粉末微注射成形脱模过程的有限元模拟

Finite element analysis on the demolding process of micro-powder injection molding

本文选取圆柱状微结构的截面作为研究对象,分析了粉末微注射成形脱模过程中脱模阻力的构成。在保压压力为10 MPa,脱模温度分别为60℃、80℃、100℃和140℃条件下,利用有限元方法模拟了微结构在脱模过程中处于不同位置时的应力分布状态及变化趋势。结果表明:在脱模刚开始时,微结构受到的应力最大,最容易造成微结构破坏。在脱模温度低于临界平衡温度(T_(cr))时,脱模温度越低,微结构受到的应力越大,微结构距离生坯几何中心越远,其承受的应力越大,越容易造成微结构的破坏;在脱模温度高于T_(cr)时,在整个脱模过程中,生坯中的各个微结构处于相同的应力状态。

Microstructures with circular cross section were selected to study the demolding process of micro injection molding.The demolding force mainly consists of contact stresses and adhesive force.When the holding pressure is 10 MPa and the demolding temperatures are 60 ℃ 、80 ℃、100 ℃ and 140 ℃,respectively,the stress distributions of the microstructures at different locations were simulated using the finite element method.A critical temperature（T_（cr））exists,at which the stress of the microstructure is zero.The results reveal that the stress of the microstructures is highest at the beginning of demolding,which easily cause damage of the microstructure.When the demolding temperature is below T_（cr）,the lower the demolding temperature is,the higher stress the microstructure has,and the microstructure which is far away from the geometric center of the molded part is easily damaged.When the demolding temperature is above T_（cr）,all microstructures of the molded part are in the same stress state through the demolding process.