采用MAGMA压铸模拟软件模拟了A356铝合金轮毂低压铸造中的缺陷分布及凝固场, 在此基础上对工艺进行了优化; 采用初始工艺和优化工艺低压铸造了A356铝合金轮毂, 测试了其力学性能, 观察了其内部缺陷并与模拟结果进行了对比验证。结果表明: 模拟得到初始工艺(浇注温度为730 ℃, 各部位全部采用风冷)压铸后轮毂内轮缘、轮辐和轮辋交界处和轮辋处都产生了缩松, 且凝固时间较长; 将浇注温度降至700 ℃, 在边模、顶模、轮辋及底模处提高保温层热交换系数, 边模和轮心采用水冷等措施对初始工艺优化后, 轮毂中的缩松消除, 轮毂各部位凝固完全; 优化工艺下铸造的轮毂力学性能比未优化的高, 缩松及夹杂等缺陷减少, 试验结果验证了有限元模拟对低压铸造轮毂缺陷预测的准确性。

The defect distributions and solidification fields of A356 aluminum alloy wheels by the low pressure casting process were simulated by the casting simulation software MAGMA. Based on the simulation results, the process was optimized. The A356 aluminum alloy wheels were manufactured by the preliminary and the optimum low pressure casting process respectively and the mechanical properties were tested. The defects in the wheels were also observed and compared with the simulation results. The results show that when using the preliminary process (at the pouring temperature of 730 ℃ and air cooling every parts), the shrinkage porosity was produced at the inner wheel flange, the spoke and wheel rim junction and the wheel rim, and the solidification time was relatively long. After optimizing the preliminary process by lowering the pouring temperature to 700 ℃, increasing the heat exchange coefficients at the side-core, top-core, wheel rim and bottom-core and water cooling the spoke and wheel center, the shrinkage porosity in the wheel was eliminated and the separate parts of the wheel were solidified completely. The mechanical properties of the wheel casted by the optimized process were higher than those by the preliminary process and the defects such as shrinkage porosity and slag were fewer. The accuracy of the finite element simulation for the defect prediction in the low pressure casting wheel was verified by the experimental results.