【作者】 潘大伟；

【导师】 黄勇；

【作者基本信息】 沈阳理工大学 ， 材料加工工程， 2010， 硕士

【摘要】 铝合金压力铸件具有尺寸精度高、表面质量好、材料利用率高、经济效益好等特点,被广泛应用于各个工业部门中。传统的压铸生产只能凭借多年生产经验对工艺参数进行确定,精度不高。利用数值模拟技术可以很好的指导实际生产,在生产前进行压铸的流场和温度场数值模拟,预测压铸件缺陷产生的位置及大小,从而优化并确定最佳工艺参数,使压铸缺陷减少,避免人力、物力的浪费。压铸生产正在从只凭经验走向由科学理论指导的道路。压铸件下壳体是煤气表上的主要零件,该压铸件结构复杂、壁薄等特点使其生产难度较大。该下壳体现生产成品率较低,主要缺陷为内部缩孔、缩松过多,产品打压实验不合格。因此极大地降低了产品的成品率。本课题主要研究内容是对下壳体进行数值模拟及实验研究,主要包括三维造型、网格划分、确定边界条件和初始条件,分析各组参数下壳体的充型、凝固情况,缩孔、缩松数量,从而优化压铸工艺参数,使缩孔、缩松数量最小化,提高压铸件的成品率。通过ProCAST软件模拟得出最佳的压铸工艺参数为:合金液浇注温度630℃、模具预热温度190℃、压射速度3.5m/s、压射比压70MPa、内浇口厚度2mm。使用该组参数,合金液充型平稳,缩孔、缩松数量最少,且满足压铸件对孔隙度的要求。经实验验证,该组工艺参数与实际生产所用的充型时间,凝固时间相符,压铸件打压合格率在95%以上,很好地解决了该企业生产的下壳体压铸件缩孔、缩松多的难题,验证了本次模拟的正确性。通过数值模拟确定的最佳工艺参数已应用于实际生产中。更多还原

【Abstract】 Aluminum alloy high pressure die-castings are widely used in various industrial fields for their high dimensional accuracy, good surface quality, high material utilization, good economic returns,etc. The determination of process parameters depends on the production experience of many years in traditional high pressure die-casting production, the accuracy is very low. Numerical simulation technology is a good guide to the actual production.The numerical simulation of flow field and temperature field can predict the location and size of the defects before the casting. It can optimize and determine the optimal process parameters, and reduce the high pressure die-casting defects, avoiding the human and material resources waste. High pessure die-casting production is moving to the road on which is directed by scientific theory from by experience.Casting shell is a main part of the gas meter, considerable difficulties appear in high pressure die-casting because of its complex structure, the thin wall and so on. The yield of the shell is very low now, shrinkage is the major defect, which leads to pressure test failure. It greatly reduces the productivity of the casting.The main research content in this paper is divided into the following, they include modeling for the shell, meshing, determination of the boundary conditions and initial conditions, analysis of filling, solidification and shrinkage number of each group parameters. It can optimize the high pressure die-casting process parameters, reduce the amount of shrinkage, improve casting yield.The optimal high pressure die-casting process parameters are obtained through simulation using ProCAST software, pouring temperature 630℃, mold preheating temperature 190℃, injection speed of 3.5m/s, pressure 70MPa, inside gate thickness of 2mm. Based on the above parameters, the liquid alloy filling smoothly, the number of shrinkage is least. It meet the requirements of high pressure die-casting for porosity.It is validated by the experiment that the filling time, solidification time agree with the actual production for these parameters. The casting pass rate is more than 95%, the problem of more shrinkage is well solved for the company for the shell casting. The optimum die-casting process parameters determined through numerical simulation have been applied to the actual production.更多还原