JPH0690185B2 - Ultrasonic inspection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultrasonic inspection apparatus for performing water immersion flaw detection on a large number of objects of the same shape by a pulse reflection method, and in particular, echo level sensitivity in the inspection apparatus. The present invention relates to an inspection device suitable for performing calibration easily and steplessly with a simple configuration.

[Prior Art] In order to ensure a certain quality of a product, in ultrasonic inspection, inspection criteria such as a pass / fail judgment value, a threshold value for echo level, a structure of a master work (material, size, shape, etc.), Inspection conditions including probe position, gain in ultrasonic flaw detector, flaw detection conditions such as gate, etc. are determined according to various types of objects. Among these conditions, the gain of ultrasonic flaw detector is the pass / fail judgment value. It is directly related to the threshold value, and when a large number of objects of the same shape are continuously inspected, it is particularly necessary to keep them constant. However, even if the above-mentioned gain is inspected using the same inspection device, it changes considerably due to, for example, contamination of the water being used, temperature change, or deterioration of the probe, so it is necessary to determine the cycle and perform sensitivity calibration. is there.

Sensitivity calibration of a conventional ultrasonic flaw detector uses a masterwork or sensitivity standard test piece manufactured with the same material, size, shape, etc. of the test part of the test object to detect the reflection echo, This is done by rotating the knob of the ultrasonic flaw detector so as to change the gain so that the reflected echo level becomes constant.

[Problems to be Solved by the Invention]

For this reason, the conventional sensitivity calibration has a problem that the gain can be adjusted only stepwise in a stepwise manner, and the sensitivity calibration is limited to within the range and accurate sensitivity calibration cannot be performed.

Further, when applying the method of changing the gain so that the level of the reflection echo from the conventional master work is constant to the automatic inspection, it is necessary to computer-control the ultrasonic flaw detector, resulting in a significant cost increase. In addition, there is a problem in that the gain control is somewhat difficult, which causes troubles.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to provide an ultrasonic inspection apparatus capable of easily and steplessly performing echo level sensitivity calibration in the ultrasonic inspection apparatus. .

[Means for Solving the Problems]

In order to achieve the above object, the ultrasonic inspection apparatus of the present invention,
A moving device that relatively displaces the subject and a probe facing the subject within a certain distance, and transmits and receives an ultrasonic pulse to and from the subject through the probe and outputs an analog signal of a reflection echo from the subject. In an ultrasonic inspection apparatus including an ultrasonic flaw detector and a computer device that controls the moving device and captures an output signal of the ultrasonic flaw detector to display data, the configuration is the same as the test portion of the subject, And a moving device that generates a timing signal corresponding to the relative displaced position by placing the master work in which the number of defects existing in the inspected part is known so that the master work is changed to the subject and the probe is relatively displaceable, An ultrasonic flaw detector that outputs an analog signal of a reflection echo from the master work for a certain distance that is relatively displaced in synchronization with the timing signal, and is output from the ultrasonic flaw detector. The peak value of each reflected echo is input and accumulated, and the threshold value corresponding to the number of defects of the master work is set in the echo envelope formed by the accumulated peak value of each reflected echo, and the master work is set. And a computer device for setting and displaying different thresholds at which the number of defects and the number of defects at the threshold are the same on echo envelopes having different echo levels obtained by measuring with the same gain.

[Action]

First, prepare a master work having the same material, size, shape, etc., as that of the inspected part of the subject and a known number of defects existing in the inspected part, and move the master work relative to the probe by a moving device. Let At this time, the moving device generates a timing signal corresponding to the relative displaced position.
The ultrasonic flaw detector outputs an analog signal of a reflection echo from the master work during a certain distance in which the master work and the probe are relatively displaced in synchronization with the timing signal. The output analog signal is input to the computer device, digitized in the computer device, and stored in the memory with the digital value and the flaw detection position of the timing signal as a pair. With respect to the accumulated digital value, an echo envelope formed by the peak value is displayed in a graph, and a threshold value corresponding to the number of defects in the master work is set. This threshold becomes the pass / fail judgment value,
Subsequently, the pass / fail of the actual product subject is judged. However, due to changes in flaw detection conditions and the nature of ultrasonic waves, it is necessary to determine the cycle and perform sensitivity calibration.In this case, when the echo envelope and threshold value are set using the master work, When the echo envelopes are graphically displayed with the same gain as the gain, the echo levels of both echo envelopes are not always the same level, and echo envelopes having different peak values may be formed.
The sensitivity calibration method in this case is performed by setting the threshold values for the different echo envelopes so that the number of defects is the same as the number of defects at the threshold value set for the original echo envelope. The acceptance / rejection determination of the subject of the actual product is performed again using the sensitivity-calibrated threshold value.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 and 2. In the figure, reference numeral 1 denotes a masterwork having an inspected portion 1a having the same material, size, and shape as the inspected portion (circumferential welded portion) 1'a of the inspected object 1'which is an actual product. The number of defects in the test portion 1a is already known. Reference numeral 2 denotes a probe arranged to face the master work 1 and 3 denotes a rotating device for rotatably mounting the master work 1 (or the subject 1 '). Due to the rotation, the test portion 1a (or 1'a) and the probe 2 are relatively displaced, and at the same time, a predetermined timing signal corresponding to the relative displacement position is generated by the rotating device 3. Reference numeral 4 denotes an echo reflected from the master work 1 during a fixed distance (one rotation in the case of this embodiment) in which ultrasonic waves are transmitted and received to and from the master work 1 in synchronization with the timing signal via the probe 2. Is an ultrasonic flaw detector that outputs an analog signal of. Reference numeral 5 denotes an A / D converter for inputting and digitizing a plurality of reflected echoes output from the ultrasonic flaw detector 4, for example, the peak value of each reflected echo at 1,000 points per rotation.
Is a memory for accumulating data paired with the peak value digitized by the A / D converter 5 and the flaw detection position by the timing signal, 7 is a display, and an echo envelope formed by the data accumulated in the memory 6. Display the threshold set on the line and the echo envelope. Reference numeral 8 is a keyboard, 9 is a CPU, and 10 is a computer device including an A / D converter 5, a memory 6, a display 7, a keyboard 8, a CPU 9, and the like.

When the master work 1 facing the probe 2 is rotated by the rotating device 3, the timing signal is generated at the same time as the rotation, and the ultrasonic flaw detector 4 finishes from the flaw detection start position in synchronization with the timing signal. The analog signals of a plurality of (for example, 1,000 points) reflected echoes are output from the master work 1 up to the position, that is, according to the rotation angle during one rotation of the matus work 1. The analog signal is input to the computer device 10, digitized by the A / D converter 5, and the digital value is paired with the flaw detection position signal and stored in the memory 6. The accumulated data is displayed on the display 7 as an echo envelope formed by the peak value of the reflected echo, and a threshold value corresponding to the number of defects of the master work 1 is set in the echo envelope.

When the threshold value is set, the master work 1 is changed to the inspection of the actual object 1'of the product, and the acceptance / rejection determination is performed based on the threshold value. However, when the inspection is restarted after a certain period of time, or after a large number of inspections have been performed even for the same type of object, the inspection conditions in the inspection device may change due to water contamination or probe deterioration. However, the gain of the ultrasonic flaw detector 4 is likely to change, and therefore it is necessary to determine the cycle and calibrate the sensitivity.

As a method of sensitivity calibration, the master work 1 is used again, and the echo envelope is displayed on the display 7 as a graph with the same gain as that of the echo envelope obtained at the beginning. However, as shown in FIG. 2, assuming that the echo envelope initially obtained is a, an echo envelope b having different echo levels is formed in the display 7 due to a change in the inspection condition or the like, and the echo envelope a, The echo level of b may not always be the same level. When the echo envelopes a and b have different echo levels as described above, the number of known defects between the rotation angles m and n at the threshold value A set for the echo envelope a and the number of defects in the echo envelope b. The threshold value B is set to the echo envelope b so that the values are the same. When the threshold value B is set, the inspection of the actual object 1 ′ of the product is performed again, and the acceptance / rejection determination is performed by the threshold value B. In this case, the threshold value B has a lower echo level than that of the threshold value A as shown in FIG. 2, but the sensitivity is calibrated in response to changes in inspection conditions and the like. It is possible to obtain the same inspection result as the inspection result of 1'with the threshold value A.

As described above, the sensitivity calibration of the echo level can be steplessly and accurately shifted to the one corresponding to the inspection condition in that case, and an accurate pass / fail judgment value can be obtained.

In addition, in the above-mentioned embodiment, the portion to be inspected such as the circumferential welded portion.
The case where the master work 1 having 1a, 1'a or the subject 1'is rotated by the rotating device 3 has been described, but the present invention is not limited to this, and a linear material having a constant length on a flat material can be used. In the case of flaw detection of the welded portion, it is of course possible to use it in the same manner. In that case, the moving device 3 is used instead of the rotating device 3.

〔The invention's effect〕

Since the present invention is configured as described above, it is possible to easily and steplessly perform sensitivity calibration of the echo level in the ultrasonic inspection apparatus with a simple configuration, and the accuracy of the object can be improved. The effect that a good and accurate pass / fail judgment can be performed is produced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the ultrasonic inspection apparatus of the present invention, and FIG. 2 shows an example of data graphically displayed on the display of the apparatus of FIG. It is a diagram. 1 ... Masterwork, 1 '... Actual product specimen, 1a,
1'a ... Inspected part, 2 ... probe, 3 ... rotating device (moving device), 4 ... ultrasonic flaw detector, 10 ... computer device.

Claims (1)

[Claims] 1. A moving device that relatively displaces a subject and a probe facing the subject within a certain distance, and an ultrasonic pulse is transmitted to and received from the subject via the probe to generate a reflection echo from the subject. In an ultrasonic inspection apparatus including an ultrasonic flaw detector that outputs an analog signal, and a computer device that controls the moving device and captures an output signal of the ultrasonic flaw detector to display data, a test portion of the subject and A master work having the same structure and having a known number of defects existing in the inspected part is changed to the object to be placed so as to be relatively displaceable with the probe, and a timing signal corresponding to the relative displaced position is generated. Moving device, an ultrasonic flaw detector that outputs an analog signal of a reflection echo from a master work for a certain distance that is relatively displaced in synchronization with the timing signal, and the ultrasonic flaw detector Accumulated by inputting the peak value of each reflected echo output by, the threshold value corresponding to the number of defects of the master work is set to the echo envelope formed by the peak value of each accumulated reflected echo, A computer device configured to set and display different threshold values at which the number of defects and the number of defects at the threshold value are set and displayed on echo envelopes having different echo levels obtained by measuring the masterwork with the same gain. An ultrasonic inspection device characterized by the above.