| Summary: | 碩士 === 華梵大學 === 機電工程學系博碩專班 === 97 === The main purpose of this paper was to investigate the effect of the down milling and up milling of carbon steel for the different radius of ball end mills on the roughness and geometric finish of the curved surface. The ball end mills with R4, R3 and R2 mm, the different spindle speed and feed rate or reducing spindle speed and feed rate were selected to study the roughness and geometric finish of curved surface.
The experiment results showed that using ball end mills of R4 mm under down milling of the curved surface and lower cross feed can obtain a relatively better workpiece roughness than those of R3 and R2 mm, but a poorer geometric finish. The workpiece surface roughness obtained for down milling was better than that of up milling. Besides, at inflection arcs of curved surface reducing spindle speed and feed rate during milling can improve the workpiece roughness. Relatively, using a smaller radius of ball end mills under down milling can cause a poorer curved roughness, but a better curved surface geometric finish. The reason for this is that the tool of smaller radius produces a larger chatter during milling, causing a poorer roughness. But the better curved geometric finish is attributed to reducing an overcut action at inflection arcs of curved surface.
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