Inspection device and inspection method for bolt fastening condition

Abstract

The present invention provides an inspection device that can diagnose the fastening condition of bolts and reduce overload on structures to which bolts are fastened. [Solution] The bolt fastening inspection device 1 according to the present invention comprises an imaging unit 15 that photographs a bolt fastening portion 24 of a structure 3 fastened with a plurality of bolts 22 and acquires an image containing the plurality of bolts 22, and a processing unit 16 capable of controlling the operation of the structure 3. The imaging unit 15 photographs the bolt fastening portion 24 before a load is applied to acquire a first image of the bolt fastening portion 24 before deformation, and photographs the bolt fastening portion 24 after a load is applied to acquire a second image of the bolt fastening portion 24 after deformation. The processing unit 16 performs image analysis processing on the first and second images to calculate the displacement amount and the distribution of the displacement direction of the plurality of bolts 22. The processing unit 16 controls the operation of the structure 3 so that the displacement amount of each of the plurality of bolts 22 is smaller than a preset allowable value.

Description

Technical Field

[0001] The present invention relates to an inspection device and an inspection method for diagnosing the fastening state of bolts of a structure.

Background Art

[0002] In the bolt fastening part of a structure, problems such as loosening and breakage occur due to repeated loads or excessive loads acting over a long period of time. In order to avoid such problems, it is necessary to diagnose the bolt fastening state and reduce the overload on the structure.

[0003] As a method for diagnosing the bolt fastening state, there is a method of attaching a sensor such as a strain gauge to the bolt and measuring and recording the strain. When such a sensor is attached to the surface of a structure, it is necessary to devise the routing of the sensor wiring and further prevent disconnection of the wiring and failure of the sensor body to avoid the risk of loss of the sensor function. Furthermore, it is necessary to identify the correspondence between individual bolts and sensors and speed up the data processing process.

[0004] Therefore, the development of a technique for estimating the axial force of a bolt is being promoted by using the difference in the deformation amount of the bolt head before and after tightening and the relationship between the bolt axial force and the deformation amount of the bolt head obtained in advance by means such as finite element method (FEM) analysis. Here, the difference in the deformation amount of the bolt head before and after tightening can be obtained by the digital image correlation (DIC) method. In the DIC method, a time history image of the displacement of a speckle pattern (hereinafter also referred to as "pattern") provided on the surface of the structure is taken. The pattern can be applied to the surface of the structure with paint, seal, stamp, etc., and it deforms following the deformation of the structure receiving an external force. By photographing the deformation of the pattern with a digital camera and processing the photographed image by the DIC method, the distribution of the displacement amount of the pattern can be obtained, and the deformation amount of the bolt head can be determined.

[0005] Patent Document 1 describes an example of an inspection device using such a method. The inspection system described in Patent Document 1 includes an imaging device for infrared measurement of a structure and a processing unit that performs image analysis based on the digital image correlation method on the infrared image obtained by the imaging device. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-067558 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The inspection system described in Patent Document 1 applies the DIC method to infrared images showing temperature changes to inspect the amount and direction of displacement on the surface of a structure caused by deformation. Such an inspection system can measure information about local displacement (such as the amount and direction of displacement) that occurs in areas where a pattern has been applied due to external force. However, it is not easy to diagnose, for example, the fastening state of multiple bolts in the entire bolted section, or the load applied to the structure to which the bolts are fastened, from the local displacement information obtained by measurement.

[0008] With conventional technology, in order to diagnose the fastening status of multiple bolts and reduce overload on the structure, it is necessary to increase the number of measurement points, that is, to widen the area to which patterns are applied, and furthermore, it is necessary to increase the amount of photographic equipment used for measurement, which increases the number of work processes and labor costs.

[0009] The object of the present invention is to provide an inspection device and inspection method that can diagnose the fastening condition of bolts and reduce overload on structures to which bolts are fastened. [Means for solving the problem]

[0010] The bolt fastening inspection device according to the present invention comprises an imaging unit that photographs a bolt fastening portion of a structure fastened with multiple bolts and acquires an image containing the multiple bolts, a processing unit capable of controlling the operation of the structure, and a display unit connected to the processing unit. The imaging unit photographs the bolt fastening portion before a load is applied to acquire a first image of the bolt fastening portion before deformation, and photographs the bolt fastening portion after a load is applied to acquire a second image of the bolt fastening portion after deformation. The processing unit performs image analysis processing on the first and second images to calculate the displacement amount and the distribution of the displacement direction of the multiple bolts. The display unit displays the distribution. The processing unit controls the operation of the structure so that the displacement amount of each of the multiple bolts is smaller than a preset allowable value.

[0011] The bolt fastening inspection method according to the present invention comprises: a first image acquisition step in which an imaging unit photographs a bolt fastening portion of a structure, which is fastened with a plurality of bolts, before a load is applied, and acquires a first image of the bolt fastening portion before deformation, which includes the plurality of bolts; a second image acquisition step in which the imaging unit photographs the bolt fastening portion, which is fastened with a load, after a load is applied, and acquires a second image of the bolt fastening portion after deformation, which includes the plurality of bolts; a distribution calculation step in which a processing unit performs image analysis processing on the first image and the second image to calculate the distribution of the displacement amount and direction of displacement of the plurality of bolts; a display step in which a display unit displays the distribution; and a control step in which the processing unit controls the operation of the structure so that the displacement amount of each of the plurality of bolts is smaller than a preset allowable value. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an inspection device and inspection method that can diagnose the fastening condition of bolts and reduce overload on structures to which bolts are fastened. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing an example of a bolt fastening inspection device and a structure equipped with a bolt fastening portion to be inspected by the inspection device, according to an embodiment of the present invention. [Figure 2] Figure 1 shows the axial cross-section A of the tower, including the tower connection section. [Figure 3] This flowchart shows the processing procedure for the bolt fastening condition inspection method according to an embodiment of the present invention. [Figure 4A] This diagram schematically shows the random pattern applied to the surface of an object to which the DIC method is applied, and is an example of the random pattern before deformation of the object to be measured. [Figure 4B] Figure 4A shows an example of the random pattern after deformation of the object being measured, in the random pattern shown in Figure 4A. [Figure 5] This diagram schematically shows an example of a bolted fastening section in wind power generation equipment. [Figure 6] Figure 5 schematically illustrates an example of a bolted fastening section being deformed under wind load. [Figure 7A] This diagram schematically shows another example of a bolted fastening section in wind power generation equipment. [Figure 7B] This diagram schematically shows another example of a bolted fastening section in wind power generation equipment. [Figure 8] This diagram schematically shows another example of a bolted fastening section in wind power generation equipment. [Figure 9] Figure 8 shows a perspective view of an example of a bolt head in a bolted connection, enclosed by the dashed line B. [Figure 10A] This figure shows an example where the speckle pattern applied to the top surface of the bolt head is a random pattern (spotted pattern). [Figure 10B] This figure shows an example where the speckle pattern applied to the top surface of the bolt head is a two-dimensional code. [Figure 10C] This figure shows an example where the speckle pattern applied to the top surface of a bolt head is a string of characters. [Figure 10D]This is a diagram showing an example in which the speckle pattern applied to the top surface of the bolt head is a pattern consisting of a solid circle and an annular ring. [Figure 11] This is a diagram schematically showing an example of a bolt fastening part to which a speckle pattern is applied to the fastened surface.

Embodiments for Carrying Out the Invention

[0014] The inspection apparatus and inspection method for bolt fastening states according to the present invention photograph a bolt fastening part of a structure fastened with a plurality of bolts, obtain displacements of the plurality of bolts, diagnose the fastening state of the bolts, and can reduce an overload on the structure. For this reason, in the present invention, not only the bolt fastening part but also the soundness of the structure can be maintained.

[0015] Hereinafter, an inspection apparatus and inspection method for bolt fastening states according to an embodiment of the present invention will be described. In the embodiments described below, as an example, an example in which the structure to which bolts are fastened is a wind power generation facility will be described. However, in the present invention, the structure to which bolts are fastened is not limited to power generation facilities such as wind power generation facilities, and can be any structure that can be operated and whose operation can be controlled. Further, in the present embodiment, the digital image correlation method (DIC method) is used as the image analysis process for obtaining the displacement of the bolt, and an example in which the speckle pattern used in the DIC method is a random pattern will be mainly described.

[0016] In the drawings referred to in this specification, the same or corresponding components are denoted by the same reference numerals, and repeated descriptions of these components may be omitted.

Examples

[0017] FIG. 1 is a schematic diagram showing an example of an inspection apparatus 1 for bolt fastening states according to an embodiment of the present invention and a structure including a bolt fastening part inspected by the inspection apparatus 1. As described above, the structure including the bolt fastening part inspected by the inspection apparatus 1 according to the present embodiment is a power generation facility, specifically, a wind power generation facility 3.

[0018] The wind power generation equipment 3 comprises a rotor 40, a rotating main shaft 6, a nacelle 7, and a tower 8. The rotor 40 comprises blades 4 and a rotor hub 5. The nacelle 7 and tower 8 are shown in cross-sectional view in Figure 1.

[0019] The blades 4 are attached to the rotating spindle 6 via the rotor hub 5. The rotating spindle 6 is connected to the power generator 10 via a speed increaser 9 in the nacelle 7. The blades 4 generate electricity by receiving wind load 11, which causes the rotating spindle 6 to rotate in the spindle rotation direction 12a, and then driving the power generator 10 via the speed increaser 9.

[0020] The nacelle 7 rotates in a swirling rotation direction 12b according to the wind direction and is connected to the tower 8 via a yaw gear 13. The swirling rotation direction 12b is the direction around the axis of the tower 8. The rotation in the swirling rotation direction 12b is called yaw rotation.

[0021] Tower 8 is a cylindrical structure and is installed on the foundation 14. In the case of onshore wind power generation equipment 3, the foundation 14 is constructed on the ground. In the case of offshore wind power generation equipment 3, the foundation 14 consists of monopiles, tripods (3 piles), jackets (4 piles), and gravity-type structures.

[0022] Tower 8 is equipped with a tower connection section 21. The tower connection section 21 is the point where the portion of Tower 8 on the nacelle 7 side and the portion on the foundation section 14 side are connected to each other. Figure 1 shows an axial cross-section A of Tower 8 including the tower connection section 21.

[0023] The wind power generation equipment 3 includes a wind direction control unit 19 and an output control unit 20. The wind direction control unit 19 controls the rotation of the nacelle 7 and adjusts the wind direction relative to the nacelle 7. The output control unit 20 controls the power output of the power generation device 10.

[0024] The inspection apparatus 1 according to this embodiment comprises an imaging unit 15, a processing unit 16, and a display unit 18. The imaging unit 15 can be configured as, for example, a digital camera and captures images. The processing unit 16 comprises a storage device and an arithmetic unit and is connected to the imaging unit 15 and the display unit 18. The storage device stores the images captured by the imaging unit 15. The arithmetic unit performs image analysis processing on the images captured by the imaging unit 15 using the DIC method. The display unit 18 has a screen and displays images stored in the storage device and the results of the image analysis processing by the arithmetic unit on the screen.

[0025] The processing unit 16 is connected to the wind direction control unit 19 and the output control unit 20 of the wind power generation equipment 3, and is configured to send and receive signals for wind direction control and output control, thereby enabling control of the operation of the wind power generation equipment 3.

[0026] In this embodiment, the imaging unit 15 is installed on the floor of the tower 8. The imaging unit 15 photographs the tower connection section 21 in a direction that looks upward from the base section 14 toward the nacelle 7.

[0027] Figure 2 shows the axial cross-section A of the tower 8, including the tower connection section 21, as shown in Figure 1.

[0028] At the tower connection section 21, the tower flange connection section 81 on the nacelle 7 side and the tower flange connection section 82 on the foundation section 14 side are fastened to each other with multiple bolts 22 and nuts 23. The multiple bolts 22 are arranged along the circumferential direction of the tower 8.

[0029] In a structure (wind power generation equipment 3 in this embodiment), a portion fastened with multiple bolts 22 is called a bolted fastening portion 24. In this embodiment, the portion where multiple bolts 22 fasten the tower flange connection portion 81 on the nacelle 7 side and the tower flange connection portion 82 on the foundation portion 14 side to each other is the bolted fastening portion 24, and the tower connection portion 21 is included in the bolted fastening portion 24. Washers, collars, etc. may also be included in the bolted fastening portion 24.

[0030] In this embodiment, the imaging unit 15 photographs the tower flange connection portion 82 in the bolt fastening portion 24. The imaging unit 15 is installed on the floor surface of the tower 8 and photographs the tower flange connection portion 82 from a distance, looking up. Therefore, in this embodiment, one imaging unit 15 photographs the entire bolt fastening portion 24, which includes multiple bolts 22, and photographs multiple bolts 22 simultaneously. By photographing the entire bolt fastening portion 24, the imaging unit 15 obtains an image containing multiple bolts 22. The processing unit 16 performs image analysis processing on the image obtained by the imaging unit 15 using the DIC method to determine the displacement amount and direction of displacement of the multiple bolts 22.

[0031] In the following, the distribution of displacement amounts and displacement directions of multiple bolts 22 in the bolt fastening section 24 will also be referred to as displacement distribution information. The fastening state of the bolts 22 refers to the displacement amount and displacement direction of the bolts 22, that is, the state of the bolts 22 as shown by the displacement distribution information.

[0032] Next, an example of a method for inspecting the bolt fastening state according to this embodiment will be described. However, the inspection method according to this embodiment is not limited to this example. The inspection method according to this embodiment can be performed by the inspection device 1 according to this embodiment.

[0033] Figure 3 is a flowchart showing the processing procedure for the bolt fastening condition inspection method according to this embodiment. The inspection method according to this embodiment includes a diagnostic step 26 for measuring and diagnosing the fastening condition of the bolts 22, and a control step 27 for reducing the overload on the wind power generation equipment 3, which is the structure to which the bolts 22 are fastened. The diagnostic step 26 comprises steps S6 to S8. The control step 27 comprises steps S9 to S11.

[0034] In S1, the imaging unit 15 photographs the entire bolt fastening portion 24 before the load is applied, and obtains an overall image (first image) of the bolt fastening portion 24 before it is deformed by the load. That is, the imaging unit 15 simultaneously photographs multiple bolts 22 in the bolt fastening portion 24 before deformation. For example, the imaging unit 15 photographs the entire bolt fastening portion 24 before the wind power generation equipment 3 starts operation, when no wind load 11 is acting, or when a small wind load 11 is acting that can be considered as not acting. The overall image of the bolt fastening portion 24 before deformation (first image) becomes the reference image when the processing unit 16 performs image analysis processing using the DIC method. The storage device of the processing unit 16 stores the image taken by the imaging unit 15.

[0035] In S2, wind power generation facility 3 begins operation.

[0036] In S3, the rotor 40 and tower 8 are subjected to wind. A wind load of 11 is applied to the rotor 40 and tower 8 as they receive the wind.

[0037] In S4, tower 8 deforms due to the wind load 11 applied to both rotor 40 and tower 8.

[0038] In S5, the tower connection part 21 deforms as the tower 8 deforms. When the tower connection part 21 deforms, the bolt fastening part 24 also deforms.

[0039] In S6, the imaging unit 15 photographs the entire bolt fastening portion 24 after the load has been applied, and obtains an overall image (second image) of the bolt fastening portion 24 after deformation due to the applied load. That is, the imaging unit 15 simultaneously photographs multiple bolts 22 in the deformed bolt fastening portion 24. For example, the imaging unit 15 photographs an overall image of the bolt fastening portion 24 after the wind load 11 has been applied after the wind power generation equipment 3 has started operation. The storage device of the processing unit 16 stores the image taken by the imaging unit 15.

[0040] In S7, the processing unit 16 performs image analysis processing using the DIC method on the images captured by the imaging unit 15 in S1 and S6, namely the overall image of the bolt fastening part 24 before deformation (first image) and the overall image of the bolt fastening part 24 after deformation (second image).

[0041] In S8, the calculation unit of the processing unit 16 calculates and acquires displacement distribution information (distribution of the amount of displacement and direction of displacement of the bolts 22) for multiple bolts 22 in the bolt fastening section 24 from the results of the image analysis processing. It is preferable for the calculation unit to acquire displacement distribution information for all bolts 22 in the bolt fastening section 24. The display unit 18 displays the distribution of the amount of displacement and direction of displacement of the bolts 22 in the bolt fastening section 24.

[0042] In S9, the calculation unit of the processing unit 16 determines whether the displacement of all of the bolts 22 from which displacement distribution information has been acquired is smaller than a preset allowable value. This allowable value can be arbitrarily determined, for example, by determining the allowable deformation amount of the tower connection part 21 using finite element analysis, and then determining the allowable displacement amount of the bolts 22 in the bolt fastening part 24 from the determined deformation amount.

[0043] For all bolts 22 from which displacement distribution information has been obtained, if the displacement is less than the allowable value, the process in S12 is executed. If there are any bolts 22 from which displacement distribution information has been obtained that have a displacement greater than or equal to the allowable value, the process in S10 is executed.

[0044] In S12, wind turbine 3 continues its current operation. As wind turbine 3 continues to operate, rotor 40 and tower 8 receive wind (S3).

[0045] In S10, the calculation unit of the processing unit 16 performs wind direction control and output control to reduce the wind load 11 acting on the wind power generation equipment 3, based on the displacement distribution information of multiple bolts 22 in the bolt fastening section 24 acquired in the diagnostic process 26.

[0046] Specifically, the processing unit 16 controls the operation of the wind power generation equipment 3 so that the wind load 11 applied to the rotor 40 and tower 8 decreases and the displacement of each of the bolts 22 falls below the allowable value. For example, the processing unit 16 controls at least one of the wind direction relative to the nacelle 7 and the power output of the power generator 10 to reduce the displacement of the bolts 22. The processing unit 16 transmits signals for wind direction control and power output control to the wind direction control unit 19 and the power output control unit 20 of the wind power generation equipment 3, respectively.

[0047] In S11, the processing unit 16 calculates the number of times the imaging unit 15 has taken images of the bolt fastening section 24 since the start of operation of the wind power generation equipment 3, and determines whether this number of images is less than a predetermined value. This predetermined value can be set arbitrarily.

[0048] If the number of images taken is less than the specified value, the process in S6 is executed, and the diagnostic process 26 and the control process 27 are performed again. If the number of images taken is greater than the specified value, the process in S13 is executed.

[0049] In S13, the wind power generation equipment 3 is shut down. The operation of the wind power generation equipment 3 is shut down because, even after repeating the diagnostic process 26 and the control process 27 to control the operation of the wind power generation equipment 3, the displacement of all bolts 22 does not fall below the allowable value.

[0050] In this embodiment, the fastening state of the multiple bolts 22 can be diagnosed as described above, and the wind load 11 acting on the wind power generation equipment 3 can be reduced, thereby reducing the overload on the wind power generation equipment 3.

[0051] In this embodiment, an example was described in which wind direction control and output control are performed to reduce the wind load 11 acting on the wind power generation equipment 3. However, the method for reducing this wind load 11 is not limited to controlling wind direction and power output, and other methods may be used.

[0052] The display unit 18 can display images captured by the imaging unit 15 and information about the processing performed by the processing unit 16. For example, the display unit 18 can display the results of image analysis processing (e.g., the distribution of the displacement amount and direction of the bolt 22), the judgment results in S9 and S11, and information related to operation control (e.g., the changed wind direction and power output).

[0053] In this embodiment, the processing unit 16 performs image analysis processing using the DIC method on images of the bolt fastening portion 24 before and after deformation, which are captured by the imaging unit 15. In the DIC method image analysis processing, the processing unit 16 measures the displacement distribution information of multiple bolts 22 in the bolt fastening portion 24 based on the brightness distribution on the surface of the tower flange connection portion 82, which is the fastened surface of the bolts 22. A brightness distribution is generated on the surface of the tower flange connection portion 82 (the fastened surface of the bolts 22) by the multiple bolts 22 and the fastened surfaces of these bolts 22.

[0054] The determination of the displacement amount and direction of the bolt 22 based on the DIC method will be explained with reference to Figures 4A and 4B.

[0055] Figure 4A schematically shows a random pattern 28 applied to the surface of an object to be measured using the DIC method, and is a diagram showing an example of the random pattern 28a before deformation of the object to be measured.

[0056] The random pattern 28 is applied, for example, by placing multiple black spots on a white background, and is also called a spotted pattern. The shape and position of the spots, as well as the colors of the background and spots, can be arbitrarily determined, provided that the contrast between the background and the spots is strong.

[0057] In random pattern 28a, a small image region (subset region) R is set centered on an arbitrary point Q, and the luminance distribution within the subset region R is determined. In this way, the luminance distribution within the subset region R before deformation of the object being measured is obtained.

[0058] Figure 4B shows an example of the random pattern 28b after deformation of the object being measured, in the random pattern 28 shown in Figure 4A.

[0059] In the random pattern 28b of the object under test after deformation, a region S with a luminance distribution that has the best correlation with the luminance distribution within the subset region R of the object under test before deformation is searched for and found. The position of the center point U of this region S is taken as the position of point Q that was displaced by the deformation of the object under test. That is, it is assumed that point Q was displaced to point U due to the deformation of the object under test. In this way, the amount of displacement and the direction of displacement of point Q can be determined simultaneously.

[0060] In this embodiment, the object to be measured is defined as the bolt fastening portion 24, and points Q and U are defined as the positions of the bolt 22. This allows the displacement and direction of the bolt 22 to be determined based on the DIC method.

[0061] Figure 5 is a schematic diagram showing an example of a bolted fastening section 24 of the wind power generation equipment 3. Figure 5 shows an example of the bolted fastening section 24 before deformation. The bolted fastening section 24 is annular in shape and comprises a plurality of bolts 22 and a fastening surface 30 for the plurality of bolts 22.

[0062] In this embodiment, the fastened surface 30 is the surface of the tower flange connection portion 82, and a plurality of bolts 22 are fastened to it. The plurality of bolts 22 are arranged at approximately equal intervals along the circumferential direction of the fastened surface 30.

[0063] In the diagnostic process 26, the fastened surface 30 is considered as the base material and the bolts 22 as spots in the bolted fastening portion 24, and a subset region R is set, assuming that a random pattern 28 (spot pattern) is applied to the bolted fastening portion 24. Then, the processing unit 16 performs image analysis processing on the images of the bolted fastening portion 24 before and after deformation using the DIC method.

[0064] Figure 6 schematically shows an example of the bolted fastening portion 24 shown in Figure 5 being deformed by a wind load 11. In other words, Figure 6 shows an example of the bolted fastening portion 24 after deformation.

[0065] Figure 6 shows the shape 83 of the fastened surface 30 (the surface of the tower flange connection portion 82) before deformation with a dashed line, and the shape 84 of the fastened surface 30 after deformation with a solid line. The bolt 22 is displaced in accordance with the deformation of the fastened surface 30. Figure 6 shows an example where the bolt 22 is displaced to position 32.

[0066] Figure 6 also shows an example of the results of image analysis processing performed by the processing unit 16 on the image of the bolt fastening part 24 before deformation (Figure 5) and the image of the bolt fastening part 24 after deformation (Figure 6) using the DIC method. As an example of this result, Figure 6 shows a vector 33 indicating the amount of displacement and the direction of displacement when the bolt 22 is displaced to position 32.

[0067] In this embodiment, an example was described in which image analysis processing was performed using the DIC method on one image of the bolt fastening portion 24 before deformation and one image of it after deformation. When performing image analysis processing using the DIC method, it is preferable to use two or more images of the deformed portion. Furthermore, when performing image analysis processing, it is also preferable to synchronize the time history of physical quantities measured by other means with the time history of image capture. These physical quantities include, for example, the amount of deformation of the shape of the tower flange connection portion 82 measured by a laser displacement meter, wind direction and wind speed data measured by an anemometer, and strain of the tower flange connection portion 82 and tower 8 measured by a strain gauge.

[0068] In this embodiment, in the bolt fastening portion 24, the fastened surface 30 is considered as the base for a random pattern 28, and the multiple bolts 22 arranged on the fastened surface 30 are considered as spots, thereby giving the bolt fastening portion 24 a random pattern 28 (spotted pattern). Then, the deformation of the wind power generation equipment 3 when subjected to an external force such as a wind load 11 (for example, the shape 84 of the fastened surface 30 after deformation, and vectors 33 indicating the displacement amount and direction of the bolts 22) can be obtained by image analysis processing in the diagnostic step 26 and displayed on the display unit 18. The obtained deformation of the wind power generation equipment 3 (for example, the displacement amount and direction of the bolts 22) can then be used in the control step 27 for wind direction control and output control, thereby reducing the wind load 11 acting on the wind power generation equipment 3.

[0069] In this embodiment, the fastening condition of the multiple bolts 22 can be diagnosed as described above, thereby reducing the overload on the wind power generation equipment 3. Therefore, in this embodiment, not only the multiple bolts 22 and bolt fastening parts 24, but also the overall integrity of the wind power generation equipment 3 can be maintained.

[0070] Figure 7A schematically shows another example of a bolted fastening section 34 of the wind power generation equipment 3. This bolted fastening section 34 comprises a plurality of bolts 35 and a fastening surface 36 for the plurality of bolts 35.

[0071] The bolt 35 and the fastened surface 36 are colored in similar colors, for example, for rust prevention. For example, a bolt 35 painted in a roughly gray color is fastened to a fastened surface 36 that is also painted in a roughly gray color. In such a bolted fastening section 34, even if image analysis processing is performed using the DIC method, it is difficult to obtain displacement distribution information of the bolt 35, making it difficult to diagnose the fastening state of the bolt 35.

[0072] Figure 7B schematically shows another example of the bolt fastening portion 24 of the wind power generation equipment 3 in this embodiment.

[0073] In the bolted fastening section 24, the head of the bolt 22 and the fastened surface 30 are colored differently from each other. For example, the head of the bolt 22 is colored black, which is different in color from the fastened surface 30.

[0074] In a bolted fastening section 24, if the head of the bolt 22 and the fastened surface 30 are colored with different colors, the color contrast between the bolt 22 and the fastened surface 30 increases. Therefore, when image analysis processing is performed on such a bolted fastening section 24 using the DIC method, it becomes easier to obtain displacement distribution information of the bolt 22, making it suitable for diagnosing the fastening state of the bolt 22.

[0075] Furthermore, it is preferable that the process of coloring the bolts 35 and applying the random pattern 28 is performed before the process in which the imaging unit 15 takes an image of the bolt fastening portion 24 before the wind power generation equipment 3 starts operation (S1 in Figure 3).

[0076] Figure 8 schematically shows another example of a bolt fastening section 24 of the wind power generation equipment 3 in this embodiment. The fastened surface 30 is colored white, and a bolt 22 is fastened to it. The bolt 22 has a random pattern 28 applied to the top surface of its head. This random pattern 28 is applied to the bolt 22 in a color different from the base color of the bolt head and the color of the fastened surface 30.

[0077] Even if a random pattern 28 is applied to the top surface of the bolt head 22, performing image analysis processing on the bolt fastening portion 24 using the DIC method makes it easier to obtain displacement distribution information of the bolt 22. Also, because the bolt 22 is applied to the random pattern 28, the top surface of the bolt head has multiple colors. Even if the head of the bolt 22 is colored with multiple colors, performing image analysis processing on the bolt fastening portion 24 using the DIC method makes it easier to obtain displacement distribution information of the bolt 22.

[0078] Figure 9 is a perspective view showing an example of the head of a bolt 22 enclosed by the dashed line B in the bolt fastening section 24 shown in Figure 8. As shown in Figure 9, a random pattern 28 is applied to the top surface of the head of the bolt 22.

[0079] The top surface of the head of bolt 22 may have a speckle pattern other than the random pattern 28.

[0080] Figures 10A to 10D show examples of speckle patterns applied to the top surface of the head of bolt 22. Figure 10A shows an example where the speckle pattern is a random pattern (spotted pattern). Figure 10B shows an example where the speckle pattern is a two-dimensional code (e.g., a QR code® or a data matrix code). Figure 10C shows an example where the speckle pattern is a string (e.g., a text string containing individual identification information for bolt 22). Figure 10D shows an example where the speckle pattern consists of a pattern of solid circles and rings.

[0081] The speckle pattern applied to the top surface of the bolt head 22 can be any form, not limited to those exemplified herein, as long as it clearly distinguishes the fastened surface 30 and the bolt 22 in the bolt fastening portion 24.

[0082] The imaging unit 15 photographs the bolt fastening portion 24, that is, the top surface of the head of the bolt 22 having such a speckle pattern and the fastened surface 30, and the processing unit 16 can obtain displacement distribution information of the bolt 22 by performing image analysis of the image captured by the imaging unit 15 using the DIC method.

[0083] The method for applying the speckle pattern (pattern) to the top surface of the bolt head 22 can be any method. For example, when applying a pattern to the bolt 22 by coating, the pattern can be applied by applying a solution containing a solvent and the constituent materials of the pattern to the bolt 22 and drying it. The application and drying can be carried out with any application and drying apparatus. Alternatively, the pattern can be applied to the top surface of the bolt head 22 by forming a pattern on any member such as a coating material, a sheet-like member, and a seal-like member, and then fixing this member to the top surface of the bolt head 22 so that it does not peel off. The formation of the pattern on the member and the fixing of the member with the pattern on it to the bolt 22 can be carried out with any apparatus.

[0084] Another method for applying a pattern to the top surface of the bolt head 22 is to use a laser marking device. In this method, the pattern is formed by heating the very surface of the bolt head 22 with a laser. Therefore, issues such as peeling or cracking of the coating or patterned material, which can occur when patterns are applied using the methods described above, do not occur. Furthermore, in this method, a pattern with more favorable contrast can be formed by painting the top surface of the bolt head 22 and then heating the surface layer of this painted surface with a laser.

[0085] As explained above, the method for applying a pattern to the bolt 22 and the members on which the pattern is formed can be arbitrarily determined, and can be selected or combined, for example, depending on the purpose.

[0086] The speckle pattern may be applied to the fastened surface 30 rather than to the bolt 22.

[0087] Figure 11 schematically shows an example of a bolted fastening section 24 in which a speckle pattern is applied to the fastened surface 30. The speckle pattern is a random pattern 28 (spotted pattern). Multiple bolts 22 are arranged at approximately equal intervals along the circumferential direction of the fastened surface 30.

[0088] In the diagnostic step 26, a subset region R is set, assuming that the bolt fastening portion 24 is covered with a random pattern 28 (spotted pattern) consisting of bolts 22 and the fastened surface 30. Then, the processing unit 16 performs image analysis processing on the images of the bolt fastening portion 24 before and after deformation using the DIC method.

[0089] Furthermore, the speckle pattern may be applied to both the bolt 22 and the fastened surface 30. In this case, the top surface of the bolt head and the fastened surface 30 shall have different speckle patterns.

[0090] In the above description, the location of the imaging unit 15 is the floor surface of the tower 8. However, the imaging unit 15 is not limited to this location; it can be installed in any location from which the entire bolt fastening section 24 can be photographed. For example, the imaging unit 15 can be installed in the foundation 14 or inside the tower 8.

[0091] In the above description, an example was described in which the imaging unit 15 photographs the tower flange connection portion 82 on the base portion 14 side of the bolt fastening portion 24, and the processing unit 16 diagnoses the tower flange connection portion 82 side of the bolt fastening portion 24. In this embodiment, the imaging unit 15 can also photograph the tower flange connection portion 81 on the nacelle 7 side of the bolt fastening portion 24, and the processing unit 16 can diagnose the tower flange connection portion 81 side of the bolt fastening portion 24. In this case, the nuts 23 fastened to the bolts 22 can be diagnosed and inspected.

[0092] Furthermore, the imaging unit 15 can photograph the bolt fastenings at the connection between the yaw gear 13 and the tower 8, and the bolt fastenings at the connection between the yaw gear 13 and the nacelle 7, and the processing unit 16 can diagnose such bolt fastenings.

[0093] The above description illustrates an example in which the bolt fastening portion 24 is annular and multiple bolts 22 are arranged along the circumferential direction. The multiple bolts 22 may be arranged in any direction, for example, they may be arranged side by side in two directions in two dimensions.

[0094] Furthermore, by pre-determining the relationship between the external force acting on the structure (for example, the wind power generation equipment 3) and the displacement distribution information of the bolts 22 using methods such as finite element analysis, it is also possible to estimate the magnitude and direction of the external force acting on the structure based on the displacement distribution information obtained using the inspection device and inspection method according to this embodiment.

[0095] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and the present invention is not necessarily limited to embodiments having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add configurations from other embodiments to the configuration of one embodiment. Furthermore, it is possible to delete parts of the configuration of each embodiment, or to add or replace other configurations. [Explanation of Symbols]

[0096] 1...Inspection device, 3...Wind power generation equipment, 4...Blade, 5...Rotor hub, 6...Rotating main shaft, 7...Nacelle, 8...Tower, 9...Speed ​​increaser, 10...Power generation device, 11...Wind load, 12a...Main shaft rotation direction, 12b...Slewing rotation direction, 13...Yaw gear, 14...Base section, 15...Image unit, 16...Processing unit, 18...Display unit, 19...Wind direction control unit, 20...Output control unit, 21...Tower connection section, 22...Bolt, 23...Nut, 24 ...bolt fastening section, 26...diagnostic process, 27...control process, 28, 28a, 28b...random pattern, 30...fastened surface, 32...position where the bolt has been displaced, 33...vector, 34...bolt fastening section, 35...bolt, 36...fastened surface, 40...rotor, 81...tower flange connection section on the nacelle side, 82...tower flange connection section on the foundation side, 83...shape of the fastened surface before deformation, 84...shape of the fastened surface after deformation.

Claims

1. A camera unit that photographs a bolted fastening section of a structure that is fastened with multiple bolts and acquires an image that includes multiple of the bolts, A processing unit capable of controlling the operation of the aforementioned structure, A display unit connected to the aforementioned processing unit, Equipped with, The imaging unit photographs the bolt fastening portion before the load is applied to obtain a first image of the bolt fastening portion before deformation, and photographs the bolt fastening portion after the load is applied to obtain a second image of the bolt fastening portion after deformation. The processing unit performs image analysis on the first image and the second image to calculate the distribution of the displacement amount and direction of displacement of the multiple bolts. The display unit displays the distribution, The processing unit controls the operation of the structure such that the displacement of each of the multiple bolts is less than a preset allowable value. A device for inspecting the state of bolt fastening, characterized by the following features.

2. The processing unit performs the image analysis process on the first image and the second image using the digital image correlation method. The bolt fastening condition inspection device according to claim 1.

3. The bolt fastening portion comprises a plurality of bolts and a fastened surface to which the plurality of bolts are fastened, and a speckle pattern is provided on either the head of the bolt or the fastened surface. The imaging unit photographs the bolt fastening portion to which the speckle pattern is applied. The bolt fastening condition inspection device according to claim 1.

4. The bolt fastening portion comprises a plurality of bolts and a fastened surface to which the plurality of bolts are fastened, and the bolt heads and the fastened surface are provided with different speckle patterns. The imaging unit photographs the bolt fastening portion to which the speckle pattern is applied. The bolt fastening condition inspection device according to claim 1.

5. The bolt fastening portion comprises a plurality of bolts and a fastened surface to which the plurality of bolts are fastened, and the heads of the bolts and the fastened surface are colored in different colors from each other. The aforementioned imaging unit photographs the bolt fastening portion which is colored with the aforementioned color. The bolt fastening condition inspection device according to claim 1.

6. The imaging unit captures a bolted fastening portion of a structure, which is fastened with multiple bolts, before a load is applied, and obtains a first image of the bolted fastening portion before deformation, which includes multiple bolts. The imaging unit performs a second image acquisition step in which it photographs the bolt fastening portion after a load has been applied and obtains a second image of the deformed bolt fastening portion that includes a plurality of the bolts, The processing unit performs image analysis on the first image and the second image to calculate the distribution of the displacement amount and displacement direction of the multiple bolts, and The display unit performs a display step of displaying the distribution, The processing unit includes a control step of controlling the operation of the structure so that the displacement amount of each of the multiple bolts is less than a preset allowable value, Having, A method for inspecting the state of bolt fastening, characterized by the following features.

7. In the distribution calculation step, the processing unit performs the image analysis process on the first image and the second image using the digital image correlation method. The method for inspecting the bolt fastening state according to claim 6.

8. The bolt fastening portion comprises a plurality of bolts and a fastened surface to which the plurality of bolts are fastened, and a speckle pattern is provided on either the head of the bolt or the fastened surface. The method for inspecting the bolt fastening state according to claim 6.

9. The bolt fastening portion comprises a plurality of bolts and a fastened surface to which the plurality of bolts are fastened, and the bolt heads and the fastened surface are provided with different speckle patterns. The method for inspecting the bolt fastening state according to claim 6.

10. The bolt fastening portion comprises a plurality of bolts and a fastened surface to which the plurality of bolts are fastened, and the heads of the bolts and the fastened surface are colored in different colors from each other. The method for inspecting the bolt fastening state according to claim 6.

Images