横浇道几何特征对镁合金挤压铸造流态影响的数值模拟

在内浇道速度为0.1m/s,金属液和模具的温度分别为680℃、200℃的挤压铸造工艺条件下,用数值模拟方法获取金属液填充分别位于横浇道中间和切向浇道末端的阶梯平板的流场,来分析横浇道几何特征对充填流态的影响。结果表明,铸件位于中心时充填形态最好,不同流动距离下各向速度变化平缓;当向末端平移时,随横浇道当量半径减小,流动距离增加,X、Z方向速度变化剧烈,且充型方向上速度幅值增大,填充形态变得难以控制。

Numerical Simulation on Effects of the Geometric Shape of Runner on the Flow of Mg Alloy in Squeezing Casting

With filling velocity of 0.1 m/s in ingate and temperature of liquid Mg alloy and mould at 680 ℃ and 200℃, respectively, flow morphology of liquid Mg alloy at center of runner and end of tangential runner of step plate was simulated by numerical simulation to understand the effects of geometric shape of runner on the flow of liquid Mg alloy in squeezing casting. The results reveal that liquid Mg alloy exhibits desirable flow morphology at the center of runner, where velocity at different direction is slightly changed at varied flow distance. However, at end of tangential runner, with reducing in equivalent radius of runner and increasing in flow distance, the velocity at x and Z directions exhibits dramatically change and velocity amplitude is obviously fluctuated at filling direction, resulting in the difficulty of control to flow morphology.