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为了得到同轴送粉激光熔覆中激光束穿过粉末流后的能量变化,研究了粉末浓度分布对激光能量的衰减作用。模拟了稳态、存在基底和熔池的情况下粉末流的空间分布,通过粉末浓度与激光能量衰减的关系,得到了任意粉末分布及激光能量分布下的衰减率。研究了基底对气流场的作用以及基底对粉末的反弹作用两种因素对粉末浓度分布的影响,并比较了平顶形光束在不同熔池尺寸和送粉率下的衰减率。结果表明,存在基底时粉末流对激光的衰减率比无基底作用时一般高2倍以上,与送粉率成正比,在熔池尺寸较小时与其大小成反比。
In order to get the energy change of the laser beam passing through the powder stream in the coaxial powder cladding laser cladding, the attenuation of the laser energy by the powder concentration distribution was studied. The spatial distribution of powder flow in the steady state and in the presence of the basal and molten pool was simulated. The attenuation rate under any powder distribution and laser energy distribution was obtained by the relationship between the powder concentration and the laser energy attenuation. The influence of the substrate on the gas flow field and the rebound effect of the substrate on the powder concentration were studied. The decay rate of the flattened beam under different melt pool size and powder feeding rate was compared. The results show that when the substrate is present, the decay rate of the laser powder to the laser is more than 2 times higher than that without the substrate, which is proportional to the powder feeding rate. It is inversely proportional to the size when the size of the weld pool is small.