微注射成形中表面张力效应的数值模拟  

Numerical analysis to surface tension effects of micro-injection molding

作　　者：石建军[1] 成志强[1] 柳葆生[1] 

机构地区：[1]西南交通大学,成都610031

出　　处：《应用力学学报》2010年第4期727-731,共5页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(10772154);高等学校博士学科点专项科研基金新教师基金(20070613021);中央高校基本科研业务费专项(SWJTU09CX67)

摘　　要：微注射成形过程是一个喂料射入膜腔挤出腔内空气的过程。在这一过程中,存在喂料和空气的移动界面。由于喂料和气体物质特性差异很大,喂料分子对界面上的分子引力明显大于气体分子的引力,故界面上的分子会受到方向指向喂料内部的合力,即表面张力。为了研究表面张力效应对粘性流微注射模拟结果的影响,在矢量化显式算法的有限元模拟软件中,实现了表面张力计算和模拟功能,并在有限元方法中以系统化方法确定了离散变量场的拉普拉斯算子值。应用植入该功能的软件,模拟了一个典型的注射填充过程的算例,探讨了表面张力作用项对粘性流体填充过程的影响。通过对不同尺寸构件的模拟结果比较,证实表面张力作用项对粘性流注射填充过程模拟结果影响不大,除了毫米级以下构件,在一般情况下可以忽略。In the process of micro-injection molding,the feedstock is injected into the mold cavity and the air inside is squeezed out.In such a process,there exists a moving interface between the feedstock and the air.Because of the important difference between the physical properties of feedstock and air,the molecules on interface are attracted by the molecules of feedstock significantly more than that of the air.Then the molecules on interface subject to the resultant force directed towards inside of the feedstock,namely the surface tension.In order to study the effect of surface tension on the simulation results of mico-injection of viscous flow,the evaluation of surface tension in simulation is realized.The development is carried out on the basis of finite element simulation software,in which the vectorial explicit algorithm is developed previously.Realization of the function for surface tension is based on a numerical method,in which a systematic procedure is used to determine the Laplacian values of a discretized field.By application of the software with this function,a typical example of the injection filling process is simulated.The influence of surface tension effect on filling process of the viscous flow is investigated.By comparison among the results of simulation on different sizes of the configuration,it is proved that the surface tension term does not represent important effect on injection filling of the viscous flow.Except for scale of the problems below millimeter,it can be neglected generally.

关 键 词：微注射成形 矢量化显式算法 表面张力 数值方法 

分 类 号：TH16[机械工程—机械制造及自动化] O35[理学—流体力学]