|
現今拋光技術對於球面鏡面加工製程已趨近成熟，可以達到很高的表面形狀精度，但在光學系統中的使用上球面透鏡仍存在像差問題。為了改善此現象，球面透鏡常以多片鏡面組合，但卻也降低鏡組之對比度且增大了光學系統之體積。非球面鏡片便為因應此現象而生，其局部曲率半徑隨著徑向位置而改變之特性，能有效改善像差問題，但製程上相對困難，無法以固定曲率模具進行研磨拋光，若能利用電腦輔助進行小口徑軟質拋光頭的數控拋光，加工出良好之加工表面，便能有效提升製程效率且大幅提升國內拋光技術，增進產業競爭力。
本論文針對數控拋光應用於非球面鏡面製程之參數配置進行研究，以提供佳化之拋光策略與參數之設定。在過往研究中，發現到小口徑軟質氣囊式拋光頭運用於數控拋光有嚴重中低頻表面紋理之產生並且主導工件之峰谷值(Peak-to-Valley)和方均根值(Root-Mean-Square)，且於後段之精加工十分難以被抑制，本論文特別針對此段表面紋理問題進行研究，而藉由實驗與表面分析結果得知，數控拋光之拋光頭偏置量對於加工所產生之紋理並無直接之影響關係；拋光頭轉速與拋光頭進給速率，則為表面紋理產生之關鍵性影響因子。若加工參數之設定未控制於適當之參數範圍內，則會產生嚴重之表面紋理。藉由控制拋光頭加工之路徑間距迴避機台自然震動所產生之定頻紋理之頻率，則可有效改善表面品質，並抑制紋理之產生。本研究藉由所歸納出數據與參數設定之分析，針對拋光製程中表面輪廓修整階段所提之拋光頭進給速率建議，與移除次表面破壞層最後拋光階段之定材料移除率之加工參數組，經過分析比較與實驗驗證，確實能有效提升拋光後表面品質並明顯抑制數控拋光加工中所產生之中低頻表面紋理，進而降低拋光過程所需時間及人力成本，並大幅提高拋光加工之工件品質。
關鍵字：精密數控拋光、非球面製程、氣囊式拋光、表面品質、表面紋理
Polishing techniques on spherical
lenses have reached a certain level recently. However, issues
such as chromatic aberration and optical distortion are still
left unsolved when it comes to application. In order to solve
the problems, spherical lenses are often used as a combination
of lenses. Unfortunately, it reduces the contrast of the image
through the lenses, and it increases the volume of the optical
system. Aspherical lenses were then born in response. They
overcome the aberration problem by having different local
curvatures which are based on the radial distances. Nonetheless,
it increases the difficulties of the manufacturing procedures
since aspherical lenses cannot be polished or grinded with
traditional polishing techniques. Only if the computer-aided
bonnet polishing on a fine quality surface fabrication is
available, the domestic polishing techniques could be improved
substantially while enhancing the industrial competitiveness
The research
focuses on the parameters of the computer-aided polishing that
are applied on the manufacturing process of an aspherical lens,
in order to optimize the parameters and the polishing
strategies. In the past studies, it was found that obvious
low-to-mid spatial frequency errors occurred during the
polishing process, which increased the values of the surface’s
Peak-to-Valley values and the Root-Mean-Square values, and it is
hard to be eliminated. This study is mainly concerned with the
surface texture problems formed during the polishing process.
According to the experiments and the analyzation results, the
offsets of the tool have no direct effects on the results of the
surface textures. The heads' speed and the tool feed rate are
the two main factors, that will worsen the surface quality when
they are not under controlled in an appropriate processing
range. By determining the track spacing of the pitch, it can
resolve the surface texture problem caused by the machine
vibration. The optimization of parameters and polishing
strategies in the study of the aspherical lenses manufacturing
are conformed to improve the surface quality and eliminate the
low-to-mid spatial frequency errors occurred during the
computer-aided polishing processes. Additionally, the cost of
the polishing process can be decreased while improving the
product quality significantly.
Keywords:
Computer-aided polishing, Aspheric lens manufacturing, Bonnet
polishing, Surface quality, Surface texture |
