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題 名 | 鋁合金消失模鑄造法界面熱傳係數之量測與其在凝固模擬上之應用=The Measurement of Interfacial Heat Transfer Coefficient and Its Application to the Solidification Model for Evaporative Pattern Casting of A356 Aluminum Alloy |
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作 者 | 陳瑞琴; 黃文星; | 書刊名 | 鑄工 |
卷 期 | 24:4=99 1998.12[民87.12] |
頁 次 | 頁24-40 |
分類號 | 472.2 |
關鍵詞 | 消失模鑄造; 凝固熱傳解析; 界面熱傳導係數; 鋁合金鑄造; Evaporative pattern casting; Solidification heat transfer analysis; Interfacial heat transfer coefficient; Aluminum casting; |
語 文 | 中文(Chinese) |
中文摘要 | 本研究主要的目的是希望深入了解 A356 鋁合金消失模鑄造法在鑄造過程中凝固熱 傳的變化。所以本研究利用一維熱傳的實驗數據配合 Inverse Method 來量測消失模鑄件與 無黏結劑砂模之間的界面熱傳係數,並且利用所量得的界面熱傳係數值放入凝固模擬的程式 中預測鑄件在凝固時溫度對時間的變化,並將預測結果與實驗量測結果做一個比較。 在實驗量測部分,主要是界面熱傳係數量測所需的一維熱傳系的實驗設計。本研究利用 CO �祝熉狳茤T定無黏結劑砂模內之熱電偶, 並且在保麗龍模型四周鋪上耐火棉來逼近一維 熱傳。除此之外,對於凝固時鑄件溫度的變化,本研究亦做了長方形與階梯形二鑄件的溫度 量測實驗,並將其結果與模擬的結果做一個比較,討論這兩者的差異性並提出除了界面熱傳 係數以外其他可能影響的因素。在界面熱傳係數的計算上,除了用 Inverse Method 計算出 界面熱傳係數的值以外,並將其做了單方向性一維熱傳的驗證。若以鑄件表面的溫度來界定 其值的話, 約可以分為: A356 鋁合金液相線溫度以上, 界面熱傳係數約為 0.0120 ( cal/sec . cm �插D。c);共晶點溫度以下,約為 0.0060 ( cal/sce . cm �插D。c) ;而二者之間約為 0.0080 ( cal/sec . cm �插D。c' )左右。 在鑄件凝固溫度的模擬 方面,除了考慮界面熱傳係數的影響外,本研究利用文獻的實驗數據加以應用在凝固溫度的 模擬上,並與實驗結果互相比較。由比較結果發現砂模的熱傳導係數和不同冷卻速率下之潛 熱釋放模式對消失模鑄件的凝固溫度溫度模擬也會有影響。 |
英文摘要 | This research is to study the solidification heat transfer phenomena for the evaporative pattern casting (EPC) of A356 aluminum alloy. Temperature measurement in an unidirectional heat transfer system along with the Inverse Method are used to measure the interfacial heat transfer coefficient between the casting and the binderfree sand. The measured interfacial heat transfer coefficient is then applied to a solidification model to predict the temperature variation in a EPC casting. A corresponding EPC casting is made and temperature measurements are taken to compare with the simulated results. For the experimental measurement of interfacial heat transfer coefficient, h, a major difficulty is how to design and fabricate an unidirectional heat transfer condition for EPC casting. In this syudy, a CO�盎and mold is used to fix the thermocouples and heat insulating material is used to surround the polystyrene pattern to fabricate the unidirectional heat transfer system. Furthermore, temperature measurements are made for two EPC castings; one rectangular and the other one stepwise. The measured temperature data are compared with the simulated ones. Possible reasons besides the interfacial heat transfer coefficient are discussed if discrepancy exists between the two results. For the measurement of interfacial heat transfer coefficient, the value calculated from the Inverse Method is again verified in the unidirectional heat transfer system. With refernce to the surface temperature of casting, the values of h can be categorized into three ranges. The value of h is approximately 0.012 cal/sec.cm��.。C for temperature above the liquidus temperatrue. It becomes 0.006 cal/sec.cm��.。C for temperature below the eutectic temperature. For the temperature in between, the value of h is apprxcimately 0.008 cal/sec.cm��.。C. For the simulation of solidification heat transfer in EPC casting, it is found in this study that other than h, the thermal conductivity of sand and the dependence of latent heat released on cooling rate also have significant effects on the results of the simulation. |
本系統中英文摘要資訊取自各篇刊載內容。