Self-sensing and self-driven intelligent vibration reduction tool holder system and method for suppressing cutting vibration

Abstract

This invention provides a self-sensing, self-driven intelligent vibration-damping tool holder system and a method for suppressing vibrations during machining, relating to the field of vibration reduction technology in robotic machining. The intelligent vibration-damping tool holder system includes a rotating device for completing the cutting process, a driving device for reducing vibration, and a detection device for real-time vibration feedback. The rotating device is mounted on the machining spindle; the detection device is arranged circumferentially around the tool holder body; the driving device is fixed to the outer ring of the machining spindle; the detection device includes an acceleration sensor and an eddy current displacement sensor for real-time detection of vibrations in the tool holder body. This invention performs real-time analysis and detection of axial and radial vibrations of the tool holder during machining, actively suppressing vibrations caused by time-varying cutting forces during machining. Combined with control algorithms, it optimizes vibration suppression, improving workpiece machining efficiency and quality.

Description

Technical Field

[0001] This invention relates to the field of vibration reduction technology in robotic machining, and in particular to a self-sensing and self-driven intelligent vibration reduction tool holder system and a method for suppressing vibration during cutting. Background Technology

[0002] Machining is a subtractive manufacturing process that removes excess material from a workpiece surface using cutting tools to achieve the desired shape, size, and surface quality. The importance of machining lies in its high precision and efficiency, wide material adaptability, ability to machine complex shapes, and automation and intelligence. Machining can produce parts with high precision and high surface quality, handle almost all types of materials, and produce complex geometries, improving production efficiency and reducing labor costs. Robots and machine tools are the two most widely used tools in machining. However, during machining, factors such as unstable cutting forces, insufficient system stiffness, tool wear and imbalance, and resonance cause deformation and periodic vibrations in the system under cutting forces. This leads to decreased workpiece machining accuracy, reduced surface quality, shortened tool life, and increased wear and tear on machine tools and industrial robots. Therefore, a universal vibration reduction system and method are urgently needed to reduce vibrations during the cutting process.

[0003] Piezoelectric ceramics offer several advantages in active vibration suppression. Firstly, they can rapidly respond to vibrations during machining, effectively reducing their impact on machining accuracy and improving machining quality and efficiency. Secondly, piezoelectric ceramics are small in size, have a fast response speed, and low energy consumption, making them suitable for integration into machining tool holder systems for intelligent vibration control. Therefore, to address these issues, a self-sensing and self-driven intelligent vibration damping tool holder system is proposed, capable of meeting various complex machining conditions. This system uses a piezoelectric ceramic intelligent actuator to generate driving force that counteracts vibrations in the tool holder body in real time, improving machining stability and ensuring machining quality.

[0004] Chinese invention patent CN117773976B, authorized under the title "Piezoelectric Active Vibration Control System and Control Method for Milling Processing of Industrial Robots," specifically discloses a vibration-damping tool holder that utilizes a piezoelectric stack embedded inside the tool holder and connects the internal actuator and external analysis and control device via brushes. However, embedding the piezoelectric stack inside the tool holder increases the overall length of the tool holder, reduces its structural rigidity, and severely limits its applicability to various machining conditions. Secondly, brushes, being consumables, accumulate carbon over time, leading to decreased brush transmission efficiency and affecting the robot's vibration damping effect. Finally, embedding the piezoelectric stack into the tool holder introduces a phase correspondence problem in vibration suppression. As the tool holder rotates during cutting, the piezoelectric stack also rotates accordingly. The angular correspondence between the vibration generated by the tool and the piezoelectric stack inside the tool holder cannot be effectively resolved, severely impacting the vibration suppression effect.

[0005] For example, Chinese invention patent CN103825396B discloses an "active control device for electric spindle vibration," which specifically discloses a bearing assembly installed on the electric spindle and an adjustable positioning assembly for radial positioning of the bearing assembly. The device uses piezoelectric ceramic actuators arranged around the radial periphery of the electric spindle to adjust the position of the spindle center, thereby suppressing the vibration of the electric spindle. However, this device only suppresses radial vibration of the electric spindle. In actual machining processes, depending on different machining states and conditions, the vibration of the electric spindle can be multi-directional, including radial and axial vibrations. This device cannot suppress axial vibration, thus exhibiting significant limitations and a limited vibration suppression effect.

[0006] For example, Chinese invention patent CN107972185B discloses "a tool holder with vibration damping function," which specifically discloses that an inner hole is opened in the body of the tool holder to place a damping block and a collet, and a groove is opened on the inner surface to provide a vibration damping device, which includes a collar and an elastic body. This device as a whole is a passive vibration damping device, which dissipates vibration energy through damping devices. This passive vibration damping device has a slow response speed, poor adaptability, high system complexity, and limited vibration suppression effect. In some complex and changing machining environments, it may lose its vibration suppression capability. Summary of the Invention

[0007] Purpose of the Invention: The purpose of this invention is to solve the vibration suppression problem in existing cutting processes and overcome the defects in existing vibration reduction technologies. It proposes a self-sensing, self-driven intelligent vibration-damping tool holder system, and further proposes a cutting vibration suppression method implemented in conjunction with the aforementioned intelligent vibration-damping tool holder system. This method performs real-time analysis and detection of the axial and radial vibrations of the tool holder during processing, thereby effectively solving the aforementioned problems in the existing technology.

[0008] This invention proposes a self-sensing, self-driven intelligent vibration-damping tool holder system. This system comprises three components: a rotating device for completing the cutting process, a driving device for reducing vibration, and a detection device for real-time vibration feedback. The rotating device is mounted on the machining spindle; the detection device is arranged circumferentially around the tool holder body; and the driving device is fixed to the outer ring of the machining spindle.

[0009] The drive unit includes radial piezoelectric ceramic actuators distributed inside the bottom sleeve, axial piezoelectric ceramic actuators distributed inside the bearing housing, and a fixing layer connected to the outer ring of the spindle.

[0010] The detection device is installed inside the drive unit and includes an acceleration sensor and an eddy current displacement sensor to analyze and detect the radial and axial vibrations of the tool holder body in real time.

[0011] The rotating device includes a tool holder body directly connected to the spindle, a bearing positioning device, and rolling bearings.

[0012] In a further embodiment, the detection device includes at least two eddy current displacement sensors mounted on the lower part of the radial piezoelectric ceramic actuator. The eddy current displacement sensors themselves are threaded and fixed through the threaded holes at the bottom end of the base sleeve to ensure stability. The vibration displacement of the tool holder body is directly detected by the probe of the eddy current displacement sensor, which serves as a direct evaluation of the control voltage of the radial piezoelectric ceramic actuator, enabling it to generate a corresponding driving force to suppress the radial vibration generated by the tool holder body.

[0013] In a further embodiment, the detection device includes at least one acceleration sensor mounted on the bottom of the lower bearing housing. The acceleration sensor needs to be mounted on the same axial plane as the axial piezoelectric ceramic actuator and be able to directly detect vibration signals in multiple directions and convert the corresponding vibration signals into analog voltage outputs to control the driving force of the axial piezoelectric ceramic actuator and suppress the axial vibration of the tool holder body.

[0014] The rotating device mainly includes a tool holder body directly connected to the spindle, a bearing positioning device, and a rolling bearing; the tool holder body includes a snap ring cap, a spring collet, and a cutting tool, wherein the snap ring cap is connected to the end of the tool holder body by threads and clamps the cutting tool by squeezing the spring collet.

[0015] In a further embodiment, the inner ring of the rolling bearing in the rotating device is connected to the bearing positioning device by an interference fit. The rolling element of the rolling bearing serves as the intermediate transmission point for the vibration of the tool holder body, transmitting the force on the tool holder body to the bearing housing. At the same time, the bearing positioning device is provided with a positioning ring and a positioning hole. The positioning ring ensures the precise axial positioning between the bearing positioning device and the inner ring of the rolling bearing, and the positioning hole is used to determine the axial position between the bearing positioning device and the tool holder body. The two are fixedly connected by bolts.

[0016] In a further embodiment, the driving device includes at least four radial piezoelectric ceramic actuators, which are mounted and supported by a base sleeve. They are evenly distributed on the radial plane of the piezoelectric vibration damping tool holder at equal intervals, forming a 90° angle with each other. The angle between them can be adjusted according to the specific actual situation, so that when the tool holder body generates radial vibration in any direction, the radial piezoelectric ceramic actuators can cooperate with each other to generate a corresponding driving force to cancel out its vibration displacement.

[0017] In a further embodiment, the drive unit has at least four axial piezoelectric ceramic actuators inside the upper and lower bearing housings, all located on the central axial plane of the tool holder body and arranged symmetrically in pairs. Depending on the applied control voltage, these actuators can suppress axial vibrations generated in the tool holder body during cutting. The self-sensing, self-driven intelligent vibration damping tool holder system can simultaneously suppress radial and axial vibrations of the tool holder body. This characteristic allows it to be applied to vibration suppression in various cutting processes, including milling and drilling.

[0018] In a further embodiment, all piezoelectric ceramic actuators in the drive device are fitted with a piezoelectric sheath. The piezoelectric sheath and the piezoelectric ceramic actuator are tightly bonded together with epoxy resin. Its function is not only to transmit the driving force of the piezoelectric ceramic actuator through the piezoelectric sheath, but also to ensure that the piezoelectric ceramic actuator is not affected by the shearing force that may be generated by the tool holder body during the cutting process. The piezoelectric sheath and the bottom sleeve plane are in frictional rather than fixed contact, and there will be relative sliding between the two when the piezoelectric ceramic actuator outputs driving force. Threaded holes are opened on the circumference of the bottom sleeve, and the preload bolts apply a certain preload force to the piezoelectric ceramic actuator through the threaded holes.

[0019] In a further embodiment, the drive device also includes a fixing layer connected to the outer ring of the machining spindle. The fixing layer is in close contact with the bottom sleeve and the two are connected by bolts to keep it fixed. The fixing layer serves as the load-bearing carrier of the entire drive device, and its upper end is fixed to the machining spindle by bolts. The fixing layer can be customized according to different spindle types, so that the self-sensing and self-driving intelligent vibration damping tool holder system is not only suitable for robot cutting processing, but also for machine tool cutting processing. This further enhances the versatility and convenience of the piezoelectric vibration damping tool holder system.

[0020] In a further embodiment, the rolling bearing is a deep groove ball bearing, and the inner and outer rings of the bearing are connected by an interference fit and a contact device to ensure the stability of vibration transmission during the cutting process; in addition, the present invention can be fitted with the corresponding bearing type according to the specific processing conditions and load requirements.

[0021] Furthermore, the present invention also proposes the above-mentioned method for suppressing vibration during cutting.

[0022] If it is in the milling process, the vibration of the tool holder body in the radial plane is detected in real time by the eddy current displacement sensor. The self-sensing and self-driving intelligent vibration reduction tool holder system includes at least two eddy current displacement sensors. The current vibration displacement is determined by detecting the output of the analog voltage to determine whether the current vibration displacement is closer to or farther from the sensor.

[0023] If it is in the drilling process, the vibration of the tool holder body in the axial plane is detected in real time by an accelerometer. The self-sensing and self-driving intelligent vibration reduction tool holder system includes at least one accelerometer, which determines the specific direction of the current vibration displacement by detecting the output of the analog voltage.

[0024] The vibration signals from the eddy current displacement sensor and / or acceleration sensor are transmitted to the controller, which uses a fuzzy PID control algorithm to tune the collected vibration signals into a control voltage before outputting them.

[0025] In a further embodiment, the vibration signal of the corresponding sensor is transmitted to the controller. The controller adjusts the output of the control voltage in real time according to the control algorithm set therein. When the fuzzy PID control algorithm is used to adjust the collected vibration signal, unlike the traditional PID control strategy, it can dynamically change the PID controller parameters according to the tracking error signal, thereby achieving a larger vibration control range and a better vibration control effect.

[0026] The sensor collects vibration signals as v a Compare with the desired value r set in the controller; use the deviation e (e = r - v) a (where r is the expected value of 0) and the rate of change of deviation e c As input to the fuzzy self-tuning PID control algorithm, to satisfy e and e at different times. c To meet the requirements for PID parameter self-tuning, a two-input, three-output fuzzy controller is established. Based on professional knowledge and control experience, fuzzy control rules are developed. The fuzzy self-tuning PID controller determines the three parameters K of the PID controller. p K I K D with e and e c The fuzzy relationship between them is determined by continuously detecting e and e during operation. cBased on the principle of fuzzy control, three parameters are adjusted online to meet different e and e c Different requirements for control parameters enable the controlled object to possess good dynamic and static characteristics. The input quantities are e and e0. c The output consists of three correction values ​​ΔK for the PID controller parameters. p ΔK I ΔK D .

[0027]

[0028] in , , For speed correction values, their values ​​will decrease as the number of corrections increases. Alternatively, they can be set as constants. The control parameters in the next step of the controller can be composed of a weighted sum of the current controller parameters and the controller parameter increments derived from fuzzy inference. This represents the proportional gain at time k. This represents the integral gain at time k. This represents the differential gain at time k; k-1 represents the gain at the previous time. Finally, the PID controller outputs the final control voltage. :

[0029]

[0030] In the formula, This represents the error at the current moment, that is, the difference between the set value and the theoretical value.

[0031] Discretizing the above equation is necessary because sensor signals in digital control systems typically need to be discretized for use in the controller.

[0032]

[0033] In the formula, This represents the difference between the set value and the theoretical value after discretization.

[0034] The control voltage is transmitted to the power amplifier via the controller's digital-to-analog converter. The power amplifier amplifies the analog voltage by 15 times and transmits it to the corresponding piezoelectric ceramic actuator. The piezoelectric ceramic has an inverse piezoelectric effect, which generates a corresponding driving force according to the polarization direction and the applied electric field, thereby suppressing the vibration of the tool holder body in the current direction. Alternatively, when the axial and radial vibrations are relatively large due to the influence of machining parameters during the cutting process, all sensors and piezoelectric ceramic actuators can be used simultaneously.

[0035] Beneficial Effects: This invention proposes a self-sensing, self-driven intelligent vibration damping tool holder system and a method for suppressing vibrations during cutting. By symmetrically distributing at least eight piezoelectric ceramic actuators in the radial and axial planes of the base sleeve and bearing housing, it can actively suppress vibrations caused by time-varying cutting forces during cutting. It can suppress not only the axial vibration of the tool holder body but also the radial vibration. Compared with other vibration damping tool holders, this invention is highly integrated and modular, and the corresponding structural dimensions can be modified for different tool holders and machining spindle models. It has the advantages of marketability and mass production. Furthermore, it can be combined with different control algorithms to achieve the best vibration suppression effect, ultimately improving the machining efficiency and quality of the workpiece. Attached Figure Description

[0036] Figure 1 This is a front sectional view of the self-sensing and self-driving intelligent vibration damping tool holder system in the embodiment.

[0037] Figure 2 This is a schematic diagram of the self-sensing and self-driving intelligent vibration damping tool holder system and its installation on the spindle in the embodiment.

[0038] Figure 3 This is an isometric view of the self-sensing and self-driving intelligent vibration damping tool holder system in the embodiment.

[0039] Figure 4 This is a schematic diagram of the self-sensing and self-driving intelligent vibration damping tool holder system installed on the machine tool spindle in the embodiment.

[0040] Figure 5 This is a schematic diagram of the self-sensing and self-driving intelligent vibration damping tool holder system installed on the robot spindle in the embodiment.

[0041] The attached figures are labeled as follows: 1. Tool holder body; 2. Fixing layer; 3. Piezoelectric protective layer; 4. Preload bolt; 5. Base sleeve; 6. Eddy current displacement sensor; 7. Spring collet; 8. Snap ring cap; 9. Cutting tool; 10. Accelerometer; 11. Lower bearing housing; 12. Radial piezoelectric ceramic actuator; 13. Upper bearing housing; 14. Axial piezoelectric ceramic actuator; 15. Rolling bearing; 16. Bearing positioning device; 17. Robot spindle; 18. Wire; 19. Power amplifier; 20. Controller; 21. Machine tool spindle; 22. Self-sensing and self-driving intelligent vibration damping tool holder system. Detailed Implementation

[0042] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0043] Figure 1 The image shown is a front cross-sectional view of the self-sensing and self-driving intelligent vibration damping tool holder system 22 in this embodiment. Figure 3 The image shown is its orthographic isometric projection. (From...) Figure 1 and Figure 3 It can be seen that the intelligent vibration damping tool holder system includes a tool holder body 1, a fixing layer 2, a piezoelectric protective layer 3, a preload bolt 4, a bottom sleeve 5, an eddy current displacement sensor 6, a spring collet 7, a snap ring cap 8, a cutting tool 9, an acceleration sensor 10, a lower bearing housing 11, a radial piezoelectric ceramic actuator 12, an upper bearing housing 13, an axial piezoelectric ceramic actuator 14, a rolling bearing 15, and a bearing positioning device 16.

[0044] To reduce the overall size and weight of the tool holder and lighten the load on the machining spindle, the self-sensing and self-driving intelligent tool holder system employs a unique design. The dimensions and shapes of the main components and devices are optimized, resulting in a dart-shaped appearance for the self-sensing and self-driving intelligent tool holder system. This minimizes the size and contact area of ​​the fixing layer 2 and the bottom sleeve 5 connected to the spindle, thus making it lightweight.

[0045] In this embodiment, the self-sensing and self-driving intelligent tool holder system includes a rotating device installed on the machining spindle and a driving device fixed to the outer ring of the spindle. The driving device also includes a device for measuring and analyzing vibration signals. The radial piezoelectric ceramic actuator 12 is installed inside the bottom sleeve 5 and transmits driving force through contact between the piezoelectric protective layer 3 and the upper bearing housing 13. The axial piezoelectric ceramic actuator 14 is installed inside the upper bearing housing 13 and the lower bearing housing 11 and is fixed between the pre-tightening bolt 4, the fixing layer 2, and the bottom sleeve 5. The fixing layer 2 serves as the support carrier for the entire driving device and is fixed to the robot spindle 17 through bolt connections to ensure that the driving device will not loosen during the cutting process and thus affect the vibration suppression effect.

[0046] In this embodiment, the measurement and analysis device includes an acceleration sensor 10 and an eddy current displacement sensor 6. The acceleration sensor 10 can be directly attached to the bottom of the lower bearing housing 11 and installed on the same axial plane as the axial piezoelectric ceramic actuator 14, thereby avoiding complex measurement-drive coordinate transformation and enhancing the convenience and accuracy of measurement. The eddy current displacement sensor 6 achieves a threaded connection with the bottom sleeve 5 through its own threads, and its installation position is as close as possible to the axial piezoelectric ceramic actuator 14, making it closer to the vibration source position to ensure the accuracy of vibration signal measurement.

[0047] In this embodiment, the acceleration sensor 10 and the eddy current displacement sensor 6 are both integrated into the self-sensing and self-driving intelligent vibration damping tool holder system 22, which integrates vibration detection and suppression, avoiding the use of external sensors for vibration measurement. This not only avoids the influence of unnecessary factors during processing, such as chip splashing and processing space limitations, but also allows the sensor to be installed closer to the vibration source, greatly improving control efficiency and accuracy.

[0048] Figure 2 This demonstrates the installation of the self-sensing, self-driven intelligent vibration damping tool holder system 22 with the spindle. In this embodiment, the rotating device includes a tool holder body 1 directly connected to the machining spindle, a bearing positioning device 16, and a rolling bearing 15. The snap ring cap 8 applies a clamping force to the spring collet 7 through a threaded engagement with the end of the tool holder body 1, ensuring that the spring collet 7 firmly clamps the cutting tool 9 and prevents it from falling off. The inner ring of the rolling bearing 15 is connected to the bearing positioning device 16 with an interference fit. The bearing positioning device 16 is equipped with a positioning ring and a positioning hole. The positioning ring ensures precise axial positioning between the bearing positioning device 16 and the inner ring of the rolling bearing 15, directly contacting the inner ring of the rolling bearing 15. The positioning hole is used to determine the axial position between the bearing positioning device 16 and the tool holder body 1. The two are fixedly connected by bolts to ensure that the rolling bearing 15 will not loosen during the rotation of the tool holder body 1. All components and the tool holder body 1 form a tight fit, avoiding dynamic imbalance during the cutting process.

[0049] In this embodiment, four radial piezoelectric ceramic actuators 12 in the driving device are evenly distributed on the radial plane of the tool holder body 1. The base sleeve 5 serves as the carrier for their installation and load-bearing. They are at a 90° angle to each other, and the angle can be adjusted according to the specific actual situation. This ensures that when the tool holder body 1 vibrates radially in any direction, the radial piezoelectric ceramic actuators 12 can cooperate to generate a corresponding driving force to cancel the vibration displacement. At least two eddy current displacement sensors 6 are installed on the lower part of the radial piezoelectric ceramic actuators 12. The probes of the eddy current displacement sensors 6 are threaded and fixed through the threaded holes at the bottom of the base sleeve 5, as close as possible to the radial piezoelectric ceramic actuators 12 to ensure the accuracy of their measurement results. They directly detect the radial vibration displacement of the tool holder body 1 and are used as a direct evaluation of the control voltage of the radial piezoelectric ceramic actuators 12. No matter what direction the tool holder body 1 vibrates in the radial plane, the radial piezoelectric ceramic actuators 12 can cooperate to generate a corresponding driving force to cancel the vibration.

[0050] In this embodiment, at least four piezoelectric ceramic actuators are axially arranged inside the upper and lower bearing housings 11, located on the central axial plane of the tool holder body 1, and arranged symmetrically in pairs. They are pressed into the upper and lower bearing housings 11 by direct contact between the pre-tightening bolts 4 and the piezoelectric protective layer 3. At least one acceleration sensor 10 is installed at the bottom of the lower bearing housing 11, which can directly detect and analyze vibration signals in multiple directions and convert the corresponding vibration signals into analog voltage outputs to control the driving force output of the axial piezoelectric ceramic actuators 14. This can suppress the axial vibration generated by the tool holder body 1 during the cutting process.

[0051] In this embodiment, all self-sensing piezoelectric ceramic actuators are equipped with a piezoelectric sheath 3. The piezoelectric sheath 3 and the piezoelectric ceramic actuator are tightly bonded together with epoxy resin. Its function is not only to transmit the driving force of the piezoelectric ceramic actuator, but also to ensure that the piezoelectric ceramic actuator is protected from the shearing forces that may be generated inside the tool holder system during cutting, which could cause irreversible damage to the piezoelectric ceramic actuator. The piezoelectric ceramic actuator is connected to the base sleeve 5 via a preload bolt 4, ensuring the application of preload and unidirectional freedom.

[0052] In this embodiment, the drive device also includes a fixing layer 2 connected to the outer ring of the machining spindle. The fixing layer 2 and the bottom sleeve 5 are in close contact and are connected by bolts to keep them fixed. The fixing layer 2 serves as the load-bearing carrier of the entire drive device. Its upper end is fixed to the machining spindle by bolts to ensure its stability during the cutting process. The fixing layer 2 can be customized according to different types of machining spindles, so that the self-sensing and self-driving intelligent vibration damping tool holder system 22 is not only suitable for robot cutting processing, but also for machine tool cutting processing. This further enhances the versatility and convenience of the piezoelectric vibration damping tool holder system.

[0053] In this embodiment, the rolling bearing 15 is a deep groove ball bearing, which can withstand not only large radial loads but also a certain axial load. The bearing type can be changed according to the specific processing conditions and load requirements. The bearing type selected in this invention is a custom 4200A; the material of the tool holder body 1, snap ring cap 8, cutting tool 9, spring collet 7, and bearing positioning device 16 is 20CrMnTi; the material of the rolling bearing 15, bottom sleeve 5, fixing layer 2, upper and lower bearing housings 11, and piezoelectric protective layer 3 is heat-treated 45# steel.

[0054] In this embodiment, the piezoelectric ceramic actuator generates driving force using its inverse piezoelectric effect. When an electric field is applied in the polarization direction of the piezoelectric ceramic, the ceramic will generate corresponding driving force and displacement as the electric field strength changes. However, a single piezoelectric ceramic can only generate a small driving force and displacement. Therefore, in industry, multiple piezoelectric sheets are sintered together, with electrodes connected between each layer to achieve greater displacement and stronger driving force output. This stacked structure increases the total electric field strength when a voltage is applied, thereby enhancing the piezoelectric effect and increasing the output mechanical energy. The piezoelectric ceramic actuator is made of multiple piezoelectric ceramic sheets sintered at high temperature. Its specific model is PSt150 / 14×14 / 20L, with a maximum / nominal displacement of 28 / 20μm, capacitance of 14.5μF, stiffness of 500N / μm, resonant frequency of 47kHz, and weight of 31.3g. The bolts are all made of stainless steel, and the wire 18 is made of copper enameled wire.

[0055] This embodiment also proposes a method for suppressing cutting vibration in conjunction with the aforementioned self-sensing and self-driving intelligent tool holder system. This self-sensing and self-driving intelligent tool holder system has two installation scenarios: one is installation on the machine tool spindle 21 (see...). Figure 4 Another type is mounted on the robot spindle 17 (see...). Figure 5 The steps for vibration suppression in machining are as follows:

[0056] S1. During cutting operations, the machining state is used to determine whether it is milling or drilling. The difference in the direction of the cutting force between milling and drilling leads to different vibration directions of the tool holder: In milling, the cutting force acts along the cutting direction and normal direction of the tool, causing the tool holder to vibrate in multiple directions; while in drilling, the cutting force mainly acts along the axial direction of the drill bit, causing the tool holder to vibrate mainly in the axial direction. This difference in directionality makes the vibration of the tool holder in milling more complex, but the main vibration is still in the radial plane, while the vibration of the tool holder in drilling is relatively simple and concentrated.

[0057] S2. If the machining state is milling, the vibration of the tool holder body 1 in the radial plane is detected in real time by the eddy current displacement sensor 6. The self-sensing and self-driving intelligent tool holder system contains at least two eddy current displacement sensors 6. The current vibration displacement is determined by detecting the output of the analog voltage, indicating whether the vibration displacement is moving closer to or further away from the sensor. The eddy current displacement sensor 6 operates non-contactly, eliminating the need for physical contact with the sensing target, thus avoiding wear and contamination problems. It has good linearity and high resolution, enabling accurate measurement of minute displacement changes. It is suitable for high temperature, high pressure, and harsh environments, exhibiting strong corrosion resistance and stability. It has a fast response speed, allowing real-time monitoring of target position changes, and is widely used in precision measurement and automated control systems.

[0058] S3. If the machining state is drilling, the vibration of the tool holder body 1 in the axial plane is detected in real time by the accelerometer 10. The self-sensing and self-driving intelligent tool holder system includes at least one accelerometer 10, which determines the specific direction of the current vibration displacement by detecting the output of the analog voltage. The accelerometer 10 has a fast response speed and can detect signal changes in real time; it has a wide frequency response range and good linearity, and can accurately measure dynamically changing signals; it has a simple structure, small size, and is easy to integrate and install; it is stable and reliable in operation and requires almost no maintenance during long-term use.

[0059] S4. The vibration signal from the corresponding sensor is transmitted to the controller 20 in the form of an analog voltage. The controller 20, based on a pre-set control algorithm (e.g., PID control, fuzzy control, neural network control), tunes the voltage to obtain the optimal control voltage value. The fuzzy PID control method, by combining the advantages of fuzzy logic and traditional PID control, effectively handles system nonlinearity and uncertainty, improving the adaptability and robustness of vibration suppression. It improves system response speed, reduces steady-state error, and provides better performance in multi-objective control and complex systems, while simplifying the design and adjustment process of the control system. When using the fuzzy PID control algorithm to tune the parameters of the acquired vibration signal, unlike traditional PID control strategies, it can dynamically change the parameters of the PID controller 20 based on tracking error signals, thereby achieving a wider vibration control range and better vibration control effect.

[0060] S5, The sensor collects vibration signals as v a Compare with the desired value r set in controller 20; use the deviation e (e = r - v) a (where r is the expected value of 0) and the rate of change of deviation e c As input to the fuzzy self-tuning PID control algorithm, to satisfy e and e at different times. c To meet the self-tuning requirements of PID parameters, a two-dimensional fuzzy controller 20 with two inputs and three outputs is established. Based on professional knowledge and control experience, fuzzy control rules are established, as shown in Table 1. For each input and output variable, a universe of discourse (i.e., the possible range of values ​​for the variable) is defined. A fuzzy set is defined for each variable, typically including several fuzzy subsets, such as {NB (negative large), NM (negative medium), NS (negative small), ZO (zero), PS (positive small), PM (positive medium), PB (positive large)}. For the deviation e and the rate of change of deviation e... c The universe of discourse is initially set to [-10, 10], and each variable has 7 fuzzy subsets. For ΔK p ΔK I ΔK DThe universe of discourse is initially set to [0.1, 5] based on the actual system and experience, and corresponding fuzzy subsets are defined. To enhance the system robustness and control sensitivity, Z-shaped and S-shaped membership functions are selected for the linguistic values ​​NB and PB of each input and output variable, respectively, while triangular membership functions are selected for the remaining linguistic values.

[0061] Table 1 Fuzzy Control Rules

[0062]

[0063] The rule describes the relationship between the input variables and the PID parameter tuning. The input variables are e and ep. c The output is the three correction values ​​ΔK of the 20 parameters of the PID controller. p ΔK I ΔK D .

[0064]

[0065] in , , For speed correction values, their values ​​will decrease as the number of corrections increases, or they can be set to constants. Next, the control parameters in controller 20 can be composed of the weighted sum of the current controller 20 parameters and the incremental controller 20 parameters derived from fuzzy inference. Finally, the PID controller 20 outputs the final control voltage. .

[0066]

[0067] Discretizing the above equation is necessary because sensor signals in digital control systems typically need to be discretized for use in controller 20.

[0068]

[0069] S6. The control voltage is transmitted to the power amplifier 19 via the analog-to-digital converter of the controller 20. The power amplifier 19 amplifies the analog voltage by 15 times and transmits it to the corresponding piezoelectric ceramic actuator. The piezoelectric ceramic has the inverse piezoelectric effect, which generates a corresponding driving force according to the polarization direction and the applied electric field, thereby suppressing the vibration of the tool holder body 1 in the current direction. Alternatively, when the axial and radial vibrations are relatively large due to the influence of machining parameters during the cutting process, all sensors and piezoelectric ceramic actuators can be used simultaneously. Since the accelerometer 10 can measure vibration in three dimensions, it can not only be used as a measurement feedback loop, but also be connected to an external vibration signal analysis instrument to view the vibration suppression effect in real time.

[0070] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for suppressing cutting vibration in a self-sensing, self-driven intelligent vibration damping tool holder system, characterized in that, The vibration damping tool holder system includes: a rotating device for completing the cutting process, a driving device for reducing vibration, and a detection device for real-time vibration feedback. The rotating device is mounted on the machining spindle. The rotating device includes a bearing positioning device and a rolling bearing located on the outer circumference of the tool holder body. The rolling bearing is housed within a bearing housing. The bearing housing is formed by assembling an upper bearing housing and a lower bearing housing. A fixed layer is connected to the machining spindle, and a bottom sleeve is connected to the fixed layer. A space for supporting the entire drive device is formed between the fixed layer and the bottom sleeve. At least two eddy current displacement sensors are installed inside the bottom sleeve and located below the radial piezoelectric ceramic actuator. At least one acceleration sensor is installed at the bottom of the lower bearing housing. The detection device is arranged around the circumference of the tool holder body; the driving device is fixed to the outer ring of the machining spindle; the driving device includes: At least four radial piezoelectric ceramic actuators are evenly spaced and arranged at a predetermined angle to each other on the radial plane of the tool holder body to suppress radial vibration of the tool holder body; At least four axial piezoelectric ceramic actuators are arranged symmetrically in pairs inside the upper bearing housing and the lower bearing housing, and are located in the central axial plane of the tool holder body to suppress axial vibration of the tool holder body. The detection device includes an acceleration sensor and an eddy current displacement sensor, which detect the vibration of the tool holder body in real time. The vibration suppression method includes: If it is in the milling process, the vibration of the tool holder body in the radial plane is detected in real time by the eddy current displacement sensor. The self-sensing and self-driving intelligent vibration reduction tool holder system includes at least two eddy current displacement sensors. The current vibration displacement is determined by detecting the output of the analog voltage to determine whether the current vibration displacement is closer to or farther from the sensor. If it is in the drilling process, the vibration of the tool holder body in the axial plane is detected in real time by an accelerometer. The self-sensing and self-driving intelligent vibration reduction tool holder system includes at least one accelerometer, which determines the specific direction of the current vibration displacement by detecting the output of the analog voltage. The vibration signals from the eddy current displacement sensor and / or acceleration sensor are transmitted to the controller, which uses a fuzzy PID control algorithm to tune the collected vibration signals into a control voltage before outputting them.

2. The method for suppressing cutting vibration in the self-sensing, self-driven intelligent vibration damping tool holder system according to claim 1, characterized in that: The rotating device includes a tool holder body directly connected to the machining spindle, a snap ring cap connected to the lower end of the tool holder body, and a cutting tool clamped by a spring collet.

3. The method for suppressing cutting vibration in the self-sensing, self-driven intelligent vibration damping tool holder system according to claim 2, characterized in that: The inner ring of the rolling bearing is connected to the bearing positioning device by an interference fit. The bearing positioning device is provided with a positioning ring and a positioning hole. The upper end face of the positioning ring coincides with the surface of the inner ring of the rolling bearing. The positioning hole is connected to the bearing positioning device and the tool holder body by bolts.

4. The method for suppressing cutting vibration in the self-sensing, self-driven intelligent vibration damping tool holder system according to claim 1, characterized in that: The drive device also includes a fixing layer connected to the outer ring of the machining spindle; The piezoelectric ceramic actuator includes a radial piezoelectric ceramic actuator and an axial piezoelectric ceramic actuator; The radial piezoelectric ceramic actuators are distributed radially inside the bottom sleeve, and the axial piezoelectric ceramic actuators are distributed axially inside the bearing housing.

5. The method for suppressing cutting vibration in the self-sensing, self-driven intelligent vibration damping tool holder system according to claim 4, characterized in that: All piezoelectric ceramic actuators transmit driving force through the piezoelectric sheath. Threaded holes are opened on the circumference of the base sleeve, and preload bolts apply preload to the piezoelectric ceramic actuators through these threaded holes.

6. The method for suppressing cutting vibration in the self-sensing, self-driven intelligent vibration damping tool holder system according to claim 1, characterized in that: The controller is a two-input, three-output two-dimensional fuzzy controller, with the inputs being the deviation e and the rate of change of the deviation e. c The output consists of three correction values ​​for the PID controller parameters. , , The three correction quantities satisfy the following relationship: ； In the formula, , , These are speed correction values, which decrease as the number of corrections increases; This represents the proportional gain at time k. This represents the integral gain at time k. k represents the differential gain at the current k-th time; k-1 represents the previous time. The control parameters in the next step of the controller are composed of a weighted sum of the current controller parameters and the controller parameter increments derived from fuzzy inference. Finally, the final control voltage is output through the PID controller. : ； In the formula, This represents the error at the current moment, that is, the difference between the set value and the theoretical value; Discretizing the above equation, we get: ； In the formula, This represents the difference between the set value and the theoretical value after discretization. Discretized control voltage The force is transmitted to the piezoelectric ceramic actuator, which generates a corresponding driving force based on the polarization direction and the applied electric field, thereby suppressing the vibration of the tool holder body in the current direction.

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