JP5908549B2 - Ultrasonic inspection equipment - Google Patents

Description

  The present invention relates to an ultrasonic inspection apparatus that visualizes a state such as a defect in a structure or a component, a void, or a peeling of a joint using ultrasonic waves transmitted and received by a piezoelectric transducer.

Using an ultrasonic inspection apparatus, it is widely practiced to evaluate states such as defects, voids, and peeling of joints in structures and parts to be inspected.
The echo waveform, which is the reflected wave of the ultrasonic wave irradiated to the inspection object, is derived from the surface, defect, and back surface of the inspection object. And in order to detect a defect, the process which extracts paying attention to the echo waveform originating in this defect is needed. In order to extract this echo waveform, a gate is provided that starts after passing the echo waveform derived from the front surface and ends before passing the echo waveform derived from the back surface, and the echo waveform passing through this gate is derived from the defect. handle. By detecting the intensity and timing of the echo waveform derived from the defect, information such as the position and size of the defect in the inspection object is visualized (for example, Patent Document 1).

JP 2003-121426 A

  However, in a conventional ultrasonic inspection apparatus using such a gate, it is necessary to set a plurality of gates having different widths when the distance between the front surface and the back surface of the inspection target is not constant. However, it is difficult to replace the appropriate gate among the plurality in synchronization with the shape change of the inspection object, and there is a problem that the accuracy of defect detection such as false detection is lowered particularly when this shape change is complicated. .

  The present invention has been made in consideration of such circumstances, and an ultrasonic inspection apparatus capable of performing inspection of internal defects, voids, and peeling with high accuracy and ease in an inspection object that is two-dimensionally displayed internally. The purpose is to provide.

An ultrasonic inspection apparatus according to the present invention includes an ultrasonic transducer that obtains an echo signal by irradiating a structure or article to be inspected with ultrasonic waves , and a tertiary that processes the echo signal and visualizes the inside of the inspection object. a signal processing unit for generating the original image information, to define the upper part region of interest of the back surface of the surveyed said ultrasonic waves have you inside the test object is reflected, more space definition that defines the coordinate information about the coordinate transformation A rotation unit that rotates any one of the inspection object and the ultrasonic transducer, and an inspection data generation unit that generates a 3D image for inspection from which image information other than the region of interest in the 3D image information is removed mechanism and the echo signal the inspection three-dimensional image perpendicular to the setting axis defined by the coordinate information about the defect image that is certified by from the region of interest Defect image area of any cross-section is characterized in that comprises a two-dimensional imaging unit for imaging a cross section of maximum, the.

  ADVANTAGE OF THE INVENTION According to this invention, the apparatus for ultrasonic inspection which can test | inspect accurately the defect which exists in the inside of the inspection object of complicated shape with high precision is provided.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows 1st Embodiment of the apparatus for ultrasonic inspection which concerns on this invention. (A) The perspective view of the test object of complicated shape, (B) The sectional drawing, (C) The figure which shows the waveform of an echo signal. (A) Image information based on echo signal detected by ultrasonic transducer, (B) attention area in detection range, (C) extracted image of detected defect, (D) defect image area in detected defect is maximized The figure which each shows the cross-sectional image of the part which becomes. Explanatory drawing of the correction | amendment function of the reference plane in an ultrasonic inspection apparatus. The block diagram which shows 2nd Embodiment of the apparatus for ultrasonic inspection which concerns on this invention. The block diagram which shows the modification of 2nd Embodiment of the apparatus for ultrasonic inspection which concerns on this invention. (A) Longitudinal sectional view showing an arrangement relationship between the ultrasonic inspection apparatus according to the second embodiment and an inspection object, (B) a cross-sectional image captured at one stationary position, and (C) continuous rotation of the inspection object. The figure which shows each of several cross-sectional image imaged automatically. (A) The figure which shows an example of the display system of the defect contained in the test object imaged with the ultrasonic inspection apparatus which concerns on 2nd Embodiment, (B) The example of another display system, respectively. An arithmetic expression for executing conversion from the rectangular display shown in FIG. 8A to the circular display shown in FIG. 8B in the second embodiment.

(First embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
As shown in FIG. 1, an ultrasonic inspection apparatus includes an ultrasonic transducer 2 that is brought into contact with an inspection object 3 via a coupling 27 and a shoe 25, and an apparatus main body 1 that is connected to the ultrasonic transducer 2 with a cable. It is composed of
The apparatus body 1 includes a signal generation unit 10, a drive element selection unit 11, a signal detection unit 12, an amplification unit 13, an A / D conversion unit 14, a signal processing unit 15, a region definition unit 16, and an attention. An area data storage unit 17, a two-dimensional information storage unit 18, a determination threshold data storage unit 19, an inspection data generation unit 20, a two-dimensional imaging unit 21, a defect determination unit 22, a display device 23, The control unit 24, the reference surface detection unit 28, the correction information storage unit 30, and the correction processing unit 31 are configured.

The ultrasonic transducer 2 has a plurality of piezoelectric transducers 26 made of piezoelectric elements arranged in a matrix or a straight line, and each piezoelectric transducer 26 is driven by selection of the drive element selector 11. Is determined and the drive signal from the signal generator 10 is derived. When this electrical drive signal is input, the piezoelectric conversion 26 generates an ultrasonic wave as a property of the piezoelectric body, and this ultrasonic wave reaches the defect 4 in the inspection object 3 through the shoe 25. Then, the ultrasonic echo U reflected from the defect 4 is input again to the piezoelectric conversion unit 26 via the shoe 25, and an electric signal generated in each is guided to the signal detection unit 12.
As described above, the ultrasonic transducer 2 outputs an ultrasonic wave toward the inspection object 3 and receives an ultrasonic echo reflected from the internal defect 4 and further from the front surface 3a and the back surface 3b.

The signal generation unit 10 generates a pulse-like or continuous drive signal that causes the piezoelectric conversion unit 26 to generate an ultrasonic wave, and guides it to the drive element selection unit 11. The drive element selection unit 11 guides a drive signal derived from the signal generation unit 10 after selecting one or a plurality of piezoelectric conversion units 26 to be driven.
The signal detection unit 12 detects a weak analog electric signal generated by the piezoelectric conversion unit 26, and the analog signal applied to the inspection is guided to the amplification unit 13.

The amplifying unit 13 amplifies the derived analog signal and supplies it to the A / D conversion unit 14. The A / D converter 14 A / D converts the derived analog signal into a digital signal, and guides the signal to the signal processor 15.
The signal processing unit 15 includes a parallel processor inside, and processes the digital signal derived from the A / D conversion unit 14 and generates the three-dimensional image information Q for visualizing the internal state of the inspection object 3 by aperture synthesis processing. Generate.

  At the time of inspection, the region definition unit 16 generates definition information of the attention region R inside the inspection object 3, coordinate information T for displaying the inside of the inspection object 3 two-dimensionally, and threshold information G that defines a threshold value for determining a defect. These are generated and stored in the attention area data storage unit 17, the two-dimensional information storage unit 18, and the determination threshold value data storage unit 19, respectively.

The inspection data generation unit 20 applies the definition information of the attention area R stored in the attention area data storage section 17 to the three-dimensional image information Q generated by the signal processing section 15, and obtains image information other than the attention area R. The removed inspection three-dimensional image S is generated.
The two-dimensional imaging unit 21 uses the coordinate information T stored in the two-dimensional information storage unit 18 to convert an arbitrary cross section of the inspection three-dimensional image S orthogonal to the set axis as the inspection two-dimensional image F.

  The correction processing unit 31 corrects the input inspection two-dimensional image F and outputs a corrected two-dimensional image K.

The defect determination unit 22 applies the threshold information G stored in the determination threshold data storage unit 19 to the input inspection two-dimensional image F, and determines the presence / absence, area, etc. of the region above or below the threshold. Calculated and displayed on the display device 23.
The above operations are comprehensively controlled by the control unit 24, and a series of operations such as driving of the ultrasonic transducer 2, transmission of ultrasonic waves, reception, image information generation, attention area extraction, determination, and display are executed.

With reference to FIG. 2, an inspection example of the inspection object 3 having a complicated shape using the ultrasonic inspection apparatus according to the present embodiment will be described.
As shown in FIG. 2A, the inspection object 3 is a complicated shape having a back surface shape in which the back surface 3b is undulated. The ultrasonic transducer 2 is brought into contact with the flat surface 3a and moved in the X direction for inspection. I do. Although not shown in the figure, it is assumed that appropriate shoes and couplings are used.

  As shown in the cross-sectional view of the inspection object 3 in FIG. Then, the ultrasonic transducer 2 irradiates the attention area R of the inspection object 3 with ultrasonic waves from the front surface 3a toward the back surface 3b. Then, the ultrasonic echo is reflected from the front surface 3a, the back surface 3b, and the defect 4 existing inside the region of interest R.

  FIG. 2C is an echo signal obtained by converting the ultrasonic echo received by the ultrasonic transducer 2 into an electrical signal, and is displayed so that time elapses from the left to the right in the figure. The waveform on the right side is the surface echo waveform 5 corresponding to the front surface 3a, the waveform on the left side is the back surface echo waveform 6 corresponding to the back surface 3b, and when there is a defect 4, the surface echo waveform 5 and the back surface echo waveform 6 are present. In the meantime, the defect echo waveform 7 is displayed.

A process for visualizing defects detected by the ultrasonic inspection apparatus will be described with reference to FIG.
FIG. 3A is a side view of the three-dimensional image information Q generated by the signal processing unit 15. Although it is displayed in a plane in the drawing, image information is actually generated also in the depth direction of the drawing. Both the linear array probe and the matrix array probe can be used as the ultrasonic transducer 2, but in the case of the linear array probe, a cross-sectional image immediately below the ultrasonic transducer 2 (the opening direction of the probe is represented by Y in one imaging). A two-dimensional image of the YZ plane) is generated where the axis is the axis and the depth direction of the inspection object is the Z axis. A plurality of cross-sectional images are sequentially generated by moving (scanning) the ultrasonic transducer 2 in the X direction, and the three-dimensional image information Q shown in FIG. When the matrix array probe is used, a unit image having a three-dimensional structure of XYZ is generated at one time, and the same three-dimensional image information Q is generated by combining the unit images.

  The image in FIG. 3A includes a front surface echo image Ea and a back surface echo image Eb of the inspection object 3 (FIG. 2). In order to extract only the portion of the attention area R shown in FIG. 3B, definition information created by the area definition section 16 (FIG. 1) and stored in the attention area data storage section 17 is used.

  Then, in the inspection data generation unit 20, the 3D image information Q generated by the signal processing unit 15 is designated by performing processing based on the definition information of the attention area R stored in the attention area data storage section 17. Only the data of the attention area R is extracted and converted into the inspection three-dimensional image S from which the front surface echo image Ea and the back surface echo image Eb are removed as shown in FIG.

  Here, the definition information of the attention area R is mesh data in which the constituent pixels of the attention area R are “1” and other portions are “0”, and the mesh data is generated by the signal processing unit 15. By multiplying the information Q by the mesh unit, only the data corresponding to the attention area R is extracted. In this example, a rectangular area is shown as the attention area R. However, the attention area R is not limited to a rectangle and can be set to an arbitrary shape.

  The coordinate information T related to the coordinate transformation defined by the region definition unit 16 is stored in the two-dimensional information storage unit 18. This coordinate information T is a coordinate system consisting of the three axes xyz illustrated in FIG. 3C, and is separate from the XYZ coordinate system defined with the inspection object 3 as a reference. In FIG. 3, since the attention area R is the upper part of the undulating back surface 3b, a defect image is conventionally projected on a plane (XY plane) orthogonal to the traveling direction of the ultrasonic wave (Z axis) in the XYZ coordinate system. Two-dimensional imaging is performed in the form. For this reason, conventionally, when the defect 4 having the inclined main surface is imaged with respect to the XYZ coordinate system set with the inspection object 3 as a reference, a two-dimensional image of the defect 4 having a distorted shape is generated. .

  Therefore, in the present embodiment, the two-dimensional imaging unit 21 images a surface having the maximum defect image area in an arbitrary cross section of the defect 4 orthogonal to the setting axis (here, the z axis). That is, an xyz coordinate system is defined so that the z-axis is orthogonal to the main surface of the defect 4, and two-dimensional imaging is performed on a plane along the xy plane coordinates. Thereby, a two-dimensionalized inspection two-dimensional image F parallel to the main surface of the defect 4 as shown in FIG.

  The threshold information G defined by the region definition unit 16 and stored in the determination threshold data storage unit 19 is applied to the inspection two-dimensional image F (or the corrected two-dimensional image K), and the defect determination unit 22 performs the calculation. Run. Thereby, a display two-dimensional image H in which the defect 4 is imaged is generated and displayed by the display device 23. The display two-dimensional image H is performed by comparing the pixel values of the pixels constituting the inspection two-dimensional image F with the threshold information G stored in the determination threshold data storage unit 19. Although it is determined that the image is derived from the defect 4 at the lower threshold or higher or lower than the upper threshold, the present invention is not limited to this method.

  On the other hand, the defect determination unit 22 may change and apply the threshold information G based on reference plane correction information P by a reference plane detection unit 28 described later. This is because the intensity of the ultrasonic echo derived from the defect 4 changes as the relative distance between the front surface 3a and the back surface 3b of the inspection object 3 and the ultrasonic transducer 2 changes.

  Furthermore, the defect determination unit 22 can determine the intensity of the inspection two-dimensional image F and apply the threshold information G by changing the threshold information G. This is because the generated inspection two-dimensional image F is bright or dark as a whole depending on the inspection conditions, and does not always have the same intensity. For this reason, when the same threshold value information G is applied, it may be assumed that there are different determinations such as no defect and presence of a defect depending on different inspection conditions. In order to deal with such a situation, for example, the average image intensity of the generated two-dimensional image F for inspection is calculated, and if this average value is higher than the reference value, the threshold applied to the determination is corrected to be high. If it is lower than the reference value, the threshold value to be applied is corrected to be low. Accordingly, it is possible to perform appropriate defect determination even for a plurality of two-dimensional inspection images having different brightness intensities that are imaged by changing the inspection conditions.

  The reference plane detection unit 28 shown in FIG. 1 determines a reference plane to which the definition information of the attention area R stored in the attention area data storage section 17 is applied from the three-dimensional image information Q generated by the signal processing section 15. The correction information P to be corrected is output. The reference plane correction information P is transferred from the reference plane detection unit 28 to the inspection data generation unit 20, and the above-described correction of the reference plane is executed.

The operation of the reference plane detection unit 28 will be described with reference to FIG.
During the ultrasonic inspection, the distance between the ultrasonic transducer 2 and the inspection object 3 may change. If this happens, it is difficult to correctly set the attention area R in the inspection object 3, but the reference plane detection unit 28 is for coping with such a problem.

  When the distance between the ultrasonic transducer 2 and the inspection object 3 changes, as shown in FIGS. 4A to 4B, the position of the surface echo Ea in the three-dimensional image information Q is relative to the reference plane. Will change. The reference plane detection unit 28 detects the current surface position B in the 3D image information Q, and subtracts the surface position A of the definition information of the attention area R stored in the attention area data storage section 17 as a reference plane. Then, the reference plane correction information P is calculated. The reference plane correction information P is output to the inspection data generation unit 20 and corrects the position where the definition information of the attention area R is applied, as shown in FIG. As a result, even when the distance between the ultrasonic transducer 2 and the inspection object 3 changes, the correct three-dimensional image S for inspection can be extracted.

  On the other hand, the reference plane correction information P generated by the reference plane detection unit 28 is applied to the defect determination unit 22, and the threshold information G is appropriately changed even if the position of the front surface 3a or the back surface 3b of the inspection target 3 changes. Can be applied. As a result, even if the distance between the ultrasonic transducer 2 and the inspection object 3 changes and the ultrasonic propagation conditions change inside the inspection object 3, the threshold information T is corrected and the inspection two-dimensional image F is corrected. On the other hand, it is possible to correctly determine the defect 4.

  The correction information storage unit 30 illustrated in FIG. 1 has a function of storing correction information J for the region definition unit 16 to correct the inspection two-dimensional image F. Then, the correction processing unit 31 uses the correction information J to perform multiplication or addition for each mesh of the inspection two-dimensional image F generated by the two-dimensional imaging unit 21, or two predefined two-dimensional tables. 1 is added and the other is added to generate a corrected two-dimensional inspection image K and send it to the defect determination unit 22.

  In general, the inspection two-dimensional image F generated by the two-dimensional imaging unit 21 may not necessarily be uniform due to the influence of the internal state of the inspection object 3, the propagation path of ultrasonic waves, and the like. If the defect determination unit 22 applies the threshold information F to the inspection two-dimensional image F and performs defect determination, the defect detection accuracy may be lacking.

  Therefore, in order to deal with such an event, the correction information J created in advance considering the internal state of the inspection object 3, the ultrasonic propagation path, etc. is stored in the correction information storage unit 30, and this correction information is stored. The correction processing unit 31 applies J to the inspection two-dimensional image F so that a uniform correction two-dimensional inspection image K can be generated.

(Second Embodiment)
FIG. 5 is an explanatory diagram of an ultrasonic inspection apparatus according to the second embodiment of the present invention. In the second embodiment, a rotation mechanism (turn table 33a) that rotates in a state where a cylindrical or cylindrical inspection object 3 is placed is provided. Then, the ultrasonic transducer 2 is fixed to the upper surface or the side surface of the inspection object 3 so that it can be acoustically coupled through a coupling agent such as water, and the inside of the rotating inspection object 3 is inspected. Although not shown in the drawing, the entire structure is placed in a water tank so that a coupling agent such as water is interposed between the ultrasonic transducer 2 and the inspection object 3.

FIG. 6 is an explanatory diagram of a modification of the ultrasonic inspection apparatus according to the second embodiment. In this modification, the ultrasonic transducer 2 arranged on the upper surface or side surface of a cylindrical or cylindrical inspection object 3 is fixed to a mechanism (turn table 33b) that rotates around the inspection object 3. It has become.
This turntable 33b is driven by the rotational drive mechanism 32, and the ultrasonic transducer 2 is attached to the lower surface thereof.

  Although not shown, the ultrasonic transducer 2 and the inspection object 3 are acoustically coupled by placing the whole in a water tank so that a coupling agent such as water is interposed therebetween. In this example, since the ultrasonic transducer 2 and the apparatus main body 1 are directly connected by a cable, the turntable 33b does not rotate continuously, but performs a reciprocating operation in a range of −180 degrees to +180 degrees. Assumed. Alternatively, the turntable 33b can be continuously rotated by providing a rotation signal transmission mechanism such as a slip ring in the middle of the cable connected to the ultrasonic transducer 2.

FIG. 7 is an explanatory diagram of an imaging method in the ultrasonic inspection apparatus according to the second embodiment.
In the second embodiment, the ultrasonic transducer 2 may be arranged parallel to the upper surface of the inspection object 3 or may be arranged with a certain inclination. FIG. 7A shows an example in which there is an inclination, and the ultrasonic wave is refracted on the upper surface of the inspection object 3 and enters the inspection object 3 as indicated by the incident path 34. It is assumed that water is interposed between the ultrasonic transducer 2 and the inspection object 3. An area that is imaged inside the inspection object 3 by the ultrasonic transducer 2 is an imaging area 35 indicated by a broken line, and every time a predetermined angle is displaced along with the rotation of the inspection object 3 around the Z axis. The imaging of the YZ plane as shown in FIG. 7B is performed. When the entire inspection object 3 is inspected, an image generated by one rotation around the Z axis is evaluated, and the obtained inspection image is in the YZ plane as shown in FIG. A bundle of rectangular cross sections.

  In this example, it is assumed that the defect 4 in the region parallel to the upper surface of the inspection target inside the inspection target 3 is inspected, and the coordinate information T for converting the obtained three-dimensional image information Q into the inspection two-dimensional image F. Is the XYZ coordinate system shown in FIG. Then, this XYZ coordinate system is applied to the three-dimensional image information Q shown in FIG. 7A, and an XY two-dimensional image in which the cross-sectional area of the defect 4 orthogonal to the Z axis shows the maximum value is an inspection two-dimensional image. It will be adopted as F.

  Therefore, the coordinate information T stored in the two-dimensional information storage unit 18 (FIG. 1) in the second embodiment is the YZ plane shown in FIG. 7C generated by the inspection data generation unit 20. A three-dimensional image S for inspection composed of a bundle of rectangular cross sections is converted into a two-dimensional image F for inspection displayed in a YX rectangle as shown in FIG. 8A, and as shown in FIG. 8B. A function of converting into a two-dimensional image F for inspection displayed in a circular form Xc-Yc is provided. In the two-dimensional imaging unit 21, one of the functions of the coordinate information T is selected, and a coordinate conversion process is performed from the inspection three-dimensional image S to the inspection two-dimensional image F.

FIG. 9 is an example of an arithmetic expression for executing conversion from the rectangular display shown in FIG. 8A to the circular display shown in FIG. 8B in the second embodiment.
Here, the A coordinate (xcA, ycA) after the circular display conversion shown in FIG. 8B and the A coordinate (xA, yA) of the rectangular display before the conversion shown in FIG. 8A corresponding thereto. Is related by the arithmetic expression shown in FIG. However, the 12 o'clock direction of the image after the circular display conversion is the conversion base point, and the rectangular image is converted into a circular display in the clockwise direction using this as the base point. The length xe of the rectangular image corresponds to one rotation.

  In FIG. 9, yofs is one parameter for circular display conversion, and determines the radial display position of the original rectangular image when circular display is performed. A process for obtaining coordinates on the YX coordinate system for each point in the Xc-Yc coordinate system, taking out a two-dimensional image for inspection at that point, and pasting it on the Xc-Yc coordinate system is necessary for the Xc-Yc coordinate system. By performing this over the entire range, the rectangular image can be converted into a circle and displayed. If necessary, scale conversion or the like can be performed by multiplying the first term on the right side by a coefficient to obtain yA. The area definition unit 16 has a function to define yofs, a circular transformation direction (clockwise, counterclockwise), a coefficient to be multiplied by the first term on the right side, and the like, which is stored in the two-dimensional information storage unit 18. The two-dimensional imaging unit 21 may perform circular display conversion of a rectangular image as in the above example.

As described above, the ultrasonic inspection apparatus according to the present invention makes it possible to specify a region of interest inside a complicated inspection target in detail and to determine a defect using a high-precision two-dimensional image. Defects, voids, and delamination can be accurately extracted and inspected.
The present invention is not limited to the above-described embodiments, and can be appropriately modified and implemented within the scope of the common technical idea.

  DESCRIPTION OF SYMBOLS 1 ... Apparatus main body, 2 ... Ultrasonic transducer, 3 ... Inspection object, 3a ... Front surface, 3b ... Back surface, 4 ... Defect, 5 ... Surface echo waveform, 6 ... Back surface echo waveform, 7 ... Defect echo waveform, 10 ... Signal generation 11, drive element selection unit, 12, signal detection unit, 13, amplification unit, 14, A / D conversion unit, 15, signal processing unit, 16, region definition unit, 17, attention region data storage unit, 18,. Two-dimensional information storage unit, 19 ... Determination threshold data storage unit, 20 ... Inspection data generation unit, 21 ... Two-dimensional imaging unit, 22 ... Defect determination unit, 23 ... Display device, 24 ... Control unit, 25 ... Shoe, DESCRIPTION OF SYMBOLS 26 ... Piezoelectric conversion part, 27 ... Coupling, 28 ... Reference plane detection part, 30 ... Correction information storage part, 31 ... Correction processing part, 32 ... Rotation drive mechanism, 33a, 33b ... Turntable, 34 ... Incident path, 35 ... imaging area, Ea ... surface eco Image, Eb ... Back echo image, Ec ... Defect echo image, P ... Reference plane correction information, Q ... Three-dimensional image information, R ... Region of interest, S ... Three-dimensional image for inspection, T ... Coordinate information, G ... Threshold information , H: display two-dimensional image, J: correction information, K: correction two-dimensional inspection image.

Claims (4)

An ultrasonic transducer that obtains an echo signal by irradiating the structure or article to be inspected with ultrasonic waves;
A signal processor for processing the echo signal and generating three-dimensional image information that visualizes the inside of the inspection object;
A region defining section for the have you inside of the test object by defining a region of interest on the top of the back of the surveyed said ultrasound is reflected, further defines the coordinate information about the coordinate transformation,
An inspection data generation unit that generates an inspection 3D image in which image information other than the region of interest in the 3D image information is removed;
A rotating mechanism for rotating either one of the inspection object and the ultrasonic transducer;
Imaging the cross-section of the defect image area of any cross-section of the inspection three-dimensional image for defects image to be certified by the echo signal is orthogonal to the set axis defined by the coordinate information is maximized from the region of interest And a two-dimensional imaging unit.   The ultrasonic inspection apparatus according to claim 1, further comprising a water tank in which the inspection object, the ultrasonic transducer, and a coupling agent interposed therebetween are placed.   The ultrasonic inspection apparatus according to claim 1, wherein the rotation mechanism performs a reciprocating operation in a range of −180 degrees to +180 degrees.   4. The display device according to claim 1, further comprising: a display unit configured to perform coordinate conversion of a plurality of two-dimensional images obtained by the imaging for each predetermined displacement of the rotation mechanism and display the same on one coordinate. The apparatus for ultrasonic inspection according to 1.

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