Research On Principle And Experimental Study Of Ultrasonic Vibration Composite Polishing

With the rapidly developing of science and technology,smooth surfaces and precision components are increasingly used in many high-tech industries such as optical system,aerospace,microelectronic,biomedicine and new energy.Moreover,the requirements for their surface quality and accuracy have been raised.However,due to its widespread use of difficult-to-machine materials for manufacturing and production,higher requirements have been proposed on the corresponding surface finishing technology as well.Therefore,an ultrasonic vibration composite polishing technology emerged as the times require in order to solving the finishing problem of smooth surfaces and difficult-to-machine materials.Ultrasonic vibration composite polishing technology has many advantages that traditional surface finishing technology does not have.For example,it has less thermal influence on the specimen and a wide processing range.The polished surface is not easy to be deformed and the processing precision and efficiency are quite high.In this context,this paper has conducted some intensive researches on the principle and process of ultrasonic vibration composite polishing technology.The contrast polishing experiments,single factor experiments and orthogonal experiments were carried out by using the self-built ultrasonic polishing platform firstly.Then the ultrasonic field effect and material removal mechanism were studied by trajectory simulation and theoretical modeling.At last,the process parameters were optimized by Taguchi method and comprehensive scoring method.The specific research contents are as follows:(1)An ultrasonic vibration composite polishing experimental platform was built and the contrast polishing experiment was conducted on this equipment.The gain effects of ultrasonic vibration field on polishing quality and efficiency were analyzed based on the experimental results.The existence form of the abrasive particles was confirmed as embedded abrasive particles and free abrasive particles according to the microscopic morphology of the lower polishing pad,furthermore,kinematic analysis and modeling of the two kinds of abrasive particles were carried out.Finally,the kinematics calculation and trajectory simulation of abrasive particles were accomplished by MATLAB and the effects of ultrasonic vibration on the polishing process were elaborated based on the calculation and simulation results.(2)According to the action form of the polishing particles,two kinds of material removal theories were proposed,one is the intermittent scratch removal of the embedded abrasive particles,and the other is the high frequency impact removal of all the abrasive particles.Based on the nickel-based alloy 718,the material removal function of ultrasonic vibration composite polishing hard and tough materials was established by theoretical analysis and derivation calculation.Moreover,the main influence parameters were obtained as speed,amplitude,particle size and pressure.Four groups of single factor experiments were designed and conducted according to the main influence parameters to study their effect laws on polishing efficiency and surface quality.(3)A four-factor three-level orthogonal experiments were designed according to the main influence parameters obtained by the ultrasonic composite polishing model and parameter range determined by the single factor experiments.The Taguchi method was used to optimize the process parameters based on the two single indexes of surface roughness and material removal rate respectively.Then,the comprehensive scoring method was used to conduct the multi objective optimization and the selection of parameter levels was accomplished based on the optimization results.Finally,the validation experiments were carried out by applying the optical parameter combination obtained after comprehensive optimization.