JP2004150875A - Method and system for imaging internal flaw using ultrasonic waves - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve resolution in the case of imaging internal flaws, using a method of C-scan immersion ultrasound flaw detection. <P>SOLUTION: In this method, beam path values of echoes indicative of flaws are measured, while scanning an ultrasonic probe 10 for transmitting / receiving focused beams, and a flaw image is composited from the beam path values, measured at a large number of points. The directivity of the ultrasonic beam is also incorporated, when the compositing of the flaw images is carried out. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic flaw detection method, which is a type of non-destructive inspection method, and provides high-resolution images of internal defects that can be present in variously shaped objects such as plates, tubes, and cylinders made of metal, resin, and the like. The present invention relates to a method and an apparatus for imaging an internal defect by ultrasonic waves to be displayed.
[0002]
[Prior art]
It is a very important technical task for the manufacturing industry to detect non-destructively internal defects of products of various shapes such as plates, tubes, columns, and the like made of metal, resin, and the like, and to further investigate properties of the internal defects.
[0003]
The purpose is to inspect the internal quality of the product in detail, prevent the delivery of products with harmful internal defects to consumers, investigate the problems of manufacturing technology from the nature of the internal defects, and generate internal defects Not to establish a manufacturing technology. Representative examples of internal defects include the inclusion of foreign substances, voids, and internal cracks. For example, in the case of steel products, the content of foreign substances is often an oxide of aluminum or calcium, and these are called nonmetallic inclusions.
[0004]
Among such non-destructive inspection methods, which are collectively called a nondestructive inspection method, the ultrasonic flaw detection method is suitable for the inspection of the inside of a product. As described above, the inspection targets include inclusion of foreign substances, voids, and internal cracks, and the detection of these internal defects is referred to as flaw detection.
[0005]
Ultrasonic waves used in ultrasonic flaw detection are roughly classified into longitudinal waves and transverse waves. Longitudinal waves are compressional vibrations (also referred to as compressional waves) transmitted through an object or medium as well as sound waves transmitted through air or water. This longitudinal wave is often used when a flaw is detected by propagating ultrasonic waves perpendicularly to the surface of the subject (referred to as vertical flaw detection).
[0006]
Transverse waves are the propagation of shear strain and are often used for oblique flaw detection of welds and the like.
[0007]
Generally, when transmitting ultrasonic waves to a subject, an electric pulse is applied to the piezoelectric vibrator to generate high-frequency pulse vibration, and this vibration is guided to the subject via an appropriate couplant (water, oil, etc.). It is performed by. The reception of the ultrasonic wave is performed in a process reverse to the transmission, and a voltage or a current generated by the vibration received by the piezoelectric vibrator is observed by an appropriate electric device. A sensor that has a built-in piezoelectric vibrator and oscillates ultrasonic waves by a received electric pulse is called an ultrasonic transmitter, and a sensor that has a built-in piezoelectric vibrator and converts received vibration into an electric signal is called an ultrasonic receiver. There is no special difference in the structure, and a sensor having a built-in piezoelectric vibrator can be generally used for transmitting and receiving ultrasonic waves. In many cases, the sensor is used for both transmitting and receiving ultrasonic waves, and at this time, this sensor is referred to as an ultrasonic transceiver. The names of the ultrasonic transmitter, the ultrasonic receiver, and the ultrasonic transmitter / receiver are names given from the function of the sensor, but the names of the ultrasonic probe and the ultrasonic probe in the sense of a tool for performing an exploration. Are often used.
[0008]
The ultrasonic flaw detection method using an ultrasonic transmitter / receiver using a piezoelectric vibrator is a direct contact method in which an ultrasonic transmitter / receiver is applied to a subject via oil or the like to transmit / receive ultrasonic waves, and a medium such as water is interposed. The method is broadly divided into a liquid immersion method for transmitting and receiving ultrasonic waves to and from a subject (a water immersion method when the medium is water). In the immersion method,
(1) The ultrasonic transceiver does not come into contact with the subject.
(2) It is easy to keep the incident intensity of the ultrasonic wave on the subject constant.
(3) By focusing an ultrasonic beam using an acoustic lens or a spherical vibrator, measurement with high spatial resolution is possible.
The liquid immersion method is preferably used when the inside of the subject is evaluated in detail with high spatial resolution.
[0009]
Taking the water immersion method (one form of the liquid immersion method) shown in FIG. 9 as an example of the prior art, the principle of ultrasonic flaw detection will be briefly described below. FIG. 9 shows that an object to be inspected is immersed in water, ultrasonic waves are transmitted from the ultrasonic probe 111 to the object 110 via water, and reflected waves (echoes) from the surface and the inside of the object 110 are reflected in water. 1 shows a general configuration of a water immersion flaw detection method for detecting a defect by receiving an ultrasonic probe 111 via the interface. In this case, the ultrasonic probe 111 is also used for transmitting and receiving ultrasonic waves. When the ultrasonic wave emitted from the ultrasonic transducer is applied to the subject, the ultrasonic wave is reflected on the surface and returns to the ultrasonic transducer through the medium again (hereinafter, the reflected wave from the subject surface is referred to as a surface echo). ). On the other hand, at the same time, ultrasonic vibration occurs on the surface of the subject on which the ultrasonic wave has entered, and the vibration propagates into the subject. If there is no defect in the object, the propagated ultrasonic vibration is applied to the surface on the opposite side of the object (for example, the back surface of the plate if ultrasonic waves are applied to the surface of the plate. , Which is also referred to as a bottom surface), is reflected at the bottom surface, propagates in the subject in the opposite direction, returns toward the surface of the subject, passes through the medium again, and transmits and receives the ultrasonic transceiver. (Hereinafter, this reflected wave is referred to as a bottom surface echo).
[0010]
If there is any defect in the object, the ultrasonic wave incident on the object is reflected by the defect, returns toward the surface of the object, passes through the medium, and returns to the ultrasonic transmitter / receiver (hereinafter referred to as defect echo). ). The timing at which the defective echo returns to the ultrasonic transmitter / receiver is earlier than that of the bottom surface echo in accordance with the difference in the length of the propagation path (hereinafter, referred to as the beam path). Detecting this defect echo is the basic principle of ultrasonic flaw detection.
[0011]
At this time, by using an ultrasonic lens that can focus the ultrasonic beam at one point using an acoustic lens or a spherical oscillator as an ultrasonic transceiver, and by using a thin portion where the ultrasonic beam is focused, measurement is performed. Higher resolution can be achieved.
[0012]
There is a C-scan ultrasonic flaw detection method (see Non-patent Document 1) as a method for two-dimensionally scanning an ultrasonic transmitter / receiver for transmitting / receiving a focused beam with respect to an object and imaging an internal defect of the object with high resolution. This flaw detection method is often used for detecting internal defects that require high resolution.
[0013]
[Non-patent document 1]
Edited by Japan Non-Destructive Inspection Association, "Ultrasonic Testing II", Japan Non-Destructive Inspection Association (2000), p. 151-152
[0014]
Generally, the C scan flaw detection method has a configuration in which a defect echo is extracted by a gate circuit 114 and the amplitude of the defect echo is detected by a peak detector 115, as shown in FIG. It is a dimensional map. As described above, the conventional C-scan flaw detection method is characterized in that amplitude information of a defect echo is used.
[0015]
Hereinafter, problems of the conventional C-scan flaw detection method will be described with reference to FIG.
[0016]
First problem: As shown in FIG. 10, the focused beam has a large beam diameter at a position other than the focal point, the resolution is reduced at a position other than the focal point, and various depths of the subject ( It is difficult to visualize the internal defect existing in the direction (z direction in FIG. 10) at a uniform resolution.
[0017]
Second problem: In imaging an internal defect of an extremely thick material, it is necessary to focus a focused beam on a deep position of the subject in order to improve the resolution of a defect image at a deep position of the subject. Assuming that the wavelength of the ultrasonic wave is λ, the short-range sound field limit distance X of the ultrasonic transducer which is a flat plate having a diameter D ₀ Is represented by the following equation (1).
[0018]
X ₀ = D ² / (4 · λ) (1)
[0019]
The near-field limit distance is the natural focus, which is the distance at which the phases of the ultrasonic waves radiated from the individual element points of the vibrator are almost aligned and no interference occurs (without focusing by a lens or the like). Even if the phases match.) Therefore, the focus of the focused beam is at the near-field limit distance X ₀ Unless the position is set closer to the probe, a sufficient focusing effect cannot be obtained. Practically, the focal length F of the focused beam is X ₀ It is said that it is necessary to be shorter than / 2.
[0020]
From the above, to set the focus of the focused beam at a deep position of the subject, X ₀ It must be understood that it is necessary to increase the diameter of the ultrasonic vibrator. However, in order to electrically drive the ultrasonic vibrator to emit ultrasonic pulses, it is necessary to prevent the electric resistance of the ultrasonic vibrator from becoming too low, and the diameter of the ultrasonic vibrator is limited. Exists. Therefore, it is technically difficult to set the focus of the focused beam at a deep position of the extremely thick material. For example, to image an internal defect of a steel object using a frequency of 2 MHz, a depth of about 80 mm is a limit. is there. Therefore, it is difficult to visualize an internal defect at a deeper position with a high resolution.
[0021]
In addition to the above-described C-scan flaw detection method, there is an aperture synthesis method as a technique aiming at high-resolution imaging. The principle of aperture synthesis will be described by taking as an example a case where defect imaging is performed by bringing the transducer array shown in FIG. 11 into contact with the surface of the subject 110. Ultrasonic waves are transmitted from each transducer of the transducer array to detect a defect echo, and the beam path of the defect echo in the subject 110 is measured from the time from transmission of the ultrasonic wave to reception of the echo. Since the ultrasonic waves transmitted and received from the individual transducers 120p (p = 1, 2,...) Are spatially spread, the beam path of the echo detected by the transducer 120p is Wp (p = 1, 2, 1). , ‥‥), there is a reflection source somewhere in the directivity range of the ultrasonic wave transmitted and received by the transducer 120 p in the hollow sphere Sp (p = 1, 2, ‥‥) having a radius Wp. . When the echo is detected using all the transducers and the intersection of the hollow sphere Sp is obtained, the intersection becomes a defect image. FIG. ₆ , 120 ₈ , 120 ₁₀ , 120 _Thirteen , 120 _Fifteen 3 shows a state in which a defect image is synthesized from the beam path of the detected echo.
[0022]
Furthermore, if the transducer array 120 is scanned in a direction perpendicular to the plane of the paper (scanning stroke is Ls), a three-dimensional defect image can be obtained. When the total length of the transducer array is L, this method corresponds to transmitting an ultrasonic wave from each point of the transducer having a large size of L × Ls and receiving an echo to obtain a defect image. The method has a feature that high resolution equivalent to defect imaging by a large vibrator can be obtained without restriction on the vibrator diameter due to matching of electric impedance. Patent Documents 1 and 2 are cited as prior art documents of this technology.
[0023]
[Patent Document 1]
JP-A-7-49398
[Patent Document 2]
JP-A-10-142201
[0024]
[Problems to be solved by the invention]
However, in this method, as shown in Patent Document 1, in order to detect a defect echo over a wide range, a wide directivity angle is required for the ultrasonic transceiver, and the ultrasonic beam is focused on a narrow area. This technique is incompatible with the C-scan flaw detection method in which the measurement is performed by using a conventional method.
[0025]
Therefore, the following items have become extremely important issues in imaging internal defects by ultrasonic waves using a focused beam.
[0026]
(1) Imaging is performed at a uniform resolution regardless of the depth at which internal defects exist.
[0027]
(2) Imaging is performed with high resolution even when the plate thickness is large and the depth of the focused beam cannot be reached.
[0028]
In addition, since the above (2) is equivalent to the case of imaging an internal defect located beyond the focus in (1), the problem is ultimately summarized in (1).
[0029]
The present invention has been made in view of such circumstances, and it is an object of the present invention to enable imaging with uniform resolution regardless of the depth at which internal defects exist.
[0030]
[Means for Solving the Problems]
The present invention, water is interposed between the water immersion type ultrasonic probe and the subject, while scanning the ultrasonic probe relative to the subject, transmitting ultrasound toward the subject, In a method of imaging an internal defect by using an ultrasonic wave that receives a reflected wave (echo) from an internal defect of the subject and visualizes the internal defect, an ultrasonic focused beam is transmitted from the point focusing type ultrasonic probe toward the subject. Then, a reflected wave (echo) from the internal defect of the subject is received, the beam path of the defect echo is recorded at each measurement point, and the reconstruction of the internal defect image is performed. The image is divided into microelements of the same size, microelements that can be a defect echo source are selected from the beam path measured at each measurement point, and the shading and color are applied to the microelements according to the number of times that they are selected repeatedly. To indicate the internal defect of the subject More it is obtained by solving the above problems.
[0031]
According to the present invention, water is interposed between the water immersion type ultrasonic probe and the subject, and the ultrasonic probe is scanned relative to the subject while transmitting ultrasonic waves toward the subject. A point-focusing ultrasonic probe, a point-focusing ultrasonic probe, and an ultrasonic imaging device that receives reflected waves (echoes) from the internal defect of the subject and visualizes the internal defect. Means for receiving a reflected wave (echo) of the ultrasonic focused beam transmitted from the internal defect of the subject, means for recording the beam path of the defect echo at each measurement point, and reconstruction of the internal defect image. In performing this, the reconstructed image of the subject is divided into microelements of the same size, a means for selecting a microelement that can be a defect echo source from a beam path measured at each measurement point, and a number of times that the element is selected redundantly Depending on the fine element, With a, is characterized in that it comprises a means for displaying the internal defects of the object to provide a video apparatus for internal defects by ultrasound.
[0032]
In addition, the present invention interposes water between the water immersion type ultrasonic probe and the subject, transmits the ultrasonic wave toward the subject while scanning the ultrasonic probe relatively to the subject. A method of imaging an internal defect by ultrasonic waves, which receives a reflected wave (echo) from the internal defect of the subject and visualizes the internal defect, by applying an ultrasonic focused beam from a point focusing type ultrasonic probe to the subject. And transmits the reflected wave (echo) from the internal defect of the subject, records the beam path of the defect echo at each measurement point, and reconstructs the internal defect image. The reconstructed image is divided into microelements of the same size, microelements that can be defect echo sources are selected from the beam path measured at each measurement point, and the microelements are calculated from the calculated or experimental values of the directivity of the ultrasonic beam. The incident intensity of the ultrasonic wave at After adding the incident intensity as an increment to an evaluation value counter that aggregates the evaluation values as a reflection source, performing the above-described processing for all the measurement points, and then shading or coloring the minute elements according to the value of the evaluation value counter. The above-mentioned problem has been solved by displaying the internal defect of the subject with a mark.
[0033]
According to the present invention, water is interposed between the water immersion type ultrasonic probe and the subject, and the ultrasonic probe is scanned relative to the subject while transmitting ultrasonic waves toward the subject. A point-focusing ultrasonic probe, a point-focusing ultrasonic probe, and an ultrasonic imaging device that receives reflected waves (echoes) from the internal defect of the subject and visualizes the internal defect. Means for receiving a reflected wave (echo) of the ultrasonic focused beam transmitted from the internal defect of the subject, means for recording the beam path of the defect echo at each measurement point, and reconstruction of the internal defect image. In performing this, the reconstructed image of the subject is divided into microelements of the same size, and an evaluation value counter that counts the evaluation values as a reflection source for each microelement, and a defect based on the beam path measured at each measurement point. Select small elements that can be echo sources From the calculated or experimental value of the directivity of the ultrasonic beam, determine the incident intensity of the ultrasonic wave in the microelement, add the incident intensity to the evaluation value counter as an increment, and perform the above processing for all the measurement points. Means for displaying the internal defect of the subject by shading or coloring the minute element in accordance with the value of the evaluation value counter, and displaying the internal defect of the subject. It is intended to provide an imaging device.
[0034]
According to the present invention, in imaging of internal defects by ultrasonic waves using a focused beam,
(1) Imaging is performed at a uniform resolution regardless of the depth at which internal defects exist.
(2) Imaging is performed with high resolution even when the plate thickness is large and the depth of the focused beam cannot be reached.
It becomes possible.
[0035]
According to the present invention, as shown in FIG. 2, an ultrasonic focused beam transmitted from a point-focusing type ultrasonic probe transmitted using a spherical oscillator or an acoustic lens has a direction (beam) perpendicular to the center of the spherical oscillator or the acoustic lens. Not only the waves parallel to the central axis of the beam, but also the fact that waves directed in directions that are not parallel to the central axis of the beam are densely contained over a certain angular range. It is based on the finding that it is possible to combine aperture synthesis methods with ultrasound focused beams that are not suitable. (Generally, in order to perform aperture synthesis, it is necessary to transmit a wave that spreads over a wide directional angle from an ultrasonic transceiver.)
[0036]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0037]
FIG. 1 shows a configuration diagram according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a subject to be tested. In this example, the subject 1 is a stationary subject, and imaging (imaging) of an internal defect is performed using a liquid immersion method, and water is used as a medium. An ultrasonic probe 10 transmits and receives a focused beam, transmits an ultrasonic focused beam to a subject by an electric pulse from the transmitting circuit 11 at a constant period, and reflects a reflected wave (echo) from the surface and the inside of the subject. ) To receive. The received signal is amplified by the receiving amplifier 12 to an appropriate level convenient for subsequent signal processing. The ultrasonic probe 10 is two-dimensionally scanned (xy scanning) with respect to the subject 1 by an appropriate scanning unit, and the position thereof is detected by an x-direction position detection unit 21 and a y-direction position detection unit 22. 14 is sent.
[0038]
The defect echo beam path measurement circuit 13 calculates the difference between the reception timings of the surface echo 51 and the defect echo 52, that is, the beam path of the defect echo 52 in the subject 1 (hereinafter, the path in the subject 1 is omitted, and the beam path of the defect echo is omitted). , Or simply referred to as the beam path). Either the propagation time of the ultrasonic wave or the propagation distance of the ultrasonic wave multiplied by the speed of sound may be used as the beam path. The measured beam paths are sent to the defect image synthesizing device 14, and the position P of the ultrasonic probe 10 at this time is _{i, j} (I: position in the x direction, j: position in the y direction).
[0039]
FIG. 3 shows a method of synthesizing a defect image according to the present method. FIG. 3 sets the surface of the subject 1 in a virtual three-dimensional space, and sets the depth range in which a defect inside the subject 1 may exist to a three-dimensional minute element Pf. _{k, l, m} (K: position in the x direction, l: position in the y direction, m: position in the Z direction). _{i, j} Path W of defect echo measured at _{i, j} The figure shows how a small element that can be a reflection source of the echo is extracted from the above. In the figure, the hatched elements indicate P among the small elements at the position where the depth is the smallest. _{i, j} Distance from W _{i, j} Are shown. The procedure for synthesizing a defect image in the present embodiment is as follows.
[0040]
Defect image synthesis procedure 1
(1) The ultrasonic probe 10 is scanned at a predetermined pitch and each position P _{i, j} From the transmission / reception signal of the ultrasonic wave, the defect echo beam path measurement circuit 13 uses the defect echo beam path W _{i, j} Is measured and recorded in the defect image synthesizing device 14.
[0041]
(2) The total beam path W recorded in the defect image synthesizing device 14 _{i, j} From the depth range in which a defect may be present, a small element is set in this depth range, and the three-dimensional address Pf _{k, l, m} Attach
[0042]
(3) Each probe position P _{i, j} For Pf _{k, l, m} And the measured beam path W _{i, j} And if they match within a predetermined error range, Pf _{k, l, m} Counter C provided in _{k, l, m} Is added to the count 1. Counter C _{k, l, m} Is a three-dimensional array. When the position in the depth direction is fixed (the value of m is fixed), the array becomes a two-dimensional array. FIG. 4 further shows a part of the extracted data.
[0043]
The numbers entered in FIG. 4 indicate how many times the sequence element has been matched in the comparison step.
[0044]
(4) After performing the above calculation for all the probe positions, m is fixed to a specific value, and C _{k, l, m} Is displayed in a shaded or colored manner according to the count value, a two-dimensional defect image (a C scope with a limited position in the depth direction) is obtained. When a two-dimensional defect image is created by changing the value of m, a change in the defect shape in the depth direction can be observed.
[0045]
Reference numeral 15 denotes a defect image display device, which displays the two-dimensional defect image created as described above with a color or shading according to the count value.
[0046]
The display of the defect image is not limited to the above, and may be displayed three-dimensionally without fixing m, or by fixing the value of k or l and displaying a tomographic image such as a B scope. Is also good.
[0047]
(Example 1)
FIG. 5 (a) shows, using the apparatus of the above embodiment, a minute defect at a depth of 80 mm of a steel test piece having a thickness of 120 mm at a frequency of 2 MHz, a transducer diameter of 50.8 mm, and a focal length in water of 406 mm. 4 shows the measurement results obtained by setting a focal point at a position at a depth of 60 mm using the focusing probe shown in FIG. FIG. 5C shows a defect image obtained by conventional C-scan flaw detection under the same conditions for comparison. Since the depth of existence of the minute defect is far from the focal point of the ultrasonic beam, the defect image obtained by the conventional C-scan detection is blurred. However, in the apparatus of this embodiment, the fine structure of the defect is clear. Has been visualized. In other words, it can be seen that the resolution of the present embodiment can be used to solve the problem of the resolution reduction other than the focal point, which is a problem in the conventional C-scan flaw detection.
[0048]
(Embodiment 2)
Further, according to the following procedure 2 for synthesizing a defective image, the sharpness of the defective image can be further improved.
[0049]
Defect image synthesis procedure 2
(1) The ultrasonic probe 10 is scanned at a predetermined pitch and each position P _{i, j} From the ultrasonic transmission / reception signal, each position P is detected by the defect echo beam path measurement circuit 13. _{i, j} Path W of the defect echo detected in step _{i, j} Is measured and recorded in the defect image synthesizing device 14.
[0050]
(2) Beam path W recorded in the defect image synthesizing device 14 _{i, j} From the depth range in which a defect may be present, a small element is set in this depth range, and the three-dimensional address Pf _{k, l, m} Attach
[0051]
(3) Each probe position P _{i, j} For Pf _{k, l, m} And the measured beam path W _{i, j} Is compared within a predetermined error range, the above-mentioned Pf is calculated from the calculated value or the experimental value of the directivity of the ultrasonic beam. _{k, l, m} Incident intensity I of ultrasonic wave _{k, l, m} , Pf _{k, l, m} Counter C provided in _{k, l, m} Increment I _{k, l, m} Is added. Also in this procedure 2, the counter C _{k, l, m} Is a three-dimensional array. When the position in the depth direction is fixed (the value of m is fixed), the array becomes a two-dimensional array. FIG. 6 further shows a part of the extracted data.
[0052]
The numbers input in FIG. 6 indicate the incident intensity I of the ultrasonic wave when the agreement is found in the comparison step. _{k, l, m} (FIGS. 4 and 6 are count values obtained by using the same data, and the method of adding to the counter according to the procedure is different. Changed).
[0053]
(4) After performing the above calculation for all the probe positions, m is fixed to a specific value, and C _{k, l, m} Is displayed in a shaded or colored manner according to the count value, a two-dimensional defect image (a C scope with a limited position in the depth direction) is obtained. When a two-dimensional defect image is created by changing the value of m, a change in the defect shape in the depth direction can be observed.
[0054]
(Example 2)
FIG. 5B shows a defect image obtained by the above procedure 2. It can be seen that the sharpness of the defect image is further increased as compared with the defect image shown in FIG.
[0055]
FIG. 7 shows the result of observing a change in defect shape in the depth direction by creating a two-dimensional defect image by changing the value of m. Procedure 2 was used in synthesizing the defect image. FIGS. 7 (a) to 7 (f) show, using the apparatus of the second embodiment, a minute defect at a position of about 60 mm in depth of a steel test piece having a thickness of 160 mm at a frequency of 2 MHz and a vibrator diameter of 50 mm. The figure shows the measurement result obtained by setting a focal point at a position of 40 mm in depth using a focusing probe having a focal length of 8 mm and an underwater focal length of 406 mm. FIG. 8 shows a defect image obtained by conventional C-scan flaw detection under the same conditions for comparison. In the conventional C-scan inspection, it can be seen that a defect that appears to be simply circular has a reflective surface at a position different depending on the depth, and that the method of the present invention makes it easy to grasp the three-dimensional shape of the defect.
[0056]
Although the embodiments of the present invention have been described above, the present invention is not limited to this, and the present invention is applicable not only to the case where the test object is a steel plate, but also to a cylindrical body such as a roll or a steel pipe. Obviously, the material is not limited to steel, but may be a resin or other metal or a completely different material. In addition, the subject need not be limited to a stationary object, and can be applied to a moving object. The medium in which the subject is immersed may of course be oil, or other material in addition to water.
[0057]
【The invention's effect】
According to the present invention, in the quality evaluation of a product in which internal defects such as inclusion of foreign substances, voids, and internal cracks may exist, the internal quality of the product is inspected in detail, and a customer of a product having a harmful internal defect is inspected. Can be prevented from being delivered to the company, and furthermore, problems of the manufacturing technology can be examined from the nature of the internal defect, and a manufacturing technology free of internal defects can be established.
[Brief description of the drawings]
FIG. 1 is a block diagram including a partial cross-sectional view showing an apparatus according to the configuration of the present invention.
FIG. 2 shows a focused beam used in the present invention.
FIG. 3 is a perspective view showing a method for synthesizing a defect image according to the present invention.
FIG. 4 is a table showing examples of count values;
FIG. 5 is a diagram showing an example of the effect of the present invention in comparison with a conventional example.
FIG. 6 is a chart showing an example of a count value by an addition method different from that in FIG. 4;
FIG. 7 is a diagram showing an example of a measurement result according to the method of the present invention.
FIG. 8 is a diagram showing an example of a defect image according to the related art.
FIG. 9 is a block diagram including a partial cross-sectional view showing an apparatus according to a configuration of the related art.
FIG. 10 is a perspective view for explaining a problem of the related art.
FIG. 11 is a sectional view for explaining the principle of a conventional aperture synthesis method.
[Explanation of symbols]
1, 110 ... subject
10, 111 ... ultrasonic probe
11, 112 ... transmission circuit
12, 113 ... receiving amplifier
13: Defect echo beam path measurement circuit
14. Defect image synthesis device
15 ... Defect image display device
21 x-direction position detecting means
22... Y-direction position detecting means
51 ... Surface echo
52 ... Defect echo
114 ... Gate circuit
115 ... Peak detector
120 ... transducer array

Claims (4)

Water is interposed between the water immersion type ultrasonic probe and the subject, and while the ultrasonic probe is relatively scanned with respect to the subject, an ultrasonic wave is transmitted toward the subject, and the inside of the subject is transmitted. In a method of imaging an internal defect by ultrasonic waves that receives a reflected wave (echo) from the defect and visualizes the internal defect,
A point-focusing type ultrasonic probe transmits an ultrasonic focused beam toward a subject, receives a reflected wave (echo) from an internal defect of the subject,
At each measurement point, record the beam path of the defect echo,
In reconstructing the internal defect image, the reconstructed image of the object is divided into minute elements of the same size, and a minute element that can be a defect echo source is selected from a beam path measured for each measurement point,
A method of imaging internal defects by ultrasonic waves, characterized by displaying the internal defects of the subject by shading or coloring the minute elements according to the number of times selected and selected repeatedly. Water is interposed between the water immersion type ultrasonic probe and the subject, and while the ultrasonic probe is relatively scanned with respect to the subject, an ultrasonic wave is transmitted toward the subject, and the inside of the subject is transmitted. In an internal defect imaging device using ultrasonic waves that receives reflected waves (echoes) from the defect and visualizes the internal defect,
A point-focusing ultrasonic probe,
Means for receiving a reflected wave (echo) of an ultrasonic focused beam transmitted from the point focused ultrasonic probe from an internal defect of the subject;
Means for recording the beam path of the defect echo at each measurement point;
In performing the reconstruction of the internal defect image, the reconstructed image of the subject is divided into small elements of the same size, and a means for selecting a small element that can be a defect echo source from a beam path measured for each measurement point,
Means for displaying the internal defect of the subject by coloring and shading the microelements according to the number of times selected in duplicate,
A device for imaging internal defects by ultrasonic waves, comprising: Water is interposed between the water immersion type ultrasonic probe and the subject, and while the ultrasonic probe is relatively scanned with respect to the subject, an ultrasonic wave is transmitted toward the subject, and the inside of the subject is transmitted. In a method of imaging an internal defect by ultrasonic waves that receives a reflected wave (echo) from the defect and visualizes the internal defect,
A point-focusing type ultrasonic probe transmits an ultrasonic focused beam toward a subject, receives a reflected wave (echo) from an internal defect of the subject,
At each measurement point, record the beam path of the defect echo,
In reconstructing the internal defect image, the reconstructed image of the object is divided into minute elements of the same size, and a minute element that can be a defect echo source is selected from a beam path measured for each measurement point,
From the calculated value or experimental value of the directivity of the ultrasonic beam, determine the incident intensity of the ultrasonic wave in the microelement, add the incident intensity as an increment to an evaluation value counter that aggregates the evaluation values as a reflection source,
After performing the above-described processing for all the measurement points, the microelements are shaded or colored according to the value of the evaluation value counter, and the internal defect of the subject is displayed. How to visualize defects. Water is interposed between the water immersion type ultrasonic probe and the subject, and while the ultrasonic probe is relatively scanned with respect to the subject, an ultrasonic wave is transmitted toward the subject, and the inside of the subject is transmitted. In an internal defect imaging device using ultrasonic waves that receives reflected waves (echoes) from the defect and visualizes the internal defect,
A point-focusing ultrasonic probe,
Means for receiving a reflected wave (echo) of an ultrasonic focused beam transmitted from the point focused ultrasonic probe from an internal defect of the subject;
Means for recording the beam path of the defect echo at each measurement point;
In performing the reconstruction of the internal defect image, the reconstructed image of the subject is divided into minute elements of the same size, and an evaluation value counter that totals the evaluation value as a reflection source for each minute element,
From the beam path measured at each measurement point, select a small element that can be a defect echo source, and from the calculated or experimental value of the directivity of the ultrasonic beam, obtain the incident intensity of the ultrasonic wave at the small element, and obtain the evaluation value. Means for adding the incident intensity to a counter as an increment;
After performing the above process for all the measurement points, by applying a shade or color to the micro element according to the value of the evaluation value counter, means for displaying the internal defect of the subject,
A device for imaging internal defects by ultrasonic waves, comprising:

Images