臺灣博碩士論文加值系統

本研究旨在以電腦數值模擬技術探討球墨鑄鐵單向凝固的過程。以呋喃砂模與水冷式冷激塊所組成之複合砂模做為單向凝固的控制。
首先量測冷卻過程鑄塊內部特定點的凝固冷卻曲線，然後以量得之數據計算鑄件與冷激模面間的界面熱傳係數。
再將球墨鑄鐵已知的熱性質與計算所得之界面熱傳係數，輸入ANSYS有限元素分析軟體裡，並給予適當的起始條件與邊界條件，來模擬澆鑄後，鑄件內部特定點的冷卻曲線。並利用實驗取得之特定點的實際凝固冷卻曲線與模擬結果做比較。
研究結果顯示，配置在複合砂模內的水冷式冷激塊確實有控制熱量單向流通的效果，但太低的水溫其冷激效果不見得會更好。

This study is aimed to simulate the unidirectional solidification process of ductile iron by computer numerical analysis technique. A composite furan mold mounted on top of a water-cooled chilling steel block was used to control the heat flow direction.
At first, the temperature of casting at four different locations were measured during the cooling, and then these measured temperature cooling curves were used to calculate out the interface heat transfer coefficient by numerical method.
The calculated interface heat transfer coefficient together with the physical properties were defined into the pre-processor of ANSYS finite element analysis software, also the initial and boundary conditions were set to simulate the solidification of casting. The cooling curves of casting solidification both from simulation results and measured ones were studied.
It shows that the use of the water-cooled chilling steel block was effectively to provide a unidirectional heat flow, but the chilling effect was not too good by using an circulated water with too low temperature.

中文摘要…………………………………………………………………Ⅰ
英文摘要…………………………………………………………………Ⅱ
誌謝………………………………………………………………………Ⅲ
目錄………………………………………………………………………Ⅳ
符號索引…………………………………………………………………Ⅶ
圖表索引…………………………………………………………………Ⅹ
第一章前言…………………………………………………………..1
第二章原理與文獻探討……………………………………………..3
2.1 球墨鑄鐵之簡介……………………………………………….3
2.2 鑄鐵之凝固…………………………………………………….3
2.3 球狀石墨之成核、成形理論與成長機構…………………….4
2.4 凝固潛熱……………………………………………………….5
2.5 凝固過程的熱傳機構………………………………………….7
2.6 界面熱傳係數………………………………………………….8
2.7 熱傳控制方程式與邊界條件………………………………….8
2.8 呋喃砂模配料………………………………………………….9
2.9 模擬用之材料熱物理性質…………………………………….10
2.9.1 鑄鐵……………………………………………………….10
2.9.2 呋喃砂模………………………………………………….10
2.9.3 冷激模…………………………………………………….10
2.10 有限元素法之分析流程……………………………………….11
2.11 有限元素分析軟體(ANSYS) ………………………………….11
2.12 模型之建立…………………………………………………….12
第三章實驗方法………………………………………………………20
3.1 研究流程…………………………………………………………20
3.2 呋喃砂模與呋喃－冷激塊複合模………………………………20
3.3 熔煉與澆鑄………………………………………………………20
3.4 冷卻曲線之量測…………………………………………………21
3.5 凝固冷卻模擬之起始條件與邊界條件…………………………22
3.6 界面熱傳係數……………………………………………………22
3.7 ANSYS分析流程………………………………………………….24
3.8 分割模型的選定…………………………………………………24
第四章結果與討論……………………………………………………35
4.1 澆鑄件之凝固特性………………………………………………35
4.1.1 凝固之溫度變化曲線…………………………………….35
4.1.2 冷激程度對冷卻曲線之影響…………………………….35
4.1.3 界面熱傳係數與鑄塊表面溫度的關係………………….37
4.2 凝固模擬之特性…………………………………………………38
4.2.1 鑄件與砂模之界面為絕熱……………………………….39
4.2.2 鑄件與砂模界面非絕熱………………………………….40
4.3 實測與模擬之比較………………………………………………41
第五章結論與建議……………………………………………………68
參考文獻………………………………………………………………….70
附錄A 球墨鑄鐵之熱性質………………………………………………73
附錄B 越南矽砂的化學成分與粒度分佈等相關資料…………………74
附錄C 金晶公司呋喃甲醇樹脂及對甲苯磺酸硬化劑之性質…………75
附錄D 原料之化學成分及鑄件目標成份………………………………76
附錄E 球墨鑄鐵材料配重………………………………………………77
附錄F MATLAB核心運算程式……………………………………………78

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