Bolt pretightening force loading method and device

Abstract

The invention provides a bolt pre-tightening force loading method and device, and relates to the technical field of bolt pre-tightening force, and the bolt pre-tightening force loading method specifically comprises the steps of parameter collection, parameter analysis, comprehensive analysis and bolt safety level.The bolt pre-tightening force loading method comprises the steps of collecting the working temperature and vibration parameters of a bolt; the interference degree between the bolt and the object at the working temperature is analyzed, the damage degree of the bolt caused by interference between the heated and expanded bolt and the object at the working temperature is analyzed, a bolt expansion damage index is output, and equipment vibration parameters are analyzed. According to the method, a bolt vibration damage degree index for reflecting the damage degree of the bolt during equipment vibration is generated, after comprehensive correlation analysis, a pre-tightening force loss index for reflecting the pre-tightening force loss degree of the bolt after equipment working time t is generated, and then the bolt safety level is output.

Description

Technical Field

[0001] The present invention relates to the technical field of bolt pre-tightening force, in particular to a method and device for loading bolt pre-tightening force. Background Art

[0002] Bolt preload refers to the initial tension applied in a bolted connection to ensure that the contact surfaces between the connecting parts remain tight. The presence of preload can effectively improve the stability and safety of the structure. In engineering applications, appropriate preload not only ensures the reliability of the connection, but also improves the load-bearing capacity of the bolts and extends their service life. The selection of preload involves multiple factors, including the material, diameter, thread type, and properties of the bolts. Too low a preload may cause the connection to loosen, while too high a preload may cause plastic deformation or even fracture of the bolts. Therefore, during design and installation, it is often necessary to determine the appropriate preload through calculations and experiments. Therefore, in engineering practice, it is particularly important to monitor and maintain the preload status of the bolts. Through regular inspections and necessary adjustments, the safety and reliability of the connection can be ensured, thereby effectively avoiding potential structural failures and safety hazards.

[0003] Generally, the preload force of bolts is often set at room temperature. However, the working environment of the objects and equipment fastened by bolts is not necessarily at room temperature. The temperature may be much higher than room temperature. At this time, the impact of thermal expansion on the performance of the bolts cannot be ignored. At the same time, when the equipment is working, the vibration of the motor on it drives the regular vibration of the entire equipment, and the vibration will also have an impact on the bolts. Both vibration and high temperature will damage the bolts and create the risk of loosening, resulting in their lifespan being much lower than normal when the preload force is preset, thus creating risks.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and device for loading bolt preload force to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The method for loading bolt preload includes the following steps:

[0008] S1. Collecting bolt parameters and object parameters, wherein the bolt parameters include the bolt linear thermal expansion coefficient, initial length, and bolt operating temperature; and the object parameters include the object linear thermal expansion coefficient, initial thickness, and object operating temperature; performing correlation analysis on the bolt parameters to generate a bolt length variation; and performing correlation analysis on the object parameters to generate an object thickness variation;

[0009] S2. Perform correlation analysis on the bolt length variation and the object thickness variation to generate the temperature interference variation. Perform correlation analysis on the temperature interference variation Δ3 and the bolt parameters to generate the bolt expansion damage index LSZ. The bolt expansion damage index LSZ is used to reflect the damage caused to the bolt by the interference between the thermal expansion of the bolt and the object at the working temperature.

[0010] S3. Collect vibration parameters of the equipment, including the average vibration frequency, mass, and maximum acceleration of the object, perform correlation analysis on the vibration parameters to generate vibration stress, perform correlation analysis on the equipment operating time and average vibration frequency to generate the number of equipment operating cycles, and generate a bolt vibration damage severity index LZS. The bolt vibration damage severity index LZS is used to reflect the degree of damage to the bolts caused by equipment vibration;

[0011] S4. Combined with the equipment working time, the bolt vibration damage index LZS and the bolt expansion damage index LSZ are correlated and analyzed to generate the preload loss index LSS. The preload loss index LSS is used to reflect the degree of preload loss of the bolt after the equipment has been working for a period of time t.

[0012] S5. Compare the preload loss index LSS with the threshold θ and output the bolt safety level.

[0013] Furthermore, the bolts are tightened to the object, and the working temperature T1 of the bolts and the working temperature T2 of the object are measured by temperature sensors. The initial length L1 of the bolts and the initial thickness L2 of the object are measured by vernier calipers. The linear thermal expansion coefficients α1 of the bolts and α2 of the object are respectively queried based on the material properties of the bolts and the object. A correlation analysis is performed on the bolt parameters to generate the bolt length change Δ1. The formula used is:

[0014] Δ1=L1*α1*(T1-T s )

[0015] Among them, T s The bolt length change Δ1 is used to reflect the expansion amplitude of the bolt caused by heating at the working temperature.

[0016] Perform correlation analysis on the object parameters to generate the object thickness variation Δ2 based on the following formula:

[0017] Δ2=L2*α2*(T2-T s )

[0018] The object thickness variation Δ2 is used to reflect the expansion amplitude of the fastened object due to heat at the working temperature.

[0019] Furthermore, a correlation analysis is performed on the bolt length variation and the object thickness variation to generate the temperature interference variation Δ3, based on the following formula:

[0020] Δ3=|Δ2-Δ1|

[0021] The temperature interference variation Δ3 is used to reflect the relative expansion of the bolt and the object at the working temperature;

[0022] The correlation analysis of the temperature interference variation Δ3 and the bolt parameters is performed to generate the bolt expansion damage index LSZ. The formula is as follows:

[0023]

[0024] Among them, the bolt expansion damage index LSZ is used to reflect the damage caused to the bolt by the interference between the thermal expansion of the bolt and the object at the working temperature. E is the elastic modulus of the bolt, σ u is the ultimate strength of the bolt material, which is used to indicate the maximum stress that the material can withstand, σ Y is the yield strength of the bolt material, which is used to indicate the stress when the material begins to deform plastically. K1 is the stiffness of the bolt material, and K2 is the stiffness of the object material.

[0025] Furthermore, during operation, the vibration parameters of the device are collected, and the vibration parameters include the average vibration frequency f of the object, the mass m of the object and the maximum acceleration a max , perform correlation analysis on vibration parameters and generate vibration stress σ d , based on the formula:

[0026]

[0027] Where A is the cross-sectional area of ​​the bolt, N is the total number of bolts, and the vibration stress v d Used to reflect the averaged stress generated by each bolt under the influence of vibration.

[0028] Furthermore, a correlation analysis is performed on the equipment working time t and the average vibration frequency f to generate the equipment working cycle number M based on the following formula:

[0029] M=t*f

[0030] The number of equipment working cycles M is used to reflect the number of cyclic vibrations of the equipment, where the average vibration frequency f is the average vibration frequency of the equipment when it is working;

[0031] The correlation analysis of the equipment working cycle number M is performed to generate the bolt vibration damage degree index LZS based on the following formula:

[0032]

[0033] Among them, C is the maximum number of vibration cycles that the bolt material can withstand, and the bolt vibration damage degree index LZS is used to reflect the degree of damage to the bolt when the equipment vibrates.

[0034] Furthermore, the bolt vibration damage index LZS and the bolt expansion damage index LSZ were correlated to generate the preload loss index LSS. The formula is as follows:

[0035]

[0036] Among them, F0 is the contact area between the bolt and the nut, and the preload loss index LSS is used to reflect the degree of preload loss of the bolt after the equipment has been working for t.

[0037] Furthermore, the preload loss index LSS is compared with the threshold θ to output the bolt safety level. When LSS ≥ θ, the output bolt safety level is level 2. At this time, the bolt is in danger of loosening and needs to be reloaded and tightened. When LSS < θ, the output bolt safety level is level 1. At this time, the bolt is relatively tight and there is no risk of loosening.

[0038] Furthermore, the vibration frequency and maximum acceleration of the equipment are collected through the vibration sensor, the vibration frequency is analyzed by MATLAB software, and the average vibration frequency is output. The mass of the object is collected through the weight sensor, and the mass of the object is the mass of the equipment.

[0039] The present invention also provides a bolt preload force loading device for executing a bolt preload force loading method, comprising:

[0040] A temperature acquisition module is used to acquire bolt parameters and object parameters. The bolt parameters include the bolt's linear thermal expansion coefficient, initial length, and bolt operating temperature. The object parameters include the object's linear thermal expansion coefficient, initial thickness, and object operating temperature. A correlation analysis is performed on the bolt parameters to generate a bolt length change. A correlation analysis is performed on the object parameters to generate an object thickness change.

[0041] The temperature analysis module is used to perform correlation analysis on the change in bolt length and the change in object thickness to generate the temperature interference change. The temperature interference change Δ3 is then correlated with the bolt parameters to generate the bolt expansion damage index LSZ. The bolt expansion damage index LSZ reflects the damage caused to the bolt by the interference between the thermal expansion of the bolt and the object at the operating temperature.

[0042] A vibration acquisition module is used to collect vibration parameters of the equipment, including the average vibration frequency, mass, and maximum acceleration of the object, perform correlation analysis on the vibration parameters to generate vibration stress, and perform correlation analysis on the equipment operating time and average vibration frequency to generate the number of equipment operating cycles;

[0043] The vibration analysis module is used to perform correlation analysis on the data obtained by the vibration acquisition module to generate the bolt vibration damage degree index LZS. The bolt vibration damage degree index LZS is used to reflect the degree of damage to the bolts when the equipment vibrates;

[0044] The output module is used to perform correlation analysis on the bolt vibration damage index LZS and the bolt expansion damage index LSZ based on the equipment working time, and generate the preload loss index LSS. The preload loss index LSS is used to reflect the degree of preload loss of the bolt after the equipment working time t. The preload loss index LSS is compared with the threshold θ to output the bolt safety level.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The present invention collects the working temperature and vibration parameters of the bolts, analyzes the degree of interference between the bolts and the object at the working temperature, analyzes the degree of damage to the bolts caused by the thermal expansion of the bolts and the interference with the object at the working temperature, outputs the bolt expansion damage index, and analyzes the vibration parameters of the equipment to generate a bolt vibration damage degree index for reflecting the degree of damage to the bolts when the equipment vibrates. After comprehensive correlation analysis, it generates a preload loss index for reflecting the degree of preload loss of the bolts after the equipment has been working for a time t, and then outputs the bolt safety level. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the overall method flow of the present invention;

[0048] Figure 2 It is a schematic diagram of the overall system flow of the present invention. DETAILED DESCRIPTION

[0049] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to specific embodiments.

[0050] It should be noted that, unless otherwise defined, the technical or scientific terms used in the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0051] Example:

[0052] See also Figure 1 , the present invention provides a technical solution:

[0053] The method for loading bolt preload includes the following steps:

[0054] S1. To analyze the impact of temperature changes on the interference of bolts and objects on the equipment during operation, bolt parameters and object parameters are collected. The bolt parameters include the bolt's linear thermal expansion coefficient, initial length, and bolt operating temperature. The bolt operating temperature is the average temperature of the bolt when the equipment is operating normally. The object parameters include the object's linear thermal expansion coefficient, initial thickness, and object operating temperature. Correlation analysis is performed on the bolt parameters to generate a bolt length change. Correlation analysis is performed on the object parameters to generate an object thickness change.

[0055] Bolts are used to fasten objects. The working temperature of the bolts T1 and the object T2 are measured by temperature sensors. When the equipment is working stably, the working temperature of the bolts and each bolt position is constant and the variation is within a controllable range. Therefore, when collecting parameters, the working temperature values ​​are averaged. The initial length L1 of the bolts and the initial thickness L2 of the object are measured with a vernier caliper. The linear thermal expansion coefficients α1 and α2 of the bolts and the object are queried based on their material properties. A correlation analysis is performed on the bolt parameters to generate the bolt length change Δ1. The formula used is:

[0056] Δ1=L1*α1*(T1-T s )

[0057] Among them, T sThe bolt length change Δ1 is used to reflect the expansion amplitude of the bolt due to heat at the working temperature. The larger the value of the bolt length change Δ1, the higher the bolt expansion degree.

[0058] Perform correlation analysis on the object parameters to generate the object thickness variation Δ2 based on the following formula:

[0059] Δ2=L2*α2*(T2-T s )

[0060] The object thickness variation Δ2 is used to reflect the expansion amplitude of the fastened object due to heat at the working temperature. The larger the value of the object thickness variation Δ2, the higher the degree of thermal expansion of the fastened object.

[0061] S2. Perform correlation analysis on the bolt length variation and the object thickness variation to generate the temperature interference variation. Perform correlation analysis on the temperature interference variation Δ3 and the bolt parameters to generate the bolt expansion damage index LSZ. The bolt expansion damage index LSZ is used to reflect the damage caused to the bolt by the interference between the thermal expansion of the bolt and the object at the working temperature.

[0062] Since the preload is only measured and calculated at room temperature, when the temperature changes, expansion interference will cause the preload to be lost. When the bolt and the fastened object are made of different materials, their expansion coefficients are also different. Even if they are heated the same, the expansion degrees are different. Since the bolt and the object are tightly connected, when the bolt and the object expand to different degrees, interference will occur between the two, which will have a negative impact on the bolt and further cause the loss of preload. Specifically, a correlation analysis is performed on the change in bolt length and the change in object thickness to generate the temperature interference change Δ3. The formula based on this is:

[0063] Δ3=|Δ2-Δ1|

[0064] The temperature interference variation Δ3 is used to reflect the relative expansion of the bolt and the object at the working temperature. The temperature interference variation Δ3 is used to reflect the comparative expansion of the bolt and the object at the working temperature.

[0065] The correlation analysis of the temperature interference variation Δ3 and the bolt parameters is performed to generate the bolt expansion damage index LSZ. The formula is as follows:

[0066]

[0067] Among them, the bolt expansion damage index LSZ is used to reflect the damage caused to the bolt by the interference between the thermal expansion of the bolt and the object at the working temperature. E is the elastic modulus of the bolt, σ u is the ultimate strength of the bolt material, which is used to indicate the maximum stress that the material can withstand, σY is the yield strength of the bolt material, which is used to indicate the stress when the material begins to plastically deform. K1 is the stiffness of the bolt material, and K2 is the stiffness of the object material. The ultimate strength and yield strength of the bolt material are both measured through mechanical property test experiments. Δ3 / L1 reflects the degree of interference deformation between the bolt and the object. Its product with the elastic modulus E indicates the magnitude of the deformation stress of the bolt and the object. The degree of damage is obtained by analyzing the proportion of the maximum stress exceeded. The stiffness ratio of the bolt material stiffness to the object material stiffness is used to indicate the damage coefficient when the bolt and the object expand and interfere. The larger the bolt expansion damage index LSZ, the more serious the interference between the bolt and the object due to thermal expansion.

[0068] S3. Generally, when the equipment is working, the motor on it will drive the equipment to vibrate. The vibration frequency of the vibration is relatively stable, but the vibration will have a negative impact on the bolts. Therefore, the vibration parameters of the equipment are collected. The vibration parameters include the average vibration frequency of the object, the mass of the object, and the maximum acceleration. The vibration parameters are correlated to generate vibration stress. The equipment working time and the average vibration frequency are correlated to generate the number of equipment working cycles. The bolt vibration damage degree index LZS is generated. The bolt vibration damage degree index LZS is used to reflect the degree of damage to the bolts when the equipment vibrates. The equipment working time is the time when the vibration parameters are collected when the equipment is working normally.

[0069] During operation, the vibration parameters of the equipment are collected, including the average vibration frequency f of the object, the mass m of the object and the maximum acceleration a max , perform correlation analysis on vibration parameters and generate vibration stress σ d , based on the formula:

[0070]

[0071] Where A is the cross-sectional area of ​​the bolt, N is the total number of bolts, and the vibration stress σ d It is used to reflect the average stress generated by each bolt under the influence of vibration. This stress is the maximum stress. It is used to reflect the maximum stress of all bolts as a whole, and generate vibration stress σ after averaging. d .

[0072] The correlation analysis of the equipment working time t and the average vibration frequency f is performed to generate the number of equipment working cycles M based on the following formula:

[0073] M=t*f

[0074] The number of equipment working cycles M is used to reflect the number of cyclic vibrations of the equipment, where the average vibration frequency f is the average vibration frequency of the equipment when it is working;

[0075] The correlation analysis of the equipment working cycle number M is performed to generate the bolt vibration damage degree index LZS based on the following formula:

[0076]

[0077] Among them, C is the maximum number of vibration cycles that the bolt material can withstand. The bolt vibration damage index LZS is used to reflect the degree of damage to the bolt when the equipment vibrates. The larger the value, the higher the degree of damage. When the generated bolt vibration damage index LZS is greater than 1, it means that the bolt is loose due to vibration and cannot be used. The maximum number of vibration cycles C is obtained through experimental testing. Specifically, a standard bolt sample is prepared to ensure that its material and size are the same as those of the actual bolts. A fatigue tester is used to apply the same stress as σ d The same alternating stress is used to determine the vibration frequency, stress and test room temperature. Cyclic loading is performed under the set conditions. The number of cycles each sample endures before breaking is recorded. The stress-cycle number curve is drawn to determine the stress as σ d The number of cycles under the condition of vibration is recorded as the maximum vibration cycle number C.

[0078] S4. Combined with the equipment working time, the bolt vibration damage index LZS and the bolt expansion damage index LSZ are correlated and analyzed to generate the preload loss index LSS. The preload loss index LSS is used to reflect the degree of preload loss of the bolt after the equipment has been working for a period of time t.

[0079] The bolt vibration damage index LZS and the bolt expansion damage index LSZ are correlated to generate the preload loss index LSS. The formula is:

[0080]

[0081] Where F0 is the contact area between the bolt and the nut. A larger contact area indicates a less likely bolt to loosen. Larger bolt vibration damage indexes (LZS) and expansion damage indexes (LSZ) indicate a greater likelihood of bolt loosening. The preload loss index (LSS) reflects the extent of preload loss in the bolt after equipment operation time t. When a bolt is damaged by thermal expansion and vibration, it can loosen, leading to a decrease in tightening force. The preload loss index (LSS) reflects the magnitude of this decrease in tightening force. A larger LSS indicates a looser bolt and a greater risk of loosening. LZS1 / 2 is calculated by taking the square root of the vibration damage index to amplify the effect of vibration damage on preload while maintaining relative sensitivity to damage severity. ln(1+LSZ*t) represents the product of the expansion damage index and time using the natural logarithm, reflecting the increasing impact of expansion damage on preload loss over time. This logarithmic relationship also indicates that the impact of an increasing damage index gradually decreases, avoiding the linear amplification effect caused by an excessively high index.

[0082] S5. Compare the preload loss index LSS with the threshold θ and output the bolt safety level.

[0083] The preload loss index LSS when the bolt is loose is obtained through experiments. The minimum value is taken and set as the threshold θ. The preload loss index LSS is compared with the threshold θ to output the bolt safety level. When LSS ≥ θ, the output bolt safety level is level 2. At this time, the bolt is in danger of loosening and needs to be reloaded and tightened. When LSS < θ, the output bolt safety level is level 1. At this time, the bolt is relatively tight and there is no risk of loosening.

[0084] The vibration frequency and maximum acceleration of the equipment are collected through the vibration sensor, the vibration frequency is analyzed by MATLAB software, and the average vibration frequency is output. The mass of the object is collected through the weight sensor, and the mass of the object is the mass of the equipment.

[0085] Reference Figure 2 The present invention also provides a bolt preload force loading device for executing a bolt preload force loading method, comprising:

[0086] A temperature acquisition module is used to acquire bolt parameters and object parameters. The bolt parameters include the bolt's linear thermal expansion coefficient, initial length, and bolt operating temperature. The object parameters include the object's linear thermal expansion coefficient, initial thickness, and object operating temperature. A correlation analysis is performed on the bolt parameters to generate a bolt length change. A correlation analysis is performed on the object parameters to generate an object thickness change.

[0087] The temperature analysis module is used to perform correlation analysis on the change in bolt length and the change in object thickness to generate the temperature interference change. The temperature interference change Δ3 is then correlated with the bolt parameters to generate the bolt expansion damage index LSZ. The bolt expansion damage index LSZ reflects the damage caused to the bolt by the interference between the thermal expansion of the bolt and the object at the operating temperature.

[0088] A vibration acquisition module is used to collect vibration parameters of the equipment, including the average vibration frequency, mass, and maximum acceleration of the object, perform correlation analysis on the vibration parameters to generate vibration stress, and perform correlation analysis on the equipment operating time and average vibration frequency to generate the number of equipment operating cycles;

[0089] The vibration analysis module is used to perform correlation analysis on the data obtained by the vibration acquisition module to generate the bolt vibration damage degree index LZS. The bolt vibration damage degree index LZS is used to reflect the degree of damage to the bolts when the equipment vibrates;

[0090] The output module is used to perform correlation analysis on the bolt vibration damage index LZS and the bolt expansion damage index LSZ based on the equipment working time, and generate the preload loss index LSS. The preload loss index LSS is used to reflect the degree of preload loss of the bolt after the equipment working time t. The preload loss index LSS is compared with the threshold θ to output the bolt safety level.

[0091] The above formulas are all dimensionless and numerical calculations. The formulas are obtained by collecting a large amount of data and performing software simulation to obtain the most recent real situation. The preset parameters in the formulas are set by technicians in this field according to actual conditions.

[0092] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software depends on the specific application and design constraints of the technical solution.

[0093] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment as needed.

[0094] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

Claims

1. The method for loading bolt preload is characterized by: The specific steps include: S1. Collecting bolt parameters and object parameters, wherein the bolt parameters include the bolt linear thermal expansion coefficient, initial length, and bolt operating temperature; and the object parameters include the object linear thermal expansion coefficient, initial thickness, and object operating temperature; performing correlation analysis on the bolt parameters to generate a bolt length variation; and performing correlation analysis on the object parameters to generate an object thickness variation; S2. Perform correlation analysis on the bolt length variation and the object thickness variation to generate the temperature interference variation. Perform correlation analysis on the temperature interference variation Δ3 and the bolt parameters to generate the bolt expansion damage index LSZ. The bolt expansion damage index LSZ is used to reflect the damage caused to the bolt by the interference between the thermal expansion of the bolt and the object at the working temperature. S3. Collect vibration parameters of the equipment, including the average vibration frequency, mass, and maximum acceleration of the object, perform correlation analysis on the vibration parameters to generate vibration stress, perform correlation analysis on the equipment operating time and average vibration frequency to generate the number of equipment operating cycles, and generate a bolt vibration damage severity index LZS. The bolt vibration damage severity index LZS is used to reflect the degree of damage to the bolts caused by equipment vibration; S4. Combined with the equipment working time, the bolt vibration damage index LZS and the bolt expansion damage index LSZ are correlated and analyzed to generate the preload loss index LSS. The preload loss index LSS is used to reflect the degree of preload loss of the bolt after the equipment has been working for a period of time t. S5. Compare the preload loss index LSS with the threshold θ and output the bolt safety level.

2. The method for applying bolt preload according to claim 1, wherein: Bolts are used to tighten objects. The working temperature of the bolts, T1, and the working temperature of the object, T2, are measured using temperature sensors. The initial length of the bolts, L1, and the initial thickness of the object, L2, are measured using a vernier caliper. Based on the material properties of the bolts and the object, the linear thermal expansion coefficients of the bolts, α1, and α2, respectively, are queried. Correlation analysis is performed on the bolt parameters to generate the bolt length change, Δ1, using the following formula: Δ1=L1*α1*(T1-T s ) Among them, T s The bolt length change Δ1 is used to reflect the expansion amplitude of the bolt caused by heating at the working temperature. Perform correlation analysis on the object parameters to generate the object thickness variation Δ2 based on the following formula: Δ2=L2*α2*(T2-T s ) The object thickness variation Δ2 is used to reflect the expansion amplitude of the fastened object due to heat at the working temperature.

3. The method for applying bolt preload force according to claim 2, wherein: The correlation analysis between the bolt length change and the object thickness change is performed to generate the temperature interference change Δ3, based on the following formula: Δ3=|Δ2-Δ1| The temperature interference variation Δ3 is used to reflect the relative expansion of the bolt and the object at the working temperature; The correlation analysis of the temperature interference variation Δ3 and the bolt parameters is performed to generate the bolt expansion damage index LSZ. The formula is as follows: Among them, the bolt expansion damage index LSZ is used to reflect the damage caused to the bolt by the interference between the thermal expansion of the bolt and the object at the working temperature. E is the elastic modulus of the bolt, σ u is the ultimate strength of the bolt material, which is used to indicate the maximum stress that the material can withstand, σ Y is the yield strength of the bolt material, which is used to indicate the stress when the material begins to deform plastically. K1 is the stiffness of the bolt material, and K2 is the stiffness of the object material.

4. The method for applying bolt preload force according to claim 1, wherein: During operation, the vibration parameters of the equipment are collected, including the average vibration frequency f of the object, the mass m of the object and the maximum acceleration a max , perform correlation analysis on vibration parameters and generate vibration stress σ d , based on the formula: Where A is the cross-sectional area of ​​the bolt, N is the total number of bolts, and the vibration stress σ d Used to reflect the averaged stress generated by each bolt under the influence of vibration.

5. The method for applying bolt preload force according to claim 4, characterized in that: The correlation analysis of the equipment working time t and the average vibration frequency f is performed to generate the number of equipment working cycles M based on the following formula: M=t*f The number of equipment working cycles M is used to reflect the number of cyclic vibrations of the equipment, where the average vibration frequency f is the average vibration frequency of the equipment when it is working; The correlation analysis of the equipment working cycle number M is performed to generate the bolt vibration damage degree index LZS based on the following formula: Among them, C is the maximum number of vibration cycles that the bolt material can withstand, and the bolt vibration damage degree index LZS is used to reflect the degree of damage to the bolt when the equipment vibrates.

6. The method for applying bolt preload force according to claim 1, wherein: The bolt vibration damage index LZS and the bolt expansion damage index LSZ are correlated to generate the preload loss index LSS. The formula is: Among them, F0 is the contact area between the bolt and the nut, and the preload loss index LSS is used to reflect the degree of preload loss of the bolt after the equipment has been working for t.

7. The method for applying bolt preload force according to claim 6, characterized in that: The preload loss index LSS is compared with the threshold θ to output the bolt safety level. When LSS ≥ θ, the output bolt safety level is level 2. At this time, the bolt is in danger of loosening and needs to be reloaded and tightened. When LSS < θ, the output bolt safety level is level 1. At this time, the bolt is relatively tight and there is no risk of loosening.

8. The method for applying bolt preload force according to claim 1, wherein: The vibration frequency and maximum acceleration of the equipment are collected through the vibration sensor, the vibration frequency is analyzed by MATLAB software, and the average vibration frequency is output. The mass of the object is collected through the weight sensor, and the mass of the object is the mass of the equipment.

9. A bolt preload force loading device, used to execute the bolt preload force loading method according to claim 1, characterized in that: include: A temperature acquisition module is used to acquire bolt parameters and object parameters. The bolt parameters include the bolt's linear thermal expansion coefficient, initial length, and bolt operating temperature. The object parameters include the object's linear thermal expansion coefficient, initial thickness, and object operating temperature. A correlation analysis is performed on the bolt parameters to generate a bolt length change. A correlation analysis is performed on the object parameters to generate an object thickness change. The temperature analysis module is used to perform correlation analysis on the change in bolt length and the change in object thickness to generate the temperature interference change. The temperature interference change Δ3 is then correlated with the bolt parameters to generate the bolt expansion damage index LSZ. The bolt expansion damage index LSZ reflects the damage caused to the bolt by the interference between the thermal expansion of the bolt and the object at the operating temperature. A vibration acquisition module is used to collect vibration parameters of the equipment, including the average vibration frequency, mass, and maximum acceleration of the object, perform correlation analysis on the vibration parameters to generate vibration stress, and perform correlation analysis on the equipment operating time and average vibration frequency to generate the number of equipment operating cycles; The vibration analysis module is used to perform correlation analysis on the data obtained by the vibration acquisition module to generate the bolt vibration damage degree index LZS. The bolt vibration damage degree index LZS is used to reflect the degree of damage to the bolts when the equipment vibrates; The output module is used to perform correlation analysis on the bolt vibration damage index LZS and the bolt expansion damage index LSZ based on the equipment working time, and generate the preload loss index LSS. The preload loss index LSS is used to reflect the degree of preload loss of the bolt after the equipment working time t. The preload loss index LSS is compared with the threshold θ to output the bolt safety level.

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