摘要
在激光熔覆过程中,三通道同轴送粉喷嘴是关键部件,它利用惰性气体将金属粉末稳定地输送到熔池,同时形成保护流场,隔绝周围的空气。喷嘴气体流场对粉末的汇聚和高温区域的保护具有显著的作用,直接影响粉末利用率、金属材料性能和零件的成形精度。为了研究喷嘴保护流场特性,文中采用粒子图像测速(PIV)技术结合数值模拟计算,对自研的三通道同轴送粉喷嘴气体速度场分布进行了试验和分析。结果表明,喷嘴中心、内环和外环三个通道出口的气流速度一致时,喷嘴所形成的流场较为稳定,没有涡流存在。因此,粉末的汇聚性及对溶池的保护效果好;当外通道气流速度大于内通道时,在工件表面上出现旋涡,流场呈不稳定状态;随喷嘴与工件表面距离增加,有效保护范围减小。
In laser cladding, the three-duct coaxial powder feeding nozzle is an important component, which stably feeds metal powder to the melting pool with inert gas, and also forms shielding gas flow field to isolate the surrounding air. The gas flow field of the nozzle is significant for converging of the power and protection of the high-temperature area, which directly affects the power usage, performance of the metal material, and the forming precision of the parts. In this paper, in order to study the features of the shielding gas flow field, experiment and analysis on distribution of the gas velocity field of the three-duct coaxial powder feeding nozzle were carried out by adopting the PIV technology, combined with numerical simulation and calculation. The re- sult indicates that stable flow field can be obtained in the nozzle when the gas velocities at the outlets of the central, inner ring and outer ring ducts are consistent and the vortex disappears. It is beneficial to the conver- gence of the power and protection of the melting pool. When gas Velocity in the outer duct is greater than that in the inner duct, vortex appears on the workpiece surface, and the flow field becomes unstable. With the in- crease of the distance from the nozzle to the workpiece, the range of efficient protection decreases.
出处
《中国表面工程》
EI
CAS
CSCD
北大核心
2012年第1期51-55,共5页
China Surface Engineering
