| Vibration cutting is a kind of advanced machining technology that utilizes much knowledge such as materials science, metal cutting theory, vibration engineering, engineering mechanics control engineering etc. Vibration drilling is a branch of vibration cutting Because of its unique process effect, vibration drilling, especially axial vibration drilling, has been noticing widely by many specialists and scholars.Based on vibration drilling of small hole, This paper studied deeply kinematics characteristics, dynamic characteristics, chip-breaking, chip-removing and process effect of axial vibration drilling. The author applied theory analysis, numerical simulation and experimentation with real situation to study the vibration drilling. And the creative work and research content of this paper is mainly as follows:(1) Forming mechanism of drilling in Axial Vibration Process.The four kinematics characteristics of axial vibration drilling are analyzed. The influence of vibration parameters on kinematics characteristics is disclosed. According to the dynamic theory of mechanical system, the paper built the bend and torsion vibration model of the twist drill and analyzed the bend and torsion vibration rules of drill in vibration drilling. So, the essential of decreasing vibration of vibration drilling is primarily opened out. At the same time, the mechanism of absolute chip-breaking and the predictive method of chip dimension of totally separate vibration drilling were also analyzed. The predicted rules were in good agreement with the measured data under vibration condition. The vibration drilling has more advantage over the normal drilling in machining small hole.(2) Finite element modeling of drilling in Axial Vibration Process.Based on the recent research and development in twist drill modeling, the paper analyzed some key aspects and features of the three FEM that’s used to simulation of the vibration drilling process. At the same time, a 3D finite element model was developed for the simulation of drilling temperature and burr formation processes of stainless steel. The nonlinear thermo-elastic-plastic model simultaneously accounts for dynamic effects of strain hardening, strain rate, automatic mesh contact with friction capability, material ductile failure and temperature mechanical coupling. Material ductile failure criteria were proposed to simulate drilling burr formation.(3) Feed-direction burr forming and it’s control technology.With theoretical analysis, numerical simulation and experimental research of high speed axial vibration drilling, some key aspects of Feed-direction burrs forming and it’s control technology had been studied. The feed-direction burr formation had been experimented and pointed out that there are three types of the feed-direction burrs: burr type I , II and III and studied the influence factors of the feed-direction burrs. Furthermore, a numerical analysis method provided by finite element model here to model the burr formation and analyzed the physical characteristic of burrs region. At last, the author had proposed some new control technologies for feed-direction burr formation in drilling process.This research is an important part of national natural sciences fund project (No.50275066, 50675088), and also gets the support of Sci-tech Innovation Found of Jiangsu University. The working achievement of this paper will riches and develops the theory of vibration drilling. It has high theoretical and applied value in prompting the application and development of this technique... |
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