| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 105 === This study investigates the effect of chip thickness on milling stability. The experimental results show that the shearing cutting coefficients increase as the average chip thickness decrease. The trend can be approximated as an exponential decay function. Then, a discretization method based on Newton-Cotes integration is proposed to predict milling stability with high-order forces and high-order process damping. In addition, the varying shearing cutting coefficient are also considered into the dynamic milling system model. The predicted lobes indicate that the milling stability decrease with the chip thickness. In other words, the stability will enhance as the chip thickness increase. This analysis results are confirmed by a series of chatter experiments. Through the presented method, it is also shown that the stability will also increase at low spindle speed region because of process damping. However, it demonstrates that the prediction results disagree with the experiments owing to the assumption of the fixed process damping coefficient in the proposed method. From the experimental results, it is inferred that the process damping coefficients may also increase when the average cutting thickness decrease.
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