| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 99 === Surface quality of machined products do not only determines the appearance of the products, but also determines the features of products. Novel three-axis milling CNC machines have advantages of high efficiency, high flexibility, high rigidity and high accuracy. Therefore, improving the efficiency and quality of the surface finishing by using three-axis CNC milling machine is a essential issue. This study will use a three-axis CNC milling machine to research the finishing oblique surface and curved surface. Considering the toolpath stepover, stepdown, height of scallop, spindle speed, cutting speed, feed rate, tool radius, slope gradient, radius of curvature, end mills and ball end mills effect on the machined surface.
The experimental results show that feed rate and spindle speed effect surface roughness in the feed direction. The scallop is caused by toolpath and tool radius, and effect surface roughness in cross feed direction. Ball end mills is easier than end mills to get low surface roughness in oblique surface finishing. Furthermore, the surface roughness of oblique in feed direction made by contour toolpath is better than parallel toolpath. For curved surface finishing, using ball end mills with parallel toolpath will produce surface waviness caused by small shape errors of tool. Surface waviness is related to radius of curvature, and can be removed by second processing.
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