JP2009025093A - Electromagnetic ultrasonic measuring device, and measuring method of plate thickness and stress using electromagnetic ultrasonic wave - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic ultrasonic measuring device capable of measuring a material thickness and a stress inexpensively in a short time. <P>SOLUTION: An ultrasonic wave is generated on the surface of a measuring object plate. In this case, sound velocity of a transversal wave or a longitudinal wave is assumed (S11). The waveform of a received resonance spectrum is calculated (S12), and, first of all, the plate thickness is calculated (S13). Then, the sound velocity is calculated based on the plate thickness (S14). Acoustic double refraction B or a sound velocity ratio R is determined based on the calculated sound velocity. The stress is calculated based on the determined acoustic double refraction B or sound velocity ratio R (S15). Thereafter, the determined plate thickness and stress are displayed on a display part (S16). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic ultrasonic measuring apparatus and a method for measuring plate thickness and stress using electromagnetic ultrasonic waves, and in particular, an electromagnetic ultrasonic wave capable of measuring the plate thickness and stress of a steel structure using an electromagnetic ultrasonic resonance method. The present invention relates to a measuring and measuring apparatus and a method for measuring plate thickness and stress using electromagnetic ultrasonic waves.

  A method for measuring the bending stress of a tube with electromagnetic ultrasonic waves is described in, for example, Japanese Patent Laid-Open No. 9-280969 (Patent Document 1).

According to Patent Document 1, a first transverse wave that vibrates in the tube axis direction and a second transverse wave that vibrates in the tube circumferential direction are excited by an electromagnetic ultrasonic unit that can scan in the tube circumferential direction, and the first transverse wave and the second transverse wave are excited. The pipe propagation sound speed is calculated using a resonance method, and the bending stress applied to the pipe is evaluated from the distribution of the tube propagation sound speed difference between the first transverse wave and the second transverse wave over the entire region in the pipe circumferential direction.
JP-A-9-280969 (summary)

  Conventional tube stress measurement using ultrasonic waves has been performed as described above. The plate thickness was measured using, for example, an ultrasonic thickness meter. Thus, conventionally, stress measurement and thickness measurement in a steel structure have been performed individually. For this reason, there is a problem that the cost is high and the measurement takes time.

  The present invention has been made in view of the above problems, and can measure the thickness and stress of materials at a low cost in a short time. An object is to provide a measurement method.

  The electromagnetic ultrasonic measuring apparatus according to the present invention simultaneously measures the thickness of the material and the stress applied to the material using electromagnetic ultrasonic waves.

  Preferably, the electromagnetic ultrasonic measurement device is configured to measure a plate thickness on the assumption of a velocity value of the electromagnetic ultrasonic wave, and a sound velocity in the material using the plate thickness value obtained by the plate thickness measurement unit. A sound speed detecting means to be obtained; and a stress measuring means for measuring a stress applied to the material from the sound speed obtained by the sound speed detecting means.

  More preferably, the electromagnetic ultrasonic wave includes a transverse wave or a longitudinal wave, and the sound velocity detecting means includes respective sensors for detecting the transverse wave or the longitudinal wave of the electromagnetic ultrasonic wave.

  The longitudinal wave detection sensor for detecting longitudinal waves preferably includes a transmission sensor and a reception sensor which are separated from each other.

  The transmitting sensor includes a pair of second magnets provided so as to sandwich a magnet having the first polarity, a coil wound around the magnet having the first polarity, and the magnet having the first polarity outside the coil. And a polar magnet.

  The receiving sensor preferably includes a magnet having a first polarity and a coil wound around the magnet having the first polarity.

  In another aspect of the present invention, a method for measuring plate thickness and stress is characterized in that the plate thickness of a material and the stress applied to the material are simultaneously measured using electromagnetic ultrasonic waves.

  Preferably, the step of measuring the plate thickness on the assumption of the velocity value of the electromagnetic ultrasonic wave, the step of determining the sound velocity in the material using the plate thickness value obtained by the plate thickness measurement, and the obtained sound velocity to the material Measuring such stress.

  More preferably, the electromagnetic ultrasonic wave includes a transverse wave and a longitudinal wave, and includes a step of detecting the transverse wave and the longitudinal wave of the electromagnetic ultrasonic wave, respectively.

  In the present invention, the plate thickness of the material and the stress applied to the material are simultaneously measured using electromagnetic ultrasonic waves. Therefore, it is not necessary to separately prepare a measuring device for measuring the plate thickness and a device for measuring the stress.

  As a result, it is possible to provide an electromagnetic ultrasonic measuring apparatus and a measuring method using electromagnetic ultrasonic waves that can measure the thickness and stress of the material at a low cost in a short time.

(1) Configuration of Electromagnetic Ultrasonic Measuring Device Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a main part of an electromagnetic ultrasonic measurement apparatus according to an embodiment of the present invention. The electromagnetic ultrasonic measurement device 10 performs measurement using an electromagnetic ultrasonic resonance method. In this electromagnetic ultrasonic resonance method, a burst wave having a sufficient wave number in the thickness direction is excited, and the resonance state of the excited burst wave and the reflected wave is induced by changing the ultrasonic phase every moment. The ultrasonic wave used here may be a transverse wave or a longitudinal wave. First, a case where a transverse wave is used will be described.

  Referring to FIG. 1, an electromagnetic ultrasonic measurement device 10 includes a measurement device main body 11 and a transverse wave electromagnetic ultrasonic sensor 20 connected to the measurement device main body 11. The measuring apparatus body 11 includes a diplexer 12 connected to the electromagnetic ultrasonic sensor 20, a receiving amplifier 13 that amplifies a signal from the electromagnetic ultrasonic sensor 20 received by the diplexer 12, and a signal amplified by the amplifier 13. A spectrum calculation processing unit 14 that calculates a spectrum, an A / D converter 15 that converts a calculation result in the spectrum calculation processing unit 14 into a digital signal, a measured plate thickness, and a plate thickness that calculates stress, which will be described later And a stress calculation processing unit 16 and a display unit 19 such as a display.

  The measurement apparatus body 11 further includes a signal generator 17 that generates a measurement signal and an amplifier 18 that amplifies the signal generated by the signal generator 17, and the measurement signal amplified by the amplifier 18 is the diplexer 12. To the electromagnetic ultrasonic sensor 20. The plate thickness and stress calculation processing unit 16 is composed of a CPU. The diplexer 12 is a device that separates ultrasonic transmission / reception signals. The transverse ultrasonic electromagnetic sensor 20 is composed of a coil and a magnet.

  Next, the configuration of the transverse electromagnetic ultrasonic sensor 20 will be described. The electromagnetic ultrasonic sensor 20 is composed of a coil and a magnet, and can generate ultrasonic waves of various modes depending on how they are combined. FIG. 2A is a schematic view of a generally known transverse wave vertical propagation type transverse wave detection sensor. Transverse waves can be easily transmitted / received to / from a magnetic material such as mild steel.

  On the other hand, longitudinal waves can be detected without problems if they are non-magnetic, but it has been conventionally said that it is difficult to obtain a sufficiently strong signal for magnetic materials. However, the inventor has divided into longitudinal wave sensors for transmission (FIG. 2C) and reception (FIG. 2B) as shown in FIGS. 2B and 2C by various studies. By using the two-probe method, a sufficient received signal in a magnetic material such as mild steel was confirmed. Table 1 shows an example of the magnet and coil characteristics of each detection sensor.

  Referring to FIGS. 2B and 2C, the transmission longitudinal wave sensor sandwiches the N-pole magnet, the coil wound around the N-pole magnet, and the N-pole magnet outside the coil. A pair of south pole magnets provided as described above. The longitudinal wave sensor for reception includes an N-pole magnet and a coil wound around the N-pole magnet. The N pole and S pole may be reversed.

  Next, an electromagnetic ultrasonic measurement apparatus capable of measuring a magnetic material when longitudinal waves are used as ultrasonic waves will be described. FIG. 3 is a block diagram showing a configuration of the electromagnetic ultrasonic measurement device 10a when a longitudinal wave is used as an ultrasonic wave, and corresponds to FIG. 1 when a transverse wave is used. Only the electromagnetic ultrasonic sensor is different between the case where the transverse wave is used and the case where the longitudinal wave is used. The configuration from the receiving amplifier 13 of the receiving unit to the display unit 19 and the signal generator 17 of the transmitting unit are different. Since the configuration of the amplifier 18 is the same as that shown in FIG. 1, the same reference numerals are given to the same portions, and the description thereof is omitted. As shown in FIG. 3, when a longitudinal wave is used, the transmission sensor 21 and the reception sensor 22 are separated as electromagnetic ultrasonic sensors, and the transmission sensor 21 is connected to the amplifier 18 to receive the reception sensor. 22 is connected to the receiving amplifier 13. Therefore, when a longitudinal wave is used, a diplexer is not necessary.

(2) Measurement of board thickness Next, the measuring method of board thickness is demonstrated. The case where a transverse wave is used and the case where a longitudinal wave is used are basically the same, but here, a case where a transverse wave is used will be described first. FIG. 4 is a diagram showing a state in which the steel plate 30 is measured using the transverse wave detection sensor shown in FIG. FIG. 4 shows a state where the electromagnetic ultrasonic sensor 20 is placed on the plate 30. Here, ultrasonic waves are generated at magnet portions indicated by N and S (portions indicated by hatching in the figure).

  A specific plate thickness measurement method will be described later. Generally, in the electromagnetic ultrasonic resonance method, the following equation (1) is established.

f _n = (n × V) / (2 × d) (1)
Here, f is the frequency, V is the speed of sound, d is the plate thickness, and n (≧ 1) is the resonance order. The peak value of the resonance spectrum is calculated by approximating the spectrum data by the least square method, and this is used as the resonance frequency.

  When the shear wave was used, the shear wave velocity V was measured as 3230 m / s as described above. An example of the result in this case is shown in FIG. FIG. 5 is a diagram showing the relationship between frequency and amplitude when a plate 30 having a plate thickness d = 20 mm is measured.

  When the measurement material has a certain plate thickness, a resonance spectrum 41 stands for each frequency corresponding to the plate thickness. Assuming the speed of sound in this way, the plate thickness can be measured.

  The same applies to the case where longitudinal waves are used. As the longitudinal wave, for example, the sound speed may be assumed to be 5900 m / s.

(3) Stress measurement Next, a stress measurement method will be described. Here, the stress is measured using the acoustoelastic method. The acoustoelastic method is a method for evaluating the stress from the sound speed by utilizing the effect that the sound speed of the ultrasonic wave changes depending on the stress. In general, the following formulas (2) and (3) are established in a plane stress state in which the principal anisotropy axis of the material coincides with the principal stress direction.

B = (V ₁ −V ₂ ) / ((V ₁ + V ₂ ) / 2) = B ₀ + C _A (σ ₁ −σ ₂ ) (2)
R = V _L / ((V ₁ + V ₂ ) / 2) = R ₀ + C _R (σ ₁ + σ ₂ ) (3)
Here, V ₁ and V ₂ are the speeds of transverse waves in directions orthogonal to each other, _VL is the speed of sound of longitudinal waves, B is acoustic birefringence, and R is deflected in two directions with longitudinal wave speeds of sound. It is a ratio to the transverse wave average sound speed, B ₀ is a tissue anisotropy, R ₀ is a sound speed ratio when no stress is applied, and C _A and _CR are acoustoelastic constants.

The inventor conducted a tensile test in the elastic region as a basic study of acoustoelastic characteristics using the transverse wave detection sensor or the developed longitudinal wave detection sensor shown in FIG. The test piece used for the uniaxial tensile test is shown in FIG. The length of the test piece in the rolling direction was 550 mm and the width was 108 mm. The material was SS400, and the tensile direction was the rolling direction of the material. In addition, since it is uniaxial tension, it was set as (sigma) ₂ = 0 of Formula (2) and (3). The electromagnetic ultrasonic sensor 20 was disposed at the center of the test piece, and the transverse wave detection sensor measured two directions of a sound velocity V ₁ whose deflection direction was parallel to the rolling direction and a vertical sound velocity V ₂ . In the case of the longitudinal wave, a longitudinal wave detection sensor was arranged on the front and back of the test piece, and the two probe method was used. Each sound velocity measurement was performed in the range of the elastic region about every 30 MPa from an unloaded state. The measurement conditions of the resonance method were a burst wave number of 250 cycles, a measurement frequency of 2.0 to 4.0 MHz, and a sampling number of 600.

(4) Results of Stress Measurement Experiments on Tensile Specimens FIG. 7 shows the sound velocity measurement results of transverse waves deflected in two directions obtained by a tensile test. In formula (1), the plate thickness was calculated as 6.00 mm. The shear wave velocity V ₁ deflected in the rolling direction (represented by □ in the figure) decreases as the stress increases, and V ₂ (represented by ○ in the figure) increases as the stress increases. On the other hand, the longitudinal wave velocity V _L (represented by ◇ in the figure) tends to increase with stress. FIG. 8 shows the acoustic birefringence B and the sound speed ratio R calculated from the sound speed values. Table 2 shows acoustoelastic constants and initial values obtained from these regression curves. Both the acoustic birefringence B and the sound speed ratio R changed linearly with respect to the stress, and the inclination of the sound speed ratio was slightly larger. FIG. 9 shows a comparison between the measured stress value obtained from the acoustoelastic method and the nominal stress value. In the figure, □ indicates a transverse wave, and ■ indicates a longitudinal wave. As shown in FIG. 9, the measurement result by the acoustoelastic method is well matched with the nominal stress, and it was found that the measurement can be performed with sufficient accuracy not only in the transverse wave but also in the longitudinal wave. Therefore, the difference and sum of the principal stresses σ ₁ and σ ₂ can be obtained by the birefringence method or the sound velocity ratio method by using the above-described transverse wave detection sensor or longitudinal wave detection sensor. That is, the principal stresses σ ₁ and σ ₂ can be obtained even in a steel material by a combination of the birefringence method and the sound velocity ratio method.

(5) Examination of simultaneous measurement of plate thickness and stress From the results of the examination so far, it was found that the plate thickness and stress (each principal stress) can be measured individually using the electromagnetic ultrasonic resonance method. Each of these measurements is a result when the speed of sound or the plate thickness is known, and both measurements are required when applied to an actual structure.

  In plate thickness measurement using a general piezoelectric probe, the sound speed is set using a calibration piece, and the plate thickness is measured after appropriate calibration. FIG. 10 shows the plate thickness measurement error by the electromagnetic ultrasonic resonance method when the shear wave velocity of steel is 3230 m / s.

  FIG. 10 is a diagram plotting the actual plate thickness on the horizontal axis and the plate thickness measured by changing the number of sampling of each data on the vertical axis. An enlarged view of each point is displayed in the portion indicated by the arrow. In the enlarged view, ◯ and ● indicate data when the sampling number is 100, and Δ, ▲, ▽, and ▼ indicate data when the sampling number is 200 and 300, respectively. White and black indicate data of each transverse wave deflected in two directions. Referring to FIG. 10, for example, if the plate thickness is less than 20 mm, all measurement points are included within ± 0.1 mm, but if the plate thickness is 20 mm or more, the number of samplings is not large. It can be seen that most of the points do not exist within ± 0.1 mm. That is, if the plate thickness is increased, an accurate value cannot be obtained unless the number of samplings is increased.

The burst wave number was sufficient for each plate thickness. As the plate thickness increases, d increases in the above-described equation (1), and thus f _n decreases. As a result, since the number of resonance spectra increases, the number of data per resonance spectrum decreases with the same number of samplings as the thin plate, and the error in detecting a peak by the least square method increases. Therefore, in the case of a thick plate, as described above, a sufficient number of samplings are required for the measurement frequency range. As a result of this time, it was found that for a thick plate of up to about 35 mm, an accuracy of less than 0.1 mm can be ensured if the sampling number is 200 in the frequency range of 1 MHz. From the above, regarding plate thickness measurement, high-accuracy sound speed is not required, and sufficient thickness measurement accuracy can be obtained at a transverse wave sound velocity of 3230 m / s if measurement is performed with a sufficient number of samplings corresponding to the plate thickness. Was confirmed.

Next, the effect of plate thickness on stress measurement will be examined. As shown in FIG. 7, the change of each sound velocity value due to the stress is about 5 m / s in the range of 0 to 240 MPa. Also in transverse _{V 2,} it is about 5/3230 = 0.15%, which is only the error range of the plate thickness measurement by general ultrasound. In order to confirm the change in the sound speed value due to the plate thickness measurement error, the change in the sound speed value due to the stress when the plate thickness is changed by 0.1 mm from the actual value is shown in FIGS. FIG. 11 shows a case of a transverse wave, and FIG. 12 shows a case of a longitudinal wave.

FIG. 11A is a diagram showing the relationship between the stress and the sound velocity of the transverse wave when the plate thickness is changed in the deflection directions different from each other by 90 degrees, and FIG. 11B shows the relationship between FIG. It is a figure which shows the relationship between stress and acoustic birefringence created based on this. In FIG. 11A, □ corresponds to V ₁ and ◯ corresponds to V ₂ . In FIG. 11A, the case of a plate thickness of 6 mm is shown in black. Referring to FIG. 11A, when the plate thickness changes, the absolute value of each sound velocity changes, but the slope of the transverse wave in each deflection direction is constant, and the difference in sound velocity in the transverse wave deflection direction changes. Not done. That is, as shown in FIG. 11B, it can be seen that the acoustic birefringence B at each stress is obtained regardless of the plate thickness. Therefore, if the acoustoelastic characteristics are grasped in advance for each measurement material, it is considered that the stress measurement is possible without being affected by the plate thickness measurement.

  On the other hand, FIG. 12 (A) is a diagram showing the relationship between stress and sound velocity when the plate thickness is changed using longitudinal waves, and FIG. 12 (B) is based on FIG. 12 (A). It is a figure which shows the created relationship between the ratio R of the stress, the longitudinal wave sound velocity, and the transverse wave average sound velocity deflected in two directions.

  Referring to FIG. 12, in this case as well, if the acoustoelastic characteristics are grasped for each measurement material in advance, stress measurement can be performed using the sound velocity ratio method without being affected by the thickness measurement. Is possible.

  From the above, the inventor has come up with the idea that plate thickness measurement and stress measurement can be performed simultaneously using an electromagnetic ultrasonic measurement device. The procedure will be described below.

(6) Method for Simultaneously Performing Plate Thickness Measurement and Stress Measurement FIG. 13 is a diagram for explaining the operation of performing plate thickness and stress measurement using the electromagnetic ultrasonic measurement device 10 according to this embodiment. Specifically, it is a flowchart showing an operation performed by the plate thickness and stress calculation processing unit 16. Referring to FIG. 13, first, a signal generator 17 generates a high-frequency signal, which is amplified by an amplifier 18, and in the case of a transverse wave, to the electromagnetic ultrasonic sensor 20 via the diplexer 12, and in the case of a longitudinal wave. Using a direct transmission sensor, a high-frequency current is passed, ultrasonic waves are generated on the surface of the measurement target plate, and ultrasonic waves are propagated toward the plate 30 from there. At this time, the sound speed is assumed to be 3230 m / s, for example, if it is a transverse wave, and 5900 m / s, for example, if it is a longitudinal wave (step S11, hereinafter, steps are omitted).

  Next, a reflected wave from the plate 30 is received by the electromagnetic ultrasonic sensor 20 (or reception sensor), the received reflected wave is amplified by the amplifier 13, and the amplified reflected wave is calculated by the spectrum calculation processing unit 14. Then, the resonance spectrum waveform is calculated (S12), converted by the A / D converter 15, and the plate thickness and stress calculation processing unit 16 first calculates the plate thickness (S13).

  As resonance conditions here, the measurement frequency range was 1 to 5 MHz, and the burst wave number was 250 cycles. The plate thickness value is obtained by the following equation obtained by modifying the above equation (1) based on the resonance method.

d = (n × V) / (2 × f)
Here, each variable is as described above.

  At this time, as described above, if sufficient sampling is performed according to the plate thickness, the plate thickness can be obtained with an accuracy of less than 0.1 mm.

  Next, the calculated plate thickness and resonance frequency are inputted into the equation (1), and the sound velocity of the transverse wave or the longitudinal wave is calculated with high accuracy (S14). The acoustic birefringence B is obtained on the basis of the calculated transverse wave sound velocity and the equation (2). Similarly, when the longitudinal wave is used, the sound speed ratio R is obtained. When the acoustic birefringence B and the sound velocity ratio R are obtained, as shown by arrows in FIGS. 11B and 12B, the difference between the main stresses and the sum of the main stresses can be obtained. The main stress can be obtained (S15). Thereafter, the obtained plate thickness and stress are displayed on the display unit 19 (S16). Therefore, the plate thickness and stress calculation processing unit 16 functions as a plate thickness measuring unit, a sound speed detecting unit, and a stress measuring unit.

  As described above, according to this embodiment, it is possible to measure the plate thickness and the stress applied to the plate using a single electromagnetic ultrasonic measurement device. As a result, it is possible to provide an apparatus that can measure the thickness and stress at a low cost and in a short time.

  In addition, since electromagnetic ultrasonic waves are used here, unlike a general piezoelectric element type ultrasonic sensor, a contact medium is not required, and it is possible to efficiently and easily measure a plate thickness and stress with high accuracy.

  Next, data obtained by detecting a longitudinal wave using a longitudinal wave receiving sensor will be described. FIG. 14 is a diagram showing data obtained by the longitudinal wave detection sensor, and corresponds to the data obtained by the transverse wave shown in FIG. (A) is a detection example in aluminum having a plate thickness of 20 mm, and (B) and (C) are detection examples in steel having a plate thickness of 5.6 mm. The dotted line in the figure in (B) shows the frequency of the longitudinal wave spectrum corresponding to the plate thickness of 5.6 mm calculated from the equation (1) with V = 5947 m / s. (C) shows the frequency of the transverse wave spectrum corresponding to the plate thickness of 5.6 mm calculated from the equation (1) with V = 3256 m / s.

  In the case of an aluminum plate, the sensor shown in FIG. 2C is measured for both transmission and reception. In the case of steel, the front and back sides of the test piece are shown in FIG. 2C for transmission and FIG. 2B for reception. It is an example at the time of arranging and measuring each sensor.

  Referring to (A), it can be seen that a longitudinal wave spectrum is easily obtained with aluminum.

  Also in the case of steel, as shown in (B) and (C), the longitudinal wave spectrum is clearly obtained although the transverse wave spectrum exists. Therefore, in this embodiment, it can be seen that longitudinal waves can be detected even in a magnetic material such as steel.

  In other words, in this embodiment, a sensor for transmission and reception was developed as a longitudinal wave sensor, so the plate thickness and each principal stress can be measured simultaneously even for magnetic materials such as steel. It became.

  In the above-described embodiment, the case where the stress is measured after measuring the plate thickness is described. However, the present invention is not limited to this, and the stress may be measured while measuring the plate thickness.

  In the above embodiment, the case where a magnetic material is used has been described as the case where a longitudinal wave is used. However, the present invention is not limited to this. This is possible using an electromagnetic ultrasonic sensor.

  Further, in the above embodiment, the thickness of the plate was measured using the electromagnetic ultrasonic resonance method. However, the present invention is not limited to this, and if a single probe is used for transmission and reception, the single-around method, An arbitrary method such as a pulse overlap method may be used.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

It is a block diagram which shows the principal part of the electromagnetic ultrasonic measuring apparatus using the transverse wave concerning one embodiment of this invention. It is a top view of an electromagnetic ultrasonic sensor. It is a block diagram which shows the principal part of the electromagnetic ultrasonic measurement apparatus using a longitudinal wave. It is a figure which shows the state which measures a steel board using an electromagnetic ultrasonic sensor. It is a figure which shows the resonance spectrum at the time of measuring a healthy board. It is a top view which shows a tensile test piece. It is a figure which shows the sound velocity measurement result of the transverse wave deflected in two directions obtained by the tensile test. It is a figure which shows the acoustic birefringence B and the sound speed ratio R. It is a figure which shows the comparison with the measured stress value calculated | required from the acoustoelastic method, and a nominal stress value. It is a figure which shows the plate | board thickness measurement error by an electromagnetic ultrasonic resonance method. It is a figure which shows the relationship between a stress and the sound velocity of a transverse wave, and the relationship between a stress and acoustic birefringence when changing plate | board thickness. It is a figure which shows the relationship between stress and the speed of sound at the time of changing plate | board thickness using a longitudinal wave, and ratio R of the transverse wave average sound speed deflected to a stress, a longitudinal wave sound speed, and two directions. It is a flowchart explaining the operation | movement which performs plate | board thickness and stress measurement using an electromagnetic ultrasonic measurement apparatus. It is a figure which shows the data obtained by the sensor for longitudinal wave detection.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Electromagnetic ultrasonic measurement apparatus, 11 Measurement apparatus main body, 12 Diplexer, 13 Amplifier, 14 Spectrum calculation processing part, 15 A / D converter, 16 Plate thickness and stress calculation processing part, 17 Signal generator, 18 Amplifier, 19 Display Part, 20 electromagnetic ultrasonic sensor, 21 transmitting sensor, 22 receiving sensor, 30 plate.

Claims (9)

An electromagnetic ultrasonic measurement apparatus that simultaneously measures a plate thickness of a material and stress applied to the material using electromagnetic ultrasonic waves. Plate thickness measuring means for measuring the plate thickness assuming the velocity value of the electromagnetic ultrasonic wave,
A sound velocity detecting means for obtaining a sound velocity in the material using a plate thickness value obtained by the plate thickness measuring means;
The electromagnetic ultrasonic measurement apparatus according to claim 1, further comprising: a stress measurement unit that measures a stress applied to the material from a sound speed obtained by the sound speed detection unit. The electromagnetic ultrasonic wave includes a transverse wave or a longitudinal wave,
The electromagnetic ultrasonic measurement device according to claim 2, wherein the sound velocity detection unit includes a sensor that detects a transverse wave or a longitudinal wave of the electromagnetic ultrasonic wave. The electromagnetic ultrasonic measurement apparatus according to claim 3, wherein the longitudinal wave detection sensor that detects the longitudinal wave includes a transmission sensor and a reception sensor that are separated from each other. The transmitting sensor includes a pair of magnets having a first polarity, a coil wound around the magnet having the first polarity, and a first polarity magnet sandwiched outside the coil. The electromagnetic ultrasonic measurement device according to claim 4, comprising a second polarity magnet. The electromagnetic ultrasonic measurement apparatus according to claim 5, wherein the reception sensor includes a magnet having the first polarity and a coil wound around the magnet having the first polarity. A method for measuring a plate thickness and stress using electromagnetic ultrasonic waves, wherein the plate thickness of the material and stress applied to the material are simultaneously measured using electromagnetic ultrasonic waves. Measuring the thickness of the material assuming a velocity value of electromagnetic ultrasonic waves;
Obtaining the sound velocity in the material using the plate thickness value obtained by the plate thickness measurement;
The method of measuring a plate thickness and stress using electromagnetic ultrasonic waves according to claim 7, comprising the step of measuring a stress applied to the material from the obtained sound speed. Electromagnetic ultrasound includes transverse or longitudinal waves,
The plate thickness and stress measurement method using electromagnetic ultrasonic waves according to claim 7 or 8, comprising a step of detecting transverse waves or longitudinal waves of the electromagnetic ultrasonic waves.

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