JPH0599908A - Gain controlling apparatus for ultrasonic flaw detector - Google Patents

Abstract

PURPOSE:To obtain a gain controlling apparatus for an ultrasonic flaw detector which can perform adequate flaw detection regardless of the state of the surface of a body under inspection, the presence or absence of temperature drift in a circuit and the like. CONSTITUTION:The ultrasonic-wave reflected signal from a probe 2 is stored in a waveform memory 6 through a receiving part 4, an A/D converter 5 and a gate circuit 16 and displayed on a liquid-crystal display part 14. A predetermined reference signal is taken out of the ultrasonic-wave reflected signals. Meanwhile, a specified level is set with respect to the maximum level, which can be displayed on the liquid-crystal display part. This level is compared with the reference signal. The gain of the receiving part 4 is adjusted based on the deviation between both values. Since the gain is automatically adjusted, the adequate flaw detection can be performed regardless of the peripheral conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gain control device for an ultrasonic flaw detector for detecting the size and position of a defect or the like on an object to be inspected.

[0002]

2. Description of the Related Art An ultrasonic flaw detector is known as an apparatus for inspecting the state of the surface or the inside of an object without destroying the object. Such an ultrasonic flaw detector emits an ultrasonic wave from the probe to the object, receives the reflected wave by the probe, converts the reflected wave into an electric signal corresponding to this, and outputs the electric signal (echo The signal) is received by the receiver, A / D converted and processed by the microcomputer, and the result is displayed as a waveform.

FIG. 6 is a side view showing an object to be inspected and a probe. In the figure, reference numeral 1 is an object to be inspected, and 2 is a probe abutted on the surface of the object to be inspected 1. f ₁ and f ₂ are objects to be inspected 1
Defects present inside the. When the probe 2 is at the position shown in the figure, the ultrasonic waves emitted from the probe 2 are reflected by the defect f ₁ and the bottom surface of the inspected object 1 and returned to the probe 2 to be converted into an electric signal. Is processed and displayed.

FIG. 7 is a signal waveform diagram displayed on the display unit. This waveform diagram shows a signal when the probe 2 is at the position shown in FIG. 6, where T is a transmitted wave immediately reflected on the surface of the inspected object 1, F ₁ is an echo signal reflected by the defect f ₁ , and B
Indicates a bottom surface wave reflected on the bottom surface of the inspected object 1.

In the ultrasonic flaw detector, in order to check only the defective portion, a means for setting a gate in advance and processing an echo signal within the gate range is adopted. FIG. 7 shows the contents of the gate. That is, t ₁ and t ₂ respectively indicate the start time and end time of the gate, and only the signal within the time interval between them (in this case, the echo signal F _{1 of the} defect) passes and is processed. Also, the gate is set not only for time but also for signal level. This value is indicated by the level V _S , and it is judged whether or not the echo signal within the time interval is equal to or higher than the level V _S. The gain for the echo signal received by the gate or the receiver is input and set in advance by the keyboard.

[0006]

The inspection of the object 1 to be inspected by the ultrasonic flaw detector is performed by sequentially moving the probe 2 in the arrow direction as shown in FIG. By the way, for example, when dirt D is attached to the surface of the object 1 to be inspected just above the defect f _2, the ultrasonic wave emitted from the probe 2 is attenuated by the dirt D and its echo signal is set by the gate. There is a risk that the level will be lower than the set level V _S.

FIG. 8 is a signal waveform diagram showing this state.
Echo signal of the defect f ₂ is defective f ₂ defect f ₁ the same depth, despite the defects of the same size, it is below the level V _S for stains D, and there is a defect f ₂ However, it will be judged to be normal. Such a situation occurs not only when the dirt D is present but also when a part of the surface is rough or when the pressing force of the probe 2 is uneven. A similar situation occurs in the water depth method in which the probe 2 is not brought into direct contact with the object to be inspected. Further, when the ultrasonic flaw detector is used for a long time, the functions thereof are deteriorated due to temperature drift of the transmitter and the receiver, and the same situation occurs.

Conventionally, such a situation has been solved by the operator adjusting the gain of the receiver or changing the contact pressure of the probe 2 by intuition based on experience, but the operator is unskilled. In this case, it is impossible to eliminate the above situation, and it is troublesome to adjust the gain and change the pressure even if an unskilled person is involved, which causes a problem that the inspection time becomes long.

An object of the present invention is to solve the above-mentioned problems in the prior art and to provide a gain control device for an ultrasonic flaw detector capable of performing stable and accurate inspection without requiring any manpower.

[0010]

To achieve the above object, the present invention provides a transmitter for outputting a pulse for exciting a probe and a receiver for receiving an ultrasonic wave reflection signal from the probe. A display unit for displaying the waveform of the signal based on the signal received by the receiving unit; gate means for setting an arbitrary time range after the pulse output; and a signal existing in the selected time range. In the ultrasonic flaw detector equipped with the maximum value detecting means for detecting the maximum value, a predetermined reference signal of the ultrasonic reflection signals can be taken out and the reference signal can be displayed on the display section. Other gate means for which a predetermined level is determined with respect to the maximum level, a first calculation means for calculating a deviation between the reference signal and the predetermined level, and a gain deviation amount corresponding to the calculated deviation. And second computing means, characterized in that a gain adjustment means for adjusting the gain of the receiver unit based on the gain deviations calculated.

[0011]

The ultrasonic wave reflected from the object to be inspected is converted into an electric ultrasonic wave reflected signal by the probe, amplified and detected by the receiving section, further image-processed, and then displayed on the display section. Of the ultrasonic reflected signals, for example, a bottom surface reflected wave signal from the bottom surface of the object to be inspected or a surface reflected wave signal from the surface of the object to be inspected is used as a reference signal, and a display unit is provided for comparison with the maximum level of the reference signal. A predetermined predetermined level is set for the maximum level that can be displayed.

At the time of ultrasonic flaw detection, the reference signal is compared with the above predetermined level, the deviation thereof is calculated, the deviation of the gain of the receiving unit corresponding to the deviation is calculated, and the deviation is received based on the deviation of the gain. The gain of the section is adjusted.
That is, the gain of the receiving unit is automatically adjusted so that the maximum value of the reference signal and the predetermined level always match. As a result, during ultrasonic inspection, the gain of the receiver is held at an optimum value and proper flaw detection is possible regardless of the ambient conditions such as the surface condition of the object to be inspected.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

FIG. 1 is a block diagram of a gain control device for an ultrasonic flaw detector according to an embodiment of the present invention. In the figure, 1 is an object to be inspected, f ₁ is a defect in the object to be inspected 1, W is a water tank in which the object to be inspected 1 is placed, Wa is water, and Wb is a mounting table of the object to be inspected 1. Reference numeral 2 is a probe, and in the case of the drawing, water Wa
It is opposed to the inspected object 1 via. Reference numeral 3 is a transmission unit that outputs a pulse to the probe 2 to generate an ultrasonic wave, and 4 is a reception unit that receives an echo signal from the probe 2. The receiving unit 4 is composed of an attenuation circuit 4a, an amplification circuit 4b and a detection circuit 4c.

Reference numeral 5 is an A / D converter for converting the analog echo signal received by the receiving section 4 into a digital value, and 6 is an A / D converter.
A waveform memory for storing the data converted by the D converter 5,
Reference numeral 7 is an address counter for designating the address of the waveform memory 6. Reference numeral 8 is a timing circuit composed of a crystal oscillator, which controls the pulse output timing of the transmitter 3, the conversion timing of the A / D converter 5, and the address designation timing of the address counter 7.

Reference numeral 10 is a C for performing necessary control such as processing of data stored in the waveform memory 6 and driving of the timing circuit 8.
PU (Central Processing Unit), 11 is a RAM (Random Access Memory) for temporarily storing various parameters and data, and 12 is a ROM for storing the processing procedure of the CPU 10.
(Read only memory). Reference numeral 13 is a keyboard input unit for inputting required data. Reference numeral 14 is a liquid crystal display unit composed of a predetermined number of liquid crystal dots arranged in a matrix, 15 is a display unit controller for controlling the display of the liquid crystal display unit 14, and 15m is a display unit controller 15
Is a display memory for storing data displayed on the liquid crystal display unit.

Reference numeral 16 is a gate circuit. The gate circuit 16 includes a time gate signal generation circuit and a maximum value detection circuit, and finds the maximum value of the data existing within the gate range set by the time gate signal generation circuit. In this embodiment, two time gates are provided, one is a gate corresponding to the time when the defect echo signal is present, and one is a gate corresponding to the time when the bottom wave echo signal which is the reference signal is present. Reference numeral 18 denotes the ultrasonic flaw detector main body of the present embodiment.

FIG. 2 is a plan view of the keyboard input section shown in FIG. In the figure, numeral 13a is a numeral key consisting of numerals "0" to "9", numeral 13b is a decimal point key, numeral 13c is a sound velocity key for inputting a sound velocity, numeral 13d is a gate level key for inputting a gate level, and numeral 13e is A gate start point key for inputting the gate start point, 13f is a gate width key for inputting the gate width, 13g is a set key for setting the input numerical value, 13h is a clear key for canceling the set numerical value, Reference numeral 13i is a reference gate key for setting a reference signal.

Next, the operation of this embodiment will be described with reference to the waveform chart shown in FIG. 3 and the flow charts shown in FIGS. In this embodiment, as the reference signal, the bottom surface echo signal reflected by the bottom surface of the object 1 to be inspected as described above (FIGS. 7 and 8).
The echo signal B) shown in is used. Then, control is performed to adjust the gain of the receiving unit 4 so that the maximum value of the bottom surface echo signal B is always at a predetermined level on the display surface of the liquid crystal display unit 14. This will be further described with reference to FIG.

In FIG. 3, 14D shows the display surface of the liquid crystal display unit 14. The lowermost part of the display surface 14D is divided into the uppermost part, the lowermost part is "0"%, and the uppermost part is "100"%.
Now, assuming that when the maximum value of the bottom surface echo signal B is 2V, and the tip of the waveform is at the uppermost portion of the display surface 14D, when the predetermined level is set to 1V, the bottom surface echo signal B has a waveform B in this embodiment. _As shown in ₀ , the peak is displayed on the display surface 14.
The gain of the receiving unit 4 is adjusted so that the position is 50% of D. The gain adjustment amount ΔG for changing the bottom echo signal B to the bottom echo signal B ₀ is −20 log.
(1/2) = 6 dB. The predetermined level is preferably set to about 80%.

Next, referring to the flow charts of FIGS. 4 and 5,
The actual operation of ultrasonic flaw detection in this embodiment will be described. First, the gate (gate 1) for the defect echo signal is set using the gate start point key 13e, the gate width key 13f, the gate level key 13d and the required numeric key 13a of the keyboard input unit 13 (step S ₁ shown in FIG. 4). ). Next, to set the gate (gate 2) relative to the bottom surface echo signal as a reference signal with a reference gate key 13i and the required number keys 13a of the keyboard input unit 13 (Step S _2). After setting the two gates, ultrasonic waves are radiated from the probe 2 (step S ₃ ), and the bottom surface echo signal is displayed on the display surface 14.
The gain of the receiver 4 is adjusted so as to reach a predetermined level on D, and the end signal input is awaited (step S ₄ ). The gain G of the receiving unit 4 when the gain adjustment is completed and the peak value (maximum value) P of the bottom surface echo signal at that time are stored in the RAM 11 (step S ₅ ). Then performs a gain process (Step S _6), performs flaw detection was collected data (defect data) in the gate 2 (Step S _7), flaw is determined whether or not it is completed (Step S _8), the procedure repeats the processing of S ₆ ~ procedure S ₈ until the flaw end.

Details of the gain processing in step S ₆ will be described below with reference to the flowchart shown in FIG. In the gain processing, the peak value p in the gate 2, that is, the maximum value p of the bottom surface echo signal is read every predetermined time (step S).
₆₀ ). Next, the value P stored in step S ₅ from the RAM 11
The value P is taken out and the peak value p is compared (step S ₆₁ ). When the peak value p is larger than the value P, that is, when the gain of the receiving unit 4 is larger than the predetermined gain, the deviation ΔP between the two is calculated (step S ₆₂ ), and this deviation Δ
A gain deviation ΔG corresponding to P is obtained (step S ₆₃ ).

This gain deviation ΔG can be obtained by the following equation, as mentioned in the explanation of FIG. ΔG = −20log (ΔP / V ₁₄ ) However, in the above formula, the value V ₁₄ is the full-scale voltage of the display surface 14D (2V in the example illustrated in the description of FIG. 3).

When the gain deviation ΔG is obtained, the gain G to be newly set in the receiving section 4 is obtained from the current gain G of the receiving section 4 and the gain deviation ΔG (step S ₆₄ ), and this gain G is received. It is set in the section 4 (step S ₆₅ ).

On the other hand, in step S ₆₁ , the peak value p is the value P.
Smaller when the (gain of the receiver 4 a predetermined gain smaller) is determined, the newly obtained gain G to be set in the receiver 4 in the processing of steps S ₆₆ ~ Step S _68, receiving this Set in Part 4. In step S ₆₁ , the peak value p
If it is determined that the value P is equal to the value P, the value G stored in the RAM is read (step S ₆₉ ) and the value G is set in the receiving unit 4. In this case, the gain of the receiver 4 is not changed.

As described above, in the present embodiment, the bottom surface echo signal is used as the reference signal and is constantly compared with the predetermined level during the flaw detection, and the gain of the receiving unit 4 is adjusted based on the result. Appropriate flaw detection can be performed regardless of the surface condition of the substrate, the presence or absence of temperature drift in the circuit, and the like. Further, since the adjustment of the gain is automatically performed, no trouble is required and even if the operator is unskilled, flaw detection can be performed without any trouble.

In the description of the above embodiment, the case where the bottom surface echo signal is used as the reference signal has been described. However, this is when the defect is extremely fine, or the thickness of the plate or steel pipe is measured by using a flaw detector. Is effective for. However, in the case of an inspected object with a large defect, the bottom surface echo signal may change depending on the size of the defect. Therefore, in such a case, it is convenient to use, as the reference signal, the surface echo signal reflected by the surface of the object to be inspected which maintains a constant level regardless of the size of the defect.

[0028]

As described above, according to the present invention, the predetermined reference signal of the ultrasonic reflection signals is constantly compared with the predetermined level during the flaw detection, and the gain of the receiving unit is determined based on the result. Since the adjustment is made, proper flaw detection can be performed regardless of the surface condition of the object to be inspected and the presence or absence of temperature drift in the circuit. Further, since the adjustment of the gain is automatically performed, no trouble is required and even if the operator is unskilled, flaw detection can be performed without any trouble.

[Brief description of drawings]

FIG. 1 is a block diagram of a gain control device for an ultrasonic flaw detector according to an embodiment of the present invention.

FIG. 2 is a plan view of the keyboard input unit shown in FIG.

FIG. 3 is an explanatory diagram illustrating a relationship between a display surface of the liquid crystal display unit shown in FIG. 1 and a reference signal.

FIG. 4 is a flowchart illustrating the operation of the exemplary embodiment of the present invention.

FIG. 5 is a flowchart illustrating the operation of the embodiment of the present invention.

FIG. 6 is a side view of a probe and an object to be inspected.

FIG. 7 is a waveform diagram of an ultrasonic reflected signal.

FIG. 8 is a waveform diagram of an ultrasonic reflection signal.

[Explanation of symbols]

 1 inspected object 2 probe 3 transmitter 4 receiver 6 waveform memory 10 CPU 13 keyboard input unit 14 liquid crystal display unit 15 display unit controller

Claims (3)

[Claims] 1. A transmitting unit that outputs a pulse for exciting a probe, a receiving unit that receives an ultrasonic wave reflected signal from the probe, and a signal receiving unit that receives a signal based on the signal received by the receiving unit. A super unit including a display unit for displaying a waveform, a gate unit for setting an arbitrary time range after the pulse output, and a maximum value detecting unit for detecting a maximum value among signals existing in the selected time range. In the ultrasonic flaw detector, a predetermined reference signal of the ultrasonic reflected signal is taken out, and other gate means in which a predetermined level with respect to the maximum level that can be displayed on the display unit is determined for this reference signal, First computing means for computing a deviation between the reference signal and the predetermined level, second computing means for computing a gain deviation corresponding to the calculated deviation, and based on the calculated gain deviation And a gain adjusting means for adjusting the gain of the receiving section. 2. The gain control device for an ultrasonic flaw detector according to claim 1, wherein the reference signal is a bottom surface reflected wave signal included in the ultrasonic reflected signal. 3. The gain control device for an ultrasonic flaw detector according to claim 1, wherein the reference signal is a surface reflected wave signal included in the ultrasonic reflected signal.