陶瓷模具應用於曲面玻璃光學鏡片之自重成形研究

Abstract

曲面玻璃光學鏡片加工技術難度高，目前加工方式以研磨、模造、自重成形為主。本實驗室曾以不銹鋼Stavaxesr為模具材料，進行自重成形研究，其製作之成品表面粗糙度不佳。為了製作更高表面品質需求之曲面光學鏡片，本研究將以陶瓷材料取代不銹鋼作為模具材料，並以智慧型手環之曲面玻璃鏡片為載具，進行自重成形之有限元素分析與實驗驗證。 於玻璃自重成形實驗中發現，碳化矽模具上DLC鍍硬膜層能有效抗粘黏，並且發現模具目標溫度於485度時為最佳製程參數；而於特定陶瓷模具玻璃自重成形實驗中，發現特定陶瓷不需鍍膜就能擁有良好抗粘黏特性，但其熱傳係數低，模具表面溫度容易比模具中心高，因此以較低之加熱速率(< 20 ℃/min)確認模具溫度均勻性(亦需較長之加熱時間)。而本研究之有限元素分析對比實驗後，能預測玻璃因溫度上升而成形之趨勢，但對邊緣之厚度與高度預測仍不夠準確。 關鍵字:陶瓷模具、曲面光學玻璃、自重成形、有限元素

The demand in making curved optical glasses is increasing for 3C products. The possible processes for manufacturing these glasses are grinding and polishing, glass molding and glass sagging. The researcher in our lab had used Stavaxesr stainless steel as the mold material for glass sagging process, but the experimental product suffered from low surface quality. In order to process a high surface quality curved optical glasses, e.g. curved cover glasses on the smart band, this study replaces stainless steel with ceramic mold materials to improve glass sagging process. With SiC mold for glass sagging, experimental results showed that good anti-sticking property can be obtained if DLC was coated on SiC surface and the working temperature of mold was kept at 485 ℃. With the other mold material, a specific ceramic material provided by supplier with unknown specifications, experimental result showed this specific ceramic mold had very good anti-sticking property even without any coating. The specific ceramics have relatively low heat transfer coefficient, therefore, lower heating rate(<20℃/min) is needed to avoid high temperature gradient between center and surface of the mold. Comparison between the results of the forming experiment and finite element simulation showed that, the simulation can well predict the trend of glass sagging and process. However, discrepancies were observed on the thickness and height of the specimen edge. Further investigations are proposed to overcome these problems. Key words: Ceramic mold, Curved optical glass, Glass sagging, Finite element