本文主要探討切屑厚度對切削係數的影響及其與銑削穩定性之關係，同時建立包含再生效應和製程阻尼的穩定圖來預測銑削穩定性。首先利用剪切效應和剪犂效應兩種模式來預測銑削力，並從實驗的平均力求得FCD400 材料在不同平均切削厚度下的切削係數。從切削係數實驗結果中發現，剪切係數會隨著平均切屑厚度下降呈現近似指數拉升的趨勢，切向的犁切係數則隨著平均切屑
厚度增加呈現近似線性上升的關係。接著本文將隨著平均切屑厚度變化的剪切係數考慮到動態銑削模型中，並基於離散概念和辛普森積分法建立每刃週期下的轉移矩陣來預測銑削穩定性，此模式包含高階動態力和高階製程阻尼力的影響。從分析結果發現當切屑厚度變小時，系統穩定性會有降低的趨勢；反之，當切屑厚度變大則系統穩定性提高，此趨勢與實驗結果相符。從分析結果也得知，在低轉速區由於受到製程阻尼影響，極限切深會有拉升的趨勢。但與實驗結果比較後發現，以固定的製程阻尼係數無法準確預測系統在低轉速區的穩定性，並從實驗結果推斷製程阻尼係數也可能會隨著平均切削厚度變小而有變大的趨勢。

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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