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摘要
五軸加工擁有高自由度的特性，可進行自由曲面加工，在模具製造、航太製造等先進製造產業中廣泛使用。五軸加工的路徑規劃主要依據路徑平滑化與降低工件尺寸誤差，依照工件表面之曲率來規劃使用的刀具軸向及進給方向。如果能在事前規劃上考慮到刀具軸向改變對於切削力與工件表面品質的變化，能夠提升加工的品質與穩定性。因此研究五軸加工下刀具軸向改變對於切削力以及表面品質的影響，是非常重要且值得的研究目標。
本研究討論球刀槽銑鋁製工件的情況。透過模擬計算不同刀具軸向下的切削力變化。使用動力計量測五軸加工時的切削力，紀錄使用不同刀具軸向進行槽銑的切削力數據。使用表面粗度儀量測切削後的工件表面，紀錄使用不同刀具軸向進行槽銑的表面品質。根據實驗結果整理出各刀具軸向的切削力變化與表面粗糙度之間的關係，當刀具前傾角(lead
angle)接近零時，因部分接觸點的切削速度很低，會產生刀尖接觸與表面黏附損傷等現象，導致切削力激增且表面品質差。增加前傾角避免刀尖接觸點的切削速度過低，可以穩定切削力與提升表面品質。當刀具向左傾斜，側傾角(tilt
angle)為負時，因為切屑排出方向隨著刀具旋轉方向改變而更傾向往未切削工件方向排屑，增加切屑厚度與堆積現象，造成切削力不穩定與表面切屑黏附。而刀具向右傾斜時切削力較穩定，但是會造成表面產生波浪狀的刀痕。側傾角的正負選擇還可以根據切屑堆積位置做決定，刀具的側傾方向會導致該方向的切屑堆積而減低表面品質，例如側傾角為正時刀具右傾，槽銑後的工件表面靠右側處較為粗糙，靠左側處則較平滑，反之亦然。本研究依據實驗結果整理五軸刀具軸向對於切削狀態之影響，刀具軸向改變會造成某些形況下刀具與工件接觸點的切削速度過低，導致表面品質變差，以及改變刀具軸向造成切屑排出的方向改變，造成切屑的堆積現象。根據本研究的結果可以避免五軸切削時因為使用了不適當的向量而造成切削品質的落差。
關鍵字：刀具軸向、切削力、表面粗糙度、五軸加工、路徑規劃
Abstract
Five-axis machining is characterized by high
degree of freedom and can be used for free-form surface machining. It is
widely used in advanced manufacturing industries such as mold manufacturing
and aerospace manufacturing. Tool path planning for five-axis machining
mainly based on smooth trajectory and reducing form error. Tool orientation
and feed direction are planned according to curvature of workpiece surface.
The quality and stability of machining can be improved if changes in cutting
force and surface quality due tool orientation changes can be considered in
prior planning. Therefore, it is very important and worthwhile to study the
influence of tool orientation change on cutting force and surface quality
under five-axis machining.
This study deals with ball-end slot milling of aluminum
workpieces. The cutting force variations under different tool orientation
are calculated by simulation. The cutting force during five-axis machining
with different tool orientation is measured by dynamic metering. The surface
roughness tester is used to measure the surface of the cut workpiece and
record the surface quality of the slot milling with different tool
orientation. According to the experimental results, the cutting performance
of each tool orientation is sorted out. When the lead angle of the tool
approaches zero, the tool tip contact and surface adhered damage will occur,
which will lead to sharp increase of cutting force and poor surface quality.
Increasing the lead angle to avoid tool tip contact can stabilize cutting
force and improve surface quality. When the tool tilts to the left, tilt
angle is negative, chip thickness and accumulation will increase, resulting
in unstable cutting force and surface adhered . While the cutting force is
more stable when the tool is tilted to the right, but it will cause wavy
tool marks on the surface. The positive and negative selection of the tilt
angle can also be determined by the position of chip accumulation. The
direction of tool tilt will result the chip thickness incre
Keyword：tool
orientation, cutting force, surface roughness, 5-axis machining, path
planning
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