本研究為鋁合金6061的熱間擠製圓管，對擠製模具之各項幾何參數進行討論後，利用有限元素模擬軟體QForm分析鋁合金圓管擠製行為，解析在連續擠製時擠錠在模具裡材料流動與塑性變形的情形，以及前後料錠之間橫向銲縫長度之分布。藉由修整模具幾何來提高銲合壓力與減少橫向銲縫長度，探討擠製負載對於模具造成的影響，避免超過機台負載。最後，利用田口式品質工程設計進行模具的最佳化設計以求產品得最佳成形解。
熱間擠製實驗採用7吋擠錠與2100美噸(18.69 MN)擠製機進行，實驗結果與模擬結果進行比較以驗證有限元素模型之適用性。本研究所選用的因子為分流孔半徑、桁架寬度、銲合室高度及軸承高度。模擬結果顯示桁架寬度對於銲合壓力並無太大影響，其餘三者越大則銲合壓力即越高；而當分流孔半徑與銲合室高度越小時則橫向銲縫長度即越短，對於桁架寬度與軸承高度而言，橫向銲縫長度之影響皆不高，本研究不僅要求較高的銲合壓力同時要縮減橫向銲縫長度，故採用一優化評估式J來判斷最高效益的組合，利用腐蝕試驗與擴張破裂試驗測試管件的橫向銲縫流動情形與其強度測試，若產品其破裂位置非位於縱向銲縫處短，則其強度優於母材Al6061，實驗結果發現管材的結合強度可達到160MPa以上。

This research is focused on hot extrusion of aluminum alloy 6061 circular tubes. Die geometries are discussed and some factors are used to analyze material flow, plastic deformation, and length of transverse seam during continuous aluminum hot extrusion using QForm simulation software. Die geometries are modified for enhancing welding pressure and decreasing transverse seam length. Effects of extrusion load on the die are also discussed to avoid overloading. Taguchi Quality Engineering is adopted to optimize die geometries and obtain best forming conditions.

Hot extrusion experiments are conducted with a billet of 7 inches in diameter by 2100 tons extrusion machine. The feasibility of finite element model is validated by comparing the simulation and experiments results. Factors chosen in the Taguchi method are porthole radius, bridge width, welding chamber height, and bearing length. Simulation results showed a higher welding pressure is obtained with a larger porthole radius, welding chamber height, and bearing length. However, a larger bridge width can increase the welding pressure slightly. A shorter transverse seam length can be obtained with a smaller porthole radius and welding chamber height. The effects of bridge width and bearing length are slight on the transverse seam length. Higher welding pressure and shorter transverse seam length are required for high productivity. A formula J is adopted to gain the best combination for the best design. Corrosion test and expansion test are conducted to verify strength and transverse seam of the product. It is found the fractured position did not occur at welding line, which means the bonding strength is stronger than the base metal Al6061. The bonding strength of extruded tubes can reach about 160MPa.

論文審定書 i
謝誌 ii
摘要 iii
Abstract iv
目錄 v
圖目錄 viii
表目錄 xv
符號說明 xvi
第一章 緒論 1
1.1 前言 1
1.2 鋁合金特性 2
1.3 擠製加工製程簡介 3
1.4 模具設計之原則 6
1.5 縱向銲縫與橫向銲縫之介紹 7
1.6 文獻回顧 8
1.6.1 擠製與摩擦模式相關之文獻 8
1.6.2 擠製數值分析與銲縫介紹相關之文獻 10
1.6.3 解析結果最佳化相關之文獻 13
1.6.4 管件強度與擠製品微結構相關之文獻 14
1.6.5 與Al 6061材料特性相關之文獻 16
1.7 研究動機與論文架構 19
第二章 鋁合金圓管擠製有限元素分析 21
2.1 擠製模具介紹 21
2.1.1 窗口模基本結構 21
2.1.2 分流孔、分流道、銲合室、軸承之設計 23
2.2 鋁合金圓管擠製有限元素分析模組建立 29
2.2.1有限元素分析軟體QForm簡介 29
2.2.2厚壁圓管幾何尺寸與擠製模型建立 30
2.2.3 QForm摩擦模式介紹[15] 32
2.2.4 模擬條件設定 34
2.3 鋁合金圓管擠製有限元素解析結果 35
2.3.1模具Z方向位移量與模具應力分析 35
2.3.2鋁合金圓管橫向銲縫流線分析 37
2.3.3鋁合金圓管銲合壓力計算 38
2.3.4原始模具幾何修整與探討 39
2.4 模擬參數分析方法介紹與探討其影響性 43
2.4.1模擬參數分析方法介紹 43
2.4.2田口法之基本原理[29][30] 44
2.4.3模具參數控制因子與水準選定 48
2.5 田口法解析結果 51
第三章 鋁合金圓管熱間擠製及實驗分析 56
3.1 鋁合金圓管熱間擠製實驗 56
3.1.1 擠製機介紹 56
3.1.2 擠製流程介紹 58
3.1.3 原始模具實際擠製負載與模擬比較 63
3.2 鋁合金圓管腐蝕實驗 64
3.2.1腐蝕實驗介紹 64
3.2.2腐蝕實驗流程 66
3.2.2橫向銲縫與縱向銲縫觀察 75
3.3 優化模具實驗結果 80
3.3.1腐蝕實驗結果 80
3.3.2擴張破裂實驗結果 84
第四章 結論與未來展望 112

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