A method for detecting the breaking torque of threaded fasteners

Abstract

The invention discloses a method for detecting the breaking torque of a threaded fastener. Firstly, a supporting disc with a positioning pin is fixed on a two-in-one torque clamping force sensor of a friction performance testing machine, and a breaking torque fixture with a threaded hole is installed. Then, the threaded fastener to be tested is screwed into the threaded hole of the fixture, 2 to 3 pitches are kept exposed, and it is initially fixed with a torque wrench. During the test, the testing machine is started to perform an automated test, and a torque-angle curve is collected and displayed in real time. Once the torque drop is monitored to exceed 20%, the system automatically stops and records the maximum torque value. In the data processing stage, the fastener fracture position is recorded, the torque-angle curve data is derived, and a statistical analysis report is generated. The method has the advantages of being able to significantly improve the accuracy and reliability of the detection data, reduce the interference of human factors, and realize the automation of the detection process.

Description

Technical Field

[0001] The invention relates to the technical field of threaded fastener detection, and in particular to a threaded fastener breaking torque detection method. Background Art

[0002] The breaking torque of threaded fasteners refers to the torque value required when fasteners (such as bolts, nuts, etc.) are tightened to break. This parameter is crucial for evaluating the mechanical properties and safety of fasteners. In industrial production, the breaking torque of fasteners directly affects the stability and safety of the assembly structure. If the breaking torque is too low, the fasteners may loosen or break during use, causing safety accidents; if the breaking torque is too high, the fasteners or connecting parts may be damaged during installation. Therefore, accurately detecting the breaking torque of threaded fasteners is of great significance to ensure product quality and safety.

[0003] At present, the detection of the breaking torque of threaded fasteners usually adopts the traditional manual method. The specific steps are as follows: fix the fastener to be tested in the breaking torque fixture, and then use the torque wrench to gradually increase the torque until the fastener breaks. Record the maximum torque value displayed by the torque wrench as the breaking torque of the fastener. This traditional detection method is still widely used in many manufacturing companies because it requires simple equipment and is easy to operate.

[0004] Although the traditional manual detection method has certain advantages, it also has obvious shortcomings:

[0005] 1. Accuracy problem: The accuracy of torque wrenches is low, usually only about ±4%, which will lead to large errors in test results and affect the accuracy of data;

[0006] 2. Human factors: The testing process is highly dependent on manual operation. Differences in strength, movement speed, and operating skills among different testers can lead to inconsistencies in test results.

[0007] 3. Data recording: The traditional manual method can only record the final torque value, and cannot record other data in the test process in detail, such as the torque change curve, which is not conducive to subsequent analysis and process tracing;

[0008] 4. Inefficiency: Manual detection methods are time-consuming and require a lot of human resources, which is not suitable for large-scale production and automated production lines.

[0009] In order to overcome the above shortcomings and improve the accuracy of test data and the degree of automation of the test process, it is necessary to develop a new detection method. Summary of the invention

[0010] The object of the present invention is to provide a method for detecting the breaking torque of a threaded fastener, which can significantly improve the accuracy and reliability of detection data, reduce the interference of human factors, and realize the automation of the detection process.

[0011] To achieve the above object, the present invention provides the following technical solution: a method for detecting the breaking torque of a threaded fastener, comprising the following steps:

[0012] S1. Clamping and positioning:

[0013] Fix the supporting disc with the positioning pin on the two-in-one torque clamping force sensor of the friction performance testing machine, and the positioning pin matches the positioning hole on the two-in-one torque clamping force sensor;

[0014] Installing a breaking torque fixture with threaded holes in the clamping portion of the support disc;

[0015] S2. Sample installation:

[0016] Screw the threaded fastener to be tested into the threaded hole of the breaking torque fixture until the thread is exposed 2-3P;

[0017] Use a torque wrench to initially secure the threaded fasteners;

[0018] S3. Parameter settings:

[0019] Set the speed to 10±0.5rpm;

[0020] Set the torque sampling frequency to 1000Hz;

[0021] Set the angle sampling frequency to 500Hz;

[0022] The fracture judgment condition is set to a sudden drop of 20% in torque;

[0023] S4. Execute the test:

[0024] Start the friction performance testing machine for automatic testing;

[0025] Real-time acquisition and display of torque-angle curve;

[0026] When a 20% torque drop is detected, the machine will automatically stop and record the maximum torque value;

[0027] S5. Data processing:

[0028] Record the fracture location of threaded fasteners;

[0029] Export torque-angle curve data and generate data statistical analysis report.

[0030] Preferably, the step S3 also includes establishing an intelligent early warning mechanism:

[0031] Step 1: Theoretical calculation:

[0032] Calculate the theoretical breaking torque T according to the nominal diameter d and strength grade of the threaded fastener. b :

[0033] T b =σ b ×0.2d 3

[0034] where σ b is the tensile strength of threaded fasteners;

[0035] Step 2: Setting the warning value:

[0036] Set the first level warning value to T b 70%;

[0037] Set the second level warning value to T b 80%;

[0038] Set the third level warning value to T b 90%;

[0039] Step 3: Early warning response:

[0040] When the torque reaches the first-level warning value, an audible and visual prompt is issued, a warning message is displayed on the test interface, and the current torque and angle values ​​are recorded;

[0041] When the torque reaches the second-level warning value, the speed is automatically reduced to 5rpm, the sampling frequency is increased to 2000Hz, and vibration monitoring is started;

[0042] When the torque reaches the third-level warning value, the speed is further reduced to 2rpm and emergency shutdown is prepared.

[0043] Preferably, the specific steps of vibration monitoring are as follows:

[0044] Step 1: Install the triaxial acceleration sensor on the breaking torque fixture;

[0045] Step 2: Set the sampling frequency to 5000 Hz and synchronously collect acceleration signals in the X, Y, and Z directions;

[0046] Step 3: Use the fast Fourier transform algorithm to process the collected vibration signal, extract the main frequency component and spectrum characteristics, and calculate the amplitude, frequency and energy distribution of the vibration signal;

[0047] Step 4: The vibration amplitude threshold is preset to 0.5g. When the vibration amplitude exceeds the threshold, the speed is automatically reduced by 10%-30%, and the interval between each speed reduction is not less than 1 second. The final speed is not less than 50% of the original set speed.

[0048] Step 5: When any of the following abnormal conditions occurs, an emergency shutdown is triggered immediately:

[0049] a. The main frequency component of the vibration spectrum suddenly changes by more than 50% of the original reference value;

[0050] b. The vibration amplitude exceeds 1g in a short period of time;

[0051] c. The vibration spectrum shows obvious nonlinear characteristics.

[0052] Preferably, step S4 also includes a real-time monitoring step for monitoring the torque change rate and the angle change rate and dynamically adjusting the test process, which specifically includes the following steps:

[0053] Step 1: Torque change rate monitoring:

[0054] Real-time calculation of torque change rate ΔM / Δt, where ΔM represents the torque increment and Δt represents the time interval;

[0055] Step 2: Angle change rate monitoring:

[0056] Calculate the angle change rate Δθ / Δt in real time, where Δθ represents the angle increment and Δt represents the time interval;

[0057] Step 3: Trigger condition determination:

[0058] When any of the following conditions is detected, the test will be automatically paused:

[0059] ΔM / Δt>5N·m / s, indicating that the torque growth rate exceeds the threshold, which may lead to abnormal stress concentration;

[0060] Δθ / Δt<0.5° / s, indicating that the angle change speed is lower than the threshold, and the device may be stuck or the test may be abnormal;

[0061] Step 4: Pause response:

[0062] When the pause condition is triggered, the friction performance tester automatically stops and maintains the current state, while recording the torque, angle and time data of the abnormal point.

[0063] Preferably, the step S5 also includes a step of strength calculation, which specifically includes the following steps:

[0064] Step 1: Torsional strength calculation:

[0065] Calculate the torsional strength τ of threaded fasteners based on the torque value and geometric dimensions of the threaded fasteners B , the formula is as follows:

[0066]

[0067] Where M is the maximum torque value of the threaded fastener, t is the effective pitch of the thread, and d is the nominal diameter of the threaded fastener;

[0068] Step 2: Shear strain calculation:

[0069] Calculate the shear strain γ of threaded fasteners using the following formula: Where d is the nominal diameter of the threaded fastener, θ is the angle change when the threaded fastener breaks, and L is the length of the force-bearing section of the threaded fastener.

[0070] Preferably, step S5 also includes a temperature compensation calculation step, which specifically includes the following steps:

[0071] Step 1: Temperature monitoring:

[0072] The current ambient temperature T is monitored in real time by a temperature sensor installed in the friction performance tester;

[0073] Step 2: Temperature compensation calculation:

[0074] According to the following formula, the maximum torque value M obtained from the test is corrected to obtain the torque value M after temperature compensation. t ;

[0075] M t =M×[1+α(T-20)], where M is the actual measured maximum torque value, α is the temperature compensation coefficient, T is the real-time monitored ambient temperature, and 20 is the reference temperature value.

[0076] Preferably, the step S5 also includes a step of determining data anomaly during the test process:

[0077] Step 1: Create a torque-angle reference curve:

[0078] Collect test data of at least 10 samples of the same specification, calculate the average torque-angle curve, and determine the standard deviation range of each characteristic point;

[0079] Step 2: Real-time data analysis:

[0080] Calculate the deviation between the current test curve and the reference curve, monitor the slope change of the torque rising section, and record the ratio of the angle increment to the torque increment;

[0081] Step 3: Abnormal determination conditions:

[0082] When one of the following situations occurs, it is considered abnormal and the test is automatically suspended:

[0083] The torque-angle curve deviates from the reference curve by ±3 standard deviations;

[0084] There is a sudden change or step in the torque rising section;

[0085] The ratio of the angle increment to the torque increment exceeds the preset range by ±20%.

[0086] Preferably, the clamping and positioning in step S1 further includes the following specific steps:

[0087] Step 1: Check the support disc before installation:

[0088] Check that the outer circle runout of the locating pin does not exceed 0.01mm, check that the flatness error of the supporting disc does not exceed 0.02mm, clean the contact surface between the supporting disc and the sensor to ensure that there is no oil or impurities.

[0089] Step 2: Destruction torque fixture installation control:

[0090] Use a micrometer to check the coaxiality of the fixture, and the deviation should not exceed 0.03mm. Use a torque wrench to cross-tighten the clamping bolts with a torque value of 30±2N·m. Use a laser alignment instrument to ensure that the parallelism error between the center line of the fixture and the axis of the sensor is less than 0.1°.

[0091] Preferably, the sample installation in step S2 includes the following specific steps:

[0092] Step 1: Threaded hole pretreatment:

[0093] Use compressed air to clean the threaded hole, use an internal thread gauge to check the go / no-go gauge fit of the threaded hole, and measure the axial circular runout of the threaded hole to ensure that it is within 0.05mm.

[0094] Step 2: Torque wrench control:

[0095] First, pre-tighten with a torque of 2 N·m, pause for 3 seconds, increase to 3.5 N·m, and finally reach 5 N·m. Hold for 2 seconds and then release the wrench to complete the installation.

[0096] Compared with the prior art, the advantages of the present invention are that the method for detecting the destructive torque of threaded fasteners realizes an efficient and accurate detection process through precise steps and scientific parameter settings. Its working principle is to use a friction performance testing machine for automated testing, and to systematize the destructive torque test process of threaded fasteners by combining the five steps of clamping and positioning, sample installation, parameter setting, test execution and data processing. First, the stability of the clamping of the testing machine and the precise positioning of the sample are ensured by the coordination of the locating pin and the fixture. Then, a pre-tightening force is applied to the threaded fasteners through a torque wrench to ensure that the installation of the fasteners meets the standards. Then, by setting precise speed, torque and angle sampling frequencies, as well as fracture judgment conditions, the test process has high reliability and sensitivity.

[0097] During the test execution phase, the torque-angle curve is collected in real time to ensure that the details of each test point are recorded. When a sudden drop of 20% in torque is detected, the machine automatically stops and locks the maximum torque value to avoid additional damage caused by overload. During the data processing phase, by recording the fracture position, exporting the test curve, and generating a report containing multiple key parameters, a scientific basis is provided for the performance evaluation and data traceability of threaded fasteners. This method has the advantages of high degree of automation, high test accuracy, comprehensive data recording and high operating efficiency. It can effectively solve the problems of low accuracy, incomplete data and low operating efficiency of traditional manual detection methods, and is suitable for batch detection and performance evaluation of threaded fasteners in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0099] Figure 1 It is a flowchart of the present invention;

[0100] Figure 2 It is a three-dimensional structural schematic diagram of the testing process of the present invention;

[0101] Figure 3 The present invention Figure 2 A cross-sectional view of

[0102] Figure 4 is a torque-angle graph of the present invention;

[0103] In the figure, 1. Support disc; 2. Friction performance testing machine; 3. Two-in-one torque clamping force sensor; 4. Destructive torque fixture. DETAILED DESCRIPTION

[0104] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0105] Embodiment: As shown in the figure, a method for detecting the breaking torque of a threaded fastener comprises the following steps:

[0106] S1. Clamping and positioning:

[0107] The supporting disc 1 with the positioning pin is fixed on the two-in-one torque clamping force sensor 3 of the friction performance testing machine 2, and the positioning pin is matched with the positioning hole on the two-in-one torque clamping force sensor 3;

[0108] Install the breaking torque fixture 4 with threaded holes in the clamping portion of the support disc 1;

[0109] S2. Sample installation:

[0110] Screw the threaded fastener to be tested into the threaded hole of the breaking torque fixture 4 until the thread is exposed 2-3P;

[0111] Use a torque wrench to initially secure the threaded fasteners;

[0112] S3. Parameter settings:

[0113] Set the speed to 10±0.5rpm;

[0114] Set the torque sampling frequency to 1000Hz;

[0115] Set the angle sampling frequency to 500Hz;

[0116] The fracture judgment condition is set to a sudden drop of 20% in torque;

[0117] S4. Execute the test:

[0118] Start the friction performance testing machine 2 to perform automatic testing;

[0119] Real-time acquisition and display of torque-angle curve;

[0120] When a 20% torque drop is detected, the machine will automatically stop and record the maximum torque value;

[0121] S5. Data processing:

[0122] Record the fracture location of threaded fasteners;

[0123] Export torque-angle curve data and generate data statistical analysis report.

[0124] In this embodiment, the step S3 also includes establishing an intelligent early warning mechanism:

[0125] Step 1: Theoretical calculation:

[0126] Calculate the theoretical breaking torque T according to the nominal diameter d and strength grade of the threaded fastener. b :

[0127] T b =σ b ×0.2d 3

[0128] where σb is the tensile strength of threaded fasteners;

[0129] Step 2: Setting the warning value:

[0130] Set the first level warning value to T b 70%;

[0131] Set the second level warning value to T b 80%;

[0132] Set the third level warning value to T b 90%;

[0133] Step 3: Early warning response:

[0134] When the torque reaches the first-level warning value, an audible and visual prompt is issued, a warning message is displayed on the test interface, and the current torque and angle values ​​are recorded;

[0135] When the torque reaches the second-level warning value, the speed is automatically reduced to 5rpm, the sampling frequency is increased to 2000Hz, and vibration monitoring is started;

[0136] When the torque reaches the third-level warning value, the speed is further reduced to 2rpm and emergency shutdown is prepared.

[0137] The advantage of this process is that it can effectively improve the safety, efficiency and accuracy of threaded fastener breaking torque detection. By establishing an intelligent early warning mechanism, it is possible to predict in advance that the threaded fastener is about to reach the breaking torque, and take timely measures to avoid accidents and improve test safety.

[0138] For example, when the torque reaches the first-level warning value, the system will issue an audible and visual prompt, display a warning message on the test interface, record the current torque and angle values, alert the operator, and promptly adjust the test parameters or stop the test to avoid excessive stress on threaded fasteners. When the torque reaches the second-level warning value, the system will automatically reduce the speed, increase the sampling frequency, and start vibration monitoring, which can more accurately capture the critical point of damage of threaded fasteners and improve test efficiency. When the torque reaches the third-level warning value, the system will further reduce the speed to 2rpm and prepare for emergency shutdown to prevent accidental damage to threaded fasteners due to excessive stress, further improving test safety.

[0139] In this embodiment, the specific steps of vibration monitoring are as follows:

[0140] Step 1: Install the triaxial acceleration sensor on the breaking torque fixture 4;

[0141] Step 2: Set the sampling frequency to 5000 Hz and synchronously collect acceleration signals in the X, Y, and Z directions;

[0142] Step 3: Use the fast Fourier transform algorithm to process the collected vibration signal, extract the main frequency component and spectrum characteristics, and calculate the amplitude, frequency and energy distribution of the vibration signal;

[0143] Step 4: The vibration amplitude threshold is preset to 0.5g. When the vibration amplitude exceeds the threshold, the speed is automatically reduced by 10%-30%, and the interval between each speed reduction is not less than 1 second. The final speed is not less than 50% of the original set speed.

[0144] Step 5: When any of the following abnormal conditions occurs, an emergency shutdown is triggered immediately:

[0145] a. The main frequency component of the vibration spectrum suddenly changes by more than 50% of the original reference value;

[0146] b. The vibration amplitude exceeds 1g in a short period of time;

[0147] c. The vibration spectrum shows obvious nonlinear characteristics.

[0148] This step determines the stress condition of the threaded fasteners by monitoring the vibration signals of the threaded fasteners during the destructive torque test, and takes timely measures to prevent accidental damage to the threaded fasteners due to excessive stress. Specifically, this step collects the vibration signals of the threaded fasteners in real time by installing a three-axis acceleration sensor on the destructive torque fixture 4, and uses the fast Fourier transform algorithm to analyze the spectral characteristics of the vibration signal, extract information such as the main frequency component and amplitude, and the fast Fourier transform algorithm can convert the time domain signal into a frequency domain signal, so as to more conveniently analyze the frequency characteristics of the vibration signal and identify possible abnormal conditions. When the vibration signal is abnormal, the system will automatically reduce the speed, and take corresponding measures according to the specific abnormal conditions of the vibration signal, such as reducing the speed, triggering an emergency shutdown, etc., to ensure the safety and reliability of the test process.

[0149] This step can predict the risk of impending damage to the threaded fasteners in advance by real-time monitoring of the vibration signals of the threaded fasteners, and take timely measures to avoid accidents and improve the safety of the test. By analyzing the spectral characteristics of the vibration signal, the stress condition of the threaded fasteners can be judged more accurately, and the critical point of damage to the threaded fasteners can be predicted based on the changing trend of the vibration signal to improve the test accuracy. In addition, by automatically reducing the rotation speed, the stress condition of the threaded fasteners can be effectively controlled to avoid damage to the threaded fasteners due to excessive stress, further improving the safety of the test. At the same time, by taking timely measures, the test losses caused by accidental damage to the threaded fasteners can be reduced, the test costs can be reduced, the test time can be shortened, and the test efficiency can be improved.

[0150] In this embodiment, step S4 also includes a real-time monitoring step for monitoring the torque change rate and the angle change rate and dynamically adjusting the test process, which specifically includes the following steps:

[0151] Step 1: Torque change rate monitoring:

[0152] Calculate the torque change rate ΔM / Δt in real time, where ΔM represents the torque increment and Δt represents the time interval; in order to improve the monitoring accuracy, a smaller time interval Δt, such as 100ms or shorter, may be used;

[0153] Step 2: Angle change rate monitoring:

[0154] Calculate the angle change rate Δθ / Δt in real time, where Δθ represents the angle increment and Δt represents the time interval;

[0155] Step 3: Trigger condition determination:

[0156] When any of the following conditions is detected, the test will be automatically paused:

[0157] ΔM / Δt>5N·m / s, indicating that the torque growth rate exceeds the threshold, which may lead to abnormal stress concentration;

[0158] Δθ / Δt<0.5° / s, indicating that the angle change speed is lower than the threshold, and the device may be stuck or the test may be abnormal;

[0159] Step 4: Pause response:

[0160] When the pause condition is triggered, the friction performance tester 2 automatically stops and maintains the current state, while recording the torque, angle and time data of the abnormal point.

[0161] By real-time monitoring of the torque change rate and angle change rate, abnormal stress conditions and rotation states of threaded fasteners can be discovered in time, and timely measures can be taken to avoid test failure or equipment damage due to excessive stress or jamming, thereby improving test safety.

[0162] By monitoring the angle change rate, equipment jams or test abnormalities can be discovered in a timely manner, and the test can be paused in a timely manner to avoid inaccurate test results or the inability to continue the test process due to jams, thereby improving test reliability; by dynamically adjusting the test process, test interruptions due to abnormal conditions can be effectively avoided, thereby improving test efficiency.

[0163] The application of this step can effectively reduce test risks, improve the accuracy and reliability of test results, shorten test time and improve test efficiency.

[0164] In this embodiment, the step S5 also includes a step of strength calculation, which specifically includes the following steps:

[0165] Step 1: Torsional strength calculation:

[0166] Calculate the torsional strength τ of threaded fasteners based on the torque value and geometric dimensions of the threaded fasteners B , the formula is as follows:

[0167]

[0168] Where M is the maximum torque value of the threaded fastener, t is the effective pitch of the thread, and d is the nominal diameter of the threaded fastener;

[0169] Step 2: Shear strain calculation:

[0170] Calculate the shear strain γ of threaded fasteners using the following formula: Where d is the nominal diameter of the threaded fastener, θ is the angle change when the threaded fastener breaks, and L is the length of the force-bearing section of the threaded fastener.

[0171] Adding a strength calculation step to the destructive torque test actually combines the destructive torque test with material mechanics analysis to more comprehensively evaluate the performance of threaded fasteners. This step measures the maximum torque value and angle change of the threaded fastener during the destructive torque test, and calculates its torsional strength and shear strain in combination with the geometric dimensions of the threaded fastener, thereby determining the strength and toughness of the threaded fastener. The advantage of this method is that it can more comprehensively evaluate the performance of threaded fasteners, improve the accuracy of test results, and provide a reference for material optimization. By calculating the torsional strength and shear strain, the actual strength of the threaded fastener can be more accurately determined, avoiding misjudgment caused by focusing only on the destructive torque value. At the same time, the torsional strength and shear strain of different materials can also be understood, providing a reference for material selection and optimization of threaded fasteners.

[0172] In this embodiment, step S5 also includes a temperature compensation calculation step, which specifically includes the following steps:

[0173] Step 1: Temperature monitoring:

[0174] The current ambient temperature T is monitored in real time by a temperature sensor installed in the friction performance tester 2;

[0175] Step 2: Temperature compensation calculation:

[0176] According to the following formula, the maximum torque value M obtained from the test is corrected to obtain the torque value M after temperature compensation. t ;

[0177] M t=M×[1+α(T-20)], where M is the actual measured maximum torque value, α is the temperature compensation coefficient, T is the real-time monitored ambient temperature, and 20 is the reference temperature value.

[0178] The addition of temperature compensation calculation in step S5 actually takes the influence of ambient temperature into consideration in the friction performance test, which makes the test results more accurately reflect the performance of the threaded fastener in the actual use environment.

[0179] The working principle of this step is to monitor the ambient temperature in real time and correct the maximum torque value obtained from the test according to the temperature compensation formula, thereby eliminating the influence of the ambient temperature on the test results.

[0180] For example, assuming that the strength of the material of a threaded fastener decreases when the temperature rises, and the ambient temperature during the test is higher than the standard temperature, if temperature compensation is not performed, the test results will be low and cannot truly reflect the actual performance of the threaded fastener at the standard temperature. Through temperature compensation calculation, the test results can be corrected to the value at the standard temperature, thereby eliminating the influence of the ambient temperature and making the test results more accurate.

[0181] The advantages of this structure are mainly reflected in the following aspects:

[0182] Improve the accuracy of test results: Ambient temperature affects the strength and friction coefficient of the material, thus affecting the torque value of threaded fasteners. Through temperature compensation calculation, the influence of ambient temperature can be eliminated, so that the test results can more accurately reflect the actual performance of threaded fasteners.

[0183] Improve the comparability of test results: When testing in different temperature environments, if temperature compensation is not performed, the test results cannot be directly compared. Through temperature compensation calculation, the test results in different temperature environments can be unified to the same reference temperature, improving the comparability of test results.

[0184] Improve the reliability of test results: Temperature compensation calculations can improve the reliability of test results and make the test results closer to the actual performance of threaded fasteners in actual use environments.

[0185] In this embodiment, the step S5 also includes a data anomaly determination step during the test process:

[0186] Step 1: Create a torque-angle reference curve:

[0187] Collect test data of at least 10 samples of the same specification, calculate the average torque-angle curve, and determine the standard deviation range of each characteristic point;

[0188] Step 2: Real-time data analysis:

[0189] Calculate the deviation between the current test curve and the reference curve, monitor the slope change of the torque rising section, and record the ratio of the angle increment to the torque increment;

[0190] Step 3: Abnormal determination conditions:

[0191] When one of the following situations occurs, it is considered abnormal and the test is automatically suspended:

[0192] The torque-angle curve deviates from the reference curve by ±3 standard deviations;

[0193] There is a sudden change or step in the torque rising section;

[0194] The ratio of the angle increment to the torque increment exceeds the preset range by ±20%.

[0195] The data anomaly determination step in step S5 establishes a torque-angle reference curve and uses real-time data analysis to compare the current test curve with the reference curve to determine whether an abnormal situation occurs during the test process. This brings many benefits to the test process.

[0196] First, it significantly improves the reliability of the test results. During the test, due to the influence of various factors, some abnormal conditions may occur, such as threaded fasteners breaking and thread slipping. Through real-time data analysis, these abnormal conditions can be discovered in time and the test can be automatically suspended to avoid deviations in the test results, thereby ensuring the authenticity and accuracy of the test results. This step effectively improves the test efficiency. Through real-time data analysis, abnormal conditions can be discovered in time and the test can be automatically suspended to avoid unexpected situations during the test process, thereby reducing unnecessary test time, improving test efficiency, and ensuring the safety and reliability of the test process.

[0197] In this embodiment, the clamping and positioning in step S1 further includes the following specific steps:

[0198] Step 1: Check the support disc 1 before installation:

[0199] Check that the outer circle runout of the locating pin does not exceed 0.01mm, check that the flatness error of the support disc 1 does not exceed 0.02mm, and clean the contact surface between the support disc 1 and the sensor to ensure that there is no oil or impurities.

[0200] Step 2: Destruction torque fixture 4 installation control:

[0201] Use a micrometer to check the coaxiality of the fixture, and the deviation should not exceed 0.03mm. Use a torque wrench to cross-tighten the clamping bolts with a torque value of 30±2N·m. Use a laser alignment instrument to ensure that the parallelism error between the center line of the fixture and the axis of the sensor is less than 0.1°.

[0202] The clamping and positioning step in step S1 includes strict control of the installation accuracy of the support disc 1 and the breaking torque fixture 4 to ensure the accuracy and reliability of the test process.

[0203] Specifically, the above step 1 is to perform a pre-installation inspection on the support disc 1, mainly to ensure the flatness of the support disc 1 and the accuracy of the positioning pin, to avoid the threaded fasteners from tilting or shifting during the test due to the flatness error of the support disc 1 or the runout of the positioning pin, thereby affecting the accuracy of the test results.

[0204] The second step is to control the installation of the destructive torque fixture 4, which is mainly to ensure the coaxiality of the fixture, the tightening torque of the clamping bolt and the parallelism between the center line of the fixture and the axis of the sensor, so as to avoid uneven force on the threaded fasteners during the test due to the installation error of the fixture, thereby affecting the accuracy and reliability of the test results.

[0205] In this embodiment, the sample installation in step S2 includes the following specific steps:

[0206] Step 1: Threaded hole pretreatment:

[0207] Use compressed air to clean the threaded hole, use an internal thread gauge to check the go / no-go gauge fit of the threaded hole, and measure the axial circular runout of the threaded hole to ensure that it is within 0.05mm.

[0208] Step 2: Torque wrench control:

[0209] First, pre-tighten with a torque of 2 N·m, pause for 3 seconds, increase to 3.5 N·m, and finally reach 5 N·m. Hold for 2 seconds and then release the wrench to complete the installation.

[0210] The specimen installation steps in the above steps, by pre-processing the threaded holes and controlling the torque wrench, can ensure that the threaded fasteners are accurately installed on the test device and in close contact with the test device, providing a reliable connection for subsequent testing processes, thereby improving the accuracy and reliability of the test results.

[0211] The first step is to pre-treat the threaded holes, which is mainly to ensure the cleanliness and accuracy of the threaded holes, and to avoid loose installation of threaded fasteners or stress concentration due to dirt or accuracy errors in the threaded holes, thereby affecting the accuracy of the test results.

[0212] The second step is to control the torque wrench, which is mainly to ensure the installation torque of the threaded fasteners and avoid over-tightening or loosening of the threaded fasteners due to excessive or insufficient installation torque, thereby affecting the accuracy and reliability of the test results.

[0213] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for detecting the breaking torque of a threaded fastener, characterized in that: The following steps are involved: S1. Clamping and positioning: Fix the supporting disc with the positioning pin on the two-in-one torque clamping force sensor of the friction performance testing machine, and the positioning pin matches the positioning hole on the two-in-one torque clamping force sensor; Installing a breaking torque fixture with threaded holes in the clamping portion of the support disc; S2. Sample installation: Screw the threaded fastener to be tested into the threaded hole of the breaking torque fixture until the thread is exposed 2-3P; Use a torque wrench to initially secure the threaded fasteners; S3. Parameter settings: Set the speed to 10±0.5rpm; Set the torque sampling frequency to 1000Hz; Set the angle sampling frequency to 500Hz; The fracture judgment condition is set to a sudden drop of 20% in torque; S4. Execute the test: Start the friction performance testing machine for automatic testing; Real-time acquisition and display of torque-angle curve; When a 20% torque drop is detected, the machine will automatically stop and record the maximum torque value; S5. Data processing: Record the fracture location of threaded fasteners; Export torque-angle curve data and generate data statistical analysis report.

2. A method for detecting the breaking torque of a threaded fastener according to claim 1, characterized in that: The S3 step also includes establishing an intelligent early warning mechanism: Step 1: Theoretical calculation: Calculate the theoretical breaking torque T according to the nominal diameter d and strength grade of the threaded fastener. b : T b =σ b ×0.2d 3 where σ b is the tensile strength of threaded fasteners; Step 2: Setting the warning value: Set the first level warning value to T b 70%; Set the second level warning value to T b 80%; Set the third level warning value to T b 90%; Step 3: Early warning response: When the torque reaches the first-level warning value, an audible and visual prompt is issued, a warning message is displayed on the test interface, and the current torque and angle values ​​are recorded; When the torque reaches the second-level warning value, the speed is automatically reduced to 5rpm, the sampling frequency is increased to 2000Hz, and vibration monitoring is started; When the torque reaches the third-level warning value, the speed is further reduced to 2rpm and emergency shutdown is prepared.

3. A method for detecting the breaking torque of a threaded fastener according to claim 2, characterized in that: The specific steps of vibration monitoring are as follows: Step 1: Install the triaxial acceleration sensor on the breaking torque fixture; Step 2: Set the sampling frequency to 5000 Hz and synchronously collect acceleration signals in the X, Y, and Z directions; Step 3: Use the fast Fourier transform algorithm to process the collected vibration signal, extract the main frequency component and spectrum characteristics, and calculate the amplitude, frequency and energy distribution of the vibration signal; Step 4: The vibration amplitude threshold is preset to 0.5g. When the vibration amplitude exceeds the threshold, the speed is automatically reduced by 10%-30%, and the interval between each speed reduction is not less than 1 second. The final speed is not less than 50% of the original set speed. Step 5: When any of the following abnormal conditions occurs, an emergency shutdown is triggered immediately: a. The main frequency component of the vibration spectrum suddenly changes by more than 50% of the original reference value; b. The vibration amplitude exceeds 1g in a short period of time; c. The vibration spectrum shows obvious nonlinear characteristics.

4. A method for detecting the breaking torque of a threaded fastener according to claim 1, characterized in that: Step S4 also includes a real-time monitoring step for monitoring the torque change rate and the angle change rate and dynamically adjusting the test process, which specifically includes the following steps: Step 1: Torque change rate monitoring: Real-time calculation of torque change rate ΔM / Δt, where ΔM represents the torque increment and Δt represents the time interval; Step 2: Angle change rate monitoring: Calculate the angle change rate Δθ / Δt in real time, where Δθ represents the angle increment and Δt represents the time interval; Step 3: Trigger condition determination: When any of the following conditions is detected, the test will be automatically paused: ΔM / Δt>5N·m / s, indicating that the torque growth rate exceeds the threshold, which may lead to abnormal stress concentration; Δθ / Δt<0.5° / s, indicating that the angle change speed is lower than the threshold, and the device may be stuck or the test may be abnormal; Step 4: Pause response: When the pause condition is triggered, the friction performance tester automatically stops and maintains the current state, while recording the torque, angle and time data of the abnormal point.

5. A method for detecting the breaking torque of a threaded fastener according to claim 1, characterized in that: The step S5 also includes a step of strength calculation, which specifically includes the following steps: Step 1: Torsional strength calculation: Calculate the torsional strength τ of threaded fasteners based on the torque value and geometric dimensions of the threaded fasteners B , the formula is as follows: Where M is the maximum torque value of the threaded fastener, t is the effective pitch of the thread, and d is the nominal diameter of the threaded fastener; Step 2: Shear strain calculation: Calculate the shear strain γ of threaded fasteners using the following formula: Where d is the nominal diameter of the threaded fastener, θ is the angle change when the threaded fastener breaks, and L is the length of the force-bearing section of the threaded fastener.

6. A method for detecting the breaking torque of a threaded fastener according to claim 1, characterized in that: Step S5 also includes a temperature compensation calculation step, which specifically includes the following steps: Step 1: Temperature monitoring: The current ambient temperature T is monitored in real time by a temperature sensor installed in the friction performance tester; Step 2: Temperature compensation calculation: According to the following formula, the maximum torque value M obtained from the test is corrected to obtain the torque value M after temperature compensation. t ; M t =M×[1+α(T-20)], where M is the actual measured maximum torque value, α is the temperature compensation coefficient, T is the real-time monitored ambient temperature, and 20 is the reference temperature value.

7. A method for detecting the breaking torque of a threaded fastener according to claim 1, characterized in that: The step S5 also includes a data anomaly determination step during the test process: Step 1: Create a torque-angle reference curve: Collect test data of at least 10 samples of the same specification, calculate the average torque-angle curve, and determine the standard deviation range of each characteristic point; Step 2: Real-time data analysis: Calculate the deviation between the current test curve and the reference curve, monitor the slope change of the torque rising section, and record the ratio of the angle increment to the torque increment; Step 3: Abnormal determination conditions: When one of the following situations occurs, it is considered abnormal and the test is automatically suspended: The torque-angle curve deviates from the reference curve by ±3 standard deviations; There is a sudden change or step in the torque rising section; The ratio of the angle increment to the torque increment exceeds the preset range by ±20%.

8. A method for detecting the breaking torque of a threaded fastener according to claim 1, characterized in that: The clamping and positioning in step S1 also includes the following specific steps: Step 1: Check the support disc before installation: Check that the outer circle runout of the locating pin does not exceed 0.01mm, check that the flatness error of the supporting disc does not exceed 0.02mm, clean the contact surface between the supporting disc and the sensor to ensure that there is no oil or impurities. Step 2: Destruction torque fixture installation control: Use a micrometer to check the coaxiality of the fixture, and the deviation should not exceed 0.03mm. Use a torque wrench to cross-tighten the clamping bolts with a torque value of 30±2N·m. Use a laser alignment instrument to ensure that the parallelism error between the center line of the fixture and the axis of the sensor is less than 0.1°.

9. A method for detecting the breaking torque of a threaded fastener according to claim 1, characterized in that: The sample installation in step S2 includes the following specific steps: Step 1: Threaded hole pretreatment: Use compressed air to clean the threaded hole, use an internal thread gauge to check the go / no-go gauge fit of the threaded hole, and measure the axial circular runout of the threaded hole to ensure that it is within 0.05mm. Step 2: Torque wrench control: First, pre-tighten with a torque of 2 N·m, pause for 3 seconds, increase to 3.5 N·m, and finally reach 5 N·m. Hold for 2 seconds and then release the wrench to complete the installation.

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