Nothing Special   »   [go: up one dir, main page]

WO2019077778A1 - Eddy-current flaw testing method and eddy-current flaw testing device - Google Patents

Eddy-current flaw testing method and eddy-current flaw testing device Download PDF

Info

Publication number
WO2019077778A1
WO2019077778A1 PCT/JP2018/013244 JP2018013244W WO2019077778A1 WO 2019077778 A1 WO2019077778 A1 WO 2019077778A1 JP 2018013244 W JP2018013244 W JP 2018013244W WO 2019077778 A1 WO2019077778 A1 WO 2019077778A1
Authority
WO
WIPO (PCT)
Prior art keywords
component
magnetic
imaginary
eddy current
phase component
Prior art date
Application number
PCT/JP2018/013244
Other languages
French (fr)
Japanese (ja)
Inventor
塚田　啓二
Original Assignee
国立大学法人 岡山大学
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 国立大学法人 岡山大学 filed Critical 国立大学法人 岡山大学
Priority to JP2019549104A priority Critical patent/JP6826739B2/en
Publication of WO2019077778A1 publication Critical patent/WO2019077778A1/en

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
    • G01N27/90—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws using eddy currents

Definitions

  • an eddy current flaw detection method and an eddy current flaw detection method for detecting a magnetic field produced by an eddy current generated in a subject by applying an alternating magnetic field to the subject with a magnetic sensor to detect defects in the subject It relates to the device.
  • the eddy current flaw detection method is a method in which an alternating current magnetic field is applied to an object to be inspected by an application coil to generate an eddy current for inspection.
  • the inspection object has a defect such as a flaw
  • the eddy current is disturbed and the magnetic field generated by the eddy current is changed.
  • a change in the magnetic field is detected by a detection coil or a magnetic sensor.
  • a magnetic field is generally applied using a circular or square application coil having a central axis in a direction perpendicular to the surface of the object to be inspected, that is, the normal direction of the object to be inspected. It is generating current. This normal direction is taken as the z axis.
  • Non-Patent Document 1 there is also a method of detecting the magnetic field generated by the eddy current generated in the inspection object using the application coil itself, but it is arranged coaxially with the application coil separately from the application coil and the same normal A method of detecting a magnetic field of a component is widely used (see, for example, Non-Patent Document 1).
  • Eddy current testing is classified as surface testing. As the reason, it is mentioned that the alternating current magnetic field which is high frequency in many cases is used for the alternating current magnetic field applied to the test object.
  • the depth to which the alternating magnetic field enters from the surface of the subject is frequency dependent, and this depth is called the skin depth.
  • the intensity of the eddy current also has frequency characteristics, and when the alternating current magnetic field applied to the inspection object is a low frequency, the intensity of the eddy current is attenuated and the magnetic field generated by the eddy current also becomes smaller.
  • the detection coil for detecting the magnetic field generated by the eddy current also has frequency characteristics, and the sensitivity decreases when the AC magnetic field applied to the test object has a low frequency. Conversely, it is known that the sensitivity of the detection coil improves as the frequency of the AC magnetic field applied to the test subject increases.
  • a high frequency alternating current magnetic field is used as an alternating current magnetic field applied to the object to be inspected, and as a result, the skin depth must be reduced, and there is a situation that only the surface of the object to be inspected can be inspected.
  • Examples of magnetic sensors used for nondestructive inspection include Hall elements, magnetoresistance elements (MR), magnetoimpedance elements (MI), and even more sensitive superconducting quantum interference elements (SQUIDs). Also, as described above, a normal coil can not obtain sufficient sensitivity at low frequencies, but it has been reported that a coil using a recent superconducting wire can obtain constant sensitivity even at low frequencies ( See, for example, Non-Patent Document 2).
  • Hall elements due to the structure of the element, the direction in which the magnetic field is detected and the physical quantity to be detected are different.
  • Hall elements, MR elements, MI elements or SQUIDs can be made very small because they are manufactured using a thin film manufacturing process.
  • a Hall element in order to obtain a large Hall effect, it is necessary to receive a magnetic field on the flat surface of the sensor chip in the element, and a relatively large area is required.
  • the SQUID since a magnetic flux, that is, a physical quantity obtained by multiplying the area by the magnetic flux density is measured using a pickup coil, a relatively large area is required, and there is a limit to miniaturization.
  • the MR element or the MI element is a sensor that can detect the magnetic flux density at a very small area of the cross section of the laminated thin film, that is, at one point, and is less affected by the miniaturization.
  • the inventor mounted a cancellation coil on a magnetic sensor disposed coaxially with the application coil that generates an applied magnetic field in the z-axis direction, and generated the applied magnetic field entering the magnetic sensor by the cancellation coil. And a method of detecting the magnetic signal in the z-axis direction from the object under test by canceling the above method (see Patent Document 3).
  • the eddy current flaw detection method is applied variously and is widely used for the inspection of a crack generated on the surface of the object to be inspected.
  • the material of the inspection object is a nonmagnetic material such as aluminum or copper
  • only the magnetic field due to the eddy current can be detected purely, so it is possible to catch the change of the magnetic field due to the eddy current whose distribution is disturbed by the crack. it can.
  • a magnetic substance such as steel
  • the generated magnetic field is detected as a signal.
  • the magnetic probe with the applied coil and the magnetic sensor it is desirable to make the magnetic probe with the applied coil and the magnetic sensor as small as possible.
  • the sensor chip constituting the MR element or the MI element can be vertically disposed because of its configuration, so the sensor chip is vertically disposed.
  • the magnetic probe can be miniaturized to the extent of the occupied area of the sensor chip placed vertically.
  • the dummy inspection object having a crack is an artificially formed slit-like flaw having a width of 1 mm and a length of 30 mm formed on the surface of a steel plate (SM material) having a thickness of 19 mm.
  • SM material steel plate
  • the application coil constituting the magnetic probe is a coil of which the innermost dimension is a square of 2.3 mm ⁇ 2.3 mm and 32 turns, and a tunnel type MR element is used as a magnetic sensor, and a tunnel type MR element Are disposed on the central axis of the application coil.
  • An alternating current of 100 Hz is supplied to the application coil to generate an alternating magnetic field.
  • the overall signal strength is large, and a change in strength occurs therein, so that the change in strength is likely to be unclear.
  • the overall signal strength is the signal associated with the magnetization of the sample body caused by applying a magnetic field to the ferromagnetic sample body. Therefore, when a low frequency magnetic field is applied to reduce the influence of the magnetization of the sample body, the signal of the eddy current generated in the sample body is also reduced, so detection of the magnetic field generated by the eddy current is performed. It is difficult.
  • the inventor of the present invention has made the present invention while conducting research and development in order to enable detection of a crack that has occurred in a subject to be inspected more accurately.
  • the magnetic sensor is a center of the application coil.
  • a magnetic field component parallel to the axis is detected, the in-phase component and the imaginary component are measured from the signal output from the magnetic sensor, and the initially set reference in-phase component and the reference imaginary component are subtracted to obtain a differential in-phase component and a differential imaginary component
  • the analysis is performed using the difference in-phase component and the difference imaginary number component to detect a crack generated in the object to be inspected.
  • the eddy current flaw detection method of the present invention is also characterized by the following points.
  • the reference in-phase component and the reference imaginary-number component are an in-phase component and an imaginary-number component measured in an area without defects in the test object, or an in-phase component and an imaginary-number component set arbitrarily.
  • the magnetic sensor is disposed between the central axis of the application coil and the coil side.
  • a magnetic probe including an applying coil and a magnetic sensor, a power supply for supplying an alternating current to the applying coil, and a component for measuring an in-phase component and an imaginary component from an output signal of the magnetic sensor
  • the magnetic sensor detects a magnetic field component parallel to the central axis of the applied coil.
  • the analyzer subtracts the initially set reference in-phase component and reference imaginary number component from the in-phase component and imaginary number component obtained by the component measuring instrument to obtain a difference in-phase component and a difference imaginary component, and the difference in-phase component and the difference imaginary number component
  • the analysis is performed using
  • the eddy current flaw detector according to the present invention is characterized by the following points.
  • the reference in-phase component and the reference imaginary-number component are an in-phase component and an imaginary-number component measured in an area without defects in the test object, or an in-phase component and an imaginary-number component set arbitrarily.
  • the magnetic sensor is disposed between the central axis of the application coil and the coil side to detect a magnetic field component parallel to the central axis.
  • the magnetic probe should be provided with a plurality of magnetic sensors.
  • the magnetic sensors are arranged symmetrically with respect to a plane of symmetry including the central axis of the application coil. (5) Attaching a plurality of magnetic probes to an adapter capable of detachably attaching a magnetic probe.
  • the present invention by subtracting the in-phase component and the imaginary component measured in a sound region without cracks in advance or the in-phase component and the imaginary component arbitrarily set from the measured in-phase component and the imaginary component, The influence of the magnetization signal of the ferromagnetic material can be reduced to extract the signal change due to the crack.
  • the eddy current flaw detector according to the present invention includes a magnetic probe 2-1 provided with an applying coil and a magnetic sensor, and a magnetic sensor for adjusting a signal output from the magnetic sensor of the magnetic probe 2-1. And analysis using the in-phase component and the imaginary-number component detected by the lock-in amplifier 6 as a component measuring instrument for measuring the in-phase component and the imaginary number component from the output signal of the And a power supply 8 for supplying an alternating current to the application coil of the magnetic probe 2-1.
  • the magnetic sensor circuit 5 may be combined with the lock-in amplifier 6 to form a component measuring instrument.
  • reference numeral 9 denotes a test object, and for convenience of explanation, the flat test object 9 is positioned on the XY plane, and the normal direction of the test object 9 is the Z axis direction. .
  • the magnetic sensor detects a magnetic field component parallel to the central axis of the application coil.
  • a magnetic sensor a tunnel type MR element, an anisotropic MR element, a giant MR element, an MI element or the like can be used.
  • a tunnel MR element is used.
  • the central axis of the application coil is parallel to the Z axis.
  • the power supply 8 for supplying an alternating current to the application coil inputs information such as the frequency of the supplied alternating current to the lock-in amplifier 6, and the lock-in amplifier 6 receives the information from the magnetic sensor circuit 5 based on the input information.
  • the input signal is detected to measure the in-phase component and the imaginary component.
  • the in-phase component and the imaginary component may be specified by performing fast Fourier transform on the output signal of the magnetic sensor circuit 5 with the analyzer 7 instead of using the lock-in amplifier 6.
  • the analyzer 7 is a personal computer in the present embodiment, and subtracts the initially set reference in-phase component and reference imaginary number component from the in-phase component and the imaginary number component obtained by the lock-in amplifier 6 and subtracts the in-phase component and the difference imaginary component. And the analysis is performed using the differential in-phase component and the differential imaginary component.
  • the initially set reference in-phase component and the reference imaginary component are stored in advance in a predetermined storage area of the analyzer 7.
  • the reference in-phase component and the reference imaginary-number component can use the in-phase component and the imaginary-number component measured in an area without defects in the test object, and the test object as an initial setting mode at the beginning of the inspection by the eddy current flaw detector.
  • the in-phase component and the imaginary-number component measured in the region where there is no defect can be measured and set. Alternatively, it may be an in-phase component and an imaginary component which are arbitrarily set.
  • the dummy test object described in the above-mentioned [Problems to be solved by the invention] that is, a steel plate (SM material) having a thickness of 19 mm, which simulates a crack on the surface of this steel plate
  • the eddy current flaw detection method of the present invention will be described using a dummy inspection object having a slit-like flaw formed therein and having a width of 1 mm and a length of 30 mm.
  • the first in-phase component and the reference imaginary component are initially determined using the first measurement data of the line scanning.
  • the reference in-phase component and the reference imaginary component are subtracted from the in-phase component and the imaginary component of the measurement data obtained by measurement thereafter to obtain a difference in-phase component and a difference imaginary component.
  • a graph of signal strength obtained using this differential in-phase component and differential imaginary-number component is as shown in FIG.
  • the signal intensity increases when approaching a flaw existing at a position of 15 mm on the horizontal axis of FIG. 2, and the signal returns to the baseline immediately above the flaw.
  • the signal strength increases with distance from the wound and then decays back to the baseline.
  • the influence of the magnetization signal of the ferromagnetic material can be reduced and the signal change caused by the flaw can be extracted. . That is, reliable detection of a flaw can be enabled.
  • the change in the signal indicating the presence of a flaw is a wide change of about 20 mm, and the signal returns near the signal strength of the original baseline immediately above the flaw.
  • the magnetic sensor In the measurement of the signal intensity at which the graph of FIG. 2 was obtained, in the magnetic probe, the magnetic sensor was disposed on the central axis of the application coil. On the other hand, as shown in FIG. 3, the magnetic sensor was removed from the central axis of the application coil and disposed between the central axis of the application coil 1-1 and the coil side.
  • the coil side is a part of a coil forming a closed loop.
  • the application coil 1-1 is disposed on the tip end side of the magnetic probe 2-1 as a coil with 30 turns, with the innermost dimension being a square of 7 mm ⁇ 2.3 mm.
  • the application coil 1-1 is connected to the power supply 8 through appropriate wiring.
  • the shape of the application coil 1-1 may not be a square, but may be a circle or an ellipse, as long as it has a closed loop shape.
  • the magnetic sensor 4-1 is a tunnel type MR element in this embodiment, and is located at a position away from the central axis of the application coil 1-1, preferably at a distance from the central axis of the application coil 1-1 to the coil side. It is better to separate by 1/2 or more.
  • the magnetic sensor 4-1 is mounted on the magnetic sensor mounting substrate 3-1 and disposed in the magnetic probe 2-1.
  • reference symbol S-1 denotes a socket for connecting the magnetic sensor mounting substrate 3-1 and the sensor wiring T-1.
  • the sensor wiring T-1 is connected to the magnetic sensor circuit 5 via an appropriate wiring.
  • FIG. 4 shows a graph of signal intensity obtained by performing line scanning on a dummy test object using the magnetic probe 2-1 configured as shown in FIG.
  • the reference in-phase component and the reference imaginary-number component are initialized using measurement data of the first point of line scanning.
  • an alternating current of 100 Hz is supplied to the applying coil 1-1 to generate an alternating magnetic field.
  • the magnetic sensors 4-2 and 4-3 can be disposed symmetrically with respect to a plane of symmetry including the central axis of the application coil 1-2.
  • the application coil 1-2 is disposed on the tip side of the magnetic probe 2-2 as a coil having 30 turns, with the innermost dimension being a square of 7 mm ⁇ 2.3 mm.
  • the application coil 1-2 is connected to the power supply 8 via appropriate wiring.
  • the shape of the application coil 1-2 may not be a square, but may be a circle or an ellipse, as long as it has a closed loop shape.
  • the magnetic sensors 4-2 and 4-3 are tunnel type MR elements in the present embodiment, and positions away from the central axis of the applying coil 1-2, desirably, the coil axis of the applying coil 1-2 Of the distance up to a half of the distance up to and including the central axis of the application coil 1-2 as a symmetry plane, and in particular, arranged symmetrically about the center axis of the application coil 1-2 as a symmetry axis ing.
  • the two magnetic sensors 4-2 and 4-3 are separated by about 5 mm.
  • the magnetic sensors 4-2 and 4-3 are mounted on the magnetic sensor mounting boards 3-2 and 3-3, respectively, and disposed in the magnetic probe 2-2.
  • reference symbol S-2 denotes a socket for connecting the magnetic sensor mounting substrate 3-2 and the sensor wiring T-2
  • reference symbol S-3 denotes the magnetic sensor mounting substrate 3-3 and the sensor wiring T. It is a socket that connects -3.
  • the sensor wires T-2 and T-3 are connected to the magnetic sensor circuit 5 through appropriate wires.
  • FIG. 6 shows a graph of signal intensity obtained by performing line scanning on a dummy test object using the magnetic probe 2-2 configured as shown in FIG.
  • the reference in-phase component and the reference imaginary-number component are initialized using measurement data of the first point of line scanning. Further, an alternating current of 100 Hz is supplied to the application coil 1-2 to generate an alternating magnetic field.
  • the two magnetic sensors 4-2 and 4-3 give exactly the same result, and one signal peak obtained by the flaw existing at the position of 15 mm on the horizontal axis. Is steep, and a half width of about 2.5 mm is obtained.
  • the two magnetic sensors 4-2 and 4-3 are separated by about 5 mm, the two peaks shown in FIG. 6 are separated by about 5 mm. Since the half width is smaller than the distance between the magnetic sensors 4-2 and 4-3, it indicates that a crack can be detected independently when line scanning is performed. This result indicates that even if two or more scratches are present in close proximity, they can be separated and detected clearly if they are separated by a half width of 2.5 mm or more.
  • the size of the magnetic probe in the eddy current flaw detector according to the present invention is regulated by the size of the applied coil, in order to realize a two-channel magnetic probe, the combination of one applied coil and one magnetic sensor is dare Instead of providing two magnetic sensor probes to form two channels, as shown in FIG. 5, two channels can be realized by one applied coil and two magnetic sensors to realize a small magnetic probe.
  • the magnetic sensors 4-2 and 4-3 disposed symmetrically with respect to the plane of symmetry including the central axis of the applying coil 1-2 are the two magnetic sensors 4-2, 4-3, the central axis of the application coil 1-2 is positioned and arranged, but as a modified example, as shown in FIG. 7, for example, in the plane of symmetry including the central axis of the application coil 1-3.
  • Two magnetic sensors 4-4 and 4-5 may be disposed symmetrically to each other.
  • the application coil 1-3 is disposed on the tip side of the magnetic probe 2-3 as a 30-turn coil with an innermost dimension of 7 mm ⁇ 2.3 mm.
  • the application coil 1-3 is connected to the power supply 8 through appropriate wiring.
  • the shape of the application coil 1-3 may not be a square, but may be a circle or an ellipse, as long as it has a closed loop shape.
  • the magnetic sensors 4-4 and 4-5 are also tunnel type MR elements in this embodiment, and the position away from the central axis of the application coil 1-3, desirably, the coil of the central axis of the application coil 1-2 A plane which is half or more of the distance to the side and which includes the central axis of the application coil 1-3 is arranged as a plane of symmetry.
  • the central axis of the application coil 1-3 is not located between the two magnetic sensors 4-4 and 4-5.
  • the magnetic sensors 4-4 and 4-5 are mounted on the magnetic sensor mounting boards 3-4 and 3-5, respectively, and disposed in the magnetic probe 2-3.
  • reference symbol S-4 denotes a socket for connecting the magnetic sensor mounting substrate 3-4 and the sensor wiring T-4
  • reference symbol S-5 denotes the magnetic sensor mounting substrate 3-5 and the sensor wiring T. It is a socket to connect with -5.
  • the sensor wires T-4 and T-5 are connected to the magnetic sensor circuit 5 through appropriate wires.
  • FIG. 8 shows a graph of signal intensity obtained by performing line scanning on a dummy test object using the magnetic probe 2-3 configured as shown in FIG.
  • two magnetic sensors 4-4 and 4-5 are used instead of using the in-phase component and the imaginary component obtained from the first measurement data of line scanning as the reference in-phase component and the reference imaginary component.
  • a reference in-phase component and a reference imaginary-number component obtained from the other magnetic sensor are used as the in-phase component and the imaginary-number component. That is, by subtracting the in-phase component and the imaginary component of the magnetic signal obtained by each of the magnetic sensors 4-4 and 4-5, the differential in-phase component and the differential imaginary component are measured.
  • the magnetic sensors 4-4 and 4-5 are adjacent to each other, so that measuring the differential in-phase component and the differential imaginary component yields a signal close to a differential signal.
  • the magnetic sensors 4-4 and 4-5 are adjacent to each other, so that measuring the differential in-phase component and the differential imaginary component yields a signal close to a differential signal.
  • an appropriate adapter is provided so that line scanning of the magnetic probe can be performed stably.
  • a magnetic probe may be attached to the operation arm and used.
  • FIG. 10 the case where it uses for the test
  • a steel floor plate 11 is laid below the pavement surface of the road, and a steel U-rib 12 is welded to the lower surface of the steel floor plate 11 to form a support structure.
  • a crack is likely to be generated in the welded portion 13 welding the U-rib 12 and the steel floor plate 11 due to the vibration caused by the movement of the load.
  • the weld bead in the weld portion 13 has a width, with only one magnetic probe, the area of the applied coil provided on the magnetic probe is small compared to the surface of the weld bead, so many times line scanning Need to do.
  • a plurality of magnetic probes 2-4, 2-5, and 2-6 can be detachably attached to the adapter 10 to which the magnetic probes are attached. , 2-5 and 2-6 at one time, the inspection time can be shortened.
  • the adapter 10 of the present embodiment has an arc-shaped base around a weld, and the magnetic probes 2-4, 2-5, and 2-6 are inserted into this base at predetermined intervals in the circumferential direction. Through holes are provided.
  • Each of the magnetic probes 2-4, 2-5, 2-6 can be mounted simply by inserting it into the through hole of the adapter 10. As shown in FIG. 10, the three magnetic probes 2-4, 2-5, 2 can be mounted. -6 is attached, and each of the magnetic probes 2-4, 2-5 and 2-6 is shown in FIG. Thus, a six-channel magnetic sensor array can be realized.
  • the adapter 10 is made of plastic, and the end of the adapter 10 is provided with a rolling roller R that rolls in contact with the steel floor plate 11 or the U-rib 12. It can be easily moved along the stretching direction, and line scanning can be performed stably.
  • the adapter 10 may have an appropriate shape in accordance with the shape of the inspection site, and can inspect the magnetic probe and the inspection device in various locations without changing the same.
  • the present invention can be widely used in inspections for detecting defects such as cracks occurring in metallic structures by eddy current flaw detection, and in particular steel structures that have been difficult in the past, such as bridges, buildings, factories, etc. It can be applied to inspection of structures in a wide range of fields such as plants, power generation facilities, and railways.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)

Abstract

Provided are an eddy-current flaw testing method and eddy-current flaw testing device that make it possible to reduce the amount by which inspection is influenced by the magnetization signal of a ferromagnetic object to be inspected when ascertaining cracking in a steel structure that is the object to be inspected by using a magnetic sensor to detect a magnetic field produced by eddy current occurring in the object to be inspected as a result of the application of an alternating magnetic field to the object to be inspected. In the present invention, a magnetic sensor for detecting a magnetic field component parallel to the central axis of an application coil for applying a magnetic field to the object to be inspected is disposed in a position inside the application coil and removed from the central axis thereof, the application coil is made to produce a magnetic field of a prescribed frequency, and the in-phase component and imaginary component of the magnetic signal detected by the magnetic sensor are measured. The measured in-phase component and imaginary component are subtracted from an in-phase component and imaginary component measured beforehand for a location of the object to be inspected with no flaw, and are analyzed.

Description

渦電流探傷法及び渦電流探傷装置Eddy current flaw detection method and eddy current flaw detection device
　本発明は、被検査体に交流磁場を印加することで被検査体に発生させた渦電流が作る磁場を磁気センサで検出し、被検査体の欠陥を探傷する渦電流探傷法及び渦電流探傷装置に関する。 According to the present invention, an eddy current flaw detection method and an eddy current flaw detection method for detecting a magnetic field produced by an eddy current generated in a subject by applying an alternating magnetic field to the subject with a magnetic sensor to detect defects in the subject It relates to the device.
　従来、金属製構造物の欠陥を磁気的に検査する方法として、渦電流探傷法や漏洩磁束探傷法がある。特に、渦電流探傷法は、被検査体に印加コイルにより交流磁場を印加して渦電流を発生させて検査する方法である。被検査体に傷などの欠陥がある場合には、渦電流には乱れが生じ、渦電流が作る磁場が変化する。渦電流探傷法では、この磁場の変化を検出コイルあるいは磁気センサ等で検出している。 Conventionally, as a method of magnetically inspecting a defect of a metal structure, there are an eddy current flaw detection method and a leakage flux flaw detection method. In particular, the eddy current flaw detection method is a method in which an alternating current magnetic field is applied to an object to be inspected by an application coil to generate an eddy current for inspection. When the inspection object has a defect such as a flaw, the eddy current is disturbed and the magnetic field generated by the eddy current is changed. In the eddy current flaw detection method, a change in the magnetic field is detected by a detection coil or a magnetic sensor.
　渦電流探傷法では、一般に被検査体の表面に垂直な方向、つまり被検査体の法線方向に中心軸をもつ円形や四角形の印加コイルを用いて磁場を印加して、被検査体に渦電流を発生させている。この法線方向をｚ軸とする。 In the eddy current flaw detection method, a magnetic field is generally applied using a circular or square application coil having a central axis in a direction perpendicular to the surface of the object to be inspected, that is, the normal direction of the object to be inspected. It is generating current. This normal direction is taken as the z axis.
　また、被検査体に発生させた渦電流によって生じる磁場を検出する検出コイルは、印加コイルそのものを利用する方法もあるが、印加コイルとは別に印加コイルと同軸上に配置して、同じ法線成分の磁場を検出する方法が広く用いられている（例えば非特許文献１参照）。 In addition, there is also a method of detecting the magnetic field generated by the eddy current generated in the inspection object using the application coil itself, but it is arranged coaxially with the application coil separately from the application coil and the same normal A method of detecting a magnetic field of a component is widely used (see, for example, Non-Patent Document 1).
　このほかにも様々な印加コイルと検出コイルの配置が報告されている。例えば、四角形とした検出コイルの中心軸を、印加コイルの中心軸と直交させるとともに、被検査体の表面と水平にして配置して検出する方法が報告されている（特許文献１参照）。あるいは、印加コイルの配線の一部を非検査体にできるだけ近接させて配置することで、非検査体に配線の延伸方向と同じ方向の磁場を生じさせる渦電流を発生させ、この磁場を非検査体表面に設けた磁気センサで検出する方法が報告されている（特許文献２参照）。 Various other arrangements of the application and detection coils have been reported. For example, a method has been reported in which a central axis of a rectangular detection coil is arranged orthogonal to a central axis of an application coil and arranged horizontally to the surface of a test object (see Patent Document 1). Alternatively, by arranging a part of the wiring of the applied coil as close as possible to the non-inspection body, an eddy current is generated which causes the non-inspection body to generate a magnetic field in the same direction as the extension direction of the wiring. A method of detecting with a magnetic sensor provided on the body surface has been reported (see Patent Document 2).
　渦電流探傷法は、表面探傷法に分類されている。その理由として、被検査体に印加する交流磁場に、多くの場合で高い周波数とした交流磁場を用いていることが挙げられる。交流磁場が被検査体の表面から入っていく深さには周波数依存性があり、この深さを表皮深さと呼ぶ。 Eddy current testing is classified as surface testing. As the reason, it is mentioned that the alternating current magnetic field which is high frequency in many cases is used for the alternating current magnetic field applied to the test object. The depth to which the alternating magnetic field enters from the surface of the subject is frequency dependent, and this depth is called the skin depth.
　被検査体の表面から深い領域を検査するためには、被検査体に印加する交流磁場の周波数を低くする必要がある。一方、渦電流の強さにも周波数特性があり、被検査体に印加する交流磁場を低周波とした場合には渦電流の強度が減衰し、渦電流によって発生する磁場も小さくなってくる。さらに、渦電流によって発生する磁場を検出する検出コイルにも周波数特性があり、被検査体に印加する交流磁場が低い周波数の場合では感度が減少する。逆に、被検査体に印加する交流磁場の周波数が高ければ高いほど検出コイルの感度が向上することが知られている。 In order to inspect a region deep from the surface of the object to be inspected, it is necessary to lower the frequency of the alternating magnetic field applied to the object to be inspected. On the other hand, the intensity of the eddy current also has frequency characteristics, and when the alternating current magnetic field applied to the inspection object is a low frequency, the intensity of the eddy current is attenuated and the magnetic field generated by the eddy current also becomes smaller. Furthermore, the detection coil for detecting the magnetic field generated by the eddy current also has frequency characteristics, and the sensitivity decreases when the AC magnetic field applied to the test object has a low frequency. Conversely, it is known that the sensitivity of the detection coil improves as the frequency of the AC magnetic field applied to the test subject increases.
　したがって、被検査体に印加する交流磁場としては高周波の交流磁場が用いられ、その結果として表皮深さが小さくならざるを得えず、被検査体の表面しか検査できないという状況がある。 Therefore, a high frequency alternating current magnetic field is used as an alternating current magnetic field applied to the object to be inspected, and as a result, the skin depth must be reduced, and there is a situation that only the surface of the object to be inspected can be inspected.
　そこで、低周波の印加磁場でも計測できるように、検出コイルの代わりに周波数にかかわらず磁場感度が一定的で高感度である磁気センサを用いる探傷法の開発が最近では進んできている。 Therefore, in order to measure even a low frequency applied magnetic field, development of a flaw detection method using a magnetic sensor having a constant magnetic field sensitivity regardless of frequency and high sensitivity has recently been advanced instead of a detection coil.
　非破壊検査に用いられる磁気センサとしては、ホール素子や、磁気抵抗素子(MR)、磁気インピーダンス素子(MI)、さらにはもっと高感度な超伝導量子干渉素子(SQUID)などがある。また、上述したように普通のコイルでは低周波において十分な感度が得られないが、最近の超伝導線材を用いたコイルでは、低周波でも一定の感度を得ることができることが報告されている（例えば、非特許文献２参照）。 Examples of magnetic sensors used for nondestructive inspection include Hall elements, magnetoresistance elements (MR), magnetoimpedance elements (MI), and even more sensitive superconducting quantum interference elements (SQUIDs). Also, as described above, a normal coil can not obtain sufficient sensitivity at low frequencies, but it has been reported that a coil using a recent superconducting wire can obtain constant sensitivity even at low frequencies ( See, for example, Non-Patent Document 2).
　これらの磁気センサでは、素子の構造上、磁場を検出する方向や検出する物理量が異なってくる。ホール素子、ＭＲ素子、ＭＩ素子あるいはSQUIDなどは、薄膜製造プロセスを利用して製造されるので、非常に小さくすることができる。ただし、ホール素子では、大きなホール効果を得るためには素子中のセンサチップの平面で磁場を受ける必要があり、比較的大きな面積とした領域が必要となることから、小型化には限界がある。同様に、SQUIDでは、ピックアップコイルを利用して磁束、つまり磁束密度に面積をかけた物理量を測定しているため、比較的大きな面積とした領域が必要であり、小型化には限界がある。一方、ＭＲ素子やＭＩ素子は、積層した薄膜の断面部分の非常に小さな面積、つまり一点で磁束密度を検出することができ、小型化の影響が少ないセンサである。 In these magnetic sensors, due to the structure of the element, the direction in which the magnetic field is detected and the physical quantity to be detected are different. Hall elements, MR elements, MI elements or SQUIDs can be made very small because they are manufactured using a thin film manufacturing process. However, in the case of a Hall element, in order to obtain a large Hall effect, it is necessary to receive a magnetic field on the flat surface of the sensor chip in the element, and a relatively large area is required. . Similarly, in the SQUID, since a magnetic flux, that is, a physical quantity obtained by multiplying the area by the magnetic flux density is measured using a pickup coil, a relatively large area is required, and there is a limit to miniaturization. On the other hand, the MR element or the MI element is a sensor that can detect the magnetic flux density at a very small area of the cross section of the laminated thin film, that is, at one point, and is less affected by the miniaturization.
　低周波領域まで検査できる磁気センサを用いた渦電流探傷法であっても、印加磁場の強度に比べて渦電流が作る磁場が弱いために、低周波から一定の感度を持つ磁気センサにおいて、検出する信号のほとんどが印加磁場成分となり、ＳＮが十分でないことが多い。 Even in the eddy current flaw detection method using a magnetic sensor that can inspect to the low frequency range, detection is performed in the magnetic sensor having a certain sensitivity from low frequency because the magnetic field generated by the eddy current is weaker than the strength of the applied magnetic field. Most of the signals to be detected become applied magnetic field components, and SN is often insufficient.
　そのため、本発明者は、ｚ軸方向の印加磁場を生じさせる印加コイルと同軸上に配置する磁気センサにキャンセルコイルを装着して、磁気センサに入ってくる印加磁場をキャンセルコイルで生じさせた磁場でキャンセルして、被検査体からのｚ軸方向の磁気信号を検出する方法を報告している（特許文献３参照）。 Therefore, the inventor mounted a cancellation coil on a magnetic sensor disposed coaxially with the application coil that generates an applied magnetic field in the z-axis direction, and generated the applied magnetic field entering the magnetic sensor by the cancellation coil. And a method of detecting the magnetic signal in the z-axis direction from the object under test by canceling the above method (see Patent Document 3).
　このように、渦電流探傷法は様々な工夫が施され、被検査体の表面に生じるき裂の検査に広く用いられている。特に、被検査体の材料がアルミや銅などの非磁性体の場合には、渦電流による磁場だけを純粋に検出できるので、き裂によって分布が乱れた渦電流による磁場の変化をとらえることができる。しかし、鉄鋼などの磁性体の場合には、渦電流によって発生する磁場だけでなく、磁性体の高透磁率特性に起因して被検体への印加磁場による磁化が生じることで、この磁化にともなって発生した磁場が信号として検出されるという問題があった。 As described above, the eddy current flaw detection method is applied variously and is widely used for the inspection of a crack generated on the surface of the object to be inspected. In particular, when the material of the inspection object is a nonmagnetic material such as aluminum or copper, only the magnetic field due to the eddy current can be detected purely, so it is possible to catch the change of the magnetic field due to the eddy current whose distribution is disturbed by the crack. it can. However, in the case of a magnetic substance such as steel, not only the magnetic field generated by the eddy current but also the magnetization due to the magnetic field applied to the object due to the high permeability characteristic of the magnetic substance There is a problem that the generated magnetic field is detected as a signal.
　この問題を解決するためには、印加コイルと磁気センサを備えた磁気プローブを、できるだけ小さくすることが望ましい。特に、磁気センサとしてＭＲ素子やＭＩ素子を用いた場合には、その構成上、ＭＲ素子やＭＩ素子を構成しているセンサチップを縦置きに配置できることから、センサチップを縦置きとすることで縦置きとしたセンサチップの占有面積の程度まで磁気プローブを小型化することができる。 In order to solve this problem, it is desirable to make the magnetic probe with the applied coil and the magnetic sensor as small as possible. In particular, when an MR element or an MI element is used as a magnetic sensor, the sensor chip constituting the MR element or the MI element can be vertically disposed because of its configuration, so the sensor chip is vertically disposed. The magnetic probe can be miniaturized to the extent of the occupied area of the sensor chip placed vertically.
特開２００５－１６４４４２号公報JP, 2005-164442, A 特開平１０－２３９２８３号公報Japanese Patent Application Laid-Open No. 10-239283 特開２００６－０３０００４号公報JP, 2006-030004, A
　き裂を有するダミー被検査体として、厚さ19mmの鋼板(ＳＭ材)の表面に、幅1mm、長さ30mmの貫通したスリット状の傷を人工的に形成したものを用い、このダミー被検査体に設けた傷を横断させて磁気プローブのラインスキャンニングを行った場合には、図１０に示す信号強度のグラフが得られる。すなわち、磁気プローブから出力された信号は、図１０の横軸の15mmの位置に設けている傷に近づくにつれて信号強度の変化が大きくなり、傷から離れるにつれて信号強度の変化が小さくなり、元の信号強度に近い強度となっている。 The dummy inspection object having a crack is an artificially formed slit-like flaw having a width of 1 mm and a length of 30 mm formed on the surface of a steel plate (SM material) having a thickness of 19 mm. When line scanning of the magnetic probe is performed by traversing a wound provided on the body, a graph of signal strength shown in FIG. 10 is obtained. That is, in the signal output from the magnetic probe, the change in signal intensity increases as it approaches the scratch provided at the position of 15 mm on the horizontal axis in FIG. 10, and the change in signal intensity decreases as it gets away from the scratch. The intensity is close to the signal intensity.
　ここで、磁気プローブを構成している印加コイルは、最内側の寸法を2.3mm×2.3mmの四角状として32巻きとしたコイルとし、磁気センサとしてはトンネル型ＭＲ素子を用い、トンネル型ＭＲ素子を印加コイルの中心軸線上に配置している。印加コイルには、100Hzの交流電流を流して交流磁場を生成している。 Here, the application coil constituting the magnetic probe is a coil of which the innermost dimension is a square of 2.3 mm × 2.3 mm and 32 turns, and a tunnel type MR element is used as a magnetic sensor, and a tunnel type MR element Are disposed on the central axis of the application coil. An alternating current of 100 Hz is supplied to the application coil to generate an alternating magnetic field.
　図１０に示すように、得られる信号では、全体の信号強度が大きく、その中での強度変化が生じることとなっているため、強度変化が不明瞭となりやすい。特に、全体の信号強度は、強磁性体であるサンプル体に磁場を印加したことによって生じるサンプル体の磁化にともなう信号である。したがって、サンプル体の磁化の影響を小さくするために低い周波数の磁場を印加することとした場合には、サンプル体に発生する渦電流の信号も小さくなるため、渦電流が生成する磁場の検出が困難となっている。 As shown in FIG. 10, in the obtained signal, the overall signal strength is large, and a change in strength occurs therein, so that the change in strength is likely to be unclear. In particular, the overall signal strength is the signal associated with the magnetization of the sample body caused by applying a magnetic field to the ferromagnetic sample body. Therefore, when a low frequency magnetic field is applied to reduce the influence of the magnetization of the sample body, the signal of the eddy current generated in the sample body is also reduced, so detection of the magnetic field generated by the eddy current is performed. It is difficult.
　本発明者は、このような現状に鑑み、より精度良く被検査体に生じたき裂の検出を可能とするために研究開発を行う中で、本発明を成すに至ったものである。 In view of such a current situation, the inventor of the present invention has made the present invention while conducting research and development in order to enable detection of a crack that has occurred in a subject to be inspected more accurately.
　本発明の渦電流探傷法では、印加コイルと磁気センサとを備えた磁気プローブで被検査体をラインスキャニングすることで被検査体を検査する渦電流探傷法において、磁気センサは、印加コイルの中心軸と平行な磁場成分を検出することとし、磁気センサから出力された信号から同相成分及び虚数成分を計測し、初期設定した基準同相成分及び基準虚数成分を差し引いて差分同相成分及び差分虚数成分として、この差分同相成分及び差分虚数成分を用いて解析を行うことで被検査体に生じたき裂を検出するものである。 In the eddy current flaw detection method of the present invention, in the eddy current flaw detection method for inspecting a subject by line scanning the subject with a magnetic probe provided with an application coil and a magnetic sensor, the magnetic sensor is a center of the application coil. A magnetic field component parallel to the axis is detected, the in-phase component and the imaginary component are measured from the signal output from the magnetic sensor, and the initially set reference in-phase component and the reference imaginary component are subtracted to obtain a differential in-phase component and a differential imaginary component The analysis is performed using the difference in-phase component and the difference imaginary number component to detect a crack generated in the object to be inspected.
　さらに、本発明の渦電流探傷法では、以下の点にも特徴を有するものである。
（１）基準同相成分及び基準虚数成分は、被検査体で欠陥がない領域で計測した同相成分及び虚数成分、あるいは任意に設定した同相成分及び虚数成分であること。
（２）磁気センサを印加コイルの中心軸とコイル辺との間に配置していること。 Furthermore, the eddy current flaw detection method of the present invention is also characterized by the following points.
(1) The reference in-phase component and the reference imaginary-number component are an in-phase component and an imaginary-number component measured in an area without defects in the test object, or an in-phase component and an imaginary-number component set arbitrarily.
(2) The magnetic sensor is disposed between the central axis of the application coil and the coil side.
　また、本発明の渦電流探傷装置では、印加コイルと磁気センサとを備えた磁気プローブと、印加コイルに交流電流を供給する電源と、磁気センサの出力信号から同相成分及び虚数成分を計測する成分計測器と、この成分計測器で得られた同相成分及び虚数成分を用いて解析を行う解析器とを有する渦電流探傷装置において、磁気センサは、印加コイルの中心軸と平行な磁場成分を検出し、解析器では、成分計測器で得られた同相成分及び虚数成分から、初期設定した基準同相成分及び基準虚数成分を差し引いて差分同相成分及び差分虚数成分とし、この差分同相成分及び差分虚数成分を用いて解析を行うものである。 Further, in the eddy current flaw detector according to the present invention, a magnetic probe including an applying coil and a magnetic sensor, a power supply for supplying an alternating current to the applying coil, and a component for measuring an in-phase component and an imaginary component from an output signal of the magnetic sensor In an eddy current flaw detector including a measuring instrument and an analyzer that performs analysis using the in-phase component and the imaginary component obtained by the component measuring instrument, the magnetic sensor detects a magnetic field component parallel to the central axis of the applied coil. The analyzer subtracts the initially set reference in-phase component and reference imaginary number component from the in-phase component and imaginary number component obtained by the component measuring instrument to obtain a difference in-phase component and a difference imaginary component, and the difference in-phase component and the difference imaginary number component The analysis is performed using
　さらに、本発明の渦電流探傷装置では、以下の点にも特徴を有するものである。
（１）基準同相成分及び基準虚数成分は、被検査体で欠陥がない領域で計測した同相成分及び虚数成分、あるいは任意に設定した同相成分及び虚数成分であること。
（２）磁気センサは、印加コイルの中心軸とコイル辺との間に配置して、中心軸と平行な磁場成分を検出すること。
（３）磁気プローブには、磁気センサを複数配設していること。
（４）印加コイルの中心軸を含む対称面に対して対称に磁気センサを配置していること。
（５）磁気プローブを着脱自在に装着可能としたアダプターに複数の磁気プローブを装着すること。 Furthermore, the eddy current flaw detector according to the present invention is characterized by the following points.
(1) The reference in-phase component and the reference imaginary-number component are an in-phase component and an imaginary-number component measured in an area without defects in the test object, or an in-phase component and an imaginary-number component set arbitrarily.
(2) The magnetic sensor is disposed between the central axis of the application coil and the coil side to detect a magnetic field component parallel to the central axis.
(3) The magnetic probe should be provided with a plurality of magnetic sensors.
(4) The magnetic sensors are arranged symmetrically with respect to a plane of symmetry including the central axis of the application coil.
(5) Attaching a plurality of magnetic probes to an adapter capable of detachably attaching a magnetic probe.
　本発明によれば、あらかじめき裂のない健全な領域で計測した同相成分と虚数成分あるいは、任意に設定した同相成分と虚数成分を初期値として、計測した同相成分と虚数成分から差し引くことにより、強磁性体の磁化信号の影響を低減してき裂による信号変化を抽出することができる。 According to the present invention, by subtracting the in-phase component and the imaginary component measured in a sound region without cracks in advance or the in-phase component and the imaginary component arbitrarily set from the measured in-phase component and the imaginary component, The influence of the magnetization signal of the ferromagnetic material can be reduced to extract the signal change due to the crack.
渦電流探傷装置の説明図である。It is explanatory drawing of an eddy current flaw detector. 本発明に係る渦電流探傷法で得られる信号強度のグラフである。It is a graph of the signal strength obtained by the eddy current flaw detection method concerning the present invention. 本発明に係る渦電流探傷装置の磁気プローブの説明図である。It is explanatory drawing of the magnetic probe of the eddy current flaw detection apparatus which concerns on this invention. 本発明に係る渦電流探傷装置でダミー被検査体をラインスキャンニングして得られた信号強度のグラフである。It is a graph of the signal strength obtained by carrying out line scanning of the dummy to-be-inspected object by the eddy current flaw detector concerning this invention. 本発明に係る渦電流探傷装置の磁気プローブの説明図である。It is explanatory drawing of the magnetic probe of the eddy current flaw detection apparatus which concerns on this invention. 本発明に係る渦電流探傷装置でダミー被検査体をラインスキャンニングして得られた信号強度のグラフである。It is a graph of the signal strength obtained by carrying out line scanning of the dummy to-be-inspected object by the eddy current flaw detector concerning this invention. 本発明に係る渦電流探傷装置の磁気プローブの説明図である。It is explanatory drawing of the magnetic probe of the eddy current flaw detection apparatus which concerns on this invention. 本発明に係る渦電流探傷装置でダミー被検査体をラインスキャンニングして得られた信号強度のグラフである。It is a graph of the signal strength obtained by carrying out line scanning of the dummy to-be-inspected object by the eddy current flaw detector concerning this invention. 本発明に係る渦電流探傷装置の磁気プローブの使用形態の説明図である。It is explanatory drawing of the usage form of the magnetic probe of the eddy current flaw detection apparatus which concerns on this invention. 従来の渦電流探傷装置でダミー被検査体をラインスキャンニングして得られた信号強度のグラフである。It is a graph of the signal strength obtained by carrying out line scanning of the dummy to-be-inspected object with the conventional eddy current flaw detector.
　本発明の渦電流探傷装置は、図１に示すように、印加コイルと磁気センサとを備えた磁気プローブ２－１と、磁気プローブ２－１の磁気センサから出力された信号を調整する磁気センサ用回路５と、磁気センサの出力信号から同相成分及び虚数成分を計測する成分計測器としてのロックインアンプ６と、ロックインアンプ６で検出された同相成分及び虚数成分を用いて解析を行う解析器７と、磁気プローブ２－１の印加コイルに交流電流を供給する電源８とを有している。なお、磁気センサ用回路５はロックインアンプ６と組み合わせて成分計測器としてもよい。図１中、符号９は、被検査体であり、説明の便宜上、平板状とした被検査体９はＸ－Ｙ平面上に位置させ、被検査体９の法線方向をＺ軸方向としている。 The eddy current flaw detector according to the present invention, as shown in FIG. 1, includes a magnetic probe 2-1 provided with an applying coil and a magnetic sensor, and a magnetic sensor for adjusting a signal output from the magnetic sensor of the magnetic probe 2-1. And analysis using the in-phase component and the imaginary-number component detected by the lock-in amplifier 6 as a component measuring instrument for measuring the in-phase component and the imaginary number component from the output signal of the And a power supply 8 for supplying an alternating current to the application coil of the magnetic probe 2-1. The magnetic sensor circuit 5 may be combined with the lock-in amplifier 6 to form a component measuring instrument. In FIG. 1, reference numeral 9 denotes a test object, and for convenience of explanation, the flat test object 9 is positioned on the XY plane, and the normal direction of the test object 9 is the Z axis direction. .
　磁気プローブ２－１の構成については、詳しくは後述するが、磁気センサは、印加コイルの中心軸と平行な磁場成分を検出することとしている。磁気センサとしては、トンネル型ＭＲ素子、異方性ＭＲ素子や巨大ＭＲ素子、ＭＩ素子等を用いることができる。本実施形態では、トンネル型ＭＲ素子を用いている。印加コイルの中心軸は、Ｚ軸と平行としている。 The configuration of the magnetic probe 2-1 will be described in detail later, but the magnetic sensor detects a magnetic field component parallel to the central axis of the application coil. As a magnetic sensor, a tunnel type MR element, an anisotropic MR element, a giant MR element, an MI element or the like can be used. In the present embodiment, a tunnel MR element is used. The central axis of the application coil is parallel to the Z axis.
　印加コイルに交流電流を供給する電源８は、供給している交流電流の周波数等の情報をロックインアンプ６に入力し、ロックインアンプ６では入力された情報に基づいて磁気センサ用回路５から入力された信号の検波を行い、同相成分及び虚数成分を計測している。なお、ロックインアンプ６を用いるのではなく、解析機７で磁気センサ用回路５の出力信号に対して高速フーリエ変換を実行して、同相成分と虚数成分を特定してもよい。 The power supply 8 for supplying an alternating current to the application coil inputs information such as the frequency of the supplied alternating current to the lock-in amplifier 6, and the lock-in amplifier 6 receives the information from the magnetic sensor circuit 5 based on the input information. The input signal is detected to measure the in-phase component and the imaginary component. The in-phase component and the imaginary component may be specified by performing fast Fourier transform on the output signal of the magnetic sensor circuit 5 with the analyzer 7 instead of using the lock-in amplifier 6.
　解析機７は、本実施形態ではパーソナルコンピュータであって、ロックインアンプ６で得られた同相成分及び虚数成分から、初期設定した基準同相成分及び基準虚数成分を差し引いて差分同相成分及び差分虚数成分とし、この差分同相成分及び差分虚数成分を用いて解析を行っている。 The analyzer 7 is a personal computer in the present embodiment, and subtracts the initially set reference in-phase component and reference imaginary number component from the in-phase component and the imaginary number component obtained by the lock-in amplifier 6 and subtracts the in-phase component and the difference imaginary component. And the analysis is performed using the differential in-phase component and the differential imaginary component.
　初期設定した基準同相成分及び基準虚数成分は、あらかじめ解析機７の所定の記憶領域に記憶させている。基準同相成分及び基準虚数成分は、被検査体で欠陥がない領域で計測した同相成分及び虚数成分を用いることができ、渦電流探傷装置による検査の開始当初に、初期設定モードとして、被検査体で欠陥がない領域で計測した同相成分及び虚数成分を計測して、設定することができる。あるいは、任意に設定した同相成分及び虚数成分とすることもできる。 The initially set reference in-phase component and the reference imaginary component are stored in advance in a predetermined storage area of the analyzer 7. The reference in-phase component and the reference imaginary-number component can use the in-phase component and the imaginary-number component measured in an area without defects in the test object, and the test object as an initial setting mode at the beginning of the inspection by the eddy current flaw detector. The in-phase component and the imaginary-number component measured in the region where there is no defect can be measured and set. Alternatively, it may be an in-phase component and an imaginary component which are arbitrarily set.
　以下において、上述の［発明が解決しようとする課題］の項で説明したダミー被検査体、すなわち、厚さ19mmの鋼板(ＳＭ材)であって、この鋼板の表面に、き裂に模した幅1mm、長さ30mmの貫通したスリット状の傷を形成したダミー被検査体を用いて、本発明の渦電流探傷法を説明する。 In the following, the dummy test object described in the above-mentioned [Problems to be solved by the invention], that is, a steel plate (SM material) having a thickness of 19 mm, which simulates a crack on the surface of this steel plate The eddy current flaw detection method of the present invention will be described using a dummy inspection object having a slit-like flaw formed therein and having a width of 1 mm and a length of 30 mm.
　ダミー被検査体に対して、上述した渦電流探傷装置の磁気プローブによるラインスキャンニングを行う際には、ラインスキャンニングの最初の一点目の計測データを用いて基準同相成分及び基準虚数成分を初期設定する。基準同相成分及び基準虚数成分の初期設定後、それ以降に計測して得た計測データの同相成分及び虚数成分から基準同相成分及び基準虚数成分を差し引いて差分同相成分及び差分虚数成分とする。この差分同相成分及び差分虚数成分を用いて得られる信号強度のグラフは、図２にようになる。 When performing line scanning with the magnetic probe of the eddy current flaw detector described above on a dummy test object, the first in-phase component and the reference imaginary component are initially determined using the first measurement data of the line scanning. Set After initial setting of the reference in-phase component and the reference imaginary component, the reference in-phase component and the reference imaginary component are subtracted from the in-phase component and the imaginary component of the measurement data obtained by measurement thereafter to obtain a difference in-phase component and a difference imaginary component. A graph of signal strength obtained using this differential in-phase component and differential imaginary-number component is as shown in FIG.
　図２に示すように、図２の横軸の15mmの位置に存在している傷に近づいてくると信号強度が大きくなり、傷の直上では信号が基線に戻ってきている。さらに、傷から離れるにつれて信号強度が大きくなり、その後、減衰して基線に戻ってきている。このように、計測した同相成分及び虚数成分から基準同相成分及び基準虚数成分をそれぞれ差し引くことにより、強磁性体の磁化信号の影響を低減して、傷に起因する信号変化を抽出することができる。すなわち、傷の確実な検出を可能とすることができる。 As shown in FIG. 2, the signal intensity increases when approaching a flaw existing at a position of 15 mm on the horizontal axis of FIG. 2, and the signal returns to the baseline immediately above the flaw. In addition, the signal strength increases with distance from the wound and then decays back to the baseline. As described above, by subtracting the reference in-phase component and the reference imaginary-number component from the measured in-phase component and imaginary-number component, the influence of the magnetization signal of the ferromagnetic material can be reduced and the signal change caused by the flaw can be extracted. . That is, reliable detection of a flaw can be enabled.
　なお、図２においては、傷の存在を示す信号変化が約20mm程度の幅が広い変化となっており、しかも、傷の直上では信号が元の基線の信号強度近くに戻っている。 In FIG. 2, the change in the signal indicating the presence of a flaw is a wide change of about 20 mm, and the signal returns near the signal strength of the original baseline immediately above the flaw.
　図２のグラフが得られた信号強度の計測の際には、磁気プローブにおいて、磁気センサを印加コイルの中心軸線上に配置していた。これに対して、図３に示すように、磁気センサを印加コイルの中心軸線上から外し、印加コイル１－１の中心軸とコイル辺との間に配置してみた。コイル辺とは、閉ループを構成しているコイルの一部である。 In the measurement of the signal intensity at which the graph of FIG. 2 was obtained, in the magnetic probe, the magnetic sensor was disposed on the central axis of the application coil. On the other hand, as shown in FIG. 3, the magnetic sensor was removed from the central axis of the application coil and disposed between the central axis of the application coil 1-1 and the coil side. The coil side is a part of a coil forming a closed loop.
　ここで、本実施形態では、印加コイル１－１は、最内側の寸法を7mm×2.3mmの四角状として巻き数30のコイルとして、磁気プローブ２－１の先端側に配設している。印加コイル１－１は、適宜の配線を介して電源８に接続している。印加コイル１－１の形状は四角でなくても円形あるいは楕円であってもよく、閉ループの形状をしていればよい。 Here, in the present embodiment, the application coil 1-1 is disposed on the tip end side of the magnetic probe 2-1 as a coil with 30 turns, with the innermost dimension being a square of 7 mm × 2.3 mm. The application coil 1-1 is connected to the power supply 8 through appropriate wiring. The shape of the application coil 1-1 may not be a square, but may be a circle or an ellipse, as long as it has a closed loop shape.
　磁気センサ４－１は、本実施形態ではトンネル型ＭＲ素子であって、印加コイル１－１の中心軸から離れた位置、望ましくは、印加コイル１－１の中心軸らコイル辺までの距離の1/2以上離した方がよい。 The magnetic sensor 4-1 is a tunnel type MR element in this embodiment, and is located at a position away from the central axis of the application coil 1-1, preferably at a distance from the central axis of the application coil 1-1 to the coil side. It is better to separate by 1/2 or more.
　本実施形態では、磁気センサ４－１は、磁気センサ用実装基板３－１の上に実装されて、磁気プローブ２－１内に配設している。図３中、符号Ｓ－１は、磁気センサ用実装基板３－１とセンサ配線Ｔ－１とを接続するソケットである。センサ配線Ｔ－１は、適宜の配線を介して磁気センサ用回路５に接続している。 In the present embodiment, the magnetic sensor 4-1 is mounted on the magnetic sensor mounting substrate 3-1 and disposed in the magnetic probe 2-1. In FIG. 3, reference symbol S-1 denotes a socket for connecting the magnetic sensor mounting substrate 3-1 and the sensor wiring T-1. The sensor wiring T-1 is connected to the magnetic sensor circuit 5 via an appropriate wiring.
　図３の構成とした磁気プローブ２－１を用いて、ダミー被検査体に対してラインスキャンニングして得られた信号強度のグラフを図４に示す。ここで、ラインスキャンニングの最初の一点目の計測データを用いて基準同相成分及び基準虚数成分を初期設定している。また、印加コイル１－１には、100Hzの交流電流を流して交流磁場を生成している。 FIG. 4 shows a graph of signal intensity obtained by performing line scanning on a dummy test object using the magnetic probe 2-1 configured as shown in FIG. Here, the reference in-phase component and the reference imaginary-number component are initialized using measurement data of the first point of line scanning. In addition, an alternating current of 100 Hz is supplied to the applying coil 1-1 to generate an alternating magnetic field.
　図４に示すように、横軸の15mmの位置に存在している傷の近くに信号のピークが得られ、しかも、その変化幅を5mm程度とシャープな信号変化とすることができた。 As shown in FIG. 4, a peak of the signal was obtained near the scratch existing at the position of 15 mm on the horizontal axis, and the change width could be as sharp as 5 mm.
　磁気プローブの印加コイル内に配設する磁気センサは、一つとする場合だけでなく、複数とすることもできる。特に、図５に示すように、印加コイル１－２の中心軸を含む対称面に対して対称に磁気センサ４－２,４－３を配置することもできる。 Not only one magnetic sensor but also a plurality of magnetic sensors may be provided in the application coil of the magnetic probe. In particular, as shown in FIG. 5, the magnetic sensors 4-2 and 4-3 can be disposed symmetrically with respect to a plane of symmetry including the central axis of the application coil 1-2.
　ここでも、印加コイル１－２は、最内側の寸法を7mm×2.3mmの四角状として巻き数30のコイルとして、磁気プローブ２－２の先端側に配設している。印加コイル１－２は、適宜の配線を介して電源８に接続している。印加コイル１－２の形状は四角でなくても円形あるいは楕円であってもよく、閉ループの形状をしていればよい。 Also in this case, the application coil 1-2 is disposed on the tip side of the magnetic probe 2-2 as a coil having 30 turns, with the innermost dimension being a square of 7 mm × 2.3 mm. The application coil 1-2 is connected to the power supply 8 via appropriate wiring. The shape of the application coil 1-2 may not be a square, but may be a circle or an ellipse, as long as it has a closed loop shape.
　磁気センサ４－２,４－３は、本実施形態ではトンネル型ＭＲ素子であって、印加コイル１－２の中心軸から離れた位置、望ましくは、印加コイル１－２の中心軸らコイル辺までの距離の1/2以上であって、印加コイル１－２の中心軸を含む面を対称面として対象に、特に、印加コイル１－２の中心軸を対称軸として線対称に配設している。本実施形態では、２つの磁気センサ４－２,４－３は、約5mm離している。 The magnetic sensors 4-2 and 4-3 are tunnel type MR elements in the present embodiment, and positions away from the central axis of the applying coil 1-2, desirably, the coil axis of the applying coil 1-2 Of the distance up to a half of the distance up to and including the central axis of the application coil 1-2 as a symmetry plane, and in particular, arranged symmetrically about the center axis of the application coil 1-2 as a symmetry axis ing. In the present embodiment, the two magnetic sensors 4-2 and 4-3 are separated by about 5 mm.
　本実施形態でも、磁気センサ４－２,４－３は、それぞれ磁気センサ用実装基板３－２,３－３の上に実装されて、磁気プローブ２－２内に配設している。図５中、符号Ｓ－２は、磁気センサ用実装基板３－２とセンサ配線Ｔ－２とを接続するソケットであり、符号Ｓ－３は、磁気センサ用実装基板３－３とセンサ配線Ｔ－３とを接続するソケットである。センサ配線Ｔ－２,Ｔ－３は、それぞれ適宜の配線を介して磁気センサ用回路５に接続している。 Also in the present embodiment, the magnetic sensors 4-2 and 4-3 are mounted on the magnetic sensor mounting boards 3-2 and 3-3, respectively, and disposed in the magnetic probe 2-2. In FIG. 5, reference symbol S-2 denotes a socket for connecting the magnetic sensor mounting substrate 3-2 and the sensor wiring T-2, and reference symbol S-3 denotes the magnetic sensor mounting substrate 3-3 and the sensor wiring T. It is a socket that connects -3. The sensor wires T-2 and T-3 are connected to the magnetic sensor circuit 5 through appropriate wires.
　図５の構成とした磁気プローブ２－２を用いて、ダミー被検査体に対してラインスキャンニングして得られた信号強度のグラフを図６に示す。ここで、ラインスキャンニングの最初の一点目の計測データを用いて基準同相成分及び基準虚数成分を初期設定している。また、印加コイル１－２には、100Hzの交流電流を流して交流磁場を生成している。 FIG. 6 shows a graph of signal intensity obtained by performing line scanning on a dummy test object using the magnetic probe 2-2 configured as shown in FIG. Here, the reference in-phase component and the reference imaginary-number component are initialized using measurement data of the first point of line scanning. Further, an alternating current of 100 Hz is supplied to the application coil 1-2 to generate an alternating magnetic field.
　図６に示すように、２つの磁気センサ４－２,４－３は、まったく同様の結果が得られており、横軸の15mmの位置に存在している傷による得られた一つの信号ピークは急峻で半値幅約2.5ｍｍが得られている。 As shown in FIG. 6, the two magnetic sensors 4-2 and 4-3 give exactly the same result, and one signal peak obtained by the flaw existing at the position of 15 mm on the horizontal axis. Is steep, and a half width of about 2.5 mm is obtained.
　本実施形態では、２つの磁気センサ４－２,４－３は約5mm離れているので、図６に示される２つのピークは約5mm離れている。半値幅は、磁気センサ４－２,４－３の間距離より小さいので、ラインスキャンニングした時にそれぞれ独立してき裂を検出できていることを示している。この結果は、仮に傷が２つ以上近接して存在した場合にも、半値幅2.5mm以上離れていれば、きれいに分離して検出できることを示している。 In the present embodiment, since the two magnetic sensors 4-2 and 4-3 are separated by about 5 mm, the two peaks shown in FIG. 6 are separated by about 5 mm. Since the half width is smaller than the distance between the magnetic sensors 4-2 and 4-3, it indicates that a crack can be detected independently when line scanning is performed. This result indicates that even if two or more scratches are present in close proximity, they can be separated and detected clearly if they are separated by a half width of 2.5 mm or more.
　本発明の渦電流探傷装置における磁気プローブの大きさは、印加コイルの大きさに規制されるので、２チャンネルの磁気プローブを実現するために、あえて１つの印加コイルと１つの磁気センサの組み合わせからなる磁気センサプローブを２個設けて２チャンネルとするのではなく、図５に示すように、１つの印加コイルと２つの磁気センサとで２チャンネル化し、小さな磁気プローブを実現することができる。 Since the size of the magnetic probe in the eddy current flaw detector according to the present invention is regulated by the size of the applied coil, in order to realize a two-channel magnetic probe, the combination of one applied coil and one magnetic sensor is dare Instead of providing two magnetic sensor probes to form two channels, as shown in FIG. 5, two channels can be realized by one applied coil and two magnetic sensors to realize a small magnetic probe.
　図５に示した磁気プローブ２－２では、印加コイル１－２の中心軸を含む対称面に対して対称に配置した磁気センサ４－２,４－３は、２つの磁気センサ４－２,４－３の中間に印加コイル１－２の中心軸を位置させて配置しているが、変容例として、例えば、図７に示すように、印加コイル１－３の中心軸を含む対称面に対して対称に２つの磁気センサ４－４,４－５を配設してもよい。 In the magnetic probe 2-2 shown in FIG. 5, the magnetic sensors 4-2 and 4-3 disposed symmetrically with respect to the plane of symmetry including the central axis of the applying coil 1-2 are the two magnetic sensors 4-2, 4-3, the central axis of the application coil 1-2 is positioned and arranged, but as a modified example, as shown in FIG. 7, for example, in the plane of symmetry including the central axis of the application coil 1-3. Two magnetic sensors 4-4 and 4-5 may be disposed symmetrically to each other.
　ここで、印加コイル１－３は、最内側の寸法を7mm×2.3mmの四角状として巻き数30のコイルとして、磁気プローブ２－３の先端側に配設している。印加コイル１－３は、適宜の配線を介して電源８に接続している。印加コイル１－３の形状は四角でなくても円形あるいは楕円であってもよく、閉ループの形状をしていればよい。 Here, the application coil 1-3 is disposed on the tip side of the magnetic probe 2-3 as a 30-turn coil with an innermost dimension of 7 mm × 2.3 mm. The application coil 1-3 is connected to the power supply 8 through appropriate wiring. The shape of the application coil 1-3 may not be a square, but may be a circle or an ellipse, as long as it has a closed loop shape.
　磁気センサ４－４,４－５は、本実施形態でもはトンネル型ＭＲ素子であって、印加コイル１－３の中心軸から離れた位置、望ましくは、印加コイル１－２の中心軸らコイル辺までの距離の1/2以上であって、印加コイル１－３の中心軸を含む面を対称面として対象にに配設している。特に、本実施形態では、２つの磁気センサ４－４,４－５の中間に印加コイル１－３の中心軸が位置する配置とはしていない。 The magnetic sensors 4-4 and 4-5 are also tunnel type MR elements in this embodiment, and the position away from the central axis of the application coil 1-3, desirably, the coil of the central axis of the application coil 1-2 A plane which is half or more of the distance to the side and which includes the central axis of the application coil 1-3 is arranged as a plane of symmetry. In particular, in the present embodiment, the central axis of the application coil 1-3 is not located between the two magnetic sensors 4-4 and 4-5.
　本実施形態でも、磁気センサ４－４,４－５は、それぞれ磁気センサ用実装基板３－４,３－５の上に実装されて、磁気プローブ２－３内に配設している。図７中、符号Ｓ－４は、磁気センサ用実装基板３－４とセンサ配線Ｔ－４とを接続するソケットであり、符号Ｓ－５は、磁気センサ用実装基板３－５とセンサ配線Ｔ－５とを接続するソケットである。センサ配線Ｔ－４,Ｔ－５は、それぞれ適宜の配線を介して磁気センサ用回路５に接続している。 Also in the present embodiment, the magnetic sensors 4-4 and 4-5 are mounted on the magnetic sensor mounting boards 3-4 and 3-5, respectively, and disposed in the magnetic probe 2-3. In FIG. 7, reference symbol S-4 denotes a socket for connecting the magnetic sensor mounting substrate 3-4 and the sensor wiring T-4, and reference symbol S-5 denotes the magnetic sensor mounting substrate 3-5 and the sensor wiring T. It is a socket to connect with -5. The sensor wires T-4 and T-5 are connected to the magnetic sensor circuit 5 through appropriate wires.
　図７の構成とした磁気プローブ２－３を用いて、ダミー被検査体に対してラインスキャンニングして得られた信号強度のグラフを図８に示す。本実施形態では、基準同相成分及び基準虚数成分として、ラインスキャンニングの最初の一点目の計測データから得られる同相成分及び虚数成分を用いるのではなく、２つの磁気センサ４－４,４－５のうち、一方の磁気センサに対して他方の磁気センサから得られる基準同相成分及び基準虚数成分を同相成分及び虚数成分としている。すなわち、各磁気センサ４－４,４－５で得られた磁気信号の同相成分及び虚数成分の差し引きを行うことで差分同相成分及び差分虚数成分を計測している。 FIG. 8 shows a graph of signal intensity obtained by performing line scanning on a dummy test object using the magnetic probe 2-3 configured as shown in FIG. In this embodiment, instead of using the in-phase component and the imaginary component obtained from the first measurement data of line scanning as the reference in-phase component and the reference imaginary component, two magnetic sensors 4-4 and 4-5 are used. Of the two magnetic sensors, a reference in-phase component and a reference imaginary-number component obtained from the other magnetic sensor are used as the in-phase component and the imaginary-number component. That is, by subtracting the in-phase component and the imaginary component of the magnetic signal obtained by each of the magnetic sensors 4-4 and 4-5, the differential in-phase component and the differential imaginary component are measured.
　図７の構成とした磁気プローブ２－３では、磁気センサ４－４,４－５が隣り合っていることで、差分同相成分及び差分虚数成分を計測することは、微分信号に近いものが得られることになる。特に、鋼板などの強磁性体を計測した時に問題となる磁気雑音がなくなり、欠陥のあるところだけ信号変化が得られる特徴がある。 In the magnetic probe 2-3 configured as shown in FIG. 7, the magnetic sensors 4-4 and 4-5 are adjacent to each other, so that measuring the differential in-phase component and the differential imaginary component yields a signal close to a differential signal. Will be In particular, there is a feature that there is no magnetic noise that becomes a problem when measuring a ferromagnetic material such as a steel plate, and a signal change can be obtained only at a location where there is a defect.
　上記のように構成した磁気プローブ２－１,２－２,２－３を用いて渦電流探傷法による検査を行う場合には、磁気プローブのラインスキャニングを安定して行えるように、適宜のアダプターあるいは操作アームに磁気プローブを装着して使用してもよい。 When performing inspection by eddy current flaw detection using the magnetic probes 2-1, 2-2, 2-3 configured as described above, an appropriate adapter is provided so that line scanning of the magnetic probe can be performed stably. Alternatively, a magnetic probe may be attached to the operation arm and used.
　図１０には、道路橋に使用されている鉄鋼製の鋼床版１１にＵリブ１２を溶接している溶接部１３の検査に使用する場合を示している。 In FIG. 10, the case where it uses for the test | inspection of the welding part 13 which is welding U rib 12 to the steel-made steel floor slab 11 used for the road bridge is shown.
　道路橋では道路の舗装面の下に鉄鋼製の鋼床版１１が敷かれており、この鋼床版１１の下面に鉄鋼製のＵリブ１２を溶接して、支持構造を構成している。道路橋を荷重のある車が頻繁に通過すると、その荷重移動によって生じる振動によって、Ｕリブ１２と鋼床版１１とを溶接している溶接部１３にき裂が発生しやすい。 In the road bridge, a steel floor plate 11 is laid below the pavement surface of the road, and a steel U-rib 12 is welded to the lower surface of the steel floor plate 11 to form a support structure. When a vehicle with load frequently passes through the road bridge, a crack is likely to be generated in the welded portion 13 welding the U-rib 12 and the steel floor plate 11 due to the vibration caused by the movement of the load.
　さらに、溶接部１３における溶接ビードは幅を持っているため、１つの磁気プローブだけでは、磁気プローブに設けている印加コイルの面積が溶接ビードの表面と比較して小さいため、何回もラインスキャニングを行う必要がある。 Furthermore, since the weld bead in the weld portion 13 has a width, with only one magnetic probe, the area of the applied coil provided on the magnetic probe is small compared to the surface of the weld bead, so many times line scanning Need to do.
　そこで、図１０に示すように、磁気プローブが装着されるアダプター１０には、複数の磁気プローブ２－４,２－５,２－６を着脱自在に装着可能として、複数の磁気プローブ２－４,２－５,２－６を一度にラインスキャニングさせることで、検査時間を短縮することができる。 Therefore, as shown in FIG. 10, a plurality of magnetic probes 2-4, 2-5, and 2-6 can be detachably attached to the adapter 10 to which the magnetic probes are attached. , 2-5 and 2-6 at one time, the inspection time can be shortened.
　本実施形態のアダプター１０は、溶接部を中心とする円弧形状の基体を有し、この基体には、円周方向に所定間隔で磁気プローブ２－４,２－５,２－６を挿入する貫通穴を設けている。 The adapter 10 of the present embodiment has an arc-shaped base around a weld, and the magnetic probes 2-4, 2-5, and 2-6 are inserted into this base at predetermined intervals in the circumferential direction. Through holes are provided.
　各磁気プローブ２－４,２－５,２－６は、アダプター１０の貫通穴に挿入するだけで装着可能としており、図１０に示すように３つの磁気プローブ２－４,２－５,２－６を装着し、かつ各磁気プローブ２－４,２－５,２－６を図５に示し磁気プローブ２－２のように２つの磁気センサ４－２,４－３を設けた磁気プローブとすることで、6チャンネルの磁気センサアレイを実現することができる。 Each of the magnetic probes 2-4, 2-5, 2-6 can be mounted simply by inserting it into the through hole of the adapter 10. As shown in FIG. 10, the three magnetic probes 2-4, 2-5, 2 can be mounted. -6 is attached, and each of the magnetic probes 2-4, 2-5 and 2-6 is shown in FIG. Thus, a six-channel magnetic sensor array can be realized.
　本実施形態では、アダプター１０はプラスチック製としており、アダプター１０の端部には、鋼床版１１またはＵリブ１２と接して転動する転動ローラＲを設けていることで、溶接部１３の延伸方向に沿って容易に移動させることができ、安定してラインスキャニングを行うことができる。 In the present embodiment, the adapter 10 is made of plastic, and the end of the adapter 10 is provided with a rolling roller R that rolls in contact with the steel floor plate 11 or the U-rib 12. It can be easily moved along the stretching direction, and line scanning can be performed stably.
　アダプター１０は、検査箇所の形状に合わせて適宜の形状としてよく、磁気プローブと検査装置には変更を加えることなく、様々な箇所に対応して検査することができる。 The adapter 10 may have an appropriate shape in accordance with the shape of the inspection site, and can inspect the magnetic probe and the inspection device in various locations without changing the same.
　本発明は、金属性の構造物に生じるき裂などの欠陥を渦電流探傷法で検出する検査に広く用いることができ、特に従来困難であった鉄鋼製の構造物、たとえば橋梁やビル、工場プラント、発電設備、鉄道など幅広い分野での構造物の検査に応用ができる。 INDUSTRIAL APPLICABILITY The present invention can be widely used in inspections for detecting defects such as cracks occurring in metallic structures by eddy current flaw detection, and in particular steel structures that have been difficult in the past, such as bridges, buildings, factories, etc. It can be applied to inspection of structures in a wide range of fields such as plants, power generation facilities, and railways.
　１－１　印加コイル
　１－２　印加コイル
　１－３　印加コイル
　２－１　磁気プローブ
　２－２　磁気プローブ
　２－３　磁気プローブ
　２－４　磁気プローブ
　２－５　磁気プローブ
　２－６　磁気プローブ
　３－１　磁気センサ用実装基板
　３－２　磁気センサ用実装基板
　３－３　磁気センサ用実装基板
　３－４　磁気センサ用実装基板
　３－５　磁気センサ用実装基板
　４－１　磁気センサ
　４－２　磁気センサ
　４－３　磁気センサ
　４－４　磁気センサ
　４－５　磁気センサ
　５　　　磁気センサ用回路
　６　　　ロックインアンプ
　７　　　解析器
　８　　　励磁コイル用交流電源
　９　　　被検査体
　１０　　アダプター
　１１　　鋼床版
　１２　　Ｕリブ
　１３　　溶接部 1-1 Applied coil 1-2 Applied coil 1-3 Applied coil 2-1 Magnetic probe 2-2 Magnetic probe 2-3 Magnetic probe 2-4 Magnetic probe 2-5 Magnetic probe 2-6 Magnetic probe 3-1 Magnetic sensor Mounting substrate 3-2 magnetic sensor mounting substrate 3-3 magnetic sensor mounting substrate 3-4 magnetic sensor mounting substrate 3-5 magnetic sensor mounting substrate 4-1 magnetic sensor 4-2 magnetic sensor 4-3 magnetic sensor 4-4 Magnetic sensor 4-5 Magnetic sensor 5 Circuit for magnetic sensor 6 Lock-in amplifier 7 Analyzer 8 AC power supply for exciting coil 9 Test object 10 Adapter 11 Steel floor plate 12 U rib 13 Weld

Claims (9)

  1. 　印加コイルと磁気センサとを備えた磁気プローブで被検査体をラインスキャニングすることで前記被検査体を検査する渦電流探傷法において、
    　前記磁気センサは、前記印加コイルの中心軸と平行な磁場成分を検出することとし、
    　前記磁気センサから出力された信号から同相成分及び虚数成分を計測し、初期設定した基準同相成分及び基準虚数成分を差し引いて差分同相成分及び差分虚数成分として、この差分同相成分及び差分虚数成分を用いて解析を行うことで前記被検査体に生じたき裂を検出する渦電流探傷法。     In an eddy current flaw detection method for inspecting an object to be inspected by line scanning the object to be inspected with a magnetic probe provided with an applying coil and a magnetic sensor,
    The magnetic sensor detects a magnetic field component parallel to a central axis of the application coil,
    The in-phase component and the imaginary number component are measured from the signal output from the magnetic sensor, and the initially set reference in-phase component and the reference imaginary number component are subtracted to use the difference in-phase component and the difference imaginary number component as the difference in-phase component and the difference imaginary number component. Eddy current flaw detection method that detects a crack that has occurred in the inspection object by performing an analysis.
  2. 　前記基準同相成分及び前記基準虚数成分は、前記被検査体で欠陥がない領域で計測した同相成分及び虚数成分、あるいは任意に設定した同相成分及び虚数成分である請求項１に記載の渦電流探傷法。 The eddy current flaw detection device according to claim 1, wherein the reference in-phase component and the reference imaginary component are an in-phase component and an imaginary component measured in a region free of defects in the inspection object or an in-phase component and an imaginary component arbitrarily set. Law.
  3. 　前記磁気センサは、前記印加コイルの中心軸とコイル辺との間に配置している請求項１または請求項２に記載の渦電流探傷法。 The eddy current flaw detection method according to claim 1 or 2, wherein the magnetic sensor is disposed between a central axis of the application coil and a coil side.
  4. 　印加コイルと磁気センサとを備えた磁気プローブと、
    　前記印加コイルに交流電流を供給する電源と、
    　前記磁気センサの出力信号から同相成分及び虚数成分を計測する成分計測器と、
    　この成分計測器で得られた前記同相成分及び前記虚数成分を用いて解析を行う解析器と、
    を有する渦電流探傷装置において、
    　前記磁気センサは、前記印加コイルの中心軸と平行な磁場成分を検出し、
    　前記解析器では、前記成分計測器で得られた同相成分及び虚数成分から、初期設定した基準同相成分及び基準虚数成分を差し引いて差分同相成分及び差分虚数成分とし、この差分同相成分及び差分虚数成分を用いて解析を行う渦電流探傷装置。     A magnetic probe comprising an applying coil and a magnetic sensor;
    A power supply for supplying an alternating current to the application coil;
    A component measuring device for measuring an in-phase component and an imaginary component from an output signal of the magnetic sensor;
    An analyzer that performs analysis using the in-phase component and the imaginary component obtained by the component measuring device;
    In an eddy current flaw detector having
    The magnetic sensor detects a magnetic field component parallel to a central axis of the application coil,
    The analyzer subtracts the initially set reference in-phase component and reference imaginary number component from the in-phase component and the imaginary number component obtained by the component measuring device to obtain a difference in-phase component and a difference imaginary component, and the difference in-phase component and the difference imaginary number component Eddy current flaw detector to analyze using.
  5. 　前記基準同相成分及び前記基準虚数成分は、前記被検査体で欠陥がない領域で計測した同相成分及び虚数成分、あるいは任意に設定した同相成分及び虚数成分である請求項４に記載の渦電流探傷装置。 5. The eddy current flaw detection device according to claim 4, wherein the reference in-phase component and the reference imaginary-number component are an in-phase component and an imaginary-number component measured in an area without defects in the inspection object or an in-phase component and an imaginary-number component set arbitrarily. apparatus.
  6. 　前記磁気センサは、前記印加コイルの中心軸とコイル辺との間に配置して、前記中心軸と平行な磁場成分を検出する請求項４または請求項５に記載の渦電流探傷装置。 The eddy current flaw detector according to claim 4 or 5, wherein the magnetic sensor is disposed between a central axis of the application coil and a coil side to detect a magnetic field component parallel to the central axis.
  7. 　前記磁気プローブには、前記磁気センサを複数配設している請求項４～６のいずれか１項に記載の渦電流探傷装置。 The eddy current flaw detector according to any one of claims 4 to 6, wherein a plurality of the magnetic sensors are disposed on the magnetic probe.
  8. 　前記磁気センサは、前記印加コイルの中心軸を含む対称面に対して対称に配置している請求項７に記載の渦電流探傷装置。 The eddy current flaw detector according to claim 7, wherein the magnetic sensors are arranged symmetrically with respect to a plane of symmetry including the central axis of the application coil.
  9. 　前記磁気プローブを複数備えた請求項４～８のいずれか１項に記載の渦電流探傷装置であって、前記磁気プローブを着脱自在に装着可能としたアダプターを有する渦電流探傷装置。 The eddy current flaw detection apparatus according to any one of claims 4 to 8, comprising a plurality of the magnetic probes, wherein the eddy current flaw detection apparatus has an adapter capable of detachably mounting the magnetic probe.
PCT/JP2018/013244 2017-10-20 2018-03-29 Eddy-current flaw testing method and eddy-current flaw testing device WO2019077778A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2019549104A JP6826739B2 (en) 2017-10-20 2018-03-29 Eddy current flaw detection method and eddy current flaw detector

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2017203687 2017-10-20
JP2017-203687 2017-10-20

Publications (1)

Publication Number Publication Date
WO2019077778A1 true WO2019077778A1 (en) 2019-04-25

Family

ID=66173208

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2018/013244 WO2019077778A1 (en) 2017-10-20 2018-03-29 Eddy-current flaw testing method and eddy-current flaw testing device

Country Status (2)

Country Link
JP (1) JP6826739B2 (en)
WO (1) WO2019077778A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118191394A (en) * 2024-03-15 2024-06-14 弘乐集团有限公司 Electronic current-voltage sensor circuit, measuring method and structure thereof

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63168853U (en) * 1987-04-25 1988-11-02
US4821204A (en) * 1985-11-28 1989-04-11 Nukem Gmbh Method and device for testing for flaws with the eddy-current principle
JPH0783884A (en) * 1993-09-14 1995-03-31 Kenzo Miya Flaw examination method, flow examination device and flaw examination sensor
JP2012002633A (en) * 2010-06-16 2012-01-05 Hitachi Ltd Eddy current inspection device and inspection method
JP2013113787A (en) * 2011-11-30 2013-06-10 Hitachi Transportation Technologies Ltd Remote field eddy current flaw detection system and remote field eddy current flaw detection method
JP2015500498A (en) * 2011-12-15 2015-01-05 ポスコ Steel sheet flaw detector
JP2016038270A (en) * 2014-08-07 2016-03-22 高島産業株式会社 Eddy curent inspection device
JP2016105046A (en) * 2014-12-01 2016-06-09 国立大学法人 岡山大学 Magnetic nondestructive inspection device
JP2017003336A (en) * 2015-06-06 2017-01-05 国立大学法人 岡山大学 Magnetic field measurement device and nondestructive inspection device using the same

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06242076A (en) * 1993-02-12 1994-09-02 Toshiba Corp Electromagnetic flaw detecting equipment
CA3064833A1 (en) * 2017-05-26 2018-11-29 Ihi Corporation Apparatus for producing three-dimensional multilayer model, method for producing three-dimensional multilayer model, and flaw detector

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4821204A (en) * 1985-11-28 1989-04-11 Nukem Gmbh Method and device for testing for flaws with the eddy-current principle
JPS63168853U (en) * 1987-04-25 1988-11-02
JPH0783884A (en) * 1993-09-14 1995-03-31 Kenzo Miya Flaw examination method, flow examination device and flaw examination sensor
JP2012002633A (en) * 2010-06-16 2012-01-05 Hitachi Ltd Eddy current inspection device and inspection method
JP2013113787A (en) * 2011-11-30 2013-06-10 Hitachi Transportation Technologies Ltd Remote field eddy current flaw detection system and remote field eddy current flaw detection method
JP2015500498A (en) * 2011-12-15 2015-01-05 ポスコ Steel sheet flaw detector
JP2016038270A (en) * 2014-08-07 2016-03-22 高島産業株式会社 Eddy curent inspection device
JP2016105046A (en) * 2014-12-01 2016-06-09 国立大学法人 岡山大学 Magnetic nondestructive inspection device
JP2017003336A (en) * 2015-06-06 2017-01-05 国立大学法人 岡山大学 Magnetic field measurement device and nondestructive inspection device using the same

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118191394A (en) * 2024-03-15 2024-06-14 弘乐集团有限公司 Electronic current-voltage sensor circuit, measuring method and structure thereof

Also Published As

Publication number Publication date
JPWO2019077778A1 (en) 2020-11-05
JP6826739B2 (en) 2021-02-10

Similar Documents

Publication Publication Date Title
US7759931B2 (en) Device for measuring magnetic impedance
Ramos et al. Present and future impact of magnetic sensors in NDE
JP5483268B2 (en) Surface property inspection method
Tsukada et al. Detection of back-side pit on a ferrous plate by magnetic flux leakage method with analyzing magnetic field vector
JP6083613B2 (en) Magnetic nondestructive inspection equipment
Ramos et al. Using the skin effect to estimate cracks depths in mettalic structures
CN103675094A (en) Non-destructive testing device
Tsukamoto et al. Development of eddy current testing system using HTS-SQUID on a hand cart for detection of fatigue cracks of steel plate used in expressways
Wang et al. Multi-frequency imaging with non-linear calibration of magnetoresistance sensors for surface and buried defects inspection
Bernieri et al. A measurement system based on magnetic sensors for nondestructive testing
Tsukamoto et al. Eddy current testing system using HTS-SQUID with external pickup coil made of HTS wire
JP6826739B2 (en) Eddy current flaw detection method and eddy current flaw detector
JP2009103534A (en) Magnetic measurement apparatus
Chomsuwan et al. Application of eddy-current testing technique for high-density double-Layer printed circuit board inspection
Chomsuwan et al. Bare PCB inspection system with SV-GMR sensor eddy-current testing probe
JPH1038854A (en) Non-destructive inspection method and device of conductive material
Postolache et al. GMR based eddy current sensing probe for weld zone testing
Matsunaga et al. Application of a HTS coil with a magnetic sensor to nondestructive testing using a low-frequency magnetic field
Rucki et al. Evaluation of the residual magnetic field measurement system for early identification of railway defects
Saari et al. A circular eddy current probe using miniature fluxgates for multi-orientation slit evaluation in steel components
Reig et al. High-Spatial Resolution Giant Magnetoresistive Sensors-Part I: Application in Non-Destructive Evaluation
Dalal Radia et al. Detection of Defects Using GMR and Inductive Probes
Yamada et al. Application of giant magnetoresistive sensor for nondestructive evaluation
Kacprzak et al. Inspection of printed-circuit board by ECT probe with solenoid pickup coil
JPS59112257A (en) Method and device for nondestructive inspection of ferromagnetic material

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 18868406

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2019549104

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18868406

Country of ref document: EP

Kind code of ref document: A1