JP2009068915A - Defect measuring apparatus, defect measuring method, program, and computer-readable storage medium - Google Patents

Abstract

An object of the present invention is to make it possible to quantitatively measure the size of a defective portion existing in an object to be measured.
An electromagnetic ultrasonic sensor 110 disposed at a predetermined position of an object to be measured 200, a transmission control unit 141 for performing control of transmitting an ultrasonic wave 300a from the electromagnetic ultrasonic sensor 110 to the object to be measured 200, and The reflected ultrasonic wave 300b transmitted from the electromagnetic ultrasonic sensor 110 and reflected by the defect part 200a, and the reception control unit 142 that performs control to receive the magnetic noise (Barkhausen noise) by the electromagnetic ultrasonic sensor 110; A crystal grain size calculator 143 that calculates the crystal grain size of the DUT 200 based on the magnetic noise, and a defect size calculator that calculates the size of the defect part 200a based on the calculated crystal grain size and the reflected ultrasonic wave 300b. Part 145 is provided.
[Selection] Figure 4

Description

  The present invention relates to a defect measurement device that measures a defect portion existing in a measurement object, a defect measurement method, a program for causing a computer to execute the defect measurement method, and a computer-readable storage medium that stores the program. .

  Conventionally, an ultrasonic flaw detection method using ultrasonic waves has been proposed as a method for detecting a defect portion such as inclusions present in a large object to be measured such as a pipe or a steel plate. At this time, an ultrasonic sensor that transmits and receives ultrasonic waves to the object to be measured is used. In the ultrasonic flaw detection method using a normal ultrasonic sensor, the ultrasonic sensor needs to be in close contact with the object to be measured using a contact medium. Especially when measuring a large object to be measured, workability is extremely high. Get worse. Thus, conventionally, an ultrasonic flaw detection method using an electromagnetic ultrasonic (EMAT) sensor that can perform non-contact measurement without using a contact medium has been proposed (see, for example, Patent Document 1 and Patent Document 2 below).

JP-A-2005-214686 JP 2006-329868 A Yuichi Ito, “Application of Barkhausen Noise to Material Evaluation”, Toyota Central R & D Review Vol. 27 No. 4, 1992, p. 1-11

  However, the above-described conventional method for detecting a defective portion using an electromagnetic ultrasonic sensor is limited to detecting the defective portion, and it is difficult to quantitatively measure the size of the defective portion.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to make it possible to quantitatively measure the size of a defective portion existing in a measurement object.

  The defect measurement apparatus of the present invention is a defect measurement apparatus that measures a defect portion existing in an object to be measured using ultrasonic waves, and is disposed to face a predetermined position on the surface of the object to be measured. An ultrasonic sensor that transmits and receives ultrasonic waves while applying a signal, a transmission control means that performs control to transmit ultrasonic waves from the electromagnetic ultrasonic sensor to the object to be measured, and the electromagnetic ultrasonic sensor. Receiving control means for controlling the reflected ultrasonic waves reflected by the defective portion and the Barkhausen noise generated in the measurement object by the electromagnetic ultrasonic sensor, and the bulk received by the electromagnetic ultrasonic sensor. Based on the Hausen noise, the crystal grain size calculating means for calculating the crystal grain size of the measurement object, the crystal grain size calculated by the crystal grain size calculating means, and the defect portion based on the reflected ultrasonic wave And a defect size calculating means for calculating the size.

  The defect measurement method of the present invention includes an electromagnetic ultrasonic sensor that is disposed to face a predetermined position on the surface of the object to be measured and that transmits and receives ultrasonic waves while applying an alternating magnetic field, and is present in the object to be measured. A defect measurement method by a defect measurement device for measuring a defect portion, wherein a transmission control step for performing control to transmit ultrasonic waves from the electromagnetic ultrasonic sensor to the object to be measured is transmitted from the electromagnetic ultrasonic sensor. A reception control step for performing control to receive the reflected ultrasonic wave reflected by the defective portion and the Barkhausen noise generated in the object to be measured by the electromagnetic ultrasonic sensor, and the bulk received by the electromagnetic ultrasonic sensor. A crystal grain size calculating step for calculating a crystal grain size of the object to be measured based on Hausen noise; a crystal grain size calculated in the crystal grain size calculating step; and the reflected ultrasonic wave Based on, and a defect size calculating step of calculating the size of the defect.

  A program according to the present invention is provided with an electromagnetic ultrasonic sensor that is arranged to face a predetermined position on the surface of an object to be measured, and that transmits and receives an ultrasonic wave while applying an alternating magnetic field. A transmission control step for causing a computer to execute a defect measurement method by a defect measurement apparatus for measuring the object, wherein the electromagnetic wave is controlled to be transmitted from the electromagnetic ultrasonic sensor to the object to be measured, and the electromagnetic A reception control step for performing control to receive the reflected ultrasonic wave transmitted from the ultrasonic sensor and reflected by the defect portion and the Barkhausen noise generated in the object to be measured by the electromagnetic ultrasonic sensor; A crystal grain size calculating step for calculating a crystal grain size of the object to be measured based on Barkhausen noise received by an acoustic wave sensor; and the crystal grain size calculating step The calculated grain size, and, on the basis of the reflected ultrasonic wave, is intended for executing the defect size calculating step of calculating the size of the defect portion to the computer.

  The computer-readable storage medium of the present invention stores the program.

  According to the present invention, it is possible to quantitatively measure the size of a defect portion present in a measurement object.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In the following description, an example applied to a steel plate made of a magnetic material as an object to be measured will be described.

FIG. 1 is a schematic diagram illustrating an example of a schematic configuration of a defect measuring apparatus according to an embodiment of the present invention.
As shown in FIG. 1, the defect measuring apparatus 100 includes an EMAT (electromagnetic ultrasonic) sensor 110, a first alternating current source 120, a second alternating current source 130, and an information processing device 140. Has been.

  The EMAT sensor 110 is disposed at a predetermined position of the object to be measured (steel plate) 200 (or the reference plate 201) with the magnetic pole N (S) and the magnetic pole S (N) facing each other, and based on the control of the information processing device 140. Then, an SH wave (Shear Horizontal Wave) 300a which is an ultrasonic wave is generated on the measurement object (steel plate) 200 (or the reference plate 201). Here, the SH wave is an elastic wave that vibrates in a direction perpendicular to the propagation direction of the wave and parallel to the incident surface. In this case, the elastic wave is an ultrasonic wave. In addition, the EMAT sensor 110 is configured so that the SH wave 300a transmitted from the EMAT sensor 110 is transmitted to the defect portion 200a of the measurement target (steel plate) 200 (or the pseudo defect portion 201a of the reference plate 201) based on the control of the information processing device 140. ) And the reflected SH wave 300b that is the reflected ultrasonic wave and the magnetic noise (specifically, “Barkhausen noise” in the present embodiment) are detected.

  Specifically, the EMAT sensor 110 includes a core part 111a and an excitation coil 111b for exciting the core part 111a, and an electromagnet 111 that applies a magnetic field in the vicinity of the surface of an object to be measured (steel plate); The sensor coil 112 is configured to transmit the SH wave 300a, receive the reflected SH wave 300b, and receive Barkhausen noise according to the phase of the alternating current supplied to the exciting coil 111b. In this embodiment, the SH wave is transmitted as the ultrasonic wave transmitted from the EMAT sensor 110. However, another type of ultrasonic wave may be used. In the present embodiment, the Barkhausen noise is received by the sensor coil 112. However, the present invention is not limited to the Barkhausen noise. For example, other magnetic noise generated in the measured object (steel plate) 200 is used. It is also possible to measure by receiving.

  The first alternating current source 120 supplies alternating current to the exciting coil 111 b based on the control of the information processing device 140. Here, in the present embodiment, an alternating current related to a sine wave having a frequency of 50 Hz, for example, is supplied from the first alternating current source 120 to the exciting coil 111b.

  The second alternating current source 130 supplies alternating current to the sensor coil 112 based on the control of the information processing device 140. Here, in the present embodiment, for example, an alternating current related to a sine wave having a frequency of 150 kHz is supplied from the second alternating current source 130 to the sensor coil 112.

  The information processing apparatus 140 controls the EMAT sensor 110, the first alternating current source 120, and the second alternating current source 130, and measures the size (size) of the defect portion 200a in the measurement target (steel plate) 200. Various processes are performed.

Next, the mechanism of SH wave generation will be described below.
Specifically, the SH wave is generated by the magnetostriction effect of the object to be measured (steel plate) 200 (or the reference plate 201) made of a magnetic material. This magnetostriction effect is magnetized by applying a magnetic field to the magnetic material. This is a phenomenon in which directional distortion (elongation or shrinkage) of the magnetic field appears in the magnetic material. Then, reverse distortion (shrinkage or elongation) appears in the direction perpendicular to the magnetic field of the magnetic material.

FIG. 2 is a schematic diagram showing a sensor coil 112 opposed to the vicinity of the surface of the object to be measured (steel plate) 200 and a magnetic field generated thereby when the EMAT sensor 110 is viewed from above in FIG.
FIG. 2 (a) shows one pole and the other pole of the U-shaped electromagnet 111 shown in FIG. 1 at the top and bottom, and for convenience, at the top of FIG. 2 (a). The N pole of the electromagnet 111 is shown, and the S pole of the electromagnet 111 is shown in the lower part of FIG. FIG. 2A shows the sensor coil 112 shown in FIG. 1 between the N pole and the S pole of the electromagnet 111. As shown in FIGS. 2A and 1, the sensor coil 112 is formed of a meandering coil having a meandering shape.

First, as shown in FIG. 2A, a quasi-static current that slowly changes in time from the north pole to the south pole of the electromagnet 111 by flowing a current sufficiently large to be magnetized by the first alternating current source 120. A magnetic field H ₀ is generated (in this embodiment, the frequency of the current is 50 Hz, which will be described as a quasi-static magnetic field). Further, when a current in the direction of the thin arrow shown in FIG. 2A flows from the second alternating current source 130 to the sensor coil 112, the surface near the surface of the measurement object (steel plate) 200 at the position i is shown in FIG. An induction magnetic field H _x having a direction shown in a) is generated.

FIG. 2B shows the combined magnetic field H _{t at} the position i of the sensor coil 112. In FIG. 2B, the propagation direction of the SH wave 300a is the X axis, and the vibration direction of the SH wave 300a is the Y axis. In the case of the state shown in FIG. 2A, as shown in FIG. 2B, a synthetic magnetic field H _t by a quasi-static magnetic field H ₀ and an induction magnetic field H _x is generated at the position i.

  FIG. 3 is a schematic diagram showing the direction of magnetostriction generated in the measurement object (steel plate) 200 (or the reference plate 201). 3A and 3B, similarly to FIG. 2A, the N pole of the electromagnet 111 is shown in the upper part, and the S pole of the electromagnet 111 is shown in the lower part.

When a current in the direction shown in FIG. 3A (that is, the direction shown in FIG. 2A) flows through the sensor coil 112, the object to be measured (steel plate) 200 (in the direction shown by the arrow in FIG. Alternatively, the reference plate 201) is distorted (usually stretched with a steel plate). Further, when a current in the direction shown in FIG. 3B (that is, the direction opposite to the direction shown in FIGS. 2A and 3A) flows through the sensor coil 112, the arrow in FIG. The measured object (steel plate) 200 (or the reference plate 201) is distorted in the direction shown. At this time, with respect to the direction of the quasi-static magnetic field H ₀ , both of the strains in FIG. 3A and FIG. On the other hand, when the current of the sensor coil 112 is 0, the induced magnetic field H _x is zero, and the arrow points downward (in the direction of the quasi-static magnetic field H ₀ ), so that in FIGS. 3 (a) and 3 (b). More distortion than usual. Then, in one cycle of the alternating current supplied from the second alternating current source 130 to the sensor coil 112, two cycles of vibration are generated due to the magnetostriction shown in FIGS. By repeating the operation, the SH wave 300a propagating in the direction as shown in FIG. 1 is generated. At this time, for example, when an alternating current having a frequency of 150 kHz is supplied from the second alternating current source 130 to the sensor coil 112, an SH wave 300a having a frequency of 300 kHz is transmitted.

Next, the internal configuration of the defect measuring apparatus 100 will be described below.
FIG. 4 is a schematic diagram showing an example of the internal configuration of the defect measuring apparatus according to the embodiment of the present invention. Specifically, FIG. 4 shows the internal configuration of the information processing apparatus 140 shown in FIG. 1 as a functional configuration. In FIG. 4, the same components as those shown in FIG. 4 illustrates a case where the defect portion 200a of the measurement target (steel plate) 200 illustrated in FIG. 1 is present on the surface of the measurement target (steel plate) 200. In the present embodiment, the defect The present invention can also be applied to the case where the portion 200a exists inside or on the back surface of the measurement target (steel plate) 200.

  As illustrated in FIG. 4, the information processing apparatus 140 includes a transmission control unit 141, a reception control unit 142, a crystal grain size calculation unit 143, a reference data storage unit 144, a defect size calculation unit 145, and a display unit 146. It is comprised.

  The transmission control unit 141 performs control to transmit an SH wave 300 a that is an ultrasonic wave from the EMAT sensor 110 to the object to be measured (steel plate) 200. The control operation by the transmission control unit 141 will be described with reference to FIG.

  FIG. 5 shows an example of the timing of the alternating current supplied to the exciting coil 111b, the timing of transmission and reception of SH waves in the sensor coil 112, and the timing of reception of magnetic noise (Barkhausen noise) in the sensor coil 112. It is a timing chart. Specifically, in FIG. 5, the timing of the alternating current supplied to the exciting coil 111b is shown in FIG. 5 (a), and the timing of transmission and reception of the SH wave in the sensor coil 112 is shown in FIG. 5 (b). FIG. 5C shows the reception timing of magnetic noise (Barkhausen noise) in the sensor coil 112.

  When the transmission control unit 141 performs control to transmit the SH wave 300a, first, as shown in FIG. 5A, for example, a sine having a frequency of 50 Hz is transmitted from the first alternating current source 120 to the exciting coil 111b. The control which supplies the alternating current which concerns on a wave is performed. Subsequently, as shown in FIGS. 5A and 5B, the transmission control unit 141 determines the maximum value of the alternating current supplied from the first alternating current source 120 to the exciting coil 111b to the EMAT sensor 110. In a phase range (maximum value-containing phase range) that is large enough to magnetize the vicinity of the surface of the object to be measured (steel plate) 200 that opposes and includes a phase corresponding to the maximum value, the second alternating current Control is performed to supply an alternating current related to a sine wave having a frequency of 300 kHz, for example, from the source 130 to the sensor coil 112. Thereby, the magnetostriction shown in FIG. 3 is generated in the measurement object (steel plate) 200, and the SH wave 300a is transmitted from the EMAT sensor 110.

The waveform 300 of the SH wave shown in FIG. 5B is a waveform related to the transmission / reception of the SH wave obtained in the sensor coil 112 in the maximum value-containing phase range, and is transmitted from the EMAT sensor 110 in the first half thereof. The waveform of the reflected SH wave 300a (amplitude A ₀ ) is present, and the waveform of the reflected SH wave 300b (amplitude A ₂ ) received by the EMAT sensor 110 is present in the latter half thereof.

  Based on the transmission timing signal from the transmission control unit 141, the reception control unit 142 reflects the reflected SH wave 300b, which is a reflected ultrasonic wave transmitted from the EMAT sensor 110 and reflected by the defect portion 200a, and Barkhausen, which is magnetic noise. Control to receive noise by the EMAT sensor 110 is performed.

  Specifically, as shown in FIG. 5B, the reception control unit 142 performs control to receive the reflected SH wave 300b by the sensor coil 112 in the maximum value-containing phase range. Further, as shown in FIG. 5C, the reception control unit 142 corresponds to the phase range between the maximum value-containing phase ranges, and the amplitude of the alternating current supplied to the exciting coil 111b corresponds to 0 (zero). In the phase range including the phase (zero value-containing phase range), the sensor coil 112 performs control to receive Barkhausen noise. In other words, the reception control unit 142 controls the EMAT sensor 110 to receive the reflected SH wave 300b and Barkhausen noise at different timings in synchronization with an AC magnetic field generated by an AC current supplied to the excitation coil 111b. .

  Here, a mechanism for detecting the reflected SH wave 300b and Barkhausen noise in the EMAT sensor 110 will be described below.

When the reflected SH wave 300b propagates through the measured object (steel plate) 200 from the X-axis direction shown in FIG. 2B, distortion due to the reflected SH wave 300b occurs in the static magnetic field H ₀ , and the magnetic material causes An alternating current (alternating voltage) having the same frequency as that of the reflected SH wave 300 b is induced in the sensor coil 112 by the magnetostriction effect of the measured object (steel plate) 200. As for Barkhausen noise, an alternating current (alternating voltage) is induced in the sensor coil 112 as in the case of the reflected SH wave 300b. The reception control unit 142 receives the reflected SH wave 300b and Barkhausen noise based on the alternating current (alternating voltage) induced in the sensor coil 112.

The crystal grain size calculation unit 143 calculates the crystal grain size of the measurement target (steel plate) 200 based on Barkhausen noise that is magnetic noise received by the reception control unit 142. Specifically, in the present embodiment, the crystal grain size calculation unit 143 has the average crystal grain size D of the measurement target (steel plate) 200 based on the average fluctuation range P _noise of Barkhausen noise shown in FIG. ₁ is calculated.

The reference data storage unit 144 stores reference data related to the reference plate 201 which is a reference object made of a magnetic material. Here, the reference plate 201, which is a reference object, is provided with a pseudo-defect portion 201a having a predetermined artificial shape (in this embodiment, a rectangular parallelepiped having a length of 10 mm, a width of 10 mm, and a depth of 1 mm). Yes. Specifically, the reference data storage unit 144 stores table data relating to the amplitude A ₁ of the reflected SH wave 300b when the distance L ₀ from the EMAT sensor 110 shown in FIG. 1 to the pseudo defect 201a is used as a parameter (FIG. 7). ) And data such as the average crystal grain size D ₀ and the attenuation rate α _{0 of the} reference plate 201 are stored as reference data.

The defect size calculation unit 145 includes the crystal grain size (average crystal grain size D ₁ ) of the measurement target (steel plate) 200 calculated by the crystal grain size calculation unit 143, and the reflected SH wave 300 b received by the reception control unit 142. Based on the above, the size of the defective portion 200a of the measurement object (steel plate) 200 is calculated. More specifically, the defect size calculation unit 145 includes the average crystal grain size D _{1 of} the measurement target (steel plate) 200, the reflected SH wave 300b reflected by the defect portion 200a of the measurement target (steel plate) 200, and the reference data. using the reference data stored in the storage unit 144, calculates the size S ₁ of the defect portion 200a of the 200 object to be measured (steel).

The display unit 146 displays a measurement result in the size S ₁ of the defective part 200 a of the measurement target (steel plate) 200, or displays an operation status in the information processing apparatus 140.

Next, a specific defect measuring method by the defect measuring apparatus 100 will be described.
FIG. 6 is a flowchart illustrating an example of a processing procedure of the defect measurement method by the defect measurement apparatus according to the embodiment of the present invention.

First, in step S101 of FIG. 6, the information processing apparatus 140 performs a process of acquiring reference data related to the reference plate 201 made of a magnetic material. Specifically, in the present embodiment, the table data relating to the amplitude A ₁ of the reflected SH wave 300b when the distance L ₀ from the EMAT sensor 110 to the pseudo defect portion 201a shown in FIG. Data such as an average crystal grain size D _{0 of} 201 and an attenuation rate α ₀ are acquired as reference data.

FIG. 7 is a schematic diagram showing an example of table data related to the amplitude A ₁ of the reflected SH wave 300b when the distance L ₀ from the EMAT sensor 110 shown in FIG. 1 to the pseudo defect portion 201a of the reference plate 201 is used as a parameter. is there. In the present embodiment, the table data shown in FIG. 7 is actually measured by the defect measuring apparatus 100 and acquired.

Specifically, in the system shown in FIG. 1, the reference plate 201 is set, the distance L ₀ of the EMAT sensor 110 with respect to the pseudo defect portion 201a is varied, and the amplitude A ₁ of the reflected SH wave 300b at each measurement point is measured. To do. Thereby, the table data shown in FIG. 7 is acquired.

In the present embodiment, the table data shown in FIG. 7 is actually measured and acquired by the defect measuring apparatus 100. For example, table data obtained using another measuring apparatus is The form acquired by making it input into the defect measuring device 100 may be sufficient. Further, data such as the average crystal grain size D ₀ and the attenuation rate α _{0 of} the reference plate 201 are acquired by inputting data obtained using another measuring device to the defect measuring device 100.

  Thereafter, the information processing apparatus 140 stores the reference data related to the reference plate 201 acquired in step S101 in the reference data storage unit 144.

Subsequently, in step S102, the transmission control unit 141 of the information processing apparatus 140 performs control to transmit the SH wave 300a that is an ultrasonic wave from the EMAT sensor 110 to the measurement target (steel plate) 200. At this time, in FIG. 5B, the amplitude of the SH wave 300a transmitted from the EMAT sensor 110 is A ₀ .

  Specifically, the transmission control unit 141 generates an alternating current supplied from the first alternating current source 120 to the exciting coil 111b and an alternating current supplied from the second alternating current source 130 to the sensor coil 112. By controlling, control which transmits SH wave 300a is performed. More specifically, the transmission control unit 141 corresponds to the maximum value of the alternating current supplied from the first alternating current source 120 to the exciting coil 111b as shown in FIGS. 5 (a) and 5 (b). Control is performed to supply an alternating current from the second alternating current source 130 to the sensor coil 112 in the maximum value containing phase range including the phase. Thus, by supplying an alternating current to the sensor coil 112 in the maximum value-containing phase range, the magnetostriction shown in FIG. 3 is increased, and the SH wave 300a having a large amplitude can be transmitted. Contributes to improved measurement accuracy.

  Subsequently, in step S103, the reception control unit 142 of the information processing device 140, based on the transmission timing signal from the transmission control unit 141, the reflected SH wave 300b transmitted from the EMAT sensor 110 and reflected by the defective part 200a, and Then, the EMAT sensor 110 receives the Barkhausen noise that is magnetic noise.

  Specifically, as shown in FIG. 5B, the reception control unit 142 performs control to receive the reflected SH wave 300b by the sensor coil 112 in the maximum value-containing phase range. Further, as shown in FIG. 5C, the reception control unit 142 corresponds to the phase range between the maximum value-containing phase ranges, and the amplitude of the alternating current supplied to the exciting coil 111b corresponds to 0 (zero). In the phase range including the phase (zero value-containing phase range), the sensor coil 112 performs control to receive Barkhausen noise. Thus, by receiving Barkhausen noise in the zero value-containing phase range, there is an advantage that Barkhausen noise can be detected with high sensitivity.

  Subsequently, in step S104, the crystal grain size calculation unit 143 of the information processing apparatus 140 calculates the crystal grain size of the measurement target (steel plate) 200 based on the Barkhausen noise that is the magnetic noise received by the reception control unit 142. calculate.

Specifically, the crystal grain size calculation unit 143 calculates the average crystal grain size D of the measured object (steel plate) 200 according to the following formula 1 based on the average fluctuation range P _noise of Barkhausen noise shown in FIG. ₁ is calculated.

  In Equation 1, G () is a known function, and is shown in Non-Patent Document 1, for example. Specifically, Non-Patent Document 1 shows the following Formulas 2 to 4.

P _noise shown in Equation 2 corresponds to the average fluctuation range P _noise of Barkhausen noise shown in FIG. 5C, and D ₁ shown in Equation 2 is the average crystal grain size D _{1 of the} measurement object (steel plate) 200. It corresponds to. Further, C _V in Equation 3 is a constant, t _total in Equation 3 is the total generation time of pulses related to Barkhausen noise, r in Equation 3 is domain wall energy per unit area, I _S is saturation magnetization, and K is magnetic anisotropic. Indicates a sex constant. In Equation 4, H represents the strength of the applied magnetic field, t represents time, N represents the total number of pulses related to Barkhausen noise, and Φ represents magnetic flux.

Subsequently, in step S105, the defect size calculation unit 145 of the information processing device 140 is based on the crystal grain size of the measurement target (steel plate) 200 calculated in step S104 and the reflected SH wave 300b received in step S103. Then, the size of the defective portion 200a of the measurement object (steel plate) 200 is calculated. More specifically, the defect size calculation unit 145 includes the average crystal grain size D _{1 of} the measurement target (steel plate) 200, the reflected SH wave 300b reflected by the defect portion 200a of the measurement target (steel plate) 200, and the reference data. using the reference data stored in the storage unit 144, calculates the size S ₁ of the defect portion 200a of the 200 object to be measured (steel).

Processing for calculating the size S ₁ of the defective portion 200a in step S105 will be described in detail below.
First, the defect size calculation unit 145 calculates the EMAT sensor according to the following Equation 5 based on the time t from the transmission time of the SH wave 300a by the transmission control unit 141 to the reception time of the reflected SH wave 300b by the reception control unit 142. A distance L from 110 to the defective portion 200a of the measurement object (steel plate) 200 is calculated.

  In Formula 5, V is the speed of sound of the SH wave, and is a known value of about 3000 m / s, for example.

Next, the defect size calculation unit 145 uses the table data shown in FIG. 7 from the data stored in the reference data storage unit 144 and uses the reference plate 201 when the distance L ₀ is the calculated distance L. The amplitude A ₁ of the reflected SH wave 300b is extracted. Here, the amplitude A ₁ of the reflected SH wave 300 b on the reference plate 201 can be expressed by the following Equation 6.

In Equation 6, A ₀ represents the amplitude of the SH wave 300 a transmitted from the EMAT sensor 110, α ₀ represents the SH wave attenuation rate at the reference plate 201, and R ₀ represents SH at the pseudo defect portion 201 a of the reference plate 201. Shows wave reflectivity. Here, the attenuation rate α ₀ is a known value acquired in step S101. The attenuation rate α ₀ can be expressed by the following formula 7.

In Equation 7, C and n indicate constants, and D ₀ indicates the average crystal grain size of the reference plate 201. Here, the average crystal grain size D ₀ of the reference plate 201 is the known value acquired in step S101. Further, when the frequency of the SH wave 300a transmitted in the reference plate 201 is 300 kHz, the sound velocity V is about 3000 m / s, so the wavelength λ is about 10 mm, and the wavelength λ >> average crystal grain size D ₀ is so-called. Since it is a Rayleigh scattering region, the constant n is about 3.0 from theory and experiment. For this reason, the value of the constant C is also determined from the attenuation rate α ₀ and the average crystal grain size D ₀ acquired in step S101.

Further, the reflectance R ₀ in Expression 6 can be expressed by Expression 8 below, where the cross-sectional area S ₀ of the pseudo defect portion 201a of the reference plate 201 shown in FIG.

In the present embodiment, the pseudo defect portion 201a of the reference plate 201 is formed of a rectangular parallelepiped having a length of 10 mm, a width of 10 mm, and a depth of 1 mm. Therefore, the cross-sectional area S ₀ of the pseudo defect portion 201a shown in FIG. ²

Next, the defect size calculation unit 145 detects the amplitude A ₂ shown in FIG. 5B from the waveform of the reflected SH wave 300b in the measured object (steel plate) 200 received in step S103. Here, the amplitude A ₂ of the reflected SH wave 300 _b in the object to be measured (steel plate) 200 can be expressed by Equation 9 below.

In Equation 9, A ₀ indicates the amplitude of the SH wave 300a transmitted from the EMAT sensor 110, as in Equation 6, and in this embodiment, the amplitude of the SH wave 300a transmitted from the EMAT sensor 110 is the reference The same applies to the plate 201 and the object to be measured (steel plate) 200. In Equation 9, L represents the distance from the EMAT sensor 110 to the defective portion 200a calculated by Equation 5, α ₁ represents the SH wave attenuation rate in the object to be measured (steel plate) 200, and R ₁ represents the object to be measured. The reflectance of the SH wave in the defect part 200a of the thing (steel plate) 200 is shown. Here, the attenuation rate α ₁ and the reflectance R ₁ can be expressed by the following formulas 10 and 11, respectively.

In Formula 10, D ₁ is the average crystal grain size of the object to be measured (steel plate) 200, which is a known value calculated in step S104. Further, since the value of the constant C is also determined by Equation 7, the SH wave attenuation rate α ₁ in the measurement target (steel plate) 200 can be calculated by Equation 10. Further, in Equation 11, S ₁ is the cross-sectional area of the object to be measured (steel plate) 200 of the defect portion 200a shown in FIG. 1, namely, it shows the size of the defect portion 200a.

  Then, dividing the left side and the right side of Formula 9 by the left side and the right side of Formula 6, respectively, results in Formula 12 below.

In Expression 12, the right side is a known value, and thereby (R ₁ / R ₀ ) is obtained. Further, when the left side and the right side of Formula 11 are divided by the left side and the right side of Formula 8, respectively, Formula 13 below is obtained.

Then, when (R ₁ / R ₀ ) is obtained in Expression 12, the cross-sectional area S ₀ of the pseudo defect portion 201a of the reference plate 201 is a known value, so that the defect portion 200a of the measured object (steel plate) 200 is disconnected. area, i.e., it can calculate the size S ₁ of the defective portion 200a. In this way, the defect size calculation unit 145 calculates the size S ₁ of the defect part 200a of the measurement target (steel plate) 200.

Returning to the description of the flowchart of FIG.
When the object to be measured (steel) 200 calculation of the size S ₁ of the defect portion 200a is finished in step S105, the process proceeds to step S106. In step S106, the information processing apparatus 140 (defect size calculation unit 145) displays on the display unit 146 the measurement results in the size S ₁ of the calculated defect 200a in step S105. Thereby, the measurer can grasp the size S ₁ of the defective portion 200a of the measurement target (steel plate) 200 by visually recognizing the measurement result displayed on the display unit 146.

  By passing through the process of the above step S101-step S106, the measuring method of the size of the defect part 200a based on the calculated crystal grain diameter of the to-be-measured object (steel plate) 200 and the received reflected ultrasonic wave is performed.

In the defect measuring apparatus 100 of the present embodiment, ultrasonic waves are transmitted from the EMAT sensor 110 to the object to be measured (steel plate) 200 (step S102), and reflected ultrasonic waves transmitted from the EMAT sensor 110 and reflected by the defect portion 200a. Then, the magnetic noise (Barkhausen noise) is received by the EMAT sensor 110 (step S103), and the crystal grain size of the measurement object (steel plate) 200 is calculated based on the received magnetic noise (Barkhausen noise) (step S103). S104), the calculated object to be measured (steel) 200 grain size, and, based on the received reflected ultrasonic waves, and to calculate the size S ₁ of the defective portion 200a (step S105).
According to such a configuration, it is possible to quantitatively measure the size of the defective portion existing in the object to be measured.

  Further, in the defect measuring apparatus 100 of the present embodiment, when the reflected ultrasonic waves and magnetic noise (Barkhausen noise) are received by the EMAT sensor 110, as shown in FIGS. 5B and 5C, they are different. Since reception is performed at the timing, it is only necessary to provide one sensor coil 112 in the EMAT sensor 110, and the configuration of the EMAT sensor 110 can be simplified.

  Further, in the defect measuring apparatus 100 of the present embodiment, since SH waves are used as ultrasonic waves transmitted from the EMAT sensor 110, for example, when water droplets or oil adheres to the surface of the measurement object (steel plate) 200, for example. Even so, it can be made less susceptible to that effect.

  4 constituting the defect measuring apparatus 100 according to the present embodiment described above, and each step of FIG. 6 showing the defect measuring method by the defect measuring apparatus 100 are stored in a RAM or a ROM of a computer. This can be realized by operating the program. This program and a computer-readable storage medium storing the program are included in the present invention.

  Specifically, the program is recorded in a storage medium such as a CD-ROM, or provided to a computer via various transmission media. As a storage medium for recording the program, a flexible disk, a hard disk, a magnetic tape, a magneto-optical disk, a nonvolatile memory card, and the like can be used in addition to the CD-ROM. On the other hand, as the program transmission medium, a communication medium in a computer network (LAN, WAN such as the Internet, wireless communication network, etc.) system for propagating and supplying program information as a carrier wave can be used. In addition, examples of the communication medium at this time include a wired line such as an optical fiber, a wireless line, and the like.

  Further, the present invention is not limited to an aspect in which the function of the defect measuring apparatus 100 according to the present embodiment is realized by executing a program supplied by a computer. The program is also included in the present invention when the function of the defect measuring apparatus 100 according to the present embodiment is realized in cooperation with an OS (operating system) or other application software running on the computer. . Further, even when all or part of the processing of the supplied program is performed by the function expansion board or function expansion unit of the computer and the function of the defect measuring apparatus 100 according to the present embodiment is realized, the program is not limited to this program. Included in the invention.

  In addition, all of the above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. . That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

It is a schematic diagram which shows an example of schematic structure of the defect measuring device which concerns on embodiment of this invention. FIG. 2 is a schematic diagram showing a sensor coil facing a surface of an object to be measured (steel plate) and a magnetic field generated thereby when the EMAT sensor shown in FIG. 1 is viewed from above, showing the embodiment of the present invention. It is a schematic diagram which shows embodiment of this invention and shows the direction of the magnetostriction which arises in to-be-measured object (steel plate) (or reference | standard board). It is a schematic diagram which shows an example of the internal structure of the defect measuring device which concerns on embodiment of this invention. 1 illustrates an embodiment of the present invention, an example of timing of alternating current supplied to an excitation coil, timing of transmission and reception of SH waves in a sensor coil, and timing of reception of magnetic noise (Barkhausen noise) in a sensor coil It is a timing chart which shows. It is a flowchart which shows an example of the process sequence of the defect measuring method by the defect measuring device which concerns on embodiment of this invention. FIG. 5 is a schematic diagram illustrating an example of table data relating to the amplitude of a reflected SH wave when the distance from the EMAT sensor illustrated in FIG. 1 to the pseudo defect portion of the reference plate is used as a parameter, according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Defect measurement apparatus 110 EMAT (electromagnetic ultrasonic) sensor 111 Electromagnet 111a Core part 111b Excitation coil 112 Sensor coil 120 1st alternating current source 130 2nd alternating current source 140 Information processing apparatus 141 Transmission control part 142 Reception control part 143 Crystal grain size calculation unit 144 Reference data storage unit 145 Defect size calculation unit 146 Display unit 200 Object to be measured (steel plate)
200a Defect part 201 of measured object (steel plate) Reference plate 201a Pseudo defect part 300a of reference plate SH wave 300b Reflected SH wave S ₀ Cross sectional area of pseudo defect part of reference plate (size of pseudo defect part of reference plate)
S ₁ Cross-sectional area of the defective part of the workpiece (steel plate) (size of the defective portion of the workpiece (steel plate))

Claims (14)

A defect measuring apparatus that measures a defect portion existing in an object to be measured using ultrasonic waves,
An electromagnetic ultrasonic sensor that is arranged facing a predetermined position on the surface of the object to be measured, and that transmits and receives ultrasonic waves while applying an alternating magnetic field;
Transmission control means for performing control to transmit ultrasonic waves from the electromagnetic ultrasonic sensor to the object to be measured;
A reception control means for performing control to receive the reflected ultrasonic wave transmitted from the electromagnetic ultrasonic sensor and reflected by the defect portion and the Barkhausen noise generated in the object to be measured by the electromagnetic ultrasonic sensor;
Crystal grain size calculating means for calculating the crystal grain size of the object to be measured based on Barkhausen noise received by the electromagnetic ultrasonic sensor;
A defect measuring apparatus comprising: a defect size calculating unit that calculates a size of the defect portion based on the crystal particle size calculated by the crystal particle size calculating unit and the reflected ultrasonic wave.   The said reception control means performs control which receives the said reflected ultrasonic wave and the said Barkhausen noise synchronizing with the said alternating current magnetic field at a different timing in the said electromagnetic ultrasonic sensor. Defect measuring device.   The electromagnetic ultrasonic sensor includes an electromagnet configured to include a core part and an exciting coil for exciting the core part, and transmits the ultrasonic wave according to a phase of an alternating current supplied to the exciting coil. 3. The defect measuring apparatus according to claim 1, further comprising: a sensor coil that receives the reflected ultrasonic wave and receives the Barkhausen noise. 4. The transmission control means performs control to transmit the ultrasonic wave from the sensor coil in a maximum value-containing phase range that is a phase range including a phase corresponding to the maximum value of the alternating current supplied to the excitation coil,
The reception control means performs control to receive the reflected ultrasonic wave with the sensor coil in the maximum value-containing phase range, and performs the Barkhausen with the sensor coil in a phase range between the maximum value-containing phase ranges. The defect measuring apparatus according to claim 3, wherein control for receiving noise is performed. It further comprises storage means for storing reference data relating to the reference object in which the pseudo defect portion is formed,
The defect size calculation means calculates the size of the defect portion using the reference data in addition to the crystal grain size calculated by the crystal grain size calculation means and the reflected ultrasound. The defect measuring device according to any one of claims 1 to 4.   The defect measuring apparatus according to claim 1, wherein the ultrasonic wave transmitted from the electromagnetic ultrasonic sensor is an SH wave. A defect measuring device that is disposed to face a predetermined position on the surface of the object to be measured and includes an electromagnetic ultrasonic sensor that transmits and receives ultrasonic waves while applying an alternating magnetic field, and measures a defect portion existing in the object to be measured. Defect measurement method by
A transmission control step for performing control to transmit ultrasonic waves from the electromagnetic ultrasonic sensor to the object to be measured;
A reception control step for performing control to receive the reflected ultrasonic wave transmitted from the electromagnetic ultrasonic sensor and reflected by the defect portion and the Barkhausen noise generated in the object to be measured by the electromagnetic ultrasonic sensor;
A crystal grain size calculating step for calculating a crystal grain size of the object to be measured based on Barkhausen noise received by the electromagnetic ultrasonic sensor;
A defect measurement method comprising: a defect size calculation step of calculating a size of the defect portion based on the crystal particle size calculated in the crystal particle size calculation step and the reflected ultrasonic wave.   8. The reception control step according to claim 7, wherein the electromagnetic ultrasonic sensor performs control to receive the reflected ultrasonic wave and the Barkhausen noise in synchronization with the AC magnetic field at different timings. Defect measurement method.   The electromagnetic ultrasonic sensor includes an electromagnet configured to include a core part and an exciting coil for exciting the core part, and transmits the ultrasonic wave according to a phase of an alternating current supplied to the exciting coil. The defect measuring method according to claim 7, further comprising: a sensor coil that receives the reflected ultrasonic wave and receives the Barkhausen noise. In the transmission control step, in the maximum value-containing phase range that is a phase range including a phase corresponding to the maximum value of the alternating current supplied to the excitation coil, control is performed to transmit the ultrasonic wave from the sensor coil,
In the reception control step, control is performed so that the reflected ultrasonic waves are received by the sensor coil in the maximum value-containing phase range, and the sensor coil is used by the Barkhausen in a phase range between the maximum value-containing phase ranges. The defect measurement method according to claim 9, wherein control for receiving noise is performed. The defect measuring apparatus further includes storage means for storing reference data relating to a reference object in which a pseudo defect portion is formed,
In the defect size calculation step, in addition to the crystal grain size calculated in the crystal grain size calculation step and the reflected ultrasonic wave, the size of the defect portion is calculated using the reference data. The defect measuring method according to any one of claims 7 to 10.   The defect measurement method according to claim 7, wherein the ultrasonic wave transmitted from the electromagnetic ultrasonic sensor is an SH wave. A defect measuring device that is disposed to face a predetermined position on the surface of the object to be measured and includes an electromagnetic ultrasonic sensor that transmits and receives ultrasonic waves while applying an alternating magnetic field, and measures a defect portion existing in the object to be measured. A program for causing a computer to execute a defect measurement method according to
A transmission control step for performing control to transmit ultrasonic waves from the electromagnetic ultrasonic sensor to the object to be measured;
A reception control step for performing control to receive the reflected ultrasonic wave transmitted from the electromagnetic ultrasonic sensor and reflected by the defect portion and the Barkhausen noise generated in the object to be measured by the electromagnetic ultrasonic sensor;
A crystal grain size calculating step for calculating a crystal grain size of the object to be measured based on Barkhausen noise received by the electromagnetic ultrasonic sensor;
A program for causing a computer to execute the defect size calculation step of calculating the size of the defect portion based on the crystal particle size calculated in the crystal particle size calculation step and the reflected ultrasonic wave.   A computer-readable storage medium storing the program according to claim 13.

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