金屬粉末射出成形毛細吸附脫脂之數值模擬; Numerical Simulations of Wick Debinding in Metal Injection Molding

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Title:	金屬粉末射出成形毛細吸附脫脂之數值模擬;Numerical Simulations of Wick Debinding in Metal Injection Molding
Authors:	黃柏翰;Hank Huang
Contributors:	機械工程研究所
Keywords:	金屬粉末射出成形;毛細吸附脫脂;有限差分法;蒙地卡羅法;Monte Carlo method;wick debinding;metal powder injection molding;finite difference scheme
Date:	2005-07-07
Issue Date:	2009-09-21 11:46:33 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	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.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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