Dynamic vibration coupling suppression system and method for multi-spindle linkage machining system

Abstract

The invention belongs to the technical field of multi-spindle linkage machining, relates to a dynamic vibration coupling suppression system and method of a multi-spindle linkage machining system, and solves the problem that the machining quality is affected by vibration among multiple spindles. A distributed sensing array of the system collects local high-frequency vibration and overall low-frequency modal signals through a first-class sensor installed on a spindle box and a second-class sensor installed on a key node of a cross beam; the signal decoupling and source positioning module identifies vibration coupling strength and a propagation path to position an interference source main shaft by calculating a cross-correlation function of different main shaft vibration signals; and the dual active suppression controller outputs a dynamic rotating speed modulation instruction to the interference source main shaft so as to damage regenerative flutter, retrieves a pre-stored mapping table according to the real-time distance between the two main shafts, and dynamically corrects the current loop damping gain of the servo system so as to compensate the local dynamic stiffness reduction of the cross beam. Real-time sensing, source positioning and cooperative active suppression of vibration coupling among multiple spindles are achieved, and the stability and the machining quality of linkage machining are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of multi-spindle linkage machining, and particularly relates to a dynamic vibration coupling suppression system and method of a multi-spindle linkage machining system. BACKGROUND

[0002] The multi-spindle linkage machining center is a key equipment for improving the machining efficiency and consistency of complex parts. It can greatly shorten the production cycle by configuring multiple spindles on the same shared cross beam to work synchronously.

[0003] However, in the prior art, each spindle and its driving unit are coupled to each other through the shared cross beam, forming a complex dynamic system. In actual machining, especially when the loads of the spindles are uneven, such as rough and fine machining, or intermittent cutting, the vibration energy generated by a certain spindle will be transmitted to other spindles through the cross beam, inducing forced vibration or even regenerative chatter of the disturbed spindles. This dynamic vibration coupling effect between multiple spindles not only deteriorates the surface quality and tool life at a single machining position, but also can lead to a decrease in machining accuracy and consistency defects, which seriously restricts the performance potential of the equipment.

[0004] That is, the prior art cannot effectively monitor and suppress the complex and time-varying dynamic vibration coupling in the multi-spindle linkage machining system, affecting the stability and precision of multi-spindle machining. SUMMARY

[0005] The present application aims to solve the above problems in the prior art and proposes a dynamic vibration coupling suppression system for a multi-spindle linkage machining system.

[0006] To achieve the purpose of the present application, the following technical solutions can be used:

[0007] A dynamic vibration coupling suppression system for a multi-spindle linkage machining system includes:

[0008] A distributed sensing array: including a first type of sensor installed on each machining head spindle box for collecting local high-frequency vibration signals near the cutting point; and a second type of sensor installed on the key modal nodes of the shared cross beam for collecting low-frequency modal vibration signals reflecting the overall response of the structure;

[0009] A signal decoupling and source positioning module: configured to receive signals from the first and second types of sensors, and after band-pass filtering and preprocessing the signals, calculate the cross-correlation function between the signals of different machining heads Based on the cross-correlation peak value and phase delay, the vibration coupling strength and propagation path between the spindles are identified, and the disturbance source spindle causing the vibration is located;

[0010] Dual active suppression controller: in communication connection with the driving layer of the numerical control system, used to execute the following suppression strategies:

[0011] (1) For the main shaft judged as the interference source, output dynamic rotating speed fluctuation frequency modulation instruction to destroy the phase condition of regenerative chatter;

[0012] (2) Obtain the real-time position coordinates of the first machining head and the second machining head on the beam, calculate the relative distance of the two According to the relative distance, dynamically search the pre-stored position-stiffness mapping table, and real-time correct the current loop damping gain of the servo system to offset the local dynamic stiffness reduction of the beam caused by the main shaft position close.

[0013] The system of the application realizes full-frequency domain and full-space coverage monitoring of the vibration state of the multi-spindle machining system by constructing a distributed sensing array composed of local high-frequency and overall low-frequency sensors, overcoming the limitations of single measurement point information. The signal decoupling and source positioning module can clearly separate and quantify the vibration transmission relationship between the main shafts from the complex mixed signal by using cross-correlation analysis technology, accurately lock the vibration interference source, and solve the technical problem that the interference source is difficult to identify in real time and accurately in the traditional method. The dual active suppression controller implements the cooperative strategy of "source elimination" and "path strengthening", and the dynamic rotating speed modulation of the interference source main shaft can directly break down the generation mechanism of regenerative chatter, and the real-time position acquisition from the numerical control system and the table lookup adjustment of the servo parameter can dynamically compensate the weakening of the beam stiffness caused by the movement of the main shaft. The technical effect of this integrated scheme is that it can actively and adaptively cut off the energy transmission chain of vibration coupling, significantly improving the dynamic stability and machining precision of multi-spindle cooperative machining.

[0014] In the dynamic vibration coupling suppression system of the multi-spindle linkage machining system described above, the dual active suppression controller is internally provided with an SSV parameter adaptive adjustment unit, which is configured to:

[0015] Real-time monitoring of the peak intensity of the cross-correlation function ;

[0016] When the peak intensity is in the first interval, output a rotating speed modulation signal that changes in a sinusoidal wave;

[0017] When the peak intensity is in the second interval higher than the first interval, output a rotating speed modulation signal that changes in a triangular wave, and simultaneously increase the amplitude and the modulation frequency of the rotating speed fluctuation until the peak intensity drops below the preset safety threshold.

[0018] By setting the SSV parameter adaptive adjustment unit, the system's suppression intensity can be intelligently matched with the actual severity of vibration coupling, realizing the refinement and optimization of the suppression strategy. When the coupling is weak, a mild sinusoidal modulation is used to minimize additional interference to the machining process. When the coupling is strong, it is automatically upgraded to a stronger triangular wave modulation and the modulation parameters are increased, thereby ensuring that it can quickly and effectively suppress severe vibrations and avoid out-of-control vibrations. This adaptive mechanism ensures the suppression effect while also taking into account the machining efficiency and smoothness.

[0019] In the dynamic vibration coupling suppression system of the multi-spindle linkage machining system described above, the position-stiffness mapping table is a lookup table stored in the non-volatile memory of the controller, which is pre-constructed by the following method:

[0020] In the non-cutting state of the machine tool, the double spindles are stopped at different positions of the cross beam with different spacings The hammer modal knocking experiment or finite element dynamics simulation is performed;

[0021] The first-order bending modal frequency and damping ratio of the system under different spacings are extracted;

[0022] A nonlinear mapping relationship is established between the spindle spacing and the additional electromagnetic damping gain value required to maintain system stability .

[0023] The system pre-constructs the position-stiffness mapping table to convert the complex mechanical structure dynamics into data that can be quickly queried by the controller, and applies the offline obtained accurate modal knowledge to real-time control in a linear manner, so that the system can predict and compensate the stiffness risk caused by the change of spindle layout in advance, avoiding the delay and error caused by online identification of stiffness, realizing the forward-looking and accurate compensation of the cross beam dynamic stiffness change, and greatly enhancing the adaptability of the system to different machining positions.

[0024] In the dynamic vibration coupling suppression system of the multi-spindle linkage machining system described above, the signal decoupling and source positioning module further includes a frequency domain feature extraction unit for performing fast Fourier transform on the collected vibration signals before calculating the cross-correlation function;

[0025] The signal decoupling and source positioning module only starts the calculation process of the cross-correlation function when it detects that there are overlapping dominant frequency components in the vibration spectra of the two spindles, and the amplitude of the overlapping component exceeds the background noise by more than 3dB.

[0026] By adding a frequency domain feature extraction unit and setting a "condition trigger" mechanism, the system's operation efficiency and real-time performance are improved. The system only starts the complex cross-correlation analysis when the spectrum analysis confirms the existence of significant and possibly coupled frequency components, avoiding unnecessary complex operations during periods of no coupling or weak coupling. This allows valuable computing resources to be concentrated on truly risky moments, ensuring reliable operation in a multi-task real-time system.

[0027] In the dynamic vibration coupling suppression system of the multi-spindle linkage machining system described above, the modification strategy of the current loop damping gain of the double active suppression controller is specifically:

[0028] The center of the beam span is set as the weakest point of stiffness. When the two spindles are symmetrical about the beam center and the distance is less than 1 / 3 of the beam span, the speed feedback gain of the current loop is kept unchanged, while the proportional gain and the differential gain of the current loop are increased to increase the equivalent electronic damping of the servo system.

[0029] This gain modification strategy, which focuses on enhancing the dynamic response of the current loop while keeping the speed loop stable, can improve the electronic damping of the servo system in specific weak working conditions. This targeted enhancement strategy is more effective than globally adjusting parameters, as it can effectively suppress vibrations that are easily amplified in local low-stiffness areas, while avoiding overall instability or performance loss that may be caused by blind parameter adjustment.

[0030] In the dynamic vibration coupling suppression system of the multi-spindle linkage machining system described above, the first type of sensor in the distributed sensing array is an IEPE piezoelectric acceleration sensor built into the front end cover of the motorized spindle, with a frequency response range covering 3 times the blade passing frequency corresponding to the highest spindle speed; the second type of sensor is a low-frequency high-sensitivity acceleration sensor installed on the reinforcement rib at the back of the beam.

[0031] The built-in high-frequency IEPE sensor can capture vibrations directly related to cutting near the source, avoiding signal transmission attenuation and pollution; the low-frequency sensor installed on the reinforcement rib is most sensitive to the overall modal of the structure. The combination of the two ensures the accuracy and completeness of the system's perception of basic data, laying a reliable physical information foundation for subsequent accurate analysis and effective control.

[0032] In the dynamic vibration coupling suppression system of the multi-spindle linkage machining system described above, the suppression system is connected to the numerical control system through an industrial field bus, and the suppression system reads the coordinate grating position data inside the CNC at a sampling rate of not less than 1 kHz, which is used to calculate the relative distance​ .

[0033] Through the direct high-speed reading of the CNC grating ruler data by the industrial field bus, the real-time, high-precision and synchronous acquisition of the spindle spacing information is realized, the delay, asynchronization or insufficient precision problem caused by the indirect measurement by the external sensor is avoided, the position information on which the stiffness compensation strategy is based is ensured to be strictly consistent with the actual motion state of the machine tool, and therefore the position-based dynamic compensation can be accurately and timely implemented.

[0034] Another object of the present application is to provide a dynamic vibration coupling suppression method for a multi-spindle linkage machining system to solve the above problems in the prior art.

[0035] To achieve the object of the present application, the following technical solutions can be used:

[0036] A dynamic vibration coupling suppression method for a multi-spindle linkage machining system, based on the dynamic vibration coupling suppression system for the multi-spindle linkage machining system, comprises the following steps:

[0037] S1, multi-channel signal synchronous acquisition: real-time synchronous acquisition of vibration time series of the machining head A and the machining head B and ;

[0038] S2, coupling feature analysis: using the cross-correlation function to calculate the correlation degree of the two signals and extract the maximum correlation coefficient ;

[0039] S3, interference source identification: if exceeds the preset coupling threshold , compare the real-time rotation frequency and the harmonic frequency of each spindle with the current vibration main frequency to determine the spindle with high frequency coincidence degree as the interference source spindle;

[0040] S4, cooperative suppression control:

[0041] Sub-step S4-1: send SSV control instructions to the interference source spindle to make its rotation speed periodically fluctuate around the set value;

[0042] Sub-step S4-2: read the numerical control system coordinate data to calculate the distance between the two spindles , according to the distance, look up the table to obtain the damping compensation coefficient, and send it to the servo driver to modify the current loop parameters.

[0043] The method of the application integrates the functions of the foregoing system into a set of automatically operated processes through ordered sensing-analysis-decision-execution steps, realizes closed-loop control of dynamic vibration coupling, and forms a complete feedback suppression loop from synchronous acquisition, quantitative analysis of coupling strength, intelligent identification of interference sources, to execution of collaborative suppression, so that the system can automatically respond to and suppress time-varying coupled vibration generated during operation, and greatly reduces the need for manual intervention for such complex problems.

[0044] In the dynamic vibration coupling suppression method of the multi-spindle linkage machining system, in step S4-2, the application of the damping compensation coefficient adopts a smooth transition algorithm, that is, when the distance is detected to change, a first-order low-pass filter is used to smooth the target gain value to prevent servo system oscillation caused by sudden gain change.

[0045] The smooth transition algorithm is introduced in the parameter correction, which directly avoids the secondary oscillation or impact of the servo system caused by the step change of the damping gain. Through filtering and smoothing, the adjustment process of the control parameters is smooth and continuous, ensuring the stability of the servo system during the parameter adaptive process, thereby ensuring the stability and safety of the entire vibration suppression process and improving the robustness of the system.

[0046] In the dynamic vibration coupling suppression method of the multi-spindle linkage machining system, the method further comprises step S5, suppression effect evaluation and iteration.

[0047] After step S4 is executed, the second type of sensor signal amplitude on the cross beam is continuously monitored; if the vibration amplitude does not decrease to the safety range within the set time, a secondary protection mechanism is triggered to forcibly reduce the feed rate of all spindles to a preset safety value.

[0048] By adding the suppression effect evaluation and the secondary protection mechanism, double safety protection is provided for the system, wherein the primary active suppression strategy is used as the main means, and if it does not achieve the expected effect within the specified time, the system can automatically trigger the speed reduction protection, i.e., the secondary protection mechanism, to quickly suppress vibration deterioration by forcibly reducing the cutting load. This ensures that the system can always control the vibration risk within a safe range under extreme or unforeseen working conditions, fundamentally preventing equipment damage or workpiece rejection due to uncontrolled vibration, and improving the reliability and safety of the entire machining system.

[0049] Compared with the prior art, the application mainly has the following advantages:

[0050] 1. The application uses cross-correlation function to accurately locate the interference source and only implements SSV control on the interference source, thereby maximizing the machining state of other spindles and improving the overall efficiency.

[0051] 2. The present application solves the problem of the failure of traditional fixed parameter control at the weakest point of machine tool stiffness by introducing a "position-damping" gain scheduling strategy, which is beneficial to improve the limit cutting depth during double-spindle near-distance machining.

[0052] 3. The system of the present application integrates a complete closed loop of detection, analysis, decision, execution and effect evaluation, and has self-adaptive ability to complex working conditions without manual intervention to suppress sudden chatter. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 is a schematic diagram of a dynamic vibration coupling suppression system of a multi-spindle linkage machining system;

[0054] Figure 2 is a flowchart of a dynamic vibration coupling suppression method of a multi-spindle linkage machining system;

[0055] Figure 3 is a schematic diagram of a double-slide-ram gantry machining center according to an embodiment of the present application. DETAILED DESCRIPTION

[0056] The following is a specific embodiment of the present application and further describes the technical solutions of the present application in conjunction with the drawings, but the present application is not limited to these embodiments.

[0057] As shown in Figure 1 , the dynamic vibration coupling suppression system of the multi-spindle linkage machining system according to the present embodiment includes:

[0058] Distributed sensing array: including first type sensors installed on each machining head spindle box for collecting local high-frequency vibration signals near the cutting point; and second type sensors installed on the shared beam key modal nodes for collecting low-frequency modal vibration signals reflecting the overall response of the structure;

[0059] Signal decoupling and source positioning module: configured to receive signals of the first type and the second type sensors, and calculate the cross-correlation function between the signals of different machining heads after band-pass filtering preprocessing of the signals, identify the vibration coupling strength and propagation path between the spindles based on the cross-correlation peak value and phase delay, and thereby locate the disturbance source spindle causing the vibration;

[0060] Dual active suppression controller: in communication connection with the drive layer of the numerical control system, used to execute the following suppression strategies:

[0061] (1) For the spindle judged as the disturbance source, output dynamic speed fluctuation frequency modulation instructions to destroy the phase condition of regenerative chatter;

[0062] (2) Obtain the real-time position coordinates of the first machining head and the second machining head on the beam, calculate the relative distance According to the relative distance, a pre-stored position-stiffness mapping table is dynamically retrieved to correct the current loop damping gain of the servo system in real time to offset the local stiffness reduction of the beam caused by the proximity of the spindle position.

[0063] Specifically, the system of the present application achieves full-frequency domain and full-space coverage monitoring of the vibration state of the multi-spindle machining system by constructing a distributed sensing array composed of local high-frequency and overall low-frequency sensors, overcoming the limitations of single-point information. The signal decoupling and source positioning module can clearly separate and quantify the vibration transmission relationship between spindles from complex mixed signals using cross-correlation analysis technology, accurately locking the vibration interference source, and solving the technical problem of real-time and accurate identification of the interference source in traditional methods. The dual active suppression controller implements a collaborative strategy of "source elimination" and "path reinforcement", which can directly break down the generation mechanism of regenerative chatter by dynamically modulating the speed of the interference source spindle, and dynamically compensate for the weakening of the beam stiffness caused by the movement of the spindle by acquiring the position from the numerical control system and adjusting the servo parameters. The technical effect of this integrated solution is that it can actively and adaptively cut off the energy transmission chain of vibration coupling, significantly improving the dynamic stability and machining precision of multi-spindle collaborative machining.

[0064] As an optimization, the dual active suppression controller has an SSV parameter adaptive adjustment unit, which is configured to:

[0065] real-time monitor the peak intensity of the cross-correlation function; when the peak intensity is in the first interval, output a speed modulation signal that varies in a sinusoidal wave;

[0066] when the peak intensity is in the second interval higher than the first interval, output a speed modulation signal that varies in a triangular wave, and simultaneously increase the amplitude

[0067] and the modulation frequency of the speed fluctuation until the peak intensity drops below a preset safety threshold.

[0068] Specifically, by setting the SSV parameter adaptive adjustment unit, the suppression strength of the system can be intelligently matched with the actual severity of vibration coupling, achieving fine and optimization of the suppression strategy. When the coupling is weak, a gentle sinusoidal modulation is used to minimize additional interference to the machining process; when the coupling is strong, it is automatically upgraded to a more powerful triangular wave modulation and the modulation parameters are increased, ensuring that it can quickly and effectively suppress severe vibrations and prevent vibration from getting out of control. This adaptive mechanism ensures the suppression effect while also considering machining efficiency and smoothness.

[0069] ​As an optimization, the position-stiffness mapping table is a look-up table stored in the controller's non-volatile memory, which is pre-constructed by the following way:

[0070] In the non-cutting state of the machine tool, the double-spindle is set at different intervals When parked at different positions of the beam, modal hammering experiments or finite element dynamics simulations are performed;

[0071] The first-order bending modal frequency and damping ratio of the system at different intervals are extracted;

[0072] A nonlinear mapping relationship is established between the interval of the main shaft and the additional electromagnetic damping gain value required to maintain system stability .

[0073] Specifically, the system converts the complex mechanical structure dynamics characteristics into data that can be quickly queried by the controller by pre-constructing the position-stiffness mapping table, and applies the offline obtained accurate modal knowledge to real-time control linearly, so that the system can predict and compensate the stiffness risk caused by the change of spindle layout in advance, avoid the delay and error caused by online identification of stiffness, realize the forward-looking and accurate compensation of the beam dynamic stiffness change, and greatly enhance the adaptability of the system to different machining positions.

[0074] As an optimization, the signal decoupling and source positioning module also includes a frequency domain feature extraction unit for performing fast Fourier transform on the collected vibration signals before calculating the cross-correlation function;

[0075] The signal decoupling and source positioning module only starts the calculation process of the cross-correlation function when it detects that there is an overlapping dominant frequency component in the vibration spectrum of the two spindles, and the amplitude of the overlapping component exceeds the background noise by more than 3dB.

[0076] Specifically, by adding a frequency domain feature extraction unit and setting a "conditional trigger" mechanism, the system's operation efficiency and real-time performance are improved. The system only starts the complex cross-correlation analysis after the spectrum analysis confirms the existence of significant and possibly coupled frequency components, avoiding unnecessary complex operations during periods of no coupling or weak coupling, so that valuable computing resources can be concentrated on truly risky moments, ensuring reliable operation in a multi-task real-time system.

[0077] As an optimization, the double active suppression controller's modification strategy for current loop damping gain is as follows:

[0078] The center of the beam span is set as the weakest point of stiffness, and when the two spindles are symmetric about the center of the beam and the interval is less than 1 / 3 of the beam span, the speed feedback gain of the current loop Keeping the same time, while increasing the current loop proportional gain and the differential gain to increase the equivalent electronic damping of the servo system.

[0079] Specifically, this gain correction strategy, for the high-risk working condition of weak beam stiffness and adjacent double spindles, adopts the way of keeping the speed loop stable and focusing on enhancing the dynamic response of the current loop, which can improve the electronic damping of the servo system in specific weak working conditions. This directional enhancement strategy is more effective than globally adjusting parameters, as it can effectively suppress the vibration amplified in the local low stiffness area, while avoiding the overall instability or performance loss caused by blind parameter adjustment.

[0080] As an optimization of the embodiment, the first type of sensor in the distributed sensing array is an IEPE piezoelectric acceleration sensor built into the front end cover of the motorized spindle, with a frequency response range covering 3 times the blade passing frequency corresponding to the highest spindle speed; the second type of sensor is a low-frequency high-sensitivity acceleration sensor installed on the reinforcement rib at the back of the beam.

[0081] Specifically, the built-in high-frequency IEPE sensor can capture vibrations directly related to cutting near the source, avoiding signal transmission attenuation and pollution; the low-frequency sensor installed on the reinforcement rib is most sensitive to the overall structure modal. The combination of the two ensures the accuracy and completeness of the system's perception of basic data from a technical effect point of view, laying a reliable physical information foundation for subsequent accurate analysis and effective control.

[0082] As an optimization, the suppression system is connected to the CNC system through an industrial field bus, and the suppression system reads the coordinate axis grating position data inside the CNC at a sampling rate of not less than 1kHz, which is used to calculate the relative distance in real time.

[0083] Specifically, by directly and high-speed reading the CNC grating data through the industrial field bus, the real-time, high-precision, and synchronous acquisition of spindle spacing information is achieved, avoiding the problems of delay, asynchronization, or insufficient precision caused by indirect measurement through external sensors, ensuring that the position information on which the stiffness compensation strategy is based is strictly consistent with the actual motion state of the machine tool, so that the position-based dynamic compensation can be accurately and timely effective.

[0084] As shown in Figure 2 , the dynamic vibration coupling suppression method of the multi-spindle linkage machining system of the embodiment, based on the above-mentioned dynamic vibration coupling suppression system of the multi-spindle linkage machining system, comprises the following steps:

[0085] S1, multi-channel signal synchronous acquisition: real-time synchronous acquisition of vibration time series of machining head A and machining head B and ;

[0086] S2, coupling feature analysis: using cross-correlation function Calculate the correlation of two signals and extract the maximum correlation coefficient ;

[0087] S3, interference source identification: if Exceeds the preset coupling threshold , compare the real-time rotation frequency of each main shaft and its harmonic frequency with the current vibration main frequency, and determine the main shaft with high frequency coincidence degree as the interference source main shaft;

[0088] S4, cooperative suppression control:

[0089] Sub-step S4-1: Send SSV control instruction to the interference source main shaft to make its rotation speed fluctuate periodically around the set value;

[0090] Sub-step S4-2: Read the numerical control system coordinate data to calculate the distance between the two main shafts , according to the distance, look up the damping compensation coefficient, and send it to the servo driver to modify the current loop parameter, the application of damping compensation coefficient uses smooth transition algorithm, that is, when the distance changes are detected, a first-order low-pass filter is used to smooth the target gain value to prevent gain mutation from causing servo system oscillation;

[0091] S5, suppression effect evaluation and iteration; continuously monitor the signal amplitude of the second type of sensor on the cross beam; if the vibration amplitude does not decrease to the safety range within the set time, trigger the secondary protection mechanism and forcibly reduce the feed rate of all main shafts to the preset safety value.

[0092] Specifically, the method of the present application integrates the functions of the aforementioned system into a set of automated processes through the ordered steps of perception-analysis-decision-execution, realizes closed-loop control of dynamic vibration coupling, from synchronous acquisition, quantitative analysis of coupling strength, intelligent discrimination of interference sources, to execution of coordinated suppression, forms a complete feedback suppression loop, enables the system to automatically respond to and suppress the time-varying coupling vibration generated during operation, greatly reduces the need for manual intervention for such complex problems. In the parameter correction, a smooth transition algorithm is introduced, which directly avoids the secondary oscillation or impact of the servo system caused by the step change of damping gain. Through filtering and smoothing processing, the adjustment process of the control parameters is smooth and continuous, ensuring the stability of the servo system during the parameter adaptive process, thereby ensuring the smoothness and safety of the entire vibration suppression process and improving the robustness of the system. By adding suppression effect evaluation and secondary protection mechanism, the system provides double-layer safety protection, among which the primary active suppression strategy is the main means, if it does not achieve the expected effect within the specified time, the system can automatically trigger the speed reduction protection, i.e. the secondary protection mechanism, which quickly suppresses the vibration deterioration by forcibly reducing the cutting load. It ensures that the system can always control the vibration risk within a safe range under extreme or unforeseen working conditions, fundamentally prevents equipment damage or workpiece rejection caused by out-of-control vibration, and improves the reliability and safety of the entire machining system.

[0093] As a further embodiment, as shown in Figure 3 , the present embodiment is applied to a double-slide ram gantry machining center.

[0094] Among them, the specific configuration of the distributed sensing array is:

[0095] 1. Single-axis IEPE piezoelectric acceleration sensors are installed on the front end covers of the motorized spindles of the machining head A and the machining head B (near the bearings), which are the first type of sensors for source monitoring, with a sensitivity of 100 mV / g and a frequency response range of 0.5 Hz-10 kHz. The sensitive axis of the sensor is perpendicular to the spindle axis and points to the workpiece, i.e. in the radial cutting force direction.

[0096] 2. Low-frequency high-sensitivity acceleration sensors are arranged on the reinforcing ribs at the 1 / 4, 1 / 2, and 3 / 4 positions of the gantry span, which are the second type of sensors for path monitoring, with a sensitivity of 1000 mV / g, used to capture low-frequency coupling vibration modes (usually between 20 Hz-200 Hz) transmitted through the structure.

[0097] 3. All sensor signals are connected to the data acquisition machine box through shielded cables, and the vibration acquisition module is configured with a sampling rate of 12.8 kS / s.

[0098] The host computer IPC runs signal decoupling and decision software developed based on LabVIEW, and communicates with the numerical control system CNC and PLC of the machine tool in real time through industrial Ethernet. The IPC is responsible for reading the spindle speed , the coordinate position of each axis , and the spindle load current data in the CNC.

[0099] In terms of specific algorithms for signal decoupling and interference source positioning, the signal decoupling module of the embodiment performs the following specific logical operations:

[0100] 1. Signal preprocessing

[0101] The collected original vibration signal x(t) is subjected to DC component removal and band-pass filtering. The passband of the filter is set to , where is 0.5 times the lowest spindle rotation frequency, is 3 times the highest blade passing frequency, for example: rotation speed 3000-15000 rpm, three-blade cutter, then the passband is about 25 Hz-750 Hz.

[0102] 2. Real-time calculation of cross-correlation function:

[0103] The system sets a sliding time window , and calculates the cross-correlation function of the spindle A sensor signal and the spindle B sensor signal in each window :

[0104]

[0105] At the same time, the normalized cross-correlation coefficient is calculated, with a value range of [-1, 1].

[0106] 3. Decision logic and threshold setting

[0107] Independent cutting decision: if (prespecified first threshold value), it is determined that the vibrations of the two spindles are not related, and the system does not intervene.

[0108] Strong coupling decision: if (prespecified second threshold value), it is determined that there is strong coupling, and the interference source needs to be further identified.

[0109] Interference source positioning (frequency fingerprint matching): the FFT transform is performed on the crossbeam center sensor signal to extract the maximum peak frequency .

[0110] If , where k is the number of teeth, The spindle speed A Assuming a frequency tolerance of 2Hz, then spindle A is determined to be the interference source.

[0111] Conversely, if the characteristic frequency of the main axis B is matched, then B is determined to be the source of interference.

[0112] Regarding the execution details of the dual active suppression strategy, once the source of interference (assumed to be spindle A) is identified and the structural coupling risk between the two spindles is confirmed, the controller will concurrently execute the following two instructions:

[0113] 1. Parameter-adaptive SSV control

[0114] The active suppression controller sends speed override commands to the inverter of spindle A via the Profibus bus.

[0115] Waveform selection: Sine wave modulation is used. .

[0116] Parameter calculation:

[0117] Modulation frequency : Set as For example, at 6000rpm, the modulation frequency is 1Hz.

[0118] Modulation amplitude A: Initially set to That is, a fluctuation of 10%. If the cross-correlation coefficient... If the value does not drop below 0.4 within 5 seconds after executing SSV, the amplitude A will be automatically and gradually increased. The maximum percentage shall not exceed 20%.

[0119] 2. Damping Gain Correction Based on Location Lookup Table

[0120] This is the core innovation of the invention: the system reads the Y-axis coordinates of slide A and slide B from the feedback of the grating ruler in real time. ), calculate the physical distance between the two and the position of the center of gravity of the combination .

[0121] During the machine tool's factory commissioning phase, modal testing of the crossbeam was performed using a force hammer. The double slide blocks were placed at different intervals (e.g., 200mm, 500mm, 1000mm...) to determine the system's dynamic stiffness. Experimental data show that when d < 500 mm and When located at the midpoint of the beam, the first-order dynamic stiffness of the system decreases by approximately 40%.

[0122] Based on this data, a "Position-Gain Compensation Table" is constructed and stored in the PLC data block. Part of the data is shown in the table below:

[0123]

[0124] When d = 450 mm is detected and the center of the beam is reached, the controller queries the above table every 10 ms, calculates the current optimal value using a linear interpolation algorithm, and through the drive parameter writing function of the CNC system, modifies the equivalent damping parameter of the current loop of the servo drive in real time to 1.5 times the standard value. This operation increases the "electronic viscous force" of the servo system, effectively absorbing the amplified vibration energy due to insufficient structural stiffness.

[0125] The specific embodiments described herein are merely illustrative of the spirit of the present application. Various modifications or supplements or replacements of the described specific embodiments or similar ways can be made by those skilled in the art to which the present application belongs without departing from the spirit of the present application or exceeding the scope defined by the appended claims.​

Claims

1. A dynamic vibration coupling suppression system for a multi-spindle linkage machining system, characterized in that, include: Distributed sensing array: contains a first type of sensor installed on the spindle box of each machining head, used to collect local high-frequency vibration signals near the cutting point; And a second type of sensor installed on the key modal nodes of the shared beam, used to collect low-frequency modal vibration signals that reflect the overall response of the structure; Signal decoupling and source localization module: configured to receive signals from the first and second types of sensors, perform bandpass filtering preprocessing on the signals, and calculate the cross-correlation function between the corresponding channel signals of different processing heads. Based on the cross-correlation peak value and phase delay, the vibration coupling strength and propagation path between the main shafts are identified, thereby locating the main shaft that causes the vibration interference. Dual active suppression controller: Communicates with the drive layer of the CNC system to execute the following suppression strategies: (1) For the spindle that is identified as an interference source, output a dynamic speed fluctuation frequency modulation command to disrupt the phase condition of regenerative chatter. (2) Obtain the real-time position coordinates of the first and second processing heads on the crossbeam, and calculate the relative distance between them. Based on the relative distance, the pre-stored position-stiffness mapping table is dynamically retrieved, and the current loop damping gain of the servo system is adjusted in real time to offset the decrease in local dynamic stiffness of the crossbeam caused by the proximity of the spindle position.

2. The dynamic vibration coupling suppression system of the multi-spindle linkage machining system according to claim 1, characterized in that, The dual active suppression controller has a built-in SSV parameter adaptive adjustment unit, which is configured as follows: Real-time monitoring of the cross-correlation function Peak intensity; When the peak intensity is in the first range, the output is a speed modulation signal that varies in a sine wave. When the peak intensity is in the second interval, which is higher than the first interval, the output speed modulation signal exhibits a triangular wave variation, and the amplitude of the speed fluctuation is increased simultaneously. and modulation frequency Until the peak intensity drops below the preset safety threshold.

3. The dynamic vibration coupling suppression system of the multi-spindle linkage machining system according to claim 1, characterized in that, The position-stiffness mapping table is a lookup table stored in the controller's non-volatile memory, and this table is pre-built in the following way: In the non-cutting state of the machine tool, the dual spindles are positioned at different intervals. When the beam is stopped at different positions, a hammer modal impact test or finite element dynamics simulation is performed. Extract the first-order bending mode frequency and damping ratio of the system under different spacings; Establish spindle spacing Additional electromagnetic damping gain required to maintain system stability The nonlinear mapping relationship between them.

4. The dynamic vibration coupling suppression system of the multi-spindle linkage machining system according to claim 1, characterized in that, The signal decoupling and source localization module also includes a frequency domain feature extraction unit, which performs a fast Fourier transform on the acquired vibration signal before calculating the cross-correlation function. The signal decoupling and source localization module only initiates the cross-correlation function calculation process when it detects overlapping dominant frequency components in the vibration spectra of the two main shafts, and the amplitude of the overlapping component exceeds the background noise by more than 3dB.

5. The dynamic vibration coupling suppression system of the multi-spindle linkage machining system according to claim 1, characterized in that, The specific strategy for correcting the current loop damping gain of the dual active suppression controller is as follows: The center of the beam span is set as the weakest point in terms of stiffness. When the two principal axes are symmetrical about the beam center and the spacing is... When the span is less than 1 / 3 of the beam span, the velocity feedback gain of the current loop is adjusted. Keep it constant, while increasing the proportional gain of the current loop. and differential gain This is to increase the equivalent electronic damping of the servo system.

6. The dynamic vibration coupling suppression system of the multi-spindle linkage machining system according to claim 1, characterized in that, The first type of sensor in the distributed sensing array is an IEPE piezoelectric accelerometer built into the front cover of the electric spindle, whose frequency response range covers three times the passing frequency of the blades corresponding to the highest spindle speed; the second type of sensor is a low-frequency, high-sensitivity accelerometer installed on the reinforcing rib on the back of the crossbeam.

7. The dynamic vibration coupling suppression system for a multi-spindle linkage machining system according to claim 1, characterized in that, The suppression system is connected to the CNC system via an industrial fieldbus. The suppression system reads the position data of the coordinate axis grating ruler inside the CNC at a sampling rate of no less than 1 kHz for real-time calculation of relative distance. .

8. A method for suppressing dynamic vibration coupling in a multi-spindle linkage machining system, characterized in that, The system according to any one of claims 1-7 includes the following steps: S1. Multi-channel signal synchronous acquisition: Real-time synchronous acquisition of vibration time series of processing head A and processing head B. and ; S2. Coupling Feature Analysis: Using Cross-Correlation Functions Calculate the correlation between the two signals and extract the maximum correlation coefficient. ; S3. Interference Source Identification: If Exceeding the preset coupling threshold Then, compare the real-time rotation frequency and harmonic frequency of each spindle with the current vibration frequency to determine the spindle with the high frequency matching degree as the interference source spindle. S4, Synergistic Inhibition Control: Sub-step S4-1: Send an SSV control command to the spindle of the interference source to make its rotational speed fluctuate periodically around the set value; Sub-step S4-2: Read coordinate data from the CNC system and calculate the distance between the two spindles. The damping compensation coefficient is obtained by looking up the table based on the spacing and then sent to the servo driver to modify the current loop parameters.

9. The dynamic vibration coupling suppression method for a multi-spindle linkage machining system according to claim 8, characterized in that, In step S4-2, the damping compensation coefficient is applied using a smooth transition algorithm, that is, upon detecting the spacing... When the gain changes, a first-order low-pass filter is used to smooth the target gain value to prevent sudden changes in gain from causing oscillations in the servo system.

10. The dynamic vibration coupling suppression method for a multi-spindle linkage machining system according to claim 8, characterized in that, It also includes step S5, evaluation and iteration of the inhibition effect; After executing step S4, the amplitude of the second type of sensor signal on the crossbeam is continuously monitored; if the vibration amplitude does not drop to a safe range within a set time, the secondary protection mechanism is triggered, and the feed rate of all spindles is forcibly reduced to the preset safe value.

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