Optical fiber gasket structure for fastener looseness alarm

Abstract

The invention discloses an optical fiber gasket structure for fastener looseness alarm, and relates to a fastener looseness alarm device based on optical fiber strain measurement. The core of the device is that the deformation of a gasket arranged between a bolt and a connecting piece is accurately measured by using the fiber bragg grating, so that the pretightening force condition of the bolt is indirectly evaluated. A wavelength demodulator is used as an optical signal processing unit and is responsible for emitting an optical signal to the fiber bragg grating and receiving a reflected light beam, the strain condition of the gasket is analyzed by analyzing the change of the wavelength of the light beam, and then whether the bolt is loosened or not is judged. Once the pretightening force of the bolt is detected to be reduced below the preset threshold value, the device sends out an alarm signal. The high sensitivity of the fiber bragg grating is combined with the long-distance and anti-electromagnetic interference characteristics of optical fiber transmission, so that the accuracy of measurement and the stability of data transmission are ensured. Therefore, the fastener looseness alarm device provided by the invention is accurate in measurement and strong in anti-interference capability, and provides important guarantee for safe operation of mechanical equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical fastening monitoring, and specifically to a fastener loosening alarm device using the optical fiber strain measurement principle, which can monitor the fastening state of the fastener in real time, promptly discover and alarm the loosening of the fastener caused by vibration, fatigue and the like, and ensure the safe operation of the equipment. Background Art

[0002] During the operation of mechanical equipment, continuous vibration and dynamic loads pose a severe challenge to the stability of bolted connections. Bolt loosening prevention, that is, leaving appropriate looseness or taking specific loosening prevention measures when tightening bolts, is essential to ensure the stable connection of key vehicle components. In the vibration environment of mechanical equipment, bolts may gradually loosen due to repeated vibration shocks, which will not only affect the performance and safety of mechanical equipment, but may also cause damage or fall off of components, leading to serious accidents.

[0003] In the case of mechanical vibration environments, it is particularly important to adopt effective bolt loosening and anti-loosening strategies. These strategies include the use of locking washers, double nuts, wire anti-loosening devices, etc. to increase the friction and stability of bolt connections. However, the anti-loosening measures currently taken are mainly regular inspection and maintenance of bolt fasteners, which are necessary measures to ensure the safe operation of mechanical equipment. By regularly checking the tightening status and anti-loosening effect of the bolts, loose or damaged bolts can be discovered and handled in a timely manner, thereby preventing safety accidents caused by loose bolts. However, inspection and maintenance require the mechanical equipment to stop running, which reduces the working efficiency of the mechanical equipment. At the same time, if the fasteners suddenly loosen during operation, the mechanical equipment cannot alarm in time, and there are still major safety hazards.

[0004] Therefore, the present invention proposes a fastener loosening alarm device using optical fiber strain measurement, which can detect the connection status of bolt fasteners in real time during the operation of mechanical equipment. When the bolt fastener is loose, the optical fiber strain measurement system can measure the loosening of the bolt and issue an alarm signal in time. Using the technology of the present invention, it is possible to detect whether each bolt fastener is loose in real time online without stopping the mechanical equipment, thereby improving the safety of equipment movement. Summary of the invention

[0005] The object of the present invention is to provide an optical fiber gasket structure for fastener loosening alarm.

[0006] The technical solution to achieve the purpose of the present invention is: a structure of a fastener loosening alarm device using optical fiber strain measurement, which mainly includes a gasket, a protective shell, an optical fiber protection sleeve, a grating measuring head, an optical fiber, an optical fiber connector, a wavelength demodulator and an alarm device.

[0007] Furthermore, the gasket is a gasket used to be clamped in a bolt fastener, to protect the surface of a workpiece, to increase the force contact area, or to provide anti-loosening support elastic force.

[0008] Furthermore, the gasket is installed between the fastener and the fastened component to serve as a bearing base for the optical fiber sensor, and has a certain elasticity to respond to the tightness change of the fastener.

[0009] Furthermore, the gasket is made of metal; or, the gasket is made of non-metallic material, and as long as it is compressed in the bolt fastener, it does not affect the function of measuring the strain of the gasket.

[0010] Furthermore, the protective shell covers and protects the core components of the entire device, preventing the external environment from damaging sensitive components such as optical fibers, while having a certain sealing performance to cope with harsh working environments.

[0011] Furthermore, the optical fiber protection sleeve is placed in the protective shell to protect the optical fiber from mechanical damage and external environmental interference and ensure stable transmission of optical fiber signals. The grating measurement head and part of the optical fiber are placed inside the protective shell.

[0012] Furthermore, the grating measuring head, as the core component of the optical fiber sensor, is placed in the optical fiber protection sleeve, or fixed at a specific position of the gasket, and uses the sensitivity of the optical fiber grating to strain to measure the tiny deformation caused by loosening of the fastener in real time.

[0013] Furthermore, the optical fiber connects the grating measuring head and the optical fiber connector, and is responsible for transmitting the strain information captured by the grating measuring head to the wavelength demodulator in the form of an optical signal.

[0014] Furthermore, the optical fiber connector provides a stable connection interface between the optical fiber and the wavelength demodulator, ensuring reliable transmission of the optical signal.

[0015] Furthermore, the wavelength demodulator is used to transmit and receive optical signals transmitted by optical fibers, and convert them into corresponding strain values ​​or wavelength offsets, and determine whether the fastener is loose through a built-in algorithm. A data processing unit is integrated or placed separately in the wavelength demodulator for data processing and analysis.

[0016] Furthermore, when the wavelength demodulator detects that the fastener is loose and exceeds a preset threshold, the alarm device is triggered to emit an audible and visual alarm or send an alarm signal to a remote monitoring system.

[0017] Compared with the prior art, the present invention has the following significant advantages:

[0018] (1) The fiber grating strain measurement device designed in the present invention is mainly used to measure the strain of the gasket when the bolt fastener is in a compressed state. When the gasket is strained, it proves that the bolt fastener still generates a large preload and the bolt is not loose. Compared with the prior art, the preload state of the bolt fastener can be detected online in real time. When looseness occurs, the preload changes and the release device can send an alarm signal, thereby improving the accuracy and timeliness of monitoring.

[0019] (2) The present invention is designed with a gasket structure connected to the fiber Bragg grating, which uses optical fiber to transmit signals. Compared with the existing technology of transmitting electrical signals by wires, the signals transmitted by optical fiber have no electromagnetic radiation and will not be interfered by the surrounding electromagnetic radiation, thereby avoiding false alarm signals and ensuring the stability and reliability of monitoring data.

[0020] (3) The grating measuring head has high sensitivity and high resolution, and can accurately capture the tiny deformation caused by loosening of fasteners, so it has high detection accuracy. It is also suitable for various harsh working environments, such as high temperature, high humidity, strong vibration, etc., providing a strong guarantee for the safe operation of engineering equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic structural diagram of the optical fiber measurement relaxation alarm gasket provided by the present invention.

[0022] Figure 2 A schematic diagram of the structural decomposition of the optical fiber measurement relaxation alarm gasket provided by the present invention.

[0023] Among them, 1 is a gasket; 2 is a protective shell; 3 is an optical fiber protective sleeve; 4 is a grating measuring head; 5 is an optical fiber; 6 is an optical fiber connector; 7 is a wavelength demodulator; and 8 is an alarm device. DETAILED DESCRIPTION

[0024] The present invention provides a fastener loosening alarm device structure using optical fiber strain measurement, the principle of which is to use a grating measuring head to accurately measure the tiny deformation of the gasket, thereby indirectly judging the preload state of the bolt, thereby achieving real-time monitoring and early warning of the bolt loosening. The core components of the system include a gasket with an integrated grating measuring head, an optical fiber transmission line, a wavelength demodulator, and an alarm device.

[0025] The grating measuring head is embedded in or close to the surface of the gasket. When the bolt is properly tightened, the gasket will be subjected to pressure from the bolt and the connector, resulting in a certain deformation. This deformation will cause a slight change in the physical structure inside the fiber grating, thereby affecting the specific wavelength of the reflected light. The wavelength demodulator transmits a light signal to the grating measuring head and receives the light signal reflected back. By analyzing the change in the wavelength of the reflected light through an algorithm, the demodulator can calculate the deformation of the gasket, which directly reflects the current preload state of the bolt.

[0026] When the bolt is in normal working condition, the bolt maintains sufficient preload, the pressure on the gasket is stable, and the deformation detected by the grating measuring head is maintained within a certain range. However, once the preload of the bolt gradually decreases due to factors such as vibration, temperature change or material fatigue, the pressure on the gasket will also decrease, causing its deformation to decrease. This process is quickly captured by the grating measuring head and converted into a wavelength change of the optical signal and transmitted to the wavelength demodulator. When the wavelength demodulator analyzes that the deformation of the gasket is significantly reduced and is lower than the preset safety threshold, the alarm mechanism is triggered immediately.

[0027] The gasket is installed between the bolt and the connector, and its design needs to consider compatibility with the fiber grating measuring head to ensure that the grating measuring head can accurately measure the deformation of the gasket. The gasket material can be selected according to the specific application, such as metal, alloy, plastic or high-performance composite material to ensure sufficient strength and durability.

[0028] The optical fiber protection sleeve is made of high-strength, corrosion-resistant materials, which effectively protects the optical fiber from damage by the external environment. The grating measuring head is placed in the optical fiber protection sleeve, and can be tightly bonded to the optical fiber protection sleeve by a special adhesive. The optical fiber protection sleeve is tightly attached to the surface of the gasket, and can be bonded or welded to ensure that the slight deformation of the gasket can be accurately reflected. The slight deformation is transmitted to the grating measuring head, thereby causing slight deformation of the grating measuring head.

[0029] After the grating measuring head is slightly deformed, the wavelength of the optical signal transmitted from the optical fiber changes during reflection, which can be detected by the wavelength demodulator. The optical fiber is led out from the grating measuring head, passes through the optical fiber protection sleeve, and finally connected to the optical fiber connector for long-distance transmission of optical signals.

[0030] The protective shell is designed to wrap the entire fiber grating measuring head, the fiber protection sleeve and part of the optical fiber structure, and is made of waterproof and impact-resistant materials to ensure that the device can work stably for a long time in harsh environments. The protective shell is installed in the appropriate position of the gasket by bonding, welding or other fixing methods.

[0031] The wavelength demodulator is connected to the optical fiber through an optical fiber connector, and is responsible for sending optical signals to the grating measuring head and receiving the reflected optical signals. The demodulator has a built-in high-precision signal processing algorithm, and a data processing unit is integrated or placed separately inside for data processing and analysis. It can analyze the wavelength change caused by the gasket deformation of the grating measuring head in real time, so as to calculate the preload state of the bolt. Once the preload is detected to be lower than the set threshold, it is considered that the bolt is loose, and the demodulator immediately sends a signal to the alarm device.

[0032] The wavelength demodulator has a temperature compensation system inside, which can adjust the parameters accordingly with the change of temperature. Alternatively, the wavelength demodulator is connected to an external temperature compensation optical fiber to detect the temperature change of the measured object and adjust the parameters.

[0033] The fastener loosening alarm device may further include a data processing unit for receiving the output signal of the wavelength demodulator and performing further data processing and analysis to improve the accuracy and reliability of the alarm.

[0034] After receiving the signal from the demodulator, the alarm device immediately starts the alarm program and warns the operator through sound, light flash, display screen or remote communication. At the same time, the alarm device can record the alarm time, location and other information to remind the operator to take timely measures to tighten or replace the bolts to prevent structural failure or safety accidents caused by loose bolts.

[0035] The present invention is described in detail below with reference to the accompanying drawings and embodiments. Example

[0036] The optical fiber gasket structure for fastener loosening alarm proposed by the present invention is as follows Figure 1 As shown in the figure, the gasket 1 is installed between the bolt and the connector as the measurement object. When used without being installed, the gasket 1 is not deformed, and the grating measuring head 4 does not measure the deformation of the gasket 1, indicating that the gasket 1 is not under stress at this time. After the bolt is tightened, the gasket 1 is subjected to a large pre-tightening pressure and produces a slight deformation. The grating measuring head 4 can accurately measure the slight deformation of the gasket 1. If the gasket 1 is deformed, it indicates that the gasket 1 has been subjected to a large pressure, and the bolt fastener has a large pre-tightening force. If the deformation of the gasket 1 is reduced, it means that the pre-tightening force of the bolt fastener is reduced, and the bolt may be loose. Therefore, the pre-tightening state of the bolt fastener can be judged by the deformation of the gasket 1.

[0037] like Figure 2The grating measuring head 4 shown in the figure is placed in the optical fiber protection sleeve 3. The optical fiber protection sleeve 3 is a hollow structure, and the grating measuring head 4 and part of the optical fiber 5 are inserted into the optical fiber protection sleeve 3. The optical fiber protection sleeve 3 is potted with high-strength glue to fix the grating measuring head 4 and part of the optical fiber 5, and enhance the overall rigidity, protect the grating measuring head 4 and the optical fiber 5 from external physical damage and chemical corrosion, and accurately transmit the deformation state of the gasket 1. The optical fiber protection sleeve 3 is tightly attached to the surface of the gasket 1, and can be bonded or welded to ensure that the slight deformation of the gasket 1 can be accurately reflected.

[0038] like Figure 2 The protective shell 2 shown in the figure is located at the outermost layer of the gasket 1 and is made of a strong and durable material, which protects the optical fiber protective sleeve 3, the grating measuring head 4 and part of the optical fiber 5, ensuring that the device can work stably for a long time in a harsh environment. The optical fiber 5 connects the grating measuring head 4 and the wavelength demodulator 7 to achieve stable transmission of optical signals. The outer skin of the optical fiber 5 is made of a strong and durable material, which has the characteristics of anti-electromagnetic interference and corrosion resistance, and is suitable for harsh environments and complex electromagnetic environments.

[0039] like Figure 2 One end of the optical fiber 5 shown in the figure is connected to the grating measuring head 4, and the other end is connected to the optical fiber connector 6. The optical fiber connector 6 is a quick plug-in mechanism that can easily and quickly connect the optical fiber 5 to an instrument such as a wavelength demodulator 7. The wavelength demodulator 7 is used to transmit and receive optical signals, analyze the wavelength change of the optical fiber grating caused by the deformation of the gasket 1, and when the deformation of the gasket 1 decreases, it is considered that the preload force of the bolt is reduced, and looseness may occur. A data processing unit is integrated or placed separately in the wavelength demodulator 7 for data processing and analysis. There is a temperature compensation unit inside or outside the wavelength demodulator 7, which changes the detection parameters as the temperature changes. When it is detected that the bolt preload force is lower than the preset threshold (that is, it is judged that the bolt is loose), the wavelength demodulator 7 sends an alarm message to the alarm device 8. The alarm device 8 will immediately send out an alarm signal in various forms such as sound, light, display screen, or remote communication.

[0040] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A fiber optic gasket structure design for fastener loosening alarm, a fastener loosening alarm device based on fiber optic strain measurement, Features It comprises a gasket (1), a protective shell (2), an optical fiber protective sleeve (3), a grating measuring head (4), an optical fiber (5), an optical fiber connector (6), a wavelength demodulator (7), and an alarm device (8).

2. The gasket according to claim 1 is installed between a bolt and a connecting piece, or between a nut and a connecting piece, or between other fasteners, as a measurement object to sense changes in the preload force of the bolt.

3. The grating measuring head according to claim 1 is directly attached to the surface of the gasket to measure the strain of the gasket caused by the change of the bolt preload; or it is placed in the optical fiber protection sleeve by glue or compression fastening, and the deformation of the gasket can be transmitted to the optical fiber protection sleeve, and then to the grating measuring head.

4. The optical fiber protection sleeve according to claim 1 is fixed to the gasket by at least one fixing method (such as gluing or welding) to ensure accurate measurement of the strain of the gasket. The internal glue potting material has high strength, corrosion resistance, and anti-aging properties to provide long-term protection.

5. The optical fiber protection sleeve according to claim 1 can be an integrated structure with the grating measuring head. When a specially made optical fiber protection sleeve is not used, the grating measuring head can also be directly pasted to a suitable position on the gasket.

6. The optical fiber according to claim 1 is connected to the grating measurement head and the wavelength demodulator to realize the long-distance transmission of optical signals and has the ability to resist electromagnetic interference.

7. The protective shell according to claim 1 is located at the outermost layer, surrounds and protects the grating measuring head, the optical fiber protection ring and the optical fiber connection part, and ensures that the device can work stably for a long time in a harsh environment.

8. The wavelength demodulator according to claim 1 is used to transmit an optical signal to the grating measuring head, receive the reflected optical signal, analyze the wavelength change of the fiber grating caused by the gasket deformation, and thus determine the preload state of the bolt. A data processing unit is integrated or placed separately inside the demodulator to receive the output signal of the wavelength demodulator and perform further data processing and analysis to improve the accuracy and reliability of the alarm.

9. The wavelength interrogator according to claim 1 has a temperature compensation system inside, which can adjust the parameters accordingly with the change of temperature. Or the wavelength interrogator is connected to an external temperature compensation optical fiber to detect the temperature change of the measured object and adjust the parameters.

10. The alarm device according to claim 1 is connected to the wavelength demodulator, and sends out an alarm signal when it is detected that the bolt preload is lower than a preset threshold value, that is, the bolt is loose, according to the analysis result of the wavelength demodulator.

11. The fastener loosening alarm device according to claim 1, It is characterized in that The fitting mode of the grating measuring head and the gasket enables it to sensitively capture the minute strain of the gasket caused by the change of the bolt pre-tightening force.

12. The fastener loosening alarm device according to claim 1, It is characterized in that The alarm device can emit alarm signals in various forms such as sound, light, display screen or remote communication to meet the usage requirements in different occasions.

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