Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/1899
標題: 螺旋刃球形銑刀之切削表面粗糙度探討
An Investigation on the Surface Roughness of Helix Ball-End Milling
作者: 王信誌
Wang, Hsin-Chih
關鍵字: Helix Ball-End Milling;螺旋刃球形銑刀;Surface Roughness;表面粗糙度
出版社: 機械工程學系
摘要: 
近來機械製造精度不斷提高,而資訊產品與數位科技設計的應用更使得產品外形日趨複雜且形狀變化多端,大量應用自由曲面,故加工自由曲面之球銑技術愈發顯得重要,而表面粗糙度更是自由曲面加工追求的重要指標,本文即針對金屬之球銑切削,探討其理論表面粗糙度,並透過實驗設計以驗證該理論之合理性。文中首先以微分幾何建構螺旋刃球形銑刀之刀刃曲線,並且針對文獻不足處進行螺旋刃球形銑刀之刀刃運動路徑分析,再以其刀刃運動路徑為依據,推導加工表面粗糙度之理論模式;為驗證該理論之合理性與適用性,本研究另以低硬度Al-6061鋁合金、中硬度NAK-80模具鋼及高硬度SKD-11合金鋼三種不同性質之材料,透過臥式高速切削中心及立式切削中心,選用螺旋刃與直刃球形銑刀配合不同切削參數進行實驗,實驗結果之表面粗糙度Ra實驗值與理論值誤差小於85%,而Rmax之誤差介於25%至318%,顯示所發展之理論模式雖尚待改進,但已較一般文獻所觀察相差四倍甚至二十倍以上之差距為佳。此外實驗結果顯示螺旋刃球形銑刀較直刃球形銑刀加工之表面精度為佳,亦顯示工件材料硬度愈高實驗值愈接近理論值。

Free surface has been widely employed in industrial products in recent years. Therefore, the ball-end milling technique for machining free surface is becoming more important. As surface roughness is a crucial index of free surface, this thesis focuses on the analysis of surface roughness by ball-end milling. Theoretical analysis of surface roughness based on the motion of cutting edges is first investigated. Experiments to verify the theoretical model are also designed and conducted. The differential geometry is employed to model the cutting edges of the helix ball-end cutter. The trajectory of the cutting edge is then derived from the rotation and translation of the ball-end mill. Based on the trajectory, we derived the theoretical model of surface roughness. To verify the theoretical model, three materials with different hardness  Al-6061 aluminum alloy, NAK-80 molding steel and SKD-11 alloy steel  are machined by ball-end cutters with different cutting parameters through a high-speed horizontal machining center and a vertical machining center. Experimental results showed that errors between the theoretical model and experimental data in Ra are less than 85%, while those in Rmax are between 25% and 318%. Although it implies that the derived model needs further improvement, this result is much better compared with the errors 422% to 2000% in literature. In addition, experimental results also showed that the surface roughness of ball-end milling by helix cutting edge behaves better than that by straight cutting edge. Furthermore, as the hardness of the material increases, the experimental result fits better to the theoretical model.
URI: http://hdl.handle.net/11455/1899
Appears in Collections:機械工程學系所

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