消除覆砂铁型铸造曲轴气缩孔的措施

Measures to Eliminate Shrinkage+Blowhole of Nodular Iron Crankshaft Cast with Resin Sand-Coated Iron Mold

覆砂铁型铸造二缸球铁曲轴按原工艺生产曾因气缩孔缺陷引起报废,通过采取相应措施,该问题已得到解决:(1)加大铸型内两支曲轴的间距和增大铁型外形尺寸,增强铁型的冷却作用;(2)改进曲轴连杆轴颈内孔形状及其砂芯设计,减薄砂芯砂层厚度,减少砂芯发气量,并改善内孔部位的冷却条件;(3)适当调整化学成分和降低浇注温度,减少液态收缩。

The nodular iron twn-cylinder crankshafts produeed with former resin sand-coated irnn mold designed according former casting method had been rejected due to the shrinkage＋blowhole defect. By adopting following measures,the problem has been solved：（ 1 ）enlarging the distance between two crankshaffts cast in one mohl In increase the cooling effect of the iron mold;（ 2 ）improving lhe design of internal hole of the connecting necks and relevant sand cores to reduee sand layer thickness of the cores and thereby In reduce the gas evolution of the cores and improve the cooling condition of the areas near to the internal cnres;（ 3 ）properly adjusling chemical composition and decreasing pouring temperature to reduce liquid eontraction.