脉冲PAW+缆式七丝焊丝MIG复合焊的电弧耦合行为及熔池振荡行为的研究

Pulse PAW-MIG hybrid welding with cable-type seven wires is a innovative welding process, which has an efficient, high quality and low cost. Seven wires and plasma arc are both acted to the weld pool during welding process. Arc are rotating and coupling at wire tip when the cable type wire is feed, which are acting together with periodic contraction and expansion arc of pulse plasma arc. This unique arc shape can increases the fluidity of molten pool. However, mutual interference exists between the MIG arc and plasma arc. Too many process parameters are existed, and can effect the stability of the arc. The dynamic behavior is very complex. So far, its action physics mechanism remains still unclear. In this project, numerical simulation and experimental verification method are combined. According to process characteristics of the pulse PAW-MIG hybrid welding with cable-type seven wires, the coupled arc behavior, droplet transfer and weld pool oscillation and fluid behavior are studied. The influence rule of welding parameters on the coupled arc behavior, droplet transfer and weld pool oscillation and fluid behavior can be obtain. After that, pulse modulation technique is carried out to weld variable thickness workpiece stablely. The correlation among "welding specification parameters - coupled arc behavior - keyhole and the shape of weld pool – weld formation " is determined. This project can promote comprehensive understanding of the dynamic process of pulse PAW-MIG hybrid welding with cable-type seven wires, and can enrich and develop the physical mechanism of welding heat transfer and mass transfer. Therefore, this research has important scientific significance and practical value.

脉冲PAW+缆式七丝焊丝MIG复合焊是一种高效、优质、低耗的新型焊接工艺。焊接时七根焊丝与等离子弧共同作用于熔池。缆式焊丝送进时端部电弧旋转耦合，与脉冲等离子弧的周期性涨缩共同作用形成独特的电弧形态，增强了熔池的流动性，但丝极间电弧相互干扰，影响因素众多，动态行为复杂，其电弧物理作用机制仍不明确。本研究采用数值模拟和试验验证相结合的方法，依据脉冲PAW+缆式七丝焊丝MIG复合焊工艺特点，开展其电弧耦合行为、熔滴过渡与熔池振荡及流体行为的研究，获得焊接规范参数对焊接电弧耦合行为、熔滴过渡和熔池振荡及流体行为的影响规律，继而开展PAW脉冲调制研究，实现对变厚度截面焊接工件的稳定焊接，确立“焊接规范参数-电弧耦合行为-小孔和熔池形态-焊缝成形”之间的相关性。本项目能促进对脉冲PAW+缆式七丝焊丝MIG复合焊接动态过程的全面系统理解，丰富和发展焊接传热传质理论，具有重要的科学意义和实际价值。

脉冲PAW+缆式七丝焊丝MIG复合焊综合了脉冲等离子弧焊、复合焊和缆式焊丝MIG等工艺的优点，对于中、厚壁开坡口焊件可以单道一次填充，熔敷速度高，焊接速度快，具有广阔应用前景。.项目采用数值模拟和试验验证的方法进行了系统研究，结论如下： .1、利用高速摄像拍摄了脉冲PAW+缆式七丝焊丝MIG复合焊电弧及熔滴过渡的动态行为。.2、开展了七丝缆式焊丝气保焊的电弧以及熔滴过渡的数值模拟。缆式焊丝MIG电弧的电流密度、温度场、速度场、电弧压力以及电弧电势均随着焊接电流的增大而显著增加。电弧温度场受到保护气气流量大小的影响甚微。随着焊接电流增大，缆式焊丝MIG熔滴尺寸减小，过渡频率显著增加。试验与仿真吻合良好。.3、建立了脉冲PAW+缆式七丝焊丝MIG复合焊电弧的数理模型，结果表明：增大等离子焊接电流，复合焊中MIG弧的温度场、速度场、压力场以及电流密度场均增大。随着MIG焊焊接电流的增大，复合焊中MIG弧的温度场、速度场、压力场以及电流密度场均增大。随着丝极间距的增大，对复合焊中电弧最高温度影响并不明显，但是对电弧形态影响很大。试验与仿真吻合良好。.4、建立了适用的三维瞬态小孔、熔池流体流动及温度场的数理模型，结果表明：随着等离子焊接电流增加，等离子弧穿透能力逐渐增强，熔深不断增加，熔宽也随之变宽，但其幅度要远远小于熔深。当等离子电流不变时，随MIG焊接电流增加，熔深变大，熔宽增大，熔池呈现上宽下窄形态。随焊速增加，熔宽减小，焊缝余高先增大再减小。熔池内金属的流动速度虽然有所降低，但是变化并不大。.5、通过对比研究焊接过程中焊缝的大小随着焊接速度、MIG焊接电流以及等离子焊接电流的变化规律，发现试验规律与模拟规律一致。.项目揭示了脉冲PAW+缆式焊丝GMAW的电弧物理行为，为推广脉冲PAW+缆式焊丝GMAW焊接奠定了理论基础。