粘土砂湿型铸铁件常见铸造缺陷的防止措施

Measures to Prevent Common Defects of Green Sand Mould Iron Castings

介绍了粘土砂湿型生产灰铸铁件的常见缺陷及相应防止措施,分析总结如下:(1)铁液最后到达部位出现的气孔可采用溢流和排气的方式来消除,防止皮下气孔的方法主要是提高浇注温度和增加排气;(2)防止浇注时铁液最后到达部位的上表面边缘部位出现黑色夹杂缺陷,可在侧面安装溢流槽,排放夹杂物;(3)防止铸件的变形,可在不出现气孔和冷隔的情况下尽量降低浇注温度,如果温度不能降低,可通过调整温度场的均匀性来控制变形;(4)防止冲砂缺陷,可以采用薄而扁且分散的内浇道,减弱铁液对砂型的冲刷力,如果有可能,可以采用底注式浇注系统。

The common defects and corresponding prevention measures of gray iron castings produced with green sand mould were introduced. Based on the reason analysis,following conclusions were obtained： （1）The blowholes occurring at location the iron meh reached lastly,could be eliminated by overflowing or by venting. Elevating pouring temperature and increasing venting were the main method to avoid subsurface blow holes.（2）The black inclusion defects occurring at h〉cation the iron meh reached lastly could be avoided by setting side overflow canal to expel the inclusions.（3 ）The casting deformation defect could be avoided by decreasing pouring temperature as possible under the condition of no blowhole or cold shut occuning. If the temperature couldn＇t be decreased,the deformation could be controlled by adjusting the uniformity of the temperature field.（4）The sand wash defect could be prevented by using thin and wide separated ingates to reduce the washing force from the iron meh to the mould, and if possible,it was suggested to use bottom gating system.