An ultrasonic-based real-time measurement device for bolt axial force of electrolytic cell

Abstract

The utility model discloses an electrolytic cell bolt axial force real -time measuring device based on ultrasonic wave, including setting in the ultrasonic monitoring mechanism of magnetism seat, magnetism seat includes magnetic core, mounting seat, magnetic flux path, one end of magnetic core is provided with magnetic flux path, and the other end is provided with the mounting seat of ultrasonic monitoring mechanism, and the magnetic core is cylindrical, and the high -frequency ultrasonic probe is set in the one end close to magnetic flux path through the through -hole, the end of the bolt of being monitored is processed and forms the bolt end face, and the magnetism seat is fixed on the bolt end face through the magnetic attraction of magnetic flux path one end, makes the high -frequency ultrasonic probe coupling surface and bolt end face between keeping acoustic coupling. The utility model solves the technical pain point of big error, unable dynamic monitoring of traditional torque indirect measurement method, can reflect electrolytic cell stress state in real time, ensures electrolytic cell sealing performance and electric performance stable, has the advantages of strong anti -interference ability, wide adaptability, convenient operation simultaneously, is applicable to all kinds of large -scale electrolytic cell bolt's whole life cycle monitoring.

Description

Technical Field

[0001] This utility model relates to the field of electrolytic cell testing and maintenance technology, specifically to an ultrasonic-based real-time measurement device and method for bolt axial force in electrolytic cells; it is particularly suitable for monitoring the bolt axial force of large electrolytic cells in the chlor-alkali industry, non-ferrous metal electrolysis and other fields. Background Technology

[0002] As the core equipment in the electrolysis process, the electrolytic cell's sealing and electrical performance directly determine production efficiency and operational safety. The cell body is secured with numerous high-strength bolts. The sealing of the electrolytic cell depends on the stability of the bolt preload (i.e., axial force). Bolt axial force is not only crucial for maintaining the pressure on the sealing surface but also a core indicator reflecting the overall stress state of the electrolytic cell. Insufficient axial force can lead to electrolyte leakage, causing safety accidents, and can also increase the contact resistance between the electrode plates and the diffuser current collector, resulting in higher cell voltage, increased energy consumption, and decreased efficiency. Excessive axial force, on the other hand, can cause plastic deformation of the bolts and cracking of the electrolytic cell shell, directly affecting the stability of electrical performance and causing significant economic losses.

[0003] There are two main methods for measuring the axial force of bolts in electrolytic cells: one is the torque wrench method, which indirectly estimates the axial force by controlling the bolt tightening torque. However, the conversion between torque and axial force is affected by factors such as bolt surface roughness, lubrication status, and thread friction coefficient, with errors generally reaching 15%-20%, which cannot meet the requirements for high-precision sealing. The other is the strain gauge method, which directly measures the strain by attaching strain gauges to the bolt surface. However, strain gauges are easily affected by the high temperature and corrosive gases in the working environment of the electrolytic cell, have a short lifespan, and are complex to install, making long-term real-time monitoring impossible.

[0004] Furthermore, existing technologies are ill-suited for the synchronous monitoring of multiple bolts in electrolytic cells and lack a temperature compensation mechanism—temperature fluctuations during electrolytic cell operation can cause changes in the Young's modulus of the bolt material and shifts in ultrasonic wave propagation velocity, further amplifying measurement errors. Therefore, developing a high-precision, real-time, and interference-resistant electrolytic cell bolt axial force measurement technology is crucial for addressing the pain points in electrolytic cell operation and maintenance. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a real-time measurement device and method for the axial force of bolts in an electrolytic cell based on ultrasound, so as to realize accurate and dynamic monitoring of bolt axial force, reflect the stress state of the electrolytic cell in real time, and ensure the sealing performance and operational safety of the electrolytic cell.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows: An ultrasonic-based real-time measuring device for the axial force of bolts in an electrolytic cell includes an ultrasonic monitoring mechanism mounted on the bolt. The ultrasonic monitoring mechanism is housed within a magnetic base and is attached to the end of the bolt being monitored via the magnetic base. The magnetic base includes a magnetic core, a mounting base, and a magnetic guide plate. One end of the magnetic core is provided with a magnetic guide plate, and the other end is provided with a mounting base for the ultrasonic monitoring mechanism. The magnetic core is cylindrical and has a through hole along its axial direction for the ultrasonic probe to pass through and be mounted. The high-frequency ultrasonic probe is mounted at one end near the magnetic guide plate through the through hole. A bolt end face is formed at the end of the bolt being monitored. The magnetic seat is magnetically fixed to the bolt end face by one end of the magnetic guide plate, so that the coupling surface of the high-frequency ultrasonic probe and the bolt end face maintain good acoustic coupling.

[0007] Furthermore, the magnetic base structure also includes an externally enclosed reinforced shell, which is made of 1.5-2mm thick 304 stainless steel as the outer shell.

[0008] Furthermore, the high-frequency ultrasonic probe is used to transmit and receive ultrasonic signals to the target bolt of the electrolytic cell, and its operating frequency range is 2MHz-15MHz. The high-frequency ultrasonic probe is a longitudinal wave ultrasonic probe.

[0009] Furthermore, the ultrasonic monitoring mechanism is fixed to the mounting base via a threaded connection.

[0010] Furthermore, the magnetic core uses neodymium iron boron strong magnetic material, so that the magnetic attraction force of the magnetic base is ≥50N, and the probe fits tightly against the end face of the bolt.

[0011] Furthermore, an adjustable gasket assembly is provided on one side of the magnetic plate. The gasket assembly is made of polytetrafluoroethylene and has a thickness of 1-3 mm. The gasket and the magnetic plate are connected by a slot structure. The edge of the gasket has a positioning protrusion, and the bottom of the magnetic plate has a corresponding positioning groove.

[0012] Furthermore, it also includes a coupling agent storage and sealing structure. An annular coupling agent storage tank is provided around the magnetic guide plate at the bottom of the magnetic base. The inside of the coupling agent storage tank is a cavity structure. A coupling agent filling cavity is formed between the high-frequency ultrasonic probe and the bolt end face. Multiple connecting pipes are provided inside the coupling agent storage tank. The connecting pipes radially pass through the magnetic guide plate and connect to the filling cavity where the probe end is located inside. The coupling agent storage tank is provided with an injection hole and an exhaust valve is provided at the top.

[0013] The advantages and beneficial effects of this utility model are as follows: 1. High measurement accuracy: Through the microsecond-level timing accuracy of ultrasonic waves, the micro-elongation of the bolt is directly correlated. Combined with the temperature compensation mechanism, the axial force measurement error is ≤2%, which is far superior to the traditional torque method (15%-20% error), meeting the high-precision sealing requirements of electrolytic cells and industrial-grade measurement requirements.

[0014] 2. Real-time dynamic monitoring: The sampling frequency can reach 1Hz-10Hz, monitoring not only individual bolts but also the overall health status of the entire electrolytic cell through stress distribution cloud maps. It can capture changes in bolt axial force in real time, promptly detect anomalies such as axial force attenuation and sudden changes, and avoid the risk of leakage or structural damage. This ensures that the sealing performance of the electrolytic cell is always under control.

[0015] 3. Strong anti-interference capability: Through signal filtering, high-temperature coupling agent, and temperature compensation design, it can withstand the high temperature, electromagnetic interference, and corrosive environment of the electrolytic cell, and adapt to long-term stable operation. Suitable for harsh industrial scenarios.

[0016] 4. Data-driven decision-making: The accumulated long-term axial force data provides a solid data foundation for predictive maintenance, optimized fastening processes, and extended equipment life. A fixed sensor network has been established, enabling uninterrupted or on-demand monitoring throughout the entire lifecycle of the electrolytic cell, realizing the transformation from "periodic maintenance" to "condition monitoring."

[0017] 5. Convenient operation and maintenance: Non-contact measurement, no need to stop the machine or remove bolts, intuitive cloud platform and visual terminal interface, support data export and remote early warning, reducing operation and maintenance costs. Attached Figure Description

[0018] Figure 1 This is a logic diagram of an ultrasonic-based real-time measurement system for the axial force of bolts in an electrolytic cell, according to the present invention. Figure 2 This is a schematic diagram of the real-time measurement system for the axial force of bolts in an electrolytic cell based on ultrasound in this invention. Figure 3 This is a partially enlarged schematic diagram of the magnetic base in this invention; In the diagram: 1. Ultrasonic monitoring mechanism; 2. Magnetic base; 3. Monitored bolt; 4. Magnetic core; 5. Mounting base; 6. Magnetic guide plate; 7. Through hole; 8. Bolt end face; 9. Reinforced housing; 10. Gasket assembly; 11. Positioning protrusion; 12. Positioning groove; 13. Coupling agent storage tank; 14. Filling cavity; 15. Connecting pipe; 16. Injection hole; 17. Exhaust valve; 18. Electrolytic cell end pressure plate; 19. High-frequency ultrasonic probe. Detailed Implementation

[0019] The specific embodiments of this utility model will be further described below with reference to examples. These examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0020] An ultrasonic-based real-time measuring device for the axial force of bolts in an electrolytic cell, such as... Figure 1 As shown, it mainly consists of an ultrasonic sensor network, a parameter storage unit, a central analysis server, an early warning unit, a cloud platform, and a visualization terminal. The units work together to achieve full automation from signal acquisition to result output. Ultrasonic sensing network: The core is a high-frequency ultrasonic probe 19, which includes a signal conditioning module and an acoustic time acquisition submodule. Each probe is fixedly installed at the end of a monitored bolt 3.

[0021] This is the front-end sensing layer of the system, using a longitudinal wave ultrasonic probe that is high-temperature resistant, anti-magnetic, and has an IP67 or higher protection rating. A small groove or flat surface is machined at the center of the end of the bolt being inspected, and the probe is fixed in this position using a high-strength magnetic base 2 or a special clamp. Stable and good acoustic coupling is ensured between the probe coupling surface and the bolt end face 8 through a high-temperature couplant. All high-frequency ultrasonic probes 19 are connected to the field signal junction box located on the electrolytic cell operating platform via shielded twisted-pair cables or coaxial cables. The cables should be laid in high-temperature resistant cable trays to avoid mechanical damage and high-temperature baking.

[0022] The ultrasonic monitoring mechanism 1 consists of a high-frequency ultrasonic probe 19, a signal conditioning module, and an acoustic time acquisition submodule. The high-frequency ultrasonic probe 19 is a longitudinal wave type with a working frequency range of 2MHz-15MHz. It can effectively penetrate bolts and accurately reflect signals. It is installed on the end of the monitored bolt 3 using a magnetic fixing structure (using neodymium iron boron strong magnetic material, with a suction force ≥50N). A 1-3mm adjustable shim is provided at the bottom to accommodate a flatness error of ≤0.5mm on the bolt end face. A 3-8mm thick high-temperature silicon-based coupling agent layer is applied to the end face to ensure tight adhesion and wear and corrosion resistance in the electrolytic cell working environment of -20℃-150℃. The signal conditioning module is responsible for amplifying the power of the emitted ultrasonic signal and filtering, reducing noise, and adjusting the gain of the received reflected signal to eliminate signal interference caused by electrolytic cell vibration and electromagnetic interference. The acoustic time acquisition submodule accurately captures ultrasonic propagation time data with a time resolution of 0.1μs, providing high-precision raw data for subsequent calculations.

[0023] Data storage unit: This unit is installed in the field control cabinet, close to the electrolytic cell. Hardware components: It includes a multi-channel ultrasonic pulse transmitter and receiver card, a high-precision time-to-digital converter, a multiplexer, and a temperature acquisition module. It is responsible for sequentially transmitting high-voltage pulse excitation signals to each ultrasonic probe and for receiving and digitizing the returned echo signals with high precision. Its core task is to accurately measure the flight time of the ultrasonic wave from transmission to reception, i.e., acoustic time, with a measurement accuracy down to the nanosecond level.

[0024] Furthermore, this unit adopts a partitioned storage architecture of "basic parameter area + calibration parameter area + threshold parameter area + historical data area" to achieve data classification management and efficient retrieval. The basic parameter area stores fixed information such as bolt stress cross-sectional area A, material Young's modulus E, effective length L, probe model, and channel number, supporting one-time writing or batch import, with no data retention restrictions; the calibration parameter area stores calibration data such as ultrasonic standard propagation velocity v0, temperature correction coefficient α, real-time operating temperature T, and corrected sound velocity vT, which is automatically overwritten and updated after each calibration and the records are retained for easy tracking of calibration accuracy; the threshold parameter area allows setting independent axial force threshold ranges for the sealing requirements of bolts at different locations in the electrolytic cell; the historical data area uses a cyclic overwrite storage method, supports data export, and is used for axial force change trend analysis and fault tracing, with the storage interval flexibly set between 1s and 3600s.

[0025] Central Analysis Server: This is an industrial computer or server. It has built-in dedicated analysis software, including a sound time extraction module: using cross-correlation algorithms or threshold detection methods, it accurately calculates the sound time value t from the acquired echo signal. Temperature Compensation Module: Receives signals from a platinum resistance thermometer installed near the bolt. It corrects the sound velocity in real time according to a formula, or directly establishes a sound time-temperature fitting relationship for compensation. Axial Force Calculation Module: Executes the core calculation logic. Diagnosis and Early Warning Module: Performs axial force range judgment and uniformity analysis.

[0026] As the data processing core of the system, the central analysis server is electrically connected to the ultrasonic monitoring mechanism 1 and the parameter storage unit respectively, and is built with an algorithm engine and a number of functional modules. Its core functions include: first, receiving the real-time sound time data transmitted by the sound time acquisition sub-module, executing the axial force calculation logic, converting the sound time variation into elongation, and then deriving the real-time axial force in combination with the physical parameters of the bolt; second, the built-in temperature compensation module obtains the real-time temperature of the bolt through a temperature sensor (acquisition accuracy ±0.5°C), and corrects Young's modulus E to ET (correction accuracy ≤0.5%) and the sound velocity v0 to vT (correction accuracy ≤0.3%) according to the pre-stored correction curves and formulas; third, it is equipped with a moving average filtering algorithm to filter the sound time data, and is provided with an "abnormal data elimination" function. When the deviation between a single sound time data and the historical average exceeds 5%, it is automatically determined as abnormal data and eliminated, so as to ensure the stability of the calculation result; fourth, it generates a stress cloud map of the electrolyzer, and combines the axial force data and geographical location information of all monitored bolts to visually display the uniformity of the stress distribution in the tank body.

[0027] The early warning unit is electrically connected to the central analysis server, and adopts a three-level early warning mechanism of "dynamic threshold + delayed trigger" to avoid false alarms caused by instantaneous fluctuations: first-level early warning (yellow prompt) corresponds to axial force F approaching the threshold boundary and lasting for ≥30s, which only displays a prompt on the visual terminal; second-level early warning (orange acousto-optic alarm) corresponds to axial force exceeding the threshold by less than 5% and lasting for ≥10s, which triggers an intermittent acousto-optic alarm; third-level early warning (red acousto-optic alarm) corresponds to axial force exceeding the threshold by more than 5%, which triggers a continuous acousto-optic alarm and synchronously sends a remote signal to the operation and maintenance terminal, and even triggers a "load reduction" signal for the electrolyzer control system. The cloud platform and the visual terminal provide a user-friendly human-computer interaction interface, including a real-time monitoring interface (displaying axial force (accurate to 0.1kN), elongation (accurate to 0.001mm), sound time and temperature data by both instrument panel and digital display), a parameter setting interface (supports manual input or scanning code entry of bolt parameters, and can select the preset value of temperature correction coefficient α according to materials), a data query interface (supports querying historical data by time and channel number, generating axial force / temperature change curves and supports zooming and screenshot), and a system maintenance interface (displays probe connection, communication and power status, and supports firmware upgrade, self-checking and fault location).

[0028] Specifically, the measurement method matched with the solution of the present invention strictly follows the whole-process logic of "calibration - benchmark acquisition - real-time monitoring - compensation calculation - early warning recording", and the specific steps are as follows: 1. Device Deployment and Parameter Initialization: Fix the high-frequency ultrasonic probe 19 to the end face 8 of the target bolt in the electrolytic cell and apply a high-temperature coupling agent. Input the physical parameters (A, E, L) of the bolt through the cloud platform. In addition, under the standard ambient temperature of 25℃, use a standard sample of the same material and specification as the target bolt as the test object, emit ultrasonic waves and record the propagation time t. Combine the standard sample length L to calculate the standard sound velocity v0 (v0=L / t). The calibration is performed no less than 3 times, and the average value is taken to ensure that the calibration error is ≤0.1%. At the same time, set the axial force threshold range.

[0029] 2. Initial reference value acquisition: When the electrolytic cell is not running or the bolts are in the initial pre-tightening state, ultrasonic waves are emitted to the bolts through the ultrasonic monitoring mechanism 1, and the initial acoustic time t0 is recorded as the reference data for subsequent measurements, thus eliminating the influence of initial installation errors on the results.

[0030] 3. Real-time acoustic time monitoring: During the operation of the electrolytic cell, the ultrasonic monitoring unit 1 continuously emits ultrasonic waves at a settable sampling frequency of 1Hz-10Hz, and collects the propagation time t1 in real time. The central analysis server calculates the change in acoustic time Δt=|t1-t0|.

[0031] 4. Temperature compensation and parameter correction: The temperature compensation module collects the real-time operating temperature T of the electrolytic cell, corrects the Young's modulus E to ET according to the pre-stored correction curve, and corrects the sound velocity v0 to vT using the formula vT=v0×(1+α×T), thus eliminating the interference of temperature on the calculation accuracy.

[0032] 5. Calculation of Elongation and Axial Force: The central analysis server calculates the real-time elongation of the bolt according to the formula ΔL=(vT×Δt) / 2, and then substitutes it into the formula F=(A×ET×ΔL) / L to obtain the real-time axial force F.

[0033] 6. Stress state judgment and early warning: The real-time axial force F is compared with the threshold range in the parameter storage unit. If F is within the threshold, the stress is judged to be normal and the sealing is qualified. If F is lower than the lower limit, the risk of sealing failure is indicated. If F is higher than the upper limit, the bolt overload or the stress of the groove is exceeded. The early warning unit triggers the corresponding early warning according to the three-level mechanism.

[0034] 7. Data Recording and Output: The cloud platform displays axial force, elongation, temperature and stress status in real time, automatically stores historical data and supports export, providing data support for operation and maintenance personnel to conduct trend analysis and troubleshooting.

[0035] Example 1: Bolt monitoring of a 30kA electrolytic cell in a chlor-alkali plant 1. Preliminary preparations and deployment Eight M30 bolts from a 30kA electrolytic cell in a chlor-alkali plant were selected as monitoring targets. A high-frequency ultrasonic probe 19 with a working frequency of 5MHz was used, installed on the end face 8 of each bolt via a magnetic fixing structure, and coated with a 5mm thick high-temperature silicon-based coupling agent. A multi-channel switching module was connected, and the sampling frequency was set to 5Hz to meet dynamic monitoring requirements. The physical parameters of the M30 bolts were input via a cloud platform: stress cross-sectional area A = 561mm². 2 The material has a Young's modulus E = 206 GPa and an effective length L = 200 mm. The ultrasonic propagation speed was calibrated under a standard environment of 25℃. Using an M30 standard sample of the same material and specifications (length L_standard = 200 mm), the propagation time was measured in three calibrations: 33.9 μs, 33.8 μs, and 33.9 μs. The average value t_standard = 33.87 μs was taken, and v0 = L_standard / t_standard = 200 mm / 33.87 μs ≈ 5900 m / s was calculated. Considering the sealing requirements of the electrolytic cell, the axial force threshold range was set to 180 kN-220 kN.

[0036] 2. Measurement process and results After the electrolytic cell starts up, the system collects data in real time at a sampling frequency of 5Hz: the initial acoustic time recorded under the initial pre-tightening state is t0=67.8μs; during operation, the real-time working temperature of the bolt is monitored to be T=65℃. The temperature compensation module corrects the Young's modulus E to ET=202GPa based on the pre-stored correction curve, using the formula vT=v0×(1+α×T) (the sound velocity temperature coefficient of the bolt material is α=1.2×10). -5 / ℃) The calculated value is vT = 5900 m / s × (1 + 1.2 × 10⁻⁶ ... -5 (65℃ / ℃) = 5940m / s; The real-time acoustic acquisition time t1 = 68.1 μs. The change in acoustic time Δt = |68.1μs - 67.8μs| = 0.3μs; Substitute into the elongation formula ΔL=(vT×Δt) / 2=(5940m / s×0.3×10 -6 s) / 2=0.891mm; Substitute into the axial force formula: F=(A×ET×ΔL) / L =(561mm 2 ×202GPa×0.891mm) / 200mm≈200kN, If the axial force is within the threshold range of 180kN-220kN, the electrolytic cell is considered to have normal stress and satisfactory sealing performance.

[0037] 3. Anomaly Simulation and Early Warning Response To verify the effectiveness of the early warning function, abnormal axial force was simulated by manually adjusting the bolt preload: when the bolt axial force dropped to 175kN, the system monitored t1=67.98μs, calculated Δt=0.18μs, ΔL=0.85mm, and F=178kN. At this point, the axial force was close to the lower threshold limit, and the system triggered a level one yellow warning, displaying a prompt message on the visual terminal; when the axial force was further reduced to 170kN, t1 was monitored again at 67.95μs, and F=170kN was calculated. The axial force exceeded the lower threshold limit by more than 5%, and the system immediately triggered a level two orange audible and visual alarm. After receiving the alarm signal, the maintenance personnel promptly tightened the bolt to avoid the risk of electrolyte leakage, verifying the timeliness and effectiveness of the system's early warning.

[0038] Example 2: Synchronous Monitoring of Multiple Bolts in a 50kA Electrolytic Cell at a Non-ferrous Metal Electrolysis Plant 1. Deployment and Parameter Settings Twelve M36 bolts from a 50kA electrolytic cell in a non-ferrous metal electrolysis plant were selected as monitoring targets. A high-frequency ultrasonic probe 19 with an operating frequency of 8MHz was used, magnetically fixed to the bolt end face 8 and coated with a high-temperature coupling agent. The sampling frequency was set to 8Hz to accommodate the high fluctuations in the operating conditions of the electrolytic cell. The input parameters for the M36 bolts were: A = 817mm. 2 E=208GPa, L=250mm; calibrated at 25℃, v0=5920m / s; based on the sealing requirements of bolts at different positions in the electrolytic cell, the threshold range for bolts at both ends is set to 220kN-260kN, and the threshold range for bolts in the middle is set to 200kN-240kN (the sealing pressure requirement in the middle is slightly lower than that at the ends).

[0039] 2. Monitoring and Stress Analysis During the operation of the electrolytic cell, the system collected axial force data of 12 bolts in real time and generated a stress distribution cloud map. Within one hour of operation, the axial force of 10 bolts remained stable within the threshold range. The axial forces of the two end bolts were 245kN and 242kN, respectively, while the axial forces of the eight middle bolts were between 210kN and 225kN. The axial force of two other middle bolts (numbered 3# and 7#) continued to decrease, from an initial 220kN to 205kN (after 30 minutes of operation). At this point, the axial force was close to the lower limit of the threshold, and the system triggered a level one warning. After running for a period of time, the axial force of bolt #3 dropped to 198kN, exceeding the lower limit of the threshold by 1%, triggering a level two warning. The maintenance personnel quickly located the positions of bolts #3 and #7 through the stress cloud map and found that there was a slight deformation of the electrolytic cell shell in this area, which caused uneven stress on the bolts. The shell was adjusted in time and the bolts were tightened, and the axial force was finally restored to 215kN, ensuring the stable operation of the electrolytic cell.

[0040] 3. Data traceability and trend analysis After 30 days of continuous operation, maintenance personnel exported historical data from the cloud platform, generating axial force variation curves for 12 bolts. Analysis revealed that the average fluctuation range of the axial force of the end bolts was ±3kN, and the average fluctuation range of the middle bolts was ±2kN, indicating good overall axial force stability. Simultaneously, a brief abrupt change in axial force was observed in bolt #7 on the 25th day of operation (from 220kN to 235kN). Combined with the temperature data at that time (T=140℃, 15℃ higher than usual), it was determined that the instantaneous axial force change was caused by thermal expansion and contraction of the bolt due to a sudden temperature rise. Since the duration was only 2 seconds, the system did not trigger an alarm, verifying the effectiveness of the "dynamic threshold + delayed trigger" design in avoiding false alarms. Based on the 30 days of historical data, maintenance personnel established a bolt maintenance cycle for this type of electrolytic cell, adjusting the original monthly manual inspection to once every two months, and combining real-time system monitoring data for on-demand maintenance, significantly reducing maintenance costs.

[0041] Example 3: The magnetic base 2 serves as the core fixing component of the high-frequency ultrasonic probe 19, such as Figure 2 , 3 As shown, the magnetic base 2 needs to balance strong adsorption, environmental adaptability, and installation flexibility. It includes a magnetic core 4 made of neodymium iron boron (NdFeB) strong magnetic material. The magnetic core 4 enables the magnetic base 2 to possess the required magnetism. The magnetic core 4 is cylindrical and has a through hole 7 along its axial direction for the ultrasonic probe to pass through. The magnetic base 2 structure also includes an externally encased reinforced shell 9. The reinforced shell 9 can be made of 1.5-2mm thick 304 stainless steel, thus protecting the magnetic core 4 from corrosive gases in the electrolytic cell environment and preventing the magnetic field from interfering with external equipment. One end of the magnetic core 4 is provided with a magnetic guide plate 6, and the other end is provided with a mounting base 5 for a high-frequency ultrasonic probe 19. The high-frequency ultrasonic probe 19 is fixed to the mounting base 5 by a threaded connection. The probe part of the high-frequency ultrasonic probe 19 is located at the end near the magnetic guide plate 6 through the through hole 7. The threaded connection of the high-frequency ultrasonic probe 19 allows for convenient disassembly and replacement during maintenance. The magnetic plate 6 is annular and 3-5mm thick. It is used to ensure that there is no stress concentration when it is in contact with the bolt end face 8, and at the same time enhances the magnetic field concentration effect, so that the overall attraction force is ≥50N, which meets the fixing requirements under the vibration condition of the electrolytic cell.

[0042] Furthermore, to accommodate flatness errors, an adjustable shim assembly 10 is provided at the bottom of the magnetic base 2 and below the magnetic guide plate 6. The shim assembly 10 is made of polytetrafluoroethylene (PTFE), with a temperature resistance of -20℃ to 260℃, suitable for the working temperature of the electrolytic cell. It is available in three thicknesses: 1mm, 2mm, and 3mm, which can be combined and stacked according to the flatness error (≤0.5mm) of the bolt end face 8. The shim and the magnetic guide plate 6 are connected via a slot-type connection. The edge of the shim has a positioning protrusion 11, and the bottom of the magnetic guide plate 6 has a corresponding positioning groove 12, ensuring that the shim does not shift after installation. Simultaneously, the surface of the shim is frosted (roughness Ra1.6) to enhance friction with the bolt end face 8, further improving the fixing stability.

[0043] Furthermore, a coupling agent storage and sealing structure is provided. Specifically, an annular coupling agent storage tank 13 with a width of 5-8 mm and a depth of 3-5 mm is provided around the magnetic plate 6 at the bottom of the magnetic base 2. It surrounds the reinforced shell 9 and is used to store high-temperature silicon-based coupling agent. The inside of the coupling agent storage tank 13 is designed as a cavity structure. During installation, coupling agent is injected into the cavity. The coupling agent is made of an elastic material, such as fluororubber, which has a certain elasticity and is oil and corrosion resistant. Multiple connecting pipes 15 are provided inside the coupling agent storage tank 13. The connecting pipes 15 radially pass through the magnetic plate 6 and connect to the through hole 7 where the probe is set inside, so that the coupling agent is injected between the probe and the end face of the bolt. Because the coupling agent storage tank 13 is elastic, its elastic pressure can keep the internal coupling agent under a certain pressure, so as to completely fill the space between the probe and the bolt end face 8, ensuring that the probe and the bolt end face 8 always maintain good acoustic coupling. When the magnetic base 2 is adsorbed onto the bolt end face 8, it effectively prevents the coupling agent from leaking and avoids external dust and electrolyte seeping in and affecting the coupling effect. The coupling agent storage tank 13 is equipped with an injection hole 16 and an exhaust hole at the top. The coupling agent can be replenished periodically using a syringe. When filling the coupling agent for the first time, the exhaust hole can be opened to release the air. For subsequent replenishments, the coupling agent can be directly injected into the coupling agent storage tank 13 without disassembling the magnetic base 2, reducing the complexity of operation and maintenance.

[0044] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A real-time measuring device for the axial force of bolts in an electrolytic cell based on ultrasound, characterized in that, The device includes an ultrasonic monitoring mechanism mounted on the monitoring bolt. The ultrasonic monitoring mechanism is housed within a magnetic base and is attached to the end of the bolt being monitored via the magnetic base. The magnetic base includes a magnetic core, a mounting base, and a magnetic guide plate. One end of the magnetic core is provided with a magnetic guide plate, and the other end is provided with a mounting base for the ultrasonic monitoring mechanism. The magnetic core is cylindrical and has a through hole along its axial direction for the ultrasonic probe to pass through and be mounted. The high-frequency ultrasonic probe is mounted at one end near the magnetic guide plate through the through hole. A bolt end face is formed at the end of the bolt being monitored. The magnetic seat is magnetically fixed to the bolt end face by one end of the magnetic guide plate, so that the coupling surface of the high-frequency ultrasonic probe and the bolt end face maintain good acoustic coupling.

2. The real-time measuring device for the axial force of bolts in an electrolytic cell based on ultrasound according to claim 1, characterized in that, The magnetic base structure also includes an externally enclosed reinforced shell, which is made of 1.5-2mm thick 304 stainless steel.

3. The real-time measuring device for axial force of bolts in an electrolytic cell based on ultrasound according to claim 1, characterized in that, The high-frequency ultrasonic probe is used to transmit and receive ultrasonic signals to the target bolts in the electrolytic cell. Its operating frequency range is 2MHz-15MHz. The high-frequency ultrasonic probe is a longitudinal wave ultrasonic probe.

4. The real-time measuring device for axial force of bolts in an electrolytic cell based on ultrasound according to claim 1, characterized in that, The ultrasonic monitoring mechanism is fixed to the mounting base by a threaded connection.

5. The real-time measuring device for the axial force of bolts in an electrolytic cell based on ultrasound according to claim 1, characterized in that, The magnetic core uses neodymium iron boron strong magnetic material, which makes the magnetic attraction force of the magnetic base ≥50N, so that the probe fits tightly against the end face of the bolt.

6. The real-time measuring device for axial force of bolts in an electrolytic cell based on ultrasound according to claim 1, characterized in that, An adjustable gasket assembly is provided on one side of the magnetic plate. The gasket assembly is made of polytetrafluoroethylene and has a thickness of 1-3mm. The gasket and the magnetic plate are connected by a slot structure. The edge of the gasket has a positioning protrusion, and the bottom of the magnetic plate has a corresponding positioning groove.

7. The real-time measuring device for axial force of bolts in an electrolytic cell based on ultrasound according to claim 1, characterized in that, It also includes a coupling agent storage and sealing structure. An annular coupling agent storage tank is provided around the magnetic guide plate at the bottom of the magnetic base. The inside of the coupling agent storage tank is a cavity structure. A coupling agent filling cavity is formed between the high-frequency ultrasonic probe and the bolt end face. Multiple connecting pipes are provided inside the coupling agent storage tank. The connecting pipes radially pass through the magnetic guide plate and connect to the filling cavity where the probe end is located inside. The coupling agent storage tank is provided with an injection hole and an exhaust valve is provided at the top.

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