负压实型铸造砂型强度及型壁移动的影响因素

研究了影响负压实型铸造中砂型强度及型壁移动的工艺因素及其影响规律．结果表明：提高真空度或增加吃砂量都可以提高砂型内部压力而使其强度提高，并减少型壁移动；砂型侧面压力远远低于正面压力，通过振动可以提高砂型的侧面压力而有利于砂型在水平方向上的充填；实验得出的真空度、吃砂量与砂型内部压力、型壁位移及由液体产生的外部压力之间的定量关系，为制定铸造工艺参数以消除铸件冲砂缺陷、提高铸件尺寸精度提供了依据．

The Strength of Sand Mold for Vacuum Evaporation Pattern Casting (VEPC) and the Moving of Cavity Wall

The influence of processing parameters in VEPC on the strength of sand mold and the moving of cavity wall have been studied. The results indicate that the inner pressure of sand mold can be raised by increasing the vacuum or the burying depth of foam pattern. The higher the mold strength, the less the moving of cavity wall. The pressure in the side direction of the cavity is much less than that in the vertical direction, and the side pressure can be raised by mold vibration. The quantitative relations gained through the experiments among the vacuum, burying depth of pattern and inner pressure of sand mold, moving of cavity wall, and impulsive force of metal liquid can be used to determine the processing parameters in VEPC, so that the defects of castings can be eliminated and the precision of castings can be improved.