JPH0862192A - Ultrasonic flaw detection apparatus and flaw judgement method - Google Patents

Abstract

PURPOSE: To provide an ultrasonic flaw detection apparatus and a flaw judgement method which nearly eliminate an uninspected region and which can automatically detect a flaw in a material to be inspected/without using a test material which contains an artificial flaw. CONSTITUTION: In a gate part 21, a point after a definite time from the rise of outer- surface echoes in a reflected echo signal is used as a gate starting point, a gate signal which can gate inner-surface echoes is generated, and the reflected echo signal is gated. The frequency component of an amplitude change in the output signal of a peak hold part 17 is divided into the frequency component fC of an amplitude change due to the rotation of a material 4 to be inspected and into the frequency component fF of an amplitude change generated at a time when ultrasonic waves propagated inside the material 4 to be inspected are masked by a flaw. A gain-variable amplification part 24 almost removes an amplitude change portion due to the rotation of the material 4 to be inspected of the output signal of the peak hold part 17 so as to be output. A high-pass filter 25 sufficiently attenuates and removes the frequency component fC in an input signal, and it outputs only the frequency component almost which is generated at a time when the flaw is masked and whose amplitude change is high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flaw detector and a flaw determination method, and more particularly, to a flaw due to attenuation of an ultrasonic wave incident perpendicularly to the surface of a material to be inspected such as a steel material or a composite material. The present invention relates to an ultrasonic flaw detector for inspecting defects and a flaw determination method.

[0002]

2. Description of the Related Art Conventionally, for ultrasonic flaw detection of metallic materials,
The bevel flaw detection method and the vertical flaw detection method are used, and in particular, only the bevel flaw detection method is often used for a flaw inspection of a steel pipe. However, the bevel flaw detection method detects cracks on the inner and outer surfaces of the steel pipe, but it does not have enough ability to detect flaws inside the steel pipe (portions other than the vicinity of the inner and outer surfaces). To do this, a vertical flaw detection method is used.

In this vertical flaw detection method, as shown in the schematic view of FIG. 5, from a probe 3 connected to an ultrasonic flaw detector 1 through a coaxial cable 2, a material to be inspected (for example, a steel pipe) 4
The ultrasonic flaw detector 1 receives the ultrasonic wave perpendicularly to the surface of the test object 4 from the reflected echo signal received by the probe 3 from the test object 4 The surface 4
The position and size of the flaw 5 existing inside from a to the inner surface 4b are detected.

FIG. 6 shows a block diagram of an example of a conventional ultrasonic flaw detector used as the ultrasonic flaw detector 1. In the figure, the ultrasonic flaw detector 10 is connected to the probe 3 via the coaxial cable 2 as in FIG. A medium (usually water) for propagating ultrasonic waves and a mechanism portion for holding the relative positional relationship between the probe and the inspection material are required between the probe 3 and the inspection material 4. However, the description is omitted.

The ultrasonic flaw detector 10 includes a synchronizing signal oscillator 1
1, a transmission unit 12, a reception unit 13, a sweep wave generation unit 14, a display unit 15, a gate unit 16, a peak hold unit 17, an alarm unit 18, and a recording output unit 19. The synchronization signal oscillator 11 oscillates a synchronization signal that activates the operation of each part of the pulse ultrasonic flaw detector 10.

The transmitter 12 receives the synchronizing signal a shown in FIG. 7A, which is oscillated and output from the synchronizing signal oscillator 11, and
A pulse with a large amplitude and a short time width is generated, this pulse is output to the probe 3 via the coaxial cable 2, and this is excited. As a result, the probe 3 emits an ultrasonic wave, which is vertically incident on the material 4 to be inspected.

The receiving section 13 receives an echo signal obtained by converting the ultrasonic echo received by the probe 3 from the inspection object 4 into an electric signal and amplifies it. The components of the receiving unit 13 detect an amplifier for amplifying an echo signal, an attenuator for setting the sensitivity of the ultrasonic flaw detector 10 and an envelope of an AC waveform that is an output of the attenuator, and output a DC detection signal. Although it is a detector, these are not shown.

The sweep wave generator 14 includes a synchronization signal oscillator 11
In response to the synchronization signal a output from the receiver, a sweep signal necessary for displaying the output signal of the receiver 13 on the display unit 15 described below is generated. The display unit 15 is a device that displays the output signal of the receiving unit 13, and is, for example, a cathode ray tube (CR).
T), a vertical deflection circuit that amplifies the output of the receiver 13 to the amplitude and DC potential required for CRT display, and the sweep wave generator 14
It is composed of a horizontal deflection circuit that amplifies the output sweep wave of (1) to the amplitude and DC potential required for CRT display, a brightness and focus adjustment circuit, and the like.

The gate section 16 generates an echo necessary for the purpose of flaw detection among the echo signals received by the probe 3 and amplified and output by the receiving section 13 based on the synchronizing signal a.
It is selected and output based on the gate signal shown in (C).
The gate unit 16 includes a circuit capable of setting the starting point and the width of the echo-gating range with the echo from the surface of the inspected material 4 among the echo signals as a reference time point. FIG. 7B shows an output signal of the gate unit 16 which is a flaw echo. It should be noted that this flaw echo is not always received and is rarely received and output.

The peak hold unit 17 is a circuit for holding a signal having a voltage value proportional to the maximum amplitude value of the flaw echo output by the gate unit 16 until the echo reception in the next cycle. Therefore, this peak hold unit 17
From, the maximum amplitude value of the output flaw echo of the gate unit 16 is
When it is A1 as shown in FIG. 7 (B), as shown in FIG. 7 (D), a voltage having a value of A2 proportional to it is output.

The alarm unit 18 generates and outputs an alarm signal when the amplitude of the flaw echo gate-output from the gate unit 16 exceeds a predetermined alarm level. This alarm level can be adjusted according to the purpose of flaw detection. If necessary, the setting can be changed so that an alarm signal is output when the amplitude of the flaw echo gate-output from the gate unit 16 becomes smaller than a preset alarm level.

The recording output unit 19 is a peak hold unit 17.
Output signal is converted into a recording signal suitable for use in a recording device such as a recorder to be used and then output.

[0013]

However, the above-mentioned conventional ultrasonic flaw detector has a problem that uninspected regions are formed in the portion immediately below the outer surface of the material 4 to be inspected and on the bottom surface side. This point will be described in more detail. The transmitter 12 receives the synchronization signal a from the synchronization signal oscillator 11 shown in FIG.
The same signal as the synchronizing signal a in FIG. 7A is received as an input signal, and a large amplitude pulse shown in FIG. 8B is generated to excite the probe 3.

As a result, the probe 3 transmits an ultrasonic wave, enters the material 4 to be inspected vertically, receives an ultrasonic echo reflected from the material 4 to be inspected, and converts it into an electric signal. The echo signal is input to the receiving unit 13. As a result, the echo signal shown in FIG. 8C is output from the receiver 13.

Here, in FIG. 8C, T is a pulse obtained by amplifying the output pulse of the transmitter 12, and is a transmission wave having a relatively wide time width. S is a reflected wave at the boundary between the ultrasonic wave propagating medium (usually water) and the outer surface of the material 4 to be inspected, and is called an outer surface echo or S wave. F is an echo received when there is a flaw in the ultrasonic wave propagation path in the inspected material 4, and is a flaw echo. Further, B is a reflected wave from the inner surface of the material 4 to be inspected, which is called an inner surface echo or B wave.

Therefore, the gate section 16 of the conventional ultrasonic flaw detector 10 sets the starting point of the gate after a fixed time elapses from the rising edge of the synchronizing signal a, and outputs the reflected echo signal from the receiving section 13 shown in FIG. 8C. A gate signal is generated so as to output the flaw echo F of FIG.

If the material 4 to be inspected is a steel pipe and an attempt is made to detect flaws on the entire surface (in the circumferential and axial directions), one of the probe 3 and the material to be inspected (steel pipe) 4 is rotated. Moreover, it is necessary to fix the other and convey the inspected material 4 in the axial direction. Therefore, at that time, vibrations in the diametrical direction and the eccentric direction of the inspected material 4 are generated to some extent due to the outer diameter dimension variation and deformation of the inspected material.
The outer surface 4a of the probe 3 and the inspection object 4 shown by LW in FIG.
The distance and the angle of incidence fluctuate and the magnitude of the S wave fluctuates. In addition, the magnitude of the S wave varies depending on the unevenness of the material surface.

In setting the gate of the gate section 16 described above,
Even if the size and width of the S wave are maximized, the setting is made as shown in FIG. 8D so that the S wave does not enter the gate. Therefore, when the distance LW becomes shorter and the S wave approaches the T wave, the time between the rising point of the S wave and the rising point of the gate signal becomes wider, and the flaw echo F received during that time can be output to the gate. Can not. That is, the flaw detection range immediately below the outer surface is expanded. Immediately below this outer surface, the area where flaw detection is not possible is the probe 3
The lower the frequency, the greater the frequency. Naturally, it is theoretically difficult to detect the flaw echo F which is located immediately below the outer surface and is included in the S wave.

By the way, in the case where the material 4 to be inspected is a seamless (seamless) steel pipe, since the center of the outer surface circle and the center of the inner surface circle do not match (uneven thickness) to some extent, the steel pipe at the time of flaw detection With rotation, the thickness indicated by t in FIG. 5 changes. Therefore, conventionally, the gate width is set so that the inner surface echo B does not enter the gate of the gate portion 16 even when the thickness t is minimum.

Therefore, as the thickness t increases, the time from the gate end point to the rising point of the inner surface echo B increases. That is, in this case, it is not possible to detect a flaw near the inner surface (bottom surface) of the material 4 to be inspected, which is represented by a flaw echo generated within the time from the gate end point to the rising point of the inner surface echo B.

Further, conventionally, a test material obtained by processing an artificial flaw is necessary for adjusting the gate, and it is necessary to insert the test material into an inspection device including the ultrasonic flaw detector 10. , Has become a big problem in automation of the device.

On the other hand, as a flaw determination method of the conventional vertical flaw detection method, there is a method of determining the decrease of the echo B on the inner surface. This method is a method of determining the size of a flaw because the amplitude of the inner surface echo B decreases if a flaw is present during the propagation of ultrasonic waves. However, in this conventional method, it is difficult to automatically determine the flaw because the amplitude of the inner surface echo B changes due to the eccentricity of the material in the automatic inspection.

The present invention has been made in view of the above points, and an ultrasonic wave capable of almost completely eliminating an uninspected region and automatically detecting flaws in a material to be inspected without using a test material having an artificial flaw. It is an object to provide a flaw detection device and a flaw determination method.

[0024]

In order to achieve the above object, the present invention operates at intervals of a preset cycle to cause an ultrasonic wave to be incident on a material to be inspected from a probe at each of the above cycles, Based on the reflection echo signal received by the probe through the ultrasonic wave reflected by the inspection material by this, in the pulse type ultrasonic flaw detection device for inspecting the flaw in the inspection material, from the received reflection echo signal The gate unit that outputs a specific echo to the gate, the peak hold unit that holds and outputs a signal having a voltage value proportional to the peak level of the output signal of the gate unit at each preset cycle, and the peak hold unit A first filter for separating and filtering a low-frequency component of an amplitude fluctuation due to the rotation of the material to be inspected or the probe from the output signal; a signal delay unit for delaying the output signal of the peak hold unit; A configuration having a variable gain amplifier for amplifying the output signal of the signal delay unit based on the gain controlled by the output signal of the filter, and a second filter for removing low frequency components from the output signal of the variable gain amplifier It was done.

Further, according to the present invention, an arithmetic unit for performing an arithmetic operation of a predetermined procedure for the output signal of the peak hold unit and the output signal of the first filter is provided in the signal delay unit and the variable gain amplifying unit. A configuration provided instead may be used.

The gate portion of the present invention gates the inner surface echo in the input reflected echo signal on the basis of the gate signal having a gate starting point after a fixed time with reference to the outer surface echo in the input reflected echo signal. It is what

Further, in the present invention, the probe is configured to inject ultrasonic waves perpendicularly to the outer surface of the material to be inspected and perform inspection while rotating one of the probe and the material to be inspected. .

Further, in order to achieve the above object, the method of judging a flaw of the present invention is a method of judging a flaw in which an ultrasonic pulse is incident on a material to be inspected from a probe to determine a flaw inside the material to be inspected. In advance, a signal having an amplitude value proportional to the amplitude value of the inner surface echo of the material to be inspected and a signal obtained by separately filtering the frequency component of the amplitude fluctuation accompanying the rotation of the material to be inspected or the probe from the inner surface echo signal Perform the prescribed calculation,
A signal obtained by removing the frequency component of the amplitude fluctuation caused by the rotation of the inspection material or the probe from the signal of the calculation result is used to determine whether or not the detected flaw is allowed in the inspection material. It is a thing.

[0029]

In the ultrasonic flaw detector of the present invention, a specific echo is gate-outputted from the reflected echo signal received by the gate unit, and this gate output signal is supplied to the variable gain amplifying unit through the peak hold unit and the signal delay unit. At the same time, by controlling the gain of the variable gain amplifying section based on the low frequency component of the amplitude fluctuation due to the rotation of the inspected material or the probe separated and filtered from the output signal of the gate section by the first filter. The variable gain amplifier outputs a signal from which amplitude fluctuations due to the rotation of the material to be inspected or the probe have been substantially eliminated.

In the present invention, the output signal of the variable gain amplifying section is output through the second filter which selects only the high frequency component which changes abruptly due to the presence of the defect. A flaw can be inspected stably, automatically and accurately based on the specific echo output by the gate from the unit.

Further, in the case of using an arithmetic unit for performing an arithmetic operation of a predetermined procedure for the output signal of the peak hold unit and the output signal of the first filter, the output signal of the variable gain amplifying unit is used. An equivalent signal can be output from the arithmetic unit.

Furthermore, since the gate portion is configured to gate the inner surface echo in the input reflected echo signal based on the gate signal whose starting point is a fixed time after the outer surface echo in the input reflected echo signal is used as a reference, Even if the distance between the material to be inspected and the probe changes due to the rotation of the material to be inspected or the probe, the inner surface echo is always output to the gate and the flaw is inspected based on the amplitude of the inner surface echo. be able to.

[0033]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a block diagram of a first embodiment of the present invention. 6, those parts that are the same as those corresponding parts in FIG. 6 are designated by the same reference numerals, and a description thereof will be omitted.

The ultrasonic flaw detector 20 of this embodiment comprises a synchronizing signal oscillator 11, a transmitter 12, a receiver 13, a sweep wave generator 14, a display unit 15, a gate unit 21, and a peak hold unit 1.
7, a low-pass filter 22, a signal delay unit 23, a variable gain amplifying unit 24, a high-pass filter 25, an alarm unit 26, and a recording output unit 27.

That is, the ultrasonic flaw detector 20 of this embodiment
Then, the gate section 21 is changed to a configuration in which the gate starting point and the gate width are set so as to gate the echo from the inner surface of the inspection object 4, and the low frequency range is added to the output side of the peak hold section 17. The filter 22, the signal delay unit 23,
The variable gain amplifier 24 and the high-pass filter 25 are provided, and the output signal of the high-pass filter 25 is supplied to the alarm unit 26 and the recording output unit 27.

As a result, in the present embodiment, the internal surface echo attenuation method is used, the change in the size of the internal surface echo for each material 4 to be inspected is detected by the low-pass filter 22, and the sensitivity is adjusted by the variable gain amplifying section 24. After the correction, the inner surface echo reduction signal due to a flaw included in the variation of the inner surface echo height due to the scanning of the material 4 to be inspected is detected by using the high-pass filter 25. It is possible to detect flaws automatically even if the variation of the flaws occurs or even without using a test piece processed with artificial flaws.

Next, the operation of this embodiment will be described.
As described above, the synchronization signal a (FIG. 7) output from the synchronization signal oscillator 11 and having a constant transmission cycle shown in FIG.
In synchronization with (A) and FIG. 8A), a large amplitude pulse as shown in FIG. 2B is output from the transmitter 12 to the probe 3 via the coaxial cable 2. . As a result, as described above, the reflected wave of the ultrasonic wave vertically incident from the probe 3 into the inspected material 4 is received by the probe 3, and further,
The reflected echo signal as shown in FIG. 2C is input to the gate unit 21 via the receiving unit 13 after being converted into the reflected echo signal of the electric signal.

The gate section 21 has a gate starting point after a certain time from the rise of the outer surface echo S which is the first reflected echo in the input reflected echo signal, and the inner surface echo B
2D is generated to have a width such that the inner surface echo B can be gated even when fluctuates, and the reflected echo signal is gated. Such a gate portion 21
The so-called S echo synchronization of FIG.
As shown in (E), a signal b in which the inner surface echo B in the reflected echo signal is gated is output.

The gate output signal b is supplied to the peak hold section 17 and peak-held. Therefore, the output signal of the peak hold unit 17 is an analog signal having an amplitude proportional to the amplitude of the inner surface echo B of the material 4 to be inspected, and the amplitude fluctuates for each transmission cycle of the ultrasonic flaw detector 20.

The frequency component of this amplitude fluctuation of the output signal of the peak hold unit 17 is the frequency component f _C of the amplitude fluctuation accompanying the rotation of the inspection object 4 and the ultrasonic wave propagating in the inspection object 4 It is divided into frequency components f _{F of} amplitude fluctuations caused by being masked by the flaws in 4. Of these frequency components f _C and f _F , f _C is the same as the frequency of rotation of the inspected material 4 during flaw detection (in this case, the probe 3 is fixed). Since the rotation frequency of the material 4 to be inspected is 1 Hz or less, f _C is 1 Hz or less.

In the vertical flaw detection of the material 4 to be inspected, especially the steel pipe, the transmission repetition frequency of the ultrasonic flaw detection device is usually 1
It is set to about kHz. The ultrasonic wave propagating in the inspection material 4 is masked by the flaws in the inspection material 4, and the duration of the amplitude fluctuation that occurs is about several cycles of transmission (except if there is a large flaw, but first of all, No problem). Therefore, the amplitude fluctuation frequency component f _F generated by the ultrasonic waves propagating in the inspection object 4 being masked by the flaws in the inspection object 4 may be larger than 100 Hz. Since there is such a difference between both amplitude fluctuation frequency components f _C and f _F , as will be described later,
It is easy to remove one by the low pass filter 22 or the high pass filter 25.

FIG. 3 shows an example of fluctuations in the output signal of the peak hold unit 17 due to the rotation of the material 4 to be inspected. When viewed in detail (when the time axis is enlarged), this waveform has an amplitude that varies every transmission cycle of the ultrasonic flaw detector 20. F1 and F2 in FIG. 3 indicate that the flaws inside the material 4 to be inspected mask the propagation of ultrasonic waves and the echoes on the inner surface are reduced. The larger the flaw, the larger the amplitude reduction of the output signal of the peak hold unit 17.

In FIG. 3, F1 and F2 are flaws of approximately the same size, but in the circuit of the configuration of FIG. 6, F1 and F2 cannot be evaluated as the same flaw, and the amplitude is zero. F2 falling closer to the electric potential is evaluated as a large flaw. The present invention makes vertical flaw detection more effective by evaluating F1 and F2 as the same flaw.

The output signal of the peak hold unit 17 is branched into two, one of which has the frequency component f _F removed by the low-pass filter 22 (the frequency component f _C has been filtered), and the gain control of the variable gain amplifying unit 24. Is input to the first input terminal (for this input voltage value is Vc). Further, the other of the output signals of the peak hold unit 17 is supplied to the signal delay unit 23, where delay adjustment is performed for a time equal to the delay time of the low pass filter 22. Such an analog signal delay circuit capable of adjusting the delay time can be easily realized by, for example, a bucket brigade integrated circuit.

The output signal of the signal delay unit 23 is input to the other input terminal of the variable gain amplification unit 24 (this input voltage value is Vi). The variable gain amplifying section 24 amplifies the input voltage Vi based on the gain controlled by the input voltage Vc and outputs the output voltage Vo having a value represented by the following equation.

[0046]

## EQU00001 ## Vo = k.Vi / Vc (1) where k is a constant determined by the circuit configuration.
A circuit having such a function can be easily manufactured by using a commercially available integrated circuit.

As can be seen from the equation (1), the amplitude of the frequency component f _C of the amplitude fluctuation due to the rotation of the material 4 to be inspected is changed by the circuit unit including the low-pass filter 22, the signal delay unit 23 and the variable gain amplifying unit 24. Automatic gain control (AG
By performing step C), the output signal of the peak hold unit 17 is extracted from the variable gain amplification unit 24 after the amplitude fluctuation component due to the rotation of the inspection object 4 is almost removed.
It is supplied to the high-pass filter 25.

The high-pass filter 25 sufficiently attenuates and removes the frequency component f _C of the amplitude fluctuation due to the rotation of the inspected material 4 in the input signal, and the ultrasonic waves propagating in the inspected material 4 are inspected. A frequency component including an amplitude fluctuation frequency component f _F generated by being masked by a flaw in the material 4 is filtered.

The output signal of the high-pass filter 25 is supplied to the alarm unit 26 and the recording output unit 27, respectively. The alarm unit 26 has a predetermined alarm level and a high-pass filter 25.
The output signal of is compared with the level, and an alarm signal is generated and output when the level falls below the alarm level. This alarm level can be adjusted according to the purpose of flaw detection.

The recording output unit 27 converts the output signal of the high-pass filter 25 into a recording signal suitable for the use of a recording device such as a recorder to be used and outputs it.

The output signal of the high-pass filter 25 is a signal that accurately corresponds to the amplitude of the inner surface echo B in the material 4 to be inspected, and the amplitude changes depending on whether or not there is a flaw. Therefore, the flaw can be detected by the amplitude. Assuming that the reception level of the inner surface echo B when there is no defect is B _S and the reception level of the inner surface echo B when there is a defect is B _F , the ratio of these is k _B (= B _F / B _S ). To be evaluated.

As described above, according to the present embodiment, since the inner surface echo B is gate-outputted by the S echo synchronization in the gate portion 21, the inspection target material 4 is rotated by the rotation of the inspection target material 4. Due to the diametrical vibration, the gate portion 21
The internal surface echo B can be stably gated out even if the time between the transmission wave T and the external surface echo S in the reflected echo signal shown in FIG. It is possible to remove the undetectable area immediately below the outer surface and the undetectable area near the inner surface.

FIG. 4 shows the configuration of a second embodiment of the ultrasonic flaw detector of the present invention. In the figure, the same components as those in FIG. 1 are designated by the same reference numerals, and their description will be omitted. The ultrasonic flaw detector 30 shown in FIG. 4 has a digital peak hold unit 31 and a digital low-pass filter 3 on the output side of the gate unit 21.
2, a calculation unit 33, a digital high-pass filter 34, an alarm unit 35, and a recording output unit 36 are provided, which is composed of a digital circuit.

The digital peak hold unit 31 holds the digital signal having a value proportional to the maximum amplitude value of the echo gated in the gate unit 21 until the echo reception in the next cycle. The calculation unit 33 calculates the formula (1) for the output signal of the digital low-pass filter 32 and the output signal of the digital peak hold unit 31. Further, the arithmetic unit 33 receives the gate signal from the gate unit 21 and then delays by a time equal to the delay time of the digital low-pass filter unit 32 to start a predetermined arithmetic operation.

The digital signal output from the arithmetic unit 33 is supplied to the digital high-pass filter 34 to sufficiently attenuate and remove the frequency component f _C of the amplitude fluctuation due to the rotation of the inspected material 4, and the inspected material 4 as well. The ultrasonic wave propagating inside is masked by flaws in the material 4 to be inspected, and a frequency component including an amplitude fluctuation frequency component f _F generated by the flaw is digitally filtered.

The alarm unit 35 and the recording output unit 36 respectively receive the output digital signals of the digital high-pass filter 34, perform the same operation as the alarm unit 26 and the recording output unit 27 by digital processing, and when necessary, generate an alarm signal. , Output the recording signal.

[0057]

As described above, according to the present invention, the second signal for removing the low frequency component of the amplitude fluctuation due to the rotation of the material to be inspected or the probe from the output signal of the variable gain amplifying section or the arithmetic section. By outputting through the filter, it is stable based on the specific echo output by the gate section.
Since the flaw can be inspected automatically and accurately, the flaw can be inspected accurately without using the test piece having the artificial flaw.

Further, according to the present invention, the inner surface echo in the input reflected echo signal is gated based on the gate signal whose gate starts from the outer surface echo in the input reflected echo signal at a gate after a certain time. By doing so, even if the distance between the material to be inspected and the probe changes due to the rotation of the material to be inspected or the probe, the inner surface echo is always gated out and based on the amplitude of the inner surface echo. Since the flaw is inspected, it is possible to prevent the non-detectable range immediately below the outer surface and the non-detectable range near the inner surface even if the amplitude changes due to the rotation of the material to be inspected or the probe.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of a device of the present invention.

FIG. 2 is a timing chart for explaining the operation of FIG.

FIG. 3 is a diagram showing an output signal waveform of a peak hold unit accompanying rotation of a material to be inspected.

FIG. 4 is a configuration diagram of a second embodiment of the device of the present invention.

FIG. 5 is a schematic diagram for explaining a vertical flaw detection method.

FIG. 6 is a configuration diagram of an example of a conventional device.

FIG. 7 is a timing chart for explaining the operation of the conventional device.

FIG. 8 is a timing chart for explaining a problem of the conventional device.

[Explanation of symbols]

 1, 10, 20, 30 ... Ultrasonic flaw detector 2 ... Coaxial cable 3 ... Probe 4 ... Inspected material 11 ... Synchronous signal oscillator 12 ... Transmitter 13 ... Receiver 14 ... Sweep wave generator 15 ... Display 17 ... Peak hold unit 21 ... Gate unit 22 ... Low-pass filter 23 ... Signal delay unit 24 ... Gain variable amplification unit 25 ... High-pass filter 31 ... Digital peak-hold unit 32 ... Digital low-pass filter 33 ... Calculator 34 ... Digital high-pass filter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigetoshi Hyodo 1st Nishino-cho, Higashimukaijima, Amagasaki City, Hyogo Prefecture Sumitomo Metal Industries Co., Ltd. Steel Pipe Works

Claims (5)

[Claims] 1. An ultrasonic wave which is operated at intervals of a preset period to cause an ultrasonic wave to be incident on a material to be inspected by the probe at each of the above cycles, whereby the ultrasonic wave reflected from the material to be inspected is transmitted to the probe. A pulse-type ultrasonic flaw detector for inspecting flaws in the material to be inspected based on a reflected echo signal received via a gate unit for gate-outputting a specific echo from the received reflected echo signal; A peak hold unit for holding and outputting a signal having a voltage value proportional to the peak level of the output signal of the unit at each of the preset periods, and the output signal of the peak hold unit from the inspected material or the probe. A first filter that separates and filters low-frequency components of amplitude fluctuations due to the rotation of the tentacle; a signal delay unit that delays the output signal of the peak hold unit; and an output signal of the first filter. A variable gain amplifying section for amplifying the output signal of the signal delaying section based on the gain controlled by the second delay section, and a second filter for passing only a high-frequency component having a large change from the output signal of the variable gain amplifying section. An ultrasonic flaw detector characterized by the above. 2. The probe is operated at intervals of a preset cycle to cause ultrasonic waves to enter the material to be inspected from the probe for each of the above cycles, whereby ultrasonic waves reflected from the material to be inspected are reflected. A pulse-type ultrasonic flaw detector for inspecting flaws in the material to be inspected based on a reflected echo signal received via a gate unit for gate-outputting a specific echo from the received reflected echo signal; A peak hold unit for holding and outputting a signal having a voltage value proportional to the peak level of the output signal of the unit at each of the preset periods, and the output signal of the peak hold unit from the inspected material or the probe. A first filter that separates and filters a low-frequency component of the amplitude variation due to the rotation of the tentacle, and an output signal of the peak hold unit and an output signal of the first filter are predetermined. A calculation section that performs calculation procedure that is, the ultrasonic flaw detection apparatus characterized by a second filter for passing only intense high frequency components of the change from the output signal of the arithmetic unit. 3. The gate unit gates an inner surface echo in the input reflected echo signal based on a gate signal whose starting point is a fixed time after the outer surface echo in the input reflected echo signal is used as a reference. Claim 1 characterized by the above-mentioned.
Or the ultrasonic flaw detector according to 2. 4. The probe injects ultrasonic waves perpendicularly to the outer surface of the inspection target material, and performs inspection while rotating one of the probe and the inspection target material. The ultrasonic flaw detector according to any one of claims 1 to 3. 5. A flaw determination method for determining an internal flaw of a material to be inspected by injecting an ultrasonic pulse from the probe into the material to be inspected, which is proportional to an amplitude value of an inner surface echo of the material to be inspected. A signal having an amplitude value to be obtained and a signal obtained by separating and filtering the frequency component of the amplitude variation due to the rotation of the material to be inspected or the probe from the inner surface echo signal are subjected to a predetermined calculation, and the calculation is performed. The signal obtained by removing the frequency component of the amplitude fluctuation due to the rotation of the inspected material or the probe from the signal of the result, it is possible to determine whether the detected flaw is allowed in the inspected material. Characteristic flaw judgment method.