The Study of surface Characterization in Ball-End Milling

通过理论分析和切削实验，阐明了球立铣刀轴向工件倾斜方向和角度、切削条件和切削液对模具表面粗糙度的影响。结果表明，在切削进给方向和截齿进给方向上存在着能获得较小表面粗糙度的最佳倾斜方向和角度。此外，左拾取进给方向优于右拾取进给方向。实验证明，由于形成了连续型的切屑，因此获得良好表面粗糙度的最佳切削刃形状具有较大的真前角和切屑袋。当切削进给速度非常快时，还通过实验研究了从球立铣刀侧面开始切削的影响（这种现象称为“后退切削”）。在黄铜、铝等7种商用材料中，通过对切削实验的灵敏度评价，选择镁合金作为最优材料，通过定义“仿形度”来证明理论表面粗糙度。最小量液法（12cc/min）使刀具寿命延长1.4倍。

This study intends to clarify how the surface roughness in die-making is influenced especially by tilting direction and angle of ball-end mill axis towards the work-piece, cutting conditions and cutting fluids in addition by using theoretical analysis and cutting experiments.The optimum tilting direction and angle in order to get small surface roughness was found to exist and differ in both cutting feed direction and pick feed direction.Moreover, the leftward pick feed direction is better than the rightward one to the cutting feed direction. It was proved by experiments that the best shape of the cutting edge for good surface roughness has the large true rake angle and chip pockets because chips of continuous type are formed.When cutting feed rate is very fast, the effect of cutting which begins from the flank of the ball-end mill (this phenomenon is called 'Regressive cutting') was studied also by experiments in case of backward tilting cutting.Among such seven kinds of commercial materials as brass, aluminum etc, magnesium alloy was selected as the optimum material to prove the theoretical surface roughness by defining 'Degree of Copying' due to sensitivity evaluation on cutting experiments.Minimal Quantity Liquid Method (12cc/min) improved the tool life 1.4 times longer.