JP4462277B2 - Ultrasonic flaw detection method and apparatus - Google Patents

Description

  The present invention relates to a method and an apparatus for performing flaw detection by transmitting / receiving ultrasonic waves to / from a test material using an array probe having a plurality of transducers.

In the conventional ultrasonic flaw detection method, a single probe selected from a plurality of ultrasonic probes is connected to an ultrasonic flaw detector to inspect a test material (flaw detection). Therefore, the ultrasonic probe having a frequency, size, and type (vertical, oblique, etc.) suitable for the purpose of use is selected and connected. For example, a probe displayed as 5Z20N is a vertical probe having a frequency of 5 MHz, a transducer having a circular shape and a diameter of 20 mm.
When one ultrasonic probe is selected in this way, the frequency and size of the probe (in this example, the diameter D of the circular transducer) is determined (fixed). The sound field generated in the test material by the child is also determined.

The sound field generated in the test material by the circular vibrator is a near field sound in a range from the surface of the test material in contact with the vibrator to the near field limit distance x ₀ determined by the following equation (1). and the field is divided into a far field of the range from x ₀ long-distance.
x ₀ = D ² / 4λ = D ² f / 4C (1)
Here, D is the diameter of the circular vibrator, λ is the wavelength of the ultrasonic wave being propagated, λ = C / f where f is the frequency and C is the propagation velocity.

FIG. 7 is an explanatory diagram of the shape of the ultrasonic beam by the circular vibrator. The ultrasonic beam propagating from the surface of the test material to the inside of the test object is a short distance as shown in FIG. In the sound field, the thickness is almost equal to the diameter of the vibrator.
Further, in the far field far away from x ₀ , as shown in FIG. 7, the distance is longer due to the conical shape having the center of the transducer as the apex and the directivity angle ψ ₀ determined by the following equation (2). It becomes a thick beam gradually.
ψ ₀ = 70λ / D = 70C / Df (2)
Here, D and λ are the diameter and wavelength of the vibrator, respectively, similarly to the equation (1).
As described above, the shape of the ultrasonic beam varies depending on the size of the transducer and the wavelength of the ultrasonic wave.

  Now, when a normal commercially available vertical probe is used to detect a flaw in a near field in a test material, for example, a small flaw near the surface, the A scope display generally uses a flaw. The height (amplitude value) of the reflected echo is displayed in proportion to the ratio of the area of the flaw and the effective area of the transducer (meaning the effective area of the ultrasonic beam), Using the vibrator can detect even fine flaws with high sensitivity.

However, if a small-sized vibrator is used, flaws in the near field within the specimen can be detected with high sensitivity, but in order to detect flaws in the far field, from the spread of the directivity angle, The apparent effective area of the vibrator is increased, and the detection sensitivity is reduced due to the relationship with the flaw area.
In order to make it easier to detect a flaw in the far-field sound field in the test material, it is necessary to increase the size (diameter) of the vibrator in order to reduce the directivity angle. However, if a large-sized vibrator is used, it is easy to detect a flaw in the far field, but conversely, a small flaw near the surface has a large vibrator area, so the sensitivity is high due to the ratio of the flaw area. Decreases and makes detection difficult.

As described above, in the conventional ultrasonic flaw detection method, a single ultrasonic probe can be used to achieve a wide range from the near field to the far field in the test material with good sensitivity or almost uniform sensitivity. The flaw could not be detected.
Therefore, in order to perform a flaw detection without reducing the detection sensitivity, first a flaw detection is performed on the near-field sound field (portion close to the surface of the test material) using a probe having a small diameter, and then It is necessary to replace the probe with one with a larger diameter, and to perform the flaw detection on the far-field sound field (the deep part inside the test material) for the same test material. There was a problem that it increased twice as much as the case of the probe.

When estimating the flaw size, when the flaw is smaller than the transducer size, a method is generally used in which the flaw is estimated by the ratio F / B of the flaw echo height F on the A scope and the bottom echo height B.
For this reason, if the contact state between the ultrasonic probe and the test material changes slightly, the apparent effective area of the transducer changes, and the height B of the bottom echo and the value of F / B change accordingly. There are also problems such as variations in flaw size estimation accuracy.

  Ultrasonic diagnostic technology is similar to this ultrasonic flaw detection technology, and even in this ultrasonic diagnosis, in order to obtain a clear ultrasonic image over a wide range from a shallow part to a deep part of the subject, the depth of focus is deep. There has been a demand for a probe that forms a thin ultrasonic beam. There is JP-A-8-289889 (hereinafter simply referred to as a patent gazette) as a known document that meets this demand.

FIG. 8 is a block diagram of the ultrasonic diagnostic apparatus according to the first embodiment of the above patent publication.
In FIG. 8, an annular array type ultrasonic transducer (transducer) 104 is composed of a piezoelectric element 101 that generates a focused sound field that focuses on a predetermined point, and concentric piezoelectric elements 102 and 103 that have a confocal point. The acoustic lens 120 is joined to the acoustic radiation surface. The electrode 106 of the piezoelectric element 101 is connected to the excitation circuit 109 via the delay line 107 and the separation circuit 108, the electrode 110 of the piezoelectric element 102 is connected to the excitation circuit 109 via the delay line 111, and the electrode 112 of the piezoelectric element 103 is connected. Is directly connected to the excitation circuit 109. The excitation circuit 109 is connected to the observation device 113, and the separation circuit 108 is connected to the observation device 113 via the amplifier 114. The piezoelectric elements 101 and 102 are driven with a delay relative to 103 so that the synthesized sound field of each piezoelectric element is focused on a point different from the predetermined focus.
In this first embodiment, the piezoelectric element 103 is directly excited (that is, without time delay), the piezoelectric element 102 is delayed by 40 ns by the delay line 111, and the piezoelectric element 101 is delayed by 80 ns by the delay line 107, and the frequency is 15 MHz. In the synthesized sound field of each piezoelectric element, an electronic focal length of 21 mm different from the geometric focal length of 30 mm is obtained.

However, the sound field characteristics of the ultrasonic probe and the transmission / reception method of the above-mentioned patent publication are shown in FIGS. 3 and 8, and the ultrasonic beam at the electronic focal length is narrowed down. The position is a rather thick beam.
In ultrasonic flaw detection, it is desirable that flaw detection can be performed with a substantially constant ultrasonic beam diameter and good sensitivity within a predetermined flaw detection range. Therefore, the sound field characteristics of the above-mentioned patent publication are satisfactory for use in ultrasonic flaw detection. It wasn't possible.

Further, the excitation method of each piezoelectric element in the above-mentioned patent gazette sequentially excites a time difference between each piezoelectric element, so that multiple ultrasonic waves are generated by the excitation of the first piezoelectric element, and the first ultrasonic wave During the generation period, a process in which a plurality of ultrasonic waves are generated again by excitation of the next piezoelectric element is repeated. Therefore, in proportion to the case where all the piezoelectric elements are excited simultaneously, the wave number of the ultrasonic wave generated as a whole increases, and the distance resolution deteriorates.
In ultrasonic flaw detection, information on the position and size of flaws is important, and the above-described deterioration in distance resolution is not preferable.

  In this way, in ultrasonic flaw detection, a single ultrasonic probe is used, and a wide range from the near field to the far field in the test material is highly sensitive or has good sensitivity that is almost uniform. Therefore, there has been a demand for an ultrasonic flaw detection method and apparatus that can perform flaw detection with the same method and that does not deteriorate the distance resolution.

  In the ultrasonic flaw detection method according to the present invention, the transducer area for transmitting and receiving ultrasonic waves can be changed to a plurality of N stages by an array probe having a plurality of vibrators. The transducer area is changed in stages, and ultrasonic waves are transmitted to and received from the specimen to acquire received signals within a predetermined flaw detection range, and the received signals for each transmission and reception period acquired in a plurality of N ultrasonic transmission and reception periods are respectively quantized. A plurality of N time series data is stored, the stored N time series data is compared for each time series position, and data having the maximum amplitude value is extracted as reception result data at that time series position. It is.

  In the ultrasonic flaw detection method according to the present invention, a plurality of N time-series data are compared for each time-series position, and reception result data within a predetermined flaw detection range obtained by sequentially extracting data having the maximum amplitude value of the time-series data is obtained. When displaying or recording, the sensitivity of the reception result data at each extraction position is displayed or recorded without changing the sensitivity, or the sensitivity of the reception result data at each extraction position is almost uniform within a predetermined flaw detection range. It is changed to be displayed or recorded.

  In the ultrasonic flaw detection method according to the present invention, a plurality of N time-series data are compared for each time-series position, and data having the maximum amplitude value is sequentially extracted and detected from reception result data in a predetermined flaw detection range. As the evaluation of the flaw, the flaw size is evaluated based on the ratio of the echo height of the detected flaw and the height of the bottom echo in the time series data from which the reception result data corresponding to this flaw is extracted, or the flaw detected The flaw size is evaluated on the basis of the echo height of the ultrasonic beam and the effective area of the ultrasonic beam at the detection position where the transmission / reception cycle stores the time-series data from which the reception result data corresponding to the flaw is stored.

  An ultrasonic flaw detector according to the present invention includes an array probe having a central vibrator, and one or a plurality of peripheral vibrators arranged at positions surrounding the central vibrator, and an array probe. By adding one or more peripheral vibrators to the central vibrator and the central vibrator, the vibrator area can be changed to multiple N stages one by one for each ultrasonic transmission / reception cycle. Ultrasonic transmission / reception means for transmitting / receiving ultrasonic waves to the material, and a plurality of N time series by quantizing the reception signals in a predetermined flaw detection range acquired by the ultrasonic transmission / reception means for each transmission / reception period in a plurality of N ultrasonic transmission / reception periods A reception result data extracting unit that stores the N time-series data stored as data, compares the time-series data stored for each time-series position, and extracts data having the maximum amplitude value as reception result data at the time-series position. It is those with a door.

  In the ultrasonic flaw detector according to the present invention, the reception result data extraction unit inputs reception result data extracted for each time series position from a plurality of N time series data, and the reception result data for each time series position is Sensitivity change selection means for outputting the reception sensitivity amplitude value as it is or changing the amplitude value so that the sensitivity is substantially uniform within a predetermined flaw detection range, and a plurality of N time series of reception result data extraction means. When the reception result data extracted for each time-series position is inspected from the data, and the evaluation of the flaw detected from this reception result data, the echo height of the detected flaw and the reception result data corresponding to this flaw are extracted Evaluate the flaw size based on the ratio of bottom echo height in the series data, or the time series in which the echo height of the detected flaw and the reception result data corresponding to the flaw were extracted Is obtained by adding a flaw size evaluation means for evaluating the flaw size on the basis of the effective area of the ultrasonic beam at those flaws detected position of the transmitting and receiving period for storing a over data.

  In the present invention, the transducer area for transmitting and receiving ultrasonic waves can be changed to a plurality of N stages by an array probe having a plurality of transducers, and the transducer area is sequentially divided into N stages for each ultrasonic transmission / reception cycle. Is changed to obtain a reception signal in a predetermined flaw detection range by transmitting / receiving ultrasonic waves to / from the test material, and quantizing the reception signals for each transmission / reception period acquired in a plurality of N ultrasonic transmission / reception periods, Since the stored time series data of the plurality N is compared for each time series position, and the data having the maximum amplitude value is extracted as the reception result data at the time series position. For each flaw, it is possible to automatically acquire flaw data detected at the highest sensitivity at the detection position of the win.

  In the present invention, a plurality of N time-series data are compared for each time-series position, and reception result data within a predetermined flaw detection range obtained by sequentially extracting data having the maximum amplitude value among them is displayed or recorded. In this case, the sensitivity of the reception result data at each extraction position is displayed or recorded as it is without changing the sensitivity, or the sensitivity of the reception result data at each extraction position is substantially uniform in a predetermined flaw detection range. Since it is changed and displayed or recorded, it is possible to display flaws with the highest sensitivity at each flaw detection position and display flaws with almost uniform sensitivity over the entire flaw detection range.

  Further, according to the present invention, a plurality of N time-series data are compared for each time-series position, and the flaws detected from the reception result data in the predetermined flaw detection range obtained by sequentially extracting the data having the maximum amplitude value among them. Evaluation is based on the ratio of the echo height of the detected flaw and the height of the bottom echo in the time series data from which the reception result data corresponding to this flaw is extracted, or the echo height of the detected flaw Since the size of the flaw is evaluated based on the effective area of the ultrasonic beam at the position where the detection result of the transmission / reception cycle where the reception result data corresponding to the flaw is extracted is stored, the bottom echo height Whether or not is sufficiently obtained, the flaw dimensions can be evaluated with high accuracy by using calibration data together.

Embodiment 1
In the first embodiment, the transducer area of the ultrasonic probe can be changed to a plurality of stages (3 in this embodiment, but generally N), and a predetermined flaw detection range of the test material ( For example, in the case of vertical flaw detection, the entire range from the surface to the bottom surface of the test material is divided into the same number of ranges as the plurality N, and is divided into the plurality N in advance corresponding to each of the N-stage transducer areas. One of the flaw detection ranges is allocated, and the transducer area is changed to the N stages sequentially for each ultrasonic transmission / reception cycle to transmit / receive ultrasonic waves to / from the test material. The flaw detection is performed for each flaw detection range assigned in correspondence.

In the first embodiment, a combination example of a three-stage vibrator area and each flaw detection range obtained by dividing the whole flaw detection range into three corresponding to this will be described later. When each flaw detection is performed by the above, a corresponding combination of each transducer area and each flaw detection range is made so that flaw detection can be performed with the highest sensitivity according to each transducer area.
Further, a method that does not require a predetermined combination of each transducer area and each flaw detection range will be described in the second embodiment.

FIG. 1 is a block diagram of an ultrasonic flaw detector according to Embodiment 1 of the present invention, and FIG. 2 is a timing chart for explaining the operation of the apparatus of FIG.
First, an array type ultrasonic probe shared by the first and second embodiments will be described.
FIG. 3 is a configuration diagram of the array-type ultrasonic probe according to the first and second embodiments of the present invention.
FIG. 3 shows an example of an annular array type ultrasonic probe. In FIG. 3, 1, 2 and 3 in (a) are # 1, # 2, and # 3 vibrations arranged concentrically. 4 and 5 are spacers between the vibrators. For example, # 1 vibrator 1 has a circular shape with a diameter of 7 mm, # 2 vibrator 2 has a ring shape with an inner diameter of 7.1 mm and an outer diameter of 10.0 mm, and # 3 vibrator 3 has a ring with an inner diameter of 10.1 mm and an outer diameter of 14.0 mm. Is. In addition, the spacers 4 and 5 have an annular shape such as non-conductive rubber or resin, and are provided between the vibrators.
3A, the # 1 vibrator 1 is a central vibrator, and the # 2, # 3 vibrators 2 and 3 are peripheral vibrators arranged at positions surrounding the central vibrator. Also called.

3, 7 and 8 in FIG. 3B are individual electrodes provided on one surface of the # 1, # 2 and # 3 vibrators, respectively, # 1 vibrator electrode, # 2 vibrator electrode, It is called # 3 vibrator electrode. Reference numeral 9 denotes a common electrode provided in common on the other surface of the # 1, # 2, and # 3 vibrators. The common electrode 9 is formed by integrally bonding the # 1, # 2, # 3 vibrators 1, 2, 3 and the spacers 4, 5 such as resin, and then sputtering the metal material on the acoustic radiation surface. . Each of the electrodes 6 to 9 is provided with a connection line.
As described above, the array-type ultrasonic probe 10 shown in FIG. 3 has a single probe structure. However, it is possible to transmit and receive ultrasonic waves using each transducer and to transmit and receive ultrasonic waves using a plurality of transducers. .
That is, if a pulse voltage is applied only between the common electrode 9 and the # 1 transducer electrode 6 through the connection line to each electrode, ultrasonic waves are transmitted by the # 1 transducer 1 and the common electrode 9 and If a pulse voltage is applied only between the # 2 vibrator electrodes 7, transmission by the # 2 vibrator 2 is performed.
If # 1 vibrator electrode 6 and # 2 vibrator electrode 7 are externally coupled via a connecting line, and a pulse voltage is applied between this coupling point and common electrode 9, # 1 vibrator 1 and # 2 Transmission of ultrasonic waves by the vibrator 2 is performed. Each transducer can also receive signals in the same manner as ultrasonic waves.

Next, an example will be described in which the transducer area for transmitting and receiving ultrasonic waves is changed in three stages using # 1, # 2, and # 3 transducers 1, 2, and 3.
(1) If only the # 1 vibrator 1 is used now, the vibrator area A ₁ is about 38.5 mm ² as a circular area with a diameter of 7 mm in this example.
(2) Next, when the # 1 vibrator 1 and the # 2 vibrator 2 are used, they are approximately circular with a diameter of 10 mm, so that the vibrator area A ₂ is about 78.5 mm ² , which is about A ₁ . Doubled.
(3) Next, when # 1 vibrator 1, # 2 vibrator 2 and # 3 vibrator 3 are used, since it is approximately circular with a diameter of 14 mm, the vibrator area A ₃ is about 153.9 mm ^2. And approximately twice A ₂ .

In the first and second embodiments, as described above, only the central vibrator is first, the next is the central vibrator and one peripheral vibrator adjacent thereto, and the next is the central vibrator and the next. two peripheral portion vibrator, ... and by increasing the number of transducers for transmitting and receiving ultrasonic waves sequentially, can change the transducer area 38.5mm ^2, 78.5mm ^2, 153.9mm ² and in three steps I am doing so.
An example of a combination of each transducer area and one flaw detection range of the first embodiment divided into three will be described later.

In the ultrasonic flaw detector of FIG. 1, reference numeral 10 denotes the array-type ultrasonic probe described in FIG. 3, the common electrode 9 is grounded, and the # 1, # 2, # 3 transducer electrodes 6, 7, 8 are connected. Are connected to the transducer selection circuit 20.
Reference numeral 20 denotes a transducer selection circuit, which includes mechanical or semiconductor switches S ₁ and S ₂ for selecting a transducer for transmitting and receiving ultrasonic waves. That is, the switch S ₁ is in the closed, # 1, it is possible to transmit and receive according to # 2 resonator 1, the switch S ₁ and S ₂ are both in the closed, # 1, # 2, # 3 transducers 1,2 , 3 can be transmitted and received. The opening / closing control signals for the switches S ₁ and S ₂ are supplied from the timing control circuit 80.
A reception protection circuit 21 is a circuit for protecting the reception circuit 40 during transmission. For example, a bidirectional diode or the like protects the application of positive and negative excessive voltages to the receiving circuit 40 during transmission.

Reference numeral 30 denotes a transmission circuit, which outputs a transmission pulse for exciting the vibrator each time a synchronization signal (repetition frequency is f, that is, repetition period is T = 1 / f) is supplied from the timing control circuit 80. This transmission pulse is generated, for example, by charging a capacitor from a high-voltage power supply via a resistor and instantaneously discharging the capacitor charge via a semiconductor switch (such as SCR) by the synchronization signal.
Reference numeral 40 denotes a reception circuit, and since a reception signal from the transducer is input via the reception protection circuit 21, the reception signal in the required frequency band is amplified, detected, and output as a video signal (including an echo signal). .
41 is a reception gate circuit, and any one of the # 1 reception gate signal, # 2 reception gate signal, and # 3 reception gate signal is supplied as a reception gate signal from the timing control circuit 80. Only the signal during the generation period of the supplied reception gate signal is extracted from the output signal of the reception circuit 40 and output.

50 is an A / D converter, 51 is a # 1 memory, 52 is a # 2 memory, 53 is a write / read control circuit, and S ₃ and S ₄ are switches such as semiconductors. Note # 1 and # of providing two of the two memories, the duration is writing the output data of the A / D converter 50 into one of the memory through a switch S ₃ (# 1 memory 51 in the illustrated), parallel (in the illustrated # 2 memory 52) other memory in order that the read to the data already stored from via the switch S _4. Reference numeral 60 denotes flaw detection result evaluation means, which is composed of, for example, a commercially available personal computer. 61 is a D / A converter, 62 is a display device such as a CRT or liquid crystal, and 70 is a printing device (including a recorder).

A timing control circuit 80 generates various signals for controlling the timing of the entire apparatus and supplies the signals to other devices. For example, the switches S ₁ and S ₂ in the transducer selection circuit 20 are supplied with # 2, # 3 periodic signals, the transmission circuit 30 is provided with a synchronization signal, and the reception gate circuit 41 is provided with # 1, # 2, # 3 reception gate signals. The sampling clock signal is supplied to the A / D converter 50, and the timing control signal is supplied to the write / read control circuit 53, respectively.
The various timing control signals generated and output by the timing control circuit 80 are changed according to parameter data such as the number of transducers included in the array-type ultrasonic probe 10, the thickness of the test material, and the material. Accordingly, the timing control circuit 80 is provided with, for example, a DIP switch for setting the parameter data, or a parameter data input register, and the parameter data is input via the flaw detection result evaluation means 60 such as a personal computer. It is desirable that the parameter data can be easily changed by a technique such as

In the first and second embodiments, the test material is mild steel and the thickness (length from the surface to the bottom surface) is 55 mm. In addition, the acquisition range of the received signal is a time range corresponding to a depth of 60 mm from the surface so that the bottom echo can be sufficiently detected.
Next, in the first embodiment, the reception range (also referred to as the entire flaw detection range) from the surface to 60 mm is divided into three flaw detection ranges of the surface to 20 mm, 20 mm to 40 mm, and 40 mm to 60 mm, and the array type ultrasonic wave The flaw detection is performed by combining the three-step area of the probe and the divided flaw detection ranges as follows. It should be noted that at the boundary between the three flaw detection ranges, it is desirable that adjacent flaw detection ranges are set so as to overlap somewhat so that flaw detection is not lost. Since each transmission / reception requires one transmission / reception cycle, the following three transmission / reception cycles are used.
(1) In the # 1 transmission / reception cycle, transmission / reception is performed with the transducer area of 38.5 mm ² , and a reception signal in the range from the surface of the test material to the inside 20 mm is used for flaw detection.
(2) In the # 2 transmission / reception cycle, transmission / reception is performed with the transducer area of 78.5 mm ² , and a received signal in the range from 20 mm to 40 mm inside the test material is used for flaw detection.
(3) In the # 3 transmission / reception cycle, transmission / reception is performed with the transducer area set to 153.9 mm ² , and a reception signal in the range of 40 mm to 60 mm inside the test material is used for flaw detection.

The operation of FIG. 1 will be described with reference to the time chart of FIG. All the horizontal axes in FIG. 2 are time.
The timing control circuit 80 shown in FIG. 1 has a synchronization signal (shown in FIG. 2) every predetermined repetition frequency f (for example, 10 KHz), that is, every repetition period T (= 1 / f, so if f = 10 KHz, T = 100 μs). (See (a)) is generated and supplied to the transmission circuit 30.
In addition, in this example, the timing control circuit 80 outputs a # 1 reception gate signal for extracting a reception signal in the range of 20 mm from the surface of the test material in the # 1 transmission / reception cycle. The # 2 reception gate signal for extracting the reception signal in the range from 20 mm to 40 mm inside the specimen, and the reception signal in the range from 40 mm to 60 mm inside the specimen in this example in the # 3 transmission / reception cycle. # 3 reception gate signals are generated for each.
Since one transmission / reception cycle is formed by the above three periods, the timing control circuit 80 counts the synchronization signal by a ternary counter and always knows what number period it is currently in.

(1) # 1 transmission / reception cycle In the # 1 transmission / reception cycle, using only the # 1 transducer 1 (as a probe area equivalent to 5Z7 of a commercially available probe), for example, a depth of 20 mm from the surface of the test material Flaw detection shall be conducted for the range up to.
In this # 1 transmission / reception cycle, the switches S ₁ and S ₂ in the transducer selection circuit 20 are controlled by the timing control circuit 80 so as to be opened, so that the transmission pulse output from the transmission circuit 30 based on the synchronization signal. Is applied only to the # 1 vibrator 1 (see FIG. 2B).
The ultrasonic wave propagating into the test material by the excitation of the # 1 vibrator 1 and reflected from the internal flaw etc. is received through the # 1 vibrator 1, the reception protection circuit 21, and the reception circuit 40 again. 41.

In the # 1 transmission / reception cycle, the timing control circuit 80 supplies only the # 1 reception gate signal having the time width t ₁ to the reception gate circuit 41 immediately after the end of the # 1 transducer transmission pulse (see (e) of FIG. 2). reference).
Here, the time width t ₁ is obtained as follows in order to extract a received signal having a depth of 20 mm from the surface of the test material.
Now, if the test material is mild steel, and longitudinal wave flaw detection is performed by a vertical probe, the longitudinal wave sound velocity v in this case is about 5900 m / s, and the longitudinal wave propagates through a distance of 40 mm in both directions. The required time t ₁ is obtained as t ₁ = 40 mm / 5900 m / s≈6.78 μs.

Based on the supplied # 1 reception gate signal, the reception gate circuit 41 extracts a reception video signal having a depth of 20 mm from the surface of the test material from the input video signal and supplies it to the A / D converter 50. The A / D converter 50 can display an echo waveform with a desired amplitude resolution for each sampling clock signal selected from the timing control circuit 80 by selecting this input video signal so as to satisfy a desired distance resolution. The data is sequentially converted into digital data having a sufficient number of bits and output.
The time-series digital data output from the A / D converter 50 is controlled by the write / read control circuit 53 via the switch S ₃ such as a semiconductor (not shown in FIG. 1). # 1 memory 51).

In the case of vertical flaw detection, the # 1 memory 51 and the # 2 memory 52 are time series data (amplitude data for each sampling position) obtained by quantizing all received signals from the surface to the bottom surface of the test material, and each flaw detection range boundary. The memory capacity is sufficient to store the boundary identification data.
In the example of FIG. 1, the write / read control circuit 53 is provided for each unit depth from the surface of the test material in the # 1 memory 51 to a depth of 20 mm in the # 1 transmission / reception cycle of the #i transmission / reception cycle. to set the address, sequentially written a series digital data when supplied from the a / D converter 50 through a switch S _3.
Also, in this # 1 transmission / reception cycle, the write / read control circuit 53, based on the read control signal from the flaw detection result evaluation means 60, stores the test stored from the # 2 memory 52 in the previous # (i-1) transmission / reception cycle. sequentially read series digital data when the entire inspection range from the surface of the wood to the bottom, and supplies the inspection result evaluation unit 60 via a switch S _4.
The operation of the flaw detection result evaluation means 60 relates to all of the # 1 to # 3 transmission / reception cycles, and will be described after the description of the # 3 transmission / reception cycles.

(2) # 2 transmission / reception cycle In the # 2 transmission / reception cycle, ultrasonic transmission / reception is performed using the # 1 transducer 1 and # 2 transducer 2 (with a probe area equivalent to 5Z10 of a commercially available probe). For example, it is assumed that flaw detection is performed in a range of 20 mm to 40 mm in depth of the test material.
In the # 2 transceiver period, the switch S ₁ in the transducer selection circuit 20 is in the closed by # 2 periodic signal supplied from the timing control circuit 80, the transmission pulse output from the transmission circuit 30 # 1 Applied to both the vibrator 1 and the # 2 vibrator 2 (see FIGS. 2B and 2C).
The ultrasonic waves that have propagated through the specimen by the excitation of the # 1 vibration 1 and the # 2 vibrator 2 and are reflected from the internal flaw etc. are received through the # 1 vibrator 1 and the # 2 vibrator 2 again. The signal is supplied to the reception gate circuit 41 through the protection circuit 21 and the reception circuit 40.

In the # 2 transceiver period, the timing control circuit 80, after the elapse of the time t ₁ immediately after the completion of the transmitted pulse, and supplies the reception gate circuit 41 only # 2 receives the gate signal time width t ₂ (in FIG. 2 (See (f)).
Here, the time t ₁ is the same as the time t ₁ of the # 1 reception gate signal and is about 6.78 μs, and the time width t ₂ is obtained as follows.
Similar to the above, the longitudinal wave sound velocity v is about 5900 m / s, and the time t required for the longitudinal wave to propagate through a distance of 80 mm in the round trip is t = 80 mm / 5900 m / s≈13.56 μs, and t ₂ = t−t ₁ ≈ (13.56-6.78) μs≈6.78 μs.
In actual device design, it is preferable to terminate the # 1 reception gate signal after the generation of the # 2 reception gate signal so that no signal break occurs between the two gate signals.

Based on the supplied # 2 reception gate signal, the reception gate circuit 41 extracts a reception video signal having a depth of 20 mm to 40 mm of the test material from the input video signal and supplies it to the A / D converter 50. . The A / D converter 50 converts the amplitude value of the input video signal into digital data of a predetermined number of bits for each sampling clock signal supplied from the timing control circuit 80, as in the # 1 transmission / reception cycle. Output sequentially.
Series digital data when output from the A / D converter 50 is controlled by the write-read control circuit 53, via the switch S _3, it was subjected to the data writing in the # 1 transceiver period # 1 memory 51 It is sequentially written in each address set for each unit depth from 20 mm to 40 mm in depth.
At this time, if boundary identification data indicating the boundary between the data group in the flaw detection range in # 1 transmission / reception cycle and the data group in the flaw detection range in # 2 transmission / reception cycle is provided in the memory, the difference in sensitivity between the two data groups is determined. This is convenient when correcting.
Further, the writing / reading control circuit 53, based on the reading control signal from the flaw detection result evaluation means 60, reads from the surface to the bottom surface of the test material stored in the previous # (i-1) transmission / reception cycle from the # 2 memory 52. among the time-series digital data of all flaw detection range, it reads echo data to be required, and supplies the inspection result evaluation unit 60 via a switch S _4.

# 3 transmission / reception cycle In the # 3 transmission / reception cycle, all transducers of # 1, transducer 2, # 2, and # 3 transducer 3 are used (with a transducer area equivalent to 5Z14 of a commercially available probe). It is assumed that ultrasonic waves are transmitted and received, for example, flaw detection is performed in the range of a depth of 40 mm to 60 mm of the test material.
In this # 3 transmission / reception cycle, the switches S ₁ and S ₂ in the transducer selection circuit 20 are both closed by the # 3 cycle signal supplied from the timing control circuit 80, so that they are output from the transmission circuit 30. The transmission pulse is applied to all the vibrators of the # 1 vibrator 1, the # 2 vibrator 2, and the # 3 vibrator 3 (see (b), (c), and (d) of FIG. 2).
The ultrasonic waves that have propagated through the specimen by the excitation of the # 1 vibrator 1, # 2 vibrator 2, and # 3 vibrator 3 and are reflected from the internal flaw, bottom surface, etc. are again # 1 to # 3 vibrations. The signals are supplied to the reception gate circuit 41 through the reception protection circuit 21 and the reception circuit 40 via the elements 1 to 3.

In this # 3 transmission / reception cycle, the timing control circuit 80 supplies only the reception gate signal of the time width t ₃ to the reception gate circuit 41 after the elapse of the times t ₁ and t ₂ immediately after the end of the transmission pulse (FIG. 2). (See (g)).
Wherein said time t _1, t _2, the # 1, the same as the time t _1, t ₂ of # 2 receive the gate signal, respectively are 6,78Myuesu, time width t ₃ is obtained as follows.
Similarly to the above, the longitudinal wave sound velocity v is about 5900 m / s, and the time t required for the longitudinal wave to propagate through a distance of 120 mm in the round trip is t = 120 mm / 5900 ms≈20.34 μs, and t ₃ = t− (T ₁ + t ₂ ) ≈ (20.34-13.56) μs≈6.78 μs.
In actual device design, it is preferable to terminate the # 2 transmission / reception signal after the generation of the # 3 transmission / reception gate signal so that no signal break occurs between the two gate signals.

Based on the supplied # 3 reception gate signal, the reception gate circuit 41 extracts a reception video signal having a depth of 40 mm to 60 mm of the test material from the input video signal and supplies it to the A / D converter 50. . The A / D converter 50 converts the amplitude value of the input video signal into digital data of a predetermined number of bits for each sampling clock signal supplied from the timing control circuit 80, as in the # 1 and # 2 transmission / reception periods. Are converted and output sequentially.
Series digital data when output from the A / D converter 50 is controlled by the write-read control circuit 53, # 1 memory made of data writing in the # 1, # 2 transceiver periodically via a switch S ₃ The test material in 51 is sequentially written to each address set for each unit depth from 40 mm to 60 mm in depth.
At this time, boundary identification data indicating the boundary between the data group in the flaw detection range in the # 2 transmission / reception cycle and the data group in the flaw detection range in the # 3 transmission / reception cycle is provided in the memory.

In this way, at the end of the # 3 transmission / reception cycle, all data obtained by quantizing the received signals from the entire flaw detection range from the surface to the bottom surface of the test material is unit depth (A / D converter 50 is stored at each address set for each distance (distance that ultrasonic waves can reciprocate in the period of the sampling clock). When the # 3 transmission / reception cycle ends, the #i transmission cycle ends.
In this # 3 transmission / reception cycle, the write / read control circuit 53 also stores the data stored in the previous # (i-1) transmission / reception cycle from the # 2 memory 52 based on the read control signal from the flaw detection result evaluation means 60. among the time-series digital data of all flaw detection range to the bottom from the surface of the test material, it reads echo data to be required, and supplies the inspection result evaluation unit 60 via a switch S _4.

FIG. 4 is an explanatory diagram of beams of the array-type ultrasonic probe according to the first and second embodiments of the present invention, and (a), (b), and (c) of FIG. 4 are # 1, # 2, and #, respectively. The case where the transducer size is a circular transducer having a diameter of 7 mm, 10 mm, and 14 mm in three transmission / reception cycles is shown, and the ultrasonic frequency generated by each transducer is shown as 5 MHz.
Incidentally, x ₀ figure near field limit distance, [psi ₀ is directivity angle, in FIG. (A), (b), in (c), x ₀ is approximately 10.4 mm, 21.2 mm, 41 0.5 mm, and ψ ₀ is about 11.8 °, 8.28 °, and 5.9 °. Also, t ₁ , t ₂ , and t _{3 in the} figure are # 1, # 2, and # 3 reception gate times, and flaw detection can be performed with high sensitivity by the respective transducer areas (a), (b), and (c). It is used to extract received signals from each flaw detection range (vibrator˜20 mm, 20 mm˜40 mm, 40 mm˜60 mm).

In the first embodiment of the present invention, the transducer area is changed in three stages as shown in FIG. 4 using three transmission / reception cycles, and the entire flaw detection range is divided into three in advance, one of each transducer area. Although one flaw detection range is assigned, the conventional flaw detection method performs flaw detection over the entire flaw detection range using a single ultrasonic probe (that is, the same transducer area).
Here, the sound field size and sensitivity in the conventional flaw detection method in which flaw detection is performed using the commercially available probe 5Z10 and the flaw detection method of the present invention are compared.
Now, as a test steel material, a flat bottom hole with a diameter of 2 mm is processed into a steel plate with a thickness of 100 mm to 17 mm, 30 mm and 55 mm from the surface. As an example of flaw detection of this steel plate with a conventional probe 5Z10, the detection sensitivity of the three processed holes was +1 dB when the depth from the surface was 17 mm, 0 dB when 30 mm, and -7 dB when 55 mm. The decrease in sensitivity at a depth of 55 mm is caused by the fact that the beam becomes thick and the effective area of the vibrator increases at a depth of 40 mm or more as shown in FIG. The sensitivity difference within this range is 8 dB.

In the first embodiment, a circular plane flaw having a depth of 17 mm from the surface is inspected by a vibrator having a diameter of 7 mm in FIG. In FIG. 4A, the sound field is already a far-field sound field at a distance of 17 mm from the vibrator, but the effective dimension of the ultrasonic beam is substantially equal to the diameter of the vibrator. In this case, the height of the reflected echo from the flaw is proportional to the ratio between the flaw area and the vibrator area. In the conventional flaw detection method, flaw detection is performed with a vibrator having a diameter of 10 mm shown in FIG. 4B, and the vibrator area (78.5 mm ² ) in FIG. 4B is the vibrator area (38.5 mm ² ) in FIG. Twice as much.
Therefore, the height of the flaw echo when a circular plane flaw having a depth of 17 mm is detected by a vibrator having a diameter of 7 mm is almost twice (+6 dB) the height of the flaw echo when being detected by a vibrator having a diameter of 10 mm. Since the first embodiment has higher sensitivity, even fine flaws can be detected.
Further, the position at a distance of 17 mm from the vibrator is a short-distance sound field with a large variation in sound pressure in FIG. 4B, but a long-distance sound field with a small variation in sound pressure in FIG. 4A. Therefore, stable flaw detection is possible.

  For flaw detection with a circular flat surface flaw 30 mm deep from the surface, both the first embodiment and the conventional flaw detection method use the same transducer with a diameter of 10 mm, so both are flaw detection in a far-field sound field and have the same detection sensitivity. You may think.

In the first embodiment, flaw detection is performed on a circular plane flaw having a depth of 55 m from the surface by the vibrator having a diameter of 14 mm in FIG. In FIG. 4C, the sound field is already a far field at a distance of 55 mm from the transducer, but the effective dimension of the ultrasonic beam is approximately equal to the diameter of the transducer.
In the conventional flaw detection method, flaw detection is performed by a vibrator having a diameter of 10 mm shown in FIG. 4B, and the beam diameter is increased to about 16 mm at a depth of 55 mm. The effective area of the ultrasonic beam in FIGS. 4B and 4C at this position is about 201 mm ² and 154 mm ² . Accordingly, the height of the flaw echo detected by a circular plane flaw having a depth of 55 mm by a vibrator having a diameter of 14 mm is approximately 1.3 times (+2.5 dB) when detected by a vibrator having a diameter of 10 mm. The sensitivity is better.

As described above, in the first embodiment, for each flaw detection range obtained by dividing the whole flaw detection range into a plurality, the setting is made so as to combine the vibrator areas that enable the most sensitive flaw detection in each flaw detection range. High-sensitivity flaw detection can be performed as compared with the conventional flaw detection method using a single transducer area.
Most of the divided flaw detection ranges (in this example, about 80%) are far-field sound fields, but the effective dimensions of the ultrasonic beam are close to the transducer diameter (the range in which the beam does not become thick). Therefore, stable flaw detection can be performed.

When the entire range from the surface to the bottom surface of the test material is displayed or recorded together, the detection sensitivity difference between the plurality of flaw detection ranges is reduced, and detection is almost uniform over the entire flaw detection range. You may want to do it depending on the sensitivity. In such a case, in the first embodiment, this is realized by one or both of the following (1) and (2).
(1) Almost uniform detection sensitivity can be obtained over the entire flaw detection range by combining the combination of the number of transducer area change stages and the flaw detection ranges corresponding to each of the flaw detection ranges with the highest sensitivity for each flaw detection range so far. Change to a combination.
For example, even in a flaw detection range of 20 mm from the surface, a transducer having a diameter of 10 mm is used (the use of a transducer having a diameter of 7 mm is stopped), and flaw detection is performed with a two-step area. That is, if a flaw is detected from a surface to a depth of 40 mm by a vibrator having a diameter of 10 mm and a flaw is detected from a depth of 40 mm to 60 mm by a vibrator having a diameter of 14 mm, the sensitivity from the surface to a depth of 55 mm is within 2.5 dB. Flaw detection can be performed on the difference.

(2) The flaw detection result evaluation means 60, which will be described later, corrects flaws of the same size so that they become echoes of the same height for each flaw detection range, and displays or records the corrected data.
As a test material for calibration, a flaw (such as a flat bottom hole) having the same dimensions is previously provided for each flaw detection range of the test material. Then, when calibrating this device with this test material, the flaw echo height is measured for each flaw detection range, and the correction coefficient for each flaw detection device is such that these echo heights are almost the same height over the entire flaw detection range. And the correction coefficient is stored in the inside.
At the time of actual flaw detection, correction is performed for each flaw detection range with respect to the measured flaw echo height using the correction coefficient stored at the time of calibration.

Next, evaluation, display, and print operation of the flaw detection result of # (i-1) transmission / reception cycle in #i transmission / reception cycle will be described.
At the start of the #i transmission / reception cycle, in this example, the # 2 memory 52 stores time-series digital data of flaw detection results from the surface to the bottom surface of the test material in the # (i-1) transmission / reception cycle. since, upon entering the # 1 transceiver period, flaw detection result evaluation unit 60 controls the write-read control circuit 53, the time series digital data, read from the # 2 memory 52 via a switch S _4, once the self Then, the following processes (1) and (2) are performed in parallel.

(1) As a first process, the flaw detection result evaluation means 60 converts the stored time-series data into an analog signal via the D / A converter 61 and displays it as an echo waveform on the A scope of the display device 62. Let
There are two methods of displaying the echo waveform: a case where the display range is limited for display for each flaw detection range, and a case where the entire flaw detection range from the front surface to the bottom surface is displayed collectively. In the former case, since the flaw waveform can be enlarged and displayed by local scanning, a method of displaying high-sensitivity data for each flaw detection range as it is (here, referred to as method A) may be used, but in the latter case, A method of correcting and displaying data (herein referred to as method B) is generally used so that the detection sensitivity is substantially uniform over the entire flaw detection range. Therefore, in the present embodiment, the method A or the method B is automatically selected as the display sensitivity by selecting the display range.

When the method A is selected, it is not necessary to correct the data amplitude value, so that the flaw detection result evaluation means 60 directly synchronizes the time-series digital data stored therein with the scanning speed of the display device 62. What is necessary is just to output to the / A converter 61.
Further, when the method B is selected, the data amplitude value needs to be corrected. Therefore, the flaw detection result evaluation means 60 distinguishes each flaw detection range in advance (for example, provides boundary data) and stores it inside itself. The time series digital data is multiplied by the correction coefficient for each flaw detection range acquired at the time of calibration, and the data of the multiplication result is output to the D / A converter 61 in synchronization with the scanning speed of the display device 62.
The echo waveform display process (1) may be performed only once in the # 1 transmission / reception cycle if the display device 62 has a video memory. However, if the display device 62 does not have a video memory, the display is continued. Therefore, the flaw detection result evaluation means 60 performs all scanning times of the # 1, # 2, and # 3 transmission / reception periods.

(2) Further, the flaw detection result evaluation means 60 performs the following second process in parallel with the process (1) by, for example, a time division process using a scanning blanking period of the display device 62 or the like.
That is, as a second process, the flaw detection result evaluation means 60 estimates the flaw size (diameter, etc.) for all flaw data included in the stored time-series digital data, and calculates the flaw position (depth) and size. Data is output to the printing device 70 (or a recorder, etc.).
In the single probe method, if the flaw is a flat flaw in the far field, the echo height from the flaw is the ratio of the flaw area to the effective area of the transducer (meaning the effective area of the ultrasonic beam). Therefore, if the relationship between the two is obtained in advance using a test material or the like, the flaw size can be calculated from the effective area of the vibrator and the height of the echo.

That is, a plurality of flat bottom holes having a known hole diameter are processed and provided in advance for each flaw detection range of the test material. When the apparatus is calibrated, a known hole is provided for each of the three flaw detection ranges (# 1, # 2, # 3 flaw detection ranges) in which the area of the vibrator is changed in three stages (A ₁ , A ₂ , A ₃ ). The flaw echo height (F ₁ , F ₂ ,...) With respect to the diameter (φ ₁ , φ ₂ ,...) Is measured. Then, the echo heights F ₁ , F ₂ ,... Corresponding to the hole diameters φ ₁ , φ ₂ ,... Measured for each flaw detection range are stored in the flaw detection result evaluation means 60 as echo height reference values. . The flaw echo height obtained for each flaw detection range during actual flaw detection can be obtained by estimating the flaw diameter using the reference value for the known hole diameter.
The flaw detection result evaluation means 60 uses the time-series digital data stored inside itself in a time zone that does not overlap with the processing of (1) within the # 1 to # 3 transmission / reception cycle, and estimates and estimates the flaw size. Data is output to the printing device 70.

Embodiment 2
In the second embodiment, the transducer area of the ultrasonic probe can be changed to a plurality of stages (3 in this embodiment, but generally N), and one stage for each ultrasonic transmission / reception cycle. The transducer area is sequentially changed to the N stages to transmit / receive ultrasonic waves to / from the test material to acquire reception signals in a predetermined flaw detection range, and the acquired reception signals for each transmission / reception period in a plurality of N ultrasonic transmission / reception periods. Are respectively quantized and stored as a plurality of N time-series data. The stored N time-series data are compared for each time-series position, and data having the maximum amplitude value is extracted as reception result data at the corresponding time-series position.
As a result, the echo obtained with the maximum sensitivity can be automatically extracted from a plurality of N echoes for the same flaw.

FIG. 5 is a block diagram of an ultrasonic flaw detector according to Embodiment 2 of the present invention, and FIG. 6 is a timing chart for explaining the operation of the apparatus of FIG.
First, differences between FIGS. 5 and 1 and differences between FIGS. 6 and 2 will be described.
In FIG. 5, the timing control circuit 80 </ b> A supplies a single type of reception gate signal that can extract the reception signals in the entire flaw detection range from the surface to the bottom surface of the test material to the reception gate circuit 41. I have to.
The # 1 memory 51A and the # 2 memory 52A are each provided with a capacity capable of storing time-series digital data of the entire flaw detection range from the surface to the bottom surface of the test material for three transmission and reception cycles.
The processing contents of the flaw detection result evaluation means 60 are different from those in the first embodiment, but when viewed as an apparatus such as a personal computer, the same apparatus as in the first embodiment may be used.
The above is the difference between FIG. 5 and FIG. 1, and the other devices in FIG. 5 are the same as those in FIG.
In FIG. 6, instead of the # 1, # 2, and # 3 reception gate signals (e), (f), and (g) of FIG. 5, all the common reception gate signals (e) (time width is t) are used. The timing is the same as that shown in FIG.

In the second embodiment, operations different from those in the first embodiment will be mainly described.
The transducer area of the ultrasonic probe # 1, # 2, and sequentially incremented by one step every # 3 transmit and receive periods (in this example, 38.5 mm ^2, 78.5 mm ^2, as 153.9Mm ²⁾ The operation of transmitting / receiving ultrasonic waves to / from the test material is the same as in the first embodiment (see FIGS. 6A to 6D).
For each reception period, the timing control circuit 80A applies a time width to the reception signal reflected from the test material and input to the reception gate circuit 41A via the vibrator, the reception protection circuit 21, and the reception circuit 40. A common reception gate signal of t is supplied (see (e) of FIG. 6).
Here, the time width t is a time t required for the longitudinal ultrasonic wave to reciprocate a distance of 60 mm in depth from the surface so as to cover the entire flaw detection range from the surface to the bottom surface of the test material. It is determined as 20.34 μs.
Therefore, the reception gate circuit 41A outputs a reception signal in the entire flaw detection range from the surface to 60 mm for each transmission / reception cycle.

A / D converter 50, the analog signal output of the receiving gate circuit 41A for each sampling clock is converted into quantized data, via a switch S _3, the memory (Figure 5 which is not currently performing a read operation When supplied to the # 1 memory 51A), the write / read control circuit 53 # 1, # 2, # 3 provided in the # 1 memory 51A corresponding to the # 1, # 2, and # 3 transmission / reception cycles, respectively. The time-series digital data obtained by receiving in the corresponding (for example, # 1) transmission / reception cycle is stored in the corresponding (for example, # 1) cycle memory.
When three transmission / reception cycles are completed in this way, in the # 1 memory 51A, three time-series digital results obtained by flaw-detecting the entire flaw detection range of the specimen by changing the transducer area in three stages. Data is stored. The stored data naturally includes bottom echo data.

In the second embodiment, when the # 1 transmission / reception cycle of the #i transmission / reception cycle starts, the flaw detection result evaluation means 60 performs the following processes (1), (2), and (3).
(1) As a first process, the flaw detection result evaluation means 60 is stored in the # 1, # 2, # 3 cycle memory in the # 2 memory 52A as flaw detection result data of # (i-1) transmission / reception cycle. The three time-series digital data are read out via the switch S ₄ , and the three data are compared for each time-series position, and the data with the highest amplitude value is represented as representative data (herein referred to as reception result data). And the extracted data is stored in its own internal memory.
At this time, if a 2-bit code for identifying which transmission / reception period (that is, how many transducer areas) data is extracted is added to the head of the reception result data, sensitivity correction and scratches are later made. This is convenient when measuring dimensions.

The physical meaning of extracting the data with the highest amplitude value among the three data at the same time series position was obtained by performing the measurement three times for the same flaw in the test material. That is, the echo data obtained with the maximum sensitivity is automatically extracted from the three echo data.
As described above with reference to FIG. 4, the high-sensitivity echo extracted in this manner results in a small diameter of the transducer depending on the short distance, medium distance, and long distance in the depth direction from the transducer. In the case of the medium diameter and large diameter, the echoes will be extracted sequentially, but with the diameter of the transducer, the boundary (for example, the boundary between the short distance and the medium distance) where the flaw is detected is compared by sensitivity comparison. It will be determined automatically.
Therefore, in the second embodiment, unlike the first embodiment, it is not necessary to set a flaw detection range corresponding to each transducer area in advance.
When the reception result data extraction process (1) is completed, the flaw detection result evaluation means 60 immediately performs the following processes (2) and (3) in parallel as in the first embodiment.

(2) Next, the flaw detection result evaluation means 60 converts the time series digital data over the entire flaw detection range extracted as the maximum sensitivity data into an analog signal via the D / A converter 61, and on the A scope of the display device 62 Is displayed as an echo waveform.
As in the case of the first embodiment, this echo waveform display method limits the display range (as a local scan) and enlarges and displays the flaw waveform, so that the maximum sensitivity extracted in the process of (1) can be obtained. Either method A for displaying data with the same sensitivity, or method B for displaying all the flaw detection ranges at once, so that the sensitivity of each data is corrected so that the detection sensitivity is almost uniform over the whole flaw detection range. Is selected, the processing by the selected method is performed. Since the specific sensitivity correction method, the data output timing to the display device 62, and the like are the same as in the case of the first embodiment, a duplicate description is omitted.

(3) The flaw detection result evaluation means 60 performs the following third process in parallel with the process (2).
That is, as a third process, the flaw detection result evaluation means 60 estimates the flaw size (diameter, etc.) for all flaw data included in the time-series digital data extracted and stored, and the flaw position (depth). ) And dimensional data are output to the printing apparatus 70 (or recorder, etc.).
In the second embodiment, since the bottom surface echo height data for each transmission / reception cycle is also stored, for example, F / which calculates the scratch diameter from the ratio of the height (F) of the scratch echo and the height (B) of the bottom echo. The B method can be used (see, for example, the Japan Nondestructive Inspection Association, Ultrasonic Flaw Test II, February 1989, p109 for the F / B method).
As in the case of the first embodiment, the calibration data is acquired in advance using the test material, and the transmission / reception storing the height of the flaw echo and the time series data from which the reception result data corresponding to the flaw is extracted is stored. The size of the flaw can be evaluated based on the effective area of the ultrasonic beam at the flaw detection position corresponding to the period.

In the F / B method, it is effective to acquire calibration data in advance using a test material as in the case of the first embodiment.
That is, the test material is previously provided with a plurality of flat bottom holes or the like having a known hole diameter at a plurality of positions at equal intervals from the surface of the test material. When the apparatus is calibrated, the area of the vibrator is changed in three stages (A ₁ , A ₂ , A ₃ ), and a flaw with respect to a known hole diameter (φ ₁ , φ ₂ ,...) For each of the plurality of positions. The echo height (F ₁ , F ₂ ,...) And the bottom echo height (B ₁ , B ₂ ,...) Are measured. The measured values of the echo heights corresponding to the respective hole diameters are stored internally as reference values, and further theoretical flaws obtained from the relational expression with the F / B and the flaw diameter (d) described in the above-mentioned literature and the like. Find the error between the diameter and the actual hole diameter.
The diameter can be accurately calculated without using the reference value and error with respect to the flaw echo height and the bottom surface echo height obtained during actual flaw detection.

  The flaw detection result processing means 60 first completes the process (1) within the # 1 to # 3 transmission / reception cycle, and then uses the data processed according to (1) to (2) and (3) These processes are performed in parallel by time division so that the time zones do not overlap each other.

  In the ultrasonic probe shown in FIG. 3, the # 1 transducer, which is the central transducer, is circular, and the # 2, # 3 transducers, which are peripheral transducers arranged at positions surrounding the central transducer. Is a concentric ring shape, but the present invention is not limited to this shape. For example, the central vibrator may be an ellipse, a quadrangle, a hexagon, an octagon, or the like, and the peripheral vibrator may have a shape that surrounds the central vibrator and sequentially increases the vibrator area.

1 is a configuration diagram of an ultrasonic flaw detector according to Embodiment 1 of the present invention. FIG. It is a timing chart for demonstrating operation | movement of the apparatus of FIG. It is a block diagram of the array type ultrasonic probe which concerns on Embodiment 1, 2 of this invention. It is explanatory drawing of the beam of the array type ultrasonic probe which concerns on Embodiment 1, 2 of this invention. It is a block diagram of the ultrasonic flaw detector which concerns on Embodiment 2 of this invention. It is a timing chart for demonstrating operation | movement of the apparatus of FIG. It is explanatory drawing of the ultrasonic beam shape by a circular vibrator. It is a figure which shows the structural example of the ultrasound diagnosing device shown by the well-known literature.

Explanation of symbols

1 # 1 transducer 2 # 2 transducer 3 # 3 transducer 4 spacer 5 spacer 6 # 1 transducer electrode 7 # 2 transducer electrode 8 # 3 transducer electrode 9 common electrode 10 array type ultrasonic probe 20 vibration Child selection circuit 21 Reception protection circuit 30 Transmission circuit 40 Reception circuit 41, 41A Reception gate circuit 50 A / D converter 51, 51A # 1 memory 52, 52A # 2 memory 53 Write / read control circuit 60 Flaw detection result evaluation means 61 D / A converter 62 Display device 70 Priton device

Claims (5)

  An array probe having a plurality of transducers can change the transducer area for transmitting and receiving ultrasonic waves to a plurality of N stages, and the transducer area is sequentially changed to N stages one by one for each ultrasonic transmission / reception cycle. The ultrasonic wave is transmitted / received to / from the test material to acquire a reception signal in a predetermined flaw detection range, and the acquired reception signal for each transmission / reception period in each of a plurality of N ultrasonic transmission / reception periods is quantized to obtain a plurality of N time-series data. Ultrasonic flaw detection characterized in that the plurality of N time-series data stored are compared for each time-series position, and data having the maximum amplitude value is extracted as reception result data at the corresponding time-series position. Method.   When displaying or recording the reception result data within the predetermined flaw detection range obtained by comparing the plurality of N time-series data for each time-series position and sequentially extracting the data having the maximum amplitude value, Display or record with the same sensitivity without changing the sensitivity of the reception result data at the extraction position, or change the sensitivity of the reception result data at each extraction position so that the sensitivity is almost uniform in the predetermined flaw detection range. The ultrasonic flaw detection method according to claim 1, wherein display or recording is performed.   The N time series data is compared for each time series position, and the detection is performed as the evaluation of the flaw detected from the reception result data of the predetermined flaw detection range obtained by sequentially extracting the data having the maximum amplitude value. The flaw size is evaluated based on the ratio between the height of the echo of the flaw and the height of the bottom echo in the time-series data from which the reception result data corresponding to the flaw is extracted, or the flaw echo height detected and the flaw The flaw size is evaluated based on the effective area of the ultrasonic beam at the corresponding flaw detection position in the transmission / reception cycle in which the time-series data from which the reception result data corresponding to is stored is stored. Ultrasonic flaw detection method. An array probe having a central transducer and one or more peripheral transducers arranged at positions surrounding the central transducer;
By adding one or more peripheral transducers to the central transducer of the array probe and one or more peripheral transducers to the central transducer, the transducer area is sequentially increased to N stages for each ultrasonic transmission / reception cycle. An ultrasonic transmission / reception means for transmitting / receiving ultrasonic waves to / from a test material,
In a plurality of N ultrasonic transmission / reception cycles, the reception signals within a predetermined flaw detection range acquired by the ultrasonic transmission / reception means for each transmission / reception cycle are respectively quantized and stored as a plurality of N time-series data. An ultrasonic flaw detector comprising: reception result data extraction means for comparing data for each time series position and extracting data having the maximum amplitude value as reception result data at the corresponding time series position. The reception result data extraction means inputs reception result data extracted for each time series position from a plurality of N time series data, and outputs the reception result data for each time series position as the amplitude value of the reception sensitivity. Or a sensitivity change selection means for changing and outputting an amplitude value so that the sensitivity is substantially uniform in the predetermined flaw detection range;
The reception result data extraction means inspects reception result data extracted for each time series position from a plurality of N time series data, and as an evaluation of the flaw detected from the reception result data, the echo height of the detected flaw, The size of the flaw is evaluated based on the ratio with the height of the bottom echo in the time-series data from which the reception result data corresponding to this flaw is extracted, or the echo height of the detected flaw and the reception result data corresponding to the flaw 5. A flaw size evaluation means for evaluating a flaw size based on an effective area of an ultrasonic beam at a corresponding flaw detection position in a transmission / reception cycle in which time-series data extracted is stored is added. Ultrasonic flaw detector.

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