JP5662873B2 - Ultrasonic flaw detection method - Google Patents

Description

The present invention relates to an ultrasonic flaw detection how, in particular, using a remote scanning mechanism and the array probe, relates to suitable ultrasonic flaw detection methods from performing ultrasonic flaw detection, such as weld metal material.

  In order to evaluate the soundness of a structure, an ultrasonic flaw detection method is widely used as a nondestructive inspection method for the surface and the inside of a structure (for example, a welded portion of a metal material). When it is difficult to directly access the structure to be examined, a remote scanning mechanism such as a scanner, manipulator or vehicle is used, and this remote scanning mechanism automatically scans the position of the ultrasonic probe (AUT: Automated Ultrasonic Testing).

  Here, between the ultrasonic probe and the normal subject, the structure is inspected via an intermediate medium in order to improve the transmission of ultrasonic waves. As an intermediate medium, a liquid (for example, glycerin, machine oil, water, etc.) is widely used. In special cases, a gas or a highly viscous gel substance may be used as the intermediate medium. In particular, when there is a change in shape such as curvature or swell on the surface of the subject, a flaw detection method called “water immersion method” through an intermediate medium such as water is applied. In the water immersion method, the distance between the ultrasonic probe and the subject is often several millimeters to several tens of millimeters.

Here, as a kind of ultrasonic flaw detection method, there is a so-called phased array type ultrasonic flaw detection method. Here, the phased array system, also called a scan type or electronic scanning method, for example, a plurality of ultrasonic sound Namioku receiving element probe arranged in an array composed of a piezoelectric element, a so-called array probe Using the electrical signal that triggers the generation of ultrasonic waves to each element of the array probe with a predetermined time delay, the ultrasonic waves generated from each element are superimposed to form a composite wave, Conditions such as the transmission angle and reception angle of ultrasonic waves to the inspected object, the transmission position and reception position, or the position where the combined wave interferes and strengthens energy, that is, the focal position, are changed at high speed by electrical control. It is an ultrasonic flaw detection method that made it possible. Here, a predetermined combination of delays given to each element is referred to as a delay pattern.

  The reason for electrically scanning the flaw detection conditions using the array probe in this way is that the ultrasonic transmission / reception angular position and focus can be freely changed over a wide inspection range. This is because by selecting an angle, a position, and a focal point at which a reflected wave from a body reflection source (such as a defect) can be received more strongly, a defect that is a reflection source can be easily found. As a typical combination of delay patterns, there are a sector scan method in which the transmission angle and the reception angle are changed, and a linear scan method in which the transmission position and the reception position are translated. Each method has a feature that it can be visualized as a cross-sectional image of a subject from signals obtained at different angles (or positions), and it is easy to identify the position and properties of a reflection source.

  When performing an ultrasonic flaw detection method through an intermediate medium such as a water immersion method by the phased array method, multiple reflected waves of ultrasonic waves in the medium are used as in the case of using an ordinary ultrasonic probe. In order to prevent the flaw detection signal from affecting the flaw detection signal, flaw detection is performed by separating the subject and the array probe by a predetermined distance (for example, about several tens of mm in the case of the water immersion method). For this reason, a spatial separation occurs between the position of the array probe and the point (ultrasonic incident point) where the ultrasonic wave enters the subject after propagating through the medium. Therefore, in order to obtain more accurate and reliable flaw detection results, among the positional relationship between the array probe and the subject, particularly the ultrasonic incident position (angle, distance to the subject) in the subject is controlled. It is necessary to.

  Therefore, for example, it is input and stored in advance as shape data of the curved surface shape of the subject, and based on the stored data, the position and direction of the ultrasonic probe at a certain angle at the incident point on the surface of the subject In addition, there is known an ultrasonic flaw detection method that maintains a constant distance (see, for example, Patent Document 1).

  In addition, in order to maintain the distance and angle between the subject and the ultrasonic probe, there is known a method for measuring the shape of the subject with a distance measurement probe in advance (see, for example, Patent Document 2).

  Also, in ultrasonic flaw detection using an array probe, the surface shape of the subject is measured using the array probe, the delay time given to the array probe is calculated from the surface shape data, and the complex shape portion However, a flaw detection method for focusing at a predetermined position is known (for example, see Patent Document 3).

JP-A 63-309853 JP-A-1-292248 JP 2008-122209 A

  However, in Patent Document 1 and Patent Document 2, there is a description regarding a preset for keeping the positional relationship (angle and distance) between the subject and the ultrasound probe constant. It is not possible to specify whether or not the positional relationship has been established.

  In addition, in Patent Document 3, there is a description regarding setting of flaw detection conditions in consideration of the surface shape of the subject, but in automatic flaw detection (AUT), the positional relationship between the array probe and the subject (angle and distance). Cannot be specified.

An object of the present invention is an ultrasonic flaw detection method in which ultrasonic waves are propagated through an intermediate medium such as water by a phased array method using an array probe, and the ultrasonic probe is scanned by a remote scanning mechanism . the positional relationship of the array probe and the object to pinpoint, small deviation of the positional relationship of the array probe and the object, to provide a more capable accurate ultrasonic flaw ultrasonic test how is there.

(1) In order to achieve the above object, the present invention propagates the ultrasonic wave transmitted from the ultrasonic probe to the subject via the medium and uses the remote scanning mechanism to perform the ultrasonic probe. An ultrasonic flaw detection method for scanning a probe, wherein an ultrasonic transmitter / receiver is used to scan a probe position for enabling scanning to keep the ultrasonic probe at a predetermined distance and angle with respect to the subject. conduct teaching, the teaching, the reflected wave on the front surface or these object received as the first received signal, the flaw detection image by the first reception signal, the first using a sound velocity of the medium The ultrasonic probe for the subject is controlled by a drive control device based on the surface profile of the subject obtained by teaching. Predetermined Distance and to keep the angle, by using the ultrasonic transmitting and receiving apparatus to implement the testing of the subject, testing of the subject, the reflected wave from the inner portion of the subject as a second reception signal receiving, the flaw detection image by the second reception signal, said display as a second acoustic image using a subject of sound, at the same time or by switching the front surface or these reflected waves of the subject The first received signal is received, and the flaw detection image based on the first received signal is displayed as the first acoustic image using the sound speed of the medium.

( 2 ) In the above ( 1 ), preferably, the drive control device is configured such that the maximum amplitude MAX_A (θx) is a maximum value in the maximum amplitude MAX_A (θx) of the reflected echo group with respect to the rotation angle θx of the ultrasonic probe. A value obtained by adding the incident angle θA at the incident point on the subject to the angle θxm to be a sensor angle θxA, and based on the distance RA at the sensor angle θxA, the sensor and the subject surface The ultrasonic probe with respect to the subject is kept at a predetermined distance and angle by moving by a distance (RA-R0) so as to be a predetermined distance R0.

According to the present invention, it is possible to accurately specify the positional relationship between the array probe and the subject and perform more accurate ultrasonic flaw detection with little deviation in the positional relationship between the array probe and the subject.

It is a block diagram of the ultrasonic flaw detector by one Embodiment of this invention. It is operation | movement explanatory drawing of the remote scanning mechanism used for the ultrasonic flaw detector by one Embodiment of this invention. It is a block diagram which shows the structure of the ultrasonic transmitter / receiver used for the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of a structure of the array probe used for the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of the flaw detection method by the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of the flaw detection method by the ultrasonic flaw detector by one Embodiment of this invention. 1 is an overall configuration diagram of an ultrasonic flaw detection system using an ultrasonic flaw detection apparatus according to an embodiment of the present invention. It is a flowchart which shows the content of the ultrasonic flaw detection method by the ultrasonic flaw detector by one Embodiment of this invention. It is a flowchart which shows the content of the ultrasonic flaw detection method for depth sizing by the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of the setting method of the teaching data in the ultrasonic flaw detection method by one Embodiment of this invention. It is explanatory drawing of the relationship between the sensor and the subject in the ultrasonic flaw detection method. It is explanatory drawing of the relationship between the sensor and the subject in the ultrasonic flaw detection method. It is explanatory drawing of the relationship between the sensor and the subject in the ultrasonic flaw detection method. It is explanatory drawing of the relationship between the sensor and the subject in the ultrasonic flaw detection method. It is explanatory drawing of a structure of the array probe used for the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of the linear scan type | system | group flaw detection method by the ultrasonic flaw detector by one Embodiment of this invention. It is explanatory drawing of the linear scan type | system | group flaw detection method by the ultrasonic flaw detector by one Embodiment of this invention.

Hereinafter, the contents of an ultrasonic flaw detection method using the ultrasonic flaw detection apparatus according to an embodiment of the present invention will be described with reference to FIGS. Here, an example using the sector scan method among the phased array method using the array probe will be described.
First, the configuration of the ultrasonic flaw detector according to the present embodiment will be described with reference to FIG.
FIG. 1 is a configuration diagram of an ultrasonic flaw detector according to an embodiment of the present invention.

  The subject 101 shows an example of a welded portion having a complex shape portion, and is obtained by penetrating a tube 101B through a steel plate 101A at a predetermined angle. The periphery of the pipe 101B where the pipe 101B and the steel plate 101A are close to each other is welded to form a welded part 101C.

  The subject 101 is disposed in the container CH, and water is stored in the container. That is, the subject 101 is placed in water. Accordingly, water is used as a medium for propagating ultrasonic waves from the array probe 100 as ultrasonic transmission / reception means to the subject 101, and inspection of the presence or absence of scratches on the welded portion 101C by ultrasonic flaw detection using a water immersion method. Measure the dimensions of the wound.

  Here, the shape of the welded part 101C changes three-dimensionally depending on the angle in the circumferential direction of the tube 101B, and has a feature of a saddle shape in which concave and convex surfaces are combined, and the ultrasonic wave is accurately applied to the target position. It has a shape that is difficult to enter.

  Here, the application destination of this example is, for example, a defect in a welded portion 101C (for example, a control rod drive mechanism stub tube, an in-core instrumentation nozzle housing, a shroud support, a shroud, etc.) of a reactor internal structure of a nuclear power plant. Non-destructive inspection for detection and dimensional measurement. In addition, the method and procedure described in this example can be similarly applied to a pipe or a plate-shaped inspection object in addition to the curved surface characteristic of the in-furnace structure.

  The array probe 100 is installed above the flaw detection surface of the subject 101 via a liquid (for example, water), and receives ultrasonic waves from the ultrasonic transmission / reception surface 100A by a drive signal supplied from the ultrasonic transmission / reception device 104. It is generated and propagated toward the subject 101, a reflected wave appearing from the surface or inside of the subject 101 is detected, and a received signal is input to the ultrasonic transmission / reception apparatus 104.

  When the reflection source 103 such as a crack exists in the welded part 101 </ b> C, the reflected wave from the crack 103 is received by the array probe 100.

  The array probe 100 is connected to the ultrasonic transmission / reception device 104 and is displayed as flaw detection result information on the acoustic image display means 105. The array probe 100 is attached to the remote scanning mechanism 102 and moves to a predetermined position to perform flaw detection.

  The acoustic image display means 105 includes a display unit 105A and a display unit 105B. The display image of the display unit 105A will be described later with reference to FIG. 5, but a reflection image from the subject surface 101D is obtained and information on the surface profile of the welded part 101C is obtained. The display image of the display unit 105B will be described later with reference to FIG.

  The drive control device 110 controls the remote scanning mechanism 102 based on the surface profile information of the welded portion 101C detected by the ultrasonic transmitting / receiving device 104, so that the array probe 100 is applied to the surface of the welded portion 101C. Thus, a predetermined angle is set at a predetermined distance.

Next, the operation of the remote scanning mechanism 102 used in the ultrasonic flaw detector according to the present embodiment will be described with reference to FIG.
FIG. 2 is an explanatory view of the operation of the remote scanning mechanism used in the ultrasonic flaw detector according to one embodiment of the present invention.

  In order to scan the array probe 100 three-dimensionally, for example, a remote scanning mechanism 102 having six or more control axes used for an automatic robot, a manipulator, or the like is used.

  The remote scanning mechanism 102 is, for example, a head having three rotation axes of θx, θy, and θz that rotates about the array probe 104 as rotation axes in the directions of the X, Y, and Z axes. Consists of a part 102A and three axes Z, R, and φ, which are seated on the pipe 101B and move the entire head unit 102A, up and down (H axis), radial direction (R axis), and rotation axis (φ axis) Is done. The array probe 100 can be moved by the remote scanning mechanism 102.

Next, the configuration of the ultrasonic transmission / reception apparatus 104 used in the ultrasonic flaw detection apparatus according to the present embodiment will be described with reference to FIG.
FIG. 3 is a block diagram showing a configuration of an ultrasonic transmission / reception apparatus used in the ultrasonic flaw detection apparatus according to the embodiment of the present invention.

  The transmission / reception device 104 includes a computer 104A, a time control unit 104B, a pulsar 104C, a receiver 104D, a data recording unit 104E, and a storage unit 104F. The pulser 104C supplies a drive signal to the array probe 100 shown in FIG. 1, and a receiver 104D processes a reception signal input from the array probe 100.

  Here, the computer 104A controls the time control unit 104B, the pulsar 104C, the receiver 104D, and the data recording unit 104E so as to obtain necessary operations.

  The time control unit 104B controls the timing of the drive signal output from the pulser 104C and also controls the input timing of the reception signal by the receiver 104D. Thus, the reception signal from the receiver 104C is sequentially stored in the data recording unit 104E in synchronization with the transmission signal.

  The data recording unit 104E functions to process the received signal supplied from the receiver 104D and supply it to the acoustic image display unit 105. Here, the operation of the acoustic image display unit 105 will be described in detail later.

  The storage unit 104F stores, for example, a delay pattern of a delay time for sector scanning.

Next, the configuration of the array probe 100 used in the ultrasonic flaw detector according to the present embodiment will be described with reference to FIG.
FIG. 4 is an explanatory diagram of the configuration of the array probe used in the ultrasonic flaw detector according to one embodiment of the present invention. FIG. 4A is a bottom view and FIG. 4B is a front view.

  FIG. 4 schematically shows the most basic configuration of the array probe 100. The array probe 100 includes a plurality of ultrasonic transmission / reception elements 1202 arranged in a line. The ultrasonic transmission / reception element 1202 includes a piezoelectric conversion element such as a piezoelectric ceramic, a piezoelectric polymer, or a piezoelectric composite material. The ultrasonic transmission / reception element 1202 includes a front plate 1203 for protecting the ultrasonic transmission / reception element and adjusting acoustic matching by multiple reflection, and is in contact with a medium (such as water) outside the array probe as an ultrasonic transmission / reception surface. ing. The center position 1201 of the ultrasonic transmission / reception surface is treated as a representative point as a transmission / reception point of the array probe as necessary during display or evaluation. The array probe 100 is connected to the transmission / reception device 104 shown in FIG. 1 by a cable.

Next, the flaw detection method using the ultrasonic flaw detector according to the present embodiment will be described with reference to FIGS.
5 and 6 are explanatory diagrams of a flaw detection method using an ultrasonic flaw detector according to an embodiment of the present invention. FIG. 5 is a flaw detection screen using the sound speed of the medium. FIG. 6 is a flaw detection screen using the sound speed of the subject.

  First, the flaw detection screen using the sound speed of the medium (water in the water immersion method) between the subject and the array probe will be described with reference to FIG.

  An ultrasonic wave 1301 is transmitted from the array probe 100 into a medium such as water.

A delay pattern is set so that the propagation angle (incident angle) with respect to the medium changes from the array probe 100 to the subject 101, and ultrasonic waves are transmitted while changing the incident angle θi. For example, the range of change in incident angle is set to a 1 ° pitch (total of 121 angles) from −60 ° to + 60 °.

  The ultrasonic wave 1301 transmitted from the array probe 100 is reflected by the subject surface 101D and received again by the array probe 100. The received signal is recorded in the data recording unit 104E of FIG. 3 as one waveform for each incident angle θi. Assuming that the amplitude value of the point 1302B of the one-way propagation time T1 in the reflected wave of the subject surface 101D is A (T1; θi), the angle θ1 is expressed as a shaded black and white or color pixel proportional to the amplitude value. As shown in FIG. 5, the display unit 105A in FIG. 1 displays a flaw detection image 106A and a reflected image 106E from the subject surface 101D by displaying in a fan shape with the propagation path length (the product of the time T1 and the sound velocity of the medium). Can be obtained.

Further, the shape (surface profile) of the subject surface 101D can be identified from the image 106C of the waveform rising point 1302A among the reflected waves of the subject surface 101D. Certain of the surface profile, referred to as Te I Chingu of the subject.

  Further, the distance between the array probe and the subject can be specified from the image 106C of the subject surface shape, from the distance 106D in the direction immediately below the sensor.

  Next, the flaw detection screen using the sound speed of the subject will be described with reference to FIG.

  An ultrasonic wave 1401 is transmitted from the array probe 100 into a medium such as water.

  A delay pattern is installed from the array probe 100 to the subject 100 so as to change the propagation angle (refraction angle) in the subject, and an ultrasonic wave having a changed refraction angle θj is transmitted. The incident angle θj ′ from the array probe to the medium when propagating to the subject at θj is given by sin θj ′ = sin θj × (V ′ / V) according to Snell's law. V ′ is the sound speed of a medium such as water, and V is the sound speed of the subject.

  The ultrasonic wave 1401 transmitted from the array probe 100 is refracted to the inside of the subject on the subject surface 101D, propagates into the subject, and is reflected when the reflection source 103 such as a defect exists in the subject. The signal reflected by the source 103 is refracted by the object surface 101D and received by the array probe 100 again.

  The received signal is recorded in the data recording unit 104E of FIG. 3 as one waveform for each refraction angle θj. Assuming that the amplitude value of the point 1402 of the one-way propagation time T2 among the reflected waves of the reflection source 103 inside the subject is A (T2; θj), the angle is expressed as a shaded black and white or color pixel having the amplitude value. By displaying in a fan shape with θj and propagation path length (product of time T1 and sound velocity of the subject), the flaw detection image 106B corresponding to the cross-sectional view of the subject is displayed on the display unit 105B of FIG. 1 as shown in FIG. Can be obtained.

When performing an automatic ultrasonic flaw detection (AUT) while controlling the position of the array probe 100 with the remote scanning mechanism 102, as shown in FIG. 2, for example, a robot having six axes or more is used as shown in FIG. using a surface profile of the object obtained by the object of te I Chingu described Te, so the angle and distance of the array probe and the object is constant, to scan the probe position. Note that water exists as the medium between the array probe and the subject, and the distance between the array probe and the subject is set to about 30 mm, for example. A specific method for making the angle and distance between the array probe and the subject constant will be described later with reference to FIG.

  The flaw detection based on the sound speed of the subject shown in FIG. 6 and the flaw detection based on the sound speed of the medium (water or the like) shown in FIG. 5 include, for example, a delay pattern based on the sound speed of the subject and a delay pattern based on the sound speed of the medium. It can be realized by setting at the same time or switching.

  As described above, in the present embodiment, in addition to ultrasonic flaw detection using the sound velocity of a subject that has been performed in conventional ultrasonic inspection, a medium (such as water) that exists between the array probe and the subject. ) At the same time (or by switching), the distance between the array probe and the subject is specified, and the shape of the object directly under the array probe is specified, so that It becomes possible to specify the exact positional relationship between the array probe and the subject. In this way, the mutual positional relationship is specified, so that the position of the reflection source can be more accurately evaluated. The reliability of the measurement accuracy of the reflection source position and the dimensional measurement accuracy of the reflection source position is high. High inspection can be done.

Next, a specific example of an ultrasonic flaw detection method using the ultrasonic flaw detector according to one embodiment of the present invention will be described with reference to FIGS.
First, the overall configuration of an ultrasonic flaw detection system using the ultrasonic flaw detection apparatus according to the present embodiment will be described with reference to FIG.
FIG. 7 is an overall configuration diagram of an ultrasonic flaw detection system using an ultrasonic flaw detection apparatus according to an embodiment of the present invention.

  Here, as an example of the application target, an overall configuration of an ultrasonic flaw detection system in the case of applying to inspection of a welded portion of a reactor internal structure of a nuclear power plant is shown.

The objects to be inspected are various welded joints of the shroud 2002, which is a structure in the reactor pressure vessel 2001, a through-pipe welded portion 101B such as a control rod drive mechanism stub tube, and the like. On the operation floor 2003, a work carriage 2004 for moving up and down equipment such as a control device 2005 of a multi-axis manipulator that is a remote scanning mechanism 102, an ultrasonic flaw detector 2006, and various cables 2007 is installed in the furnace. . The array probe 100 is installed in front of the multi-axis manipulator 102, and the probe is scanned by the multi-axis manipulator 102 so as to cover the examination region of the subject, and automatic flaw detection is performed.

  The ultrasonic flaw detector 2006 includes the transmission / reception device 104 and the acoustic image display means 105 shown in FIG. The manipulator control device 2005 includes the drive control device 110 shown in FIG.

Next, the contents of the ultrasonic flaw detection method using the ultrasonic flaw detector according to the present embodiment will be described with reference to FIG.
FIG. 8 is a flowchart showing the contents of an ultrasonic flaw detection method by the ultrasonic flaw detection apparatus according to one embodiment of the present invention.

  Here, the case of the inspection of the in-core structure weld of the nuclear reactor shown in FIG. 7 will be described.

  First, in step S1801, the inspector performs visual inspection using an underwater camera for the purpose of detecting a defect instruction.

  Thereafter, in step S1802, the inspector performs an eddy current flaw detection as necessary to measure the opening length of the defect.

  Further, in step S1803, the inspector uses the ultrasonic flaw detector of the present embodiment to perform ultrasonic inspection (UT) for the purpose of depth measurement (depth sizing) of the detected defect. To implement.

  Thereafter, in step S1804, the inspector performs defect progress evaluation, and in step S1805, repairs and replacement are performed as necessary.

  The ultrasonic flaw detection method according to this embodiment is applied by the depth sizing in step S1803.

Next, the contents of the ultrasonic flaw detection method for depth sizing by the ultrasonic flaw detector according to the present embodiment will be described with reference to FIG.
FIG. 9 is a flowchart showing the contents of an ultrasonic flaw detection method for depth sizing by the ultrasonic flaw detector according to one embodiment of the present invention.

  First, calibration before flaw detection (step S1901) is performed to adjust sensitivity, time axis, and the like. Next, the apparatus is installed in the furnace (step S1902), and the apparatus position (such as the origin of each axis) is initialized (step S1903).

  Next, teaching of the position of the array probe (teaching of the initial value of the set value) is performed for the assumed position of the defect (step S1904).

Next, a confirmation scan for confirming the teaching data is performed (step S1905), whether there is any interference between the equipment and the inspection device (remote drive device, probe, cable, etc.) positional relationship between the subject confirms whether it is appropriate, until the positional relationship between coherence confirmed probe and the object of the device is in a state no problem, teaching (step S1904) and confirms the scan (step S1905) is repeated.

  After confirming that there is no problem, the probe is moved to the flaw detection start position (step S1906). After the sensor installation state at the start position is confirmed (step S1907), flaw detection is started (step S1908).

  During the flaw detection, it is confirmed whether there is any abnormality in the test data (step S1909), the positional relationship between the probe and the subject (step S1910), and finally whether the flaw detection range is covered. Confirmation (step S1911), if there is no problem, the flaw detection is terminated (step S1912).

  After completion of the flaw detection, the apparatus is uninstalled from the furnace (step S1913), and calibration after the flaw detection is completed (step S1914).

  Here, for example, in the steps during the flaw detection (steps S1908 to S1912), when the positional relationship between the array probe and the subject is confirmed (step S1910), the normal flaw detection using the subject sound velocity is performed. At the same time, the distance and angle (inclination of the subject) between the array probe and the subject are confirmed using the speed of sound of the medium (such as water) between the array probe and the subject.

  At this time, an acoustic image based on the sound velocity of the subject and an acoustic image based on the sound velocity of the medium (water, etc.) are displayed simultaneously (or switched), so that the positional relationship is confirmed while flaw detection is performed. By recording, the positional relationship can be recorded.

  By recording the positional relationship between the array probe and the subject, for example, after flaw detection, the distance and angle between the array probe and the subject can be specified, and when there is a deviation from the assumed value, It can be corrected and evaluated, and a highly reliable ultrasonic flaw detection can be provided.

  Further, for example, in teaching (step S1904), which is a step before the flaw detection, simultaneously with normal flaw detection using the object sound velocity, the sound velocity of the medium (water or the like) between the array probe and the object is used. As described above, appropriate teaching data (initial value) can be set while confirming the distance and angle (inclination of the subject) between the array probe and the subject.

  On the other hand, it is also important to record the positional relationship between the array probe and the subject. For example, when performing flaw detection without performing teaching (step S1904), the positional relationship between the array probe and the subject can be recorded. In this case, there is little unevenness on the surface of the subject, and flaw detection can be performed without performing teaching (step S1904). In this case, flaw detection is performed without performing teaching (step S1904), and on the other hand, as a result of checking flaw detection data after completion of flaw detection by recording the positional relationship between the array probe and the subject, the flaw detection data is suspicious. When there is an uncertain location, it is possible to confirm whether there is no abnormality in the distance and angle between the array probe and the subject by confirming the positional relationship between the array probe and the subject already recorded. When there is no abnormality in the angular distance, the data of the suspicious part can be considered as data due to defects inside the subject.

Next, a teaching data setting method in the ultrasonic flaw detection method according to the present embodiment will be described with reference to FIG.
FIG. 10 is an explanatory diagram of a teaching data setting method in the ultrasonic flaw detection method according to one embodiment of the present invention.

  The array probe 100 transmits an ultrasonic wave 2101 in a direction directly below it.

  The waveform reflected from the subject surface 101D is recorded in the data recording unit 104E in FIG. This waveform data includes information on the distance between the array probe 100 and the subject 101 and information on the angle between the array probe 100 and the subject 101.

As a received waveform, when the propagation time is taken on the horizontal axis and the absolute value of the amplitude is taken on the vertical axis, the maximum amplitude MAX_A (θx) of the reflected echo group 2105 from the subject surface 101D can be obtained. Here, θx represents the rotation axis of the remote scanning mechanism. θx is an example for explanation, and any of the drive shafts may be used in addition to the other rotation axes θy and θz.

  When the rotation axis θx is changed, the maximum amplitude MAX_A (θx) changes with respect to θx. At this time, when the maximum amplitude value is the maximum value (in the case of the sensor rotation angle 2102 in the display on the display unit 105C), it is confirmed that the array probe and the subject are facing each other (incident angle is 0 degree). Therefore, the value θx of the rotation axis that gives the directly facing condition where the ultrasonic wave is incident on the subject most efficiently can be obtained and set as the teaching value.

  Furthermore, since the position of the array probe in the normal direction (facing relationship) on the surface of the subject can be specified as necessary, the angle between the array probe and the subject can be adjusted.

Similarly, when the propagation time is taken on the horizontal axis and the absolute value of the amplitude is taken on the vertical axis as the received waveform, the speed of sound of the medium (water, etc.) is calculated during the one-way propagation time until the reflection echo group 2105 rises from the subject surface. Is multiplied by the distance R (θx). The rise of the echo can be automatically obtained as the intersection of the time gate signal 2106 and the waveform 2105. Θx represents the rotation axis of the remote scanning mechanism. θx is an example for explanation, and any of the drive shafts may be used in addition to the other rotation axes θy and θz.

  When the rotation axis θx is changed, the distance R (θx) changes with respect to θx. For example, when it is desired to set the distance R0, the value of the distance R (θx) closest to the distance R0 (in the case of the sensor rotation angle 2103 in the display on the display unit 105D) or the difference between the distance R0 and the distance R (θx) The θx at which the absolute value is the minimum value can be set as the teaching value.

  In this way, by setting a highly accurate teaching value at the teaching stage, it is possible to reduce in advance a deviation from the setting value of the confirmation at the time of flaw detection (step S1910), and the flaw detection is performed more efficiently in a short time. It becomes possible.

  Here, the relationship between the sensor and the subject will be described with reference to FIGS.

  FIGS. 11-14 is explanatory drawing of the relationship between the sensor and a test object in an ultrasonic flaw detection method.

  Hereinafter, in the case where ultrasonic waves are transmitted to a structure that is a subject via an intermediate medium, a change in the positional relationship between the ultrasonic waves and the subject in the case of the water immersion method will be described as an example.

  As shown in FIG. 11, consider a case where the surface 210 of the subject 101 has a curved surface and the probe is scanned so that the incident point of the ultrasonic wave is changed from point A to point B. At point A, the probe 202A is installed at an angle θA with respect to the normal line orthogonal to the tangent line 204A of the ultrasonic incident point 203A. By arranging in this way, the ultrasonic wave 208A enters the incident point 203A on the subject at an angle θA, and is refracted at an angle θA ′ on the surface of the subject, whereby the oblique ultrasonic wave 209A propagating in the steel material is generated. can get.

  FIG. 11 shows an example of probe scanning not considering the flaw detection conditions. When the ultrasonic probe is simply translated from the position 202A and scanned to the position 202B, the ultrasonic wave 208B is incident at an angle θB with respect to the normal perpendicular to the tangent line 204B with respect to the incident point 203B. The light is refracted at an angle θB ′ and propagates as an oblique supersonic wave 209B.

  At this time, the refraction angle θA ′ with respect to the subject at point A and the refraction angle θB ′ with respect to the subject at point B are different. It is not possible to confirm whether or not there has been a deviation in angle during ultrasonic flaw detection, and if it is evaluated that there has been no deviation, an accurate evaluation cannot be performed because the actual refraction angle is different. For this reason, in general, in an ultrasonic examination, it is required to inspect an object (or a reflection source inside the object) while maintaining the same angle (for example, 45 °), and a change in refraction angle is required. It is necessary to move the probe so that there is no.

Comparing the propagation speed of longitudinal ultrasonic waves for the intermediate medium (water) used in the water immersion method and the subject (for example, steel), the sound velocity of water V1 = 1500 m / s and the sound velocity of steel V2 = 6000 m / s. Quad sound speed is different. For this reason, the relationship of the following formula | equation (1) is materialized by the incident angle (theta) 1 from water, and the refraction angle (theta) 2 to steel materials from Snell's law.

sin θ2 = sin θ1 × (V2 / V1) (1)

That is, the greater the sound speed ratio (V2 / V1), the greater the angular change due to refraction. For example, if the incident angle is deviated by a small angle Δθ from θ1 = 0 °, when evaluating the ultrasonic flaw detection result, if the deviation amount cannot be grasped, the sound speed ratio V2 / Since V1 = 4, the refraction angle in the steel material has a large deviation of 4Δθ.

  Further, the distance from the point 207A to the point 203A and the distance from the point 207B to the point 203B are also different with respect to the distance (water distance) between the point where the ultrasonic wave is transmitted from the probe and the ultrasonic incident point on the subject. .

  Therefore, when the ultrasonic wave reception waveforms at the points A and B are compared, as shown in FIGS. 12A and 12B, the signals (301A and 301B) from the subject surface and the signals (302A and 302A) from the inside of the subject are obtained. 302B), the reception time is different by the time difference Δt. In ultrasonic inspection, the position and properties of the reflection source are specified according to the time of the received signal. Therefore, the probe position is moved so that the reception time of the signal from the reflection source does not vary depending on the probe position. There is a need.

With respect to the time lag of the received signal, if the propagation distance in water is D1 and the propagation distance in steel is D2, the one-way propagation time T is expressed by equation (2).

T = (D1 / V1) + (D2 / V2) (2)

Here, since the ultrasonic flaw detector generally uses the sound velocity V2 of the subject and displays the propagation time converted into the propagation distance, the propagation time of the equation (2) is expressed as the propagation in the steel material. When converted into the distance W, it can be expressed as equation (3).

W = D1 × (V2 / V1) + D2 (3)

Accordingly, if the propagation distance D1 in water is deviated by ΔD, the sound velocity ratio V2 / V1 = 4. Therefore, when the ultrasonic wave flaw detection cannot be performed, the one-way propagation displayed on the ultrasonic flaw detector The path W is displayed as a large deviation of 4ΔD, which causes an error in the evaluation result.

  In this way, in ultrasonic inspection through a medium such as the water immersion method, it is possible to correctly set the angle of the probe position and the distance to the subject, and to grasp the actual positional relationship at the time of flaw detection, Necessary for accurate evaluation.

  Next, an example of probe scanning in consideration of flaw detection conditions will be described with reference to FIG. When scanning the ultrasonic probe from the position 202A to the position 402B, the ultrasonic wave 406B is incident at an angle 406B equal to the angle θB with respect to the normal line orthogonal to the tangent line 204B with respect to the incident point 203B. If the angle of the probe is set, it is refracted at an angle 410B equal to the angle 210A on the surface of the subject and propagates as an oblique supersonic wave 409B.

  The direction of the ultrasonic wave transmitted from the ultrasonic probe is set as 408B, and the distance (water distance) between the point where the ultrasonic wave is transmitted from the probe and the ultrasonic incident point on the subject is also set. , 207A to 203A and 407B to 403B need to be set to have the same position.

  If set in this way, as shown in FIGS. 14A and 14B, in the received waveforms at points A and B, the reflected waves (301A and 501A) from the subject surface and the inside of the subject The reception times of the reflected waves (302A and 502B) from the display are displayed so as to be substantially the same, and the flaw detection result can be more accurately evaluated.

Again, with reference to FIG. 10, with the subject surface profile obtained by te I Chingu of the subject, so that the angle and distance of the array probe and the object is constant, the probe position A scanning method will be described. This scanning is performed by the array probe 100 using the remote scanning mechanism 102 having six or more control axes based on the surface profile of the subject from the transmission / reception device 104 by the drive control device 110 shown in FIG. Is performed by three-dimensionally scanning.

  As described with reference to FIG. 10, the waveform data reflected from the object surface 101 </ b> D recorded in the data recording unit 104 </ b> E includes information on the distance between the array probe 100 and the object 101, the array probe 100, and the like. Information on the angle of the subject 101 is included.

  In the relationship of the maximum amplitude MAX_A (θx) of the reflected echo group with respect to the sensor rotation angle θx displayed on the display unit 105C, the angle at which the maximum amplitude MAX_A (θx) becomes the maximum value is defined as θxm. At the sensor rotation angle θxm, the array probe and the subject are facing each other (incidence angle 0 degree). In the example shown in FIG. 13, the incident angle θA at the incident point of the ultrasonic wave on the subject is, for example, 5 degrees. On the other hand, in the display example of the display unit 105C of FIG. 10, if the sensor rotation angle θxm + 5 degrees is the sensor angle θxA, the incident angle can be 5 degrees if the sensor angle is θxA. When the incident angle is 0 degree, the sensor angle is θxm. Thus, the incident angle can be set to a predetermined angle.

  Next, in the display example shown on the display unit 105D, the distance R0 is a predetermined distance. When the distance when the sensor angle is θxA is RA, the distance between the sensor and the subject surface can be set to a predetermined distance R0 by moving the distance by (RA−R0).

Prior to the implementation of ultrasonic flaw detection (step S1803), an eddy current flaw detection (using a remote scanning mechanism used for ultrasonic flaw detection and a remote drive mechanism having a drive shaft sharing one or more drive shafts) When another process such as step S1802) is performed, the accuracy of the teaching value used for ultrasonic flaw detection can be improved by using, for example, the teaching value used for overcurrent flaw detection as the initial value for teaching. This makes it possible to reduce the deviation from the set value for the confirmation at the time of flaw detection (step S1910) in advance, so that flaw detection can be performed more efficiently in a short time.

  As described above, it is possible to specify the positional relationship between the array probe and the subject by performing the flaw detection at the medium sound speed and the flaw detection at the object sound speed in the step during the flaw detection and the teaching step before the flaw detection. By being able to do so, a more reliable ultrasonic flaw detection can be provided.

  Next, as an ultrasonic flaw detection method using the ultrasonic flaw detector according to the present embodiment with reference to FIGS. 15 to 17, an example using a linear scan method in a phased array method using an array probe is used. explain. The configuration of the ultrasonic flaw detector according to the present embodiment is the same as that shown in FIG. The configuration of the remote scanning mechanism 102 used in the ultrasonic flaw detector according to the present embodiment is the same as that described with reference to FIG. Furthermore, the configuration of the ultrasonic transmission / reception apparatus 104 used in the ultrasonic flaw detection apparatus according to the present embodiment is the same as that described with reference to FIG.

First, the configuration of the array probe used in this example will be described with reference to FIG.
FIG. 15 is an explanatory diagram of the configuration of the array probe used in the ultrasonic flaw detector according to one embodiment of the present invention. FIG. 15A is a bottom view, and FIG. 15B is a front view.

  Here, the basic configuration of the array probe is the same as that shown in FIG. An active element array, which is a feature of the linear scan array probe 100 'used in this example, will be described. As shown in the figure, the array probe 100 'is composed of N ultrasonic coarse transmitting / receiving elements 1202 arranged in a line. In the linear scan method, for example, when the number of element groups (active elements) used for transmission / reception is n, the (j + n−1) th element is activated from the jth element. In the linear scan method, the transmission / reception position 1501 of the active element group is switched by changing the start element number of the active element from, for example, 1 to (Nn-1) th by changing the delay pattern. Perform flaw detection.

Next, the flaw detection method using the ultrasonic flaw detector according to the present embodiment will be described with reference to FIGS.
16 and 17 are explanatory diagrams of a linear scan type flaw detection method using an ultrasonic flaw detector according to an embodiment of the present invention. FIG. 16 is a flaw detection screen using the sound speed of the medium. FIG. 17 is a flaw detection screen using the sound speed of the subject.

  First, the flaw detection screen using the sound speed of the medium (water in the water immersion method) between the subject and the array probe will be described with reference to FIG.

An ultrasonic wave 1601 is transmitted from the array probe 100 ′ into a medium such as water.
A delay pattern is set from the array probe 100 ′ to the subject 100 so that the transmission / reception position 1501 (FIG. 15) of the active element group changes, and ultrasonic waves are transmitted while changing the transmission / reception position Xi. To do. For example, the number of active element groups is set to 32 elements (n = 32) out of 128 elements (N = 128).

  The ultrasonic wave 1601 transmitted from the array probe 100 'is reflected by the subject surface 101D and received again by the array probe 100'. The received signal is recorded as one waveform for each transmission / reception position Xi in the data recording unit 104E of FIG. Assuming that the amplitude value of the point 1602B at the one-way propagation time T1 in the reflected wave of the subject surface 101D is A (T1; Xi), the angle θ1 is propagated as a shaded black and white or color pixel having the amplitude value intensity. A flaw detection image 1603 and a reflection image from the subject surface 101D can be obtained by displaying on the display unit 105E in a parallelogram shape with a path length (product of time T1 and sound velocity of the medium).

  Furthermore, the shape of the subject surface 101D can be specified from the image of the waveform rising point 1602A among the reflected waves of the subject surface 101D.

  Further, the distance between the array probe and the subject can be specified from the image of the subject surface shape from the distance in the direction directly below the sensor.

  In FIG. 16, the propagation angle (incident angle) from the array probe 100 ′ to a medium such as water has been described as 0 °. However, for example, even with an oblique component such as 10 °, the shape of the subject surface 101 </ b> D is similarly obtained. be able to.

  Next, the flaw detection screen using the sound speed of the subject will be described with reference to FIG.

  The flaw detection based on the sound speed of the subject and the flaw detection based on the sound speed of the medium (water, etc.) are set by, for example, switching the delay pattern based on the sound speed of the subject and the delay pattern based on the sound speed of the medium at the same time or switching. It can be realized.

  An ultrasonic wave 1701 is transmitted from the array probe 100 ′ into a medium such as water.

  A delay pattern is installed from the array probe 100 ′ to the subject 100 so as to change the propagation angle (refraction angle) in the subject, and an ultrasonic wave is transmitted with the incident angle θA fixed. Change the transmission / reception position. Note that the refraction angle θB from the medium to the subject when incident on the subject at θA is given by sinθA = sinθB × (V ′ / V) according to Snell's law. V ′ is the sound speed of a medium such as water, and V is the sound speed of the subject.

  The ultrasonic wave 1701 transmitted from the array probe 100 ′ is refracted to the inside of the subject by the subject surface 101D, propagates into the subject, and when the reflection source 103 such as a defect exists in the subject, The signal reflected by the reflection source 103 is refracted by the subject surface 101D and received by the array probe 100 again.

  The received signal is recorded as one waveform for each transmission / reception position Xj in the data recording unit 104E of FIG. Assuming that the amplitude value of the point 1702B of the one-way propagation time T2 among the reflected waves of the reflection source 103 inside the subject is A (T2; Xj), transmission / reception is performed as light and shade black-and-white or color pixels having the amplitude value intensity. By displaying the point position Xj and the propagation path (the product of time T1 and the sound velocity of the subject) on the display unit 105E in a parallelogram shape, a flaw detection image corresponding to a cross-sectional view of the subject can be obtained.

  As described above, the display unit 105 can display an acoustic image based on the sound speed of a medium such as water and an acoustic image based on the sound speed of the subject, and the positional relationship between the array probe and the subject can be determined based on the acoustic image based on the medium sound speed. The ultrasonic image of the subject can be determined by the acoustic image based on the sound velocity of the subject.

When automatic ultrasonic flaw detection (AUT) is performed using the remote scanning mechanism 102 while controlling the probe position of the array probe 100, for example, a robot having six or more axes is used as shown in FIG. Thus, the probe position is scanned so that the angle and distance between the array probe and the subject are constant. Note that water exists as the medium between the array probe and the subject, and the distance between the array probe and the subject is set to about 30 mm, for example.

  As in this example, in addition to the ultrasonic flaw detection using the sound velocity of the subject performed in the conventional ultrasonic inspection, the flaw detection based on the sound velocity of the medium (such as water) existing between the array probe and the subject. Is performed simultaneously (or by switching), the distance between the array probe and the subject is specified, and the shape of the subject directly under the array probe is specified, thereby detecting the array probe at the time of flaw detection. And the exact positional relationship between the subject and the subject can be specified.

  In this way, the mutual positional relationship is specified, so that the position of the reflection source can be more accurately evaluated. The reliability of the measurement accuracy of the reflection source position and the dimensional measurement accuracy of the reflection source position is high. High inspection can be provided.

  As described above, according to this embodiment, in addition to the flaw detection based on the sound velocity of the subject that is normally performed, the flaw detection is performed based on the sound velocity of the medium existing between the array probe and the subject. The shape of the specimen surface can be specified, and the distance between the array probe and the subject can be specified.

  Further, it is possible to set the array probe and the subject at the directly facing position according to the intensity of the signal from the subject surface.

  Therefore, regardless of the set value of the position of the array probe and the subject, the positional relationship between the two at the time of actual flaw detection can be specified, and even if there is a deviation in the positional relationship, the sound speed of the medium Since the distance and angle between the array probe and the subject can be specified from the flaw detection result obtained by the above, it is possible to correct the positional relationship and provide a more accurate flaw detection result.

  In addition, the teaching point for the position of the array probe can be provided more accurately by using the sound speed of the medium and the sound speed of the subject in teaching performed before the flaw detection is performed, and the positional deviation during flaw detection is reduced. It becomes possible to provide a more accurate flaw detection result.

  In addition, if there is teaching information for automatic scanning performed prior to flaw detection in teaching performed prior to flaw detection, this information can be used to provide teaching points for the position of the array probe more accurately. In addition, it is possible to reduce positional deviation during flaw detection, and to provide more accurate flaw detection results.

In addition, the defect image can be inspected by displaying the acoustic image based on the sound velocity of the subject, and the positional relationship between the array probe and the subject can be specified by displaying the acoustic image based on the sound velocity of the medium. The measurement position accuracy of the reflection source position of the acoustic image by the specimen sound speed and the accuracy of the defect dimension measurement are improved.

DESCRIPTION OF SYMBOLS 100,100 '... Array probe 101 ... Subject 102 ... Remote scanning mechanism 104 ... Ultrasonic transmission / reception apparatus 105 ... Ultrasonic image display means 110 ... Drive control apparatus

Claims (2)

An ultrasonic flaw detection method for propagating ultrasonic waves transmitted from an ultrasonic probe to a subject through a medium and scanning the ultrasonic probe using a remote scanning mechanism,
Using an ultrasonic transmitter / receiver, teaching the probe position to enable scanning to keep the ultrasonic probe at a predetermined distance and angle with respect to the subject,
The teaching, the reflected wave on the front surface or these object received as the first received signal, displaying the inspection image by the first reception signal, as a first acoustic image using the acoustic velocity of the medium And so as to obtain the surface profile of the subject,
Based on the surface profile of the subject obtained by the teaching, the ultrasonic probe with respect to the subject is maintained at a predetermined distance and angle by a drive control device, and the ultrasonic transmitting / receiving device is used. Conducting a test of the subject,
The testing of the subject, the reflected waves from the inner part of the subject received as a second received signal, the flaw detection image by the second reception signal, a second acoustic using sound velocity of the subject and displayed as an image, and at the same time or by switching to receive a table surface or these reflected waves of the subject as the first reception signal, the flaw detection image by the first received signal, using a sound velocity of the medium And displaying as a first acoustic image. The ultrasonic flaw detection method according to claim 1,
The drive control device applies ultrasonic waves to an angle θxm at which the maximum amplitude MAX_A (θx) has a maximum value in the maximum amplitude MAX_A (θx) of the reflected echo group with respect to the rotation angle θx of the ultrasonic probe. A value obtained by adding the incident angle θA at the incident point on the specimen is defined as a sensor angle θxA. Based on the distance RA at the sensor angle θxA, the distance ( An ultrasonic flaw detection method characterized by maintaining the ultrasonic probe with respect to the subject at a predetermined distance and angle by moving only RA-R0).

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