JP2003294715A - Ultrasonic flaw detecting device and ultrasonic flaw detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detecting device which can detect a flaw just under the surface of an object to be examined. <P>SOLUTION: The ultrasonic flaw detecting device is provided with a receiving circuit part which receives a reflected wave reflected from an object to be examined, a first comparing circuit 32a which has the first threshold having a higher value than a negative peak of an echo of a flaw to be examined and outputs a signal when the value of the reflected wave received by the receiving circuit part is smaller than the first threshold, a second comparing circuit 32b which has the second threshold having a smaller value than a negative peak of an echo of a flaw to be examined and outputs a signal when the value of the reflected wave received by the receiving circuit part is smaller than the second threshold, and a logical circuit part which outputs a signal obtained by an exclusive OR of the output from the first comparing circuit and the output from the second comparing circuit. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention reliably detects a defect inside an object to be inspected, particularly a defect immediately below the surface or just below the bottom surface (hereinafter, also referred to as just below the surface) of the object to be inspected, using ultrasonic waves. The present invention relates to an ultrasonic flaw detector and an ultrasonic flaw detector method.

[0002]

2. Description of the Related Art Ultrasonic flaw detectors emit ultrasonic waves from a probe to an object to be inspected and detect a reflected wave (echo) reflected and returned by the object to be inspected. Inspect for internal defects. FIG. 6 is a schematic diagram for explaining a probe method of the ultrasonic flaw detector. In FIG. 6, 10 is a probe, 11 is a flat plate-shaped object to be inspected, 12
Is a defect inside the inspection object. Note that, in FIG. 6, circled numbers indicate ultrasonic wave paths. FIG. 7A is a diagram showing a pattern of a reflected wave from the object to be inspected, FIG. 7B is a diagram showing a waveform of a delay pulse, and FIG. 7C is a diagram showing a waveform of a gate signal. Further, in FIG. 7, T is an ultrasonic pulse, S is a surface echo, F is a defect echo, and B is a bottom echo.
The waveform of the reflected wave shown in FIG. 7 is a full-wave rectified reflected wave.

When the ultrasonic pulse T is emitted from the probe 10, the surface echo S reflected by the surface of the object 11 to be inspected first returns. Next, if there is no defect inside the inspection object 11, the bottom surface echo B reflected on the bottom surface returns.
On the other hand, if there is a defect 12 inside the inspection object 11, the defect echo F reflected by the defect 12 returns.
As a method for identifying the defect echo F from the plurality of waveforms thus received, the conventional ultrasonic flaw detector employs the following method. First, after the ultrasonic pulse, a surface echo is detected by detecting a waveform having a magnitude exceeding a certain threshold. Since this surface echo is large and has a width, the delay pulse shown in FIG. 7 is generated from the time when the surface echo is detected, and the delay pulse is slightly delayed by this delay pulse to be a region for searching for a defect echo (FIG. 7C).
Since the gate signal shown in (1) is generated (ON) and the plate thickness of the inspection object is known in advance, the gate signal is cut off (OFF) just before the bottom surface echo. Within the period in which the gate is open (the period in which the gate signal is in the ON state), a waveform equal to or greater than a certain threshold is detected as a defect echo, thereby detecting a defect inside the inspection object.

[0004]

However, in the ultrasonic flaw detector, the surface echo is not obtained as one large echo, but a plurality of echoes reflected from various points of the object to be inspected are superposed. Obtained as. Further, some ultrasonic flaw detectors use the concave probe shown in FIG. 6 in order to improve the detectability of defects. When using such a concave probe,
The surface echo of the ultrasonic wave emitted from the central part of the probe and the surface echo of the ultrasonic wave emitted from the peripheral part of the probe are different, and therefore the concave probe of FIG. 6 is used. In this case, echoes that have passed through various paths are received as surface echoes, and the surface echoes have a plurality of peaks and a wide width. Further, even when the state of the surface of the inspection object is not uniform, the surface echo has a plurality of peaks and a wide width. Thus, when a concave probe is used, or when the surface of the inspection object is not uniform, the surface echo has a plurality of peaks and a wide width. When the surface echo has a plurality of peaks as described above, if the surface echo is detected using the threshold value, the echo may be detected as the surface echo, and the position of the surface echo may deviate from the original position of the surface echo.

Further, in order to accurately detect the internal defect of the inspection object, it is necessary to make the width of the gate as close as possible to the plate thickness of the inspection object. However, if the width of the gate is widened, the width of the gate is fixed when the detection timing of the surface coe is deviated and delayed as described above. Therefore, the width of the gate is deviated in the right direction of FIG. 7 as a whole. The bottom echo may be determined to be a defect echo. On the contrary, if the detection quimming of the surface echo shifts and becomes faster, the width of the gate shifts to the left in FIG. 7, and it becomes impossible to detect a defect near the bottom surface. As described above, in the conventional device, when the detection of the surface echo is not stable, the gate signal is not stable, and therefore the bottom surface echo may be erroneously detected as a defect echo, and the defect immediately below the bottom surface of the inspection object is accurately detected. There was a problem that it could not be detected.

The present invention has been made under the above circumstances, and an object thereof is to provide an ultrasonic flaw detector and an ultrasonic flaw detection method capable of reliably detecting a defect immediately below the surface of an object to be inspected. It is what

[0007]

In order to achieve the above object, an ultrasonic flaw detector according to a first aspect of the present invention includes a transmitter for emitting ultrasonic waves from a probe to an object to be inspected, and an object to be inspected. In an ultrasonic flaw detector including a receiving unit that receives a reflected wave from the detection unit and detects a defect inside the inspected object, the receiving unit includes a receiving circuit unit that receives the reflected wave reflected by the inspected object, The first threshold value is set on the negative region side and has a first threshold value set to a value higher than the negative peak of the defect echo to be detected, and the value of the reflected wave received by the receiving circuit means and the first threshold value. And a signal that is output when the value of the reflected wave is lower than the first threshold by comparing
A comparing means; and a second threshold value set on the minus region side and having a value lower than the minus peak of the defect echo to be detected, the value of the reflected wave received by the receiving circuit means, and A second threshold that compares with a second threshold and outputs a signal when the value of the reflected wave is lower than the second threshold
Comparing means and logic means for outputting a signal by taking the exclusive OR of the output value of the first comparing means and the output value of the second comparing means, and based on the output signal of the logic means. The feature is that a defect echo is detected.

An ultrasonic flaw detector according to a second aspect of the present invention for achieving the above object is a transmitter for emitting ultrasonic waves from a probe to an object to be inspected, and a reflected wave from the object to be inspected. Then, in the ultrasonic flaw detector comprising a receiving unit for detecting a defect inside the inspection object, the receiving unit, a receiving circuit means for receiving a reflected wave reflected by the inspection object, and on the plus region side, and The first threshold value is set lower than the positive peak of the defect echo to be detected, and the value of the reflected wave received by the receiving circuit means and the first threshold value.
A first comparing means for comparing a threshold value and outputting a signal when the value of the reflected wave is higher than the first threshold value, and a peak on the plus region side and on the plus side of the defect echo to be detected. A second threshold value set to a value, the value of the reflected wave received by the receiving circuit means is compared with the second threshold value, and a signal is output when the value of the reflected wave is higher than the second threshold value. The second comparison means for outputting, and the logic means for outputting a signal by taking the exclusive OR of the output value of the first comparison means and the output value of the second comparison means, and the output of the logic means. The feature is that a defect echo is detected based on the signal.

An ultrasonic flaw detector according to a third aspect of the present invention for achieving the above object is the gate according to the first or second aspect of the invention, further provided with a surface echo or a specific time as a reference. A detection unit that detects an echo higher than a preset threshold value as a defective echo within the ON period of the signal, and an OR unit that ORs the output value of the logic unit and the output value of the detection unit. However, the defect echo is detected based on the output signal of the OR means. An ultrasonic flaw detection method according to a fourth aspect of the present invention for achieving the above object is a transmitting step of emitting an ultrasonic wave from a probe to an object to be inspected, and receiving a reflected wave from the object to be inspected. In the ultrasonic flaw detection method comprising a receiving step of detecting a defect inside the inspection body, the receiving step,
Receiving a reflected wave reflected by the object to be inspected,
The first threshold is set on the negative region side and has a first threshold value set to a value higher than the negative peak of the defect echo to be detected, and the value of the reflected wave received by the receiving step and the first threshold value. A first comparing step of outputting a signal when the value of the reflected wave is lower than the first threshold by comparing
The second threshold value is set on the negative region side and has a second threshold value set to a value lower than the negative peak of the defect echo to be detected, and the value of the reflected wave received by the receiving step and the second threshold value. And a second comparing step of outputting a signal when the value of the reflected wave is lower than the second threshold value,
A logic step of outputting a signal by taking the exclusive OR of the output value of the first comparing step and the output value of the second comparing step;
And detecting a defect echo based on the output signal of the logic step.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION [Configuration of First Embodiment]
An ultrasonic flaw detector according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a flaw detection unit of the ultrasonic flaw detection apparatus according to the present embodiment. Note that in FIG. 1, those having the same functions as those shown in FIG.
By giving the same reference numerals, detailed description thereof will be omitted.

As shown in FIG. 1, the probe 1 of the present embodiment.
0 and the inspection object 11 are immersed in the water in the tank 15 (water immersion method). Further, the probe 10 of the present embodiment has a concave shape shown in FIG. Although the probe 10 and the device under test 11 are immersed in water in the present embodiment, the present invention is not limited to water, and other liquids such as oil may be used.

The ultrasonic flaw detector of the present embodiment is provided with a probe 1.
The transmitting unit emits an ultrasonic pulse from 0 to the inspected object and the receiving unit that receives a reflected wave reflected from the inspected object and detects a defect inside the inspected object. FIG. 2 is a schematic control block diagram of the ultrasonic flaw detector according to the present embodiment. As shown in FIG. 2, the reception unit of the present embodiment includes a reception circuit unit 31 that detects a reflected wave of an ultrasonic pulse emitted to the inspection object 11 by the transmission unit 20, and a reflection circuit received by the reception circuit unit 31. A comparison unit 3 that compares and processes the value of the reflected wave and a preset threshold value with respect to the wave and outputs a signal indicating the result.
2 and the signal of the reflected wave received by the receiving circuit unit 31 and the signal detected by the comparison unit 32, the peak signal of the reflected wave is calculated, and the position and size of the defect are calculated based on the peak signal. And a defect calculator 33 that

FIG. 3 is a circuit diagram of the comparison section 32. Figure 4
(A) is a figure which shows the waveform of the reflected wave from a to-be-inspected object, (b)
Is a diagram showing a waveform of an output signal of the first comparison circuit section 32a,
(C) is a figure which shows the waveform of the output signal of the 2nd comparison circuit part 32b, (d) is a figure which shows the output signal of the logic circuit part 32c. The waveform of the ultrasonic pulse is omitted in FIG. Further, in FIG. 4A, the peak portions of the surface echo S and the bottom surface echo B are flat, but this is much larger than the defect echo of the surface echo and the bottom surface echo. This is because the top of is omitted.

As shown in FIG. 3, the comparison section 32 has a first comparison circuit section 32a having a first threshold value which is a high threshold value set on the minus area side, and a low threshold value set on the minus area side. Second comparison circuit section 32b having a certain second threshold
And the output value of the first comparison circuit section 32a and the second comparison circuit section 3
2b, and a logic circuit section 32c that takes an exclusive OR (hereinafter, also referred to as EXOR) with the output value of 2b. The first comparison circuit unit 32a compares the value of the reflected wave with a preset first threshold value, and outputs a signal indicating whether the value is larger or smaller than the first threshold value. Since the first threshold value of the first comparison circuit of the present embodiment is set to the negative region side, it is slightly larger than the negative peak value of the defect echo depending on the size of the defect echo to be detected. It is set to a value that does not detect negative noise. The second comparison circuit unit 32b also compares the value of the reflected wave with a preset second threshold value, and outputs a signal indicating whether the value is larger or smaller than the second threshold value. Second
Since the second threshold value of the comparison circuit unit 32b is also set to the negative region side, it is smaller than the negative peak value of the defect echo to be detected and higher than the negative peak value of the bottom echo. Is set.

In this embodiment, the first threshold value and the second threshold value
Although the case where the threshold value is set to the minus area side has been described, the first threshold value and the second threshold value may be set to the plus area side. When the first threshold value is set to the plus side, the first comparison circuit unit compares the value of the reflected wave with a preset first threshold value and outputs a signal indicating whether the value is larger or smaller than the first threshold value. To do. Since the first threshold value of the first comparison circuit in this case is set to the plus region side, it is slightly smaller than the plus side peak value of the defect echo and plus depending on the size of the defect echo to be detected. It is set to a value that does not detect noise on the side. When the second threshold value is set to the plus side, the second threshold value of the second comparison circuit unit is larger than the plus side peak value of the defect echo to be detected, and the bottom side echo plus side peak value. Set to a lower value.

In the above embodiment, the case where the defect is detected based on the reflected wave received by the receiving circuit section has been described. However, the present invention is based on the waveform after the full wave rectification of the reflected wave. May be detected.

The transmitting section 20 is similar to that of the conventional apparatus, and its detailed description is omitted.

[Operation of First Embodiment] Next, the operation of the ultrasonic flaw detector according to the present embodiment will be described. Transmitter 20
When an ultrasonic pulse is emitted from the probe 10 to the device under test 11 through the probe 10, the receiving circuit 31 of the receiving unit 30 causes the probe 1 to move.
The reflected wave is received via 0 and amplified. The received reflected wave includes a surface echo S reflected on the surface of the inspection object and a bottom echo B reflected on the bottom surface of the inspection object as shown in FIG. Further, if there is a defect inside the inspection object, the reflected wave also includes a defect echo F. Receiver circuit section 3
The waveforms of the surface echo S, the bottom surface echo B, the defect echo F, and the like received and amplified by 1 are sent to the first comparison circuit unit 32a and the second comparison circuit unit 32b of the comparison unit 32.

In the first comparison circuit section 32a, the value of the input reflected wave is compared with a predetermined first threshold value H, and when the value of the reflected wave is smaller than the first threshold value H, the output signal is low. A signal is emitted, and when it is large, a high signal (zero signal) is emitted as an output signal. The first comparison circuit section 3
2a compares the input reflected wave value with a predetermined first threshold value H, emits a high signal as an output signal when the reflected wave value is smaller than the first threshold value H, and outputs it as an output signal when it is larger. It may be one that emits a low signal. The same applies to the second comparison circuit unit described later. The comparison unit 32 is shown in FIG.
When the reflected wave shown in (a) is received, the output waveform of the first comparison circuit section 32a falls when the value of the reflected wave becomes smaller than the first threshold value H, as shown in (b) of the figure. , Becomes a waveform that rises when it becomes larger than the first threshold value H.

In the second comparison circuit section 32b, the value of the input reflected wave is compared with a predetermined second threshold L, and when the value of the reflected wave is smaller than the first threshold L, the output signal is output. As a low signal, and when high, a high signal (zero signal) as an output signal. The comparison unit 32 is shown in FIG.
When the reflected wave shown in (a) is received, the output waveform of the second comparison circuit section 32b falls when the value of the reflected wave becomes smaller than the second threshold value L, as shown in (c) of the figure. , Becomes a waveform that rises when it becomes larger than the second threshold value L. The logic circuit unit 32c outputs the signal output from the first comparison circuit unit 32a shown in FIG. 4B and the second comparison circuit unit 3
Upon receipt of the signal shown in FIG. 2C, which is the output value of 2b, the exclusive OR of the two signals is calculated, and the signal indicating the result, that is, the signal shown in FIG. By taking the exclusive OR of the output value of the first comparison circuit unit and the output value of the second comparison circuit unit, it is possible to detect the signal corresponding to the defect echo immediately below the bottom surface shown in FIG. 4A. .

By the way, the logic circuit section 32c detects the echoes as defect echoes and outputs them when the rising and falling waveforms of the front surface echo and the bottom surface echo are not vertical but slightly inclined. The signal goes low. However, the output signal when the logic circuit detects such a surface echo or bottom echo is much larger than the defect echo when the surface echo or bottom echo is detected. Then, the width of the low signal when the surface echo or the bottom echo is detected becomes extremely narrow. Therefore, among the low output signals of the logic circuit section 32c, only those having a predetermined constant width may be output as the detection signal of the defect echo. After the detected echoes, the process of selecting only those having a predetermined width is performed by the comparison unit 3
2 may be performed, or the defect calculation unit 33 may be performed.

The defect calculating section 33 calculates the defect echo by referring to the original reflected wave received by the receiving circuit section based on the signal corresponding to the defect echo detected by the comparing section 32, and calculates the defect echo. Based on this, the position and size of the defect inside the inspection object are calculated. When calculating the position of the defect echo, the peak of the corresponding defect echo is obtained from the received reflected waves based on the signal corresponding to the defect echo detected by the comparison unit 32. For example, from the surface echo (or bottom echo) If the time to the peak of the defect echo is t and the sound velocity is v, the distance from the surface (or bottom surface) of the object 11 to be inspected to the defect can be obtained by the equation d = v × t / 2. The distance to such a defect may be calculated by performing parallel processing on the basis of an analog signal, or the reflected wave received by the receiving circuit unit 31 may be converted into digital data, and the digital data may be calculated. May be stored in a waveform memory (not shown) and the data of the stored waveform memory may be used for calculation.

In the above embodiment, the case of detecting the defect just below the bottom surface has been described. However, when detecting the defect just below the surface, the inspection object is turned upside down or the probe. 10 is arranged on the bottom surface side of the inspection object, and ultrasonic waves are emitted from the bottom surface side of the inspection object to perform the inspection.

[Effects of the First Embodiment] According to the present embodiment, a defect immediately below the bottom surface can be stably detected without being affected by the bottom surface echo or the variation of the plate thickness. Also,
According to the present embodiment described above, the gate circuit used in the conventional device becomes unnecessary.

Further, according to this embodiment, it is possible to improve the yield in the steel plate manufacturing process. That is,
In the steel sheet manufacturing process, if there is a defect just below the surface of the material, the defect becomes a surface defect when rolled in the rolling process, and the work in each processing process is completely wasted, and the product becomes a defective product. . Therefore, in the steel plate manufacturing process, there is a demand to find defects immediately below the surface at the earliest possible stage and to eliminate unnecessary work in the manufacturing process as much as possible. In such a case, by using the present embodiment, it is possible to reliably detect a defect immediately below the surface of the raw material and improve the yield in the steel plate manufacturing process.

In the above embodiment, the method of selecting the surface echo (or the bottom surface echo) detected by the comparison unit and the defect echo based on the width of the output signal of the comparison unit has been described. , But is not limited to this. For example, a gate signal may be created in a range in which the surface echo and the bottom echo do not enter, and the output signal of the comparison unit may be taken out within the period in which the gate signal is on.
Thereby, it is possible to reliably prevent the surface echo and the bottom echo from being detected as defect echoes. Further, when the gate signal is created, the present inventor does not create it based on the surface echo,
As disclosed in No. 3, the gate signal can be easily and accurately created by using the bottom echo. Further, even when the defective echo is selected based on the width of the detected echo, the echo may be detected using the gate signal only within the period of the gate signal.

Further, in the above embodiment, the case where the threshold values of the first comparison circuit section and the second comparison circuit section are set to the minus region side has been described, but the threshold values of the first comparison circuit section and the second comparison circuit section are described. May be set to the plus area side.

[Second Embodiment] FIG. 5 shows a second embodiment of the present invention.
It is a schematic block diagram of the receiving part of the ultrasonic flaw detector of the embodiment. The present embodiment is different from the first embodiment only in the receiving section, and the other parts are the same as those in the first embodiment. Therefore, in the present embodiment, in order to simplify the description, detailed description of parts other than the receiving unit is omitted. Further, among the receiving units 300 of the present embodiment, those having the same functions as those of the receiving unit 30 of the first embodiment will be denoted by the same reference numerals or corresponding reference numerals, and detailed description thereof will be omitted.

The receiving unit 300 of this embodiment is the transmitting unit 20.
The receiving circuit unit 31 for detecting the reflected wave of the ultrasonic pulse emitted to the inspection object 11 by the and the reflected wave received by the receiving circuit unit 31 have defects similar to those in the comparison unit of the first embodiment. A comparison unit 32 that detects and outputs a signal indicating the result, a detection unit 302 that detects a reflected wave by a method similar to that of a conventional device, and that issues a low signal or a high signal indicating the detection, and a comparison unit. An OR circuit 3 that outputs a signal by ORing the output value of 32 and the output value of the detection unit 302.
03 and a defect calculator 33 that calculates a defect based on the output signal of the OR circuit 303.

As described above, the comparison unit 32 of this embodiment.
Has a function similar to that of the comparison unit 32 of the first embodiment, and detailed description thereof will be omitted. Further, the detection unit 302 detects a defect by a method similar to that of the conventional device. That is, the detection unit 302 creates a gate signal based on a surface echo or the like, detects a defect echo within the period of the created gate signal, and emits a low signal when the defect echo is detected. In the present embodiment, a normally considered defect is detected by the comparison unit 32 as in the first embodiment. However, if the comparison unit 32 of the present embodiment selects and outputs only the detected output signal having a large width without using a gate signal, for example, the detected defect echo may be a surface echo or a surface echo. If the echo is as large as the bottom echo, the detection signal of such a large defect echo cannot be detected because its width is extremely small. In such a case, the detection unit 302 detects such a large defect echo by a method substantially similar to that of the conventional device. Therefore, the threshold value of the detection unit 302 is set to be larger than the threshold value of the comparison unit 32 when set to the plus side, and is set to be smaller than the threshold value of the comparison unit 32 when set to the minus side. . Also,
In the present embodiment, the comparison unit 32 can detect a defect immediately below the bottom surface, and therefore the period of the gate signal of the inspection unit 302 does not have to be strict.

The OR circuit unit 303 obtains the output value of the comparison unit 32 and the output value of the inspection unit 302, takes the logical sum of the two, and detects the defect if either one of the output values is low. A signal to that effect is sent to the defect calculator 33. Defect calculation unit 33
Calculates the defect echo, the position and size of the defect, etc. by the same method as in the first embodiment based on the output signal of the OR circuit unit.

According to the second embodiment described above, the comparison unit 32
Detects the defect echo inside the inspected object with certainty, even if the output signal is selected as the signal corresponding to the defect echo without selecting the gate signal and only the detected output signal with a large width is selected. can do. In addition, the present embodiment has the same actions and effects as the actions and effects of the first embodiment.

[Other Embodiments] The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example,
The present invention is not limited to the water immersion method of the above-described embodiment, the probe is slightly floated from the object to be inspected by using a holder or the like, and oil or the like is kept between the probe and the object to be inspected. It is also possible to make them contact with each other via a contact medium. Also,
The present invention can also be used for a so-called two-division type contactor method (two-probe method) in which two probes are provided separately for a transmitting probe and a receiving probe. .

[0034]

As described above, according to the present invention, a defect immediately below the surface of the object to be inspected can be detected stably without being affected by the disturbance of the surface echo or the variation of the plate thickness of the object to be inspected. It is possible to provide an ultrasonic flaw detection device and an ultrasonic flaw detection method that can be performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a flaw detection unit of an ultrasonic flaw detection apparatus according to an embodiment.

FIG. 2 is a schematic control block diagram of the present embodiment.

FIG. 3 is a circuit diagram of a comparison unit 32.

4A is a diagram showing a waveform of a reflected wave from an object to be inspected, FIG. 4B is a diagram showing a waveform of an output signal of the first comparison circuit unit 32a, and FIG. 4C is a second comparison circuit unit 32b. 2D is a diagram showing the waveform of the output signal of FIG.

FIG. 5 is a schematic block diagram of a receiver of the ultrasonic flaw detector according to the second embodiment of the present invention.

FIG. 6 is a schematic diagram for explaining a probe method of a conventional ultrasonic flaw detector.

FIG. 7 is a diagram showing a pattern of a reflected wave from an object to be inspected, a delay pulse, and a gate signal in a conventional ultrasonic flaw detector.

[Explanation of symbols]

10: probe, 11: object to be inspected, 12: defect, 15: tank, 20: transmitter, 30: receiver, 31: receiver circuit, 32: comparator, 33:
Defect calculation unit, 32a: First comparison circuit unit, 32b:
2nd comparison circuit part, 32c: Logic circuit part, 30
0: reception unit, 302: inspection unit, 303: OR circuit unit

Claims (4)

[Claims] 1. An ultrasonic flaw detector comprising: a transmitter that emits ultrasonic waves from a probe to an object to be inspected; and a receiver that receives a reflected wave from the object to be inspected and detects a defect inside the object to be inspected. In the apparatus, the receiving unit is set to a value higher than a negative side peak of a defect echo to be detected and a receiving circuit means for receiving a reflected wave reflected by an object to be inspected. A first comparison having a first threshold value, comparing the value of the reflected wave received by the receiving circuit means with the first threshold value, and outputting a signal when the value of the reflected wave is lower than the first threshold value. Means and a second threshold value set on the minus region side and lower than the minus peak of the defect echo to be detected, and the value of the reflected wave received by the receiving circuit means; The above-mentioned reflection by comparing with two thresholds Of the second comparison means for outputting a signal when the value of is lower than the second threshold value, and the output value of the first comparison means and the output value of the second comparison means are exclusive-ORed to output the signal. The ultrasonic flaw detection device is characterized in that a defect echo is detected based on an output signal of the logic means. 2. An ultrasonic flaw detector comprising: a transmitter that emits ultrasonic waves from a probe to an object to be inspected; and a receiver that receives a reflected wave from the object to be inspected and detects a defect inside the object to be inspected. In the device, the receiving section is set to a receiving circuit means for receiving a reflected wave reflected by the object to be inspected, a plus region side, and a peak lower than the plus side peak of the defect echo to be detected. First comparing means having one threshold value and comparing the value of the reflected wave received by the receiving circuit means with the first threshold value and outputting a signal when the value of the reflected wave is higher than the first threshold value. And a second threshold value set on the plus region side and having a value higher than the peak on the plus side of the defect echo to be detected, and the value of the reflected wave received by the receiving circuit means; The value of the reflected wave is compared with the threshold value Second outputting a signal when higher than the second threshold value
Comparing means and logic means for outputting a signal by taking the exclusive OR of the output value of the first comparing means and the output value of the second comparing means, and based on the output signal of the logic means. An ultrasonic flaw detector characterized by detecting a defect echo. 3. A detection means for detecting an echo higher than a preset threshold value as a defect echo within an ON period of a surface echo or a gate signal provided with reference to a specific time.
3. A logical sum means for taking a logical sum of the output value of the logic means and the output value of the detection means, and a defect echo is detected based on the output signal of the logical sum means. Alternatively, the ultrasonic flaw detector according to item 2. 4. An ultrasonic flaw detection comprising: a transmitting step of emitting ultrasonic waves from a probe to an object to be inspected; and a receiving step of receiving a reflected wave from the object to be inspected to detect a defect inside the object to be inspected. In the method, the receiving step includes a step of receiving a reflected wave reflected by an object to be inspected, and a first value set to a negative region side and a value higher than a negative side peak of a defect echo to be detected. A first comparison step having a threshold value, comparing the value of the reflected wave received by the receiving step with the first threshold value, and outputting a signal when the value of the reflected wave is lower than the first threshold value; A second threshold value set on the negative region side and lower than the negative peak of the defect echo to be detected, the value of the reflected wave received by the receiving step, and the second threshold value. Compared with the reflected wave A second comparison step of outputting a signal when the value is less than the second threshold value, wherein an output value of the first comparison step second
And a logic step of outputting a signal by taking an exclusive OR with the output value of the comparison step, and detecting a defect echo based on the output signal of the logic step.