JP2001309475A - Ultrasound probe, ultrasonic wave measuring unit and ultrasonic wave thickness measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the discharge of water, to prevent restriction of a distance between a reception element and uneveness surface of a body to be measured and to prevent the existence of a material stuck to a surface from impairing the reliability of a measurement value. SOLUTION: Bodies 1 and 2, incorporating the reception element 5 receiving an ultrasonic wave, have a space 8 storing liquid, whose conductivity of the ultrasonic wave is high in the inside. A sealing film 13 closing the space is formed at the tip face of a body 2. The sealing film 13 confines liquid. The reception element 5 is arranged so that a position can be changed freely, and the restriction of the thickness of the body being the object of measuring is relieved. Reflectance is amplified by a log amplifier, and a fine structure spectrum immediately after the rise of a waveform is separated and can be detected. Thus, the existence of the stuck material can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe, an ultrasonic measuring instrument, and an ultrasonic thickness measuring method,
An ultrasonic probe and an ultrasonic measuring device that can easily and accurately measure the thickness of an object such as a steel plate having an uneven surface formed by deposits such as rust and a coating film on the surface. And an ultrasonic thickness measuring method.

[0002]

2. Description of the Related Art A steel sheet is used after its surface is coated. The surface coating layer is eroded, and the steel plate portion is corroded. The extent of such corrosion can be known by measuring the overall thickness.
A measuring device for measuring such a thickness is known as shown in FIG. A probe 1 for measuring an uneven surface near a surface of a measurement object 101 subject to surface corrosion such as a steel plate
02 is positioned. The tip is formed in a tapered shape. Such a tapered shape is also known from JP-A-7-208968. The tapered holder 103 is formed in a tapered conical surface, and the conical space is filled with water flowing from the outside. The use of water is because ultrasonic pulses are highly conductive in water and very poor in air. The receiving element 104 is fixed to an end of the holder 103. Receiving element 104
Can also be used for transmitting ultrasonic waves.

When the receiving element 104 is brought into direct contact with the surface of the object 101 to be measured, a surface reflected pulse reciprocating at a small gap between the receiving element 104 and the uneven surface of the object 101 to be measured has a surface echo of the pulse. Variations make high-precision measurements impossible. In order to avoid such a problem, an appropriate separation distance is provided between the receiving element 104 and the surface of the measurement target object 101, and the conical space having the separation distance is filled with water. The time difference between the propagation time of the surface reflection pulse and the propagation time of the bottom surface reflection pulse is converted into a distance. By such distance conversion, the measurement object 1
It is possible to measure a thickness of 01. In order to make the distance between the receiving surface of the receiving element 104 and the uneven surface of the object to be measured 101 as accurate as possible, the holder 103 is formed to be tapered, and ultrasonic waves are applied to a probe point where the tapered tip touches the uneven surface. To concentrate, the receiving or transmitting surface of the receiving element 104 is formed as a spot-focus type (point-focus type) spherical surface or spherically similar surface.

[0004] Such a known measuring device has the following problems. (1) Drip of water In order to inject water into the holder 103, a pump 10
5 is used. The treatment of running water is problematic. The use of the pump 105 is troublesome for the measurement operation. (2) Fixing of receiving element The distance between the receiving element 104 fixed to the holder 103 and the surface of the measurement object 101 is fixed.
Such fixing limits the range of plate thickness at which high-precision measurement is possible. Conventionally, many measuring instruments whose distances have been changed variously have been required. (3) Measuring Method The thickness is determined from the above-described converted distance and the characteristics of the spectrum of the reflectance of the ultrasonic wave. In order to form the spectrum, a linear amplifier is used as an amplifier for amplifying the reflectance of ultrasonic waves. In the spectrum, the vertical axis is the reflectivity of the ultrasonic pulse, and the horizontal axis is the converted distance. In the measurement of the uneven surface, the echo reflected on the bottom surface of the measurement object is very small compared to the echo reflected on the bottom surface thereof due to the existence of the gap of the uneven surface layer. Therefore, in order to confirm the bottom surface reflected echo by enlarging the vertical axis, the measurement must be performed while adjusting the height of the waveform. If an adhered substance such as rust or a coating material adheres to the surface, it is difficult to separate the adhered substance during measurement, and the measurement error increases. Therefore, it cannot be evaluated as an inspection value of the structure.

[0005] There is a need to prevent the running of water. Next, it is desired that the distance between the receiving element and the uneven surface is not limited. Furthermore, it is desired that the reliability of the measured values is not lost due to the presence of surface deposits.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultrasonic probe, an ultrasonic measuring instrument, and an ultrasonic thickness measuring method which can prevent water from flowing down. Another object of the present invention is to provide an ultrasonic probe, an ultrasonic measuring instrument, and an ultrasonic thickness measuring method in which a distance between a receiving element and an uneven surface of an object to be measured is not limited. It is still another object of the present invention to provide an ultrasonic probe, an ultrasonic measuring device, and an ultrasonic thickness measuring method in which the presence of a surface deposit does not impair the reliability of the measured value. Still another object of the present invention is to prevent the running of water,
In addition, the distance between the receiving element and the uneven surface of the object to be measured is not limited, and the presence of the attached substance does not impair the reliability of the measured value. ,
It is an object of the present invention to provide an ultrasonic thickness measuring method.

[0007]

Means for solving the problem are described as follows. The technical items appearing in the expression are appended with numbers, symbols, and the like in parentheses (). The numbers, symbols, and the like are technical items that constitute at least one embodiment or a plurality of the embodiments of the present invention, in particular, the embodiments or the examples. Corresponds to the reference numerals, reference symbols, and the like assigned to the technical matters expressed in the drawings corresponding to the above. Such reference numbers and reference symbols clarify the correspondence and bridging between the technical matters described in the claims and the technical matters of the embodiments or examples. Such correspondence / bridge does not mean that the technical matters described in the claims are interpreted as being limited to the technical matters of the embodiments or the examples.

The ultrasonic probe according to the present invention has a main body (1,
2) and a receiving element (5) attached to the main body for receiving ultrasonic waves. The main bodies (1, 2) have a space (8) for storing a liquid having a high ultrasonic conductivity. Further, a sealing film (13) for closing the space at the distal end face of the main body (1, 2) is included. The liquid is confined by the seal film, the liquid does not flow on the surface side of the object to be measured (21), and the thickness information of the liquid layer is variably turned into noise and is not detected. , Does not pollute the surroundings. The noise generated by the seal film is fixed and does not adversely affect the thickness measurement.

The main body (1, 2) includes a first holder (1) for fixing the receiving element (5) and a second holder (2) for holding a sealing film. The space (8) includes a first space formed by the first holder (1) and a second holder (2).
And the second space formed by The first holder (1) has an opening connected to the first space and opening on the outer surface of the first holder (1), which opening can be closed by a plug (11). The first space and the second space are continuous,
The liquid can cover the entire receiving surface (6) of the receiving element (5), and since air bubbles do not enter the entire receiving surface, the transmission of ultrasonic waves becomes stable and uniform.

[0010] The receiving element (5) is fixed to the main body so as to be variable in the propagation direction of the ultrasonic wave received by the receiving element (5). The distance between the receiving surface (6) and the surface of the object to be measured (21) is properly adopted, and the thickness of the object to be measured (21) whose measured value falls within the allowable accuracy range can be increased. The receiving element (5) is fixed to the main body (1) via an O-ring 4. The O-ring absorbs and attenuates sonic noise and prevents liquid leakage. The cross-sectional shape of the O-ring need not be a circle.

The ultrasonic measuring device according to the present invention using such an ultrasonic probe has a logarithmic amplifier for logarithmically amplifying the intensity of the ultrasonic wave received by the receiving element (5). A logarithmic amplifier that logarithmically suppresses a large physical signal value and reduces it to a small value can sense a small change in a part of the waveform physically sharply and amplify it. By such amplification, the existence of the layers (23, 24) adhering to the object surface can be known more precisely.

According to the ultrasonic thickness measuring method of the present invention for measuring the thickness of an object to be measured using such an ultrasonic measuring instrument, the object to be measured (21) is composed of an object body (22) and an object body (22). The first ultrasonic wave (B) formed from an adhering substance layer (24) adhering to the object body and reflected on the bottom surface of the object body (22)
Measuring the first propagation time of 1), the object body (22)
Of the second ultrasonic wave (B2) reflected at the bottom surface of the object body (22), then at the interface between the deposit layer (24) and the object body (22), and further at the bottom surface of the object body (22) Measuring the propagation time, calculating the thickness of the object body (22) from the time difference between the first propagation time and the second propagation time,
A spectrum is created for each of which the reception intensity of the ultrasonic wave (B1) and the second ultrasonic wave (B2) is set as the vertical axis, and the propagation distance (t2, t1) of the ultrasonic wave (T2, t1) is converted to the distance, and the horizontal axis is the converted distance. That is, detecting a small protrusion immediately after the rising of the first ultrasonic wave (B1) and the second ultrasonic wave (B2) in the direction of the vertical axis by a logarithmic amplifier. Utilizing the physical characteristics of the logarithmic amplifier, small protrusions immediately after the rise of the waveform (fine structure of the spectrum)
Are separated and the presence of a thin layer such as a deposit layer can be detected.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Corresponding to the drawings, in an embodiment of the ultrasonic probe according to the present invention, a log amplifier (logarithmic amplifier) is provided together with a thickness measuring instrument. The thickness measuring device 10 includes an upper holder 1 and a lower holder 2. The upper holder 1 and the lower holder 2 are unified by a plurality of fastening screws 3 having a screw axis in the axial direction. The receiving element 5 is held and fixed to the center of the upper holder 1 via an O-ring 4. Receiver element 5
Is a conventional means having a function of receiving ultrasonic waves and also having a function of transmitting ultrasonic waves.

The receiving element 5 has a receiving surface 6 corresponding to the transmitting surface.
As a lower end surface. The receiving surface 6 is formed as a spherical surface or a pseudo-spherical surface, and an ultrasonic pulse 7 transmitted from the receiving surface.
Is focused on the point focal point P. The receiving surface 6 is exposed in a substantially conical space formed in the lower holder 2. The conical space forms a chamber (or internal space) 8 that is filled with water. Chamber 8
Are connected to a water injection channel 9 formed as an internal space of the upper holder 1. The water injection channel 9 has an opening communicating with the outside world, and the opening is provided with a water inlet blocking screw (plug).
11 is inserted.

The lower end opening 12 of the tapered chamber 8 is closed by a seal film 13.
A film as thin as possible is used for the seal film 13. The output terminal of the receiving element 5 is a log amplifier 1
4 input side terminals. The log amplifier 14
It has a physical function of converting a signal value output by the receiving element 5 into a logarithmic value. The receiving element 5 can be fixed to the upper holder 1 by a fixing screw 15 that is movable in a direction perpendicular to the axis.

The internal space formed by the chamber 8 is formed by a lower space formed by the lower holder 2 and an upper space formed by the upper holder 1. The upper space is continuous with the lower space. The upper holder 1
It has an opening that opens on its outer surface, and the opening is connected to the upper space. The opening is closed by the water inlet sealing screw 11 as described above. The upper space and the lower space are closed by the seal film 13 and the water inlet blocking screw 11. The O-ring 4 can prevent the water in the chamber 8 from leaking.

FIG. 2 shows a measurement principle for measuring the thickness of a steel sheet. The steel plate 21 includes a steel plate body 22 and a steel plate body 2.
2 coating films 23, 23 applied to both surfaces (upper and lower surfaces). The upper surface side of the steel plate main body 22 is partially corroded in a concave shape due to the erosion of the upper surface side coating film of the steel plate 21, and rust is generated in the corroded portion to form the rust layer 24.

The ultrasonic pulse emitted from the receiving element 5 is concentrated on a point-like area near the surface of the steel plate 21. Steel plate 2
The ultrasonic waves concentrated in the vicinity of the surface of the steel sheet main body 1 (1) pass through the rust layer 24, are reflected at the boundary surface between the steel sheet body 22 and the lower coating film 23 (the bottom surface of the steel sheet body), and It propagates through the inside and further bounces off as an echo B1 transmitted through the rust layer 24 and incident on the receiving surface, or (2) passes through the rust layer 24 and interfaces with the steel plate body 22 and the lower coating film 23. Reflected at the bottom of the rust layer 24, propagated through the steel plate body 22, and reflected again at the bottom surface of the steel plate body 22 to be reflected four times. E propagating through the rust layer 24 and propagating through the steel plate body 22 and entering the receiving surface
Bounce as 2.

If the time for the echo B1 to pass through the steel plate body is represented by t, the time for the echo B2 to pass through the steel plate body is 2t with good accuracy. The difference between the time when the echo B1 propagates through the steel plate body and the time when the echo B2 propagates through the steel plate body is t. If t is known, the thickness of the corroded steel plate body 22 is vt, where v is the propagation speed of the ultrasonic wave in the steel plate body.

FIG. 3 shows the measurement results of the sample shown in FIG. In the spectrum shown in FIG. 3, the horizontal axis is the converted distance obtained by converting the propagation time of the ultrasonic pulse, and the vertical axis is the intensity of the received ultrasonic wave. Its intensity is converted to a logarithmic value. Since all the waveforms from the surface reflected echo S to the echoes B1 and B2 can be visually checked, it can be confirmed that the echoes B1 and B2 are reflected waves that have passed through the above-described paths. The presence of both the small protrusion immediately after the rising of the echo B1 and the small protrusion immediately after the rising of the echo B2 is due to the fact that the steel plate body 22
Indicates that there is a deposit layer such as a thin coating layer 23 on the back surface of the substrate.

The difference between the horizontal axis scale indicating the maximum rise of the echo B1 and the horizontal axis scale indicating the maximum rise of the echo B2 corresponds to the thickness D of the steel plate body 22. Such a spectrum indicates the layer structure and corrosion state of the entire steel sheet. The layer structure and the corrosion state of the entire steel sheet can be determined by the measurer from the form of the entire spectrum displayed on the display screen of the log amplifier 14 by the measurer. If various spectrum patterns are prepared and registered and stored in the log amplifier 14, automatic measurement is possible.

FIG. 4 shows a spectrum of a conventional measuring means using a linear amplifier. Conventional measuring means uses a linear amplifier without using a log amplifier. In FIG. 5, a small protrusion immediately after the rising of each of the echoes B1 and B2 is not visible. Since the vertical axis indicates the reflectivity of the ultrasonic wave, the reflectivity of the bottom surface reflected wave is naturally smaller than the reflectivity of the surface reflected wave. In order to make small projections appear, as shown in FIG. 5, the vertical axis is enlarged and the display is changed so that the vertex of the echo B1 becomes 100%. Even if such an enlargement is performed, the protrusion immediately after the rising of the echoes B1 and B2 is
Since the echoes B1 and B2 have been absorbed by the entirety, the presence or absence of such a projection cannot be confirmed. Generally, in a linear amplifier, multiple waveforms overlap,
It is very difficult to read the fine structure of the echo.
A conventional log amplifier that amplifies a signal logarithmically has physical and mathematical characteristics that clearly reveal the fine structure in the vertical direction (projection direction) of a waveform that changes like a protrusion.

There is a correlation between the fineness of the probe tip and the size of the corrosion hole in terms of measurement accuracy. The smaller the tip of the probe, the higher the measurement accuracy, and the larger the corrosion hole, the higher the measurement accuracy. Furthermore, the thinner the sealing film, the higher the measurement accuracy. The thickness of the seal film can be made sufficiently thin so as not to affect the measurement accuracy. In the experiment, the tip shape of the lower holder 2 was made as thin as possible so as not to peel off the seal film. The tip shape is a circle with a small diameter or a rectangle with a small area. Under such conditions, for corrosion pits having a diameter of 6 mm or more, positive and negative 0.
A measurement accuracy of 1 mm was achieved. The positive / negative 0.1 mm is sufficiently high as the precision currently required.

Conventionally, the distance between the receiving surface 6 of the receiving element and the surface of the object 21 to be measured is kept at 11 mm. In this case, the above-described high accuracy is realized when the thickness of the steel plate is in the range of 3 mm to 20 mm. It was done. In the ultrasonic probe according to the present invention, by moving the receiving element 4 upward, 20 m
The high precision described above can be achieved by measuring a steel plate having a thickness of m or more.

In the data processing in which the value is simply enlarged numerically, the waveforms are overlapped with each other, so that the resolution which can confirm the small protruding portion cannot be obtained. It is possible to obtain a resolution enough to confirm small protrusions.

[0026]

The ultrasonic probe, the ultrasonic measuring device, and the ultrasonic thickness measuring method according to the present invention firstly prevent water contamination, do not allow bubbles to enter, and secondly measure. Third, the range of the thickness of the object to be measured that can maintain the accuracy can be expanded, and thirdly, the resolution of the analysis of the high-precision measurement can be increased, and high-accuracy measurement can be realized as a result.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an ultrasonic probe according to the present invention.

FIG. 2 is a cross-sectional view showing a measurement principle.

FIG. 3 is a graph showing a measurement result according to the present invention.

FIG. 4 is a graph showing measurement results obtained by a known device.

FIG. 5 is a graph showing a result obtained by processing a measured value by a known device.

FIG. 6 is a cross-sectional view showing a known device.

[Explanation of symbols]

 1, 2 main body 1 first holder 2 second holder 5 receiving element 6 receiving surface 8 chamber (space) 11 stopper 13 seal film 21 object to be measured 22 object body 24 adhering substance layer B1: first ultrasonic wave B2: second ultrasonic wave t2, t1 ... propagation time

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshimichi Kawakami 1-8-1 Koura, Kanazawa-ku, Yokohama-shi, Kanagawa Prefecture Inside the Yokohama Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Motonori Yasunaga 4 Ibori, Kitakyushu-shi, Fukuoka Prefecture No.10-13 F-term (in reference) in New Japan Non-Destructive Inspection Co., Ltd.

Claims (7)

[Claims] 1. A body comprising: a main body; and a receiving element attached to the main body for receiving an ultrasonic wave, wherein the main body has a space for accommodating a liquid having a high ultrasonic conductivity, An ultrasonic probe including a seal film that closes the space at the tip end surface of the ultrasonic probe. 2. The ultrasonic probe according to claim 1, wherein the main body includes a first holder for fixing the receiving element, and a second holder for holding the seal film. 3. The device according to claim 2, wherein the space is formed by a first space formed by the first holder and a second space formed by the second holder. An ultrasonic probe having an opening connected to one space and opening on an outer surface of the first holder, and further including a plug closing the opening. 4. The ultrasonic probe according to claim 1, wherein the receiving element is fixed to the main body so as to be position-variable in a propagation direction of an ultrasonic wave received by the receiving element. 5. The ultrasonic probe according to claim 4, wherein the receiving element is fixed to the main body via an O-ring. 6. An ultrasonic measurement device using the ultrasonic probe according to claim 1, wherein the ultrasonic measurement device includes a logarithmic amplifier that logarithmically amplifies the intensity of the ultrasonic wave received by the receiving element. . 7. An ultrasonic thickness measuring method for measuring the thickness of an object to be measured using the ultrasonic measuring device according to claim 6, wherein the object to be measured is an object main body and an attachment attached to the object main body. Measuring a first propagation time of a first ultrasonic wave, which is formed from a kimono layer and reflected on the bottom surface of the object body, reflected on the bottom surface of the object body, and Measuring the second propagation time of the second ultrasonic wave reflected at the boundary surface and further reflected at the bottom surface of the object body; calculating the thickness of the object body from the time difference between the first propagation time and the second propagation time Creating a spectrum in which the reception intensity of each of the first ultrasonic wave and the second ultrasonic wave is set as the vertical axis and the converted distance obtained by converting the propagation time into a distance is set as the horizontal axis; Each of the sound wave and the second ultrasonic wave Ultrasonic Thickness measuring method and a possible small projections immediately after the direction of rise of the longitudinal axis of the spectrum is detected by the logarithmic amplifier.