CN116336956A

CN116336956A - Thread structure looseness universal measuring device based on distributed optical fiber sensing

Info

Publication number: CN116336956A
Application number: CN202310312342.6A
Authority: CN
Inventors: 朱涛
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2023-03-28
Filing date: 2023-03-28
Publication date: 2023-06-27

Abstract

The invention provides a thread structure loosening universal measuring device based on distributed optical fiber sensing, wherein a distributed sensing optical fiber is arranged on a spring piece, a bolt sequentially penetrates through a to-be-fixed object and a claw gasket positioned on the upper surface of the to-be-fixed object and then is in threaded connection with a first nut in the claw gasket, the first nut is rotated to enable the nut of the bolt to be abutted with the lower bottom surface of the to-be-fixed object, and a spring piece moving cavity is fixed on the to-be-fixed object; when the first nut rotates, the claw gasket drives the spring piece to stretch along the cavity of the spring piece moving cavity, so that the distributed sensing optical fiber is subjected to first change; and determining the change condition of the distributed sensing optical fiber according to the optical signal returned after the distributed sensing optical fiber receives the measuring optical signal, and determining the loosening condition of the thread structure according to the change condition of the distributed sensing optical fiber. The invention can realize the loose measurement of the thread structure with any setting angle, and has high universality and high measurement sensitivity.

Description

Thread structure looseness universal measuring device based on distributed optical fiber sensing

Technical Field

The invention belongs to the field of bolt looseness detection, and particularly relates to a thread structure looseness universal measuring device based on distributed optical fiber sensing.

Background

Bolt looseness on multiple nodes such as a power transmission tower is a main factor causing deformation or other damages of the tower, so that the method has very important significance in timely identifying the bolt looseness damage degree at the node plate. In the current bolt looseness measurement, most systems adopt a measuring method of strain gauges, one strain gauge corresponds to one measuring point, and in order to measure bolt looseness, a plurality of strain gauges are generally adopted for measurement. When detecting large-scale and large-scale structures, the method has the problems that a large number of strain gauges and matched electrical equipment are required, and the method is influenced by electromagnetic interference, so that the complexity of the system on hardware is increased, and the running and maintenance cost of the system is increased. In order to solve the above problems, researchers have proposed a distributed optical fiber sensing technology for monitoring the loosening situation of a threaded structure, for example, patent application No. 2022106238554, entitled "device for measuring loosening of a threaded structure based on distributed optical fiber sensing". However, this patent realizes that screw thread structure is not hard up the monitoring, needs to be with the help of the gravity of its partial subassembly, consequently its setting direction must vertical setting and make this partial subassembly up, can see at present that when utilizing distributed optical fiber sensing to carry out screw thread structure and become flexible measurement, screw thread structure can't set up according to arbitrary angle, has the problem that the setting angle commonality is not high.

Disclosure of Invention

The invention provides a thread structure loosening universal measuring device based on distributed optical fiber sensing, which aims to solve the problem that the setting angle of a thread structure in the existing distributed optical fiber thread structure loosening measuring device is not universal.

According to a first aspect of the embodiment of the invention, a thread structure loosening universal measuring device based on distributed optical fiber sensing is provided, and the thread structure loosening universal measuring device comprises a thread structure, a claw gasket, a spring piece moving cavity and a spring piece arranged in the spring piece moving cavity, wherein the spring piece is provided with a distributed sensing optical fiber, the thread structure comprises a bolt and a first nut, a second end of the bolt sequentially penetrates through a to-be-fixed object and the claw gasket positioned on the upper surface of the to-be-fixed object, is in threaded connection with the first nut in the claw gasket, and rotates the first nut to enable the nut of the bolt to abut against the lower bottom surface of the to-be-fixed object, so that the to-be-fixed object fastening is realized;

the first end of the spring piece is connected with the spring piece moving cavity, the second end of the spring piece moving cavity is connected with the claw gasket, and the spring piece moving cavity is fixed on the object to be fixed; when the first nut rotates, the claw gasket drives the spring piece to stretch along the cavity of the spring piece movement cavity, so that the distributed sensing optical fiber is subjected to first change; and determining the change condition of the distributed sensing optical fiber according to the optical signal returned after the distributed sensing optical fiber receives the measuring optical signal, and determining the loosening condition of the thread structure according to the change condition of the distributed sensing optical fiber.

In an alternative implementation, the first nut rotation includes the following types of rotation:

only the first nut of the bolt and the first nut is rotated upwards in the positive direction under the action of external force;

only when the bolt rotates downwards under the action of external force, the bolt and the first nut drive the first nut to rotate in the opposite direction, and the second claw gasket is abutted against the upper surface of the object to be fixed in the opposite direction rotation process of the first nut;

when the bolt is rotated downward by an external force, and the first nut is influenced by an external force which prevents the first nut from rotating in the opposite direction, the first nut rotates in the forward direction or the opposite direction.

In another optional implementation manner, determining the loosening condition of the thread structure according to the change condition of the distributed sensing optical fiber specifically includes: judging whether the change of the distributed sensing optical fiber comprises a first change caused by the rotation of the first nut, if so, determining that the thread structure is loosened, otherwise, determining that the thread structure is not loosened.

In another alternative implementation manner, when the screw thread structure looseness measuring device is installed, the object to be fixed is fastened first, then the spring piece moving cavity is fixed on the object to be fixed, and then the second end of the spring piece in the spring piece moving cavity is connected with the claw gasket;

The first nut is spaced apart from and closely attached to the jaw pad and extends from within the jaw pad toward the first end of the bolt.

In another alternative implementation, the spring piece is in a wave shape relative to the upper surface of the object to be fixed, and the distributed sensing optical fibers are distributed on the spring piece along the wave trend.

In another optional implementation manner, the spring piece moving cavity comprises an upper cover and a bottom plate, the upper cover comprises a cover plate, and a first arc baffle and a second arc baffle which extend towards the bottom plate on the cover plate, the first arc baffle and the second arc baffle are concentric with a circular shaft, the radian is equal, the two ends of the first arc baffle are aligned, and the first end of the spring piece is clamped in a first buckle between the first arc baffle and the second arc baffle, so that the first end of the spring piece is fixed;

the bottom plate comprises a bottom plate body, an annular groove is formed in the bottom plate body, the annular groove is matched with the space between the first circular arc partition plate and the second circular arc partition plate, and after the upper cover is covered on the bottom plate, the space surrounded by the annular groove, the first circular arc partition plate and the second circular arc partition plate forms a cavity of the spring piece movement cavity.

In another alternative implementation, the base plate body extends upward to form an arcuate connecting plate, and the arcuate connecting plate extends inward to form an arcuate baffle parallel to the base plate body; the bottom plate body is also provided with an arc through hole, the arc through hole is positioned below the arc baffle, two ends of the arc through hole extend out of the position right below the arc baffle respectively, and the arc connecting plate, the arc baffle, the arc through hole and the second arc baffle are concentric with a circular mandrel;

the second circular arc partition plate is positioned at the outer side of the first circular arc partition plate, and a third circular arc partition plate extends outwards from one end of the second circular arc partition plate, which faces the bottom plate; two ends of the outer edge of the third arc-shaped partition plate respectively extend downwards to form a convex block; inserting the third arc baffle plate between the arc baffle plate and the bottom plate body, and inserting the convex blocks into the arc through holes so as to realize clamping of the upper cover and the bottom plate;

the circular arc baffle, the cover plate and the bottom plate body are respectively provided with a matched first through hole, and the fastening piece sequentially penetrates through the first through holes of the circular arc baffle, the cover plate and the bottom plate body to fix the spring piece moving cavity formed by the upper cover and the bottom plate on the object to be fixed.

In another optional implementation manner, the cover plate and the bottom plate body are both provided with central through holes for accommodating the claw gaskets, the central through holes on the cover plate are positioned at the inner sides of the first circular arc partition plates, and the central through holes on the bottom plate body are positioned at the inner sides of the annular grooves;

The circular baffle ring extends upwards from the outer side groove edge of the annular groove, and after the upper cover is clamped on the bottom plate, the first circular arc baffle plate is positioned in the annular groove, and the second circular arc baffle plate is positioned outside the circular baffle ring.

In another optional implementation manner, the claw gasket comprises a gasket, fixing blocks and a connecting portion, a second through hole with the radius larger than or equal to the radius of the bolt is formed in the gasket, the gasket upwards extends to form a plurality of fixing blocks, each fixing block is circumferentially and uniformly arranged outside the second through hole, and one fixing block outwards extends to form the connecting portion for being in butt joint with the second end of the spring piece.

In another alternative implementation manner, one end of the distributed sensing optical fiber of the current thread structure can be connected with the next thread structure after penetrating out of the spring piece, and the distributed sensing optical fiber is distributed on the spring piece of the next thread structure, so that the loosening measurement of a plurality of thread structures can be realized by using one distributed sensing optical fiber;

the optical fiber sensor comprises a light source, a pulse modulator, a frequency shifter, a circulator, a coupler, a photoelectric detector, a data acquisition unit, a data processor and an optical fiber to be detected, wherein distributed sensing optical fibers in a plurality of thread structures are connected in series to form the optical fiber to be detected, the output end of the light source is respectively connected with the pulse modulator and the frequency shifter, the output end of the pulse modulator is connected with the first end of the circulator, the second end of the circulator is sequentially connected with one end of the optical fiber to be detected, the third end is connected with the first input end of the coupler, the output end of the frequency shifter is connected with the second input end of the coupler, and the output end of the coupler is sequentially connected with the data processor through the photoelectric detector and the data acquisition unit;

The light source divides continuous light into two paths of detection light and reference light, wherein the detection light is periodically injected into the optical fiber to be detected through the circulator according to a certain period, the optical fiber to be detected generates backward transmitted Brillouin scattering light after receiving the detection light, so that Brillouin frequency shift is generated, and the backward transmitted Brillouin scattering light is transmitted to the coupler through the circulator; the reference light is injected into the frequency shifter, and is transmitted to the circulator after frequency shift occurs through the frequency shifter; the Brillouin scattered light and the reference light after frequency shift interfere at the coupler to form an interference light signal; the photoelectric detector converts the interference optical signal into an interference electric signal; the data collector collects the interference electric signals and sends the collected interference electric signals to the data processor; and the data processor demodulates the change condition of the optical fiber to be detected according to the interference electric signal, and determines the loosening condition of each thread structure according to the change condition of each distributed sensing optical fiber in the optical fiber to be detected.

The beneficial effects of the invention are as follows:

1. the screw structure comprises a bolt and a first nut, the nut of the bolt is abutted against an object to be fixed, the second end of the bolt passes through the object to be fixed and is in threaded connection with the first nut, the object to be fixed can be fastened by rotating the first nut, the loosening measurement mainly depends on first change of the distributed sensing optical fiber caused by rotation of the first nut, and the rotation of the first nut is irrelevant to the setting angle of the screw structure, so that the loosening measurement is irrelevant to the setting angle of the screw structure, namely the loosening measurement of the screw structure with any setting angle can be realized, and the universality is high; the invention is provided with the spring piece, the distributed sensing optical fiber is arranged on the spring piece, and the spring piece is driven to stretch along the cavity of the spring piece moving cavity when the thread structure is loosened, so that the stretching amount of the spring piece is larger even if the action amplitude caused by the loosening of the thread structure is smaller, and correspondingly, the change of the distributed sensing optical fiber on the spring piece is larger, therefore, the loosening measurement sensitivity of the thread structure is higher;

2. According to the invention, the screw connection tightness degree between the bolt and the first nut is designed, so that the bolt is driven to rotate in the opposite direction when being rotated downwards by external force, the loosening situation of the bolt when being rotated downwards by external force can be further subdivided, the loosening can not be determined by relying on the first change of the distributed sensing optical fiber only when the external force value applied to the first nut reaches a specific value after subdivision, and the dynamic changing external force environment enables the value to be ignored, so that any possible loosening situation can be determined by relying on the first change of the distributed sensing optical fiber, and various loosening situations possibly occurring in a screw structure can be comprehensively monitored, and the monitoring sensitivity of various loosening situations is higher; in addition, the screw thread structure only comprises two components, namely the screw and the first nut, so that the types of loosening conditions formed by combination are fewer, and under the combined loosening conditions, the first nut is driven to rotate in the opposite direction when the bolt is rotated downwards by external force, so that the loosening conditions of all the formed types can be monitored by utilizing the first change;

3. According to the invention, the installation sequence of each component of the device is designed, so that the installation requirement of an object to be fixed with any thickness can be met, and the universality of the device can be further improved; according to the invention, the first nut and the claw gasket are separately arranged, so that the flexibility of installation of the device can be improved, and even if the fixation of the spring piece moving cavity is finished before the fastening of an object to be fixed is finished, the installation of a loosening measuring device of an object to be fixed with any thickness can be continuously realized, and the applicability is stronger; in addition, the first nut and the claw gasket are tightly attached, so that the claw gasket can be smoothly driven to synchronously rotate when the first nut rotates; the first nut extends out of the claw gasket towards the second end of the bolt, so that the first nut is convenient to rotate and fasten directly when overhauling the first nut;

4. according to the invention, the spring piece is in a wave shape, and the distributed sensing optical fibers are distributed on the spring piece along the wave trend, so that the change caused by the rotation of the first nut and the inclination of the bolt can be amplified, and the looseness measurement sensitivity of the thread structure can be improved;

5. according to the invention, the spring piece moving cavity is divided into the upper cover and the bottom plate, the upper cover is arranged on the bottom plate to form a cavity for placing the spring piece, when the spring piece and/or the distribution sensing optical fibers on the spring piece are damaged, the spring piece can be taken out for replacement after the upper cover is taken down, and the spring piece moving cavity is not required to be replaced when the spring piece is replaced, so that the maintenance cost is reduced; in addition, the first arc baffle and the second arc baffle extend out of one side of the upper cover, which faces the bottom plate, and the two baffles are arc-shaped, so that a cavity formed by the two arc baffles on the upper cover and the annular groove on the bottom plate is arc-shaped;

6. According to the invention, the connecting mechanism between the upper cover and the bottom plate is designed, so that the upper cover can be conveniently and quickly clamped on the bottom plate, and corresponding through holes on the upper cover and the bottom plate are quickly aligned, so that a spring piece moving cavity formed by the upper cover and the bottom plate can be conveniently and quickly fixed on an object to be fixed by using a fastener, and the mounting efficiency of the spring piece moving cavity is improved;

7. according to the invention, the central through holes enough for accommodating the claw gaskets are formed in the upper cover and the bottom plate, so that the rotation of the claw gaskets is not influenced by the movement cavity of the spring piece; according to the invention, the circular baffle ring extends upwards from the outer side groove edge of the annular groove, and the second circular arc baffle plate is positioned outside the circular baffle ring and not in the annular groove, so that when the upper cover is clamped on the bottom plate, the two circular arc baffle plates in the upper cover are not required to be aligned with the annular groove, and therefore, the clamping efficiency between the upper cover and the bottom plate can be further improved, and the spring piece movement cavity installation efficiency is further improved;

8. according to the invention, the distributed sensing optical fibers corresponding to the plurality of thread structures are connected in series, and the loosening measurement of the plurality of thread structures can be realized by utilizing one optical fiber.

Drawings

FIG. 1 is a schematic diagram of the overall structure of an embodiment of a thread structure loosening universal measuring device based on distributed optical fiber sensing according to the present invention;

FIG. 2 is a side view of the overall structure of one embodiment of the thread-loosening universal measuring device of the present invention based on distributed fiber optic sensing;

FIG. 3 is a cross-sectional view A-A of FIG. 2;

FIG. 4 is a schematic view of the structure of the spring plate of the present invention;

FIG. 5 is a schematic view of the structure of the upper cover of the present invention;

FIG. 6 is a schematic view of the structure of the base plate of the present invention;

FIG. 7 is a schematic view of a portion of the structure of the base plate of the present invention at a first view angle;

FIG. 8 is a schematic view of a portion of the structure of the base plate of the present invention at a second view angle;

FIG. 9 is a schematic view of the structure of the present invention with the upper cover and base plate assembled;

FIG. 10 is a schematic view of the construction of the jaw pad of the present invention;

FIG. 11 is a diagram of the positional relationship of the upper cover and the claw gasket of the present invention;

FIG. 12 is a top view of the jaw pad and base plate of the present invention;

FIG. 13 is a schematic diagram of a measurement structure of an embodiment of a thread loosening universal measuring device based on distributed optical fiber sensing according to the present invention.

Detailed Description

In order to better understand the technical solution in the embodiments of the present invention and make the above objects, features and advantages of the embodiments of the present invention more comprehensible, the technical solution in the embodiments of the present invention is described in further detail below with reference to the accompanying drawings.

In the description of the present invention, unless otherwise specified and defined, it should be noted that the term "connected" should be interpreted broadly, and for example, it may be a mechanical connection or an electrical connection, or may be a connection between two elements, or may be a direct connection or may be an indirect connection through an intermediary, and it will be understood to those skilled in the art that the specific meaning of the term may be interpreted according to the specific circumstances.

Referring to fig. 1, an overall structure diagram of an embodiment of a thread structure loosening universal measuring device based on distributed optical fiber sensing according to the present invention is shown. As shown in fig. 2 and fig. 3, the universal measuring device for loosening of a thread structure based on distributed optical fiber sensing may include a thread structure, a claw gasket 2, a spring piece moving cavity 3 and a spring piece 4 disposed in the spring piece moving cavity 3, the thread structure may include a bolt 1 and a first nut 13, the spring piece 4 is provided with a distributed sensing optical fiber, and a second end of the bolt 1 sequentially passes through a to-be-fixed object 5 and the claw gasket 2 located on the upper surface of the to-be-fixed object, and is in threaded connection with the first nut 13 in the claw gasket 2, and the first nut 13 is rotated to enable the nut 12 of the bolt 1 to be abutted to the lower bottom surface of the to-be-fixed object 5, so as to fasten the to-be-fixed object 5. The first end of the spring piece 4 is connected with the spring piece moving cavity 3, the second end of the spring piece 4 is connected with the claw gasket 2, and the spring piece moving cavity 3 is fixed on the object 5 to be fixed; when the first nut 13 rotates, the claw gasket 2 drives the spring piece 4 to stretch and retract along the cavity of the spring piece moving cavity 3, so that the distributed sensing optical fiber is subjected to first change; and determining the change condition of the distributed sensing optical fiber according to the optical signal returned after the distributed sensing optical fiber receives the measuring optical signal, and determining the loosening condition of the thread structure 1 according to the change condition of the distributed sensing optical fiber. Wherein, the change can be strain or deformation; the jaw pad 2 may be located inside the leaf spring movement chamber 3.

The screw structure comprises a bolt and a first nut, the nut of the bolt is abutted against an object to be fixed, the second end of the bolt passes through the object to be fixed and is in threaded connection with the first nut, the object to be fixed can be fastened by rotating the first nut, the loosening measurement mainly depends on first change of the distributed sensing optical fiber caused by rotation of the first nut, and the rotation of the first nut is irrelevant to the setting angle of the screw structure, so that the loosening measurement is irrelevant to the setting angle of the screw structure (namely, the angle of the bolt relative to the horizontal plane), namely, the loosening measurement of the screw structure with any setting angle can be realized, and the universality is high. When the distributed sensing optical fiber is used for reflecting the loosening condition of the thread structure, if the distributed sensing optical fiber is directly connected with the thread structure, the loosening identification sensitivity of the thread structure is lower because the action amplitude caused by the loosening of the thread structure is difficult to identify. The invention is provided with the spring piece, the distributed sensing optical fiber is arranged on the spring piece, and the spring piece is driven to stretch along the cavity of the spring piece moving cavity when the thread structure is loosened, so that the stretching amount of the spring piece is larger even if the action amplitude caused by the loosening of the thread structure is smaller, and correspondingly, the change of the distributed sensing optical fiber on the spring piece is larger, therefore, the thread structure loosening measurement sensitivity is higher.

In this embodiment, the bolt 1 may include a screw 11 and a nut 12 that are fixedly connected, since the nut is fixed on the bolt 1, when the nut abuts against the object 5 to be fixed, the distance between the first nut 13 and the nut determines the thickness of the object to be fixed after the fastening is completed, and the first nut 13 rotates while driving the claw washer 2 to rotate, so that the positions of the first nut 13 on the screw 11 are different, and the directions of the connecting portions on the claw washer 2 for connecting the second ends of the spring pieces 4 are different correspondingly, that is, the directions of the connecting portions on the claw washer 2 are related to the thickness of the object to be fixed. If the spring piece moving cavity 3 is first fixed on the object 5 to be fixed to fix the first end of the spring piece 4 when the thickness of the object 5 to be fixed makes the connecting part on the claw pad 2 point to the first end of the spring piece 4, the second end of the spring piece 4 cannot be butted with the connecting part on the claw pad 2 even if the spring piece 4 is compressed to the limit. It can be seen that, when the first nut 13 is rotated in place and before the object to be fixed is fastened, the spring piece moving cavity 3 is fixed, and the object to be fixed with any thickness may not be installed, so that the universality is low. Therefore, when the screw thread structure loosening universal measuring device is installed, the object to be fixed can be fastened first, then the spring piece moving cavity is fixed on the object to be fixed, and then the second end of the spring piece in the spring piece moving cavity is connected with the claw gasket. According to the invention, through designing the installation sequence of each component of the device, the installation requirement of an object to be fixed with any thickness can be met, so that the universality of the device can be further improved.

In this embodiment, the first nut 13 may be separately disposed from the jaw pad 2 and closely attached thereto. When the invention is installed, if the installation sequence is wrong, the spring piece moving cavity is firstly fixed to the object to be fixed, and then the object to be fixed is fastened, the second end of the spring piece 4 can not be butted with the connecting part on the claw gasket 2, and at the moment, if the first nut 13 and the claw gasket 2 are integrally formed, the spring piece moving cavity can only be reinstalled after being disassembled, and the installation flexibility is poor. According to the invention, the first nut 13 and the claw gasket 2 are separately arranged, at the moment, if the spring piece moving cavity 3 is fixed before the object 5 to be fixed is fastened, the direction of a connecting part on the claw gasket 2, which is connected with the second end of the spring piece 4, can be firstly adjusted according to the connecting position of the first end of the spring piece 4 and the spring piece moving cavity 3, when the first nut 13 rotates to the inlet of the upper end of the claw gasket 2, the claw gasket 2 is moved to the first nut 13, so that the first nut 13 is arranged in the claw gasket 2, and then the first nut 13 drives the claw gasket 2 to rotate, so that the direction of the connecting part on the claw gasket 2 is proper after the object to be fixed is fastened. Because the direction of the connecting part between the claw gasket 2 and the spring piece 4 is adjustable before the claw gasket 2 rotates along with the first nut 13, the invention can improve the installation flexibility of the device by separating the first nut from the claw gasket and independently arranging the claw gasket, and can continuously realize the installation of the looseness measuring device of the object to be fixed with any thickness even if the fixation of the spring piece moving cavity is completed before the fastening of the object to be fixed is completed, thereby having stronger applicability; in addition, the first nut and the claw gasket are tightly attached, so that the claw gasket can be smoothly driven to synchronously rotate when the first nut rotates. In addition, as shown in fig. 1, the first nut 13 may also extend from the claw washer 2 toward the second end of the bolt 1, so that the first nut can be conveniently and directly fastened in rotation during installation and maintenance of the first nut.

Because the position of the object 5 to be fixed is fixed, after the object 5 to be fixed is fastened, the first nut 13 cannot continuously rotate downwards under the action of external force, and the bolt 1 cannot continuously rotate upwards under the limit action of the nut 12, the loosening of the thread structure may have the following situations:

the first is that only the first nut 13 in the bolt 1 and the first nut 13 is rotated in the upward positive direction by external force, at this time, the bolt 1 is not externally forced, the first nut 13 can drive the claw washer 2 to synchronously rotate, the claw washer 2 rotates and drives the spring piece 4 to stretch or compress along the cavity of the spring piece moving cavity 3, so that the distributed sensing optical fiber is subjected to the first change in the positive direction, and because the spring piece 4 has a certain expansion limit, after the first nut 13 rotates to a certain angle, the spring piece 4 cannot continuously expand and contract, and under the limiting effect of the spring piece, the first nut 13 stops continuously rotating. In addition, as the first nut 13 is rotated upward, the distance between the nut 12 and the first nut 13 increases, the bolt 1 is tilted with respect to the object to be fixed, and at this time, the distributed sensing fiber is changed in a second manner due to the tilting of the bolt 1. In this case, it can be seen that the distributed sensing fiber generates a first change in the forward direction due to the rotation of the first nut 13 and a second change due to the inclination of the bolt 1, and the change is determined by the rotation angle of the first nut 13 and the inclination angle of the bolt 1.

The second is that only the bolt 1 in the bolt 1 and the first nut 13 is rotated downwards by external force, at this time, the first nut 13 is not externally applied, the bolt 1 drives the first nut 13 to rotate in the opposite direction, and the first nut 13 drives the spring piece 4 to compress or stretch along the cavity of the spring piece moving cavity 3 through the claw gasket 2, so that the distributed sensing optical fiber is subjected to the first change in the opposite direction. In addition, as the bolt 1 moves down, the distance between the nut 12 and the first nut 13 increases, the bolt 1 tilts with respect to the object to be fixed, and at this time, the distributed sensing fiber undergoes a second change due to the tilting of the bolt 1. It can be seen that in this case the distributed sensing fiber will undergo a first change in the opposite direction due to the rotation of the first nut 13 and a second change due to the tilting of the bolt 1, the change being determined by the rotation angle of the first nut 13 and the tilting angle of the bolt 1. It should be noted that, when the bolt 1 rotates downward to drive the first nut 13 and the jaw pad 2 to rotate, the first nut 13 and the jaw pad 2 will not move downward due to the position limitation of the object to be fixed 5, but only rotate on the contact plane with the object to be fixed 5, i.e. the jaw pad 2 contacts with the upper surface of the object to be fixed 4 during the reverse rotation of the first nut.

The third is that the bolt 1 is rotated downward by an external force, and the first nut 13 is affected by the external force preventing the reverse rotation thereof. Because when the bolt 1 rotates downwards to drive the first nut 13 and the claw gasket 2 to rotate, the first nut 13 and the claw gasket 2 only rotate on the abutting plane with the object 5 to be fixed, the first nut 13 may be kept at an initial position under the influence of external force and cannot rotate in the forward and reverse directions, but the distance between the nut 12 and the first nut 13 still increases, so that the second change of the distributed sensing optical fiber caused by the inclination of the bolt 1 still occurs, and the change condition is determined by the inclination angle of the bolt 1; next, the first nut 13 may be rotated in the opposite direction or in the forward direction by the external force, and the distance between the nut 12 and the first nut 13 may be increased regardless of the opposite direction or the forward direction, so that the distributed sensor may be changed in the opposite direction by the rotation of the first nut 13 or in the second direction by the inclination of the bolt 1, or in the first direction by the rotation of the first nut 13 or in the second direction by the inclination of the bolt 1, which is determined by the rotation angle of the first nut 13 and the inclination angle of the bolt 1.

As can be seen from the above description, the rotation of the first nut may include the following types of rotation: only the first nut of the bolt and the first nut is rotated upwards in the positive direction under the action of external force; only when the bolt rotates downwards under the action of external force, the bolt and the first nut drive the first nut to rotate in the opposite direction, and the second claw gasket is abutted against the upper surface of the object to be fixed in the opposite direction rotation process of the first nut; when the bolt is rotated downward by an external force, and the first nut is influenced by an external force which prevents the first nut from rotating in the opposite direction, the first nut rotates in the forward direction or the opposite direction.

In addition, in the above description, if the first nut 13 is kept not rotated when the bolt 1 is rotated downward by an external force, the looseness can be determined depending on the first change which is large in change only when the first nut 13 is rotated upward by an external force, and for all other cases where the first nut 13 is not rotated upward (for example, in the above-described case where only the bolt is rotated downward by an external force and the bolt and the first nut are simultaneously forced but the first nut is not rotated), the looseness can be determined depending on the second change only, but the second change is generally small and is difficult to be detected. The bolt is divided into the second and third two conditions when rotating downwards, the second condition can completely depend on the first change of the opposite direction caused by the rotation of the first nut to determine looseness, and the third condition only depends on the first change when the first nut is kept at the initial position due to the fact that the external force applied by the first nut is equal to the force applied by the bolt to drive the first nut to rotate in the opposite direction, and the looseness can be determined according to the second change only when the first nut does not rotate, namely the external force applied by the first nut is larger than or smaller than the force applied by the bolt to drive the first nut to rotate in the opposite direction, and accordingly the first nut rotates in the square direction or rotates in the opposite direction. Because the external force applied to the first nut is usually wind force, the first nut can be dynamically changed, and the first nut can be continuously kept at the initial position under the influence of the external force when the bolt rotates downwards, and the first nut belongs to extremely special and uncontrollable conditions, so that the first nut can be ignored. Therefore, the screw connection tightness between the bolt and the first nut is designed, so that the bolt is driven to rotate in the opposite direction when being rotated downwards by external force, the loosening situation when the bolt is driven to rotate downwards can be further subdivided, the loosening can not be determined by relying on the first change of the distributed sensing optical fiber only when the external force value applied to the first nut reaches a specific value after subdivision, the dynamic changing external force environment can be ignored, and therefore any possible loosening situation can be determined by relying on the first change of the distributed sensing optical fiber.

It should be noted that when the object to be fixed is fastened, a form of one screw rod plus two nuts may be adopted, but three components exist in the threaded structure, more kinds of loosening situations may occur due to mutual combination of the three components in different states, and when the threaded structure in the form is adopted, even if the bolt is rotated downwards by external force, the first nut is driven to rotate in the opposite direction, and monitoring of all loosening situations cannot be achieved by utilizing the first change. The screw thread structure only comprises two components, namely the screw and the first nut, so that the types of loosening conditions formed by combination are fewer, and under the combined loosening conditions, the first nut is driven to rotate in the opposite direction when the bolt is rotated downwards by external force, so that the loosening conditions of all the formed types can be monitored by utilizing the first change. In order to ensure that the first nut can rotate in the forward direction and in the reverse direction, the spring piece can be in an unlimited telescopic state, preferably in a stretching state to a small extent in the initial state.

According to the change condition of the distributed sensing optical fiber, the method for determining the loosening condition of the thread structure specifically comprises the following steps: judging whether the change of the distributed sensing optical fiber comprises a first change caused by the rotation of the first nut, if so, determining that the thread structure is loosened, otherwise, determining that the thread structure is not loosened.

As can be seen from the above embodiments, the screw structure of the present invention includes a bolt and a first nut, the nut of the bolt is abutted against the object to be fixed, the second end of the bolt passes through the object to be fixed and is in threaded connection with the first nut, the object to be fixed can be fastened by rotating the first nut, and the loosening measurement of the present invention mainly depends on the first change of the distributed sensing optical fiber caused by the rotation of the first nut, and the rotation of the first nut is irrelevant to the setting angle of the screw structure, so the loosening measurement of the present invention is irrelevant to the setting angle of the screw structure, that is, the loosening measurement of the screw structure with any setting angle can be realized, and the universality is high; the invention is provided with the spring piece, the distributed sensing optical fiber is arranged on the spring piece, and the spring piece is driven to stretch along the cavity of the spring piece moving cavity when the thread structure is loosened, so that the stretching amount of the spring piece is larger even if the action amplitude caused by the loosening of the thread structure is smaller, and correspondingly, the change of the distributed sensing optical fiber on the spring piece is larger, therefore, the thread structure loosening measurement sensitivity is higher.

In addition, as shown in fig. 4, the spring plate 4 has a wave shape with respect to the upper surface of the object to be fixed 5, and the distributed sensing optical fibers are arranged on the spring plate 4 along the wave direction. According to the invention, the spring piece is in a wave shape, and the distributed sensing optical fibers are distributed on the spring piece along the wave trend, so that the change caused by the rotation of the first nut can be amplified, and the thread structure looseness measurement sensitivity can be improved. As shown in fig. 4, 5 and 6, the spring piece moving cavity 3 may include an upper cover 6 and a bottom plate 7, where the upper cover 6 may include a cover plate 61, and a first circular arc partition plate 62 and a second circular arc partition plate 63 extending toward the bottom plate 7 on the cover plate 61, where the first circular arc partition plate 62 and the second circular arc partition plate 63 are concentric with each other, and have equal radians and aligned two ends, and the first end 41 (as shown in fig. 4) of the spring piece 4 is clamped in a first buckle 64 between the first circular arc partition plate 62 and the second circular arc partition plate 63, so that the first end 41 of the spring piece 4 is fixed; the bottom plate 7 may include a bottom plate body 71, where the bottom plate body 71 is provided with an annular groove 72, the annular groove 72 is matched with a space between the first circular arc partition plate 62 and the second circular arc partition plate 63, and after the upper cover 6 is covered on the bottom plate 7, a space enclosed by the annular groove 72, the first circular arc partition plate 62 and the second circular arc partition plate 63 forms a cavity of the spring piece moving cavity 3.

According to the invention, the spring piece moving cavity is divided into the upper cover and the bottom plate, the upper cover is arranged on the bottom plate to form a cavity for placing the spring piece, when the spring piece and/or the distribution sensing optical fibers on the spring piece are damaged, the spring piece can be taken out for replacement after the upper cover is taken down, and the spring piece moving cavity is not required to be replaced when the spring piece is replaced, so that the maintenance cost is reduced; in addition, the first arc baffle and the second arc baffle extend out of one side of the upper cover facing the bottom plate, and the two baffles are arc-shaped, so that a cavity formed by the two arc baffles on the upper cover and the annular groove on the bottom plate is arc-shaped.

As shown in fig. 5 to 8, the bottom plate body 71 extends upward to form an arc-shaped connection plate 73, and the arc-shaped connection plate 73 extends inward to form an arc-shaped baffle 74 parallel to the bottom plate body 71; the bottom plate body 71 is further provided with an arc through hole 75, the arc through hole 75 is positioned below the arc baffle 74, two ends of the arc through hole extend out of the position right below the arc baffle 74, and the arc connecting plate 73, the arc baffle 74, the arc through hole 75 and the second arc baffle 63 are concentric with a circular shaft; in the upper cover 6, the second circular arc partition 63 is located outside the first circular arc partition 62, and a third circular arc partition 65 extends outwards from one end of the second circular arc partition 63 towards the bottom plate 7; two ends of the outer edge of the third arc separator 65 respectively extend downwards to form a convex block 66; inserting the third circular arc baffle 65 between the circular arc baffle 74 and the bottom plate body 71, and inserting the protruding block 66 into the circular arc through hole 75, so as to implement the clamping of the upper cover 6 and the bottom plate 7, as shown in fig. 9; the cover plate 61, the circular arc baffle 74 and the bottom plate body 71 are respectively provided with a matched first through hole, and the fastening piece sequentially passes through the first through holes on the cover plate 61, the circular arc baffle 74 and the bottom plate body to fix the spring piece moving cavity 3 formed by the upper cover 6 and the bottom plate 7 on the object 5 to be fixed. According to the invention, the connecting mechanism between the upper cover and the bottom plate is designed, so that the upper cover can be conveniently and quickly clamped on the bottom plate, and corresponding through holes on the upper cover and the bottom plate are quickly aligned, so that a spring piece moving cavity formed by the upper cover and the bottom plate can be conveniently and quickly fixed on an object to be fixed by using a fastener, and the mounting efficiency of the spring piece moving cavity is improved.

In addition, the cover plate 61 and the base plate body 71 are provided with central through holes 8 for accommodating the claw gaskets 2, the central through holes 8 on the cover plate 61 are positioned at the inner side of the first circular arc partition plate 62, and the central through holes 8 on the base plate body 71 are positioned at the inner side of the annular groove 72. According to the invention, the central through holes enough for accommodating the claw gaskets are formed in the upper cover and the bottom plate, so that the rotation of the claw gaskets is not influenced by the movement cavity of the spring piece. As shown in fig. 7, the outer side edge of the annular groove 72 extends upward to form a circular baffle ring 76, after the upper cover 6 is clamped on the bottom plate 7, the first circular baffle plate 62 is located in the annular groove 72 and abuts against the inner side edge of the annular groove 72, and the second circular baffle plate 63 is located outside the circular baffle ring 76 and abuts against the circular baffle ring 76. According to the invention, the circular baffle ring extends upwards from the outer side groove edge of the annular groove, and the second circular arc baffle plate is positioned outside the circular baffle ring instead of in the annular groove, so that when the upper cover is clamped on the bottom plate, the two circular arc baffle plates in the upper cover are not required to be aligned with the annular groove, and therefore, the clamping efficiency between the upper cover and the bottom plate can be further improved, and the spring piece movement cavity installation efficiency is further improved.

As shown in fig. 10, the claw spacer 2 may include a spacer 21, fixing blocks 22 and a connecting portion 24, where the spacer 21 is provided with a second through hole 23 with a radius greater than or equal to the radius of the bolt 1, the spacer 21 extends upward to form a plurality of fixing blocks 22, each fixing block 22 is circumferentially and uniformly arranged outside the second through hole 23, and one of the fixing blocks 22 extends outward to form the connecting portion 24 for interfacing with the second end 42 (as shown in fig. 4) of the spring plate 4. The circumference of the fixing block 22 is concentric with the second through hole 23. As shown in fig. 11 and 12, the second through hole 23 is concentric with the second circular partition 63 in the spring moving cavity, and the connecting portion 24 extends to the inner side of the annular groove 72 at most, so as to avoid the rotation of the first nut and the claw gasket from being affected by the spring moving cavity.

In addition, one end of the distributed sensing optical fiber of the current thread structure can be connected with the next thread structure after penetrating out of the spring piece, and is distributed on the spring piece of the next thread structure, so that the loosening measurement of a plurality of thread structures can be realized by utilizing one distributed sensing optical fiber. As shown in fig. 13, the thread structure loosening universal measurement device based on distributed optical fiber sensing may further include a light source, a pulse modulator, a frequency shifter, an circulator, a coupler, a photoelectric detector, a data collector, a data processor, and optical fibers to be measured formed by connecting distributed sensing optical fibers in series in a plurality of thread structures, wherein an output end of the light source is respectively connected with the pulse modulator and the frequency shifter, an output end of the pulse modulator is connected with a first end of the circulator, a second end of the circulator is sequentially connected with one end of the optical fibers to be measured, a third end is connected with a first input end of the coupler, an output end of the frequency shifter is connected with a second input end of the coupler, and an output end of the coupler is sequentially connected with the data processor through the photoelectric detector and the data collector.

The light source divides continuous light into two paths of detection light and reference light, wherein the detection light is periodically injected into the optical fiber to be detected through the circulator according to a certain period, the optical fiber to be detected generates backward transmitted Brillouin scattering light after receiving the detection light, so that Brillouin frequency shift is generated, and the backward transmitted Brillouin scattering light is transmitted to the coupler through the circulator; the reference light is injected into the frequency shifter, and is transmitted to the circulator after frequency shift occurs through the frequency shifter; the Brillouin scattered light and the reference light after frequency shift interfere at the coupler to form an interference light signal; the photoelectric detector converts the interference optical signal into an interference electric signal; the data collector collects the interference electric signals and sends the collected interference electric signals to the data processor; and the data processor demodulates the change condition of the optical fiber to be detected according to the interference electric signal, and determines the loosening condition of each thread structure according to the change condition of each distributed sensing optical fiber in the optical fiber to be detected. When the corresponding change of the distributed sensing optical fiber in a certain thread structure exceeds a corresponding threshold value, an early warning can be sent out for loosening of the thread structure.

Other embodiments of the invention will be apparent to those skilled in the art from 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 following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It is to be understood that the invention is not limited to the precise arrangements and instrumentalities shown in the drawings, which have been described above, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the invention is to be governed only by the following claims.

Claims

1. The utility model provides a general measuring device of screw thread structure looseness based on distributed optical fiber sensing, its characterized in that includes screw thread structure, claw gasket, spring leaf motion chamber and the spring leaf of arranging in the spring leaf motion chamber, be equipped with distributed sensing optic fibre on the spring leaf, screw thread structure includes bolt and first nut, after the second end of bolt passes in proper order and waits to fix the thing and lie in the claw gasket on waiting to fix the thing upper surface, with the first nut threaded connection in this claw gasket, rotatory first nut makes the nut of bolt with wait the lower bottom surface butt of fix the thing, thereby realize waiting to fix the thing fastening;

2. The distributed fiber optic sensing based thread structure loosening universal measurement device of claim 1, wherein the first nut rotation comprises the following types of rotation:

3. The device for measuring the loosening of a thread structure based on distributed optical fiber sensing according to claim 1 or 2, wherein the determining the loosening of the thread structure according to the change condition of the distributed optical fiber comprises: judging whether the change of the distributed sensing optical fiber comprises a first change caused by the rotation of the first nut, if so, determining that the thread structure is loosened, otherwise, determining that the thread structure is not loosened.

4. The universal measuring device for thread structure looseness based on distributed optical fiber sensing according to claim 3, wherein when the universal measuring device for thread structure looseness is installed, the object to be fixed is fastened firstly, then the spring piece moving cavity is fixed on the object to be fixed, and then the second end of the spring piece in the spring piece moving cavity is connected with the claw gasket;

5. The device for measuring the looseness of a thread structure based on distributed optical fiber sensing, according to claim 1, wherein the spring piece is in a wave shape relative to the upper surface of the object to be fixed, and the distributed optical fiber sensing is distributed on the spring piece along the wave direction.

6. The universal measuring device for looseness of a thread structure based on distributed optical fiber sensing according to claim 1, wherein the spring piece moving cavity comprises an upper cover and a bottom plate, the upper cover comprises a cover plate and a first circular arc partition plate and a second circular arc partition plate which extend towards the bottom plate on the cover plate, the first circular arc partition plate and the second circular arc partition plate are concentric with a circular mandrel, radians are equal, two ends of the first circular arc partition plate and the second circular arc partition plate are aligned, and a first end of the spring piece is clamped in a first clamping buckle between the first circular arc partition plate and the second circular arc partition plate so that the first end of the spring piece is fixed;

7. The universal measuring device for thread structure looseness based on distributed optical fiber sensing of claim 6, wherein the base plate body extends upward out of an arc-shaped connecting plate, and the arc-shaped connecting plate extends inward out of an arc-shaped baffle plate parallel to the base plate body; the bottom plate body is also provided with an arc through hole, the arc through hole is positioned below the arc baffle, two ends of the arc through hole extend out of the position right below the arc baffle respectively, and the arc connecting plate, the arc baffle, the arc through hole and the second arc baffle are concentric with a circular mandrel;

8. The universal measuring device for thread structure looseness based on distributed optical fiber sensing of claim 6 or 7, wherein the cover plate and the bottom plate body are provided with central through holes for accommodating the claw gaskets, the central through holes on the cover plate are positioned on the inner side of the first circular arc partition plate, and the central through holes on the bottom plate body are positioned on the inner side of the annular groove;

9. The universal measuring device for loosening of thread structure based on distributed optical fiber sensing according to claim 1, wherein the claw gasket comprises a gasket, fixing blocks and a connecting portion, a second through hole with the radius larger than or equal to the radius of the bolt is formed in the gasket, the gasket extends upwards to form a plurality of fixing blocks, each fixing block is circumferentially and uniformly arranged outside the second through hole, and one fixing block extends outwards to form the connecting portion for being butted with the second end of the spring piece.

10. The universal measuring device for thread structure looseness based on distributed optical fiber sensing according to claim 1, wherein one end of the distributed sensing optical fiber of the current thread structure can be connected with the next thread structure after being penetrated out of the spring piece, and the distributed sensing optical fiber is distributed on the spring piece of the next thread structure, so that the looseness measurement of a plurality of thread structures can be realized by utilizing one distributed sensing optical fiber;