光學鏡片之有限元素網格品質探討暨模仁全方位體積收縮補償法之研究;Investigation of finite element mesh quality and 3D volume shrinkage compensation method in core and cavity design for optical lenses

NCUIR > Engineering College > Graduate Institute of Mechanical Engineering > Electronic Thesis & Dissertation > Item 987654321/81835

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/81835

Title:	光學鏡片之有限元素網格品質探討暨模仁全方位體積收縮補償法之研究;Investigation of finite element mesh quality and 3D volume shrinkage compensation method in core and cavity design for optical lenses
Authors:	蔡嘉軒;Tsai, Chia-Hsuan
Contributors:	機械工程學系
Keywords:	射出成型;光學鏡片;收斂性分析;全方位體積收縮補償法;injection molding;optical lens;convergence analysis;3D volume shrinkage compensation method
Date:	2019-08-22
Issue Date:	2019-09-03 17:25:29 (UTC+8)
Publisher:	國立中央大學
Abstract:	網格搭建在有限元素分析中為重要的技術，直接影響模擬的準確度和計算效率，若使用 Moldex3D 自動建立的 BLM 網格(Boundary layer meshes)，雖然快速簡易但網格品質較差，但使用六面體網格(Hexahedron) 或三角柱網格(Prism)，能大量提升網格品質，唯須手動建立且較耗時，因此本研究建立三種網格，分別是 Prism+Hexa 網格、Mostly Hexa 網格與 BLM 網格，將不同網格之模擬結果與實驗之流動波前形狀、光程差分佈照片比較，來驗證模型準確度，從研究結果得知，Mostly Hexa 網格可獲得較正確的模流分析結果，其次是 Prism+Hexa 網格，而最差的是 BLM 網格。透過收斂性分析，建立不同尺寸的 Mostly Hexa 網格，藉由模擬與實驗的比對，得知 0.04mm 的網格尺寸可獲得較正確的模流分析結果。為了改善光學鏡片形狀精度的問題，業界常見以總體積補償法來優化翹曲品質，但是由於產品的不等向收縮，往往很難達到產品所有部位之精度要求，本研究使用 Moldex3D 提出之全方位體積收縮補償法(3D volume shrinkage compensation method)，以雙面非球面鏡片為模型，使用網格品質最佳的 Mostly Hexa 網格進行模仁補償，從結果顯示，對於光學鏡片之外徑與中心厚度之尺寸精度均有明顯改善。關;In finite element analysis, mesh generation is an important technique, which directly affects the accuracy and computational efficiency of the simulation. Using BLM (Boundary layer meshes) automatically is fast and easy in Moldex3D, but the mesh quality is not excellent. If using Hexahedron or Prism mesh can greatly improve mesh quality but consuming more time. Therefore, this study generate three kinds of meshes, Prism + Hexa mesh, Mostly Hexa mesh and BLM mesh. To verify the accuracy of model, we compared the results of simulation with experimental melt front and optical retardation. The results of the study shows that the Mostly Hexa mesh can bring the correct molding simulation results. The results of molding simulation of Prism+ Hexa mesh are not so correct. And the results of molding simulation of BLM mesh are incorrect. Then, through the convergence analysis, we generate the different size for Mostly Hexa mesh. By comparing the simulation with the experiment, we found that the mesh size of 0.04 mm can bring the through correct molding simulation results. In order to improve the shape accuracy of optical lenses, industry often use the total volume compensation method to optimize the warpage. However, due to the unequal concentration of the product, it is difficult to meet the requirements of all parts of the product. In this research, we use 3D Volume shrinkage compensation method (3DVSCM) for cavity compensation. In conclusion, using 3DVSCM obviously improves the outer diameter and center thickness of the optical lens.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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