Development Of Ultrasonic Power Supply With Constant Amplitude Control Based On Load Change

With the high-precision new materials,with brittle and hard properties,were applied in modern manufacturing industries such as aircraft manufacturing.Rotary ultrasonic machining technology has developed rapidly,because it adapted to brittle and hard materials processing.Non-contact rotary machining technology has become a research focus of ultrasonic machining technology with its safe energy transmission and high speed spindle rotation.However,the rapid change of cutting force and the low efficiency of power transmission of non-contact rotary ultrasonic machining is more prone to the phenomenon of amplitude attenuation and amplitude instability,which seriously affects the cutting quality.To solve the problem of amplitude attenuation,ultrasonic power supply should quickly adjust the output frequency and power according to the change of cutting force during the processing,and has appropriate compensation circuit in the non-contact power supply part.Based on the existing ultrasonic vibrator and non-basic power supply coupler,conducted the following research:1.The experimental platform for loading the axial and radial forces of the ultrasonic vibrator is built.Replace the cutting force of the ultrasonic vibrator during machining with axial load force and radial load force.Measuring the electrical performance parameters of the ultrasonic vibrator by an impedance analyzer.The variation trend of the ultrasonic vibrator's electrical performance parameters under different axial and tangential forces is obtained.According to the equivalent model under the ultrasonic vibrator load force,the influence of the change of electrical performance parameters on the amplitude attenuation of the ultrasonic vibrator is analyzed.Measures to improve amplitude attenuation by ultrasonic power supply were proposed.2.Comparing the mutual inductance model and the leakage inductance model of the contactless power supply coupler.Based on the mutual inductance model,to derive the calculation formula of the primary and secondary compensation capacitors of the three compensation methods.Calculate the values of the parameters under the coupler mutual inductance model using the LCR bridge measurement.The unilateral compensation simulation is performed in the software Multisim,and verify the conclusions of the primaryside compensation tuning and the secondary side compensation adjustment efficiency.3.Design the hardware circuit of the ultrasonic power supply according to the function to be realized.Determine the structure of each module and select each module device.Frequency and power control are performed by the phase difference and current signal fed back by the feedback circuit.Automatic tracking and constant amplitude control program based on completed hardware circuit design frequency.The frequency tracking uses a variable step size control strategy,and the power control uses a control strategy combining stepping and PID algorithms.4.According to the design that has been completed,the ultrasonic power supply hardware is fabricated through the steps of drawing schematic diagram,drawing PCB diagram,plate making and welding,etc.Writing software programs through the MDK5 development environment.Perform long-term experimental debugging on the completed board,and theoretically analyze and test the existing problems.Experiments show that,the ultrasonic power supply can realize the functions of resonant frequency tracking and constant amplitude control.