NUMERICAL MODELING AND CONTROL OF TRANSDUCER IN ULTRASONICALLY ASSISTED MACHINING

【摘要】：Background, Motivation and Objective Ultrasonic assisted machining has been applied in the brittle and hard material. The key problem in the promotion of ultrasonically assisted machining is the development of the proper adaptive control of the ultrasonic vibration. Many experts and scholars have paid great attention and interest of the ultrasonic vibration cutting processing technology. While the actual process in combined with load together, the study is so sacred in academic and industry nowadays. It was shown that frequency control is inefficient in achieving peak performance of ultrasonic vibrating systems. To solve this problem, a numerical vibration model is established by a mass-damper-elastic component, which helps to understand the dynamics of the ultrasonic transducer. In order to improve the control performance of the vibration, the PID and H∞ algorithm for vibration control is established and simulated in the Matlab Simulink. Statement of Contribution/Methods(1) The mechanical structure of ultrasonic transducer is introduced in detail.(2) The vibration model of mass-damper-elastic with/without load is established.(3) Effect of the load to the vibration charactrerics of ultrasonic transducer, simulation calculation is carried out in the Matlab-Simulink.(4) Simulation of the load switch by without any controller, PID controller, H∞ controller is analyzed.(5) Verified experiment includes: different load effect on the transducer; vibration Control at different load. Results The calculation of the coefficients of the numerical model based on the parameters of an ultrasonic transducer and the process of calculation is explained in detail. The validity of the created model of the ultrasonic vibrating system has been confirmed experimentally. A model of the robust controller for this system has been developed. The simulation results for the model of the ultrasonic transducer with the load applied is showed. The validity of the model of the ultrasonic vibrating system has been confirmed experimentally. In the condition of constant voltage, constant current and constant power, the design of the controller satisfies the requirement of the amplitude of the control system under the load. Discussion and Conclusions(1) Effect of the load to the vibration charactrerics of the ultrasonic transducer is discussed in the Matlab-Simulink.(2) The control performance of the transducer without any controller, PID controller, H∞ controller is discussed.(3) The agreement between theory and experiment result is discussed in detail. The effect of different damper and elastic component on the frequency characteristic of the ultrasonic transducer is found from the simulation. The PID and H∞ algorithm for vibration control is found that the PID and H∞ algorithm can achieve the accurate and fast control result. Some experiments to verify the theory and simulation calculation is carried out.