A kind of active vibration suppression device and vibration suppression method based on metal cutting machine tool

Abstract

The present application belongs to the technical field of metal cutting machine tool, and particularly relates to an active vibration suppression device and method based on a metal cutting machine tool. The device comprises a mechanical support mechanism fixed on a slide near the surface of a tool tip point. In the inner cavity of the mechanism, a rectangular permanent magnet is elastically suspended through multiple rubber blocks. The permanent magnet is provided with two separated cavities, and a plurality of coils are fixed in each cavity, and the winding planes of the two groups of coils are perpendicular to each other. Rubber blocks are arranged between the mechanical support mechanism and the permanent magnet. Through the two groups of orthogonally arranged coils, Lorentz forces in X and Y directions can be independently generated in the permanent magnet constant magnetic field, so as to synthesize a vibration suppression force vector in any direction in the plane. The device is installed near the tool tip point of the slide, and the near field of the vibration suppression force is realized. The permanent magnet is connected and suspended by the rubber blocks, the self-damping can provide passive vibration reduction, and the asymmetric arrangement can optimize the dynamic stiffness in different directions.

Description

Technical Field

[0001] This invention belongs to the field of metal cutting machine tool technology, specifically relating to an active vibration suppression device and method based on a metal cutting machine tool. Background Technology

[0002] The slide of a metal cutting machine tool is the core linear motion actuator of precision and heavy-duty cutting machine tools such as CNC floor-type milling and boring machines, gantry machining centers, and heavy-duty milling and boring machines. It is also the main component that generates, transmits, and bears cutting vibrations.

[0003] In actual cutting, the ram will continuously bear the three-dimensional cutting force, feed inertia force, transmission impact and tool excitation. In the overhang state, the rigidity is reduced, and low-frequency vibration and low-amplitude high-frequency vibration are generated in the X and Y directions. These vibrations will be directly transmitted to the tool tip, causing the tool to wear rapidly, the machined surface to have chatter marks, and the dimensional accuracy to exceed the standard. Summary of the Invention

[0004] This invention provides an active vibration damping device for metal cutting machine tools, which generates a reaction force in real time that is equal in amplitude and opposite in phase to the processing vibration. The two forces cancel each other out, thereby achieving the effect of vibration damping and improving the performance of high-end CNC machine tools.

[0005] The device includes: an active vibration damping device; The active vibration damping device is equipped with a mechanical support mechanism, which is fixed on the surface of the slide block near the tip of the blade. An acceleration sensor is installed at the connection between the mechanical support mechanism and the slide block; The mechanical support mechanism is equipped with a permanent magnet in its inner cavity. The mechanical support mechanism and the permanent magnet are connected by a rubber block, so that the permanent magnet is suspended in the inner cavity of the mechanical support mechanism. The permanent magnet is provided with a first cavity and a second cavity, and a partition groove is provided between the first cavity and the second cavity; Both the first cavity and the second cavity are provided with multi-turn coils. The winding plane of the multi-turn coil in the first cavity is perpendicular to the winding plane of the multi-turn coil in the second cavity, so that the two multi-turn coils generate Lorentz forces in the X and Y directions respectively after being energized.

[0006] Preferably, the mechanical support mechanism is fixed to the surface of the ram of the metal cutting machine tool near the tool tip by bolts or adhesive. The mechanical support mechanism and the permanent magnet have rectangular cross-sections, and two rubber blocks are arranged along the long side of the mechanical support mechanism and the permanent magnet. A rubber block is provided along the short side of the mechanical support mechanism and the permanent magnet.

[0007] Preferably, the acceleration sensor includes a first unidirectional acceleration sensor and a second unidirectional acceleration sensor; The mechanical support mechanism is provided with a first mounting boss and a second mounting boss on the connecting surface facing the slide block. The platform of the first mounting boss is perpendicular to the X direction of the slide, the platform of the second mounting boss is perpendicular to the Y direction of the slide, and the platform of the first mounting boss and the platform of the second mounting boss are perpendicular to each other. The detection end face of the first unidirectional accelerometer is attached to the platform of the first mounting boss and fixed thereon. The first unidirectional accelerometer is used to sense vibration signals in the X direction. The detection end face of the second unidirectional acceleration sensor is attached to the platform of the second mounting boss and fixed thereon. The second unidirectional acceleration sensor is used to sense vibration signals in the Y direction.

[0008] Preferably, a non-contact gap is left between the platform of the first mounting boss and the second mounting boss and the surface of the slide block, so as to ensure that the two acceleration sensors only respond to the relative vibration deformation at the connection surface between the mechanical support mechanism and the slide block, and avoid direct interference from local unevenness or friction on the surface of the slide block.

[0009] Preferably, the mechanical support mechanism is an integrally formed closed inner cavity shell, and the mounting base surface of the mechanical support mechanism facing the slide is a planar adaptation structure. The mounting base surface is in contact with the surface of the slide, and the mechanical support mechanism transmits the vibration damping reaction force to the blade tip.

[0010] According to another embodiment of this application, an active vibration suppression method based on a metal cutting machine tool is provided, the method comprising: S1: The vibration signals of the slide block in the X and Y directions are collected in real time by the first unidirectional acceleration sensor and the second unidirectional acceleration sensor, respectively; S2: The collected vibration signal is transmitted to the CNC system, which filters and integrates the vibration signal to convert it into a digital speed signal; S3: The CNC system analyzes the frequency, phase, and amplitude of the digital speed signal and calculates a reaction force command that has the same frequency, opposite phase, and equal amplitude as the vibration signal. S4: Based on the pre-stored linear relationship between reaction force and current, the reaction force command is converted into a current command, the current command including current magnitude, current frequency and current direction; S5: The current command is amplified by a power amplifier and then sent to the multi-turn coil located in the first and second cavities of the permanent magnet; S6: When the multi-turn coil is energized, it generates a Lorentz force in the magnetic field of the permanent magnet, which drives the permanent magnet to move. The permanent magnet transmits the reaction force to the mechanical support mechanism through the rubber block. The mechanical support mechanism transmits the reaction force to the slide block to counteract the vibration of the slide block in the X and Y directions. S7: The first unidirectional acceleration sensor and the second unidirectional acceleration sensor continue to collect the residual vibration signal after vibration suppression, and feed the residual vibration signal back to the CNC system. The CNC system dynamically corrects the current command based on the residual vibration signal. Repeat steps S2 to S7.

[0011] Preferably, in step S3, the CNC system performs a fast Fourier transform on the velocity sequences in the X and Y directions respectively, with a transform length of 1024 points or 2048 points; calculates the physical frequency corresponding to each frequency index based on the sampling frequency and transform length; traverses the amplitude of the X-direction spectrum within the positive frequency range, locates the index corresponding to the largest amplitude, and the physical frequency corresponding to the index is identified as the dominant frequency of the ram vibration, and this frequency is used simultaneously for generating the reaction force in both the X and Y directions; After locking the dominant frequency, the CNC system reads the complex number corresponding to that frequency from the X-direction spectrum and the complex number corresponding to the same frequency from the Y-direction spectrum; it obtains the velocity amplitude in the X and Y directions through modulo operation, and obtains the velocity phase in the X and Y directions through four-quadrant arctangent calculation.

[0012] Preferably, the CNC system calls the pre-stored equivalent mass coefficients in the X and Y directions, multiplies the X-direction velocity amplitude by the equivalent mass coefficient in that direction, and then multiplies it by the product of twice pi and the dominant frequency to obtain the X-direction reaction force amplitude; the same operation is performed on the Y-direction velocity amplitude to obtain the Y-direction reaction force amplitude; the X-direction reaction force phase is the X-direction velocity phase plus π radians, and the Y-direction reaction force phase is the Y-direction velocity phase plus π radians; finally, the X-direction and Y-direction reaction force commands are expressed in complex number form.

[0013] Preferably, the linear relationship between the pre-stored reaction force and the current in step S4 is obtained through the following offline calibration process: Disconnect the active vibration damping device from the slide block, fix the active vibration damping device on a horizontal calibration platform, install a standard force sensor on the side of the calibration platform, and align the force measurement direction of the force sensor with the X or Y direction of the active vibration damping device; pass a DC current through the multi-turn coil in the first or second cavity, with the current value increasing from zero, and record the reading of the standard force sensor at each current value; plot a force-current scatter plot, fit a straight line using the least squares method, and the slope of the straight line is the linear coefficient of the cavity; repeat three times and take the average, the relative deviation of the three slopes is considered to be less than the preset deviation threshold as qualified calibration.

[0014] Preferably, in step S7, the CNC system performs the same trapezoidal numerical integration on the residual acceleration sequence as in step S2 to obtain the residual velocity sequence; the positive maximum value and the negative minimum value are extracted from the residual velocity sequence, and the residual vibration amplitude in the X direction is calculated to be half the difference between the positive maximum value and the negative minimum value; When the residual vibration amplitude in the X direction exceeds the allowable threshold in the X direction, the CNC system calculates the current correction in the X direction as the X-direction proportional coefficient multiplied by the difference between the residual vibration amplitude in the X direction and the allowable threshold in the X direction. The X-direction proportional coefficient is obtained through offline calibration. During calibration, a known current increment is applied and the change in residual vibration amplitude is measured. The X-direction proportional coefficient is calculated as the inverted current increment divided by the change in residual vibration amplitude. The Y-direction proportional coefficient is obtained using the same calibration method. The CNC system superimposes the X-direction current correction amount onto the X-direction current command amplitude calculated in step S4 to obtain the corrected X-direction current command amplitude; it also superimposes the Y-direction current correction amount onto the Y-direction current command amplitude to obtain the corrected Y-direction current command amplitude; after superposition, it checks whether the corrected current command amplitude exceeds the maximum output current limit of the power amplifier; if it does, the amplitude is limited to that limit; the corrected current command replaces the original command and is output through step S5.

[0015] As can be seen from the above technical solutions, the present invention has the following advantages: The permanent magnet of this invention has two cavities with mutually perpendicular winding planes inside, and each cavity contains an independent multi-turn coil. The two coils are independently powered by two channels of a power amplifier, and the magnitude and direction of the current are calculated by a numerical control system based on signals from two directional acceleration sensors. Driven independently in the two directions, the vibrations of the slide in the X and Y directions are canceled out by the corresponding reaction forces.

[0016] The rubber block suspends the permanent magnet inside the shell, preventing direct contact between the magnet and the metal surface of the shell during movement. This eliminates the hysteresis and wear problems caused by dry friction. This suspension structure allows the permanent magnet to respond freely across a wide frequency band without losing high-frequency signals due to mechanical jamming, and its long-stroke movement in the low-frequency range is also unrestricted.

[0017] The enclosed inner cavity confines the magnetic field lines generated by the permanent magnet within the housing, reducing outward leakage and resulting in a more uniform magnetic flux density in the coil area, thus improving the linearity of the Lorentz force output. The mechanical support mechanism's mounting base facing the slide is designed as a planar fit structure, maximizing the contact area by ensuring the base surface fits snugly against the slide surface during installation. This planar fit structure guarantees that the center of gravity of the device is on the same plane as the slide surface after installation, preventing the introduction of additional overturning moments due to a shift in the center of gravity after installation, and ensuring that the machine tool's dynamic balance characteristics remain unaffected.

[0018] During vibration suppression, the accelerometer continuously collects residual vibration signals. The CNC system calculates the ratio of the residual amplitude to the original amplitude and the difference between the residual phase and the reaction force phase after each control cycle. When the ratio exceeds a preset threshold, the current command amplitude is proportionally amplified or reduced to meet the vibration suppression requirements. Attached Figure Description

[0019] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram showing the active vibration damping device in conjunction with the slide block. Figure 2 This is a schematic diagram of an active vibration damping device; Figure 3 for Figure 2 Diagram of the AA direction; Figure 4 Schematic diagram of a permanent magnet; Figure 5 This is a flowchart of an active vibration suppression method for metal cutting machine tools. Detailed Implementation

[0021] like Figure 1 As shown, the slide 1, also known as the metal cutting machine tool slide 1, is the mounting carrier and target of the entire active vibration damping device.

[0022] The ram body is made of high-strength gray cast iron, ductile iron, or alloy cast steel, and undergoes multiple rounds of aging treatment to eliminate internal residual stress, ensuring no stress deformation even after long-term use. The ram adopts a rectangular or square cross-section structure with internal grid-shaped or honeycomb-shaped stiffeners to enhance bending and torsional rigidity. Externally, it is machined with high-precision guideway mating surfaces and a flat mounting base. The guideway mating surfaces mate with the linear or hydrostatic guideways of the machine tool saddle and spindle box. The mounting base is used to fix mechanical support mechanisms and other auxiliary components. The front end of the ram is the working end near the tool tip, used to mount the spindle, tool holder, cutting tools, and various milling head accessories. The rear end connects to the machine tool's feed transmission mechanism, enabling axial and transverse linear feed motion. On some large boring and milling machines, the ram can be horizontally extended, forming a cantilever beam configuration.

[0023] The ram bears the spindle system and all cutting loads during the cutting process, converting the feed power of the servo motor into the linear motion of the tool to complete cutting actions such as drilling, boring, milling, and tapping. The ram maintains the positional accuracy and linearity of the tool tip. The rigidity and motion accuracy of the ram directly determine the dimensional accuracy, form and position tolerances, and surface roughness of the workpiece. Furthermore, the ram provides a stable mounting base for active vibration damping devices. The area of ​​the ram closest to the tool tip experiences the greatest vibration amplitude, making it the optimal location for applying vibration damping force.

[0024] During actual cutting, the ram continuously bears triaxial cutting forces, feed inertia forces, transmission impacts, and tool excitation. In its overhang state, its rigidity decreases, generating low-frequency and low-amplitude high-frequency vibrations in the X and Y directions. These vibrations are directly transmitted to the tool tip, causing rapid tool wear, surface chatter marks, and dimensional inaccuracies. The ram's vibration signals are the target of the accelerometers in this invention. The vibration of ram 1 is acquired by two accelerometers 7 through the relative deformation between the mechanical support mechanism 3 and the connecting surface. The sensors collect the vibration signals in the X and Y directions and send them to the CNC system. The CNC system calculates the reaction force command and drives the active vibration damping device 2 to output a reverse Lorentz force. This force is transmitted back to the mounting surface of ram 1 via the mechanical support mechanism 3 and the rubber block 4, directly offsetting the cutting vibration force near the tool tip. Ram 1 itself does not participate in the generation of force; it is both the vibration carrier and the force-bearing body for damping. The entire dual-degree-of-freedom active vibration damping device is designed and arranged around the vibration characteristics of ram 1 in the X and Y directions.

[0025] The active vibration damping device based on metal cutting machine tools according to this application will be described in detail below. Specific details such as particular system structures and technologies are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details.

[0026] Combination Figures 2 to 4 As shown, the active vibration damping device based on a metal cutting machine tool includes: an active vibration damping device 2. The active vibration damping device 2 is fixed on the surface of the slide 1 near the tool tip, which is the area where the cutting force is most concentrated. The reaction force can cancel out the vibration excitation on the force transmission path.

[0027] Furthermore, the active vibration damping device 2 is provided with a mechanical support mechanism 3, which is fixed to the surface of the slide block 1 near the tip. The mechanical support mechanism 3, as a closed shell frame, provides installation space for the internal permanent magnet 5 and multi-turn coil 6, and also plays a role in force transmission, ultimately guiding the Lorentz force generated by the coil to the slide block 1.

[0028] In some embodiments, the mechanical support mechanism 3 is fixed to the slide 1 by bolts or adhesive. Bolt connections are convenient for installation and disassembly, and can be directly installed on different types of machine tools. Both the mechanical support mechanism 3 and the permanent magnet 5 have rectangular cross-sections, with two rubber blocks 4 arranged along the long side and one rubber block 4 arranged along the short side. The long side is the main direction of motion, and the vibration amplitude is usually larger. Arranging the two rubber blocks side-by-side can distribute the load and avoid nonlinear stiffness characteristics caused by excessive deformation of a single rubber block. The vibration amplitude in the short side direction is relatively small, and one rubber block is sufficient to provide the required elastic support.

[0029] The rubber block suspends the permanent magnet inside the shell, preventing direct contact between the magnet and the metal surface of the shell during movement. This eliminates the hysteresis and wear problems caused by dry friction. This suspension structure allows the permanent magnet to respond freely across a wide frequency band without losing high-frequency signals due to mechanical jamming, and its long-stroke movement in the low-frequency range is also unrestricted.

[0030] Accelerometer 7 is attached to the connection surface between mechanical support mechanism 3 and slide 1. Accelerometer 7 can sense the vibration state of slide in the two orthogonal directions X and Y in real time. After the collected acceleration signal is filtered and integrated by the CNC system, it is converted into velocity and displacement information, providing raw data for calculating reaction force commands.

[0031] The permanent magnet 5 is suspended in the inner cavity of the mechanical support mechanism 3 by the rubber block 4. This suspension method gives the permanent magnet the freedom to move freely in both the X and Y directions. The permanent magnet 5 itself does not have rigid contact with the shell, so there will be no friction or jamming during movement. Therefore, the response speed is not restricted by mechanical clearance.

[0032] The first and second cavities of the permanent magnet are separated by a slot. Each cavity contains a set of multi-turn coils 6. The winding planes of these two sets of coils are perpendicular to each other. When energized, one set generates a Lorentz force laterally, and the other set generates a Lorentz force longitudinally. These two sets independently control the reaction forces in the X and Y directions and are not coupled. According to Fleming's left-hand rule, the direction of the current in the coil determines the direction of the Lorentz force. Changing the current polarity reverses the direction of the force, thus providing an output quantity that is completely opposite to the vibration signal.

[0033] Furthermore, the magnitude of the force is determined by the formula F=BILsinθ, where B is provided by the magnetic flux density of the permanent magnet, I is determined by the current value output by the controller, and L is the effective length of the coil in the magnetic field. The product of these three parameters directly determines the maximum reaction force that the device can output. The permanent magnet, acting as a moving mass, reciprocates linearly along the guide system under the drive of the Lorentz force. The reaction force generated by this motion is transmitted through the rubber block 4 to the mechanical support mechanism 3, and then from the mechanical support mechanism 3 to the slide block 1.

[0034] Rubber block 4 is an elastic support element for the permanent magnet, allowing the permanent magnet to suspend and move freely within the housing. It is also a force transmission medium, elastically transmitting the reaction force generated by the movement of the permanent magnet to the housing. The elastic deformation of the rubber material can also absorb some high-frequency impacts, preventing rigid collisions from interfering with the sensor.

[0035] In some embodiments, the accelerometer 7 can be configured as a first unidirectional accelerometer and a second unidirectional accelerometer. Each accelerometer is used to sense vibration in only one direction. This division of labor allows signal processing in the X and Y directions to be performed completely independently, preventing misjudgments caused by cross-coupling. A first mounting boss and a second mounting boss are provided on the connecting surface of the mechanical support mechanism 3 facing the slide ram 1. The surfaces of these two bosses are perpendicular to the X and Y directions, respectively, and are mutually perpendicular. The sensor is mounted on these two bosses.

[0036] It should be noted that the purpose of the boss is to raise the detection end face of the accelerometer from the surface of the housing, creating a non-contact gap between the detection end face and the surface of the slide block 1. This is because if the accelerometer is directly attached to the surface of the slide block, local unevenness, chip accumulation, or coolant splashing on the slide block surface will be misread as vibration signals by the accelerometer. However, after being raised by the boss, the accelerometer only senses the relative deformation caused by vibration at the connection surface between the mechanical support mechanism 3 and the slide block 1, thus improving the accuracy of the signal.

[0037] It should be noted that the first unidirectional accelerometer is fixed after its detection end face is attached to the platform of the first mounting boss, sensing the vibration acceleration in the X direction. Similarly, the second unidirectional accelerometer senses the vibration acceleration in the Y direction. The two signals are separately sent to the CNC system. The controller of the CNC system independently performs spectrum analysis on each signal, extracting its frequency, phase, and amplitude information, and then calculates the required reaction force current command in the corresponding direction. This dual-channel independent processing architecture ensures that the vibration suppression control in the X and Y directions does not interfere with each other, improving the system's robustness.

[0038] In some embodiments, the mechanical support mechanism 3 adopts an integrally molded closed inner cavity shell structure. This structure is characterized by a completely sealed internal space, preventing external chips, coolant, and dust from entering the inner cavity. The permanent magnet 5 and the multi-turn coil 6 will not experience movement stagnation or coil short circuit due to foreign object intrusion.

[0039] The enclosed inner cavity confines the magnetic field lines generated by the permanent magnet within the housing, reducing outward leakage and resulting in a more uniform magnetic flux density in the coil area, thus improving the linearity of the Lorentz force output. The mechanical support mechanism 3 has a planar fit structure on its mounting base facing the slide 1. During installation, the base surface fits snugly against the surface of the slide 1, maximizing the contact area. The bolt holes on the mounting base align with the bolt holes on the slide 1, and are then tightened with bolts. This planar fit structure ensures that the center of gravity of the device is on the same plane as the surface of the slide 1 after installation, preventing the introduction of additional overturning moments due to a shift in the center of gravity after installation, and preserving the machine tool's dynamic balance characteristics.

[0040] The following are embodiments of the active vibration suppression method for metal cutting machine tools provided in this disclosure. This method and the active vibration suppression device for metal cutting machine tools in the above embodiments belong to the same inventive concept. For details not described in detail in the embodiments of the active vibration suppression method for metal cutting machine tools, please refer to the embodiments of the active vibration suppression device for metal cutting machine tools described above.

[0041] S1: The vibration signals of the slide block 1 in the X and Y directions are collected in real time by the first unidirectional acceleration sensor and the second unidirectional acceleration sensor, respectively.

[0042] In some embodiments, the sampling frequency of the two unidirectional acceleration sensors is set above the estimated upper limit frequency of the slide vibration. The estimated upper limit frequency can be calculated based on the maximum spindle speed and the number of teeth of the tool, using the following formula: ,in Z represents the spindle speed in revolutions per minute (rpm), and Z represents the number of tool teeth. Sampling frequency. For example, a spindle with a maximum speed of 6000 rpm and a four-tooth end mill. =400 Hz, f s Select 1600 Hz or higher. Two sensors are triggered synchronously, and the trigger signal is generated by a timer interrupt of the CNC system, with the interrupt period equal to the sampling period.

[0043] During each sampling period, the CNC system reads the voltage values ​​from the two sensors, multiplies them by a calibration sensitivity coefficient, and converts them into acceleration values. The calibration sensitivity coefficient is provided by the manufacturer when the sensors are shipped.

[0044] S2: The collected vibration signal is transmitted to the CNC system, which filters and integrates the vibration signal to convert it into a digital speed signal.

[0045] In some embodiments, the CNC system reads the original acceleration sequence and first performs a digital low-pass filter. The filtered acceleration sequence is denoted as... and , where n is the sampling point number.

[0046] Numerical integration is performed on the filtered acceleration sequence to obtain the velocity sequence.

[0047] The integration method uses the trapezoidal rule, and the formula is as follows: ,in The sampling period.

[0048] The initial value of the integral v(0) is set to zero. In practical applications, since the average value of the acceleration signal is zero, the initial value error will naturally decay after several cycles.

[0049] The total phase frequency characteristic of the low-pass filter is close to linear phase within the vibration frequency band, with constant delay. Different frequency components have the same delay, so there is no need to compensate for the filter phase shift during subsequent phase analysis.

[0050] S3: The CNC system analyzes the frequency, phase, and amplitude of the digital speed signal and calculates a reaction force command that has the same frequency, opposite phase, and equal amplitude as the vibration signal.

[0051] In some embodiments, the CNC system measures the velocity sequences v in the X and Y directions. x (n) and v y (n) Perform Fast Fourier Transform (FFT) on each of the n values, with a transform length of N. fft The number of points is usually set to 1024 or 2048 to achieve a balance between frequency resolution and real-time performance.

[0052] The FFT output is a complex array V. x (k) and V y (k), where each index k corresponds to a physical frequency. fs is the sampling frequency. Traverse k=1 to k=N fft / 2 spectral magnitude V x (k), locating the index k of the maximum value. max,x Its corresponding frequency f v =k max,x ×fs / N fft This frequency is identified as the dominant frequency of the current slide vibration. It is used simultaneously to generate reaction forces in both the X and Y directions, ensuring synchronized excitation of both axes and preventing beat vibration caused by frequency deviation.

[0053] Locking the dominant frequency f v Then, the system directly extracts the complex value of that frequency point from the FFT result: V x (f v )=V x (k max,x V y (f v )=V(k max,y The velocity amplitude is obtained through modulo operation. .

[0054] The phase is obtained by four-quadrant arctangent . The plural form is used herein instead of time-domain peak detection because the vibration waveform is often distorted due to interference from random impacts during cutting, and frequency-domain peaks are robust to such non-stationary noise and can stably track the real vibration frequency.

[0055] The construction of the reaction force command is based on the frequency-domain form of Newton's second law. The system calls the pre-stored equivalent mass coefficient m eg.x and m eq.y , which are obtained through factory calibration and reflect the comprehensive inertia-stiffness characteristics of the ram in a specific direction. The method for converting velocity amplitude to force amplitude is , .

[0056] The phase is set to to ensure that the force vector is opposite to the vibration velocity vector. Finally, the reaction force command is .

[0057] S4: converting the reaction force command into a current command according to a pre-stored linear relationship between reaction force and current, wherein the current command includes current magnitude, current frequency and current direction.

[0058] In some embodiments, the numerical control system is configured with a reaction force-current linear coefficient table, which is generated by off-line calibration after the active vibration suppression device is assembled.

[0059] The calibration process is as follows: disconnect the connection between the active vibration suppression device and the ram, and fix the device on a horizontal calibration table. A standard force sensor is installed on the side of the calibration table, and the force measuring direction of the force sensor is aligned with the X direction or Y direction of the active vibration suppression device. Direct current is supplied to the multi-turn coil in the first cavity or the second cavity, the current value increases incrementally starting from 0, and the reading of the standard force sensor corresponding to each current value is recorded. Draw a force-current scatter diagram, fit a straight line by the least square method, and the slope of the straight line is the linear coefficient k of the cavity FI . Repeat the process three times and take the average value; calibration is considered qualified if the relative deviation of the three slopes is less than 2%.

[0060] During conversion, the X-direction reaction force amplitude |F x | is divided by the linear coefficient k of the first cavity FI1 to obtain the first current amplitude I1=| | / k FI1 . The Y-direction reaction force amplitude | | is divided by the linear coefficient k of the second cavity FI2 to obtain the second current amplitude I2=| | / k FI2The current frequency is the vibration frequency locked in S3. .

[0061] S5: The current command is amplified by a power amplifier and then sent to the multi-turn coil 6 located in the first and second cavities of the permanent magnet 5.

[0062] In some embodiments, the power amplifier receives a weak current command output by the numerical control system and amplifies the current signal to the strength required to drive the multi-turn coil according to a fixed amplification factor. The amplified current is independently delivered to the multi-turn coil in the first cavity and the second cavity of the permanent magnet. The current delivery lines are independent of each other and no current crosstalk occurs.

[0063] S6: When the multi-turn coil 6 is energized, it generates a Lorentz force in the magnetic field of the permanent magnet 5, which drives the permanent magnet 5 to move. The permanent magnet 5 transmits the reaction force to the mechanical support mechanism 3 through the rubber block 4. The mechanical support mechanism 3 transmits the reaction force to the slide block 1 to counteract the vibration of the slide block 1 in the X and Y directions.

[0064] S7 The first and second unidirectional acceleration sensors continue to collect the residual vibration signal after vibration suppression and feed the residual vibration signal back to the CNC system. The CNC system dynamically corrects the current command according to the residual vibration signal and repeats steps S2 to S7.

[0065] In some embodiments, during step S6, the first unidirectional acceleration sensor and the second unidirectional acceleration sensor simultaneously acquire residual vibration signals in the X and Y directions after vibration suppression. In each sampling period, the CNC system reads the voltage values ​​of the two sensors, multiplies them by the calibration sensitivity coefficient to convert them into residual acceleration values, and performs the same trapezoidal numerical integration as in step S2 on the residual acceleration sequence to obtain the residual velocity sequence.

[0066] Peak values ​​are extracted from the residual velocity sequence: positive peaks are the maximum values ​​in the sequence, and negative peaks are the minimum values. The residual vibration amplitude A in the X direction is acquired in real time. x Take half the sum of the absolute values ​​of the positive and negative peaks, i.e., Ax = (max(v x )-min(v x )) / 2. Similarly, A is obtained in the Y direction. y .

[0067] Preset allowable threshold A x0 and A y0 A x0 A preset vibration amplitude threshold is set for the X-direction, which is the maximum residual vibration amplitude of the slide block in the X-direction allowed by the system. Exceeding this value will trigger current correction. A y0A preset vibration amplitude threshold is set for the Y-direction, which is the maximum residual vibration amplitude of the slide in the Y direction allowed by the system. Exceeding this value will trigger current correction. The specific value is set according to the machine tool type during device calibration, and can be selected as 5% to 10% of the original vibration amplitude of the slide.

[0068] When Ax > Ax0, calculate the X-direction drive current correction ΔI. x =K x ×(Ax-Ax0), where K x This is a proportionality coefficient, measured in amperes per meter per second. The value of Kx is obtained during offline calibration of the device: a known current increment ΔItest is applied, the change in residual vibration amplitude ΔAtest is measured, and Kx is calculated as Kx = -ΔItest / ΔAtest, with a positive result. The calibration method for the Y direction is the same: Ky = -ΔIytest / ΔAy_test. ΔIy = Ky × (Ay - Ay0), where ΔIy is the correction amount for the Y-direction drive current, superimposed on the original Y-direction current command, directly changing the magnitude of the current flowing through the multi-turn coil in the second cavity.

[0069] Ky is the Y-direction current correction coefficient, a fixed positive value obtained from the pre-shipment frame test calibration, used to set the adjustment range of the current after residual vibration exceeds the tolerance. Ay is the real-time acquired Y-direction residual vibration amplitude, obtained from the second unidirectional acceleration sensor.

[0070] The CNC system will correct the amount ΔI x The current command amplitude I in the X direction calculated in step S4 is superimposed on it. x Above, we get I x '=I x +ΔI x After superposition, check I. x Does it exceed the maximum output current limit of the power amplifier? max If exceeded, the limit is I. max The same procedure applies to the Y direction. The corrected current command replaces the original command and is output via step S5.

[0071] Then, steps S2 to S7 are executed repeatedly. During the repeated execution, the CNC system retains the residual vibration amplitude A from the previous iteration. x For reference, when A is in three consecutive loops x All are lower than A x0 At that time, K x Temporarily reduce by half to avoid over-correction causing oscillations. If A x Surpass A again x0 Restore the original K x value.

[0072] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0073] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0074] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0075] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An active vibration damping device based on a metal cutting machine tool, characterized in that, include: Active vibration damping device (2); The active vibration damping device (2) is provided with a mechanical support mechanism (3), which is fixed on the surface of the slide block (1) near the tip of the blade. An acceleration sensor (7) is installed at the connection between the mechanical support mechanism (3) and the slide (1); The mechanical support mechanism (3) is provided with a permanent magnet (5) in its inner cavity. The mechanical support mechanism (3) and the permanent magnet (5) are connected by a rubber block (4), so that the permanent magnet (5) is suspended in the inner cavity of the mechanical support mechanism (3). The permanent magnet (5) is provided with a first cavity and a second cavity, and a partition groove is provided between the first cavity and the second cavity; Both the first cavity and the second cavity are provided with multi-turn coils (6), wherein the winding plane of the multi-turn coil in the first cavity is perpendicular to the winding plane of the multi-turn coil in the second cavity, so that the two multi-turn coils generate Lorentz forces in the X and Y directions respectively after being energized.

2. The active vibration damping device based on a metal cutting machine tool according to claim 1, characterized in that, The mechanical support mechanism (3) is fixed to the surface of the slide of the metal cutting machine tool near the tool tip by bolts or adhesive; The cross-sections of the mechanical support mechanism (3) and the permanent magnet (5) are rectangular, and two rubber blocks (4) are arranged along the long side of the mechanical support mechanism (3) and the permanent magnet (5). A rubber block (4) is provided on the short side of the mechanical support mechanism (3) and the permanent magnet (5).

3. The active vibration damping device based on a metal cutting machine tool according to claim 1, characterized in that, The acceleration sensor (7) includes a first unidirectional acceleration sensor and a second unidirectional acceleration sensor; The mechanical support mechanism (3) has a first mounting boss and a second mounting boss on the connecting surface facing the slide (1); The platform of the first mounting boss is perpendicular to the X direction of the slide (1), the platform of the second mounting boss is perpendicular to the Y direction of the slide (1), and the platform of the first mounting boss and the platform of the second mounting boss are perpendicular to each other. The detection end face of the first unidirectional accelerometer is attached to the platform of the first mounting boss and fixed thereon. The first unidirectional accelerometer is used to sense vibration signals in the X direction. The detection end face of the second unidirectional acceleration sensor is attached to the platform of the second mounting boss and fixed thereon. The second unidirectional acceleration sensor is used to sense vibration signals in the Y direction.

4. The active vibration damping device based on a metal cutting machine tool according to claim 3, characterized in that, A non-contact gap is left between the platform of the first mounting boss and the second mounting boss and the surface of the slide (1) to ensure that the two acceleration sensors only respond to the relative vibration deformation at the connection surface between the mechanical support mechanism (3) and the slide (1), and avoid direct interference from local unevenness or friction on the surface of the slide.

5. The active vibration damping device based on a metal cutting machine tool according to claim 1, characterized in that, The mechanical support mechanism (3) is an integrally formed closed inner cavity shell. The mounting base of the mechanical support mechanism (3) facing the slide (1) is a planar adaptation structure. The mounting base is in contact with the surface of the slide (1). The mechanical support mechanism (3) transmits the vibration damping reaction force to the tip of the blade.

6. An active vibration suppression method based on metal cutting machine tools, characterized in that, The method is implemented based on the active vibration damping device for metal cutting machine tools as described in any one of claims 1 to 5, and the method includes: S1: The vibration signals of the slide block (1) in the X and Y directions are collected in real time by the first unidirectional acceleration sensor and the second unidirectional acceleration sensor respectively; S2: The collected vibration signal is transmitted to the CNC system, which filters and integrates the vibration signal to convert it into a digital speed signal; S3: The CNC system analyzes the frequency, phase, and amplitude of the digital speed signal and calculates a reaction force command that has the same frequency, opposite phase, and equal amplitude as the vibration signal. S4: Based on the pre-stored linear relationship between reaction force and current, the reaction force command is converted into a current command, the current command including current magnitude, current frequency and current direction; S5: The current command is amplified by a power amplifier and then sent to the multi-turn coil (6) located in the first cavity and the second cavity of the permanent magnet (5). S6: After the multi-turn coil (6) is energized, it generates Lorentz force in the magnetic field of the permanent magnet (5), which drives the permanent magnet (5) to move. The permanent magnet (5) transmits the reaction force to the mechanical support mechanism (3) through the rubber block (4). The mechanical support mechanism (3) transmits the reaction force to the slide (1) to counteract the vibration of the slide (1) in the X and Y directions. S7: The first unidirectional acceleration sensor and the second unidirectional acceleration sensor continue to collect the residual vibration signal after vibration suppression, and feed the residual vibration signal back to the CNC system. The CNC system dynamically corrects the current command based on the residual vibration signal. Repeat steps S2 to S7.

7. The active vibration suppression method for metal cutting machine tools according to claim 6, characterized in that, In step S3, the CNC system performs a fast Fourier transform on the velocity sequences in the X and Y directions, respectively, with a transform length of 1024 or 2048 points; calculates the physical frequency corresponding to each frequency index based on the sampling frequency and transform length; iterates through the amplitude of the X-direction spectrum within the positive frequency range, locates the index corresponding to the largest amplitude, and identifies the physical frequency corresponding to the index as the dominant frequency of the ram vibration, and uses this frequency simultaneously for generating the reaction force in both the X and Y directions; After locking the dominant frequency, the CNC system reads the complex number corresponding to that frequency from the X-direction spectrum and the complex number corresponding to the same frequency from the Y-direction spectrum; it obtains the velocity amplitude in the X and Y directions through modulo operation, and obtains the velocity phase in the X and Y directions through four-quadrant arctangent calculation.

8. The active vibration suppression method for metal cutting machine tools according to claim 7, characterized in that, The CNC system calls the pre-stored equivalent mass coefficients in the X and Y directions. It multiplies the X-direction velocity amplitude by the equivalent mass coefficient in that direction, and then multiplies it by the product of twice pi and the dominant frequency to obtain the X-direction reaction force amplitude. The same operation is performed on the Y-direction velocity amplitude to obtain the Y-direction reaction force amplitude. The X-direction reaction force phase is the X-direction velocity phase plus π radians, and the Y-direction reaction force phase is the Y-direction velocity phase plus π radians. Finally, the X-direction and Y-direction reaction force commands are expressed in complex number form.

9. The active vibration suppression method for metal cutting machine tools according to claim 6, characterized in that, The linear relationship between the pre-stored reaction force and the current mentioned in step S4 is obtained through the following offline calibration process: Disconnect the active vibration damping device from the slide block, fix the active vibration damping device on a horizontal calibration platform, install a standard force sensor on the side of the calibration platform, and align the force measurement direction of the force sensor with the X or Y direction of the active vibration damping device; pass a DC current through the multi-turn coil in the first or second cavity, with the current value increasing from zero, and record the reading of the standard force sensor at each current value; plot a force-current scatter plot, fit a straight line using the least squares method, and the slope of the straight line is the linear coefficient of the cavity; repeat three times and take the average, the relative deviation of the three slopes is considered to be less than the preset deviation threshold as qualified calibration.

10. The active vibration suppression method for metal cutting machine tools according to claim 6, characterized in that, In step S7, the CNC system performs the same trapezoidal numerical integration on the residual acceleration sequence as in step S2 to obtain the residual velocity sequence; the positive maximum value and the negative minimum value are extracted from the residual velocity sequence, and the residual vibration amplitude in the X direction is calculated to be half the difference between the positive maximum value and the negative minimum value; When the residual vibration amplitude in the X direction exceeds the allowable threshold in the X direction, the CNC system calculates the current correction in the X direction as the X-direction proportional coefficient multiplied by the difference between the residual vibration amplitude in the X direction and the allowable threshold in the X direction. The X-direction proportional coefficient is obtained through offline calibration. During calibration, a known current increment is applied and the change in residual vibration amplitude is measured. The X-direction proportional coefficient is calculated as the inverted current increment divided by the change in residual vibration amplitude. The Y-direction proportional coefficient is obtained using the same calibration method. The CNC system superimposes the X-direction current correction amount onto the X-direction current command amplitude calculated in step S4 to obtain the corrected X-direction current command amplitude. The Y-direction current correction is superimposed on the Y-direction current command amplitude to obtain the corrected Y-direction current command amplitude. After superposition, check whether the amplitude of the corrected current command exceeds the maximum output current limit of the power amplifier. If it does, the amplitude is limited to that limit. The corrected current command replaces the original command and is output through step S5.

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