A dual swing angle spindle with adaptive vibration suppression and online dynamic balancing function and a vibration suppression method thereof

Abstract

This invention discloses a double-swivel spindle with adaptive vibration suppression and online dynamic balancing functions, and its vibration suppression method. The spindle includes a C-axis, an A-axis, a sensor system, a signal acquisition and processing unit, and a control unit. The A-axis is hinged to one end of the C-axis and is equipped with an electric slider and an eccentric adjustment motor. The sensor system is used to collect signals during the machining process of the double-swivel spindle in real time. The signal acquisition and processing unit acquires the signals collected by the sensor system, processes the signals, calculates the vibration error and the rate of change of error, and calculates a compensation command based on the vibration error and the rate of change of error using a fuzzy sliding control strategy. The control unit controls the movement of the electric slider and the rotation of the eccentric adjustment motor according to the compensation command. By calculating the compensation control amount based on the real-time acquired vibration signals, the movement of the electric slider and the rotation of the eccentric adjustment motor are controlled to level the dynamic balance of the double-swivel spindle, improving the operating stability of the spindle system and the surface quality of the machined parts.

Description

Technical Field

[0001] This invention relates to machine tool spindle machining, specifically to a double-swivel spindle with adaptive vibration suppression and online dynamic balancing functions, and a vibration suppression method thereof. Background Technology

[0002] With the increasing demand for high-precision and high-efficiency machining, the vibration and imbalance problems of CNC machine tool spindle units under high-speed cutting and complex working conditions are becoming increasingly prominent. Traditional online dynamic balancing technology for single-angle spindles mainly targets vibrations generated by the Z-axis or the spindle's own rotation, making it difficult to adapt to complex structures with two swing degrees of freedom, either A-axis or C-axis. In double-angle spindles, the multi-order harmonic vibrations caused by changes in the swing angle and the superposition of cutting loads are even more complex. Traditional dynamic balancing devices are usually performed offline, unable to compensate for eccentric mass in real time, leading to decreased surface quality, shortened tool life, and the need for frequent machine stops for calibration, thus affecting production efficiency.

[0003] Existing technologies include methods for correcting spindle imbalances using a single vibration sensor or accelerometer in conjunction with an offline dynamic balancing machine. However, these methods fail to achieve real-time online dynamic balancing and adaptive vibration suppression in double-pendulum structure spindles. Furthermore, existing vibration control methods are mostly based on fixed-parameter PID or frequency response compensation, which struggles to cope with real-time changes in cutting conditions and pendulum angles, resulting in slow response speeds and low compensation accuracy. Summary of the Invention

[0004] Purpose of the invention: To address the above problems, this invention provides a dual-swing angle spindle with adaptive vibration suppression and online dynamic balancing functions, achieving fast response and high compensation accuracy.

[0005] The present invention also provides a processing apparatus and a processing method for using the above-described electrolysis-turning combined machining cathode device.

[0006] Technical Solution: To solve the above problems, this invention employs a double-swing-angle spindle with adaptive vibration suppression and online dynamic balancing functions, including a C-axis, an A-axis, a sensor system, a signal acquisition and processing unit, and a control unit. The A-axis is hinged to one end of the C-axis and swings relative to the C-axis. An electric slider is installed on the C-axis, sliding radially along the C-axis in a direction parallel to the extension direction of the A-axis. An eccentric adjustment device is installed on the A-axis, comprising an eccentric adjustment motor and an eccentric mass block mounted on the output shaft of the eccentric adjustment motor. The output shaft of the eccentric adjustment motor is perpendicular to the extension direction of the A-axis, and the rotation plane of the eccentric mass block is parallel to the extension direction of the A-axis. The sensor system is used to collect signals during the machining process of the double-swing-angle spindle in real time. The signal acquisition and processing unit is used to acquire the signals collected by the sensor system, process the signals, calculate the vibration error and the rate of change of error, and calculate the compensation command based on the vibration error and the rate of change of error using a fuzzy sliding diaphragm control strategy. The control unit is used to control the movement of the electric slider and the rotation of the eccentric adjustment motor according to the compensation command.

[0007] Furthermore, the sensor system includes an inertial measurement unit and a vibration sensor. The inertial measurement unit is used to acquire the angular velocity and linear acceleration during the spindle attitude change process, and the vibration sensor is used to acquire the vibration signal of the spindle.

[0008] Furthermore, at least three inertial measurement units are provided, all installed in the oscillating pair structure of the A-axis and C-axis, and at least four vibration sensors are provided, symmetrically installed on the outer side of the front and rear bearing seats of the spindle, for real-time monitoring of the vibration characteristics of the spindle in the X, Y, and Z three-dimensional directions.

[0009] Furthermore, the signal acquisition and processing unit includes an analog front-end, an analog-to-digital converter, an FPGA processing unit, and a DSP processing unit. The analog front-end is used to filter and amplify the acquired signal to obtain an amplified analog signal. The analog-to-digital converter is used to convert the amplified analog signal into a digital signal. The FPGA processing unit is used to perform frequency domain processing on the digital signal. The DSP processing unit is used to perform time domain processing on the frequency-domain processed digital signal to obtain time domain characteristics. Error integration is performed using the time domain characteristics to obtain the vibration error and error rate of change. The compensation command is then calculated based on the vibration error and error rate of change using a fuzzy control strategy.

[0010] Furthermore, the FPGA processing unit is used to perform fast Fourier transform and wavelet packet decomposition on the digital signal, and to decouple and filter out the swing angle state change and vibration disturbance through a multivariable Kalman filter algorithm.

[0011] Furthermore, the fuzzy sliding mode control strategy includes a fuzzy control algorithm and a sliding mode control algorithm. When the vibration error is less than a threshold, the fuzzy control algorithm is used. The fuzzy control algorithm outputs a compensation torque based on the vibration error and the error change rate. The displacement compensation of the electric slider and the motor rotation angle compensation of the eccentric adjustment device are calculated based on the compensation torque. When the vibration error is greater than the threshold, the sliding mode control algorithm is used to compensate the fuzzy control algorithm. The sliding mode control algorithm designs a sliding surface s = λe + Δe. The displacement compensation and angle compensation output by the fuzzy control algorithm are further corrected by the sliding mode law, where e is the vibration error, Δe is the error change rate, and λ is the design parameter.

[0012] Furthermore, a radial groove is formed inside the C-axis, with the groove extending parallel to the A-axis. A slider motor is installed at one end of the groove, and a lead screw is connected to the output end of the slider motor. The electric slider is threadedly connected to the lead screw, and the electric slider slides in the groove. The slider motor drives the lead screw to rotate, thereby causing the electric slider to move along the groove.

[0013] Furthermore, the slide is provided with an elastic buffer limit block, which is used to prevent the slide from overshooting.

[0014] The present invention also employs a vibration suppression method for the above-mentioned double-swivel-angle spindle, comprising the following steps:

[0015] (1) Real-time acquisition of signals during the machining process of the double-swivel spindle, including angular velocity, linear acceleration and vibration signals;

[0016] (2) The acquired signal is processed by filtering, amplification and conversion to generate a digital signal;

[0017] (3) Extract frequency domain features and signal structure from digital signals, extract time domain errors from digital signals after frequency domain feature extraction, and calculate vibration error and error change rate based on time domain error;

[0018] (4) The compensation command quantity is calculated based on the vibration error and the error change rate using the fuzzy sliding diaphragm control strategy;

[0019] (5) Control the movement of the electric slider and the rotation of the eccentric adjustment motor according to the compensation command.

[0020] Furthermore, in step (1), the harmonic spectrum characteristics of the collected vibration signal are analyzed and the dynamic response amplitude is calculated; if the calculated vibration dynamic response amplitude exceeds the preset threshold, then step (2) is performed.

[0021] Beneficial effects: Compared with the prior art, the significant advantage of this invention is that by calculating the compensation control quantity based on the real-time collected vibration signal, the electric slider movement and the eccentric adjustment motor rotation are controlled to level the dynamic balance of the double-swing angle spindle. By constructing an intelligent compensation system integrating "sensing-processing-control-execution", the invention achieves online vibration monitoring, active intervention and high-precision dynamic balancing of the spindle in the multi-degree-of-freedom dynamic swing state of the A / C axis, thereby improving the operating stability of the spindle system and the surface quality of the machined surface. Attached Figure Description

[0022] Figure 1 This is a cross-sectional view of the double-swivel angle main shaft in this invention.

[0023] Figure 2 This is a functional block diagram of the vibration suppression control method in this invention.

[0024] Figure 3 This is a schematic diagram of the fuzzy sliding mode control process in this invention. Detailed Implementation

[0025] Example 1

[0026] Depend on Figure 1 As shown in this embodiment, a dual-swivel-angle spindle device with adaptive vibration suppression and online dynamic balancing functions is applicable to A / C axis dual-swivel-angle CNC machine tool spindles. By constructing a closed-loop mechanism of "sensing-processing-control-execution", it realizes dynamic balance control and multi-order adaptive vibration suppression under multi-degree-of-freedom spindle posture. The device mainly includes five functional units: an inertial measurement unit (IMU), a vibration sensor array, a signal acquisition and processing unit, a control unit, and a compensation execution mechanism.

[0027] The sensing modules are configured within the A-axis and C-axis oscillating joint structures of the main spindle, each integrating three sets of six-DOF inertial measurement units (IMUs). Their housings are fixed to pre-set sensor mounting slots on the inner wall of the main spindle oscillating joint structure housing using screws, and connected to a signal acquisition board via plugs and signal cables. Each IMU module integrates a three-axis gyroscope and a three-axis accelerometer (vibration sensor) to accurately acquire changes in the angular velocity and linear acceleration of the main spindle in any attitude, providing real-time attitude calculation data, especially for high-speed attitude disturbances during dual-swing linkage processes.

[0028] Four vibration sensors are symmetrically arranged on the outer side of the bearing housings at the front and rear ends of the spindle via threads. The sensor housings are fixed to the bearing housings with metal sleeves and shielding layers are added to prevent interference. This sensor array is used to sense the micro-amplitude vibration signals of the spindle in the X, Y, and Z directions, realizing the synchronous acquisition of spatial vibration data and achieving spatial perception and multi-source fusion of vibration distribution changes under dual swing angle postures.

[0029] The signal acquisition and processing unit includes an analog front-end, an analog-to-digital converter (ADC), an FPGA processing unit, and a DSP processing unit. Various sensor signals first undergo bandpass filtering, amplification, and shaping at the analog front-end, and then are digitized in real-time by a high-resolution analog-to-digital converter (A / D). The sampling frequency is no less than 1kHz to meet the dynamic response requirements during high-speed spindle rotation and attitude changes, providing real-time and high-fidelity data conversion performance. The module uses a stacked PCB structure and is fixedly connected to the elastic vibration damping mounting base inside the spindle housing. The digital signals then pass through the FPGA and DSP modules sequentially for frequency and time domain processing, respectively. After A / D conversion, the digital signals first enter the FPGA module for frequency domain feature processing, including Fast Fourier Transform (FFT), wavelet decomposition, and multivariable extended Kalman filtering. Its main function is to extract characteristic frequencies from the full-band vibration signal, locate harmonic sources, and achieve state decoupling, providing target frequency bands and disturbance references for time-domain control. The signal then enters the DSP module for time-domain feature extraction and control calculation. Based on the fusion of frequency-domain features, the DSP outputs compensation commands, thereby realizing dual-channel control of the radial displacement Δr of the electric slider and the rotation angle Δθ of the eccentric adjustment motor.

[0030] like Figure 3 As shown, in the dynamic control of the double-swivel spindle, a composite architecture of fuzzy control and sliding mode control is adopted: when the system vibration deviation is large, the sliding mode control module takes the lead, ensuring convergence speed and global robustness; when the deviation enters a small range, fuzzy control takes over, adjusting the compensation torque based on the real-time error e(k) and the error change rate Δe(k), thereby avoiding chattering caused by sliding mode switching. Through this "large deviation - sliding mode control, small deviation - fuzzy control" mode, rapid convergence and low residual stable control under high-speed attitude disturbances are achieved.

[0031] Combined with appendix Figure 2 The complete process shown illustrates that the fuzzy inference module takes the error e(k) and the rate of change of error Δe(k) as inputs and outputs two compensation quantities: one is the radial displacement compensation Δr, used to drive the electric slider to adjust the counterweight position; the other is the axial angle compensation Δθ, used to control the eccentric adjustment motor to adjust the angular distribution of the eccentric mass, achieving dual-dimensional adaptive compensation. The dual outputs of the fuzzy inference are directly fed into the DSP module for decomposition processing: when the deviation is within a small range, the DSP directly calls the fuzzy outputs Δr and Δθ as the final compensation instructions; when the deviation is large, the DSP constructs a sliding surface s=λe+Δe based on the fuzzy output results and enters the sliding mode control loop, where the sliding mode law further corrects the compensation quantity, ensuring that the system still has strong robustness and fast convergence under large disturbances. Thus, the attached... Figure 2The "error e" output path corresponds to the small deviation case and directly enters fuzzy compensation; while the "sliding surface s" path corresponds to the large deviation case and is adjusted by the sliding surface controller. Finally, the control commands processed by the DSP are uniformly sent to the compensation actuator, driving the electric slider and the eccentric adjustment motor to work together to achieve online dynamic balance and vibration adaptive suppression of the double-swivel spindle under multi-degree-of-freedom dynamic posture.

[0032] The compensation actuator mainly consists of two parts: an electric slider mechanism and an eccentric adjustment motor assembly. The electric slider is fixed inside the C-axis spindle structure. A radial groove is formed within the C-axis body, parallel to the extension direction of the A-axis. An embedded counterweight slider slides along the groove via a rectangular slider guide rail, with elastic buffer limit blocks at both ends of the guide rail to prevent overshoot. The electric slider mechanism is equipped with a micro servo motor and a ball screw drive pair. The electric slider and ball screw are threaded together, and the micro servo motor drives the ball screw to rotate, thereby driving the electric slider to slide along the rectangular slider guide rail. The A-axis is fixed inside the oscillating head machine body. The rotation of the A-axis around the C-axis drives the oscillating head machine body to rotate. A machining head is fixedly mounted on the oscillating head machine body. The eccentric adjustment motor is arranged in the tail cavity of the oscillating head machine body, rigidly connected to the cylindrical shell at the tail end of the body via a flange to ensure installation stability under high-speed conditions. The output shaft of the eccentric adjustment motor is perpendicular to the extension direction of the A-axis and parallel to the extension direction of the machining head. The rotation center of the eccentric adjustment motor is parallel to the rotation center of the spindle.

[0033] An eccentric mass block is directly mounted on the output shaft of the eccentric adjustment motor. The center of mass of this mass block is fixedly offset from the rotation center of the eccentric adjustment motor. The rotation plane of the eccentric mass block on the output shaft of the eccentric adjustment motor is parallel to the extension direction of axis A. When the eccentric adjustment motor is driven, a controllable eccentric torque is generated within the cross-section of the oscillating head body. By adjusting the rotation angle of the eccentric adjustment motor, the orientation of the eccentric mass block relative to axis A can be changed within a range of ±180°, realizing online dynamic adjustment of the direction of the inertial force vector. This adjustment is based on the axis of the oscillating head body, that is, the eccentric adjustment motor drives the eccentric mass block to rotate in a plane parallel to the cross-section of the oscillating head body, so that the direction of the compensation torque is opposite to the direction of the real-time detected disturbance torque, thereby effectively counteracting the unbalanced force.

[0034] The motor power and signal lines are led out via slip rings to ensure reliable power supply and signal transmission during the spindle's oscillation motion. The DSP module calculates the angle compensation Δθ based on sensor feedback data and drives the eccentric adjustment motor in real time to adjust the angular position of the eccentric mass block. Combined with the radial displacement compensation Δr provided by the electric slider, the two work together to form a "dual-dimensional" dynamic compensation mechanism, thereby achieving online dynamic balance and multi-order harmonic vibration suppression of the spindle under A / C dual-oscillation postures.

[0035] When the spindle is in a high-speed rotation and multi-angle swing state, the IMU and vibration sensor provide real-time feedback on the eccentric imbalance state of the spindle system. The DSP algorithm outputs the required radial displacement Δr and angle compensation Δθ, driving the electric slider to adjust the counterweight position radially along the C-axis spindle. The eccentric adjustment motor drives the eccentric mass block at the tail end of the A-axis to adjust the angle direction in a plane parallel to the cross-section of the swing head body, so that the equivalent centrifugal force vector and the disturbance torque are superimposed and canceled in opposite directions, ultimately achieving dynamic balance and harmonic suppression of the spindle system.

[0036] In terms of structural layout, the slider guide groove and motor platform are integrally machined into the inner wall of the spindle housing. All connections adopt a double fastening structure and are equipped with wear-resistant limit rings and stroke detection switches. Power supply and signal transmission between components are achieved through pre-embedded cables, flexible wires, and slip rings, ensuring high reliability.

[0037] The device then re-enters the sensing-processing-control cycle to determine if the residual vibration meets the standard. If high-frequency interference or low-frequency drift still exists, the next round of compensation iteration is performed until the residual stabilizes within the set threshold, completing the adaptive dynamic balance. All sensor feedback signals and control commands maintain real-time closed-loop communication with the main control system via high-speed industrial Ethernet, forming a four-stage dynamic compensation mechanism of multi-source sensing, rapid calculation, precise execution, and stable feedback.

[0038] Example 2

[0039] This embodiment describes a vibration suppression method for a double-swivel-angle spindle as described above, comprising the following steps:

[0040] (1) IMU and vibration sensor are arranged at the A-axis and C-axis rotary joint of the spindle to collect spindle angular velocity, linear acceleration and vibration information in real time; the sensor sampling rate is not less than 1kHz to ensure high response capability and real-time control under typical working conditions such as double swing angle fast attitude adjustment, intermittent cutting or complex path machining.

[0041] (2) The collected analog signal is filtered and amplified by the analog front end and then sent to the A / D converter to generate a digital signal;

[0042] (3) Frequency domain feature extraction and signal decoupling are performed in the FPGA, and time domain error extraction and control calculation are performed in the DSP;

[0043] (4) The radial displacement Δr of the counterweight slider and the angle compensation Δθ of the eccentric adjustment motor are generated by the fuzzy control and sliding mode control modules respectively;

[0044] (5) Drive the compensation actuator to complete real-time dynamic balance adjustment;

[0045] (6) Determine whether the current residual vibration amplitude is less than 1 μm. If not, repeat steps (1) to (5).

Claims

1. A double-swivel spindle with adaptive vibration suppression and online dynamic balancing functions, characterized in that, The system includes a C-axis, an A-axis, a sensor system, a signal acquisition and processing unit, and a control unit. The A-axis is hinged to one end of the C-axis and swings relative to the C-axis. The C-axis is equipped with an electric slider that slides radially along the C-axis in a direction parallel to the extension direction of the A-axis. The A-axis is equipped with an eccentric adjustment device, which includes an eccentric adjustment motor and an eccentric mass block disposed on the output shaft of the eccentric adjustment motor. The output shaft of the eccentric adjustment motor is perpendicular to the extension direction of the A-axis, and the rotation plane of the eccentric mass block is parallel to the extension direction of the A-axis. The sensor system is used to acquire signals in real time during the machining process of the double-swivel spindle. The signal acquisition and processing unit is used to acquire the signals acquired by the sensor system, process the signals, calculate the vibration error and the rate of change of error, and calculate the compensation command based on the vibration error and the rate of change of error using a fuzzy sliding diaphragm control strategy. The control unit is used to control the movement of the electric slider and the rotation of the eccentric adjustment motor according to the compensation command.

2. The double-swivel-angle spindle according to claim 1, characterized in that, The sensor system includes an inertial measurement unit and a vibration sensor. The inertial measurement unit is used to collect the angular velocity and linear acceleration during the spindle attitude change process, and the vibration sensor is used to collect the vibration signal of the spindle.

3. The double-swivel angle spindle according to claim 2, characterized in that, At least three inertial measurement units are provided, all installed in the oscillating pair structure of the A-axis and C-axis. At least four vibration sensors are provided, symmetrically installed on the outer side of the front and rear bearing seats of the spindle, for real-time monitoring of the vibration characteristics of the spindle in the X, Y, and Z three-dimensional directions.

4. The double-swivel angle spindle according to claim 1, characterized in that, The signal acquisition and processing unit includes an analog front-end, an analog-to-digital converter, an FPGA processing unit, and a DSP processing unit. The analog front-end is used to filter and amplify the acquired signal to obtain an amplified analog signal. The analog-to-digital converter is used to convert the amplified analog signal into a digital signal. The FPGA processing unit is used to perform frequency domain processing on the digital signal. The DSP processing unit is used to perform time domain processing on the frequency-domain processed digital signal to obtain time domain characteristics. Error integration is performed based on the time domain characteristics to obtain the vibration error and error rate of change. The compensation command is then calculated based on the vibration error and error rate of change using a fuzzy control strategy.

5. The double-swivel angle spindle according to claim 4, characterized in that, The FPGA processing unit is used to perform fast Fourier transform and wavelet packet decomposition on digital signals, and to decouple and filter out swing angle state changes and vibration disturbances through a multivariable Kalman filter algorithm.

6. The double-swivel angle spindle according to claim 4, characterized in that, The fuzzy sliding mode control strategy includes a fuzzy control algorithm and a sliding mode control algorithm. When the vibration error is less than a threshold, the fuzzy control algorithm is used. The fuzzy control algorithm outputs a compensation torque based on the vibration error and the error change rate. The displacement compensation of the electric slider and the motor rotation angle compensation of the eccentric adjustment device are calculated based on the compensation torque. When the vibration error is greater than the threshold, the sliding mode control algorithm is used to compensate the fuzzy control algorithm. The sliding mode control algorithm designs a sliding surface s = λe + Δe. The displacement compensation and angle compensation output by the fuzzy control algorithm are further corrected by the sliding mode law, where e is the vibration error, Δe is the error change rate, and λ is the design parameter.

7. The double-swivel angle spindle according to claim 4, characterized in that, A radial groove is formed inside the C-axis, and the groove extends parallel to the A-axis. A slider motor is installed at one end of the groove, and the output end of the slider motor is connected to a lead screw. The electric slider is threadedly connected to the lead screw. The electric slider slides in the groove, and the slider motor drives the lead screw to rotate, thereby moving the electric slider along the groove.

8. The double-swivel angle spindle according to claim 7, characterized in that, The slide is equipped with an elastic buffer limit block, which is used to prevent the slide from overshooting.

9. A vibration suppression method for a double-swivel-angle spindle according to any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Real-time acquisition of signals during the machining process of the double-swivel spindle, including angular velocity, linear acceleration and vibration signals; (2) The acquired signal is processed by filtering, amplification and conversion to generate a digital signal; (3) Extract frequency domain features and signal structure from digital signals, extract time domain errors from digital signals after frequency domain feature extraction, and calculate vibration error and error change rate based on time domain error; (4) The compensation command quantity is calculated based on the vibration error and the error change rate using the fuzzy sliding diaphragm control strategy; (5) Control the movement of the electric slider and the rotation of the eccentric adjustment motor according to the compensation command.

10. The vibration suppression method according to claim 9, characterized in that, In step (1), the harmonic spectrum characteristics of the collected vibration signal are analyzed and the dynamic response amplitude is calculated; if the calculated vibration dynamic response amplitude exceeds the preset threshold, then step (2) is performed.

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