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研究生:李正隆
研究生(外文):Cheng-Lung Li
論文名稱:重力鑄造中鋁合金熔液經過陶瓷泡沫濾網後品質的改變
論文名稱(外文):The Quality Change Of Molten Aluminum Alloy After Flowing Through The Ceramic Foam Filter In Gravity Casting
指導教授:許富淵
指導教授(外文):Fu-Yuan Hsu
口試委員:林惠娟劉柏良
口試委員(外文):Huey-Jiuan LinPo-Liang Liu
口試日期:2013-07-26
學位類別:碩士
校院名稱:國立聯合大學
系所名稱:材料科學工程學系碩士班
學門:工程學門
學類:材料工程學類
論文種類:學術論文
論文出版年:2013
畢業學年度:101
語文別:中文
論文頁數:61
中文關鍵詞:陶瓷泡沫濾網流道方案設計重力鑄造臨界鋁合金澆鑄速度雙膜缺陷面積分率雙膜指數圖
外文關鍵詞:ceramic foam filterrunner system designgravity castinggravity castingbi-film defect“area normalized” bifilm index map
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陶瓷泡沫濾網時常應用於鋁合金重力鑄造的方案設計,其使用目的,除了減低金屬流體速度小於鋁合金之入水口的臨界速度0.5 m/s外,最重要經過濾網後,金屬流體因動能回覆成靜壓力能,使得流體能達到整流效果;同時,可以避免在進入模穴時產生紊流而造成捲氣和氧化膜捲入形成所謂雙膜缺陷(bifilm defect)。
為了要瞭解鋁合金液體經由不同方式進入陶瓷泡沫濾網後,其流體外型改變的情形,以及對於鋁液品質的影響。本研究運用底澆方式,設計了三種不同方案設計之流道系統,控制三種澆鑄高度,並選用10ppi、20ppi陶瓷濾網及一組未設置濾網進行比較實驗。
觀察鋁合金液體通過濾網後的流體外型及流速的變化,是使用透明壓克力模具來做水流實驗模擬試驗,目的要類比模擬鋁合金液體通過濾網的情況,以便觀察三種流道設計與不同濾網條件下流體外觀的改變;並且以此流體外型的動畫資料,進行計算流體力學電腦模擬的驗證。
鑄造實驗後,探討金屬液體通過濾網後其鋁液品質變化,是針對濾網出口處附近的鑄件,進行切除取樣,並將這些出口處的試片,經過重熔(re-melting)及減壓測試RPT(reduced pressure test),使用阿基米德法量測這些減壓測試後的試片的密度及孔隙率並進行切面觀察,並透過本研究所新提出的”面積分率”雙膜指數圖(“Area normalized” Bifilm index map)進行量化探討。
Ceramic foam filter is normally applied in the design of runner system in aluminum gravity casting. The purpose of using this filter is to reduce the velocity of liquid aluminum under the so-called critical gating velocity (e.g., 0.5 m/s for aluminum alloys). After liquid aluminum flows through the foam filter, its static pressure energy is recovered from kinetic energy. The foam filter then can be used for stabilizing the aluminum flow during the filling of mold cavity. The so-called bi-film defect, deriving from the surface turbulence and the entrapment of oxide films during filling process, can thus be avoided.
The purpose of this study was to understand the change of profile and melt quality of liquid aluminum after flowing through the foam filter in various runner system designs. Three types of bottom gating runner systems were designed.
For observing the flow going through the ceramic foam filter, water analogy method, dyed water filling test in a transparent PMMA material mold, was applied. This flowing profile had been used for the validating the result of computational modeling.
In the casting experiment, the aluminum casting sample in the outlet region of the foam filter was sectioned. These specimens then did re-re-melt reduced pressure test (re-melt RPT). The bulk density of the specimens was measured by Archimedes method. By comparing the density differences between the original degassed liquid aluminum and the casting specimens, the contamination of hydrogen of the liquid aluminum after flowing through the filter was measured. "Area normalized" Bifilm index map was proposed to quantify the content of bifilm defects within the casting samples.
摘要 ...................................................................................................................... I
Abstract ............................................................................................................... II
圖目錄 ............................................................................................................... VI
表目錄 ............................................................................................................... IX
第一章 序論 .................................................................................................. 1
1.1 前言 .................................................................................................. 1
第二章 文獻回顧 .......................................................................................... 3
2.1 雙膜缺陷(Bifilm defect) .................................................................. 3
2.2 雙膜指數(Bifilm index) ................................................................... 8
2.3 臨界澆鑄速度與方案設計 ............................................................ 11
2.4 陶瓷泡沫濾網 ................................................................................ 13
2.5 電腦模擬 ........................................................................................ 15
第三章 實驗方法 ........................................................................................ 17
3.1 流道方案系統 ................................................................................ 17
3.2 水流實驗模擬類比試驗 ................................................................ 18
3.3 砂模鑄造實驗 ................................................................................ 19
3.3.1 砂模製作 ............................................................................. 19
3.3.2 旋轉除氫 ............................................................................. 20
3.3.3 減壓含氣量測試(Reduced pressure test) ........................... 20
3.3.4 阿基米德密度量測(Archimedes method) .......................... 21
3.3.5 面積分率雙膜指數圖 (“Area normalized” Bifilm index map) ............................................................................................... 22
3.4 電腦模擬 ........................................................................................ 25
第四章 實驗結果 ........................................................................................ 28
V
4.1 水流實驗模擬類比試驗 ................................................................ 28
4.2 水流實驗模擬試驗與電腦模擬驗證 ............................................ 32
4.3 鑄造實驗 ........................................................................................ 40
4.3.1 重熔減壓測試孔洞體積百分比分析 ................................. 40
4.3.2 重熔減壓含氫量測試切面分析 ......................................... 42
第五章 結果討論 ........................................................................................ 45
5.1 電腦模擬 ........................................................................................ 45
5.2 面積分率雙膜指數圖(“Area normalized” Bifilm index map) ...... 50
第六章 結論 ................................................................................................ 56
參考文獻 ........................................................................................................... 58
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