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本文将直接差分法用于铸件的凝固数值计算,在原来二维凝固计算的基础上加以扩充,编制了原则上适用于任意复杂形状铸件的三维凝固解析通用程序;为使需要输入大量数据的三维计算付诸实用,还研究编制了数据自动形成预处理程序.从L形纯铝及铝硅合金铸件的计算结果说明,这种形状的铸件不能采用二维计算,而三维计算结果接近于实验值.作者又在L形铝合金铸件的底部按置冷铁进行了实验和计算,结果指出:对具有一定凝固范围的共晶型合金,凝固过程中的固相线推进速度与微观缩松之间具有很好的对应关系.因而提出:在补缩方向的固相线推进速度可以作为此类合金微观缩松程度的判别参数,并有可能在采用工艺措施控制固相线推进速度的同时,通过数值计算来确保获得组织致密的铸件.
In this paper, the direct difference method is applied to the numerical calculation of the solidification of castings. Based on the original two-dimensional solidification calculation, the general differential expansion method is extended and a generalized three-dimensional solidification analysis program applicable to any complex shape casting is prepared. The calculation is put into practical use and a data preprocessing program is also developed.The calculation results from L-shaped pure aluminum and aluminum-silicon alloy castings show that this shape of castings can not be calculated in two dimensions and the three-dimensional calculation results are close to the experimental values The author also carried out experiments and calculations on the bottom of L - shaped aluminum alloy castings with cold iron. The results show that for eutectic alloys with a certain range of solidification, between the solidus propulsion speed and microscopic shrinkage during solidification Therefore, it is proposed that the solidus advancing velocity in the direction of shrinkage can be used as the discriminant parameter of the micro-shrinkage degree of the alloy and it is possible to control the solidus propulsion speed by adopting the process measures Numerical calculations to ensure the organization of dense castings.