JPH09243608A - Oblique angle flaw detection method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the noise at a specific position like the reflected wave from a non-objective while enhancing only the intensity of the reflected wave from an objective and to enhance the relative SN ratio of a detection signal in oblique flaw detection. SOLUTION: Time shift quantity is set corresponding to the relative position of a probe 14 and a flaw 21 so that the phase only of the reflected wave from an object 20 to be inspected is matched with the same phase. The waveform operational processing of the mutual receiving signals at respective positions having this time shift quantity is executed by a waveform data operation part 6 to increase the intensity only of the reflected wave from the object. Since the phases of the receiving signals at the respective positions are different in the reflected wave from a non-objective, the intensity thereof is lowered by this waveform operational processing. By this constitution, the relative SN ratio of a detection signal can be enhanced in oblique angle flaw detection and the minute flaw of a welded part can be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oblique-angle flaw detection method and an oblique-angle flaw detection device for transmitting and receiving ultrasonic waves to and from an inspection target at a specific incident angle to detect defects in the inspection target, and this oblique-angle flaw detection. The present invention relates to an ultrasonic inspection device using the device.

[0002]

2. Description of the Related Art Techniques for improving the SN ratio of a detection signal in a reflector position detecting device using surface waves include, for example, Japanese Patent Application Laid-Open Nos. 63-214664 and 63.
The technique described in Japanese Patent No. 2626262 is known. On the other hand, a longitudinal wave bevel 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 range of use is limited. Therefore, it is desired to improve the SN ratio in such a bevel flaw detection method.
As described in Japanese Patent No. 14165, there is also known a method in which the distance between the probe and the defect is kept constant, ultrasonic waves are transmitted and received a plurality of times, and the received signals are time-added to improve the SN ratio.

[0003]

By the way, in the conventional technique in the above-mentioned oblique flaw detection, noises such as electrical noises which are randomly generated on the time axis are added and averaged to relatively reduce the noises. However, no consideration is given to the reduction of noise that occurs at a specific position on the time axis, such as reflected waves from non-objects, 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 an object thereof is to relatively reduce random noise and noise at a specific position and improve the SN ratio of a detection signal in oblique flaw detection. An object of the present invention is to provide a bevel angle flaw detection method and a bevel angle flaw detection device capable of detecting minute defects in a welded portion with high sensitivity.

Another object of the present invention is to provide an ultrasonic inspection apparatus capable of inspecting a welded portion of a nuclear power plant for defects by using the above-described bevel flaw detector.

[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 incline the object to be inspected with respect to the surface of the object to be inspected. Angle that detects 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 receiving the reflected signal from the object while transmitting the ultrasonic wave at the incident angle of In the flaw detection method, a step of setting a delay time according to the relative position of the ultrasonic probe and the object, and a step of adding the waveforms of the received signals comrades with the set delay time deviation,
It is characterized in that the presence or absence and the position of the object are detected by increasing the intensity of the reflected wave by adding the waveforms of the received signals.

In this case, in the step of adding the waveforms of the received signals, the virtual defect position in the x direction is obtained from the peak value of the signal obtained by adding the received signals in the y direction at each position to be measured,
It is preferable that the virtual defect position is used as a reference and 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 is included. It should be noted that the time shift amount (Δt) is obtained when L _{0 is} a propagation distance from the virtual defect position, L _{i is} a propagation distance from a position shifted from the virtual defect position by an arbitrary distance, and C is a sound velocity. , Δt = 2 (L _i −L ₀ ) / C.

In the step of adding the waveforms,
It is also possible to set the area where the waveforms are added from the divergence of the beam of the ultrasonic probe that has been measured in advance.

Further, it is also possible to use a transmission wave to be transmitted to the ultrasonic probe as a burst wave and apply it to the detection of a defect of a subject arranged through 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 at the same time from the object. In the bevel flaw detector that detects the presence and position of the object from the reflected wave data of the object obtained by receiving the reflected signal and the position signal of the ultrasonic probe, the relative position of the ultrasonic probe and the object It is characterized in that it is provided with a computing means for setting a delay time according to the position and a waveform adding means for performing a waveform adding process of a received signal.

In this case, there is further provided means for storing the waveform addition area set from the beam divergence of the ultrasonic probe measured in advance, and the waveform addition means executes the addition processing in the waveform addition area. It can also be configured as follows.

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 are arranged via the gap. It can also be configured to detect defects in the inspected body.

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

The inspected object can be applied to, for example, a shroud of a nuclear power plant or a CRD stub tube, whereby a shroud or a CRD is used.
The oblique angle flaw detection device may be incorporated in the ultrasonic inspection device as a defect detection means for the welded portion of the stub tube to perform the inspection.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The measurement principle and embodiments of the present invention will be described below with reference to the drawings.

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

FIG. 2 is a diagram for explaining the inspection method of the present invention. Here, the inspection method for detecting the defect 21 in the welded portion 22 of the inspection object 20 is shown. In this example, from the probe 14 arranged on the upper surface of the inspected object 20 into the inspected object 20, the z axis perpendicular to the upper surface of the inspected object 20 (x axis and y axis parallel to the upper surface are set. It is assumed that
For the 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, the probe 14 is two-dimensionally scanned in the x and y directions in Δx _i and Δy _j pitch units on the inspected object 20, and the received signal E (i, j) at each position (x _i, y _j ) is obtained. Is received and stored in the waveform memory.

Next, using this received signal E (i, j), a virtual defect position x ₀ is obtained. Here, the defect is targeted at a defect in the y direction which is parallel to the welded part having a high occurrence frequency.
Therefore, the intensity of the defect reflected wave can be increased by adding the respective received signals in the y direction in the vicinity x _i of the position where the defect reflected wave is received. By this processing, it becomes 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
_If the received signals E (i, j + 1) of _i, y _{j +} 1) are added,
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 crest value p ₀ in the relationship 43 between the position x and the crest value p is defined as a virtual defect position x ₀ . In this way, the virtual defect position that is the reference for the waveform addition process is obtained.

The principle of the present invention using the waveform addition process for reducing the specific position noise and enhancing the defect echo will be described below.

5 and 6 are explanatory views 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 reception signal E ₀ (t) from the defect 21 is transmitted.
To receive. Next, shift the probe 14 by 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 _i only. 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 the scanning of the probe 14, the reflected wave appears at the same propagation time even if the probe 14 is shifted as shown in FIG. Here, the received signal E _i (t) is shifted by −Δt _i, and the signal E _i (t−
Consider Δt _i ). With this signal E _i (t−Δt _i ),
The defect echo 42 appears at the same propagation time as the signal E ₀ (t). Further, since the specific position noise 41 shifts the time of the original signal, its propagation time changes depending on the distance Δx _i . Therefore, by adding the signal E ₀ (t) and the time-shifted signal E _i (t−Δt _i ) of the original signal,
In the defect echo 42, since the phases of the reflected waves are the same, the intensity is high. On the other hand, the specific position noise 41 does not have the same phase, so the intensity is low. In this way, the signal S obtained by changing the position of the probe 14 and adding E _i (t−Δt _i ) n times
(T)

[0025]

[Equation 2]

## EQU2 ## In this 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 executing the waveform addition processing as described above.

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

In FIG. 1, the bevel flaw detector comprises 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 scan 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 angle flaw detection device 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 object 20 to be inspected at a predetermined angle of incidence, and if there is a defect 21 in the welded portion 22, the probe 14 reflects the reflected wave from the defect 21. To receive. On the other hand, electric noise 40 is superimposed on the signal E "(t) received by the probe 14 and amplified by the receiver 2. This signal E" is time gate 31 by the gate circuit 3. The specific echo (positional noise 41 and defect echo 42) is extracted and becomes 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, and the above-mentioned time addition and averaging process is performed to reduce the electrical noise 40.
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 addition processing of waveform data are performed. The calculation result is displayed on the waveform data display unit 12 in the form of a waveform, and on the image display unit 13 in the form of cross-sectional information of an object to be inspected visualized by ultrasonic waves. Further, the probe 14 is connected to a scanning mechanism 8 capable of scanning in the x and y directions, and two-dimensionally scans in the x and y directions according to a command from the scanning control unit 7. The position signal in this scanning is the position detector 9
Is detected by and is sent to the waveform data calculation unit 6. The received signal at each position is stored in the memory 10 as waveform data corresponding to the scanning position (x _i , y _j ) of the probe 14.

The algorithm of the bevel flaw detection in the bevel flaw detector thus constructed is shown in the flowchart of FIG. That is, in this algorithm, first, the probe 14 is two-dimensionally scanned, and the reception signals at each position (x _i , y _j ) are time-averaged in a specific pitch unit to obtain a reception signal E (t) in a waveform memory. (Step 70)
1). Next, each received signal in the y direction is added at the position x _i in the x direction to obtain the peak value of the reflected wave having the propagation time expected to be a defect (step 702). Here, the position x _{0 at} which the peak value of the reflected wave is maximum in the x direction is obtained and set as a virtual defect position (step 703). With reference to this virtual defect position x ₀ , the received signal E _i (t) at the position x _i is shifted by −Δt _i to obtain the signal E _i (t−Δt _i ) (step 704). Further, addition processing 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). Such waveform addition processing is continuously executed until the end by using the signal E _i (t) received at the position shifted by Δx _i pitch (step 706). Further, it is judged whether or not the defect signal strength obtained by this processing is the maximum value (step 707). Here, if the defect signal strength is not maximum,
The virtual defect position x ₀ is updated and continuously executed until the maximum value is reached (step 708).

The results of the experiment in which the oblique flaw detection is performed by the above apparatus and algorithm are as follows. FIG. 9 shows the configuration of the experimental device, and FIG. 10 shows the experimental result.

The results of this experiment are shown in FIG.
The slit defect 21 having a length of 10 mm existing in the welded portion 22 of 0 is detected, and the probe 14 is set to Δx _i = 0.2.
This is a case in which oblique angle flaw detection is performed at an incident angle θ = 45 ° after shifting by 5 mm.

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, by performing the waveform addition process shown in equation (2) as shown in FIG. 10B, 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 in improving the SN ratio in oblique angle flaw detection. The number of additions in this embodiment is six.

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

As shown in FIG. 11, the ultrasonic beam 15u transmitted from the probe 14 has a specific spread.
The divergence of the ultrasonic beam has an intensity distribution as indicated by reference numeral 43 in FIG. 12 centered on the position x ₀ . In the waveform addition process, it is considered that the region contributing to the improvement of the defect echo intensity is up to the position x _e at which the maximum intensity I ₀ becomes I _0/2 . Therefore, in the waveform addition processing, the waveform data from the position x ₀ to the position x _e may be added. Therefore, in this embodiment, the waveform addition processing is executed using the waveform data from the position x ₀ to the position x _e . Since the bevel flaw detector itself is configured in the same manner as that shown in FIG. 1 described above, the same reference numerals are given to the same parts and the description thereof will be omitted.

The algorithm of the processing when the ultrasonic beam is thus spread is shown in the flowchart of FIG. In this algorithm, first, step 700-1
Then, the divergence of the beam 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, which is equivalent to that in 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
The processing of 07 and step 708 is 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 ultrasonic inspection in the case where there is a gap between two inspection objects as shown in FIG. .

In FIG. 14, it is assumed that the ultrasonic wave propagates from the medium 51 and propagates to the medium 53 via the medium 52 in the gap 35. Ultrasonic waves are medium 51 and medium 5.
2 is reflected by the interface 54 with the medium 2, and the medium 52 and the medium 5 are further reflected.
It is also reflected on the boundary surface 55 with 3. However, when the gap length is ¼ of the wavelength in the gap, the phases of the ultrasonic waves that have passed through the boundary surface 55 between the medium 52 and the medium 53 and the ultrasonic waves that have reciprocated through the gap 35 are opposite phases, The ultrasonic waves propagating through 53 cancel each other (FIG. 14-C). On the other hand, when the gap length is half the wavelength in the gap, the medium 5
The ultrasonic waves that have passed through the boundary surface 55 between the medium 2 and the medium 53 and the ultrasonic waves that have reciprocated through the gap 35 have the same phase, so that the ultrasonic waves that propagate through the medium 53 strengthen each other and propagate to the medium 53 ( Figure 14-F). The conditions under which the intensity of the ultrasonic wave propagating through the gap 35 is maximum are as follows.

[0039]

(Equation 3)

It 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 is maximum is

[0042]

(Equation 4)

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

Therefore, by setting the optimum frequency in accordance with the gap length, it is possible to increase the pass ratio at the boundary surface 55 and realize ultrasonic inspection through the gap 35.

FIG. 15 shows a schematic structure of a bevel flaw detector for performing bevel flaw detection when there is such a gap. FIG. 16 is a diagram showing this transmission / reception signal. Here, as can be seen from the block diagram of FIG. 15, the two probes, that is, the first probe 14a that receives the reflected wave of the defect 21 and the second probe 14b that receives the reflected wave from the gap 35. Is used. In addition, the transmitter 1 in the first embodiment
Instead, a power amplifier 1a, a burst wave generation circuit 1b, and a transmission control unit 1c are provided, and the transmission control unit 1c is configured to be capable of bidirectionally transmitting and receiving with the waveform data calculation unit 6, and the power amplifier 1a is connected to the first search unit. A signal is output to the tentacle 14a and the received signal is input to the receiver 2.
The signal received from the probe 14b is input to the receiver 2. The other parts are configured in the same manner as the parts in the first embodiment described above.

In the oblique angle flaw detector thus constructed,
The burst wave 45 represented by P (t) of high voltage 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
A burst wave ultrasonic wave 15a is emitted from 4a.
Defect 2 is transmitted with a certain incident angle in a and 20b.
1 receives the reflected wave E ″ (t). On the other hand, in the second probe 14b, the ultrasonic wave 15b is reflected from the gap 35, and the reflected wave g (t) is received. The transmission frequency is set so that the gap echo intensity 46 (FIG. 16) of g (t) is minimized, and a high-voltage burst wave is transmitted to the first probe 14a. It is a burst wave ultrasonic signal E ″ (t).
Subsequent processing is the same as that of the first embodiment described above.

The processing algorithm of the third embodiment is shown in the flowchart of FIG. In this algorithm, first, the transmitted burst wave P
The frequency of (t) is swept and the gap passing frequency is set (step 700-2). Ultrasonic waves are transmitted using the transmission burst wave P (t) having the set frequency, and waveform addition processing is executed using the received waveform data. The subsequent processing is the same as the processing procedure in the first embodiment shown in FIG.

The results of the experiment in which the oblique flaw detection is performed by the above-described device and algorithm are as follows. FIG.
Fig. 18 shows the configuration of the experimental apparatus, and Fig. 18 shows the experimental results.

In this experiment, the second flat plate test body 20 arranged from the first flat plate test body 20a through the gap 35 was used.
It is an experimental result which detected the slit defect 21 in the welding part 22 of b, and is the 1st and 2nd flat plate test body 20a, 20b.
The plate thicknesses were 16 mm and 19 mm, the defect 21 was 10 mm in length, and Δx _i was 0.2 mm. In the original waveform shown in FIG. 18A, the defect echo 42
Is smaller than 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 performing the waveform addition processing 10 times, and the SN ratio is 2 The above can be done.
From this, it has been confirmed that the flaw detection apparatus and flaw detection method of the present embodiment are effective in improving the SN ratio in oblique angle flaw detection through a gap.

[Fourth Embodiment] FIG. 20 shows a fourth embodiment of the present invention.
It is a block diagram showing a configuration of a bevel flaw detector according to the embodiment. This embodiment is an example of a bevel 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 this bevel flaw detector, the first flaw angle 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 controller 17a are provided, and a switch controller 16a and a position detector 16b are provided. The other parts are configured in the same manner as the bevel flaw detector in the first embodiment described above.

In such a configuration, the transmitter 1 transmits a transmission pulse 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 in accordance with the incident angle of the ultrasonic beam.
The ultrasonic beam 15 is transmitted from the inside of the object 20 to be inspected.
The control data of the high-voltage switch 16 is set in the switch control unit 16a, and by switching the 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
Directional position data is input to the waveform data calculation unit 6. By such an operation, the array probe 14c is used to scan the ultrasonic beam in the x direction, and the received signal at each position is stored in the memory as waveform data corresponding to the scanning position (x _i, y _j ) of the probe. 10 and processed in the same manner as in the first embodiment.

The processing algorithm of the oblique angle flaw detector thus constructed is shown in the flowchart of FIG. In this algorithm, first, the array probe is electronically scanned in the x direction of the device under test, and the array probe is mechanically scanned in the y direction of the device under test to scan the ultrasonic beam. The dimension is scanned (step 700-3). Thus, in this embodiment, the scanning of the probe only needs to be the uniaxial scanning in the y direction.
The 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 bevel flaw detector according to the present invention is applied to an apparatus for inspecting a shroud welding line in a reactor pressure vessel.

In the figure, the inspection device 63 is attached to the flange 60 on the upper part of the shroud 61, and is inspected by moving in the circumferential direction and the axial direction under the control of the scanning control device 71. The tip of this inspection device 63 has a link structure, and it is possible to install the probe 14 in the vicinity of 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 apparatus 72, where various signal processing including the above-described processing is performed and the inspection result is displayed as an image in the form of a sectional view and a plan view.

[Sixth Embodiment] FIG. 23 is a schematic view showing a sixth embodiment in which the ultrasonic flaw detector of the present invention is applied to an inspection device for a CRD stub tube welded portion under a reactor pressure vessel. For inspection, ultrasonic waves are transmitted from the probe 14 installed in the CRD housing 83, and C is transmitted through the gap 35.
Welded portion 8 of RD stub tube 81 and pressure vessel lower 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 processing including the above-described processing is performed to display the inspection result as an image in the form of a sectional view and a plan view. It should be noted that this gap 35 corresponds to the gap 35 in the above-described third embodiment, and it can be seen that the third embodiment is effective for the inspection of such an apparatus.

[0057]

As described above, according to the present invention,
By performing the waveform addition processing of the received signals that set the time shift amount according to the relative position of the probe and the defect,
The intensity of the reflected wave from the object is increased, random noise and noise at a specific position are reduced, and the SN of the detection signal is relatively increased.
Since the ratio can be improved, 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 the member on the back side arranged through the gap.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a bevel flaw detector according to a first embodiment of the present invention.

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

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

FIG. 4 is a diagram showing a positional relationship between crest values used in the oblique angle flaw detection method according to the present invention.

FIG. 5 is a diagram showing a relationship between a probe shift amount and a probe position when waveforms are added in the oblique angle flaw detection method according to the present invention.

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

FIG. 7 is a flowchart showing a processing procedure in 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 bevel flaw detector according to the first embodiment.

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

FIG. 11 is a view showing a flaw detection state of the oblique angle flaw detection device according to the second embodiment.

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

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

FIG. 14 is a diagram for explaining a state of transmission of ultrasonic waves in the third embodiment.

FIG. 15 is a block diagram showing a configuration of a bevel flaw detector according to a third embodiment.

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

FIG. 17 is a diagram showing a state during flaw detection of the bevel flaw detector according to the third embodiment.

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

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

FIG. 20 is a block diagram showing a configuration of a bevel flaw detector according to a fourth embodiment.

FIG. 21 is a flowchart showing 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 is a perspective view of the angle beam inspection apparatus of the present invention used in a nuclear power plant C;
It is a figure which shows the example applied to the RD stub tube inspection device.

[Explanation 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 wave 15a Burst ultrasonic wave 15b Reflected wave 15u Ultrasonic beam 16 High voltage switch 16a Switch control unit 16b Position Detection unit 17 Delay element 17a Delay control unit 20 Inspected object 20a, 20b Flat plate test body 21 Defect part 22 Welded part 31 Hours gate 35 Gap 40 Electrical noise 41 Position noise 42 Defect echo 46 Gap echo intensity 71 Scan control device 72 Ultrasonic wave Inspection equipment

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Bunshin Takahashi 7-2-1, Omika-cho, Hitachi City, Ibaraki Pref.

Claims (10)

[Claims] 1. An ultrasonic probe is scanned on an object to be inspected, ultrasonic waves are 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 reflection signal from the object is received. In the oblique angle flaw detection method for detecting the presence and the position of the target object from the reflected wave data of the target object and the position signal of the ultrasonic probe obtained according to the relative position of the ultrasonic probe and the target object. Setting the delay time and adding the waveforms of the received signals with the set delay time deviations, the reflected wave intensity is increased by the addition of the waveforms of the received signals to perform the detection. A characteristic angle beam testing method. 2. The step of adding the waveforms obtains a virtual defect position in the x direction from the peak value of the signal obtained by adding the received signals in the y direction at each position to be measured, and using this virtual defect position as a reference, x The oblique angle flaw detection method according to claim 1, further comprising a process of setting a time shift amount according to a relative position in the direction and adding the waveforms of the received signals. 3. The time shift amount (Δt) is a propagation distance from the virtual defect position L ₀ , a propagation distance from a position shifted from the virtual defect position by an arbitrary distance L _i ,
The oblique angle flaw detection method according to claim 2, wherein when the sound velocity is C, the amount is Δt = 2 (L _i −L ₀ ) / C. 4. The step of adding the waveforms of the received signals, wherein the area to which the waveforms are added is set based on the beam divergence of the ultrasonic probe that has been measured in advance. Angled flaw detection method described. 5. The oblique flaw detection method according to claim 1, wherein the transmission wave to be transmitted to the ultrasonic probe is a burst wave, and the subject is arranged via a gap. 6. An ultrasonic probe is scanned on an object to be inspected, ultrasonic waves are 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 reflection signal from the object is received. In the bevel flaw detector that detects the presence and position of the target object from the reflected wave data of the target object and the position signal of the ultrasonic probe obtained according to the relative position of the ultrasonic probe and the target object. An oblique flaw detection apparatus comprising: a calculation unit that sets a delay time; and a waveform addition unit that performs a waveform addition process of received signals. 7. The apparatus further comprises means for storing a waveform addition area set from the beam divergence of the ultrasonic probe measured in advance, wherein the waveform addition means executes addition processing in the waveform addition area. The bevel flaw detector according to claim 6. 8. A transmission means for transmitting a burst wave to the ultrasonic probe, and a transmission control means for controlling the frequency of the burst wave according to the gap length in the body to be inspected. The bevel flaw detector according to claim 6 or 7. 9. The ultrasonic probe comprises 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. 9. The oblique angle flaw detection apparatus according to claim 6, further comprising: a delay control unit that sets the position of the probe and a switching unit that switches the operation of each probe. 10. The supersonic beam flaw detector according to claim 6 is included as defect detection means for a welded portion of a shroud or a CRD stub tube of a nuclear power plant. Sound wave inspection device.