Fixed axial force construction device for detecting bolt pre-tightening force in real time

Abstract

The invention provides a fixed axial force construction device for detecting bolt pre-tightening force in real time, and relates to the technical field of bolt detection and control. Temperature changes of all parts of a bolt can be monitored in real time through a temperature data acquisition module, and a historical temperature change data set is formed; secondly, a warning threshold value is set through a warning threshold value setting module according to the average temperature and historical data of all parts of the bolt, and the stability and reliability of the pretightening force of the bolt at different environment temperatures are ensured; and furthermore, through an index generation module, the environment temperature, the assignment evaluation coefficient and the thermal expansion coefficient are comprehensively considered, a pre-tightening force fine adjustment index is generated, compensation fine adjustment is performed on the bolt pre-tightening force after the torque is applied currently, and dynamic adjustment and accurate control of the pre-tightening force are realized.

Description

Technical Field

[0001] The invention relates to the technical field of bolt detection and control, and in particular to a fixed-axis force construction device for real-time detection of bolt pre-tightening force. Background Art

[0002] The torque output by the torque wrench acts on the effective preload force of the bolt axial direction through the nut, gasket, connected parts and threaded pair. The effective preload force often does not reach the design value due to the difference in intermediate transmission. It is difficult to ensure the consistency of the axial preload force when the same torque coefficient is used for tightening. This is the key factor for "not tightening" or "over tightening". The axial tensile strength of the "untightened" bolt cannot function normally. The shear strength of the high-strength bolt itself is relatively weak, which can easily cause the connected parts to slip and the bolt to be sheared during use; the "over-tightened" bolt has insufficient residual tensile strength and insufficient design margin to resist instantaneous high loads; and according to the following link content, it is established that the bolt calibration data is to establish the relationship between the bolt and the ultrasonic sound time difference (elongation, axial force), obtain the calibration test data, and establish a compilation file to provide data support for the subsequent axial force test;

[0003] The UHW is an industrial-grade high-precision bolt tightening tool. It is a typical electro-hydraulic servo integrated control system. The UHW is mainly composed 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 tablet computer (PAD) and a software system. The ultrasonic sensor is introduced to measure the axial preload of the bolt in real time during the tightening process, and the feedback is fed back to the electro-hydraulic servo system to control the wrench to tighten. Since the direct axial force is measured, the error influencing factors such as the friction of the thread pair and the connection end face are avoided, and high-precision preload control is achieved.

[0004] The working principle of the whole system is as follows: the user places the wrench on the nut, places the ultrasonic sensor on one end face of the bolt, inputs the bolt parameters and target preload on the human-machine interactive terminal PAD, starts tightening, and the system controller sends a work instruction to the hydraulic pump and the 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. The controller precisely controls the pressure output of the hydraulic pump after feedback calculation. When the error between the measured bolt preload and the set value is within the allowable accuracy range, the controller sends a stop tightening instruction, and the bolt tightening ends. The whole tightening process automatically tightens to the set preload without human intervention.

[0005] In the prior art, the publication number is CN117824902A, and the name is a bolt preload monitoring and control method based on ultrasonic single wave technology, which obtains the calibrated speed of the bolt, uses the ultrasonic single wave to detect the initial ultrasonic propagation time of the bolt, and calculates the initial length of the bolt; starts the construction tool to apply torque to the bolt, uses the ultrasonic single wave to detect the ultrasonic propagation time in real time, calculates the actual length of the bolt after the i-th detection, and calculates the length change of the bolt before and after the force is applied; calculates the absolute value of the bolt preload after the current torque is applied to the bolt according to the bolt calibration data; determines whether the absolute value of the current bolt preload has reached the target preload range, and if not, continues to apply torque and calculates the absolute value of the bolt preload until the target preload range is reached;

[0006] At present, most detection methods have poor adaptability to changes in ambient temperature and cannot monitor and adjust the temperature changes of various parts of the bolt in real time; temperature changes will directly affect the thermal expansion coefficient of the bolt, thereby causing deviations in the preload force; secondly, the existing technology has lags in data collection and analysis and processing, and cannot achieve real-time monitoring and dynamic adjustment of the bolt preload force, resulting in reduced accuracy and reliability of preload force control; in addition, the existing technology lacks systematicity and intelligence in setting warning thresholds and fine-tuning preload force, and cannot accurately compensate and adjust preload force based on the historical data and current working conditions of the bolt;

[0007] The above information disclosed in the above 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 one of ordinary skill in the art. Summary of the invention

[0008] The purpose of the present invention is to provide a fixed-axis force construction device for real-time detection of bolt preload, so as to solve the problems raised in the above-mentioned background technology.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A fixed-axis force construction device for real-time detection of bolt preload, the device includes a preload detection control system using ultrasonic technology, specifically including:

[0011] Calibration module: used to calibrate the number of acquisitions of ultrasonic real-time detection to form 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};

[0012] Temperature data acquisition module: used to collect the thermal expansion coefficient of the bolt in the i-th data acquisition, and obtain the bolt head temperature, bolt thread temperature, nut temperature, bolt tail temperature and ambient temperature near the bolt to form the i-th temperature detection data set, and upload the data set to the database to record the historical temperature change data of each part of the bolt;

[0013] Calibration data collection module: used to collect the corresponding bolt calibration data in the i-th data collection, 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, so as to calculate the average temperature of each part of the bolt under the current ambient temperature, and set the warning threshold of each part of the bolt according to these average temperatures;

[0015] Adjustment module: used to compare and analyze the temperature data of each part of the bolt obtained by the current nth data collection with the corresponding warning threshold, and construct an assigned evaluation coefficient. The assigned 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, so as to calculate the bolt preload after the current torque is applied, and set the target preload range of the current bolt;

[0017] Index generation module: used to obtain the ambient temperature collected for the nth time, the assigned evaluation coefficient and the thermal expansion coefficient after dynamic adjustment, and perform analysis and processing to generate a 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 torque is applied;

[0018] Post-processing module: After the bolt preload is adjusted through the compensation fine-tuning strategy, the output of the hydraulic pump in the fixed-axis force construction device is controlled to make the actual preload reach the compensated preload, and keep it 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 collection; m is the total number of locations tested on the bolt;

[0022] E j,n is the evaluation coefficient assigned to the jth part in the nth data collection; T5,n is the ambient temperature in the nth data collection; T0 is the reference temperature value, which is used to normalize the influence of temperature change; Rx′ n is the dynamically adjusted thermal expansion coefficient; E max is the maximum value of the assigned evaluation coefficient;

[0023] k1 is the adjustment factor, which determines the sensitivity of the preload fine-tuning index, 0.12≤k1≤0.68; set P n The value range is 0 <P n ≤M, 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, and the initial reference value of U1 is set to 0.52;

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

[0026] ΔF n =δ1·(P n -U1)·F n

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

[0028] It also indicates that the current preload is high and needs to be compensated by reducing the preload, and the compensation amount is related to P n - Proportional to U1;

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

[0030] ΔF n =δ2·F n

[0031] Among them, δ2 is the second compensation adjustment coefficient, 0.01≤δ2≤0.07, which means that a small amount of fine-tuning is performed, and a small amount of compensation adjustment is performed when the preload force is within the expected range;

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

[0033] ΔF n =δ3·(U1-P n )·F n

[0034] Among them, δ3 is the third compensation adjustment coefficient, and the value range of δ3 is 0.2≤δ3≤0.4, which indicates that the current preload is low and needs to be compensated by increasing the preload. The compensation amount is related to U1-P n Directly proportional.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: through the temperature data acquisition module, the temperature changes of various parts of the bolt can be monitored in real time, and a historical temperature change data set can be formed; secondly, through the warning threshold setting module, the warning threshold is set according to the average temperature and historical data of various parts of the bolt, so as to ensure the stability and reliability of the bolt preload under different ambient temperatures; furthermore, through the index generation module, the ambient temperature, the assigned evaluation coefficient and the thermal expansion coefficient are comprehensively considered to generate a preload fine-tuning index, and the preload of the bolt after the current torque is applied is compensated and fine-tuned, thereby realizing dynamic adjustment and precise control of the preload. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0037] 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 in conjunction with specific embodiments.

[0038] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "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 positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0039] Embodiment 1:

[0040] See also Figure 1 , the present invention provides a technical solution:

[0041] A fixed-axis force construction device for real-time detection of bolt preload, the device includes a preload detection control system using ultrasonic technology, specifically including:

[0042] Calibration module: used to calibrate the number of acquisitions of ultrasonic real-time detection to form 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};

[0043] Temperature data acquisition module: used to collect the thermal expansion coefficient of the bolt in the i-th data acquisition, and obtain the bolt head temperature, bolt thread temperature, nut temperature, bolt tail temperature and ambient temperature near the bolt to form the i-th temperature detection data set, and upload 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 to collect the corresponding bolt calibration data in the i-th data collection, and upload the i-th bolt calibration data to the database to form a historical calibration data change set of the bolt;

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

[0046] Adjustment module: used to compare and analyze the temperature data of each part of the bolt obtained from the current nth data collection with the corresponding warning threshold, obtain the assignment results of each part of the bolt, analyze and process the assignment results of each part of the bolt, and construct the assignment evaluation coefficient. The assignment evaluation coefficient is used to provide a dynamic adjustment strategy for the measured thermal expansion coefficient of the bolt;

[0047] Preload calculation module: used to transmit the bolt calibration data collected for the nth time to the controller for processing, so as to calculate the bolt preload after the current torque is applied, and set the target preload range of the current bolt;

[0048] Index generation module: used to obtain the ambient temperature collected for the nth time, the assigned evaluation coefficient and the thermal expansion coefficient after dynamic adjustment, and perform analysis and processing to generate a 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 torque is applied;

[0049] Post-processing module: After the bolt preload is adjusted through the compensation fine-tuning strategy, the output of the hydraulic pump in the fixed-axis force construction device is controlled to make the actual preload reach the compensated preload, and in the subsequent tightening process, the adjusted preload is maintained within the set target preload range until the tightening is completed.

[0050] Further explanation: In the i-th data collection, the thermal expansion coefficient, 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 are marked as Rx i , T 1,i , T 2,i , T 3,i , T 4,i , T 5,i ;

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

[0052] Elastic modulus E: represents the stiffness of the material, that is, the degree to which the material deforms under stress;

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

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

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

[0056] 4) Calibration data:

[0057] Data obtained through laboratory or field testing to calibrate the ultrasonic measurement system; this data includes the ultrasonic propagation time and the change in bolt length measured at a known preload;

[0058] Calculate the average temperature of each part of the bolt under the current ambient temperature, and set the warning threshold of each part of the bolt according to these average temperatures, including:

[0059] The tail of the bolt is the end of the bolt rod, away from the nut. This part is subjected to force but has less friction and relatively small temperature changes.

[0060] The nut is an accessory installed on the bolt thread. The friction between the nut and the bolt thread generates heat, and the temperature rises greatly;

[0061] The bolt head is the top of the bolt, which is in direct contact with the fixed-axis force construction device. This part is mainly affected by the friction and pressure of the wrench or the fixed-axis force construction device, and the temperature rises greatly;

[0062] The bolt thread is the threaded area on the bolt shank, where the nut directly fits in. Due to the friction between the bolt and the nut, the threaded part generates heat and the temperature rises significantly;

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

[0064]

[0065] Among them, i represents the i-th data collection, and n represents the current n-th data collection;

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

[0067]

[0068] Among them, T 5,i represents the ambient temperature collected for the i-th time;

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

[0070]

[0071] Among them, H j is the warning threshold of the jth bolt position, ΔT j It is a temperature increment set according to the safety standard of the jth part of the bolt to ensure that the temperature of the jth part of the bolt will not exceed the safety range when the external environment changes;

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

[0073]

[0074] Where, ΔT j is the temperature increment of the jth part of the bolt, ensuring that the temperature of this part does not exceed the safe range; α j is the temperature variation coefficient of the jth part of the bolt, and its value range is 0<α j ≤1, reflects the degree of temperature change in different parts; ΔT max It is the predetermined maximum temperature increment, a maximum allowable temperature increment set according to the bolt material and environment, ΔT max With α j The specific determination method is obtained by the expert group through experimental data analysis and will not be elaborated here;

[0075] According to the causes and extent of temperature changes in different parts, set the temperature change coefficient α of each part of the bolt j as follows:

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

[0077] For nuts, friction with bolt threads generates heat, causing a large temperature rise; α3 = 0.8;

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

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

[0080] Based on the above settings, the warning threshold H of each part of the bolt j The calculation formula is as follows:

[0081]

[0082] Further explanation: constructing an assigned evaluation coefficient, which is used to provide a dynamic adjustment strategy for the thermal expansion coefficient of the bolt, specifically includes:

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

[0084]

[0085] Among them, E j,n is the assigned 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 during the nth data collection; is the average temperature of the ambient temperature; ΔT max It is the predetermined maximum temperature increment, a maximum allowable temperature increment set according to the bolt material and environment;

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

[0088] It is to normalize the temperature deviation value, and standardize the degree of temperature deviation based on the warning threshold;

[0089] It is the factor of ambient temperature change. Using exponential decay function, when the ambient temperature changes greatly, the impact on the assigned evaluation coefficient is small, ensuring that the ambient temperature fluctuation will not cause distortion of the evaluation result;

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

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

[0092] To avoid special values ​​such as 0 that affect the accuracy of the results, ensure that the following requirements are met:

[0093] By setting α j and ΔT max value, get H j ≠0;

[0094] Since the ambient temperature fluctuation will not be 0, we get

[0095] The temperature deviation is limited to not be 0, and we get

[0096] Assign the evaluation coefficient E j,n The interval is divided 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)

[0097] When the bolt is pre-tightened by the fixed-axis force construction device, the temperature of each part of the bolt will change, which will cause the thermal expansion coefficient to change. By setting the following dynamic adjustment formula, the thermal expansion coefficient Rx obtained in advance can be adjusted in the nth data collection. n Perform dynamic adjustments to improve the accuracy of obtaining the thermal expansion coefficient;

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

[0099] And T j,n >H j When the temperature of the bolt exceeds the warning threshold, the assigned evaluation coefficient is low, the bolt state fluctuates, and the thermal expansion coefficient Rx n The adjustment ratio is between 0% and 1.75%, and the dynamic adjustment formula is as follows:

[0100]

[0101] And Tj,n <H j When , it means that the temperature of the bolt part is lower than the warning threshold. The dynamic adjustment formula is as follows:

[0102]

[0103] Among them, Rx′ n is the thermal expansion coefficient after dynamic adjustment, which represents the thermal expansion coefficient of the current bolt in the nth data collection;

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

[0105] And T j,n >H j When the temperature of the bolt exceeds the warning threshold, the evaluation coefficient is medium, the bolt state fluctuates, and the thermal expansion coefficient Rx n The adjustment ratio is between 3.5% and 6.4%, and the dynamic adjustment formula is as follows:

[0106]

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

[0108]

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

[0110] And T j,n >H j When , it means that the temperature of the bolt part exceeds the warning threshold, the temperature is seriously high, the assigned evaluation coefficient is high, the bolt state is abnormal, and the adjustment ratio is between 16% and 25%. The dynamic adjustment formula is as follows:

[0111]

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

[0113]

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

[0115] Further explanation: The bolt calibration data collected for the nth time is transmitted to the controller for processing to calculate the bolt preload after the current torque is applied and set the target preload range of the current bolt, specifically including:

[0116] The steps to obtain bolt calibration data are as follows:

[0117] Initial length measurement: Use ultrasonic single wave technology to measure the initial length L0 of the bolt;

[0118] Initial propagation time measurement: measure the propagation time t0 of the ultrasonic wave in the bolt under no stress;

[0119] Apply a known preload F to the bolt. known , and measure the propagation time t of the ultrasonic wave in this state known , used to calibrate the ultrasonic measurement system;

[0120] Calculate the length change ΔL of the bolt under a known preload;

[0121] Calculate the ultrasonic calibration velocity v based on the measured data calibration ;

[0122] According to the initial ultrasonic propagation time t0 and the calibration speed v calibration Calculate the initial length L0 of the bolt:

[0123] L0=v calibration t0

[0124] During the nth data acquisition, the ultrasonic propagation time t is measured during the process of applying torque to the bolt. n ;

[0125] Calculate the actual length L of the bolt in the current nth data collection n :

[0126] L n =v calibration ·t n

[0127] Calculate the length change ΔL n :

[0128] ΔL n =L n -L0

[0129] Using bolt calibration data and length change ΔL n , calculate the bolt preload F after the current applied torque based on the elastic modulus E and cross-sectional area A n :

[0130]

[0131] Set the target preload range of the current bolt to (F1 n , F2 n ), and F1 n 、F2 n Both are positive numbers, F1 n <F2 n .

[0132] Further explanation: the preload fine-tuning index is defined as P n , the calculation formula is as follows:

[0133]

[0134] Among them, P n is the preload fine-tuning index generated in the nth data collection; m is the total number of parts detected on the bolt;

[0135] E j,n is the evaluation coefficient assigned to the jth part in the nth data collection; T 5,n is the ambient temperature in the nth data collection; T0 is the reference temperature value, which is used to normalize the influence of temperature change; Rx′ n is the thermal expansion coefficient after dynamic adjustment in the nth data acquisition; E max is the maximum value of the assigned evaluation coefficient;

[0136] k1 is an adjustment factor, which determines the sensitivity of the preload fine-tuning index. In this embodiment, 0.12≤k1≤0.68;

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

[0138] Set the preload fine-tuning index P n The comparison threshold is U1, and 0.32≤U1≤0.76, and the initial reference value of U1 is 0.52;

[0139] When the preload fine-tuning index P n When >U1, the compensation fine-tuning strategy formula is:

[0140] ΔF n =δ1·(P n -U1)·F n

[0141] Where, ΔF nis the preload force to be compensated; δ1 is the first compensation adjustment coefficient, and its value range is 0.1≤δ1≤0.3;

[0142] When P n >U1, indicating that the current preload is high and needs to be compensated by reducing the preload. The compensation amount is related to P n - Proportional to U1;

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

[0144] ΔF n =δ2·F n

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

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

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

[0148] ΔF n =δ3·(U1-P n )·F n

[0149] Among them, δ3 is the third compensation adjustment coefficient, and its value range is 0.2≤δ3≤0.4;

[0150] When P n When <U1, it means that the current preload is low and needs to be compensated by increasing the preload. The compensation amount is related to U1-P n Directly proportional.

[0151] Embodiment 2:

[0152] Further explanation based on the first embodiment, this embodiment 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, assignment evaluation coefficient and thermal expansion coefficient in the actual bolt tightening process, obtaining relevant data, and generating the 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 bolts of different types are selected and marked as bolt A, bolt B, bolt C, bolt D, bolt E, and bolt F;

[0155] 1.2) Ambient temperature measurement: Use a high-precision temperature sensor to measure the ambient temperature and record the ambient temperature;

[0156] 1.3) Assignment evaluation coefficient: Calculate the assignment evaluation coefficient E according to laboratory conditions and bolt material properties. j,n ;

[0157] 1.4) Thermal expansion coefficient: Through material thermal expansion experiments, measure and dynamically adjust the thermal expansion coefficient Rx′ n ;

[0158] 1.5) Preload force measurement equipment: Use a high-precision torque wrench and preload force sensor to measure the current bolt preload force F n ;

[0159] Detailed implementation process:

[0160] 2) Data collection:

[0161] Temperature sensors are installed at different locations on each bolt to record the ambient temperature T in real time. 5,n ;

[0162] Collection assignment evaluation coefficient E j,n , and record the thermal expansion coefficient Rx′ after dynamic adjustment n ;

[0163] 3) Generate preload fine-tuning index:

[0164] The preload fine-tuning index P is generated by the following formula n :

[0165]

[0166] Set M = 1.0, T0 = 25 °C, δ2 = 0.05, δ3 = 0.3, and calculate the P of the current nth acquisition n ;

[0167] 4) Application of compensation fine-tuning strategy:

[0168] Set the preload fine-tuning index P n The comparison threshold U1 = 0.52;

[0169] According to P n Comparison results with U1, applying different compensation fine-tuning strategies:

[0170] 5) Adjust the preload:

[0171] According to the compensation fine-tuning strategy, adjust the hydraulic pump output so that the actual preload force reaches the preload force after compensation and remains within the target preload force range (F1 n , F2 n), (F1 n , F2 n ) is determined by the expert group through experimental data and will not be elaborated on;

[0172] 6) Monitoring and recording:

[0173] Use sensors to monitor preload changes in real time and record corresponding data before and after adjustment to ensure that each adjustment meets the expected goals;

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

[0175] The implementation data is recorded as follows:

[0176] Table 1

[0177]

[0178] The table data analysis is as follows:

[0179] 1) Bolt A data analysis:

[0180] Initial preload F n 500N, ambient temperature The temperature is 30℃, and the evaluation coefficient E is assigned j,n The thermal expansion coefficient is 0.3, Rx′ n is 1.05, the calculated preload fine-tuning index P n is 0.65;

[0181] Preload fine-tuning 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 preload force is F adj =500-16.25=483.75≈475N, where F adj is the preload force after adjustment;

[0184] From the data, it can be seen that when the ambient temperature of bolt A is high and the evaluation coefficient is high, the system actively reduces the preload force, avoiding excessive preload force due to overheating, which reflects the preload force adjustment effect of the present invention in temperature changes;

[0185] 2) Analysis of the relationship between various parameters and their value changes:

[0186] Ambient temperature T 5,n Preload fine-tuning index P n :

[0187] Ambient temperature T 5,n The higher the index part The smaller the P n Reduce; for example, bolt A and bolt C are 30℃ and 28℃ respectively, and the corresponding P n They are 0.65 and 0.55 respectively;

[0188] When the ambient temperature increases by 10%, the preload force fine-tuning index P n Reduce by 5%; assign evaluation coefficient E j,n Preload fine-tuning index P n :

[0189] Assignment evaluation coefficient E j,n The higher the preload fine-tuning index P n The larger the bolt is, the larger the P is. For example, bolt B and bolt F are 0.4 and 0.36 respectively. n Both are 0.48, indicating that E j,n It has a great influence on the preload fine-tuning index;

[0190] The assigned evaluation coefficient increases by 10%, and the preload fine-tuning index P n 20% increase;

[0191] Thermal expansion coefficient Rx′ n Preload fine-tuning index P n :

[0192] Thermal expansion coefficient Rx′ n The higher the preload fine-tuning index P n The larger the bolt is, the larger the P is. For example, bolt A and bolt E are 1.05 and 1.04 respectively. n They are 0.65 and 0.54 respectively;

[0193] The thermal expansion coefficient increases by 1%, and the preload fine-tuning index P n Increase by 1%;

[0194] Through the analysis of the above table data and formula, the following beneficial effects of the present invention can be obtained:

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

[0196] For example, in high temperature environment, bolt A can avoid over-tightening due to thermal expansion by reducing the preload to keep it within the appropriate range.

[0197] Bolt B increases the preload force at lower temperature and high evaluation coefficient to ensure the tightening effect;

[0198] Multi-parameter comprehensive control: The present invention provides a more comprehensive preload control solution by comprehensively considering the ambient temperature, the assigned evaluation coefficient and the thermal expansion coefficient to accurately calculate the preload fine-tuning index;

[0199] The preload fine-tuning index of bolt D is relatively stable under moderate ambient temperature and assigned evaluation coefficient, indicating that the system can effectively adjust various working conditions;

[0200] Improve fastening accuracy: Through the compensation fine-tuning strategy, the system can effectively adjust the preload force to keep it within the target range, thus improving fastening accuracy and reliability;

[0201] After fine-tuning the preload force of bolt F, the actual preload force was accurately adjusted to 527N, which was close to the target value, indicating the high-precision adjustment performance of the system in practical applications.

[0202] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0203] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product. Those skilled in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0204] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0205] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in 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 control system using ultrasonic technology, characterized in that: Specifically include: Calibration module: used to calibrate the number of acquisitions of ultrasonic real-time detection to form 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: used to collect the thermal expansion coefficient of the bolt in the i-th data acquisition, and obtain the bolt head temperature, bolt thread temperature, nut temperature, bolt tail temperature and ambient temperature near the bolt to form the i-th temperature detection data set, and upload the data set to the database to record the historical temperature change data of each part of the bolt; Calibration data collection module: used to collect the corresponding bolt calibration data in the i-th data collection, 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, so as to calculate the average temperature of each part of the bolt under the current ambient temperature, and set the warning threshold of each part of the bolt according to these average temperatures; Adjustment module: used to compare and analyze the temperature data of each part of the bolt obtained by the current nth data collection with the corresponding warning threshold, and construct an assigned evaluation coefficient. The assigned 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, so as to calculate the bolt preload after the current torque is applied, and set the target preload range of the current bolt; Index generation module: used to obtain the ambient temperature collected for the nth time, the assigned evaluation coefficient and the thermal expansion coefficient after dynamic adjustment, and perform analysis and processing to generate a 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 torque is applied; Post-processing module: After the bolt preload is adjusted through the compensation fine-tuning strategy, the output of the hydraulic pump in the fixed-axis force construction device is controlled to make the actual preload reach the compensated preload, and in the subsequent tightening process, the adjusted preload is maintained within the set target preload range until the tightening is completed.

2. The fixed-axis force construction device for real-time detection of bolt preload according to claim 1, characterized in that: In the i-th data collection, the thermal expansion coefficient, the temperature of the bolt head, the temperature of the bolt thread part, the temperature of the nut, the temperature of the bolt tail and the ambient temperature near the bolt are marked as Rxi, T1,i, T2,i, T3,i, T4,i, T5,i respectively; The bolt calibration data includes elastic modulus E, initial length L0 of the bolt, calibration speed vcalibration, and actual length Li of the bolt in the i-th data collection; Calculate the average temperature of each part of the bolt under the current ambient temperature, and set the warning threshold of each part of the bolt according to these average temperatures, including: set up represents the average temperature of different parts of the bolt, where j∈{1,2,3,4}, The calculation formula is as follows: Among them, i represents the i-th data collection, and n represents the current n-th data collection; set up is the average temperature under the current ambient temperature, and the calculation formula is as follows: Among them, T5,i represents the ambient temperature collected for the i-th time; According to the calculated average temperature of each part, the warning threshold is set. The setting formula of the warning threshold is as follows: Where, 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: Where, 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 fixed-axis 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 collection, the defined assignment evaluation coefficient is Ej,n, and the calculation formula is as follows: Where, Ej,n is the assignment evaluation coefficient of the j-th part of the bolt in the n-th data collection; Tj,n is the temperature of the jth part of the bolt in the nth data collection; Hj is the warning threshold of the jth part of the bolt; T5,n is the ambient temperature near the bolt in the nth data collection; 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 indicates that the j-th part is closer to the warning threshold; When Ej,n is closer to 1, it indicates that the j-th part is farther away 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 indicates 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 Rxn is between 0% and 1.75%. The dynamic adjustment formula is as follows: And when Tj,n < Hj, it indicates 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 indicates 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 Rxn is between 3.5% and 6.4%. The dynamic adjustment formula is as follows: And when Tj,n < Hj, it indicates 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 indicates that the temperature of this bolt part exceeds the warning threshold, the temperature is seriously high, the assignment evaluation coefficient is high, 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 indicates 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: Where, 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.

4. The 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: Measure the initial length L0 of the bolt using the ultrasonic single-wave technique; Measure the propagation time \(t_0\) of ultrasonic waves in the bolt in the unloaded state and calibrate the speed \(v_{calibration}\); Calculate the initial length \(L_0\) of the bolt based on the initial ultrasonic propagation time \(t_0\) and the calibrated speed \(v_{calibration}\): \(L_0 = v_{calibration}\cdot t_0\) During the \(n\)th data acquisition, when torque is applied to the bolt, measure the ultrasonic propagation time \(t_n\); Calculate the actual length \(L_n\) of the bolt in the current \(n\)th data acquisition: \(L_n = v_{calibration}\cdot t_n\) Calculate the length change \(\Delta L_n\): \(\Delta L_n = L_n - L_0\) Using the bolt calibration data and the length change \(\Delta L_n\), calculate the bolt pre-tightening force \(F_n\) 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 to \((F_{1n}, F_{2n})\), and both \(F_{1n}\) and \(F_{2n}\) are positive numbers, and \(F_{1n}<F_{2n}\).

5. The 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 \(P_n\), and the calculation formula is as follows: Where \(P_n\) is the pre-tightening force fine-tuning index generated in the \(n\)th data acquisition; \(m\) is the total number of detected parts on the bolt; \(E_{j,n}\) is the assignment evaluation coefficient of the \(j\)th part in the \(n\)th data acquisition; \(T_{5,n}\) is the ambient temperature in the \(n\)th data acquisition; \(T_0\) is the reference temperature value used to normalize the influence of temperature change; \(R_x'n\) is the dynamically adjusted coefficient of thermal expansion; \(E_{max}\) is the maximum value of the assignment evaluation coefficient; \(k_1\) is an adjustment factor that determines the sensitivity of the pre-tightening force fine-tuning index, \(0.12\leq k_1\leq0.68\); set the value range of \(P_n\) to \(0 < P_n\leq M\), and \(M\) is the maximum value set according to specific applications; Set the comparison threshold of the pre-tightening force fine-tuning index \(P_n\) to \(U_1\), and \(0.32\leq U_1\leq0.76\), and set the initial reference value of \(U_1\) to \(0.52\); When the pre-tightening force fine-tuning index \(P_n > U_1\), the compensation fine-tuning strategy formula is: \(\Delta F_n=\delta_1\cdot(P_n - U_1)\cdot F_n\) Where \(\Delta F_n\) is the pre-tightening force that needs to be compensated; \(\delta_1\) is the first compensation adjustment coefficient, and the value range of \(\delta_1\) is \(0.1\leq\delta_1\leq0.3\); 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 \(P_n - U_1\); When the pre-tightening force fine-tuning index \(P_n = U_1\), the compensation fine-tuning strategy formula is: \(\Delta F_n=\delta_2\cdot F_n\) Where \(\delta_2\) is the second compensation adjustment coefficient, \(0.01\leq\delta_2\leq0.07\), 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 \(P_n < U_1\), the compensation fine-tuning strategy formula is: \(\Delta F_n=\delta_3\cdot(U_1 - P_n)\cdot F_n\) Where \(\delta_3\) is the third compensation adjustment coefficient, and the value range of \(\delta_3\) is \(0.2\leq\delta_3\leq0.4\), 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 \(U_1 - P_n\).

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