JPH06109712A - Method and apparatus for automatically adjusting sensitivity of ultrasonic flaw detector - Google Patents

Abstract

(57) [Summary] [Purpose] The sensitivity of the device is automatically adjusted so that it is always the optimum sensitivity without making the device large-scale, and the transmitted signal intensity from a sound part, which is the criterion for defect judgment, is kept constant. (EN) An automatic sensitivity adjusting method for an ultrasonic flaw detector, which maintains the temperature, facilitates the determination work, and improves the inspection accuracy, and the apparatus. [Structure] Only the effective signal is extracted from the ultrasonic transmission signal that was used only for the synthesis of the inspection image of the ultrasonic flaw detector, and then the difference from the target sensitivity is obtained from this effective signal. A method for automatically adjusting the sensitivity of an ultrasonic flaw detector, comprising: automatically adjusting the sensitivity of the ultrasonic flaw detector. A signal extractor for branching the ultrasonic transmission signal extracted from the monitor gate section of the ultrasonic flaw detector to extract only a signal having a transmission signal intensity within a certain range as an effective signal, and the effective signal from the signal extractor and the target sensitivity And an automatic sensitivity of the ultrasonic flaw detector, which comprises a signal measuring device for determining the difference between the signal measuring device and a target sensitivity obtained by the signal measuring device as a control signal to a variable attenuator or an amplifier of the ultrasonic flaw detector Adjustment device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic sensitivity adjusting method for an ultrasonic flaw detector and its apparatus.

[0002]

2. Description of the Related Art For example, a honeycomb structure part used in an aircraft such as an Erlang ladder or the like is inspected for peeling or the like by mainly using a transmission type ultrasonic flaw detector. In the transmission type ultrasonic flaw detection, the defect transmission is detected based on the magnitude of the transmission signal by utilizing that the ultrasonic transmission intensity of the defect is lower than that of the sound part. However, as the thickness of the inspection part changes, the transmitted signal intensity of the sound part changes greatly and exceeds the input dynamic range of the flaw detector, so a dedicated inspector constantly monitors the oscilloscope and keeps the signal strength of the sound part constant. The sensitivity of the device is manually adjusted so that

On the other hand, the following method has been conventionally proposed as an automatic sensitivity adjusting method for an ultrasonic flaw detector. A logarithmic amplifier method that uses a logarithmic amplifier in the input amplifier to expand the input dynamic range and increase the amount of signals that can be captured at one time. A teaching method in which the sensitivity of the flaw detection device is taught in advance according to the shape and thickness of the part (position of the ultrasonic sensor), and the flaw detection is performed while the sensitivity is changed by the playback operation. AGC method that activates AGC (automatic gain control) function for transmitted signals.

By the way, in the above-mentioned logarithmic amplifier method, the apparatus becomes large-scaled with respect to the flaw detection target. In addition, since the ultrasonic transmission signal intensity of a sound part, which is a reference for the determination in the transmission method, changes, it is necessary to have experience in determining the defect. The teaching method described above requires a large-scale apparatus for a flaw detection target. Further, since the flaw detection conditions change due to variations in flaw detection components, optimum sensitivity cannot always be obtained. Since the above-mentioned AGC method acts on all transmitted signals, it is difficult to distinguish between a decrease in signal intensity due to a change in wall thickness and a decrease in signal intensity due to a defective portion.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention provides a method for automatically adjusting the sensitivity of an ultrasonic flaw detector, which automatically adjusts the sensitivity of the apparatus so that the sensitivity is always optimum without increasing the size of the apparatus. It is intended to provide the device.

[0006]

An automatic sensitivity adjusting method for an ultrasonic flaw detector according to the present invention for solving the above-mentioned problems is based on an ultrasonic transmission signal used only for synthesizing an inspection image of the ultrasonic flaw detector. Only the effective signal is extracted, the difference from the target sensitivity is then obtained from this effective signal, and then the sensitivity of the ultrasonic flaw detector is automatically adjusted so as to reach the target sensitivity during the feeding operation. The automatic sensitivity adjusting device of the ultrasonic flaw detector of the present invention for carrying out the above-described automatic sensitivity adjusting method branches the ultrasonic transmission signal taken out from the monitor gate section of the ultrasonic flaw detector to divide the transmission signal intensity within a certain range. Signal extractor for extracting only the signal of as the effective signal, a signal measuring device for obtaining the difference between the effective signal from the signal extractor and the target sensitivity, and the difference between the target sensitivity obtained by the signal measuring device as the control signal And a signal circuit for sending to a variable attenuator or an amplifier of the ultrasonic flaw detector.

[0007]

The above-described automatic sensitivity adjusting method for the ultrasonic flaw detector of the present invention is obtained from the vicinity of both ends of the flaw detection range in the ultrasonic transmission signal extracted as a voltage from the monitor gate of the ultrasonic flaw detector. An unstable signal and a signal excluding a signal above a certain level and below a certain level that is determined to be output from a part other than the flaw detection part or a defective portion are used as effective signals, and thus become strong against noise. Also, the difference from the target sensitivity is calculated from the effective signal, and the sensitivity of the ultrasonic flaw detector is automatically adjusted based on this difference so that the target sensitivity is obtained during the feed operation. Is kept constant, the judgment work is facilitated, and the inspection accuracy is improved. Moreover, since the state of the flaw detection component itself is fed back, it is possible to always perform flaw detection with optimum sensitivity without being affected by variations in the components.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic sensitivity adjusting method for an ultrasonic flaw detector and a device therefor according to the present invention will be described. First, the system configuration of the ultrasonic flaw detector and its automatic sensitivity adjusting device will be described with reference to the block diagram of FIG. 1. 1 is an ultrasonic sensor, 2 is a sensor drive unit, 3 is a sensor control unit, 4 is a control / image synthesis computer. The sensor position is transmitted from the sensor drive unit 2, and the mechanism control signal is transmitted / received to / from the sensor control unit 3. An ultrasonic flaw detector 5 is adapted to transmit a transmission signal to the control / image synthesis computer 4. Reference numeral 6 is a variable attenuator or amplifier of the ultrasonic flaw detector 5.

The automatic sensitivity adjusting device 8 in the ultrasonic flaw detector 7 having such a structure is a portion surrounded by a dashed line.
Signal extraction for branching the ultrasonic transmission signal used only for the synthesis of the inspection image transmitted from the ultrasonic flaw detector 5 to the control / image synthesis computer 4 and extracting only the signal of the transmission signal intensity within a certain range as an effective signal. And the signal extractor 9
Signal circuit 10 for obtaining the difference between the effective signal from the target and the target sensitivity, and a signal circuit for sending the difference between the target sensitivity obtained by the signal measuring apparatus to the variable attenuator of the ultrasonic flaw detector 5 or the amplifier 6 as a control signal. It consists of 11

Next, an automatic sensitivity adjusting method of the ultrasonic flaw detector 7 by the automatic sensitivity adjusting device 8 will be described. In ultrasonic flaw detection of the flaw detection component, the ultrasonic transmission signal used only for synthesis of the inspection image transmitted from the ultrasonic flaw detector 5 to the control / image synthesis computer 4, that is, as a voltage from the monitor gate section. The extracted ultrasonic transmission signal is branched, and the signal extractor 9 removes an unstable signal obtained from the vicinity of both ends of the flaw detection range L of the flaw detection component 12 shown in FIG. 2 and a signal other than the flaw detection component. A signal excluding a signal having a certain level or more and a certain level or less, which is determined to have been output from the defect portion, that is, a signal having a certain range of the transmitted signal intensity appearing in the monitor scope as shown in FIG. 3, is extracted as an effective signal. . Next, this effective signal is sent to the signal measuring device 10 and compared with the target sensitivity, that is, the target signal strength, to obtain the difference. Next, by using this difference as a control signal, the sensitivity of the variable attenuator of the ultrasonic flaw detector 5 or the amplifier 6 is automatically adjusted at the time of operation so as to attain the target sensitivity at the next flaw detection.

Thus, it becomes resistant to noise during flaw detection. Further, the intensity of the transmitted signal from the sound portion, which serves as a criterion for defect determination, is kept constant, the determination work is facilitated, and the inspection accuracy is improved. Furthermore, since the state of the flaw detection component itself is fed back, flaw detection can be performed with optimum sensitivity at all times without being affected by variations in the components. As a concrete example, the results of ultrasonic flaw detection of an artificial defect of a tapered honeycomb structure part simulating an aileron ladder of an aircraft will be described below together with a conventional example.

FIG. 5 shows a conventional ultrasonic flaw detector with a thickness of 1 /
This is the result of setting the optimum sensitivity in the area 2 and performing flaw detection on the whole in that state. Since the signal in the portion thinner than the set sensitivity portion is saturated and the transmission signal is not obtained in the thick portion, artificial defects other than the set sensitivity portion cannot be detected.

FIG. 4 shows the case where the automatic sensitivity adjusting method of the present invention is carried out, in which almost uniform transmission signal intensity is obtained over all parts, and all artificial defects are detected. It can be seen that the accuracy has improved.

[0014]

As described above, in the automatic sensitivity adjusting method for the ultrasonic flaw detector of the present invention, among the ultrasonic transmission signals extracted as a voltage from the monitor gate section of the ultrasonic flaw detector,
An unstable signal obtained from the vicinity of both ends of the flaw detection range and signals excluding signals above and below a certain level that are judged to have been output from other than the flaw detection part or from the defective portion are regarded as effective signals, so noise is eliminated. It becomes stronger against. Also, the difference from the target sensitivity is calculated from the effective signal, and the sensitivity of the ultrasonic flaw detector is automatically adjusted to obtain the target sensitivity during feed operation from this difference. Is kept constant, making judgment work easier,
Inspection accuracy is improved. Furthermore, since the state of the flaw detection component itself is fed back, it is not affected by the variation of components,
Can detect flaws with optimum sensitivity at all times. Moreover, unlike the conventional case, the inspector does not need to manually adjust the sensitivity while constantly monitoring it, which eliminates the need for the inspector and significantly reduces the inspection man-hours. Further, according to the automatic sensitivity adjusting device of the ultrasonic flaw detector of the present invention, the excellent automatic sensitivity adjusting method described above can be easily and reliably performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration of an apparatus for carrying out an automatic sensitivity adjusting method for an ultrasonic flaw detector according to the present invention.

FIG. 2 is a diagram showing an effective signal detection range in the automatic sensitivity adjustment method of the present invention.

FIG. 3 is a diagram showing a transmitted signal intensity in a certain range used as an effective signal in the automatic sensitivity adjustment method of the present invention.

FIG. 4 is a diagram showing an image of flaw detection results of artificial defects in a tapered honeycomb structure component by an ultrasonic flaw detection apparatus that has implemented the automatic sensitivity adjustment method of the present invention.

FIG. 5 is a diagram showing an image of flaw detection results of artificial defects in a tapered honeycomb structure part by a conventional ultrasonic flaw detector.

[Explanation of symbols]

 1 Ultrasonic Sensor 2 Sensor Drive Unit 3 Sensor Control Unit 4 Control / Image Synthesis Computer 5 Ultrasonic Flaw Detector 6 Variable Attenuator or Amplifier 7 Ultrasonic Flaw Detector 8 Automatic Sensitivity Adjustment Device 9 Signal Extractor 10 Signal Measuring Device 11 Signal Circuit

Claims (2)

[Claims] 1. An effective signal is extracted from an ultrasonic transmission signal used only for combining inspection images of an ultrasonic flaw detector, then a difference from a target sensitivity is obtained from this effective signal, and then a target is obtained during a feed operation. A method for automatically adjusting the sensitivity of an ultrasonic flaw detector, which is characterized in that the sensitivity of the ultrasonic flaw detector is automatically adjusted so as to obtain sensitivity. 2. A signal extractor for branching an ultrasonic transmission signal extracted from a monitor gate section of an ultrasonic flaw detector to extract only a signal having a transmission signal intensity within a certain range as an effective signal, and a signal extractor from the signal extractor. An ultrasonic wave including a signal measuring device for obtaining a difference between an effective signal and a target sensitivity, and a signal circuit for sending the difference between the target sensitivity obtained by the signal measuring device as a control signal to a variable attenuator or an amplifier of an ultrasonic flaw detector. Automatic sensitivity adjustment device for flaw detectors.