Method for restraining fluttering of thin-wall workpiece based on follow-up supporting device

Abstract

The invention discloses a method for inhibiting fluttering of a thin-wall workpiece based on a follow-up supporting device, which comprises the following steps of: installing the follow-up supporting device, establishing initial normal contact between a rolling wheel in the follow-up supporting device and the back surface of the thin-wall workpiece and applying pre-tightening force to finish initial calibration of a contact state between the follow-up supporting device and the thin-wall workpiece; based on the contact state, a force sensor and a displacement sensor in the rolling wheel are used for collecting normal contact force and displacement signals; the control unit calculates a modal participation coefficient and a dynamic correction function according to the real-time signal to form a time-varying model of equivalent stiffness and damping of the thin-wall part, and a stepping motor in the follow-up supporting device drives a gear-rack mechanism to finely adjust the position of a rolling wheel, so that self-adaptive adjustment of the supporting force is realized; data recording and feedback optimization; and finishing processing and outputting parameters. The device has the advantages of real-time sensing, self-adaptive adjustment, measurable parameters, compact structure and the like, and the machining precision and the surface quality of the thin-walled workpiece are remarkably improved.

Description

Technical Field

[0001] This invention relates to the fields of machining and vibration control technology, and in particular to a method for suppressing chatter in thin-walled workpieces based on a follow-up support device. Background Technology

[0002] Thin-walled parts, due to their light weight, high rigidity, complex structure, and ease of deformation, are widely used in aerospace, precision molds, automotive manufacturing, and high-end equipment. As the manufacturing industry moves towards higher precision and efficiency, thin-walled part milling has become a key machining process. However, in actual machining, thin-walled parts, due to their low structural rigidity, low damping, and complex boundary constraints, are highly susceptible to regenerative chatter under periodic cutting force excitation. Regenerative chatter leads to increased relative vibration between the tool and the workpiece, causing periodic fluctuations in the cutting thickness, resulting in ripples on the workpiece surface, dimensional deviations, severe tool wear, and even workpiece scrap.

[0003] Currently, methods for suppressing chatter in thin-walled parts mainly fall into the following categories: The first category is improving structural stiffness, which involves improving fixtures, adding support points, or using special clamping structures to enhance the overall workpiece stiffness. The second category is passive or semi-active vibration absorption, with common methods including embedding damping dampers in the tool holder or setting adjustable vibration reduction mechanisms. The third category is optimizing process parameters, which involves adjusting spindle speed, depth of cut, feed rate, or tool geometry to avoid unstable areas and thus reduce chatter risk. In recent years, some researchers have proposed introducing auxiliary support devices during thin-walled part machining, i.e., providing additional support to the workpiece through external mechanisms to improve local stiffness. These devices are typically installed on the back or free end of the workpiece, using contact force to counteract deformation caused by cutting forces. However, existing auxiliary supports are mostly static, fixed structures that cannot be dynamically adjusted according to changes in the milling cutter trajectory.

[0004] Therefore, how to design a follow-up support device and method that can sense the vibration state of the workpiece in real time during the processing and automatically adjust the support position and contact force has become a key technical problem to be solved in this field. Summary of the Invention

[0005] Technical Objective: To address the deficiencies in existing technologies, this invention discloses a method for suppressing chatter in thin-walled workpieces based on a follow-up support device. By organically combining a force sensor, a displacement sensor, a stepper motor, and a gear and rack transmission structure, and supplementing it with algorithmic control based on modal participation coefficients and dynamic correction functions, real-time synchronization and adaptive adjustment of the support and the workpiece are achieved. This effectively suppresses chatter during processing and improves the processing accuracy and surface quality of thin-walled parts.

[0006] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution.

[0007] A method for suppressing chatter in thin-walled workpieces based on a servo support device includes the following steps: S1. Device pre-tightening and initialization: Install the follower support device, make the rolling wheel in the follower support device establish initial normal contact with the back of the thin-walled workpiece and apply pre-tightening force to complete the initial calibration of the contact state between the follower support device and the thin-walled workpiece. S2. Real-time signal acquisition and contact monitoring: Based on the contact state, the force sensor and displacement sensor in the rolling wheel are used to collect the normal contact force and displacement signals. After signal amplification, filtering and digital processing, the signals are input to the control unit in the follow-up support device. S3. Real-time follow-up adjustment and dynamic correction: The control unit calculates the modal participation coefficient and dynamic correction function based on the real-time signal to form a time-varying model of the equivalent stiffness and damping of the thin-walled part. The position of the rolling wheel is finely adjusted by the stepper motor driving the gear-rack mechanism in the follow-up support device to achieve adaptive adjustment of the support force. S4. Data recording and feedback optimization: During the processing, the support parameters are dynamically adjusted according to the detected changes in vibration amplitude to keep the support reaction force in balance with the workpiece vibration, thereby suppressing regenerative chatter. S5. Processing completion and parameter output.

[0008] Preferably, the follow-up support device includes a rolling bearing, an upper fixed plate, a motor mounting plate, a gear, a stepper motor, a magnetic chuck, a three-axis connector, a rack, a lower fixed plate, a rolling wheel, a milling cutter, a force sensor, a displacement sensor, an encoder, and a control unit; The rolling wheel is clamped and fixed between the upper and lower fixed plates by rolling bearings. The motor mounting plate is fixed on the upper fixed plate, and a stepper motor is mounted on the motor mounting plate. The stepper motor is connected to a gear, and the gear meshes with a rack. The stepper motor converts the rotational motion of the motor into the linear feed motion of the rolling wheel by controlling the meshing transmission between the gear and the rack. The stepper motor is started and stopped by the control unit. The magnetic chuck and the rack are connected by a three-axis connector. By adjusting the three-axis connector, it is ensured that the rotation axis of the rolling wheel is parallel to the cutting direction of the milling cutter, and the normal direction of the rolling wheel is perpendicular to the surface of the thin-walled workpiece. The rolling wheel integrates a force sensor and a displacement sensor arranged in series to detect the normal contact force and displacement change signals between the rolling wheel and the thin-walled workpiece, respectively. A high-precision encoder is installed at the axial end of the stepper motor to detect the motor rotation angle information. The force sensor, displacement sensor, and encoder are all connected to the control unit. The control unit first controls the stepper motor to start, thereby bringing the rolling wheel closer to and in contact with the thin-walled workpiece, applying a preload force to the workpiece. After receiving the normal contact force feedback from the force sensor until the set preload range is reached, the control unit controls the stepper motor to stop. The control unit receives the rolling wheel displacement feedback from the displacement sensor and uses the initial normal force as a reference to complete the initial calibration of the contact state between the follow-up support device and the thin-walled workpiece.

[0009] Preferably, in S2, contact monitoring is performed by calculating a contact gate function. The calculation formulas include: , in, For real-time detection of normal force, To preset the contact threshold, This is the smoothing coefficient.

[0010] Preferably, a dynamic correction function The calculation formulas include: , in, Indicates the spatial attenuation coefficient. This represents the time response coefficient.

[0011] Preferably, the formula for calculating the time response coefficient includes: , in, is the time constant.

[0012] Preferably, the spatial attenuation coefficient is obtained by interpolating and fitting discrete data, and the calculation formula for each discrete data includes: , in, The position of the rolling wheel along the length of the workpiece The corresponding workpiece vibration amplitude, This represents the maximum amplitude without support. The minimum amplitude is found at all measuring points.

[0013] Preferably, the time-varying model of the equivalent stiffness and damping of the thin-walled component includes: , in, Let x(t) represent the modal mass of the thin-walled component, and let x(t) be the generalized displacement of the thin-walled component in a selected principal mode or equivalent single-degree-of-freedom direction. They are velocity and acceleration, respectively. This indicates the cutting force applied by the follower-supported milling cutter to the thin-walled workpiece. For the initial stiffness and damping of thin-walled components, The corrections introduced for the follow-up support device. It is a dynamic correction function. These are the corrected equivalent stiffness and equivalent damping parameters. For modal participation coefficients, The weights of the modal participation coefficients.

[0014] Preferably, the modal participation coefficient Based on the dominant mode shape function of the thin-walled workpiece under the corresponding clamping boundary conditions Obtained through calculation.

[0015] Preferably, in S4, the normal force is continuously recorded during the processing. Roller displacement Equivalent stiffness With damping The change curve is fed back to the control unit; the control unit extracts the support stiffness-amplitude response curve to evaluate the servo device's effect on suppressing chatter in thin-walled components; when a change in chatter frequency or an amplitude exceeding the limit is detected, the control system automatically adjusts modal participation and dynamically corrects relevant parameters, including the modal participation coefficient. weight With time response coefficient time constant Improve the correction function Sensitivity.

[0016] Preferably, The range of values ​​is , These are the minimum and maximum values, respectively. The determination satisfies the following condition: Under the maximum permissible compensation, the target contact force does not exceed the permissible upper limit. Furthermore, the normal fine-tuning displacement of the rolling wheel does not exceed the upper limit of the actuator's stroke. ;at the same time The determination satisfies the following condition: the contact gate function can still be maintained under minimum compensation. .

[0017] Beneficial effects: 1. Integration of device and algorithm: For the first time, the follow-up support device and dynamic adjustment algorithm are deeply integrated. By sensing the changes in normal contact force and displacement through sensors, the position of the rolling wheel is adjusted in real time to achieve follow-up adaptive vibration suppression. 2. This invention introduces a modal participation and dynamic correction mechanism: By using modal participation coefficients and dynamic correction functions, a real-time update model of the equivalent stiffness and damping of thin-walled components is established, which accurately reflects the vibration energy distribution of the support points under different modes, thereby achieving precise vibration suppression of thin-walled components. 3. Real-time contact determination and self-correction control of the present invention: The contact gate function in the form of Sigmoid function is used to represent the support contact state. When the contact force is weakened or the support is disengaged, the system automatically drives the stepper motor to fine-tune the position of the rolling wheel, restores stable contact, and realizes self-correction closed loop. 4. Measurable and adjustable structure: The device adopts a modular design and consists of a magnetic chuck, a stepper motor, a gear and rack mechanism, a force / displacement sensor, and a rolling wheel. It has a compact structure, adjustable parameters, and can be quickly adapted to different types of thin-walled parts. Attached Figure Description

[0018] Figure 1 This is a flowchart of a method for suppressing flutter in thin-walled components based on a follower support device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a follower support device according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a follower support device supporting a thin-walled workpiece in milling according to an embodiment of the present invention; Wherein: 201: rolling bearing, 202: upper fixed plate, 203: motor mounting plate, 204: gear, 205: stepper motor, 206: magnetic chuck, 207: three-axis connector, 208: rack, 209: lower fixed plate, 210: rolling wheel; 301: milling cutter, 302: thin-walled workpiece. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application. Example

[0020] As attached Figure 1 and attached Figure 2 As shown in this embodiment, a method for suppressing chatter in thin-walled workpieces based on a follow-up support device is applicable to various milling conditions of thin-walled parts with complex structures and low stiffness. This method consists of... Figure 2 , Figure 3The illustrated follow-up support device achieves its core function by dynamically correcting the workpiece's equivalent stiffness and damping using an algorithm model through real-time sensing of the workpiece's normal force and displacement, thereby realizing adaptive vibration suppression. The method includes the following steps: S1. Device pre-tightening and initialization: Install the follower support device, make the rolling wheel in the follower support device establish initial normal contact with the back of the thin-walled workpiece and apply pre-tightening force to complete the initial calibration of the contact state between the follower support device and the thin-walled workpiece. like Figure 2 As shown, the follow-up support device includes a rolling bearing 201, an upper fixed plate 202, a motor mounting plate 203, a gear 204, a stepper motor 205, a magnetic chuck 206, a three-axis connector 207, a rack 208, a lower fixed plate 209, a rolling wheel 210, a milling cutter 301, a force sensor, a displacement sensor, an encoder, and a control unit. The rolling wheel 210 is clamped and fixed between the upper fixed plate 202 and the lower fixed plate 209 by the rolling bearing 201. The lower fixed plate 209 supports the rolling wheel 210, ensuring the stability and flexibility of the support movement. The motor mounting plate 203 is fixed on the upper fixed plate 202 and is used to mount the stepper motor 205. In this embodiment, the motor mounting plate 203 is fixed on the upper fixed plate 202 by bolts. In other embodiments of the present invention, other fixing and mounting methods can also be used, which will not be described in detail here. The stepper motor 205 is connected to the gear 204, and the gear 204 meshes with the rack 208. The stepper motor 205 converts the rotational motion of the motor into the linear feed motion of the rolling wheel by controlling the meshing transmission between the gear 204 and the rack 208. The stepper motor completes the start and stop operation through the control unit. The magnetic chuck 206 and the rack 208 are connected by a three-axis connector 207. By adjusting the three-axis connector 207, it is ensured that the rotation axis of the roller 210 is parallel to the cutting direction of the milling cutter 301, and the normal direction of the roller is perpendicular to the surface of the thin-walled workpiece 302.

[0021] The entire follow-up support device adopts a modular structure design, which facilitates installation, adjustment, and replacement, and is suitable for thin-walled workpieces of different sizes and shapes. The follow-up support device is fixed to the machine tool worktable by a magnetic chuck 206. The magnetic chuck 206, as the basic mounting component of the follow-up support device, can firmly adhere to the machine tool worktable or the metal base surface of the fixture, providing stable support for the entire follow-up device. The rolling wheel is connected to the lower fixed plate through a rolling bearing, ensuring the smoothness and flexibility of the support movement. The follow-up support device of this invention has high transmission accuracy and fast response speed. Through the meshing transmission between the stepper motor 205 and the gear 204 and rack 208, the rotational motion of the motor is converted into the linear feed motion of the rolling wheel, enabling micron-level adjustment of the normal position of the rolling wheel.

[0022] In this embodiment, the surface of the rolling wheel is covered with a wear-resistant rubber layer to reduce the coefficient of friction when in contact with the workpiece and to protect the workpiece surface from being damaged.

[0023] In addition, the rolling roller integrates several sensors, including miniature force and displacement sensors arranged in series, to detect the normal contact force and displacement changes between the rolling roller and the thin-walled workpiece, respectively. A high-precision encoder is mounted on the axial end of the stepper motor 205 to provide real-time feedback of motor rotation angle information to the control unit. This achieves closed-loop position control. The control unit uses the equivalent rotation angle-displacement coefficient of the gear-rack mechanism. The motor rotation angle fed back by the encoder Converted to normal fine-tuning displacement on the rolling wheel drive side ,in The equivalent rotation angle-displacement conversion factor, taking into account the gear pitch circle radius, transmission ratio, and assembly errors, can be obtained through calibration. The zero point of the rotation angle at the initial calibration moment, i.e., the completion of pre-tightening, is defined as the initial calibration time. The force sensor, displacement sensor, and encoder are all connected to the control unit. The control unit first controls the stepper motor to start, causing the rolling wheel to approach and contact the thin-walled workpiece, applying a pre-tightening force. It receives the normal contact force from the force sensor until the set pre-tightening range is reached, at which point the control unit stops the stepper motor. The control unit receives the rolling wheel displacement from the displacement sensor and uses this, combined with the initial normal force, as a reference to complete the initial calibration of the contact state between the servo support device and the thin-walled workpiece. To avoid ambiguity in subsequent algorithms due to inconsistent sources of "displacement," in this embodiment, the normal displacement of the rolling wheel output by the displacement sensor is denoted as... and with The displacement input serves as the basis for subsequent contact monitoring and equivalent parameter updates; the encoder collects the motor rotation angle. It is only used for drive-side closed-loop position control and command execution quantity verification.

[0024] The installation steps for the follow-up support device include: First, the follow-up support device is firmly attached to the machine tool worktable using a magnetic chuck to complete the rapid positioning of the device.

[0025] Subsequently, the three-axis connector 207 is adjusted to ensure that the rotation axis of the roller 210 remains parallel to the cutting direction of the milling cutter 301, and that the normal direction of the roller is perpendicular to the surface of the thin-walled workpiece 302. That is, the relative angle between the upper and lower fixed plates is finely adjusted through the three-axis connector to keep the rotation axis of the roller parallel to the cutting direction of the milling cutter, and to ensure that the normal direction of the roller is consistent with the normal direction of the outer surface of the thin-walled workpiece.

[0026] After adjustment, as the thickness of the thin-walled workpiece gradually decreases during milling, a stepper motor can be started to drive the gear and rack to mesh. Through the gear transmission mechanism, the rolling wheel is slowly pushed along the normal direction, causing it to gradually contact the outer wall of the workpiece and generate an initial preload. The magnitude of this preload is detected in real time by a force sensor installed between the rolling wheel and the bearing. The control unit compares this preload with the target preload range, typically set between 5 and 15 N. In this embodiment, a value of approximately 10 N is used. If insufficient, the advance continues; if excessive, a reverse fine-tuning is performed, ensuring stable and controllable contact and synchronous movement of the tool and support roller on the thin-walled workpiece contact surface. During the preload advance and reverse fine-tuning process, the control unit utilizes encoder feedback... Implement closed-loop control to ensure that each fine-tuning... Repeatable and traceable.

[0027] During this process, the displacement sensor records the normal displacement of the rolling wheel. Force sensor records normal contact force Automatically calibrate the initial displacement Initial contact force and initial displacement error As the initial input parameters and subsequent control reference, the initial calibration of the contact state between the servo device and the workpiece is achieved. Specifically, the encoder feedbacks the motor rotation angle. and through Obtain the relative displacement on the drive side; at the moment of preload completion The initial displacement on the driving side is denoted as The initial displacement error is defined as This is used to characterize the deviation between the "driven displacement and the actual displacement" caused by assembly gaps or elastic deformation. After this step is completed, a reliable normal constraint boundary is formed between the servo support device and the thin-walled workpiece, providing a structural basis for subsequent dynamic compensation and chatter suppression.

[0028] S2. Real-time signal acquisition and contact monitoring: Based on the contact state, the force sensor and displacement sensor in the rolling wheel are used to collect the normal contact force and displacement signals. After signal amplification, filtering and digital processing, the signals are input to the control unit in the follow-up support device. Since the thickness of thin-walled parts gradually decreases during milling, force and displacement sensors continuously collect the normal force applied to the workpiece by the rolling wheel and the relative displacement signal of the workpiece after milling begins. The sampling period can be set to 2–5 ms to ensure real-time dynamic response. The control unit amplifies, filters, and digitizes the signal (A / D conversion) for algorithm control, i.e., the real-time follow-up adjustment and dynamic correction process in S3, used to determine the contact state between the support and the workpiece. The control unit first normalizes the collected signal, and then, to avoid the instability of traditional binary "contact / disengagement" determination, calculates the contact gate function. This embodiment uses an improved Sigmoid continuous smoothing function to determine in real time whether the thin-walled part contacts the servo device after the thickness of the thin-walled part changes, and a contact gate function. The calculation formulas include: , in, For real-time detection of normal force, To preset the contact threshold, This is the smoothing coefficient. This function allows the contact state to be represented as a continuous state. ,when When the value approaches 1, it indicates that the support is in a stable contact state; when it approaches 0, it indicates that the contact force is weakening, representing a possible detachment; at this time, a compensation command will be automatically triggered, driving the stepper motor to make fine adjustments along the normal direction to restore stable contact force. During the detection process, when it is determined... When a downward trend appears, it indicates that the normal contact force between the rolling roller and the thin-walled workpiece is decreasing, and the control unit immediately triggers the compensation logic. Under closed-loop control, the stepper motor fine-tunes the position of the rolling roller to restore the target contact force so that the rolling roller and the thin-walled workpiece remain in contact.

[0029] When the milling cutter 301 cuts the thin-walled workpiece 302, the rolling wheel of the follower device always maintains normal contact with the back of the workpiece. The rolling wheel rolls along the cutting direction on the workpiece surface, preventing frictional slippage and continuously sensing the minute deformation of the workpiece caused by the cutting force. A force sensor measures the contact force in real time, and a displacement sensor monitors the normal displacement, transmitting the signals to the control module for real-time calculation.

[0030] The control unit calculates the contact gate function based on sensor signals to determine the contact state between the device and the workpiece. When a weakening of the contact force or an increase in the distance between the rolling wheel and the workpiece is detected, the system automatically drives the stepper motor to rotate forward, and pushes the rolling wheel to make a fine adjustment along the normal direction through a gear-rack mechanism to restore the target contact force. Conversely, if an excessive contact force or a local increase in the stiffness of the workpiece surface is detected, the control module drives the motor to retract in the reverse direction to prevent over-support from causing workpiece indentation or sudden changes in structural stiffness.

[0031] During machining, as the milling cutter feed path changes, the follow-up support device can flexibly change its support direction and angle through the adjustment function of the three-axis connector 207, ensuring that the normal direction of the rolling wheel always aligns with the normal direction of the local surface of the workpiece. When the machining area changes or the workpiece structure is complex, the operator can preset the rolling wheel path parameters, and the system will synchronously adjust the support position according to the tool path to achieve follow-up support along the tool path.

[0032] S3. Real-time follow-up adjustment and dynamic correction: The control unit calculates the modal participation coefficient and dynamic correction function based on the real-time signal to form a time-varying model of the equivalent stiffness and damping of the thin-walled part. The position of the rolling wheel is finely adjusted by the stepper motor driving the gear-rack mechanism in the follow-up support device to achieve adaptive adjustment of the support force. During the cutting process, the workpiece vibrates under the action of periodic cutting forces. That is, the effect of the servo support device on the dynamic characteristics of the thin-walled workpiece is not uniformly distributed throughout the entire axial depth of cut, but rather locally concentrated near the support position. Under the periodic excitation of the cutting force, the thin-walled workpiece will exhibit significant dynamic deformation and vibration. To achieve adaptive control of the servo support device under different vibration states, this invention calculates the modal participation coefficient in real time in the control unit. With dynamic correction function It is used to describe the coupling degree and spatiotemporal variation law of the follower support point to the modal response of the workpiece.

[0033] Among them, modal participation coefficient This coefficient characterizes the coupling degree of the servo support point in the overall vibration modes of the workpiece. Its value ranges from [0,1] and can be determined based on the support point position z and the displacement distribution function of each vibration mode of the workpiece. This coefficient reflects the contribution ratio of different support positions to the overall vibration energy transfer: when the support point is in the peak displacement region of the vibration mode, A larger value indicates that the support effectively reduces vibration energy; however, when the support point is located near a mode node... A value close to zero indicates that the vibration damping effect of the support at that location is limited. By introducing this coefficient, the control system can automatically weight different modal responses according to the support location, thereby correcting the spatial distribution of the support effect.

[0034] Dynamic correction function It is used to describe the continuous variation of stiffness and damping of a servo support over time and space, and its general form is: , in, The spatial attenuation coefficient is used to reflect the influence of the offset of the support point from the center of the main vibration mode of the thin-walled component on the vibration suppression effect. When the rolling support point deviates from the maximum displacement area of ​​the vibration mode (i.e. the vibration belly), its contribution to the effective stiffness increment of the system will decrease according to a certain law. In other words, the closer the support point is to the node area (i.e. the place where the vibration amplitude is small), the weaker the control effect of the applied normal force on the overall modal response. The time response coefficient characterizes the dynamic response speed and hysteresis characteristics of a system (the entire system in contact with the workpiece) when subjected to vibration excitation. This coefficient reflects the response delay of the support system under short-term vibration fluctuations: the faster the response, the better. The closer to 1, the slower the response. It will decay over time.

[0035] To ensure that the dynamic correction parameters of the follow-up support device conform to the actual working conditions, this embodiment adjusts the spatial attenuation coefficient. and time response coefficient Experimental calibration was conducted.

[0036] Spatial attenuation coefficient This is used to reflect the changing pattern of vibration damping effect as the support point moves along the length of the workpiece. During calibration, multiple positions are selected along the length of the workpiece for the rolling wheel. The vibration amplitude of the workpiece was measured under the same spindle speed and feed conditions. By comparing the maximum amplitude when unsupported. With each point The calculation yields: , in The minimum amplitude is found at all measuring points. Subsequently, interpolation fitting is performed on the discrete data to obtain a continuous function form. Its value is between 0 and 1, representing the weight of the support point position on the attenuation of vibration energy.

[0037] Time response coefficient Used to characterize the response speed of a device when subjected to vibration disturbances. During calibration, a small external disturbance (such as a momentary impact) is applied under stable contact with the servo support, and the contact force is recorded by a force sensor. Curve showing the change over time. Based on the time constant required for the system to reach 63.2% of its steady-state response. It can be fitted to: , Wherein, time constant This reflects the combined hysteresis characteristics of system control and mechanical inertia. If the system response is slow, a second-order approximation model can be used for correction.

[0038] Finally, the calibration results are stored in the control unit to form the follow-up correction function: This function can correct the compensation amount of the support force in real time, enabling the device to dynamically adjust its vibration response to thin-walled components, thereby improving the stability and adaptability of flutter suppression.

[0039] Based on the support point position z and the rolling wheel displacement The system updates the equivalent stiffness of thin-walled workpieces in real time. With damping The calculation formula is: , in, For the initial stiffness and damping of thin-walled components, The correction amount introduced for the follow-up support device. These are the corrected equivalent stiffness and equivalent damping parameters. Let be the modal participation coefficient, and , used to characterize the coupling weight of the support point in the principal mode; The weights of the modal participation coefficients.

[0040] Modal participation coefficient Based on the dominant mode shape function of the thin-walled workpiece under the corresponding clamping boundary conditions Calculation yields: Mode shape function This can be obtained through finite element modal analysis at the support point location. At this point, the displacement amplitude of the vibration mode is normalized: ,make , where r is the modal order. When considering the combined effect of multiple modes, a weighted superposition method can be used: , ,in These are the weighting coefficients for the r-th mode. This means that the sum of all participating modal weights equals 1; R is the total number of modal orders.

[0041] It can be calculated in real time from sensor detection data and algorithm feedback: within the sliding time window, let Least squares fitting ,have to The data is then filtered and limited before being used for updating equivalent parameters. From the perspective of the dynamic characteristics of thin-walled workpieces, the dynamic equation of a thin-walled workpiece without a servo device is: , in, Indicates the modal quality of a thin-walled component. This represents the cutting force applied by the milling cutter to the thin-walled workpiece, where x(t) is the generalized displacement of the thin-walled workpiece in a selected principal mode or equivalent single-degree-of-freedom direction. These are velocity and acceleration, respectively. The corrected dynamic equations for the thin-walled component after installing the servo support device can be expressed as: , in, The equivalent cutting excitation after coupling with the servo support is the cutting force applied by the servo support lower milling cutter to the thin-walled part. It is used to characterize the equivalent effect of the cutting excitation in this modal direction after the servo support changes the boundary conditions. This model shows that the supporting effect of the servo device does not directly change the stiffness of the thin-walled part, but rather couples the additional stiffness and damping to the thin-walled part system through contact force, thereby changing its overall dynamic response characteristics.

[0042] Based on the above correction results, the control unit outputs drive commands. The stepper motor drives the gear-rack mechanism to slightly adjust the position of the rolling wheel along the normal direction, causing the support reaction force to change dynamically over time, thereby altering the equivalent boundary conditions of the workpiece. Force and displacement sensors monitor changes in normal force and displacement in real time, forming a closed-loop control. When the system detects an increase in the normal amplitude of the workpiece or a decrease in contact force, the algorithm automatically improves... The response weights are adjusted to moderately increase the preload of the follow-up support in order to restore stable contact; when the amplitude decreases, the system appropriately reduces the compensation amount to avoid over-support, thereby achieving an adaptive balance between the support force and the vibration response.

[0043] S4. Data recording and feedback optimization: During the processing, the support parameters are dynamically adjusted according to the detected changes in vibration amplitude to keep the support reaction force in balance with the workpiece vibration, thereby suppressing regenerative chatter. Normal force is continuously recorded during the processing. Roller displacement Equivalent stiffness With damping The control unit performs statistical analysis and fitting on these data to extract the support stiffness-amplitude response curve, which is used to evaluate the servo device's effect on suppressing flutter in thin-walled components. When a change in flutter frequency or an amplitude exceeding the limit is detected, the control system automatically adjusts modal participation and dynamically corrects relevant parameters, including the modal participation coefficient. weight With time response coefficient time constant ,in The weighting coefficients of the modal participation coefficient term, i.e., as modal participation coefficients. Adjustable weights for items, used to adjust The strength of the impact on the update of equivalent parameters The initial value is set to 1, and the amplitude can be adaptively updated and limited based on the vibration amplitude deviation, thereby making the correction function... The increased sensitivity optimizes the support response speed and enables adaptive parameter updates.

[0044] In this invention, As modal participation coefficient Adjustable weights for items, used to adjust The intensity of the impact on the update of equivalent parameters; The initial value is set to 1, and it can be adaptively updated and limited based on the vibration amplitude deviation. To avoid overcompensation or undercompensation, Limited to Inside, among which These are the minimum and maximum values, respectively. This can be obtained through testing and calibration before processing, such as determining it through testing and calibration based on the maximum / minimum fine-tuning displacement and force feedback stability range achievable by the actuator, as well as the closed-loop stability requirements of the system. The determination satisfies the following condition: Under the maximum permissible compensation, the target contact force does not exceed the permissible upper limit. Furthermore, the normal fine-tuning displacement of the rolling wheel does not exceed the upper limit of the actuator's stroke. ;at the same time The determination satisfies the following condition: the contact gate function can still be maintained under minimum compensation. .

[0045] Under the pre-tightened and stable contact condition, gradually increase Short-term trial cutting or external disturbances are performed, and the peak contact force and the peak fine-tuning displacement are recorded. When the peak contact force reaches the upper limit of the allowable range... Or fine-tune the peak displacement to reach the upper limit of the actuator's stroke. At that time, the corresponding Values Similarly, gradually reduce When the minimum value of the contact gate function is lower than the preset lower limit Or the contact force is lower than the lower limit of the contact force. At that time, the corresponding Values .

[0046] Meanwhile, this invention employs a sliding window filtering and delay compensation algorithm to process real-time signals, eliminating the effects of noise interference and measurement delay, and ensuring the smoothness and accuracy of the compensation action. Through continuous feedback and autonomous learning mechanisms, the system can automatically optimize parameter combinations according to different working conditions, keeping the support response within the optimal working range and achieving effective vibration suppression of the workpiece.

[0047] S5. Processing Completion and Parameter Output: After processing is completed, record the contact forces throughout the entire processing process. Displacement Equivalent stiffness With damping The optimal set of support parameters is generated based on the changing data and the characteristics of the flutter frequency. Where N is the target preload or target contact force setting value, in N, and K is the stiffness compensation parameter, in N / m, used for forming or limiting the amplitude. The upper limit of compensation, where C is the damping compensation parameter, in units of... Used to form or limit amplitude The compensation upper limit serves as an initial reference value for the next similar workpiece processing, enabling experience inheritance and autonomous parameter learning. This invention not only provides data accumulation for system operation but also provides a foundation for subsequent process optimization and device iteration, thereby realizing the intelligent and adaptive evolution of the follow-up support system.

[0048] This invention achieves innovation on both structural design and algorithm modules, providing a movable support device and an adaptively adjustable algorithm method. The combination of these two approaches can effectively suppress chatter during milling of thin-walled parts, improve machining accuracy and surface quality without altering the original machine tool structure, and has broad engineering application prospects.

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for suppressing chatter in thin-walled workpieces based on a follow-up support device, characterized in that: Includes the following steps: S1. Device pre-tightening and initialization: Install the follower support device, make the rolling wheel in the follower support device establish initial normal contact with the back of the thin-walled workpiece and apply pre-tightening force to complete the initial calibration of the contact state between the follower support device and the thin-walled workpiece. S2. Real-time signal acquisition and contact monitoring: Based on the contact state, the force sensor and displacement sensor in the rolling wheel are used to collect the normal contact force and displacement signals. After signal amplification, filtering and digital processing, the signals are input to the control unit in the follow-up support device. S3. Real-time follow-up adjustment and dynamic correction: The control unit calculates the modal participation coefficient and dynamic correction function based on the real-time signal to form a time-varying model of the equivalent stiffness and damping of the thin-walled part. The position of the rolling wheel is finely adjusted by the stepper motor driving the gear-rack mechanism in the follow-up support device to achieve adaptive adjustment of the support force. S4. Data recording and feedback optimization: During the processing, the support parameters are dynamically adjusted according to the detected changes in vibration amplitude to keep the support reaction force in balance with the workpiece vibration, thereby suppressing regenerative chatter. S5. Processing completion and parameter output.

2. The method for suppressing chatter in thin-walled workpieces based on a follow-up support device according to claim 1, characterized in that: The follow-up support device includes rolling bearings, upper fixed plate, motor mounting plate, gears, stepper motor, magnetic chuck, three-axis connector, rack, lower fixed plate, rolling wheel, milling cutter, force sensor, displacement sensor, encoder, and control unit; The rolling wheel is clamped and fixed between the upper and lower fixed plates by rolling bearings. The motor mounting plate is fixed on the upper fixed plate, and a stepper motor is mounted on the motor mounting plate. The stepper motor is connected to a gear, and the gear meshes with a rack. The stepper motor converts the rotational motion of the motor into the linear feed motion of the rolling wheel by controlling the meshing transmission between the gear and the rack. The stepper motor is started and stopped by the control unit. The magnetic chuck and the rack are connected by a three-axis connector. By adjusting the three-axis connector, it is ensured that the rotation axis of the rolling wheel is parallel to the cutting direction of the milling cutter, and the normal direction of the rolling wheel is perpendicular to the surface of the thin-walled workpiece. The rolling wheel integrates a force sensor and a displacement sensor arranged in series to detect the normal contact force and displacement change signals between the rolling wheel and the thin-walled workpiece, respectively. A high-precision encoder is set at the axial end of the stepper motor to detect the motor rotation angle information and realize closed-loop position control. The force sensor, displacement sensor and encoder are all connected to the control unit. The control unit first controls the stepper motor to start, which in turn makes the rolling wheel approach and contact the thin-walled workpiece, applying a preload force to the thin-walled workpiece. After receiving the normal contact force feedback from the force sensor until the set preload range is reached, the control unit controls the stepper motor to stop. The control unit receives the rolling wheel displacement feedback from the displacement sensor, and uses the initial normal force as a reference to complete the initial calibration of the contact state between the follow-up support device and the thin-walled workpiece.

3. The method for suppressing chatter in thin-walled workpieces based on a follower support device according to claim 1, characterized in that: In S2, contact monitoring is performed by calculating the contact gate function. Calculation formula include: ， in, For real-time detection of normal force, To preset the contact threshold, This is the smoothing coefficient.

4. The method for suppressing chatter in thin-walled workpieces based on a follow-up support device according to claim 1, characterized in that: Dynamic correction function Calculation formula include: ， in, Indicates the spatial attenuation coefficient. This represents the time response coefficient.

5. A method for suppressing chatter in thin-walled workpieces based on a follow-up support device according to claim 4, characterized in that: Formula for calculating time response coefficient include: ， in, is the time constant.

6. The method for suppressing chatter in thin-walled workpieces based on a follow-up support device according to claim 4, characterized in that: The spatial attenuation coefficient is obtained by interpolating and fitting discrete data. The calculation formula for each discrete data point includes: ， in, The position of the rolling wheel along the length of the workpiece The corresponding workpiece vibration amplitude, This represents the maximum amplitude without support. The minimum amplitude is found at all measuring points.

7. A method for suppressing chatter in thin-walled workpieces based on a follow-up support device according to claim 1, characterized in that: Time-varying models of equivalent stiffness and damping for thin-walled components include: ， in, Let x(t) represent the modal mass of the thin-walled component, and let x(t) be the generalized displacement of the thin-walled component in a selected principal mode or equivalent single-degree-of-freedom direction. They are velocity and acceleration, respectively. This indicates the cutting force applied by the follower-supported milling cutter to the thin-walled workpiece. For the initial stiffness and damping of thin-walled components, The corrections introduced for the follow-up support device. It is a dynamic correction function. These are the corrected equivalent stiffness and equivalent damping parameters. For modal participation coefficients, The weights of the modal participation coefficients.

8. A method for suppressing chatter in thin-walled workpieces based on a follow-up support device according to claim 1, characterized in that: Modal participation coefficient Based on the dominant mode shape function of the thin-walled workpiece under the corresponding clamping boundary conditions Obtained through calculation.

9. A method for suppressing chatter in thin-walled workpieces based on a follow-up support device according to claim 1, characterized in that: In S4, the normal force is continuously recorded during the processing. Roller displacement Equivalent stiffness With damping The change curve is fed back to the control unit; the control unit extracts the support stiffness-amplitude response curve to evaluate the servo device's effect on suppressing chatter in thin-walled components; when a change in chatter frequency or an amplitude exceeding the limit is detected, the control system automatically adjusts modal participation and dynamically corrects relevant parameters, including the modal participation coefficient. weight With time response coefficient time constant Improve the correction function Sensitivity.

10. A method for suppressing chatter in thin-walled workpieces based on a follower support device according to claim 9, characterized in that: The range of values ​​is , These are the minimum and maximum values, respectively. The determination satisfies the following condition: Under the maximum permissible compensation, the target contact force does not exceed the permissible upper limit. Furthermore, the normal fine-tuning displacement of the rolling wheel does not exceed the upper limit of the actuator's stroke. ;at the same time The determination satisfies the following condition: the contact gate function can still be maintained under minimum compensation. .

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