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  • 學位論文

泛用端銑刀切削力與切削尺寸誤差預測模式

Cutting Force and Dimensional Error Prediction Models for General End Mill Cutting

指導教授 : 蔡哲雄
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摘要


端銑刀廣泛應用於各種機械加工,是最重要的切削刀具之一。特別是模具加工或特殊元件如葉輪的切削,各型端銑刀如球形端銑刀、牛鼻端銑刀及錐形球端銑刀的應用更是不可或缺。由於端銑刀的夾持方式及有較大的刀長/刀徑比,使得切削時切削力經常迫使刀具沿刀軸方向有明顯撓曲情形,而造成切削尺寸誤差問題。因此在講究高速高精度的加工時代,端銑刀切削力的預測是擬定切削製程的重要參考。 過去有關端銑刀切削力的文獻報告大多是針對平端銑刀,其餘較少見。本文建構一套適用於各型端銑刀銑削力的預測模式,並以Matlab寫成分析程式進行模擬驗證,在輸入刀具的資料、銑削條件以及切削材料的比切削力回歸函數(fitted equation of specific cutting force)等已知條件,即能計算端銑刀迴轉銑削過程三維方向的切削力變化。本文首先建立泛用型螺旋刃端銑刀切削幾何,及任意螺旋刃切削位置的切削厚度計算方法。接著說明本文比切削力及其回歸函數的獲得方法。本文計算端銑刀三維切削力的方法是將切削區域的螺旋刃分割成許多微小短刃,依各微小短刃之切削厚度一一代入合適的比切削力參數以計算該切削點的三維切削力,然後將各短刃切削力加總之。本文最後以各型端銑刀切削7075-T6鋁合金為例,比較本文預測模擬結果與實驗之切削力數據,顯示預測的切削力和實際的切削力在進給方向及垂直進給方向表現相當相近。本文方法簡便,可應用於各型端銑刀粗切削、精切削的受力預測,本文最後應用此切削力模型為基礎,計算切削刀具的撓曲,進而推估端銑刀切削側面的尺寸誤差情形之應用,與實驗量測結果亦相當接近。

並列摘要


End milling cutter widely used in many kinds of machining, especially for die and mould cutting, is one of the most important cutting tools. Besides flat end mill, many other types of end milling cutter, such as ball end mill, bull end mill and tapered ball end mill etc., are being used indispensably for a variety of part machining. In the past, papers regarding end mill cutting forces, flat end mill cutter are much more than the other ones. In this paper, a mechanistic cutting force prediction model for general end milling cutter is presented for predicting end milling forces acted on the cutter during machining. This model is based on chip load, cut geometry, and the relationship between cutting forces and chip load. At first, we formulate the helical cutting edges geometry of a general end milling cutter. Secondly, we describe how the parameters of specific cutting force and their fitted functions were being constructed based on experimentally obtained average cutting forces. Thirdly, to calculate the cutting force by a computer program(in Matlab language) and show relationships between cutting force, end milling conditions and rotation of the cutter by figures. Finally, machining experiments are performed on workpieces of 7075-T6 aluminum to verify the ability of present model and predict end milling forces. The model predicted three directional cutting forces (tool axial force, and two lateral forces) are compared with the measured forces. This model for the prediction of end milling forces provides a useful aid for the analysis of machined dimensional accuracy.

參考文獻


[11] 林忠誠,五軸側銑直紋曲面之切削力分析,碩士論文,國立台北科技大學製造科技研究所, 2007。
[10] 陳政億,球形端銑刀銑削斜面之切削力分析模式,碩士論文,國立台北科技大學製造科技研究所, 2006。
[1] M. E. Martellotti, "An Analysis of the milling process," Trans. ASME 63,667(1941).
[2] W. A. Kline, R. E. DeVor and I. A. Snareef, “The Prediction of Surface Accuracy in End Milling,” Journal of Engineering for Industry, Vol. 104, 1982, pp. 272-278.
[3] F. Koenigsberger and A. J. P. Sabberwal, “An Investigation into the Cutting Force Pulsations During Milling Operations," International Journal of Machine Tool Design and Research, Vol. 1, 1961, pp. 15-23.

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