| Summary: | 碩士 === 國立高雄應用科技大學 === 模具工程系 === 103 === Sub-reflector of a head lamp, which covers lateral emission of main light source, and which avoids invalid emission of auxiliary light source, is one of key components in vehicle lighting device. Generally speaking, the sub-reflector design changes in terms of vehicle geometric design and optical design. In design process, a sub-reflector is prone to a bad cooling efficiency because of its complex curve and its non-uniform thickness. In injection molding process, normally, the plastic clotting of thin thickness area is faster than other areas, which causes certain flow resistance and different pressure in areas. Thus, according to the above-mentioned situations, a sub-reflector is prone to deformation, dent, and wrong size, which might become a defective product easily.
This study aims to analyze the warpage of sub-reflector in injection molding process. There are two stages in this study: (a) discuss cooling efficiency in different molding cooling channel configurations (drilled cooling channel configuration, drilled and barricade cooling channel configuration, industry cooling channel configuration). (b) use CAE Analysis Software and Taguchi Method to control forming factors and multi-packing. Furthermore, according to the results of two stages, the study discusses the warpage of sub-reflector.
Therefore, this study shows that the drilled and barricade cooling channel configuration is more significant than other configurations because of minimum temperature of core and cavity. In addition, its molding temperature is the closet to the expected molding temperature. The warpage of a sub-reflector was caused by shrinkage. However, the study initially uses Taguchi Method to know the optimal forming factors (one stage packing), and reuse Taguchi Method to analyze multi-packing. The study finds that packing pressure of forming parameters and the stage-I packing time of multi-packing are more significant. Finally, after optimizing forming parameters, improvement rate was 14.2%.
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