JP2008249441A - Ultrasonic flaw detection method and ultrasonic flaw detection program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detection method capable of discriminating accurately between a reflection echo caused by a shape, into penetration bead and reflected echoes caused by defects, while adopting a flaw detection method for recording all echo waveforms. <P>SOLUTION: This method for inspecting a defect in a weld zone of an inspection object by using ultrasonic waves has an inspection step for providing a detection means for detecting a reflection echo, by allowing the ultrasonic wave to enter an inspection object part, and detecting the reflection echo by scanning in an inspection object range by the detection means; a cell formation step for forming a cell, wherein a defect on a position corresponding to an incident spot of the ultrasonic waves is projected onto a plane, based on the reflected echo detected in the inspection step; and a defect specification step for specifying a defect position on the plane by using a synthetic aperture method, based on the reflected echo detected in the inspection step. The influence due to echo caused by the shape of the weld zone is removed, by reflecting the defect position acquired in the defect specification step to the cell formed in the cell formation step. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for inspecting a defect in a welded portion of an object to be inspected using ultrasonic waves, and a program therefor.

  Conventionally, regarding ultrasonic flaw detection technology, “the accuracy of defect inspection is increased and the data processing time is shortened. As a technique for the purpose of the above, “a cell that projects a discontinuous portion at a position corresponding to a reflected echo from the inspection object 3 onto the same surface, and creates a range where the discontinuous portion continues on the same surface as a cell. Creation means 21, defect existence area setting means 22 for setting a defect existence area where it is determined that a defect exists from the created cell distribution, and whether or not a reflected echo corresponding to a discontinuous portion in the defect existence area is a defect echo A defect echo identification means 23 for identifying the defect existence area, a display means 24 for displaying the defect existence area and the defect echo, a defect existence area setting means 22 and a correction means 25 for correcting the output of the defect echo identification means 23. Is proposed (Patent Document 1).

  In addition, “in ultrasonic flaw detection using the aperture synthesis technique, inspection accuracy decreases due to vertical movement and tilt movement during scanning of the probe. ”Measures the disturbance information such as the vertical movement of the probe for ultrasonic data including the effects of time differences caused by the vertical movement and tilting movement of the probe. Is used to correct the ultrasonic data, thereby eliminating the influence of the disturbance and improving the aperture synthetic ultrasonic flaw detection accuracy. Is proposed (Patent Document 2).

  Moreover, the flaw detection method of the welding part using an ultrasonic wave is standardized (nonpatent literature 1).

JP 10-82766 A (summary) JP 2006-105657 A (summary) JGA finger 210-04, "Automatic ultrasonic flaw detection method for gas pipe circumference welds", Japan Gas Association

When inspecting the presence or absence of defects in the welded part of the inspection object using ultrasound, it is possible to distinguish between echoes reflected from the back bead generated on the opposite surface of the welded part and echoes reflected from the defective part. There may not be.
In the technique described in Patent Document 1, all reflected echo waveforms are recorded without distinguishing the reflected echo from the back bead and the reflected echo from the defective part, and the cell is created. Therefore, there is a possibility that the defect detection accuracy may be lowered, and there is a problem that the work cost is very high.
On the other hand, the aperture synthesis method described in Patent Document 2 is a technique that is often used in ultrasonic flaw detection, and can accurately identify defects, but the method alone requires that all echo waveforms be recorded. There is a problem that it is not possible to correspond to the standard to be.

  The present invention has been made in order to solve the above-described problems. While adopting a flaw detection method for recording all echo waveforms, the present invention is caused by reflection echoes caused by a shape like a back bead and defects. It is an object of the present invention to obtain an ultrasonic flaw detection method capable of accurately distinguishing reflected echoes.

  An ultrasonic flaw detection method according to the present invention is a method for inspecting a defect in a welded portion of an object to be inspected using an ultrasonic wave, and includes a detecting means for detecting the reflected echo by injecting an ultrasonic wave into an inspection target portion. A detection step of detecting a reflected echo by scanning the detection means in a range to be inspected, and a defect at a position corresponding to an ultrasonic incident location is projected on a plane based on the reflected echo detected in the detection step A cell creating step for creating a cell, and a defect identifying step for identifying a defect position on the plane by an aperture synthesis method based on the reflected echo detected in the detecting step, and obtained in the defect identifying step By reflecting the defect position in the cell created in the cell creation step, the influence of echo caused by the shape of the welded portion is removed.

  In the ultrasonic flaw detection method according to the present invention, the cell creation step and the defect identification step are executed in parallel.

  An ultrasonic flaw detection program according to the present invention causes a computer to execute the above method.

  According to the ultrasonic flaw detection method according to the present invention, while adopting the flaw detection method that records the entire echo waveform, the reflected echo caused by the shape like the back bead and the reflected echo caused by the defect are accurately obtained. Can be distinguished.

Embodiment 1 FIG.
FIG. 1 shows a state in which an ultrasonic probe 1 according to Embodiment 1 of the present invention is inspecting a defect in a welded portion of a material to be inspected.
In FIG. 1, reference numeral 2 denotes an ultrasonic wave that the ultrasonic probe 1 enters the inspection target range, 3 denotes a weld bead, and 4 denotes a back bead.
The weld bead 3 is a weld metal (metal melted and solidified during welding) made by welding.
The back bead 4 is a bead that can be formed on the opposite side (back surface) to the welded portion in one-side welding. In FIG. 1, it is formed on the opposite surface of the weld bead 3.
The ultrasonic probe 1 enters the ultrasonic wave 2 toward the welded portion while scanning the weld bead 3 in a zigzag manner, and detects the reflection echo to detect defects existing in the inspection target material. Detect.

Note that the ultrasonic probe 1 appropriately includes means for making ultrasonic waves incident on the inspection target range, detection means for the reflected echo, and storage means for recording the reflected echo waveform data.
The ultrasonic probe 1 includes a control unit that controls the operation of the ultrasonic probe 1. The control unit can be configured by an arithmetic device such as a CPU or a microcomputer. In addition to the operation control, the control unit performs operations such as data processing by an aperture synthesis method described later.

FIG. 2 shows a state in which a defect detected based on the detected reflected echo is three-dimensionally drawn.
The ultrasonic probe 1 detects reflected echoes while moving along the y-axis in FIG. 2, and repeatedly executes them at a predetermined pitch in the x-axis direction so that it is within the inspection target range. Record the total reflection echo waveform.
When the waveform recording of the total reflection echo is finished, a drawing cell in which the internal defect is projected on the yz plane is created based on the data, as shown in FIG. By visually confirming the drawing cell, the position and size of the defect 5 existing inside can be specified.

FIG. 3 illustrates how a defect that does not exist is erroneously detected due to reflection of ultrasonic waves by the backside bead 4.
Hereinafter, the process of erroneous detection will be briefly described step by step.

(1) The ultrasonic probe 1 enters the ultrasonic wave toward the direction of the inspection object. If the reflected echo at this time matches a predetermined condition, it can be determined that a defect exists in the same direction.

(2) However, since the ultrasonic beam is a wave, it spreads within a certain range. Therefore, the ultrasonic beam reaches a certain range around the detection target direction.
When the back bead 4 is present in the spread range, the echo reflected by the back bead 4 is detected by the ultrasonic probe 1 as an echo reflected in the detection target direction.

(3) Then, the ultrasonic probe 1 may erroneously detect that there is a defect in the detection target direction.
Whether or not to make a false detection depends on the shape of the back bead 4 and the like, and therefore a false detection may not necessarily occur, but there is a possibility that the detection accuracy is lowered.

In the technique described in Patent Document 1, scanning is performed with the possibility of such erroneous detection already folded.
Therefore, after performing flaw detection, (1) Fold the possibility that more defects will be detected than the actual one and design it to the safe side. (2) Determine the presence or absence of false detection by visual confirmation of the drawing cell It is necessary to take measures such as

Thus, it is clear that the possibility of erroneous detection of defects is not preferable from the viewpoint of not only accuracy but also work cost.
Therefore, in the present invention, the aperture synthesis method is applied to the reflected echo detected during the scanning in the y-axis direction in FIG. 2, the position of the reflected echo is specified, the influence of the back bead 4 is removed, and an accurate defect is obtained. Propose to detect.

FIG. 4 shows how the ultrasonic probe 1 performs flaw detection.
The ultrasound probe 1 applies the aperture synthesis method to the reflected echo detected when scanning in the y-axis direction.
Conventionally, the reflected echo waveform was simply recorded, but by applying the aperture synthesis method, the same effect as that obtained by increasing the antenna diameter can be exhibited. Problems caused by the spread of the ultrasonic beam can be reduced, and the accuracy of the position of the defect is improved.

FIG. 5 shows a comparison between a defect detection result obtained by detecting and recording all reflected echoes and a defect detection result obtained by the aperture synthesis method.
As described with reference to FIG. 3, simply detecting and recording the reflected echo may cause erroneous detection in a place where there is no defect. Therefore, as shown in FIG. 5A, the defect detection range tends to be wider.
On the other hand, when the aperture synthesis method is applied, the accuracy of the defect position is increased, so that the defect detection range is limited to a narrower range as shown in FIG.

5 (a) and 5 (b) are drawing cells created based on the same reflection echo, although the processing procedure after detection of the reflection echo is different, a true defect is obtained by comparing the two. The position and its size can be specified with high accuracy.
As a comparison method, visual confirmation may be used, or drawing cells may be divided at a predetermined pitch and data may be compared for each divided cell.

FIG. 6 shows a state in which the specified defect positions are connected in the x-axis direction.
With the method described with reference to FIG. 5, it is possible to specify a defect position or the like on the yz plane by the aperture synthesis method. Next, by connecting data in the x-axis direction, a defect position or the like in the three-dimensional space can be specified and drawn as three-dimensional cell data.

  Although it is conceivable to detect defects using only the aperture synthesis method from the beginning, in the following circumstances, the final detection result cannot be obtained using only the aperture synthesis method. It is necessary to use the method described in the first embodiment.

In the standard of ultrasonic flaw detection, it may be required to record the total reflection echo waveform and present the result. In this case, it is inevitable to record the total reflection echo waveform, and the aperture synthesis method alone cannot be used alone.
Therefore, in this case, the aperture synthesis method is applied in combination with the recording of the total reflection echo waveform, and the standard compliance and accurate flaw detection are realized at the same time.

As described above, according to the first embodiment, by applying the aperture synthesis method to the reflected echo obtained during the scanning in the y-axis direction, a defect is erroneously detected by the echo reflected by the back bead 4. This reduces the accuracy of defect detection.
In addition, since the aperture synthesis method is applied under the premise of recording all echo waveforms, even if recording of all echo waveforms is required from the viewpoint of standards compliance, etc., high-accuracy flaw detection should be performed while complying with this Can do.

Embodiment 2. FIG.
In the first embodiment, the technique of applying the aperture synthesis method to the recording results of all echo waveforms and reducing the erroneous detection of defects has been described mainly from the viewpoint of detection accuracy.
In the second embodiment of the present invention, a technique for further improving the flaw detection execution speed will be described.

  In the second embodiment, the ultrasound probe 1 applies the aperture synthesis method in parallel with the recording of the reflected echo waveform. By performing the parallel processing, the flaw detection processing can be performed simultaneously with the waveform recording, so that a quick flaw detection is possible.

  FIG. 7 is an operation flow of the ultrasonic probe 1 according to the second embodiment. Hereinafter, each step will be described.

(S701)
The ultrasonic probe 1 performs scanning along the weld bead 3 (in the x-axis direction).
The scanning pitch is set to 1 mm or 2 mm, for example, and the subsequent steps S702 to S710 are repeated until the entire range to be inspected is scanned.
(S702)
The ultrasonic probe 1 moves at a predetermined pitch in the x-axis direction (only for the first time, the ultrasonic probe 1 is set at the scanning start position).

(S703)
The ultrasonic probe 1 performs scanning in the y-axis direction.
The scanning pitch is, for example, 1 mm or 2 mm, and the subsequent steps S704 to S705 are repeated until the entire range to be inspected is scanned.
(S704)
The ultrasonic probe 1 moves at a predetermined pitch in the y-axis direction.
(S705)
The ultrasonic probe 1 enters an ultrasonic wave toward the inspection target position, detects a reflected echo, and records its waveform data.

(S706)
The ultrasound probe 1 executes the processes of the next steps S707 and S708 in parallel.
(S707)
The ultrasound probe 1 generates cell data reflecting the defect detection result as described with reference to FIG. 2 for the yz plane based on the reflected echo waveform data recorded in step S705 (during scanning in the y-axis direction). .
(S708)
The ultrasound probe 1 applies the aperture synthesis method based on the reflected echo waveform data recorded in step S705 (during scanning in the y-axis direction), and identifies the defect position and the like.

(S709)
The ultrasound probe 1 compares the cell data based on the recording of all echo waveforms generated in step S707 with the defect position specified by the aperture synthesis method in step S708, and determines the defect position on the cell data.
(S710)
The ultrasonic probe 1 records the determination result of the defect position on the cell data.

As described above, according to the second embodiment, cell data as shown in FIG. 2 is generated without impairing the recording result of all echo waveforms, and the defect position specified by the aperture synthesis method is reflected on the cell data. By doing so, the influence of the reflected echo by the backside bead 4 can be removed.
In addition, since the processes in steps S707 and S708 are executed in parallel, it is possible to quickly identify defects.

Embodiment 3 FIG.
In the first and second embodiments, it has been described that the ultrasound probe 1 includes a control unit that performs data processing calculation and a storage unit for data recording. These configurations are not necessarily configured integrally with the ultrasound probe 1, and an external device such as a computer may have the same function.

  In the above embodiment, the example of removing the influence of the shape echo caused by the back bead 4 has been described. However, the present invention is not limited to this, and any other arbitrary method can be used by using the ultrasonic flaw detection method according to the present invention. The effect of the shape echo can be eliminated.

The ultrasonic probe 1 which concerns on Embodiment 1 shows a mode that the defect in the welding part of a test object material is test | inspected. It shows a state in which a defect detected based on the detected reflection echo is three-dimensionally drawn. A state in which a defect that does not exist is erroneously detected due to reflection of ultrasonic waves by the back bead 4 will be described. The state in which the ultrasonic probe 1 performs flaw detection is shown. This shows the comparison between the defect detection result by detecting and recording all reflected echoes and the defect detection result by the aperture synthesis method. It shows a state in which the identified defect positions are connected in the x-axis direction. 6 is an operation flow of the ultrasonic probe 1 according to the second embodiment.

Explanation of symbols

  1 Ultrasonic probe, 2 ultrasonic waves, 3 weld beads, 4 back wave beads, 5 defects.

Claims (3)

A method for inspecting a defect in a welded portion of an inspection object using ultrasonic waves,
Provide a detection means for detecting the reflected echo by injecting the ultrasonic wave into the inspection target part,
A detection step of detecting a reflected echo by scanning the detection means in an inspection object range;
Based on the reflected echo detected in the detection step, a cell creation step for creating a cell in which a defect at a position corresponding to an ultrasonic incident location is projected on a plane;
Based on the reflected echo detected in the detection step, a defect specifying step for specifying a defect position on the plane by an aperture synthesis method;
Have
By reflecting the defect position obtained in the defect identification step in the cell created in the cell creation step,
An ultrasonic flaw detection method characterized in that, in the cell, an influence of an echo caused by the shape of the welded portion is removed. The ultrasonic flaw detection method according to claim 1, wherein the cell creation step and the defect identification step are executed in parallel.   An ultrasonic flaw detection program that causes a computer to execute the ultrasonic flaw detection method according to claim 1.

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