Heat Transfer Analysis of a Small-Mouth Hot Sprue For Injection Molding of Plastics

本研究使用CAE軟體-ANSYS針對塑膠射出成型模具所用之一種小澆口熱澆道元件進行暫態與穩態之熱傳分析，研究中先針對三個不同設計之模型，分別分析其穩態加熱時所需之功率與溫度場之分佈情形，分析中選取五項參數:(1)澆道入口面的溫度(2)熱澆道與模具接觸面的溫度(3)熱澆道元件中主體材料的熱傳導係數(4)加熱棒的數目(5)加熱棒與流道間的距離，以進行各項參數對熱澆道元件中流道壁面之徑向與軸向溫度分佈的影響。然後針對NCHU(中興大學)製作之熱澆道元件進行加熱過程中暫態溫度變化之量測，並與軟體模擬之結果及美國DME熱澆道元件之實驗量測之結果進行比較，研究結果顯示，模擬分析之結果與實驗量測之數據大致吻合，而NCHU熱澆道元件由30℃加熱至240℃需時150秒，而維持穩態之總加熱量為38.4W，此元件經實際裝置於模具上進行射出成型測試，其性能已達到一般射出成型所需之要求。This work adopts a CAE software–ANSYS analyzing the heat transfer in a small-mouth hot sprue which is used in injection molding of plastics. Three different designs were considered. A steady-state heat transfer analysis was performed for obtaining the required power consumption and temperature distribution on the surface of the flow channel. Five variables were selected, namely, surface temperature at the inlet of hot sprue, contact surface temperature between hot sprue and mold, thermal conductivity (K) of main body, number of heating bars, distance between heating bar and melt. For various conditions, the axial and circumferential temperature distributions on the surface of the flow channel were obtained. In the experiment, the heating rate of a hot sprue manufactured by the NCHU was tested. The experimental data were compared to the simulation result, as well as to the measured data from a hot sprue manufactured by DME Co.. The comparison shows a good agreement between the measured data of the NCHU hot sprue and computer predicted result. The result also shows that it takes 150 seconds for the NCHU hot sprue heated from 30℃ to 240℃. In the steady-state operation, the total power consumption is 38.4 Watts. The NCHU hot sprue was also installed in a mold to proceed injection molding. The result shows that its performance fulfills the general requirement for injection molding.中文摘要..............................................................................................................i 英文摘要.............................................................................................................ii 目錄....................................................................................................................iii 表目錄................................................................................................................vi 圖目錄...............................................................................................................vii 符號說明.............................................................................................................x 第一章 簡介.....................................................................................................1 1.1 前言............................................................................................1 1.2 澆道系統的分類........................................................................2 1.3 使用熱澆道的目的....................................................................3 1.4 熱澆道系統的優缺點................................................................3 1.5 熱澆道系統常見的配置方式....................................................4 1.6 文獻回顧....................................................................................5 1.7 研究目的....................................................................................8 第二章 熱澆道之構造...................................................................................10 2.1 主體部分..................................................................................10 2.2 射嘴部分..................................................................................10 2.3 與模具接觸部分......................................................................11 2.4 加熱棒部分..............................................................................11 2.5 電熱偶線..................................................................................12 第三章 熱傳分析模式...................................................................................13 3.1 熱傳基本理論..........................................................................13 3.1.1 熱傳導基本理論.........................................................13 3.1.2 熱對流基本理論.........................................................13 3.1.1 熱輻射基本理論.........................................................14 3.2 能量平衡方程式......................................................................15 3.3 溫度場之有限元素分析..........................................................16 第四章 有限元素模型之建立.......................................................................21 4.1 分析流程與前置設定..............................................................21 4.1.1 設定元素形式.............................................................22 4.1.2 設定材料性質.............................................................22 4.2 建立有限元素模型..................................................................22 第五章 模擬分析之結果...............................................................................24 5.1 三種不同熱澆道元件設計之暫態溫度分佈曲線..................24 5.1.1 三種設計之構造與分析模式.....................................24 5.1.2 第一種(case(i))熱澆道元件之暫態溫度分佈曲線....26 5.1.3 第二種(case(ii))熱澆道元件之暫態溫度分佈曲線...29 5.1.4 第一種(case(iii))熱澆道元件之暫態溫度分佈曲線..30 5.1.5 初始加熱功率對加熱時間之影響.............................31 5.1.6 流道橫截面溫度分佈之均勻性.................................31 5.1.7 三種熱澆道元件性能之比較.....................................31 5.2 澆道入口面溫度對溫度分佈之影響......................................32 5.3 熱澆道與模具接觸面溫度對溫度分佈之影響......................34 5.4 k值對溫度分佈之影響...........................................................36 5.5 加熱棒數目對溫度分佈之影響..............................................37 5.6 加熱棒與流道間距離對溫度分佈之影響..............................38 5.7 小結............................................................................................38 第六章 熱澆道暫態加熱過程之量測與分析...............................................39 6.1 實驗過程..................................................................................39 6.2 實驗結果與模擬分析之比較..................................................40 6.3 實際測試之結果......................................................................41 第七章 結論與建議.......................................................................................42 參考文獻...........................................................................................................4