设置应力释放槽预防夹砂的探讨

Discussion on Installing Stress Release Slots to Prevent Sand Inclusion

针对后桥箱体铸件夹砂问题,讨论了铸件上大平面产生夹砂的原因。在受力分析的基础上,分析了砂型表面层弯曲断裂的过程,指出了垂直压应力是造成砂型表面层早期弯曲的根源,进而提出了在砂型大平面处设置应力释放槽预防夹砂缺陷的措施,并且进行了生产验证。结果表明,应力释放槽不仅减小水平热压应力,而且减小垂直热压应力造成的弯曲挠度,而且窄而深的应力释放槽预防夹砂的效果更好。

The sand inclusion causes on the big plane of rear axle box castings were discussed in this paper. On the basis of force analysis, the bending fracture process of sand mould surface layers is studied; it is indicated that the vertical compressive stress is the cause for early bending of sand mould surface layers. The prevention measure of installing stress release slots on large planes of castings is presented, and also verified in production practices. The results show that the stress release slot reduces not only the level of oriental thermal compressive stresses but also the bend deflection produced bythe vertical thermal compressive stresses. The narrow and deep stress release slots have better effects on sand inclusion preventions.