- 學位論文
田口方法於射出成型機之頂出力與熱澆道澆口冷卻系統之研究
A Study for Taguchi Method on Ejection Force of Injection Molding and Cooling Design of Hot Runner Gating System
摘要
本文第一部分結合電腦輔助工程分析(Computer Aided Engineering, CAE)以及田口方法(Taguchi Method)，探討塑膠射出成型中，頂出機構設計之多項因素對於塑膠成品脫模所需之頂出力的影響，提出設計頂出系統參數最佳化設計之方法。首先為了瞭解實驗與分析數據之差異性，本文以CAE分析軟體(ANSYS)，模擬塑膠成品在脫模時所產生的摩擦應力及變形量，與文獻上之實驗數據做驗證 ，確定軟體模擬的正確性。接著參考塑膠成品設計的經驗法則，建立成品之有限元素模型，以頂針直徑、數量、位置以及接觸形狀做為田口方法的控制因子，成品頂出時之總頂出力做為品質特性。將所得之結果利用田口方法找出最佳之設計參數，與實際案例之CAE分析做比較，探討影響頂出力之因素，提供設計頂出機構時的參考依據。 第二部分探討在熱澆道系統中，冷卻系統對熱傳效能的影響。塑料在熱澆道中藉由加熱管加熱之傳導性，持續被加熱以達到塑料保持熔融狀態，做為下一次射出成型所需材料。熱傳效能的探討在此機構設計的影響極為重要；過高的模溫將會提升產品的不良率與縮短熱澆道使用之壽命，所以冷卻水路的設置也是影響熱傳效率的重要因素。而澆口處溫度若是太低，易使熔膠冷卻固化而在下一次射出時將硬料填入模穴；溫度若是過高，則會使熔膠趨於液化減低黏滯性，易造成毛邊等問題使產品外觀受影響。本文配置影響冷卻效能之多組實驗；經由CAE軟體模擬多個實驗組之冷卻結果，並從多組分析結果中了解如何控制噴嘴溫度在適當範圍，建立整合一完整資料庫；因熱澆道內部設計及技術不易取得，從CAE分析結果可以協助建立噴嘴系統與冷卻水路，並將優化設計流程推廣至開發熱澆道或快速模具變溫等新製程，使成品受熱均勻，減少翹曲或收縮現象產生，且不需經由二次加工，也可達到高亮度的外觀面。
並列摘要
Combing with Computer Aided Engineering, CAE, and Taguchi Method, the first part of the study discusses, in plastic injection molding, the influence of the factors in designing ejection machines on the ejection force when stripping plastic molds. It proposes a way to design the optimization of designing ejection parameters. To understand the differences of the experiment data and analysis data, the study uses CAE analysis software, ANSYS, to simulate the friction stress and deformation produced in stripping the plastic molds. To ensure the validity of the simulation, the study verifies the simulation with the experiment data in the bibliography. Then, it consults with the rules of thumb in designing plastic molds and builds the finite element mold of the product. The diameters, numbers and the position of the ejector pin and the connecting shape are the controlling factor in Taguchi Method. The deformation of the product when accepting stress is the quality feature of the product. With Taguchi Method, the study uses the result to find out the optimized design parameters and compares it with CAE analysis of actual cases. It discusses the factors of the ejection force and provides references of designing ejection machines. The second part of the study discusses how the cooling system influences the heat transfer efficiency in hot running system. The plastic is heated up and kept in molten state in the hot runner by the heating tube. It is the material for next ejection. The discussion of heat transfer efficiency in designing the machine is crucial. High mold temperature will raise the rejection rate and shorten the life of the hot runner. Therefore, the setting of cooling water circuit is one of the important factors affecting heat transfer efficiency. The molten plastic will clot and stuck the gate if the temperature at the gate is too low, whereas, high temperature lowers the viscosity of the plastic and causes flash and affects the appearance of the products. The study sets up many experiments that affect cooling efficiency, through CAE, it simulates the cooling results in the different experiments and learns how to control the nozzle temperature within proper range and then builds up a complete database. Because the interior design and the skill of hot runners are difficult to acquire, CAE analysis can support the building of nozzle system and cooling water circuit. The optimized design process can be promoted to the developing process of hot runner or rapid mold heating, helping the product obtain even heat and reducing warpage and shrinking. Through the process, the product can have bright cosmetic without second process.