消失模铸造充型阶段干砂型壁的稳定准则

The Criteria for Mold Wall Stability During Mold Filling in Lost Foam Casting Process

对干砂的抗剪强度进行了研究,认为型砂存在咬合强度。基于含有咬合强度的摩尔 库仑抗剪强度包线,研究了在消失模铸造充型阶段,保持干砂 气隙界面、干砂 金属液界面稳定的力学关系式,结果表明,干砂 气隙界面不可能发生朗肯被动破坏,只可能发生朗肯主动破坏,其后果是铸型坍塌。与此相反,干砂 金属液界面不可能发生朗肯主动破坏,只可能发生朗肯被动破坏,其后果是铸件增厚或胀箱。据此提出了避免坍塌缺陷的临界气隙高度和避免胀箱缺陷的许可铸件高度概念,并讨论了各种工艺因素对它们的影响。

The shear strength of dry sand has been studied,the result shows the interlocking strength existing interdry sands compacted.Based on the MohrCoalomb Shear Strength Curve,the mechanical condition which is essential for dry sandgas gap interface and dry sandmelt metal interface to keep stability also has been researched during mold filling in lost foam casting process.The results indicate that on the interface of the dry sandgas gap,The occurrence of Rankine passive destroying is impossible,but the occurrence of Rankine active destroying, which causes the mold collapse defect.On the contrary,Rankine passive destroying takes place of Rankine active destroying on the interface of the dry sandmelt metal,which results in the castings incrassation defect or the mold expansion defect. Thus it is proposed that the critical highness of gas gap for avoiding the collapse defect and the critical highness of castings for avoiding the mold expansion defect,and the effect of various technological parameters on which is discussed.