旋回破碎机上机架厚大部位缩孔与缩松的模拟

Simulation of Shrinkage and Porosity in the Thick Position of the Upper Bracket of a Gyratory Crusher

针对大型铸钢件旋回破碎机上机架铸造生产过程中存在的缺陷问题,利用Pro CAST模拟软件中临界固相率对厚大部位的凝固过程进行模拟分析,从而判断出缩孔产生的热节区位置;同时基于Niyama判据预测了冒口补缩区域缩松缺陷的产生。在此基础上,修改原工艺设计方案,即将原设计的一个暗冒口改为两个对称分布的暗边冒口。模拟结果表明,改进后的工艺满足顺序凝固条件,消除了孤立的热节区域,Niyama判据满足不形成缩松的临界值要求,避免了缩孔缺陷的产生。模拟实验与实际生产吻合较好。

By observation the defects existed in the large scale casting, the critical solid fraction and Niyama criterion of the ProCAST simulation software were used to simulate and analyze the solidification process of the thick position in the upper bracket of a gyratory crusher. The locations of the hot spots related to the shrinkage cavity and the Niyama value related to porosity defect in feeding areas were estimated. Based on this, the original casting technique was improved, i.e., changing one blind riser as two blind risers which were symmetric distributed at the thick position of the casting. The results obtained by simulation indicate that the improved process meets the directional solidification manner. The isolated hot spots are eliminated and the value of Niyama criterion is larger than critical one of no porosity defect formation. Therefore it is predicted that no shrinkage cavity and porosity can be formed in the casting. The simulated results were further tested in the practical production and a good agreement between them was obtained.