臺灣博碩士論文加值系統

鋅合金壓鑄因內部孔洞導致壓鑄件的機械性能無法再提升，而限制其應用。為開拓鋅合金應用範圍並提高其機械性能，需不斷地提升及開發鋅合金壓鑄之技術。本研究利用真空輔助系統置於熱室壓鑄鋅合金之製程中，配合模具的改良，對不同鑄造壓力、模具溫度和澆注溫度等三種製程參數交互組合壓鑄條件，在一般大氣及抽真空輔助條件下，進行AG40A鋅合金衛浴把手之壓鑄實驗分析，進而尋求真空輔助壓鑄AG40A鋅合金之最佳製程參數條件。
研究結果顯示，施以各種壓鑄實驗後，發現真空輔助AG40A鋅合金壓鑄件較未真空輔助壓鑄件具有更少的孔洞率、更佳的抗壓強度和更高的抗洩漏試驗壓力值。此外，在其他條件相同下，對於可造成AG40A鋅合金壓鑄件孔洞率為最少及抗壓強度為最高的模具溫度之比較，發現施以真空輔助時的模具溫度為150℃，較未施以真空輔助時的100℃模具溫度高。而且在其他條件相同下，對於造成AG40A鋅合金壓鑄件孔洞率為最少的澆注溫度之比較，亦發現施以真空輔助的澆注溫度為420℃，較未施以真空輔助的400℃澆注溫度高。然而，無論有無施以真空輔助壓鑄，鑄造壓力對於AG40A鋅合金壓鑄件之孔洞率及抗壓強度的影響趨勢並未有改變。對於抗洩漏試驗，有施以真空輔助及未施以真空輔助的鋅合金把手壓鑄件皆發現未有洩漏情形，係因AG40A鋅合金的晶粒近似於圓晶而造成晶界未有應力集中所致。
利用OM觀察AG40A鋅合金把手壓鑄件之手柄破斷面處附近
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的區域，發現施以真空輔助可使鑄件的孔洞率減少且尺寸變小，鑄件的晶粒亦會變小，而促使其抗壓強度增加，同時也發現使用真空輔助壓鑄在150℃模具溫度時可使AG40A鋅合金壓鑄件的晶粒變得更小。而對於SEM觀察把手壓鑄件的手柄破斷面處，發現施以真空輔助的確可使AG40A鋅合金晶粒微細化，進而造成其抗壓強度增加，同時也發現施以真空輔助壓鑄在420℃澆注溫度時可使AG40A鋅合金把手鑄件的孔洞變得更少且小。

The mechanical properties of Zinc alloy die casting can not be upgraded because of the internal holes which limit its application. To explore the scope of application of zinc alloy and improve its mechanical properties, constantly upgrading and developing the technology of zinc alloy die-casting are needed. In this study, a vacuum-assisted system coupled with improved mold in the process of zinc alloy die-casting is used. Analyze the results of experiments with different combinations of casting conditions-different pressure, mold temperature and pouring temperature under the conditions of the atmosphere and vacuum-assisted die-casting. Through this experiment, the best process parameters of vacuum-assisted AG40A zinc alloy die-casting can be obtained.
The experimental results showed that the die-casting process with vacuum-assisted system has a fewer average value of porosity percentage, a better compressive strength and a higher pressure value of leakage-resistant for leakage test than the conventional zinc die casting. In addition, compare the least porosity percentage as well as the maximum compressive strength of AG40A zinc alloy die castings obtained from the process parameter combinations, the mold temperature of the vacuum-assisted system is 150℃, which is higher than the mold temperature 100℃ of the traditional system. Similarly, to acquire the same results above-mentioned, the pouring temperature of the vacuum-assisted system is 420℃, which is higher than the pouring temperature 400℃ of the traditional system. However, there is not any change about the effect trend of casting pressure on the porosity percentage and compressive strength of AG40A zinc alloy die castings whether the vacuum-assisted system is applied or not. As for the castings examined by the leakage test, due to their crystal grains are near to be round and less stress concentration occurred, all the die-castings whether the vacuum-assisted system is applied or not did not reveal any leakage defect.
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OM observation of the region near the fracture surface of handle of all castings shows that the vacuum-assisted process can reduce the porosity percentage and the pore size and the grain size as well. Therefore, the compressive strengths of castings for process with vacuum-assisted system are increased. The mold temperature which can result in the AG40A zinc alloy die casting with the smallest grains is 150℃. In addition, the results show that the process with vacuum-assisted system indeed promotes the grain of castings to be smaller and increases their compressive strengths via SEM observations. The pouring temperature of the process with vacuum-assisted system which can result in the least porosity and smaller pores is 420℃.

封面內頁
簽名頁
授權書................................................................................................ iii
中文摘要............................................................................................ iv
ABSTRACT....................................................................................... vi
誌謝.................................................................................................. viii
目錄.................................................................................................... ix
圖目錄............................................................................................... xii
表目錄............................................................................................... xv
符號說明.......................................................................................... xvi
第一章 前言....................................................................................... 1
第二章 文獻探討............................................................................... 2
2.1 壓鑄.............................................................................. 2
2.1.1 熱式壓鑄法....................................................... 2
2.1.2 冷式壓鑄法....................................................... 3
2.2 AG40A鋅合金.............................................................. 3
2.2.1 AG40A鋅合金的成分分析............................... 4
2.2.2 AG40A鋅合金的特性....................................... 4
2.3 鋅合金的壓鑄.............................................................. 5
2.3.1 完美的壓鑄方案.............................................. 6
2.3.2 鋅合金的壓鑄充模.......................................... 6
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2.3.3 鋅合金壓鑄之凝固與缺陷.............................. 8
2.3.4 壓鑄件孔洞模式.............................................. 9
2.4 真空輔助鑄造.............................................................. 9
2.4.1 真空輔助概念................................................ 10
2.4.2 真空系統 ........................................................ 11
2.5 真空輔助壓鑄參數.................................................... 12
2.5.1 模具溫度 ........................................................ 13
2.5.2 澆注溫度 ........................................................ 13
2.5.3 鑄造壓力 ........................................................ 14
2.6 真空輔助對鑄造之影響............................................ 15
第三章 實驗方法及步驟................................................................. 23
3.1 研究目的.................................................................... 23
3.2 實驗設備與材料選用................................................ 23
3.3 實驗方法.................................................................... 24
3.3.1 真空輔助系統設計........................................ 24
3.3.2 鑄造參數 設定................................................ 24
3.3.3 FLOW 3D電腦模流分析................................ 25
3.3.4 實際進行壓鑄................................................ 25
3.4 孔洞率量測................................................................ 25
3.5 抗洩漏試驗................................................................ 26
3.6 三點彎曲試驗............................................................ 27
3.7 金相顯微組織觀察.................................................... 27
第四章 結果與討論......................................................................... 38
4.1 真空輔助壓鑄參數對鋅壓鑄件孔洞率之影響...... 38
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4.1.1 鑄造壓力對鋅壓鑄件孔洞率之影響.............. 38
4.1.2 澆注溫度對鋅壓鑄件孔洞率之影響.............. 39
4.1.3 模具溫度對鋅壓鑄件孔洞率之影響.............. 40
4.1.4 真空輔助對鋅壓鑄件孔洞率之影響.............. 41
4.2 真空輔助對鋅壓鑄件抗洩漏性之影響...................... 41
4.3 真空輔助壓鑄參數對鋅壓鑄件抗壓強度之影響...... 42
4.3.1 鑄造壓力對鋅壓鑄件抗壓強度之影響.......... 42
4.3.2 澆注溫度對鋅壓鑄件抗壓強度之影響.......... 43
4.3.3 模具溫度對鋅壓鑄件抗壓強度之影響.......... 43
4.3.4 真空輔助對鋅壓鑄件抗壓強度之影響.......... 44
4.4 壓鑄件孔洞率與抗壓強度之分析.............................. 44
4.5 AG40A鋅合金壓鑄件之金相顯微組織觀察.............. 45
4.5.1 光學OM顯微組織之觀察................................ 45
4.5.2 掃描式SEM顯微組織之觀察.......................... 47
第五章 結論..................................................................................... 92
參
考文獻........................................................................................... 94

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參
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