Ultrasonic Machining Quality Control Method, System and Electronic Device for Monitoring Tool Wear

Abstract

The present invention discloses an ultrasonic machining quality control method, system and electronic device for monitoring tool wear, which relates to the fields of mechanical machining and system control. The ultrasonic machining quality control method for monitoring tool wear provided by the present invention controls the reactive power to be constant according to the real-time resistance of the transducer to achieve power tracking; according to the real-time impedance relationship of the transducer, the real-time resonant frequency of the transducer is obtained through eigenvalue calculation and curve fitting to achieve frequency tracking; the amplitude of the transducer is stabilized by controlling the feedback current to be constant, ensuring the stability of the ultrasonic machining effect, and obtaining the real-time constant current and constant amplitude voltage of the system; on the basis of ensuring the stability of the ultrasonic machining effect by constant current and constant amplitude, the tool wear state is monitored by real-time monitoring of the constant current and constant amplitude voltage of the transducer, and accurate control of the ultrasonic machining quality is achieved without using a force sensor.

Description

Technical Field

[0001] The present invention relates to the fields of machining and system control, and particularly to an ultrasonic machining quality control method, system and electronic device for monitoring tool wear. Background Art

[0002] Most of the ultrasonic machining frequency resonance controls are used, and during the ultrasonic machining process, the control of machining quality stability is rarely carried out. Fluctuating machining is an advanced ultrasonic machining method, and good improvement in machining quality has been achieved in cutting machining, such as high-speed precision, cutting and extrusion strengthening, etc. However, how to ensure the machining quality stability problem caused by the tool state during the machining process has become a key problem in the application of this technology in the machining of large integral components.

[0003] The amplitude of ultrasonic machining is a key parameter determining its machining quality, and it changes with the tool state. Experiments show that the tool state increases the cutting force, resulting in a smaller diameter of the impedance circle of the transducer and reducing the amplitude of ultrasonic machining. The quality of ultrasonic machining is sensitive to the change of amplitude. Therefore, real-time monitoring of the tool state and control of amplitude stability are crucial for improving the vibration performance of the transducer.

[0004] After the tool state changes, in the frequency tracking drive resonance circuit, the resonance frequency changes, and its value is Δf, but the change value Δf of the resonance frequency does not change monotonically with the cutting force, so the tool state cannot be monitored by Δf. In the non-phase-locked drive resonance circuit, the value of the impedance phase change is ΔΦ, but ΔΦ also does not change monotonically with the cutting force. Therefore, the tool state cannot be monitored by ΔΦ either. The cutting force changes monotonically with the tool state, and the tool state can be monitored by using the change of the cutting force. A reasonable cutting force monitoring method is to attach a force sensor to the cutting tool handle, but limited by problems such as the rotary machining mode of the tool handle, this solution has not been practical yet. Currently, the cutting force monitoring method mainly uses means such as a dynamometer, but the dynamometer must be fixed on the machine tool workbench, and special tooling needs to be designed, and even the machine tool structure needs to be modified. Moreover, in actual machining production, force sensors such as dynamometers cannot be used, and there are many difficulties in monitoring the tool state in industrial production. Summary of the Invention

[0005] To solve the above problems existing in the prior art, the present invention provides an ultrasonic machining quality control method, system and electronic device for monitoring tool wear.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] An ultrasonic machining quality control method for monitoring tool wear, comprising:

[0008] Obtain the dynamic resistance and dynamic reactance of the transducer during the ultrasonic machining process, and determine the time-domain impedance of the transducer in real time based on the dynamic resistance and dynamic reactance of the transducer, so as to obtain the time-domain impedance relationship;

[0009] Perform Laplace transform on the time-domain impedance relationship to obtain the frequency-domain impedance curve of the transducer;

[0010] Fit the frequency-domain impedance curve of the transducer to obtain a curve with a unique pair of conjugate characteristic roots;

[0011] Obtain the resonant frequency of the transducer in real time based on the curve with a unique pair of conjugate characteristic roots to achieve frequency tracking;

[0012] By tracking the feedback current in real time, obtain the dynamic total resistance and dynamic total reactance of the ultrasonic system in real time, and determine the proportion of active power and reactive power in the output power based on the dynamic total resistance and dynamic total reactance of the ultrasonic system. Adjust the output power based on the proportion to achieve power tracking, and obtain the constant-current and constant-amplitude voltage of the ultrasonic system in real time;

[0013] During the ultrasonic machining process, detect in real time the difference between the constant-current and constant-amplitude voltage of the ultrasonic system and the constant-current and constant-amplitude voltage in the tool dulling state, determine the tool wear state based on the difference, and judge whether the current tool can complete the machining of the entire process based on the tool wear state; The tool wear states include: no-load state, cutting new tool state, and tool dulling state.

[0014] Optionally, before obtaining the dynamic resistance and dynamic reactance of the transducer during the ultrasonic machining process and determining the time-domain impedance of the transducer in real time based on the dynamic resistance and dynamic reactance of the transducer, the method further includes:

[0015] Obtain the constant-current and constant-amplitude voltage and feedback current values in different tool wear states under the cutting workpiece part or cutting parameters through experiments.

[0016] Optionally, the time-domain impedance of the transducer is:

[0017]

[0018] where Z t is the time-domain impedance of the transducer at time t, R t is the dynamic resistance of the transducer at time t, X t is the dynamic reactance of the transducer at time t, ω is the vibration angular frequency of the transducer, C0 is the static capacitance of the transducer, R1 is the resistance value of the dynamic resistance, L1 is the inductance of the dynamic inductor, C p is the total capacitance value of the transducer considering the static capacitance, and j is the imaginary part symbol in the complex plane.

[0019] Optionally, a series of response curve data points are obtained in the S-plane at a set distance from the imaginary axis through an interpolation calculation method, and the frequency-domain impedance curve of the transducer is fitted according to the obtained response curve data points to obtain a curve with a unique pair of conjugate characteristic roots.

[0020] Optionally, the relationship between the dynamic resistance and the dynamic reactance of the transducer is as follows:

[0021]

[0022] In the formula, R t is the dynamic resistance of the transducer at time t, X t is the dynamic reactance of the transducer at time t, ω p is the parallel resonance angular frequency, C0 is the static capacitance of the transducer, and R1 is the resistance value of the dynamic resistance.

[0023] According to the specific embodiments provided by the present invention, the following technical effects are disclosed:

[0024] The ultrasonic machining quality control method for monitoring tool wear provided by the present invention controls the reactive power to be constant according to the real-time resistance of the transducer to achieve power tracking; according to the real-time impedance relationship of the transducer, the real-time resonance frequency of the transducer is obtained through characteristic root calculation and curve fitting to achieve frequency tracking; the amplitude of the transducer is stabilized by controlling the feedback current to be constant, ensuring the stability of the ultrasonic machining effect and obtaining the real-time constant-current and constant-amplitude voltage of the system; on the basis of ensuring the stability of the ultrasonic machining effect with constant current and constant amplitude, the tool wear state is monitored by real-time monitoring of the constant-current and constant-amplitude voltage of the transducer, and the precise control of ultrasonic machining quality is achieved without using a force sensor.

[0025] Furthermore, the present invention also provides an ultrasonic machining quality control system for monitoring tool wear to apply the above ultrasonic machining quality control method for monitoring tool wear; the system includes:

[0026] A time-domain impedance relationship determination module, configured to obtain the dynamic resistance and the dynamic reactance of the transducer during ultrasonic machining, and based on the dynamic resistance and the dynamic reactance of the transducer, determine the time-domain impedance of the transducer in real time to obtain a time-domain impedance relationship;

[0027] A frequency-domain impedance curve determination module, configured to perform a Laplace transform on the time-domain impedance relationship to obtain the frequency-domain impedance curve of the transducer;

[0028] A curve fitting module, configured to fit the frequency-domain impedance curve of the transducer to obtain a curve with a unique pair of conjugate characteristic roots;

[0029] A frequency tracking module, configured to obtain the resonant frequency of a transducer in real time based on a curve having a unique pair of conjugate characteristic roots, so as to achieve frequency tracking;

[0030] A power tracking module, configured to obtain the dynamic total resistance and dynamic total reactance of an ultrasonic system in real time by tracking a feedback current in real time, determine the proportions of active power and reactive power in the output power based on the dynamic total resistance and dynamic total reactance of the ultrasonic system, adjust the output power based on the proportions, so as to achieve power tracking, and obtain a constant-current and constant-amplitude voltage of the ultrasonic system in real time;

[0031] A tool wear state determination module, configured to detect in real time the difference between the constant-current and constant-amplitude voltage of the ultrasonic system and the constant-current and constant-amplitude voltage in a tool dull state during an ultrasonic machining process, determine the tool wear state based on the difference, and judge whether the current tool can complete the machining of an entire process based on the tool wear state; the tool wear states include: an idle state, a cutting new tool state, and a tool dull state.

[0032] An electronic device, comprising:

[0033] A memory, configured to store a computer program;

[0034] A processor, connected to the memory, configured to retrieve and execute the computer program to implement the above-mentioned ultrasonic machining quality control method for monitoring tool wear.

[0035] Optionally, the memory is a computer-readable storage medium.

[0036] Since the technical effects achieved by the above two structures provided by the present invention are the same as those achieved by the ultrasonic machining quality control method for monitoring tool wear provided by the present invention, they will not be elaborated herein. Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts;

[0038] Figure 1 It is a flowchart of the ultrasonic machining quality control method for monitoring tool wear provided by the present invention;

[0039] Figure 2 It is a schematic diagram of an equivalent circuit model of a transducer provided by the present invention;

[0040] Figure 3 It is a schematic diagram of an impedance circle model of a transducer provided by the present invention;

[0041] Figure 4 Schematic diagram of the amplitude stabilization control principle provided by the present invention;

[0042] Figure 5 Example diagram of the impedance circle changing with the load provided by the present invention;

[0043] Figure 6 Flow chart of the amplitude stabilization control provided by the present invention. Specific implementation manner

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] The purpose of the present invention is to provide an ultrasonic machining quality control method, system and electronic device for monitoring tool wear, which can utilize the change of the working state of the transducer to monitor the tool state in real time during ultrasonic machining, and perform amplitude stabilization control according to the detection result to make the ultrasonic machining process stable. Moreover, the present invention does not require the use of a force sensor, and can solve the problem of tool state monitoring in actual machining production while improving the machining quality.

[0046] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0047] As Figure 1 shown, the ultrasonic machining quality control method for monitoring tool wear provided by the present invention includes:

[0048] Step 100: Obtain the dynamic resistance and dynamic reactance of the transducer during ultrasonic machining, and based on the dynamic resistance and dynamic reactance of the transducer, determine the time-domain impedance of the transducer in real time to obtain a time-domain impedance relationship.

[0049] In the actual application process, the ultrasonic piezoelectric transducer in ultrasonic machining is a strongly non-linear time-varying system, and its electrical characteristics can be expressed in the form of a series connection of a resistor and an inductor, that is, the transducer impedance is Z = R + jX, where the reactance can be regarded as a series connection of a capacitor and an inductor. Then R is the dynamic resistance of the transducer, C is the dynamic capacitance of the transducer, L is the dynamic inductance of the transducer, and X is the reactance. As Figure 2 shown in the equivalent circuit model of the transducer, assume that the resistance value of the dynamic resistance is R1, the capacitance value of the dynamic capacitance is C1, the inductance of the dynamic inductance is L1, and the static capacitance of the transducer is C0. Then the mechanical resonance frequency of the transducer is:

[0050]

[0051] f is also known as the series resonance frequency of the transducer. When the transducer vibrates at frequency f, the vibration amplitude reaches the maximum value, which is the ideal machining state. As Figure 3 shown, during the oscillatory machining process, the static capacitance C0 of the transducer acts as a capacitive load and needs to be compensated by an additional matching inductor. The series matching inductor L0 needs to satisfy the following conditions:

[0052] jωL0 + jωX p = 0 (2)

[0053] where ω is the angular vibration frequency of the transducer, and X p is the total reactance of the transducer without the series inductor.

[0054] Then the total impedance of the resonant system at this time is:

[0055]

[0056] where Z t is the time-domain impedance of the transducer at time t, R t is the dynamic resistance of the transducer at time t, X t is the dynamic reactance of the transducer at time t, j is the imaginary part symbol in the complex plane, and C p is the total capacitance value of the transducer considering the static capacitance, and C p = C0C1 / (C0 + C1).

[0057] When , L1 and C p form a resonant circuit in the transducer. The angular frequency at this time is called the parallel resonance angular frequency and is denoted as ω p . Near ω p , the dynamic resistance R t of the transducer at time t and the dynamic reactance X t of the transducer at time t have the following relationship:

[0058]

[0059] At this time, the graphs of the resistance and reactance of the resonant system in the complex plane are circular, which is called the impedance circle. During the ultrasonic machining process, an increase in the cutting force will cause an increase in the dynamic resistance R1 of the transducer, and both R t and X t in the total impedance of the resonant system will change accordingly. During the ultrasonic machining process, the tool wears continuously, so the impedance relationship of the transducer changes in real time dynamically.

[0060] In the actual ultrasonic machining working conditions, the degree of tool wear continues to increase, resulting in a continuous increase in the cutting force. Therefore, the dynamic resistance R1 of the transducer continuously increases, and the radius of the impedance circle continuously shrinks. It can be found that during the ultrasonic machining process, the change of the real-time impedance relationship of the transducer is monotonic and continuous, and can be tracked in the ultrasonic power supply system.

[0061] Step 101: Perform Laplace transform on the time-domain impedance relationship to obtain the frequency-domain impedance curve of the transducer.

[0062] In actual work, the voltage applied across the ultrasonic piezoelectric transducer is a pulsed square wave, causing the transducer to operate in the sub-natural resonance region. Performing Laplace transform on the time-domain impedance of the transducer, that is, Equation (3), we can obtain:

[0063]

[0064] In the formula, s is the differential operator.

[0065] Step 102: Fit the frequency-domain impedance curve of the transducer to obtain a curve with a unique pair of conjugate characteristic roots. Specifically, the curve fitting process can be: obtaining a series of response curve data points in the s-plane close to the imaginary axis through interpolation calculation, and performing curve fitting based on these data points to obtain a curve with a unique pair of conjugate characteristic roots.

[0066] Among them, the frequency-domain impedance curve obtained after performing Laplace transform on the time-domain impedance of the transducer is a high-order curve, and the calculation of the characteristic roots is relatively slow. In actual application of this step, using the control algorithm of curve fitting data, using a curve with a unique pair of conjugate characteristic roots to fit the frequency-domain impedance curve of the transducer, and ensuring that the conjugate characteristic roots of the fitting curve are the same as the main characteristic roots of the transducer frequency-domain impedance, can effectively increase the resonance frequency tracking speed.

[0067] Step 103: Based on the curve with a unique pair of conjugate characteristic roots, obtain the resonance frequency of the transducer in real time to achieve frequency tracking, so that the ultrasonic system is in a stable resonance state.

[0068] Among them, calculate the characteristic roots of Equation (5). The set of conjugate characteristic roots closest to the poles is the main characteristic roots, and the rest are the secondary characteristic roots. The resonance frequency represented by the main characteristic roots is the resonance frequency of the transducer system. The ultrasonic system can quickly obtain the time-domain impedance of the transducer by tracking the real-time impedance relationship of the transducer in real time, that is, Equation (5). Solving Equation (5) can obtain the resonance frequency of the transducer system for frequency tracking.

[0069] Based on this, the process of frequency tracking can be as follows: The time-domain impedance of the transducer system can be obtained in real time by tracking the real-time impedance relationship of the transducer. The resonant frequency of the transducer system can be obtained by solving the characteristic roots. According to the obtained resonant frequency, the ultrasonic power supply system can change the output frequency in real time to match the resonant state of the transducer, thereby achieving frequency tracking.

[0070] Step 104: By tracking the feedback current in real time, the dynamic total resistance and dynamic total reactance of the ultrasonic system are obtained in real time. Based on the dynamic total resistance and dynamic total reactance of the ultrasonic system, the proportion of active power and reactive power in the output power is determined, and the output power is adjusted based on this proportion to achieve power tracking, and the constant-current and constant-amplitude voltage of the ultrasonic system is obtained in real time.

[0071] In the actual application process, the power feedback module adjusts the output power according to the feedback current, controls the reactive power to be constant, and obtains the dynamic total resistance R of the ultrasonic system by tracking the feedback current I in real time. t and the dynamic total reactance X t , and based on this, the proportion of active power and reactive power in the output power is calculated, thereby adjusting the output power to achieve power tracking, making the feedback current and the ultrasonic amplitude value stable, ensuring the stability of the ultrasonic processing effect, and obtaining the real-time constant-current and constant-amplitude voltage of the ultrasonic system.

[0072] Among them, the calculation formula of the active power P a is as follows:

[0073]

[0074] In the formula, P t is the total output power of the ultrasonic system.

[0075] The reactive power is P r = P t - P a . By adjusting the output power according to the feedback current and controlling the reactive power to be constant, power tracking can be achieved.

[0076] Furthermore, the adjustment process of power tracking is as follows: During the ultrasonic processing, as the tool wears, the cutting force increases. The increase in the cutting force will cause the dynamic resistance R1 of the transducer to increase. At this time, the voltage value at both ends of the transducer remains unchanged, and both the output current and the feedback current values decrease. The power feedback module adjusts the output power according to the feedback current, increases the duty cycle of the PWM wave of the output voltage, increases the feedback current value, and realizes the stability of the feedback current and the ultrasonic amplitude value. That is, on the premise of current stability, the output power is adjusted by changing the output voltage, and the adjusted output voltage value is the constant-current and constant-amplitude voltage. In actual processing, the feedback adjustment process is completed within the time of microseconds. Therefore, the feedback current value remains constant in the display interface, and the output voltage value changes in real time with the cutting process. This voltage is called the "constant-current and constant-amplitude voltage".

[0077] For example, Figure 4 This is a schematic diagram of the amplitude stabilization control principle of the ultrasonic machining quality control method for monitoring tool wear by a constant current and constant amplitude voltage in the embodiments of the present invention. Figure 4 In it, the upper right coordinate system is Figure 3 Part near the series resonance frequency of the impedance circle model of the transducer. The circle where point A1 is located is the impedance circle before loading, the circle where point A2 is located is the impedance circle after loading, and the resistance R t2 >R t1 . Point A1 and point A2 respectively correspond to point 1 and point 2 in the lower right coordinate system. The lower right coordinate system is the functional relationship between current and transducer resistance when the voltage is constant. Curve U'1 is the functional curve before current feedback regulation, and the voltage value at both ends of the transducer is U1. Curve U'2 is the functional curve before current feedback regulation, and the voltage value at both ends of the transducer is U2. Point 1 represents the state of the transducer before loading, denoted as the first state. Point 2 represents the state of the transducer after loading, denoted as the second state. Point 3 represents the state of the transducer after feedback regulation, denoted as the third state. After the transducer is loaded, the diameter of the impedance circle decreases and the resistance increases. At this time, the voltage value U1 at both ends of the transducer remains unchanged, and the current value drops from I1 to I2, that is, the working state switches from the first state to the second state. The lower left coordinate system is a triangular wave for controlling the current output, and the upper left coordinate system is a PWM square wave for controlling the voltage output. When the current value of the triangular wave is higher than the current value of the transducer, the PWM square wave outputs a high potential. In the PWM square wave, the larger the proportion of the high potential, that is, the larger the duty cycle, the higher the voltage value at both ends of the transducer. After the transducer is loaded, the current value of the transducer drops from I1 to I2, and the proportion of the current value in the triangular wave higher than the current value of the transducer increases, resulting in an increase in the duty cycle of the PWM square wave. After the feedback regulation is stable, the voltage value at both ends of the transducer increases from U1 to U2 (U1 / R t1 =U2 / R t2 ), at this time the working state of the transducer switches to the third state, and the current value stabilizes at I1, achieving stable current control and thus achieving amplitude stabilization control. R t1 is the transducer resistance in the first state, and R t2 is the transducer resistance in the second state. Among them, Figure 4 in it, f1 is the series resonance frequency of the transducer before loading, and f2 is the series resonance frequency of the transducer after loading. In addition, in this embodiment, left, right, up, and down are relative to the page display and are not specifically limited in the present invention.

[0078] Figure 5 This is an example diagram of the impedance circle of the ultrasonic machining quality control method for monitoring tool wear by a constant current and constant amplitude voltage in the embodiments of the present invention changing with the load. As Figure 5 shown, the tangent point of the transducer impedance circle and the reactance axis is below zero, which is in line with the theory. Figure 5The position marked by the circle is the working area of the transducer, that is, near the series resonance frequency. As the load increases, the diameter of the impedance circle continuously decreases, the impedance near the series resonance frequency gradually increases, and the feedback current decreases.

[0079] Step 105: During the ultrasonic machining process, in real time, detect the difference between the constant-current and constant-amplitude voltage of the ultrasonic system and the constant-current and constant-amplitude voltage in the state of tool dulling, determine the tool wear state based on the difference, and judge whether the current tool can complete the machining of the entire process based on the tool wear state.

[0080] Among them, the tool wear state refers to the change amount of the monitoring signal caused by the tool wear degree under a certain cutting parameter. During the ultrasonic machining process, as the tool wears, the cutting force increases, and under the power tracking of the ultrasonic system, the output voltage in the ultrasonic system also increases accordingly. The output voltage changes monotonically with the tool wear degree. Therefore, the output voltage, that is, the constant-current and constant-amplitude voltage monitoring method is used to monitor the tool wear state.

[0081] Furthermore, before ultrasonic machining, through pre-experiments, store the values of the constant-current and constant-amplitude voltage (output voltage) and the feedback current in three states of a certain part of the cutting workpiece or under a certain cutting parameter in the ultrasonic power supply. The three tool wear states are specifically:

[0082] (1) No-load state: The state where the cutting force is zero, used to calibrate the feedback current.

[0083] (2) New cutting tool state: The state where the tool just starts ultrasonic machining, used to calibrate the initial constant-current and constant-amplitude voltage.

[0084] (3) Tool dulling state: The state where the tool needs to be replaced, used to calibrate the final constant-current and constant-amplitude voltage.

[0085] In the actual application process, the judgment basis adopted by the present invention is: If the real-time constant-current and constant-amplitude voltage value is less than the final constant-current and constant-amplitude voltage value, the tool is in an un-dulled state. If the real-time constant-current and constant-amplitude voltage value is greater than or equal to the final constant-current and constant-amplitude voltage value, it is determined that the tool is dulled.

[0086] Figure 6 This is the amplitude stabilization control flow chart of the ultrasonic machining quality control method for monitoring tool wear by constant-current and constant-amplitude voltage in the present invention. As Figure 6 shown, after the tool state changes, the cutting force changes accordingly, resulting in an increase in the impedance when the transducer works near the series resonance frequency. At this time, the feedback current signal in the feedback circuit is input into the power tracking and frequency tracking modules. The power tracking module adjusts the output power in real time, and the frequency tracking module transmits the signal to the curve fitting module to track the resonance frequency. Finally, the processor adjusts the PWM wave frequency and duty cycle of the output voltage. During the fluctuating machining process, this feedback adjustment mode can make the output current of the transducer stable and achieve the amplitude stabilization control effect.

[0087] Further, the present invention also provides an ultrasonic machining quality control system for monitoring tool wear to apply the above ultrasonic machining quality control method for monitoring tool wear. The system includes:

[0088] A time-domain impedance relationship determination module, configured to obtain the dynamic resistance and dynamic reactance of the transducer during ultrasonic machining, and determine the time-domain impedance of the transducer in real time based on the dynamic resistance and dynamic reactance of the transducer, so as to obtain the time-domain impedance relationship.

[0089] A frequency-domain impedance curve determination module, configured to perform Laplace transform on the time-domain impedance relationship to obtain the frequency-domain impedance curve of the transducer.

[0090] A curve fitting module, configured to fit the frequency-domain impedance curve of the transducer to obtain a curve with a unique pair of conjugate characteristic roots.

[0091] A frequency tracking module, configured to obtain the resonance frequency of the transducer in real time based on the curve with a unique pair of conjugate characteristic roots to achieve frequency tracking.

[0092] A power tracking module, configured to obtain the dynamic total resistance and dynamic total reactance of the ultrasonic system in real time by tracking the feedback current in real time, determine the proportion of active power and reactive power in the output power based on the dynamic total resistance and dynamic total reactance of the ultrasonic system, adjust the output power based on the proportion to achieve power tracking, and obtain the constant-current and constant-amplitude voltage of the ultrasonic system in real time.

[0093] A tool wear state determination module, configured to detect in real time the difference between the constant-current and constant-amplitude voltage of the ultrasonic system and the constant-current and constant-amplitude voltage in the tool blunt state during ultrasonic machining, determine the tool wear state based on the difference, and determine whether the current tool can complete the machining of the entire process based on the tool wear state. The tool wear state includes: no-load state, cutting new tool state, and tool blunt state.

[0094] An electronic device, including:

[0095] A memory, configured to store a computer program.

[0096] A processor, connected to the memory, configured to retrieve and execute the computer program to implement the above ultrasonic machining quality control method for monitoring tool wear.

[0097] In addition, when the computer program in the above-mentioned memory is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories, random access memories, magnetic disks, or optical discs.

[0098] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method part.

[0099] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A method for ultrasonic machining quality control for monitoring tool wear, characterized in that: include: Acquiring a dynamic resistance and a dynamic reactance of the transducer during ultrasonic machining, and determining a time domain impedance of the transducer in real time based on the dynamic resistance and the dynamic reactance of the transducer to obtain a time domain impedance relationship; Performing Laplace transform on the time-domain impedance relationship to obtain a frequency-domain impedance curve of the transducer; Fitting the frequency domain impedance curve of the transducer to obtain a curve having a unique pair of conjugate characteristic roots; The resonant frequency of the transducer is obtained in real time based on a curve with a unique pair of conjugate characteristic roots to achieve frequency tracking; By real-time tracking of the feedback current, the dynamic total resistance and dynamic total reactance of the ultrasonic system are obtained in real time, and the proportion of active power and reactive power in the output power is determined based on the dynamic total resistance and dynamic total reactance of the ultrasonic system. The output power is adjusted based on the proportion to achieve power tracking, and the steady current and amplitude voltage of the ultrasonic system are obtained in real time; During ultrasonic machining, the difference between the steady-current and steady-amplitude voltage of the ultrasonic system and the steady-current and steady-amplitude voltage when the tool is blunt is detected in real time. The tool wear state is determined based on the difference, and based on the tool wear state, it is judged whether the current tool can complete the machining of the entire process; the tool wear state includes: no-load state, new tool cutting state and tool blunt state.

2. The ultrasonic machining quality control method for monitoring tool wear according to claim 1, characterized in that: Before obtaining the dynamic resistance and the dynamic reactance of the transducer during ultrasonic machining and determining the time domain impedance of the transducer in real time based on the dynamic resistance and the dynamic reactance of the transducer, the method further includes: Through experiments, the steady-current and steady-amplitude voltage and feedback current values of different tool wear states under different cutting workpiece positions or cutting amounts are obtained.

3. The ultrasonic machining quality control method for monitoring tool wear according to claim 1, characterized in that: The time domain impedance of the transducer is: Where Z t is the time domain impedance of the transducer at time t, R t is the dynamic resistance of the transducer at time t, X t is the dynamic reactance of the transducer at time t, ω is the vibration angular frequency of the transducer, C0 is the static capacitance of the transducer, R1 is the dynamic resistance, L1 is the inductance of the dynamic inductor, C p is the total capacitance of the transducer when considering the static capacitance, and j is the sign of the imaginary part in the complex plane.

4. The ultrasonic machining quality control method for monitoring tool wear according to claim 1, characterized in that: A series of response curve data points are obtained in an S plane at a set distance from the imaginary axis by an interpolation calculation method, and the frequency domain impedance curve of the transducer is fitted according to the obtained response curve data points to obtain a curve with a unique pair of conjugate characteristic roots.

5. The ultrasonic machining quality control method for monitoring tool wear according to claim 1, characterized in that: The relationship between the dynamic resistance of the transducer and the dynamic reactance of the transducer is: Where R t is the dynamic resistance of the transducer at time t, X t is the dynamic reactance of the transducer at time t, ω p is the parallel resonant angular frequency, C0 is the static capacitance of the transducer, and R1 is the dynamic resistance.

6. An ultrasonic machining quality control system for monitoring tool wear, characterized in that: The ultrasonic machining quality control method for monitoring tool wear according to any one of claims 1 to 5 is applied; the system comprises: a time-domain impedance relationship determination module, configured to obtain the dynamic resistance and the dynamic reactance of the transducer during ultrasonic machining, and determine the time-domain impedance of the transducer in real time based on the dynamic resistance and the dynamic reactance of the transducer to obtain the time-domain impedance relationship; A frequency domain impedance curve determination module, configured to perform Laplace transform on the time domain impedance relationship to obtain a frequency domain impedance curve of the transducer; A curve fitting module, configured to fit the frequency domain impedance curve of the transducer to obtain a curve having a unique pair of conjugate characteristic roots; A frequency tracking module is used to obtain the resonant frequency of the transducer in real time based on a curve having a unique pair of conjugate characteristic roots to achieve frequency tracking; A power tracking module is used to obtain the dynamic total resistance and dynamic total reactance of the ultrasonic system in real time by real-time tracking of the feedback current, and to determine the proportion of active power and reactive power in the output power based on the dynamic total resistance and dynamic total reactance of the ultrasonic system, to adjust the output power based on the proportion, to achieve power tracking, and to obtain the steady current and steady amplitude voltage of the ultrasonic system in real time; The tool wear state determination module is used to detect in real time the difference between the steady-current and steady-amplitude voltage of the ultrasonic system during ultrasonic machining and the steady-current and steady-amplitude voltage when the tool is blunt, determine the tool wear state based on the difference, and judge whether the current tool can complete the machining of the entire process based on the tool wear state; the tool wear state includes: no-load state, new tool cutting state and tool blunt state.

7. An electronic device, characterized in that: include: memory for storing computer programs; A processor is connected to the memory and is used to retrieve and execute the computer program to implement the ultrasonic machining quality control method for monitoring tool wear according to any one of claims 1 to 5.

8. The electronic device according to claim 7, wherein: The memory is a computer-readable storage medium.

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