大型球墨铸铁蜗壳件砂型铸造模拟分析与工艺优化

Large Nodular Cast Iron Volute Parts Sand Casting Simulation Analysis and Process Optimization

针对铸件蜗形圆弧结构特征对液体金属流动充填的有利条件,同时考虑球墨铸铁铸件壁厚差过大易于导致石墨化严重不均匀的特性,把内浇道设置在铸件斜管最薄处附近的法兰孔外缘两边,达到减少铸件各处凝固结晶温差,使铸件各部分石墨化更均匀;此外针对球墨铸铁凝固过程中石墨化膨胀的特性,利用浇注系统进行自补缩,同时用砂箱加强砂型强度,提高液态铁液质量等措施,达到球墨铸铁的无冒口浇注。结果表明,经过多种方案分析及数值模拟,证明这种浇注位置便于造型及型芯固定,充填最均匀,渣易于上浮,在铸件质量、节约材料、造型成本等方面达到最佳匹配。

In view of the favorable conditions for molten iron filling due to the characteristics of the volute arc structure of the casting, and considering the characteristics that the wall thickness difference of ductile iron castings was too large to lead to serious inhomogeneity of graphitization. The inner runner was arranged on both sides of the outer edge of the flange hole attached to the thinnest part of casting inclined pipe to reduce the solidification and crystallization temperature difference in various parts of the casting, so that all parts of the casting were graphitized more uniformly. In addition, according to the characteristics of graphitization expansion in the solidification process of ductile iron, the casting system was used for self-feeding shrinkage, and the sand mold was used to strengthen the strength of sand mold and improve the quality of molten iron, so as to achieve the non-riser casting of ductile iron. The results show that through analysis and numerical simulation of various schemes, it is proved that the pouring position is convenient for modeling and core fixation, the filling is the most uniform, the slag is easy to float, and the casting quality, materials saving and modeling cost are best matched.