Self-adaptive vibration cutting machining method based on piezoelectric sensing phase signals

Abstract

The invention provides a self-adaptive vibration cutting processing method based on a piezoelectric sensing phase signal, which comprises the following steps of: installing a piezoelectric sensor between a tool apron and a tool of a vibration device, collecting an output signal of the piezoelectric sensor in a vibration-only non-cutting state, and extracting a phase of the output signal as a reference phase; the machine tool is controlled to make a cutter make contact with the workpiece for vibration cutting machining, output signals of the piezoelectric sensor at the moment are collected, and the phase difference between the output signals and the reference phase is calculated; according to the phase difference, the correction coefficient of the pre-calibrated cutting force and the cutting depth index of the cutting depth influence are combined, and the real-time cutting depth of current vibration cutting machining is obtained through back calculation; the real-time cutting depth is compared with the set cutting depth to obtain a cutting depth difference value, the cutting depth difference value is input into a closed-loop feedback controller to generate a compensation driving signal, the compensation driving signal acts on a driving element of a vibration device or a machine tool, and the relative position of a cutter is adjusted to compensate the cutting depth error. And self-adaptive vibration cutting machining control over the surface profile of the workpiece is completed.

Description

Technical Field

[0001] The present application relates to the field of vibration processing technology, and in particular to an adaptive vibration cutting processing method based on piezoelectric sensing phase signals. Background Art

[0002] In recent years, with the development of bionics, researchers have found that compared with smooth metal surfaces, metal surfaces with periodic microstructures perform better in many aspects such as wetting properties, optical properties, and electrical properties, and have good application prospects in many fields such as aerospace, electronic devices, and biomedicine.

[0003] Single-point diamond vibration cutting is one of the important methods for active control of surface microstructure processing. However, the depth of the microstructure is usually small, only a few microns. Factors such as insufficient flatness of the workpiece surface and insufficient parallelism between the workpiece surface and the machine tool motion axis will affect the consistency of the microstructure height (or depth), and may even cause the tool to separate from the workpiece and be unable to process, seriously affecting the processing quality and efficiency. The current solution is to pre-polish or cut to a higher surface quality, flatness, and parallelism before microstructure processing. However, such pre-treatment is time-consuming and labor-intensive, and is not conducive to large-scale manufacturing. Cutting force is an important factor reflecting the depth of cut during processing. Real-time monitoring of cutting force can achieve real-time perception of the depth of cut. Although traditional commercial dynamometers can monitor cutting force in real time, they are usually expensive and need to be installed under the workpiece. They have high installation requirements for parts of different shapes and are difficult to be widely used.

[0004] By adding low-rigidity energy storage elements such as springs to the processing equipment, it is possible to achieve constant cutting force to a certain extent, and thus indirectly achieve stable control of the cutting depth. However, the control accuracy of this type of method is usually low, and it is difficult to apply to ultra-precision processing processes such as single-point diamond vibration cutting. By integrating sensors on the processing equipment to sense the cutting depth in real time, it is not restricted by the shape of the workpiece and has more diverse application scenarios. The current existing technologies mainly include two categories: using displacement sensors to monitor deformation to indirectly obtain cutting force; using piezoelectric sensors to directly monitor cutting force. Among them, the former usually requires the careful design of low-rigidity and easily deformable structures for deformation monitoring, but it will lead to reduced processing accuracy and bandwidth, affecting the processing performance of the processing equipment; the latter is currently mainly used in static and quasi-static processing scenarios, and cannot be applied to dynamic processing scenarios such as vibration processing. Summary of the Invention

[0005] The present application aims to solve one of the technical problems in the related art at least to a certain extent.

[0006] To this end, the first purpose of this application is to propose an adaptive vibration cutting processing method based on piezoelectric sensing phase signal, so as to realize real-time monitoring of cutting force and real-time perception of cutting depth in periodic dynamic processing processes such as vibration cutting processing, and then realize adaptive tool setting and adaptive surface contour closed-loop feedback control.

[0007] The second purpose of this application is to propose an adaptive vibration cutting device based on piezoelectric sensing phase signals.

[0008] The third objective of this application is to provide an electronic device.

[0009] The fourth object of this application is to provide a computer-readable storage medium.

[0010] A fifth object of this application is to provide a computer program product.

[0011] To achieve the above objectives, the first embodiment of the present application proposes an adaptive vibration cutting method based on piezoelectric sensing phase signals, comprising:

[0012] A piezoelectric sensor is installed between the tool holder and the tool of the vibration device, an output signal of the piezoelectric sensor in a vibration-only, non-cutting state is collected, and its phase is extracted as a reference phase;

[0013] Controlling the machine tool to make the tool contact the workpiece to perform vibration cutting processing, collecting the output signal of the piezoelectric sensor at this time, and calculating the phase difference with the reference phase;

[0014] The real-time cutting depth of the current vibration cutting process is obtained by reverse calculation based on the phase difference, a correction coefficient of the pre-calibrated cutting force and a cutting depth index affected by the cutting depth;

[0015] The real-time cutting depth is compared with the set cutting depth to obtain a cutting depth difference, the cutting depth difference is input into a closed-loop feedback controller to generate a compensation drive signal, and the compensation drive signal is applied to the driving element of the vibration device or the machine tool.

[0016] Optionally, the step of installing a piezoelectric sensor between the tool holder and the tool of the vibration device, collecting an output signal of the piezoelectric sensor in a vibration-only, non-cutting state, and extracting its phase as a reference phase includes:

[0017] The piezoelectric sensor is clamped between the tool and the tool holder through a through-hole structure, and an axial pre-tightening force is provided by a pre-tightening bolt; signal lines are respectively led out on both sides of the polarization direction of the piezoelectric sensor, and are connected to the signal acquisition and processing equipment after passing through a charge amplifier;

[0018] Under external excitation, the tool, piezoelectric sensor and pre-tightening bolt generate simple harmonic vibration along the polarization direction, and the vibration displacement is:

[0019] x(t)=Asin(2πft)

[0020] Where A is the amplitude of the component of the vibration caused by external excitation in the polarization direction of the piezoelectric sensor, and f is the external excitation vibration frequency;

[0021] The vibration velocity v and acceleration a of the tool, piezoelectric sensor, and pre-tightening bolt are calculated based on the vibration displacement. The formula is:

[0022]

[0023] When there is only vibration but no cutting, according to Newton's second law, the force F on the upper and lower sides of the piezoelectric sensor caused by external excitation vibration is obtained 1v and F 2v They are:

[0024] F 1v (t)=(m t +k b1 m b )·a(t)

[0025] F 2v (t)=(m t +m p +k b2 m b )·a(t)

[0026] Among them, m t is the mass of the tool, m p is the mass of the piezoelectric sensor, and the mass of the pre-tightened bolt is m b , k b1 and k b2 It is the correction factor for preloaded bolts;

[0027] The average force F on the piezoelectric sensor caused by external excitation vibration v Expressed as:

[0028]

[0029] Among them, m eq is the equivalent mass of the piezoelectric sensor, expressed as:

[0030]

[0031] The average force F v Converted into voltage output, the output voltage of the piezoelectric sensor is:

[0032] U v (t) = k CA ·d 33·F v (t)=-4π 1 f 2 k CA d 33 m eq Asin(2πft)

[0033] Among them, d 33 is the piezoelectric constant of the piezoelectric sensor along the polarization direction, k CA is the voltage amplification factor of the charge amplifier;

[0034] The amplitude of the output signal of the piezoelectric sensor when it is only vibrating and not cutting and phase They are:

[0035]

[0036] Among them, the phase as a reference signal.

[0037] Optionally, controlling the machine tool to make the tool contact the workpiece to perform vibration cutting processing, collecting the output signal of the piezoelectric sensor at this time, and calculating the phase difference with the reference phase includes:

[0038] During the vibration cutting process between the tool and the workpiece, the output voltage U of the piezoelectric sensor is collected. o (t), where U o (t) is the output under the combined action of vibration and cutting force, which satisfies the superposition principle and is expressed as:

[0039] U o (t) = U v (t)+U c (t)

[0040] Among them, U c (t) = k CA ·d 33 ·F c (t) is the output voltage of the piezoelectric sensor caused by the cutting force, F c (t) is the cutting force, which is approximately:

[0041] F c (t) = kh n v(t)

[0042] Where h is the cutting depth of vibration machining, n is the correction index of cutting depth effect, and k is the correction coefficient of cutting force;

[0043] Substituting in:

[0044] U o (t)=-2πfkCA d 33 A(2πfm eq sin(2πft)-kh n cos(2πft))

[0045] According to the auxiliary angle formula, the output voltage U of the piezoelectric sensor during the vibration cutting process between the tool and the workpiece is o (t) can be equivalently expressed as:

[0046]

[0047] The amplitude of the output signal of the piezoelectric sensor in the vibration cutting state and phase They are:

[0048]

[0049] Therefore, the signal difference between the actual vibration cutting process and the vibration without cutting is:

[0050]

[0051] Where ΔA U is the difference in signal amplitude between the actual vibration cutting process and the vibration without cutting, It is the signal phase difference between the actual vibration cutting process and the signal phase difference between the vibration without cutting.

[0052] Optionally, the back-calculation to obtain the real-time cutting depth of the current vibration cutting process based on the phase difference in combination with a pre-calibrated cutting force correction coefficient and a cutting depth index affected by the cutting depth includes:

[0053] The phase difference Substitute the following formula to calculate the current cutting depth h:

[0054]

[0055] Among them, k is the correction coefficient of the pre-calibrated cutting force, and n is the cutting depth index of the pre-calibrated cutting depth effect.

[0056] Optionally, before controlling the machine tool to bring the tool into contact with the workpiece for vibration cutting processing, the method further includes:

[0057] Before machining, the machine tool controls the tool to vibrate and test-cut on the workpiece surface, and the perceived cutting depth during the test-cut is calculated in reverse.

[0058] If the perceived cutting depth is less than the tool setting threshold, it is considered that the tool is not in contact with the workpiece at this time. The distance between the tool and the workpiece is reduced and the next trial cutting is performed until the perceived cutting depth obtained by backcalculation is greater than the tool setting threshold. It is considered that the tool is in contact with the workpiece at this time, and the trial cutting and tool setting are completed.

[0059] Optionally, the comparing the real-time cutting depth with the set cutting depth to obtain a cutting depth difference, inputting the cutting depth difference into a closed-loop feedback controller to generate a compensation drive signal, and applying the compensation drive signal to a driving element of a vibration device or a machine tool, comprises:

[0060] During the vibration cutting process, the difference between the real-time cutting depth obtained by inverse calculation based on the phase difference and the set cutting depth is calculated to obtain a cutting depth error;

[0061] The cutting depth error is sent as input to a closed-loop feedback controller, and a cutting depth compensation drive signal is generated through a set control algorithm;

[0062] The compensation drive signal is used to feedback control the drive element of the vibration device or the machine tool motion system to achieve micro-adjustment of the position of the tool relative to the workpiece to correct the cutting depth error and realize adaptive vibration cutting processing of the workpiece surface contour.

[0063] To achieve the above-mentioned purpose, the second embodiment of the present application proposes an adaptive vibration cutting device based on piezoelectric sensing phase signal, comprising:

[0064] A reference phase acquisition module is used to install a piezoelectric sensor between the tool holder and the tool of the vibration device, collect the output signal of the piezoelectric sensor in a vibration-only, non-cutting state, and extract its phase as a reference phase;

[0065] a processing state signal acquisition and phase difference calculation module, for controlling the machine tool to bring the tool into contact with the workpiece for vibration cutting processing, acquiring the output signal of the piezoelectric sensor at this time, and calculating the phase difference with the reference phase;

[0066] A cutting depth back-calculation module is used to back-calculate the real-time cutting depth of the current vibration cutting process based on the phase difference combined with a pre-calibrated cutting force correction coefficient and a cutting depth index of cutting depth influence;

[0067] A compensation execution module is used to compare the real-time cutting depth with the set cutting depth to obtain a cutting depth difference, input the cutting depth difference into a closed-loop feedback controller to generate a compensation drive signal, and apply the compensation drive signal to the driving element of the vibration device or the machine tool.

[0068] To achieve the above-mentioned purpose, a third embodiment of the present application provides an electronic device, comprising: a processor, and a memory communicatively connected to the processor;

[0069] The memory stores computer-executable instructions;

[0070] The processor executes the computer-executable instructions stored in the memory to implement the method as described in any one of the first aspects.

[0071] To achieve the above-mentioned purpose, the fourth embodiment of the present application proposes a computer-readable storage medium, which stores computer-executable instructions. When the computer-executable instructions are executed by a processor, they are used to implement the method as described in any one of the first aspects.

[0072] To achieve the above-mentioned objectives, the fifth embodiment of the present application proposes a computer program product, which implements any one of the methods in the first aspect when executed by a processor.

[0073] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0075] Figure 1 A schematic flow chart of an adaptive vibration cutting method based on piezoelectric sensing phase signals provided in an embodiment of the present application;

[0076] Figure 2 This is a schematic diagram of the closed-loop feedback control principle for adaptive surface contouring during vibration machining provided by an embodiment of the present application;

[0077] Figure 3 Schematic diagram of the installation and vibration of the piezoelectric sensor provided in the embodiment of the present application;

[0078] Figure 4 A schematic diagram of the output signal of the piezoelectric sensor provided in an embodiment of the present application;

[0079] Figure 5 This is a schematic diagram of the adaptive tool setting control principle for vibration machining provided in an embodiment of the present application. DETAILED DESCRIPTION

[0080] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0081] Figure 1This is a flow chart of an adaptive vibration cutting method based on piezoelectric sensing phase signal provided in an embodiment of the present application. Figure 2 This is a schematic diagram of the closed-loop feedback control principle for the adaptive surface profile of vibration machining provided in the embodiment of this application. Figure 1 and Figure 2 , the method comprises the following steps:

[0082] Step 101: Install a piezoelectric sensor between a tool holder and a tool of a vibration device, collect an output signal of the piezoelectric sensor in a vibration-only, non-cutting state, and extract its phase as a reference phase.

[0083] The basic form of vibration cutting is to install the tool on the tool holder of the vibration device, apply the external excitation signal to the driving element of the vibration device (piezoelectric actuator, voice coil motor, etc.) to generate vibration, and then transmit it to the tool through the main structure of the vibration device. At the same time, the machine tool drives the entire vibration device (including the tool) to perform nominal cutting and feed motion to achieve vibration cutting of the workpiece surface.

[0084] In actual machining, cutting force can be simplified as a spatial vector. While the magnitude and direction of the cutting force at the same point in each cycle typically vary for vibration cutting processes with different parameters (tool parameters, vibration trajectory parameters, and cutting motion parameters), for vibration cutting processes with the same parameters, the direction of the cutting force at the same point in each cycle is generally the same, and its magnitude is positively correlated with the depth of cut. Therefore, in theory, only one force component needs to be monitored, combined with calibration data, to achieve depth of cut perception.

[0085] In order to shorten the transmission path of cutting force and reduce the errors caused by machining accuracy and joint surface, the embodiment of the present application designs the piezoelectric sensor between the cutting tool and the tool holder of the vibration device, and the center of the piezoelectric sensor is designed with a through hole for connection. Figure 3 As shown, the pre-tightening bolt passes through the through holes on the tool and the piezoelectric sensor and is connected to the thread of the tool holder to fix the tool and the piezoelectric sensor and provide a certain pre-tightening force for the piezoelectric sensor. The polarization direction of the piezoelectric sensor is designed to be along the axial direction of the through hole to monitor the cutting force in this direction.

[0086] Furthermore, in the embodiment of the present application, signal lines are drawn from both sides of the piezoelectric sensor in the polarization direction, and then connected to the signal acquisition and processing equipment after passing through a charge amplifier. In actual operation, to avoid distortion of the collected signal, the signal acquisition frequency should be much higher than the external excitation vibration frequency. At the same time, because the frequency of the external excitation vibration is usually constant, a bandpass filter can be added to filter out noise signals and improve the signal-to-noise ratio of the piezoelectric sensor output signal.

[0087] In general, when the tool vibration caused by external excitation is not perpendicular to the polarization direction of the piezoelectric sensor, the component of the vibration in the polarization direction will cause the piezoelectric sensor to have a certain signal output even when it is unloaded (only vibrating without cutting).

[0088] Therefore, in the present embodiment, to achieve real-time perception of the depth of cut during vibration machining, the output pattern of the piezoelectric sensor in an unloaded state (i.e., vibrating only, not in contact with the workpiece) is first modeled and analyzed. The excitation source of the vibration device can be activated to drive the tool, piezoelectric sensor, preload bolt, etc. to vibrate synchronously with a simple harmonic signal. The simple harmonic signal output by the piezoelectric sensor is then monitored, and the phase of this signal is calculated and recorded as a reference phase.

[0089] Specifically, under external excitation, the tool, piezoelectric sensor, and pre-tightening bolt generate simple harmonic vibration along the polarization direction, and the vibration displacement is:

[0090] x(t)=Asin(2πft)

[0091] Where A is the amplitude of the component of the vibration caused by the external excitation in the polarization direction of the piezoelectric sensor, and f is the vibration frequency of the external excitation. Since the initial phase has no substantial effect on the vibration processing process in the embodiment of this application, it is taken as zero to simplify the expression.

[0092] Then, the present application can calculate the vibration velocity v and acceleration a of the tool, piezoelectric sensor, and pre-tightening bolt based on the vibration displacement. The formula is:

[0093]

[0094] In the embodiment of the present application, the tool, piezoelectric sensor and pre-tightening bolt form a series structure, and their masses will jointly participate in the dynamic response during the vibration process. Since the bolt mass contributes to the force of the system in an uneven distribution, the mass correction coefficient k is introduced. b1 and k b2 Used for correction at both ends. At this time, when there is only vibration but no cutting, according to Newton's second law, the force F on the upper and lower sides of the piezoelectric sensor caused by external excitation vibration can be obtained. 1v and F 2v They are:

[0095] F 1v (t)=(m t +k b1 m b )·a(t)

[0096] F 2v (t)=(m t +m p +k b2 m b)·a(t)

[0097] Among them, m t is the mass of the tool, m p is the mass of the piezoelectric sensor, and the mass of the pre-tightened bolt is m b , k b1 and k b2 It is the correction factor for preloaded bolts.

[0098] In this embodiment of the present application, the average force F is obtained by taking the average force at both ends. v expression:

[0099]

[0100] Among them, m eq is the equivalent mass of the piezoelectric sensor, which represents the equivalent dynamic inertia of the entire tool-piezoelectric-bolt structure to the piezoelectric sensor. The specific form is:

[0101]

[0102] In the embodiment of the present application, the polarization direction of the piezoelectric sensor is not perpendicular to the excitation direction, so the vibration component in this direction can be effectively converted into a charge signal. According to the principle of the piezoelectric effect, the force will cause charges of opposite polarity to accumulate on both sides of the piezoelectric material, which are then amplified by a charge amplifier and output as a voltage signal. The voltage output expression is:

[0103] U v (t) = k CA ·d 33 ·F v (t)

[0104] Among them, d 33 is the piezoelectric constant of the piezoelectric sensor along the polarization direction, k CA is the voltage amplification factor of the charge amplifier.

[0105] Substituting the above formula, the output voltage signal of the piezoelectric sensor under the condition of no cutting load and only excited vibration can be further written as:

[0106] U v (t)=-4π 2 f 2 k CA d 33 m eq Asin(2πft)

[0107] The above signal is in standard simple harmonic form, with fixed amplitude and phase, where the amplitude and phase They are:

[0108]

[0109] In the embodiment of the present application, the phase of the output signal of the piezoelectric sensor in the non-cutting state is As a reference phase, it is used for phase comparison in subsequent vibration cutting state, so as to realize back calculation of cutting depth and dynamic compensation control.

[0110] Step 102 : Control the machine tool to make the tool contact the workpiece to perform vibration cutting processing, collect the output signal of the piezoelectric sensor at this time, and calculate the phase difference with the reference phase.

[0111] In an embodiment of the present application, the tool is controlled by the machine tool to contact the workpiece and perform vibration cutting processing, and the simple harmonic signal output by the piezoelectric sensor at this time is monitored again, and the phase of the signal and the phase difference with the reference phase are calculated.

[0112] Similarly, when the cutting force acts on the tool, the cutting force will be transmitted to the piezoelectric sensor because the tool, piezoelectric sensor, and tool holder form a series system. For ultra-precision vibration cutting with a shallow cutting depth, the cutting force is positively correlated with the strain rate (i.e., speed), so the cutting force F c (t) can be approximately expressed as:

[0113] F c (t) = kh n v(t)

[0114] Among them, h is the cutting depth of vibration machining, n is the correction index of the cutting depth effect, which is used to characterize the nonlinear relationship between cutting force and cutting depth under different materials; k is the correction coefficient of cutting force, which is related to factors such as the material and shape of the workpiece and tool.

[0115] The voltage output response of the cutting force to the piezoelectric sensor is obtained as follows:

[0116] U c (t) = k CA ·d 33 ·F c (t)

[0117] In the actual vibration cutting process, the amplitude of the tool usually remains stable and the influence of the cutting depth can be approximately ignored. Since the system is a linear system, it can be directly superimposed. Therefore, in the actual vibration cutting process, the output voltage U of the piezoelectric sensor is o (t) is:

[0118] U o (t) = U v (t)+U c (t)

[0119] Substituting in:

[0120] U o (t)=-2πfk CA d 33 A(2πfm eq sin(2πft)-kh n cos(2πft))

[0121] The signal is a simple harmonic function with synthetic amplitude and phase, which can be further rewritten by the auxiliary angle formula. That is, according to the auxiliary angle formula, the output voltage U of the piezoelectric sensor during the vibration cutting process of the tool and the workpiece is: o (t) can be equivalently expressed as:

[0122]

[0123] Furthermore, the amplitude of the output signal of the piezoelectric sensor in the vibration cutting state is and phase They are:

[0124]

[0125] Therefore, the signal difference between the actual vibration cutting process and the vibration without cutting is:

[0126]

[0127] Where ΔA U is the difference in signal amplitude between the actual vibration cutting process and the vibration without cutting, It is the signal phase difference between the actual vibration cutting process and the signal phase difference between the vibration without cutting.

[0128] Step 103 , based on the phase difference, combined with the pre-calibrated correction coefficient of the cutting force and the cutting depth index of the cutting depth, the real-time cutting depth of the current vibration cutting process is obtained by reverse calculation.

[0129] Because the amplitude of the piezoelectric sensor output signal caused by external excitation vibration is usually much larger than the signal output amplitude caused by cutting, the change in the amplitude of the piezoelectric sensor output signal before and after vibration cutting is relatively small, especially when the cutting depth is small. Even after the voltage is amplified by the charge amplifier, when the voltage resolution of the acquisition device is insufficient, it is difficult to perceive the actual cutting depth by detecting the change in the voltage signal amplitude, or the perception accuracy of the cutting depth is insufficient. In contrast, when the sampling rate is high, the phase change of the piezoelectric sensor output signal caused by vibration cutting will be more obvious, such as Figure 4 shown.

[0130] It should be noted that, because the cutting force of vibration cutting processing is affected by factors such as the material and shape of the workpiece and the tool, which cannot be ignored, it is necessary to pre-calibrate the correction coefficient k of the cutting force and the correction index n of the cutting depth. There are many ways to choose from. The embodiment of the present application lists one of the calibration methods: select the material to be processed to make a sample, and pre-polish or cut it to obtain a sufficiently high surface quality, install it on the machine tool and adjust it to be parallel to the moving axis. Use this system to carry out a set of vibration cutting processing tests with different cutting depths, record the phase difference of the output signal of the piezoelectric sensor in each set of tests, and measure the actual cutting depth of each set of tests through equipment such as white light three-dimensional topography interferometer, establish a mapping relationship between the phase difference and the actual cutting depth, and perform parameter calibration accordingly. After completing the parameter calibration, the embodiment of the present application can process workpieces with general surface quality, monitor the phase difference of the simple harmonic signal output by the piezoelectric sensor relative to the reference phase during the vibration processing in real time, and the real-time cutting depth can be obtained by inverse calculation based on the parameter calibration results.

[0131] In one embodiment of the present application, the phase difference of the output signal of the piezoelectric sensor before and after the vibration cutting process is detected. The cutting depth of vibration cutting is calculated as follows:

[0132]

[0133] Among them, k is the correction coefficient of the pre-calibrated cutting force, and n is the cutting depth index of the pre-calibrated cutting depth effect.

[0134] In special cases, when the tool vibration caused by external excitation is perpendicular to the polarization direction of the piezoelectric sensor, ideally the piezoelectric sensor will not generate signal output due to external excitation. At this time, the signal output of the piezoelectric sensor is the signal output caused by the cutting force. The cutting force can be directly calculated based on the piezoelectric constant of the piezoelectric sensor and the amplification factor of the charge amplifier, and then the current cutting depth can be obtained.

[0135] It should also be noted that, in the embodiment of the present application, before controlling the machine tool to make the tool contact with the workpiece for vibration cutting, the tool is controlled by the machine tool to vibrate and test-cut on the surface of the workpiece, and the above-mentioned method is used to monitor the cutting depth during the test cutting process. When the perceived cutting depth obtained by reverse calculation is less than a certain threshold value, it is considered that the tool is not in contact with the workpiece at this time, and the distance between the tool and the workpiece can be reduced before the next test cutting. Until the perceived cutting depth obtained by reverse calculation is greater than the threshold value, it is considered that the tool is in contact with the workpiece at this time, and the test cutting and tool setting are completed. If there are no special requirements, the tool setting process can also omit parameter calibration and cutting depth reverse calculation, and directly judge based on whether the phase difference is non-zero, such as Figure 5 shown.

[0136] Step 104 : compare the real-time cutting depth with the set cutting depth to obtain a cutting depth difference, input the cutting depth difference into a closed-loop feedback controller to generate a compensation drive signal, and apply the compensation drive signal to the driving element of the vibration device or the machine tool.

[0137] After extracting the phase difference and calculating the actual depth of cut through back-calculation, the present embodiment compares the real-time depth of cut with the target depth of cut preset in the machining task to calculate the depth of cut error under the current cutting state. This error reflects the deviation between the actual machining state and the target state caused by uneven workpiece surface, tool clamping deviation, thermal deformation of the equipment, or other disturbances.

[0138] Furthermore, the cutting depth error is fed into a closed-loop feedback controller in real time. This controller can use proportional-integral-derivative (PID) control, model predictive control (MPC), fuzzy control, or other algorithms suitable for ultra-precision control to calculate the corresponding compensation drive signal based on the error size, change trend, and dynamic response characteristics.

[0139] Finally, the compensation signal is directly applied to the vibration device's drive element, such as a piezoelectric actuator or voice coil motor. It can also be adjusted by controlling the machine tool's feed axis (such as the Z axis), thereby achieving micro-corrections for the tool's displacement along the machining direction. This adjustment process dynamically maintains the set depth of cut or executes depth-of-cut changes without interrupting the process, ensuring the consistency and accuracy of the machined structure.

[0140] In a preferred embodiment of the present application, after completing the initial adaptive tool setting (i.e. confirming that the tool is in contact with the workpiece), adaptive surface profile vibration cutting processing can be carried out directly. During this processing, the tool moves along the set path to the workpiece, and the system continuously senses the actual cutting depth at each point and compares it with the target cutting depth in real time. All cutting depth errors are input into the feedback controller in real time, and the drive system is adjusted according to the feedback to achieve dynamic compensation of cutting depth. This closed-loop control process is not only applicable to constant cutting depth processing of general surface quality workpieces, thereby greatly improving efficiency and surface quality stability, but also applicable to microstructure processing tasks with gradients, varying curvatures or special depth distributions. For example, in an embodiment of the present application, a target cutting depth curve that changes with the tool path can be set according to the CAD model or functional requirements. The system will automatically adjust the tool position based on the sensing results to achieve precision manufacturing of complex features such as gradient cutting depth structures and functional microtextures. In addition, the adaptive control strategy also has good versatility and scalability. It can be used for planar workpieces and can also be extended to irregular structures such as free-form surfaces and multi-curvature complex surfaces, and has significant industrial application potential.

[0141] In summary, step 104 introduces the cutting depth error into the closed-loop control system and cooperates with the high-response drive device to construct an adaptive vibration cutting system that integrates real-time perception, feedback adjustment, and precision machining. It not only effectively solves the depth consistency problem in microstructure machining, but also significantly expands the functional boundaries and application scope of vibration cutting technology.

[0142] To implement the above embodiment, the present application also proposes an adaptive vibration cutting device based on piezoelectric sensing phase signals. The device includes:

[0143] A reference phase acquisition module is used to install a piezoelectric sensor between the tool holder and the tool of the vibration device, collect the output signal of the piezoelectric sensor when it is only vibrating and not cutting, and extract its phase as the reference phase;

[0144] The processing state signal acquisition and phase difference calculation module is used to control the machine tool to make the tool contact with the workpiece to perform vibration cutting processing, collect the output signal of the piezoelectric sensor at this time, and calculate the phase difference with the reference phase;

[0145] The cutting depth back-calculation module is used to calculate the real-time cutting depth of the current vibration cutting process based on the phase difference combined with the pre-calibrated cutting force correction coefficient and the cutting depth index of the cutting depth;

[0146] The compensation execution module is used to compare the real-time cutting depth with the set cutting depth to obtain the cutting depth difference, input the cutting depth difference into the closed-loop feedback controller to generate a compensation drive signal, and apply the compensation drive signal to the driving element of the vibration device or the machine tool.

[0147] Regarding the apparatus in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0148] In order to implement the above embodiments, the present application also proposes an electronic device, comprising: a processor, and a memory communicatively connected to the processor; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory to implement the method provided by the above embodiments.

[0149] In order to implement the above embodiments, the present application also proposes a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement the methods provided by the above embodiments.

[0150] In order to implement the above embodiments, the present application also proposes a computer program product, including a computer program, which implements the methods provided by the above embodiments when executed by a processor.

[0151] The collection, storage, use, processing, transmission, provision and disclosure of user personal information involved in this application are in compliance with relevant laws and regulations and do not violate public order and good morals.

[0152] It is important to note that personal information collected from users should be used for legitimate and reasonable purposes and should not be shared or sold beyond these legitimate uses. Furthermore, such collection / sharing should be conducted only after receiving the user's informed consent, including but not limited to notifying the user to read the user agreement / user notice and sign an agreement / authorization that includes the relevant user information before using the feature. Furthermore, any necessary steps must be taken to safeguard and secure access to such personal information and ensure that others with access to personal information comply with its privacy policy and procedures.

[0153] This application contemplates providing implementations that allow users to selectively block the use or access of personal information data. Specifically, this disclosure contemplates providing hardware and / or software to prevent or block access to such personal information data. Risks can be minimized by limiting data collection and deleting data once it is no longer needed. Furthermore, where applicable, such personal information can be de-identified to protect user privacy.

[0154] In the descriptions of the foregoing embodiments, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually inconsistent.

[0155] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0156] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application belong.

[0157] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). Furthermore, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing it in another suitable manner if necessary, and then storing it in a computer memory.

[0158] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0159] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0160] In addition, the functional units in the various embodiments of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into a module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0161] The storage medium mentioned above may be a read-only memory, a magnetic disk, or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application. Persons skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

[0162] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this application can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of this application can be achieved. This is not limited herein.

[0163] The above specific embodiments do not constitute a limitation on the scope of protection of this application. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application shall be included within the scope of protection of this application.

Claims

1. An adaptive vibration cutting method based on piezoelectric sensing phase signal, characterized in that: The following steps are involved: A piezoelectric sensor is installed between the tool holder and the tool of the vibration device, an output signal of the piezoelectric sensor in a vibration-only, non-cutting state is collected, and its phase is extracted as a reference phase; Controlling the machine tool to make the tool contact the workpiece to perform vibration cutting processing, collecting the output signal of the piezoelectric sensor at this time, and calculating the phase difference with the reference phase; The real-time cutting depth of the current vibration cutting process is obtained by reverse calculation based on the phase difference, a correction coefficient of the pre-calibrated cutting force and a cutting depth index affected by the cutting depth; The real-time cutting depth is compared with the set cutting depth to obtain a cutting depth difference, the cutting depth difference is input into a closed-loop feedback controller to generate a compensation drive signal, and the compensation drive signal is applied to the driving element of the vibration device or the machine tool.

2. The method according to claim 1, characterized in that The method comprises: installing a piezoelectric sensor between the tool holder and the tool of the vibration device, collecting an output signal of the piezoelectric sensor in a vibration-only, non-cutting state, and extracting its phase as a reference phase. The piezoelectric sensor is clamped between the tool and the tool holder through a through-hole structure, and an axial pre-tightening force is provided by a pre-tightening bolt; signal lines are respectively led out on both sides of the polarization direction of the piezoelectric sensor, and are connected to the signal acquisition and processing equipment after passing through a charge amplifier; Under external excitation, the tool, piezoelectric sensor and pre-tightening bolt generate simple harmonic vibration along the polarization direction, and the vibration displacement is: x(t)=Asin(2πft) Where A is the amplitude of the component of the vibration caused by external excitation in the polarization direction of the piezoelectric sensor, and f is the external excitation vibration frequency; The vibration velocity v and acceleration a of the tool, piezoelectric sensor, and pre-tightening bolt are calculated based on the vibration displacement. The formula is: When there is only vibration but no cutting, according to Newton's second law, the force F on the upper and lower sides of the piezoelectric sensor caused by external excitation vibration is obtained 1v and F 2v They are: F 1v (t)=(m t +k b1 m b )·a(t) F 2v (t)=(m t +m p +k b2 m b )·a(t) Among them, m t is the mass of the tool, m p is the mass of the piezoelectric sensor, and the mass of the pre-tightened bolt is m b , k b1 and k b2 It is the correction factor for preloaded bolts; The average force F on the piezoelectric sensor caused by external excitation vibration v Expressed as: Among them, m eq is the equivalent mass of the piezoelectric sensor, expressed as: The average force F v Converted into voltage output, the output voltage of the piezoelectric sensor is: U v (t)=k CA ·d 33 ·F v (t)=-4π 2 f 2 k CA d 33 m eq Asin(2πft) Among them, d 33 is the piezoelectric constant of the piezoelectric sensor along the polarization direction, k CA is the voltage amplification factor of the charge amplifier; The amplitude of the output signal of the piezoelectric sensor when it is only vibrating and not cutting and phase They are: Among them, the phase as a reference signal.

3. The method according to claim 2, characterized in that The controlling of the machine tool causes the tool to contact the workpiece to perform vibration cutting processing, collects the output signal of the piezoelectric sensor at this time, and calculates the phase difference with the reference phase, including: During the vibration cutting process between the tool and the workpiece, the output voltage U of the piezoelectric sensor is collected. o (t), where U o (t) is the output under the combined action of vibration and cutting force, which satisfies the superposition principle and is expressed as: U o (t)=U v (t)+U c (t) Among them, U c (t) = k CA ·d 33 ·F c (t) is the output voltage of the piezoelectric sensor caused by the cutting force, F c (t) is the cutting force, which is approximately: F c (t)=kh n ·v(t) Where h is the cutting depth of vibration machining, n is the correction index of cutting depth effect, and k is the correction coefficient of cutting force; Substituting in: U o (t)=-2πfk CA d 33 A(2πfm eq sin(2πft)-kh n cos(2πft)) According to the auxiliary angle formula, the output voltage U of the piezoelectric sensor during the vibration cutting process between the tool and the workpiece is o (t) can be equivalently expressed as: The amplitude of the output signal of the piezoelectric sensor in the vibration cutting state and phase They are: Therefore, the signal difference between the actual vibration cutting process and the vibration without cutting is: Where ΔA U is the difference in signal amplitude between the actual vibration cutting process and the vibration without cutting, It is the signal phase difference between the actual vibration cutting process and the signal phase difference between the vibration without cutting.

4. The method according to claim 3, characterized in that The real-time cutting depth of the current vibration cutting process is obtained by reversely calculating the phase difference in combination with a pre-calibrated cutting force correction coefficient and a cutting depth index affected by the cutting depth, including: The phase difference Substitute the following formula to calculate the current cutting depth h: Among them, k is the correction coefficient of the pre-calibrated cutting force, and n is the cutting depth index of the pre-calibrated cutting depth effect.

5. The method according to claim 4, characterized in that Before controlling the machine tool to make the tool contact with the workpiece for vibration cutting, it also includes: Before machining, the machine tool controls the tool to vibrate and test-cut on the workpiece surface, and the perceived cutting depth during the test-cut is calculated in reverse. If the perceived cutting depth is less than the tool setting threshold, it is considered that the tool is not in contact with the workpiece at this time. The distance between the tool and the workpiece is reduced and the next trial cutting is performed until the perceived cutting depth obtained by backcalculation is greater than the tool setting threshold. It is considered that the tool is in contact with the workpiece at this time, and the trial cutting and tool setting are completed.

6. The method according to claim 5, characterized in that The method comprises: comparing the real-time cutting depth with the set cutting depth to obtain a cutting depth difference, inputting the cutting depth difference into a closed-loop feedback controller to generate a compensation drive signal, and applying the compensation drive signal to a driving element of a vibration device or a machine tool, including: During the vibration cutting process, the difference between the real-time cutting depth obtained by inverse calculation based on the phase difference and the set cutting depth is calculated to obtain a cutting depth error; The cutting depth error is sent as input to a closed-loop feedback controller, and a cutting depth compensation drive signal is generated through a set control algorithm; The compensation drive signal is used to feedback control the drive element of the vibration device or the machine tool motion system to achieve micro-adjustment of the position of the tool relative to the workpiece to correct the cutting depth error and realize adaptive vibration cutting processing of the workpiece surface contour.

7. An adaptive vibration cutting device based on piezoelectric sensing phase signal, characterized in that: include: A reference phase acquisition module is used to install a piezoelectric sensor between the tool holder and the tool of the vibration device, collect the output signal of the piezoelectric sensor in a vibration-only, non-cutting state, and extract its phase as a reference phase; a processing state signal acquisition and phase difference calculation module, for controlling the machine tool to bring the tool into contact with the workpiece for vibration cutting processing, acquiring the output signal of the piezoelectric sensor at this time, and calculating the phase difference with the reference phase; A cutting depth back-calculation module is used to back-calculate the real-time cutting depth of the current vibration cutting process based on the phase difference combined with a pre-calibrated cutting force correction coefficient and a cutting depth index of cutting depth influence; A compensation execution module is used to compare the real-time cutting depth with the set cutting depth to obtain a cutting depth difference, input the cutting depth difference into a closed-loop feedback controller to generate a compensation drive signal, and apply the compensation drive signal to the driving element of the vibration device or the machine tool.

8. An electronic device, characterized in that: include: a processor, and a memory communicatively connected to the processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory to implement the method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 6 when executed by a processor.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 6 when the computer program is executed by a processor.

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