An online monitoring and early warning system for bolt tightening degree and a detection method

Abstract

The present invention discloses an on-line monitoring and early warning system for bolt fastening degree and a detection method, belonging to the technical field of bolt fastening degree detection. The on-line monitoring and early warning system for bolt fastening degree includes an upper magnetic ring assembly, a lower magnetic ring assembly, a Hall sensing probe, a communication bus, a data acquisition module, a data communication module and on-line monitoring and early warning software for bolt fastening degree; the upper magnetic ring assembly is used to provide a magnetic field for the bolt, and the lower magnetic ring assembly is used to provide a magnetic field for the nut; the Hall sensing probe is used to detect the change in magnetic flux acting on the Hall sensor by the upper magnetic ring assembly and the lower magnetic ring assembly, and convert the collected change data of magnetic flux into bolt loosening angle data; the Hall sensing probe is connected to the data acquisition module through the communication bus. The present invention provides an on-line monitoring and early warning system for bolt fastening degree and a detection method, which can automatically monitor the bolt fastening degree with high monitoring accuracy and small error.

Description

Technical Field

[0001] The present invention relates to an on-line monitoring and early warning system and detection method for bolt tightening degree, belonging to the technical field of bolt tightening degree detection. Background Art

[0002] At present, in large-scale steel structure building fields such as wind power, hydropower stations, dams, nuclear power plants, bridges, cranes, airports, stations, stadiums, etc., bolts are usually used to achieve fixed connections between various structural components. However, during long-term use, bolts will loosen, resulting in insufficient firmness of the connection between structural components.

[0003] In the prior art, piezoelectric sensing technology, strain sensing technology, acceleration sensing technology, ultrasonic sensing technology, etc. are usually used to detect the tightening degree of bolts.

[0004] Piezoelectric sensing technology: mainly based on the piezoelectric effect, when a screw is subjected to external forces (such as vibration, impact or loosening), mechanical strain will be generated. This mechanical strain acts on the piezoelectric material, and the piezoelectric material will thus undergo polarization, that is, electric charges are generated on its surface. In this process, mechanical energy is converted into electrical energy to form an electrical signal. This electrical signal can be monitored and measured. By analyzing the characteristics of the electrical signal such as frequency and amplitude, the tightening state of the screw can be inferred. If the screw loosens, the generated mechanical strain and the corresponding electrical signal characteristics will also change, so the loosening of the screw can be detected by monitoring the electrical signal.

[0005] The piezoelectric sensing technology has the following defects:

[0006] 1. Unstable frequency response, piezoelectric sensors have defects in measuring low-frequency vibrations and acoustic signals. Due to small mechanical damping, it is not easy to be stable during low-frequency measurement, and amplitude harmonic distortion is likely to occur.

[0007] 2. Susceptible to temperature influence, the sensitivity of piezoelectric materials is greatly affected by temperature, and it is more serious at high temperatures. Temperature changes will cause changes in the length or cross-sectional area of the material, thereby affecting its electrical properties and resulting in unstable output signals.

[0008] 3. Not suitable for low-frequency measurement, due to small mechanical damping of piezoelectric materials, piezoelectric sensors have low response sensitivity to low-frequency signals, so they are not applicable in low-frequency signal measurement.

[0009] 4. Photoelectromechanical interference, the working principle of piezoelectric generators is similar to the photoelectromechanical effect. When there is strong light interference near the sensor, an error signal will be generated, and special attention needs to be paid to the surrounding environmental light during installation.

[0010] 5. Long-term stability issue: The key parameters of piezoelectric sensing depend on the polarization state of piezoelectric materials. Under long-term electromechanical coupling, piezoelectric materials may age and fatigue, resulting in performance degradation and affecting the long-term operation reliability.

[0011] Strain sensing technology: Based on the strain effect, when a screw is subjected to external forces (such as tension, compression, bending, etc.), it will undergo minute deformations, which are called strains. A strain sensor senses this minute deformation and converts it into an electrical signal or other measurable physical quantity, thereby realizing the monitoring of the loosening or stress state of the screw. When the screw loosens, the stress distribution it experiences changes, causing the output signal of the strain sensor to also change. By analyzing this signal change, the loosening problem of the screw can be detected in a timely manner, and corresponding measures can be taken for tightening or repair to ensure the safe and stable operation of the equipment.

[0012] The strain sensor technology has the following defects:

[0013] 1. Nonlinearity problem: Under large strain states, strain sensors, especially semiconductor strain gauges, will exhibit obvious nonlinearity, which may affect the measurement accuracy.

[0014] 2. Weak output signal: The output signal of a strain sensor is usually relatively weak and has poor anti-interference ability. Extra shielding measures need to be taken to ensure the stable transmission of the signal.

[0015] 3. Measurement limitation: A strain sensor can only measure the average strain at a point or within the strain gauge range and cannot fully reflect the stress gradient change in the stress field, which can easily lead to misjudgment of the screw loosening state.

[0016] 4. Installation and protection requirements: The strain gauge needs to be installed on-site and requires a protective layer and adhesives, which not only increases the installation complexity but may also affect the strength and dynamic characteristics of the object under test.

[0017] 5. Influence of environmental factors: The measurement of a strain sensor is easily affected by environmental factors such as temperature and humidity, resulting in measurement errors.

[0018] Acceleration sensing technology: It mainly judges the tightening state of the screw by measuring the acceleration change generated when the screw is subjected to external forces. An acceleration sensor usually contains a mass block and a spring system inside. When the screw is subjected to vibration or impact, the mass block will displace due to inertia, causing the spring system to deform. This deformation will be captured by the detection elements (such as capacitor plates) inside the sensor and converted into an electrical signal for output. By monitoring the change of this electrical signal, the loosening situation of the screw can be inferred.

[0019] The acceleration sensing technology has the following defects:

[0020] 1. Limited discrimination ability: The acceleration sensor has difficulty in distinguishing vibrations caused by screw loosening from those caused by other factors (such as gravitational acceleration, environmental vibrations, etc.), which may lead to false alarms or missed alarms.

[0021] 2. Signal noise impact: In a short period of time, due to the presence of signal noise, the measurement of the acceleration sensor may generate errors, affecting the accurate judgment of the screw loosening state.

[0022] 3. Drift phenomenon: The acceleration sensor may exhibit a drift phenomenon during long-term use, resulting in the gradual accumulation of measurement errors. Regular calibration is required to maintain the measurement accuracy.

[0023] 4. Application limitations: Although the acceleration sensor has high precision and can respond quickly in a moving state, its long-term measurement stability is limited. It is more suitable for monitoring the attitude changes in short-term and dynamic situations, and may not be ideal for long-term and static screw loosening monitoring.

[0024] Ultrasonic sensing technology: It is mainly based on the propagation and reflection characteristics of ultrasonic waves. Ultrasonic waves are mechanical waves with characteristics such as high frequency, short wavelength, and good directivity. When ultrasonic waves propagate in a material, they will encounter different interfaces or obstacles, such as the loosened part of the screw, resulting in reflection, refraction, and transmission phenomena. Reflection and measurement: Use an ultrasonic sensor to emit ultrasonic waves and irradiate them onto the screw. When the screw is in a tightened state, the ultrasonic waves will pass through smoothly and be received at the receiver. Once the screw becomes loose, its interface will change, causing changes in the propagation path and reflection characteristics of the ultrasonic waves. By measuring these changes, such as the intensity of the reflected wave, time delay, etc., the loosening situation of the screw can be inferred. The received ultrasonic signal will be processed by a signal processor to extract information related to screw loosening, such as wave frequency, amplitude, and time interval. These information will be further analyzed to determine the axial force state or loosening degree of the screw.

[0025] The ultrasonic sensing technology has the following defects:

[0026] 1. High equipment cost: Ultrasonic measurement equipment is usually expensive, especially high-precision and multi-functional systems. For large-scale bolt monitoring, the cost is a significant consideration.

[0027] 2. Limited measurement accuracy: Multiple factors such as the uniformity, surface condition, and diameter of the bolt material will affect the measurement accuracy. The change in sound velocity caused by the acoustoelastic effect is weak, requiring the measurement system to have very high accuracy.

[0028] 3. Complex installation operation: The ultrasonic sensor needs to be precisely installed on the bolt, and limited space or hard-to-reach positions will increase the installation and operation difficulties.

[0029] 4. Influence of environmental factors: Environmental factors such as temperature changes, humidity, and vibration are likely to cause deviations in measurement results.

[0030] 5. Potential damage to the bolt: Under the action of high temperature and high stress, the bolt may develop cracks due to thermal brittleness, creep, fatigue, and stress corrosion.

[0031] 6. Detection distance and azimuth limitations: The ultrasonic sensing technology has a relatively slow ranging speed and a certain diffusion angle. It can only measure the distance and cannot accurately measure the azimuth. There is a minimum detection distance limitation, and the sensor cannot effectively detect when the distance is less than this value. Summary of the Invention

[0032] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an on-line monitoring and early warning system and detection method for bolt tightening degree, which can automatically monitor the bolt tightening degree with high monitoring accuracy and small error.

[0033] To solve the above technical problems, the technical solution of the present invention is:

[0034] On the one hand, the present invention provides an on-line monitoring and early warning system for bolt tightening degree, which includes an upper magnetic ring assembly, a lower magnetic ring assembly, a Hall sensing probe, a communication bus, a data acquisition module, a data communication module, and an on-line monitoring and early warning software for bolt tightening degree;

[0035] The upper magnetic ring assembly is used to provide a magnetic field for the bolt, and the lower magnetic ring assembly is used to provide a magnetic field for the nut;

[0036] The Hall sensing probe is used to detect the change in magnetic flux acting on the Hall sensor by the upper magnetic ring assembly and the lower magnetic ring assembly, and convert the collected change data of the magnetic flux into bolt loosening angle data;

[0037] The Hall sensing probe is connected to the data acquisition module through the communication bus. The data acquisition module is used to collect the bolt loosening angle data output by the Hall sensing probe and encode it, and send the encoded bolt loosening angle data information to the data communication module;

[0038] The data communication module is used to transmit the bolt status data information sent by the data acquisition module to the upper computer;

[0039] The on-line monitoring and early warning software for bolt tightening degree is set in the upper computer. The on-line monitoring and early warning software for bolt tightening degree is used to receive the bolt loosening angle data information sent by the data acquisition module, and analyze and judge the bolt status data information to identify whether the bolt shows signs of loosening.

[0040] Further, the upper magnetic ring assembly includes an upper magnetic ring, and a plurality of upper magnets are arranged inside the upper magnetic ring; the lower magnetic ring assembly includes a lower magnetic ring, and a plurality of lower magnets are arranged inside the lower magnetic ring.

[0041] Further, the Hall sensing probe includes a probe housing and a probe circuit board;

[0042] A plurality of side wall magnets are arranged on the inner cavity side wall of the probe housing, and the side wall magnets are adsorbed on the side wall of the nut; a plurality of upper surface magnets are arranged in the inner cavity of the probe housing, and the upper surface magnets are adsorbed on the end surface of the nut;

[0043] An upper Hall sensor for sensing the magnetic field generated by the upper magnetic ring assembly is arranged at the top of the probe housing;

[0044] The probe circuit board is arranged at the bottom of the probe housing, and a lower Hall sensor for sensing the magnetic field generated by the lower magnetic ring assembly is arranged on the probe circuit board;

[0045] Both the upper Hall sensor and the lower Hall sensor are electrically connected to the probe circuit board, and the probe circuit board is electrically connected to the data acquisition module.

[0046] Further, a soft magnetic material is arranged on the side of the side wall magnet away from the side wall of the nut, and a soft magnetic material is arranged on the side of the upper surface magnet away from the end surface of the nut.

[0047] On the other hand, the present invention provides a detection method for an on-line monitoring and warning system for the bolt tightening degree, which includes the following steps:

[0048] Step S1, establish a magnetic field coordinate system;

[0049] Step S2, collect magnetic field data through the Hall sensing probe;

[0050] Step S3, calculate the positions of the nut and the bolt within a quarter cycle according to the magnetic field data;

[0051] Step S4, determine the zero position of the nut;

[0052] Step S5, combine the nut zero position information to determine the positions of the nut and the bolt within the remaining three quarters of the cycle;

[0053] Step S6, perform bolt loosening discrimination;

[0054] Step S7, give an alarm when the bolt is loose.

[0055] Further, in step S1, to establish a magnetic field coordinate system, it specifically includes the following steps:

[0056] The axial direction of the bolt is denoted as the z-axis;

[0057] A z-axis magnetic field component with a sinusoidal distribution or a sawtooth distribution around the z-axis is generated by the upper magnetic ring assembly and the lower magnetic ring assembly;

[0058] The position of a point on the circular ring around the z-axis can be calculated by measuring the distribution of the z-axis magnetic field near any point.

[0059] Furthermore, in the step S3, calculating the positions of the nut and the bolt within a quarter cycle according to the magnetic field data specifically includes the following steps:

[0060] For the z-axis magnetic field component with a sinusoidal magnetic field distribution, upper Hall sensors and lower Hall sensors are arranged at intervals of λ / 4 on the circumference with the z-axis as the center, where λ is the spatial wavelength of the sinusoidal magnetic field;

[0061] Denote the magnetic field value measured by the upper Hall sensor as V1, and the magnetic field value measured by the lower Hall sensor as V2. When V1 and V2 are in the sinusoidal magnetic field, calculate the angle D at the position of V1:

[0062]

[0063] The angle D at the position of V1 is the position of the nut and the bolt within a quarter cycle;

[0064] For the z-axis magnetic field component with a sawtooth magnetic field distribution, upper Hall sensors and lower Hall sensors are arranged at intervals of L on the circumference with the z-axis as the center, where L = θR, R is the radius of the circle where the Hall sensors are located, and θ is the interval angle between the two Hall sensors;

[0065] Denote the magnetic field value measured by the upper Hall sensor as V1, and the magnetic field value measured by the lower Hall sensor as V2. When V1 and V2 are in the sawtooth magnetic field, calculate the angle D at the midpoint position of V1 and V2:

[0066]

[0067] The angle D at the midpoint position of V1 and V2 is the position of the nut and the bolt within a quarter cycle.

[0068] Furthermore, in the step S4, determining the zero position of the nut specifically includes the following steps:

[0069] After the Hall sensing probe is installed and powered on for the first time, the angles of the nut and the bolt are measured at fixed intervals, and the last m measurement values are recorded;

[0070] Denote as the zero position of the nut, and take D i= D - D0 is the angular position of the nut in the i-th measurement.

[0071] Further, in the step S5, in combination with the zero position information of the nut, the positions of the nut and the bolt in the remaining three-quarters of the cycle are determined, which specifically includes the following steps:

[0072] Judge the quadrant where the nut is located according to the positive and negative of V1 and V2;

[0073] Call the conversion function of the corresponding quadrant;

[0074] Use the zero position information to convert the angles of the nut and the bolt to the range of -90° to 270°.

[0075] Further, in the step S6, bolt loosening discrimination is performed, which specifically includes the following steps:

[0076] Formulate a bolt loosening angle criterion D s , when the angular position of the nut in the i-th measurement satisfies |D i - D0| ≥ D s , it is determined that the bolt is loose.

[0077] Adopting the above technical solutions, the present invention has the following beneficial effects:

[0078] 1. The lower magnetic ring and the Hall sensing probe of the present invention are fixed by magnetic attraction, and the installation and disassembly are very simple.

[0079] 2. The lower magnetic ring, the Hall sensing probe, the upper magnetic ring, etc. of the present invention do not need to transform the bolt, nut and gasket, and do not affect the strength of the existing bolt.

[0080] 3. The Hall sensor probes of the present invention are connected in series in pairs through a data cable, which is simple to install and eliminates the risk of circuit confusion, and has higher reliability.

[0081] 4. Compared with the prior art, the bolt tightening degree detection method of the present invention has higher monitoring accuracy and smaller error.

[0082] 5. The present invention can greatly improve the bolt loosening detection rate. Description of the Drawings

[0083] Figure 1 is the principle block diagram of the on-line monitoring and early warning system for bolt tightening degree of the present invention;

[0084] Figure 2 is the structural schematic diagram of the upper magnetic ring of the present invention;

[0085] Figure 3 is the structural schematic diagram of the lower magnetic ring of the present invention;

[0086] Figure 4Schematic cross-sectional structure diagram of the Hall sensing probe of the present invention;

[0087] Figure 5 Schematic dorsal structure diagram of the Hall sensing probe of the present invention;

[0088] Figure 6 Installation position diagram of the Hall sensing probe, upper magnetic ring and lower magnetic ring of the present invention;

[0089] Figure 7 Flow chart of the detection method of the on-line monitoring and early warning system for bolt tightening degree of the present invention. Detailed implementation manners

[0090] In order to make the content of the present invention easier to be clearly understood, the present invention will be further described in detail below according to specific embodiments in conjunction with the accompanying drawings.

[0091] Embodiment 1

[0092] As Figure 1 shown, this embodiment provides an on-line monitoring and early warning system for bolt tightening degree, which includes an upper magnetic ring assembly, a lower magnetic ring assembly, a Hall sensing probe, a communication bus, a data acquisition module, a data communication module and an on-line monitoring and early warning software for bolt tightening degree.

[0093] The upper magnetic ring assembly is used to provide a magnetic field for the bolt, and the lower magnetic ring assembly is used to provide a magnetic field for the nut.

[0094] The Hall sensing probe is used to detect the change in magnetic flux acting on the Hall sensor by the upper magnetic ring assembly and the lower magnetic ring assembly, and convert the collected change data of the magnetic flux into bolt loosening angle data.

[0095] The Hall sensing probe is connected to the data acquisition module through the communication bus. The data acquisition module is used to collect the bolt loosening angle data output by the Hall sensing probe and encode it, and send the encoded bolt loosening angle data information to the data communication module.

[0096] The data communication module is used to transmit the bolt status data information sent by the data acquisition module to the upper computer.

[0097] The on-line monitoring and early warning software for bolt tightening degree is set in the upper computer. The on-line monitoring and early warning software for bolt tightening degree is used to receive the bolt loosening angle data information sent by the data acquisition module, and analyze and judge the bolt status data information to identify whether the bolt shows signs of loosening.

[0098] This system can achieve online monitoring and early warning of the tightening state of installed rotary bolts. The monitoring parameter is the rotational displacement of the bolt and nut. When the bolt becomes loose, the magnetic flux acting on the Hall sensor will change. The Hall sensing probe converts the collected magnetic flux change data into bolt loosening angle data according to the built-in algorithm. The bolt loosening data is transmitted to the data acquisition module through the communication bus, and after being summarized and encoded, it is transmitted to the upper computer through the data communication module. The monitoring and early warning software infers the loosening situation of the nut and bolt according to the detection algorithm. Once it is determined that the bolt has abnormal conditions such as loosening, the online monitoring and early warning software for bolt tightening degree will immediately send a warning signal to the operation and maintenance personnel to ensure that the problem can be handled in a timely manner, eliminate potential safety hazards, and avoid accidents such as the deterioration of bolt loosening into collapse.

[0099] As Figure 2 、 6 shown, the upper magnetic ring assembly of this embodiment includes an upper magnetic ring 1. A plurality of upper magnetic ring mounting grooves 11 are arranged in the upper magnetic ring 1 according to a certain rule. An upper magnet is installed in each upper magnetic ring mounting groove 11. The upper magnet can be a rectangular or sector-shaped strong magnet. The upper magnet can generate a periodic and regular magnetic field. The upper magnetic ring 1 is fixed on the top of the bolt 101. There is a friction interface material on the threaded contact surface, which can ensure that the upper magnetic ring 1 will not have relative displacement with the bolt even under strong vibration conditions. According to different bolt specifications, different sizes of the upper magnetic ring 1 can be customized to adapt to different bolt diameters and heights.

[0100] As Figure 3 、 6 shown, the lower magnetic ring assembly of this embodiment includes a lower magnetic ring 2. A plurality of lower magnetic ring mounting grooves 21 are arranged in the lower magnetic ring 2 according to a certain rule. A lower magnet is installed in each lower magnetic ring mounting groove 21. The lower magnet can be a rectangular or sector-shaped strong magnet. The lower magnet can generate a periodic and regular magnetic field. As Figure 6 shown, at the same time, the lower magnetic ring 2 can be tightly adsorbed on the flange surface 100 where the bolt 101 is installed. There is a friction interface material on the surface of the lower magnetic ring 2 in contact with the flange surface 100, which can ensure that the lower magnetic ring 2 will not have relative displacement with the flange surface 100 even under strong vibration conditions. According to different bolt and gasket specifications, different sizes of the lower magnetic ring 2 can be customized to adapt to different sizes of bolts and gaskets.

[0101] As Figure 4 、 5 、6 shown, the Hall sensing probe of this embodiment includes a probe housing 3 and a probe circuit board 4.

[0102] On the inner cavity side wall of the probe housing 3, a plurality of side wall magnets 8 are arranged, and the side wall magnets 8 are adsorbed on the side wall of the nut 102; in the inner cavity of the probe housing 3, a plurality of upper surface magnets 9 are arranged, and the upper surface magnets 9 are adsorbed on the end surface of the nut 102.

[0103] At the top of the probe housing 3, an upper Hall sensor 6 is provided for sensing the magnetic field generated by the upper magnetic ring assembly.

[0104] The probe circuit board 4 is arranged at the bottom of the probe housing 3, and a lower Hall sensor 5 for sensing the magnetic field generated by the lower magnetic ring assembly is arranged on the probe circuit board 4.

[0105] Both the upper Hall sensor 6 and the lower Hall sensor 5 are electrically connected to the probe circuit board 4, and the probe circuit board 4 is electrically connected to the data acquisition module.

[0106] The Hall sensing probe determines the loosening condition of the bolt 101 by detecting the magnetic fields generated by the upper magnetic ring 1 and the lower magnetic ring 2. Two groups of magnets are installed inside the probe, namely the side wall magnet 8 and the upper surface magnet 9. The two groups of magnets enable the Hall sensing probe to be firmly connected to the nut 102 and achieve reliable positioning. There is a friction interface material on the contact surface between the Hall sensing probe and the nut 102, which can ensure that the Hall sensing probe will not have relative displacement with the nut 102 even under strong vibration conditions. As Figure 4 、 5 shown, two groups of Hall sensors are arranged on the Hall sensing probe, located at the top and bottom of the Hall sensing probe respectively, for sensing the magnetic fields generated by the upper and lower magnetic rings 2. There is a probe circuit board 4 on the Hall sensing probe. The sensor circuit on the circuit board can collect the signals of the two groups of Hall sensors and use a customized algorithm to achieve high-precision identification of the loosening angles of the bolt 101 (corresponding to the upper magnetic ring magnetic field) and the nut 102 (corresponding to the lower magnetic ring 2 magnetic field). The circuit also has a logic judgment function. According to certain criteria, the loosening angles of the bolt 101 and the nut 102 can give the loosening grade of the bolt and nut. Two LED indicators 7 are provided on the Hall sensing probe, corresponding to the states of the bolt 101 and the nut 102 respectively. When the bolt 101 and the nut 102 are loose, the corresponding LED indicator 7 shows the corresponding color according to the loosening grade of the bolt and nut.

[0107] As Figure 4 、 5 shown, on one side of the side wall magnet 8 of the present embodiment away from the side wall of the nut 102, a soft magnetic material 10 is provided, and on one side of the upper surface magnet 9 away from the end face of the nut 102, a soft magnetic material 10 is provided. The soft magnetic material 10 can make the fixing of the Hall sensing probe on the nut 102 stronger. In addition, the soft magnetic material 10 also plays a role in eliminating the influence of the two groups of magnets on the probe on the Hall sensor.

[0108] As Figure 1As shown in the figure, the communication bus in this embodiment adopts CAN or 485, and has functions of transmitting data, power supply, electromagnetic shielding, and IP67 waterproofing. The communication bus connects the probes in pairs, and all the probes are connected in series in the way of A connecting to B, B connecting to C, and C connecting to D, and finally connected to the data acquisition module. This connection method is equivalent to a single bus in series, avoiding the risk of confusion caused by arranging a large number of wires in the deployment area.

[0109] As Figure 1 shown in the figure, the data acquisition module in this embodiment is a module that acquires bolt loosening data, encodes and transmits the data. There are multiple communication buses on the data acquisition module, and each communication bus can connect hundreds of Hall sensing probes. One data acquisition module can complete the acquisition of data from hundreds of Hall sensing probes. The data acquisition module can perform two-way data transmission, and send the instructions, configuration information, etc. sent by the upper computer or cloud server to a certain probe in a targeted manner. A DC power module is installed on the data acquisition module, which can supply power to hundreds of probes. After the data acquisition module completes the acquisition of all Hall sensing probes, it will encode the data. The encoded data is losslessly compressed, and all information such as time, probe number, and bolt loosening status is completely retained. Ethernet interfaces, CAN, RS485 and other data interfaces are provided on the data acquisition module, and communication is carried out with the data communication module through these interfaces.

[0110] As Figure 1 shown in the figure, the data communication module in this embodiment sends the data to the gateway in the device / facility through local wireless networks such as WIFI, Lora, Bluetooth, and Zigbee, and finally transmits it to the upper computer or cloud server. The data communication module can also directly transmit the data to the upper computer or cloud server through 4G / 5G operator networks or BT-iot platforms, etc. The data communication module has a data encryption function, and encrypts the data during the transmission process to ensure the security of the data. The data communication module can perform two-way data transmission, that is, send data such as instructions or configuration information to the data acquisition module through the upper computer or cloud server.

[0111] As Figure 1 shown in the figure, the online monitoring and early warning software for bolt tightening degree in this embodiment is a software system that real-time monitors the bolt tightening degree status and issues early warning signals. This system is mainly applied in industrial Internet fields such as wind power and hydropower stations, and is used to real-time monitor the tightening degree of bolts at important parts of large equipment units such as wind power tower barrels and hydropower station water turbine units. By receiving the bolt status data transmitted from the data acquisition module, advanced algorithms are used to analyze and judge the acquired data to identify whether there are signs of bolt loosening. It provides data support for the health management and intelligent operation and maintenance of the equipment, ensures the safety and reliability of key bolts, and prevents major safety hazards caused by bolt loosening or abnormal pre-tightening force.

[0112] Example 2

[0113] As Figure 7 shown, this embodiment provides a detection method for an on-line monitoring and early warning system for bolt tightening degree, which includes the following steps:

[0114] Step S1: Establish a magnetic field coordinate system, specifically:

[0115] Record the axis direction of the bolt as the z-axis;

[0116] Generate a z-axis magnetic field component with a sine distribution or a sawtooth distribution around the z-axis through the upper magnetic ring assembly and the lower magnetic ring assembly, that is, the z-axis magnetic field components at different positions on the ring around the z-axis are different;

[0117] The position of a point on the ring around the z-axis can be calculated by measuring the distribution of the z-axis magnetic field near any point.

[0118] Step S2: Collect magnetic field data through Hall sensing probes;

[0119] Step S3: Calculate the positions of the nut and the bolt within a quarter cycle according to the magnetic field data. The position calculation methods of the nut and the bolt are the same, specifically:

[0120] For the z-axis magnetic field component with a sine magnetic field distribution, arrange the upper Hall sensor 6 and the lower Hall sensor 5 at intervals of λ / 4 on the circumference with the z-axis as the center, where λ is the spatial wavelength of the sine magnetic field;

[0121] Record the magnetic field value measured by the upper Hall sensor 6 as V1, and the magnetic field value measured by the lower Hall sensor 5 as V2. When V1 and V2 are in the of the sine magnetic field, calculate the angle D at the position of V1:

[0122]

[0123] The angle D at the position of V1 is the position of the nut and the bolt within a quarter cycle;

[0124] For the z-axis magnetic field component with a sawtooth magnetic field distribution, arrange the upper Hall sensor 6 and the lower Hall sensor 5 at intervals of L on the circumference with the z-axis as the center, where L = θR, R is the radius of the circle where the Hall sensor is located, and θ is the interval angle between the two Hall sensors;

[0125] Record the magnetic field value measured by the upper Hall sensor 6 as V1, and the magnetic field value measured by the lower Hall sensor 5 as V2. When V1 and V2 are in the of the sawtooth magnetic field, calculate the angle D at the midpoint position of V1 and V2:

[0126]

[0127] The angle D at the midpoint of V1 and V2 is the position of the nut and bolt within a quarter cycle.

[0128] Step S4: Determine the nut zero position, specifically:

[0129] After the Hall sensing probe is installed and powered on for the first time, measure the angles of the nut and bolt at fixed intervals, and record the last m measurement values as D n-m+1 、D n-m+2 、......D n ;

[0130] Denote as the nut zero position, and take D i = D - D0 as the angular position of the nut at the i-th measurement.

[0131] Step S5: Combine the nut zero position information to determine the positions of the nut and bolt in the remaining three - quarter cycles, specifically:

[0132] Judge the quadrant where the nut is located (a total of four quadrants) according to the positive and negative of V1 and V2;

[0133] Call the conversion function for the corresponding quadrant;

[0134] Use the zero position information to convert the angles of the nut and bolt to the range of - 90° to 270°.

[0135] Step S6: Conduct bolt loosening discrimination, specifically:

[0136] Based on information such as the bolt operation manual of the object to be detected, the operation and maintenance experience data of the equipment owner, and the calculation formula for bolt pre - tightening force and loosening angle, formulate a bolt loosening angle criterion D s , when the angular position of the nut at the i - th measurement satisfies |D i - D0|≥D s , it is determined that the bolt is loose.

[0137] Step S7: Alarm when the bolt is loose. When the bolt is loose or the pre - tightening force is abnormal, the system will immediately trigger the alarm mechanism, and send alarm information to relevant business personnel through sound, light, text message, email, etc. The system will store all monitoring data and alarm records. After a bolt loosening warning occurs, big data can be formed for backtracking, which is convenient for management personnel to query and analyze at any time, providing data support for equipment maintenance and management. Through the efficient operation of the online monitoring and warning software, the system can achieve real - time monitoring and intelligent warning, effectively ensuring the safe and stable operation of the equipment.

[0138] In the specific embodiments described above, the technical problems solved by the present invention, the technical solutions and the beneficial effects have been further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An on-line monitoring and early warning system for bolt fastening degree, characterized in that: It includes an upper magnetic ring assembly, a lower magnetic ring assembly, a Hall sensing probe, a communication bus, a data acquisition module, a data communication module, and on-line monitoring and early warning software for bolt tightening degree; The upper magnetic ring assembly is used to provide a magnetic field for the bolt, and the lower magnetic ring assembly is used to provide a magnetic field for the nut; the upper magnetic ring assembly includes an upper magnetic ring (1), and a plurality of upper magnets are arranged inside the upper magnetic ring (1); the lower magnetic ring assembly includes a lower magnetic ring (2), and a plurality of lower magnets are arranged inside the lower magnetic ring (2); The Hall sensing probe is used to detect the change in magnetic flux acting on the Hall sensor by the upper magnetic ring assembly and the lower magnetic ring assembly, and convert the collected change data of the magnetic flux into bolt loosening angle data; The Hall sensing probe is connected to the data acquisition module through the communication bus. The data acquisition module is used to collect the bolt loosening angle data output by the Hall sensing probe and perform encoding, and send the encoded bolt loosening angle data information to the data communication module; the Hall sensing probe includes a probe housing (3) and a probe circuit board (4); a plurality of side wall magnets (8) are arranged on the side wall of the inner cavity of the probe housing (3), and the side wall magnets (8) are adsorbed on the side wall of the nut; a plurality of upper surface magnets (9) are arranged in the inner cavity of the probe housing (3), and the upper surface magnets (9) are adsorbed on the end surface of the nut; an upper Hall sensor (6) for sensing the magnetic field generated by the upper magnetic ring assembly is arranged at the top of the probe housing (3); the probe circuit board (4) is arranged at the bottom of the probe housing (3), and a lower Hall sensor (5) for sensing the magnetic field generated by the lower magnetic ring assembly is arranged on the probe circuit board (4); the upper Hall sensor (6) and the lower Hall sensor (5) are both electrically connected to the probe circuit board (4), and the probe circuit board (4) is electrically connected to the data acquisition module; The data communication module is used to transmit the bolt state data information sent by the data acquisition module to the upper computer; The on-line monitoring and early warning software for bolt tightening degree is set in the upper computer. The on-line monitoring and early warning software for bolt tightening degree is used to receive the bolt loosening angle data information sent by the data acquisition module, and analyze and judge the bolt state data information to identify whether the bolt shows signs of loosening.

2. The on-line monitoring and early warning system for bolt fastening degree according to claim 1, characterized in that: A soft magnetic material (10) is arranged on the surface of the side wall magnet (8) away from the side wall of the nut, and a soft magnetic material (10) is arranged on the surface of the upper surface magnet (9) away from the end surface of the nut.

3. A detection method for an on-line monitoring and early warning system for the bolt fastening degree as described in any one of claims 1 to 2, characterized in that, It includes the following steps: Step S1, establish a magnetic field coordinate system; Step S2, collect magnetic field data through the Hall sensing probe; Step S3, calculate the positions of the nut and the bolt within a quarter cycle according to the magnetic field data; Step S4, determine the zero position of the nut; Step S5, combine the nut zero position information to determine the positions of the nut and the bolt within the remaining three quarters of the cycle; Step S6, perform bolt loosening discrimination; Step S7, alarm when the bolt is loose.

4. The detection method according to claim 3, wherein In the step S1, to establish a magnetic field coordinate system, it specifically includes the following steps: Record the axis direction of the bolt as the z-axis; Generate a z-axis magnetic field component with a sinusoidal distribution or a sawtooth distribution around the z-axis through the upper magnetic ring assembly and the lower magnetic ring assembly; The position of a point on a circular ring around the z-axis can be calculated by measuring the distribution of the z-axis magnetic field near any point.

5. The detection method according to claim 4, wherein In the step S3, calculating the positions of the nut and the bolt within a quarter cycle according to the magnetic field data specifically includes the following steps: For the z-axis magnetic field component of the sinusoidal magnetic field distribution, Hall sensors (6) and lower Hall sensors (5) are arranged at intervals on a circle centered on the z-axis, where is the spatial wavelength of the sinusoidal magnetic field; ​ Record the magnetic field value measured by the upper Hall sensor (6) as and the magnetic field value measured by the lower Hall sensor (5) as . When and are in the of the sinusoidal magnetic field, calculate the angle at the position of : ； The angle of the location is the position of the nut and bolt within a quarter cycle; For the z-axis magnetic field component of the sawtooth magnetic field distribution, an upper Hall sensor (6) and a lower Hall sensor (5) are arranged at intervals of L on a circumference centered on the z-axis, where, , is the radius of the circumference where the Hall sensors are located, is the angular interval between the two Hall sensors; Record the magnetic field value measured by the upper Hall sensor (6) as , and the magnetic field value measured by the lower Hall sensor (5) as . When and are in the of the sawtooth magnetic field, calculate the angle of the midpoint of and : ； and the angle of the midpoint position is the position of the nut and bolt within a quarter cycle.

6. The detection method according to claim 5, wherein In the step S4, determining the zero position of the nut specifically includes the following steps: After the Hall sensing probe is installed and powered on for the first time, measure the angles of the nut and the bolt at fixed intervals, and record the last m measurement values; Record as the nut zero position, and take as the angular position of the nut at the i-th measurement.

7. The detection method according to claim 6, wherein In the step S5, combining the nut zero position information to determine the positions of the nut and the bolt within the remaining three quarters of the cycle specifically includes the following steps: Judge the quadrant where the nut is located according to the positive and negative of V1 and V2; Call the conversion function corresponding to the quadrant; Use the zero position information to convert the angles of the nut and the bolt to the range of -90° to 270°; 8. The detection method according to claim 7, characterized in that In the step S6, perform bolt loosening discrimination, specifically including the following steps: Formulate the bolt loosening angle criterion D s , when the nut angular position measured at the i-th time satisfies ≥ , it is determined that the bolt is loose.

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