JP2010078473A - Ultrasonic flaw detector and ultrasonic flaw detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detector and an ultrasonic flaw detection method capable of improving sensitivity of UT by increasing SH wave components of an inspection wave. <P>SOLUTION: In this ultrasonic flaw detector having a UT sensor 1 on which a plurality of ultrasonic elements 5 for transmitting an SH wave to a defect 3 are arranged, assuming that the length and the curvature in the major axis direction of the defect 3 are W1, R1 respectively, the length and the curvature in the minor axis direction of the defect 3 are W2, R2 respectively, the length and the curvature in the major axis direction of the UT sensor 1 are W1', R1' respectively, and the length and the curvature in the minor axis direction of the UT sensor 1 are W2', R2' respectively, the bottom surface of the UT sensor 1 has a curved surface shape so as to fulfill relations: (1) R1'÷R1=W1'÷W1, (2) R2'÷R2=W2'÷W2, and a shoe 7 for propagating an ultrasonic wave is provided between an inspection object 2 and each ultrasonic elements 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ultrasonic flaw detection apparatus and an ultrasonic flaw detection method.

  Ultrasonic flaw detection (hereinafter referred to as UT) is an inspection method in which an ultrasonic wave is incident on an inspection target and a reflected wave from a defect is detected (see Patent Document 1).

JP 11-337540 A

  In a conventional UT using a transverse wave, a vertically polarized transverse wave (hereinafter referred to as an SV wave) is used. The SV wave is an ultrasonic mode that vibrates in a plane perpendicular to the inspection surface. The reflection efficiency of the SV wave depends on the incident angle, and a part of the incident wave is converted into a longitudinal wave and attenuates at the time of reflection, so that the signal intensity is lowered. Since this attenuation factor depends on the incident angle, there is a problem that the detection sensitivity varies greatly depending on the incident angle.

  On the other hand, when a horizontally polarized transverse wave (hereinafter referred to as SH wave) is used, a decrease in signal strength due to attenuation is suppressed. The SH wave is an ultrasonic mode in which the polarization direction is shifted by 90 ° from that of the SV wave, and conversion to a longitudinal wave does not occur at the time of reflection, and high sensitivity flaw detection is possible because of high reflection efficiency.

  The present invention has been made in view of the above, and an object of the present invention is to provide an ultrasonic flaw detection apparatus and an ultrasonic flaw detection method capable of improving the sensitivity of the UT by increasing the SH wave component of the inspection wave.

(1) In order to achieve the above object, the present invention is an ultrasonic flaw detection apparatus having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to defects are arranged. The length and curvature in the major axis direction of the defect of the three-dimensional curved surface shape are W1 and R1, respectively, the length and curvature in the minor axis direction of the defect are W2 and R2, respectively, and the length and curvature in the major axis direction of the ultrasonic flaw detection sensor. Are W1 ′ and R1 ′, and the length and curvature in the minor axis direction of the ultrasonic flaw detection sensor are respectively W2 ′ and R2 ′, the bottom surface of the ultrasonic flaw detection sensor is
R1 ′ ÷ R1 = W1 ′ ÷ W1 (1)
R2 ′ ÷ R2 = W2 ′ ÷ W2 (2)
And a shoe for propagating the ultrasonic wave between the inspection object and each ultrasonic element.

  (2) In order to achieve the above object, the present invention provides an ultrasonic flaw detection apparatus having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit a horizontally polarized transverse wave to a defect are arranged, and the defect occurrence position. The plurality of ultrasonic elements are arranged such that ultrasonic waves are incident from a plurality of directions to a place assumed as follows.

  (3) In the above (2), preferably, the ultrasonic elements are arranged concentrically.

  (4) In order to achieve the above object, the present invention provides an ultrasonic flaw detection apparatus having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit a horizontally polarized transverse wave to a defect are arranged. When the occurrence of a plurality of defects having different angles is assumed, the ultrasonic element is arranged on a plane orthogonal to each defect.

  (5) In order to achieve the above object, the present invention provides an ultrasonic flaw detection apparatus having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit a horizontally polarized wave to a defect are arranged, and includes a rotary actuator and A moving mechanism that has at least two axes of translational actuators and that allows the ultrasonic flaw detection sensor to move and rotate in a plane, and calculates the shape and position of an assumed defect by executing strength calculation based on the shape information of the inspection object A calculation unit for deriving a point where the calculated normal of the defect and the surface to be inspected intersect as an ultrasonic transmission point, and instructing the moving mechanism to move the ultrasonic flaw detection sensor to the ultrasonic transmission point, A command to rotate the ultrasonic flaw detection sensor so that the ultrasonic wave transmitted toward the calculated defect position becomes a horizontal polarization transverse wave, and to instruct the ultrasonic flaw detection sensor to emit a horizontal polarization transverse wave. Characterized by comprising and.

  (6) In any one of the above (1) to (5), preferably, an angle formed by a surface orthogonal to the defect and an ultrasonic traveling axis of the ultrasonic element is 25 ° or less. .

  (7) In any one of the above (1) to (6), preferably, at least one of a stress distribution analysis device and a stress distribution analysis result database is provided.

(8) In order to achieve the above object, the present invention is an ultrasonic flaw detection method using an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit a horizontally polarized wave to a defect are arranged. The length and curvature of the three-dimensional curved surface defect in the major axis direction are W1 and R1, respectively, the minor axis length and curvature of the defect are W2 and R2, respectively, and the major axis length of the ultrasonic flaw detection sensor and When the curvature is W1 ′, R1 ′, the length in the minor axis direction of the ultrasonic flaw detection sensor and the curvature are W2 ′, R2 ′, respectively, the bottom surface of the ultrasonic flaw detection sensor is
R1 ′ ÷ R1 = W1 ′ ÷ W1 (1)
R2 ′ ÷ R2 = W2 ′ ÷ W2 (2)
And a shoe for propagating ultrasonic waves between the inspection object and each ultrasonic element.

  (9) In order to achieve the above object, the present invention provides an ultrasonic flaw detection method including an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to a defect are arranged, and the defect occurrence position. The plurality of ultrasonic elements are arranged so that ultrasonic waves are incident from a plurality of directions on a place assumed as follows.

  (10) In order to achieve the above object, the present invention provides an ultrasonic flaw detection method having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit a horizontally polarized transverse wave to a defect are arranged. When the generation of a plurality of defects having different angles is assumed, the ultrasonic element is arranged on a plane orthogonal to each defect.

  (11) In order to achieve the above object, the present invention provides an ultrasonic flaw detection method having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to defects are arranged, Based on the shape information, intensity calculation is performed to calculate the shape and position of the assumed defect, and the point where the calculated normal of the defect intersects the surface to be inspected is derived as an ultrasonic transmission point, and the ultrasonic transmission point The ultrasonic flaw detection sensor is moved to the position of the calculated defect, and the ultrasonic flaw detection sensor is rotated so that the ultrasonic wave transmitted toward the calculated defect position becomes a horizontally polarized wave, and the calculation by the ultrasonic flaw detection sensor is performed. A horizontal polarized transverse wave is transmitted to the position of the defect.

  (12) In any one of the above (8) to (11), preferably, an angle formed by a surface orthogonal to the defect and an ultrasonic traveling axis of the ultrasonic element is 25 ° or less. .

  (13) In any one of the above (8) to (12), preferably, the stress distribution of the inspection object is analyzed based on the shape of the inspection object, and an ultrasonic flaw detection is performed on a portion having a high stress distribution specified by the analysis. It is characterized by that.

  (14) In any one of the above (8) to (12), preferably, ultrasonic flaw detection is performed on a portion having a high stress distribution on a database created based on a stress distribution analysis result.

  (15) In any one of the above (8) to (12), preferably, an ultrasonic flaw detection is performed on a location with a high defect occurrence frequency based on a defect occurrence case database.

  According to the present invention, the sensitivity of the UT can be improved by increasing the SH wave component of the inspection wave.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the background art of ultrasonic flaw detection will be described along with its problems.

<First Embodiment>
Here, first, the technical background of the present embodiment will be described.

  Ultrasonic flaw detection (hereinafter referred to as UT) is an inspection method in which an ultrasonic wave is incident on an inspection object and a reflected wave from a defect is detected. When the inspection object 2 has no defect as shown in FIG. 1A, the reflected wave does not return to the UT sensor 1, but when the inspection object 2 has a defect 3 as shown in FIG. The reflected wave from the defect 3 returns to the UT sensor 1. The presence of the defect 3 is detected by detecting this reflected wave.

  A conventional UT using a transverse wave uses a vertically polarized transverse wave (hereinafter referred to as an SV wave). As shown in FIG. 2A, the SV wave is a super-vibration in a plane perpendicular to the inspection surface (reflection surface) of the inspection object 2 (a surface including the traveling axis and the polarization plane is orthogonal to the inspection surface). Sound wave mode. The SV wave reflection efficiency has the incident angle dependency shown in FIG. When the SV wave is reflected, a part of the incident wave is converted to a longitudinal wave and attenuated to reduce the signal intensity. This causes a problem of a decrease in detection sensitivity.

  On the other hand, a horizontally polarized wave (hereinafter referred to as SH wave) is an ultrasonic mode in which the polarization direction is shifted by 90 ° from the SV wave as shown in FIG. Since this SH wave does not undergo mode conversion to a longitudinal wave when reflected, the reflection efficiency is as high as 99% or more as shown in FIG. 3, and high-sensitivity flaw detection is possible.

  FIG. 4 is a conceptual diagram when the SH wave is inclined in the direction orthogonal to the paper surface and incident on the reflecting surface. The incident wave has an SH wave component and an SV wave component. Since the SH wave component and the SV wave component have dependency as shown in FIG. 5 with respect to an angle (polarization angle) formed by the reflection surface 4 and the polarization direction (polarization plane), the SH wave component is dominant. However, if the polarization angle is not 90 °, it has an SV wave component, and the SV wave component increases as the polarization angle moves away from 90 °, and the rate of reflection as an SV wave increases and the reflection efficiency decreases. . Although there is a UT sensor using an SH wave, a configuration in which a plurality of ultrasonic elements 5 are arranged in a lattice shape and accommodated in a rectangular protective case 6 as shown in FIG. When a shape defect is a target for flaw detection, the ultrasonic polarization angles of all the ultrasonic elements 5 cannot be set to 90 ° or an angle close thereto.

  Based on the above, an embodiment of an ultrasonic flaw detection apparatus and an ultrasonic flaw detection method that can increase the sensitivity of the UT by increasing the SH wave component of the inspection wave will be described.

  The present embodiment is an ultrasonic flaw detection apparatus having a UT sensor in which a plurality of ultrasonic elements that transmit SH waves to defects is arranged, and is particularly effective when the assumed defect has a three-dimensional curved surface shape. This is an example of a simple ultrasonic flaw detection.

  FIG. 8 is a schematic view of a UT sensor used in the ultrasonic flaw detector according to the first embodiment of the present invention.

As shown in FIG. 8, the ultrasonic flaw detector according to the present embodiment has a three-dimensional curved surface defect 3 with a length W1 in the major axis direction, a curvature R1, and a defect minor axis length W2. When the curvature is R2, the length in the major axis direction of the UT sensor 1 is W1 ′, the curvature is R1 ′, the length in the minor axis direction of the UT sensor 1 is W2 ′, and the curvature is R2 ′,
R1 ′ ÷ R1 = W1 ′ ÷ W1 (1)
R2 ′ ÷ R2 = W2 ′ ÷ W2 (2)
The bottom surface of the UT sensor 1 has a curved surface so that the above relationship is established, and a shoe 7 that propagates ultrasonic waves between the inspection object 2 and the ultrasonic element 5 is provided. That is, the upper surface (mounting surface of the ultrasonic element 5) of the shoe 7 has a curved surface shape that satisfies the relationship of the above formulas (1) and (2), and the bottom surface is a flat surface that comes into contact with the surface of the inspection object 2. . Although not particularly shown, the UT sensor 1 is covered with a protective case.

  FIG. 9 is a schematic configuration diagram of ultrasonic flaw detection according to the present embodiment, and FIG. 10 is a functional block diagram thereof.

  The ultrasonic flaw detection apparatus shown in FIGS. 9 and 10 includes a personal computer (personal computer) 9, a UT apparatus 8, and a UT sensor 1.

  The personal computer 9 includes a CPU 21 that executes various arithmetic processes, a RAM 23 that temporarily stores calculation results and values during the calculation, a ROM 24 that stores programs and necessary constants, an HDD 22, an I / O port 25, a keyboard 26, a DVD, A recording medium 27 such as a Blu-ray disc, a monitor 28 and the like are provided.

  The UT device 8 includes an I / O port 25, a D / A converter 30, and an A / D converter 29.

FIG. 11 is a schematic configuration diagram illustrating a configuration example of the UT sensor 1.
The UT sensor 1 shown in FIG. 11 includes a plurality of piezoelectric elements 18 facing an inspection object, electrodes 10 and 10 provided on the bottom surface (opposite surface to the inspection object) and the upper surface of each piezoelectric element 18, and an electrode 10 , 10 and a signal line 15 for applying a voltage to the upper electrode 10, and a damper 11 provided on the upper electrode 10 for absorbing the energy of the transmitted ultrasonic wave. The piezoelectric element 18 is a piezoelectric element such as PZT, LiNbO ₃ , PVDF, the electrodes 10 and 10 are highly conductive metals such as Au, Ag, Cu, the signal line 15 is a copper wire, and the damper 11 is What mixed metals, such as Hf, W, and Ta, with resin can be used, respectively. A protective case (not shown) for covering these can be used by molding one or more materials of resin and metal. Moreover, since the damper 11 reduces the after-vibration at the time of ultrasonic transmission, S / N can be improved by providing this. The ultrasonic elements 5 having such a configuration are two-dimensionally arranged in n rows and m columns so as to satisfy the above expressions (1) and (2).

  FIG. 12 is a flowchart showing the procedure of an ultrasonic flaw detection method using the ultrasonic flaw detection apparatus of the present embodiment.

Step 101: Input of inspection information Input one or more of the expected shape and position of the defect 3, the shape and position of the UT sensor 1, and the shape of the inspection object 2 from the keyboard 26 and the recording medium 27 shown in FIG. Input from the device. Further, when data regarding the position, size, and occurrence frequency of the defect 3 of the inspection object 2 is accumulated, the data is used as a defect occurrence example database, and one or more input devices of the keyboard 26 and the recording medium 27 are used. Enter from. These pieces of information are transmitted to the CPU 21 via the I / O port 25 and stored in at least one storage device such as the HDD 22, the RAM 23, and the ROM 24. Information such as the shape is transmitted to the CPU 21 via the I / O port 25 and stored in at least one storage device such as a hard disk drive (HDD) 22, a random access memory (RAM) 23, and a read only memory (ROM) 24. Is done.

Step 102: Defect position / shape analysis Based on the shape information of the inspection object 2, the CPU 21 executes structural intensity calculation of the inspection object 2, and analyzes and predicts the shape and position of the defect 3 based on the calculation result. May be. The analysis result is stored in at least one storage device of the HDD 22, RAM 23, and ROM 24. As described above, the CPU 21 functions as a stress distribution analysis unit, and sets a location having a high stress distribution specified by the analysis as a target location of the UT. In addition, the analysis result of the stress distribution is stored as a database in a storage device (at least one of the previous HDD 22, RAM 23, and ROM 24) that stores the analysis result.

Step 103: Calculation of ultrasonic transmission start time difference Based on the shape of the inspection object 2, the shape and position of the defect 3, the shape and position of the UT sensor 1, the defect shape and position information analyzed in step 102, the CPU 21 causes the UT sensor 1 to An ultrasonic transmission start time difference between the constituent ultrasonic elements 5 is calculated.

  Here, FIG. 13 is an explanatory diagram of an ultrasonic transmission start time calculation method for each ultrasonic element. The distance Lij between the ultrasonic element in the i-th row and j-th column of the ultrasonic element 5 arranged two-dimensionally in the UT sensor 1 when the defect position is set as the ultrasonic convergence point is obtained, and the k-th and l-th super The ultrasonic transmission start time difference dtkl of the acoustic wave elements is calculated by the CPU 21 according to the following equation (3), and is stored in one or more storage devices among the HDD 22, RAM 23, and ROM 24.

dtkl = (Max (Lij) −Lkl) ÷ V (3)
here,
Max (Lij): Maximum value of the distance between the ultrasonic convergence point and the ultrasonic element
Lkl: distance between the ultrasonic convergence point and the i-th and j-th ultrasonic elements V: ultrasonic velocity.

  By shifting the transmission start time of each ultrasonic element 5 according to the difference between the ultrasonic transmission start times calculated by the above equation (3), the ultrasonic waves simultaneously reach the convergence point from each ultrasonic element 5 and the ultrasonic wave at the convergence point. The strength is increased and the signal strength is improved.

Step 104: UT sensor installation The UT sensor 1 is installed on the inspection object 2.

Step 105: UT execution Depending on the difference in ultrasonic transmission start time, the ultrasonic element 5 is passed through the I / O 25 port of the personal computer 9, the I / O port 25 of the UT device 8, and the D / A converter 30 in FIG. A voltage is applied and ultrasonic waves are transmitted.

  The transmitted ultrasonic wave enters the inspection object 2 and is reflected by the defect. The reflected wave from the defect is detected as a voltage by the ultrasonic element 5 and transmitted to the CPU 21 via the A / D converter 29, the I / O port 25 of the UT device 8, and the I / O port 25 of the personal computer 9, and the HDD 22, The data is stored in at least one storage device of the RAM 23 and the ROM 24. Further, the UT result is displayed on the monitor 28 via the I / O port 25.

  In the ultrasonic flaw detection system according to the present embodiment, as described above, the bottom surface shape of the UT sensor 1 is similar to the shape of the defect 3 so that the traveling axis of the incident wave of each ultrasonic element 5 is the curved surface of the defect 3. Since the polarization angle of the incident wave approaches 90 ° when the SH wave is transmitted from each ultrasonic element 5 toward the defect 3, the SH wave component in the reflected wave from the defect 3 is Since it increases, the sensitivity of the UT is improved.

<Second Embodiment>
The present embodiment is an ultrasonic flaw detection apparatus having a UT sensor in which a plurality of ultrasonic elements that transmit SH waves to defects are arranged, and is an example that is particularly effective when the angle of the generated defect cannot be determined. is there. Schematically, it is an example in which a plurality of ultrasonic elements are arranged so that ultrasonic waves are incident from a plurality of directions with respect to a place assumed as a defect occurrence position, and the ultrasonic flaw detection apparatus in the present embodiment is a UT. The configuration is the same as that of the first embodiment except that the arrangement of the ultrasonic elements of the sensor is different and a shoe is unnecessary.

  In the first embodiment, the case where the defect 3 having a three-dimensional curved surface shape is assumed is illustrated. However, even if the defect 3 does not have a curved surface shape, the ultrasonic elements are arranged in a grid pattern as shown in FIG. When the UT is performed with the conventional UT sensor fixed to the inspection object, the polarization angle changes depending on the angle of the defect to be generated. Therefore, the polarization angle of the ultrasonic wave incident on the defect from the ultrasonic element is set to 90 °. Or, it was not possible to make the angle close to that. Also in this case, the SV wave component is increased and the reflection efficiency is lowered.

  Therefore, in the present embodiment, as shown in FIG. 15, when a plurality of defects 3 that occur at different angles at the assumed defect occurrence position are assumed and viewed from the direction of the intersection of each defect 3, each defect 3 An ultrasonic element 5 of n rows and m columns is arranged in a curved surface shape or polygonal shape region connecting points on the normal line, and this is used as the UT sensor 1. Therefore, m ultrasonic elements 5 in each row are arranged on a plane orthogonal to the target defect 3. In this example, the case where the ultrasonic elements 5 of n rows and m columns are two-dimensionally arranged concentrically is illustrated.

  As a result, the polarization angle from the ultrasonic element 5 in any row becomes 90 ° or an angle close thereto depending on the angle of the defect 3, so that the ultrasonic wave whose polarization angle becomes 90 ° or the closest angle thereto. By selecting the element 5 based on the intensity of the reflected wave and performing UT using the detection result of the selected ultrasonic element 5, the SH wave component in the reflected wave from the defect 3 increases, so the sensitivity of the UT is increased. improves.

<Third Embodiment>
The present embodiment is an ultrasonic flaw detection apparatus having a UT sensor in which a plurality of ultrasonic elements that transmit SH waves to defects are arranged. In particular, it is assumed that a plurality of defects having different angles are generated at a flaw detection location. This is an example effective in the case where the ultrasonic element is arranged on a plane orthogonal to each assumed defect. In the second embodiment, the traveling axes of the ultrasonic elements of the ultrasonic elements in each row are aligned with respect to a single defect whose angle cannot be predicted, and ultrasonic waves are incident on the assumed defect occurrence positions from a plurality of different directions. In contrast, in the present embodiment, the ultrasonic elements in each row transmit ultrasonic waves to each of a plurality of assumed defects with respect to a place where a plurality of defects having different angles are highly likely to occur. It is different in point. The ultrasonic flaw detection apparatus according to the present embodiment is the same as that of the first embodiment except that the arrangement of the ultrasonic elements of the UT sensor is different.

  As an example of the flaw detection location where a plurality of defects having different angles occur, for example, around a pin hole of a blade fork of a turbine rotor blade. The structure of the blade fork of the turbine blade will be described with reference to FIG.

  The turbine shown in FIG. 16 includes a disk 41, turbine blades 42, and pins 43. In FIG. 16, only a part of the disk 41 is shown in a partial cross section.

  The disk 41 is a disk-like member attached to the outer peripheral side of the rotating shaft, and has disk forks 46 arranged in the outer peripheral portion in the rotating shaft direction of the rotor (hereinafter referred to as the rotor shaft direction). The disk fork 46 is provided with a plurality of pin holes 45 penetrating in the axial direction.

  The turbine rotor blade 42 includes a blade implantation portion 47, a blade attachment portion 48, and a blade portion (profile portion) 49. The blade implantation portion 47 is a portion located on the disk 41 side in a posture (blade attachment posture) in which the turbine rotor blade 42 is attached to the disk 41, and has a plurality of blade forks 50. The blade fork 50 is provided with a plurality of pin holes 51 penetrating in the axial direction. The forks 50 are members that protrude inward in the rotor radial direction in a posture in which the turbine rotor blades 42 are attached to the disks 41, and a plurality of forks 50 are arranged in the axial direction. These forks 50 are arranged at intervals corresponding to the intervals of the disk forks 46 so as to engage with the outer peripheral portion of the disk 41. The blade attachment portion 48 is a portion having a predetermined thickness in the rotor radial direction, and is formed integrally with the blade implantation portion 47 outside the blade implantation portion 47 in the rotor shape direction. A blade portion 49 of the turbine rotor blade 42 is attached to a blade attachment surface 53 on the outer side in the rotor radial direction of the blade attachment portion 48. Further, the blade attachment portion 48 has overhang portions 52 at both ends in the axial direction. The overhang portion 52 protrudes in the axial direction from both axial end surfaces of the blade implantation portion 47 in a posture in which the turbine rotor blade 42 is attached to the disk 41.

  The pin hole 45 of the disk fork 46 and the pin hole 51 of the blade fork 50 correspond to each other in the posture in which the turbine rotor blade 42 is attached to the disk 41, and the pin 43 is placed axially in the pin holes 45, 51. The turbine rotor blade 42 is fixed to the disk 41 by being inserted. The pin holes 45 and 51 are configured such that the diameters of the pin holes 45 and 51 coincide with each other in the posture in which the turbine rotor blade 42 is attached to the disk 41. Moreover, in order to disperse the stress applied to the pin holes 45 and 51 with the rotation of the turbine and improve the durability, a plurality of pin holes 45 and 51 are provided for each blade fork.

  However, in such a fork type turbine rotor, even if a plurality of pin holes 51 are provided in the blade fork 50, cracks (hereinafter referred to as defects) are generated around the pin holes 45 and 51 due to stress applied as the turbine rotates. ) May occur. Therefore, in order to confirm the reliability of the turbine rotor blade 42, the defect inspection technique of the blade fork 50 is important.

  As shown in FIG. 17, the defect detection around the pin hole 51 of the blade fork 50 is performed by installing the UT sensor 1 on the surface facing the axial direction of the overhanging portion 52 (hereinafter, referred to as a sensor installation surface). The ultrasonic wave is incident on the position where the defect 3 is generated (position where the possibility of occurrence is high) while the ultrasonic wave is reflected on the inner surface of the surface, and the reflected wave from the defect 3 is detected.

  The defect 3 of the pin hole 51 of the blade fork 50 is likely to occur in the range shown in FIG. 18 (the lower half side of the pin hole 51 (the disk 41 side)) and tends to occur so as to extend in the radial direction of the pin hole 51. Are known. The defect occurrence range is divided into n to assume a defect occurrence position on the outer periphery of the pin hole 51, and a perpendicular (normal line of the pin hole 51) is drawn from each defect occurrence position to assume a defect 3. Then, when viewed from the axial direction of the pin hole 51, normals of the respective defects 3 extending from the vicinity of the outer peripheral part of the pin hole 51 to the overhanging part 52 side are obtained, and these normals are used as the traveling axis of the incident wave of ultrasonic waves. . The ultrasonic elements 5 in each row are arranged in a posture capable of transmitting ultrasonic waves along these normals on the sensor installation surface, and this is used as the shape of the UT sensor 1. Therefore, in this example, each row of ultrasonic elements 5 is arranged on a plane orthogonal to each defect 3, and the traveling axis of the ultrasonic wave transmitted from each ultrasonic element 5 is along the orthogonal plane of the target defect 3. Further, in this example, the UT sensor 1 is arranged by two-dimensionally arranging the ultrasonic elements 5 in n rows and m columns in a polygonal arc-shaped or arc-shaped region formed by connecting points on each normal line on the sensor installation surface. Forming.

  Since the ultrasonic element 5 is arranged on the surface orthogonal to the defect 3, the polarization angle of the incident wave when the SH wave is transmitted from each ultrasonic element 5 toward the defect 3 in this embodiment is 90. It can be at or near an angle. Therefore, the SH wave component occupying the reflected wave from the defect 3 is increased, and the UT sensitivity is improved.

  As shown in FIG. 19, even if the incident vector of the ultrasonic wave deviates from the normal line, the reflection efficiency that can withstand the UT can be obtained as long as it is within an allowable range. For example, when the deviation angle is 5 °, a reflection efficiency of 50% as compared with the case where the deviation angle is 0 ° is obtained. As the deviation angle increases, the reflection efficiency decreases accordingly, but in a region where the deviation angle exceeds 25 °, the reflection efficiency converges to about 5% of the reflection angle when the deviation angle is 0 °. In other words, the reflection efficiency can be improved by reducing the shift angle in the range of 25 ° or less. Accordingly, the deviation angle is at least 25 °, and 0 (zero) or an angle close to 0 is preferable. The same can be said for the tolerance of this shift angle in other embodiments.

<Fourth embodiment>
The present embodiment is an ultrasonic flaw detection apparatus having a UT sensor in which a plurality of ultrasonic elements that transmit SH waves to defects is arranged, and in particular, when the position and angle of a generated defect can be specified. This is an effective example for further improving the sensitivity. The ultrasonic flaw detection apparatus according to the present embodiment is the same as that of the first embodiment except that the arrangement of the ultrasonic elements of the UT sensor is different.

  FIG. 20 is a configuration diagram of the UT sensor in the present embodiment.

  In FIG. 20, a normal is drawn from the defect 3 having the highest probability of occurrence in one pin hole 51 of the blade fork 50 onto the sensor installation surface of the overhanging portion 52, and the ultrasonic element 5 is placed in a direction perpendicular to the defect 3. A two-dimensional array (in this example, a lattice array) is arranged in rows and m columns. When all of these n × m ultrasonic elements 5 transmit ultrasonic waves toward the same defect 3, the polarization angles are slightly different for each row. Further, a normal is drawn from the defect 3 having the highest probability of occurrence in the pin hole 51 of the same blade fork 50 on the sensor installation surface of the overhanging portion 52, and the ultrasonic element 5 is placed in the direction orthogonal to the defect 3 by n 'rows m. 'Two-dimensional array (lattice array in this example) in a row. Even when all of these n ′ × m ′ ultrasonic elements 5 transmit ultrasonic waves toward the same defect 3, the polarization angles are slightly different for each row. In this example, two ultrasonic element groups of n rows and m columns and n ′ rows and m ′ columns are combined to form one UT sensor 1.

  In the pin hole 51 of the blade fork 50, the position of 45 ° on the lower half side (disk side) has the highest probability of occurrence of a defect, and the defect tends to extend in the radial direction of the pin hole 51. Therefore, in this example, the UT sensor 1 is formed in an L-shape that is bent by 90 °. However, when the position where the probability of occurrence of a defect is highest is different (when it is not a 45 ° position), or the highest probability. When not detecting flaws that occur but flaw detection at a position (not a 45 ° position) where it is desired to know the presence or absence of defects, the folding angle of the UT sensor 1 varies accordingly.

  According to the present embodiment, it is possible to further improve the UT sensitivity when the position and angle of the generated defect can be specified. In addition, since the UT sensor 1 according to the present embodiment can simultaneously execute UTs of a plurality of different pin holes 51, an effect of speeding up the UT can also be obtained.

<Fifth embodiment>
The present embodiment is an ultrasonic flaw detection apparatus having a UT sensor in which a plurality of ultrasonic elements that transmit SH waves to defects are arranged as in the other embodiments, and in particular, the UT sensor is a surface to be inspected. This is an example in which an SH wave is transmitted to a defect by adjusting the position and angle without being fixed to. In general, a moving mechanism having a rotary actuator and a translational actuator of at least two axes and enabling the plane movement and rotation of the UT sensor, and a defect occurrence position based on intensity calculation of the inspection object 2 or a defect occurrence example database. Predicting the shape, the calculation unit for deriving the point where the predicted normal of the defect and the surface to be inspected intersect as an ultrasonic transmission point, and instructing the moving mechanism to move the UT sensor to the ultrasonic transmission point, And a command unit that rotates the UT sensor so that the ultrasonic wave transmitted toward the calculated defect position becomes an SH wave, and instructs the UT sensor to transmit the SH wave. A specific configuration will be briefly described below.

  FIG. 21 is a schematic configuration diagram of the ultrasonic flaw detector according to the present embodiment. As shown in FIG. 21, the ultrasonic flaw detector according to the present embodiment includes a personal computer 9, a UT device 8, a UT sensor 1, a UT sensor moving mechanism 12, an actuator 13, and an actuator driver 14.

  FIG. 22 is a configuration diagram of the UT sensor 1, in which ultrasonic elements 5 similar to those of the other embodiments are arranged one-dimensionally on a straight line, and other than the arrangement of the ultrasonic elements 5, the other embodiments are arranged. It is the same as the UT sensor.

  FIG. 23 is a configuration diagram of the UT sensor moving mechanism 12. As shown in FIG. 23, the UT sensor moving mechanism 12 includes, for example, a driving mechanism such as a motor or a piezo element, and includes at least a biaxial translational actuator 13a that moves the UT sensor 1 in a plane, and a rotary actuator 13b that rotates the UT sensor 1. A storage container 16 for storing an actuator formed by molding metal, resin, or the like, and a suction cup 17 serving as a fixing means for fixing the storage container 16 to the inspection object 2 are provided. The position and angle of the UT sensor 1 are controlled by the UT sensor moving mechanism 12.

  The UT method using this ultrasonic flaw detection system will be described with reference to the functional block diagram of FIG. 24 and the ultrasonic flaw detection step of FIG.

Step 201: Input of Inspection Object Shape and Defect Shape / Position The shape and position of defect 3 expected from one or more input devices of the keyboard 26 and the recording medium 27 shown in FIG. The position and the shape of the inspection object 2 are input. When data relating to defect occurrence cases of the inspection object 2 is accumulated, the cases are used as a database relating to the position / size / occurrence frequency of the defect, and one or more input devices of the keyboard 26 and the recording medium 27 are used. Enter from. The shape information is transmitted to the CPU 21 via the I / O port 25 and stored in one or more storage devices among the HDD 22, the RAM 23, and the ROM 24. As described above, the CPU 21 functions as a stress distribution analysis unit, and sets a location having a high stress distribution specified by the analysis as a target location of the UT. In addition, the analysis result of the stress distribution is stored as a database in a storage device (at least one of the previous HDD 22, RAM 23, and ROM 24) that stores the analysis result.

Step 202: Analysis of defect position The shape and position of the defect 3 may be analyzed and predicted by calculating the intensity of the inspection object 2 by the CPU 21 based on the shape information of the inspection object.

Step 203: Analysis of Ultrasonic Propagation Path The CPU 21 analyzes the ultrasonic propagation path when ultrasonic waves are transmitted in the normal direction from the position of the defect 3 to obtain the emission point on the surface of the inspection object 2, and the emission point Is stored in one or more storage devices among the HDD 22, RAM 23, and ROM 24 as sensor installation positions. FIG. 26 is an explanatory diagram of an analysis method of the ultrasonic propagation path. It is assumed that a straight line is drawn from the defect 3 in the normal direction of the defect 3 and is reflected by the mirror surface when it hits the surface in the inspection object 2. Find the point to reach the sensor installation surface. When an ultrasonic wave is transmitted from this reaching point, it is incident on the defect 3, and this point is set as an ultrasonic wave transmission point. Therefore, in the case of the functional block diagram of FIG. 24, the CPU 21 corresponds to the arithmetic unit described above.

Step 204: Analysis of difference in ultrasonic transmission start time FIG. 27 is an explanatory diagram of a method of calculating the ultrasonic transmission start time of each ultrasonic element. In FIG. 27, the distance Li between each ultrasonic element 5 constituting the UT sensor 1 and the ultrasonic convergence point is obtained, and the ultrasonic transmission start time difference from the ultrasonic element that starts transmitting the kth ultrasonic element 5 first. dtk is calculated by the CPU 21 as follows,
dtk = (Max (Li) −Lk) ÷ V (4)
The data is stored in one or more storage devices among the HDD 22, the RAM 23, and the ROM 24.
here,
Li: Distance between the ultrasonic convergence point and the i-th ultrasonic element Lk: Distance between the ultrasonic convergence point and the k-th ultrasonic element Max (Li): Ultrasonic convergence point and the i-th ultrasonic wave Maximum value of distance from element V: Represents ultrasonic velocity. By obtaining the ultrasonic transmission start time difference according to the above equation (4), the ultrasonic waves simultaneously reach the convergence point 36 from each ultrasonic element 5, the ultrasonic intensity at the convergence point 36 is increased, and the signal intensity is improved.

Step 205: Installation of Sensor The UT sensor moving mechanism 12 to which the UT sensor 1 is fixed is fixed on the inspection object 2 with the suction cup 17. Further, the initial installation position of the UT sensor 1 is input from the keyboard 26, transmitted to the CPU 21 via the I / O port 25, and stored in one or more storage devices among the HDD 22, RAM 23, and ROM 24.

Step 206: Sensor Movement Based on the ultrasonic transmission point obtained in step 203 and the position of the UT sensor 1 recorded in step 205, the CPU 21 shown in FIG. 24 sends a UT to the actuator driver 14 via the I / O port 25. A signal of the amount of movement of the sensor 1 is sent, electric power is supplied from the actuator driver 14 to the actuator 13, the UT sensor 1 is moved to the installation position, and the angle is adjusted. Therefore, in the case of the functional block diagram of FIG. 24, the CPU 21 also corresponds to the command unit described above.

Step 207: Execution of UT Based on the ultrasonic transmission start time difference obtained previously, the I / O port 25 of the personal computer 9, the I / O port 25 of the UT device 8, and the D / A converter 30 shown in FIG. A voltage is applied to the ultrasonic element 5 via this to transmit ultrasonic waves.

  The transmitted ultrasonic wave is reflected by the defect 3 when there is the defect 3. The reflected ultrasonic wave is detected as a voltage by the ultrasonic element 5 and transmitted to the CPU 21 via the A / D converter 29, the I / O port 25 of the UT device 8, and the I / O port 25 of the personal computer 9, and the HDD 22, The data is stored in one or more storage devices of the RAM 23 and the ROM 24. Further, the UT result is displayed on the monitor 28 via the I / O port 25.

  As described above, since the SH wave can be applied to the defect with high accuracy also in the present embodiment, the same effects as those of the above-described embodiments can be obtained. Further, since the position and angle of the UT sensor 1 can be adjusted according to the predicted position and shape of the defect, the number of ultrasonic elements 5 can be reduced as compared with the above-described embodiments in which the UT sensor 1 is fixed. Can be suppressed. As a result, the UT device 8 can be simplified and the UT device 8 can be made inexpensive. Further, since the position and orientation of the UT sensor 1 can be flexibly controlled according to the analysis result of the position and angle of the defect, the reliability is also improved.

It is a conceptual diagram of ultrasonic flaw detection (UT). It is a conceptual diagram of ultrasonic propagation mode. It is a figure showing the incident angle dependence of reflection efficiency. It is a conceptual diagram of incident mode change. This is the polarization angle dependency of the incident mode ratio. It is a block diagram of the conventional SH wave sensor. It is a block diagram of the conventional SH wave sensor. It is a conceptual diagram of the SH wave sensor which concerns on 1st Embodiment. 1 is a configuration diagram of an ultrasonic flaw detector according to a first embodiment. FIG. It is a functional block diagram of the ultrasonic flaw detector according to the first embodiment. It is the schematic of the SH wave sensor which concerns on 1st Embodiment. It is a flowchart showing the ultrasonic flaw detection step in 1st Embodiment. It is explanatory drawing for calculation of the ultrasonic transmission time difference in 1st Embodiment. It is a block diagram of the conventional SH wave sensor. It is a conceptual diagram of the SH wave sensor which concerns on 2nd Embodiment. It is the schematic of an example of the test object of 2nd Embodiment. It is a conceptual diagram of the UT method in 2nd Embodiment. It is a block diagram of the UT sensor in 3rd Embodiment. It is a figure showing the dependence with respect to the deviation angle from the defect normal of incident angle of SH wave reflection efficiency. It is a block diagram of the UT sensor in 4th Embodiment. It is a schematic block diagram of the ultrasonic flaw detector which concerns on 5th Embodiment. It is the schematic of the UT sensor in 5th Embodiment. It is a block diagram of the sensor moving mechanism in 5th Embodiment. It is a functional block diagram of an ultrasonic flaw detector according to a fifth embodiment. It is a flowchart showing the ultrasonic flaw detection step in 5th Embodiment. It is a conceptual diagram of the ultrasonic wave propagation path in 5th Embodiment. It is explanatory drawing for calculation of the ultrasonic transmission start time difference in 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 UT sensor 2 Inspection object 3 Defect 4 Reflective surface 5 Ultrasonic element 6 Protective case 7 Shoe 8 UT device 9 Personal computer 10 Electrode 11 Damper 12 UT sensor moving mechanism 13 Actuator 13a Translation actuator 13b Rotation actuator 14 Actuator driver 15 Signal line 16 Storage Container 17 Fixing mechanism 18 Piezoelectric element 21 CPU
22 HDD
23 RAM
24 ROM
25 I / O port 27 Recording medium 28 Monitor 29 A / D converter 30 D / A converter 41 Disk 42 Turbine blade 43 Fork pin 46 Disk fork 45 Disk side pin hole 48 Blade attachment part 50 Blade fork 51 Pin hole 52 Overhang Part 53 Wing mounting surface

Claims (15)

An ultrasonic flaw detection apparatus having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to a defect are arranged,
The length and curvature of the assumed three-dimensional curved surface defect in the major axis direction are W1 and R1, respectively, the length and curvature of the defect in the minor axis direction are W2 and R2, respectively, and the length in the major axis direction of the ultrasonic flaw detection sensor. When the length and curvature are W1 ′ and R1 ′, and the length and curvature in the minor axis direction of the ultrasonic flaw detection sensor are W2 ′ and R2 ′, respectively, the bottom surface of the ultrasonic flaw detection sensor is
R1 ′ ÷ R1 = W1 ′ ÷ W1 (1)
R2 ′ ÷ R2 = W2 ′ ÷ W2 (2)
An ultrasonic flaw detector characterized by having a curved surface shape that satisfies the above relationship and providing a shoe for propagating ultrasonic waves between an inspection object and each ultrasonic element. An ultrasonic flaw detection apparatus having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to a defect are arranged,
An ultrasonic flaw detector characterized in that the plurality of ultrasonic elements are arranged so that ultrasonic waves are incident from a plurality of directions on a position assumed as a defect occurrence position.   The ultrasonic flaw detector according to claim 2, wherein the ultrasonic elements are arranged concentrically. An ultrasonic flaw detection apparatus having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to a defect are arranged,
An ultrasonic flaw detector in which the ultrasonic element is arranged on a surface orthogonal to each defect when the occurrence of a plurality of defects having different angles at the flaw detection location is assumed. An ultrasonic flaw detection apparatus having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to a defect are arranged,
A moving mechanism having a rotary actuator and a translational actuator of at least two axes, and capable of moving and rotating the ultrasonic flaw detection sensor;
A calculation unit that calculates the shape and position of an assumed defect by executing an intensity calculation based on the shape information of the inspection target, and derives a point where the calculated normal of the defect intersects the surface of the inspection target as an ultrasonic transmission point; ,
The ultrasonic flaw detection sensor is moved so that the ultrasonic wave transmitted toward the calculated defect position becomes a horizontally polarized transverse wave by instructing the moving mechanism to move the ultrasonic flaw detection sensor to the ultrasonic wave transmission point. An ultrasonic flaw detection apparatus comprising: a command unit that rotates and commands the ultrasonic flaw detection sensor to transmit a horizontally polarized transverse wave.   The ultrasonic flaw detector according to any one of claims 1 to 5, wherein an angle formed by a surface orthogonal to the defect and an ultrasonic traveling axis of the ultrasonic element is 25 ° or less. .   The ultrasonic flaw detector according to claim 1, comprising at least one of a stress distribution analysis device or a stress distribution analysis result database. An ultrasonic flaw detection method using an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to a defect are arranged,
The length and curvature of the assumed three-dimensional curved surface defect in the major axis direction are W1 and R1, respectively, the length and curvature of the defect in the minor axis direction are W2 and R2, respectively, and the length in the major axis direction of the ultrasonic flaw detection sensor. When the length and curvature are W1 ′ and R1 ′, and the length and curvature in the minor axis direction of the ultrasonic flaw detection sensor are W2 ′ and R2 ′, respectively, the bottom surface of the ultrasonic flaw detection sensor is
R1 ′ ÷ R1 = W1 ′ ÷ W1 (1)
R2 ′ ÷ R2 = W2 ′ ÷ W2 (2)
An ultrasonic flaw detection method characterized by providing a curved surface shape that satisfies the above relationship and providing a shoe for propagating ultrasonic waves between an inspection object and each ultrasonic element. An ultrasonic flaw detection method having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to a defect are arranged,
An ultrasonic flaw detection method, wherein the plurality of ultrasonic elements are arranged so that ultrasonic waves are incident from a plurality of directions on a position assumed as a defect occurrence position. An ultrasonic flaw detection method having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to a defect are arranged,
An ultrasonic flaw detection method characterized by arranging the ultrasonic element on a surface orthogonal to each defect when the occurrence of a plurality of defects having different angles at the flaw detection location is assumed. An ultrasonic flaw detection method having an ultrasonic flaw detection sensor in which a plurality of ultrasonic elements that transmit horizontally polarized transverse waves to a defect are arranged,
Intensity calculation is performed based on the shape information of the inspection object, the shape and position of the assumed defect are calculated, and the point where the calculated normal of the defect intersects the surface of the inspection object is derived as an ultrasonic transmission point.
An ultrasonic flaw detection sensor is moved to the ultrasonic wave transmission point, and the ultrasonic flaw detection sensor is rotated so that the ultrasonic wave transmitted toward the calculated defect position becomes a horizontally polarized wave, and the ultrasonic flaw detection is performed. An ultrasonic flaw detection method, wherein a horizontally polarized wave is transmitted to a position of the calculated defect by a sensor.   The ultrasonic flaw detection method according to any one of claims 8 to 11, wherein an angle formed by a surface orthogonal to the defect and an ultrasonic traveling axis of the ultrasonic element is 25 ° or less. .   The ultrasonic flaw detector according to any one of claims 8 to 12, wherein the stress distribution of the inspection object is analyzed based on the shape of the inspection object, and a portion having a high stress distribution identified by the analysis is subjected to ultrasonic flaw detection. Ultrasonic flaw detection method.   The ultrasonic flaw detection method according to claim 8, wherein ultrasonic flaw detection is performed on a portion having a high stress distribution on a database created based on a stress distribution analysis result.   The ultrasonic flaw detection method according to claim 8, wherein ultrasonic flaw detection is performed on a portion having a high defect occurrence frequency based on a defect occurrence example database.

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