选择性激光烧结金属粉末瞬态温度场模拟

The Transient Simulation for Temperature Field of Selective Laser Sintering of the Metal Powder

局部输入的集中移动热源造成了选择性激光烧结过程中温度场分布不均衡且不稳定,因此研究其温度场对掌握烧结过程中温度动态分布规律具有重要意义。在考虑了热传导、热辐射和热对流,材料的非线性热物性参数和相变潜热的作用下,建立了水雾化Fe多道烧结的三维有限元模型,采用ANSYS参数化设计语言(APDL)实现移动的高斯热源的加载。模拟结果表明:激光烧结过程中,在光斑中心前端存在着较大的温度梯度;光斑中心的温度高于金属粉末的熔点,烧结过程存在液相;粉床内部温度场在深度方向呈漏斗状阶梯分布,随烧结深度的增加,粉床内部的温度和温度梯度迅速衰减;同一烧结道各点的最高温度相对稳定,但随着烧结道的增加,各点最高温度都有小幅度增加的趋势,这是温度累加的结果。

The distribution of temperature field in selective laser sintering process caused by the moving heat source is nonuniform and unstable, so it is helpful for researching on sintering process to investigate the regularity of temperature field distribution. Employing water atomized iron powders as material, the 3D transient finite element simulation model was built by using ANSYS, in which the effects of the heat loss through heat conduction, heat radiation and convection, the non-linear behavior of the thermophysical property parameters and latent heat due to phrase transformation from powder to liquid were considered. The dynamically loading of the moving Gaussian laser thermal resource was carried out using the APDL （ ANSYS Parametric Design Language）. The simulation results show that the temperature gradient in the front of laser spot is biggish in the laser sintering process. The temperature of spot center is higher than the metal powder＇s melting point, so liquid phase exists in the sintering process. The temperature field inside the powder bed appears as a funnel-shaped in depth direction, with the increasing of depth, the temperature and the temperature gradient inside the powder bed are decreased rapidly. The maximum temperature of each point of the same sintering route is relatively stable, while along with the additional process of sintering route, the highest temperature of each point has a little increase due to temperature accumulation.