离心加速场中金属凝固过程温度场分布数值分析

NUMERICAL ANALYSIS OF TEMPERATURE DISTRIBUTION OF METAL SOLIDIFICATION PROCESS IN CENTRIFUGAL ACCELERATION FIELD

采用有限差分法及 Math Cad软件首次模拟了二维柱坐标系下自硬砂型离心铸造凝固过程 ,并就转速、浇温、铸型预热温度、铸型类别等工艺参数对铸件温度场分布的影响规律进行了研究。模拟结果表明 ,由于采用自硬砂型和灰铁盖 ,铸件的上下表面首先凝固 ,然后逐渐向金属液中间推进 ;随转速、铸型蓄热系数的增加 ,铸型预热温度与浇注温度的降低 ,金属凝固加快 ;在其它条件相同的情况下 ,型温对温度场的影响最大 ,转速其次 。

Different distributions of the temperature field affect the movement and distribution of particles in a centrifugal acceleration field. To accurately describe the distribution of particles, it is necessary to simulate the temperature field in the centrifugal acceleration field under current experiment conditions. The solidification process of self-hardening sand centrifugal casting is simulated in the 2-D cylindrical coordinate by adopting the finite difference method and using MathCad 7.0 for the first time. The influences of rotational speed, pouring temperatures, mould temperatures and mould types on the temperature distribution are studied. Numerical analysis shows that the solidification process of casting with self-hardening sand and iron cover is not similar to the directional solidification from outer to inner. The upper and lower surfaces of casting firstly solidify, and then the solidification front moves to the middle. This study also indicates that solidification speed of casting increases with an increase in rotational speed and thermal diffusivity of casting mould, or increases with a decrease in mould temperature and pouring temperature. The influence of mould temperature on the temperature field is the largest, the influence of rotational speed is the second, and that of pouring temperature the least.