Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/2460
標題: 具內部熱源的板狀模具之熱傳 計算與表面溫度分佈探討
A Study on the Heat Transfer Characteristic and Surface Temperature Distribution of a Plate Type Mold with Internal Heat Source
作者: 黃炯瑞
Huang, Chiung Jui
關鍵字: Plate Type Mold;板狀模具;Natural Convection;Cylindrical heat source;CFD;自然對流;圓柱熱源;CFD
出版社: 機械工程學系所
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摘要: 
本研究主要以各種設計參數(模板幾何位置、塊狀材質、電熱管數量、長度與功率、搭配不同功率、絕熱材料)分析對模板表面溫度以及熱對流係數的影響,以達到模板模型溫度均勻化目標,並進行具圓柱熱源的板狀模具於靜止空氣中的自然對流現象探討。
首先以零維模式計算熱對流係數,利用最小平方法求得自然對流的平均熱對流係數、強制對流的區域的熱對流係數,並與經驗公式比較,再以熱對流係數計算模板的加熱時間,驗證昇溫模式的正確性。模板溫度由控制系統維持穩定溫度,無法確認電熱管功率長度分佈,為了獲得確實電熱管長度功率分佈,故選擇塊狀模型(一維)比對溫度曲線驗證。一維模式將電熱管分成三段,以其發熱功率及長度作為設計參數,合併內能、傳導、對流、溫度分析,建立一維溫度分析程式,計算出在不同金屬物體表面溫度分佈,以做為模板最佳化設計的依據。
利用計算流體力學軟體Fluent模擬圓柱熱源的板狀模具在於靜止空氣中的自然對流現象探討,並與實驗溫度值比對,結果顯示Fluent與實驗有相同的趨勢。最後,使用田口方法合計7個控制因子,分析各種控制因子對模板溫度均勻化的貢獻度,結果顯示電熱管二邊提高功率、幾何偏心對溫度均勻化貢獻最多,依據田口最佳組合結果溫差3℃, 分析後效果有顯助降低69%溫度標準差。

This study applied several different design parameters(the mold’s position and materials, number of electrical pipes、length and power, the arrangement of power, the insulation materials) to analysis the surface temperature of template and the effect of the heat convection coefficients in order to get the uniform temperature distribution of the template, furthermore, we also studied the phenomenon of nature convection about the template with a cylindrical heat source in a quiescence air.
This study firstly calculate the heat convection coefficient by using zero-dimensional model, and applying the least squares regression method to find out the average heat convection coefficient of both nature and forced part. Then compare these results with experienced equations. By applying the calculated value of heat convection coefficient, this study will compute the time during its heating process to verify the validity of this mathematic model. The mold’s temperature was maintained constant by the control system, because it could not find out the power distribution of the electrical pipes, for the purpose to confirm this power distribution, this study analysis the block shape mold(one dimensional) to verify the temperature distribution curve. Subsequently, it will divide the electrical heating pipe into 3 sections in one dimensional mode, and take the heating power, pipe length as the design parameters and combine the factors of internal energy, conduction, convection, temperature, etc. to establish an one dimensional analysis equation which can be used to calculate the temperature distribution on the different metals. These results could be taken as a basis for the optimal design of the template.
By using the fluid dynamic software “Fluent”, it can be used to simulate the natural heat convection on the template with a cylindrical heat source in a static air, and comparing this result with experimental data, it shows both have the same tendency. Finally, this study will use Taguchi Method with 7 controllable factors to analysis the contribution rate of each controllable factors for uniform temperature distribution on the template. The results show while increasing both of the heating power on the two ends of an electrical heating pipe and the offset can get the better contribution rate. According the simulated results from Taguchi Method, the best combination can decrease the standard deviation value from 2.09 to 0.63 Celsius degree which was obtained by the original experiment, it will have 69% advantage on dropping the standard deviation obviously.
URI: http://hdl.handle.net/11455/2460
其他識別: U0005-1608201015085300
Appears in Collections:機械工程學系所

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