JP3279473B2 - Bevel flaw detection method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oblique flaw detection method and apparatus for transmitting and receiving an ultrasonic wave to a test object at a specific incident angle and detecting a defect in the test object, and the oblique flaw detection apparatus. The present invention relates to an ultrasonic inspection apparatus using the apparatus.

[0002]

2. Description of the Related Art Techniques for improving the S / N ratio of a detection signal in a reflector position detecting device using surface waves include, for example, JP-A-63-214664 and JP-A-63-1988.
The technique described in Japanese Patent Application No. 262562 is known. On the other hand, a longitudinal wave oblique flaw detection method is also known as a method used for detecting a defect in a welded portion. However, in this method, since the SN ratio of the detection signal is low, the accuracy is low, and the use range is limited. Therefore, it is desired to improve the SN ratio in such an oblique flaw detection method.
As described in Japanese Patent No. 14165, there is also known a method in which the distance between a probe and a defect is fixed, ultrasonic waves are transmitted and received a plurality of times, and a received signal is subjected to time addition processing to improve the SN ratio.

[0003]

However, in the prior art in the oblique flaw detection, noise that is randomly generated on the time axis such as electric noise is averaged and relatively reduced. However, no consideration is given to reducing noise generated at a specific position on the time axis such as a reflected wave from a non-target object, and as a result, the SN ratio has not been sufficiently improved. .

The present invention has been made in view of such a background, and has as its object to relatively reduce random noise and noise at a specific position, improve the SN ratio of a detection signal in oblique flaw detection, An object of the present invention is to provide an oblique flaw detection method and an oblique flaw detection apparatus capable of detecting a minute defect in a welded portion with high sensitivity.

Another object of the present invention is to provide an ultrasonic inspection apparatus capable of inspecting a weld in a nuclear power plant for defects using the above-mentioned oblique flaw detection apparatus.

[0006]

In order to achieve the above object, a first means is to scan an ultrasonic probe on an object to be inspected and to obliquely scan the surface of the object to be inspected within the object to be inspected. Oblique angle to detect the presence and position of the object from the reflected wave data of the object and the position signal of the ultrasonic probe obtained by transmitting the ultrasonic wave at the incident angle and receiving the reflected signal from the object In the flaw detection method, reflected wave data of the object and an ultrasonic probe
A step of determining a virtual position of the object from a position signal of said the step of setting a delay time in accordance with the relative positions of the virtual position of the object of the ultrasonic probe, the set delay time offset And adding the waveform of the received signal to increase the reflected wave intensity by adding the waveform of the received signal to perform the detection.

In this case, the step of adding the waveform of the received signal includes determining a virtual defect position in the x direction from the peak value of the signal obtained by adding the received signal in the y direction at each position to be measured.
Based on this virtual defect position, it is preferable to include a process of setting a time shift amount according to the relative position in the x direction and adding the waveforms of the received signals. Note that the time shift amount (Δt) is defined assuming that a propagation distance from the virtual defect position is L ₀ , a propagation distance from a position shifted by an arbitrary distance from the virtual defect position is L _i , and a sound speed is C. , Δt = 2 (L _i −L ₀ ) / C.

In the step of adding the waveform,
The region to which the waveform is added can also be set from the beam spread of the ultrasonic probe, which is measured in advance.

[0009] The transmission wave transmitted to the ultrasonic probe may be a burst wave, and the burst wave may be applied to the detection of a defect of an object arranged via a gap.

The second means scans the ultrasonic probe on the object to be inspected, transmits ultrasonic waves into the object to be inspected at an oblique incident angle with respect to the surface of the object to be inspected, and simultaneously transmits the ultrasonic waves from the object. In an oblique flaw detector which detects the presence and position of an object from reflected wave data of the object obtained by receiving a reflected signal and a position signal of the ultrasonic probe , the reflected wave data of the object and the ultrasonic wave
Obtains the virtual position of the object from the position signal of the probe, the calculating means for setting a delay time in accordance with the relative positions of the virtual position of the object of the ultrasonic probe, the waveform sum of the received signal Waveform adding means for performing processing. Note that the waveform addition processing is performed at each position to be measured.
From the peak value of the signal obtained by adding the received signal in the y direction
Find the virtual defect position in the x direction, and refer to this virtual defect position
And set the time shift amount according to the relative position in the x direction.
The time shift
The amount (Δt) is, for example, the propagation from the virtual defect position.
The distance is L ₀ , and the distance is shifted by an arbitrary distance from the virtual defect position.
Where L _{i is} the propagation distance from the set position and C is the sound speed
In an amount set by _{Δt = 2 (L i -L 0} ) / C.

In this case, there is further provided means for storing a waveform addition area set from the beam spread of the ultrasonic probe which has been measured in advance, and the waveform addition means executes an addition process in the waveform addition area. It can also be configured as follows.

[0012] Further, transmission means for transmitting a burst wave to the ultrasonic probe and transmission control means for controlling the frequency of the burst wave according to the gap length in the body to be inspected are further provided, and the transmission means is arranged via the gap. It can also be configured to detect a defect in the inspected body.

Further, the ultrasonic probe is constituted by an ultrasonic array probe in which a plurality of ultrasonic probes are arranged in a straight line, and a delay time of each probe of the ultrasonic array probe. It is also possible to provide a delay control means for setting the distance and a switching means for switching the operation of each probe, and to electrically scan and change the position without physically moving the probe. it can.

The inspection object can be applied to, for example, a shroud of a nuclear power plant or a CRD stub tube.
The oblique flaw detector may be incorporated in an ultrasonic inspection apparatus as a means for detecting a defect in a welded portion of a stub tube, and inspection may be performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a measurement principle and an embodiment of the present invention will be described with reference to the drawings.

[Measurement Principle] First, the principle of the oblique flaw detection method according to the present invention will be described with reference to FIGS. In the present invention, it is necessary to set the time shift amount for each received signal according to the relative position between the defect and the probe, and therefore, it is necessary to obtain the virtual position of the defect. Hereinafter, a method of setting the virtual position of the defect will be described.

FIG. 2 is a diagram for explaining the inspection method of the present invention. Here, an inspection method for detecting a defect 21 in the welded portion 22 of the inspection object 20 is shown. In this example, the z-axis perpendicular to the upper surface of the object 20 (the x-axis and the y-axis are set parallel to the upper surface) from the probe 14 arranged on the upper surface of the object 20 to the object 20 to be inspected. It is.)
With respect to a predetermined incident angle θ (for example, 45
The ultrasonic beam 15 is transmitted in the direction of (°), and the reflected wave from the defect 21 is received. Here, x the probe 14 on the device under test 20, y direction [Delta] x _i, is scanned two-dimensionally by [Delta] y _j pitch unit, each position (x _i, y _j) received signal E at (i, j) Is received and stored in the waveform memory.

Next, a virtual defect position x ₀ is obtained using the received signal E (i, j). Here, the defect is a defect in the y-direction parallel to the welded portion that frequently occurs.
Accordingly, at a position near x _i defects reflected wave is received, it is possible to increase the strength of the defect reflected wave by adding each received signal in the y direction. With this processing, it is possible to determine the virtual position of the defect. Position as shown in FIG. 3 (x _i, y _j) the received signal E (i, j) between the position (x
_i, y _{j +} 1) and adding the received signal E (i, j + 1),
The intensity of the defect echo 42 can be increased. FIG. 4 shows the relationship between the peak value p of the defect echo 42 thus obtained and the position in the x direction. The position having the maximum peak value p ₀ in the relationship 43 between the position x and the peak value p is defined as a virtual defect position x ₀ . In this way, a virtual defect position serving as a reference for the waveform addition processing is obtained.

Hereinafter, the principle of the present invention using the waveform addition processing for reducing the specific position noise and increasing the defect echo will be described.

FIGS. 5 and 6 are explanatory diagrams showing the principle of the waveform addition processing. The ultrasonic wave 15 is transmitted and received at the virtual defect position x ₀ of the probe 14 and the received signal E ₀ (t) from the defect 21 is transmitted.
To receive. Then, shift the probe 14 only Δx _i,
The ultrasonic wave 15 is transmitted and received from the position x _i and the received signal E
_i (t) is received. The distance from the received signal E _i (t) at the position x ₀ to the defect 21 of the position x _i becomes longer, Delta] t from the specific position noise 41 propagation time of defect echo 42
Shift by _i . This shift time Δt _i is

[0021]

(Equation 1)

## EQU2 ##

Here, L ₀ is the propagation distance at the virtual defect position x ₀ , L _i is the propagation distance at the position x _i , and C is the speed of sound.

On the other hand, noise not caused by defects
That is, since the specific position noise 41 does not depend on scanning of the probe 14, even if the probe 14 is shifted as shown in FIG. 6, the reflected wave appears at the same propagation time. Here, the received signal E _i (t) the -.DELTA.t _i shifted signal E _i (t-
Δt _i ). In this signal E _i (t−Δt _i ),
The defect echo 42 appears at the same propagation time as the signal E ₀ (t). Further, specific position noise 41 is to shift the time of the original signal, the propagation time varies depending on the distance [Delta] x _i. Therefore, by adding the signal E ₀ (t) and the signal E _i (t−Δt _i ) obtained by shifting the time of the original signal,
In the defect echo 42, the intensity is high because the phases of the reflected waves are the same. On the other hand, since the specific position noise 41 does not have the same phase, the intensity is low. The signal S obtained by changing the position of the probe 14 and adding E _i (t−Δt _i ) n times as described above
(T)

[0025]

(Equation 2)

## EQU2 ## In the signal S (t), the specific position noise is reduced, the intensity of the defect echo is increased, and the SN ratio of the detection signal is improved.

The S / N ratio of the detection signal can be improved by performing the above-described waveform addition processing.

[First Embodiment] Next, an oblique flaw detector according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of the oblique flaw detector according to the first embodiment, and FIG. 8 is a diagram showing transmission / reception signals.

In FIG. 1, the oblique flaw detector includes a transmitter 1, a receiver 2, a gate circuit 3, an A / D converter 4, a waveform memory 5, a waveform data calculator 6, a scanning controller 7, and a scanning mechanism 8. , Position detector 9, memory 10, data storage unit 11, waveform data display unit 12, image display unit 13, and probe 14
It is basically composed of In the oblique flaw detector including such components, first, the transmitter 1 transmits a transmission pulse P (t) to the probe 14. As a result, the ultrasonic beam 15 is transmitted from the probe 14 into the test object 20 at a predetermined incident angle, and if there is a defect 21 in the welded portion 22, the reflected wave from the defect 21 is reflected by the probe 14. Receive. On the other hand, an electric noise 40 is superimposed on the signal E ″ (t) received by the probe 14 and amplified by the receiver 2 as shown in FIG. And only specific echoes (position noise 41 and defect echo 42) are extracted to become a signal E ′ (t). This signal E ′ (t) is stored as a digital signal in the waveform memory 5 via the A / D converter 4. The stored waveform data is sent to the waveform data calculation unit 6, where the above-described time averaging process is performed to reduce the electric noise 40, and the memory 1
0 is stored as the received signal E (t) at each position. A memory 10 and a data storage unit 11 are connected to the waveform data calculation unit 6, and calculations such as an addition process of the waveform data are executed. The calculation result is displayed on the waveform data display unit 12 in the form of a waveform, and is displayed on the image display unit 13 in the form of, for example, cross-sectional information of the inspected object visualized by ultrasonic waves. Further, the probe 14 is connected to a scanning mechanism 8 that can scan in the x and y directions, and performs two-dimensional scanning in the x and y directions according to a command from the scanning control unit 7. The position signal in this scanning is transmitted to the position detector 9.
And sent to the waveform data calculation unit 6. Receiving signals at each position, the scanning position of the probe 14 (x _i, y _j) is stored in the memory 10 as the waveform data corresponding to.

FIG. 7 is a flow chart showing the algorithm of the oblique flaw detection in the oblique flaw detector constructed as described above. That is, in this algorithm, first, the probe 14 is two-dimensionally scanned, and the received signal at each position (x _i , y _j ) is time-averaged in a specific pitch unit, and the waveform memory is used as the received signal E (t). (Step 70)
1). Then, by adding each received signal in the y direction in the x-direction position x _i, obtains the peak value of the reflected wave propagation time which is expected to defects (step 702). Here, obtain the position x ₀ to the peak value of the reflected wave is maximum in the x-direction, the virtual defect position (step 703). The received signal E _i (t) at the position x _i is shifted by −Δt _i with reference to the virtual defect position x ₀ to obtain a signal E _i (t−Δt _i ) (step 704). Further, an addition process of the received signal E ₀ (t) at the position x ₀ and the signal E _i (t−Δt _i ) is executed (step 7).
05). Using such a waveform addition processing [Delta] x _i pitch shifted signal E _i received by the position (t), it is continuously executed until the end (step 706). Further, it is determined whether or not the defect signal strength obtained in this process is the maximum value (step 707). Here, if the defect signal strength is not the maximum,
While updating the virtual defect location x ₀ is continuously executed until the maximum value (step 708).

The experimental results obtained by performing the oblique flaw detection using the above-described apparatus and algorithm are as follows. FIG. 9 shows the configuration of the experimental apparatus, and FIG. 10 shows the experimental results.

The results of this experiment are as follows.
The slit 14 having a length of 10 mm existing in the weld 22 of No. 0 was detected, and the probe 14 was set to Δx _i = 0.2
This is a case where the beam is shifted by 5 mm and the angle of flaw detection is performed at an incident angle θ = 45 °.

In the original waveform shown in FIG. 10A, the intensity of the defect echo 42 is smaller than the intensity of the position noise 41, and the SN ratio is 1 or less. However, as shown in FIG. 10B, by performing the waveform addition processing represented by the equation (2), the intensity of the defect echo 42 can be made higher than the intensity of the position noise 41, and the SN ratio becomes 2 or more. can do. From this, it was confirmed that the present invention is effective for improving the SN ratio in oblique flaw detection. The number of additions in this embodiment is six.

[Second Embodiment] FIG. 11 is an explanatory diagram showing an outline of a second embodiment, and FIG. 12 is a characteristic diagram showing the spread of an ultrasonic beam in the x direction at a defect position.

As shown in FIG. 11, the ultrasonic beam 15u transmitted from the probe 14 has a specific spread.
Spread of the ultrasonic beam has the intensity distribution shown by reference numeral 43 in FIG. 12 around the position x _0. In the waveform addition processing, regions which contribute to the defect echo intensity improvement maximum I ₀ of the strength is considered to be up to the position x _e becomes I _0/2. Thus, it may be added to the waveform data from the position x ₀ to the position x _e in waveform addition. Therefore, to execute the waveform addition processing by using the waveform data from the position x ₀ to the position x _e in this embodiment. Note that the oblique flaw detector itself has the same configuration as that shown in FIG. 1 described above, and therefore, the same reference numerals are given to the same components, and description thereof will be omitted.

FIG. 13 is a flowchart showing the algorithm of the process when the ultrasonic beam is spread. In this algorithm, first, Step 700-1
The beam spread of the probe at the inspection position is measured in advance, and the addition areas x _{0 to} x _e are stored in the data storage unit 11. Then, the processing from step 701 to step 705 equivalent to that of FIG. 7 described above is executed, and step 706-1 is executed.
In using the waveform data from the position x ₀ in the setting the addition region x ₀ ~x _e to the position x _e executes waveform addition. Then, step 707 or step 7
07 and the processing of step 708 are executed, and the processing ends.
That is, in this embodiment, processing is performed by the same algorithm as that of the first embodiment except for the processing of step 700 and step 706-1.

[Third Embodiment] The third embodiment is an example in which the present invention is applied to an ultrasonic inspection in a case where there is a gap between two inspected objects as shown in FIG. .

In FIG. 14, it is assumed that the ultrasonic wave propagates from the medium 51 and propagates through the medium 52 in the gap 35 to the medium 53. The ultrasonic wave is applied to the medium 51 and the medium 5
2 and is reflected at the interface 54 between the medium 52 and the medium 5.
3 also reflects at the interface 55. However, when the gap length is 1/4 of the wavelength in the gap, the phase of the ultrasonic wave that has passed through the boundary surface 55 between the medium 52 and the medium 53 and the phase of the ultrasonic wave that has reciprocated through the gap 35 are opposite to each other. The ultrasonic waves propagating through 53 cancel each other (FIG. 14-C). On the other hand, when the gap length is の of the wavelength in the gap, the medium 5
Since the phase of the ultrasonic wave that has passed through the boundary surface 55 between the medium 2 and the medium 53 and the phase of the ultrasonic wave that has reciprocated through the gap 35 are the same, the ultrasonic waves that propagate through the medium 53 are strengthened and propagated to the medium 53 ( (FIG. 14-F). The condition for maximizing the intensity of the ultrasonic wave propagating through the gap 35 is as follows.

[0039]

(Equation 3)

Is represented by Where L is the gap length, λ
_w is the wavelength in the gap and n is an integer.

Further, the frequency at which the ultrasonic intensity becomes maximum is

[0042]

(Equation 4)

Is as follows. Where f _p is the pass frequency, v _w
Is the speed of sound in the gap.

Therefore, by setting an optimum frequency according to the gap length, the transmittance at the boundary surface 55 can be increased, and an ultrasonic inspection through the gap 35 can be realized.

FIG. 15 shows a schematic configuration of an oblique flaw detector which performs oblique flaw detection when there is a gap as described above. FIG. 16 is a diagram showing this transmission / reception signal. Here, as can be seen from the block diagram of FIG. 15, two probes, a first probe 14a for receiving a reflected wave from the defect 21 and a second probe 14b for receiving a reflected wave from the gap 35. Is used. Further, the transmitter 1 according to the first embodiment
, A power amplifier 1a, a burst wave generating circuit 1b, and a transmission control unit 1c are provided. The transmission control unit 1c is configured to be capable of bidirectional transmission and reception with the waveform data calculation unit 6, and a first search is performed from the power amplifier 1a. A signal is output to the contactor 14a, and a received signal is configured to be input to the receiver 2.
The signal received from the probe 14b is input to the receiver 2. The other components are configured in the same manner as the components in the first embodiment.

In the oblique flaw detector configured as described above,
A high-voltage burst wave 45 indicated by P (t) generated by the burst wave generation circuit 1b and the power amplifier 1a is applied to the first probe 14a. In response to this application, the first probe 1
4a, a burst wave-like ultrasonic wave 15a is
a, 20b are transmitted at a predetermined incident angle, and the defect 2
The second probe 14b receives the reflected wave g (t) by reflecting the ultrasonic wave 15b from the gap 35. The transmission control unit 1c receives this signal. The transmission frequency is set so that the gap echo intensity 46 of g (t) (FIG. 16) is minimized, and a high-voltage burst wave is transmitted to the first probe 14a. This is a burst-shaped ultrasonic signal E ″ (t).
Subsequent processing is the same as in the first embodiment.

The processing algorithm according to the third embodiment is shown in the flowchart of FIG. In this algorithm, first, a transmission burst wave P
The frequency of (t) is swept, and a gap passing frequency is set (step 700-2). An ultrasonic wave is transmitted using the transmission burst wave P (t) having the set frequency, and a waveform addition process is performed using the received waveform data. Subsequent processing is the same as the processing procedure in the first embodiment shown in FIG.

The experimental results obtained by performing the oblique flaw detection by the above-described apparatus and algorithm are as follows. FIG.
Shows the configuration of the experimental apparatus, and FIG. 18 shows the experimental results.

In this experiment, the second flat plate test piece 20a arranged via the gap 35 from the first flat plate test piece 20a was used.
b shows the results of an experiment in which a slit defect 21 in the welded portion 22 of the first and second flat plate specimens 20a and 20b was detected.
Are 16 mm and 19 mm, respectively, the length of the defect 21 is 10 mm, and Δx _i is 0.2 mm. In the original waveform shown in FIG.
Is smaller than the intensity of the position noise 41, and the SN ratio is 1
It is as follows. However, when the waveform addition processing of the present invention is performed as shown in FIG. 18B, the intensity of the defect echo 42 can be made higher than the intensity of the position noise 41 by 10 times of waveform addition processing, and the SN ratio becomes 2 Or more.
From this, it was confirmed that the flaw detection device and the flaw detection method according to the present embodiment were effective in improving the SN ratio in oblique flaw detection through a gap.

[Fourth Embodiment] FIG. 20 shows a fourth embodiment of the present invention.
It is a block diagram showing composition of an angle beam flaw detector concerning an embodiment. This embodiment is an example of an oblique flaw detector that electronically scans an ultrasonic beam in the x direction using an array probe in which a plurality of transducers are arranged.

In the oblique flaw detector, the first flaw detector shown in FIG.
In place of the probe 14 in the embodiment, an array probe 14c, a high-voltage switch 16, a delay element 17, and a delay control unit 17a are provided, and a switch control unit 16a and a position detection unit 16b are provided. The other components are configured in the same manner as the oblique flaw detector in the first embodiment.

In such a configuration, a transmission pulse is transmitted from the transmitter 1 to the array probe 36 via the delay element 17 and the high voltage switch 16. In the delay control unit 17a,
The delay time of each array element is set in the delay element 17 corresponding to the incident angle of the ultrasonic beam, and the array probe 14c
The ultrasonic beam 15 is transmitted into the test object 20 from.
The switch controller 16a sets control data for the high voltage switch 16, and by switching this high voltage switch 16, the ultrasonic beam 15 can be electronically scanned in the x direction of the inspection object 20. Further, the switch control unit 16a is connected to the position detection unit 16b, and x
The position data in the direction is input to the waveform data calculator 6. With such an operation, the ultrasonic beam is scanned in the x direction using the array probe 14c, and the received signal at each position is stored in the memory as waveform data corresponding to the scanning position (xi _{, yj} ) of the probe. 10 and are processed in the same manner as in the first embodiment.

The processing algorithm of the oblique flaw detector configured as described above is shown in the flowchart of FIG. In this algorithm, the ultrasonic beam is first scanned by electronically scanning the array probe in the x direction of the device under test and mechanically scanning the array probe in the y direction of the device under test. A dimensional scan is performed (step 700-3). As described above, in this embodiment, the scanning of the probe need only be performed by one-axis scanning in the y direction.
Subsequent processing is the same as in the first embodiment.

[Fifth Embodiment] FIG. 22 is a schematic view showing a fifth embodiment in which the oblique flaw detector according to the present invention is applied to an inspection device for a shroud welding line in a reactor pressure vessel.

In the same figure, the inspection device 63 is attached to the flange 60 on the upper part of the shroud 61, and performs inspection by moving in the circumferential direction and the axial direction under the control of the scanning control device 71. The tip of the inspection device 63 has a link structure, and the probe 14 can be installed near the welding line 62 while avoiding obstacles such as the jet pump 64. The flaw detection signal and the scanning position signal are sent to the ultrasonic inspection device 72, and various signal processings including the above-described processing are performed, and the inspection result is displayed as an image in a sectional view and a plan view.

[Sixth Embodiment] FIG. 23 is a schematic view showing a sixth embodiment in which the ultrasonic inspection device of the present invention is applied to an inspection device for a welded portion of a CRD stub tube at the lower part of a reactor pressure vessel. Inspection is performed by transmitting ultrasonic waves from the probe 14 installed in the CRD housing 83, and
Weld 8 between RD stub tube 81 and lower pressure vessel mirror 80
The second defect 84 is detected. The probe 14 is connected to the scanning control device 71 and has a CRD housing 83.
Scan inside. Further, the flaw detection signal and the scanning position signal are sent to the ultrasonic inspection apparatus 72, and various signal processings including the above-described processing are performed, and the inspection result is displayed as an image in a sectional view and a plan view. Note that this gap 35 corresponds to the gap 35 in the above-described third embodiment, and it is understood that the third embodiment is effective for inspection of such an apparatus.

[0057]

As described above , according to the present invention, the object
Of the target object from the reflected wave data of the
Obtain the virtual position, the position of the ultrasonic probe and the virtual position of the object
The delay time is set according to the relative position with respect to the position, and the waveform of the received signal shifted by the set delay time is added, so that the reflected wave intensity from the object is increased, and the random noise and the noise at the specific position are reduced. As a result, it is possible to relatively improve the SN ratio of the detection signal , and thereby, it becomes possible to detect minute defects in the welded portion with high sensitivity.

Further, it is possible to detect with high sensitivity a defect of a member located on the back side disposed through the gap.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an oblique flaw detector according to a first embodiment of the present invention.

FIG. 2 is a view for explaining an oblique flaw detection method according to the present invention.

FIG. 3 is a view for explaining the principle of the oblique flaw detection method according to the present invention.

FIG. 4 is a diagram showing a relationship between a peak value and a position used in the oblique flaw detection method according to the present invention.

FIG. 5 is a diagram illustrating a relationship between a shift amount of the probe and a position of the probe during waveform addition in the oblique flaw detection method according to the present invention.

FIG. 6 is a diagram for explaining the principle of waveform addition in the oblique flaw detection method according to the present invention.

FIG. 7 is a flowchart illustrating a processing procedure according to the first embodiment.

FIG. 8 is a diagram for explaining a waveform processing method according to the first embodiment.

FIG. 9 is a diagram for explaining an experimental result using the oblique flaw detector according to the first embodiment.

FIG. 10 is a diagram showing a state of a waveform addition process in the oblique flaw detector according to the first embodiment.

FIG. 11 is a diagram showing a flaw detection state of the oblique flaw detector according to the second embodiment.

FIG. 12 is a characteristic diagram illustrating a relationship between ultrasonic intensity and an addition area in oblique flaw detection according to the second embodiment.

FIG. 13 is a flowchart illustrating a processing procedure according to the second embodiment.

FIG. 14 is a diagram illustrating a state of transmission of ultrasonic waves according to the third embodiment.

FIG. 15 is a block diagram illustrating a configuration of an oblique flaw detector according to a third embodiment.

FIG. 16 is a diagram illustrating a state of signal processing when a burst wave is used in the third embodiment.

FIG. 17 is a view showing a state at the time of flaw detection of the oblique flaw detector according to the third embodiment.

FIG. 18 is a diagram showing a state of a waveform addition process in the oblique flaw detector according to the third embodiment.

FIG. 19 is a flowchart illustrating a processing procedure according to the third embodiment.

FIG. 20 is a block diagram illustrating a configuration of an oblique flaw detector according to a fourth embodiment.

FIG. 21 is a flowchart illustrating a processing procedure according to the fourth embodiment.

FIG. 22 is a diagram showing an example in which the bevel flaw detector of the present invention is applied to a shroud inspection device of a nuclear power plant.

FIG. 23 shows a case where the bevel flaw detector according to the present invention is used in a nuclear power plant.
It is a figure showing the example applied to the RD stub tube inspection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmitter 1a Power amplifier 1b Burst wave generation circuit 1c Transmission control unit 2 Receiver 3 Gate circuit 4 A / D converter 5 Waveform memory 6 Waveform data storage unit 7 Scanning control unit 8 Scanning mechanism 9 Position detector 10 Memory 11 Data Storage unit 12 Waveform data display unit 13 Image display unit 14, 14a, 14b Probe 14c Array probe 15 Ultrasonic 15a Burst ultrasonic 15b Reflected wave 15u Ultrasonic beam 16 High voltage switch 16a Switch control unit 16b Position Detecting unit 17 Delay element 17a Delay control unit 20 Inspection object 20a, 20b Flat plate test object 21 Defect part 22 Welding part 31 Time gate 35 Gap 40 Electric noise 41 Position noise 42 Defect echo 46 Gap echo intensity 71 Scan control device 72 Ultrasonic wave Inspection device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yudai Oura 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi, Ltd. Power & Electric Equipment Development Division (72) Inventor Fuminobu Takahashi Omika-cho, Hitachi City, Ibaraki Prefecture No. 7-2-1, Hitachi, Ltd. Electric Power & Electric Equipment Development Division (56) References JP-A-61-159156 (JP, A) JP-A-64-57165 (JP, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) G01N 29/00-29/28

Claims (12)

(57) [Claims] An ultrasonic probe is scanned on an object to be inspected, an ultrasonic wave is transmitted into the object to be inspected at an oblique incident angle with respect to the surface of the object to be inspected, and a reflected signal from the object is received. In the oblique flaw detection method of detecting the presence and position of the object from the reflected wave data of the object and the position signal of the ultrasonic probe obtained as described above, the reflected wave data of the object and the ultrasonic probe Position signal
A step of determining a virtual position of Luo object, said a step of setting a delay time in accordance with the relative positions of the virtual position of the object of the ultrasonic probe, reception signals which are shifted the set delay time Adding the waveform of the received signal, and performing the detection by increasing the reflected wave intensity by adding the waveform of the reception signal. 2. The method according to claim 1, wherein the step of adding the waveform includes obtaining a virtual defect position in the x direction from a peak value of a signal obtained by adding the received signal in the y direction at each position to be measured. 2. The oblique flaw detection method according to claim 1, further comprising a process of setting a time shift amount according to the relative position in the direction and adding a waveform of the received signal. 3. The time shift amount (Δt) is such that the propagation distance from the virtual defect position is L ₀ , the propagation distance from a position shifted by an arbitrary distance from the virtual defect position is L _i ,
The sound velocity is taken as _{C, Δt = 2 (L i} -L 0) / oblique flaw detection method according to claim 2, wherein the C is an amount that is set in. 4. The method according to claim 1, wherein, in the step of adding the waveform of the reception signal, an area to which the waveform is added is set based on a beam spread of the ultrasonic probe which has been measured in advance. The bevel flaw detection method described. 5. The oblique flaw detection method according to claim 1, wherein a transmission wave transmitted to the ultrasonic probe is a burst wave, and the subject is disposed via a gap. 6. An ultrasonic probe is scanned on an object to be inspected, an ultrasonic wave is transmitted into the object to be inspected at an oblique incident angle with respect to the surface of the object to be inspected, and a reflected signal from the object is received. In the oblique flaw detection device which detects the presence and the position of the object from the reflected wave data of the object and the position signal of the ultrasonic probe obtained as described above, the reflected wave data of the object and the ultrasonic probe Position signal
Calculated virtual position Luo object, the calculating means for setting a delay time in accordance with the relative positions of the virtual position of the object of the ultrasonic probe, the waveform adding means for performing waveform addition processing of the received signal And a bevel flaw detector characterized by comprising: 7. The method according to claim 1, wherein the waveform addition processing is performed for each position to be measured.
x from the peak value of the signal obtained by adding the received signal in the y direction
The virtual defect position in the direction is determined, and this virtual defect position is used as a reference.
And set the time shift amount according to the relative position in the x direction.
7. The oblique flaw detector according to claim 6 , further comprising a process of adding a waveform of the received signal . 8. The method according to claim 1, wherein the time shift amount (Δt) is the virtual shift amount (Δt).
The propagation distance from the defect position is L ₀ ,
The propagation distance from the position shifted by an arbitrary distance is _Li ,
The sound velocity is taken as _{C, Δt = 2 (L i} -L 0) / C that is an amount that is set at an oblique angle flaw detection apparatus according to claim 7, wherein. 9. An ultrasonic probe beam which has been measured in advance.
Means to store the waveform addition area set from the
In addition, the waveform adding means is provided in the waveform adding area.
7. The bevel flaw detector according to claim 6, wherein an addition process is performed . 10. A transmission of a burst wave to said ultrasonic probe.
The transmission means to be used and the bar
Transmission control means for controlling the frequency of the strike wave.
The bevel flaw detector according to claim 6 or 9, wherein 11. The ultrasonic probe according to claim 8, wherein said ultrasonic probe comprises a plurality of ultrasonic probes.
An ultrasonic array probe consisting of transducers arranged in a straight line
In both cases, the delay time of each probe of the ultrasonic array probe
Switching between the delay control means and the operation of each probe
7. A switching device comprising:
The oblique flaw detector according to any one of claims 9 and 10. 12. The method according to claim 6, wherein
The bevel flaw detector described is used for shrouds in nuclear power plants.
Or as a means for detecting defects in welds of CRD stub tubes
An ultrasonic inspection apparatus characterized in that it is included.