JP3454445B2 - Defect size measurement method for mobile flaw detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect size measuring method in a mobile flaw detector such as ultrasonic flaw detector.

[0002]

2. Description of the Related Art For example, as a method for measuring the size of a defect in ultrasonic flaw detection, which is used in a movable flaw detector or the like configured to be capable of self-propelled along an object to be inspected, there is the following method. Method based on echo intensity: This is a method of estimating the defect size from the echo intensity by utilizing the fact that the echo intensity and the defect size have a good correlation when the defect size is smaller than the width of the ultrasonic beam. Image-based method: An ultrasonic flaw detection sensor, that is, a probe is scanned to calculate the echo reflection source position at each position, and an image obtained by plotting the position (B scope display, C scope display, etc.) ) Is a method of estimating the defect size. Edge echo method: One of the measurement methods that uses the propagation time of ultrasonic waves. It is an echo at the tip of the defect, or "edge echo", and an echo at the corner between the defect and the material surface, or "corner echo". This is a method of estimating the defect size from the difference in the path length between the and. Other methods: a method based on the moving distance of the probe, another method using the propagation time, a method based on frequency analysis, and the like.

[0003]

When the same defect is measured by the above-mentioned method, the measured value of the defect size changes depending on the incident direction of the ultrasonic wave to the defect, and the measured defect size is It does not necessarily reflect the actual defect size.

For example, in FIG. 3, for artificially constructed welding defects A, B, and C, flaws are detected from various directions, and the echo intensity and the defect image height (height on the B scope display) are respectively detected. The measured values are plotted with the ordinate indicating the echo intensity and the abscissa indicating the height of the defect image. The circles, squares, and triangles correspond to welding defects A, B, and C, respectively.

From this figure, it can be seen that the measured value of the defect size greatly changes depending on the flaw detection direction, that is, the incident direction of ultrasonic waves to the defect, even for the same defect.

In the case where the defect has a linear shape, in principle, the defect size is most measured when the flaw detection direction is perpendicular to the longitudinal direction of the defect. If the shape is not a shape, especially if it is a natural defect, the shape is complicated, and therefore the optimum flaw detection direction is not always specified. This can be understood from the fact that the echo intensity and the flaw detection direction that maximizes the height of the defect image do not always coincide with each other in FIG. Therefore, the present invention aims to solve such a problem.

In order to solve the above-mentioned problems, the present invention is directed to a moving flaw detector in which a defect detection sensor is linearly moved, and a defect is detected by scanning a direction perpendicular to the moving direction as a defect detection direction. When a signal from a defect is detected in a certain moving direction, the defect size is estimated from the data group of the appropriate moving range in that direction, this is stored, and then the angle is appropriately changed from the previous moving direction. For each direction, the operation of estimating and storing the defect size in the range corresponding to the previous movement range is repeated until the signal from the defect is no longer detected, and the defect size estimated value group is stored, and the stored estimated value is stored. We propose a defect dimension measurement method in which the maximum value of the group is the measured value of the defect dimension.

Further, the present invention proposes that, in the above method, the defect detection sensor has a defect detection direction and a direction perpendicular to the defect detection direction as a scanning direction.

Further, according to the present invention, in the above structure, the defect detecting operation is a detecting operation in a plurality of different defect size measuring methods, and the defect size is derived for each of a plurality of different method in each defect detecting operation. It is proposed to extract the maximum value of the defect size for each method and use each as the measured value.

The present invention proposes that the defect detection sensor is an ultrasonic flaw detection sensor.

[0011]

By performing the defect detection operation from each direction and setting the maximum value as the measured value of the defect size, the underestimation of the defect size can be prevented.

If a plurality of defect size measuring methods are applied to the detection operation in each direction, the maximum value of the defect size can be obtained as a measured value for each measuring method, and the defect can be comprehensively judged.

[0013]

The present invention will be described below with reference to the drawings. FIG. 1 shows a defect detecting operation according to the present invention. Reference numeral 1 is a defect existing in an object to be inspected, and 2 is a defect detection sensor installed in a movable flaw detector. The defect detection sensor 2 is set according to the flaw detection method. In this embodiment, the flaw detection method is an ultrasonic flaw detection method, and thus the defect detection sensor 2 is an ultrasonic probe. The defect detection sensor 2 is supported by a movable flaw detector (not shown) so as to be movable in the vertical and horizontal directions and to be rotatable. In addition, the movable flaw detector has a defect detection sensor 2
This is a configuration capable of managing the coordinates and the moving direction on the flaw detection object.

In the above structure, the movable flaw detector is
As shown in FIG. 1, after the defect detection sensor 2 is moved in the vertical direction in the drawing, that is, in the A direction by a predetermined distance, it is moved in the horizontal direction in the drawing, that is, in the B direction that is perpendicular to the A direction, and defect detection is performed in this way. The sensor 2 is scanned in a zigzag pattern to detect defects. At this time, the defect detection direction in the defect detection sensor 2, that is, the direction of the center of the ultrasonic beam 3 in this case is the B direction.

When the echo from the defect 1 is observed in the defect detecting operation by the defect detecting sensor 2, the movable flaw detector detects the defect detecting sensor 2 in the direction perpendicular to the defect detecting direction, as described above. While moving in the A direction, scanning is performed in a zigzag manner to perform a defect detecting operation in a moving range as appropriate. This movement range can be, for example, a preset movement range or a range from a position where a defect is detected to a position where a defect is no longer detected. In this way, the mobile flaw detector estimates the defect size from the ultrasonic echo data group in the moving range in the A direction, for example, by each of the above-mentioned methods (1) to (5) and stores it in the storage means. For example, when a linear defect 1 as shown in the figure is present in the flaw detection object, in this detection operation, the defect 1 is detected from the B direction forming an angle θ ₁ with the length direction of the defect 1. Will be there.

Then, the movable flaw detector detects a range corresponding to the previous movement range, for example, a preset movement range or a defect as described above, in the movement direction in which the angle is appropriately changed from the previous movement direction. The defect size is estimated and stored in the range from the position to the position where the defect is no longer detected. The movement direction can be changed by, for example, the turning operation at the predetermined angle θ at the end of the previous movement range. The movement direction changed in this way, that is, the A ′ direction in FIG. 2, is as described above. Then, the defect detection sensor 2 is scanned in a zigzag manner to detect a defect in a range corresponding to the previous movement range. In this detection operation, the defect is detected from the B'direction forming an angle θ ₂ with the direction of the defect 1. Note that the angle θ ₂ = θ ₁ + θ.

The above detection operation, that is, the operation of estimating and storing the defect size in the range corresponding to the previous moving range in the moving direction obtained by appropriately changing the angle from the previous moving direction,
The estimated value group of the defect size is stored repeatedly until the signal from the defect is no longer detected. Note that the angle θ from the above A direction
The angle change is performed for each of the clockwise direction and the counterclockwise direction, and when the signal from the defect is no longer detected, the procedure of the detection operation for the defect 1 is completed. Then, the maximum value of the stored estimated value group is processed as the measured value of the defect dimension.

Next, an operation example of the present invention will be described with reference to the flow charts shown in FIGS. First, FIG. 4 shows an example of the flow of processing when the present invention is applied to a self-propelled ultrasonic flaw detection robot. First, the robot starts processing S1
In this case, for example, it is assumed that it has moved in the A direction to reach a predetermined flaw detection start position. At this position, in step S2, the robot moves in a zigzag direction in a direction perpendicular to the defect detection direction, for example, the direction A in FIG. Perform and collect signal data from defects. Then, in step S3, it is determined whether or not there is a signal from the defect.

As a result of the determination, if there is no signal from the defect, the process proceeds to step S10, the robot moves to the other position in the A direction, and in the same manner as described above, the B direction is set as the flaw detection direction in the next step S2. A defect detection operation for a predetermined distance is performed. Then, in step S3, it is determined whether or not there is a signal from the defect.

As a result of the determination in step S3, when the signal from the defect, that is, the echo is detected and the data of the signal from the defect is collected, it is necessary to derive (estimate) the defect size in step S4. Processing is performed and the result is stored in the storage means as the first estimated value of the defect dimension, as indicated by the symbol M1. Then, proceeding to step S5, the robot changes the moving direction of the robot by a predetermined angle θ by the turning mechanism or the like to set it as the A ′ direction in FIG. And in this state, while moving zigzag about the range corresponding to the previous movement range,
A defect detection operation is performed with the B'direction as the defect detection direction, and signal data from the defect is collected. And step S6
In, it is determined whether there is a signal from the defect.

As a result of the judgment, when the signal from the defect is detected and the data of the signal from the defect is collected, the defect size is derived and the necessary processing is performed in step S7, as indicated by the symbol Mn. Then, it is stored in the storage means as the second estimated value of the defect size. Then, return to step S5,
Furthermore, the moving direction of the robot is changed to change the defect detecting direction of the defect detecting sensor to perform the above-described defect detecting operation. In this way, as long as the signal from the defect is detected in step S6, the defect detection operation is performed by sequentially changing the moving direction of the robot and moving the defect detection sensor, and the defect detection operation in which the direction with respect to the defect is changed is performed and stored in the storage means. Is the third defect
........ It is stored as the nth estimated value.

Then, as a result of the determination in step S6,
When the signal from the defect is no longer detected in the movement range, the process proceeds to step S8, and the maximum value of the first to n-th estimated defect size values stored in the storage unit is extracted. Then, after storing the extracted maximum value as the measured value of the defect dimension in step S9, step S1
Move to 0. The measurement value of the defect size is stored together with the position of the robot.

After deriving the measured value of the defect size at a certain position of the flaw-detecting object and performing necessary storage as described above, the robot moves to another position in the above-mentioned A direction, and again returns to step S2. After the shift, the above defect detection operation is repeated.

Next, FIG. 5 shows another example of the processing flow of the method to which the present invention is applied in a self-propelled ultrasonic robot similar to FIG. 4. The difference from the method of FIG. The detecting operation is a detecting operation in a plurality of different defect size measuring methods, and the defect size is derived for each of a plurality of different methods in each defect detecting operation, and the maximum value of the defect size is extracted for each method. It is the point that each is a measured value,
Except for this point, the operation of each step with the same reference numeral is the same as that of FIG.

With this method, the maximum value of the defect size can be obtained as the measured value for each measuring method, so that there is an advantage that the defect can be regarded as the maximum value in a plurality of methods.

[0026]

As described above, the present invention has the following effects. Since the defect detection operation is performed from each direction and the maximum value is used as the measured value of the defect size, it is possible to prevent the defect from being underestimated. If multiple defect dimension measurement methods are applied to the detection operation in each direction, the maximum value of the defect dimension can be obtained as the measurement value for each measurement method, so that the defect can be regarded as the maximum value in the multiple methods. Yes, and underestimation of defects can be prevented by each method.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a stage of a defect detection operation according to the present invention.

FIG. 2 is a conceptual diagram showing the next stage of the defect detection operation according to the present invention.

FIG. 3 is an explanatory diagram showing a change in defect size due to a change in flaw detection direction.

FIG. 4 is a flowchart showing an operation example of the present invention.

FIG. 5 is a flowchart showing another operation example of the present invention.

[Explanation of symbols]

1 defect 2 Defect detection sensor 3 ultrasonic beam

Continuation of the front page (56) Reference JP-A-5-133942 (JP, A) JP-A-61-117450 (JP, A) JP-A-64-68652 (JP, A) JP-A-64-80859 (JP , A) JP-A-63-263465 (JP, A) JP-A-49-131489 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 29/00-29/28 G01B 17/00-17/08 G01N 22/02

Claims (4)

(57) [Claims] 1. A moving flaw detector for detecting a defect by linearly moving a defect detection sensor and scanning the direction perpendicular to the moving direction as a defect detection direction to detect a signal from the defect in a certain moving direction. In that case, the defect size is estimated from the data group of the appropriate movement range in that direction,
This is stored, and then the operation of estimating and storing the defect size in the range corresponding to the previous moving range is repeated until the signal from the defect is no longer detected in the moving direction where the angle is appropriately changed from the previous moving direction. Defect size estimation value group is stored as a defect size measurement value, and the maximum value of the stored estimation value group is used as the defect size measurement value. 2. The defect size measuring method in a mobile flaw detector according to claim 1, wherein the defect detecting sensor has a defect detecting direction and a direction perpendicular to the defect detecting direction. 3. The defect detecting operation is a detecting operation in a plurality of different defect size measuring methods, and in each defect detecting operation, the defect size is derived for each of a plurality of different methods, and the maximum defect size is obtained for each method. 2. A method for measuring a defect size in a mobile flaw detector according to claim 1, wherein the values are extracted and used as measured values. 4. The defect size measuring method in a movable flaw detector according to claim 1, wherein the defect detection sensor is an ultrasonic flaw detector.