Research On Precision Machining Based On Elastic Waves In Solids

In this paper, the development, defect and hot topic of ultra-precision machining technologywas decribed. The research process of the frictional interface of ultrasonic motors wassummarized. Based on the defect that it is difficult to improve the precision of kinematic pairs oftraditional grinding methods, a grinding tool without kinematic pairs was presented, which canrealize ultra-precision machining by fixed grain, piezoelectric ceramics which can realizeauto-deformation of the grinding tool, and piezoelectric ceramic array which can realize theaccurate control of applied force, feed direction and feed rate by producing the controllablevibration(elastic waves) on the structure parts, of which can be adopted. In the premise ofassuring shape and dimension precision, the surface quality can be improved.Take a grinding tool without compensention parts as an object of study, the law of operatingmodal frequency was studied and the structural dimensions of the tool were designed throughAnsys, according to the principle of the design of USM and grinding tools. Modal analysis andharmonic analysis were conducted and the components of the prototype were manufactured,assembled and tested for vibration and grinding performace to validate the possibility of theprecision machining under low circumstances and confirm the simulation results of modal andharmonic analysis. In the premise that the modal frequencies coherence relies on the accuracy ofthe grinding tool, the method to realize modal frequencies coherence was preposed based on thesensitivity analysis. The optimization program complied by APDL language was searched for theoptimum solution of the structural dimensions, the conclusion of which shows that the generalobjective function finally and steadily converged to a extreme value and all the sub-objectivefunctions had been optimized in different levels. Still, based the optimized structural dimensions,the modal analysis and harmonic analysis were conducted to validate that the efficiency of ellipticmotion has beed improved.Based on the defects that grinding tools have no ultimate accuracy, multi-points and matrixcompensation grinding tools were preoposed, the operating principle and structural design ofwhich were presented. The grinding tool was simulated and the structural dimensions weredesigned. Modal experiments show that the actual operating frequencies were similar to thesimulation results. Based on the defects of technics, the prototype can only operate theoretically. Take an grinding tool with high vibration amptitude as an object of study, which can be used forquantitative study of relations between wear amount and pre-stress, as well as that wear amount andapplied voltage, a series of analysis and experiment were conducted. It can be concluded that thegrinding method can realize removal of nanometer-size-material under low-stress-circumstances andaccurate control, which gives a new solution to the problem of ultra-precision surface machining.