多通道气流压缩TIG-MIG复合电弧的热-力特性及其对熔滴/熔池行为的影响机制

TIG-MIG hybrid arc breaks through the inherent constraints of conventional single arc in mass, heat and pressure transfer, and has potential advantages in high efficiency welding. However, due to the opposite polarity of tungsten electrode and welding wire, the repulsion effect of reversed magnetic field suppresses the heat-pressure coupling of the two arcs, resulting in insufficient penetrating ability and weak stability of weld formation. In this project, the multi-channel gas flow is adopted to compress the hybrid arc directionally and produce further enhancing effect to improve its penetrating ability and weld formation stability. It investigates the interaction mechanism between the gas flow compression and hybrid arc, especially the micro-scale behaviors of particles (motion, collision and ionization) inside hybrid arc, by considering self-magnetic contraction and reversed-magnetic repulsion. The influence of gas compressing pressure on the macro-scale heat-pressure characteristics of hybrid arc is revealed. The coupled model is developed for multi-physical fields, such as gas pressure field, electromagnetic field, fluid flow field and temperature field both in hybrid arc and weld pool. Numerical simulation and experimental measurement are performed together to analyze the physical properties of hybrid arc as well as the behavior of both droplet and weld pool, under the condition with and without gas flow compression. The effect of gas flow compression on the penetrating ability and weld formation stability is elucidated. The optimization and matching among multi-channel gas flow parameters, welding electrical parameters and structural parameters of hybrid welding torch are established. The expected results will enrich the theory of welding processes, and provide theoretical basis and technical support for the practical application of multi-channel gas flow compressing TIG-MIG hybrid welding technology in the field of high-efficiency welding.

TIG-MIG复合电弧突破了传统单电弧在质-热-力传递方面的固有约束，在高效焊接领域具有潜在优势。但由于钨极与焊丝极性相反，异磁互斥效应抑制两电弧的热-力耦合，导致电弧熔透和稳定成形能力较弱。本项目采用多通道气流定向压缩复合电弧，产生进一步的强化效应以提高其熔透和稳定成形能力。研究气流定向压缩对本身已存在自磁收缩和异磁互斥效应的弧柱区内粒子运动、碰撞与电离等微观行为的作用机制，揭示气流压缩对电弧宏观热-力特性的影响规律。建立气流压力场与电弧/熔池内电磁场-流场-温度场的多场耦合模型，数值模拟与实验测试相结合，分析施加气流与否时电弧物理特性与熔滴/熔池行为的差异，阐明气流压缩对电弧熔透能力及焊缝成形的影响规律。实现多通道气流参量、焊接电参数、复合焊枪结构参数之间的优化匹配。预期成果将丰富焊接工艺理论，为多通道气流压缩TIG-MIG复合焊接新工艺在高效焊接领域的实际应用提供理论依据和技术支撑。

现代制造业中，对于薄板结构的焊接成形，钨极情性气体保护焊(TIG)和熔化极气体保护焊(MIG)具有成本低、适应性强等优点。但当焊接速度提高时，焊缝产生咬边和驼峰缺陷,成为企业提高生产效率的“瓶颈”。本研究将TIG与MIG复合，施加多通道压缩气流，改善电弧热-力特性，既减小熔池液态金属后向流动速度，又促进其横向铺展，达到同时抑制高速焊咬边和驼峰缺陷的目的。.采用视觉传感系统和插值算法研究了熔化极气体保护焊接过程中熔池表面的液态金属流动。通过分析不同焊接速度、焊接电流和保护气成分下熔池的流动模式及其驱动力，研究了焊缝的形成机理。建立了计算流体动力学模型来研究高速熔化极气体保护电弧焊(MIG)中的咬边成形。采用可自适应熔池表面变形的双椭圆“电流密度-电弧压力-电磁力电弧热”一体化模型，模拟了熔池中的多物理场耦合传输现象，定量分析了驱动力对液态金属行为和咬边形成的影响。开展双层保护气熔化极脉冲焊（D-MIG-P）工艺试验。采用两个独立的通道提供保护气体，内层通道通入氩气，外层通道通入二氧化碳，使双层保护气下的电弧电流密度分布能在熔滴颈缩处产生强大的电磁收缩力，有利于熔滴过渡，从而提高焊接稳定性。研究了电极相对位置和TIG电流变化对TIG-MIG复合电弧焊接电弧稳定性和焊缝成形的影响，并与常规MIG焊接进行了比较。分析焊接电流-电压波形以表征电弧稳定性。建立了包括压缩气流、电弧等离子体和熔滴在内的TIG-MIG复合电弧三维瞬态模型。分析了压缩气流对电弧形状、电流密度、温度场、压力分布、电磁力和熔滴过渡等行为的影响机制。压缩气流使电弧等离子体外层区域收缩，使熔滴表面产生的铁蒸汽在电弧内层扩散，改变了热压力分布。揭示了压缩气流与复合电弧以及熔滴的相互作用机制。.本研究基于数值模拟与实验测试结果实现压缩气流参数、焊接电参数与焊枪结构参数之间的优化匹配，为推动TIG-MIG复合焊接新工艺在高速焊接制造领域的实际应用奠定坚实基础。