压铸ADC12转向器数值模拟及微观孔洞的研究

Numerical Simulation and Microporosity of Die Casting ADC12 Steering Gear

针对实际铝合金转向器压铸件,运用JSCAST软件对其充型及凝固过程进行模拟,采用三维X射线断层扫描技术得到了铸件中微观孔洞的形貌特征、尺寸大小及分布规律,并与模拟结果进行了对比验证与分析。结果表明,转向器铸件中主要为小体积的孔洞,其等体积球直径为0.261~0.288mm;气缩孔和缩孔尺寸较大,主要分布在铸件壁厚较大的两个安装孔和形状复杂的齿条与齿轮轴连接处。铸件中间部位由于金属液汇流,产生大量的气孔。

For the practical die casting aluminum alloy steering gear,JSCAST software was adopted to simulate the filling and solidification process,and through computed tomography（CT）scanning experiment,the characteristics,size and distribution of microporosity in the castings were analyzed and compared with the simulation ones.The results show that the holes in the steering gear mainly are small size,and the diameter defined as a sphere of an equal volume is between 0.261 and 0.288 mm.Gasshrinkage pore and shrinkage pore have a larger size,mainly distributed in the bigger thickness casting of two mounting holes and the connection of rack and pinion shaft with complex shape.The intermediate positions of steer gear generate a large number of gas-pores as a result of the convergence of liquid metal.