离心场下Ti-15-3合金异形铸件成型过程研究

Investigation on Forming Process of Ti-15-3 Abnormity Castings in Centrifugal Field

建立了离心铸造法制备Ti-15-3合金异形铸件的充型及凝固过程的教学模型,通过引入两附加项(离心力及柯氏力)将离心力场模型化,采用流函数ψ(x,y)和涡函数ξ(x,y)代替描述方程中的压力项P,建立了数学模型的差分格式。在所建立的数学模型基础上,总结了离心力场下对Ti-15-3合金构件充型和凝固过程的影响规律。结果表明, 在离心力场作用下,型腔内的流动由正向流动和反向流动两部分组成,非对称的初始温度分布使得凝固过程中的温度分布始终处于一种非对称状态,从而导致最后凝固区域与型腔中心线发生偏离。

A mathematical model for centrifugal filling and solidifying processes has been established to describe the formation of Ti-15-3 alloy abnormity castings. Effect of centrifugal field is modeled by two accessional terms: centrifugal force and Chorios force. Stream function ψ(x,y) and eddy function ξ(x,y) are introduced to be a substitute for pressure term P to obtain the difference equations for programming. The filling and the solidification in centrifugal field have been summarized based on the mathematical model established for the centrifugal cast Ti-15-3 abnormity castings. Calculated results show that the centrifugal field results in that the flow in the cavity consists of forward flow and backward flow. The unsymmetrical initial temperature field causes continuous unsymmetrical variation in the following solidification, which makes the final solidified region depart from the cavity axis and then leads to the occurrence of some special defects in castings.