Abstract
本論文主要探討塑膠射出成型品之收縮與翹曲變形及其凹痕行為, 包括結 晶性高分子材料與無定形材料之產品; 並建立一套整合性分析軟體,結合 了電腦輔助工程分析技術與高分子加工理論, 模擬整個射出成型充填, 保壓及冷卻過程中塑料的動態行為, 以及成品脫模後塑件的收縮與翹曲變 形及凹痕情形, 以幫助吾人進行模具設計及加工條件抉擇的參考。本文所 探討之基本理論包括: 模具冷卻分析, 高分子在射出成型過程中的充填, 保壓及冷卻行為, 高分子流體之黏彈性行為, 高分子熱性質與機械性質的 影響, 高分子壓力- 體積- 溫度行為之探討, 高分子之結晶現象, 以及成 品脫模後的固體力學分析等。所以本文考慮下列效應: 不均勻冷卻過程, 不均勻體積收縮, 殘餘流動應力與熱應力, 高分子結晶行為,加工條件, 及成型品之幾何效應等。文中以平板及T 形模穴與多T 形模穴進行分析, 使用材料為結晶性材料之聚丙烯(PolyPropylene)及無定形材料ABS, 預 測成型品之結晶度分佈,及其收縮與翹曲變形及凹痕大小。本文並以平板 模具進行實際射出, 量測成型品之收縮與翹曲變形大小。 The behavior of shrinkage, warpage and sink mark of plastic injection molded parts including the crystalline and amorphous polymers have been studied in this dissertation. An integrated program, coupling the computer aided engineering technique and the polymer processing theory, was also developed in this pre- sent study to simulate the dynamic behavior of injection mold- ing filling, packing and cooling processes and the shrinkage, warpage and sink mark of parts after ejected from the mold. Thus the mold design and the process conditions may be followed from the above analytical results. The basic theory in the present research considered the fol- lowing items: the mold cooling analysis, the behavior of polymer melt in injection molding filling, packing and cooling processes, the viscoelastic behavior of polymeric fluid, the influence of thermal and mechanical properties of polymer, the pressure- volume-temperature relationship of polymer, the crystallization kinetics of crystalline polymer and the solid mechanics analysis of part after ejected from the mold. Effects upon the Shrinkage, warpage and sink mark of plastic parts were considered, e.g. nonuniform cooling process, nonuniform volume shrinkage, flow- induced residual stress, thermal-induced residual stress, behav- ior of polymeric crystallization, processing conditions and the cavity geometrical effects, etc. The integrated program was applied to predict the degree of crystallinity and the shrinkage, warpage and sink mark of part of the crystalline polypropylene and amorphous ABS for the plate, T-shape and multi-T-shape cavities. In the dissertation, the exp- erimental plate mold was used to measure the dimensions of the actual part.