Method and device for loading bolt pre-tightening force

Abstract

The application provides a bolt pre-tightening force loading method and device, and relates to the technical field of bolt pre-tightening force. The bolt pre-tightening force loading method comprises the following specific steps: collecting parameters, analyzing parameters, comprehensively analyzing, and outputting the bolt safety level. The working temperature and vibration parameters of the bolt are collected, the interference degree between the bolt and the object under the working temperature is analyzed, the damage degree of the bolt caused by the interference between the bolt and the object due to thermal expansion under the working temperature is analyzed, the bolt expansion damage index is output, the equipment vibration parameters are analyzed, the bolt vibration damage degree index reflecting the damage degree of the bolt when the equipment vibrates is generated, the correlation analysis is comprehensively analyzed, the pre-tightening force loss index reflecting the pre-tightening force loss degree of the bolt after the equipment working time t is generated, and then the bolt safety level is output.

Description

TECHNICAL FIELD

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

[0002] Bolt pre-tightening force refers to the initial tension applied in bolted connections to ensure that the contact surfaces between the connected parts remain tight. The presence of pre-tightening force can effectively improve the stability and safety of the structure. In engineering applications, appropriate pre-tightening force not only ensures the reliability of the connection, but also improves the load-carrying capacity of the bolt and prolongs its service life. The selection of pre-tightening force involves multiple factors, including the material, diameter, thread type of the bolt, and the properties of the connected parts. Too low pre-tightening force may cause the connection to loosen, while too high pre-tightening force may cause plastic deformation or even breakage of the bolt. Therefore, in design and installation, it is often necessary to determine the appropriate pre-tightening force through calculation and experiment. Therefore, in engineering practice, it is particularly important to monitor and maintain the pre-tightening force state of the bolt. Through regular inspection and necessary adjustment, the safety and reliability of the connection can be ensured, thereby effectively avoiding potential structural failures and safety hazards.

[0003] Generally, the pre-tightening force of the bolt is usually set at room temperature, but the working environment of the bolted equipment may not be at room temperature, and the temperature may be much higher than room temperature. At this time, the influence of thermal expansion on the performance of the bolt cannot be ignored. At the same time, when the equipment is working, the motor on it will vibrate the entire equipment regularly, and the vibration will also affect the bolt. Both vibration and high temperature can damage the bolt and cause it to loosen, resulting in a service life much lower than normal when the pre-tightening force is pre-set, thereby posing a risk.

[0004] The above information disclosed in the background section is only used to enhance the understanding of the background of the present disclosure, and therefore it can include information that does not constitute prior art known to those of ordinary skill in the art. SUMMARY

[0005] The purpose of the present application is to provide a bolt pre-tightening force loading method and device to solve the problems raised in the background.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] The bolt pre-tightening force loading method comprises the following specific steps:

[0008] S1, collect bolt parameters and object parameters, the bolt parameters including bolt linear thermal expansion coefficient, initial length, bolt working temperature, the object parameters including object linear thermal expansion coefficient, initial thickness, object working temperature, perform correlation analysis on the bolt parameters to generate bolt length change amount, perform correlation analysis on the object parameters to generate object thickness change amount;

[0009] S2, perform correlation analysis on the bolt length change amount and the object thickness change amount to generate temperature interference change amount, perform correlation analysis on the temperature interference change amount Δ3 and the bolt parameters to generate bolt expansion damage index LSZ, the bolt expansion damage index LSZ being used to reflect the damage size of the bolt caused by the interference between the bolt and the object due to thermal expansion of the bolt at the working temperature;

[0010] S3, perform correlation analysis on the equipment working time and the average vibration frequency to generate equipment working cycle number, and generate bolt vibration damage degree index LZS, the bolt vibration damage degree index LZS being used to reflect the damage degree of the bolt caused by the vibration of the equipment;

[0011] S4, in combination with the equipment working time, perform correlation analysis on the bolt vibration damage degree index LZS and the bolt expansion damage index LSZ to generate pretightening force loss index LSS, the pretightening force loss index LSS being used to reflect the pretightening force loss degree of the bolt after the equipment working time t;

[0012] S5, compare the pretightening force loss index LSS with a threshold value θ, and output bolt safety grade.

[0013] Further, the bolt fastens the object, the bolt working temperature T1 and the object working temperature T2 are measured by a temperature sensor, the bolt initial length L1 and the object initial thickness L2 are measured by a vernier caliper, the bolt linear thermal expansion coefficient α1 and the object linear thermal expansion coefficient α2 are respectively inquired according to the material properties of the bolt and the object, correlation analysis is performed on the bolt parameters to generate bolt length change amount Δ1, and the formula is:

[0014] Δ1=L1*α1*(T1-T s )

[0015] Wherein, T s is room temperature, and the bolt length change amount Δ1 is used to reflect the expansion amplitude of the bolt caused by heat at the working temperature;

[0016] Correlation analysis is performed on the object parameters to generate object thickness change amount Δ2, and the formula is:

[0017] Δ2=L2*α2*(T2-T s )

[0018] Wherein, the object thickness change amount Δ2 is used to reflect the expansion range of the fastened object due to heat at the working temperature.

[0019] Further, the bolt length change amount and the object thickness change amount are analyzed for correlation, and a temperature interference change amount Δ3 is generated, according to the formula:

[0020] Δ3 = |Δ2-Δ1|

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

[0022] The temperature interference change amount Δ3 and the bolt parameters are analyzed for correlation, and a bolt expansion damage index LSZ is generated, according to the formula:

[0023]

[0024] Wherein, the bolt expansion damage index LSZ is used to reflect the damage to the bolt caused by the interference between the bolt expansion 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, used to represent the maximum stress that the material can withstand, σ Y is the yield strength of the bolt material, used to represent the stress at which the material begins to plastically deform, K1 is the stiffness of the bolt material, and K2 is the stiffness of the object material.

[0025] Further, the device working time t and the average vibration frequency f are analyzed for correlation, and a device working cycle number M is generated, according to the formula:

[0026] M = t*f

[0027] The device working cycle number M is used to reflect the number of cycles of the device, wherein the average vibration frequency f is the average vibration frequency during the operation of the device.

[0028] The device working cycle number M is analyzed for correlation, and a bolt vibration damage degree index LZS is generated, according to the formula:

[0029]

[0030] Wherein, 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 damage degree of the bolt during the vibration of the device.

[0031] Further, the bolt vibration damage degree index LZS and the bolt expansion damage index LSZ are analyzed for correlation, and a preload loss index LSS is generated, according to the formula:

[0032]

[0033] Wherein, F0 is the contact area of the bolt and the nut, and the pre-tightening force loss index LSS is used to reflect the pre-tightening force loss degree of the bolt after the device working time t.

[0034] Further, the pre-tightening force loss index LSS is compared with the threshold value θ, and the bolt safety level is output, when LSS≥θ, the bolt safety level is level two, at this time, the bolt is loose and needs to be reloaded; when LSS<θ, the bolt safety level is level one, at this time, the bolt is relatively tight and has no risk of loosening.

[0035] Further, the vibration frequency and the maximum acceleration of the device are collected by the vibration sensor, the vibration frequency is analyzed by the matlab software, and the average vibration frequency is output, and the object quality is collected by the weight sensor, and the object quality is the device quality.

[0036] The application also provides a bolt pre-tightening force loading device for executing the bolt pre-tightening force loading method, which comprises:

[0037] A temperature collection module is used to collect bolt parameters and object parameters, the bolt parameters include bolt linear thermal expansion coefficient, initial length and bolt working temperature, and the object parameters include object linear thermal expansion coefficient, initial thickness and object working temperature, the bolt parameters are analyzed for correlation, and the bolt length change amount is generated, and the object parameters are analyzed for correlation, and the object thickness change amount is generated;

[0038] A temperature analysis module is used to analyze the bolt length change amount and the object thickness change amount for correlation, and generate the temperature interference change amount Δ3, and analyze the temperature interference change amount Δ3 and the bolt parameters for correlation, and generate the bolt expansion damage index LSZ, which is used to reflect the damage size of the bolt caused by the interference between the bolt thermal expansion and the object under the working temperature;

[0039] A vibration collection module is used to analyze the device working time and the average vibration frequency for correlation, and generate the device working cycle number, and generate the bolt vibration damage degree index LZS, which is used to reflect the damage degree of the bolt caused by the device vibration;

[0040] A vibration analysis module is used to analyze the bolt vibration damage degree index LZS and the bolt expansion damage index LSZ for correlation in combination with the device working time, and generate the pre-tightening force loss index LSS, which is used to reflect the pre-tightening force loss degree of the bolt after the device working time t.

[0041] An output module is used to compare the pre-tightening force loss index LSS with the threshold value θ, and output the bolt safety level.

[0042] Compared with the prior art, the present application has the beneficial effects that:

[0043] The present application collects the working temperature and vibration parameters of the bolt, respectively analyzes the interference degree between the bolt and the object at the working temperature, analyzes the damage degree of the bolt caused by the interference between the bolt and the object due to thermal expansion at the working temperature, outputs the bolt expansion damage index, analyzes the equipment vibration parameters, generates the bolt vibration damage degree index for reflecting the damage degree of the bolt when the equipment vibrates, and generates the pretightening force loss index for reflecting the pretightening force loss degree of the bolt after the equipment working time t after the comprehensive correlation analysis, and then outputs the bolt safety level. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 It is a whole method flowchart of the present application;

[0045] Figure 2 It is a whole system flowchart of the present application. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with specific embodiments.

[0047] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present application should be understood as the general meaning understood by those skilled in the art to which the present application belongs. The "first", "second" and similar words used in the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Include" or "contain" and similar words mean that the elements or objects before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connected" or "connected" and similar words are not limited to physical or mechanical connection, but can include electrical connection, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to represent relative positional relationship, when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0048] EMBODIMENT:

[0049] Please refer to Figure 1 The present application provides a technical scheme:

[0050] The bolt pretightening force loading method specifically includes the following steps:

[0051] S1, in order to analyze the influence of temperature change on the interference of the bolt and the object during the operation of the device, collect the bolt parameters and the object parameters, the bolt parameters include the linear thermal expansion coefficient of the bolt, the initial length, the working temperature of the bolt, the working temperature of the bolt is the average temperature of the bolt during the normal operation of the device, the object parameters include the linear thermal expansion coefficient of the object, the initial thickness, the working temperature of the object, the correlation analysis is performed on the bolt parameters, the bolt length change amount is generated, the correlation analysis is performed on the object parameters, and the object thickness change amount is generated;

[0052] Wherein the bolt is used for fastening the object, the working temperature T1 of the bolt and the working temperature T2 of the object are measured by the temperature sensor, since the device works stably, the working temperature of the bolt and the working temperature of each bolt position are constant, and the change is within a controllable range, therefore, when collecting the parameters, the working temperature is taken as the average value, the initial length L1 of the bolt and the initial thickness L2 of the object are measured by the vernier caliper, the linear thermal expansion coefficient α1 of the bolt and the linear thermal expansion coefficient α2 of the object are respectively inquired according to the material characteristics of the bolt and the object, the correlation analysis is performed on the bolt parameters, and the bolt length change amount Δ1 is generated, and the formula is as follows:

[0053] Δ1=L1*α1*(T1-T s )

[0054] Wherein, T s is the room temperature, and the bolt length change amount Δ1 is used for reflecting the expansion range of the bolt due to heating at the working temperature, the greater the value of the bolt length change amount Δ1, the higher the expansion degree of the bolt;

[0055] The correlation analysis is performed on the object parameters, and the object thickness change amount Δ2 is generated, and the formula is as follows:

[0056] Δ2=L2*α2*(T2-T s )

[0057] Wherein, the object thickness change amount Δ2 is used for reflecting the expansion range of the object due to heating at the working temperature, the greater the value of the object thickness change amount Δ2, the higher the expansion degree of the object.

[0058] S2, the correlation analysis is performed on the bolt length change amount and the object thickness change amount, the temperature interference change amount is generated, the correlation analysis is performed on the temperature interference change amount Δ3 and the bolt parameters, the bolt expansion damage index LSZ is generated, and the bolt expansion damage index LSZ is used for reflecting the damage size of the bolt caused by the interference between the bolt expansion and the object at the working temperature;

[0059] Since the pre-tightening force is only obtained by measurement at room temperature, when the temperature changes, the expansion interference will lose the pre-tightening force, the expansion coefficients of the bolt and the fastened object are different when the materials of the bolt and the fastened object are different, and the expansion degree is different even if the heating is the same, since the bolt and the object are closely connected, when the expansion degrees of the bolt and the object are different, interference will be generated between them, thereby negatively affecting the bolt, and then losing the pre-tightening force, specifically, the correlation between the bolt length change amount and the object thickness change amount is analyzed to generate a temperature interference change amount Δ3, and the formula is:

[0060] Δ3 = |Δ2-Δ1|

[0061] The temperature interference change amount Δ3 is used to reflect the relative expansion amount of the bolt and the object at the working temperature, and the temperature interference change amount Δ3 is used to reflect the expansion contrast amount of the bolt and the object at the working temperature;

[0062] The correlation between the temperature interference change amount Δ3 and the bolt parameters is analyzed to generate a bolt expansion damage index LSZ, and the formula is:

[0063]

[0064] Wherein, the bolt expansion damage index LSZ is used to reflect the damage of the bolt caused by the interference between the bolt and the object due to the thermal expansion 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 represent the maximum stress that the material can withstand, σ Y is the yield strength of the bolt material, which is used to represent the stress at which 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 of the bolt material and the yield strength of the bolt material are obtained by mechanical property test experiment, Δ3 / L1 reflects the interference deformation degree of the bolt and the object, and the product of Δ3 / L1 and the elastic modulus E represents the deformation stress of the bolt and the object. The damage degree is obtained by analyzing the proportion of the maximum stress that can be withstood, and the ratio of the stiffness of the bolt material to the stiffness of the object material is used to represent the damage coefficient when the bolt and the object are expanded and interfered. The greater the bolt expansion damage index LSZ, the deeper the influence of the interference between the bolt and the object due to the thermal expansion.

[0065] S3, generally, when the equipment is working, the motor on the equipment will cause the equipment to vibrate, and the vibration frequency is relatively stable, and the vibration will have a negative impact on the bolt. The correlation between the equipment working time and the average vibration frequency is analyzed to generate the equipment working cycle number, and the bolt vibration damage degree index LZS is generated. The bolt vibration damage degree index LZS is used to reflect the damage degree of the bolt when the equipment vibrates. The equipment working time is the time for collecting vibration parameters when the equipment is normally working;

[0066] Correlation analysis is performed on the device working time t and the average vibration frequency f to generate the device working cycle number M, and the formula is:

[0067] M = t * f

[0068] The device working cycle number M is used to reflect the number of device cycle vibrations, wherein the average vibration frequency f is the average vibration frequency during device working time;

[0069] Correlation analysis is performed on the device working cycle number M to generate the bolt vibration damage degree index LZS, and the formula is:

[0070]

[0071] Wherein C is the maximum vibration cycle number that the bolt material can withstand, the bolt vibration damage degree index LZS is used to reflect the damage degree of the device vibration to the bolt, the larger the value is, the higher the damage degree is, and when the bolt vibration damage degree index LZS is greater than 1, it indicates that the bolt is loosened due to vibration, at this time it cannot be used, wherein the maximum vibration cycle number C is obtained by experiment test, specifically: prepare a standard bolt sample, ensure that its material and size are the same as the bolt actually used, use a fatigue testing machine to apply the same alternating stress as σ d , determine the vibration frequency, stress and test room temperature, perform cycle loading under the set conditions, record the cycle number of each sample before fracture, draw a stress-cycle number curve, and then determine the cycle number under the stress σ d , which is recorded as the maximum vibration cycle number C.

[0072] S4, in combination with the device working time, correlation analysis is performed on the bolt vibration damage degree index LZS and the bolt expansion damage index LSZ to generate the pretightening force loss index LSS, and the pretightening force loss index LSS is used to reflect the pretightening force loss degree of the bolt after the device working time t;

[0073] Correlation analysis is performed on the bolt vibration damage degree index LZS and the bolt expansion damage index LSZ to generate the pretightening force loss index LSS, and the formula is:

[0074]

[0075] Wherein, F0 is the contact area of the bolt and the nut, the larger the contact area is, the less likely the bolt is to loosen, and the larger the bolt vibration damage index LZS and the bolt expansion damage index LSZ are, the more likely the bolt is to loosen, the pre-tightening force loss index LSS is used to reflect the degree of pre-tightening force loss of the bolt after the equipment working time t, when the bolt is damaged by thermal expansion and vibration, it will loosen and further cause the fastening force to decrease, the pre-tightening force loss index LSS is used to reflect the size of the decrease of the fastening force of the bolt, the larger the pre-tightening force loss index LSS is, the more loose the bolt is, at this time, the greater the risk of bolt loosening is, LZS 1 / 2 The square root of the vibration damage index is taken, so that the influence of vibration damage on the pre-tightening force can be amplified, and the relative sensitivity to the damage degree is maintained, and the product of the expansion damage index and the time is processed by using the natural logarithm, which reflects that the influence of the expansion damage on the pre-tightening force loss gradually increases over time. This logarithmic relationship also shows that the influence of the damage index increase gradually weakens, avoiding the linear amplification effect caused by the excessively high index.

[0076] S5, comparing the pre-tightening force loss index LSS with the threshold value θ, and outputting the bolt safety level.

[0077] The pre-tightening force loss index LSS of the bolt loosening is obtained through experiments, the minimum value is taken, and the value is set as the threshold value θ, the pre-tightening force loss index LSS is compared with the threshold value θ, and the bolt safety level is output, when LSS is greater than or equal to θ, the bolt safety level is level two, at this time, the bolt is in danger of loosening and needs to be reloaded and fastened, when LSS is less than θ, the bolt safety level is level one, at this time, the bolt is relatively fastened and has no risk of loosening.

[0078] The vibration frequency and the maximum acceleration of the equipment are collected by the vibration sensor, the vibration frequency is analyzed by using the matlab software, and the average vibration frequency is output, and the object quality is collected by the weight sensor, and the object quality is the equipment quality.

[0079] Referring to Figure 2 The application also provides a bolt pre-tightening force loading device for executing the bolt pre-tightening force loading method, which comprises:

[0080] A temperature collection module is configured to collect bolt parameters and object parameters, the bolt parameters include a bolt linear thermal expansion coefficient, an initial length and a bolt working temperature, and the object parameters include an object linear thermal expansion coefficient, an initial thickness and an object working temperature, the bolt parameters are subjected to correlation analysis to generate a bolt length change amount, and the object parameters are subjected to correlation analysis to generate an object thickness change amount.

[0081] The temperature analysis module is used for correlation analysis on the bolt length change amount and the object thickness change amount, generates a temperature interference change amount, and performs correlation analysis on the temperature interference change amount and the bolt parameter, to generate a bolt expansion damage index LSZ, which is used for reflecting the damage size of the bolt caused by the thermal expansion of the bolt and the interference of the object at the working temperature.

[0082] The vibration collection module is used for correlation analysis on the device working time and the average vibration frequency, to generate a device working cycle number and a bolt vibration damage degree index LZS, which is used for reflecting the damage degree of the bolt caused by the device vibration.

[0083] The vibration analysis module is used for correlation analysis on the bolt vibration damage degree index LZS and the bolt expansion damage index LSZ in combination with the device working time, to generate a pretightening force loss index LSS, which is used for reflecting the pretightening force loss degree of the bolt after the device working time t.

[0084] The output module is used for comparison between the pretightening force loss index LSS and a threshold value θ, and outputs a bolt safety level.

[0085] The above formulas are all dimensionless numerical calculations, the formulas are obtained by software simulation of a large number of collected data, and the preset parameters in the formulas are set by the person skilled in the art according to the actual situation.

[0086] The above embodiments can be realized by software, hardware, firmware or any combination thereof, in whole or in part. When realized by software, the above embodiments can be realized in the form of a computer program product in whole or in part. Those skilled in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized by hardware or software methods depends on the specific application and design constraints of the technical solutions.

[0087] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, which can be located in one place or distributed on multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0088] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered within the protection scope of the present application.

Claims

1. Method for loading of the bolt pretension, characterized in that, The specific steps include: S1, collecting bolt parameters and object parameters, the bolt parameters including bolt linear thermal expansion coefficient, initial length, bolt working temperature, the object parameters including object linear thermal expansion coefficient, initial thickness, object working temperature, performing correlation analysis on the bolt parameters to generate bolt length change, performing correlation analysis on the object parameters to generate object thickness change; S2, performing correlation analysis on the bolt length change and the object thickness change to generate temperature interference change, performing correlation analysis on the temperature interference change Δ3 and the bolt parameters to generate bolt expansion damage index LSZ, the bolt expansion damage index LSZ being used to reflect the damage size of the bolt caused by the interference between the bolt and the object due to thermal expansion at the working temperature; S3, performing correlation analysis on the equipment working time and the average vibration frequency to generate equipment working cycle number, and generating bolt vibration damage degree index LZS, the bolt vibration damage degree index LZS being used to reflect the damage degree of the bolt caused by the equipment vibration; The bolt expansion damage index LSZ is obtained by performing correlation analysis on the temperature interference change Δ3 and the bolt parameters, and the formula is: wherein the bolt expansion damage index LSZ is used to reflect the damage size of the bolt caused by the interference between the bolt and the article due to the thermal expansion of the bolt at the working temperature, E is the elastic modulus of the bolt, σ u is the ultimate strength of the bolt material, used to indicate the maximum stress that the material can withstand, σ Y is the yield strength of the bolt material, used to indicate the stress at which the material begins to plastically deform, K1 is the stiffness of the bolt material, and K2 is the stiffness of the article material; S4, performing correlation analysis on the bolt vibration damage degree index LZS and the bolt expansion damage index LSZ in combination with the equipment working time to generate pretightening force loss index LSS, the pretightening force loss index LSS being used to reflect the pretightening force loss degree of the bolt after the equipment working time t; The bolt vibration damage degree index LZS is obtained by performing correlation analysis on the equipment working cycle number M, and the formula is: Wherein, C is the maximum vibration cycle number that the bolt material can withstand, and the bolt vibration damage degree index LZS is used to reflect the damage degree of the bolt caused by the equipment vibration; The pretightening force loss index LSS is obtained by performing correlation analysis on the bolt vibration damage degree index LZS and the bolt expansion damage index LSZ, and the formula is: Wherein, F0 is the contact area of the bolt and the nut, and the pretightening force loss index LSS is used to reflect the pretightening force loss degree of the bolt after the equipment working time t; S5, comparing the pretightening force loss index LSS with the threshold θ, and outputting the bolt safety level.

2. The method of claim 1, wherein: The bolt is used to fasten the object, the bolt working temperature T1 and the object working temperature T2 are measured by a temperature sensor, the initial length L1 of the bolt and the initial thickness L2 of the object are measured by a vernier caliper, the bolt linear thermal expansion coefficient α1 and the object linear thermal expansion coefficient α2 are respectively queried according to the material properties of the bolt and the object, correlation analysis is performed on the bolt parameters to generate bolt length change Δ1, and the formula is: Δ1 = L1*α1*(T1-T s ) wherein T s is room temperature, and the bolt length change amount Δ1 is used to reflect the expansion range of the bolt due to heating at the working temperature; Correlation analysis is performed on the object parameters to generate object thickness change Δ2, and the formula is: Δ2 = L2*α2*(T2-T s ) Wherein, the object thickness change Δ2 is used to reflect the expansion amplitude of the fastened object caused by heat at the working temperature.

3. The method of claim 2, wherein: Correlation analysis is performed on the bolt length change and the object thickness change to generate temperature interference change Δ3, and the formula is: Δ3 = | Δ2 - Δ1 | The temperature interference change amount Δ3 is used for reflecting the relative expansion amount of the bolt and the object at the working temperature.

4. The method of claim 1, wherein: The correlation analysis is performed on the equipment working time t and the average vibration frequency f to generate the equipment working cycle number M according to the formula: M=t*f The equipment working cycle number M is used for reflecting the number of cyclic vibrations of the equipment, wherein the average vibration frequency f is the average vibration frequency during the working of the equipment.

5. The method of claim 1, wherein: The pre-tightening force loss index LSS is compared with the threshold value θ, and the bolt safety level is outputted.

6. The method of claim 1, wherein: The vibration frequency and the maximum acceleration of the equipment are collected by the vibration sensor, the vibration frequency is analyzed by the matlab software, and the average vibration frequency is outputted, and the object mass is collected by the weight sensor, and the object mass is the equipment mass.

7. A bolt pre-tightening force applying device for carrying out the bolt pre-tightening force applying method according to claim 1, characterized by, The temperature collection module is used for collecting the bolt parameters and the object parameters, the bolt parameters include the bolt linear thermal expansion coefficient, the initial length and the bolt working temperature, the object parameters include the object linear thermal expansion coefficient, the initial thickness and the object working temperature, the correlation analysis is performed on the bolt parameters to generate the bolt length change amount, and the correlation analysis is performed on the object parameters to generate the object thickness change amount. The temperature analysis module is used for performing the correlation analysis on the bolt length change amount and the object thickness change amount to generate the temperature interference change amount, and performing the correlation analysis on the temperature interference change amount Δ3 and the bolt parameters to generate the bolt expansion damage index LSZ, and the bolt expansion damage index LSZ is used for reflecting the damage size of the bolt caused by the interference between the bolt thermal expansion and the object at the working temperature. The vibration collection module is used for performing the correlation analysis on the equipment working time and the average vibration frequency to generate the equipment working cycle number, and generating the bolt vibration damage degree index LZS, and the bolt vibration damage degree index LZS is used for reflecting the damage degree of the bolt during the vibration of the equipment. The vibration analysis module is used for performing the correlation analysis on the bolt vibration damage degree index LZS and the bolt expansion damage index LSZ in combination with the equipment working time to generate the pre-tightening force loss index LSS, and the pre-tightening force loss index LSS is used for reflecting the pre-tightening force loss degree of the bolt after the equipment working time t. The output module is used for comparing the pre-tightening force loss index LSS with the threshold value θ, and outputting the bolt safety level. ​

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