Piezoelectric ceramic amplitude feedback control device and method

Abstract

The application discloses a piezoelectric ceramic amplitude feedback control device and method, and relates to the technical field of ultrasonic transducers.The device comprises a driving circuit, a decoupling circuit and a control circuit.The driving circuit is used for supplying power to the piezoelectric ceramic and driving the ultrasonic auxiliary machining equipment to run.The decoupling circuit is used for extracting an electric signal at both ends of the piezoelectric ceramic.The electric signal comprises a driving signal generated by the driving circuit and a positive piezoelectric effect of the piezoelectric ceramic.The positive piezoelectric effect comprises amplitude information.The control circuit is connected with the driving circuit and the decoupling circuit, and is used for issuing a control instruction to control the driving circuit according to the amplitude information and an expected amplitude.The decoupling circuit can extract an electric signal representing the amplitude of the piezoelectric ceramic, the amplitude of the piezoelectric ceramic can be detected in real time, and the influence of environmental factors on the running of the equipment is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultrasonic transducer, in particular to a piezoelectric ceramic amplitude feedback control device and method. BACKGROUND

[0002] The existing technology for detecting the amplitude of ultrasonic machining equipment includes offline detection and real-time detection.

[0003] (1) Offline detection: the ultrasonic transducer is placed in a dedicated amplitude detection device, a control instruction is given, the amplitude is displayed by the detection device, and a corresponding curve of the driving instruction-amplitude is obtained through a series of observations and calibrations. When the ultrasonic equipment is working, the tool end face and the machined material are often closely attached together, so that external sensors such as laser displacement sensors cannot measure, and there is not enough space on the machine tool to add sensors. Therefore, according to a patent, before the ultrasonic equipment is installed, the amplitude is tested on the detection equipment, and the performance parameters are obtained before the ultrasonic equipment is installed on the machine tool. The corresponding relationship between the control instruction and the amplitude obtained by the offline detection method is only discrete points, and the number is limited. Under the premise that the machining conditions do not change greatly, this method is effective, but in the actual machining process, once the machining conditions, the machined material and other external factors change, it is difficult to control according to the preset corresponding relationship, and the machining quality is difficult to guarantee. Therefore, the application of this method has limitations, and it is difficult to guarantee the machining quality.

[0004] (2) Real-time detection: the real-time detection here is not the real-time detection of the amplitude of the piezoelectric ceramic, but the electric signal between the two ends of the piezoelectric ceramic. According to the inverse piezoelectric effect, a voltage is applied to the piezoelectric ceramic, and the piezoelectric ceramic will deform, that is, the deformation of the piezoelectric ceramic has an approximately linear corresponding relationship with the driving voltage. In occasions where the control accuracy is not high, the electric signal output by the power supply can be directly detected in real time to indirectly represent the amplitude signal. The electric signal between the two ends of the piezoelectric ceramic can represent the amplitude, but considering the hysteresis characteristics of the piezoelectric ceramic, directly representing the amplitude based on the voltage has a large error. The hysteresis model can compensate for the hysteresis characteristics, but this method has great limitations. When the working conditions change, the model parameters are difficult to accurately control. SUMMARY

[0005] The purpose of the present application is to provide a piezoelectric ceramic amplitude feedback control device and method, which effectively extracts the amplitude information of the piezoelectric ceramic by detecting the electric signal between the two ends of the piezoelectric ceramic, without adding external sensors, and is suitable for application occasions with limited working space and high amplitude accuracy requirements.

[0006] To achieve the above purpose, the present application provides the following scheme:

[0007] The application discloses a piezoelectric ceramic amplitude feedback control device, which is applied to an ultrasonic auxiliary machining device, and the ultrasonic auxiliary machining device comprises a tool holder and a piezoelectric ceramic.

[0008] A driving circuit is arranged to supply power to the piezoelectric ceramic and drive the ultrasonic auxiliary machining device to operate.

[0009] A decoupling circuit is arranged to extract an electric signal between the two ends of the piezoelectric ceramic, wherein the electric signal comprises a driving signal generated by the driving circuit and a positive piezoelectric effect of the piezoelectric ceramic, and the positive piezoelectric effect comprises amplitude information.

[0010] A control circuit is connected with the driving circuit and the decoupling circuit, and is arranged to send a control instruction to control the driving circuit according to the amplitude information and an expected amplitude.

[0011] To achieve the above object, the application further provides the following scheme.

[0012] A piezoelectric ceramic amplitude feedback control method, which is applied to the piezoelectric ceramic amplitude feedback control device, and the method comprises the following steps.

[0013] Extracting amplitude information of the piezoelectric ceramic in the ultrasonic auxiliary machining device.

[0014] Determining a control instruction according to the amplitude information and an expected amplitude.

[0015] Controlling the driving circuit to drive the ultrasonic auxiliary machining device to operate according to the control instruction.

[0016] According to the specific embodiments of the application, the following technical effects are achieved.

[0017] The decoupling circuit can extract the electric signal representing the amplitude of the piezoelectric ceramic, and the amplitude of the piezoelectric ceramic can be detected in real time, so that the influence of environmental factors on the operation of the device is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from these drawings without creative labor.

[0019] Figure 1This is a structural block diagram of the piezoelectric ceramic amplitude feedback control device provided by the present invention;

[0020] Figure 2 A schematic diagram illustrating the application of the piezoelectric ceramic amplitude feedback control device provided by the present invention in an ultrasonic-assisted processing equipment;

[0021] Figure 3 Schematic diagrams of the direct and inverse piezoelectric effects;

[0022] Figure 4 This is a schematic diagram of the decoupling circuit.

[0023] Figure 5 The flowchart shows the piezoelectric ceramic amplitude feedback control method provided by the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The purpose of this invention is to provide a piezoelectric ceramic amplitude feedback control device and method, which effectively extracts the amplitude information of the piezoelectric ceramic by detecting the electrical signals at both ends of the piezoelectric ceramic.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1

[0028] like Figures 1-2 As shown, the piezoelectric ceramic amplitude feedback control device provided by the present invention is applied to an ultrasonic-assisted machining equipment 101, which includes a tool holder 1011 and a piezoelectric ceramic 1012. The piezoelectric ceramic amplitude feedback control device includes a drive circuit 102, a decoupling circuit 103, and a control circuit 107.

[0029] The drive circuit 102 supplies power to the piezoelectric ceramic 1012, driving the ultrasonic-assisted processing equipment 101 to operate. For example... Figure 3As shown, the driving circuit 102 supplies power to the piezoelectric ceramic 1012, and the power is applied to the two ends of AB, and the piezoelectric ceramic 1012 will be mechanically deformed; when the piezoelectric ceramic 1012 works, the end face and the processed material are extruded, and by the positive piezoelectric effect, an electric charge will be accumulated at the AB end. Therefore, the electric signal at the AB end is coupled from two parts, one part is the driving signal from the driving circuit 102, and the other part is from the positive piezoelectric effect of the piezoelectric ceramic 1012, which contains the amplitude information of the piezoelectric ceramic 1012.

[0030] The decoupling circuit 103 is used to extract the electric signal at the two ends of the piezoelectric ceramic 1012. As shown, Figure 4 The decoupling circuit 103 includes a voltage follower 1031, a detection ceramic 1032, a transformer 1033, and a differential circuit 1034.

[0031] The piezoelectric ceramic 1012 is placed inside the ultrasonic auxiliary machining device 101, and a detection ceramic 1032 with the same parameters is placed outside the ultrasonic auxiliary machining device 101. The voltage following circuit 1031 ensures that the input voltage of the driving circuit 1102 is not affected by the load change, and the input voltage is followed by the voltage following circuit 1041 and is supplied to the piezoelectric ceramic 1012 and the detection ceramic 1032 through the transformer 1033.

[0032] The piezoelectric ceramic 1012 and the detection ceramic 1032 apply the same pre-tightening force, but the detection ceramic 1032 does not process. The piezoelectric ceramic 1012 simultaneously exists positive piezoelectric effect and inverse piezoelectric effect, and there is a two-way flow of electric energy and mechanical energy, when the piezoelectric ceramic 1012 processes, it receives the extrusion of hard material, and is affected by the positive piezoelectric effect, at this time, there is a voltage difference between the voltage on the piezoelectric ceramic 1012 and the voltage on the detection ceramic 1032, and the differential circuit 1034 obtains the signal for representing the amplitude.

[0033] The control circuit 107 receives the expected amplitude issued from the host computer 109 and receives the amplitude information fed back from the decoupling circuit 103, and generates a control instruction to control the driving circuit 102.

[0034] Further, the host computer 109 is connected to the control circuit 107 through the communication circuit 108 to realize human-computer interaction.

[0035] Further, the high-precision DA conversion circuit 104 is connected to the driving circuit 102; the decoupling circuit 103 is connected to the high-precision AD conversion circuit 105; the control circuit 107 is connected to the DA conversion circuit 104 and the AD conversion circuit 105 through the isolation circuit 106.

[0036] The DA conversion circuit 104 converts the digital instruction from the control circuit 107 into an analog quantity, and the driving circuit 102 amplifies the analog quantity to control the ultrasonic auxiliary machining device 101 to work. The AD conversion circuit 105 converts the analog quantity from the decoupling circuit 103 into a digital quantity. The isolation circuit 106 realizes the electrical isolation of the low-voltage circuit and the high-voltage circuit, and plays a protection role.

[0037] The present application considers that the piezoelectric ceramic simultaneously has a positive piezoelectric effect and a reverse piezoelectric effect, and the electric signal at both ends of the ceramic in the machining process is the result of the joint action of the positive and reverse piezoelectric effects. By detecting the electric signal at both ends of the ceramic, the amplitude information of the piezoelectric ceramic can be extracted through the decoupling circuit, a control algorithm is set, and then the amplitude control of the ultrasonic auxiliary machining device is realized. Moreover, in the device, the piezoelectric ceramic simultaneously has the functions of an actuator and a sensor, and does not need to additionally increase a displacement sensor, thereby saving the space of the machining device and reducing the cost.

[0038] Embodiment two

[0039] In order to apply the device corresponding to the above-mentioned embodiment one to realize the corresponding functions and technical effects, a piezoelectric ceramic amplitude feedback control method is provided below.

[0040] The method comprises:

[0041] S1: Extracting the amplitude information of the piezoelectric ceramic in the ultrasonic auxiliary machining device.

[0042] S2: Determining the control instruction according to the amplitude information and the expected amplitude.

[0043] S3: Controlling the driving circuit to drive the ultrasonic auxiliary machining device to run according to the control instruction.

[0044] The detailed process is as shown in Figure 5

[0045] Step 1: The user inputs the expected amplitude on the host computer.

[0046] Step 2: The control circuit receives the instruction from the host computer and receives the ceramic amplitude information fed back from the decoupling circuit to generate a control instruction.

[0047] Step 3: The DA conversion circuit converts the control instruction into an analog quantity.

[0048] Step 4: The driving circuit performs power amplification on the analog quantity to drive the ultrasonic auxiliary machining device to run.

[0049] Step 5: The decoupling circuit extracts the electric signal amplitude information containing the ceramic amplitude information under the premise of not affecting the normal work of the ultrasonic auxiliary machining device, converts the electric signal amplitude information into a digital quantity through the AD conversion circuit, and inputs the digital quantity into the control circuit.

[0050] ​The various embodiments described in this specification are presented for the purpose of illustrating the principles of the present application and its best mode of operation. Each of the embodiments described in this specification has been provided for the purpose of illustration and is not intended to limit the application.

[0051] The principles and implementations of the present application have been described in the specification with specific examples. The above description of the embodiments is only for the purpose of helping to understand the method of the present application and its core idea. Meanwhile, for those skilled in the art, the specific implementation and application range of the present application can be changed according to the idea of the present application. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A piezoelectric ceramic amplitude feedback control device, characterized by comprising: The piezoelectric ceramic amplitude feedback control device is applied to an ultrasonic auxiliary machining equipment, and the ultrasonic auxiliary machining equipment comprises a tool holder and a piezoelectric ceramic. A driving circuit is configured to supply power to the piezoelectric ceramic and drive the ultrasonic auxiliary machining equipment to operate. A decoupling circuit is configured to extract an electric signal between the piezoelectric ceramic, wherein the electric signal comprises a driving signal generated by the driving circuit and a positive piezoelectric effect of the piezoelectric ceramic, and the positive piezoelectric effect comprises amplitude information; the decoupling circuit comprises a voltage follower, a detection ceramic, a transformer and a differential circuit; the input voltage of the driving circuit is supplied to the detection ceramic and the piezoelectric ceramic through the transformer after passing through the voltage follower; the differential circuit is configured to obtain a voltage difference between the piezoelectric ceramic and the detection ceramic, and the voltage difference is used to represent the amplitude information. A control circuit is connected with the driving circuit and the decoupling circuit, and configured to send a control instruction to control the driving circuit according to the amplitude information and an expected amplitude.

2. The piezoelectric ceramic amplitude feedback control device according to claim 1, characterized by A DA conversion circuit is arranged between the driving circuit and the control circuit, and configured to convert the control instruction into an analog quantity.

3. The piezoelectric ceramic amplitude feedback control device according to claim 2, characterized by An AD conversion circuit is arranged between the decoupling circuit and the control circuit, and configured to convert the amplitude information into a digital quantity.

4. The piezoelectric ceramic amplitude feedback control device according to claim 3, characterized by An isolation circuit is arranged between the DA conversion circuit and the control circuit and between the AD conversion circuit and the control circuit.

5. The piezoelectric ceramic amplitude feedback control device according to claim 1, characterized by The piezoelectric ceramic and the detection ceramic have the same pre-tightening force.

6. The piezoelectric ceramic amplitude feedback control device according to claim 1, characterized by The expected amplitude is sent by a host computer to the control circuit.

7. The piezoelectric ceramic amplitude feedback control device according to claim 6, characterized by The host computer and the control circuit are connected through a communication circuit.

8. A piezoelectric ceramic amplitude feedback control method, characterized by, The method applies the piezoelectric ceramic amplitude feedback control device according to any one of claims 1-7, and the method comprises: extracting the amplitude information of the piezoelectric ceramic in the ultrasonic auxiliary machining equipment; determining the control instruction according to the amplitude information and an expected amplitude; controlling the driving circuit to drive the ultrasonic auxiliary machining equipment to operate according to the control instruction.

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