JPS6226421B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic flaw detection apparatus equipped with an automatic sensitivity calibration circuit.

Conventionally, in this type of ultrasonic flaw detection equipment, the determination of whether or not a defect in a material to be inspected is harmful has been made by comparing the amplitude of the reflected echo within the area where the defect occurs, which is determined in advance artificially or by other methods. Comparison and discrimination are usually performed based on whether the amplitude of the reflected echo is larger or smaller than the amplitude of the reflected echo for a reference defect. Conventionally, the calibration work for adjusting the amplitude of the reflected echo with respect to the reference defect to a constant level has been performed by manual calibration by an operator. FIG. 1 shows an example of conventional manual calibration by an operator. Fig. 1A shows a case where a plate material 1 is vertically immersed in water as the material to be inspected.
is kept stationary, and the amplitude H of the defective reflection echo F that appears following the transmitted pulse T and the surface reflection echo S is monitored with an oscilloscope, and adjusted to a required amplitude, for example, 50% amplitude. In addition, Fig. 1B shows a case where a pipe material 4 is subjected to water immersion angle flaw detection, in which an artificial defect 5 is provided on the circumferential surface of the pipe material 4, and the pipe material 4 is rotated at a constant speed as shown by the arrow or the reflected echo F is maximized. The position of the amplitude,
For example, it is stopped at the 1-skip position shown in the end view of FIG. 1B, and the amplitude of the defect reflection echo F is matched using an oscilloscope. Incidentally, when the pipe material 4 is rotating, a defective reflected echo appears at a moved position as indicated by a dotted line F'. However, such manual calibration by operators requires an enormous amount of work as the number of flaw detection channels increases, and individual operator differences tend to occur, and even in actual flaw detection lines, the judgment results of harmful defects may vary from day to day. This has led to a situation where the ultrasonic flaw detection equipment has been damaged, and has become a major factor hindering the reliability of ultrasonic flaw detection equipment.

An object of the present invention is to automatically adjust the gain of an amplifier, etc., so that the amplitude of the detected reflected echo becomes a predetermined amplitude during the period when the reflected echo from the contrast defect is detected by scanning the probe. By being equipped with an automatic sensitivity calibration circuit for the The present invention provides a sonic flaw detection device.

A preferred embodiment of the invention will now be described in the case of a single channel with reference to the drawings.
Note that even in the case of multiple channels, the configuration operation for each channel is the same as in the case of a single channel.

FIG. 2 shows an embodiment of the present invention regarding an ultrasonic flaw detection apparatus for vertical water immersion flaw detection, and also shows an automatic calibration distance gate and defect detection output. The probe 3 is sent in the direction of an arrow 6 by a scanning mechanism (not shown) to the plate material 1, which is a material to be inspected, which is submerged in water, and scans for a comparative defect 2. Note that the comparison defect 2 is shown enlarged for convenience of explanation. The probe 3 is connected to an ultrasonic flaw detector 8 by a cable 7, receives a transmission pulse signal of a predetermined period, converts and amplifies the reflected echo from the inspected material into an electric signal, and sends it out as a detection signal a. The output of the ultrasonic flaw detector 8 is connected to an analog/digital converter 9 (hereinafter referred to as an A/D converter), which converts the detection signal a into a digital signal. The output of the A/D converter 9 is input to the digital comparator 10, and the comparison standard of the digital comparator 10 is set in the microcomputer 11 by an arithmetic processing means. By inputting the product specifications of the material, comparison reference values are extracted from table information and automatically set. For this purpose, the digital comparator takes out the difference between the defective echo amplitude and the comparison reference value, and operates the attenuator controller 12 under the control of the microcomputer 11.
A circuit section 13 consisting of this digital comparator 10, attenuator controller 12, and microcomputer 11 constitutes an automatic sensitivity calibration circuit section in the present invention. The operation of the automatic sensitivity calibration circuit section 13 is controlled by the microcomputer 1 by the distance gate b that is opened when the probe 3 and the plate 1 are moved relative to each other and the probe 3 touches the contrast defect 2.
This is done by activating 1. Furthermore, the control output of the attenuator controller 12 is transmitted to the ultrasonic flaw detector 8.
The amplification gain is changed by increasing or decreasing the value of the attenuator provided in the amplifier for receiving echoes within, thereby increasing or decreasing the amplitude of the defective reflected echo.

Next, the automatic calibration operation for the embodiment shown in FIG. 2 will be explained. A plate material 1 on which an artificial contrast defect 2 has been processed as a calibration standard is set as a material to be inspected, and the probe 3 and the plate material 1 are moved relative to each other by a scanning mechanism. When the probe 3 touches the comparison defect 2, the distance gate b for automatic calibration is opened and the microcomputer 11 is activated. The detection signal a detected from the contrast defect 2 by the ultrasonic flaw detector 8 is converted into a digital signal representing the amplitude by the A/D converter 9, and the digital comparator 10 compares it with the reference value set by the microcomputer 11. The attenuator controller 12 reduces the amplification gain if it is larger than the reference value, and increases the amplification gain by the attenuator controller 12 if it is smaller than the reference value. Further, if it is within a prescribed range for the reference value, the attenuator controller 12 is not controlled and the amplification gain is maintained as it is. The gain modification operation by the attenuator controller 12 is controlled by the microcomputer 11, and is performed at intervals of, for example, 10 ms until the gain falls within a specified range. As a result, the detection signal a, which had a large amplitude as shown in the figure at the initial stage of defect scanning, is corrected to the specified value H by the automatic calibration operation. If this correction operation is completed while the distance gate b is open, the operation of the automatic sensitivity calibration circuit section 13 is stopped at that point. If the correction operation is not completed while the distance gate b is open, the operator is informed that a restart is required. As a result, the operator restarts the scanning mechanism that is moving the probe 3 and the plate 1 relative to each other, and the automatic calibration operation is repeated until it is completed. After the automatic calibration is completed, the operation of the automatic sensitivity calibration circuit section 13 is stopped, and the scanning mechanism is operated again to perform flaw detection of the artificial contrast defect 2 and confirm that the specified reflected echo amplitude is obtained. From there, we begin the process of identifying harmful defects using ultrasonic testing of products.

FIG. 3 shows an embodiment in which the ultrasonic flaw detection apparatus of the present invention is used for water immersion angle flaw detection of pipe materials. In FIG. 3, the configuration of the ultrasonic flaw detection apparatus is the same as the embodiment shown in FIG. 2, and for convenience of explanation, the artificial comparison defect 5 of the pipe material 4 is shown enlarged in the longitudinal direction. The echo detection signal a obtained from the artificial contrast defect 5 appears periodically with changing amplitude because the pipe material 4 is rotated relative to the probe 3, and as is clear from the enlarged detection signal. The period T of the peak value corresponds to the time required for one revolution of the pipe material 4, and the detection signal a is obtained as a set of pulse trains appearing every oscillation period t of the ultrasonic pulse.

Therefore, the automatic sensitivity calibration operation for the embodiment shown in FIG. 3 will be explained.

First, an initial value of sensitivity is set for the ultrasonic flaw detector 8. This initial value is set to an empirically obtained value, if available, or to an intermediate value between the maximum sensitivity and the minimum sensitivity if no such value is available. Artificial contrast defect 5 by scanning mechanism
The probe 3 is rotated at a constant speed while the pipe material 4 having the
Move relative to. When the probe 3 reaches one end of the artificial contrast defect 5, a calibration operation is started. That is, the ultrasonic flaw detector 8 and A/D converter 9 are put into operation, distance gate b is started, and automatic sensitivity calibration circuit section 13 is put into operation. The reflected echo from artificial contrast defect 5 is A/D
It is digitally converted by the converter 9, and the maximum echo amplitude value when the probe 3 detects an artificial defect is read by the digital comparator 10. This maximum echo amplitude value is read by timing control of the microcomputer 11 with respect to the digital comparator 10. If necessary, the maximum echo amplitude value may be determined over two or more times, and the average value of these peak values may be determined. At the same time, a comparison reference value is set in the digital comparator 10 by the microcomputer 11 and compared with the actual measurement value, and if the deviation is within a specified range, the calibration operation is completed. If the deviation is outside the specified range, a new sensitivity value that brings the echo amplitude within the specified range is calculated, this value is set in the ultrasonic flaw detector 8 by the attenuator controller 12, and its amplification is performed. Gain is changed. The same operation is repeated, and the calibration operation is ended when an actual measured value of the echo amplitude that falls within the specified range is obtained. still,
If the calibration value set by the attenuator controller 12 is either the maximum sensitivity or the minimum sensitivity of the ultrasonic flaw detector 8, and the digital comparator 10 still has a deviation outside the specified range, Since the sensitivity calibration described above is impossible, the operator is notified of the sensitivity calibration failure by displaying it.

The above calibration operation is performed within the scanning time of the probe 3 for the artificial contrast defect 5.
If the sensitivity calibration is not completed during scanning of the artificial contrast defect, the operator is notified of this by displaying the screen, and the artificial contrast defect 5 of the pipe material 4 is moved relative to the probe 3 again, and the above-mentioned calibration operation is specified. This will be repeated until a calibration sensitivity of . Furthermore, when the calibration operation is completed, the automatic sensitivity calibration circuit section 1
3 is stopped, the pipe material 4 having the artificial contrast defect 5 is moved relative to the probe 3, and it is confirmed whether the specified echo amplitude is obtained with the calibrated sensitivity. We will begin flaw detection work to determine whether or not the defects are harmful.

Note that the above embodiments explain the amplitude calibration of reflected echoes using artificial contrast defects;
Of course, by using the above comparison defects having different distances from each other, it is possible to automatically correct the distance sound field characteristics of the ultrasonic flaw detector with the same device configuration. Further, the present invention includes not only the water immersion flaw detection method but also the contact flaw detection method, and it is also possible to use a split type probe or the like.

As explained above, the ultrasonic flaw detector of the present invention includes an automatic sensitivity calibration circuit that automatically adjusts the sensitivity of the ultrasonic flaw detector in order to compare the echo amplitude from the artificial contrast defect with a reference value and adjust it to a specified value. By providing this feature, the sensitivity of the ultrasonic flaw detector can be automatically adjusted not only in the case of one channel but also in the case of multiple channels by moving the material to be inspected that has an artificial contrast defect relative to the probe of each channel. It is automatically calibrated by sequentially repeating the operations of comparison with the detected echo amplitude of the sensitivity calibration circuit, feeding back the difference, and changing the sensitivity, and there is room for human error due to individual operator differences in determining the echo amplitude that becomes the reference value. Since there is no
This has the effect of significantly increasing work efficiency.

In addition, when the work is completed within the specified time, the operation of the calibration circuit is stopped, and when the work is not completed, the operator is notified to that effect, which reduces the time and effort required for calibration. This also has the effect of greatly increasing work efficiency.

Furthermore, data regarding the inspected material and comparative defects are given in advance to the arithmetic processing means that sets the reference value for sensitivity settings, so even if the inspected material or comparative defects are changed, sensitivity calibration can be performed quickly and easily. The effect is that it can be done.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram to clarify manual sensitivity calibration in a conventional ultrasonic flaw detection device, and Fig. 2 shows an example of the ultrasonic flaw detection device of the present invention used for water immersion vertical flaw detection. FIG. 3 is a block diagram showing the ultrasonic flaw detection apparatus of the present invention used for water immersion angle flaw detection. 1... Board material, 2, 5... Artificial contrast defect, 3...
Probe, 4... Pipe material, 7... Cable, 8...
...Ultrasonic flaw detector, 9...Analog/digital converter (A/D converter), 10...Digital comparator, 11...Microcomputer, 12...
...Attenuator controller, 13...Automatic sensitivity calibration circuit.

Claims (1)

[Scope of Claims] 1. Ultrasonic flaw detection means for detecting echoes reflected by the contrast defects by a probe that moves and scans contrast defects formed on a material to be inspected using ultrasonic waves; an arithmetic processing means for setting a comparison reference value based on data regarding the inspection material and comparative defects; a comparison means for comparing the detection signal level of the reflected echo output from the ultrasonic flaw detection means with the comparison reference value; Control means for controlling the gain of the ultrasonic flaw detection means during scanning of the probe so that the detection signal level of the reflected echo falls within a prescribed range centered on the comparison reference value based on the comparison result of the comparison means. and when the control is completed during the scanning, the operations of the arithmetic processing means, the comparison means and the control means are stopped, and when the control is not completed, a predetermined display is provided to the operator. Flaw detection equipment.