防止输油泵用球铁件产生针孔缺陷的工艺措施

Process Measures for Avoiding Pinhole Defect Formation in Ductile Iron Castings of Petroleum Transfer Pump

根据球铁件针孔(皮下气孔)缺陷的形成机理,对针孔缺陷严重的球铁输油泵泵壳、叶轮的生产工艺进行了改进,包括:(1)将型砂水分由7%降低到5%;(2)型砂中加入7.5%的煤粉;(3)型芯涂料中加入6%的Fe2O3粉;(4)浇注温度提高到1380℃以上。成功地消除了针孔缺陷。

Base d on the formation mechanism of pinhole defect in ductile castings, the production process of the bump housing and impeller of the oil transfer pump, which had been rejected totally due to severe pinhole defect, was improved including： （a） reducing moisture content of the molding sand from 7% to 5%;（b） adding 7.5% coal dust into the molding sand; （c） adding 6% powder Fe203 into the core coating; （d） increasing pouring temperature to higher than 1 380 ℃. As a result, the pinhole defect was eliminated successfully.