The Multifunctional Miniaturized Machine Tool And Machining Technology

By utilizing traditional machining technologies, miniaturized machine tools have many advantages, such as strong material adaptability, less space and energy consumption, being easier to realize high precision machining and great probability of mass production in the aspect of fabricating complicated three-dimensional micro structures, especially for the multifunctional miniaturized machine tool in comparison with the single function miniaturized machine tool.For the purpose of studying the multifunctional miniaturized machine tool and its machining technologies, it is the first time to finish the development of multifunctional miniaturized machine tool with the function of micro milling and micro EDM(electrical discharging machining). It is characterized by strong material adaptability as well as diversity of processing technologies and is developed for the micro milling and micro EDM machining on the workpiece with a dimension ranging from microns to millimeters.Based on the study of burr formation mechanism in micro milling, it is proposed that to minimize the burr in micro milling by an optimization of milling parameters and tool path. It is capable of decreasing the influence of burrs on the quality of workpiece.For avoiding the acceleration of the milling tool wear even break due to the excessive cutting force in micro milling, it is the first time to propose that to control the cutting force in micro milling by adjusting the federate parameter during machining in order to realize the overload protection for milling tool.A micro EDM processing model is established with BP(back propagation) neural network. This model is used for studying the influence of pulse voltage, peak current and pulse width on tool wear and material removal rate. And then GA(Genetic Algorithm) is used for optimization of this model. Finally, it is verified by experiments. The validity of the model proves that the combination of BP and GA is an effective way of modeling micro EDM processing and optimization of machining parameters. The establishment of the model has also provided a theoretical foundation for optimization of machining parameters.Based on the multifunctional miniaturized machine tool developed in the paper, some workparts with typical micro structures such as micro thin walls, micro gears, micro shaft electrodes, micro deep holes, rectangular hole and micro thin wall pipe array etc are machined. A micro deep hole with diameter of 30 microns and depth-diameter ratio of 15.7 is machined using a copper micro flatted shaft electrode on the material of Starvax ESR, and another micro deep hole with diameter of 42 microns and depth-diameter ratio of 20.6 is machined by using a copper micro multi diameter shaft electrode on the material of Starvax ESR. The depth-diameter ratio of the two hole is greatly improved compared with the works conducted by previous researchers. In addition, a 2×2 micro brass thin wall pipe array with outer diameter of 100μm and inner diameter of 60μm is machined using both micro milling and micro EDM technologies. It is greatly verified that the multifunctional miniaturized machine tool developed in the paper have an excellent ability of fabricating miniature production with complicated three-dimensional micro structures especially which needs more than one machining procedure and processing technology.