基于一维稳态传热的纯金属热型连铸模型化分析——模型描述与参数定义

Modeling Analysis of Pure Metal Continuous Casting with Heated Mould Based on One-dimensional Steady-state Heat-transfer Description of Model and Definition of Parameters

热型连铸是一种将定向凝固和连续铸造技术结合起来的近净成形(near-net-shape)新技术,在新材料开发与加工中获得了日益广泛的应用。根据热型连铸的基本原理和工艺特点,基于一维稳态传热分析,对纯金属热型连铸过程进行了模型化处理,定义了当量热导率和当量换热系数等模型化的工艺参数,获得了以固液界面为位置坐标原点的铸坯轴向温度分布解析解,可以对铸型温度、拉铸速度、温度梯度、固液界面位置、当量热导率和当量换热系数之间的关系进行求解。给出了模型的物理数学描述和解析解;以纯锌为例阐述了根据实测温度分布曲线和固液界面位置确定当量热导率和当量换热系数的方法;以纯铜为例计算了固液界面位置、铸型温度和拉铸速度之间的匹配关系,计算结果与实验数据相符。

The technique of continuous casting with heated mould is a kind of near-net-shape processing technology, which combines directional solidification with continuous casting. It has been used widely for new material development and processing. According to the technical principle and technique characteristics of continuous casting with heated mould, a one-dimensional steady-state heat-transfer model was suggested for pure metal case. Some of modeling parameters, such as equivalent specific conductance and equivalent heat-transfer coefficient, etc, had been defined. An analytic solution of temperature profile along the axis of cast rod was obtained for solid-liquid interface to be as origin of position coordinate, by which the relations among mould temperature, casting speed, temperature gradient, solid-liquid interface position, equivalent specific conductance and equivalent heat-transfer coefficient can be solved. In this paper, physical and mathematical descriptions and analytic solutions of the model were given out. A method of determining the parameters of equivalent specific conductance and equivalent heat-transfer coefficient from experimental temperature profile with definite position of solid-liquid interface was stated in the case of pure zinc. As an example, the coordinate relations of solid-liquid interface position, mould temperature and casting speed were calculated and compared with experimental results in the case of pure copper. The calculation results were conformed by experimental ones.