大型球墨铸铁下箱体铸造过程数值模拟及工艺优化

Numerical Simulation and Process Optimization of Large Spheroidal Graphite Cast Iron Lower Box

对大型球墨铸铁下箱体铸造工艺进行设计和优化,并利用铸造模拟软件对铸件的充型和凝固过程进行了数值分析。铸件采用竖直分型、两箱手工造型的铸造工艺。针对箱体壁厚差较大、内部存在若干热节、内外部温度梯度大及不完全遵守"均衡凝固原则"的特点,在热节处添加冷铁并适当调整冒口位置,使铸件趋向同时凝固。模拟结果表明,在充型速度4.2 cm/s、充型温度1380℃的条件下,充型过程铁水流动平稳,水平方向每100 mm距离内液面起伏的高度差在25 mm以下,填充侧壁时液面上升速度为14 mm/s;铸造工艺改进之后,铸件的潜在缺陷率极低。浇注实验中,有效消除了铸件内部可能产生的缺陷,获得了外形完整、内部无缺陷的合格铸件。

The casting process of large ductile iron lower box was designed and optimized,and the casting simulation software was used to analyze the mold filling and solidification process of the casting.The casting was vertically divided,and two box manual molding was adopted.In view of large difference of wall thickness of the box,the existence of some hot spots in the interior,large internal and external temperature gradient and incomplete compliance with the principle of proportional solidification,the chills were added at the hot spots and the position of the riser was adjusted properly so as to solidify simultaneous solidification of the castings.The simulation results show that when the filling speed is 4.2 cm/s,the filling temperature is 1380℃,the flow of molten iron in filling process is stable.The height difference in horizontal direction is below 25 mm per 100 mm and the rise speed of liquid surface is 14 mm/s when the lateral wall is filled;meanwhile,the potential defect rate of the casting is very low after improvement of casting proces.In the pouring test,the defects that may be produced in the casting can be effectively eliminated,and the qualified castings with intact shape and no defects inside are obtained.