直接金属粉末激光烧结成形过程温度场模拟

Simulation of Temperature Field in Direct Metal Laser Sintering Processes

在综合考虑热传导、热辐射及对流等热现象的基础上,初步建立了用于模拟激光烧结过程中传热行为的数学模型。根据Gusarov模型求得粉床的有效导热系数,表明导热系数与铺粉过程中粉末的堆垛方式以及烧结过程中的粘结率有关。在绝热边界条件和部分热物性参数恒定的合理简化下,利用解析法求解了热传导方程。利用FORTRAN语言编写了求解结果的运算程序,并对基模高斯激光近似作用下水雾化铁粉的烧结成形温度场进行了数值模拟,模拟结果较好地验证了实验结果。

Taking into account the thermal phenomena involved in the process, such as conduction, radiation and convection, a mathematical model has been developed for simulation of the heat transferring behavior in a DMLS process. A formula for calculation of the effective thermal conductivity of a packed powder bed has been given. It shows that the thermal conductivity depends on the packing structure of powder bed, and the contact size of contiguous particles during sintering process. Based on the assumption of the thermal insulating boundary conditions and the fixed thermal physical parameters, the equation of heat conduction has been resolved with analytical calculation. Assuming that it is approximately a Gaussian laser beam, the FORTRAN language was employed to compile the program to simulate the temperature field in direct iron powder sintering process. The obtained simulation results show a good agreement with the existing experimental results.