JP6358035B2 - Measuring device, measuring method, program, and storage medium - Google Patents

Description

  In the present invention, the central solid phase ratio (hereinafter referred to as the central solid phase ratio, which is the ratio of the volume of the solid phase portion existing in the central region in the thickness direction of the object to be measured is simply referred to as “thickness direction in the object to be measured. The present invention relates to a measuring apparatus and a measuring method for measuring a central solid phase ratio of a computer, a program for causing a computer to execute the measuring method, and a computer-readable storage medium for storing the program.

  Conventionally, as a technique for measuring whether or not a liquid layer portion (molten steel portion) is present in a continuous cast slab that is an object to be measured, for example, Non-Patent Document 1, Patent Document 1, and Patent Document 2 described below are used. Technology.

First, the technique of Non-Patent Document 1 will be described.
FIG. 14 is a schematic diagram illustrating a conventional example and illustrating an example of a measurement method for measuring whether or not a liquid layer portion is present in the object to be measured.
In the technique of Non-Patent Document 1, one transmitting electromagnetic ultrasonic sensor is arranged on the surface of the object to be measured, and one receiving electromagnetic ultrasonic sensor is arranged on the back surface of the object to be measured. Send and receive. Then, in the technique of Non-Patent Document 1, using the fact that the ultrasonic velocity of the longitudinal wave is different between the solid layer portion and the liquid layer portion, after transmitting the ultrasonic wave of the longitudinal wave from the electromagnetic ultrasonic sensor for transmission, By measuring the propagation time until reception by the electromagnetic ultrasonic sensor for reception, it is determined whether or not the liquid layer portion exists inside the object to be measured.

Next, techniques of Patent Document 1 and Patent Document 2 will be described.
In Patent Document 1 and Patent Document 2, one transmitting electromagnetic ultrasonic sensor is disposed on the surface of the object to be measured, and one receiving electromagnetic ultrasonic sensor is disposed on the back surface of the object to be measured. Send and receive. And in patent document 1 and patent document 2, it is made to measure whether the liquid layer part exists in the to-be-measured object by measuring the transmittance | permeability of a transverse wave.

JP 2002-14083 A JP 2006-208393 A

Nondestructive Inspection Vol.34, No.11, p.796-803 Fundamentals and Applications of Electromagnetic Ultrasound, Kawashima Takaho Kawawa, Gakushin 19th Committee Report 9721, Coagulation 156 (1974)

  The boundary between the solid phase part and the liquid layer part inside the continuous cast slab, which is the object to be measured, may or may not have a clear interface depending on the steel type (specifically, In the case where a solid-liquid coexisting phase portion is formed between the solid phase portion and the liquid layer portion). In this solid-liquid coexisting phase part, inclusions and segregation which are bubbles and impurities accumulate, and if this remains until the end, it becomes a factor of deteriorating the quality of the product. Conventionally, in order to solve this problem, in a state where a solid-liquid coexisting phase portion exists inside the object to be measured, the object to be measured is passed through a special reduction roll to crush bubbles, inclusions, and segregation, thereby reducing harm. Technology (light reduction technology) that exists. In order to maximize the effect of this light reduction technique, it is known that light reduction should be performed in a state where the central solid fraction in the thickness direction of the object to be measured is a specific central solid fraction. Recently, there is a demand for a technique that can directly evaluate the central solid fraction in the thickness direction of the object to be measured.

  However, since the methods of Patent Document 1, Patent Document 2, and Non-Patent Document 1 described above are limited to a technique for measuring whether or not a liquid layer portion is present inside the object to be measured, It is difficult to measure the central solid fraction.

  Further, in the methods of Patent Document 1, Patent Document 2, and Non-Patent Document 1 described above, the measurement accuracy is poor due to the influence of the thickness variation of the object to be measured, and the sensor is separated from the surface of the object to be measured. Since it is also disposed on the back surface, so-called scale (iron oxide (rust)) is deposited on the sensor disposed on the back surface, and there is a problem that the maintainability of the equipment is poor.

  The present invention has been made in view of such problems, and improves the maintainability of the equipment, and measures the central solid phase ratio in the thickness direction of the object to be measured with a certain degree of accuracy in a nondestructive manner. The purpose is to provide a mechanism capable of

  As a result of intensive studies, the present inventor has conceived various aspects of the invention described below.

  The measuring apparatus according to the present invention is a measuring apparatus that measures an object to be measured, and that transmits transverse wave ultrasonic waves having a plurality of different frequencies in the thickness direction of the object to be measured from the surface of the object to be measured. A transverse wave ultrasonic wave receiving means for receiving, on the surface of the object to be measured, a transverse wave ultrasonic wave having a plurality of different frequencies propagated in a thickness direction of the object to be measured; and the transverse wave ultrasonic wave receiving means. Resonance frequency detection means for detecting a plurality of resonance frequencies in the thickness direction of the object to be measured based on the received transverse wave ultrasonic waves at each frequency, and energy for calculating an energy value of the transverse wave ultrasonic waves at the plurality of resonance frequencies An energy value calculated by the value calculating means and the energy value calculating means, wherein the energy values of the transverse ultrasonic waves at two adjacent resonance frequencies of the plurality of resonance frequencies Based on the first energy value that is the energy value of the larger value and the second energy value that is the energy value of the smaller value of the energy values of the transverse ultrasonic waves at the two adjacent resonance frequencies, Central solid fraction calculation means for calculating the central solid fraction in the thickness direction of the object to be measured.

  The measuring method of the present invention is a measuring method by a measuring device that measures a device under test, and transmits a transverse wave having a plurality of different frequencies from the surface of the device under test in the thickness direction of the device under test. An ultrasonic wave transmission step, a transverse wave ultrasonic wave reception step of receiving, at the surface of the object to be measured, a transverse wave ultrasonic wave of each of the plurality of different frequencies propagated in the thickness direction of the object to be measured; and the transverse wave ultrasonic wave A resonance frequency detecting step for detecting a plurality of resonance frequencies in the thickness direction of the object to be measured based on the transverse wave ultrasonic waves received in the reception step, and an energy value of the transverse wave ultrasonic waves at the plurality of resonance frequencies. An energy value calculating step to calculate, and energy values calculated in the energy value calculating step, and two adjacent resonances of the plurality of resonance frequencies The first energy value, which is a large energy value of the energy values of the transverse wave ultrasonic waves at the wave number, and the energy value of the smaller value of the energy values of the transverse wave ultrasonic waves at the two adjacent resonance frequencies. And a central solid fraction calculation step for calculating a central solid fraction in the thickness direction of the object to be measured based on the energy value of 2.

  A program of the present invention is a program for causing a computer to execute a measurement method by a measurement device that measures a device under test, and having a plurality of different frequencies from the surface of the device under test in the thickness direction of the device under test. A transverse wave ultrasonic wave transmitting step for transmitting a transverse wave ultrasonic wave, and a transverse wave ultrasonic wave reception for receiving the transverse wave ultrasonic wave of each of the plurality of different frequencies propagated in the thickness direction of the measured object on the surface of the measured object A resonance frequency detecting step for detecting a plurality of resonance frequencies in the thickness direction of the object to be measured based on the transverse wave ultrasonic waves of the respective frequencies received in the transverse wave ultrasonic wave reception step, and at the plurality of resonance frequencies Energy value calculating step for calculating the energy value of the transverse wave ultrasonic wave, and the energy value calculated in the energy value calculating step. A first energy value which is a larger energy value of energy values of transverse wave ultrasonic waves at two adjacent resonance frequencies of the plurality of resonance frequencies, and energy of transverse wave ultrasonic waves at the two adjacent resonance frequencies For causing a computer to execute a central solid fraction calculation step for calculating a central solid fraction in the thickness direction of the object to be measured based on a second energy value which is an energy value of a small value among the values Is.

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

  ADVANTAGE OF THE INVENTION According to this invention, while making the maintenance property of an installation favorable, the center solid-phase rate of the thickness direction in a to-be-measured object can be measured with a certain amount of accuracy without destruction.

It is sectional drawing which shows an example of the to-be-measured object measured with the measuring apparatus which concerns on embodiment of this invention. It is a figure which shows an example of schematic structure of the measuring apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the principle of what is called a resonance method. It is a figure which shows embodiment of this invention and shows the experimental result which varied the casting speed of the to-be-measured object and measured the thickness of the solid-phase part of to-be-measured object. It is a figure which shows embodiment of this invention and shows the experimental result which varied the casting speed of the to-be-measured object and measured the thickness of the solid-phase part of to-be-measured object. It is a figure explaining the relationship between the frequency of the transverse wave ultrasonic wave which propagated the to-be-measured object, and the waveform energy value when the casting speed shown in FIG. 5 is 1.25 mpm. FIG. 4 is a diagram for explaining a propagation analysis simulation of transverse wave ultrasonic waves performed on an object to be measured in which a solid-liquid coexisting phase portion is present near the center position in the thickness direction according to the embodiment of the present invention. FIG. 3 is a diagram illustrating an example of a ratio calculated by a ratio calculation unit illustrated in FIG. 2 according to the embodiment of the present invention. It is a figure for demonstrating embodiment of this invention and explaining the to-be-measured object used in the simple experiment for investigating the correspondence of the B / A parameter and the center solid phase ratio of the to-be-measured object in the thickness direction. It is a figure which shows embodiment of this invention and shows the experimental result which measured the thickness of the solid-phase part of the to-be-measured object shown in FIG. FIG. 11 is a characteristic diagram showing the embodiment of the present invention and considering the B / A parameter for the experimental result shown in FIG. 10. It is a figure which shows embodiment of this invention and shows an example of the correlation data previously stored in the correlation data storage part of FIG. It is a flowchart which shows an example of the process sequence of the measuring method by the measuring apparatus which concerns on embodiment of this invention. It is a schematic diagram which shows a prior art example and shows an example of the measuring method which measures whether a liquid layer part exists in the to-be-measured object.

  Hereinafter, embodiments (embodiments) for carrying out the present invention will be described with reference to the drawings. In the following embodiments, description will be given assuming a slab (continuous cast slab) in a continuous casting process as the object to be measured.

FIG. 1 is a cross-sectional view showing an example of an object 200 to be measured that is measured by a measuring apparatus according to an embodiment of the present invention.
As shown in FIG. 1, the DUT 200 includes a liquid phase part 201, a solid-liquid coexisting phase part 202, and a solid phase part 203 sequentially from the inside. In other words, the DUT 200 has a solid-liquid coexisting phase portion 202 inside. Here, the thickness of the DUT 200 is D. In addition, an electromagnetic ultrasonic sensor is disposed on the surface of the DUT 200, and the surface area is defined by being divided into a first surface area 210 to a third surface area 230 shown below.

  The first surface region 210 is a surface region where the liquid phase part 201, the solid-liquid coexisting phase part 202, and the solid phase part 203 exist in the thickness direction of the DUT 200. The second surface region 220 is a surface region where the solid-liquid coexisting phase portion 202 and the solid phase portion 203 exist in the thickness direction of the DUT 200. The third surface region 230 is a surface region where only the solid phase portion 203 exists in the thickness direction of the DUT 200.

FIG. 2 is a diagram illustrating an example of a schematic configuration of the measurement apparatus 100 according to the embodiment of the present invention.
The measuring apparatus 100 according to the present embodiment is an apparatus that measures the central solid phase ratio in the thickness direction of the DUT 200. As shown in FIG. 2, the measuring apparatus 100 includes an electromagnetic ultrasonic sensor 110, a transverse ultrasonic transmitting / receiving apparatus 120, an operation input apparatus 130, a control apparatus 140, and a display apparatus 150. . Here, in the example illustrated in FIG. 2, the position of the electromagnetic ultrasonic sensor 110 is fixed, and it is assumed that the DUT 200 moves from the left side to the right side of the paper by the rotation of the roll.

  As shown in FIG. 2, the electromagnetic ultrasonic sensor 110 is provided only on the surface side of the DUT 200. The electromagnetic ultrasonic sensor 110 is disposed, for example, at a position intersecting with a magnetic flux generator (not shown) made of a permanent magnet or the like that generates a magnetic flux for the DUT 200 and a magnetic flux generated from the magnetic flux generator. And a coil (not shown) to be energized.

  Based on the control of the control device 140, the transverse wave ultrasonic transmission / reception device 120 sequentially transmits, for example, an alternating current of each frequency in a predetermined frequency region including a plurality of different frequencies to the coil of the electromagnetic ultrasonic sensor 110. . As a result, an eddy current in the direction opposite to the alternating current flowing in the coil of the electromagnetic ultrasonic sensor 110 is generated in the vicinity of the inner surface of the object to be measured 200, and the eddy current and the magnetic flux generated in the object to be measured 200 are generated. A force is generated, which becomes a transverse ultrasonic vibration and propagates in the thickness direction of the object to be measured 200. Further, the transverse wave ultrasonic transmission / reception device 120 transmits the transverse wave ultrasonic wave propagated in the thickness direction (plate thickness direction) inside the DUT 200 for each frequency of the transmitted alternating current, for example, by the electromagnetic ultrasonic sensor 110. Received as an induced electromotive force generated in the coil.

  That is, the transverse wave ultrasonic transmission / reception device 120 transmits and receives transverse wave ultrasonic waves via one (identical) electromagnetic ultrasonic sensor 110 disposed on the surface of the object 200 to be measured. In the present embodiment, means for transmitting a plurality of transverse waves of different frequencies in the thickness direction of the measurement object 200 from the surface of the measurement object 200 via the electromagnetic ultrasonic sensor 110 (transverse wave ultrasonic transmission means). ) And means for receiving transverse waves of each of a plurality of different frequencies propagated in the thickness direction of the object to be measured 200 (transverse wave receiving means) on the surface of the object to be measured 200. Although the ultrasonic transmission / reception device 120 is used, for example, a mode in which the transverse wave ultrasonic wave transmission unit and the horizontal wave ultrasonic wave reception unit are performed by different devices can be applied to the present embodiment.

  The operation input device 130 is configured to be operable by the measurer, and inputs an operation input instruction from the measurer to the control device 140.

  The control device 140 comprehensively controls the operation of the measurement device 100 based on an operation input instruction or the like input from the operation input device 130. For example, when an instruction to measure the device under test 200 is input from the operation input device 130, the control device 140 controls the transmission operation and the reception operation of the transverse wave ultrasonic wave in the transverse wave ultrasonic transmitting / receiving device 120, and the transverse wave ultrasonic wave Based on the transverse wave ultrasonic wave received by the sonic wave transmitting / receiving device 120, a calculation process of the central solid phase ratio in the thickness direction of the DUT 200 is performed. In addition, the control device 140 performs control to display information such as the operation state in the measurement device 100 and the calculated center solid phase ratio in the thickness direction of the measured object 200 on the display device 150 as necessary.

  Further, as shown in FIG. 2, the control device 140 includes a resonance frequency detection unit 141, an energy value calculation unit 142, a ratio calculation unit 143, a correlation data storage unit 144, and a central solid phase ratio calculation unit 145. It is composed.

  The resonance frequency detection unit 141 detects a plurality of resonance frequencies in the thickness direction of the DUT 200 based on the transverse wave ultrasonic waves of each frequency received by the transverse wave ultrasonic transmission / reception device 120.

  The energy value calculation unit 142 calculates the energy value of the transverse ultrasonic wave at the plurality of resonance frequencies detected by the resonance frequency detection unit 141. Here, in the present embodiment, the energy value calculated by the energy value calculation unit 142, and the energy value of a larger value among the energy values of the transverse ultrasonic waves at two adjacent resonance frequencies of a plurality of resonance frequencies is calculated. The “first energy value” is defined, and the energy value of the smaller value of the energy values of the transverse ultrasonic waves at the two adjacent resonance frequencies is defined as the “second energy value”.

  For example, the ratio calculation unit 143 calculates a ratio of the second energy value calculated by the energy value calculation unit 142 to the first energy value. Here, although details will be described later, the energy value calculated by the energy value calculation unit 142 from the result of the experiment by the present inventor increases with the increase of the frequency of the transverse wave ultrasonic wave transmitted from the transverse wave ultrasonic transceiver 120. It has been found that the energy value of 1 and the second energy value are alternately repeated. At this time, for example, the ratio calculation unit 143 can take a form of calculating a ratio of an average value in the second energy value to an average value in the first energy value.

  The correlation data storage unit 144 is data indicating the correlation between the ratio of the second energy value to the first energy value and the central solid phase ratio in the thickness direction of the DUT 200, obtained in advance through experiments or the like. Store some correlation data.

  Based on the first energy value and the second energy value calculated by the energy value calculation unit 142, the central solid phase ratio calculation unit 145 calculates the central solid phase ratio in the thickness direction of the DUT 200. Specifically, the central solid fraction calculation unit 145 calculates the central solid fraction in the thickness direction of the DUT 200 according to the ratio calculated by the ratio calculation unit 143. More specifically, the central solid fraction calculation unit 145 refers to the correlation data stored in the correlation data storage unit 144, and calculates the central solid fraction corresponding to the ratio calculated by the ratio calculation unit 143. It is calculated as the central solid phase ratio in the thickness direction of the measurement object 200.

  The display device 150 displays information such as the operation state in the measurement device 100 and the calculated center solid phase ratio in the thickness direction of the measured object 200 based on the control of the control device 140. In addition, the display device 150 displays information necessary for the measurer.

Next, the principle of the so-called resonance method employed in this embodiment will be described.
FIG. 3 is a diagram for explaining the principle of the so-called resonance method.

Generally, when the thickness is twice the integral wavelength of the ultrasonic wavelength, the resonance state is reached.
Here, when the thickness of propagation of ultrasonic waves is d, the integer is n, the wavelength of the ultrasonic waves is λ, the speed of sound of the ultrasonic waves is V, and the resonance frequency is f _n , the following equation (1) holds.
2d = nλ = nV / f _n (1)

When formula (1) is arranged for the resonance frequency f _n , the following formula (2) is obtained.
f _n = nV / (2d) (2)

The resonance frequency interval Δf, which is the frequency interval between the (n + 1) th resonance frequency f _{n + 1} and the nth resonance frequency f _n , is expressed by the following equation (3).
Δf = f _{n + 1} −f _n
= (N + 1) V / (2d) -nV / (2d) = V / (2d) (3)

Here, first, the object to be measured including only the solid phase portion 203 shown in FIG. In the case of this device under test, the transverse ultrasonic wave transmitted through the electromagnetic ultrasonic sensor 110 propagates the entire thickness d of the device under test as shown in FIG. FIG. 3 (a2) is a diagram showing the relationship between the frequency of the transverse ultrasonic wave propagated through the object to be measured shown in FIG. 3 (a1) and its waveform energy value. FIG. 3A2 shows the resonance frequencies f ₁ , f ₂ , f ₃ , and f ₄ and the resonance frequency interval Δf.

Next, an object to be measured including only the solid phase portion 203 and the liquid phase portion 201 shown in FIG. Here, it is assumed that the liquid phase portion 201 exists in the central portion of the measured object in the thickness direction. In the case of this object to be measured, the transverse wave ultrasonic wave transmitted via the electromagnetic ultrasonic sensor 110 cannot penetrate the liquid phase part 201 and propagates only through the solid phase part 203 as shown in FIG. . At this time, when the thickness d of the solid phase portion 203 changes, the resonance frequency f _n also changes (see equation (2)). Therefore, the presence / absence of the liquid phase portion 201 can be detected by detecting the resonance frequency f _n . FIG. 3 (b2) is a diagram showing the relationship between the frequency of the transverse ultrasonic wave propagated through the object to be measured shown in FIG. 3 (b1) and its waveform energy value. FIG. 3B2 shows the resonance frequencies f ₁ and f ₂ and the resonance frequency interval Δf. Since the thickness d of the solid phase portion 203 of the object to be measured shown in FIG. 3 (b1) is smaller than the thickness d of the solid phase portion 203 shown in FIG. 3 (a1), the resonance frequency interval Δf shown in FIG. 3 (b2). Is a value larger than the resonance frequency interval Δf shown in FIG. 3 (a2) (see equation (3)).

Next, consider the device under test 200 shown in FIG.
In the third surface region 230 shown in FIG. 1, since only the solid phase portion 203 exists in the thickness direction of the DUT 200, the propagating shear wave ultrasonic waves are the above-described FIGS. 3 (a 1) and 3 (a 2). ).

  In the second surface region 220 shown in FIG. 1, a solid-liquid coexisting phase portion 202 and a solid phase portion 203 exist in the thickness direction of the DUT 200. Here, the solid-liquid coexistence phase portion 202 has a solid phase ratio of a value less than 100% (a liquid phase ratio is greater than 0%) to a solid phase ratio of a value greater than 0% (liquid phase ratio is 100%). It is a region that continuously changes up to a value less than). For example, the state where the solid phase ratio is 50% is a state where the solid component occupies an area of 50%, and the remaining 50% area is filled with a liquid portion. As described above, since the transverse wave ultrasonic wave cannot enter the liquid phase part 201, in the region where the solid phase ratio is 50%, it is considered that the transverse wave ultrasonic wave is transmitted through 50% and reflected by 50%. It is done.

  In the first surface region 210 shown in FIG. 1, since the liquid phase portion 201, the solid-liquid coexisting phase portion 202, and the solid phase portion 203 exist in the thickness direction of the DUT 200, the transverse wave ultrasonic wave that propagates is Although the liquid coexisting phase portion 202 permeates in accordance with the solid phase ratio, the liquid phase portion 201 exists, so that it can be considered as shown in FIGS. 3 (b1) and 3 (b2).

  Subsequently, in order to change the relative positional relationship between the first surface region 210 to the third surface region 230 shown in FIG. 1 and the electromagnetic ultrasonic sensor 110 shown in FIG. An experiment was conducted in which the thickness d of the solid phase portion 203 of the DUT 200 was measured by varying Vc. In the experiment shown below, the DUT 200 having a thickness D of 282 mm was used.

  FIG. 4 shows an embodiment of the present invention, and is a diagram showing experimental results obtained by measuring the thickness d of the solid phase portion 203 of the device under test 200 by varying the casting speed Vc of the device under test 200. In this experiment, the casting speed Vc was measured at two types of 1.1 mpm and 1.6 mpm.

  FIG. 4A shows the time taken from the measurement start timing for each casting speed Vc on the horizontal axis, and the transverse wave ultrasonic wave transmission / reception device 120 transmits / receives the transverse wave ultrasonic wave of each frequency via the electromagnetic ultrasonic sensor 110. It is the characteristic view which took the thickness d (solid phase thickness) of the solid-phase part 203 calculated by this as the vertical axis | shaft.

  As shown in FIG. 4A, when the casting speed Vc = 1.1 mpm, the average value of the calculated thickness d (solid phase thickness) of the solid phase portion 203 is the thickness D of the object 200 to be measured. Since the value is substantially the same as 282 mm, the electromagnetic ultrasonic sensor 110 is arranged in the third surface region 230 (surface region where only the solid phase portion 203 exists in the thickness direction of the DUT 200) shown in FIG. It is thought that there is. FIG. 4B shows the relationship between the frequency of the transverse ultrasonic wave propagated through the DUT 200 and the waveform energy value when the casting speed Vc is 1.1 mpm.

  Further, as shown in FIG. 4A, when the casting speed Vc = 1.6 mpm, the average value of the calculated thickness d (solid phase thickness) of the solid phase portion 203 is the thickness D of the object 200 to be measured. Therefore, the electromagnetic ultrasonic sensor 110 is arranged in the first surface region 210 (surface region where the liquid phase portion 201 exists in the thickness direction of the DUT 200) shown in FIG. It is thought that. FIG. 4C shows the relationship between the frequency of the transverse ultrasonic wave propagated through the DUT 200 and the waveform energy value when the casting speed Vc = 1.6 mpm.

  Here, as described above, the DUT 200 shown in FIG. 2 moves from the left side of the drawing to the right side of the drawing. Therefore, when the casting speed is increased, the tip portions of the liquid phase portion 201 and the solid-liquid coexisting phase portion 202 are Then, the object to be measured 200 moves to the side closer to the top of the continuous cast slab. For this reason, when the casting speed Vc = 1.6 mpm, the electromagnetic ultrasonic sensor 110 detects the first surface region 210 (surface region where the liquid phase portion 201 exists in the thickness direction of the DUT 200 shown in FIG. 1). ).

  On the other hand, when the casting speed is slowed, the tip portions of the liquid phase portion 201 and the solid-liquid coexisting phase portion 202 move to the far side from the top portion of the continuous cast slab that is the object to be measured 200. For this reason, when the casting speed Vc = 1.1 mpm, the electromagnetic ultrasonic sensor 110 has a third surface region 230 (a surface where only the solid phase portion 203 exists in the thickness direction of the DUT 200 shown in FIG. It is considered to be arranged in the area).

  FIG. 5 shows an embodiment of the present invention and is a diagram showing experimental results obtained by measuring the thickness d of the solid phase portion 203 of the device under test 200 by varying the casting speed Vc of the device under test 200. Specifically, in the experiment shown in FIG. 5, the casting speed Vc is between 1.1 mpm and 1.6 mpm used in the experiment shown in FIG. , 1.41 mpm, 1.31 mpm, 1.25 mpm, and 1.23 mpm.

  FIG. 5 shows the elapsed time from the measurement start time when the casting speed Vc = 1.41 mpm is measured and thereafter the casting speed Vc is sequentially switched to 1.31 mpm, 1.25 mpm, and 1.23 mpm. In other words, the vertical axis represents the thickness d (solid phase thickness) of the solid phase portion 203 calculated by transmitting / receiving the transverse wave ultrasonic waves of each frequency in the transverse wave ultrasonic transmitting / receiving device 120 via the electromagnetic ultrasonic sensor 110. FIG.

  When the casting speed Vc is 1.41 mpm and 1.31 mpm, the calculated average value of the thickness d (solid phase thickness) of the solid phase portion 203 is approximately half the value of 282 mm, which is the thickness D of the DUT 200. Therefore, the electromagnetic ultrasonic sensor 110 is in the first surface region 210 (surface region where the liquid phase portion 201 exists in the thickness direction of the DUT 200 (that is, the surface region with unsolidified)) shown in FIG. It is thought that it is arranged. The average value of the thickness d (solid phase thickness) of the solid phase portion 203 calculated when the casting speed Vc is 1.41 mpm is 128.1 mm, and is calculated when the casting speed Vc is 1.31 mpm. The average value of the thickness d (solid phase thickness) of the solid phase portion 203 was 139.9 mm.

  Further, when the casting speed Vc is 1.25 mpm and 1.23 mpm, the average value of the calculated thickness d (solid phase thickness) of the solid phase portion 203 is substantially equal to 282 mm which is the thickness D of the object 200 to be measured. Therefore, the electromagnetic ultrasonic sensor 110 includes the second surface region 220 (surface region where the solid-liquid coexisting phase portion 202 and the solid phase portion 203 exist in the thickness direction of the DUT 200) shown in FIG. It is considered that the third surface region 230 (region where only the solid phase portion 203 exists) is arranged in the surface region where the liquid phase portion 201 does not exist. In the experiment shown in FIG. 5, when the casting speed Vc is switched from 1.31 mpm to 1.25 mpm, the position of the electromagnetic ultrasonic sensor 110 is the surface position where the liquid phase portion 201 exists (first surface region 210). It is considered that the liquid phase portion 201 changes to a surface position where the liquid phase portion 201 does not exist (second surface region 220 or third surface region 230).

  FIG. 6 is a diagram for explaining the relationship between the frequency of the transverse ultrasonic wave propagated through the DUT 200 and the waveform energy value when the casting speed Vc shown in FIG. 5 is 1.25 mpm.

  FIG. 6A is a diagram showing the relationship between the frequency of the transverse ultrasonic wave propagated through the DUT 200 and the waveform energy value when the casting speed Vc = 1.25 mpm shown in FIG. Looking at the result of FIG. 6A, a plurality of resonance frequencies are observed with an increase in the frequency of the transverse wave ultrasonic wave propagated through the DUT 200, and a transverse wave at two adjacent resonance frequencies of the plurality of resonance frequencies. Of the energy value (waveform energy value) of the ultrasonic wave, the energy value (waveform energy value) of the first energy value 601 that is a large energy value and the energy value (waveform energy value) of the transverse wave ultrasonic wave at the two adjacent resonance frequencies It can be seen that the second energy value 602, which is a small energy value, appears alternately and repeatedly.

The inventor considered the phenomenon in which the first energy value 601 and the second energy value 602 shown in FIG. 6A appear alternately and repeatedly as follows.
Specifically, in the case of the casting speed Vc = 1.25 mpm shown in FIG. 5, the present inventor arranges the electromagnetic ultrasonic sensor 110 in the second surface region 220 shown in FIG. As shown in b), it was considered that the solid-liquid coexisting phase portion 202 was present near the center position in the thickness direction of the DUT 200. And this inventor considered the reason as follows.
As described above, in the solid-liquid coexistence phase portion 202, the transverse wave ultrasonic wave is transmitted according to the solid phase rate. For example, in the region where the solid phase ratio is 50%, the transverse wave ultrasonic wave is in a state where 50% is transmitted and 50% is reflected. When the transverse ultrasonic wave resonates at the entire thickness D (d = 282 mm) of the DUT 200 by the equation (Δf = V / (2d)) of the resonance frequency interval Δf shown in the above equation (3) (FIG. 6 ( When the transverse wave ultrasonic wave shown in b) is transmitted through the solid-liquid coexisting phase portion 202 [1]), the resonance frequency interval Δf becomes small and corresponds to the resonance frequency [1] shown in FIG. I thought. On the other hand, when the transverse ultrasonic wave resonates at a thickness approximately half the thickness D of the DUT 200 (d = 140 mm) (the transverse wave ultrasonic wave shown in FIG. 6B is reflected by the solid-liquid coexisting phase section 202 [2 )), The resonance frequency interval Δf is approximately twice the resonance frequency Δf in the case of [1] shown in FIG. 6B, and the resonance frequency [2] shown in FIG. ]. 6A, at the resonance frequency where [1] and [2] overlap, the calculated waveform energy value becomes relatively large (becomes the first energy value 601), and the resonance of only [1]. At the frequency, the calculated waveform energy value was considered to be relatively small (becomes the second energy value 602).

  Next, in order to confirm whether the above-described consideration is correct, the inventor performs a propagation analysis simulation of a transverse wave ultrasonic wave on the measurement object 200 in which the solid-liquid coexisting phase portion 202 exists near the center position in the thickness direction. went.

  FIG. 7 shows an embodiment of the present invention, and is for explaining the propagation analysis simulation of the transverse wave ultrasonic wave performed on the DUT 200 in which the solid-liquid coexisting phase portion 202 exists near the center position in the thickness direction. FIG.

Transverse wave ultrasonic wave analysis analysis simulation was performed under the following conditions.
The transmission wave transmitted from the transverse wave ultrasonic transmission / reception device 120 is a transverse wave burst wave having a time width of 200 μs as shown in FIG.
The 20 mm portion on the upper surface of the simulation model shown in FIG. 7B was used as a transverse burst wave transmitter shown in FIG.
In the simulation model shown in FIG. 7B, the total thickness of the DUT 200 is 140 mm, the thickness of the upper solid phase portion 203 is 68.5 mm, the thickness of the solid-liquid coexisting phase portion 202 near the center position is 3 mm, The thickness of the lower solid phase portion 203 was 68.5 mm.
The solid phase part 203 had a density ρ ₁ = 7.8 × 10 ⁻⁶ (kg / mm ³ ) and a shear wave velocity V ₁ = 3.2 × 10 ⁶ (mm / s).
The solid-liquid coexistence phase portion 202 had a density ρ ₂ = 7.7 × 10 ⁻⁶ (kg / mm ³ ) and a shear wave velocity V ₂ = 1.2 × 10 ⁶ (mm / s). At this time, since the transmittance of the solid-liquid coexisting phase portion 202 is t = (2ρ ₂ V ₂ ) / (ρ ₁ V ₁ + ρ ₂ V ₂ ) = 0.5, the transmittance is 50% (the reflectance is 50%). ) Is simulated.
・ Receiving wave processing is performed immediately after transmission of a 200 μs transmission wave, FFT is performed on the received wave (reception signal) in the time range of 200 μs to 1000 μs, only the transmission frequency component is extracted, and only the transmission frequency component is waveformd. Calculated by defining the energy value.
-Element size (mesh size in the case of FEM etc.) was 0.1 mm.
7B. Since the left boundary surface of the DUT 200 shown in FIG. 7B is a left / right symmetrical boundary, the actual transmitter size is 40 mm, and the right half is analyzed to shorten the analysis time. did.

  FIG. 7C is a diagram illustrating the relationship between the frequency of the transverse wave ultrasonic wave and the waveform energy value obtained as a result of the above-described propagation analysis simulation of the transverse wave ultrasonic wave. From FIG. 7C, it can be seen that there is a characteristic that the resonance frequency at which the waveform energy value is relatively large and the resonance frequency at which the waveform energy value is relatively small are alternately measured. A result equivalent to the experimental result shown in FIG. That is, from the result of the transverse wave ultrasonic wave propagation simulation described with reference to FIG. 7, the phenomenon in which the first energy value 601 and the second energy value 602 shown in FIG. It was confirmed that the above-described consideration that the solid-liquid coexisting phase portion 202 exists near the center position in the thickness direction of the DUT 200 is correct.

  FIG. 8 is a diagram for explaining an example of a ratio calculated by the ratio calculation unit 143 shown in FIG. 2 according to the embodiment of the present invention.

  FIG. 8A shows a view similar to FIG.

  FIG. 8B shows a view similar to FIG. At this time, the parameter A was an average value of the first energy values 601, and the parameter B was an average value of the second energy values 602.

The ratio of parameter B to parameter A was defined as the B / A parameter. That is, in this example, the B / A parameter is applied as the ratio calculated by the ratio calculation unit 143.
FIG. 8C is a diagram in which the vertical axis represents the B / A parameter for the experimental results shown in FIG. In FIG. 8C, when the casting speed Vc is changed as shown in FIG. 8A, the central solid fraction in the thickness direction of the DUT 200 should also be changed. It can be seen that the value of the B / A parameter also changes corresponding to the change.

  Next, a simple experiment for examining the correspondence between the B / A parameter and the central solid phase ratio in the thickness direction of the DUT 200 was performed.

  FIG. 9 shows an embodiment of the present invention, and is a diagram for explaining the object to be measured used in a simple experiment for examining the correspondence between the B / A parameter and the central solid phase ratio in the thickness direction of the object to be measured. It is. A mold having a hole with a vertical length of 150 mm and a width of 250 mm was prepared, and molten steel was poured into the mold, and the one that gradually solidified from the outside was used as the object to be measured. Further, in order to grasp the phase state of the object to be measured, a first thermocouple, a second thermocouple, and a third thermocouple as shown in FIG. 9 were embedded in the object to be measured. At this time, the first thermocouple, the second thermocouple, and the third thermocouple were arranged at a position 40 mm from the bottom of the mold. In the measurement by the electromagnetic ultrasonic sensor 110, the longitudinal direction of the object to be measured shown in FIG. 9 is the thickness direction of the object to be measured, and only the mold part (side surface of the mold) on the lower surface of the object to be measured shown in FIG. The measurement was performed with the electromagnetic ultrasonic sensor 110 brought close to the lower surface of the object to be measured.

  FIG. 10 shows the embodiment of the present invention and is a diagram showing experimental results obtained by measuring the thickness d of the solid phase portion 203 of the object to be measured shown in FIG.

10A, the horizontal axis represents the time from the start of pouring molten steel into the mold shown in FIG. 9, and the vertical axis represents the calculated thickness d (solid phase thickness) of the solid phase portion 203 of the measured object. Is shown. Specifically, in FIG. 10A, the thickness d (solid phase thickness) of the solid phase portion 203 of the measured object calculated from the measured values of the first to third thermocouples shown in FIG. 9 is indicated by a solid line. Then, the thickness d of the solid phase portion 203 (fixed) calculated by propagating the transverse ultrasonic wave through the electromagnetic ultrasonic sensor 110 (EMAT) in the thickness direction of the object to be measured (vertical direction having a length of 150 mm in FIG. 9). The phase thickness is indicated by black circles (●). The solid line of the thickness d (solid phase thickness) of the solid phase portion 203 is calculated as follows. The solid phase thickness d is expressed by the following approximate expression (4), where T is the elapsed time (seconds) from the completion time of molten steel injection into the mold and K is the thermal conductivity constant. For the coefficient K, t is the time when the thermocouple measurement temperature at the depth d _thermo from the sensor side of the first to third thermocouples becomes TS (solidification completion temperature), and (t, d _thermo ) is The coefficient K is determined by the method of least squares so as to fit (T, d) in the equation (4), and the value is used. TS is set based on a database in which the solidification completion temperature TS is uniquely determined according to the steel type (component).
d = K√ (T / 60) (4)
In the experiment shown in FIG. 10A, as described above, the electromagnetic ultrasonic sensor 110 is arranged on the lower surface of the part to be measured shown in FIG. 9, and the transverse ultrasonic wave is propagated in the longitudinal direction having a length of 150 mm in FIG. I let you. That is, in the experiment shown in FIG. 10A, the total thickness of the part to be measured is 150 mm.

  FIG. 10B is a diagram showing the relationship between the frequency of the transverse ultrasonic wave propagated through the object to be measured and the waveform energy value in the measurement value 1001 shown in FIG. As shown in FIG. 10B, the resonance frequency interval Δf is a large value of 33 kHz, and the measured value 1001 is calculated to have a solid phase thickness of about 38 mm according to the expression (3). This is a state in which the phase part 201 exists.

  FIG. 10C is a diagram showing the relationship between the frequency of the transverse ultrasonic wave propagated through the object to be measured and the waveform energy value in the measurement value 1002 shown in FIG. As shown in FIG. 10 (c), the resonance frequency interval Δf is a small value of 7.8 kHz, and the measured value 1002 is calculated as about 150 mm by the equation (3). In this case, the inside of the object to be measured is calculated. Is a state where only the solid phase portion 203 exists.

  FIG. 11 is a characteristic diagram showing the embodiment of the present invention and considering the B / A parameter for the experimental result shown in FIG.

  FIG. 11A shows a diagram similar to FIG. 8B and is a diagram for explaining the B / A parameter.

In FIG. 11 (b), the horizontal axis represents the time from the start of pouring molten steel into the mold shown in FIG. 9, and the vertical axis represents the calculated thickness d (solid phase thickness) of the solid phase portion 203 of the measured object. , And the calculated percentage of the solid phase in the thickness direction in the measured object and% obtained by multiplying the B / A parameter by 100. Specifically, in FIG. 11B, as in FIG. 10A, the thickness d () of the solid phase portion 203 of the measured object calculated from the measured values of the first to third thermocouples shown in FIG. (Solid phase thickness) is shown by a solid line. Further, in FIG. 11B, the central solid fraction in the thickness direction of the measurement object calculated from the measured values of the first to third thermocouples shown in FIG. The percentage obtained by multiplying the B / A parameter calculated by propagating the transverse ultrasonic wave in the thickness direction of the object to be measured (longitudinal direction of 150 mm in FIG. 9) by 100 is indicated by a black diamond point (♦). Yes. At this time, according to Non-Patent Document 2 described above, the central solid phase ratio can be calculated using the following equation (5).
Central solid fraction (%) = (TL−T) / (TL−TS) × 100 (5)
In this equation (5), TL is a solidification start temperature and TS is a solidification completion temperature, which is a value uniquely determined by the composition of the steel component. In the equation (5), T is the temperature at the center of the object to be measured, which is 150 mm thick, measured by a thermocouple. The equation (5) is known as the equation of Kawawa et al.

  From the result shown in FIG. 11 (b), when the B / A parameter is 50% or more, the calculated B / A parameter (%) and the central solid fraction in the thickness direction of the object to be measured substantially coincide. I understood.

Therefore, regardless of the value of the B / A parameter, it is considered that the B / A parameter and the central solid fraction in the thickness direction of the object to be measured match, and in this embodiment, the correlation data storage unit 144 in FIG. The data shown in FIG. 12 is applied as the correlation data stored in advance.
FIG. 12 is a diagram illustrating an example of correlation data stored in advance in the correlation data storage unit 144 of FIG. 2 according to the embodiment of this invention. In FIG. 12, the horizontal axis indicates the B / A parameter that is the ratio of the second energy value (B) to the first energy value (A), and the vertical axis indicates the center fixation in the thickness direction of the DUT 200. Indicates the phase rate. If the correlation data shown in FIG. 12 is used, the central solid phase ratio in the thickness direction of the DUT 200 can be obtained by calculating the B / A parameter.

Next, the processing procedure of the measuring method by the measuring apparatus 100 according to the present embodiment will be described.
FIG. 13 is a flowchart illustrating an example of a processing procedure of a measurement method performed by the measurement apparatus 100 according to the embodiment of the present invention. It is assumed that correlation data as shown in FIG. 12 has already been stored in the correlation data storage unit 144 of FIG. 2 at the time of starting the processing according to the flowchart of FIG.

  First, in step S <b> 1, the transverse wave ultrasonic transmission / reception apparatus 120 in FIG. 2 is measured under the control of the control apparatus 140 via the electromagnetic ultrasonic sensor 110 disposed at a point on the surface of the measurement object 200. A plurality of transverse ultrasonic waves having different frequencies are sequentially transmitted and received in the thickness direction of the object 200. Specifically, first, the transverse ultrasonic transmission / reception device 120 receives the transverse ultrasonic wave propagated in the thickness direction of the DUT 200 after transmitting the transverse ultrasonic wave having the first frequency. Next, the transverse wave ultrasonic transmitting / receiving apparatus 120 receives the transverse wave ultrasonic wave propagated in the thickness direction of the DUT 200 after transmitting the transverse wave ultrasonic wave having the second frequency at a predetermined frequency interval from the first frequency. . Next, the transverse wave ultrasonic transmitting / receiving apparatus 120 receives the transverse wave ultrasonic wave propagated in the thickness direction of the DUT 200 after transmitting the transverse wave ultrasonic wave having a predetermined frequency interval from the second frequency. . Thereafter, the transverse ultrasonic transmission / reception device 120 performs the same processing over a predetermined frequency region. Here, the frequency region (predetermined frequency region) of the transverse wave ultrasonic wave to be transmitted / received is, for example, the control device 140 with the total thickness D of the object 200 to be measured and the approximate value of the sound velocity in the object 200 to be measured by the transverse wave ultrasonic wave. Is set so that at least two resonance frequencies are included.

  Subsequently, in step S2, the resonance frequency detection unit 141 in FIG. 2 performs a plurality of resonances in the thickness direction of the DUT 200 based on the transverse wave ultrasonic waves of each frequency received by the transverse wave ultrasonic transmitting / receiving apparatus 120 in step S1. Detect frequency.

  Subsequently, in step S3, the energy value calculation unit 142 in FIG. 2 calculates the energy values of the transverse ultrasonic waves at a plurality of resonance frequencies detected by the resonance frequency detection unit 141 in step S2. Here, in the energy value calculated in step S3, the energy value of the larger value of the energy values of the transverse ultrasonic waves at two adjacent resonance frequencies of the plurality of resonance frequencies is set as the first energy value, and the adjacent energy values are calculated. The energy value of the smaller value among the energy values of the transverse ultrasonic waves at the two resonance frequencies is set as the second energy value.

  Subsequently, in step S4, the ratio calculation unit 143 in FIG. 2 calculates the ratio of the second energy value calculated by the energy value calculation unit 142 in step S3 to the first energy value. Specifically, the ratio calculation unit 143 calculates the B / A parameter described above with reference to FIG. 8 as the ratio to be calculated.

  Subsequently, in step S5, the central solid phase ratio calculation unit 145 in FIG. 2 performs the central solid phase in the thickness direction of the DUT 200 according to the B / A parameter that is the ratio calculated by the ratio calculation unit 143 in step S4. Calculate the rate. More specifically, the central solid fraction calculation unit 145 refers to the correlation data shown in FIG. 12 stored in the correlation data storage unit 144, and the B / A calculated by the ratio calculation unit 143 in step S4. The central solid fraction corresponding to the parameter is calculated as the central solid fraction in the thickness direction of the DUT 200. For example, when the B / A parameter calculated in step S4 is 0.5, the central solid fraction calculation unit 145 refers to the correlation data shown in FIG. The central solid phase ratio is calculated as 50%.

  Subsequently, in step S6, the control device 140 of FIG. 2 performs control to display information on the central solid phase ratio in the thickness direction of the DUT 200 calculated in step S5 on the display device 150.

  When the process of step S6 ends, the process of the flowchart shown in FIG. 13 ends.

According to the present embodiment, the first energy value having a larger value among the energy values of the transverse wave ultrasonic waves at the two adjacent resonance frequencies of the plurality of detected resonance frequencies, and the transverse wave excess at the two adjacent resonance frequencies. Since the central solid phase ratio in the thickness direction of the object to be measured 200 is calculated on the basis of the second energy value that is the smaller value of the energy values of the sound waves, the thickness direction in the object to be measured 200 is nondestructive. Can be measured with a certain degree of accuracy.
Furthermore, according to the present embodiment, transverse ultrasonic waves are sequentially transmitted / received via one electromagnetic ultrasonic sensor 110 arranged at a certain point on the surface of the object 200 to be measured. Since the phase ratio is measured, it is possible to improve the maintainability of the equipment as compared with the case where the electromagnetic ultrasonic sensors are arranged and measured on both the front surface and the back surface of the object to be measured shown in FIG. it can.

(Other embodiments)
In the above-described embodiment, the example in which the B / A parameter is applied as the ratio calculated by the ratio calculation unit 143 in FIG. 2 is shown, but the present invention is not limited to this form. For example, as an example, a mode in which A / B parameters are used as the ratio calculated by the ratio calculation unit 143 in FIG. 2 is also applicable. In this case, as the correlation data stored in advance in the correlation data storage unit 144 shown in FIG. 12, the correlation between the A / B parameter and the central solid fraction in the thickness direction of the DUT 200 is shown. It takes the form of applying the data shown.

The present invention can also be realized by executing the following processing.
That is, software (program) that realizes the function of the measurement apparatus 100 of the above-described embodiment is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus. This is a process of reading and executing a program. This program and a computer-readable recording medium storing the program are included in the present invention.

  It should be noted that each of the embodiments of the present invention described above is merely an example of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. Is. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

DESCRIPTION OF SYMBOLS 100: Measuring apparatus, 110: Electromagnetic ultrasonic sensor, 120: Transverse ultrasonic transmission / reception apparatus, 130: Operation input apparatus, 140: Control apparatus, 141: Resonance frequency detection part, 142: Energy value calculation part, 143: Ratio calculation part 144: correlation data storage unit, 145: central solid phase ratio calculation unit, 150: display device, 200: object to be measured, 201: liquid phase unit, 202: solid-liquid coexisting phase unit, 203: solid phase unit

Claims (9)

A measuring device for measuring an object to be measured,
A transverse wave ultrasonic wave transmission means for transmitting a plurality of transverse wave ultrasonic waves of different frequencies in the thickness direction of the object to be measured from the surface of the object to be measured;
A transverse wave ultrasonic wave receiving means for receiving a transverse wave ultrasonic wave of each of the plurality of different frequencies propagated in the thickness direction of the object to be measured at the surface of the object to be measured;
Resonance frequency detection means for detecting a plurality of resonance frequencies in the thickness direction of the object to be measured based on the transverse wave ultrasonic waves of the respective frequencies received by the transverse wave ultrasonic wave reception means;
Energy value calculating means for calculating energy values of transverse ultrasonic waves at the plurality of resonance frequencies;
A first energy value which is an energy value calculated by the energy value calculating means and which is an energy value of a larger value of energy values of transverse ultrasonic waves at two adjacent resonance frequencies of the plurality of resonance frequencies; Based on the second energy value, which is a smaller energy value of the energy values of the transverse wave ultrasonic waves at the two adjacent resonance frequencies, the central solid phase ratio in the thickness direction of the object to be measured is calculated. And a central solid phase ratio calculating means. A ratio calculating means for calculating a ratio of the second energy value to the first energy value;
The measuring apparatus according to claim 1, wherein the central solid phase ratio calculating unit calculates the central solid phase ratio according to the ratio calculated by the ratio calculating unit. The energy value calculated by the energy value calculating unit is alternately repeated between the first energy value and the second energy value as the frequency increases.
The measurement apparatus according to claim 2, wherein the ratio calculation unit calculates a ratio of an average value in the second energy value to an average value in the first energy value. Correlation data storage means for storing correlation data which is data indicating the correlation between the ratio of the second energy value to the first energy value and the central solid phase ratio;
The central solid fraction calculation means calculates the central solid fraction corresponding to the ratio calculated by the ratio calculation means with reference to the correlation data. The measuring device described.   5. The transverse wave ultrasonic wave transmitting means and the transverse wave ultrasonic wave receiving means respectively transmit and receive the transverse wave ultrasonic wave via the same electromagnetic ultrasonic sensor. The measuring device according to any one of the above.   The measurement apparatus according to claim 1, wherein the object to be measured has a solid-liquid coexisting phase portion therein. A measuring method using a measuring device for measuring an object to be measured,
A transverse wave ultrasonic wave transmitting step of transmitting a plurality of transverse wave ultrasonic waves having different frequencies in the thickness direction of the object to be measured from the surface of the object to be measured;
A transverse wave ultrasonic wave receiving step of receiving transverse wave ultrasonic waves of each of the plurality of different frequencies propagated in the thickness direction of the object to be measured at the surface of the object to be measured;
Resonance frequency detection step of detecting a plurality of resonance frequencies in the thickness direction of the object to be measured based on the transverse wave ultrasonic waves of each frequency received in the transverse wave ultrasonic wave reception step;
An energy value calculating step of calculating an energy value of transverse ultrasonic waves at the plurality of resonance frequencies;
A first energy value which is an energy value calculated in the energy value calculating step and which is an energy value of a larger value among energy values of transverse ultrasonic waves at two adjacent resonance frequencies of the plurality of resonance frequencies; Based on the second energy value, which is a smaller energy value of the energy values of the transverse wave ultrasonic waves at the two adjacent resonance frequencies, the central solid phase ratio in the thickness direction of the object to be measured is calculated. And a central solid phase ratio calculating step. A program for causing a computer to execute a measurement method by a measurement device for measuring an object to be measured,
A transverse wave ultrasonic wave transmitting step of transmitting a plurality of transverse wave ultrasonic waves having different frequencies in the thickness direction of the object to be measured from the surface of the object to be measured;
A transverse wave ultrasonic wave receiving step of receiving transverse wave ultrasonic waves of each of the plurality of different frequencies propagated in the thickness direction of the object to be measured at the surface of the object to be measured;
Resonance frequency detection step of detecting a plurality of resonance frequencies in the thickness direction of the object to be measured based on the transverse wave ultrasonic waves of each frequency received in the transverse wave ultrasonic wave reception step;
An energy value calculating step of calculating an energy value of transverse ultrasonic waves at the plurality of resonance frequencies;
A first energy value which is an energy value calculated in the energy value calculating step and which is an energy value of a larger value among energy values of transverse ultrasonic waves at two adjacent resonance frequencies of the plurality of resonance frequencies; Based on the second energy value, which is a smaller energy value of the energy values of the transverse wave ultrasonic waves at the two adjacent resonance frequencies, the central solid phase ratio in the thickness direction of the object to be measured is calculated. A program for causing a computer to execute the central solid fraction calculation step.   A computer-readable storage medium storing the program according to claim 8.

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