A numerical control machining parameter self-adaptive intelligent optimization regulation and control system and method

Abstract

The application relates to the field of industrial control systems and discloses a numerical control machining parameter self-adaptive intelligent optimization regulation and control system and method, which comprises a dynamic signal acquisition and conversion module, a state characteristic decoupling and observation test calculation module, a self-adaptive boundary arbitration and control reconstruction module and a real-time interpolation rewriting and driving module. The system acquires alternating current and vibration acceleration signals, reconstructs electromagnetic torque to extract load torque components, calculates a vibration energy entropy value, solves a speed increment to generate a multiple correction factor when the entropy value is out of limit, injects the correction factor into an interpolator buffer zone, rewrites a step length and driving instructions in an interpolation period, realizes cutting load and vibration source decoupling, eliminates false speed reduction, uses speed fine adjustment to destroy self-excitation regeneration phase, linkage adjusts a feeding speed to maintain cutting thickness, eliminates slip wear, rewrites the step length and compensates torque in the interpolation period, and eliminates response lag.

Description

Technical Field

[0001] This invention relates to an adaptive intelligent optimization and control system and method for CNC machining parameters, belonging to the field of industrial control system technology. Background Technology

[0002] In CNC machine tool cutting, adaptive adjustment of cutting parameters is an important means to balance machining efficiency, workpiece surface quality, and tool life. Existing industrial CNC systems usually complete machining with fixed cutting parameters according to pre-programmed CNC programs. However, in the process of machining complex curved contours, cutting difficult-to-machine materials, and tool wear, the cutting resistance, the contact state between the tool and the workpiece, and the dynamic characteristics of the machine tool structure will constantly change, exhibiting strong nonlinearity and time-varying characteristics. Most of the adaptive control in existing industrial control systems uses a single static threshold to judge the cutting state. When the cutting conditions change significantly, as long as the cutting current or cutting force exceeds the preset range, the system will usually reduce the machining speed to avoid overload. This control method, which mainly relies on speed reduction to protect the machining process, still has obvious shortcomings.

[0003] Existing software control strategies and adaptive control algorithms still have shortcomings when dealing with dynamic and complex working conditions. For example, Chinese invention patent CN111694320B discloses a machine tool adaptive control method that considers chatter suppression. It uses a deep learning network to adjust the feed speed based on the power signal and monitors chatter based on weighted wavelet packet entropy to adjust the spindle speed. However, this scheme relies on offline data training and power-vibration discrete judgment. When chatter suppression leads to an increase in power, it directly cancels the speed adjustment, lacking an essential physical decoupling of electromagnetic torque and chatter source characteristics, which easily leads to frequent oscillations in the control state. At the same time, its parameter adjustment... The entire process is completed through external communication and PLC modules, which cannot embed control commands into the underlying CNC interpolation cycle. This results in inherent response lag and servo follow-up lag. To address these issues, simply increasing the amplitude threshold sensitivity or the bus sampling frequency cannot eliminate transmission delay and misjudgment. If the threshold setting is too sensitive, it can easily cause tool breakage or equipment overload damage when real chatter occurs. Increasing the sampling frequency also cannot eliminate the inherent transmission delay between the CNC interpolator and the external control interface. Because the cutting load and chatter characteristics are mixed in the time and frequency domains, they are difficult to distinguish accurately. At the same time, there is a lack of effective timing coordination between the parameter adjustment process and the CNC interpolation cycle.

[0004] Therefore, the technical problem to be solved by this invention is how to accurately distinguish between load fluctuations and self-excited chatter caused by changes in cutting allowance from the acquired signals, establish a coordinated adjustment mechanism for spindle speed and feed rate that can avoid chatter instability zone and maintain reasonable cutting thickness, and embed parameter adjustment commands into the CNC interpolation cycle. Summary of the Invention

[0005] To address the problems in the background art, the technical solution of the present invention is as follows: A CNC machining parameter adaptive intelligent optimization and control system, the system comprising: The dynamic signal acquisition and conversion module is used to synchronously acquire the three-phase AC current signal of the spindle drive and the vibration acceleration signal of the tool holder physical contact, and convert the three-phase AC current signal and vibration acceleration signal into a digital time domain state vector. The state feature decoupling and observation calculation module is used to reconstruct the instantaneous electromagnetic torque of the spindle based on the stator current component and flux linkage component from the digital time domain state vector, extract the cutting load torque component through low-pass filtering, and extract the high-frequency characteristic energy spectrum of the vibration acceleration signal through short-time Fourier transform to calculate the chatter energy entropy value and chatter frequency. The adaptive boundary arbitration and control reconfiguration module is used to calculate the speed fine-tuning increment based on the chatter frequency, the number of tool teeth and the phase locking order when the chatter energy entropy value is greater than or equal to the preset critical threshold, generate the spindle speed multiplier correction factor, and collaboratively generate the feed rate multiplier correction factor. The real-time interpolation rewrite and drive module is used to inject the smoothed feed rate correction factor and spindle speed correction factor into the annular buffer of the CNC interpolator within the current interpolation cycle of the CNC system, and rewrite the feed step size and drive command for the next interpolation cycle.

[0006] Preferably, the sampling frequency of the dynamic signal acquisition and conversion module is set to 10kHz, and the acquisition timing of the three-phase AC current signal and the vibration acceleration signal is triggered and synchronized by the hardware timer interrupt signal of the CNC interpolator, so that the three-phase AC current signal and the vibration acceleration signal are aligned at the microsecond level on the time axis; when the state feature decoupling and observation calculation module performs low-pass filtering on the instantaneous electromagnetic torque of the spindle, the cutoff frequency of the low-pass filter is set to 50Hz.

[0007] Preferably, the state feature decoupling and observation calculation module reconstructs the instantaneous electromagnetic torque of the spindle using the number of pole pairs, flux linkage component, and stator current component after Park transformation of the spindle motor. After reconstruction, the system's no-load loss torque and acceleration inertial torque are deducted to obtain the cutting load torque component that reflects the low-frequency macroscopic cutting resistance.

[0008] Preferably, the state feature decoupling and observation calculation module extracts the short-time spectral energy density of the vibration acceleration signal in the frequency band of 100Hz to 2500Hz, and calculates the flutter energy entropy value using the normalized power spectral density distribution; when the flutter energy entropy value is less than the preset critical threshold and the cutting load torque component is lower than the rated cutting torque, the adaptive boundary arbitration and control reconstruction module determines that the cutting process is in a stable state, and the feed rate correction factor is kept at 1.0.

[0009] Preferably, when the adaptive boundary arbitration and control reconfiguration module calculates the speed fine-tuning increment, it calculates the target spindle speed based on the chatter frequency and the number of tool teeth, uses the difference between the target spindle speed and the current spindle speed to obtain the speed fine-tuning increment, adjusts the spindle speed multiplier correction factor, so that the cutting frequency avoids the natural frequency of the machine tool structure and destroys the phase condition of the self-excited regeneration effect.

[0010] Preferably, the real-time interpolation rewriting and driving module uses a second-order low-pass shaping filter to smooth the feed rate correction factor, eliminate feed step size jumps and feed acceleration abrupt changes, and limit the delay of the adjusted feed step size and driving command to a single interpolation cycle.

[0011] Preferably, the adaptive boundary arbitration and control reconfiguration module also includes a tool wear evolution estimation submodule. During the steady-state operation of the spindle, the tool wear evolution estimation submodule continuously accumulates the ratio of the average instantaneous electromagnetic torque of the spindle to the output torque of the servo axis in the feed direction. When the ratio shows a monotonically increasing trend over time at the same cutting depth and the increase exceeds the preset proportional threshold, the threshold of the allowable cutting force limit of the tool is automatically lowered, so as to realize the dynamic contraction of the control boundary with the tool wear state.

[0012] Preferably, the preset critical threshold is 0.35; when the chatter energy entropy value is greater than or equal to 0.35 and the cutting load torque component is lower than the allowable torque limit corresponding to the allowable cutting force limit of the tool, the adaptive boundary arbitration and control reconfiguration module only adjusts the spindle speed ratio correction factor and synchronously links to maintain the constant single-tooth cutting thickness.

[0013] Preferably, when the cutting load torque component is higher than the rated cutting torque but lower than the allowable torque limit corresponding to the allowable cutting force limit of the tool, and the chatter energy entropy value is less than the preset critical threshold, the adaptive boundary arbitration and control reconfiguration module keeps the spindle speed ratio correction factor unchanged, and calculates the control coefficient according to the ratio of the allowable torque limit to the cutting load torque component, and fine-tunes the feed rate ratio correction factor.

[0014] An adaptive intelligent optimization and control method for CNC machining parameters, implemented through a CNC machining parameter adaptive intelligent optimization and control system, includes the following steps: Step S1: The dynamic signal acquisition and conversion module synchronously acquires the three-phase AC current signal of the spindle driver and the vibration acceleration signal of the tool holder physical contact, and converts the three-phase AC current signal and vibration acceleration signal into a digital time domain state vector. Step S2: The state feature decoupling and observation calculation module reconstructs the instantaneous electromagnetic torque of the spindle based on the digital time domain state vector using the stator current component and the flux linkage component, extracts the cutting load torque component by low-pass filtering, and extracts the high-frequency characteristic energy spectrum of the vibration acceleration signal by short-time Fourier transform, and calculates the chatter energy entropy value and chatter dominant frequency. Step S3: When the chatter energy entropy value is greater than or equal to the preset critical threshold, the adaptive boundary arbitration and control reconstruction module calculates the speed fine-tuning increment based on the chatter main frequency, the number of tool teeth and the phase locking order, generates the spindle speed multiplier correction factor, and collaboratively generates the feed rate multiplier correction factor. Step S4: Within the current interpolation cycle of the CNC system, the real-time interpolation rewriting and drive module injects the smoothed feed rate correction factor and spindle speed correction factor into the annular buffer of the CNC interpolator, and rewrites the feed step size and drive command for the next interpolation cycle.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In a CNC machining parameter adaptive intelligent optimization and control, by extracting the cutting load torque component and chatter energy entropy value respectively, it is possible to distinguish between normal load fluctuations and self-excited chatter caused by changes in cutting allowance, and avoid misjudging the increase in cutting allowance as chatter or overload. This can reduce unnecessary speed reduction operations and maintain machining efficiency while ensuring the safety of the cutting process.

[0016] 2. When chatter is detected, the spindle speed is finely adjusted according to the main frequency of chatter to make the cutting frequency avoid the natural frequency of the machine tool structure, thereby destroying the phase condition required for the formation of the self-excited regeneration effect and restoring the cutting process to stability. At the same time, the feed rate is adjusted synchronously with the spindle speed, which can keep the single tooth cutting thickness within a reasonable range, avoid tool slippage, squeezing and severe friction due to reducing the feed rate alone, reduce tool flank wear, and reduce the risk of workpiece surface burn.

[0017] 3. By directly writing the feed rate correction factor and spindle speed correction factor into the annular buffer of the CNC interpolator, the parameter adjustment can be completed within the interpolation cycle, shortening the response time of the control command and avoiding sudden changes in servo axis acceleration caused by commands spanning multiple interpolation cycles. Through feedforward torque compensation, the servo following lag and contour trajectory tracking deviation generated during the rate adjustment process can also be reduced, thereby improving the motion smoothness and trajectory control accuracy of the CNC machining process. Attached Figure Description

[0018] Figure 1 This is a flowchart of the adaptive optimization steps for processing parameters in this invention; Figure 2 This is a structural diagram of the control system modules and data elements of the present invention.

[0019] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0021] An adaptive intelligent optimization and control system for CNC machining parameters, the system comprising: The dynamic signal acquisition and conversion module is used to synchronously acquire the three-phase AC current signal of the spindle drive and the vibration acceleration signal of the tool holder physical contact, and convert the three-phase AC current signal and vibration acceleration signal into a digital time domain state vector. The state feature decoupling and observation calculation module is used to reconstruct the instantaneous electromagnetic torque of the spindle based on the stator current component and flux linkage component from the digital time domain state vector, extract the cutting load torque component through low-pass filtering, and extract the high-frequency characteristic energy spectrum of the vibration acceleration signal through short-time Fourier transform to calculate the chatter energy entropy value and chatter frequency. The adaptive boundary arbitration and control reconfiguration module is used to calculate the speed fine-tuning increment based on the chatter frequency, the number of tool teeth and the phase locking order when the chatter energy entropy value is greater than or equal to the preset critical threshold, generate the spindle speed multiplier correction factor, and collaboratively generate the feed rate multiplier correction factor. The real-time interpolation rewrite and drive module is used to inject the smoothed feed rate correction factor and spindle speed correction factor into the annular buffer of the CNC interpolator within the current interpolation cycle of the CNC system, and rewrite the feed step size and drive command for the next interpolation cycle.

[0022] Preferably, the sampling frequency of the dynamic signal acquisition and conversion module is set to 10kHz, and the acquisition timing of the three-phase AC current signal and the vibration acceleration signal is triggered and synchronized by the hardware timer interrupt signal of the CNC interpolator, so that the three-phase AC current signal and the vibration acceleration signal are aligned at the microsecond level on the time axis; when the state feature decoupling and observation calculation module performs low-pass filtering on the instantaneous electromagnetic torque of the spindle, the cutoff frequency of the low-pass filter is set to 50Hz.

[0023] Preferably, the state feature decoupling and observation calculation module reconstructs the instantaneous electromagnetic torque of the spindle using the number of pole pairs, flux linkage component, and stator current component after Park transformation of the spindle motor. After reconstruction, the system's no-load loss torque and acceleration inertial torque are deducted to obtain the cutting load torque component that reflects the low-frequency macroscopic cutting resistance.

[0024] Preferably, the state feature decoupling and observation calculation module extracts the short-time spectral energy density of the vibration acceleration signal in the frequency band of 100Hz to 2500Hz, and calculates the flutter energy entropy value using the normalized power spectral density distribution; when the flutter energy entropy value is less than the preset critical threshold and the cutting load torque component is lower than the rated cutting torque, the adaptive boundary arbitration and control reconstruction module determines that the cutting process is in a stable state, and the feed rate correction factor is kept at 1.0.

[0025] Preferably, when the adaptive boundary arbitration and control reconfiguration module calculates the speed fine-tuning increment, it calculates the target spindle speed based on the chatter frequency and the number of tool teeth, uses the difference between the target spindle speed and the current spindle speed to obtain the speed fine-tuning increment, adjusts the spindle speed multiplier correction factor, so that the cutting frequency avoids the natural frequency of the machine tool structure and destroys the phase condition of the self-excited regeneration effect.

[0026] Preferably, the real-time interpolation rewriting and driving module uses a second-order low-pass shaping filter to smooth the feed rate correction factor, eliminate feed step size jumps and feed acceleration abrupt changes, and limit the delay of the adjusted feed step size and driving command to a single interpolation cycle.

[0027] Preferably, the adaptive boundary arbitration and control reconfiguration module also includes a tool wear evolution estimation submodule. During the steady-state operation of the spindle, the tool wear evolution estimation submodule continuously accumulates the ratio of the average instantaneous electromagnetic torque of the spindle to the output torque of the servo axis in the feed direction. When the ratio shows a monotonically increasing trend over time at the same cutting depth and the increase exceeds the preset proportional threshold, the threshold of the allowable cutting force limit of the tool is automatically lowered, so as to realize the dynamic contraction of the control boundary with the tool wear state.

[0028] Preferably, the preset critical threshold is 0.35; when the chatter energy entropy value is greater than or equal to 0.35 and the cutting load torque component is lower than the allowable torque limit corresponding to the allowable cutting force limit of the tool, the adaptive boundary arbitration and control reconfiguration module only adjusts the spindle speed ratio correction factor and synchronously links to maintain the constant single-tooth cutting thickness.

[0029] Preferably, when the cutting load torque component is higher than the rated cutting torque but lower than the allowable torque limit corresponding to the allowable cutting force limit of the tool, and the chatter energy entropy value is less than the preset critical threshold, the adaptive boundary arbitration and control reconfiguration module keeps the spindle speed ratio correction factor unchanged, and calculates the control coefficient according to the ratio of the allowable torque limit to the cutting load torque component, and fine-tunes the feed rate ratio correction factor.

[0030] An adaptive intelligent optimization and control method for CNC machining parameters, implemented through a CNC machining parameter adaptive intelligent optimization and control system, includes the following steps: Step S1: The dynamic signal acquisition and conversion module synchronously acquires the three-phase AC current signal of the spindle driver and the vibration acceleration signal of the tool holder physical contact, and converts the three-phase AC current signal and vibration acceleration signal into a digital time domain state vector. Step S2: The state feature decoupling and observation calculation module reconstructs the instantaneous electromagnetic torque of the spindle based on the digital time domain state vector using the stator current component and the flux linkage component, extracts the cutting load torque component by low-pass filtering, and extracts the high-frequency characteristic energy spectrum of the vibration acceleration signal by short-time Fourier transform, and calculates the chatter energy entropy value and chatter dominant frequency. Step S3: When the chatter energy entropy value is greater than or equal to the preset critical threshold, the adaptive boundary arbitration and control reconstruction module calculates the speed fine-tuning increment based on the chatter main frequency, the number of tool teeth and the phase locking order, generates the spindle speed multiplier correction factor, and collaboratively generates the feed rate multiplier correction factor. Step S4: Within the current interpolation cycle of the CNC system, the real-time interpolation rewriting and drive module injects the smoothed feed rate correction factor and spindle speed correction factor into the annular buffer of the CNC interpolator, and rewrites the feed step size and drive command for the next interpolation cycle.

[0031] Example 1: This example uses a vertical five-axis CNC machining center to cut a titanium alloy TC4 workpiece. A 12mm diameter carbide end mill with 4 teeth is used to mill the sidewall of a steep curved surface. The constant spindle speed command of the CNC system is set to 3000 rpm, and the commanded feed rate is... Set to 600mm / min, equivalent to 0.01m / s; the bottom interpolation cycle of the CNC interpolator is set to 1ms; the servo motor and transmission chain's converted moment of inertia... The lead screw drive pitch ratio is 0.0015 kg·m². With a value of 0.00318 m / rad, the physical contact of the tool post is selected at a position on the tool post that is rigidly connected to the tool mounting structure and can directly transmit tool vibration. The dynamic signal acquisition and conversion module simultaneously acquires the three-phase AC current signal of the spindle driver and the vibration acceleration signal of the physical contact of the tool post at a sampling frequency of 10 kHz. The hardware timer interrupt signal of the CNC interpolator synchronously triggers the acquisition of the two signals, so that the three-phase AC current signal and the vibration acceleration signal are aligned at the microsecond level on the time axis and converted into a digital time domain state vector.

[0032] When the milling cutter enters the region of abrupt change in surface allowance, the cutting depth changes abruptly from 2.0 mm to 4.5 mm. One interpolation cycle, This indicates the current interpolation cycle number. The state feature decoupling and observation calculation module obtains the stator current after Park transformation of the spindle current. Axis current components It is 12.5A, stator Axis current components It is 2.1A, combined with the number of pole pairs of the spindle motor. , Axial flux component and Axial flux component According to the formula for reconstructing the instantaneous electromagnetic torque of the spindle: The instantaneous electromagnetic torque of the spindle was calculated. It is 16.56 N·m, where, The instantaneous electromagnetic torque of the main spindle. Number of pole pairs of the spindle motor; and They are respectively Shaft flux components and Axial flux linkage component, and These are the stators after the Park transformation. Axis current components and The shaft current component is determined by a stator flux linkage observer built into the spindle driver, which consists of a high-precision voltage model and a current model. During initialization, the stator resistance and inductance parameters specified on the motor nameplate are imported, and during operation, these parameters are combined with real-time acquired voltage and current signals to calculate the current component online. The axial flux linkage component is 0.45Wb and The shaft flux component is 0.05Wb, so that the flux component used for torque reconstruction corresponds to the current electromagnetic operating state of the spindle motor.

[0033] The state characteristic decoupling and observation calculation module applies a low-pass filter with a cutoff frequency of 50Hz to the reconstructed instantaneous electromagnetic torque of the spindle, and then subtracts the system's no-load loss torque and acceleration inertia torque. During each interpolation cycle, the spindle speed is maintained at 3000 rpm, and the acceleration inertial torque is 0 N·m. After deducting the no-load loss torque of 1.20 N·m and the acceleration inertial torque, the cutting load torque component of 15.36 N·m is obtained. When the cutoff frequency is set to 50 Hz, the low-frequency average resistance generated by the changes in cutting depth and cutting allowance in the spindle torque signal enters the cutting load torque component. The high-frequency alternating fluctuations, including the 200 Hz tooth passing frequency, and the self-excited chatter energy are observed by the high-frequency characteristic energy spectrum of the vibration acceleration signal. The observation frequency band of the spindle torque signal is limited to below 50 Hz, which can filter out the high-frequency harmonics of the motor rotor and the high-frequency dynamic interference generated by the tooth entry and exit, so that the low-frequency load formed by the change in cutting allowance and the high-frequency vibration formed by self-excited chatter enter the corresponding observation channels respectively.

[0034] Meanwhile, the state feature decoupling and observation calculation module performs short-time Fourier transform on the vibration acceleration signal within a 20ms time window to extract the short-time spectral energy density in the 100Hz to 2500Hz frequency band. The normalized power spectral density distribution is obtained according to the following formula. : Then calculate the flutter energy entropy value according to the following formula. : Calculated flutter energy entropy value It is 0.21, where, The flutter energy entropy value, For a normalized power spectral density distribution, For short-time spectral energy density, As an integral variable, its frequency range is from 100Hz to 2500Hz. The short-time spectral energy density is obtained from the high-frequency vibration response after removing the spindle rotation fundamental frequency. Under stable cutting conditions, there is no strong excitation source in the high-frequency band, the background signal has a low-energy smooth distribution, and the chatter energy entropy value is maintained at a low level. When self-excited cutting chatter is generated, the nonlinear impact between the tool and the workpiece generates broadband high-order harmonics and sideband modulation. The energy diffuses at multiple characteristic frequency points in the 100Hz to 2500Hz frequency band, the distribution state of the high-frequency characteristic energy spectrum changes, and the chatter energy entropy value increases accordingly.

[0035] The adaptive boundary arbitration and control reconfiguration module compares the chatter energy entropy value of 0.21 with the preset critical threshold of 0.35, determining that the current instantaneous increase in the spindle's electromagnetic torque is caused by an increase in the cutting allowance and does not generate self-excited cutting chatter. The rated cutting torque is pre-calibrated according to the rated torque that the spindle can continuously output at the current speed. The allowable cutting force limit of the tool is converted into the corresponding allowable torque limit according to the effective radius of the current tool. In this embodiment, the allowable torque limit is 18.00 N·m, and this allowable torque limit is used as the control boundary. The current cutting load torque component of 15.36 N·m is higher than the rated cutting torque but lower than the allowable torque limit. The adaptive boundary arbitration and control reconfiguration module maintains the spindle speed multiplier correction factor. The value remains constant at 1, and the control coefficient is calculated based on the ratio of the allowable torque limit to the cutting load torque component: ,in, This is the feed rate correction factor, the system output feed rate correction factor. The actual feed rate is adjusted from 600 mm / min to 597.6 mm / min to a value of 0.996. The ratio of the allowable torque limit to the cutting load torque component is used to characterize the current rated power safety reserve. When the cutting load torque component approaches the allowable torque limit, the system uses a rated safety margin coefficient of 0.85 to constrain the control coefficient, so that the feed rate is only slightly adjusted. While maintaining the cutting thickness and machining efficiency, this limits the cutting load from continuing to rise and exceeding the mechanical safety limit, and also avoids misjudging the increase in cutting allowance as self-excited cutting chatter and drastically reducing the feed rate.

[0036] In the During one interpolation cycle, the lateral structural stiffness of the machine tool weakens, and the short-time spectrum of the vibration acceleration signal exhibits an energy peak at 1250Hz. The calculated flutter energy entropy value... When the frequency rises to 0.58, exceeding the preset critical threshold of 0.35, the system determines that self-excited cutting chatter has occurred. The adaptive boundary arbitration and control reconfiguration module then initiates the spindle speed offset algorithm based on the chatter frequency. Number of teeth on the cutting tool Phase Locking Order The target spindle speed is calculated using the following formula: The target spindle speed was calculated. The speed is 3125 rpm, where, For the target spindle speed, For the flutter frequency, This refers to the number of teeth on the cutting tool. The phase-lock order is used, and the difference between the target spindle speed and the current spindle speed is the speed fine-tuning increment. ,in, For the fine-tuning increment of the spindle speed, the adaptive boundary arbitration and control reconfiguration module only uses the spindle speed multiplier correction factor as the active adjustment amount under this operating condition, and calculates the following: The feed rate correction factor is not used as an independent boundary adjustment amount, but is synchronously linked to the change of the spindle speed correction factor to 1.042, so as to maintain a constant single-tooth cutting thickness of the tool and avoid tool slippage, squeezing and wear caused by unidirectional reduction of feed rate. After the spindle speed is adjusted, the cutting frequency avoids the natural frequency of the machine tool structure, and the phase condition of the self-excited regeneration effect changes accordingly.

[0037] The feed rate correction factor is smoothed by a second-order low-pass shaping filter within a 1ms interpolation period to obtain the feed rate change rate: ,in, For the feed rate multiplier change rate, the feedforward servo hysteresis compensation submodule calculates the feedforward torque compensation amount according to the following formula: Substituting the parameters of this embodiment, we get: ,in, This is the feedforward torque compensation amount. Calculate the moment of inertia of the servo motor and its transmission chain. For commanded feed rate, The screw drive pitch ratio is used to compensate for the servo follow lag caused by the multiplier adjustment. The feedforward torque compensation is directly superimposed on the torque loop input of the servo driver.

[0038] During the transmission of the feedforward torque compensation, the system writes the calculated feedforward torque compensation into the physical mapping address of the feedforward torque register reserved in the servo driver through the industrial real-time Ethernet interface of the CNC bus hardware layer. The digital signal processor inside the servo driver reads the register in each servo control cycle. In this embodiment, the servo control cycle is 125μs. The read feedforward torque compensation is added to the torque commands output by the position loop and speed loop in the current loop control stage to complete the real-time injection of the feedforward torque.

[0039] Real-time interpolation rewriting and driver module in the first Within each interpolation cycle, the smoothed feed rate correction factor will be applied. and spindle speed correction factor The circular buffer of the CNC interpolator is injected to rewrite the feed step size and drive command of the next interpolation cycle. The state feature decoupling and observation calculation module uses a sliding time window for state calculation. The system continuously writes newly acquired data to a 20ms long circular memory data buffer at a sampling frequency of 10kHz. Every 1ms interpolation cycle, the window is updated using the latest stored sampled data, and a short-time Fourier transform is performed on the latest 20ms data block. The spectral entropy calculation delay is controlled within the calculation time range of a single interpolation cycle, with a calculation time of less than 0.1ms. Thus, while retaining the required spectral resolution of the 20ms data window, the state calculation and circular buffer command rewriting are completed within a single 1ms interpolation cycle.

[0040] After the rewritten instructions were injected into the annular buffer, the spindle speed smoothly transitioned to 3125 rpm within 12 ms, and the feed rate smoothly increased to 625.2 mm / min. The vibration acceleration signal and chatter energy entropy value were collected again 50 ms after the adjustment was completed. The self-excited cutting chatter was suppressed when the value dropped to 0.18, and the workpiece surface roughness Ra was controlled within 0.8 μm. The spindle motor driver was equipped with a high-frequency vector control loop with a dynamic response bandwidth greater than 300 Hz. The moment of inertia of the spindle rotor and tool system was 0.0085 kg·m², the short-time overload capacity of the electromagnetic torque reached 200%, and the theoretical acceleration response time was less than 8 ms. Therefore, the spindle speed adjustment of 125 rpm could be completed within 12 ms. After the above processing, the instantaneous electromagnetic torque of the low-frequency spindle and the energy entropy value of high-frequency chatter were used to characterize the cutting allowance load and the self-excited cutting chatter, respectively, and formed a digital time-domain state vector that could be used for control within the interpolation cycle. The system changed the phase condition of the self-excited regeneration effect while maintaining the single-tooth cutting thickness through phase-locked speed fine-tuning and feedforward torque compensation, so that the state calculation, magnification reconstruction and interpolation command rewriting were completed within the same control sequence.

[0041] Example 2: This example demonstrates a cutting experiment on a titanium alloy TC4 workpiece using a vertical five-axis CNC machining center. A 12mm diameter carbide end mill with 4 teeth was used to mill a steep curved surface. The CNC system's steady-state spindle speed was set to 3000 rpm, and the commanded feed rate was set to 600mm / min (equivalent to 0.01m / s). The bottom interpolation cycle was set to 1ms, and the servo motor and transmission chain's equivalent rotational inertia were calculated. The lead screw drive pitch ratio is 0.0015 kg·m². The measured value is 0.00318 m / rad. The test platform is equipped with a three-phase AC current sensor with a measurement range of ±50A and a resolution of 0.01A. A three-axis accelerometer with a measurement range of ±50g is installed at the physical contact of the tool holder. The hardware timer interrupt signal of the CNC interpolator synchronously triggers the two types of sensors at a sampling frequency of 10kHz, so that the three-phase AC current signal and the vibration acceleration signal are aligned at the microsecond level on the time axis and converted into a digital time domain state vector. This is used to test the observation accuracy of the decoupling and observation calculation module under interference conditions and the response of the control loop. Gaussian white noise with a signal-to-noise ratio of 22dB and 50Hz power frequency harmonic interference are superimposed on the original current signal and vibration acceleration signal.

[0042] The experiment included a sample group based on the present invention and three control groups. Tests were conducted under continuous operating conditions, including smooth cutting, sudden changes in cutting allowance, self-excited cutting chatter caused by weakened lateral stiffness, and tool wear evolution. The sample group of the present invention used 10kHz interrupted synchronous acquisition. The instantaneous electromagnetic torque of the spindle was reconstructed through the flux linkage component and the stator current component. After a 50Hz low-pass filter, the no-load loss torque and acceleration inertia torque were subtracted to obtain the cutting load torque component. Simultaneously, a short-time Fourier transform was performed on the vibration acceleration signal in the 100Hz to 2500Hz frequency band to calculate the chatter energy entropy. With a preset critical threshold of 0.35, when chatter is detected, a correction factor based on the spindle speed ratio is applied. As an active adjustment amount, and as a feed rate correction factor. The system adjusts in tandem with changes in spindle speed to maintain a constant single-tooth cutting thickness. Two scaling correction factors, after smoothing, are written into the annular buffer of the CNC interpolator. The feedforward servo lag compensation submodule synchronously calculates the feedforward torque compensation amount. And it is superimposed on the torque loop input of the servo driver.

[0043] Control group 1 uses single-threshold adaptive control, setting a single static threshold based solely on the total current amplitude; once the threshold is exceeded, the feed rate is reduced unidirectionally. Control group 2 uses chatter energy entropy value for chatter identification but does not perform spindle speed fine-tuning; when the chatter energy entropy value is greater than or equal to 0.35, the feed rate is reduced unidirectionally. Control group 3 simultaneously adjusts the spindle speed multiplier correction factor and the feed rate multiplier correction factor, but does not superimpose the feedforward torque compensation. The stator values ​​of each group are continuously recorded during the experiment. Axis current components Cutting load torque component, chatter energy entropy value Spindle speed correction factor Feed rate correction factor Feedforward torque compensation Servo axis contour tracking deviation and workpiece surface roughness Ra after machining.

[0044] During the stable cutting phase, the sample group of this invention corresponds to working condition 1. At this time, the stator... Axis current components The value is 6.2A, the cutting load torque component is 7.25 N·m, and the chatter energy entropy value is... The spindle speed correction factor is 0.12. and feed rate correction factor All are 1.000, feedforward torque compensation amount The torque is 0.000 N·m, the servo axis contour tracking deviation is 1.2 μm, the workpiece surface roughness Ra is 0.42 μm, and the stator of control group 1 is in the same stable cutting condition corresponding to working condition 2. Axis current components Both are 6.2A, with a cutting load torque component of 7.25 N·m and a chatter energy entropy value. The spindle speed correction factor is 0.12. and feed rate correction factor All are 1.000, feedforward torque compensation amount The servo axis profile tracking deviation is 1.2 μm, the workpiece surface roughness Ra is 0.43 μm, and under low cutting load and no chatter conditions, all magnification correction factors remain constant.

[0045] During the stage of increasing allowance as the cutting depth abruptly increases from 2.0 mm to 4.5 mm, the stator sample of this invention, corresponding to working condition 3, was synchronously acquired. Axis current components The torque is 12.5A. After reconstructing the instantaneous electromagnetic torque of the spindle and performing low-pass filtering and torque subtraction, the cutting load torque component of 15.36 N·m is obtained; the chatter energy entropy value is calculated simultaneously. The value is 0.21, which is lower than the preset critical threshold of 0.35. Based on this, the adaptive boundary arbitration and control reconfiguration module maintains the spindle speed ratio correction factor. The value is set to 1.000, and the feed rate correction factor is adjusted accordingly. Adjusted to 0.996, the feedforward servo hysteresis compensation submodule outputs a feedforward torque compensation of 0.002 N·m. After adjustment, the servo axis contour tracking deviation was 1.5μm, the workpiece surface roughness Ra was 0.58μm, and the processing efficiency remained at 99.6%.

[0046] Control group 1, under the same margin mutation conditions corresponding to operating condition 4, its stator Axis current components The current is 12.5A, the cutting load torque component is 15.36 N·m, and the chatter energy entropy value is... The value is 0.21. Since this group only judges based on the total current amplitude, the system will adjust the feed rate correction factor. Reduced to 0.650, spindle speed ratio correction factor Keep it at 1.000, feedforward torque compensation amount With a feed rate of 0.000 N·m, the machining efficiency decreased by 35.0% after the feed rate was significantly reduced, the servo axis contour tracking deviation increased to 8.6 μm, and the workpiece surface roughness Ra increased to 1.25 μm. When judging based solely on the current amplitude as a single threshold, the low-frequency load change caused by the increase in the cutting allowance would trigger a speed reduction action. The sample of this invention, however, combines the cutting load torque component and the chatter energy entropy value for judgment, and only makes a small adjustment to the feed rate.

[0047] When the lateral stiffness decreases and 1250Hz self-excited cutting chatter occurs, the sample group of this invention corresponds to working condition 5. At this time, the stator... Axis current components The value is 13.8A, the cutting load torque component is 16.12 N·m, and the chatter energy entropy value is... The value rises to 0.58, exceeding the preset critical threshold of 0.35. The adaptive boundary arbitration and control reconfiguration module calculates the target spindle speed based on the chatter frequency, the number of tool teeth, and the phase lock order, and then corrects it using the spindle speed multiplier. As an active adjustment, it is adjusted to 1.042; feed rate correction factor. The linkage was subsequently adjusted to 1.042 to maintain a constant single-tooth cutting thickness. The feedforward servo hysteresis compensation submodule calculated a feedforward torque compensation of 0.217 N·m based on the scaling factor change. After the above treatment, the chatter was suppressed within 12ms, the servo axis profile tracking deviation was 2.1μm, and the workpiece surface roughness Ra was 0.76μm.

[0048] Control group 2, under the same flutter condition corresponding to operating condition 6, has a stator Axis current components The value is 13.8A, the cutting load torque component is 16.12 N·m, and the chatter energy entropy value is... The value is 0.58. This group does not adjust the spindle speed; the spindle speed multiplier correction factor is [value missing]. Keep it at 1.000, only adjust the feed rate correction factor. Reduced to 0.700, feedforward torque compensation amount With a feed rate of 0.000 N·m, after the feed rate is reduced in one direction, the feed per tooth is lower than the radius of the tool cutting edge, the friction between the tool and the workpiece and the wear of the back face increase, the servo axis profile tracking deviation is 6.4 μm, and the workpiece surface roughness Ra increases to 2.45 μm.

[0049] Control group 3, under the same flutter condition corresponding to operating condition 7, has a stator Axis current components The value is 13.8A, the cutting load torque component is 16.12 N·m, and the chatter energy entropy value is... The spindle speed ratio correction factor is 0.58. and feed rate correction factor All were adjusted to 1.042, since this group did not have feedforward torque compensation added. The servo tracking lag generated during the magnification adjustment process was 0.000 N·m, which caused the contour tracking deviation to expand to 18.4 μm. The surface roughness Ra of the workpiece was 1.12 μm. Under the same magnification adjustment conditions, the sample group of the present invention controlled the contour tracking deviation to 2.1 μm. The above difference was caused by the feedforward torque compensation amount compensating for the servo lag caused by the magnification change in real time.

[0050] After the chatter is suppressed and the cutting process enters a stable state, the sample group of this invention corresponds to working condition 8. At this time, the stator... Axis current components The voltage drops back to 11.2A, the cutting load torque component is 13.68 N·m, and the chatter energy entropy value is... Reduced to 0.18; Spindle speed ratio correction factor and feed rate correction factor All remain at 1.042, and the feedforward torque compensation amount remains stable after the ratio is maintained. Returning to 0.000 N·m, the servo axis profile tracking deviation under this condition is 1.4 μm, and the workpiece surface roughness Ra is 0.48 μm.

[0051] During the tool wear evolution stage, the stator sample of this invention, corresponding to working condition 9, was collected. Axis current components The value is 14.2A, the cutting load torque component is 16.85 N·m, and the chatter energy entropy value is... The value is 0.24, which does not exceed the preset critical threshold. The tool wear evolution estimation submodule continuously accumulates the ratio of the average instantaneous electromagnetic torque of the spindle to the output torque of the servo axis in the feed direction. When this ratio monotonically increases with time at the same depth of cut and the increase exceeds 20%, the system lowers the threshold of the allowable cutting force limit of the tool and updates the corresponding allowable torque limit accordingly. Under this condition, the spindle speed multiplier correction factor... Keep the feed rate correction factor at 1.000. Adjusted to 0.920, feedforward torque compensation amount The torque is 0.015 N·m, the servo axis profile tracking deviation is 1.8 μm, and the workpiece surface roughness Ra is 0.62 μm.

[0052] Control group 1, under tool wear conditions corresponding to working condition 10, its stator Axis current components The value is 14.2A, the cutting load torque component is 16.85 N·m, and the chatter energy entropy value is... The spindle speed ratio correction factor is 0.24. Keep the feed rate correction factor at 1.000. Reduced to 0.550, feedforward torque compensation amount The allowable cutting force limit of the tool was 0.000 N·m. Since the threshold of the allowable cutting force limit of the tool was not adjusted according to the tool wear condition, the servo axis profile tracking deviation increased to 12.3 μm and the workpiece surface roughness Ra increased to 1.85 μm.

[0053] To determine the preset critical threshold, gradient tests were conducted on the chatter energy entropy value within the range of 0.15 to 0.55. When the threshold was below 0.25, vibrations caused by changes in the cutting allowance would trigger chatter alarms and speed reduction actions. When the threshold was above 0.45, self-excited cutting chatter could not be triggered and controlled in time in the initial stage, and chatter marks appeared on the workpiece surface. The theoretical upper limit of the normalized energy entropy under completely uniform white noise was 1.0, and the theoretical lower limit under an ideal single-frequency sinusoidal signal was 0. When the machine tool was in a cutting state without obvious chatter, the high-frequency vibration spectrum only contained broadband background noise, and the energy entropy baseline was between 0.15 and 0.25. As the chatter energy concentrated in a specific high-frequency band, the high-frequency spectrum distribution changed, and the chatter energy entropy value increased accordingly. In the cutting test, when the chatter energy entropy value reached 0.35, the machine tool vibration amplitude was in a critical state of transition from weak disturbance to self-excited instability. Therefore, 0.35 was set as the preset critical threshold.

[0054] In the aforementioned continuous operating conditions, the cutting load torque component is used to characterize the changes in cutting allowance and cutting resistance, while the chatter energy entropy value is used to identify high-frequency self-excited cutting chatter. The spindle speed multiplier correction factor and the feed rate multiplier correction factor are adjusted according to the two types of state variables, and the feedforward torque compensation amount is written into the servo drive torque loop as the multiplier changes. It can be seen from the contour tracking deviation and workpiece surface roughness of each operating condition that the separate observation of cutting load and chatter state, the linkage adjustment of spindle speed and feed rate, and the feedforward torque compensation within the interpolation cycle can maintain the continuity of the machining process under different cutting conditions.

[0055] Example 3: In this example, titanium alloy TC4 parts are cut on a vertical five-axis CNC machining center. The dynamic signal acquisition and conversion module is triggered by the hardware timer interrupt signal of the CNC interpolator. It synchronously acquires the three-phase AC current signal of the spindle driver and the vibration acceleration signal of the tool holder physical contact at a sampling frequency of 10kHz, and converts the two signals into digital time domain state vectors.

[0056] The state feature decoupling and observation calculation module reads the digital time-domain state vector and calculates it based on the number of pole pairs of the spindle motor. Shaft flux component, Shaft flux linkage components and stator after Park transformation Shaft current components and stator The shaft current component is used to reconstruct the instantaneous electromagnetic torque of the spindle. After low-pass filtering the reconstruction result with a cutoff frequency of 50Hz, the no-load loss torque and acceleration inertia torque of the system are subtracted to obtain the cutting load torque component. The acceleration inertia torque is determined based on the spindle acceleration and the equivalent rotational inertia of the spindle rotor and tool system.

[0057] For the vibration acceleration signals acquired simultaneously, the state feature decoupling and observation calculation module extracts the short-time spectral energy density in the 100Hz to 2500Hz frequency band and calculates the flutter energy entropy value according to the normalized power spectral density distribution. The adaptive boundary arbitration and control reconstruction module executes control according to the comparison result of the flutter energy entropy value and the preset critical threshold of 0.35. When the flutter energy entropy value is less than 0.35 and the cutting load torque component is lower than the rated cutting torque, the feed rate correction factor is kept at 1.

[0058] When the cutting load torque component increases but the chatter energy entropy value is still below 0.35, the adaptive boundary arbitration and control reconfiguration module keeps the spindle speed ratio correction factor unchanged and calculates the feed rate ratio correction factor based on the ratio of the allowable torque limit to the cutting load torque component. During the calculation, a rated transmission chain thermal safety attenuation coefficient of 0.85 is introduced to reserve 15% of the rated power thermal reserve, thereby reducing the impact of torque constant drift caused by the temperature rise of the spindle motor and servo motor windings on the continuous cutting process.

[0059] When the chatter energy entropy value is greater than or equal to 0.35, the adaptive boundary arbitration and control reconfiguration module determines that cutting chatter has occurred, and calculates the speed fine-tuning increment based on the chatter main frequency, the current spindle speed, the number of tool teeth and the phase lock order, and adjusts the spindle speed multiplier correction factor to make the cutting frequency avoid the natural frequency of the machine tool structure. The feed rate multiplier correction factor is synchronously linked with the spindle speed multiplier correction factor to maintain a constant single-tooth cutting thickness.

[0060] The phase-locking order is automatically selected by the system. After detecting the flutter frequency, the system establishes a set of candidate integer orders, calculates the target spindle speed corresponding to each candidate integer order, and uses the absolute difference between the target spindle speed and the current spindle speed as the selection criterion. The candidate integer with the smallest absolute difference is determined as the phase-locking order. When the absolute difference between two adjacent integers is equal, the integer with the larger value is selected so that the calculated target spindle speed is higher than the current spindle speed, thus avoiding the low-speed vibration zone.

[0061] The real-time interpolation rewriting and driving module uses a second-order low-pass shaping filter to smooth the feed rate correction factor in order to limit the step change of feed acceleration. The circular buffer of the CNC interpolator adopts a shared memory data structure in the form of a fixed-length circular queue, and sets four data fields: interpolation sequence number, target position coordinates of each axis, feed rate multiplier, and spindle speed multiplier.

[0062] Before the end of the current interpolation cycle, the real-time interpolation rewriting and drive module obtains the hardware interpolation interrupt handle through the internal high-speed communication bus. In the real-time interrupt service routine, it locates the write pointer address pointing to the next interpolation cycle in the circular buffer and reads the feed rate correction factor after processing by the second-order low-pass shaping filter. This module writes the feed rate correction factor and the spindle speed correction factor into the corresponding ratio data field, overwriting the ratio field in the original timer instruction. After entering the next interpolation cycle, the CNC interpolator reads the updated ratio field, multiplies it by the original feed step size, and regenerates the underlying drive pulse or digital control instruction, thereby completing the rewriting of the feed step size and drive instruction for the next interpolation cycle.

[0063] The feedforward servo lag compensation submodule in the adaptive boundary arbitration and control reconfiguration module calculates the feedforward torque compensation amount based on the rate of change of the feed rate correction factor, the converted moment of inertia of the servo motor and transmission chain, the commanded feed rate, and the lead screw pitch ratio. This compensation amount is directly superimposed on the torque loop input of the servo driver to compensate for the servo following lag generated during the rate adjustment process.

[0064] During steady-state operation of the spindle, the tool wear evolution estimation submodule continuously accumulates the ratio of the average instantaneous electromagnetic torque of the spindle to the output torque of the feed direction servo axis. When this ratio shows a monotonically increasing trend over time at the same depth of cut, and the increase exceeds 20%, the system lowers the threshold of the allowable cutting force limit of the tool, so that the control boundary shrinks with the tool wear state.

[0065] The same cutting depth is determined by the stability of the average instantaneous electromagnetic torque of the spindle. When the standard deviation of the instantaneous electromagnetic torque of the spindle is less than 0.05 N·m in 50 consecutive interpolation cycles, and the spindle speed and feed rate are both in the steady-state maintenance range, the system determines the current cutting process as a stable layer depth cutting state, and extracts the average instantaneous electromagnetic torque of the spindle in this period as the reference data point. If the difference between the reference data points of two adjacent stable periods is less than 5%, the two stable periods are determined to be in the same cutting depth. On this basis, the ratio of the average instantaneous electromagnetic torque of the spindle to the output torque of the servo axis in the feed direction is accumulated to evaluate the tool wear trend.

[0066] Example 4: This example combines Figures 1 to 2 This paper describes an adaptive intelligent optimization and control system and method for CNC machining parameters, such as... Figure 1As shown, in step S1, the dynamic signal acquisition and conversion module synchronously acquires the three-phase AC current signal of the spindle driver and the vibration acceleration signal of the tool holder physical contact, converting the three-phase AC current signal and vibration acceleration signal into a digital time-domain state vector. In step S2, the state feature decoupling and observation calculation module reconstructs the instantaneous electromagnetic torque of the spindle based on the digital time-domain state vector using the stator current component and the flux linkage component, extracts the cutting load torque component using low-pass filtering, and extracts the high-frequency characteristic energy spectrum of the vibration acceleration signal through short-time Fourier transform, calculating the chatter energy entropy value and the chatter main... In step S3, when the chatter energy entropy value is greater than or equal to the preset critical threshold, the adaptive boundary arbitration and control reconstruction module calculates the speed fine-tuning increment based on the chatter main frequency, the number of tool teeth, and the phase locking order, generates the spindle speed multiplier correction factor, and collaboratively generates the feed rate multiplier correction factor. In step S4, within the current interpolation cycle of the CNC system, the real-time interpolation rewriting and drive module injects the smoothed feed rate multiplier correction factor and the spindle speed multiplier correction factor into the annular buffer of the CNC interpolator, and rewrites the feed step size and drive command for the next interpolation cycle.

[0067] like Figure 2 As shown, the dynamic signal acquisition and conversion module synchronously acquires three-phase AC current signals and vibration acceleration signals and converts them into digital time-domain state vectors. The state feature decoupling and observation calculation module reconstructs the instantaneous electromagnetic torque of the spindle using the digital time-domain state vector, extracts the cutting load torque component, and calculates the chatter energy entropy value. The adaptive boundary arbitration and control reconstruction module combines the chatter main frequency and preset critical threshold to calculate and generate the spindle speed ratio correction factor. The real-time interpolation rewriting and drive module calculates the feedforward torque compensation based on the spindle speed ratio correction factor and rewrites the feed step size within the annular buffer. Finally, the methods converge to realize the adaptive intelligent optimization and control method of CNC machining parameters.

[0068] Example 5: This example is implemented during the deployment phase of a vertical five-axis CNC machining center cutting a titanium alloy TC4 workpiece. The dynamic signal acquisition and conversion module reads the hardware timer interrupt signal cycle of the CNC interpolator and synchronously acquires the three-phase AC current signal of the spindle driver and the vibration acceleration signal at the physical contact of the tool holder at a sampling frequency of 10kHz. Before the system accesses the field environmental data, it performs signal preprocessing on the acquired raw current signal and vibration acceleration signal, retaining the digital time-domain state vector used to characterize the machine tool's operating status.

[0069] The state feature decoupling and observation calculation module reads the digital time domain state vector and performs offline calibration. During the spindle's no-load steady-state operation, the module continuously collects the stator current components within a 20ms time window, calculates and stores the initial baseline of the system's no-load loss torque, and sets the analysis frequency band of the short-time Fourier transform to 100Hz to 2500Hz.

[0070] Before the system is put into operation, the adaptive boundary arbitration and control reconfiguration module calls the machine tool self-excited vibration stability boundary equation and the initial value of the allowable cutting force limit of the tool. During the steady-state operation of the spindle, the tool wear evolution estimation submodule continuously accumulates the ratio of the average instantaneous electromagnetic torque of the spindle to the output torque of the servo axis in the feed direction. When this ratio shows a monotonically increasing trend over time at the same cutting depth and the increase exceeds 20%, the system lowers the threshold of the allowable cutting force limit of the tool, so that the control boundary shrinks with the tool wear state.

[0071] The real-time interpolation rewrite and drive module injects the smoothed feed rate correction factor and spindle speed correction factor into the annular buffer of the CNC interpolator, and rewrites the feed step size and drive command for the next interpolation cycle.

[0072] Example 6: This example is run during the process debugging stage of cutting titanium alloy TC4 parts on a vertical five-axis CNC machining center. The dynamic signal acquisition and conversion module reads the hardware timer interrupt signal cycle of the CNC interpolator and synchronously acquires the three-phase AC current signal of the spindle driver and the vibration acceleration signal at the physical contact of the tool holder at a sampling frequency of 10kHz. Before the system accesses the field environmental data, it first executes the configuration confirmation program authorized by the operator on site, and then performs desensitization processing on the acquired raw current signal and vibration acceleration signal based on hash mapping, filters and isolates redundant metadata related to the operator's identity, and retains the digital time domain state vector used to characterize the machine tool's operating status.

[0073] The state feature decoupling and observation calculation module reads the digital time domain state vector and performs offline calibration. During the spindle's no-load steady-state operation, the module continuously collects the stator current components within a 20ms time window, calculates and stores the initial baseline of the system's no-load loss torque, and sets the analysis frequency band of the short-time Fourier transform to 100Hz to 2500Hz.

[0074] Before the system is put into operation, the adaptive boundary arbitration and control reconfiguration module calls the machine tool self-excited vibration stability boundary equation and the initial value of the allowable cutting force limit of the tool. During the steady-state operation of the spindle, the tool wear evolution estimation submodule continuously accumulates the ratio of the average instantaneous electromagnetic torque of the spindle to the output torque of the servo axis in the feed direction. When this ratio shows a monotonically increasing trend over time at the same cutting depth and the increase exceeds 20%, the system lowers the threshold of the allowable cutting force limit of the tool, so that the control boundary shrinks with the tool wear state.

[0075] The real-time interpolation rewrite and drive module injects the smoothed feed rate correction factor and spindle speed correction factor into the annular buffer of the CNC interpolator, and rewrites the feed step size and drive command for the next interpolation cycle.

[0076] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A CNC machining parameter adaptive intelligent optimization and control system, characterized in that the system... include: The dynamic signal acquisition and conversion module is used to synchronously acquire the three-phase AC current signal of the spindle drive and the vibration acceleration signal of the tool holder physical contact, and convert the three-phase AC current signal and vibration acceleration signal into a digital time domain state vector. The state feature decoupling and observation calculation module is used to reconstruct the instantaneous electromagnetic torque of the spindle based on the stator current component and flux linkage component from the digital time domain state vector, extract the cutting load torque component through low-pass filtering, and extract the high-frequency characteristic energy spectrum of the vibration acceleration signal through short-time Fourier transform to calculate the chatter energy entropy value and chatter frequency. The adaptive boundary arbitration and control reconfiguration module is used to calculate the speed fine-tuning increment based on the chatter frequency, the number of tool teeth and the phase locking order when the chatter energy entropy value is greater than or equal to the preset critical threshold, generate the spindle speed multiplier correction factor, and collaboratively generate the feed rate multiplier correction factor. The real-time interpolation rewrite and drive module is used to inject the smoothed feed rate correction factor and spindle speed correction factor into the annular buffer of the CNC interpolator within the current interpolation cycle of the CNC system, and rewrite the feed step size and drive command for the next interpolation cycle.

2. The adaptive intelligent optimization and control system for CNC machining parameters according to claim 1, characterized in that, The sampling frequency of the dynamic signal acquisition and conversion module is set to 10kHz, and the acquisition timing of the three-phase AC current signal and the vibration acceleration signal is triggered and synchronized by the hardware timer interrupt signal of the CNC interpolator, so that the three-phase AC current signal and the vibration acceleration signal are aligned at the microsecond level on the time axis; when the state feature decoupling and observation calculation module performs low-pass filtering on the instantaneous electromagnetic torque of the spindle, the cutoff frequency of the low-pass filter is set to 50Hz.

3. The adaptive intelligent optimization and control system for CNC machining parameters according to claim 1, characterized in that, The state characteristic decoupling and observation calculation module reconstructs the instantaneous electromagnetic torque of the spindle using the number of pole pairs, flux linkage components, and stator current components after Park transformation of the spindle motor. After reconstructing, it deducts the no-load loss torque and acceleration inertial torque of the system and decouples to obtain the cutting load torque component that reflects the low-frequency macroscopic cutting resistance.

4. The adaptive intelligent optimization and control system for CNC machining parameters according to claim 1, characterized in that, The state feature decoupling and observation calculation module extracts the short-time spectral energy density of the vibration acceleration signal in the frequency band of 100Hz to 2500Hz, and calculates the flutter energy entropy value using the normalized power spectral density distribution. When the flutter energy entropy value is less than the preset critical threshold and the cutting load torque component is lower than the rated cutting torque, the adaptive boundary arbitration and control reconstruction module determines that the cutting process is in a stable state, and the feed rate correction factor is kept at 1.

0.

5. The adaptive intelligent optimization and control system for CNC machining parameters according to claim 1, characterized in that, When the adaptive boundary arbitration and control reconfiguration module calculates the speed fine-tuning increment, it calculates the target spindle speed based on the chatter frequency and the number of tool teeth, uses the difference between the target spindle speed and the current spindle speed to derive the speed fine-tuning increment, adjusts the spindle speed multiplier correction factor to make the cutting frequency avoid the machine tool structure's natural frequency, and destroys the phase condition of the self-excited regeneration effect.

6. The adaptive intelligent optimization and control system for CNC machining parameters according to claim 1, characterized in that, The real-time interpolation rewriting and driving module uses a second-order low-pass shaping filter to smooth the feed rate correction factor, eliminate feed step size jumps and feed acceleration abrupt changes, and limit the delay of the adjusted feed step size and driving command to a single interpolation cycle.

7. The adaptive intelligent optimization and control system for CNC machining parameters according to claim 1, characterized in that, The adaptive boundary arbitration and control reconfiguration module also includes a tool wear evolution estimation submodule. During the steady-state operation of the spindle, the tool wear evolution estimation submodule continuously accumulates the ratio of the average instantaneous electromagnetic torque of the spindle to the output torque of the servo axis in the feed direction. When the ratio shows a monotonically increasing trend over time at the same cutting depth and the increase exceeds the preset proportional threshold, the threshold of the allowable cutting force limit of the tool is automatically lowered, so as to realize the dynamic contraction of the control boundary with the tool wear state.

8. The adaptive intelligent optimization and control system for CNC machining parameters according to claim 1, characterized in that, The preset critical threshold is 0.

35. When the chatter energy entropy value is greater than or equal to 0.35 and the cutting load torque component is lower than the allowable torque limit corresponding to the allowable cutting force limit of the tool, the adaptive boundary arbitration and control reconfiguration module only adjusts the spindle speed multiplier correction factor and synchronously links to maintain the constant single-tooth cutting thickness.

9. The adaptive intelligent optimization and control system for CNC machining parameters according to claim 1, characterized in that, When the cutting load torque component is higher than the rated cutting torque but lower than the allowable torque limit corresponding to the tool's allowable cutting force limit, and the chatter energy entropy value is less than the preset critical threshold, the adaptive boundary arbitration and control reconfiguration module keeps the spindle speed ratio correction factor unchanged, and calculates the control coefficient according to the ratio of the allowable torque limit to the cutting load torque component, and fine-tunes the feed rate ratio correction factor.

10. A method for adaptive intelligent optimization and control of CNC machining parameters, implemented by the adaptive intelligent optimization and control system for CNC machining parameters as described in claim 1, characterized in that, Includes the following steps: Step S1: The dynamic signal acquisition and conversion module synchronously acquires the three-phase AC current signal of the spindle driver and the vibration acceleration signal of the tool holder physical contact, and converts the three-phase AC current signal and vibration acceleration signal into a digital time domain state vector. Step S2: The state feature decoupling and observation calculation module reconstructs the instantaneous electromagnetic torque of the spindle based on the digital time domain state vector using the stator current component and the flux linkage component, extracts the cutting load torque component by low-pass filtering, and extracts the high-frequency characteristic energy spectrum of the vibration acceleration signal by short-time Fourier transform, and calculates the chatter energy entropy value and chatter dominant frequency. Step S3: When the chatter energy entropy value is greater than or equal to the preset critical threshold, the adaptive boundary arbitration and control reconstruction module calculates the speed fine-tuning increment based on the chatter main frequency, the number of tool teeth and the phase locking order, generates the spindle speed multiplier correction factor, and collaboratively generates the feed rate multiplier correction factor. Step S4: Within the current interpolation cycle of the CNC system, the real-time interpolation rewriting and drive module injects the smoothed feed rate correction factor and spindle speed correction factor into the annular buffer of the CNC interpolator, and rewrites the feed step size and drive command for the next interpolation cycle.

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