- 學位論文
PVT控制技術建置與應用於射出成型品質控制之研究
Investigation on the establishment of PVT control method and its application to injection molded part quality
摘要
壓力-比容-溫度(PVT)關係為高分子相當重要的特性，其隨著成型的溫度或壓力變動比容也會有所改變，尤其整個射出成型的週期中高分子熔膠之變化難以預測，導致產品品質與精度難以掌控。以往需靠有經驗的人工做參數調整，未有一科學化的調整基準，使得良率維持上相當困難，如何建立一成型技術以科學化的試模與成型穩定監控則是開發的重要關鍵。本研究以紅外線溫度感測器與壓力感測器建立模穴實際PVT歷程監測技術，針對射出成型過程做熔膠充填的數據監視。另一方面，透過此PVT數據做基礎參數於品質控制性研究，探討不同參數下PVT歷程與品質控制性的關係。最後則使用此技術討論不同控制法的品質控制與連續射出成型穩定性，以現有監測技術與本研究所建立之技術做品質重複精度討論。希望透過此監控技術達到品質控制之目的，同時也可改善連續生產之產品變異的問題。 研究結果顯示，PVT監測技術成功取得成型時的PVT歷程，且數據相當穩定。在基礎參數對品質控制性則說明了不同參數設定對於PVT歷程有不同影響，PVT歷程對產品品質也有直接相關。充填過程中會產生剪切熱並於PVT歷程中顯示，其不同溫度與充填時間將影響剪切升熱的程度。動態PVT品質控制法可有效改善產品品質結果，其產品精度可提升超過40%，其他品質也有不同程度的改善。最後在連續射出成型穩定性方面，PVT監控技術可有效提升品質精度，其重量重複精度提升54%、收縮重複精度提升23%、翹曲重複精度提升12%。此監控技術之應用可提供一科學化的參數調整依據，並且不僅可優化產品品質狀況更進一步的穩定連續射出成型之品質重複精度，對於傳統射出成型所面臨的問題提出一有效的解決方案。
並列摘要
PVT relation is one of important properties for polymer processing which is affected by temperature and pressure changes. Due to the unpredictable property, it is difficult to produce with constant quality during consecutive molding process. Traditionally, the qualities of injection molded part rely on experienced operator for adjusting molding parameters; however, those parameter modifying processes are without scientific theory and standard procedure. It becomes an essential research issue for now on. This study based on the PVT theory created a practical PVT monitoring technology by using infrared temperature sensor with pressure sensor set in the mold. With those two practical data, PVT course can be described. Consequently, PVT monitoring technology was utilized to investigate the influence of molding parameters to the controllability of product quality, optimizing product quality, and molding stability. The result shows that the PVT curves are constant under consecutive molding cycle. PVT, at the same time, reveals that the influence between molding parameters and quality controllability. Specific volume is directly related to product quality such as shrinkage, weight, warpage, and tensile strength. Shear heating was observed by PVT curves under different temperature setting and filling times. On the other hand, four control methods for optimizing product qualities were investigated. Dynamic PVT control method can mold a part with smallest total shrinkage, heaviest weight, less warpage, and greater strength. For molding stability, PVT control method can constant molded quality not only on product weight but also on shrinkage and warpage. The method resulted in 54% shrinkage repeatability precision up to the traditional producing process, 23% in weight repeatability precision, and 12% in warpage repeatability.