电子束熔融直接金属成型工艺的研究

研究了工艺参数对电子束熔融工艺过程的影响,采用线性回归分析建立了一个数学模型.研究结果表明,扫描线宽与电子束电流、加速电压和扫描速度呈明显的线性关系,当搭接率为0.5时,所获得的层面质量优于搭接率小于0.5时的层面质量,回旋扫描路径可以减少热量的积累,有效地防止金属小液滴的飞溅,从而得到较好的层面质量.针对实验中出现的电子与粉末碰撞造成的未熔粉末的飞溅,采用优化的工艺参数对粉层进行预热,从而大大减少了未熔粉末的飞溅.对于扫描线的球化,采用功率与扫描速度的比值大于0.1的工艺参数进行扫描,获得了连续的扫描线.通过对工艺参数的优化,得到了性能优异的一维扫描线和二维层面,为三维实体的成型奠定了基础.

Process Investigation of Direct Metal Fabrication Based on Electron Beam Melting

The influence of the process parameters on electron beam melting process is investigated and a mathematic model is set up by linear regression analysis. The results show linear relationships of the width of scanning line with the beam current, accelerating voltage, and scanning speed. The quality of layer produced at R0 egual to 0. 5 is better than that produced at R0 less than 0. 5. The heat accumulation can be reduced by spiral scanning so that droplet splash is eliminated and high quality layer is obtained. Aiming at the unmelted powders splash from collision between electron and powders, optimized process parameters is selected to pre-heat the powders to obviously reduce the splash. For the bailing of scanning line,the process parameters with the ratio of power to scanning speed greater than 0. 10 are employed to form a continuous scanning line. One-dimensional scanning line and two-dimensional layer with high performance are obtained by process parameters optimization to lay a foundation for three-dimensional solid object fabrication.