激光点焊等离子体光信号同轴监测及其特性分析

Coaxial Monitoring and Characteristic Analysis of Plasma Optical Signal in Laser Spot Welding

激光焊接时产生的等离子体包含了许多可以反映焊接质量的相关信息。通过光电传感器采集等离子体的光信号可以有效监控激光焊接质量。本文搭建了激光点焊等离子体光信号的同轴监测系统,并对激光点焊过程中采集的光信号进行了短时能量分析。试验结果表明,在焊接起始阶段,工件表面对激光有较强的反射作用。当母材形成熔池以后,等离子体浓度逐渐增加,焊接过程趋于稳定,此时等离子体的光信号强度达到最大。随着焊接时间的增加,熔池发生塌陷,等离子体的稳定性变差,光信号的强度变弱且波动变大。工件被焊穿的瞬间,等离子体光信号强度明显减小。

The plasma produced by laser welding contains a lot of relevant information that can reflect the welding quality.The optical signal of plasma collected by photoelectric sensor can effectively monitor the laser welding quality.A coaxial monitoring system of plasma optical signal in laser spot welding was built,and the analysis of short-time energy of the collected optical signal was carried out.The experimental results show that the workpiece surface has a strong reflection on the laser at the initial stage of welding.When the base metal forms a molten pool,the plasma concentration increases gradually and the welding process tends to be stable.At this time,the optical signal intensity of the plasma reaches the maximum.With the increase of welding time,the molten pool collapses,the stability of plasma becomes worse,the intensity of light signal becomes weaker and the fluctuation becomes larger.At the moment that the workpiece is welded through,the plasma light signal intensity is significantly reduced.