Design And Experimental Study Of Vibration System For Ultrasonic Chemical Polishing Of Sapphir

Sapphire’s high hardness,high abrasion resistance,high erosion resistance and other feature make it can be used in military,medical,electronic and so on,and the market needs is growing.However,sapphire is a hard and brittle material with extremely high hardness,so it is difficult to process it.Traditional polishing methods can not meet the requirements of precision polishing of sapphire,a hard and brittle material.With the emergence of ultrasonic processing,which has proven to have unique advantages for processing hard and brittle materials.The design of ultrasonic vibration system mainly has full resonance design and local resonance design,when the full resonance design,the design requirements and processing requirements are high,there is a deviation of the resonant frequency drift phenomenon,resulting in unstable amplitude,Thus,the workpiece surface quality and processing efficiency are affected.In view of this phenomenon,this paper proposes an ultrasonic vibration system designed according to local resonance and carries out ultrasonic chemical polishing experiments.The main research is as follows:(1)Firstly,based on the design of the piezoelectric ultrasonic vibration system and chemical polishing technology,the background and application of the piezoelectric ultrasonic vibration system and chemical polishing as well as the conditions of local resonance generation in the piezoelectric vibration system are introduced,and the material removal mechanism of the ultrasonic chemical polishing is analyzed.(2)Through the design and calculation of the ultrasonic chemical polishing vibration system,the size and material parameters of the transducer,amplitude converter and polishing head are determined.Therefore,the basic model of ultrasonic chemical polishing vibration system was determined,the three-dimensional model of ultrasonic chemical polishing vibration system was established and imported into the simulation software COMSOL,and the characteristic frequency and frequency domain finite element analysis of ultrasonic chemical polishing system was carried out.The characteristic frequency of the ultrasonic chemical polishing system,the amplitude of the system under 250 V voltage and the position of the node are obtained by analysis.The ultrasonic chemical polishing vibration system is verified by simulation.The performance of the ultrasonic chemical polishing vibration system was tested.Impedance analysis of the system to determine the resonant frequency,test the pitch and the amplitude of the end of the horn,the amplitude of the output end is much larger than the amplitude of the end of the horn,explore the relationship between the voltage and the amplitude,and the experimental results and simulation results are compared to verify the rationality of the design.(3)The experimental platform of ultrasonic chemical polishing was built,the experimental methods and procedures were proposed,and the influences of four experimental factors,including machining distance,abrasive concentration,rotation speed of polishing disc and p H value,on the experimental results of ultrasonic chemical polishing were explored,and the optimal processing parameters were obtained.Ultrasonic chemical polishing experiments were carried out according to the optimal processing parameters to study the surface roughness,material removal rate and surface quality of experimental material sapphire by ultrasonic chemical polishing.Comparison experiments were conducted between local resonance polishing head and resonant polishing head.The experimental results showed that,ultrasonic chemical polishing with local resonance design is more effective in reducing the surface roughness and increasing the material removal rate of sapphire.