JP2013156173A - Inspection method for turbine blade and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly inspect the sizes and the number of corrosion pits on the surface of a turbine blade.SOLUTION: An imaging head is placed (a) over a surface of inspection position of a turbine blade; the surface is irradiated (b) with parallel light beam from an oblique direction; scattered light generated by the irradiation is taken into an imaging element and imaged (c) as imaging light beam; an image of corrosion pits are extracted (d) by a computer from the image information acquired by the imaging; the sizes of the extracted corrosion pit images are measured (e) by the computer; the number of the extracted corrosion pit images which are larger than a prescribed allowable value is counted (f) by the computer; necessity of scanning of the imaging head is determined (g); the scanning of the imaging head to the next inspection position is performed if necessary (h); steps starting from the process of irradiation (b) are repeated; and when the scanning is not necessary, the scanning is stopped (i) and the inspection is completed.

Description

  The present invention relates to a method for inspecting the presence or absence of corrosion pits generated on the surface of a turbine blade and the degree of corrosion using an image of the surface of the turbine blade.

  Turbine blades attached to the rotors of gas turbines and steam turbines may have small holes called corrosion pits on the surface during use, cracks may develop from the holes, and the turbine blades may break.

  Therefore, it is necessary to periodically inspect the surface of the turbine blade to determine whether it needs to be repaired, replaced with a new turbine blade, or still usable. Since the corrosion pits do not know when they will develop into fatigue cracks, at the time of inspection, count the number of corrosion pits larger than the specified size, and if it exceeds the specified value, repair or replace with a new one. Measures such as are taken.

  A conventional turbine blade inspection method will be described with reference to FIGS. FIG. 19 shows the overall configuration of a conventional inspection system. In the conventional method, an inspector scans the surface of the turbine blade 1 by holding the imaging head 2 by hand, and another inspector confirms an image displayed on the monitor, and a corrosion pit having a size larger than a specified value is confirmed. The method of counting the number was taken.

  At this time, in order to obtain an image of the surface of the turbine blade 1, as shown in FIGS. 20 and 21, the surface of the turbine blade 1 is entirely surrounded by illumination 6 surrounding the imaging lens 5. The image was acquired in the light of

  Therefore, as shown in FIG. 22, when a wide area (low magnification) image is taken, a shallow heat-resistant coat is peeled off at the same time, and it is difficult to identify and determine the corrosion pit from the acquired image. It was. Therefore, as shown in FIG. 23, it was necessary to enlarge and image the corrosion pits at a high magnification of about 50 times, and to observe the corrosion pit image 40 on the monitor obtained as a result.

  In this case, the inspection field of view becomes narrow due to high-magnification imaging, and if the inspector scans the microscope head 2 too quickly, the corrosion pit image 40 quickly passes over the monitor and stares at the monitor. Another inspector who is present cannot determine the corrosion pit image 40.

  Therefore, the inspector had to move the microscope head slowly, and the inspection time was inevitably increased due to the narrow field of view and slow scanning. Furthermore, since this operation is performed for each turbine blade, it took a long time to inspect the turbine blade of a gas turbine, which has a large number of blades of several tens or more per stage.

  Further, there was an oversight potential because the corrosion pit image 40 was searched while checking with a monitor. Furthermore, since the allowable size of the corrosion pit image 40 is different depending on the position where the corrosion pit is generated in the turbine blade 1, there is a risk that the size of the corrosion pit image 40 is wrongly determined.

  In response to these problems, for example, Japanese Patent No. 4015929 discloses a method for repairing a turbine blade attached to a rotating body in a corrosive environment, and the average diameter of corrosion pits generated on the surface of the turbine blade. Before growing to 50 micrometers or more, the surface of the corrosion pit is subjected to an impact treatment with an ultrasonic vibration terminal to reduce the depth of the corrosion pit to 5 micrometers or less, and fatigue cracks are generated from the corrosion pit. A method is described for preventing events leading to turbine blade breakage due to rapid propagation growth.

  In Japanese Patent Application Publication No. 2007-17376, Japanese Patent Application Publication No. 2007-17376 discloses that a subject placed in an examination position in a dark room is irradiated with near ultraviolet rays for fluorescent flaw detection, and the subject is photographed through a long pass filter. Obtain a fluorescent still image, irradiate the subject with visible light from the same position at different times, capture the subject through a long-pass filter, obtain a visible still image, and then capture the fluorescent still image and the visible still image A method is described in which images are superimposed by image processing to create a superimposed image, and fine scratches are inspected from the area of the fluorescent portion of the superimposed image.

  In Japanese Patent No. 4618502, a fluorescent agent or fluorescent magnetic powder is infiltrated or adsorbed onto the surface of the inspection position to be inspected, and the inspection object is mounted on a swivel device and swiveled to place a plurality of units in the darkroom. The flaw detection technique is described in which the position and size of a high-luminance location in the image are calculated based on the information of the image acquired by the image pickup apparatus.

Japanese Patent No. 4015929 Patent Gazette Japanese Patent Application Publication No. 2007-17376 Japanese Patent No. 4618502 Patent Gazette

  However, the technique described in Patent Document 1 does not describe a method for extracting corrosion pits. In the technique described in Patent Document 2, two types of images must be acquired while using the fluorescence flaw detection method together, and a long time is required for the inspection. The same applies to Patent Document 3, and it takes a long time to acquire an image due to preparation of an inspection environment in a dark room and an application and fixing work of a fluorescent agent as a problem peculiar to fluorescence flaw detection. As a result, the inspection takes a long time. Is required.

  Accordingly, an object of the present invention is to quickly achieve inspection of a turbine blade having a process of extracting corrosion pits generated in the turbine blade with an image.

  The basic requirements of a turbine inspection apparatus for achieving the object of the present invention are: an illuminating device that illuminates the surface of a turbine blade with a parallel light beam obliquely when viewed from the surface, and scattered light generated on the surface by the illumination A computer having an image processing function for extracting a corrosion pit image from the image based on information of an image captured by the imaging device, and a size of the corrosion pit image extracted by the image processing function. The turbine blade inspection apparatus includes a computer having a measurement function for measuring.

  Similarly, the basic requirement of the turbine inspection method is to illuminate the surface of the turbine blade with a parallel beam obliquely when viewed from the surface, image the scattered light generated on the surface, and extract the corrosion pit image from the image information A computer having a function of extracting a corrosion pit image from information of the image acquired by the imaging, and a computer having a function of measuring the size of the corrosion pit image is used to determine the size of the extracted corrosion pit image. A turbine blade inspection method comprising a step of measuring and detecting the presence and size of the corrosion pit image.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to improve the test | inspection precision and test speed of a turbine blade which has the process of extracting the corrosion pit which arose in the turbine blade with the image.

It is a schematic longitudinal cross-sectional view of the imaging head used in the Example of this invention. FIG. 2 is a schematic plan view of a main part when the imaging head of FIG. 1 is viewed from below. It is a systematic diagram of the inspection system in the Example of this invention. 2 is an image of a subject surface acquired by the imaging head of FIG. 1. It is the conceptual diagram which showed the result of having extracted the corrosion pit image from the image of FIG. It is a conceptual diagram which shows the method of calculating | requiring the magnitude | size of a corrosion pit image by applying a circumscribed ellipse to the area | region of the corrosion pit image extracted in the Example of this invention. In the figure showing the result of fitting a circumscribed ellipse to the area of the corrosion pit image extracted in the embodiment of the present invention (left figure), the upper and lower two symbols on the right side of the figure are part of the figure for explanation. It is the figure which expanded and showed. It is the figure which showed the table | surface by which the corrosion pit image extracted in the Example of this invention is displayed on a display apparatus in order of a magnitude | size. It is a conceptual diagram which shows the method of calculating | requiring the magnitude | size of a corrosion pit by applying an inscribed circle to the area | region of the corrosion pit image extracted in the Example of this invention. It is a longitudinal cross-sectional view of the ball plunger part in the contact mechanism to the subject with which the imaging head of FIG. 1 is mounted. FIG. 11 is a plan layout view of the ball plunger portion of FIG. 10. FIG. 11 is an enlarged longitudinal sectional view of the ball plunger portion of FIG. 10. It is the longitudinal cross-sectional view which showed the contact condition to the subject curved surface of the ball plunger part of FIG. It is a figure explaining the pressing mechanism and scanning mechanism with respect to the test object of the imaging head by the Example of this invention. It is a figure which shows the detail of the grab screw mechanism of FIG. It is the perspective view which showed a mode that it inspects while scanning the turbine blade surface using the imaging head by the Example of this invention, its pressing mechanism, and a scanning mechanism. It is explanatory drawing which showed a mode that the surface of the multi-direction of the turbine blade by the Example of this invention was test | inspected. It is a figure which shows the test | inspection flow in the Example of this invention. It is explanatory drawing of the conventional test | inspection method. It is a schematic longitudinal cross-sectional view of the imaging head used with the conventional test | inspection method. FIG. 21 is a schematic plan layout view of the main part of the imaging head of FIG. 20. It is the figure which showed the wide area image of the subject surface acquired with the conventional illumination method. It is the figure which showed the picked-up image by the imaging head acquired with the conventional illumination method.

  In the embodiment of the present invention, the turbine blade is set as the inspection object 8, and the illumination device A that illuminates the surface of the turbine blade with the parallel light beam 7 at a predetermined angle obliquely and the scattered light generated by the illumination as the imaging light beam 9 An imaging device B that captures and captures an image from an elevation angle, an image processing function that processes an image obtained using the imaging device B and extracts a corrosion pit image 40 generated on the surface of the inspection object 8, and the extracted corrosion A computer 46 incorporating a function of measuring the size of the pit image 40 and a function of dividing the measured corrosion pit image 40 in a predetermined size order, and a result of dividing the corrosion pit image 40 in size order are displayed. A turbine blade inspection device including a display device 47 that performs the scanning, and a scanning mechanism that moves the illumination device A and the imaging device B along the surface of the inspection object 8 is shown.

  Then, by using the inspection device, as a turbine blade inspection method, the turbine blade is set as the inspection object 8, and the surface of the inspection object 8 is illuminated obliquely with parallel rays, and the scattered light generated by the illumination is Image capturing step for capturing and imaging as an imaging light beam, scanning step for moving the above-described illumination and imaging position for the inspection object 8, and image processing for extracting the corrosion pit image 40 from information of the image obtained by the imaging The step of extracting the corrosion pit image 40 generated on the surface of the inspection object 8 using the computer 46 incorporating the function and the computer 46 incorporating the function of measuring the size of the extracted corrosion pit image 40 are used. Step of measuring the size of the extracted corrosion pit image 40 and a predetermined size based on the measured size. The number of the extracted corrosion pit images 40 exceeding the predetermined size allowable value based on the function of classifying the size of the extracted corrosion pit images 40 in order of the sizes or the measured size is counted. The step of performing the classification or the counting using the computer 46 incorporating the function and the step of displaying the classification or the counting result on the display device 47 are executed.

  Thus, in the embodiment of the present invention, the corrosion pit image is extracted from at least one image of the surface to be inspected, the size of the corrosion pit image is obtained from the extraction result, and the corrosion pit is enlarged based on the size. Since the computer counts the number of corroded pit images with a size exceeding the permissible value that is classified or determined in advance, it eliminates the step for the inspector to judge by looking at the monitor, and there is no human error. High-precision inspection work can be performed by a small number of people, and inspection can be performed using captured image information by wide-area inspection without adopting a step of observing a captured image in which a corrosion pit is enlarged at a high magnification. Therefore, the inspection speed can be improved.

  Each embodiment of the present invention will be specifically described below with reference to FIGS. 1 and 2 show the structure of an imaging head 10 according to an embodiment of the present invention.

  As shown in FIGS. 1 and 2, the imaging head 10 includes an illumination device A, an imaging device B, and a casing that covers them. The illuminating device A includes bar illuminations 11a to 11d using light emitting diodes or the like as light sources, and collimating lenses 12a to 12d for adjusting light emitted from the bar illuminations 11a to 11d to parallel light rays 7a to 7d.

  With such a configuration, the light emitted from the bar lights 11a to 11d is converted into parallel rays 7a to 7d by the collimating lenses 12a to 12d, respectively, and then oblique to the imaging region that is the inspection region of the inspection object 8. Irradiated from the direction. The elevation angle when illuminating from an angle is approximately 5 to 30 degrees. In this way, the imaging area is illuminated. At this time, illumination is performed so as to cover the entire imaging region.

  In FIG. 1 and FIG. 2, the lighting device A is arranged in four directions in 90 degree increments and illuminates from the four directions, but the orientation is not limited to four directions in 90 degree increments, It is sufficient that at least one lighting device A is provided. Moreover, you may increase the number of directions and the number of illuminating devices as needed.

  The imaging device B includes a plurality of imaging lenses 5 and an imaging element 4 such as a CCD or CMOS that allows the light collected by the imaging lens 5 to enter. With such a configuration, the scattered light generated from the imaging region of the inspection object 8 by illumination by the illumination device A is collected by the imaging lens 5 as an imaging light beam 9 for use in imaging, and the CCD or CMOS is used. An image is formed on the image sensor 4. At this time, the direction in which the scattered light generated by illuminating the surface to be inspected obliquely is set to the normal direction of the surface to be inspected.

  As shown in FIG. 3, a lighting controller 43 is connected to the switch driving unit that blinks each of the bar lights 11 a to 11 d as a control unit that controls the blinking, and a synchronization device 45 is connected to the lighting controller 43. The light emission timing of each of the bar lights 11a to 11d is determined by a command sent from the synchronization device 45 to the illumination controller 43, and the blinking of each of the bar lights 11a to 11d is controlled at the light emission timing. .

  Thus, in the illuminating device A that illuminates the turbine blade surface obliquely at a predetermined elevation angle, the light sources by the respective bar lights 11a to 11d are arranged in a plurality of directions, and the light emission timing can be individually controlled. The function of imaging the turbine blade surface with the imaging device B in synchronization can be exhibited.

  On the other hand, a camera controller 44 is connected to a signal transmission / reception unit of the image sensor 4 as a control unit that controls the timing of capturing a signal for constructing a captured image from the image sensor 4, and in response to a command from the synchronization device 45 to the camera controller 44. The timing of signal capture is controlled. Further, the timing of sending the signal to the computer 46 is controlled by a command from the synchronization device 45 to the camera controller 44.

  With such a synchronization control system, the imaging timing of the imaging device 4 is synchronized with the illumination (lighting) timing of the bar lights 11a to 11d, and is synchronously set so that the imaging region can be imaged by the imaging device 4 under illumination. The

  By such a synchronous setting, a signal of the imaging result generated by the imaging light beam 9 when the imaging light beam 9 forms an image is transferred to the computer 46 and is signal-processed by the computer 46, and the contents after the processing are stored in the storage device 48.

  FIG. 4 shows an example of an image obtained by processing by the computer 46 based on the imaging light beam incident on the image sensor 4. Such an acquired image is displayed on the display device 47 as desired.

  Compared to the image obtained by the conventional all-around illumination shown in FIG. 22, the image obtained by the illumination by the parallel rays according to the embodiment of the present invention is brightly manifested only by the corrosion pit image as shown in FIG. . The acquired image data is subjected to image processing such as binarization processing by the computer 46, and the dark-colored portion in FIG. 5 is extracted as the region of the corrosion pit image 40. Image processing such as binarization processing is performed, and the reconstructed image after the image processing is displayed on the display device 47 as a gray scale image as shown in FIG. 5 as desired. In this way, the corrosion pit image 40 is extracted more easily from the raw image as shown in FIG.

  Next, in the computer 46, when the extracted areas are continuous by the labeling process, the computer 46 performs a process of regarding the areas as the areas of one corrosion pit image 40, and assigns an individual identification number to each of the areas. For example, a number as a number is given, and the position coordinates on the image of the corrosion pit image 40 or the surface to be inspected corresponding to the number are preferably stored. Next, a process of fitting a circumscribed ellipse 39 to each extracted area of the corrosion pit image 40, that is, a fitting process as shown in FIG.

  At this time, the size of the corrosion pit image 40 is defined by the major axis “a” and the minor axis “b” of the circumscribed ellipse 39 that is circumscribed and fitted to the corrosion pit image 40. That is, if a / b is 2 or more, the size of the corrosion pit image is axb, and if a / b is less than 2, the size of the corrosion pit image 40 is the value of the diameter a. The size of the image 40 is defined.

  The result of fitting the circumscribed ellipse 39 to the extraction result of the corrosion pit image 40 described with reference to FIG. 5 can be displayed as an image 38 in FIG. In FIG. 7, an image 38 after the fitting process and a partially enlarged image of the image 38 are displayed adjacent to the image 38. In FIG. 7, reference numerals 40a, 40b, 40c, and 40d denote a plurality of corrosion pit images 40 having different sizes. The image of FIG. 7 can be displayed on the display device 47 if necessary.

  In this way, the major axis a and the minor axis b of the circumscribed ellipse 39 circumscribing the corrosion pit image 40 are obtained through the fitting process of applying an ellipse circumscribing the extracted corrosion pit image 40, and the major axis a and minor axis are obtained. A sizing process is performed in which b is calculated by the computer 46 in accordance with the size definition described above.

  The sizing processing results obtained by the computer 46 are stored in the storage device 48 and are displayed on the display device 47 in the form of a table after sorting by the computer 46 in order of size as shown in FIG.

  As shown in FIG. 8, the classifications in order of size are Nos. 27, 30, and 13, which are numbers corresponding to the corrosion pit images 40 having a size of a / b of 2.00 or more that should be emphasized. Displayed on the upper side of the table, and a / b of 2.00 or more is indicated as higher in order to determine the progress of the corrosion pits, and the inspector's attention is urged.

  The numbers corresponding to the corrosion pit images 40 having a / b of less than 2.00 are No. 28, 23, and 40, which are displayed on the lower side of the table of FIG. indicate.

  The computer 46 counts the number of corrosion pit images 40 having an a / b value equal to or greater than the allowable value 2.00, displays the count result on the display device 47, and stores the count result in the storage device 48. The computer 46 calculates the inspection result according to the counting result and displays the result on the display device 47.

  For example, when the count result exceeds a predetermined number, the computer 46 causes the display device 47 to display an inspection result indicating that the turbine blade needs to be replaced. At the time of counting, the computer 46 counts the number of a / b values that are not less than 2.00 and displays the result on the display device 47. The table of FIG. The inspector may visually count the number of objects having an a / b value of 2.00 or more. When counting by the inspector, the sizing result of the corrosion pit image 40 is visualized as a table with classification according to the size defined in advance by the computer 46. It is difficult to raise, and inspection accuracy and inspection speed can be improved.

  It should be noted that the definition of the size of the corrosion pit image 40 is not limited to the above, and can be arbitrarily determined. Further, in this embodiment, the geometry employed in the fitting process executed in the sizing process is used. Although the shape is a circumscribed ellipse, as shown in FIG. 9, there is also a method of applying an inscribed circle 41 to the area of each corrosion pit image 40, and sizing by applying an optimal geometric shape as necessary. Also good.

  When the turbine blade that is the inspection object 8 is inspected over a wide range using the imaging head 10 of FIG. 1, the imaging head 10 is inspected while performing scanning that moves the imaging head 10 along the surface of the turbine blade and changes the inspection position. It is desirable.

  Next, an inspection system suitable for scanning the imaging head 10 and inspecting the entire surface of the turbine blade will be described with reference to FIGS. 10 to 17. In this inspection system, contents suitable for scanning of the imaging head 10 are added to the contents described with reference to FIGS. Therefore, in the following, the additional contents will be described, and the description of other contents will be omitted including illustration.

  Although not shown, the imaging head 10 shown in FIG. 10 includes an imaging device B and an illumination device A similar to those described with reference to FIG. As shown in FIGS. 10 and 11, ball plungers 13 a to 13 d are formed at the four corners of the bottom part of the frame constituting the outline of the imaging head 10, and a part of the ball 15 protrudes downward in the drawing of the imaging head 10. It is attached by arrangement.

  The ball plungers 13a to 13d are, as shown in FIG. 12, a ball holder 17 that houses the ball 15 so that the ball 15 can rotate and a part of the ball 15 protrudes downward in the figure, and the ball holder 17 can move up and down. An open bottom cylindrical structure built in the ball, a ball holder stopper 19 that is fixed inside the cylindrical structure and protrudes above the ball holder 17 to limit the movable range of the ball 15, and a cylinder. And a spring 18 provided as a suspension in the vertical direction in the figure between the cylindrical structure and the ball holder 17. The cylindrical structure is fixed to a frame that forms the outline of the imaging head 10.

  When such an imaging head 10 is pressed so that the ball 15 contacts the concave curved surface of the turbine blade 1, the turbine blade 1 and the ball plungers 13 a to 13 d are in contact with each other by the ball 15. The spring 18 acts between the ball holder 17 and the ball 15 so that the ball 15 is always pushed downward in the drawing.

  Therefore, when the imaging head 10 is pressed against the curved surface of the blade of the turbine blade 1, the imaging head 10 is held in a state substantially along the curved surface of the blade of the turbine blade 1, as shown in FIG. If the imaging head 10 is moved on the curved surface of the blade of the turbine blade 1 in this state, scanning is performed in which the ball 15 rolls on the curved surface and the imaging head 10 moves smoothly to displace the imaging region, that is, the inspection position. This is possible with the curved surface of the turbine blade 1.

  At that time, since the imaging direction is generally directed to the normal direction of the surface of the turbine blade 1, an inspection method that does not change even when imaging from the normal direction is scanned can be employed. The depth of field 20 of the imaging device is set to be larger than R of the curved surface of the wing or the suspension movable range of the ball 15 of the ball plungers 13a to 13d, and the turbine is obtained by scanning the imaging head 10 along the curved surface of the wing. It is preferable for inspecting a wide range of the wing 1 while changing its position.

  In the case of manual scanning in which the inspector holds the imaging head 10 by hand, the inspector adjusts the pressing degree and posture of the imaging head 10 as shown in FIGS. 14 to 17 described below. If a simple scanning mechanism is used, an inspection in which scanning is also automated is possible.

  That is, the imaging head of FIG. 1 or the imaging head of FIG. 10 may be used, but as shown in FIG. 14, the imaging head 10 is scanned using an electric linear guide device. The imaging head 10 is attached to a grab screw 30 of a linear guide device, and a shaft 29 portion of the grab screw 30 is connected to a linear bearing 28 fixed to the linear guide 26 so as to be movable in the axial direction (length direction of the shaft 29). The shaft plate 24 is fixed to the end surface of the shaft 29, the shaft plate 24 and the linear guide 26 are connected by a spring 25, and the shaft plate 24 is always pulled toward the linear guide 26 by a spring force. . At this time, the pressing force against the turbine blade 1 to be inspected always acts on the imaging head 10 by the force of the spring 25.

  Since the connecting portion of the imaging head 10 to the grab screw 30 has a degree of freedom of rotation like a universal joint made of a ball, it tilts as shown in FIG. 14 and changes its posture in a direction generally along the surface of the turbine blade 1. be able to. Therefore, when the imaging head 10 is pressed toward the surface by the force of the spring 25, the posture of the imaging head 10 automatically changes in accordance with the curved surface shape or the inclined shape of the pressed surface, and the curved surface is almost aligned with the curved surface. Will be along.

  Since the linear guide 26 is attached to the shaft 27 so as to be electrically movable in the lateral direction along the shaft 27, the linear guide 26 can be automatically scanned and moved manually by moving the linear guide 26 electrically. The imaging head 10 can be automatically scanned in a state where the imaging head 10 is always pressed against the turbine blades 1 without any problem.

  In order to proceed with further automation by adding an additional configuration to the configuration of FIG. 14, the configuration is as follows. That is, as shown in FIG. 16, the shafts 27 and 29 in the configuration of FIG. 14 are arranged horizontally, and both ends of the shaft 27 in the linear guide device 33 of another linear guide device 33 in which the guide direction is directed in the vertical direction. The guide 31 is supported. The linear guide device 33 has a configuration of a scanning mechanism that allows the linear guide 31 to move electrically in the vertical direction.

  According to such a scanning mechanism, the imaging head 10 can be operated in the same direction by moving the linear guide 31 of the linear guide device 33 in the vertical direction 104 by electric drive. Further, by moving the linear guide 26 in the horizontal direction 103 by electric drive, the imaging head 10 can be scanned in the same direction.

  Further, since the spring 25 functions as a suspension of the shaft 29 in the horizontal direction 102 in the axial direction, the imaging head 10 is pressed against the inspection surface of the turbine blade 1 with a spring force that is not excessive or insufficient. Even if the curved surface shape of the inspection surface at the pressed position changes, the imaging head 10 follows the change and rotates in the rotational directions 100 and 101 shown in FIG. The wing 1 can move so as to substantially follow the curved surface shape of the surface.

  Thus, if the imaging head 10 is electrically moved three-dimensionally to perform scanning, it is possible to quickly inspect a wide area of the surface of the turbine blade 1 as compared with manual scanning.

  In addition, an inspection device having a linear guide device 33 as a scanning mechanism is installed in the imaging head 10 for each of the front and back surfaces of the turbine blade 1, the leading edge and the trading edge, and the curved surfaces have different curvatures. It is possible to inspect the entire surface of the turbine blade 1 by scanning and inspecting the imaging head 10 with the scanning mechanism.

  The overall flow of inspection in each of the embodiments described above is as shown in FIG. That is, first, the imaging head 10 in which the illumination device and the imaging device are integrated is placed on the surface of the turbine blade 1 to be inspected so as to be within the depth of field of the imaging device and placed at the inspection position (a ).

  Next, the surface of the turbine blade 1 is illuminated with a parallel light beam obliquely by an illumination device (b). The elevation angle when the surface of the turbine blade 1 is illuminated obliquely is approximately 5 degrees to 30 degrees. Next, the scattered light generated by illuminating the surface of the turbine blade 1 at the inspection portion at an oblique angle is imaged by an imaging device (c). The imaging direction is generally the normal direction of the inspection surface of the turbine blade 1.

  Next, the corrosion pit image 40 is extracted by a computer from the captured image acquired under such imaging conditions (d). Next, sizing of the extracted corrosion pit image 40 is executed by a computer (e). Then, the computer recognizes the sizing result of the corrosion pit image 40. Next, from the result of the sizing, the number of corrosion pit images 40 having a size exceeding a predetermined allowable value is counted by a computer (f). At least one result or a plurality of results of the counting result or the determination based on the counting result or the sizing result in the step (e) or a plurality of results are displayed and visualized on the display device 47 connected to the computer. Also, each step (d), (e), (f), or any of them not yet implemented is excluded from each successive step in FIG. 19, and it is determined that the scanning is finished in step (g). Or after the inspection end step (i), the imaging data at each scanning position is taken over, and each of the steps (d), (e), (f), or any of them is not yet implemented. The result may be continuously executed to obtain a result.

  Next, whether or not the imaging head 10 needs to be moved to a new inspection position is determined from the inspection range or the like, and whether or not the scanning of the imaging head 10 is finished is determined by a computer (g). When the scanning is not finished, the imaging head 10 is moved manually or by a scanning mechanism such as the linear guide device 33 to a new inspection position (h). Thereafter, the steps after step (b) of illuminating the surface of the turbine blade 1 at an oblique angle at a new inspection position are repeated. When it is determined that the scanning is finished, the scanning is finished (i), and the inspection is finished.

  Note that steps (d), (e), and (f) in FIG. 19 may be executed separately from other steps. For example, the data captured in step (c) is transported to a place where analysis equipment is well-prepared by recording or transporting to a recording medium. May be executed.

  The present invention has applicability to inspection techniques for inspecting the degree of corrosion of turbine blades.

DESCRIPTION OF SYMBOLS 1 Turbine blade 4 Image pick-up element 5 Imaging lens 7, 7a-7d Parallel light 8 Inspection object 9 Imaging light 10 Imaging head 11a-11d Bar illumination 12a-12d Collimate lens 13a-13d Ball plunger 15, 16 Ball 17 Ball holder 18 , 25 Spring 19 Ball holder stopper 20 Depth of field 24 Shaft plate 26, 31 Linear guide 27, 29 Shaft 28 Linear bearing 30 Grab screw 39 circumscribed ellipse 40, 40a, 40b, 40c, 40d Corrosion pit image 41 Inscribed circle 43 Illumination controller 44 Camera controller 45 Synchronization device 46 Computer 47 Display device 48 Storage device A Illumination device B Imaging device

Claims (16)

  The surface of the turbine blade is seen from the surface and illuminated with parallel rays obliquely to image the scattered light generated on the surface, and acquired by the imaging with a computer having a function of extracting the corrosion pit image from the image information The size of the extracted corrosion pit image is measured by a computer having a function of extracting the corrosion pit image from the image information and measuring the size of the corrosion pit image, and the presence and size of the corrosion pit image is detected. And a method for inspecting turbine blades.   The turbine blade inspection method according to claim 1, wherein the direction of illumination is 5 to 30 degrees in elevation.   The turbine blade inspection method according to claim 1, wherein the imaging direction is a normal direction of the surface.   The size of the extracted corrosion pit image is measured by a computer having a function of fitting a geometric shape to the area of the corrosion pit image and determining the size based on the size of the fitted geometric shape. The turbine blade inspection method according to claim 1, wherein the turbine blade inspection method is executed.   Of the extracted corrosion pit images, the number of corrosion pit images having a predetermined size or more is obtained by a computer having a function of counting the number of those having a predetermined size or more. The turbine blade inspection method according to any one of claims 1 to 4.   The turbine blade inspection method according to claim 4, wherein a circumscribed ellipse is applied as the geometric shape.   The ratio corresponding to the extracted corrosion pit image is obtained by a computer having a function of calculating a ratio of a major axis and a minor axis of a circumscribed ellipse fitted to the extracted corrosion pit image. Item 7. The turbine blade inspection method according to Item 6.   A ratio of a major axis and a minor axis of a circumscribed ellipse fitted to the extracted corrosion pit image is equal to or greater than the predetermined ratio by a computer having a function of counting the number of the corrosion pit images having a value greater than or equal to a predetermined value. The turbine blade inspection method according to claim 6 or 7, wherein the number of the corrosion pit images having a ratio is obtained and recognized. An illumination device that illuminates the surface of the turbine blade with a parallel beam obliquely when viewed from the surface;
An imaging device for imaging scattered light generated on the surface by the illumination;
A computer having an image processing function for extracting a corrosion pit image from the image based on information of the image captured by the imaging device;
A computer having a measurement function for measuring the size of the corrosion pit image extracted by the image processing function;
Turbine blade inspection device having   The turbine blade inspection apparatus according to claim 9, wherein the illumination direction is set to an angle of elevation of 5 degrees to 30 degrees.   The turbine blade inspection apparatus according to claim 9 or 10, wherein the imaging direction is set to a normal direction of the surface.   A computer having a measurement function for fitting a geometric shape to a region of the corrosion pit image and measuring the size of the extracted corrosion pit image based on the size of the fitted geometric shape; The turbine blade inspection method according to claim 9, wherein the turbine blade is inspected.   13. The computer according to claim 9, further comprising a computer having a counting function that counts the number of the corrosion pit images extracted in a predetermined size or more. Turbine blade inspection equipment.   The turbine blade inspection device according to claim 12 or 13, further comprising a computer having a function of fitting a circumscribed ellipse as the geometric shape to the extracted corrosion pit image.   The turbine blade inspection apparatus according to claim 14, further comprising a computer having a function of calculating a ratio between a major axis and a minor axis of a circumscribed ellipse fitted to the extracted corrosion pit image.   A computer having a function of counting the number of corrosion pit images having a ratio of a major axis and a minor axis of a circumscribed ellipse fitted to the extracted corrosion pit images having a value equal to or larger than a predetermined value is provided. The turbine blade inspection method according to claim 14 or 15.