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研究生:郭繼仁
研究生(外文):Ji-Ren Guo
論文名稱:放電加工陽極能量效率係數之探討
論文名稱(外文):Investigation of the fraction of power in an anode of electrical discharge machining
指導教授:楊慶煜楊慶煜引用關係
指導教授(外文):Ching-Yu Yang
學位類別:碩士
校院名稱:國立高雄應用科技大學
系所名稱:模具工程系碩士班
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:2007
畢業學年度:95
語文別:中文
論文頁數:87
中文關鍵詞:放電加工熱傳導自然對流
外文關鍵詞:electrical discharge machiningheat transfernatural convection
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本研究以實驗與模擬分析結果比較,而探討放電加工陽極之能量效率係數範圍。放電加工是最常被使用於製造形狀複雜或高硬度金屬元件,且這些非接觸式的加工技巧從刀具切削製作持續發展應用在微尺度加工上。而在放電加工過程,電極與工件之間產生熱電能量轉換,當極間距離縮小,兩極表面因電磁導電產生電弧火花,而發生局部材料的熔融與蒸發產生凹陷,達到材料移除效果。
實驗製作利用熱電偶線埋設於電極圓棒上,配合溫度擷取系統紀錄溫度分佈。模擬分析採用二維軸對稱熱傳導模型,邊界條件為熱通量、自然對流係數與絕熱。結果比較採用相對誤差平均數,取實驗製作最穩定的二至六分鐘及模擬分析之溫度數據。
其研究結果為在電極圓棒長度1.5至129.5mm之能量效率係數保持在4.5%至4.7%之間浮動且穩定,而相對誤差平均數皆低於2%。在長度129.5至250mm之能量效率係數從4.4%降至3.6%,其因加工槽上方為一開放空間,造成熱量遭空氣對流帶走,而相對誤差平均數在1%至3%之間。與Patel等人[4]研究所得知之係數範圍 有差距,其因為本實驗無加工液輔助除去熔渣,造成電極底面積碳與接觸面不平均,熱量傳導並非完整。
The present research investigates the fraction of power in an anode electrical discharge machining (EDM) by the comparison of the results of experimental and simulation. Electrical discharge machining is a well-established machine for manufacturing complex geometry or hard material parts. EDM process is based on the thermoelectric energy exchange between the electrode and the workpiece. A pulse discharge occurs in a small gap between the electrode and the workpiece, and removes the material from the parent metal through melting and vaporing. The electrode and the workpiece must have electrical conductivity to generate the electric spark.
The experiment uses the temperature sensor to measure temperature distribution of the anode in EDM. The 2D axisymmetric thermal model is used to simulate the anode, and the boundary condition includes heat flux, natural convection and adiabatic. The result is calculated by the combination of the experimental and simulation. The result shows that the proposed method is feasible to estimate the fraction of power range of EDM.
摘要 I
ABSTRACT II
致 謝 III
目 錄 IV
表 目 錄 VI
圖 目 錄 VII
符 號 說 明 IX
一、緒 論 1
1.1 研究動機與背景 1
1.2文獻回顧 4
1.3 本文架構 10
二、理 論 基 礎 11
2.1 放電加工原理 11
2.2 統御方程式 15
2.3 自然對流 18
2.4 空氣之熱物理與傳導性質 22
2.5 統計分析 26
2.5.1 相關係數 26
2.5.2 相對誤差 27
2.5.3 不確定度 27
三、實 驗 架 構 與 操 作 32
3.1 架構簡介 32
3.2 實驗設備 33
3.3 溫度量測驗證 37
3.4 實驗步驟 38
3.5 結果與討論 41
四、數 值 模 擬 分 析 45
4.1 模擬條件 45
4.2 模擬參數建立 46
4.2.1 自然對流係數 46
4.2.2 能量通量 48
4.3 幾何模型設定 50
4.4 結果討論 53
五、結 果 與 比 較 59
六、結 論 與 未 來 展 望 66
6.1 結論 66
6.2 未來展望 67
附 錄 68
附錄A:有限元素法 68
個 人 簡 歷 73
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