A fixed-axis force construction device for real-time detection of bolt pretightening force

Abstract

The application provides a kind of real-time detection bolt pre-tightening force fixed axle force construction device, it is related to bolt detection and control technical field, the application can monitor the temperature change of each part of bolt in real time by temperature data acquisition module, and form historical temperature change data set;Second, by warning threshold setting module, according to the average temperature and historical data of each part of bolt, set warning threshold, ensure the stability and reliability of bolt pre-tightening force under different environmental temperature;Further, by index generation module, comprehensive consideration environmental temperature, assignment evaluation coefficient and thermal expansion coefficient, generate pre-tightening force fine tuning index, the pre-tightening force of bolt after current applied torque is compensated and fine tuned, realizes the dynamic adjustment and accurate control of pre-tightening force.

Description

Technical Field

[0001] This invention relates to the field of bolt detection and control technology, specifically a fixed-axis force construction device for real-time detection of bolt preload. Background Technology

[0002] The torque output of a torque wrench, after passing through the nut, washer, connected parts, and threaded pair, acts as an effective preload on the bolt's axial direction. However, due to differences in transmission, the effective preload often fails to reach the design value. Using the same torque coefficient for tightening makes it difficult to ensure consistency in axial preload, a key factor in "under-tightened" or "over-tightened" bolts. Under-tightened bolts cannot function properly in terms of axial tensile strength. High-strength bolts inherently have relatively weak shear strength, making them prone to slippage of connected parts and bolt shearing during use. Over-tightened bolts, on the other hand, have insufficient remaining tensile strength and insufficient design margin, making them unable to withstand instantaneous high loads. Based on the following linked content, the relationship between bolt calibration data and ultrasonic transit time (elongation, axial force) is established. Calibration test data is obtained, and a compilation document is established to provide data support for subsequent axial force baseline tests.

[0003] The UHW (Ultra-Hard Drive) is a high-precision bolt tightening tool designed for industrial applications. It features a typical electro-hydraulic servo integrated control system. The UHW mainly consists of: a servo control system, a hydraulic drive unit, an ultrasonic axial force measurement unit, an ultrasonic sensor, a wrench, an embedded main controller, an industrial panel PC (PAD), and software. By introducing an ultrasonic sensor, it measures the bolt's axial preload in real time during tightening and feeds this data back to the electro-hydraulic servo system to control the wrench. Because it measures the direct axial force, it avoids the influence of friction from the threaded joint and errors from the connecting end faces, achieving high-precision preload control.

[0004] The entire system works as follows: The user places the wrench on the nut, places the ultrasonic sensor on one end of the bolt, inputs the bolt parameters and target preload on the human-machine interface PAD, and starts tightening. The system controller sends working instructions to the hydraulic pump and ultrasonic force measuring unit. The hydraulic pump drives the wrench to tighten the nut or bolt. The ultrasonic force measuring unit measures the bolt axial force value in real time and feeds it back to the controller. After feedback calculation, the controller precisely controls the hydraulic pump pressure output. When the error between the measured bolt preload and the set value is within the accuracy allowable range, the controller issues a stop tightening command, and the bolt tightening ends. The entire tightening process does not require human intervention and automatically tightens to the set preload.

[0005] In the prior art, a bolt pretightening force monitoring and control method based on ultrasonic single wave technology is disclosed in CN117824902A. The calibrated speed of the bolt is obtained, the initial ultrasonic wave propagation time of the bolt is detected using ultrasonic single wave, and the initial length of the bolt is calculated. The torque is applied to the bolt by starting the construction tool, the ultrasonic wave propagation time is detected in real time using ultrasonic single wave, the actual length of the bolt after the i-th detection is calculated, and the length change amount before and after the bolt is stressed is calculated. According to the bolt calibration data, the absolute value of the bolt pretightening force after the current applied torque of the bolt is calculated. It is judged whether the absolute value of the current bolt pretightening force has reached the target pretightening force range. If not, continue to apply torque and calculate the absolute value of the bolt pretightening force until the target pretightening force range is reached.

[0006] At present, most detection methods have poor adaptability to environmental temperature changes and cannot monitor and adjust the temperature changes of each part of the bolt in real time. Temperature changes will directly affect the thermal expansion coefficient of the bolt, thereby causing the deviation of the pretightening force. Secondly, the existing technology has a lag in data acquisition and analysis processing, and cannot realize real-time monitoring and dynamic adjustment of the bolt pretightening force, resulting in a decrease in the precision and reliability of the pretightening force control. In addition, the existing technology lacks systematicness and intelligence in setting the warning threshold and fine-tuning the pretightening force, and cannot accurately compensate and adjust the pretightening force according to the historical data and current working conditions of the bolt.

[0007] The above information disclosed in the above background section is only used to strengthen 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

[0008] The purpose of the present application is to provide a fixed-axis force construction device for real-time detection of bolt pretightening force to solve the problems raised in the above background.

[0009] To achieve the above purpose, the present application provides the following technical solutions:

[0010] A fixed-axis force construction device for real-time detection of bolt pretightening force, which comprises a pretightening force detection control system using ultrasonic technology, specifically comprising:

[0011] Calibration module: used for calibrating the collection times of real-time ultrasonic detection to form a set {1, 2, …, i, …, n}, wherein i represents the index of the i-th data collection, n represents the index of the current n-th data collection, and i∈{1, 2, …, n};

[0012] Temperature data acquisition module: In the i-th data acquisition, it acquires the thermal expansion coefficient of the bolt, and obtains the temperature of the bolt head, the temperature of the bolt thread, the temperature of the nut, the temperature of the bolt tail, and the ambient temperature near the bolt, forming the i-th temperature detection dataset, and uploads the dataset to the database to record the historical temperature change data of each part of the bolt.

[0013] Calibration data acquisition module: used to collect the corresponding bolt calibration data in the i-th data acquisition, and upload the i-th bolt calibration data to the database to form a historical calibration data change set of the bolt;

[0014] Warning threshold setting module: used to transmit the collected historical temperature change data to the controller for processing, to calculate the average temperature of each part of the bolt under the current ambient temperature, and to set the warning threshold of each part of the bolt based on these average temperatures;

[0015] Adjustment module: Used to compare and analyze the temperature data of various parts of the bolt obtained from the current nth data acquisition with the corresponding warning threshold, and construct an evaluation coefficient. The evaluation coefficient is used to provide a dynamic adjustment strategy for the measured thermal expansion coefficient of the bolt.

[0016] Preload calculation module: used to transmit the bolt calibration data collected for the nth time to the controller for processing, in order to calculate the bolt preload after the current applied torque, and set the target preload range for the current bolt;

[0017] Index generation module: used to obtain the ambient temperature of the current nth acquisition, the assigned evaluation coefficient and the dynamically adjusted coefficient of thermal expansion, and to analyze and process them to generate the preload fine-tuning index. The preload fine-tuning index is used to provide a compensation fine-tuning strategy for the bolt preload after the current applied torque.

[0018] Post-processing module: After the bolt preload is adjusted through a compensation fine-tuning strategy, the hydraulic pump output in the fixed-axis force construction device is controlled to make the actual preload reach the compensated preload, and it is maintained within the set target preload range during the subsequent tightening process until the tightening is completed.

[0019] Furthermore, the preload fine-tuning index is defined as P. n The calculation formula is as follows:

[0020]

[0021] Among them, P n is the preload fine-tuning index generated in the nth data acquisition; m is the total number of parts detected on the bolt;

[0022] E j,n T is the evaluation coefficient assigned to the j-th part in the nth data acquisition;5,n Rx′ represents the ambient temperature during the nth data acquisition; T0 is the reference temperature value used to normalize the effect of temperature changes; n It is the dynamically adjusted coefficient of thermal expansion; E max To assign the maximum value of the evaluation coefficient;

[0023] k1 is an adjustment factor that determines the sensitivity of the preload fine-tuning index; 0.12 ≤ k1 ≤ 0.68; P is set... n The range of values ​​is 0. <P n ≤M, where M is the maximum value set according to the specific application;

[0024] Set the preload fine-tuning index P n The comparison threshold is U1, and 0.32≤U1≤0.76. The initial baseline value of U1 is set to 0.52.

[0025] When the preload fine-tuning index P n When U1 is greater than 1, the compensation fine-tuning strategy formula is:

[0026] ΔF n =δ1·(P n -U1)·F n

[0027] Where, ΔF n δ1 is the preload force that needs to be compensated; δ1 is the first compensation adjustment coefficient, and the value of δ1 is 0.1≤δ1≤0.3;

[0028] It was explained that the current preload is too high and needs to be compensated by reducing the preload, and the compensation amount is related to P. n -U1 is directly proportional;

[0029] When the preload fine-tuning index P n When =U1, the compensation fine-tuning strategy formula is:

[0030] ΔF n =δ2·F n

[0031] Wherein, δ2 is the second compensation adjustment coefficient, 0.01≤δ2≤0.07, which means that a small amount of fine adjustment is made, and the preload is within the expected range, so a small amount of compensation adjustment is made;

[0032] When the preload fine-tuning index P n When U1 < U1, the compensation fine-tuning strategy formula is:

[0033] ΔF n =δ3·(U1-P n )·F n

[0034] Wherein, the third compensation adjustment coefficient is δ3, and the value range of δ3 is 0.2≤δ3≤0.4, and it is explained that the current pre-tightening force is low, and compensation needs to be made by increasing the pre-tightening force; the compensation amount is proportional to U1-P n .

[0035] Compared with the prior art, the beneficial effects of the present application are: through the temperature data acquisition module, the temperature changes of each part of the bolt can be monitored in real time, and a historical temperature change data set is formed; secondly, through the warning threshold setting module, the warning threshold is set according to the average temperature and historical data of each part of the bolt, to ensure the stability and reliability of the bolt pre-tightening force under different environmental temperatures; thirdly, through the index generation module, the environmental temperature, the evaluation coefficient and the thermal expansion coefficient are comprehensively considered to generate a pre-tightening force fine-tuning index, to compensate and fine-tune the bolt pre-tightening force after the current torque is applied, and realize dynamic adjustment and accurate control of the pre-tightening force. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is a whole flowchart of the present application. DETAILED DESCRIPTION

[0037] 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.

[0038] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present application should be understood as the usual 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 the relative positional relationship, when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0039] Example 1:

[0040] Please refer to Figure 1 , the present application provides a technical scheme:

[0041] A real-time bolt pre-tightening force detection and fixed shaft force construction device, the device comprises a pre-tightening force detection and control system applying ultrasonic technology, specifically comprising:

[0042] Calibration module: used for calibrating the collection times of real-time ultrasonic detection, forming a set {1, 2, …, i, …, n}, wherein i represents the index of the ith data collection, n represents the index of the current nth data collection, and i∈{1, 2, …, n};

[0043] Temperature data collection module: used for collecting the thermal expansion coefficient of the bolt in the ith data collection, and obtaining the bolt head temperature, bolt thread part temperature, nut temperature, bolt tail temperature and ambient temperature near the bolt, forming the ith temperature detection data set, and uploading the data set to the database to record the historical temperature change data of each part of the bolt;

[0044] Calibration data collection module: used for collecting the corresponding bolt calibration data in the ith data collection, and uploading the ith bolt calibration data to the database to form the historical calibration data change set of the bolt;

[0045] Warning threshold setting module: used for transmitting the collected historical temperature change data to the controller for processing to calculate the average temperature of each part of the bolt under the current ambient temperature, and setting the warning threshold of each part of the bolt according to the average temperature;

[0046] Adjustment module: used for comparing and analyzing the temperature data of each part of the bolt obtained by the current nth data collection with the corresponding warning threshold to obtain the assignment result of each part of the bolt, and analyzing and processing the assignment result of each part of the bolt to construct an assignment evaluation coefficient, which is used to provide a dynamic adjustment strategy for the measured thermal expansion coefficient of the bolt;

[0047] Pre-tightening force calculation module: used for transmitting the bolt calibration data collected in the nth time to the controller for processing to calculate the bolt pre-tightening force after the current applied torque, and setting the target pre-tightening force range of the current bolt;

[0048] Exponent generation module: used for obtaining the ambient temperature, assignment evaluation coefficient and dynamically adjusted thermal expansion coefficient collected in the current nth time, and performing analysis and processing to generate a pre-tightening force fine-tuning index, which is used to provide a compensation fine-tuning strategy for the bolt pre-tightening force after the current applied torque;

[0049] Post-processing module: after the bolt pre-tightening force is adjusted by the compensation fine-tuning strategy, the hydraulic pump in the fixed shaft force construction device is controlled to output, so that the actual pre-tightening force reaches the compensated pre-tightening force, and the adjusted pre-tightening force is maintained within the set target pre-tightening force range in the subsequent tightening process until the tightening is completed.

[0050] Further, in the i-th data collection, the thermal expansion coefficient, the bolt head temperature, the bolt thread portion temperature, the nut temperature, the bolt tail temperature and the ambient temperature near the bolt are sequentially marked as Rx i , T 1,i , T 2,i , T 3,i , T 4,i , T 5,i ;

[0051] The bolt calibration data includes the elastic modulus E, the initial length L0 of the bolt, the calibration speed v calibration , and the actual length L i of the bolt in the i-th data collection;

[0052] The elastic modulus E represents the stiffness of the material, that is, the degree of deformation of the material under stress;

[0053] The initial length L0 of the bolt is the length of the bolt in the unstressed state;

[0054] The cross-sectional area A of the bolt is calculated according to the diameter of the bolt;

[0055] The calibration speed v calibration is the speed of ultrasonic wave propagation in the bolt in the stress-free state;

[0056] 4) Calibration data:

[0057] Data obtained through laboratory or field tests to calibrate the ultrasonic measurement system; these data include the ultrasonic propagation time and the bolt length change measured under a known preload;

[0058] Calculate the average temperature of each part of the bolt at the current ambient temperature, and set the warning threshold for each part of the bolt according to the average temperature, which includes:

[0059] The bolt tail is the end of the bolt rod, away from the nut, this part is stressed but has less friction, and the temperature change is relatively small;

[0060] The nut is a fitting installed on the bolt threads, and the friction between the nut and the bolt threads generates heat, resulting in a large temperature rise;

[0061] The bolt head is the top of the bolt, which directly contacts the fixed axial force construction device, and this part is mainly affected by the friction and pressure of the wrench or fixed axial force construction device, resulting in a large temperature rise;

[0062] The bolt thread is the threaded area on the bolt rod, which directly cooperates with the nut, and due to the friction between the bolt and the nut, the thread portion generates heat, resulting in a large temperature rise;

[0063] Set represents the average temperature of different parts of the bolt, wherein j∈{1,2,3,4}, 1,2,3,4 respectively correspond to the bolt head, the bolt thread part, the nut, the bolt tail and the ambient temperature near the bolt, The calculation formula is as follows:

[0064]

[0065] wherein i represents the i-th data acquisition, and n represents the current n-th data acquisition;

[0066] Set as the average temperature under the current ambient temperature, the calculation formula is as follows:

[0067]

[0068] wherein T 5,i represents the ambient temperature of the i-th acquisition;

[0069] According to the calculated average temperature of each part, a warning threshold is set, and the setting formula of the warning threshold is as follows:

[0070]

[0071] wherein H j represents the warning threshold of the j-th part of the bolt, and ΔT j is a temperature increment set according to the safety standard of the j-th part of the bolt, to ensure that the temperature of the j-th part of the bolt does not exceed the safety range under the change of external environment;

[0072] The calculation formula of ΔT j is as follows:

[0073]

[0074] wherein ΔT j is the temperature increment of the j-th part of the bolt, to ensure that the temperature of the part does not exceed the safety range; α j is a temperature change coefficient of the j-th part of the bolt, and the value range is 0<α j ≤1, which reflects the temperature change degree of different parts; ΔT max is a predetermined maximum temperature increment, which is a maximum allowed temperature increment set according to the bolt material and the environment, and ΔT max and α j are specifically determined according to the experimental data analysis of the expert group, which will not be described here;

[0075] According to the reasons and degrees of temperature change of different parts, the temperature change coefficient α j of each part of the bolt is set as follows:

[0076] For the bolt tail (also called the bolt bottom), the temperature change is relatively small due to force but small friction; set α4=0.2;

[0077] For the nut, the temperature rises greatly due to the friction with the bolt thread; set α3=0.8;

[0078] For the bolt head, the temperature rises due to tool friction and pressure; set α1=0.6;

[0079] The bolt thread, the temperature rises greatly due to the friction with the nut; set α2=0.8;

[0080] Based on the above settings, the warning thresholds H j The calculation formula is as follows:

[0081]

[0082] Further, the evaluation coefficient is constructed, and the evaluation coefficient is used to provide a dynamic adjustment strategy for the thermal expansion coefficient of the bolt, specifically including:

[0083] In the nth data collection, the evaluation coefficient E j,n is defined as follows:

[0084]

[0085] Wherein, E j,n is the evaluation coefficient of the jth part of the bolt in the nth data collection;

[0086] T j,n is the temperature of the jth part of the bolt in the nth data collection; H j is the warning threshold of the jth part of the bolt; T 5,n is the ambient temperature near the bolt in the nth data collection; is the average temperature of the ambient temperature; ΔT max is a predetermined maximum temperature increment, which is a maximum allowed temperature increment set according to the bolt material and the environment;

[0087] |T j,n -H j | is the absolute difference between the current temperature and the warning threshold, indicating the degree of temperature deviation from the warning value;

[0088] is the normalized temperature deviation, taking the warning threshold as the reference, to standardize the temperature deviation degree;

[0089] is the environmental temperature change factor, an exponential decay function is used, when the environmental temperature changes greatly, the influence on the evaluation coefficient is smaller, and the environmental temperature fluctuation will not lead to the distortion of the evaluation result;

[0090] E j,n The value range of is (0, 1), when E j,n closer to 0, the jth part is closer to the warning threshold;

[0091] When E j,n closer to 1, the jth part is farther away from the warning threshold;

[0092] In order to avoid the influence of special values such as 0 on the accuracy of the results, the following requirements are ensured:

[0093] By setting α j and ΔT max , H j ≠ 0 is obtained;

[0094] Since the fluctuation of the environmental temperature is not 0, it is obtained that

[0095] The temperature deviation is limited to be not 0, and it is obtained that

[0096] The interval of the evaluation coefficient E j,n is divided into three continuous intervals, which are the first interval (0, 0.35], the second interval (0.35, 0.64], and the third interval (0.64, 1)

[0097] When the bolt is pre-tightened by the fixed-axis force construction device, the temperature of each part of the bolt will change, and then the thermal expansion coefficient will change. Through the following dynamic adjustment formula, in the nth data collection, the thermal expansion coefficient Rx n obtained in advance can be dynamically adjusted, and the accuracy of the thermal expansion coefficient is improved;

[0098] When the evaluation coefficient E j,n is in the first interval (0, 0.35]:

[0099] and T j,n >H j , it means that the temperature of the bolt part exceeds the warning threshold, the evaluation coefficient takes a lower value, the bolt state fluctuates, and the thermal expansion coefficient Rx n adjustment ratio is between 0% and 1.75%, and the dynamic adjustment formula is as follows:

[0100]

[0101] and Tj,n <H j When T

[0102]

[0103] wherein, Rx′ n is the thermal expansion coefficient after dynamic adjustment, which represents the thermal expansion coefficient of the current bolt in the n th data collection.

[0104] When the evaluation coefficient E j,n In the second interval (0.35, 0.64]:

[0105] and T j,n >H j , indicating that the temperature of the bolt part exceeds the warning threshold, the evaluation coefficient takes a medium value, the bolt state fluctuates, and the thermal expansion coefficient Rx n The adjustment ratio is 3.5% to 6.4%, and the dynamic adjustment formula is as follows:

[0106]

[0107] and T j,n <H j , indicating that the temperature of the bolt part is lower than the warning threshold, and the thermal expansion coefficient needs to be moderately reduced, and the dynamic adjustment formula is as follows:

[0108]

[0109] When the evaluation coefficient E j,n In the third interval (0.64, 1):

[0110] and T j,n >H j , indicating that the temperature of the bolt part exceeds the warning threshold, the temperature is seriously high, the evaluation coefficient is higher, the bolt state is abnormal, and the adjustment ratio is 16% to 25%, and the dynamic adjustment formula is as follows:

[0111]

[0112] and T j,n <H j , indicating that the temperature of the bolt part is lower than the warning threshold, and the thermal expansion coefficient needs to be reduced, and the dynamic adjustment formula is as follows:

[0113]

[0114] wherein, Rx′ n is the thermal expansion coefficient after dynamic adjustment, which represents the thermal expansion coefficient of the current bolt in the n th data collection.

[0115] Further, the bolt calibration data collected at the nth time is transmitted to the controller for processing to calculate the bolt pretightening force after the current applied torque, and to set the target pretightening force range of the current bolt, which specifically includes:

[0116] The acquisition steps of the bolt calibration data are as follows:

[0117] Initial length measurement: the initial length L0 of the bolt is measured by using the single wave technology of ultrasonic wave;

[0118] Initial propagation time measurement: the propagation time t0 of the ultrasonic wave in the bolt under the stress-free state is measured;

[0119] A known pretightening force F is applied to the bolt known , and the propagation time t known of the ultrasonic wave under this state is measured, so as to calibrate the ultrasonic wave measurement system;

[0120] The length change ΔL of the bolt under the known pretightening force is calculated;

[0121] The calibration speed v calibration of the ultrasonic wave is calculated according to the measured data;

[0122] The initial length L0 of the bolt is calculated according to the initial ultrasonic wave propagation time t0 and the calibration speed v calibration :

[0123] L0=v calibration ·t0

[0124] At the nth data acquisition, the ultrasonic wave propagation time t n is measured during the bolt torque application process;

[0125] The actual length L n of the bolt in the current nth data acquisition is calculated:

[0126] L n =v calibration ·t n

[0127] The length change amount ΔL n is calculated:

[0128] ΔL n =L n -L0

[0129] The bolt pretightening force F n after the current applied torque is calculated according to the elastic modulus E and the cross-sectional area A by using the bolt calibration data and the length change amount ΔL n :

[0130]

[0131] The target pre-tightening force range of the current bolt is set as (F1 n , F2 n ), and F1 n , F2 n are positive numbers, F1 n <F2 n .

[0132] Further, the pre-tightening force fine-tuning index P n is defined, and the calculation formula is as follows:

[0133]

[0134] wherein P n is the pre-tightening force fine-tuning index generated in the nth data collection; m is the total number of the detected parts on the bolt;

[0135] E j,n is the evaluation coefficient of the jth part in the nth data collection; T 5,n is the environmental temperature in the nth data collection; T0 is a reference temperature value for normalizing the influence of temperature change; Rx′ n is the dynamically adjusted thermal expansion coefficient in the nth data collection; E max is the maximum value of the evaluation coefficient;

[0136] k1 is an adjustment factor, which determines the sensitivity of the pre-tightening force fine-tuning index, and in the embodiment, 0.12≤k1≤0.68;

[0137] The value range of P n is set as 0<P n ≤M, and M is the maximum value set according to specific applications; the specific value range of M needs to be determined by an expert group according to the measured values of the actual temperature, the evaluation coefficient and the thermal expansion coefficient;

[0138] The comparison threshold of the pre-tightening force fine-tuning index P n is set as U1, and 0.32≤U1≤0.76, and the initial reference value of U1 is 0.52;

[0139] When the pre-tightening force fine-tuning index P n >U1, the compensation fine-tuning strategy formula is as follows:

[0140] ΔF n =δ1·(P n -U1)·F n

[0141] wherein ΔF nis a first compensation adjustment coefficient, and the value range is 0.1≤δ1≤0.3;

[0142] When P n >U1, it indicates that the current preload is high, and compensation needs to be made by reducing the preload; the compensation amount is proportional to U1-P n .

[0143] When the preload fine-tuning index P n =U1, the compensation fine-tuning strategy formula is:

[0144] ΔF n =δ2·F n

[0145] Wherein, δ2 is a second compensation adjustment coefficient, 0.01≤δ2≤0.07, indicating a small amount of fine-tuning;

[0146] When P n =U1, the preload is in the expected range, and a small amount of compensation adjustment is made;

[0147] When the preload fine-tuning index P n <U1, the compensation fine-tuning strategy formula is:

[0148] ΔF n =δ3·(U1-P n )·F n

[0149] Wherein, δ3 is a third compensation adjustment coefficient, and the value range is 0.2≤δ3≤0.4;

[0150] When P n <U1, it indicates that the current preload is low, and compensation needs to be made by increasing the preload; the compensation amount is proportional to U1-P n .

[0151] Example Two:

[0152] On the basis of Example One, this example aims to verify the effectiveness of the compensation fine-tuning strategy for the bolt preload through the preload fine-tuning index; the test is carried out in a standard laboratory environment, simulating the temperature change, evaluation coefficient and thermal expansion coefficient in the actual bolt tightening process, obtaining relevant data, and generating a preload fine-tuning index to test the adjustment effect of the compensation fine-tuning strategy on the preload;

[0153] Test preparation content:

[0154] 1.1) Test object: six different types of bolts are selected, marked as bolt A, bolt B, bolt C, bolt D, bolt E and bolt F;

[0155] 1.2) Ambient temperature measurement: Measure ambient temperature using high-precision temperature sensor, record ambient temperature T

[0156] 1.3) Assigned evaluation coefficient: Calculate assigned evaluation coefficient E according to laboratory conditions and bolt material characteristics j,n ;

[0157] 1.4) Thermal expansion coefficient: Measure and dynamically adjust thermal expansion coefficient Rx′ through material thermal expansion experiment n ;

[0158] 1.5) Pre-tightening force measurement equipment: Measure current bolt pre-tightening force F using high-precision torque wrench and pre-tightening force sensor n ;

[0159] Implementation detailed process:

[0160] 2) Data collection:

[0161] Install temperature sensors at different positions of each bolt, record ambient temperature T in real time 5,n ;

[0162] Collect assigned evaluation coefficient E j,n , and record dynamically adjusted thermal expansion coefficient Rx′ n ;

[0163] 3) Generate pre-tightening force fine-tuning index:

[0164] Generate pre-tightening force fine-tuning index P n by the following formula:

[0165]

[0166] Set M = 1.0, T0 = 25℃, δ2 = 0.05, δ3 = 0.3, and calculate the current n-th collection P n ;

[0167] 4) Compensation fine-tuning strategy application:

[0168] Set the comparison threshold U1 = 0.52 for pre-tightening force fine-tuning index P n ;

[0169] According to the comparison result of P n and U1, different compensation fine-tuning strategies are applied:

[0170] 5) Adjust pre-tightening force:

[0171] According to the compensation fine-tuning strategy, adjust the hydraulic pump output so that the actual pre-tightening force reaches the compensated pre-tightening force, and keep it in the target pre-tightening force range (F1 n , F2 n) in the inner, (F1 n , F2 n ) determined by the expert group through experimental data, not described;

[0172] 6) Monitoring and recording:

[0173] Using sensors to monitor the change of pretension in real time, and record the corresponding data before and after adjustment, to ensure that each adjustment meets the expected target;

[0174] Through the above steps, the system can dynamically adjust the pretension of the bolt to ensure it is within the target range, thereby verifying the effectiveness and advantages of the invention;

[0175] The implementation data is as follows:

[0176] Table 1

[0177]

[0178] The table data analysis is as follows:

[0179] 1) Bolt A data analysis:

[0180] Initial pretension F n 500N, ambient temperature 30℃, evaluation coefficient E j,n assigned to 0.3, thermal expansion coefficient Rx' n 1.05, calculated pretension fine adjustment index P n 0.65;

[0181] Pretension fine adjustment index P n = 0.65 > 0.52, according to the compensation strategy formula:

[0182] ΔF n = δ1·(P n -U1)·F n = 0.25·(0.65-0.52)·500 = 16.25N

[0183] The adjusted pretension is F adj = 500-16.25 = 483.75 ≈ 475N, where F adj is the adjusted pretension;

[0184] As can be seen from the data, bolt A actively reduces the pretension in the case of higher ambient temperature and higher evaluation coefficient, avoiding the over-high pretension caused by overheating, and reflecting the pretension adjustment effect of the invention in temperature changes;

[0185] 2) Relationship between parameters and numerical change analysis:

[0186] Ambient temperature T 5,n With pre-tightening fine-tuning index P n :

[0187] Ambient temperature T 5,n The higher, the index part The smaller, resulting in P n Reduction; such as bolt A and bolt C, 30 DEG C and 28 DEG C, respectively, corresponding P n 0.65 and 0.55, respectively;

[0188] Ambient temperature increases by 10%, pre-tightening fine-tuning index P n Reduction of 5%; assignment evaluation coefficient E j,n With pre-tightening fine-tuning index P n :

[0189] Assignment evaluation coefficient E j,n The higher, the pre-tightening fine-tuning index P n The greater; such as bolt B and bolt F, 0.4 and 0.36, respectively, corresponding P n 0.48, indicating that E j,n Has a greater impact on the pre-tightening fine-tuning index;

[0190] Assignment evaluation coefficient increases by 10%, pre-tightening fine-tuning index P n Increase of 20%;

[0191] Thermal expansion coefficient Rx' n With pre-tightening fine-tuning index P n :

[0192] Thermal expansion coefficient Rx' n The higher, the pre-tightening fine-tuning index P n The greater; such as bolt A and bolt E, 1.05 and 1.04, respectively, corresponding P n 0.65 and 0.54, respectively;

[0193] Thermal expansion coefficient increases by 1%, pre-tightening fine-tuning index P n Increase of 1%;

[0194] Through the data and formula analysis, the following several beneficial effects of the present application can be obtained:

[0195] Real-time adjustment of pre-tightening force: by calculating the pre-tightening fine-tuning index P n , and according to the comparison of P n With threshold U1, the pre-tightening force is adjusted in real time to prevent the pre-tightening force from being too high or too low;

[0196] Such as bolt A, in a high temperature environment, by reducing the pre-tightening force to keep the pre-tightening force within a proper range, the problem of over-tightening caused by thermal expansion is avoided;

[0197] The bolt B increases the pre-tightening force at a lower temperature and a high evaluation coefficient, and ensures the fastening effect;

[0198] Multi-parameter comprehensive regulation: the pre-tightening force fine adjustment index is accurately calculated by comprehensively considering the environmental temperature, the evaluation coefficient and the thermal expansion coefficient, and a more comprehensive pre-tightening force regulation scheme is provided;

[0199] The pre-tightening force fine adjustment index of the bolt D is relatively stable at a moderate environmental temperature and evaluation coefficient, indicating that the system can effectively regulate various working conditions;

[0200] Improve the fastening precision: through the compensation fine adjustment strategy, the system can effectively adjust the pre-tightening force, so that it is maintained in the target range, and the fastening precision and reliability are improved;

[0201] After the pre-tightening force fine adjustment of the bolt F, the actual pre-tightening force is accurately adjusted to 527N, close to the target value, indicating that the system has high precision adjustment performance in actual application.

[0202] The above formulas are dimensionless values, and the formulas are obtained by software simulation of a large amount of data to obtain a formula of the most recent real situation, and the preset parameters in the formula are set by a person skilled in the art according to the actual situation.

[0203] The above embodiments can be realized wholly or partially by software, hardware, firmware or any combination thereof. When realized by software, the above embodiments can be realized in the form of a computer program product wholly or partially. Those skilled in the art can realize that the units and algorithm steps of the examples described in connection 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.

[0204] 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 to achieve the purpose of the embodiment according to actual needs.

[0205] The above is merely 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. A fixed-axis force construction device for real-time detection of bolt preload, the device comprising a preload detection and control system utilizing ultrasonic technology, characterized in that, Specifically, it includes: Calibration module: used to calibrate the number of acquisitions in real-time ultrasonic detection, forming a set {1,2,…,i,…,n}, where i represents the index of the i-th data acquisition, n represents the index of the current n-th data acquisition, and i∈{1,2,…,n}; Temperature data acquisition module: In the i-th data acquisition, it acquires the thermal expansion coefficient of the bolt, and obtains the temperature of the bolt head, the temperature of the bolt thread, the temperature of the nut, the temperature of the bolt tail, and the ambient temperature near the bolt, forming the i-th temperature detection dataset, and uploads the dataset to the database to record the historical temperature change data of each part of the bolt. Calibration data acquisition module: used to collect the corresponding bolt calibration data in the i-th data acquisition, and upload the i-th bolt calibration data to the database to form a historical calibration data change set of the bolt; Warning threshold setting module: used to transmit the collected historical temperature change data to the controller for processing, to calculate the average temperature of each part of the bolt under the current ambient temperature, and to set the warning threshold of each part of the bolt based on these average temperatures; Adjustment module: Used to compare and analyze the temperature data of various parts of the bolt obtained from the current nth data acquisition with the corresponding warning threshold, and construct an evaluation coefficient. The evaluation coefficient is used to provide a dynamic adjustment strategy for the measured thermal expansion coefficient of the bolt. Preload calculation module: used to transmit the bolt calibration data collected for the nth time to the controller for processing, in order to calculate the bolt preload after the current applied torque, and set the target preload range for the current bolt; Index generation module: used to obtain the ambient temperature of the current nth acquisition, the assigned evaluation coefficient and the dynamically adjusted coefficient of thermal expansion, and to analyze and process them to generate the preload fine-tuning index. The preload fine-tuning index is used to provide a compensation fine-tuning strategy for the bolt preload after the current applied torque. Post-processing module: After the bolt preload is adjusted through the compensation fine-tuning strategy, the hydraulic pump output in the fixed-axis force construction device is controlled to make the actual preload reach the compensated preload. In the subsequent tightening process, the adjusted preload is kept within the set target preload range until the tightening is completed.

2. The axial force construction device for real-time detection of bolt preload according to claim 1, characterized in that: In the i-th data acquisition, the coefficient of thermal expansion, bolt head temperature, bolt thread temperature, nut temperature, bolt tail temperature, and ambient temperature near the bolt are respectively labeled as Rxi, T1,i, T2,i, T3,i, T4,i, and T5,i. The bolt calibration data includes the elastic modulus E, the initial bolt length L0, the calibration speed vcalibration, and the actual bolt length Li in the i-th data acquisition. Calculate the average temperature of each part of the bolt under the current ambient temperature, and set warning thresholds for each part of the bolt based on these average temperatures. Specifically, this includes: set up Let j represent the average temperature at different locations on the bolt, where j∈{1,2,3,4}. The calculation formula is as follows: Where i represents the i-th data collection, and n represents the current n-th data collection; set up The average temperature under the current ambient temperature is calculated using the following formula: Where T5,i represents the ambient temperature of the i-th data collection; Based on the calculated average temperature of each part, a warning threshold is set. The formula for setting the warning threshold is as follows: Among them, Hj is the warning threshold of the j-th part of the bolt, and ΔTj is a temperature increment set according to the safety standard of the j-th part of the bolt; The calculation formula for setting ΔTj is as follows: Among them, ΔTj is the temperature increment of the j-th part of the bolt; αj is the temperature change coefficient representing the j-th part of the bolt, and its value range is 0 < αj ≤ 1; ΔTmax is the predetermined maximum temperature increment. The calculation formula for further determining the warning threshold Hj of each part of the bolt is as follows:

3. The axial force construction device for real-time detection of bolt preload according to claim 2, characterized in that: Construct an assignment evaluation coefficient, which is used to provide a dynamic adjustment strategy for the thermal expansion coefficient of the bolt, specifically including: In the n-th data acquisition, the defined assignment evaluation coefficient is Ej,n, and the calculation formula is as follows: Among them, Ej,n is the assignment evaluation coefficient of the j-th part of the bolt in the n-th data acquisition; Tj,n is the temperature of the j-th part of the bolt in the nth data acquisition; Hj is the warning threshold of the j-th part of the bolt; T5,n is the ambient temperature near the bolt in the nth data acquisition. It is the average temperature of the ambient temperature; ΔTmax is the predetermined maximum temperature increment; The value range of Ej,n is (0, 1). When Ej,n is closer to 0, it means that the j-th part is closer to the warning threshold; When Ej,n is closer to 1, it means that the j-th part is farther from the warning threshold; Divide the interval of the assignment evaluation coefficient Ej,n into three consecutive intervals, namely the first interval (0, 0.35], the second interval (0.35, 0.64], and the third interval (0.64, 1) When the assignment evaluation coefficient Ej,n is in the first interval (0, 0.35]: And when Tj,n > Hj, it means that the temperature of this bolt part exceeds the warning threshold, the assignment evaluation coefficient takes a lower value, the bolt state fluctuates, and the adjustment ratio of the thermal expansion coefficient Rx'n is between 0% and 1.75%. The dynamic adjustment formula is as follows: And when Tj,n < Hj, it means that the temperature of this bolt part is lower than the warning threshold, and the dynamic adjustment formula is as follows: When the assignment evaluation coefficient Ej,n is in the second interval (0.35, 0.64]: And when Tj,n > Hj, it means that the temperature of this bolt part exceeds the warning threshold, the assignment evaluation coefficient takes a medium value, the bolt state fluctuates, and the adjustment ratio of the thermal expansion coefficient Rx'n is between 3.5% and 6.4%. The dynamic adjustment formula is as follows: And when Tj,n < Hj, it means that the temperature of this bolt part is lower than the warning threshold, and it is necessary to moderately reduce the thermal expansion coefficient. The dynamic adjustment formula is as follows: When the assignment evaluation coefficient Ej,n is in the third interval (0.64, 1): And when Tj,n > Hj, it means that the temperature of this bolt part exceeds the warning threshold, the temperature is seriously too high, the assignment evaluation coefficient is higher, the bolt state is abnormal, and the adjustment ratio is between 16% and 25%. The dynamic adjustment formula is as follows: And when Tj,n < Hj, it means that the temperature of this bolt part is lower than the warning threshold, and it is necessary to reduce the thermal expansion coefficient. The dynamic adjustment formula is as follows: Among them, Rx′n is the thermal expansion coefficient after dynamic adjustment, which represents the thermal expansion coefficient of the current bolt in the n-th data acquisition.

4. A fixed-axis force construction device for real-time detection of bolt preload according to claim 3, characterized in that: Transmit the calibrated data of the bolt collected in the n-th time to the controller for processing to calculate the pre-tightening force of the bolt after the current applied torque, and set the target pre-tightening force range of the current bolt, specifically including: Use the ultrasonic single-wave technology to measure the initial length L0 of the bolt; Measure the propagation time t0 of ultrasonic waves in the bolt under the unloaded state and calibrate the speed vcalibration; Calculate the initial length L0 of the bolt based on the initial ultrasonic propagation time t0 and the calibrated speed vcalibration: L0 = vcalibration·t0 During the nth data acquisition, when torque is applied to the bolt, measure the ultrasonic propagation time tn; Calculate the actual length Ln of the bolt in the current nth data acquisition: Ln = vcalibration·tn Calculate the length change ΔLn: ΔLn = Ln - L0 Using the bolt calibration data and the length change ΔLn, calculate the bolt pre-tightening force Fn after the current applied torque according to the elastic modulus E and the cross-sectional area A: Set the target pre-tightening force range of the current bolt as (F1n, F2n), and both F1n and F2n are positive numbers, and F1n < F2n.

5. A fixed-axis force construction device for real-time detection of bolt preload according to claim 4, characterized in that: Define the pre-tightening force fine-tuning index as Pn, and the calculation formula is as follows: Where, Pn is the pre-tightening force fine-tuning index generated in the nth data acquisition; m is the total number of detected parts on the bolt; Ej,n is the assignment evaluation coefficient of the jth part in the nth data acquisition; T5,n is the ambient temperature in the nth data acquisition; T0 is the reference temperature value used to normalize the influence of temperature change; Rx′n is the dynamically adjusted coefficient of thermal expansion; Emax is the maximum value of the assignment evaluation coefficient; k1 is an adjustment factor that determines the sensitivity of the pre-tightening force fine-tuning index, 0.12 ≤ k1 ≤ 0.68; set the value range of Pn as 0 < Pn ≤ M, and M is the maximum value set according to specific applications; Set the comparison threshold of the pre-tightening force fine-tuning index Pn as U1, and 0.32 ≤ U1 ≤ 0.76, and set the initial reference value of U1 as 0.52; When the pre-tightening force fine-tuning index Pn > U1, the compensation fine-tuning strategy formula is: ΔFn = δ1·(Pn - U1)·Fn Where, ΔFn is the pre-tightening force that needs to be compensated; δ1 is the first compensation adjustment coefficient, and the value range of δ1 is 0.1 ≤ δ1 ≤ 0.3; And it is stated that the current pre-tightening force is relatively high and needs to be compensated by reducing the pre-tightening force, and the compensation amount is proportional to Pn - U1; When the pre-tightening force fine-tuning index Pn = U1, the compensation fine-tuning strategy formula is: ΔFn = δ2·Fn Where, δ2 is the second compensation adjustment coefficient, 0.01 ≤ δ2 ≤ 0.07, indicating a small amount of fine-tuning. When the pre-tightening force is within the expected range, a small amount of compensation adjustment is made; When the pre-tightening force fine-tuning index Pn < U1, the compensation fine-tuning strategy formula is: ΔFn = δ3·(U1 - Pn)·Fn Where, δ3 is the third compensation adjustment coefficient, and the value range of δ3 is 0.2 ≤ δ3 ≤ 0.4, and it is stated that the current pre-tightening force is relatively low and needs to be compensated by increasing the pre-tightening force; the compensation amount is proportional to U1 - Pn.

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