90D缸体铸件缺陷的防止措施

介绍了90D缸体的铸件结构特点,分析了90D缸体铸件小批生产时出现的水套芯折断、砂眼、渗漏和气孔等缺陷的原因,决定采用下列改进措施:采用底注式浇注系统;设置4个冒口,使用23根明排气针和17根暗排气针;砂芯局部增加加强筋并采用圆滑过渡结构;调整水套芯与盖板芯配合芯头间隙;增加覆膜砂小芯;在热节部位刷Te粉涂料;在砂芯个别部位加芯撑;在所有水套砂芯工艺芯头处钻排气孔,加强水套砂芯在浇注时排气;将水套砂芯的树脂加入量降低至1.4%;砂芯运输采用专用垫板及小车。采用上述措施后,水套芯折断、砂眼、渗漏和气孔缺陷已消除,铸件内废率控制在3%以下,加工外废率控制在10%以下,综合废品率控制在15%以下。

Measures to Prevent Casting Defects of 90D Cylinder Block

The configuration characteristics of 90D model cylinder block were introduced. The reasons causing water jacket core breaking,sand inclusion,leakage and blowholes etc. were analyzed,and it was decided to adopt following improving measures： using bottom-gated gating system;setting 4 risers and using 23 open venting pins and 17 unopened venting pins;locally setting strengthening ribs on the cores and changing every sharp transition corner to round corner;adjusting joint clearance between water jacket core and top core;adding small resin-coated sand core;brushing Te powder-containing coating at the hot spot locations;setting chaplet at some locations of the cores;drilling venting holes in all method-needed core prints of the jacket core to improve venting during pouring process ;reducing resin addition of the water jacket core to 1.4%;using special supporting pad and doily for transport of cores. The water jacket core breaking, sand inclusion,leakage and blowhole-caused rejection have been eliminated after adopting above-mentioned measures and the rejection rate before machining was controlled lower than 3% ,the rejection rate during machining process was controlled lower than 15%.