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分析了采用泡沫模用精密铸造制壳,并用真空低压浇注成形铝、镁合金铸件的典型缺陷(主要是浇不足和冷隔、孔洞及粘砂缺陷)的行貌特征和形成机理,并提出相应的防治措施。结果表明,浇不足和冷隔缺陷主要由金属液充型速度慢、充型动力不足、浇注温度低等原因造成;孔洞缺陷主要由金属液浇注速度过快、保压压力小或保压时间短,浇注温度高,浇注系统设计不合理及型壳透气性差等原因造成。粘砂缺陷主要由型壳强度低、充型压力和真空度过大、造型型砂粒径大和激冷效果差等原因所致。
The forming characteristics and forming mechanism of the typical defects (mainly lack of pouring, cold gaps, holes and sticky sand) of aluminum and magnesium alloy castings molded by foam casting with low cost were analyzed. Prevention and treatment measures. The results show that the defects of pouring and cooling are mainly caused by the slow filling speed of the molten metal, the lack of charging power and the low pouring temperature. The defects of the holes are mainly caused by the pouring speed of the molten metal too fast, the holding pressure or the short holding time , Pouring temperature is high, pouring system design is unreasonable and bad shell permeability and other reasons. Sticky sand defects mainly by the shell strength is low, the filling pressure and the vacuum is too large, large sand shape and chilling effect of poor shape and other reasons.