Cantilever beam based distributed nut loosening optical fiber detection system

Abstract

The application provides a cantilever beam-based distributed nut loosening optical fiber detection system, which comprises a base structure, a cantilever beam, two supporting members, a force adjusting structure and a cantilever beam inclination state adjusting structure, the base structure is fixedly connected with a bolt in a threaded structure, one end of the cantilever beam is fixed on the base structure, and the other end is a free end in suspension, the cantilever beam inclination state adjusting structure and the two supporting members are both fixed on the outer side surface of the cantilever beam, and the cantilever beam inclination state adjusting structure is located between the two supporting members; the nut loosening rotation angle is different, which causes the position and direction of the force applied by the force adjusting structure to the cantilever beam inclination state adjusting structure to be different, so that the inclination state of the cantilever beam is different, the distance between the two supporting members is different in different inclination states, and the strain of the sensing optical fiber between the two supporting members is different; according to the strain detected by the sensing optical fiber, the loosening rotation angle of the nut is determined. The nut loosening detection device arranged for each threaded structure is simple in structure and convenient to install.

Description

Technical Field

[0001] This invention belongs to the field of thread structure loosening detection, specifically relating to a distributed fiber optic nut loosening detection system based on a cantilever beam. Background Technology

[0002] Traditional thread loosening detection relies primarily on manual inspection, employing methods such as: tapping the screws to listen to the sound, wrench tightening inspection, and match mark marking. The tapping method requires a high level of experience and skill from the inspector; otherwise, accurate judgment may be impossible. The wrench tightening inspection method requires observation of the screws to be inspected on-site, selection of an appropriate wrench, adjustment of torque, and tightening of each screw individually. However, this method easily leads to repeated tightening of screws, potentially damaging bolts and nuts, causing bolt stretching and deformation, or even bolt breakage. This method is time-consuming, costly, and often increases troubleshooting time. Furthermore, some installation scenarios present situations where manual access or visual inspection is difficult. Therefore, traditional thread loosening detection methods are no longer sufficient to meet modern industrial requirements. With the development of artificial intelligence and image processing technology, image-based methods for detecting loose nuts have emerged. However, their measurement range is limited, the equipment is complex to install, and the equipment cost is high, making it difficult to put them into large-scale production applications.

[0003] Existing single-thread structure loosening detection systems based on sensing optical fibers (such as the patent application number 202210623855.4) typically suffer from drawbacks such as complex detection structures and cumbersome installation. Summary of the Invention

[0004] This invention provides a distributed fiber optic detection system for loose nuts based on cantilever beams, which solves the problems of complex detection structures and cumbersome installation in current single thread structure loosening detection systems based on sensing fibers.

[0005] According to a first aspect of the present invention, a distributed fiber optic nut loosening detection system based on a cantilever beam is provided, comprising a nut loosening detection device for each threaded structure. The nut loosening detection device includes a base structure, a cantilever beam, two support members, a force adjustment structure, and a cantilever beam tilt adjustment structure. The base structure is fixedly connected to a bolt in the threaded structure. One end of the cantilever beam is fixed to the base structure, and the other end is a free end suspended in the air. The cantilever beam tilt adjustment structure and the two support members are both fixed to the outer surface of the cantilever beam. The cantilever beam tilt adjustment structure is located between the two support members, and a sensing optical fiber is fixed between the two support members. One end of the force adjustment structure is connected to the nut in the threaded structure, and the other end abuts against the outer surface of the cantilever beam tilt adjustment structure. When the nut is loosened and rotated, it drives the force adjustment structure to rotate, so that the force adjustment structure applies a force to the cantilever beam tilt adjustment structure. After receiving the force, the cantilever beam tilt adjustment structure causes the free end of the cantilever beam to move inward toward the bolt, thereby causing the cantilever beam to tilt.

[0006] The loosening and rotation of the nut changes the position and direction of the force applied by the force adjustment structure to the cantilever beam tilt adjustment structure, thereby changing the tilt state of the cantilever beam. Different angles of nut loosening and rotation correspond to different tilt states of the cantilever beam, and the distance between the two supports is different in each tilt state, as is the strain of the sensing fiber between the two supports. The loosening and rotation angle of the nut is determined based on the strain currently detected by the sensing fiber.

[0007] In one optional implementation, the force adjustment structure includes a rotating component, a driving rod, and a pressure block. The rotating component is fixedly connected to the pressure block via the driving rod, which extends outward beyond the support component. The pressure block abuts against the outer surface of the cantilever beam tilt adjustment structure. The rotating component has a through hole matching the shape of the nut. The nut is fitted inside the rotating component. When the nut is loosened and rotated, it drives the rotating component to rotate. The rotating component drives the pressure block to rotate around the central axis of the nut via the driving rod. During the rotation of the pressure block, the position and direction of the force it applies to the cantilever beam tilt adjustment structure change.

[0008] In another alternative implementation, the pressure block is an L-shaped pressure block, with its vertical section's free end fixedly connected to the drive rod, its horizontal section perpendicular to the cantilever beam and its free end abutting against the cantilever beam's tilt adjustment structure, and the plane of the cantilever beam being parallel to the central axis of the nut.

[0009] In another alternative implementation, the cantilever beam tilt adjustment structure is an inclined plate, which is fixed to the cantilever beam and located between two supports. Along the direction of rotation of the pressure block, the thickness of the inclined plate relative to the cantilever beam gradually increases.

[0010] In another alternative implementation, the base structure includes a first connecting plate and a fixing plate that are fixedly connected. The first connecting plate is fixedly connected to a nut on a bolt in the threaded structure. One end of the cantilever beam is fixed to the outer side of the fixing plate via a second connecting plate, and the fixing plate is located above the first connecting plate.

[0011] In another alternative implementation, the fixed plate, the second connecting plate, and the cantilever beam are all located below the drive rod.

[0012] In another alternative implementation, during the loosening and rotation of the nut, neither the force adjustment structure nor the cantilever beam comes into contact with the sensing fiber.

[0013] In another alternative implementation, by designing the tilt adjustment structure of the cantilever beam, the strain on the sensing fiber changes accordingly after the nut rotates by a set angle, and the measurement resolution of the nut rotation angle can be designed.

[0014] The beneficial effects of this invention are:

[0015] This invention's loosening detection involves only a few components: a cantilever beam, supporting members, a force adjustment structure, and a cantilever beam tilt adjustment structure, making the structure relatively simple. Before use, the cantilever beam is already fixed to the bolts via the base structure, eliminating the need for separate cantilever beam installation. For the force adjustment structure, after tightening the threaded structure, simply connect one end of the force adjustment structure to the nut and abut the other end against the cantilever beam tilt adjustment structure on the outer surface of the cantilever beam. For the sensing fiber, it only needs to be fixed between the two supporting members on the outer surface of the cantilever beam. Therefore, installation of this invention only requires completing three steps: connecting the force adjustment structure to the threaded connection, abutting it against the cantilever beam tilt adjustment structure, and fixing the sensing fiber between the two supporting members, making the installation method relatively simple. This invention, through the force adjustment structure... By engaging with the cantilever beam tilt adjustment structure between the two supports on the cantilever beam, the force adjustment structure can be driven to apply a force to the position between the two supports on the cantilever beam when the nut is loosened and rotated. This ensures that the distance between the two supports changes during the loosening and rotation of the nut, thereby ensuring that the strain of the sensing fiber between the two supports changes. The addition of the cantilever beam tilt adjustment structure in this invention ensures that the tilt state of the cantilever beam changes correspondingly for each set angle of nut rotation, and that the distance between the two supports is different when the cantilever beam switches to different tilt states during the loosening and rotation of the nut. This ensures that the strain of the sensing fiber between the two supports is different for each set angle of nut loosening and rotation. Based on this, this invention can determine the loosening rotation angle of the nut based on the strain currently detected by the sensing fiber. Attached Figure Description

[0016] Figure 1 This is a perspective view of an embodiment of the distributed fiber optic nut loosening detection system based on a cantilever beam according to the present invention;

[0017] Figure 2 This is a partial perspective view of an embodiment of the distributed fiber optic nut loosening detection system based on a cantilever beam of the present invention;

[0018] Figure 3 This is a front view of an embodiment of the distributed fiber optic nut loosening detection system based on a cantilever beam according to the present invention;

[0019] Figure 4 This is a side view of an embodiment of the distributed nut loosening fiber optic detection system based on a cantilever beam according to the present invention;

[0020] Figure 5 This is a top view of an embodiment of the distributed fiber optic nut loosening detection system based on a cantilever beam according to the present invention;

[0021] Figure 6This is a perspective view of the connection relationship between the fixing plate and the cantilever beam of the present invention;

[0022] Figure 7 This is a top view showing the connection relationship between the fixed plate and the cantilever beam of the present invention;

[0023] Figure 8 This is a schematic diagram of the inclined plate of the present invention. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned objectives, features and advantages of the embodiments of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0025] In the description of this invention, unless otherwise specified and limited, it should be noted that the term "connection" should be interpreted broadly. For example, it can be a mechanical connection or an electrical connection, or it can be a connection between two internal components. It can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above term according to the specific circumstances.

[0026] See Figure 1 This is a three-dimensional structural view of an embodiment of the distributed fiber optic nut loosening detection system based on a cantilever beam according to the present invention. Combined with... Figures 2 to 5 As shown, the system may include a nut loosening detection device for each threaded structure 1. This nut loosening detection device may include a base structure 2, a cantilever beam 32, two support members 4, a force adjustment structure 5, and a cantilever beam tilt adjustment structure 6. The base structure 2 is fixedly connected to the bolt 12 in the threaded structure 1 (in the figure, this connection is achieved through a nut 13 on the bolt 12). One end of the cantilever beam 32 is fixed to the base structure 2, and the other end is a free end. The cantilever beam tilt adjustment structure 6 and the two support members 4 are all fixed to the outer surface of the cantilever beam 32. The cantilever beam tilt adjustment structure 6 is located between the two support members 4, and a sensing optical fiber 7 is fixed between the two support members 4. One end of the force adjustment structure 5 is connected to the nut 11 in the threaded structure 1, and the other end abuts against the outer surface of the cantilever beam tilt adjustment structure 6. When the nut 11 is loosened and rotated, it drives the force adjustment structure 5 to rotate, so that the force adjustment structure 5 applies a force to the cantilever beam tilt adjustment structure 6. After receiving the force, the cantilever beam tilt adjustment structure 6 causes the free end of the cantilever beam 32 to move inward toward the bolt 12, thereby causing the cantilever beam 32 to tilt.

[0027] The loosening and rotation of the nut 11 changes the position and direction of the force applied by the force adjustment structure 5 to the cantilever beam tilt adjustment structure 6, thereby changing the tilt state of the cantilever beam 32. The different angles of the loosening and rotation of the nut 11 correspond to different tilt states of the cantilever beam 32, and the distance between the two support members 4 is different in each tilt state. The strain of the sensing fiber 7 between the two support members 4 is also different. The loosening and rotation angle of the nut 11 is determined based on the strain currently detected by the sensing fiber 7.

[0028] In this embodiment, after the upper end of the bolt 12 passes through the object to be fixed and the nut 11 in sequence, the object to be fixed is tightened by the nut 11, so that the object to be fixed is tightened between the nut 11 and the nut 13 at the lower end of the bolt 12 (the object to be fixed is not shown in the figure). The cantilever beam 32 is located outside the threaded structure 1, parallel to the central axis of the threaded structure and spaced apart from the threaded structure. This invention's loosening detection involves only a few components: a cantilever beam, supporting members, a force adjustment structure, and a cantilever beam tilt adjustment structure, making the structure relatively simple. Before use, the cantilever beam is already fixed to the bolts via the base structure, eliminating the need for separate cantilever beam installation. For the force adjustment structure, after tightening the object using the threaded structure, simply connect one end of the force adjustment structure to the nut and abut the other end against the cantilever beam tilt adjustment structure on the outer surface of the cantilever beam. For the sensing fiber, it only needs to be fixed between the two supporting members on the outer surface of the cantilever beam. Therefore, the installation of this invention only requires completing three steps: connecting the force adjustment structure to the threaded connection, abutting it against the cantilever beam tilt adjustment structure, and fixing the sensing fiber between the two supporting members, making the installation method quite simple.

[0029] This invention achieves this by tilting a cantilever beam, thereby changing the distance between two supports on the cantilever beam and causing deformation of the sensing optical fibers fixed to the supports. While a force can be applied to any point on the cantilever beam to tilt it, if no force is applied between the two supports, the distance between them may not change, thus the strain on the sensing optical fibers between them will remain constant. Therefore, this invention, by engaging a force adjustment structure with the cantilever beam tilt adjustment structure between the two supports, allows the force adjustment structure to apply a force to the position between the two supports when the nut is loosened and rotated. This ensures that the distance between the two supports changes during the nut's loosening and rotation, thereby guaranteeing a change in the strain on the sensing optical fibers between them.

[0030] Furthermore, although applying force only between the two supports of the cantilever beam can cause it to tilt without setting a cantilever beam tilt adjustment structure, it cannot guarantee that the tilt state of the cantilever beam will be different for each set angle of nut rotation (i.e., it cannot guarantee that the force applied to the cantilever beam after the nut rotates by a corresponding angle will be sufficient to change the tilt state of the cantilever beam). Even if the tilt state of the cantilever beam changes, it cannot guarantee that the distance between the two supports of the cantilever beam will be different under different tilt states. Therefore, this invention adds a cantilever beam tilt adjustment structure. It can be seen that by adding a cantilever beam tilt adjustment structure, this invention can ensure that the tilt state of the cantilever beam changes for each set angle of nut rotation, and that the distance between the two supports is different when the cantilever beam switches to different tilt states during the loosening rotation of the nut. This ensures that the strain magnitude of the sensing fiber between the two supports is different for each set angle of nut loosening rotation. Based on this, this invention can determine the loosening rotation angle of the nut based on the strain magnitude currently detected by the sensing fiber. Furthermore, by designing the tilt adjustment structure of the cantilever beam, the strain on the sensing fiber changes accordingly after the nut rotates by a set angle, allowing for the design of the measurement resolution of the nut loosening rotation angle.

[0031] It should be noted that: during the loosening and rotation of the nut, the force adjustment structure will move, and the tilt state of the cantilever beam will change. In order to ensure that the deformation of the sensing fiber is only affected by the distance between the two supports, when designing the initial relative distance between the force adjustment structure and the sensing fiber, as well as the initial relative distance between the cantilever beam and the sensing fiber, it is necessary to ensure that during the loosening and rotation of the nut, neither the force adjustment structure nor the cantilever beam comes into contact with the sensing fiber.

[0032] In this embodiment, combined with Figures 2 to 5 As shown, the force adjustment structure 5 may include a rotating component 51, a driving rod 52, and a pressure block 53. The rotating component 51 is fixedly connected to the pressure block 53 through the driving rod 52. The driving rod 52 extends outward beyond the support component 4. The pressure block 53 abuts against the outer surface of the cantilever beam tilt adjustment structure 6. The rotating component 51 has a through hole that matches the shape of the nut 11. The nut 11 is fitted inside the rotating component 51. When the nut 11 is loosened and rotated, it drives the rotating component 51 to rotate. The rotating component 51 drives the pressure block 53 to rotate around the central axis of the nut 11 through the driving rod 52. During the rotation of the pressure block 53, the position and direction of the force it applies to the cantilever beam tilt adjustment structure 6 change. The pressure block 53 can be an L-shaped pressure block, with its vertical section free end fixedly connected to the drive rod 52, its horizontal section perpendicular to the cantilever beam 32 and its free end abutting against the cantilever beam tilt adjustment structure 6, and the plane of the cantilever beam 32 being parallel to the central axis of the nut 11.

[0033] The cantilever beam tilt adjustment structure 6 can be an inclined plate, which is fixed to the cantilever beam 32 and located between the two support members 4. Along the direction of rotation of the pressure block 53, the thickness of the inclined plate 6 relative to the cantilever beam 32 gradually increases. For example, the inclined plate 6 can be a stepped structure. Figure 8 As shown. The sensing fiber 7 between the two support members 4 can be parallel to the plane of the cantilever beam 32 and perpendicular to the central axis of the nut 11. The base structure 2 may include a first connecting plate 21 and a fixing plate 22 fixedly connected. The first connecting plate 21 is fixedly connected to the nut 13 on the bolt 12 in the threaded structure 1. One end of the cantilever beam 32 is fixed to the outer surface of the fixing plate 22 through the second connecting plate 31. The fixing plate 22 is located on the first connecting plate 21. The base structure 2 can be an L-shaped base. The first connecting plate 21 is a horizontal section, which can be perpendicular to the central axis of the screw 12 and fixed perpendicularly to the fixing plate 22. The fixing plate 22 is a vertical section, which is parallel to the central axis of the screw 12. The second connecting plate 31 is located between the fixing plate 22 and the cantilever beam 32 and is fixed perpendicularly to the fixing plate 22 and the cantilever beam 32 respectively. The fixing plate 22 and the cantilever beam 32 are parallel to each other. When the free end of the cantilever beam 32 moves inward toward the bolt, it also moves toward the fixed plate 22. To ensure that the nut can smoothly rotate the pressure block through the rotating component and the drive rod, the fixed plate 22, the second connecting plate 31, and the cantilever beam 32 are all located below the drive rod.

[0034] Both support members 4 may have fiber optic slots. The sensing fiber 7 is wound and fixed within the fiber optic slots of the two support members 4, parallel to the cantilever beam 32. The support member may be arc-shaped. The sensing fiber can be connected to a BOTDR testing device. When the sensing fiber is strained, the Brillouin scattering light signal in the sensing fiber will undergo a frequency shift. After the BOTDR testing device detects and calculates this frequency shift, it can determine the strain of the sensing fiber based on the frequency shift, thereby determining the looseness of the nut in the nut alignment. Furthermore, this invention can use a single sensing fiber to measure the looseness of multiple nut pairs. For each nut pair, the corresponding sensing fiber segment is fixed to the support rod for fixation.

[0035] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0036] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is defined solely by the appended claims.

Claims

1. A distributed fiber optic detection system for loose nuts based on a cantilever beam, characterized in that, The device includes a nut loosening detection device for each threaded structure. This device comprises a base structure, a cantilever beam, two support members, a force adjustment structure, and a cantilever beam tilt adjustment structure. The base structure is fixedly connected to the bolt in the threaded structure. One end of the cantilever beam is fixed to the base structure, and the other end is a free end suspended in the air. The cantilever beam tilt adjustment structure and the two support members are both fixed to the outer surface of the cantilever beam. The cantilever beam tilt adjustment structure is located between the two support members, and a sensing fiber is fixed between the two support members. One end of the force adjustment structure is connected to the nut in the threaded structure, and the other end abuts against the outer surface of the cantilever beam tilt adjustment structure. When the nut loosens and rotates, it causes the force adjustment structure to rotate, applying a force to the cantilever beam tilt adjustment structure. Upon receiving this force, the cantilever beam tilt adjustment structure causes the free end to move inward towards the bolt, thus tilting the cantilever beam. The loosening and rotation of the nut changes the position and direction of the force applied by the force adjustment structure to the cantilever beam tilt adjustment structure, thereby changing the tilt state of the cantilever beam. Different angles of nut loosening and rotation correspond to different tilt states of the cantilever beam, and the distance between the two supports is different in each tilt state, as is the strain of the sensing fiber between the two supports. The loosening and rotation angle of the nut is determined based on the strain currently detected by the sensing fiber.

2. The distributed fiber optic nut loosening detection system based on a cantilever beam according to claim 1, characterized in that, The force adjustment structure includes a rotating component, a drive rod, and a pressure block. The rotating component is fixedly connected to the pressure block via the drive rod, which extends outward beyond the two supporting components. The pressure block abuts against the outer surface of the cantilever beam tilt adjustment structure. The rotating component has a through hole matching the shape of the nut. The nut is fitted inside the rotating component. When the nut is loosened and rotated, it drives the rotating component to rotate. The rotating component drives the pressure block to rotate around the central axis of the nut via the drive rod. During the rotation of the pressure block, the position and direction of the force it applies to the cantilever beam tilt adjustment structure change.

3. The distributed fiber optic nut loosening detection system based on a cantilever beam according to claim 2, characterized in that, The pressure block is an L-shaped pressure block, with its vertical section's free end fixedly connected to the drive rod, its horizontal section perpendicular to the cantilever beam and its free end abutting against the cantilever beam's tilt adjustment structure, and the plane of the cantilever beam being parallel to the central axis of the nut.

4. The distributed fiber optic nut loosening detection system based on a cantilever beam according to claim 2 or 3, characterized in that, The cantilever beam tilt adjustment structure is an inclined plate, which is fixed on the cantilever beam and located between two support members. Along the direction of rotation of the pressure block, the thickness of the inclined plate relative to the cantilever beam gradually increases.

5. The distributed fiber optic nut loosening detection system based on a cantilever beam according to claim 4, characterized in that, The base structure includes a first connecting plate and a fixing plate that are fixedly connected. The first connecting plate is fixedly connected to the nut on the bolt in the threaded structure. One end of the cantilever beam is fixed to the outer side of the fixing plate through a second connecting plate. The fixing plate is located on the first connecting plate.

6. The distributed fiber optic nut loosening detection system based on a cantilever beam according to claim 5, characterized in that, The fixed plate, the second connecting plate, and the cantilever beam are all located below the drive rod.

7. The distributed fiber optic nut loosening detection system based on a cantilever beam according to claim 1, characterized in that, During the loosening and rotation of the nut, neither the force adjustment structure nor the cantilever beam comes into contact with the sensing optical fiber.

8. The distributed fiber optic nut loosening detection system based on a cantilever beam according to claim 1, characterized in that, By designing the tilt adjustment structure of the cantilever beam, the strain on the sensing fiber changes accordingly after the nut rotates by a set angle, and the measurement resolution of the nut's rotation angle can be designed.

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