窄间隙双缆式十四丝GMAW焊接的电弧物理特性、熔滴过渡与熔池流体行为研究

As comsumable electrode, cable-type wire which is twisted by multi-wire can provide prominent advantages of high efficiency, high-quality and low power consumption. It has broad application prospects. In this study, cable-type wire twisted by seven wire is applied to double wire narrow gap welding using gas metal arc welding. Therefore, an innovative double wire narrow gap welding using gas metal arc welding with fourteen wire is created. A total fourteen wire is put into one weldpool. The arc is rotating at wire ends when the cable type wire is feed. There is a unique multi-arc coupling morphology. The arc can rotate autonomy without the help of additional complex mechanical or electromagnetic driving arc rotation device. The rotating arc can promote the heat flowing to the sidewall, so as to solve the sidewall penetration deficiencies during traditional narrow gap welding. However, mutual interference exists between the 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 mechanism is still unclear. In this study, numerical simulation and experimental verification method are combined. According to process characteristics of the narrow gap twin cable-type wire GMAW, the arc physical characteristics, droplet transfer and fluid behavior in weldpool is studied. The influence rule of welding parameters on the arc physical characteristics, droplet transfer and fluid behavior in weldpool can be obtain. It is helpful to establish the basic theory and process theory during narrow gap GMAW with twin cable-type wine twisted fourteen wire. Research results can reveal the arc physical nature of the narrow gap GMAW with twin cable-type wire and enrich the physical mechanism of welding heat transfer and mass transfer.

以多根焊丝绞合的缆状式焊丝为熔化极进行焊接，具有高效、优质和低耗等突出优点，应用前景广阔。本研究将七丝缆式焊丝应用于双丝窄间隙熔化极气保焊，创建了窄间隙双缆式十四丝GMAW新方法。焊接时十四根焊丝共熔池，缆式焊丝送进时端部电弧旋转，形成独特的多弧旋转耦合形态，无需外加复杂机械式或电磁式驱动电弧旋转装置即可实现电弧自主旋转，促进热流向侧壁传递，从而解决传统窄间隙焊侧壁熔深不足之问题。但丝间电弧相互干扰，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，依据窄间隙双缆式十四丝GMAW工艺特点，开展其电弧物理特性、熔滴过渡与熔池流体行为的研究，获得焊接规范参数对焊接电弧物理特性、熔滴过渡规律和熔池流体行为的影响规律，建立窄间隙双缆式十四丝GMAW的基础理论和工艺理论，从而揭示窄间隙双缆式十四丝GMAW的电弧物理本质，丰富和发展焊接传热传质物理机制。

项目综合了窄间隙焊、双丝焊和缆式焊丝GMAW的三种高效焊接技术的优点，独特的多弧旋转耦合电弧增加了熔池内流体的搅动，解决了常规窄间隙焊接时侧壁熔合不良的理论问题，具有广阔的工业应用前景。.项目采用数值模拟和试验验证的方法对双缆式焊丝GMAW窄间隙焊的电弧特性、熔滴过渡行为和熔池流体行为进行了研究，结论如下：.(1) 焊接电流、Ar气流量、双丝间距对缆式焊丝GMAW电弧特性影响.单缆式焊丝GMAW，焊接电流为400-600A和气流量为15-35L/min时，随着焊接电流增大，电弧的电流密度、电磁场、温度场、速度场和电弧压力最大值增加；电弧电流密度和温度最大值始终位于焊丝阳极端部；电弧等离子流速最大值始终位于弧柱区；电弧最大压力位置由速度入口向阳极区转变。气流量每增大10L/min，电弧等离子流速提升21-29%；阳极区的最大压力增大100-122Pa；电弧压力在工件表面附近的峰值压力增大50-55Pa，其作用范围半径增大1.7-2mm。.双缆式GMAW焊接过程中，随焊接电流的增加，电弧特性值均增大；电弧温度最大值位于焊丝端部，电弧等离子流速最大值位于轴向焊丝端部2~8mm处，而电弧中间轴处压强达到最大值。随着Ar气流量增加，径向等离子弧最大速度和工件表面最大电弧压力明显增加，电弧温度变化不大。双丝间距由10mm增加至15mm和20mm，电弧速度场和压力场最大值从由速度入口向焊丝端部转移。.(2) 焊接电流对缆式焊丝GMAW的熔滴过渡行为的影响.焊接电流从400A增加至500A，熔滴尺寸减小，电流每增加50A，熔滴尺寸分别减小11%和43%；熔滴完成一次完整过渡的时间逐渐缩短，分别为25ms、18ms和13ms；熔滴过渡频率显著增加，分别为40Hz、58Hz和78Hz。实验验证了所建熔滴过渡的三维模型的准确性。.(3) 研究了窄间隙双缆式焊丝GMAW熔池的流体行为.随着间隙量的增加，熔池温度场及流场的分布范围增加，熔池内部最高温度和最大流速减小。间隙量为14mm、16mm、18mm熔池的最高温度分别为3219K、3134K和3022K，最大流速分别为14.1cm/s、13.4cm/s和12.6cm/s。模拟结果和试验结果吻合良好。.项目揭示了窄间隙双缆式GMAW电弧产热产力机理，为推广窄间隙双缆式十四丝GMAW焊接奠定了理论基础。