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为消除薄壁球墨铸铁件孤立热节处经常出现的表面缩凹缺陷,曾试验在表面缩凹位置增加壁厚补贴的方法,结果该缺陷的铸件比例反而增加。随后试验在缩凹部位放置冷铁,使其冷却速度加快、收缩提早,但由于该部位的补缩通道均为薄壁,凝固早于缩凹部位而使液态补缩通道提早堵塞,表面缩凹缺陷依然存在。冒口工艺是解决表面缩凹问题比较有效的方法,最后采用保温发热冒口,提高了冷冒口的液态补缩作用,彻底解决了铸件的表面缩凹缺陷。
In order to eliminate the surface shrinkage defects frequently appearing at the hot section of the thin-wall ductile iron castings, the method of increasing the wall thickness subsidies at the surface of the shrinkage recess has been experimented. As a result, the casting proportion of the defects increases instead. After that, cold chill iron was placed in the dents and recesses to make the cooling speed faster and the shrinkage earlier. However, because the shrinkage channels in this site were thin-walled, the liquid- Defects still exist. Riser technology is to solve the problem of surface shrinkage more effective method, and finally the use of thermal insulation riser to improve the role of liquid riser riser, completely solve the surface of the casting shrinkage defects.