JP3457191B2 - Ultrasonic flaw detector and ultrasonic flaw detection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detector and an ultrasonic flaw detection method for inspecting a surface layer portion of a test body such as a billet or a round bar having a cylindrical cross section. Note that the words "inspection" and "detection" include other words such as "measurement" and "measurement", but here the words "measurement" and "measurement" mean inspection,
Treated as included in the wording of detection.

[0002]

2. Description of the Related Art A conventional ultrasonic flaw detector (method) will be described with reference to the drawings. FIG. 11 shows, for example, “New Non-Destructive Inspection Handbook”, Japan Non-Destructive Inspection Association, Nikkan Kogyo Shimbun, October 15, 1992, 1st edition, 1st edition, page 972 (hereinafter “Reference A”). Is abbreviated as ".").

In FIG. 11, 3A and 3B are probes,
Reference numeral 4 is a flaw detection region in a test body described later, 7 is a contact medium such as water (not described in Document A), 11A and 11B are central axes of ultrasonic pulses propagating in the contact medium 7, and 12A. And 12B are central axes of transverse waves propagating through the central axes 11A and 11B and propagating in the test body, and 21 is a test body such as a round bar.

The reason why there are two probes 3A and 3B is that echoes can be received even if the reflection characteristics of flaws in the flaw detection area 4 have directivity. That is, the operations of the probes 3A and 3B are the same. Hereinafter, in order to simplify the description, only the operation of the probe 3A will be described.

Next, the operation of the conventional ultrasonic flaw detection method of this type will be described. The ultrasonic pulse excited by the probe 3A propagates in the contact medium 7. The ultrasonic waves propagating in the contact medium 7 are only longitudinal waves. The ultrasonic pulse propagating in the contact medium 7 reaches the surface of the test body 21.
On the surface of the test body 21, a part of the ultrasonic pulse is reflected and a part thereof is transmitted, and the transmitted ultrasonic pulse is refracted and propagates according to Snell's law. At this time, longitudinal waves and transverse waves are excited in the test body 21 by mode conversion. FIG. 11 shows only the central axis 12A of the ultrasonic wave pulse of the transverse wave used for flaw detection.
Longitudinal ultrasonic pulses propagating through are omitted.

The transverse ultrasonic pulse propagated through the test body 21 is reflected when the flaw detection region 4 has a flaw. The reflected ultrasonic pulse of the transverse wave propagates in the opposite direction along the propagating path, becomes a longitudinal wave by mode conversion on the surface of the test body 21, propagates in the contact medium 7, and is received by the probe 3A. It

In such an operation, the flaw detection figure in the A scope display is as shown in FIG. Figure 1
In 2, 15 is a time gate for detecting flaws,
Reference numeral 17 is a transmission pulse, 18 is an echo reflected by the surface of the test body 21 and received, and 19 is an echo by a transverse wave reflected by a flaw and received. As shown in the figure, when an echo larger than the threshold value set in the time gate 15 is received, it is determined that there is a flaw.

The above is the operation of the conventional ultrasonic flaw detection method of this type, but as described above, a longitudinal wave propagates in the test body 21 by mode conversion. This longitudinal wave may affect the flaw detection test result. In such cases,
This will be described below with reference to FIG. In the figure,
13A is a propagation path when an ultrasonic pulse propagating in the contact medium 7 is incident perpendicularly to the surface of the test body 21, 1
4A is a propagation path of a longitudinal wave that propagates through the propagation path 13A and propagates in the test body 21.

Since the aperture width of the probe 3A is finite, the ultrasonic pulse spreads and propagates in the couplant 7. Therefore, the component propagating along the propagation path 13A is weaker than the component propagating along the central axis 11A. When the longitudinal wave is incident vertically, no mode conversion occurs. Also, it will not be refracted. Therefore, the longitudinal wave propagates in the test body 21 along the propagation path 14A without refraction and reaches the side surface of the test body 21. In this case, the longitudinal ultrasonic pulse is vertically incident on the side surface of the test body 21, is reflected vertically, and propagates in the opposite direction through the propagated path, so that the probe 3A is used. Be received.

FIG. 14 shows a flaw detection figure by the A scope display in such a case. In the figure, reference numeral 20 is an echo due to a longitudinal wave reflected by the side surface of the test body 21 and received. The echo 20 due to this longitudinal wave is received regardless of the presence or absence of a flaw.

As shown in FIG. 13, the beam path of the echo of the transverse wave reflected by the flaw and received is represented by the central axis 11.
The length is the sum of the length of A and the length of the propagation path 12A.
On the other hand, the beam path of the echo due to the longitudinal wave reflected by the side surface of the test body 21 and received is the length of the propagation path 13A and the propagation path 14A. That is, the beam path of the echo due to the longitudinal wave (dotted line) is longer than the beam path of the echo due to the transverse wave (solid line). However, since the longitudinal wave sound velocity is faster than the transverse wave sound velocity in a solid, the longitudinal wave echo 20 may be received at the same time as the transverse wave echo 19. In such a case, it is difficult to remove the echo 20 due to the longitudinal wave by the time gate 15. Therefore, the echo 20 due to the longitudinal wave may affect the echo 19 due to the transverse wave, and in this case, there is a problem that the accuracy of the flaw detection test is deteriorated.

On the other hand, there is an attempt to reduce the echo reflected on the side surface of the test body 21 to improve the accuracy of flaw detection. For example, Japanese Patent Application Laid-Open No. Sho 62-118252 (hereinafter referred to as "Document B") and Japanese Patent No. 2630.
No. 393 (hereinafter, referred to as “Document C”).

In the conventional technique described in Document B, the probe 3A is divided into a transmitting probe and a receiving probe,
By arranging the receiving probe in a place where the echo from the side surface of the test body 21 is hard to be received, the echo reflected by the side surface of the test body 21 and received is reduced. However, by providing a receiving probe,
The flaw detection system becomes complicated. Further, there is a problem that such a method cannot be applied when there is no physical space for installing the receiving probe.

In the conventional technique described in Document C, a reflector is provided between the probe 3A and the test body 21, and the propagation path of the echo 20 by the longitudinal wave, that is, the propagation shown in FIG. By physically blocking the paths 13A and 14A, the echo due to the longitudinal wave is removed. However, this method requires extra processing by providing the reflector, which increases the cost. Further, there is a problem that the reception sensitivity of the echo due to the transverse wave is slightly lowered.

[0015]

In the conventional ultrasonic flaw detection method as described above, when flaw detection is performed on a test piece such as a round bar, not only the echo reflected by the flaw but also the side surface of the test piece is reflected. There is a problem in that an echo due to a longitudinal wave is received, which affects the flaw detection test result and may deteriorate the flaw detection accuracy.

The present invention has been made to solve the above-mentioned problems, and a single probe is used without adding a reflector or the like in the vicinity of the test body, and the surface layer of the test body is used. An object of the present invention is to obtain an ultrasonic flaw detector and an ultrasonic flaw detection method capable of detecting a flaw existing in the vicinity thereof more accurately than in the conventional case.

[0017]

SUMMARY OF THE INVENTION An ultrasonic flaw detector according to the present invention propagates an ultrasonic pulse driven by a transmission signal into a test piece in a couplant to cause an acoustic discontinuity in the test piece. A probe that receives the ultrasonic pulse reflected by a section as a first echo and the ultrasonic pulse reflected by a side surface of the test piece as a second echo; and the probe. Scanning mechanism means for moving the to a predetermined position and outputting the spatial position thereof,
The transmission signal is generated and output to the probe, and from the probe, the first echo by the ultrasonic pulse reflected by the acoustic discontinuity in the test piece and the test piece The second echo of the ultrasonic pulse reflected by the side surface is input and stored, and the spatial position of the probe upon receiving the first and second echoes from the scanning mechanism means. To the scanning mechanism means for inputting and storing the control signal for moving the probe to a position where the reception sensitivity of the first echo is maximum with respect to the reception sensitivity of the second echo. And a transmitting / receiving means for outputting.

The ultrasonic flaw detector according to the present invention is
The positional relationship between the probe and the probe, which is the target of the flaw detection test actually performed by the transmitting / receiving means, is such that the receiving sensitivity of the first echo becomes maximum with respect to the receiving sensitivity of the second echo. As described above, the scanning mechanism means is constantly controlled.

The ultrasonic flaw detector according to the present invention propagates an ultrasonic pulse driven by a transmission signal into a test piece in a couplant and reflects the acoustic discontinuity in the test piece. A probe that receives an ultrasonic pulse as a first echo and also receives the ultrasonic pulse reflected by the side surface of the test piece as a second echo, and moves the probe to a predetermined position. And a scanning mechanism means for outputting the spatial position thereof, generating the transmission signal and outputting the transmission signal to the probe, and from the probe, the acoustic signal being reflected by the acoustic discontinuity in the test piece. The first echo generated by the ultrasonic pulse and the second echo generated by the ultrasonic pulse reflected by the side surface of the test piece are input and stored, and the first and second echoes are output from the scanning mechanism means. D The spatial position of the probe when the probe is received and stored, and the control signal for moving the probe is moved to the position where the reception sensitivity of the first echo is maximized. And a transmitting / receiving means for outputting to the mechanical means.

The ultrasonic flaw detector according to the present invention is
The transmission / reception unit constantly controls the scanning mechanism unit so that the positional relationship between the probe and the probe, which is the target of the actual flaw detection test, maximizes the reception sensitivity of the first echo. It is a thing.

The ultrasonic flaw detection method according to the present invention includes a transmission step of generating a transmission signal, outputting the transmission signal to the probe, and causing the probe to propagate an ultrasonic pulse into a test piece in a contact medium. The ultrasonic pulse reflected by the acoustic discontinuity in the test piece by the probe is received as a first echo, and the ultrasonic pulse reflected by the side surface of the test piece is received as a second echo. Reception step as an echo of the probe, a moving step of moving the probe to a predetermined position by the scanning mechanism means, and a first step by the ultrasonic pulse reflected by an acoustic discontinuity in the test piece. The echo and the second echo by the ultrasonic pulse reflected by the side surface of the test piece are input and stored, and the first and second eco signals are output from the scanning mechanism means. A storage step of inputting and storing a spatial position of the probe upon reception of the signal; and a position where the reception sensitivity of the first echo is maximum with respect to the reception sensitivity of the second echo, And a signal processing step of outputting a control signal for moving the probe to the scanning mechanism means.

The ultrasonic flaw detection method according to the present invention is
By the signal processing step, the positional relationship between the probe and the probe that is the target of the actual flaw detection test is determined by the second
The scanning mechanism means is always controlled so that the reception sensitivity of the first echo is maximized with respect to the reception sensitivity of the echo.

The ultrasonic flaw detection method according to the present invention includes a transmission step of generating a transmission signal, outputting the transmission signal to the probe, and causing the probe to propagate an ultrasonic pulse into a test piece in a contact medium. The ultrasonic pulse reflected by the acoustic discontinuity in the test piece by the probe is received as a first echo, and the ultrasonic pulse reflected by the side surface of the test piece is received as a second echo. Reception step as an echo of the probe, a moving step of moving the probe to a predetermined position by the scanning mechanism means, and a first step by the ultrasonic pulse reflected by an acoustic discontinuity in the test piece. The echo and the second echo by the ultrasonic pulse reflected by the side surface of the test piece are input and stored, and the first and second eco signals are output from the scanning mechanism means. A storage step of inputting and storing the spatial position of the probe when receiving the probe, and a control signal for moving the probe to a position where the reception sensitivity of the first echo is maximized. And a signal processing step of outputting to the scanning mechanism means.

Furthermore, in the ultrasonic flaw detection method according to the present invention, the positional relationship between the probe and the probe, which is a target for actually performing a flaw detection test, is determined by the signal processing step so that the first echo is received. The scanning mechanism means is constantly controlled so that the sensitivity is maximized.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. An ultrasonic flaw detector according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of an ultrasonic flaw detector according to Embodiment 1 of the present invention. In each figure, the same reference numerals indicate the same or corresponding parts.

In FIG. 1, 1 is a test piece such as a round bar, 2
Is an acoustic discontinuity near the surface of the test piece 1, 3 is a probe, 7 is a contact medium such as water, 10 is a case such as a water tank containing the contact medium 7 and the test piece 1, 11 is a contact medium 7 is a central axis of an ultrasonic pulse propagating in 7; 12 is a central axis of a transverse wave propagating in the central axis 11 and propagating in the test piece 1; 13 is an ultrasonic pulse incident perpendicularly to the surface of the test piece 1. In the case of doing so, a propagation path propagating in the couplant 7 (dotted line), 14 a longitudinal wave propagation path propagating in the propagation path 13 and propagating in the test piece 1 (dotted line), and 16 a test piece 1 and the probe. 3 is the center-to-center distance.

Further, as shown in the figure, the ultrasonic flaw detector comprises the above-mentioned probe 3, a transmitting / receiving device 80 connected to the probe 3, and a scanning mechanism for scanning and driving the probe 3. Part 9
With 0 and. In addition, there is "Test piece 1", but this is
It is used when setting the ultrasonic flaw detection device to obtain conditions suitable for flaw detection, and has a different meaning from the "test body" that is actually the target of the ultrasonic flaw detection test.

As the acoustic discontinuity 2 existing in the test piece 1, there are lateral holes and slits, but the shape thereof is arbitrary. The inside may be hollow or may be filled with the contact medium 7. That is, there are various acoustic discontinuities 2. Here for simplicity,
The "acoustic discontinuous portion 2" will be described as "a flaw 2".

Further, in the figure, the transmitting / receiving device 80
Includes a controller 81, a transmitter 82, a receiver 83, a signal processor 84, and a position detector 85 of the probe 3. The scanning mechanism unit 90 includes a position detection sensor (not shown).

Furthermore, in the figure, the probe 3 is
It is connected to the transmitter 82 and the receiver 83 by a signal line. The receiving unit 83 is connected to the signal processing unit 84.
The position detector 85 is connected to the signal processor 84.
The controller 81 includes a transmitter 82, a receiver 83, and a signal processor 8.
4, the position detector 85, and the scanning mechanism 90.

Further, in the figure, the scanning mechanism section 90 is
The output signal from the position detection sensor of the scanning mechanism unit 90, which is connected to the position detection unit 85, is input to the position detection unit 85. The position information of the probe 3 detected by the position detection unit 85 is input to the signal processing unit 84. Here, the probe 3
The positional information of is the center distance 16 between the test piece 1 and the probe 3.
Means

When the position information of the probe 3 can be obtained only by the signal from the control unit 81, the position information of the probe 3 (center-to-center distance 16), that is, the position detection unit 85.
The position information may be input to the signal processing unit 84 using only the information from the control unit 81 without using the information from the.

The signal processing unit 84 has a memory (not shown). In this memory, various results calculated and calculated by the signal processing unit 84 are stored as appropriate, and an input signal input to the signal processing unit 84 is stored as appropriate.

Further, although not shown, a signal indicating the processing status is appropriately input from the signal processing unit 84 to the control unit 81. Based on the input signal, the control unit 81 causes the transmission unit 82, the reception unit 83, the signal processing unit 84, the position detection unit 8
5, and outputs a control signal to the scanning mechanism unit 90,
It controls them.

Next, the operation of the ultrasonic flaw detector according to the first embodiment will be described with reference to FIGS. 2 to 9. In addition, in order to perform flaw detection on the entire surface layer portion of a test piece such as a round bar, it is necessary to rotate the test piece or the ultrasonic flaw detection device. Since a similar result is obtained in both cases, a system for rotating the test body is assumed here. That is, the test piece 1 will be described as rotating.

The transmitter 82 of the transmitter / receiver 80 generates a narrow pulse that can be regarded as an impulse, or a transmission signal such as a burst signal having a certain carrier frequency and transmits it to the probe 3. Probe 3
Is driven by the transmitted signal and emits ultrasonic pulses into the couplant 7. Longitudinal ultrasonic pulses propagate in the contact medium 7. This longitudinal ultrasonic pulse propagates through the contact medium 7 and then reaches the surface of the test piece 1. In FIG. 1, the central axis of the ultrasonic pulse propagating in the contact medium 7 is 1
The solid line is shown as 1.

On the surface of the test piece 1, the longitudinal wave propagating in the couplant 7 has a component reflected, but the test piece 1
There is also a component that penetrates inside. Since the mode conversion occurs on the surface of the test piece 1, the component that penetrates into the test piece 1 is
Although it is divided into a longitudinal wave and a transverse wave, when the incident angle is larger than the longitudinal wave critical angle and smaller than the transverse wave critical angle, only the transverse wave propagates in the test piece 1. FIG. 1 shows such a case in which the incident angle formed by the central axis of the ultrasonic pulse in the contact medium 7 and the normal line of the test piece 1 is such. In FIG. 1, the central axis of the transverse wave propagating in the test piece 1 is indicated by reference numeral 12 and is shown by a solid line.

Although not shown, the test piece 1 is connected to a rotating mechanism, and the test piece 1 is rotating in the circumferential direction. Therefore, the flaw 2 on the surface layer of the test piece 1 always exists at the moment when it crosses the central axis 12 of the transverse wave propagating in the test piece 1. FIG. 1 shows the moment when the flaw 2 crosses the central axis 12 of the transverse wave propagating in the test piece 1. Therefore, if the repetition period of the transmission signal transmitted from the transmission unit 82 is sufficiently short, the transverse wave is always emitted to the flaw 2.

Transverse waves applied to the flaw 2 are reflected, scattered,
Be diffracted. Here, the word "reflection" is treated as including not only reflection but also physical phenomena such as scattering and diffraction. That is, the word "reflection" is
It is understood that the propagation of ultrasonic waves is affected by the flaw 2 and includes all the phenomena in which the behavior behaves differently as compared to the case where the flaw 2 does not exist. When the flaw 2 has a spherical shape as shown in FIG. 1 or a cylindrical shape when viewed two-dimensionally, the reflected, scattered, and diffracted ultrasonic pulses generate transverse waves and longitudinal waves due to mode conversion.

The longitudinal wave generated by the flaw 2 is refracted when it reaches the surface of the test piece 1 and propagates in the contact medium 7, but does not propagate in the direction of the central axis 11 of the ultrasonic pulse.
The sensitivity received at is small. In addition, since the reception time is short, it is possible to separate by the time gate. Therefore, it does not affect the flaw detection test results and is ignored here. On the other hand, the transverse wave generated by being reflected by the flaw 2 propagates in the opposite direction along the central axis 12 of the transverse wave and becomes a longitudinal wave by mode conversion on the surface of the test piece 1 and propagates in the couplant 7. It is received by the tentacle 3. The echo of the received transverse wave is
The signal is amplified by the receiver 83 and sent to the signal processor 84.

Since the size of the probe 3 is finite, the ultrasonic pulse spreads in the contact medium 7 and propagates.
In FIG. 1, the test piece 1 propagates by propagating through the contact medium 7.
The propagation path incident perpendicularly to the surface of is indicated by 13 by a dotted line.

When the ultrasonic beam is vertically incident on the test piece 1, no refraction or mode conversion occurs, and a longitudinal wave propagates in the test piece 1. In FIG. 1, the propagation path of this longitudinal wave is indicated by reference numeral 14 and is shown by a dotted line. The longitudinal wave propagating in the test piece 1 reaches the side surface of the test piece 1. Test piece 1
When the test piece 1 has a circular cross-section as shown in FIG. 1, the light enters perpendicularly to the surface of the test piece 1. The vertically incident longitudinal wave is reflected vertically, propagates in the opposite direction in the propagation path 14, penetrates the surface of the test piece 1, propagates in the contact medium 7, and is received by the probe 3. The echo by the received longitudinal wave is amplified by the receiving unit 83 and sent to the signal processing unit 84.

On the other hand, the scanning mechanism section 90 detects information on the spatial position of the probe 3, and the information is detected by the position detection section 8
Sent to 5. Here, the spatial position information is the center-to-center distance 16. The center-to-center distance 16 detected by the position detector 85 is sent to the signal processor 84. In the signal processing unit 84, the center-to-center distance 16 is stored in the memory together with the echo due to the transverse wave propagating in the test piece 1 as the transverse wave and the echo due to the longitudinal wave propagating in the test piece 1 as the longitudinal wave.

Next, the probe 3 is moved by the scanning mechanism section 90.
Is laterally moved by a distance of a predetermined scanning pitch so that the center-to-center distance 16 changes. Then, the ultrasonic pulse is reflected from the probe 3 by the transmission signal from the transmitting unit 82, and the echo due to the transverse wave reflected and received by the flaw 2 and the side surface of the test piece 1 are received as in the previous case. The echoes due to the generated longitudinal waves and the center-to-center distance 16 when these echoes were obtained are stored in a memory in the signal processing 84.

This series of operations is performed over a predetermined range while moving the probe 3. After that, the control unit 8
1, the signal processing unit 84 and the scanning mechanism unit 90 perform processing described later.

Before describing the processing performed by the control unit 81, the signal processing unit 84, and the scanning mechanism unit 90, the reception sensitivity of the echo due to the transverse wave reflected by the flaw 2 and received (hereinafter referred to as "transverse wave reception"). Sensitivity "), and how the echo reception sensitivity of an echo due to a longitudinal wave reflected by the side surface of the test piece 1 (hereinafter referred to as" longitudinal wave reception sensitivity ") changes depending on the center-to-center distance 16. I will explain.

First, the reason why the shear wave reception sensitivity changes depending on the center-to-center distance 16 will be described.

As described above, the transverse wave propagating in the test piece 1 is transmitted through the boundary surface between the test piece 1 and the couplant 7, so that the round-trip transmittance at this boundary surface has a great influence.

FIG. 2 shows the round-trip transmissivity of transverse waves when the contact medium 7 is water and the test piece 1 is steel. The horizontal axis is the refraction angle of the transverse wave. The reciprocal transmittance increases as the refraction angle increases from zero, but the reciprocal transmissivity becomes zero when the refraction angle is close to 33 °, and then rapidly increases, and the reciprocal transmissivity shows a peak when the refraction angle is near 40 °. . After this peak is shown, the round-trip transmittance is uniformly reduced. This characteristic shows substantially the same tendency when the contact medium 7 is a liquid other than water and when the test piece 1 is a solid other than steel.

When the center-to-center distance 16 is zero, the central axis 11 of the ultrasonic pulse propagating in the couplant 7 is perpendicular to the test piece 1. That is, the incident angle becomes zero. When the incident angle is zero, a transverse wave due to mode conversion does not occur, so that the round-trip transmittance becomes zero as shown in FIG. In reality, since the ultrasonic pulse spreads and propagates because the size of the probe 3 is finite, the transverse wave reception sensitivity does not become zero even when the center-to-center distance 16 is zero, but it is a very small value. Become.

As the center-to-center distance 16 increases from zero, the central axis 11 of the ultrasonic pulse propagating in the contact medium 7
Is incident on the surface of the test piece 1 with a certain incident angle. That is, when the center-to-center distance 16 increases, the incident angle increases, and the refraction angle increases accordingly. Therefore, the shear wave reception sensitivity changes according to the round-trip transmittance shown in FIG.

Actually, since the ultrasonic pulse spreads in the contact medium 7 and also in the test piece 1, the echo sensitivity change due to the transverse wave does not become the same as the round-trip transmittance. However, the tendency that the round-trip transmittance increases with an increase in the center-to-center distance 16 and then decreases after showing a peak is maintained. Therefore, taking the center-to-center distance 16 on the horizontal axis and the transverse wave reception sensitivity on the vertical axis,
The characteristics are as shown in FIG.

Next, the longitudinal wave reception sensitivity is determined by the distance between the center axes of 16
Explain the reason why it changes by.

The echo by the longitudinal wave propagates through the propagation path 13 when it is incident perpendicularly to the surface of the test piece 1 and the propagation path 14 of the longitudinal wave which propagates in the test piece 1 and is received. In addition, although there are actually echoes that are received through a propagation path that is not perpendicular to the surface of the test piece 1,
Since its sensitivity is small, it will be ignored here for explanation.

When the center-to-center distance 16 is zero, the central axis 11 of the ultrasonic pulse propagating in the couplant 7 coincides with the central axis of the test piece 1, so that it is perpendicular to the surface of the test piece 1. The incident component is large. Therefore, the longitudinal wave reception sensitivity also increases.

As the center-to-center distance 16 increases from zero, the central axis 11 of the ultrasonic pulse propagating in the contact medium 7
Does not coincide with the central axis of the test piece 1. In this case, the component incident perpendicularly to the surface of the test piece 1 is a component due to the spread of the ultrasonic pulse. As the center-to-center distance 16 increases, the spread angle of the ultrasonic pulse incident perpendicularly to the surface of the test piece 1 increases, as can be seen from FIG. The intensity of the component due to the spread of the ultrasonic pulse becomes smaller as the spread angle becomes larger.
As 6 becomes larger, the component incident perpendicularly to the surface of the test piece 1 becomes smaller. Therefore, the longitudinal wave reception sensitivity is reduced. Therefore, when the center-to-center distance 16 is plotted on the abscissa and the longitudinal wave reception sensitivity is plotted on the ordinate, the outline is as shown in FIG.

Further, in the actual flaw detection test, since the flaw on the surface layer of the test body is detected by using the echo of the transverse wave, the echo of the transverse wave becomes a signal component. On the other hand, the echo caused by the longitudinal wave is a noise component because it is received regardless of the presence or absence of flaws in the test body. That is, the transverse wave reception sensitivity with respect to the longitudinal wave reception sensitivity can be considered as S / N in this case. The change in S / N with the change in the center-to-center distance 16 is
It is obtained by dividing the characteristic shown in FIG. 3 by the characteristic shown in FIG. Therefore, when the center-to-center distance 16 is taken on the horizontal axis and the S / N is taken on the vertical axis, the outline is as shown in FIG.
As shown in FIG. 5, the S / N shows a characteristic that it increases as the center-to-center distance 16 increases, shows a peak, and then decreases.

FIG. 3, FIG. 4 and FIG. 5 are diagrams for qualitative explanation, but the characteristics obtained by actual experiments are as follows.
This is shown in FIGS. 6, 7 and 8. These experimental results are the experimental results when the test piece 1 is a round bar having a diameter of 18 mm and the length of the central axis 11 of the ultrasonic pulse propagating in the couplant 7 is 113 mm. The test piece 1 is steel and the couplant 7 is water.

FIG. 6 is a transverse wave reception sensitivity for the center-to-center distance 16, FIG. 7 is a longitudinal wave reception sensitivity for the center-to-center distance 16, and FIG.
Is the ratio of the sensitivity of the transverse wave to the longitudinal wave, that is, S / N. As shown in FIG. 6, also in the experimental results, the shear wave reception sensitivity increases as the center-to-center distance 16 increases,
It shows the characteristic of decreasing after showing the peak.
Further, as shown in FIG. 7, the longitudinal wave reception sensitivity has a characteristic that it uniformly decreases as the center-to-center distance 16 increases. Therefore, the S / N shows a peak at a certain value as shown in FIG.

The reason why the transverse wave reception sensitivity, the longitudinal wave reception sensitivity, and the transverse wave reception sensitivity with respect to the longitudinal wave reception sensitivity, that is, the S / N changes with the change in the center-to-center distance 16 has been described above. Next, the processing performed by the signal processing unit 84 and the scanning mechanism unit 90 will be described.

As described above, in the memory in the signal processing unit 84, the center-to-center distance 16 at each probe position when the probe 3 is moved at a predetermined scanning pitch, the echo due to the transverse wave, and the longitudinal wave. Echoes of waves are stored. First,
From these two echoes, the transverse wave reception sensitivity and the longitudinal wave reception sensitivity corresponding to the center distance 16 at each probe position are obtained.

Next, the center distance 1 at each probe position
The transverse wave reception sensitivity with respect to the longitudinal wave reception sensitivity corresponding to No. 6, that is, S / N is obtained. Then, the center-to-center distance 16 that maximizes the S / N for the test piece 1 is extracted.
The center-to-center distance 16 is set to "d0" here.

The information of d0 is transmitted from the signal processing unit 84 to the control unit 81. From the control unit 81, the center distance 16
Is transmitted to the scanning mechanism section 90, and based on this control signal, the scanning mechanism section 90 causes the probe 3 to move.
To move. By this processing, the center-to-center distance 16 becomes d
It becomes 0.

The above-described processing is performed before the actual flaw detection test, and this state, that is, the center distance 16 is set to d0. This d0 is the center-to-center distance 16 that maximizes the S / N when the test piece 1 is targeted. However, in the case of a test body having the same diameter as the test piece 1, the center-to-center distance 16 that maximizes the S / N. Is the same as d0. Therefore, if the flaw detection test is performed with the center distance 16 fixed at d0, a high S /
Since N is obtained, the flaw detection accuracy can be improved in the flaw detection test.

FIG. 9 shows a flowchart of the operation of the ultrasonic flaw detector described above. In the flowchart of FIG. 9, the control unit 81 controls the scanning mechanism unit 9
The description of the control signal from the control unit 81 is omitted except for the description of controlling 0, but the control signal from the control unit 81 controls all the steps in the figure.

In step S100, the transmitter / receiver 8
The control unit 81 of 0 transmits the transmission signal from the transmission unit 82 to the probe 3. With this excitation signal, an ultrasonic pulse propagates from the probe 3 to the contact medium 7.

Next, in step 101, the test piece 1
Echo due to the transverse wave reflected by the inner flaw 2 and the test piece 1
The receiving unit 83 receives the echo due to the longitudinal wave reflected by the side surface of the probe 3 from the probe 3.

In step S 102, in parallel with the above step 101, the position information of the probe 3, that is, the signal regarding the center-to-center distance 16 is sent from the scanning mechanism 90 to the position detector 85.

Next, in step S103, the position detecting section 85 of the transmitter / receiver 80 detects the previous step S1.
The center-to-center distance 16 is detected based on the output signal obtained in 02.

Then, in step S104, the echo reception sensitivity (transverse wave reception sensitivity) due to the transverse wave and the echo reception sensitivity (longitudinal wave reception sensitivity) due to the longitudinal wave obtained in the previous step S101 are stored in the signal processing unit 84. To the memory of. In addition, the signal processing unit 84 associates the center-to-center distance 16 obtained in the previous step S103 with each receiving sensitivity.
Store in internal memory.

Next, in step S105, it is determined whether or not the probe 3 has scanned within a preset predetermined range. If the scanning is not performed within the predetermined range, the process proceeds to step S106. On the other hand, when the probe 3 scans within a predetermined range, the process proceeds to the next step S107.

In step S106, the controller 81
Causes the scanning mechanism unit 90 to move the probe 3 by a distance of a predetermined scanning pitch which is set in advance. After step S106, steps S100 to S100 are performed.
Repeat up to 105.

Next, in step S107, the signal processing unit 84 causes the center-to-center distance 1 at each probe position to be 1
The transverse wave reception sensitivity and the longitudinal wave reception sensitivity corresponding to 6 are obtained, the ratio (S / N) of the transverse wave reception sensitivity to the longitudinal wave reception sensitivity is calculated, and the center distance 16 at which this S / N becomes maximum is extracted. This value is d0 here.

Next, in step S108, the information of d0 is transmitted from the signal processing unit 84 to the control unit 81.

Next, in step S109, a control signal for setting the center-to-center distance 16 to d0 is transmitted from the control section 81 to the scanning mechanism section 90.

Then, in step S110, the probe 3 is moved by the scanning mechanism 90 to move the center distance 16
Be d0.

By performing the above steps, the center-to-center distance 16 (= d0) that maximizes the S / N for the test piece 1 can be obtained, and the probe 3 is located at this position. Can be moved. The center-to-center distance 16 (= d which maximizes the S / N when the test piece 1 is targeted)
If the probe 3 is fixed to 0) and a test piece having the same diameter as the test piece 1 is subjected to flaw detection, a high S / N can be obtained, so that the accuracy of the flaw detection test result can be improved.

If d0 is known, it is not necessary to use the test piece 1, and step S109 in FIG.
The center-to-center distance 16 can be set to d0 simply by performing steps S110 and S110. That is, by transmitting a control signal such that the center-to-center distance 16 becomes d0 from the control unit 81 to the scanning mechanism unit 90, the scanning mechanism unit 90 moves the probe 3 to set the center-to-center distance 16 to d0. A high S / N can be obtained, and the accuracy of the flaw detection test result can be improved.

By the way, in an actual flaw detection test, the position of a test piece such as a round bar may deviate from the initially set position. This is called "eccentricity". When this eccentricity occurs, flaw detection is performed in a state different from the center-to-center distance set before the flaw detection test. However, the center distance 1
If 6 is set to d0, even if eccentricity occurs and the center-to-center distance deviates from d0, the change in S / N is small as shown in FIG. Therefore, if the center-to-center distance 16 is set to d0 first, flaw detection can be performed with a relatively stable S / N against eccentricity, so that flaw detection accuracy can be improved in flaw detection tests. There is an effect.

As described above, in the first embodiment, by setting the center-to-center distance 16 to the transverse wave reception sensitivity with respect to the longitudinal wave reception sensitivity, that is, a value at which S / N shows a peak, a high S / N can be obtained, and a relatively stable S / N can be obtained even if eccentricity occurs,
This has an effect that the detection accuracy can be improved in the flaw detection test.

Embodiment 2. An ultrasonic flaw detector according to Embodiment 2 of the present invention will be described with reference to the drawings. The configuration of the ultrasonic flaw detector according to the second embodiment is the same as that of the above-described first embodiment, and the description thereof will be omitted.

As described in the first embodiment, eccentricity occurs in the actual flaw detection test. The operation of the ultrasonic flaw detector when this eccentricity occurs will be described below.

First, the position detection sensor in the scanning mechanism section 90 obtains information about the center distance between the test body and the probe 3, and transmits this information to the position detection section 85 to detect the test body and the probe. The center distance from the child 3 is calculated. Then, the value of the obtained center-to-center distance is transmitted to the control unit 81, and from the control unit 81, a control signal such that the center-to-center distance 16 becomes d0 is transmitted to the scanning mechanism unit 90, and based on this control signal. The scanning mechanism 90 moves the probe 3 and controls it so that the center-to-center distance is d0. By always performing such feedback processing, the center-to-center distance 16 can always be d0.

As described above, according to the second embodiment, the center-to-center distance between the test body and the probe 3 is set to the transverse wave reception sensitivity with respect to the longitudinal wave reception sensitivity, that is, the value at which the S / N shows a peak. By always setting to, there is an effect that a high S / N can be obtained and the detection accuracy in the flaw detection test can be improved.

Third Embodiment An ultrasonic flaw detector according to Embodiment 3 of the present invention will be described with reference to the drawings. The configuration of the ultrasonic flaw detector according to the third embodiment is the same as that of the above-described first embodiment, and the description thereof will be omitted.

When the diameter of the test body is large, in order to propagate the transverse wave in the test body at the required angle, the center distance between the test body and the probe 3 should be made larger than that when the diameter of the test body is small. There is a need to. In such a situation, the longitudinal wave reception sensitivity is very small, and thus the noise component is small. But,
Instead of longitudinal wave receiving sensitivity, the receiving sensitivity of the forest echo becomes a problem as noise.

The forest echo is an echo caused by crystal grains in the material or its texture. Therefore, the larger the diameter of the test body, the larger the forest echo, which becomes a noise component. Further, the forest echo does not much depend on the distance between the centers of the test body and the probe 3. Therefore, if the noise component is the reception sensitivity of the forest echo, the S / N is maximized if the shear wave reception sensitivity is maximized. in this way,
The operation of the ultrasonic flaw detector for maximizing the transverse wave reception sensitivity will be described with reference to FIG.

FIG. 10 is a flow chart similar to that of FIG. 9, but the operations after step S207 are different. That is, in the first embodiment, the transverse wave reception sensitivity with respect to the longitudinal wave reception sensitivity is set to S / N, and the center-to-center distance 16 (= d0) at which this S / N becomes maximum is obtained.

In the third embodiment, step S207
Then, the signal processor 84 determines the center-to-center distance 16 at which the shear wave reception sensitivity is maximized. This value is set to "d1". Next, in step S208, the signal processing unit 84 outputs d
The information of No. 1 is transmitted to the control unit 81.

Next, in step S209, a control signal for causing the center-to-center distance 16 to be d1 is transmitted from the control section 81 to the scanning mechanism section 90, and then in step S210, the scanning mechanism section 90 detects the probe. By moving the child 3 so that the center-to-center distance 16 becomes d1, the transverse wave reception sensitivity can be maximized and the accuracy of the flaw detection test result can be improved.

If the center-to-center distance 16 is set to d1, even if the center-to-center distance 16 deviates from the center-to-center distance 16 and the center-to-center distance 16 deviates from d1, the change in the transverse wave reception sensitivity is small.
Therefore, if the center-to-center distance 16 is set to d1 first, flaw detection can be performed with a relatively stable S / N against eccentricity, so that the flaw detection accuracy can be improved in the flaw detection test. is there.

As described above, in the third embodiment, a high S / N ratio can be obtained by setting the center-to-center distance 16 to a value at which the transverse wave reception sensitivity shows a peak, and Even if eccentricity occurs, a relatively stable S / N can be obtained, so that the detection accuracy can be improved in the flaw detection test.

Fourth Embodiment An ultrasonic flaw detector according to Embodiment 4 of the present invention will be described with reference to the drawings. The configuration of the ultrasonic flaw detector according to the fourth embodiment is similar to that of the above-described first embodiment, and thus the description thereof will be omitted.

As described in the first embodiment, eccentricity occurs in the actual flaw detection test. The operation of the ultrasonic flaw detector when this eccentricity occurs will be described below.

First, information about the center distance 16 between the test body and the probe 3 is obtained by the position detection sensor in the scanning mechanism section 90, and this information is transmitted to the position detection section 85, and the test body and the probe are detected. The center distance 16 from the child 3 is obtained. Then, the calculated value of the center-to-center distance 16 is transmitted to the control unit 81, and the control unit 81 transmits a control signal to the scanning mechanism unit 90 so that the center-to-center distance 16 becomes “d1”. Based on the above, the scanning mechanism unit 90 moves the probe 3 and controls the center distance 16 to be d1. By always performing such feedback processing, the center-to-center distance 16 can always be d1.

As described above, in the fourth embodiment, the center-to-center distance 16 between the test body and the probe 3 is always set to a value at which the transverse wave reception sensitivity shows a peak.
It is possible to obtain a high S / N and to improve the detection accuracy in the flaw detection test.

[0097]

As described above, the ultrasonic flaw detector according to the present invention propagates the ultrasonic pulse driven by the transmission signal into the test piece in the couplant so as to cause the acoustic imperfections in the test piece. The ultrasonic pulse reflected by the continuous portion is received as a first echo, and the ultrasonic pulse reflected by the side surface of the test piece is received as a second echo.
A probe that receives as an echo of, a scanning mechanism means that outputs the spatial position by moving the probe to a predetermined position, and outputs the transmission signal to the probe, From the probe, a first echo by the ultrasonic pulse reflected by the acoustic discontinuity in the test piece and a second echo by the ultrasonic pulse reflected by the side surface of the test piece. Is input and stored, and the spatial position of the probe when the first and second echoes are received from the scanning mechanism means is input and stored, and the spatial sensitivity of the second echo is received. On the other hand, since a transmission / reception means for outputting a control signal for moving the probe to the scanning mechanism means is provided at a position where the reception sensitivity of the first echo is maximized, the test piece is provided near the surface layer of the test piece. Better accuracy than existing flaws An effect that can be detected.

The ultrasonic flaw detector according to the present invention is
As described above, the positional relationship between the probe and the probe, which is the target for actually performing the flaw detection test, is determined by the transmitting / receiving means with respect to the reception sensitivity of the second echo with respect to the reception sensitivity of the first echo. Since the scanning mechanism means is constantly controlled so that the sensitivity is maximized, the detection accuracy can be improved in the flaw detection test.

As described above, the ultrasonic flaw detector according to the present invention propagates an ultrasonic pulse driven by a transmission signal into a test piece in a couplant to cause an acoustic discontinuity in the test piece. A probe for receiving the ultrasonic pulse reflected as a first echo and a second echo receiving the ultrasonic pulse reflected by the side surface of the test piece as a second echo; Scanning mechanism means for moving to a predetermined position and outputting the spatial position thereof, and generating and transmitting the transmission signal to the probe, and from the probe, an acoustic discontinuity in the test piece. The first echo by the ultrasonic pulse reflected by the ultrasonic wave and the second echo by the ultrasonic pulse reflected by the side surface of the test piece are input and stored, and the scanning mechanism means The spatial position of the probe when receiving the first and second echoes is input and stored, and the probe is moved to a position where the reception sensitivity of the first echo is maximized. Since the transmission / reception means for outputting the control signal to the scanning mechanism means is provided, it is possible to improve the detection accuracy in the flaw detection test.

The ultrasonic flaw detector according to the present invention is
As described above, the transmitting / receiving unit has a positional relationship between the probe and the probe that is the target of the actual flaw detection test, so that the reception sensitivity of the first echo is maximized.
Since the scanning mechanism means is constantly controlled, it is possible to improve the detection accuracy in the flaw detection test.

As described above, the ultrasonic flaw detection method according to the present invention generates a transmission signal and outputs it to a probe, and the probe propagates an ultrasonic pulse into a test piece in a contact medium. And a step of receiving the ultrasonic pulse reflected by an acoustic discontinuity in the test piece by the probe as a first echo, and transmitting the ultrasonic pulse reflected by a side surface of the test piece. A receiving step of receiving a sound wave pulse as a second echo, a moving step of moving the probe to a predetermined position by a scanning mechanism means, and the ultrasonic wave reflected by an acoustic discontinuity in the test piece. The first echo by the pulse and the second echo by the ultrasonic pulse reflected by the side surface of the test piece are input and stored, and the first echo by the scanning mechanism means is input. A storing step of inputting and storing the spatial position of the probe at the time of receiving the first and second echo, the relative receiving sensitivity of the second echo first
The signal processing step of outputting a control signal for moving the probe to the scanning mechanism means at a position where the echo reception sensitivity of (1) is maximized can improve the detection accuracy in the flaw detection test. Has the effect.

Further, the ultrasonic flaw detection method according to the present invention is
As described above, in the signal processing step, the positional relationship between the probe and the probe, which is the target of the actual flaw detection test, is different from that of the first echo with respect to the reception sensitivity of the second echo. Since the scanning mechanism means is constantly controlled so that the reception sensitivity is maximized, the detection accuracy can be improved in the flaw detection test.

As described above, the ultrasonic flaw detection method according to the present invention generates a transmission signal and outputs it to a probe, and the probe propagates an ultrasonic pulse into a test piece in a contact medium. And a step of receiving the ultrasonic pulse reflected by an acoustic discontinuity in the test piece by the probe as a first echo, and transmitting the ultrasonic pulse reflected by a side surface of the test piece. A receiving step of receiving a sound wave pulse as a second echo, a moving step of moving the probe to a predetermined position by a scanning mechanism means, and the ultrasonic wave reflected by an acoustic discontinuity in the test piece. The first echo by the pulse and the second echo by the ultrasonic pulse reflected by the side surface of the test piece are input and stored, and the first echo by the scanning mechanism means is input. A storage step of inputting and storing the spatial position of the probe when receiving the first and second echoes, and the probe at the position where the reception sensitivity of the first echo is maximized. Since it includes a signal processing step of outputting a control signal for moving to the scanning mechanism means, it is possible to improve the detection accuracy in the flaw detection test.

Further, in the ultrasonic flaw detection method according to the present invention, as described above, in the signal processing step, the positional relationship between the test body which is the target of the flaw detection test and the probe is the first. Since the scanning mechanism means is always controlled so that the reception sensitivity of the echo 1 is maximized,
This has an effect that the detection accuracy can be improved in the flaw detection test.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an ultrasonic flaw detector according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing the relationship between the refraction angle and the round-trip transmittance of the ultrasonic flaw detector according to Embodiment 1 of the present invention.

FIG. 3 is a diagram showing the relationship between the center-to-center distance and the shear wave reception sensitivity of the ultrasonic flaw detector according to Embodiment 1 of the present invention.

FIG. 4 is a diagram showing the relationship between the center-to-center distance and the longitudinal wave reception sensitivity of the ultrasonic flaw detector according to Embodiment 1 of the present invention.

FIG. 5 is a diagram showing the relationship between the center-to-center distance and the S / N of the ultrasonic flaw detector according to Embodiment 1 of the present invention.

FIG. 6 is a diagram showing experimental results on the relationship between the center-to-center distance and the shear wave reception sensitivity of the ultrasonic flaw detector according to Embodiment 1 of the present invention.

FIG. 7 is a diagram showing experimental results on the relationship between the center-to-center distance and the longitudinal wave reception sensitivity of the ultrasonic flaw detector according to Embodiment 1 of the present invention.

FIG. 8 is a diagram showing experimental results on the relationship between the center-to-center distance and the S / N of the ultrasonic flaw detector according to Embodiment 1 of the present invention.

FIG. 9 is a flowchart showing the operation of the ultrasonic flaw detector according to Embodiment 1 of the present invention.

FIG. 10 is a flowchart showing an operation of the ultrasonic flaw detector according to Embodiment 3 of the present invention.

FIG. 11 is a diagram showing a configuration of a conventional ultrasonic flaw detector.

FIG. 12 is a diagram showing an operation of a conventional ultrasonic flaw detector.

FIG. 13 is a diagram showing a configuration of another conventional ultrasonic flaw detector.

FIG. 14 is a diagram showing an operation of another conventional ultrasonic flaw detector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 test piece, 2 acoustic discontinuity part, 3 probe, 7 contact medium, 10 case, 80 transceiver, 81 control part, 82 transmission part, 83 reception part, 84 signal processing part,
85 position detection unit, 90 scanning mechanism unit.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoji Tanaka Marunouchi 2-3-3, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (56) Reference JP-A-63-243751 (JP, A) JP-A-62 -240855 (JP, A) JP 63-236959 (JP, A) JP 3-296694 (JP, A) JP 62-118252 (JP, A) JP 2630393 (JP, B2) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (8)

(57) [Claims] 1. An ultrasonic pulse driven by a transmitted signal is propagated through a test piece in a couplant, the ultrasonic pulse reflected by an acoustic discontinuity in the test piece being a first echo. And a probe that receives the ultrasonic pulse reflected by the side surface of the test piece as a second echo, and outputs the spatial position by moving the probe to a predetermined position. Scanning mechanism means for generating the transmission signal, outputting the transmission signal to the probe, and the first echo by the ultrasonic pulse reflected from the acoustic discontinuity in the test piece from the probe. And a second echo due to the ultrasonic pulse reflected by the side surface of the test piece are input and stored, and the probe when the first and second echoes are received from the scanning mechanism means is input. Tentacle An interim position is input and stored, and the control signal for moving the probe is moved to a position where the reception sensitivity of the first echo is maximum with respect to the reception sensitivity of the second echo. An ultrasonic flaw detector, comprising: a transmitting / receiving unit for outputting to a mechanical unit. 2. The transmitting / receiving means is arranged such that a positional relationship between a test body which is an object to be actually subjected to a flaw detection test and the probe is the reception sensitivity of the second echo with respect to the reception sensitivity of the second echo. The ultrasonic flaw detector according to claim 1, wherein the scanning mechanism means is constantly controlled so that the sensitivity is maximized. 3. An ultrasonic pulse driven by a transmitted signal is propagated through a test piece in a couplant, the ultrasonic pulse reflected by an acoustic discontinuity in the test piece being a first echo. And a probe that receives the ultrasonic pulse reflected by the side surface of the test piece as a second echo, and outputs the spatial position by moving the probe to a predetermined position. Scanning mechanism means for generating the transmission signal, outputting the transmission signal to the probe, and the first echo by the ultrasonic pulse reflected from the acoustic discontinuity in the test piece from the probe. And a second echo due to the ultrasonic pulse reflected by the side surface of the test piece are input and stored, and the probe when the first and second echoes are received from the scanning mechanism means is input. Tentacle And a transmission / reception unit for outputting a control signal for moving the probe to the scanning mechanism unit at a position where the reception sensitivity of the first echo is maximized. An ultrasonic flaw detector characterized by the above. 4. The scanning mechanism, wherein the transmitting / receiving means is arranged so that the positional relationship between the probe and the probe, which is the target of the actual flaw detection test, maximizes the receiving sensitivity of the first echo. The ultrasonic flaw detector according to claim 3, wherein the means is constantly controlled. 5. A transmission step of generating and outputting a transmission signal to a probe, and causing the probe to propagate an ultrasonic pulse into a test piece in a contact medium, and the probe causes the test piece to propagate. A receiving step of receiving the ultrasonic pulse reflected by an acoustic discontinuity therein as a first echo, and receiving the ultrasonic pulse reflected by a side surface of the test piece as a second echo; A moving step of moving the probe to a predetermined position by a scanning mechanism means, a first echo by the ultrasonic pulse reflected by an acoustic discontinuity in the test piece, and a side surface of the test piece A second echo generated by the ultrasonic pulse reflected by the scanning section and stored therein, and an empty space of the probe when the first and second echoes are received from the scanning mechanism means. A storage step of inputting and storing an interim position; and a control signal for moving the probe to a position where the reception sensitivity of the first echo is maximum with respect to the reception sensitivity of the second echo. And a signal processing step of outputting to the scanning mechanism means. 6. In the signal processing step, the positional relationship between the probe and the probe, which is an object to be actually subjected to a flaw detection test, is determined by comparing the reception sensitivity of the second echo with that of the first echo. The ultrasonic flaw detection method according to claim 5, wherein the scanning mechanism means is constantly controlled so that the reception sensitivity is maximized. 7. A transmission step of generating and outputting a transmission signal to a probe, and causing the probe to propagate an ultrasonic pulse into a test piece in a couplant, and a step of transmitting the test piece by the probe. A receiving step of receiving the ultrasonic pulse reflected by an acoustic discontinuity therein as a first echo, and receiving the ultrasonic pulse reflected by a side surface of the test piece as a second echo; A moving step of moving the probe to a predetermined position by a scanning mechanism means, a first echo by the ultrasonic pulse reflected by an acoustic discontinuity in the test piece, and a side surface of the test piece A second echo generated by the ultrasonic pulse reflected by the scanning section and stored therein, and an empty space of the probe when the first and second echoes are received from the scanning mechanism means. A storage step of inputting and storing an interim position, and a signal processing step of outputting a control signal for moving the probe to the scanning mechanism means to a position where the reception sensitivity of the first echo is maximized. An ultrasonic flaw detection method comprising: 8. The signal processing step, wherein the positional relationship between the probe and the probe, which is the target of the actual flaw detection test, maximizes the reception sensitivity of the first echo,
8. The ultrasonic flaw detection method according to claim 7, wherein the scanning mechanism means is constantly controlled.