Threaded surface torque cycle power automatic control method

Abstract

The invention relates to the technical field of machine manufacturing, and discloses a threaded surface torque cycle power automatic control method, which comprises the following steps: step S101, obtaining a first oil stain thickness through a laser distance measuring sensor; step S102, obtaining a second oil stain thickness through a capacitive sensor; s103, calculating to obtain a third oil stain thickness; s104, the optimal clamping force is obtained through calculation; step S105, calculating to obtain the required torsion, and adjusting the current torsion to the required torsion through a PID control algorithm; and S106, the current clamping force and the current torsion are cooperatively controlled. According to the invention, the oil contamination thickness is accurately monitored in real time through fusion of the laser distance measuring sensor and the capacitive sensor, and dynamic and accurate adjustment of clamping force and torsion is realized according to an optimal clamping force calculation model of the oil contamination thickness, workpiece material characteristics and geometrical shape parameters in combination with a torsion self-adaptive control algorithm; therefore, the stability and reliability of the connection process are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical manufacturing, and more particularly to a method for automatically controlling thread surface torque cycles. Background Art

[0002] Threaded connections are widely used in machinery manufacturing, equipment installation, and industrial maintenance due to their ease of assembly and disassembly and reliable connections. However, the reliability of threaded connections depends heavily on precise torque control. Traditional manual tools, such as torque wrenches, suffer from low operating efficiency, significant human interference, and difficulty maintaining torque accuracy.

[0003] With the development of automation technology, electric and pneumatic torque tools have gradually become popular. Although they have improved work efficiency to a certain extent, they still have defects such as insufficient torque control accuracy and the inability to provide real-time feedback on torque changes under different working conditions. Most existing automated torque control systems use preset program control, which makes it difficult to adapt to diverse working conditions and threaded connection requirements of different specifications. For example, in the connection process of some high-strength bolts, due to the influence of material properties, thread wear and environmental factors, the preset torque parameters are often unable to accurately match the actual needs, which can easily lead to over-torque or under-torque. Over-torque may cause plastic deformation or even fracture of the bolt or nut, while under-torque may cause the connection to loosen, thereby affecting the normal operation and safety of the equipment.

[0004] Furthermore, existing torque control methods lack real-time monitoring and dynamic adjustment mechanisms, making them difficult to meet the high-precision requirements of threaded connections under complex working conditions. This is particularly true in critical areas such as high-precision mechanical assembly, aerospace equipment maintenance, and petrochemical pipeline connections, where the demands for torque control accuracy and reliability are extremely high. Consequently, the limitations of traditional methods are even more pronounced. Therefore, developing an automatic control method that can adapt to different working conditions, monitor in real time, and precisely control the number of torque cycles on the thread surface has become a pressing technical challenge. Summary of the Invention

[0005] The present invention provides a method for automatically controlling the torque cycle of a thread surface to solve the technical problems in the above-mentioned background technology.

[0006] The present invention provides a method for automatically controlling the torque cycle number of a thread surface, comprising the following steps:

[0007] Step S101, emitting laser pulses to the oil stain surface through a laser ranging sensor, recording the round trip time of the reflected light, and calculating the first oil stain thickness based on the time;

[0008] Step S102, indirectly measuring the second oil stain thickness by using a capacitive sensor in combination with the dielectric constant of the oil stain and the capacitance change caused by the thickness change;

[0009] Step S103, performing weighted summation on the first oil stain thickness and the second oil stain thickness to obtain a third oil stain thickness;

[0010] The weight coefficients corresponding to the first and second oil stain thicknesses are both custom parameters;

[0011] Step S104, calculating and obtaining the optimum clamping force according to the third oil stain thickness, the workpiece material characteristic parameters, and the workpiece contact surface geometric parameters;

[0012] The workpiece material characteristic parameters include: elastic modulus and yield strength;

[0013] The geometric parameters of the workpiece contact surface include: workpiece contact area and curvature radius;

[0014] Step S105, calculating the required torque according to the third oil stain thickness, the optimum clamping force, and the threaded connection parameters, and adjusting the current torque to the required torque through a PID control algorithm;

[0015] Threaded connection parameters include: thread diameter and friction coefficient;

[0016] Step S106: During the process of tightening the bolt, the current clamping force and the current torque are collaboratively controlled, and the laser ranging sensor and the capacitive sensor are regularly calibrated.

[0017] Furthermore, the first oil stain thickness is obtained by multiplying the propagation speed of the laser in the medium by the round-trip time of the reflected light and then dividing the result by 2.

[0018] Furthermore, the second oil stain thickness is obtained according to the capacitance value through a calibration curve, the calibration curve is obtained by least square fitting, and the capacitance value is obtained by multiplying the dielectric constant of the oil stain by the area of ​​the capacitive sensor plate and dividing the result by the plate spacing.

[0019] Furthermore, the optimum clamping force F final The calculation formula is as follows:

[0020] Where β represents the correction factor, k represents the empirical coefficient, E represents the elastic modulus, A represents the workpiece contact area, h represents the third oil thickness, and r represents the curvature radius;

[0021] The calculation formula of the correction factor β is as follows:

[0022] Where η represents the oil viscosity, η0 represents the baseline viscosity, T represents the current temperature, T0 and T1 represent the baseline temperature and reference temperature respectively.

[0023] Furthermore, the limit value of the optimal clamping force F maxThe calculation formula is as follows:

[0024] F max =σ0×A, where σ0 represents the yield strength and A represents the workpiece contact area.

[0025] Furthermore, the required torque T final The calculation formula is as follows:

[0026] Among them F final represents the optimum clamping force, d0 represents the thread diameter, μ eff represents the effective correction factor of friction, a represents the correction coefficient, and h represents the thickness of the third oil stain;

[0027] Friction effective correction factor μ eff The calculation formula is as follows:

[0028] μ eff =μ×e -b×h , where μ represents the friction coefficient and b represents the friction factor attenuation coefficient.

[0029] Furthermore, the calculation formula of the PID control algorithm is as follows:

[0030] Where ΔT(t) represents the difference between the current clamping force and the optimal clamping force, ΔT(τ) represents the difference between the current clamping force and the optimal clamping force at the τth integration moment, and K p Indicates the proportional control coefficient, K i Indicates the integral control coefficient, K d represents the differential control coefficient.

[0031] Furthermore, if the real-time monitoring shows that the oil stain thickness is reduced to a preset percentage of the original oil stain thickness, the current clamping force and the current torque are increased to the first target value and the second target value respectively at the same time; otherwise, the current clamping force and the current torque are reduced to the third target value and the fourth target value respectively at the same time, wherein the preset percentage, the first target value, the second target value, the third target value and the fourth target value are all custom parameters.

[0032] Furthermore, when the target tightening position is reached, the current clamping force and the current torque are adjusted to the optimum clamping force and the required torque respectively, wherein the target tightening position is a custom parameter.

[0033] Furthermore, a standard oil sample with known thickness was used to measure its capacitance value and laser reflection time, and the calibration curve was obtained using the least squares method to complete the calibration of the laser ranging sensor and the capacitive sensor.

[0034] The beneficial effects of the present invention are: 1. Precise monitoring and control: through the fusion of laser ranging sensors and capacitive sensors, the thickness of oil stains is accurately monitored in real time, and the optimal clamping force calculation model based on the thickness of oil stains, workpiece material properties and geometric shape parameters is combined with the torque adaptive control algorithm to achieve dynamic and precise adjustment of clamping force and torque, thereby ensuring the stability and reliability of the connection process; 2. Improved connection quality: Dynamically adjust the clamping force and torque according to the changes in oil stain thickness, effectively avoiding loose connections or over-tightening problems caused by oil stains. During the bolt tightening process, the coordinated changes in clamping force and torque ensure that the bolts are reliably tightened. Tight, the oil and dirt on the connection interface are squeezed out moderately, forming a good sealing and connection effect, and improving the connection quality; 3. Avoid damage to the workpiece: the clamping force always does not exceed the limit value corresponding to the yield strength of the workpiece material, preventing the workpiece from deformation or damage due to excessive clamping, avoiding over-torque or under-torque, protecting the bolts and nuts from damage, and extending the service life; 4. Intelligence and automation: The closed-loop control algorithm of the PID control strategy is adopted to ensure that the torque tracks the target value quickly and accurately, and ensure the accuracy of measurement and control; 5. Strong adaptability: It can adapt to different working conditions and threaded connection requirements to achieve precise clamping force and torque control. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flow chart of the thread surface torque cycle number power automatic control method of the present invention. DETAILED DESCRIPTION

[0036] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed solely to enable those skilled in the art to better understand and implement the subject matter described herein, and that the functions and arrangements of the elements discussed may be varied without departing from the scope of this specification. Various examples may omit, substitute, or add various processes or components as needed. In addition, features described with respect to some examples may also be combined in other examples.

[0037] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in one or more embodiments of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprising" 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 object being described changes, the relative positional relationship may also change accordingly.

[0038] like Figure 1 As shown, the thread surface torque cycle number power automatic control method includes the following steps:

[0039] Step S101, emitting laser pulses to the oil stain surface through a laser ranging sensor, recording the round trip time of the reflected light, and calculating the first oil stain thickness based on the time;

[0040] Step S102, indirectly measuring the second oil stain thickness by using a capacitive sensor in combination with the dielectric constant of the oil stain and the capacitance change caused by the thickness change;

[0041] Step S103, performing weighted summation on the first oil stain thickness and the second oil stain thickness to obtain a third oil stain thickness;

[0042] The weight coefficients corresponding to the first and second oil stain thicknesses are both custom parameters;

[0043] Step S104, calculating and obtaining the optimum clamping force according to the third oil stain thickness, the workpiece material characteristic parameters, and the workpiece contact surface geometric parameters;

[0044] The workpiece material characteristic parameters include: elastic modulus and yield strength;

[0045] The geometric parameters of the workpiece contact surface include: workpiece contact area and curvature radius;

[0046] Step S105, calculating the required torque according to the third oil stain thickness, the optimum clamping force, and the threaded connection parameters, and adjusting the current torque to the required torque through a PID control algorithm;

[0047] Threaded connection parameters include: thread diameter and friction coefficient;

[0048] Step S106: During the process of tightening the bolt, the current clamping force and the current torque are collaboratively controlled, and the laser ranging sensor and the capacitive sensor are regularly calibrated.

[0049] In one embodiment of the present invention, the first oil stain thickness is obtained by multiplying the propagation speed of the laser in the medium by the round-trip time of the reflected light and dividing the result by 2. For example, the propagation speed of the laser in the medium is set to 3×10 8 m / s.

[0050] In one embodiment of the present invention, the second oil stain thickness is obtained according to the capacitance value through a calibration curve, the calibration curve is obtained by least squares fitting, and the capacitance value is obtained by multiplying the dielectric constant of the oil stain by the area of ​​the capacitive sensor plate and dividing the result by the plate spacing.

[0051] It should be noted that the calibration curve is the mapping relationship between the capacitance value and the oil stain thickness. The dielectric constant of the oil stain reflects the polarization ability of the material in the electric field. The larger the value, the more charge is stored under the same voltage. For commonly used lubricating oils, cutting oils and other oil stains, their relative dielectric constants are usually between 2 and 3, which can be obtained by consulting the technical specification table provided by the oil manufacturer; in addition, the sum of the weight coefficients corresponding to the first oil stain thickness and the second oil stain thickness is 1. For example, the weight coefficients corresponding to the first oil stain thickness and the second oil stain thickness are set to 0.2 and 0.8, respectively. The two sensor measurement methods provided by the present invention can complement and verify each other, thereby ensuring the accuracy and reliability of the oil stain thickness measurement, and the measurement accuracy can reach 0.01mm.

[0052] In one embodiment of the present invention, the optimum clamping force F final The calculation formula is as follows:

[0053] Where β represents the correction factor, k represents the empirical coefficient, E represents the elastic modulus, A represents the workpiece contact area, h represents the third oil thickness, and r represents the curvature radius;

[0054] The calculation formula of the correction factor β is as follows:

[0055] Where η represents the oil viscosity, η0 represents the baseline viscosity, T represents the current temperature, T0 and T1 represent the baseline temperature and reference temperature respectively.

[0056] It should be noted that the viscosity of the oil can be obtained through the viscosity sensor. The base viscosity, base temperature and reference temperature are all custom parameters. The base viscosity can be expressed by the viscosity corresponding to 40°C or 25°C, the base temperature can be set to 40°C or 25°C, and the reference temperature can be set to 100°C or 80°C. They will not be elaborated here.

[0057] In one embodiment of the present invention, the limit value of the optimal clamping force F max The calculation formula is as follows:

[0058] F max =σ0×A, where σ0 represents the yield strength and A represents the workpiece contact area.

[0059] It should be noted that the elastic modulus of the workpiece material is expressed by the ratio of stress to strain, and the yield strength indicates the stress value corresponding to the beginning of permanent plastic deformation of the material. The optimal clamping force cannot exceed its limit value. Determining the limit value of the optimal clamping force can prevent the workpiece from being deformed or damaged due to over-clamping.

[0060] In one embodiment of the present invention, the required torque T final The calculation formula is as follows:

[0061] Among them F final represents the optimum clamping force, d0 represents the thread diameter, μeff represents the effective friction correction factor, a represents the correction coefficient, and h represents the third oil stain thickness;

[0062] The calculation formula of the effective friction correction factor μeff is as follows:

[0063] μ eff =μ×e -b×h , where μ represents the friction coefficient and b represents the friction factor attenuation coefficient.

[0064] It should be noted that the friction coefficient is expressed by the ratio of the tangential friction force to the normal normal pressure. It is an inherent property of the workpiece material and surface roughness and can be obtained through standard friction tests; the friction factor attenuation coefficient is used to reflect the exponential attenuation rate of the oil thickness on the friction coefficient; the correction factor is used to compensate for the additional influence of the oil layer on the required torque. When the oil film becomes thicker, it is necessary to overcome the additional torque caused by the shearing or discharge of the oil film; the friction factor attenuation coefficient and the correction coefficient can be obtained by fitting the required torque by the least squares method, or solved by the gradient descent algorithm, which will not be elaborated here.

[0065] In one embodiment of the present invention, the calculation formula of the PID control algorithm is as follows:

[0066] Where ΔT(t) represents the difference between the current clamping force and the optimal clamping force, ΔT(τ) represents the difference between the current clamping force and the optimal clamping force at the τth integration moment, and K p Indicates the proportional control coefficient, K i Indicates the integral control coefficient, K d represents the differential control coefficient.

[0067] It should be noted that the PID control algorithm can ensure that the torque is tracked to the target value quickly and accurately, and can control the response time to no more than 0.5s, and the torque control accuracy can reach within 2%.

[0068] In one embodiment of the present invention, as the bolt is screwed in, the oil stain thickness is monitored in real time and reduced to a preset percentage of the original oil stain thickness, then the current clamping force and the current torque are increased to the first target value and the second target value respectively, otherwise the current clamping force and the current torque are reduced to the third target value and the fourth target value respectively, wherein the preset percentage, the first target value, the second target value, the third target value and the fourth target value are all custom parameters, for example, the preset percentage is set to 50%, the first target value and the third target value are set to 120% and 80% of the optimal clamping force respectively, and the second target value and the fourth target value are set to 120% and 80% of the required torque respectively.

[0069] In one embodiment of the present invention, when the target tightening position is reached, the current clamping force and the current torque are adjusted to the optimal clamping force and the required torque respectively to ensure that the bolt is reliably tightened and the oil and dirt on the connection interface are appropriately squeezed out to form a good sealing and connection effect, wherein the target tightening position is a custom parameter.

[0070] In one embodiment of the present invention, a standard oil sample with known thickness is used to measure its capacitance value and laser reflection time, and a calibration curve is obtained by least squares fitting to complete the calibration of the laser ranging sensor and the capacitive sensor, thereby ensuring measurement accuracy.

[0071] It should be noted that a cross-compensation model for clamping force and torque can also be established. When the clamping force is adjusted due to changes in oil thickness, its impact on torque is taken into account, and the torque output is corrected through a compensation algorithm. Similarly, the clamping force is also appropriately adjusted when the torque changes to ensure the stability and accuracy of the coordinated work of the two and control the system's comprehensive error within 3%.

[0072] It should be noted that during the connection process, the system continuously monitors the actual values ​​of the clamping force and torque, and compares them with the set values ​​in real time. The self-learning function of the intelligent controller can continuously optimize the control parameters (proportional control coefficient, integral control coefficient and differential control coefficient) to adapt to different working conditions and threaded connection requirements. For example, when a deviation between the actual torque and the target torque is detected, the intelligent controller automatically adjusts the PID parameters to ensure the accuracy and stability of the torque control. At the same time, the system records the data of each connection process to provide a basis for subsequent process optimization and quality traceability.

[0073] It should be noted that the intervals and thresholds are set for ease of comparison. The threshold size depends on the amount of sample data and the cardinality set by those skilled in the art for each set of sample data, as long as it does not affect the proportional relationship between the parameter and the quantized value. Furthermore, the above formulas are all dimensionless numerical calculations. These formulas are derived from software simulations of the most recent real-world conditions using large amounts of data. The preset parameters in these formulas are set by those skilled in the art based on actual conditions.

[0074] The above describes the embodiments of this embodiment, but this embodiment is not limited to the above specific implementation methods. The above specific implementation methods are merely illustrative and not restrictive. Ordinary technicians in this field can also make many forms based on the inspiration of this embodiment, all of which are protected by this embodiment.

Claims

1. A method for automatically controlling the torque cycle of a thread surface, characterized in that: The following steps are involved: Step S101, emitting laser pulses to the oil stain surface through a laser ranging sensor, recording the round trip time of the reflected light, and calculating the first oil stain thickness based on the time; Step S102, indirectly measuring the second oil stain thickness by using a capacitive sensor in combination with the dielectric constant of the oil stain and the capacitance change caused by the thickness change; Step S103, performing weighted summation on the first oil stain thickness and the second oil stain thickness to obtain a third oil stain thickness; The weight coefficients corresponding to the first and second oil stain thicknesses are both custom parameters; Step S104, calculating and obtaining the optimum clamping force according to the third oil stain thickness, the workpiece material characteristic parameters, and the workpiece contact surface geometric parameters; The workpiece material characteristic parameters include: elastic modulus and yield strength; The geometric parameters of the workpiece contact surface include: workpiece contact area and curvature radius; Step S105, calculating the required torque according to the third oil stain thickness, the optimum clamping force, and the threaded connection parameters, and adjusting the current torque to the required torque through a PID control algorithm; Threaded connection parameters include: thread diameter and friction coefficient; Step S106: During the process of tightening the bolt, the current clamping force and the current torque are collaboratively controlled, and the laser ranging sensor and the capacitive sensor are regularly calibrated.

2. The thread surface torque cycle power automatic control method according to claim 1, characterized in that: The first oil stain thickness is obtained by multiplying the propagation speed of the laser in the medium by the round-trip time of the reflected light and dividing the result by 2.

3. The thread surface torque cycle power automatic control method according to claim 1, characterized in that: The second oil stain thickness is obtained through a calibration curve according to the capacitance value. The calibration curve is obtained by least square fitting. The capacitance value is obtained by multiplying the dielectric constant of the oil stain by the area of ​​the capacitive sensor plates and then dividing the result by the plate spacing.

4. The thread surface torque cycle automatic control method according to claim 1, characterized in that: Optimum clamping force F final The calculation formula is as follows: Where β represents the correction factor, k represents the empirical coefficient, E represents the elastic modulus, A represents the workpiece contact area, h represents the third oil thickness, and r represents the curvature radius; The calculation formula of the correction factor β is as follows: Where η represents the oil viscosity, η0 represents the baseline viscosity, T represents the current temperature, T0 and T1 represent the baseline temperature and reference temperature respectively.

5. The thread surface torque cycle automatic control method according to claim 1, characterized in that: Optimal clamping force limit F max The calculation formula is as follows: F max =σ0×A, where σ0 represents the yield strength and A represents the workpiece contact area.

6. The thread surface torque cycle automatic control method according to claim 1, characterized in that: Required torque T final The calculation formula is as follows: Among them F final represents the optimum clamping force, d0 represents the thread diameter, μ eff represents the effective correction factor of friction, a represents the correction coefficient, and h represents the thickness of the third oil stain; The calculation formula of the effective friction correction factor μeff is as follows: μeff=μ×e -b×h , where μ represents the friction coefficient and b represents the friction factor attenuation coefficient.

7. The thread surface torque cycle automatic control method according to claim 1, characterized in that: The calculation formula of the PID control algorithm is as follows: Where ΔT(t) represents the difference between the current clamping force and the optimal clamping force, ΔT(τ) represents the difference between the current clamping force and the optimal clamping force at the τth integration moment, and K p Indicates the proportional control coefficient, K i Indicates the integral control coefficient, K d represents the differential control coefficient.

8. The thread surface torque cycle automatic power control method according to claim 1, characterized in that: If the oil stain thickness is reduced to a preset percentage of the original oil stain thickness during real-time monitoring, the current clamping force and the current torque are increased to the first target value and the second target value respectively. Otherwise, the current clamping force and the current torque are reduced to the third target value and the fourth target value respectively. The preset percentage, the first target value, the second target value, the third target value and the fourth target value are all custom parameters.

9. The thread surface torque cycle automatic control method according to claim 1, characterized in that: When the target tightening position is reached, the current clamping force and current torque are adjusted to the optimal clamping force and required torque respectively, where the target tightening position is a custom parameter.

10. The thread surface torque cycle automatic control method according to claim 1, characterized in that: A standard oil sample with known thickness is used to measure its capacitance value and laser reflection time. The calibration curve is obtained by fitting with the least squares method to complete the calibration of the laser ranging sensor and the capacitive sensor.

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