Ball Rail Numerical Simulation Of Solidification Technology,

Ductile casting is an kind of important material, and have merit of high intension, good toughness, low cost and being prone to organize to produce. Now it has been used widely in motorcars, agricultural machine, shipping manufacture, metallurgy industry, piping engineering etc. But ductile casting have the character of thick solidification, and produce expanding in the process of solidification, this make the casting bring out shrinkage and porosity, low produce rate. This is an outstanding question in the ductile iron producing progress and not is solved to this day.Numerical simulation technology of the casting solidification process is a kind of method that making use of computer technology to simulate the process of the casting solidification and show visually the foundry process. The adoption and integration of this new technology can optimize the product structure, improve the product quality, shorten the period of exploiting product, reduce the cost and improve the ability of dealing with the market emergency, it hold the balance in impelling the technique advancement of foundry.In this paper, numerical simulation technology of 3-D thermal field in the ductile eastings during solidification processes is discussed theoretically and the relative program developed. During the solidification of ductile iron, the volume change can be separated into several stages: after molten iron poured, shrinkages occur along with the temperature descent; below the liquid line, original phase begin to separate out that is graphite or austenite, it result in shrinkage or expansion besides the shrinkage brought on by the temperature descent; in the period of eutectic solidification, austenite begin to separate out graphite. Because the difference of the volume change relatively, the expansion exceed the shrinkage, so it show that the casting produce expansion; in the last, the graphite separated out become little and little, the expansion is little and little, the remnant solidifies like steel and the shrinkage is in the ascendant, the casting generate shrinkage that is named the 2nd shrinkage. The main effect in the ductile iron solidification period is casting mould, modulus and structure, molten iron composite, gestation, pouringtemperature.The model of the ductile iron solidification is set up according to the solidification character and influence factor, the volume change is computed in the progress ot solidification and the result is satisfactory.In this paper the tasks are completed on the below several aspect: Improving the technique on Dynamic multi-pool search, this advance the compute speed. According to the crystal principle of the ductile iron, the enthalpy is used in processing the latent heat, the result is close to the fact, it greatly improve the simulation veracity. According to the solidification character of the ductile iron, the 3-D thermal fields is computed, and synthetically consider the effect of the original graphite, the liquid shrinkage, the graphite expansion, the casting mould extension etc. on the base of the 3-D thermal fields computation, the position and size of the shrinkage and porosity are predicted, the predicted result is close to Procast. Besides above, the paper discuss the coupling of the thermal field and the fluent field, and the results of the fluent field computation are considered as the initial temperature of the thermal field, the computation result is close to the fact.