型腔背压条件下的压铸数值模拟及缺陷分析

Numerical Simulation and Defects Analysis during High Pressure Die Casting Process under Back Pressure Conditions

压铸过程中金属液充型行为受型腔残余气体背压影响,为准确模拟金属液充型过程,需考虑背压条件。通过引入背压控制方程,计算了某汽车用铝合金滤清器压铸充型过程,并以计算结果为依据提出了改进方案。引入背压条件预测气孔缺陷位置与实际情况一致。通过调整排气口位置能够改变局部型腔背压,进而改变金属液充型行为,从而消除了铸件缺陷。

Due to the flow behavior of metal melt affected by the back pressure from residual gas in the mould during high pressure die casting (HPDC) process,the back pressure conditions should be considered in order to simulate the filling process precisely. Filling process of an aluminum alloy filter for automobile in HPDC was simulated by introducing back pressure conditions,and the simulated results were well in agreement with actual ones. The modified design was conducted based on the simulated results. The defects in the castings can be effectively eliminated by adjusting the position of the vents to change the back pressure in local cavity and then to affect the filling distribution of liquid aluminum alloy.