【作者】 雷黎；

【导师】 于彦东；

【作者基本信息】 哈尔滨理工大学 ， 材料加工工程， 2006， 硕士

【摘要】 镁合金凝固区域较宽,在凝固收缩过程中易产生枝晶,被枝晶封闭的局部地区液体补缩受阻将形成负压,成为卷入气体析出的有利位置。同时在压铸过程中,当金属液在高压下以高速充填型腔时,型腔内原有气体难以排出,被卷入制品内部形成小气孔而影响铸件性能。本文针对镁合金普通压铸存在的弊病,采用真空压铸镁合金工艺,同时结合CAE思想,对熔融金属的充型和凝固过程作出视觉化评估,实现镁合金壳体零件真空压铸CAD/CAE的集成。本文从液态金属充型和凝固过程的基本特点出发,以数值模拟过程中的有关理论为基础,采用有限元法进行数值模拟,并阐述了充型凝固数值模拟过程中的理论基础以及使用ProCAST软件进行数值模拟的实现方法。浇注系统设计是压铸模设计中保证制品成型质量的关键,浇注系统设计的优劣取决于分流道的布局、内浇口位置的选择和内浇口截面尺寸的确定。本文首先借助Pro/Engineer软件对铸件三维实体建模,同时设计了两种类型的浇注系统,并生成面网格文件。在确定了压铸工艺参数后,利用铸造仿真软件ProCAST分别对两种浇注系统设计进行压铸和真空压铸工艺充型、凝固过程的数值模拟,观察流场和温度场分布,预测缺陷的出现部位。结果表明存在于铸件的主要缺陷为缩孔和气孔。对于两种浇注系统设计,与普通压铸相比,真空压铸均能有效改善铸件中气孔的分布情况,减小气孔的体积分数。最后根据多组模拟结果得到优化的浇注系统设计和优化的压铸工艺参数。优化方案下铸件的整体质量有了很大提高。镁合金壳体零件的计算机仿真技术反映了铸件充型和凝固过程,对真空压铸模具的设计有很好的指导作用。在优化设计的基础上,本文完成动、定模镶块等成型零件,动、定模套板等模架,导柱、导套等结构零件,抽芯机构、推出复位机构、辅助机构及真空压铸特有的抽气截流阀装置的设计,并将模具各部分按实际生产进行装配,组合出一套完整的三维模具装配图,为方便观察内部结构,反映各组件之间的内部关系,设计了真空压铸模具的装配分解图,同时将部分组件转化为2D工程图。通过实际设计达到提高设计效率和减少配合误差的目的,此更多还原

【Abstract】 It is easy to generate dendritic during the process of solidification because of the wider solidifying areas of magnesium alloys. Liquid feeding inhibited will lead to suction pressure created in the local closed areas, where is advantageous to evolved gas lixiviation. Meantime during die casting process, molten metal fill the cavity with high speed and high pressure. Gas that exist in the cavity is hard to discharged, which would be evolved in the castings and effect the casting performance. According to the deficiency of die-casting, this article proceeds optesthesia appraisal to the filling and solidifying process and completes CAD/CAE integration for magnesium cover parts with vacuum die casting technology combining with CAE thinking.The article begins with the characteristic of filling and solidifying process, assigning finite element method as computation method for simulation. The theory basis of numerical simulation process and implementation method of ProCAST software are represented.Casting system design is important to ensure the quality of die cast. Whether it is well depends on the layout of subchannel and the position and cross-section size of gate. Here first proceeds entity and finite element model building with Pro/E software. Two casting systems are designed. Secondly after technology parameters are determined, the numerical simulation of filling and solidification process is proceeded with ProCAST software. The distribution of fluid and temperature field is observed, and the distributions of flaws are forecasted. The result shows the main defects exist in the cast is shrinkage and gas porosity. Vacuum die-casting can induce gas porosity validly compared with die casing for two designs. The optimum structure design and technology parameters are更多还原