KR101104884B1 - Eddy current test apparatus and method for processing eddy current - Google Patents

Abstract

An eddy current inspection apparatus and an eddy current processing method are disclosed. According to an embodiment of the present invention, an eddy current inspection apparatus including a transducer coil, the apparatus comprising: an input unit configured to receive an eddy current input signal generated by the transducer coil; A noise removing unit for removing and amplifying a noise signal from the eddy current input signal to generate an eddy current correction signal; A signal generator configured to generate an injection signal for correcting an impedance imbalance signal included in the eddy current correction signal; And a correction unit for correcting the impedance imbalance signal included in the eddy current correction signal using the injection signal to generate an eddy current flaw detection signal.

Description

Eddy CURRENT TEST APPARATUS AND METHOD FOR PROCESSING EDDY CURRENT}

The present invention relates to an eddy current inspection apparatus, and in particular, the present invention relates to an eddy current inspection apparatus and an eddy current processing method.

When the conductor is close to the coil through which the alternating current flows, the magnetic field generated around the coil is applied to the conductor. Since the magnetic field of the coil is generated by alternating current, the direction of the magnetic flux passing through the conductor changes with time. At this time, the conductor generates an electromotive force to prevent the change of the magnetic flux through the conductor. This phenomenon is called electromagnetic induction, and the power formed in the conductor by electromotive force is called eddy current.

This eddy current is used to inspect defects such as pores or cracks inside an industrial product, internal defects of a welded part, etc. from the outside without destroying the test body, and this is called an eddy current inspection device.

In the eddy current test device, when there is a discontinuity in the test object, the size and distribution of the eddy current change.

All. The magnitude and distribution of eddy currents generated in the specimen vary with defects such as frequency, electrical conductivity, permeability, size, shape and cracking of the specimen. Therefore, the eddy current inspection apparatus can test for the presence or absence of a defect present in the test body and the material evaluation by detecting the change in the eddy current flowing through the test body.

In the eddy current test apparatus, a noise signal is generated together with the eddy current, and thus a problem that cannot accurately determine the state of the test object occurs.

However, in the conventional method of removing a signal such as a caught signal, it is necessary to manually adjust the reactance (X) / resistance (R) balance adjusting resistor to adjust the coil impedance balance, and to check that the peripheral device is correctly balanced. Is needed. In the conventional case, an external signal needs to be injected in order to adjust the X / R balance. However, since a noise component is also injected at each injection, a signal-to-noise ratio of the signal is lowered. In addition, the conventional case requires manual manipulation of the X / R core handle to adjust the primary and secondary coil impedance balances, and a peripheral device is required to ensure that it is correct. In addition, the conventional case is not suitable for digital systems.

One embodiment of the present invention is to provide an eddy current inspection apparatus and an eddy current processing method that can adjust the impedance balance of the transducer coil.

In addition, an embodiment of the present invention is to provide an eddy current inspection apparatus and an eddy current processing method capable of nulling out a noise signal, such as a residual charge signal generated by the transducer coil, to a signal from which noise is removed.

In addition, an embodiment of the present invention to provide an eddy current inspection apparatus and eddy current processing method applicable to a digital system.

According to one aspect of the invention, there is provided an eddy current inspection device comprising a transducer coil.

According to an embodiment of the present invention, an eddy current inspection apparatus including a probe coil, comprising: an input unit configured to receive an eddy current input signal generated by the transducer coil; A noise removing unit configured to remove and amplify the noise signal from the eddy current input signal to generate an eddy current correction signal; A signal generator configured to generate an injection signal for correcting an impedance imbalance signal included in the eddy current correction signal; And a correction unit configured to correct an impedance imbalance signal included in the eddy current correction signal using the injection signal to generate an eddy current flaw detection signal.

When the injection signal is input from the signal generator, the correction unit corrects the impedance imbalance signal included in the eddy current correction signal based on the phase of the injection signal to generate the eddy current flaw detection signal.

The probe coil may include a first probe coil and a second probe coil, and the input unit may receive a first eddy current input signal from the first probe coil and a second eddy current input signal from the second probe coil. Receive.

The noise removing unit may compare the first eddy current input signal and the second eddy current input signal to distinguish a first in phase signal from a first differential signal, and cancel a noise signal that is the first in phase signal. A first current amplifier for amplifying the first differential signal to generate an eddy current amplification signal; And comparing the eddy current input signal of the first eddy current input signal and the second eddy current input signal with the eddy current amplifying signal to distinguish the second in-phase signal from the second differential signal, and determine a noise signal as the second in-phase signal. And a second current amplifier configured to cancel and generate the eddy current correction signal by amplifying the second differential signal.

The signal generator may include a voltage generator configured to generate a voltage signal; A conversion unit converting the voltage signal to generate a DC conversion signal that is an analog signal; And a signal amplifier for amplifying the DC conversion signal to generate an injection signal.

Here, when the input unit receives the eddy current input signal from the transducer coil, the input unit selects a mode according to the type of the transducer coil to generate mode selection information.

In addition, according to an aspect of the present invention, there is provided a method in which the eddy current inspection apparatus processes the eddy current.

According to an embodiment of the present invention, a method for processing an eddy current by the eddy current inspection device, the method comprising the steps of receiving the first and second eddy current input signal from each of the first and second transducer coil; Generating an eddy current correction signal by removing and amplifying a noise signal from the first and second eddy current input signals; Generating an injection signal for correcting an impedance imbalance signal included in the eddy current correction signal; And generating an eddy current flaw detection signal by correcting an impedance imbalance signal included in the eddy current correction signal using the injection signal.

Here, using the injection signal to correct the impedance imbalance signal included in the eddy current correction signal to generate an eddy current flaw detection signal, the eddy current correction signal including the impedance imbalance signal based on the phase of the injection signal Compensating the origin to generate the eddy current flaw detection signal.

The generating of the eddy current correcting signal by removing and amplifying the noise signal from the first and second eddy current input signals may include the first eddy current input signal and the in-phase noise signal included in the second eddy current input signal. Canceling and amplifying the differential signal to produce an eddy current amplified signal; And canceling an eddy current input signal of the first eddy current input signal and the second eddy current input signal and a noise signal which is in phase included in the eddy current amplifying signal, and amplifying the differential signal to generate the eddy current correcting signal. It includes.

On the other hand, generating the injection signal for correcting the impedance imbalance signal included in the eddy current correction signal, the voltage generator for generating a voltage signal; Converting the voltage signal to generate a DC conversion signal that is an analog signal; And amplifying the DC conversion signal to generate an injection signal.

The eddy current processing method may further include receiving the first and second eddy current input signals from the first and second probe coils, respectively, by using the first and second eddy current input signals. The method may further include generating mode selection information by selecting a mode according to the type of the probe coil.

The eddy current inspection apparatus and the eddy current processing method according to the embodiment of the present invention can adjust the impedance balance of the transducer coil.

In addition, the eddy current inspection apparatus and the eddy current processing method according to an embodiment of the present invention can be applied to a digital system to automatically remove the noise signal included in the eddy current.

In addition, the eddy current inspection apparatus and the eddy current processing method according to an embodiment of the present invention can improve the reliability of the result of inspecting the test object by removing the noise signal flowing through the transducer coil.

In addition, the eddy current inspection apparatus and the eddy current processing method according to an embodiment of the present invention can simplify the circuit configuration to minimize the board area and the number of parts used.

1 is a block diagram showing an eddy current inspection apparatus according to an embodiment of the present invention.
2 is an exemplary view showing a circuit configuration of an eddy current inspection device according to an embodiment of the present invention.
3 is a flowchart illustrating an eddy current processing method for processing an eddy current according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Hereinafter, embodiments of the eddy current inspection apparatus and the eddy current processing method according to the present invention will be described in detail with reference to the accompanying drawings, in the description with reference to the accompanying drawings, the same or corresponding components are given the same reference numeral Duplicate description thereof will be omitted.

An eddy current inspection apparatus according to an embodiment of the present invention will be described with reference to FIG. 1.

1 is a block diagram showing an eddy current inspection apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the eddy current inspection apparatus 100 includes a transducer coil 110, an input unit 150, a noise removing unit 170, a signal generator 210, and a correction unit 260.

When the eddy current inspection device 100 contacts a conductor with the transducer coil 110, a magnetic field is generated around the transducer coil 110, and the magnetic field acts on the conductor. Since the magnetic field of the transducer coil 110 is generated by alternating current, the direction of the magnetic flux passing through the conductor changes with time. At this time, the conductor generates an electromotive force to interfere with the change of the magnetic flux through the conductor, which is called electromagnetic induction. The conductor generates an eddy current input signal that is an alternating current by this electromotive force.

The transducer coil 110 includes a first transducer coil 120 and a second transducer coil 130. That is, the first transducer coil 110 generates the first eddy current input signal by the conductor and outputs the first eddy current input signal to the input unit 150. The second probe coil 130 generates a second eddy current input signal by the conductor, and outputs a second eddy current input signal to the input unit 150.

The input unit 150 is electrically connected to the transducer coil 110. The input unit 150 receives an eddy current input signal from the transducer coil 110. In other words, the input unit 150 receives the first eddy current input signal from the first transducer coil 110 and receives the second eddy current input signal from the second eddy current coil. The input unit 150 outputs the first eddy current input signal and the second eddy current input signal received from each of the first and second transducer coils 120 and 130 to the noise removing unit 170.

When the input unit 150 receives the first eddy current input signal and the second eddy current input signal from each of the first and second probe coils 110 and 130, the mode is selected according to the type of the probe coil 110. To generate mode selection information. In this case, the input unit 150 may generate mode selection information by selecting a mode according to the type of the probe coil 110 by a control device (not shown) that controls the operation of the eddy current inspection apparatus 100. The reason for selecting the mode according to the type of the probe coil 110 is different because the criterion for determining the eddy current is different according to the type of the probe coil 110 so as to display a type (not shown) of the type of the probe coil 110 to the user. This is to inform you through.

The noise removing unit 170 removes and amplifies the noise signals included in the first eddy current input signal and the second eddy current input signal received from the input unit 150 to generate an eddy current correction signal. The noise removing unit 170 includes a first current amplifier 180 and a second current amplifier 190.

The first current amplifying unit 180 receives a first eddy current input signal and a second eddy current input signal which are in a differential state from the input unit 150. The first current amplifier 180 distinguishes the first differential signal from the first in-phase signal by comparing the first eddy current input signal with the second eddy current input signal. The first current amplifier 180 removes the first in phase signal from the first eddy current input signal and the second eddy current input signal, and amplifies the first differential signal from the first eddy current input signal and the second eddy current input signal to amplify the eddy current. Generate a signal.

The second current amplifier 190 receives an eddy current amplification signal from the first current amplifier 180, and inputs at least one eddy current input signal of the first and second eddy current input signals from the input unit 150. Receive. The second current amplifier 190 distinguishes the second differential signal from the second in phase signal by comparing the eddy current input signal received from the input unit 150 with the eddy current amplification signal. The second current amplifier 190 removes the second in-phase signal from the eddy current input signal and the eddy current amplified signal received from the input unit 150, and amplifies the second differential signal to generate an eddy current correction signal.

Each of the first current amplifier 180 and the second current amplifier 190 may include an operational amplifier (Op amp).

The signal generator 210 generates the injection signal necessary for operating the correction unit 260 and correcting the impedance imbalance signal included in the eddy current correction signal. To this end, the signal generator 210 includes a voltage generator 220, a converter 230, and a signal amplifier 240.

The voltage generator 220 generates a voltage signal for correcting the impedance imbalance signal included in the eddy current correction signal. In this case, the voltage signal may be a digital signal.

The converter 230 generates a DC conversion signal by converting the voltage signal. In other words, the converter 230 receives a voltage signal from the voltage generator 220. The conversion unit 230 converts the voltage signal, which is a digital signal, into a DC conversion signal, which is an analog signal. The converter 230 outputs the generated DC conversion signal to the signal amplifier 240. In this case, the converter 230 may be a digital-to-analog converter (DAC).

The signal amplifier 240 amplifies the DC conversion signal to generate an injection signal. That is, the signal amplifier 240 is connected to the converter 230 and receives a DC conversion signal from the converter 230. The signal amplifier 240 generates an injection signal by amplifying the DC conversion signal to operate the corrector 260. Here, the injection signal may be a start signal for operating the corrector 260.

The correction unit 260 corrects the impedance imbalance signal included in the eddy current correction signal using the injection signal to generate the eddy current flaw detection signal. In other words, the correction unit 260 starts operation when the injection signal is input from the signal generator 210, and generates an eddy current flaw detection signal by correcting the origin of the eddy current correction signal including the impedance imbalance signal based on the injection signal. . That is, the correction unit 260 generates an eddy current flaw detection signal by correcting an eddy current correction signal having a Lissajous form based on the phase of the injection signal which is a DC signal. In this case, the correction unit 260 may be an analog multiplier pulse sensitive detector.

3 shows an eddy current processing method according to an embodiment of the present invention with reference to FIG.

2 is an exemplary view showing the configuration of a circuit of the eddy current inspection apparatus according to an embodiment of the present invention, Figure 3 is a flow chart showing an eddy current processing method for processing the eddy current according to an embodiment of the present invention.

2 and 3, the eddy current inspection apparatus 100 receives an eddy current input signal from the transducer coil 110 (S310). That is, the input unit 150 of the eddy current inspection apparatus 100 receives an eddy current input signal from the first probe coil 110, and receives a second eddy current input signal from the second probe coil 130. The input unit 150 outputs the first eddy current input signal and the second eddy current input signal to the noise removing unit 170. On the other hand, the input unit 150 may include a resistor connected in parallel as shown in Figure 2 for matching the input impedance. In this case, the resistance may be 10KΩ.

The input unit 150 generates mode selection information by selecting a mode according to the type of the probe coil 110 using the first eddy current input signal and the second eddy current input signal from the probe coil 110. For example, the input unit 150 uses a switch to switch one of a differential coil, a drive pickup coil, and a differential drive pickup coil according to the transducer coil 110. Can be selected to generate mode selection information.

The eddy current inspection apparatus 100 generates an eddy current amplifying signal by removing and amplifying a noise signal from the first eddy current input signal and the second eddy current input signal (S320). In detail, the first current amplifier 180 of the eddy current inspection apparatus 100 receives a first eddy current input signal and a second eddy current input signal in a differential state from the input unit 150. The first current amplifier 180 removes the noise signal corresponding to the first in phase signal from the first eddy current input signal and the second eddy current input signal, and removes the first differential signal from the first eddy current input signal and the second eddy current input signal. The eddy current amplification signal is generated by amplifying the small signal corresponding to the micro volts. In this case, the noise signal may be at least one of thermal variation, external electro-magnetic interference, and residual carrier signal due to the current flowing through the transducer coil 110.

The eddy current inspection apparatus 100 generates an eddy current correction signal from one eddy current input signal and an eddy current amplification signal among the first eddy current input signal and the second eddy current input signal (S330). In other words, the second current amplifier 190 of the eddy current inspection apparatus 100 receives the eddy current amplification signal from the first current amplifier 180 as shown in FIG. 2, and the second eddy current from the input unit 150. Receive an input signal. The second current amplifier 190 removes a noise signal corresponding to the first in phase signal from the second eddy current input signal and the eddy current amplification signal, and amplifies the second differential signal from the second eddy current input signal and the eddy current amplification signal. To generate an eddy current correction signal.

Therefore, after the eddy current inspection apparatus 100 according to an embodiment of the present invention removes the noise signal from the first current amplifier 180, the eddy current amplification signal from which the noise signal has been removed is again returned to the second current amplifier 190. Since the noise signal is removed once, the noise signal can be removed twice, thereby improving the reliability of the eddy current signal.

In FIG. 2, an example in which the second eddy current input signal and the eddy current amplifying signal are compared to remove and amplify the noise signal has been described as an example. However, the present disclosure is not limited thereto. You may.

The eddy current inspection apparatus 100 generates a voltage signal (S340). That is, the voltage generator 220 of the eddy current inspection apparatus 100 generates a voltage signal as a reference to correct the impedance imbalance signal included in the eddy current correction signal. The voltage generator 220 is connected to the converter 230 and outputs a voltage signal to the converter 230. In this case, the magnitude of the voltage signal may be set differently according to the type of the converter 230. For example, as illustrated in FIG. 2, the voltage generator 220 may generate a voltage signal corresponding to between + 5V and −5V, which is a reference voltage of the 12-bit DAC included in the converter 230.

The eddy current inspection apparatus 100 generates a DC conversion signal by converting the voltage signal (S350). In other words, the converter 230 of the eddy current inspection apparatus 100 converts the voltage signal, which is a digital signal, to generate a DC conversion signal having an analog signal and having a DC level. For example, the converter 230 may generate a DC conversion signal by applying a voltage signal between + 5V and -5V received from the voltage generator 220 in 1.2mV steps.

The eddy current inspection apparatus 100 generates an injection signal by converting the DC conversion signal (S360). In detail, the signal amplifier 240 of the eddy current inspection apparatus 100 generates an injection signal by amplifying the DC conversion signal to output to the correction unit 260. For example, the signal amplifier 240 may generate an injection signal between + 7.5V and -7.5V by amplifying the DC conversion signal between + 5V and -5V by 1.5 times.

The eddy current inspection apparatus 100 generates an eddy current flaw detection signal by correcting an impedance imbalance signal included in the eddy current correction signal using the injection signal (S370). In other words, the correction unit 260 of the eddy current test apparatus 100 operates to correct the impedance imbalance signal when the injection signal, which is the start signal, is received because the impedance bobble signal is also a noise signal. The correction unit 260 generates an eddy current flaw detection signal by correcting the origin of the eddy current correction signal including the impedance imbalance signal based on the injection signal. That is, since the injection signal has a DC level, the correction unit 260 generates an eddy current flaw detection signal by correcting an eddy current correction signal including an impedance imbalance signal based on the phase of the injection signal. Accordingly, the eddy current inspection apparatus 100 according to an embodiment of the present invention, the thermal variation (external electro-magnetic interference), residual charge signal due to the current flowing through the transducer coil 110 The test specimen is inspected using the eddy current flaw detection signal which removes the residual carrier signal and the impedance imbalance signal, thereby accurately measuring the crack of the specimen and the internal defect of the weld.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

120, 130: transducer coil
150:
170: noise removing unit
180, 190: current amplifier
210: signal generator
220: voltage generator
230: converter
240: signal amplifier
260: correction unit

Claims (11)

In the eddy current inspection device comprising a probe coil,
An input unit configured to receive an eddy current input signal generated by the transducer coil;
A noise removing unit configured to remove and amplify the noise signal from the eddy current input signal to generate an eddy current correction signal;
A signal generator configured to generate an injection signal for correcting an impedance imbalance signal included in the eddy current correction signal; And
And a correction unit configured to correct an impedance imbalance signal included in the eddy current correction signal using the injection signal to generate an eddy current flaw detection signal.
The method of claim 1,
Wherein,
And receiving the injection signal from the signal generator to generate the eddy current flaw detection signal by correcting the impedance imbalance signal included in the eddy current correction signal based on the phase of the injection signal.
3. The method according to claim 1 or 2,
The transducer coil includes a first transducer coil and a second transducer coil,
The input unit,
And a first eddy current input signal from the first probe coil, and a second eddy current input signal from the second probe coil.
The method of claim 3, wherein
The noise removing unit,
Comparing the first eddy current input signal and the second eddy current input signal to distinguish the first in-phase signal and the first differential signal, cancel the noise signal that is the first in-phase signal, and amplify the first differential signal to eddy current A first current amplifier configured to generate an amplified signal; And
The eddy current input signal of the first eddy current input signal and the second eddy current input signal and the eddy current amplifying signal are compared to distinguish the second in-phase signal from the second differential signal, and cancel the noise signal that is the second in-phase signal. And a second current amplifier configured to amplify the second differential signal to generate the eddy current correcting signal.
3. The method according to claim 1 or 2,
The signal generator,
A voltage generator configured to generate a voltage signal;
A conversion unit converting the voltage signal to generate a DC conversion signal that is an analog signal; And
And a signal amplifier for amplifying the DC conversion signal to generate an injection signal.
3. The method according to claim 1 or 2,
The input unit,
And a mode selection information is generated according to the type of the probe coil to generate mode selection information when the eddy current input signal is received from the probe coil.
In the method in which the eddy current inspection device processes the eddy current,
Receiving first and second eddy current input signals from each of the first and second transducer coils;
Generating an eddy current correction signal by removing and amplifying a noise signal from the first and second eddy current input signals;
Generating an injection signal for correcting an impedance imbalance signal included in the eddy current correction signal; And
And generating an eddy current flaw detection signal by correcting an impedance imbalance signal included in the eddy current correction signal using the injection signal.
The method of claim 7, wherein
Compensating the impedance imbalance signal included in the eddy current correction signal using the injection signal to generate an eddy current flaw detection signal,
And generating the eddy current flaw detection signal by correcting an origin of the eddy current correction signal including the impedance imbalance signal based on the phase of the injection signal.
The method according to claim 7 or 8,
Generating an eddy current correction signal by removing and amplifying a noise signal from the first and second eddy current input signals,
Canceling the noise signal, which is in phase, included in the first eddy current input signal and the second eddy current input signal, and amplifying the differential signal to generate an eddy current amplifying signal; And
Canceling the eddy current input signal of the first eddy current input signal and the second eddy current input signal and the noise signal in phase included in the eddy current amplifying signal, and amplifying the differential signal to generate the eddy current correcting signal. Eddy current processing method comprising a.
The method according to claim 7 or 8,
Generating an injection signal for correcting the impedance imbalance signal included in the eddy current correction signal,
Generating a voltage signal;
Converting the voltage signal to generate a DC conversion signal that is an analog signal; And
And amplifying the DC conversion signal to generate an injection signal.
The method according to claim 7 or 8,
After receiving the first and second eddy current input signals from each of the first and second transducer coils,
And generating mode selection information by selecting a mode according to the type of the first and second probe coils using the first and second eddy current input signals.

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