局部加压铝合金的凝固变化及其数值模拟

局部加压方法是压铸中用于消除铸件厚壁处缩孔缺陷的一种新工艺.该研究通过试验模型测量局部加压过程中金属型、铸件和加压杆的温度变化曲线,分析了传热与凝固现象.结果表明,局部加压使铸件的凝固时间大为缩短,加压杆前端的温度大幅上升,而金属型的温度则无明显变化.利用变网格技术,根据加压深度通过适时修改网格文件、初始条件和边界条件的方法,模拟了铝合金在局部加压过程中的凝固变化,并与试验结果进行了对比和讨论.

Solidification Analysis and Its Numerical Simulation of Aluminum Alloy under Local Pressurization

Local pressurization is a new method for eliminating porosity occurred in castings with thick-section in die casting. The heat transfer and solidification change are analyzed by measuring the temperature change curves of metal mold, casting and pressurized bar in experimental model during local pressurization. It is indicated that local pressurization can significantly shorten the solidified time of castings, meanwhile the temperature of pressurization bar front end is greatly increased while there is no difference in die temperature.The simulation of solidification process under the local pressurization method was carried out through real time modification of mesh file, initial and boundary condition based on the pinned depth. Simulated results were compared with experimental ones.