无冒口铸造是一种节能铸造新工艺,可以大大提高铸件工艺成品率,节约大量工时,减轻劳动强度,大幅度提高经济效益。去年我厂为外单位生产一批牌号为QT40-17的球铁件,其主要尺寸、形状、加工部位及重量如图1、图2、图3所示。开始试制时,我们在考虑浇注系统时沿用了冒口补缩的传统球铁铸造工艺,采用顺序疑固原则,从底部或热节处引入铁水,大冒口补缩。结果不但热节部位产生严重缩松、缩孔,而且冒口根部出现集中缩孔,使零件大批报废。后来,我们大 No riser casting is a new energy-saving casting process, which can greatly improve the casting process yield, save a lot of working hours, reduce labor intensity and greatly improve economic efficiency. Last year, our factory produced a number of ductile iron pieces with the grades of QT40-17 for external units. The main dimensions, shapes, processing positions and weights are shown in Fig. 1, Fig. 2 and Fig. 3. At the beginning of trial production, we adopted the traditional ductile iron casting process, which adopted the system of pouring, and adopted the principle of orderly suspicious solidification. The molten iron was introduced from the bottom or hot section, and the big riser was rebuilt. As a result, not only severe shrinkage and shrinkage occurred at the hot section, but also centralized shrinkage at the root of the riser resulted in a large number of parts being scrapped. Later, we are big