CO_2气体保护焊表面张力的过渡

Surface tension transformation in CO_2 arc welding

CO2 气体保护焊采用短路过渡 ,飞溅大、成形差。在研究CO2 气保焊短路过渡理论基础上 ,深入研究了表面张力过渡各个阶段参数与送丝速度的关系、焊接电压与液桥缩径状态的检测方法。研究表明 ,在表面张力过渡区内存在一段失控区 ,增加了表面张力过渡的不确定性。随着送丝速度的变化 ,熔滴过渡各阶段时间影响液桥分断时的表面张力过渡。依据表面张力过渡对电源特性的要求 ,提出了两种实现方案 ,逆变环节控制和输出斩波控制 ,并指出仅采用逆变环节实现表面张力控制的局限性 ,研究还表明改变表面张力过渡区的电流值可改善过渡的稳定性。研究方案在实际中得到了验证。

The short-circuit transformation is always adopted in CO 2 arc welding process,which has disadvantages of high spatter and bad welding formation.Basing on the study of short-circuit transformation in CO 2 arc welding,the paper presented the relation between the parameters in each phase in surface tension tranformation(STT) and the wire feed.The method to test the welding voltage and the state of liquid bridge is also presented in this paper.The results show that the droplet is out of control before liquid bridge breading,which increases the unstablity of STT.With the variety of wire feed speed,the interval of each phase of droplet transformation has a great influence on the breaking state of liquid bridges.According to the requirement to the welding power in STT,two designs,invert-loop control mode and output control mode,have been pre-sented.The limitation of the invert-loop control mode in STT control is also put forward.The result shows that by adjusting the current in each phase can improve the stability of the transformation in STT.The project has been validated by experiment.