尺寸变化对L形镁合金铸件凝固过程中温度场的影响

Influence of Casting′s Size on Temperature Field of L-shape Mg-Alloy Casting in Solidification Process

采用直接差分法求解热传导方程,对L形镁合金铸造过程进行模拟,研究了铸型尺寸对温度场的影响。结果表明:在镁合金铸造过程中,热量通过铸件/空气和铸件/铸型界面向外部环境、铸型传递,铸件直边区域形成热扩散层"阶梯"温度降低,铸型内部形成温度扩散层其温度升高。在底座高度小于直边宽度时,铸件直边和底座区域温度均下降迅速,铸件从直边和底座区域向拐角区域凝固;随着底座高度和直边宽度的增加,铸件底座和直边区域的面积增加,降低相同温度所释放的热量增加,铸件拐角中心和铸型中心单元的温度均升高,铸件从直边区域向底座区域凝固,凝固时间增加。

The direct differential method was used to solve the equations of heat conduction, and the casting process of L-shape magnesium alloy parts was simulated. The effect of the casting’s size on temperature distribution was studied. The results show that, during the casting process of magnesium alloy, the heat transfers from the interface of casting/mold and casting/air to environment and mold, the thermal diffusion step in riser region of casting forms and the temperature decreases. When base’s height is less than straight’s width, the temperature of the base’s and straight region decrease rapidly,the solidification of the casting is from the riser and base’s to the corner region. With the increase of the base height and straight width, the area of base and straight region in casting increases, the heat released by decreasinbg the same temperature increases, the temperature in the center of corner and mould increases, the solidification of the casting is from the straight to the base region, the solidification time increases.