary for flaw detection using many parameters. A flaw detection test device can be realized.

According to the eddy current flaw detector according to the fourth aspect of the present invention, flaws can be accurately detected by the detection coils that are substantially parallel to each other, and the flaws can be detected stably and accurately regardless of the flaw direction. It is possible to realize an eddy current flaw detection test device that can be performed and does not need to be in a null state and can perform analysis necessary for flaw detection using a large number of parameters.

According to the eddy current flaw detector according to the fifth aspect of the present invention, among the output voltages of the plurality of detection coils, the maximum output voltage of the detection coil located at the position closest to the inside of the detection coil is the maximum. By selecting the output voltage of
Regardless of the direction of the flaw, it is possible to obtain an output voltage that accurately represents the nature of the flaw, improve the accuracy of flaw detection, do not require a null state, and use a large number of parameters. It is possible to realize an eddy current flaw detection test device capable of performing the analysis required for flaw detection.

Further, in the conventional eddy current flaw detection test, in order to select the optimum test frequency, data is taken while changing the frequency many times, and the frequency that can detect the most desired flaw with a good S / N ratio is selected. Therefore, it usually takes about half a day to determine the flaw detection conditions. On the other hand, in the eddy current flaw detector test apparatus according to the first to fifth inventions, the result as shown in FIG. 3B can be obtained in only a few minutes.
It is immediately possible to determine that 0 kHz is optimal.

When it is desired to detect cracks, holes, protrusions, etc. at optimum frequencies,
Conventionally, an experiment was conducted to search for a frequency condition where three flaws were detected over a few days, but with the eddy-current flaw testing device according to the first to fifth inventions, it is possible to perform the test in a few minutes, and It is possible to save man-hours. In addition, since 3 types of flaws can be detected simultaneously, it is possible to perform a flaw detection test that was conventionally performed by changing the condition of 2 or 3 degrees once, and it is necessary to detect many types of flaws. It is possible to obtain an extremely large effect in an eddy current flaw detection test such as.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part configuration of an embodiment of an eddy current flaw testing device according to the present invention.

FIG. 2 is a perspective view showing a configuration example of a main part of an eddy current flaw detection probe including an excitation coil and a detection coil.

FIG. 3 is a waveform diagram showing the operation of the eddy current flaw testing device according to the present invention.

FIG. 4 is a waveform diagram showing the operation of the eddy current flaw testing device according to the present invention.

FIG. 5 is a block diagram showing a main part configuration of an embodiment of an eddy current flaw testing device according to the present invention.

FIG. 6 is a block diagram showing a main part configuration of an embodiment of an eddy current flaw testing device according to the present invention.

FIG. 7 is a perspective view showing a configuration example of a main part of an eddy current flaw detection probe including an excitation coil and a detection coil.

FIG. 8 is a plan view showing a configuration of a test object used for a flaw detection test by the eddy current flaw detection test apparatus according to the present invention.

FIG. 9 is a waveform diagram showing an example result of a flaw detection test.

FIG. 10 is a block diagram showing a main configuration of an embodiment of an eddy current flaw testing device according to the present invention.

FIG. 11 is a waveform diagram showing an operation of the eddy current flaw testing device according to the present invention.

FIG. 12 is a waveform diagram showing the operation of the eddy current flaw testing device according to the present invention.

FIG. 13 is a block diagram showing a main part configuration of an embodiment of an eddy current flaw testing device according to the present invention.

FIG. 14 is a block diagram showing a main configuration of an embodiment of an eddy current flaw detector according to the present invention.

FIG. 15 is a block diagram showing a configuration example of a main part of a conventional eddy current flaw testing device.

FIG. 16 is a perspective view showing a configuration example of a main part of a conventional eddy current flaw detection probe including an excitation coil and a detection coil.

FIG. 17 is an explanatory diagram showing a signal processing method of the eddy current flaw detector.

FIG. 18 is a schematic diagram showing an outline of a configuration example of a conventional eddy current flaw detection probe.

FIG. 19 is an explanatory diagram illustrating a flow path of an eddy current generated on the surface of the test target.

FIG. 20 is an explanatory diagram illustrating the direction of a magnetic field near the detection coil.

[Explanation of symbols]

1a, 1b Excitation coil 2a, 2b, 3a, 3b, 3c detection coil 11 Power amplifier (supply means) 15,15a Phase shifter 17a, 18a Phase detector (detection means) 19,20 A / D converter 21 Digital Signal Processing Device (Detecting Means) 22 test target 23, 23a, 23b, 23c Amplifier 24 Motor drive circuit 25,25a Sweep oscillator (supply means) 26 Reference time generator 29 Selection circuit (circuit to select) 33,43,45 windings M motor R rotary encoder

[Procedure amendment]

[Submission date] September 10, 2001 (2001.9.1)
0)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

In the null state, the calculator 14 determines whether the amplified voltage of the output voltage of the detection coil 2 is within a predetermined voltage near 0. If it is not within the predetermined voltage, the balancer 16 An amplification signal obtained by outputting an instruction signal to change the amplitude and phase of the voltage signal applied to the calculator 14 and adding the voltage signal from the balancer 16 to the output voltage of the detection coil 2 is within a predetermined voltage and is in a null state. This operation is repeated until. When the balancer 16 is in the null state, the balancer 16 locks the amplitude and phase at that time to be given to the arithmetic unit 14.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

The detection coil 2 detects an AC magnetic field formed by an eddy current having a frequency F and outputs an AC voltage having a frequency F. This AC voltage is amplified by the calculator 14,
It is given to the phase detectors 17 and 18, respectively. On the other hand, the sine wave signal oscillated by the oscillator 10 corresponds to the phase displacement due to the excitation coil 1, the test target 22, and the detection coil 2, and the phase shifter 15
The phase is displaced by the phase detector 17 as a reference voltage.
Given to. The phase shifter 15 also gives a sine wave signal whose phase is shifted by 90 ° to the sine wave signal given to the phase detector 17 to the phase detector 18 as a reference voltage.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

The flaw signal generally draws a semicircular vector diagram as shown in FIG. 17B according to the frequency F of the alternating current supplied to the exciting coil 1. When the frequency F is high, The phase θf peculiar to the flaw becomes small. At low frequency A, the effect of lift-off is largely included in the inductance component, at medium frequency B, the effect of lift-off is small, and at high frequency C, the effect of lift-off is largely included in the resistance component.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction content]

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings showing the embodiments thereof. Embodiment 1. FIG. 1 is a block diagram showing the configuration of essential parts of a first embodiment of an eddy current flaw detector test apparatus according to the present invention. As shown in FIG. 3A, this eddy-current flaw detection test device has a preset range (for example, 50 kHz to 500 kHz and a frequency ratio of 1 during a preset time (for example, 3 seconds)).
Sweep frequency (sweep)
p) (while continuously increasing or decreasing the frequency within a predetermined range), a sweep oscillator 25 (supplying means) that oscillates a sine wave signal, and power that amplifies the sine wave signal oscillated by the sweep oscillator 25. The amplifier 11 (supplying means), the exciting coil 1a that excites the vicinity of the surface of the test object 22 (test object) by the AC current amplified and output by the power amplifier 11, and the surface of the test object 22 by this excitation. A detection coil 2a for detecting an AC magnetic field due to an eddy current generated in the vicinity and outputting an AC voltage is provided.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction content]

This eddy current is due to the frequency of the alternating current supplied to the exciting coil 1a, the material change of the test object 22, the spatial relationship between the lift-off etc. exciting coil 1a and the test object 22, and the vicinity of the surface of the test object 22. It changes depending on flaws such as cracks. When no flaw is present on the surface of the test object 22, an eddy current flows in the same direction as the winding direction of the exciting coil 1a on the surface of the test object 22, and a magnetic field is generated by the eddy current.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0075

[Correction method] Change

[Correction content]

This eddy current is due to the frequency of the alternating current supplied to the exciting coil 1a, the material change of the test object 22, the spatial relationship between the lift-off equalizing exciting coil 1a and the test object 22, and the vicinity of the surface of the test object 22. It changes depending on flaws such as cracks. When no flaw is present on the surface of the test object 22, an eddy current flows in the same direction as the winding direction of the exciting coil 1a on the surface of the test object 22, and a magnetic field is generated by the eddy current.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0079

[Correction method] Change

[Correction content]

The detection coil 2a detects an AC magnetic field formed by the eddy current and outputs an AC voltage. This AC voltage is amplified by the amplifier 23, and the phase detectors 17a, 1a, 1
8a respectively. On the other hand, the sine wave signal oscillated by the sweep oscillator 25a with respect to the timing signal output from the reference time generator 26 as shown in the schematic waveform diagram of FIG. phase shift amount of the detection coil 2a, the phase displacement by the phase shifter 15a, Fig. 12 (b) of the schematic as shown in waveform (output voltage of the detection coil 2a as well) the phase detector as a reference voltage 17a. The phase shifter 15a also uses a sine wave signal obtained by shifting the phase of the sine wave signal provided to the phase detector 17a by 90 ° as a reference voltage as shown in the schematic waveform diagram of FIG. It is given to the detector 18a.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0080

[Correction method] Change

[Correction content]

The voltages detected and output by the phase detectors 17a and 18a are converted into digital signals by the A / D converters 19 and 20, respectively, and the digital signal processing device 21 operates as shown in FIG.
These digital signals are captured by the capture signal output from the reference time generator 26 as shown in the schematic waveform diagram of 2 (d), and the flaw detection process near the surface of the test object 22 is performed. When a flaw exists near the surface of the test object 22, the phase of the AC voltage output by the detection coil 2a is displaced by θf which is peculiar to the flaw. Therefore,
As shown in FIG. 17A, the digital signal processing device 21 has a component S whose phase detected by the phase detector 17a is 0 °.
1 and the component S2 having a phase of 90 ° detected by the phase detector 18a, the magnitude of the flaw signal (S1 ² + S2 ² )
^1/2 , and the phase of the flaw signal θf = tan ⁻¹ (S2 /
S1) can be obtained.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0085

[Correction method] Change

[Correction content]

Sixth Embodiment FIG. 14 is a block diagram showing a main configuration of an eddy current flaw detector according to a sixth embodiment of the present invention. This eddy current flaw detection test apparatus detects the excitation coil 1b that excites the vicinity of the surface of the test target 22 and three detections that detect an AC magnetic field due to the eddy current generated near the surface of the test target 22 by this excitation and output an AC voltage. Coil 3a,
3b. 3c and. Excitation coil 1b and detection coils 3a, 3b. 3c has the same structure as the excitation coil 1b and the detection coils 3a, 3b. Since the configuration is the same as that of 3c (FIG. 7), description thereof will be omitted.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Description of Reference Signs] 1a, 1b Excitation coil 2a, 2b, 3a, 3b, 3c Detection coil 11 Power amplifier (supplying means) 15, 15a Phase shifter 17a, 18a Phase detector (detecting means) 19, 20 A / D converter 21 Digital signal processing device (means for detection) 22 Test target (test body) 23, 23a, 23b, 23c Amplifier 24 Motor drive circuit 25, 25a Sweep oscillator (supply means) 26 Reference time generator 29 Selection Circuit (selection circuit) 33, 43, 45 Winding M Motor R Rotary encoder

[Procedure Amendment 11]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

[Procedure Amendment 12]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 14

[Correction method] Change

[Correction content]

FIG. 14

Claims (5)

[Claims] 1. An alternating magnetic field formed by an exciting coil,
The change in the eddy current induced near the surface of the test object made of a conductor caused by the presence of the discontinuity near the surface is detected by the change in the magnetic field near the surface detected by the detection coil, and the detected vortex is detected. In the eddy current flaw detection test apparatus for performing flaw detection on the test object based on a change in current, a means for supplying an alternating current whose frequency changes continuously or stepwise to the exciting coil, and an alternating magnetic field formed by the exciting coil. A detection means for detecting a change in a magnetic field generated by a discontinuity near the surface of the eddy current induced near the surface of the test object, the detection coil intersecting a central axis direction of the exciting coil. A conductor is wound in a triangular shape with the direction being the central axis direction, one side of the triangle is arranged on the side of the exciting coil, and the opposite vertex of the one side is separated from the exciting coil. An eddy-current flaw detection test apparatus, which is arranged so as to perform flaw detection on the test object based on a change detected by the detection means. 2. The alternating magnetic field formed by the exciting coil,
The change in the eddy current induced near the surface of the test object made of a conductor caused by the presence of the discontinuity near the surface is detected by the change in the magnetic field near the surface detected by the detection coil, and the detected vortex is detected. Based on the change in the current, the test object is flaw-detected, and the detection coil is arranged on the central axis of the exciting coil so that the direction intersecting the central axis direction of the exciting coil is the central axis direction. An eddy current flaw testing device adapted to rotate about a central axis of the exciting coil, comprising means for supplying an alternating current whose frequency changes continuously or stepwise to the exciting coil, and the exciting coil. A detection means for detecting a change in the magnetic field caused by a discontinuity near the surface of the eddy current induced near the surface of the test object by the AC magnetic field formed by An eddy-current flaw detection test apparatus, comprising: a means for rotating the eddy current flaw detection means for performing flaw detection on the test object based on a change detected by the detection means. 3. The eddy current flaw detector test apparatus according to claim 2, further comprising means for detecting a rotation angle of the detection coil. 4. The alternating magnetic field formed by the exciting coil,
The change caused by the presence of the discontinuity near the surface of the eddy current induced near the surface of the test object made of a conductor is changed to the output voltage of each of the plurality of detection coils due to the alternating magnetic field induced by the eddy current. An eddy current flaw detection test device for detecting flaws on the basis of detection, based on which the means for supplying alternating current whose frequency changes continuously or stepwise to the exciting coil, and the alternating magnetic field formed by the exciting coil And a detection means for detecting a change in the magnetic field generated by the discontinuity near the surface of the eddy current induced near the surface of the test object by the detection coil, and the detection coil is respectively in the central axis direction of the exciting coil. A plurality of different directions intersecting each other are arranged on the central axis of the exciting coil so as to be the respective central axis directions, and the flaw detection of the test object is performed based on the change of the magnetic field detected by the detecting means. An eddy-current flaw testing device characterized in that 5. The circuit further comprises a circuit for selecting the maximum output voltage among the output voltages of the plurality of detection coils, wherein the detection means changes the magnetic field based on the output voltage selected by the circuit. The eddy current flaw detection test apparatus according to claim 4, which is configured to detect.