JPH10253599A - Ultrasonic flaw detection method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detection method and device capable of accurately detecting the position of a defect in the inspection of welded parts of a complex structure. SOLUTION: In the ultrasonic flaw detection method, an ultrasonic probe 1 is scanned on a body 27 to be inspected, ultrasonic waves are transmitted into the body 27 to be inspected, at the same time, ultrasonic waves that are reflected from a reflection body 20 are received, and the presence or absence of the reflection body 20 and the position are detected from a received reflection signal and the position signal of the ultrasonic probe 1. In this case, the ultrasonic waves are received and transmitted in a plurality of directions A and B, the position of the reflection body 20 in each direction is calculated from a reflection signal that is received in each direction and the position signal of the ultrasonic probe 1 in each direction, at the same time, a reflector display image for displaying the reflector 20 on the body 27 to be inspected for each direction is calculated and created, and the logic product of the above reflector display image that is created for each direction is calculated to obtain a desired reflector display image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detection method and apparatus, and more particularly, to an ultrasonic flaw detection method and apparatus for calculating the position of a reflector from the propagation time of a reflected signal propagating in a test object.

[0002]

2. Description of the Related Art An example of a conventional ultrasonic inspection method for a welded portion will be described with reference to FIGS. FIG. 6 is a view for explaining a defect inspection at a welded portion between the CRD stub tube and the pressure vessel lower mirror at the lower part of the nuclear pressure vessel, and FIG. 7 (a) is a transmission wave and a defect reflection at the position x0 of the ultrasonic probe. FIG. 7B is a diagram illustrating a display screen of a wave, FIG. 7B is a diagram illustrating a display screen of a transmission wave and a defect reflection wave at the position x1 of the ultrasonic probe, and FIG. 8 is a defect image and a ghost image obtained as a result of the inspection; It is a figure which shows the display screen of.

In FIG. 6, 1 is an ultrasonic probe, 20 is a CRD stub tube, 21 is a lower mirror of a pressure vessel, 22 is a welded portion, 23 is a defect, and 24 is a scanning position x of the ultrasonic probe 1.
0 is the propagation path of the ultrasonic beam at 0, 25 is the propagation path of the ultrasonic beam at the scanning position x1 of the ultrasonic probe 1,
26 is the inner surface of the CRD stub tube, 27 is the outer surface of the CRD stub tube, X and Y are the coordinate axes, x0 and x1 are the scanning positions of the ultrasonic probe 1, xd and yd are the coordinate positions of the defect, and θ is This is the refraction angle of the ultrasonic beam transmitted and received from the ultrasonic probe 1 to the inner surface of the CRD stub tube 20.

In FIGS. 7 and 8, reference numeral 30 denotes a time gate for gating a time zone in which a defect reflected wave propagates, 31 denotes a transmission wave transmitted from the ultrasonic probe 1, and 32a denotes a frequency of the ultrasonic probe 1. The defect reflected wave received at the scanning position x0, 3
2b is a pseudo reflection wave received at the scanning position x1 of the ultrasonic probe 1, 33a is a defect image corresponding to the defect reflection wave 32a, 33b is a ghost image corresponding to the pseudo reflection wave 32b,
td is the propagation time of the ultrasonic beam required for transmission and reception in the ultrasonic probe 1.

According to this ultrasonic flaw detection method, when an ultrasonic beam having a refraction angle θ is transmitted and received from the ultrasonic probe 1, a defect reflected wave is received from the defect 23 through the propagation path 24 at the scanning position x0. .

As a result, as shown in FIG. 7A, the defect reflected wave 3
2a is detected.

Here, assuming that the sound speed of the ultrasonic beam in the body to be inspected is v, and the scanning position of the ultrasonic probe 1 is x, y,
The coordinate positions xd and yd of the defect can be expressed by the following equation.

Xd = x + v · (td / 2) · cos θ yd = y + v · (td / 2) · sin θ (1) As shown in this equation, the coordinate position x,
When y, sound velocity v, propagation time td, and refraction angle θ can be detected,
The coordinate positions xd and yd of the defect can be obtained.

[0009]

In the above conventional ultrasonic flaw detection method, as shown in FIG.
Also at the scanning position x1 other than the above, pseudo reflected waves from other than the defect 23 are received through the propagation path 25 due to reflection from the welding boundary and the like. As a result, as shown in FIG. 7B, the pseudo reflected wave 32b is detected at the scanning position x1 with respect to the transmission wave 31. Therefore, when each inspection result at the scanning position x0 and the scanning position x1 is arithmetically processed and the section of the inspection object is displayed, as shown in FIG.
The welded portion 22 has a defect image 33 corresponding to the defect reflected wave 32a.
The ghost image 33b corresponding to a and the pseudo reflected wave 32b is displayed as an image.

As described above, in the conventional ultrasonic flaw detection method,
When inspecting a welded portion of a complicated structure, a pseudo reflected wave due to the shape of the inspection object is detected, and therefore, there has been a problem that the position of a true defect cannot be accurately detected.

In view of the above problems, an object of the present invention is to provide an ultrasonic flaw detection method and apparatus capable of accurately detecting the position of a defect in a weld inspection of a complicated structure. Things.

[0012]

In order to achieve the above object, the present invention employs the following means.

An ultrasonic probe is scanned on an object to be inspected, an ultrasonic wave is transmitted into the object to be inspected, and an ultrasonic wave reflected from the reflector is received. In the ultrasonic flaw detection method for detecting the presence or absence and position of a reflector from a position signal of a child, the ultrasonic wave is transmitted and received in a plurality of directions, a reflected signal received in each direction, and the ultrasonic detection method in each direction. From the position signal of the tentacle,
The position of the reflector in each direction is calculated, and a reflector display image for displaying the reflector on the inspected object is calculated and created for each direction, and the reflector created for each direction is created. It is characterized in that a logical product of the display images is calculated to obtain a desired reflector display image.

An ultrasonic probe for scanning the object to be inspected, transmitting ultrasonic waves into the object to be inspected, and receiving ultrasonic waves reflected from the reflector; Scanning control means for outputting a position signal of the ultrasonic probe means, flaw detection data obtained from the ultrasonic probe means and position data obtained from the scan control means, And an arithmetic processing unit for detecting presence / absence and position, wherein the ultrasonic probe unit transmits and receives the ultrasonic wave in a plurality of directions, and the arithmetic processing unit obtains the ultrasonic wave in each direction. Based on the obtained flaw detection data and the position data obtained in each direction, the presence / absence and position of the reflector in each direction are calculated, and the reflection on the object to be inspected is performed in each direction. A reflector display image for displaying a body is calculated and created, and further, a logical product of the reflector display images created for the respective directions is calculated, and the calculated reflector display image is displayed. It is characterized by the following.

The ultrasonic probe includes a plurality of transmitting and receiving units for transmitting and receiving the ultrasonic waves in a plurality of directions;
A switching unit for switching between the plurality of transmission / reception units for transmission / reception in each of the plurality of directions is provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a view for explaining a defect inspection at a welded portion between a CRD stub tube and a lower part of a pressure vessel lower part of a nuclear pressure vessel according to the present embodiment, and FIG. FIG. 3 is a diagram illustrating a process of obtaining a defect image.

In these figures, FIG.
8 are denoted by the same reference numerals, and description thereof will be omitted.

[0018] In these figures, 28 is the propagation path of the ultrasonic beam put the scanning position x _B of the ultrasonic probe 1, 33
Each b1,33b2 ghost images, x _A, x _B each respective scan position of the ultrasound probe 1, θ _A, θ _B, respectively ultrasonic probe 1 scan position x _A and scan position x _B Is the refraction angle of the ultrasonic beam transmitted and received from the ultrasonic probe 1 to the inner surface of the CRD stub tube 20. A and B represent the scanning directions on the inner surface of the CRD stub tube of the ultrasonic probe 1, respectively.

The ultrasonic flaw detection method according to the present embodiment also shows a method for inspecting a defect 23 in a welded portion 22 of a complicated structure. First, the ultrasonic probe 1 is scanned in the A direction to thereby wave probe 1 and the ultrasonic bi refraction angle theta _a between the object to be inspected - and receive beam, as described in the prior art from the test subject, the reflected wave including a pseudo reflected wave other than the defect reflected wave To receive.

Here, at the scanning position x _A , the reflected wave from the defect 23 is received by the propagation path 24. From the sound velocity v, the propagation time td, the scanning position x _A , and the refraction angle θ _{A of} this defect reflected wave, the defect position x is calculated in the same manner as in Expression (1).
_A d, is y _Ad is required. _{x A d = x A + v} · (td / 2) · cosθ A y A d = y A + v · (td / 2) · sinθ A similarly pseudo defect position of the pseudo reflected wave x _A d ', y
_A d 'is also required.

On the other hand, similarly from the direction B, the ultrasonic probe 1
Is scanned, and the refraction angle θ _B between the ultrasonic probe 1 and the test object is
Transmits and receives an ultrasonic beam, and receives a reflected wave including a pseudo reflected wave other than the defective reflected wave.

[0022] Here, in the scanning position x _B, the propagation path 28, the defect reflected wave is received from the defect 23. Assuming that the sound velocity v, the propagation time td, the scanning position x _B , and the refraction angle θ _B of the defect reflected wave, the defect position x _B is calculated by the following equation.
d, it is possible to determine the y _B d. x _B d = x _B over v · (td / 2) · cosθ B y B d = y B + v · (td / 2) · sinθ B in the same manner, the pseudo defect location x _B d pseudo reflected waves', y
_B d ′ is also required.

Next, each defect position and each pseudo defect position obtained as described above are calculated for each scanning direction to obtain a defect image and a pseudo defect image. FIG. 2A shows a defect image 33a obtained when the ultrasonic probe 1 is scanned from the A direction.
And a ghost image 33b1 from a reflector other than a defect is displayed. On the other hand, FIG. 2B shows a defect image 33a obtained when the ultrasonic probe 1 is scanned from the B direction and a ghost image 33b2 from a reflector other than the defect.

Next, only the true defect image is obtained by performing an AND operation on the obtained defect image and the pseudo defect image. That is, the defect image 33a and the ghost image 33b1 shown in FIG. 2A and the defect image 33 shown in FIG.
a and AND operation of the image with the ghost image 33b2 is performed. As a result, as shown in FIG.
Only can be displayed.

Next, the processing procedure of the ultrasonic flaw detection method according to this embodiment will be described with reference to the flowchart shown in FIG.

[0026] First, in step 100, and ultrasonic flaw detection at an oblique angle to the object to be inspected from the direction A, the refraction angle theta _A of the reflected wave in the time gate, the propagation time td, record flaw data such as the scanning position x _A I do.

[0027] Next, in step 101, the A direction to be inspected from the opposite direction B and oblique ultrasonic flaw detection, recording the flaw detection data such as the scanning position x _B and propagation time td of the reflected waves in the time gate .

Next, in step 102, a sectional image as shown in FIG. 2A is visualized using the flaw detection data obtained from the direction A. Further, in Step 103, using the flaw detection data obtained from the B direction,
A cross-sectional image is visualized as shown in FIG.

Next, in step 104, the logical product of the cross-sectional image obtained from the direction A and the cross-sectional image obtained from the direction B is calculated, and as shown in FIG. A cross-sectional image in which only the image is extracted is obtained.

Next, an ultrasonic flaw detector according to this embodiment will be described with reference to FIG.

FIG. 4 is a block diagram showing the overall configuration of the ultrasonic flaw detector.

In the figure, 2 is a transmitter for transmitting an ultrasonic pulse signal to the ultrasonic probe 1, 3 is a receiver for receiving a reflected signal from the ultrasonic probe 1 and performing amplification and detection processing, 4
Is a gate circuit for extracting only a specific echo from the received signal, and 5 is a scan for scanning the ultrasonic probe 1 by scanning a scanning mechanism (not shown) and transmitting a scan position signal to the arithmetic processing unit. A control unit, 6 is an arithmetic processing unit composed of a computer or the like, 7A and 7B are interfaces, 8
Is a data bus, 9 is a memory for storing various input data, various data obtained as a result of operation, or various processing programs, and 10 is an arithmetic processing in accordance with processing programs such as defect position calculation and image processing. Calculation unit to perform,
Reference numeral 11 denotes a display unit that displays calculation results of various cross-sectional images and the like.

As shown in FIG.
The ultrasonic probe 1 can be scanned from the direction B and the direction B, and the ultrasonic pulse signal transmitted from the transmitter 2 is transmitted from the ultrasonic probe 1 to the object to be inspected as an ultrasonic beam. The reflected wave is received by the ultrasonic probe 1 again. The received signal is amplified and detected by the receiver 3.
The specific echo is extracted by the gate circuit 4 and input to the arithmetic processing unit 6 via the interface 7A.
On the other hand, the scanning control unit 5 outputs a scanning signal for scanning the ultrasonic probe 1 and inputs a position signal of the ultrasonic probe 1 to the arithmetic processing device 6 via the interface 7B. The arithmetic processing unit 6 receives various kinds of flaw detection data,
The position data is calculated by the calculation unit 10 to calculate the defect position,
A logical product operation of the cross-sectional images in each direction is performed, and a cross-sectional image displaying only a true defect image obtained as a result of the calculation is obtained on the display unit 11.

Next, an ultrasonic flaw detector according to a second embodiment will be described with reference to FIG.

FIG. 5 is a block diagram showing the overall configuration of the ultrasonic flaw detector according to this embodiment.

In the figure, 13 is an ultrasonic probe having two transducers, 13a and 13b are transducers for transmitting and receiving oblique ultrasonic beams in the A direction, and oblique ultrasonic beams in the B direction. A transducer for transmitting and receiving the system, 14 is a transducer 13a,
13b.

The same parts as those in the first embodiment shown in FIG.

In the present embodiment, the ultrasonic probe 13 is composed of a plurality of transducers 1 having different directions of ultrasonic beams transmitted and received.
When the ultrasonic inspection is performed in the A direction, the changeover switch 14 is switched to the vibrator 13a, and the oblique inspection is performed from the A direction. On the other hand, when performing ultrasonic flaw detection in the B direction, the changeover switch 14 is switched to the transducer 13b, and oblique flaw detection is performed from the B direction.

The operation of this embodiment is not substantially different from that of the first embodiment shown in FIG.

As described above, according to the present embodiment, the oblique flaw detection from both directions can be performed by one reciprocal scanning of the ultrasonic flaw detection 3, so that the inspection time can be greatly reduced.

[0041]

As described above, according to the present invention, only a true defect image can be obtained by performing ultrasonic inspection from a plurality of directions and performing a logical product operation of the reflector display images created for each direction. Can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a defect inspection at a welded portion between a CRD stub tube and a lower pressure vessel mirror according to a first embodiment.

FIG. 2 is an explanatory diagram for obtaining a true defect image by performing image processing on inspection data according to the first embodiment;

FIG. 3 is a flowchart showing a processing procedure of the ultrasonic flaw detection method according to the first embodiment.

FIG. 4 is a block diagram showing the overall configuration of the ultrasonic flaw detector according to the first embodiment.

FIG. 5 is a block diagram showing an overall configuration of an ultrasonic flaw detector according to a second embodiment.

FIG. 6 is an explanatory diagram of a defect inspection at a welded portion between a CRD stub tube and a pressure vessel lower mirror according to the related art.

FIG. 7 is a diagram showing a state of generation of a transmission wave and a defective reflected wave according to the related art.

FIG. 8 is a diagram showing a display screen of a defect image and a ghost image according to the related art.

[Explanation of symbols]

 Reference Signs List 1,13 Ultrasonic probe 5 Scan control unit 6 Arithmetic processing unit 10 Arithmetic unit 11 Display unit 14 Changeover switch 20 CRD stub tube 21 Mirror under pressure vessel 22 Welding part 23 Reflector 24,28 Ultrasonic beam propagation path 33a Defect Image 33b1, 33b2 Ghost defect image

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Nobuo Awamura 6-9 Takaracho, Kure-shi, Hiroshima Babcock Hitachi Kure Factory

Claims (3)

[Claims] An ultrasonic probe is scanned on an object to be inspected, an ultrasonic wave is transmitted into the object to be inspected, and an ultrasonic wave reflected from a reflector is received. An ultrasonic flaw detection method for detecting presence / absence and position of a reflector from a position signal of a probe, wherein the ultrasonic wave is transmitted and received in a plurality of directions, a reflected signal received in each direction, and the ultrasonic wave in each direction. From the position signal of the acoustic probe, the position of the reflector in each direction is calculated, and a reflector display image for displaying the reflector on the inspected object is calculated for each direction. Performing an AND operation on the reflector display image created in step (a) to obtain a desired reflector display image. 2. An ultrasonic probe for scanning an object to be inspected, transmitting ultrasonic waves into the object to be inspected and receiving ultrasonic waves reflected from a reflector, and scanning the ultrasonic probe. Scanning control means for outputting a position signal of the ultrasonic probe means, and a reflector based on flaw detection data obtained from the ultrasonic probe means and position data obtained from the scan control means. And an arithmetic processing means for detecting presence / absence and position.The ultrasonic flaw detecting means transmits and receives the ultrasonic wave in a plurality of directions, and the arithmetic processing means obtains the ultrasonic wave in each direction. Based on the obtained flaw detection data and the position data obtained in each direction,
The presence and absence of the reflector in each direction and the position are calculated, and a reflector display image for displaying the reflector on the inspected object is calculated for each direction, and further, the reflector display image is created for each direction. An ultrasonic flaw detector which performs a logical product operation of the reflector display image and displays the calculated reflector display image. 3. The ultrasonic probe according to claim 2, wherein the ultrasonic probe is configured to transmit and receive the ultrasonic waves in a plurality of directions, and to transmit and receive the ultrasonic waves in each of the plurality of directions. An ultrasonic flaw detector, wherein a switching unit for switching the unit is provided.