|Abstract: ||背光模組(back-light module)內的增亮膜((Brightness Enhancement Film, BEF)是TFT-LCD之必要光學元件且朝向大尺寸發展，此系利用已完成微結構切削之金屬滾軸進行roll to roll制程，壓印出所需之光學結構膜，所以大尺寸滾軸微結構加工是終端產品的先決條件。增亮膜如果能以兩張V溝(V-groove)互以90度堆疊形成金字塔結構(pyramid)者，不僅可提高輝度達110%，同時一次壓印下還可降低背光模組的厚度與制程簡化。但是V溝切削不良除了容易造成邊緣型毛邊(side burr)之外，而金字塔結構屬於不連續切削，不僅會造成離斷型毛邊(exit burr)之外，更會讓刀具急劇磨耗，使微結構變形。而適合難切削材料的橢圓振動切削(Elliptical Vibration Cutting, EVC)和飛刀加工(fly-cut)，在粗糙度和切削速度上都遠遠不及于單點鑽石車削(Single Point Diamond Turning, SPDT)切削延展性金屬所能達到的奈米級鏡面和加工速度。|
本文研究發現除了不適當的切削條件外，不同微結構切削時也會產生不同的毛邊問題。同時過去傳統精密切削加工的研究中，也忽略了菱鏡(prism)結構相鄰之間的切削干擾及因為切屑的剝離不良所導致的新毛邊問題。最後針對來源不同或未知的材料，如何能在加工前預測出最適合的切削條件及有效的毛邊抑制方法進行了探討。本文研究首先透過有限元素分析( Finite element method , FEM)對毛邊的形成進行預測，接著以單點鑽石車削無氧銅為實驗基礎，利用固定荷重(fix-loading)與固定切深(fix-feed)之刮痕模式對毛邊形成機制進行討論，最後根據不同刀具設計、不同微結構與切削條件，在CNC上進行滾筒模具切削。研究結果顯示:(1)切削時刀具會對被切削材料V溝的兩側擠壓而形成邊緣型毛邊，(2)切削阻力越大者在離斷的材料端面上越容易形成離斷型毛邊，(3)V溝菱鏡結構閉合後因波峰兩兩拉扯下會形成一種新的波浪型毛邊(wave burr) 問題，(4)離斷結構切削時，切屑的脫離不良除了邊緣型毛邊外還會導致新的剝離形毛邊(stripping burr)問題，(5)spiral cut能改變進給方向以平衡切削力者可以改善不對稱切削的毛邊，(6)plung cut的微量切削特性可以抑制離斷型毛邊，(7)切屑面的皺摺間距越細則顯示該材料的被切削性越好。
The backlight module of the Brightness Enhancement Film( BEF) is a necessary element of optical TFT-LCD and towards the development of large size. Using the metal roller which has been finished cutting micro structure first, and then used roll to roll process to stamping out the required optical structure, so large size roller processing is a prerequisite for terminal products. If can be stacked with two V-groove of BEF film to form a Pyramid structure at 90 degrees, it can not only increase the brightness to 110%, but also reduce the thickness and process simplification of the backlight module at one time. V-grooving cutting bad, in addition to easy to cause the side Burr, and the Pyramid structure is not continuous cutting, so will not only cause the formation of exit Burr, will be the tool wear and then micro structure deformation. And suitable to the hard cutting materials of elliptical vibration cutting (EVC) and fly-cut, the cutting roughness and speed is far inferior to the single point diamond turning (SPDT) cutting the malleable metal can reach Nano scale mirror and processing speed.
The paper is found that in addition to the improper cutting conditions, different micro structures also produce different burrs when cutting. At the same time, in the past research on the traditional precision cutting, the cutting edge interference between the prism and the new burrs caused by the poor peeling of the chip have also been neglected. Finally, how to predict the most suitable cutting conditions and the effective methods of cutting edges are discussed for different sources or unknown materials. The paper through the finite element method (FEM) to predict the burr formation followed by single point diamond turning on Oxygen free copper as the experimental basis, mechanism of burr formation was discussed by using the fixed load and fixed cutting depth of scratch mode. Finally, we are according to different cutting tools design and different micro structure and cutting condition to do the cutting experiment of the roller is carried out by using CNC. The results show that: (1) The tool will be extruded on both sides of the V groove of the cutting material to form side burr at cutting. (2)The larger of cutting force Is more easily to exit burr formation on the material of end face. (3) A new wave burr problem is formed after V grooving is closed and the wave peak interferes with each other. (4) When cutting the discontinuous structure, the discontinuous chip will lead to a new peeling burr problem when it breaks away from the material surface. (5) Used spiral cut can change the feed direction to balance cutting force, and can improve the cutting burr of asymmetrical cutting. (6) The micro cutting characteristics of plunge cut can inhibit the exit burr. (7) The same material but different hardness, the chip of the wrinkles spacing is more fine and it shows that the material is better cutting.