JPH09178715A - Method for detecting peak in ultrasonic flaw detection equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting the peak value of flaw only when the flaw exists closer to bottom surface. SOLUTION: When gating an amplified output waveform in terms of time in an ultrasonic flaw detection equipment and measuring the relative size of a flaw by detecting a peak value 3 for a regular reflection waveform from the flaw being present within the range, a threshold which is larger than an assumed flaw waveform peak value and is smaller than a bottom surface reflection waveform peak is set 7 and the input reception operation of a storage circuit 5 for storing a detection peak value when a reflection wave voltage exceeding it is generated is stopped. On the other hand, by performing delay with a delay circuit 4 before a detected peak value arrives at the storage circuit 5, a peak value to be stored is stored at the storage circuit 5 before output as that only for a target flaw when a flaw to be detected within a gate time and a large bottom surface reflection which is delayed and generated and does not need to be detected occur together, thus detecting the peak of a flaw closer to a bottom surface with improved advantage in terms of size, detection speed, handling, and cost as compared with a computer without using the computer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a peak value of a flaw in an ultrasonic flaw detector, which is often used for industrial purposes and the like. The present invention relates to a peak detection method in which only waves can be targeted for peak detection.

[0002]

2. Description of the Related Art An example of a conventional ultrasonic flaw detector is shown in FIG. At the time of ultrasonic flaw detection, the probe (Fig. 2P) has 10 ^-7
When a short electric pulse of less than a second is given, the ultrasonic pulse waveform generated from the electric pulse advances into the object to be measured, and if there is a flaw, it is reflected at a reflectance depending on the degree of the flaw. When this reflected wave reaches the probe, the probe converts the waveform into a voltage, and if it is amplified, it becomes as shown in FIG.

That is, FIG. 1 shows an example when the measurement shown in FIG. 2 is carried out. In FIG. 2, A is an ultrasonic flaw detection amplifier having a peak value detection circuit and the like, and the amplified waveform is a CRT shown in CRT. It can be observed with an oscillograph device or other waveform observation display, and the detected flaw peak value produces an output as an analog voltage. P is an ultrasonic flaw detection probe driven by A, and is in contact with the surface of the plate to be measured indicated by H via a contact medium such that the ultrasonic waves are not attenuated. The ultrasonic wave generated from P passes through H, and the reflected wave corresponding to the size of the wound returns from P to P, but the main body of the ultrasonic wave further advances and is reflected on the bottom surface B. Return to P. Then, the probe P is moved on the surface S of the plate H for continuous measurement.

Therefore, in FIG. 1, F is a reflected wave from a flaw,
B represents a reflected wave from the bottom surface, and T is a probe driving pulse applied to the ultrasonic probe P. Generally, as far as the output waveform is seen, it has a large amplitude that completely saturates and a clear single Invisible with the pulse of.

Here, as shown in FIG. 3, the waveform from FIG. 1 is taken out as a gate from G1 after a certain time has elapsed from T to G2 in A as shown in FIG. , The extracted waveform p is as shown in FIG.
If a circuit for detecting the peak value on the + side of this waveform is created, the value of p can be taken out as an analog value. The gate between G1 and G2 is set in advance from the position where the scratch can exist.

[0006] G1 is the time from T, which means that the sound velocity of H indicates a certain depth position in H as a constant value depending on the material and temperature, and G2 is the depth distance from it. However, when the flaw position F and the bottom surface B are close to each other, FIG. 1 is as shown in FIG. 5. At this time, if the gate positions G1 and G2 are left unchanged, the waveform taken out by the gate becomes as shown in FIG. The waveform of B is also included, and the resulting peak value p does not indicate the height of the flaw F but that of the bottom surface reflected wave, and does not serve as information regarding the size of the flaw. Since the bottom surface is considered to correspond to an extremely large scratch, B has a waveform almost larger than F.

[0007]

In order to solve the above problems, the G2 position may be set between F and B, but when the flaw F is extremely close to the bottom surface of the plate H to be measured, this is For example, it shows a scratch generated just below the bottom surface of the rolled plate, but when the thickness of H fluctuates even a little, F and B come close to each other from the plate surface S, that is, T You will move away from and approach. That is, even if the position of G2 is initially set between F and B, B
However, since F also moves, it is unlikely that G2 is always between F and B, and the important F may be after G2, and F may not be detected.

[0008]

SUMMARY OF THE INVENTION According to the present invention, an output waveform amplified by an ultrasonic flaw detector is gated in time, and a peak value is detected for a reflection waveform from a flaw existing within the range. When measuring the relative size of scratches, set a threshold value of the voltage that is larger than the expected peak value of the scratch waveform and smaller than the peak value of the bottom reflected waveform, and when the reflected wave voltage exceeds that value. By stopping the input acceptance operation of the circuit that stores the detected peak value and delaying it with the delay circuit while the detected peak value reaches the storage circuit, the flaw that you want to detect within the gate time and the delay later than that When there is a large amount of bottom reflection that does not need to be detected, the peak value to be stored is stored only in the storage circuit as the target flaw, and the peak value can be output.

The present invention will be described below with reference to FIGS. FIG. 7 shows a block diagram of only the gate and the peak detection circuit section in the ultrasonic flaw detector according to the present invention.

FIG. 8 is the same as FIG. 5, and R represents the set threshold value. Figure 9 shows the start G of the gate set for it.
The positions of 1 and end G2 are shown. FIG. 10 is a waveform diagram of FIG.
The peak analog voltage p detected by the gate of the position is shown. FIG. 11 shows the analog voltage with some time delay. FIG. 12 shows a situation in which a voltage exceeding the threshold value of the waveform of FIG. 8 is detected.

The gate generator 2 of FIG. 7 issues a command between G1 and G2 by the setting device 1 of G1 and G2, and the switch circuit passes the waveform of FIG. 8 only between the gates. This is detected by the peak value detector 3 in FIG. This is the delay circuit 4
The result is as shown in FIG. The delay time is, for example, 0 when a 5 MHz probe is used.
It is set to 5 μsec or a time determined by various conditions. However, R of FIG. 8 is set by the threshold value setting device 7, and FIG. 12 is obtained by the circuit 6 which detects the threshold value or more. FIG.
11 goes to the storage circuit 5 for storing the delayed analog waveform of FIG. 11 and stops accepting the stored waveform. Therefore, the analog value stored in the storage circuit 5 is as shown in FIG. Only the peak value is stored, and the peak value of B is not stored. That is, when the stored value is taken out as an output, this shows only the peak value of the flaw F. Of course, this operation is conditioned that the bottom surface reflected wave B is always larger than the flaw reflected wave F, but this is always satisfied.

The delay circuit 4 for delaying the peak value detected as described above and the delayed analog value storage circuit 5
And the arrival of the waveform detected by the threshold value setting unit 7 for setting the value higher than the peak value of the flaw F and lower than the peak value of B, and the detection circuit 6 for detecting the waveform higher than the threshold value. Due to the wiring for stopping the acceptance of the analog waveform of the circuit 5, the output of the memory circuit 5 is only the flaw F and the peak value of the bottom reflected wave B is excluded. Naturally the start of the gate G1
Is set to a time position earlier than the possible flaw F position, and G2 at the end of the gate need only be set to a time position later than the possible flaw F position.

The acceptance stop state of the memory circuit in the above description may be released together with either T, G1 or F to start accepting the peak analog value. When this acceptance is started, the stored value up to that point may be erased. Further, the gate may be terminated when the analog value acceptance of the memory circuit is stopped, and the time may be set as G2. Further, the operation of the peak value detection circuit 3, the delay circuit 4, the storage circuit 5 and the like is the same regardless of whether it is an analog method or a digital method, and the analog output is a stored peak value output as a digital output. It does not change to

[0014]

In general, when the flaw F and the bottom surface B are close to each other and the bottom position fluctuates, it is possible to find the peak value of the flaw F waveform by digitizing the output waveform and inputting it to a computer for analysis. However, according to the method of the ultrasonic flaw detector of the present invention, a computer is unnecessary, and it is far more advantageous than a computer in terms of size, detection speed, handling, cost, and the like.

[Brief description of the drawings]

FIG. 1 shows a reflection waveform in a conventional ultrasonic flaw detector.

FIG. 2 shows an example of a conventional ultrasonic flaw detector.

FIG. 3 is a diagram illustrating a G1 forming a gate and a G2 after a predetermined time has passed.
Is shown.

FIG. 4 shows a waveform of a reflected wave peak of a flaw F.

FIG. 5 shows a reflection waveform when the flaw F and the bottom surface B are close to each other.

6 shows the waveform extracted by the waveform gate in FIG.

FIG. 7 is a block diagram of only a peak detection circuit section in the peak detection method of the present invention.

FIG. 8 shows a reflection waveform when the flaw F and the bottom surface B of the present invention are close to each other.

FIG. 9 shows the positions of G1 and G2 forming the gate.

10 shows an analog peak voltage obtained by detecting the reflection waveform of FIG. 8 with a peak detector.

11 shows a voltage obtained by delaying the peak analog voltage of FIG. 10 by a certain time.

FIG. 12 shows a situation in which a voltage exceeding the threshold value of the waveform of FIG. 8 is detected.

13 shows an analog value in which the voltage of FIG. 12 is stored in a storage circuit.

[Explanation of symbols]

 A Ultrasonic flaw detection amplifier H Measured plate B Measured plate bottom surface S Measured plate surface F Damage P Ultrasonic testing probe G1, G2 Gate p Peak value R Threshold value 1 Gate setting device 2 Gate switch circuit 3 Peak Value detector 4 Peak value delay circuit 5 Memory circuit 6 Detector for values above the threshold value 7 Threshold value setter

Claims (1)

[Claims] 1. A relative size of a flaw is measured by applying a temporal gate to an output waveform amplified by an ultrasonic flaw detector and detecting a peak value with respect to a reflection waveform from a flaw existing within the range. The threshold value of the voltage that is larger than the expected flaw waveform peak value and smaller than the bottom surface reflection waveform peak value is set, and the detected peak value is stored when the reflected wave voltage exceeds it. By stopping the input receiving operation and delaying it with the delay circuit while the detected peak value reaches the memory circuit, scratches you want to detect within the gate time and large bottom reflection that does not need to be detected and occurs later than that When existing together, the peak value to be stored can be stored in the memory circuit as only the target flaw and can be output.