Study of optimum tool change time in v-groove roller turning

• Main Authors: Yung-An Hung, 洪永安
• Other Authors: 廖運炫
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/31705159525429913309

碩士 === 國立臺灣大學 === 機械工程學研究所 === 96 === Brightness Enhancement Film (BEF) is one of the most important components in the Back Light Unit. The v-groove configuration of BEF is duplicated from the roller by roll-to-roll process. In order to enhance the luminance of the light source, the microstructure of the v-groove has to maintain two requirements which are form error for μm and mirror surface. The roller is cut by the ultra-precision diamond turning tool. To meet the current requirements of manufacturing larger size of LCD (Liquid Crystal Display), the roller has to become longer and larger in size. Hence in consequence the cutting distance becomes much longer and accompany the problems of chipping and wear of cutting tools for the long time tooling, indeed, roller is no usable. Furthermore, the diamond tool doesn’t been discarded arbitrary because it is very expensive. At present there is no other way for most manufactures except by naked eyes to estimate whether it is the time to change the tool. Moreover estimating with human eyes cannot accurately decide the critical point of surface brightness and is also ineffectual for automatic manufacturing. Thus an optimum method to estimate the time to change tool is developed in this research by quantification of the brightness from work surface, setting an experimentally determined threshold value of 240, i.e., as the brightness value is under 240 the tool has to be changed. As far as the tool is changed the developed system would determine the diamond tool tip shrinkage for follow-up compensation by machine vision in order to match the position of the new tool tip after reinstallation with worn tool position before detachment. This process allows the roller to turn continuously and finish fabrication.