熔模铸造气门摇臂气孔缺陷及改进措施

Airhole Defects of Valve Rocker Arm in Investment Casting and Improvement Measures

对NN4102发动机气门摇臂在生产过程中出现气孔缺陷进行分析,从型壳的制作工艺、铸件的浇注工艺出发,找出了气孔缺陷的产生原因,并提出了相应的解决措施:一是增加型壳透气性,延长焙烧时间,提高焙烧温度;二是降低原料发气量;三是提高出炉温度及浇注温度;四是适当提高浇注速度,缩短浇注时间。结果显示,改进生产工艺后,气孔导致的缺陷率由原先的9﹪以上下降到2﹪左右。

Airhole defects of NN6102 engine valve rocker ann in the process of production were analyzed, the causes of the blowhole defects were fount out from shell process and pouring process, and the corresponding solution measures were proposed： increasing shell permeability, prolonging roasting time, improving roasting temperature; reducing raw material gas evolution; improving melt temperature and mould temperature; increasing pouring speed, shortening casting time. Results show that, using the improved production technology, the rejection rate caused by porosity defects is decreased from former 9% to 2%.