激光熔覆垂直及倾斜工况下粉末输运行为研究

Research on Powder Transport Behavior of Laser Cladding Under Vertical and Inclined Working Conditions

通过建立同轴喷嘴和粉末输运过程的数值模型,采用数值仿真模拟的方式研究了不同工艺参数下,同轴喷嘴在垂直和倾斜使用工况下粉末汇聚性的变化规律。结果表明:粉末聚焦处的粉末浓度随载粉气速度的增加而降低,而保护气速度对粉末浓度影响较小;在载粉气流量为8 L/min,保护气流量为20 L/min,送粉量为15.8 g/min时,相比于同轴喷嘴垂直使用,倾斜使用条件下粉末的聚焦高度由19 mm升高到21 mm,焦点直径由3.7 mm增大到4.2 mm;同轴喷嘴垂直使用时粉末分布的均匀性更好;数值模拟结果与试验结果吻合良好,可以准确反映不同送粉方式中粉末的输运特性。

In this study,we developed a numerical model of the coaxial nozzle and powder transport process.Using numerical simulation we examined the effect of different processing parameters on powder convergence in the coaxial nozzle under both vertical and inclined conditions.Our results indicate that an increase in carrier gas velocity leads to a decrease in powder concentration at the powder focusing location,while the velocity of the shielding gas has little effect on the powder concentration.When the carrier gas velocity is 8 L/min,the shielding gas velocity is 20 L/min,and the powder feeding rate is 15.8 g/min,the use of the coaxial nozzle in an inclined position increases the focusing height of the powder from 19 mm to 21 mm and the focus diameter from 3.7 mm to 4.2 mm,compared to that in a vertical position.However,the uniformity of the powder distribution is much better when the coaxial nozzle is used vertically.Our numerical simulation results are consistent with the experimental results and can accurately reflect the powder transportation characteristics under different powder delivery methods.