High-precision bolt tightening method with corner compensation and self-correction functions

Abstract

The invention discloses a high-precision bolt tightening method with corner compensation and self-correction functions, and relates to the technical field of high-precision equipment. The method comprises the following steps: calculating a target torque and an initial torque according to a target pre-tightening force, loading the initial torque to fit a connected piece, and measuring an initial pre-tightening force of a bolt; calculating a first compensation rotation angle by adopting a rotation angle method according to a first difference pretightening force of the difference between the target pretightening force and the initial pretightening force, and implementing the first compensation rotation angle; measuring the compensated pre-tightening force after the first rotation angle compensation, calculating a second difference pre-tightening force of the difference between the compensated pre-tightening force and the initial pre-tightening force, judging whether self-correction is needed or not, and if so, correcting the error through self-correction of the ultrasonic dynamometer and obtaining the compensated pre-tightening force; finally, a third difference pretightening force which is the difference between the compensated pretightening force and the target pretightening force is applied again, so that the target pretightening force can be achieved; by means of the method, the bolt tightening precision can be effectively improved, the correction cost is reduced, and the overall performance and reliability of bolt tightening are improved.

Description

Technical Field

[0001] This invention relates to the field of high-precision equipment technology, and in particular to a high-precision bolt tightening method with rotation compensation and self-correction functions. Background Technology

[0002] In engineering practice, precise control and measurement of preload has been a long-standing technical challenge. In actual assembly, it is usually difficult to directly measure and obtain the preload value of bolts in real time. Therefore, a variety of indirect control methods have been developed. The common torque method has problems such as low accuracy, uncertainty of torque coefficient due to too many factors affecting the friction coefficient, and difficulty in real-time detection of abnormal friction conditions. Although the torque-angle method has improved accuracy compared to the torque method, it still cannot avoid the error introduced by the uncertainty of torque coefficient.

[0003] Existing mainstream tightening methods (torque method, torque-angle method) have reached a bottleneck in accuracy due to limitations in their principles, making it difficult to meet higher requirements. Meanwhile, the most advanced direct measurement technology, ultrasonic method, only stays at the "measurement" level and has failed to be effectively combined with "control execution" to form an intelligent closed-loop system. Summary of the Invention

[0004] The purpose of this invention is to provide a high-precision bolt tightening method with rotation compensation and self-correction functions. It combines the rotation compensation method with the self-correction function of the measuring tool, effectively improving the tightening accuracy of bolts and is suitable for the accuracy requirements of key fields such as aerospace and high-end equipment.

[0005] To achieve the above objectives, the present invention provides a high-precision bolt tightening method with rotation compensation and self-correction functions, comprising the following steps: S1. Based on the target preload of the bolt Calculate the target torque and initial torque ; S2, Input the initial torque of S1 via an automatic torque wrench. The connected parts are brought into contact, and the initial preload of the bolts is measured using an ultrasonic force gauge. ; S3. Calculate the target preload based on S1 and S2. With initial preload The first differential preload ; S4, Apply the differential preload from S3. The first compensation angle is calculated using the angle method. And implement corner compensation; After the first compensation angle of S5 and S4 is implemented, the preload force after compensation is measured. ; S6 With initial preload The second differential preload The corrected and compensated preload force is obtained by self-calibrating the ultrasonic force gauge to correct errors. ; S7, Calculate the actual preload force after compensation obtained from S6. and target preload The third differential preload And the second compensation angle is calculated again using the angle method. Preload compensation is performed, and the target preload will be achieved after compensation.

[0006] Preferably, the target torque of S1 The calculation formula is as follows: ; in, Preload for target, The torque coefficient, The diameter is the bolt diameter.

[0007] Preferably, the initial torque in S1 Set as target torque 55 ~65 .

[0008] Preferably, in S2, when the automatic torque wrench applies the initial torque, it adopts a uniform loading method. When the initial preload is measured using an ultrasonic force gauge, the bolt is measured multiple times and the average value is taken.

[0009] Preferably, the ultrasonic force measuring instrument in S2 includes single longitudinal wave measurement and dual longitudinal wave measurement, and the ultrasonic force measuring instrument probe in S2 includes a piezoelectric probe, an electromagnetic ultrasonic probe, and a temperature measurement probe.

[0010] Preferably, the first differential preload of S3 The calculation process is as follows: .

[0011] Preferably, the compensation angle of S4 The calculation process is as follows: ; in, The bolt pitch is... For bolt stiffness, The stiffness of the connected parts.

[0012] Preferably, the self-calibration process of S6 is as follows: S61. Confirm the material and geometric parameters of the bolt entered into the ultrasonic force measuring instrument; S62. Calculate the measured preload after compensation. With initial preload The second differential preload ,in According to the second differential preload and the first differential preload The relationship between the two determines whether self-correction should be performed; S63. If self-calibration is required, it shall be based on the first differential preload. Second differential preload The ratio is used to calculate a calibration coefficient, which is then input into the ultrasonic force meter to correct its measurement model. The calculation process is as follows: ; S64. After calibration, recalculate the previous data according to the new calibration coefficients, and measure the calibrated data using an ultrasonic force gauge. .

[0013] Preferably, the condition for determining whether to perform self-correction in S62 is the second differential preload. Differential preload The formula for determining whether they are the same is as follows: ; If the determination formula is not valid, the self-calibration process begins; if the determination formula is valid, the self-calibration process is not performed, and the accuracy has been achieved.

[0014] Preferably, the specific process of S7 is as follows: S71. Calculate the third differential preload. The specific process is as follows: ; S72, Calculate the second compensation angle The specific process is as follows: ; S73, According to the second compensation angle After performing secondary corner compensation, the target preload force can be achieved.

[0015] Therefore, the high-precision bolt tightening method with rotation compensation and self-correction functions described above has the following advantages compared with the prior art: 1. The dual strategy of this application method, which involves "first compensating for process errors, then calibrating the measuring tool, and finally performing precise compensation", can identify and correct systematic errors and measurement errors in the tightening process respectively. By introducing an angle compensation algorithm in the execution stage and achieving self-calibration based on ultrasonic force feedback in the measurement stage, it can gradually reduce the axial force error caused by friction coefficient fluctuations and measurement deviations, making the final preload infinitely close to the set target value. Through theoretical analysis and experimental verification, this method can improve the axial force dispersion of the traditional torque control method from about ±30% to a level better than ±3%, so as to meet the stringent requirements of key fields such as aerospace and high-end equipment. 2. This application reduces the dependence of the entire tightening method on the initial accuracy of the measuring tool. Even if the tool has a certain initial deviation, the system can perform online self-calibration based on ultrasonic force feedback, ensuring the stability and reliability of long-term operation and reducing the calibration cost of the measuring tool. 3. This application transforms the theoretical method into an implementable standardized industrial tightening process. This method significantly reduces the dependence on operator experience and ensures the consistency and high-precision repeatability of tightening results under different operators and different time conditions.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is an overall flowchart of a high-precision bolt tightening method with rotation compensation and self-correction functions according to the present invention. Detailed Implementation

[0018] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0019] Example like Figure 1 As shown, a high-precision bolt tightening method with rotation compensation and self-correction functions according to the present invention includes the following steps: S1. Based on the target preload of the bolt Calculate the target torque and initial torque ; Target torque The calculation formula is as follows: ; in, Preload for target, The torque coefficient, The diameter of the bolt; initial torque Set as target torque 55 ~65 ; S2, Input the initial torque of S1 via an automatic torque wrench. The connected parts are brought into contact, and the initial preload of the bolts is measured using an ultrasonic force gauge. ; When applying initial torque, the automatic torque wrench uses a uniform loading method to reduce dynamic torque error. When using an ultrasonic force gauge to measure the initial preload, multiple measurements are taken and the average value is calculated to reduce measurement errors caused by uneven surfaces or uneven contact. The measurement methods of ultrasonic force measuring instruments include single longitudinal wave measurement and dual longitudinal wave measurement. The measuring probes of ultrasonic force measuring instruments include piezoelectric probes, electromagnetic ultrasonic probes, and temperature measurement probes. S3. Calculate the target preload based on S1 and S2. With initial preload The first differential preload ; First differential preload The calculation process is as follows: ; S4, Apply the differential preload from S3. The first compensation angle is calculated using the angle method. And implement corner compensation; Compensation corner The calculation process is as follows: ; in, The bolt pitch is... For bolt stiffness, The stiffness of the connected parts is determined by consulting relevant design manuals or by finite element analysis, based on the material, thickness, and quantity of the connected parts, combined with the specifications and length of the bolts. After the first compensation angle of S5 and S4 is implemented, the preload force after compensation is measured. ; S6 With initial preload The second differential preload The corrected and compensated preload force is obtained by reducing errors through self-calibration of an ultrasonic force gauge. ; The self-calibration process is as follows: S61. Confirm the material and geometric parameters of the bolt entered into the ultrasonic force measuring instrument; S62. Calculate the measured preload after compensation. With initial preload The second differential preload ,in According to the second differential preload and the first differential preload The relationship between the two determines whether self-correction should be performed; The condition for determining whether to perform self-calibration is the second differential preload. Differential preload The formula for determining whether they are the same is as follows: ; If the determination formula is not valid, the self-calibration process is initiated; if the determination formula is valid, the self-calibration process is not initiated, and the accuracy has been achieved. S63. If self-calibration is required, it shall be based on the first differential preload. Second differential preload The ratio is used to calculate a calibration coefficient, which is then input into the ultrasonic force meter to correct its measurement model. The calculation process is as follows: ; S64. After calibration, recalculate the previous data according to the new calibration coefficients, and measure the calibrated data using an ultrasonic force gauge. .

[0020] S7, Calculate the actual preload force after compensation obtained from S6. and target preload The third differential preload The second compensation angle is calculated again using the angle method. The target preload can be achieved by making compensation; The specific process is as follows: S71. Calculate the third differential preload. The specific process is as follows: ; S72, Calculate the second compensation angle The specific process is as follows: ; S73, According to the second compensation angle After performing secondary corner compensation, the target preload force can be achieved.

[0021] In the specific implementation process, taking the assembly of the hub flange bolts of a wind turbine generator set as an example, the target preload of the bolt is known. 80kN, nominal bolt diameter The torque coefficient is 20mm, based on the design manual and experimental data. The bolt stiffness was determined to be 0.15 by consulting manuals and using finite element analysis. 250kN / mm, stiffness of the connected parts (hub and flange) 750kN / mm, bolt pitch It is 2.5mm.

[0022] 1. Calculate the target torque and the initial torque. Calculate the target torque and set the initial torque to 60% of the target torque (taking the midpoint of the range of 55% to 65%), resulting in a target torque of 240 N. m, initial torque is 144N m.

[0023] 2. Apply initial torque and measure initial preload. The operator sets the torque parameter of the electric tightening system (automatic torque wrench) to 144N. m, select the uniform loading mode, start the tool, and tighten the bolts until the system automatically reaches 144N. Stop at m, at which point the connected parts are aligned. The operator uses a dual longitudinal wave ultrasonic force gauge, placing the probe on the bolt head. To minimize measurement errors, multiple measurements are taken and the average value is automatically calculated. The ultrasonic force gauge, based on its built-in model, converts the average acoustic time variation into the initial preload. It is displayed as 65kN.

[0024] 3. Calculate the first differential preload and implement the first compensation angle. Calculations show that the first differential preload is 15 kN and the first compensation angle is 11.5 degrees. The system sends a command to the electric tightening tool to rotate precisely 11.5 degrees from its current angular position. .

[0025] 4. Measure the preload after compensation. After the first compensation angle was implemented, the ultrasonic force gauge was used again to measure (again, the average value of multiple points was taken). The instrument displayed the preload force after compensation. It is 78.7 kN.

[0026] 5. Self-calibrating ultrasonic force meter The second differential preload is calculated to be 13.7 kN. The system determines whether self-calibration is needed based on the formula. If so, the system automatically initiates the self-calibration process. The system calculates a calibration coefficient of 0.913, which is the ratio of the target value to the current measured value, used to correct systematic deviations in the measurement model. This calibration coefficient of 0.913 is automatically input into the measurement model of the ultrasonic force gauge to complete the calibration. After calibration, the system recalculates the previous data using the new calibration coefficient. The corrected, compensated preload is 71.85 kN.

[0027] 6. Calculate and implement the second compensation angle. Using the calibrated "true" value, the third differential preload is calculated to be 8.15 kN (if the third differential preload is negative, reverse rotation is required), and the second compensation angle is calculated to be 5.54 degrees. The electric tightening tool then rotates precisely 5.54 mm. That is, even if there is an error, it will still be within the target preload. Within an acceptable range of ±3%.

[0028] If the calculated third differential preload does not exceed the target preload. If the error range is within ±3%, then a second corner compensation is not required.

[0029] Therefore, the present invention adopts a high-precision bolt tightening method with rotation compensation and self-correction functions, which combines the rotation compensation method and the self-correction function of the measuring tool, effectively improving the tightening accuracy of the bolt, and is suitable for the accuracy requirements of key fields such as aerospace and high-end equipment.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high-precision bolt tightening method with corner compensation and self-correction functions, characterized by, The method comprises the following steps: S1, target pretightening force of the bolt calculating the target torque and the initial torque ; S2, input the initial torque calculated in S1 by automatic torque wrench Make the connected parts fit together and measure the initial pre-tightening force of the bolt by using ultrasonic force gauge ; S3, calculating the target pretension force based on S1 and S2 a first difference pretension force that differs from the initial pretension force a first difference pretension force that differs from the initial pretension force a first difference pretension force that differs from the initial pretension force S4. The first differential pre-tightening force calculated in S3 , a first compensation rotation angle is calculated using the rotation angle method and the rotation angle compensation is implemented; S5, measuring the pre-tightening force after compensation after the first corner compensation is implemented in S4 ; S6, the compensated pre-tightening force of S5 a second difference pre-tightening force a second difference pre-tightening force a second difference pre-tightening force a second difference pre-tightening force S7, calculating the corrected pre-tightening force obtained in S6 and the target pre-tightening force a third difference pre-tightening force of the difference and calculating the second compensation angle by the angle conversion method The pre-tightening force is compensated, and the target pre-tightening force is achieved after compensation.

2. The high-precision bolt tightening method with corner compensation and self-correction function according to claim 1, characterized in that: Target torque of S1 The calculation formula is as follows: ； wherein, is the target preload force, is the torque coefficient, is the diameter of the bolt.

3. The high-precision bolt tightening method with corner compensation and self-correction function according to claim 1, characterized in that: initial torque of s1 set to target torque of 55 of 65 .

4. The high-precision bolt tightening method with corner compensation and self-correction function according to claim 1, characterized in that: In S2, the automatic torque wrench adopts a uniform speed loading mode when applying the initial torque, and the ultrasonic force gauge is used to measure the initial pretightening force, and the bolt is measured multiple times and the average value is taken.

5. The high-precision bolt tightening method with corner compensation and self-correction function according to claim 1, characterized in that: The measurement mode of the ultrasonic force gauge in S2 includes single longitudinal wave measurement and double longitudinal wave measurement, and the measurement probe of the ultrasonic force gauge in S2 includes a piezoelectric probe, an electromagnetic ultrasonic probe and a temperature measurement probe.

6. The high-precision bolt tightening method with corner compensation and self-correction function according to claim 1, characterized in that: First differential pretension of S3 The calculation process is as follows: 。 7. The high-precision bolt tightening method with corner compensation and self-correction function according to claim 1, characterized in that: Compensation corner of S4 The calculation proceeds as follows: ； wherein is the bolt pitch, is the bolt stiffness, is the connected piece stiffness.

8. The high-precision bolt tightening method with corner compensation and self-correction function according to claim 1, characterized in that: The self-correction process of S6 is as follows: S61, confirming the material and geometric parameters of the bolt input in the ultrasonic force gauge; S62, calculating the measured compensation pre-tightening force a second difference pre-tightening force from the initial pre-tightening force , wherein determining whether to perform self-correction according to a relationship between the second difference pre-tightening force and the first difference pre-tightening force ​​ S63, if self-correction is needed, a calibration factor is calculated according to the ratio of the first differential pre-tightening force and the second differential pre-tightening force , and the calibration factor is input into the ultrasonic force gauge to correct its measurement model. The calculation formula of the calibration factor is as follows: ​ ； S64, after the measurement model correction is completed, the pre-tightening force after compensation is measured by the ultrasonic force gauge .

9. The high-precision bolt tightening method with corner compensation and self-correction function according to claim 8, characterized in that: The condition for determining whether to perform self-correction in S62 is the second difference in pre-tightening force whether the first difference in pre-tightening force is the same, and the determination formula is as follows: ； If the determination formula is not established, the self-correction process is entered, if the determination formula is established, the self-correction process is not performed, and the accuracy has reached the standard.

10. The high-precision bolt tightening method with corner compensation and self-correction function according to claim 1, characterized in that: The specific process of S7 is as follows: S71、calculating the third difference pre-tightening force The specific process is as follows: ； S72, calculate a second compensation corner The specific process is as follows: ； S73、According to the second compensation corner After the secondary corner compensation is performed, the target preload force can be achieved.

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