高固相率之固液混合體之塑流行為研究

Abstract

本研究的目的在於探討固液混合體於高固相率下產生塑性變形時之流動的特性。實驗中以凡士林與比重相近之小米顆粒所組成的混合體來模擬等溫狀態時固液混合狀態下被加工物受力作用之塑性變形現象。為了方便實驗過程的觀測，採用擠製加工的方式，搭配不同的固相率之固液混合體以及不同擠製比的模具，來進行模擬實驗。如此組成之固液混合體的固相率極為安定，且利於固相率高低之增減，對實驗之規劃及進行十分方便。 由實驗結果發現，當液態成份黏度較低時，固相率(小於60%)與模具擠製比的變化，對於加工所需施加荷重的影響不明顯。當固相率大於50%時，提高液態成份之黏度，則發現相同的擠製條件下，當固相率增加時，加工所需荷重也有明顯增加的趨勢。固態粒子的流動與液態物質之物理性質有關，液態物質近擠製錠中心部份流動較快，故分佈在此部份的固態粒子流動亦較快。

The purpose of this study is to explore the deformation behavior of the solid-liquid mixtures at high solid fractions. The mixture is made of vaseline and millet particles to simulate the deformation behavior of the semi-solid material at isothermal state. In the experiment, vaseline and solid millet particles mixtures was extruded under several different extrusion ratios. Parameters such as solid fraction, extrusion ratio has been changed throughout the experiment. This arrangement of the solid-liquid mixture has the advantage of a very steady solid fraction ratio. Solid particles’ distribution can be controlled and the flow-ability of both liquid and solid phase can easily be observed. Also, this mixture is very steady under room temperature, the experiment can be handled easily. From the experiment, we found that for lower viscosity mixtures the influence of the solid fraction (less 60%) and the extrusion ratio on the extrusion force is not obvious. Distribution of the solid particles in the mixture is apparently influenced by the flow of the liquid constituent. Since the liquid constituent generally flow much faster near the center, thus the solid particles near the center also have a much greater velocity than those located near the periphery.