臺灣博碩士論文加值系統

金屬射出成形為一結合射出成形與粉末冶金優點的金屬製造方法，具有高複雜性、高性能、高精密度、量產成本低、材質應用自由度高等優點。其最耗時製程是將黏結劑從成形後的金屬或是陶瓷胚體內部移除，許多缺陷容易在此製程產生。為了縮短脫脂時間，可以利用吸附材粉末的毛細吸附作用來移除黏結劑。本文利用二維的網絡模型，結合有限差分法與蒙地卡羅法數值模擬毛細吸附脫脂機制，本研究將引用局部空孔度分佈概念，來決定最適宜空孔度分佈及特徵長度，找出最適宜理論分佈函數，根據此理論分佈函數藉由亂數產生器產生大量空孔度與滲透度數據，代入數值程式中模擬，其中以特徵長度做為控制體積的邊長。數值模擬結果顯示，吸附材移動邊界之輪廓線相當不規則且會隨機性的移動擴張，毛細吸附脫脂的時間與胚體的粉末粒徑成反比，與吸附材的粉末粒徑成正比。此外，胚體的脫脂比例與脫脂時間兩者成正比關係。

Metal injection molding(MIM) is a method in metallurgy that combins the benefits from both plastic molding and powder molding. Its advantages include high capacity, high accuracy, low cost for mass production, capability in treating complicated shapes and insensitivity of material using. The removal of binder from the shaped metal or ceramic powder compact is the most consuming step in the powder injection, its many the source of defects in the manufacturing step. In order to reduce the duration of debinding, capillary extraction of the binder by wick powder may be employed. The study utilizes a two-dimensional netwok model to investigate the mechanism of wick debinding by the numerical simulation with a technique combining finite-difference and Monte Carlo methods, a local porosity distribution is quoted in the study, applicable local porosity distribution and typical length scales. Proper theoretical porosity distribution functions are adopted to fit the applicable local porosity distribution, according to the theoretical distribution function, a random number generator is used to generate data of porosity with quantitative randomness for numerical simulations. The typical length scale is an important basis for determining the size of the control volume. The result shows that the contours of wetting wick are irregular and the walking flow edges behave randomly, wick debinding time is proportional to the wick powder diameter and inversely proportional to the compact diameter. As well as the debinding time is proportional to the fractional debinding time.

目錄
中文摘要 I
英文摘要 II
目錄 III
表目錄 VI
圖目錄 VII
符號說明 X

第一章 緒論 1
1-1簡介 1
1-2金屬射出成型的製程 1
1-3粉末原料 3
1-4黏結劑 4
1-5脫脂 5
1-6文獻回顧 8
1-6-1基本回顧 8
1-6-2毛細吸附脫脂的理論和實驗 9
1-7本文研究重點 12

第二章 理論模式 14
2-1統御方程式之建立 14
2-1-1巨觀上描述毛細吸附脫脂 15
2-1-2微觀上描述毛細吸附脫脂 16
2-2邊界條件 16
2-3孔隙率 17
2-4滲透率 18
2-5毛細壓力 18

第三章 數值方法 20
3-1網絡模型的建立 20
3-2蒙地卡羅法 20
3-3亂向步進子與位移機率強度 21
3-4數值方法 23
3-5數值計算步驟 26

第四章 結果與討論 28
4-1數值模擬的各項参數 28
4-2毛細吸附脫脂過程的流場特性分析 29
4-2-1黏結劑脫出的外形與流動波前變化 29
4-2-2黏結劑脫出的壓力場變化 31
4-3不同胚體與吸附材粒徑對毛細吸附脫脂時間的影響 32
4-3-1改變胚體的粉末粒徑對脫脂時間的影響 32
4-3-2改變吸附材的粉末粒徑對脫脂時間的影響 33
4-3-3胚體與吸附材粒徑之比值對脫脂時間的影響 33
4-4胚體形狀對脫脂時間的影響 34

第五章 結論 35

參考文獻 37
表1-1MIM與P/M的比較 42
表1-2PIM成品之性質 43
表2-1圓球形粉末不同堆積狀態下之堆積密度 44
圖1-1粉末射出成型之製程流程圖 45
圖1-2粉末射出成型原料用粉末 46
圖1-3胚體與吸附材配置示意圖 47
圖1-4毛細吸附脫脂過程示意圖 48
圖1-5 Vetter [16]的毛細吸附實驗示意圖 49
圖2-1(a)(b)本數值模擬毛細吸附脫脂之邊界界條件示意圖 50
圖2-2粉末在不同幾何配置下之堆積狀態 51
圖2-3 雷文瑞特J函數 52
圖3-1胚體與吸附材之示意圖 53
圖3-2 網絡模型 54
圖3-3有限擴散聚集示意圖 55
圖3-4 典型的有限差分格點 56
圖3-5 Finite difference grid for Laplace’s equation 57
圖3-6數值計算流程圖 58
圖4-1(a)長寬比為2.08之示意圖 59
圖4-1(b)長寬比為1.15之示意圖 59
圖4-2(a)~(e)邊長比2.08，脫脂比例百分之二十到百分之百，1230~6150個粒子移動，內外波前的輪廓 60
圖4-3(a)~(e)邊長比1.15，脫脂比例百分之二十到百分之百，1230~6150個粒子移動，內外波前的輪廓 63
圖4-4毛細指狀現象示意圖 66
圖4-5正方形胚體脫脂時內外波前圖 67
圖4-6脫脂比例百分之百時之外波前(使用均ㄧ分布模擬) 68
圖4-7脫脂比例百分之百時之外波前(使用亂數分布模擬) 69
圖4-8(a)~(e)邊長比2.08，脫脂比例百分之二十到百分之百之壓力變化 70
圖4-9(a)~(e)邊長比1.15，脫脂比例百分之二十到百分之百之壓力變化 73
圖4-10空孔周圍壓力分布圖 76
圖4-11(a)邊長比1.15，使用不同粒徑的胚體粉末與脫脂時間關係77
圖4-11(b)邊長比2.08，使用不同粒徑的胚體粉末與脫脂時間關係77
圖4-12(a)邊長比1.15，使用不同粒徑的吸附材粉末與脫脂時間的關
係 78
圖4-12(b)邊長比2.08，使用不同粒徑的吸附材粉末與脫脂時間的關
係 78
圖4-13(a)邊長比1.15，不同胚體與吸附材粒徑比值與脫脂時間的關
係 79
圖4-13(b)邊長比2.08，不同胚體與吸附材粒徑比值與脫脂時間的關
係 79
圖4-14(a)邊長比2.08之內波前 80
圖4-14(b)邊長比1.15之內波前 80
圖4-15邊長比1.15與邊長比2.08，脫脂百分比與脫脂時間的比較 81

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