JP3524841B2 - Ultrasonic probe, ultrasonic measuring instrument, and ultrasonic thickness measuring method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ultrasonic probe, an ultrasonic measuring device, and an ultrasonic thickness measuring method, and in particular,
Ultrasonic probe and ultrasonic measuring instrument that can accurately and easily measure the thickness of an object such as a steel plate having an uneven surface formed by deposits such as rust and paint film on the surface. And an ultrasonic thickness measuring method.

[0002]

2. Description of the Related Art Steel sheets are used after being surface-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. The uneven surface measuring probe 1 is provided in the vicinity of the surface of the object to be measured 101 which is subjected to surface corrosion such as a steel plate.
The tip of 02 is positioned. The tip portion is formed in a tapered shape. Such a tapered shape is also known from Japanese Patent Application Laid-Open No. 7-208968. The tapered holder 103 is formed on a tapered conical surface, and the conical space is filled with water from the outside. The use of water is because the ultrasonic pulse has good conductivity in water and very poor conductivity in air. The receiving element 104 is fixed to the 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 reflection pulse that reciprocates with a slight gap between the receiving element 104 and the uneven surface of the object 101 to be measured has a surface echo. Dispersion makes accurate measurement impossible. In order to avoid such inconvenience, a proper distance is provided between the receiving element 104 and the surface of the measurement target object 101, and the conical space having the distance is filled with water. The time difference between the propagation time of the front surface reflection pulse and the propagation time of the bottom surface reflection pulse is converted into a distance. By such distance conversion, the measurement target object 1
A thickness of 01 can be measured. In order to make the distance between the receiving surface of the receiving element 104 and the uneven surface of the measurement target object 101 as accurate as possible, the holder 103 is formed in a tapered shape, and ultrasonic waves are applied to the probe point where the tapered tip touches the uneven surface. In order 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 a spherical surface.

Such a known measuring device has the following problems. (1) In order to inject water into the water drop holder 103, the pump 10
5 is used. The problem is the treatment of water that drains. The use of the pump 105 is cumbersome for the measurement work. (2) The distance between the receiving element 104 fixed to the receiving element fixing holder 103 and the surface of the measurement target object 101 is fixed.
Such fixing limits the plate thickness range in which high-precision measurement is possible. In the past, many measuring instruments with varying distances were required. (3) Measuring Method The thickness is judged from the characteristics of the converted distance and the spectrum of the reflectance of ultrasonic waves. In order to form the spectrum, a linear amplifier is used as an amplifier that amplifies the reflectance of ultrasonic waves. In the spectrum, the vertical axis represents the reflectance of the ultrasonic pulse and the horizontal axis represents the converted distance. In the measurement of the uneven surface, the echo reflected on the surface of the object to be measured is very small compared to the echo reflected on the bottom surface thereof due to the existence of the gap in the uneven surface layer. Therefore, in order to confirm the bottom surface reflection echo by enlarging the vertical axis, it becomes necessary to perform measurement while adjusting the height of the waveform. When an adhered substance such as rust or a coating material adheres to the surface, it is difficult to separate the adhered substance at the time of measurement, resulting in a large measurement error. Therefore, the inspection value of the structure cannot be evaluated.

There is a need to prevent runoff of water. Next, it is desired that there is no restriction between the receiving element and the uneven surface. Furthermore, it is desirable that the presence of surface deposits does not compromise the reliability of the measurements.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic probe, an ultrasonic measuring device, and an ultrasonic thickness measuring method capable of preventing water from flowing down. Another object of the present invention is to provide an ultrasonic probe, an ultrasonic measuring device, and an ultrasonic thickness measuring method in which the distance between the receiving element and the uneven surface of the object to be measured is not limited. Still another object of the present invention is to provide an ultrasonic probe, an ultrasonic measuring device, and an ultrasonic thickness measuring method in which the presence of surface deposits does not impair the reliability of measured values. Yet another object of the present invention is to prevent water runoff,
And, the distance between the receiving element and the uneven surface of the object to be measured is not limited, and the presence of foreign matter does not impair the reliability of the measured value ultrasonic probe, ultrasonic measuring device, and ,
An object is to provide an ultrasonic thickness measuring method.

[0007]

Means for solving the problem Means for solving the problem are expressed as follows. The technical matters appearing in the expression are accompanied by parentheses (), and numbers, symbols and the like are added. The numbers, symbols and the like are technical matters constituting at least one embodiment or plural examples of the embodiments or plural examples of the present invention, particularly the embodiment or examples. It corresponds to the reference numbers, reference symbols, etc. attached to the technical matters expressed in the drawings corresponding to. Such reference numbers and reference symbols clarify correspondences and bridges 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 limited to the technical matters of the embodiment or the examples.

The ultrasonic probe according to the present invention comprises a body (1,
2) and a receiving element (5) attached to the main body for receiving ultrasonic waves, the main body (1, 2) has a space (8) for storing a liquid having high ultrasonic conductivity inside. In addition, it further includes a seal film (13) that closes the space at the tip surfaces of the main bodies (1, 2). 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 changed into noise and is not detected. , Does not pollute the surroundings. The noise generated by the sealing film is fixed and does not adversely affect the thickness measurement.

The main body (1, 2) comprises a first holder (1) for fixing the receiving element (5) and a second holder (2) for holding a sealing film. The space (8) is the first space formed by the first holder (1) and the second holder (2).
And a second space formed by. The first holder (1) has an opening that connects to the first space and opens 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 bubbles do not enter the entire receiving surface, ultrasonic waves are stably and uniformly transmitted.

The receiving element (5) is fixed to the main body so that the position of the receiving element (5) can be changed 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 body (1) via an O-ring 4. The O-ring absorbs and attenuates acoustic noise and prevents liquid leakage. The cross-sectional shape of the O-ring does not have to be a circle.

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

In the ultrasonic thickness measuring method according to the present invention for measuring the thickness of an object to be measured using such an ultrasonic measuring device, the object to be measured (21) is an object body (22) and an object body (22). A first ultrasonic wave (B) which is formed from an adherent layer (24) attached to the
1) Measuring the first propagation time of the object body (22)
Of the second ultrasonic wave (B2) which is reflected on the bottom surface of the object body (22) and then on the boundary surface between the deposit layer (24) and the object body (22) and further on the bottom surface of the object body (22). Measuring the transit time, calculating the thickness of the body of the object (22) from the time difference between the first transit time and the second transit time, the first
A spectrum is created with the vertical axis representing the reception intensity of each of the ultrasonic waves (B1) and the second ultrasonic wave (B2), and the horizontal axis representing the converted distance obtained by converting the propagation times (t2, t1) of these waves. That is, the small protrusion immediately after the rising of the spectra of the first ultrasonic wave (B1) and the second ultrasonic wave (B2) in the direction of the vertical axis is detected by the logarithmic amplifier. The physical characteristics of the logarithmic amplifier are utilized, and a small protrusion (fine structure of spectrum) immediately after the rising of the waveform.
Are separated and the presence of a thin layer such as a deposit layer can be detected.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Corresponding to the figures, an ultrasonic probe according to an embodiment of the present invention is provided with a log amplifier (logarithmic amplifier) 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 integrated by a plurality of fastening screws 3 having a spiral axis line in the axial direction. A receiving element 5 is held and fixed to the center of the upper holder 1 via an O-ring 4. Receiving 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 which coincides with the transmitting surface.
Has as a lower end surface. The receiving surface 6 is formed into a spherical surface or a pseudo spherical surface, and the ultrasonic pulse 7 emitted from the receiving surface 7
On the point focus 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 filled with water. Chamber 8
Is 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 a water injection port closing screw (plug) is provided in the opening.
11 is inserted.

The lower end opening 12 of the tapered chamber 8 is closed by a sealing film 13.
As the seal film 13, a film that is as thin as possible is used. The output terminal of the receiving element 5 is the log amplifier 1
4 is connected to the input side terminal. The log amp 14
It has a physical function of converting the 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 the direction perpendicular to the axis.

The internal space formed by the chamber 8 is composed of 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 is
It has an opening that opens at its outer surface, and that opening is connected to the upper space. The opening is blocked by the water injection port closing screw 11 as described above. The upper space and the lower space are closed by a sealing film 13 and a water injection port closing screw 11. The O-ring 4 can prevent leakage of water in the chamber 8.

FIG. 2 shows a measuring principle for measuring the thickness of the steel sheet. The steel plate 21 includes a steel plate body 22 and a steel plate body 2
Coating films 23, 23 applied to both surfaces (upper and lower surfaces) of No. 2. In the steel plate 21, the coating film on the upper surface side is eroded, the upper surface side of the steel plate body 22 is partially corroded, and rust is generated in the corroded portion, so that the rust layer 24 is formed.

The ultrasonic pulse emitted from the receiving element 5 is concentrated on the point-like region near the surface of the steel plate 21. Steel plate 2
The ultrasonic waves concentrated in the vicinity of the surface of No. 1 pass through (1) the rust layer 24 and are reflected by the boundary surface between the steel plate body 22 and the lower coating film 23 (bottom surface of the steel plate body), and It propagates through the inside and further bounces off as an echo B1 that passes through the rust layer 24 and is incident on the receiving surface, or (2) passes through the rust layer 24 and passes through the rust layer 24 and the boundary surface between the steel plate body 22 and the lower coating film 23. And propagates in the steel plate body 22, further reflects in the bottom surface of the rust layer 24, propagates in the third and fourth steel plate bodies 22, and again in the bottom surface of the steel plate body 22 and in four degrees. And the echo B that propagates through the steel plate body 22, penetrates the rust layer 24, and is incident on 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 in the steel plate body and the time when the echo B2 propagates in 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 velocity of ultrasonic waves 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 represents the converted distance obtained by converting the propagation time of the ultrasonic pulse, and the vertical axis represents the intensity of the received ultrasonic wave. Its intensity is converted to logarithmic value. Since all the waveforms from the surface reflection echo S to the echoes B1 and B2 can be visually observed, 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 rise of echo B1 and the small protrusion immediately after the rise of echo B2 means that the steel plate body 22
It shows that there is a deposit layer such as a thin coating layer 23 on the back surface of the.

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 shows 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 judged 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 / stored in the log amplifier 14, automatic measurement is possible.

FIG. 4 shows a spectrum obtained by a conventional measuring means using a linear amplifier. The conventional measuring means uses a linear amplifier instead of a log amplifier. In FIG. 5, small protrusions immediately after the rising edges of both echoes B1 and B2 are not visible. Since the vertical axis represents the reflectance of ultrasonic waves, the reflectance of the bottom surface reflected wave is naturally a smaller value than the reflectance of the surface reflected wave. In order to make a small protrusion appear, as shown in FIG. 5, the vertical axis is enlarged and the display is conventionally changed so that the apex of the echo B1 becomes 100%. Even with such expansion, the projection immediately after the rising of the echoes B1 and B2 is
The echoes B1 and B2 are absorbed by the entire echoes, and the presence or absence of such protrusions 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 amp that amplifies a signal logarithmically has physical and mathematical characteristics that clearly reveals the fine structure in the vertical direction (projection direction) of a waveform that changes in a protruding manner.

There is a correlation between the thinness of the tip of the probe and the size of the corrosion hole in terms of measurement accuracy. The thinner 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 seal 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 that the seal film would not come off. The tip shape is a circle with a small diameter or a rectangle with a small area. Under such conditions, positive and negative 0.
A measurement accuracy of 1 mm was achieved. The positive / negative of 0.1 mm is sufficiently high as the currently required accuracy.

Conventionally, the distance between the receiving surface 6 of the receiving element and the surface of the object to be measured 21 is kept at 11 mm. In this case, the above-mentioned high accuracy is realized in the range of the steel plate thickness 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,
It has become possible to achieve the above-mentioned high accuracy by measuring a steel plate having a thickness of m or more.

In the data processing that only numerically enlarges the value, the waveforms overlap and the resolution for confirming the small protrusions cannot be obtained. However, since the log amp is physically logarithmic, It is possible to obtain a resolution that allows confirmation of small protrusions.

[0026]

EFFECT OF THE INVENTION The ultrasonic probe, the ultrasonic measuring device and the ultrasonic thickness measuring method according to the present invention are firstly for preventing water contamination and for preventing bubbles from entering and secondly for measuring. It is possible to expand the range of the thickness of the measurement target object that can maintain the accuracy, and thirdly, increase the resolution of the analysis of the high accuracy measurement, and as a result, realize the high accuracy measurement.

[Brief description of drawings]

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

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

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

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

FIG. 5 is a graph showing the results of processing measured values by a known device.

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

[Explanation of symbols]

1, 2 ... Main body 1 ... 1st holder 2nd 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 ... Adhesion layer B1 ... First ultrasonic wave B2 ... Second ultrasonic wave t2, t1 ... Propagation time

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshimichi Kawakami 1-8-chome, Koura, Kanazawa-ku, Yokohama City, Kanagawa Prefecture 1 Inside Yokohama Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inori Motonori Yasunaga 4 Ibori, Kokurakita-ku, Kitakyushu, Fukuoka No. 10-13 New Japan Non-Destructive Inspection Co., Ltd. (56) Reference JP-A-7-239227 (JP, A) JP-A-2000-35419 (JP, A) Actual development Sho-60-29278 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04R 1/02 330 G01B 17/02

Claims (5)

(57) [Claims] 1. A main body and a receiving element attached to the main body for receiving ultrasonic waves, the main body having a space for containing a liquid having high ultrasonic conductivity therein, and the main body. the distal end surface of the closing seal film said space <br/> seen including in the said body, a first holder for fixing the receiving element, and a second holder for holding the sealing film, wherein the space is First empty space formed by the first holder
From the space and the second space formed by the second holder
The first holder is connected to the first space, and the first holder is formed.
An ultrasonic probe having an opening that opens on the outer surface of the rudder, and further including a plug that closes the opening . 2. The ultrasonic probe according to claim 1, wherein the receiving element is fixed to the main body so that the position of the receiving element is variable in the propagation direction of the ultrasonic wave received by the receiving element. 3. The ultrasonic probe according to claim 2 , wherein the receiving element is fixed to the main body via an O-ring. 4. An ultrasonic measuring device using the ultrasonic probe according to claim 1, comprising an logarithmic amplifier for logarithmically amplifying the intensity of the ultrasonic wave received by the receiving element. . 5. An ultrasonic thickness measuring method for measuring the thickness of an object to be measured using the ultrasonic measuring device according to claim 4 , wherein the object to be measured is attached to the object body and the object body. Measuring a first propagation time of a first ultrasonic wave which is formed from a kimono layer and which is reflected on the bottom surface of the object body, which is reflected on the bottom surface of the object body, and then between the attached matter and the object body. Measuring a second propagation time of a second ultrasonic wave reflected by a boundary surface and further reflected by a bottom surface of the object body; calculating a thickness of the object body from a time difference between the first propagation time and the second propagation time. Creating a spectrum in which the vertical axis represents the reception intensity of each of the first ultrasonic wave and the second ultrasonic wave, and the horizontal axis represents a converted distance obtained by converting the propagation time into a distance. Sound wave and 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.