针对钨极氩弧焊(TIG)电弧高频引弧存在易破坏其周围设备、危害人体健康等问题,提出了采用激光等离子体引燃TIG电弧的新方法。以峰值时间为10 ms的CO2脉冲激光进行TIG电弧的引弧试验,并采用高速摄像观察了激光等离子体引燃TIG电弧过程中的等离子体形态。试验结果表明,激光等离子体的形态和大小是引弧成功与否的关键因数之一,只有当激光等离子体接触到钨极导致电极与工件之间的间隙被导通产生电子发射并形成自持放电时才能引燃电弧。在此基础上,进一步研究了保护气体成分、工件材料、激光束离焦量以及保护气体流量等因数对激光等离子体引弧性能的影响规律。

The high-frequency method may possibly disrupt operation of peripheral equipments and is harm to human body in tungsten inert gas (TIG) arc welding process,so a new method that the laser induced plasma ignites the TIG arc is presented. In this paper,a pulsed CO2 laser with pulsed width of 10 ms is used to ignite the TIG arc. A high-speed visual sensing system is established to detect the process of laser induced plasma triggering arc discharge and the shape of plasma. The experimental results show that the shape and volume of laser plasma are ones of the key factors. And only when the laser plasma contacts the tungsten rod,which therefore results in producing electron emission and forming self-maintaining discharge,the TIG arc can be ignited. Furthermore,the influence of main factors,such as shielding gas,workpiece materials,defocusing distance,and flow of shielding gas etc.,on the shape,the volume and the performance for triggering arc discharge of laser plasma are studied.