镁合金磁电复合场方波脉冲MIG焊接工艺机理

To promote the low-cost,high quality and high efficiency welding production for magnesium alloy as the background, according to the special physical and metallurge characteristic of magnesium alloy, a novel magnesium alloy AC square wave pulsed MIG welding process based on magneto electric composite field effect is proposed. Through the magnetic-arc non-contact coupling, the effective control of the welding process is achieved. From the joint action of internal cause (welding current with flexible combined-waveform controls the heat input of the welding arc) and external cause (the additional magnetic field changes the welding arc heat input distribution and force status of the droplet), the novel characteristic of welding arc resource heat input and its precise control method under the effect of magneto electric composite field are explored. Based on the water wave theory (WWT) and the magneto-hydro-dynamic (MHD), a novel three dimensional numerical simulation model of the weld pool dynamic behavior for magnesium alloy AC square wave pulsed MIG welding process with magneto electric composite field effect is established to reveal the dynamic evolution law of the three-dimensional temperature field, flow field and the shape changes with time of the molten pool under different magneto electric composite field parameters, which provides a basis for the accurate control of the bead forming. Based on the interaction of the software and hardware synchronization method, a collaborative response mechanism which fully embodies the coupling effect among the function units of the welding equipment is established to ensure that the overall performance conforms to the precise coordination control requirements of the magneto electric composite field parameters. Related research can reveal the process mechanism of the novel welding process with composite field effect, facilitate the integration of the technology and equipment, and promote the development of magnesium alloy welding technology.

针对镁合金独特的物理性能和冶金特点，以推动其低成本、高质量和高效率的焊接生产为应用背景，提出了镁合金磁电复合场方波脉冲MIG焊接新工艺，通过磁-电弧非接触耦合作用实现焊接过程精细调控。从内因（多波形组合的焊接电流精细控制电弧热输入量）和外因（复合磁场改变电弧热输入分布和熔滴综合受力特性）的共同作用出发，阐述电弧热源热输入新特性及其控制规律；利用水波相似模拟方法和磁流体动力学理论，建立描述磁电复合场方波脉冲MIG焊接熔池动态行为的三维数值模拟新模型，揭示熔池在不同复合场参数下的三维温度场、流场和形状随时间变化的动态演变规律，为焊道成形的精确控制提供依据；基于互作用的软硬件同步方法，构建了充分体现焊接装备各功能单元之间物理耦合效应的协同应答机制，确保复合场方波脉冲MIG焊接工艺参数的精确协同调控。项目相关研究能够深入揭示复合场焊接新工艺的机理，促进工艺与设备的融合，推动镁合金焊接新技术的发展。

镁合金独特的物理性能和冶金特点使得其MIG焊接过程中容易出现裂纹、飞溅、电弧稳定性差等问题。项目通过优化电源拓扑结构、提高电流换向速度以及附加换向高压脉冲等方法较好地提升了方波交流MIG焊接电弧稳定性；构建了全数字、可协同的镁合金机器人方波脉冲MIG焊接装备；研究了电弧燃烧不同阶段的能量配置规律，开发了多工艺参数协同调控算法；利用先进的测试分析手段对系统的协同性能、能效、输出波形、正负极性切换过程的电弧稳定性等进行了测试验证；将理论分析和计算模拟相结合，研究了磁场分布特性及其对电弧等离子体运动行为的影响规律，探索了多场作用下的交流方波电弧特性；建立了方波交流电弧焊接过程三维传热与流体流动仿真模型，分析了电流波形对熔池流动及成形的影响；掌握了多工艺参数精细协同与规范优化方法。相关研究促进了镁合金MIG焊接工艺与设备的深度融合，推动了镁合金焊接新技术的发展。