Design and control method for closing-in amount of self-locking nut
Through the adaptive receptacle technology of self-locking nuts, the closing parameters are dynamically adjusted, and the problem of inconsistent self-locking moment caused by the difference in the wall thickness of the nut and the elastic modulus of the material in the prior art is solved, achieving a higher consistency effect.
Patent Information
- Application Number
- CN202411584528.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-02-28
AI Technical Summary
The existing self-locking nut closing technology cannot effectively consider the differences in nut wall thickness and material elastic modulus, resulting in poor consistency of self-locking torque.
Adaptive receptacle technology of self-locking nuts is adopted to dynamically adjust the closing parameters, and adaptively adjust the preset receptacle amount according to the mechanical characteristics of each nut to improve the consistency of the self-locking torque.
The consistency of the self-locking torque is significantly improved, and the impact of the difference in wall thickness and material elastic modulus on the consistency of the self-locking torque is reduced.
Smart Images
Figure CN119525379A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of mechanical connection, and relates to a self-adaptive closing technology for self-locking nuts. Background Art
[0002] 1. Self-locking nuts
[0003] Self-locking nuts are nuts with closing features, which refer to the plastic deformation characteristics of the threaded hole caused by radial multi-point extrusion. Due to the closing features, the self-locking nut can produce an interference fit with the bolt when in use, thereby increasing the friction between the internal and external threads and playing a role in preventing loosening.
[0004] Self-locking nuts can be divided into two-point closing, three-point closing and four-point closing according to the number of closing features. Figure 1 Actual photos of these three types of self-locking nuts are given respectively.
[0005] 2. Self-locking torque
[0006] Self-locking torque is an important performance indicator of self-locking nuts. The so-called self-locking torque refers to the torque required for relative rotation between the inner and outer threads when the self-locking nut and the bolt are tightened before the pre-tightening force is formed. In other words, the self-locking torque is the friction torque generated by the interference fit between the closing characteristics of the self-locking nut and the bolt. The self-locking torque is a key indicator that determines the anti-loosening effect of the self-locking nut.
[0007] 3. Sealing machine
[0008] The closing feature of the self-locking nut is produced by radially extruding the nut by the pressure head of the closing machine. The closing machine is mainly composed of a servo motor, a control panel, a pressure head, and a controller. During the closing process, the nut to be closed is placed at the center of the workbench, and the servo motor drives the pressure head to advance according to the closing amount set in the control panel. After the closing is completed, the servo motor drives the pressure head to retreat quickly, and the pressure head is away from the nut.
[0009] 4. Existing closing technology
[0010] There are some commonly used expressions about the closing technology of self-locking nuts, such as "closing amount", "preset closing amount", "actual closing amount", "residual closing amount", etc. Here we first clarify the definitions of each expression. In the present invention, the closing amount and the preset closing amount have the same meaning, which refers to the preset maximum deformation of the nut in the closing direction during the closing process. The closing amount is a key parameter that determines the self-locking torque. The larger the closing amount, the greater the self-locking torque, but the two are not in a linear relationship, and there is no accurate theoretical relationship formula.
[0011] The actual closing amount refers to the actual maximum deformation of the nut in the closing direction during the closing process; the residual closing amount refers to the final residual deformation of the nut in the closing direction after the closing is completed; in addition, the closing of self-locking nuts is completed by a closing machine, such as Figure 3 As shown, during the nut closing process, the nut to be closed is placed at the center of the workbench, and the servo motor drives the pressure head to complete displacement actions such as fast forward, working forward and fast reverse. The pressure sensor records the pressure when the pressure head squeezes the nut in real time, and the grating displacement sensor records the displacement of the pressure head in real time.
[0012] The current process of self-locking nut closing technology is as follows Figure 4 shown.
[0013] The first step is to determine the preset closing amount required for the current batch of nuts based on experience or experiments to ensure that the closing at the preset closing amount can make the self-locking torque of the nuts meet the requirements.
[0014] The second step is to complete the tool setting for a nut sample and find the edge position of the nut to determine the displacement of the pressure head during the process. The specific process is as follows: Figure 5 As shown in (a), the pressure head is controlled to fast-forward from the initial position (fast-forward in the present invention refers to movement at a relatively high speed, and the purpose of fast-forward is to reduce the closing technical time) to the waiting position for work, and the waiting position for work is close to the edge position of the nut; then the pressure head is controlled to advance from the waiting position for work (work advance in the present invention refers to movement at a relatively slow speed) to the edge position of the nut, and the method for judging the edge position of the nut is based on whether the pressure when the pressure head squeezes the nut exceeds a threshold value. Once the pressure exceeds the threshold value, the pressure head immediately stops advancing and judges the current position as the edge position of the nut; after completing the judgment of the edge position of the nut, the pressure head is controlled to fast-retract from the edge position of the nut (fast-retract in the present invention refers to movement at a relatively high speed) to the waiting position for work, and the tool setting process is completed.
[0015] The third step is to complete the tool setting process and start closing all the nuts in the current batch. This process is completed by automatic program control. Figure 5 (b) First, the pressure head is controlled to advance and extrude the nut from the waiting position, and the displacement of the advance is equal to the distance between the edge of the nut and the waiting position plus the preset closing amount.
[0016] The fourth step is to maintain the pressure for the preset time after the pressure head reaches the target position.
[0017] Step 5: After the pressure is maintained, the pressure head is controlled to quickly retreat to the waiting position. This completes the automatic closing of one nut, and this process can be repeated to complete the closing of all nuts in the current batch.
[0018] 5. Limitations of existing closing technology
[0019] In the existing closing technology, for the same batch of nuts, the working displacement of the pressure head is fixed. At this time, if the size of all nuts is exactly the same, then the actual closing amount of all nuts is also the same. However, the wall thickness of individual nuts in the same batch cannot be exactly the same. Due to the existence of processing errors, there are differences in the wall thickness of different nuts. In the closing process, if the difference in nut wall thickness is ignored and the nuts are closed with a fixed working displacement, the self-locking torque of the self-locking nuts in the same batch will be inconsistent.
[0020] In the existing closing technology, the edge position of the nut is determined by a nut sample, and the edge position of the nut will not change when processing subsequent nuts. If the wall thickness of the subsequent nut is smaller, the actual edge displacement of the current nut will change during the closing process, the actual closing amount of the nut will become smaller, and the residual closing amount will also become smaller, resulting in a decrease in the self-locking torque, such as Figure 6 If the wall thickness of the subsequent nut is larger, the actual edge displacement of the current nut will change during the closing process, the actual closing amount of the nut will increase, and the residual closing amount will also increase, resulting in an increase in the self-locking torque, such as Figure 6 Therefore, the self-locking nut closing technology should consider the influence of the nut wall thickness on the closing process, accurately determine the edge position of each nut, and appropriately adjust the closing process based on the influence of the nut wall thickness on the self-locking torque to improve the consistency of the self-locking torque of the self-locking nut. This is a key principle of the present invention.
[0021] In addition, due to the instability of the material itself, the elastic modulus of the individual nuts in the same batch cannot be exactly the same. The existing closing technology ignores the difference in the elastic modulus of the nuts and uses a fixed working displacement to close the nuts, which is another reason for the inconsistency of the self-locking torque of the self-locking nuts in the same batch.
[0022] like Figure 7 As shown, under the condition of the same actual closing amount, compared with the material with the original elastic modulus, if a material with a larger elastic modulus is used, the rigidity of the nut is greater, and the rebound amount in the closing process is smaller, that is, the residual closing amount is larger, and the rigidity and residual closing amount are larger. These two main factors lead to an increase in the self-locking torque. If a material with a smaller elastic modulus is used, the rigidity of the nut is smaller, and the rebound amount in the closing process is larger, that is, the residual closing amount is smaller, and the rigidity and residual closing amount are smaller. These two main factors lead to a decrease in the self-locking torque. Therefore, the closing technology of self-locking nuts should consider the influence of the elastic modulus of the nut material on the closing process, judge the size relationship between the elastic modulus of each nut material and the elastic modulus of the raw material, and based on the influence of the elastic modulus on the self-locking torque, appropriately adjust the closing process to improve the consistency of the self-locking torque of the self-locking nut. This is another key principle of the present invention. Summary of the invention
[0023] The technical problem solved by the present application is: to overcome the deficiencies of the prior art, to provide a method for designing and controlling the closing amount of a self-locking nut, based on the mechanical properties of each nut itself, with the self-locking torque consistency as the goal, to adaptively and dynamically adjust the closing parameters, and to change the traditional "static" closing parameters to "dynamic" closing parameters. The self-adaptive closing technology of self-locking nuts reduces the impact of the differences in wall thickness and elastic modulus of materials between different nuts on the consistency of the self-locking torque, and significantly improves the consistency of the self-locking torque. The problem of poor consistency of the self-locking torque due to unstable mechanical properties of the material and inconsistent wall thickness of the nut is solved.
[0024] The technical solutions provided by this application are as follows:
[0025] A self-locking nut closing amount design and control method, comprising:
[0026] S1: Determine the preset closing amount of the nuts in the current batch;
[0027] S2: Test closing of a nut sample in the current batch of nuts, and use this nut sample as a "reference nut" to obtain the nut edge position of the "reference nut" and the pressure curve of the pressure head extruding the "reference nut" during the closing process; according to the pressure curve of the pressure head extruding the "reference nut" during the closing process, obtain the pressure F when the "reference nut" is closed to the first preset proportion of the preset closing amount. 参照 ; All nuts except the “control nuts” in the current batch of nuts are “subsequent nuts”;
[0028] S3: Select a "subsequent nut", obtain the edge position of the "subsequent nut", and obtain the pressure F of the indenter pressing the "subsequent nut" when the "subsequent nut" is pressed by the indenter to the second preset ratio of the preset closing amount. 后续 ;
[0029] S4: The difference between the edge position of the "subsequent nut" and the edge position of the "control nut" is the wall thickness increment ΔB of the "subsequent nut" relative to the "control nut". According to the wall thickness increment ΔB of the "subsequent nut" relative to the "control nut", the pressure F of the indenter extruding the "subsequent nut" 后续 The pressure F when the "control nut" is closed to the first preset ratio of the preset closing amount 参照 , calculate the adjusted preset closing amount T 调 ' 整 , and then adjust the preset closing amount T 调 ' 整 Complete the remaining work process;
[0030] S5: Maintain pressure for a preset time. After pressure maintenance, the pressure head is controlled to quickly retreat to the position to be processed, and the automatic closing of a "subsequent nut" is completed.
[0031] S6: Repeat steps S3-S5 to complete the closing of the nuts of the current batch.
[0032] The adjusted preset closing amount T 调 ' 整 Calculated by the following formula:
[0033]
[0034] Where, T 预设 is the initial preset closing amount of the "subsequent nut", M is the closing points of the nut, and F is the closing amount of the nut. 参照 F is the pressure value of the pressure head extruding the nut when the "reference nut" is closed to the first preset proportion of the preset closing amount, 后续 It is the pressure value of the pressure head extruding the nut when the "subsequent nut" is closed to the second preset proportion of the preset closing amount; ΔB is the wall thickness increment of the "subsequent nut" relative to the "control nut"; B is the nominal wall thickness of the "subsequent nut".
[0035] The feature is that the first preset ratio is the same as the second preset ratio.
[0036] The characteristic is that the first preset ratio is 50%-70%.
[0037] The feature is that the second preset ratio is 50%-70%.
[0038] S3 includes: first controlling the pressure head to fast-forward from the initial position to the waiting position of the "subsequent nut"; the pressure head starts to advance from the waiting position and determines the edge position of the "subsequent nut", and after obtaining the edge position of the "subsequent nut", the pressure head returns to the waiting position; the pressure head advances from the waiting position to a second preset proportion of the preset closing amount, and at this moment, the pressure F of the pressure head squeezing the "subsequent nut" is obtained. 后续 .
[0039] In summary, this application at least includes the following beneficial technical effects:
[0040] In view of the problem of poor self-locking torque consistency caused by unstable mechanical properties of materials and inconsistent wall thickness of nuts, the present invention proposes an adaptive closing process for self-locking nuts. Based on the mechanical properties of each nut itself and with the self-locking torque consistency as the goal, the closing parameters are adaptively and dynamically adjusted, and the traditional "static" closing parameters are changed to "dynamic" closing parameters. The adaptive closing process for self-locking nuts reduces the influence of the differences in wall thickness and elastic modulus of materials between different nuts on the consistency of self-locking torque, and significantly improves the consistency of self-locking torque. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] Figure 1 This is a physical picture of the self-locking nut;
[0042] Figure 2 This is a physical picture of the closing machine;
[0043] Figure 3 This is a schematic diagram of the main working parts of the closing machine;
[0044] Figure 4 This is the current technical flow chart of self-locking nut closing;
[0045] Figure 5 Schematic diagram of the displacement of the pressure head in the self-locking nut closing technology, where (a) is the schematic diagram of the displacement of the pressure head during the tool setting process, and (b) is the schematic diagram of the displacement of the pressure head during the closing process;
[0046] Figure 6 This is a schematic diagram of the effect of nut wall thickness on the closing process;
[0047] Figure 7 is the stress-strain curve of different elastic moduli;
[0048] Figure 8 It is the main process node of adaptive closing technology;
[0049] Fig. 9 Schematic diagram of the pressure head displacement during the tool setting process of the self-locking nut adaptive closing technology. DETAILED DESCRIPTION
[0050] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.
[0051] The present application embodiment discloses a method for designing and controlling the closing amount of a self-locking nut. Figure 8 As shown, the technical principles include:
[0052] (I) The principle of adaptive closing technology
[0053] The size of the self-locking torque of the self-locking nut is closely related to the actual closing amount. In order to eliminate the influence of the nut wall thickness on the actual closing amount, the edge position of each nut should be judged through the "tool setting process" during the closing process, so as to calculate the change in the actual wall thickness of each nut, and adjust the preset closing amount of each nut accordingly, so as to improve the consistency of the self-locking torque of the self-locking nut. This is one of the principles of the adaptive closing technology proposed in the present invention.
[0054] The size of the self-locking torque of the self-locking nut depends on the extrusion force of the nut clamping the bolt, that is, the "clamping force". Under the same friction coefficient conditions, the greater the "clamping force", the greater the friction force of the thread interface, and the greater the self-locking torque. Therefore, the consistency of the self-locking torque of the self-locking nut depends on the consistency of the "clamping force". During the closing process, the greater the pressure of the ram squeezing the nut, the greater the degree of plastic deformation of the nut, and thus the greater the "clamping force". Therefore, the pressure of the ram squeezing the nut is positively correlated with the "clamping force". Under the same closing amount conditions, the different elastic moduli of the individual nuts will lead to obvious differences in the pressure of the ram squeezing the nut. Therefore, during the closing process, the size of the elastic modulus of the material can be judged by judging the pressure of the ram squeezing the nut, and the preset closing amount can be adjusted to adjust the "clamping force" and improve the consistency of the self-locking torque. This is another principle of the adaptive closing technology proposed in the present invention.
[0055] Based on the above two principles, the general process of the adaptive closing technology proposed by the present invention is as follows:
[0056] The first step is to complete the entire process of closing a nut. During the closing process, the edge position of the nut and the pressure curve of the pressure head squeezing the nut during the closing process are obtained, and this nut is used as the "reference nut";
[0057] In the second step, during the closing process of the "subsequent nut", the adjusted preset closing amount needs to be calculated based on the edge position of the "reference nut" and the pressure curve of the pressure head squeezing the nut. The "subsequent nut" completes the closing according to the adjusted preset closing amount. Specifically, the calculation formula for the adjusted preset closing amount of the "subsequent nut" is as follows:
[0058]
[0059] Where, T 调 ' 整 The preset closing amount after adjustment of the "subsequent nut", T 预设 is the initial preset closing amount of the "subsequent nut", M is the closing points of the nut, and F is the closing amount of the nut. 参照 is the pressure value of the pressure head pressing the nut when the "reference nut" is closed to a preset ratio of the preset closing amount (preferably, the preset ratio is 50%-70%), F 后续 is the pressure value of the pressure head squeezing the nut when the "subsequent nut" is closed to a preset proportion of the preset closing amount, ΔB is the incremental value of the nut wall thickness (i.e. the difference between the edge position coordinates of the "subsequent nut" and the edge position coordinates of the "control nut"), and B is the nominal wall thickness of the nut (half the difference between the nominal diameter of the outer cylindrical surface of the nut and the nominal diameter of the thread). It should be noted that formula (1) is a possible formula, and the calculation formulas corresponding to different nuts may be different, and need to be adjusted according to actual conditions.
[0060] (II) Process of Adaptive Seaming Technology
[0061] The first step is to determine the preset closing amount of the current batch of nuts based on experience or experiments to ensure that the closing at the preset closing amount can make the self-locking torque of the nuts meet the requirements.
[0062] The second step is to determine the preset closing amount of the current batch of nuts, and then try to close a nut sample, and use this nut as a "reference nut" to obtain the nut edge position of the "reference nut" and the pressure curve of the pressure head squeezing the nut during the closing process.
[0063] In the third step, the nuts other than the "control nuts" in the current batch of nuts are "subsequent nuts". Next, the "subsequent nuts" are closed. First, the pressure head is controlled to fast-forward from the initial position to the waiting position, and the adaptive closing function is started.
[0064] In the fourth step, the ram starts to advance from the waiting position and judges the edge position of the "subsequent nut". The difference between the edge position of the "subsequent nut" and the edge position of the "reference nut" is the wall thickness increment ΔB of the "subsequent nut" relative to the "reference nut". This process is tool setting, and each "subsequent nut" has a tool setting process. After completing the edge position judgment of the "subsequent nut" and the calculation of the nut wall thickness increment ΔB, the nut extrusion process begins, and the ram continues to advance to a preset proportion of the preset closing amount (for example, 50%-70%). According to the pressure F of the ram extruding the nut at this moment 后续 The pressure F when the "control nut" is closed to the preset ratio of the preset closing amount 参照 , use formula (1) to calculate the adjusted preset closing amount T 调 ' 整 Then, complete the remaining process according to the adjusted preset closing amount.
[0065] Step 5: After completing all the processes, maintain the pressure for the preset time.
[0066] Step 6. After the pressure is maintained, the pressure head is controlled to quickly retreat to the processing position, thus completing the automatic closing of a nut. This process can be repeated to complete the closing of all nuts in the current batch.
[0067] In the above adaptive closing process, it is necessary to complete the tool setting for each "subsequent nut" to find the edge position of the "subsequent nut". The specific process is as follows: Fig. 9 As shown, the pressure head is controlled to advance from the waiting position to the edge position of the "subsequent nut". The method for judging the edge position of the "subsequent nut" is to determine whether the pressure when the pressure head squeezes the "subsequent nut" exceeds a threshold value. Once the pressure exceeds the threshold value, the current position is judged as the edge position of the "subsequent nut".
[0068] The specific implementation method of the self-locking nut adaptive closing technology is as follows:
[0069] The first step is to determine the preset closing amount of the nuts in the current batch based on experience or experiments.
[0070] The second step is to conduct a trial closing on a nut sample and use this nut as a "reference nut" to obtain the nut edge position of the "reference nut" and the pressure curve of the pressure head squeezing the nut during the closing process.
[0071] The third step is to control the pressure head to fast-forward from the initial position to the waiting position and start the adaptive closing function.
[0072] The fourth step is to contact the nut, determine the edge of the nut, and complete the tool setting. The process of squeezing the nut begins, and the pressure head continues to move forward to a preset proportion of the preset closing amount (for example, 50%-70%), and the preset closing amount is adjusted according to the pressure value of the pressure head squeezing the nut at this moment to complete the remaining closing work.
[0073] Step 5: Maintain pressure for the preset time.
[0074] The sixth step is to control the pressure head to quickly retreat to the processing position, thus completing the automatic closing of a nut.
[0075] Step 7: Repeat the above process to complete the closing of all nuts in the current batch.
[0076] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.
[0077] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.
Claims
1. A self-locking nut closing amount design and control method, characterized in that: include: S1: Determine the preset closing amount of the nuts in the current batch; S2: Test the closing of a nut sample in the current batch of nuts, and use this nut sample as a "reference nut" to obtain the nut edge position of the "reference nut" and the pressure curve of the pressure head extruding the "reference nut" during the closing process; according to the pressure curve of the pressure head extruding the "reference nut" during the closing process, obtain the pressure F when the "reference nut" is closed to the first preset proportion of the preset closing amount. 参照 ; All nuts except the "control nuts" in the current batch of nuts are "subsequent nuts"; S3: Select a "subsequent nut", obtain the edge position of the "subsequent nut", and obtain the pressure F of the indenter when the "subsequent nut" is pressed by the indenter to the second preset ratio of the preset closing amount. 后续 ; S4: The difference between the edge position of the "subsequent nut" and the edge position of the "control nut" is the wall thickness increment ΔB of the "subsequent nut" relative to the "control nut". According to the wall thickness increment ΔB of the "subsequent nut" relative to the "control nut" and the pressure F of the indenter extruding the "subsequent nut", the wall thickness increment ΔB of the "subsequent nut" relative to the "control nut" is calculated. 后续 The pressure F when the "control nut" is closed to the first preset ratio of the preset closing amount 参照 , calculate the adjusted preset closing amount T 调 ' 整 , and then adjust the preset closing amount T 调 ' 整 Complete the remaining work process; S5: Maintain pressure for a preset time. After pressure maintenance, the pressure head is controlled to quickly retreat to the position to be processed, and the automatic closing of a "subsequent nut" is completed. S6: Repeat steps S3-S5 to complete the closing of the nuts of the current batch.
2. A method for designing and controlling the closing amount of a self-locking nut according to claim 1, characterized in that: The adjusted preset closing amount T 调 ' 整 Calculated by the following formula: Where, T 预设 is the initial preset closing amount of the "subsequent nut", M is the closing points of the nut, and F is the closing amount of the nut. 参照 F is the pressure value of the pressure head extruding the nut when the "reference nut" is closed to the first preset proportion of the preset closing amount, 后续 It is the pressure value of the pressure head extruding the nut when the "subsequent nut" is closed to the second preset proportion of the preset closing amount; ΔB is the wall thickness increment of the "subsequent nut" relative to the "control nut"; B is the nominal wall thickness of the "subsequent nut".
3. A method for designing and controlling the closing amount of a self-locking nut according to claim 1, characterized in that: The first preset ratio is the same as the second preset ratio.
4. A method for designing and controlling the closing amount of a self-locking nut according to claim 1, characterized in that: The first preset ratio is 50%-70%.
5. A method for designing and controlling the closing amount of a self-locking nut according to claim 1, characterized in that: The second preset ratio is 50%-70%.
6. A method for designing and controlling the closing amount of a self-locking nut according to claim 1, characterized in that: The S3 includes: First, the pressure head is controlled to fast-forward from the initial position to the waiting position of the "subsequent nut"; the pressure head starts to advance from the waiting position and determines the edge position of the "subsequent nut". After obtaining the edge position of the "subsequent nut", the pressure head returns to the waiting position; The pressure head moves from the waiting position to the second preset ratio of the preset closing amount. At this moment, the pressure F of the pressure head squeezing the "subsequent nut" is obtained. 后续 .
7. A method for designing and controlling the closing amount of a self-locking nut according to claim 6, characterized in that: The method for judging the edge position of the "subsequent nut" is based on whether the pressure when the pressure head squeezes the "subsequent nut" exceeds a threshold value. Once the pressure exceeds the threshold value, the current position is judged as the edge position of the "subsequent nut".
8. A method for designing and controlling the closing amount of a self-locking nut according to claim 2, characterized in that: The nominal wall thickness B of the "subsequent nut" is half of the difference between the nominal diameter of the outer cylindrical surface of the "subsequent nut" and the nominal diameter of the "subsequent nut".