Development Of A 3-axis Micro Machine Tool And Experimental Study On Micro Cutting Process

Recently, with the development of miniaturized products in aerospace,medical and electronics and many other areas,the way to manufacture micro components with complex 3-dimensional morphology is getting more and more attentions. The conventional ultra-precision machine tool requires large space.It is energy-consumption and the operational cost is much too high. The MEMS technology, which derived from microelectronics technology has difficulty in manufacturing products with complex 3-dimensional morphology. MEMS can be used on specific materials. Due to those limitations, the above two technology are not suitable for producing 3D components. So the micro machining technology based on micro machine tool, which combined with conventional cutting technology, NC technology and micro machine tool technology, is becoming more and more popular since it emerged. This paper focused on the research on micro cutting process of elastic alloy 3J53, aiming to lay a foundation for the large scale commercial application of micro cutting technology based on micro machine tool.With the help of the precision motion platform which has already been commercially produced, a vertical micro CNC machine tool system has been developed, which ensured that the machine tool can provide enough accuracy. The minimum cutting thickness is the main characteristics of the micro cutting process, it is related to cutter edge radius but it is difficult to be tested through experiment directly. So a finite element simulation considering the size effect has been conducted to obtain the relations between minimum chip thickness and cutting tool edge radius. Then we establish a micro cutting force model through force simulation with consideration of minimum chip thickness and then verify the model through single tooth micro cutting process. In the end, we designed micro cutting experiment to research on the relations between cutting parameters and surface roughness in micro cutting process.The main research work of this paper focused on the following four parts:Development of a 3-axises micro machine tool. To meet the requirements of manufacturing the micro aerospace parts with high efficiency and precision, a micro machine tool has been designed. And a pneumatic counterbalance of vertical motion stage has been developed during the design process. Besides, we proposed a optimized 3-centred gantry structure with better stiffness, which is 12.8% and 14.8% higher on static and dynamic stiffness compared with other structures.Research on the calculation of minuinm chip thickness. First we revised the Johnson-cook model with consideration of size effects. Then a finite element simulation of orthogonal cutting was conducted to acquire the relations between minimum chip thickness and edge radius.Then an single-tooth micro milling experiment was conducted to verify the esdablished model.Modelling of micro cutting force in micro cutting process.Based on the minimum chip thickness values obtained from the previous chapter,micro cutting force has been modelled with considering the minimum chip thickness. With the help of the finite simulation experiment,the coefficient of the model has been calculated.we g In the end a micro milling experiment has been conducted to validate the model.Experimental research on surface roughness in micro cutting process and cutting parameters optimization.. This part aimed to analyze how cutting parameters affect the surface roughness through experimental research. Further we used response surface methodology to establish the surface roughness based on data processing. The central composite method is used in the experimental design and analysis.After modelling, the significance and the degree of fitting of the model has been calculated to demonstrate the effectiveness of the proposed model.