曲面加工等扇形高螺旋刀具路徑規劃

Constant-Scallop Height Spiral Tool Path Planning for Surface Machining

陳彥甫(Yen-Fu Chen)

指導教授 ： 蔡哲雄

國立臺北科技大學/機電學院/製造科技研究所/碩士(2011年)

摘要

曲面切削使用螺旋刀具路徑可節省加工時間及使加工零件表面有流線形的外觀。大部分螺旋路徑規劃都沒有考慮殘留於加工曲面上的扇形餘料是否均勻。本文探討兩種考量等扇形高之螺旋刀具路徑規劃法，分別應用於旋轉掃掠曲面及一般矩形曲面。旋轉掃掠曲面方面，首先是以扇形餘料高之裕度為基準，將控制曲線(用來旋轉掃掠曲面的曲線)劃分成若干弧長的刀具路徑間距，每一個路徑間距即為螺旋路徑的節距。接著再劃分每一個弧長區間為適當數量的分割點，這些分割點決定刀具在曲面上繞一圈的切削點數。最後螺旋路徑在曲面上的所有切削點可由旋轉掃略曲面參數方程式來求得。在一般矩形曲面方面，本文建構一矩形螺旋路徑切削模式，由矩形曲面外圍開始連續切削往內到中心部分。這個路徑模式的建構需要兩個步驟，第一是先在曲面上求解兩組相互交叉並考量等扇形高的Zig-型刀具路徑，接著對所有建構的刀具路徑進行重新排列以一個合適的順序產生矩形螺旋刀具路徑。本文以Matlab撰寫程式執行螺旋刀具路徑規劃，並應用CAD/CAM系統模擬測試，並將路徑資料轉成NC碼在CNC機器上實作切削，以驗證本文方法的正確性與效用。

關鍵字

螺旋刀具路徑 ； 等扇形高 ； 旋轉掃掠曲面

並列摘要

Surface cutting with spiral tool paths can save the machining time and take a streamline appearance of the part. Most of the spiral tool path planning does not take into account whether the residual scallop material on the machined surface is uniform or not. In this paper, two spiral tool path planning methods with constant-scallop height were been studied for rotational swept surface and general rectangular surface machining respectively. First, in the rotational swept surface, divide the control curve (the curve to generate the swept surface by sweeping) into several intervals based on the tolerance of the residual scallop height. Each interval is just the pitch of the spiral tool paths. Second, divide each arc length interval into some suitable partition points which determine the number of tool cutting points in one revolution on the swept surface. Finally, all the cutting points on the spiral tool paths can be calculated by applying the parametric equation of rotational swept surface. In the general rectangular surface, we develop a rectangular spiral tool paths pattern which machines the part surface from periphery to the inner centre successively. The generation of this tool paths pattern need two steps. To begin with, two set of Zig-type tool paths on the surface in cross directions must be computed with constant-scallop height path interval. Then, make a rearrangement for all the computed tool paths to generate rectangular spiral paths in a proper sequence. In this paper, a Matlab program was constructed for executing present algorithm. Some examples, including rotational swept surface and rectangular surface for spiral tool paths planning, were performed. The planned spiral tool paths also simulated in CAD/CAM system and machined on a CNC 5-axis machining center for demonstrating the validity of the proposed method. The results reveal that the proposed method is valuable.

並列關鍵字

Spiral tool path ； Constant-scallop height ； Rotational swept surface

參考文獻

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