铝合金曲轴箱压铸件缩孔分析及对策

Analysis and Countermeasures for the Shrinkage Holes(Porosities)in Aluminum Alloy Die Castings

针对某铝合金曲轴箱壁厚较大部位的缩孔问题进行了分析。从铝合金压铸件缩孔形成机理和实际的缩孔状态出发,采取一系列措施来消除缩孔缺陷。首先,铸造压力从65MPa提高至90MPa以及料饼厚度由25mm增加到30mm,但效果很差;然后,改善模具冷却状况,延长脱模剂喷涂时间,效果一般。最后,结合铝液凝固补缩原理,在铸件缩孔区域增加两根挤压销,并合理调节其挤压参数,将铸件缩孔率由最初的5%降低到0.2%,取得了良好的效果。

The shrinkage holes(porosities)in an aluminum alloy cylinder block with a large wall thickness were investigated.A series of countermeasures were considered from the formation mechanism of shrinkage holes in the aluminum alloy die-casting parts and the actual shrinkage conditions.First,through increasing the casting pressure from 65 MPa to 90 MPa and increasing thickness of the cake from 25 mm to 30 mm,the effect presents unsatisfactory.Then,the cooling condition of the mold cooling system was modified,and the spraying time of the release agent was increased,however,the effect could be neglected.Finally,combining with the principle of liquid aluminum solidification feeding,two pins in the region of the shrinkage holes were added with rationally adjusting the squeezing parameters,the shrinkage rate was reduced from 5%to 0.2%,achieving the desirable effect.