JP2015078910A - Ultrasonic measuring device and calibration method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable calibration of a measured value of an analyte for aging of a thin film ultrasonic vibrator while being installed in the analyte with simple and low cost means.SOLUTION: An ultrasonic vibrator 12A holds a piezoelectric substance 16 between an upper electrode 18 and a lower electrode 20, consists of a piezoelectric element 14 having the film thickness in micron unit and a calibration plate 22 fastened to the lower electrode 20, and is fixed on the surface of a pipeline T via a contact medium 24. The waveform of a reflection wave obtained by reflecting an ultrasonic pulse transmitted from the ultrasonic vibrator 12A with the pipeline T and the calibration plate 22 is displayed on a display part 12. The calibration plate 22 includes known plate thickness and material, and calibrates a temporal axis and a signal level of a measuring device including the ultrasonic vibrator 12A by using the waveform and temporal axis of the reflection wave reflected by the calibration plate 22.

Description

  The present invention relates to an ultrasonic measurement apparatus having an ultrasonic transducer composed of a thin film piezoelectric element, and capable of calibrating the ultrasonic transducer with simple means, and a calibration method thereof.

  There is an inspection method using ultrasonic waves as a method for inspecting a flaw or a thinning state of a pipe of a power plant or the like. This method irradiates a subject with an ultrasonic wave, receives a reflected wave, and grasps a scratch and a thinning state from the waveform. As a means for generating ultrasonic waves, a piezoelectric body having a piezoelectric effect is used. In other words, an ultrasonic transducer composed of a piezoelectric element having a piezoelectric body sandwiched between a lower electrode and an upper electrode is used, and an ultrasonic wave is transmitted to the subject by applying a voltage to the ultrasonic transducer. Yes.

The ultrasonic wave transmitted to the subject is reflected at the scratch or boundary of the subject. The reflected wave is received by the receiver, converted into a high-frequency voltage, and the waveform of the high-frequency voltage is displayed with a cathode ray tube, so that it is possible to know the presence / absence, location, and size of defects and thinning.
Ultrasonic transducers must be calibrated for sensitivity and time axis because the signal level decreases and the secular change of the time axis for transmitting signals occurs. In the case of an ultrasonic transducer that performs wall thickness measurement, calibration is generally performed by measuring a calibration piece having a known plate thickness before and after measurement. In addition, these calibrations are required to be performed at regular intervals according to standards.

  Patent Document 1 discloses a method for calibrating a flow meter using ultrasonic waves. The flow rate of the fluid to be measured flowing through the flow path is calculated based on the propagation time of the ultrasonic wave propagating through the flow path. Conventionally, the measurement start point of the propagation time is used as the input timing of the drive signal input to the ultrasonic transducer. In this case, correction is possible as long as the delay time from the input timing of the drive signal to the timing at which the ultrasonic wave is released to the fluid to be measured is constant, but correction is impossible if the delay time changes over time. Become. Therefore, in Patent Document 1, the delay time is measured periodically, and the secular change occurs by subtracting the delay time to from the measurement time tx until the ultrasonic wave reaches the receiving unit from the input timing of the drive signal. However, the propagation time can be measured accurately.

  In recent years, thin-film ultrasonic vibrators having high temperature heat resistance have been developed. In this ultrasonic transducer, a lower electrode, an upper electrode, and a piezoelectric body are formed in a thin film form in units of microns, and are attached to the surface of an object such as a pipe. As a result, it becomes possible to constantly monitor for a long period of time of one year or more. Patent Document 2 discloses such a thin-film ultrasonic transducer.

JP 2008-164465 A JP 2013-098508 A

The calibration means disclosed in Patent Document 1 has a problem that it requires a complicated measurement circuit and a correction circuit and is expensive.
Also, in order to achieve long-term, high-accuracy continuous monitoring, it is necessary to suppress errors caused by the work of removing or re-installing the sensor from the subject for calibration. The sensor must be removed from the subject. , It is better to always install. For this reason, the calibration method using the calibration piece having the known thickness and material as described above cannot be adopted.

  An object of the present invention is to make it possible to calibrate a thin-film ultrasonic transducer while it is installed on a subject by simple and low-cost means in view of the problems of the prior art.

  The ultrasonic inspection apparatus of the present invention includes a piezoelectric body sandwiched between a lower electrode and an upper electrode, is fixed to the surface of the subject, transmits ultrasonic waves toward the subject, and is reflected by the subject. The present invention is applied to an ultrasonic measurement apparatus having a thin film ultrasonic transducer that receives a reflected wave and converts it into a high-frequency voltage, and a display unit that displays the waveform of the high-frequency voltage.

  In order to achieve the above-mentioned object, a plate-like calibration member having a known plate thickness and material and fixed to the ultrasonic transducer and through which the ultrasonic wave transmitted from the ultrasonic transducer propagates is provided. A measuring device including an ultrasonic transducer based on a reflected wave of an ultrasonic wave reflected by a member, and information relating to a waveform of a high-frequency voltage of the reflected wave displayed on the display unit and a time axis (position on the time axis) This calibrates the time axis and signal level.

  The propagation speed of the ultrasonic wave propagating through the calibration member varies depending on the material of the calibration member. In the present invention, the waveform and time axis of the reflected wave reflected from the calibration member having a known plate thickness and material are displayed on the display unit together with the waveform and time axis of the reflected wave reflected from the subject. The waveform and time axis of the reflected wave reflected from the calibration member having a known plate thickness and material are known. By using the waveform and time axis of this reflected wave and comparing the known waveform and time axis with the waveform and time axis of the reflected wave of the subject, the ultrasonic transducer is included at the same time as detecting the thickness of the subject. Calibration of the measuring device can be performed.

In this way, with a simple and low-cost means that simply incorporates a calibration member having a known plate thickness and material into the ultrasonic transducer, the thin-film ultrasonic transducer remains attached to the subject such as a pipe. The calibration of the measuring device including the ultrasonic transducer becomes possible. Further, calibration can be performed at the same time as ultrasonic measurement on the subject.
Note that the calibration member may be made of a heat resistant material, for example, when the subject has a high temperature or is placed in a high temperature atmosphere.

In addition, the speed of the ultrasonic wave propagating through the substance varies depending on the temperature of the substance. Therefore, as one embodiment of the present invention, the temperature sensor for detecting the temperature of the subject and the calibration member, and the ultrasonic propagation velocity between the subject and the calibration member caused by the difference in material and temperature between the subject and the calibration member A correction unit that cancels the difference, and calibrates the time axis and the signal level of the measuring device including the ultrasonic transducer based on the ultrasonic propagation velocity of the subject and the calibration member corrected by the correction unit. Can be.
Thereby, even when the material and temperature environment of the subject and the calibration member are different, accurate calibration data can be collected.

  As an embodiment of the present invention, the plate thickness and material of the calibration member can be set to a plate thickness and material in which the reflected wave of the subject and the reflected wave of the calibration member do not overlap on the time axis of the display unit. This makes it possible to clearly display both the waveform of the reflected wave of the subject and the reflected wave of the calibration member and the time axis at the time of ultrasonic measurement on the subject, so that the measurement of the subject is not adversely affected.

As an embodiment of the apparatus of the present invention, the thickness and the material of the calibration member are set such that the amplitude of the reflected wave of the calibration member is so small that the reflected wave of the calibration member does not interfere with the grasp of the waveform and time axis of the reflected wave of the subject. The thickness and material can be used. This makes it possible to clearly display both the waveform of the reflected wave of the subject and the reflected wave of the calibration member and the time axis at the time of ultrasonic measurement on the subject, so that the measurement of the subject is not adversely affected.
As the material of the calibration member, for example, metal or resin can be used. When using a resin in a high temperature atmosphere, a heat resistant resin is used.

If the material of the calibration member is the same as the material of the subject, the propagation speed of the ultrasonic wave propagating through the subject and the propagation speed of the ultrasonic wave propagating through the calibration member are the same. This makes it easy to estimate the position on the time axis of the reflected wave of the calibration member displayed on the display unit.
For example, when the subject is a pipe used in a power plant, and the material of the pipe is low alloy steel, high Cr steel, stainless steel, Ni-base alloy, etc., the same materials as these are used.

  As one embodiment of the apparatus of the present invention, the calibration member can be disposed between the lower electrode and the subject. As a result, the calibration member does not interfere with the arrangement of the upper electrode and the temperature conditions of the calibration member and the subject can be made substantially the same. The propagation speed of ultrasonic waves propagating a substance is affected not only by the material of the substance but also by the temperature. In this embodiment, by making the temperature of the calibration member and the temperature of the subject substantially the same, the position of the reflected wave of the subject displayed on the display unit and the reflected wave of the calibration member on the time axis is determined by both plates. It is uniquely determined by the thickness. Therefore, it becomes easy to display so as to eliminate the overlapping of the reflected waves of both.

  As one embodiment of the apparatus of the present invention, the calibration member can be fixed to the surface of the upper electrode. This eliminates the calibration member between the piezoelectric element and the subject, so that attenuation of the ultrasonic wave until the ultrasonic wave reaches the subject can be reduced. Therefore, the reflected wave reflected from the subject can be measured with high sensitivity.

As one embodiment of the apparatus of the present invention, the lower electrode can be constituted by a plate-like calibration member having a known plate thickness and material. Thus, by using the lower electrode also as a calibration member, it is not necessary to provide a separate calibration member, and the configuration of the ultrasonic transducer can be simplified and reduced in cost.
In this case, the lower electrode may have a thickness and a material so that the reflected wave of the calibration member and the reflected wave of the subject do not overlap on the time axis of the display unit. This makes it possible to clearly grasp both the waveform of the reflected wave of the subject and the reflected wave of the calibration member and the time axis during ultrasonic measurement of the subject. As a result, it is possible to accurately measure the scratch and thickness of the subject without adversely affecting the measurement of the subject.

  The ultrasonic measurement apparatus calibration method of the present invention includes a piezoelectric body sandwiched between a lower electrode and an upper electrode, is fixed to the surface of the subject, transmits ultrasonic waves toward the subject, The present invention is applied to an ultrasonic measurement apparatus having an ultrasonic transducer that receives a reflected wave reflected by the laser beam and converts it into a high-frequency voltage and a display unit that displays a waveform of the high-frequency voltage.

  In order to achieve the above object, the method of the present invention includes a first step of propagating ultrasonic waves to a subject and a plate-like calibration member having a known plate thickness and material and fixed to the ultrasonic transducer, The second step of receiving the reflected ultrasonic waves reflected by the specimen and the calibration member by the ultrasonic transducer and converting them to a high frequency voltage, and displaying the waveform of the high frequency voltage of the subject and the calibration member on the display unit for calibration And a third step of calibrating the time axis and the signal level of the measuring device including the ultrasonic transducer from the information on the waveform of the high frequency voltage of the member and the time axis.

In the method of the present invention, when the subject is irradiated with ultrasonic waves from the ultrasonic transducer, the waveform and time axis of the reflected wave displayed from the subject displayed on the display unit, and a calibration member having a known plate thickness and material are used. By comparing the waveform of the reflected wave and the time axis, the measurement apparatus including the ultrasonic transducer can be calibrated simultaneously with the measurement of the thickness of the subject.
Therefore, the ultrasonic transducer can be reflected from the subject while being attached to the subject such as a pipe with a simple and low-cost means by simply incorporating a calibration member having a known thickness and material into the ultrasonic transducer. Calibration of reflected waves is possible.

As one embodiment of the method of the present invention, the temperature detection step of detecting the temperature of the subject and the calibration member, and the ultrasonic propagation speed of the subject and the calibration member caused by the difference in material and temperature between the subject and the calibration member A correction step for correcting the difference, and in the third step, based on the ultrasonic propagation velocity of the subject and the calibration member corrected in the correction step, the time axis and signal of the measuring device including the ultrasonic transducer The level can be calibrated.
Thereby, even when the material and temperature environment of the subject and the calibration member are different, accurate calibration data can be collected.

  According to the present invention, by incorporating a calibration member into a thin-film ultrasonic transducer, a measurement apparatus including the ultrasonic transducer can be easily and inexpensively installed on the subject. Further, calibration can be performed simultaneously with measurement of the subject.

1 is a configuration diagram of an ultrasonic measurement apparatus according to a first embodiment of the present invention. It is sectional drawing of the ultrasonic transducer | vibrator of the said ultrasonic measurement apparatus. It is a perspective view of the above-mentioned ultrasonic vibrator fixed to piping. It is a flowchart which shows the processing flow by the said ultrasonic measuring device. (A) shows the waveform of the reflected wave measured by the conventional ultrasonic transducer, and (B) and (C) are diagrams showing the waveform of the reflected wave measured by the ultrasonic transducer of the first embodiment. . It is a flowchart which shows the calibration time of the said ultrasonic transducer | vibrator. It is sectional drawing of the ultrasonic transducer | vibrator which concerns on 2nd Embodiment of this invention. (A) And (B) is a diagram which shows the waveform of the reflected wave measured with the ultrasonic transducer | vibrator of 2nd Embodiment. It is sectional drawing of the ultrasonic transducer | vibrator which concerns on 3rd Embodiment of this invention. It is a diagram which shows the waveform of the reflected wave measured with the ultrasonic transducer | vibrator of 3rd Embodiment. It is a diagram which shows the relationship between temperature and an ultrasonic wave propagation velocity.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

(Embodiment 1)
Next, a first embodiment of the present invention will be described with reference to FIGS. The present embodiment is an example of inspecting a flaw or a thinning state of piping used in a power plant. FIG. 1 shows a configuration of an ultrasonic measurement apparatus 10 according to the present embodiment. In FIG. 1, an ultrasonic transducer 12A is fixed to the surface of a pipe T that is a subject. The ultrasonic transducer 12 </ b> A includes a piezoelectric element 14 and a calibration plate 22 fixed to the piezoelectric element 14. The piezoelectric element 14 has a film-shaped piezoelectric body 16 having a quadrangular shape, a silver film-shaped upper electrode 18 deposited on the upper surface of the piezoelectric body 16, and a larger area than the piezoelectric body 16. And a lower electrode 20 in the form of a square film deposited on the lower surface of the substrate.

  The piezoelectric body 16 is made of ceramic and fixed to the surface of the lower electrode 20 by baking. The lower electrode 20 is made of stainless steel. The piezoelectric body 16, the upper electrode 18, and the lower electrode 20 each have a thickness in units of microns. A calibration plate 22 is fixed to the lower surface of the lower electrode 20. The calibration plate 22 preferably has the same shape and the same area as the lower electrode 20 and is made of the same material as the pipe T. For example, when the pipe T is made of low alloy steel, high Cr steel, stainless steel, Ni-base alloy or the like, the calibration plate 22 is also made of these materials.

As shown in FIG. 2, the ultrasonic transducer 12 </ b> A is fixed to the surface of the pipe T through the contact medium 24 with the calibration plate 22 in contact with the heat-resistant contact medium 24. For example, the ultrasonic transducer 12A is fixed to the surface of the pipe T by covering the ultrasonic transducer 12A with an adhesive film. Or it is made to adhere to piping T using contact medium 24 which has adhesiveness.
As shown in FIG. 3, the ultrasonic transducer 12 </ b> A is fixed over a plurality of locations in a region of the pipe T that requires inspection for the presence or absence of a flaw and a thinning state.

  The upper electrode 18 and the lower electrode 20 are connected to the flaw detector body 30 by conducting wires 26 and 28, respectively. The conducting wires 26 and 28 are bundled with a cord 29. An ultrasonic pulse is transmitted from the ultrasonic transducer 12 </ b> A to the pipe T and the calibration plate 22. Ultrasonic waves have a characteristic of reflecting between media having different acoustic characteristics. Therefore, the ultrasonic pulse transmitted from the ultrasonic transducer 12 </ b> A is reflected by the lower electrode 20, the calibration plate 22, and the front and back surfaces of the pipe T. Each reflected wave is received by the ultrasonic transducer 12A and converted into a high-frequency voltage. The flaw detector main body 30 has a display unit 32. The high-frequency voltage is sent to the display unit 32 via the conductors 26 and 28, and the waveform of the high-frequency voltage is displayed on the display unit 32 with the horizontal axis as the time axis.

  A thermocouple 34 is attached to the surface of the pipe T adjacent to the region where the ultrasonic transducer 12A is fixed. The temperature detected by the thermocouple 34 is transmitted to the flaw detector main body 30 via the cable 36. The propagation speed of the ultrasonic pulse propagating through the calibration plate 22 is determined not only by the thickness and material of the calibration plate 22 but also by the temperature of the calibration plate 22. FIG. 11 is an example of a diagram showing the relationship between the temperature and propagation speed of an ultrasonic wave propagating through a metal of a certain material.

In this embodiment, since the calibration plate 22 and the pipe T are disposed adjacent to each other, the temperature of the calibration plate 22 can be regarded as equivalent to the temperature of the pipe T detected by the thermocouple 34.
As shown in FIG. 1, the detection signal detected by the thermocouple 34 is input via a cable 36 to a propagation velocity calculation unit 38 built in the flaw detector main body 30. The propagation speed calculation unit 38 calculates the propagation speed of the ultrasonic wave that propagates through the pipe T and the calibration plate 22 from the detected detection signal and the material of the pipe T and the calibration plate 22. The correction unit 40 performs a correction process that cancels out the difference in ultrasonic propagation speed between the pipe T and the calibration plate 22 that is caused by the difference in material and temperature between the pipe T and the calibration plate 22.

In the present embodiment, since the temperature conditions of the pipe T and the calibration plate 22 are regarded as the same, it is not necessary to consider the difference in temperature. Furthermore, if the materials of the pipe T and the calibration plate 22 are the same, it is not necessary to perform correction processing by the correction unit 40. Therefore, the correction unit 40 is not necessary.
After performing the correction process by the correction unit 40, the measurement result of the thinning state of the pipe T is output to the output unit 42. Data relating to the waveform and time axis displayed on the display unit 32 and data output to the output unit 42 are stored in the storage unit 44.

  This processing flow is shown in FIG. In FIG. 4, the surface temperature of the pipe T adjacent to the calibration plate 22 is detected by the thermocouple 34 (S10). This detected temperature can be regarded as the temperature of the calibration plate 22. Next, if necessary, correction processing by the correction unit 40 is performed (S14), and then the measurement of the thinning state of the pipe T and calibration are performed simultaneously (S16).

FIG. 5 shows the waveform of the high-frequency voltage of each reflected wave displayed on the display unit 32. In the figure, the horizontal axis is the time axis. FIG. 5A shows the waveform of the high-frequency voltage when the calibration plate 22 is not incorporated in the ultrasonic transducer 12A as a comparative example. In the figure, a waveform S is a waveform of a reflected wave reflected on the surface of the pipe T, and B1 and B2 are waveforms of a multiple reflected wave reflected at least once on the back surface of the pipe T. h1 indicates the thickness of the pipe T.
FIG. 5B shows a waveform obtained by converting the reflected wave received by the ultrasonic transducer 12A of this embodiment into a high-frequency voltage. In the figure, S1 is the waveform of the reflected wave reflected on the surface of the calibration plate 22, and S2, S3 and S4 are the waveforms of the multiple reflected wave reflected at least once on the back surface of the calibration plate 22. h2 indicates the thickness of the calibration plate 22.

FIG. 5C is also a waveform obtained by converting the reflected wave received by the ultrasonic transducer 12A of the present embodiment into a high-frequency voltage, but FIG. 5B is a plate having a large thickness and an ultrasonic wave. This is a case where a calibration plate made of a material having a low propagation speed is used. On the other hand, FIG. 5C shows a case where a calibration plate having a thin plate thickness and a high ultrasonic propagation speed is used.
In this embodiment, the reflected waves S, B1, and B2 reflected by the pipe T are compared with the reflected waves S1 to S4 reflected by the calibration plate 22, and based on the difference between the waveforms and the time axis, the processing steps are performed. Measure the thickness reduction of the pipe T. Calibration is done at the same time as the measurement.

  FIG. 6 shows the time when the ultrasonic transducer 12A fixed to the pipe T is calibrated. First, the ultrasonic transducer 12A in which the calibration plate 22 is incorporated is fixed to the pipe T (S20). Next, after calibrating the change over time of the ultrasonic transducer 12A (S22), the pipe T is periodically inspected for scratches and thinning (S24 and S26). Next, when the fixed period P has passed since the previous calibration (S22), the temporal change of the ultrasonic transducer 12A is calibrated (S28). The period P is, for example, 6 months to 1 year. In this way, while continuing the operation of the power plant, the pipe T is inspected for scratches and thinning, and when the pipe T reaches the end of its life, the pipe T is discarded.

  According to the present embodiment, the ultrasonic transducer 12A remains attached to the pipe T with simple and low-cost means by simply incorporating the calibration member 22 having a known plate thickness and material into the ultrasonic transducer 12A. In this state, the thin film ultrasonic transducer 12A can be calibrated. In addition, the reflected wave of the pipe T can be calibrated simultaneously with the ultrasonic inspection of the pipe T.

  5B and 5C, in the present embodiment, the thickness and material of the calibration plate 22 are changed to the waveform of the reflected wave of the pipe T while considering the temperature condition of the calibration plate 22. The waveform is selected so as not to overlap with the waveform of the reflected wave of the calibration plate 22 or to prevent grasping of the waveform of the reflected wave of the pipe T and the time axis. Accordingly, these can be accurately grasped without adversely affecting the inspection of the pipe T and the thinning state, and the change with time of the ultrasonic transducer 12A can be accurately grasped.

Further, if the temperature and material of the calibration plate 22 and the pipe T are the same, the propagation speed of the ultrasonic pulse propagating through the calibration plate 22 and the propagation speed of the ultrasonic pulse propagating through the pipe T are the same. Therefore, the position on the time axis of the reflected wave of the calibration plate 22 displayed on the display unit 32 can be easily estimated, and the position can be easily displayed at a position that does not overlap with the reflected wave of the pipe T.
Further, since the calibration plate 22 is arranged between the lower electrode 20 and the pipe T, the calibration plate 22 does not interfere with the arrangement of the upper electrode 18. Furthermore, since the temperature conditions of the calibration plate 22 and the pipe T are the same, the position of the reflected wave of the pipe T displayed on the display unit 32 and the reflected wave of the calibration member 22 on the time axis is the thickness of both. It is determined uniquely, and it becomes easier to eliminate the overlapping of the reflected waves of both.

Hereinafter, an example of a specific configuration of the calibration plate 22 is shown.
(1) Case in which reflected wave S2 appears after reflected wave B1 (case in FIG. 5B)
When the pipe T is a low alloy steel (propagation speed 5,900 m / sec) and the plate thickness is 10 mm,
When the calibration plate 22 is low alloy steel, the calibration plate 22 is made thicker than 10 mm.
When the calibration plate 22 is heat resistant resin (propagation speed 2,360 mm / second), the calibration plate 22 is made thicker than 4 mm.
(2) Case in which reflected wave S2 appears before reflected wave B1 (case in FIG. 5C)
When the pipe T is a low alloy steel (propagation speed 5,900 m / sec) and the plate thickness is 10 mm,
When the calibration plate 22 is low alloy steel, the calibration plate 22 is made thinner than 5 mm.
When the calibration plate 22 is heat resistant resin (propagation speed 2,360 mm / second), the thickness of the calibration plate 22 is made thinner than 2 mm.

(Embodiment 2)
Next, a second embodiment of the present invention will be described with reference to FIGS. In FIG. 7, the present embodiment is an example in which a calibration plate 22 incorporated in the ultrasonic transducer 12 </ b> B is fixed to the upper surface of the upper electrode 18. Other configurations are the same as those of the first embodiment.
FIG. 8A shows a case where a calibration plate made of a material having a large plate thickness and a low ultrasonic propagation speed is used, and FIG. 8B shows a thin plate thickness and an ultrasonic propagation speed. This is the case where a fast calibration plate is used. 8A and 8B, BS1 is a waveform of a reflected wave reflected from the bottom surface of the calibration plate 22 closest to the piezoelectric element 14, and BS2, BS3, and BS4 are reflected at the surface of the calibration plate 22 one or more times. Multiple reflected waves.

  Also in the present embodiment, the thickness and material of the calibration plate 22 do not overlap with the waveform of the reflected wave of the pipe T, or the reflected wave of the pipe T can be identified even when overlapping with the waveform of the reflected wave of the pipe T. Thus, the plate thickness and material are selected so that the waveform is sufficiently small.

  According to the present embodiment, since there is no calibration plate 22 between the piezoelectric element 14 and the pipe T, the ultrasonic pulse irradiated from the ultrasonic transducer 12B is not attenuated by the calibration plate 22 and the calibration plate 22 Since it propagates to the pipe T without being reflected at the boundary surface, it is possible to maintain a high measurement sensitivity for the damage to the pipe T and the thickness reduction condition.

(Embodiment 3)
Next, a third embodiment of the present invention will be described with reference to FIGS. In FIG. 9, in the ultrasonic transducer 12C of this embodiment, the lower electrode 20 also serves as a calibration plate. Therefore, the lower electrode 20 is a plate-like body having a plate thickness of 3 microns or more (for example, 3 mm or more) and is made of the same material as the pipe T.
Further, the plate thickness of the lower electrode 20 is made smaller than the wall thickness of the pipe T so that multiple reflected waves do not overlap with the expected thickness reduction range of the pipe T. Other configurations are the same as those of the first embodiment.

According to the present embodiment, by using the lower electrode 20 as the calibration plate 22, the configuration of the ultrasonic transducer 12C can be simplified and reduced in cost.
In addition, there exists a possibility that the copying property to the surface of the piping T may fall because the plate | board thickness of the lower electrode 20 becomes thick. Therefore, at the time of manufacturing the ultrasonic transducer 12C, the shape of the lower electrode 20 may be set to follow the shape of the pipe T in advance.

  According to the present invention, the measurement value of the subject can be calibrated simultaneously with the measurement of the subject while being installed on the subject with a simple and low-cost means with respect to the temporal change of the thin-film ultrasonic transducer. It becomes.

DESCRIPTION OF SYMBOLS 10 Ultrasonic measuring device 12A, 12B, 12C Ultrasonic vibrator 14 Piezoelectric element 16 Piezoelectric body 18 Upper electrode 20 Lower electrode 22 Calibration board 24 Contact medium 26, 28 Conductor 29 Code 30, 50 Flaw detector main body 32 Display part 34 Thermocouple 36 Cable 38 Propagation speed calculation unit 40 Correction unit 42 Output unit 44 Storage unit B1, B2, BS1, BS2, BS3, BS4, S, S1, S2, S3, SS1, SS2, SS3, SS4 Reflected wave T Piping (subject) )

Claims (10)

A piezoelectric body is sandwiched between the lower electrode and the upper electrode, is fixed to the surface of the subject, transmits ultrasonic waves toward the subject, receives reflected waves reflected by the subject, and receives high-frequency waves. In an ultrasonic measurement device having a thin-film ultrasonic transducer that converts voltage, and a display unit that displays the waveform of the high-frequency voltage,
A plate-shaped calibration member that has a known plate thickness and material, is fixed to the ultrasonic transducer, and propagates ultrasonic waves transmitted from the ultrasonic transducer;
It is a reflected wave of the ultrasonic wave reflected by the calibration member, and the time axis of the measuring device including the ultrasonic transducer is obtained from the information on the waveform and time axis of the high frequency voltage of the reflected wave displayed on the display unit. And an ultrasonic measurement apparatus calibrating the signal level. A temperature sensor for detecting temperatures of the subject and the calibration member;
Correction means for canceling out a difference in ultrasonic propagation speed between the subject and the calibration member caused by a difference in material and temperature between the subject and the calibration member;
The time axis and signal level of the measuring device including the ultrasonic transducer are calibrated based on the ultrasonic propagation velocity of the subject and the calibration member corrected by the correction unit. The ultrasonic measurement apparatus described.   2. The plate thickness and material of the calibration member are set such that the reflected wave of the subject and the reflected wave of the calibration member do not overlap on the time axis of the display unit. The ultrasonic measurement apparatus described.   The plate thickness and material of the calibration member, the plate thickness and material of which the amplitude of the reflected wave of the calibration member is so small that the reflected wave of the calibration member does not hinder the grasp of the waveform and time axis of the reflected wave of the subject. The ultrasonic measurement apparatus according to claim 1, wherein:   The ultrasonic measurement apparatus according to claim 1, wherein the calibration member is disposed between the lower electrode and the subject.   The ultrasonic measurement apparatus according to claim 1, wherein the calibration member is fixed to a surface of the upper electrode.   The ultrasonic measurement apparatus according to claim 1, wherein the lower electrode is configured by a plate-shaped calibration member having a known plate thickness and material.   The said lower electrode has the thickness and material which the reflected wave of this lower electrode and the reflected wave of the said test object do not overlap on the time axis of the said display part, The material of Claim 6 characterized by the above-mentioned. Ultrasonic measuring device. A piezoelectric body is sandwiched between the lower electrode and the upper electrode, is fixed to the surface of the subject, transmits ultrasonic waves toward the subject, receives reflected waves reflected by the subject, and receives high-frequency waves. In a method for calibrating an ultrasonic measurement device having a thin-film ultrasonic transducer that converts to a voltage and a display unit that displays a waveform of the high-frequency voltage,
A first step of propagating ultrasonic waves to the subject and the plate-like calibration member having the known plate thickness and material and fixed to the ultrasonic transducer;
A second step of receiving reflected waves of ultrasonic waves respectively reflected by the subject and the calibration member by the ultrasonic transducer and converting them into a high-frequency voltage;
The waveform of the high frequency voltage of the subject and the calibration member is displayed on the display unit, and the time axis and signal of the measuring device including the ultrasonic transducer are obtained from the information about the waveform of the high frequency voltage of the calibration member and the time axis. And a third step of calibrating the level. A method for calibrating an ultrasonic measuring device. A temperature detecting step for detecting temperatures of the subject and the calibration member;
A correction step of correcting a difference in ultrasonic propagation speed between the subject and the calibration member caused by a difference in material and temperature between the subject and the calibration member;
In the third step, the time axis and signal level of the measuring device including the ultrasonic transducer are calibrated based on the ultrasonic wave propagation speed of the subject and the calibration member corrected in the correction step. The method for calibrating an ultrasonic measurement apparatus according to claim 9.

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