基于ANSYS的粉末注射成形充模流动过程模拟

【作者】 向华；

【导师】 曲选辉；

【作者基本信息】 中南大学 ， 材料学， 2004， 硕士

【摘要】 本论文在详细分析了粉末注射成形充模机理的基础上，假定喂料熔体为混合均匀、不可压缩的非牛顿流体，充模流动为层流，依据流体力学和热力学理论，结合粉末注射成形的特点，采用欧拉法列出了完整的控制方程，并给出了相应的边界条件。在不忽略惯性效应的条件下，采用有限元方法建立了速度、压力、温度的有限元求解方程，并利用有限元分析软件ANSYS中的FLOTRAN模块进行了具体的模拟求解，实现了粉末注射成形充模过程的计算机模拟。 以硬质合金Ⅰ型拉伸试样为例，模拟了PIM喂料在简单几何模腔的流动情况，讨论了注射速度、注射温度、浇口位置等主要工艺参数对熔体充模过程的影响，预测注射成形过程中部分常见缺陷产生的条件。结果表明：当采用侧面浇口、模温300K、注射温度420K、体积流速61cm~3／s的注射参数进行注射可以得到良好的硬质合金Ⅰ型拉伸试样预成形坯。 进一步对复杂模腔充模过程进行了模拟，模拟结果与Crocher等人用商业软件Polymold算出的结果相似，证明了本文所建模型和分析计算方法的可行性。根据模拟结果中流体前沿、压力场和温度场的分布，提出了部分常见注射缺陷产生的条件，同时，讨论了利用模拟结果指导注射工艺参数选择的方法。更多还原

【Abstract】 The control equations and boundary conditions for the die filling process of powder injection molding are proposed, by assuming that feedstock melt is a non-Newtonian and incompressible continuum-flow on the basis of the theories of hydromechanics and thermodynamics. The finite element analysis software -ANSYS was used to solve the equations and to simulate the die filling process.Taken the tensile bar as an example, the die filling process of cemented carbide feedstock was simulated. The effects of flow rate, injecting temperature and the gate location on the die filling process were discussed and the conditions for the appearance of some defects in compacts were predicted based on the simulation results. The results show that good green compacts of cemented carbide could be made in the condition of volume flow rate of 61cm3/s ,die temperature of 300K and the injection temperature of 420K, and with lateral injecting gate, which was proved by the experiments.Finally, the molding process of a product with complicate shape was analyzed with the developed simulation technique. The obtained results were similar to those obtained with the commercial software Polymold by Crocher et al, which verified the feasibility of our model and math methods. Based on the simulation results of melt front, temperature and pressure fields, the conditions for some defects appearing in the compacts were determined. The process for selecting injection parameters based on the simulation results are introduced.更多还原