缆式焊丝气保焊多弧旋转耦合机理研究

GMAW with cable-type wire is an innovative arc welding process using twisted multi-wire as the consumable electrode. Being provided prominent advantages of high efficiency, high-quality and low power consumption, it has broad application prospects. After preliminary researches on the new arc welding process, many unique welding physical phenomena have been found, such as unique multi-arc rotating and coupling phenomena, stable droplet transfer method with small drops or transfer along the slag wall, existence of stable quasi-arc phenomena and stable vortex fluid flow patterns of molten metal in the pool. Based on the experimental analysis and numerical simulation methods, the rules involving division of welding current in each component of cable-type wire (rule of arc composition) ,multi-arc generation and the process of their merging into a big arc after their rotating and coupling, droplet transfer, (1,rule of arc behavior), heat and force production(2,rule of arc behavior) and fluid flow(3, rule of arc behavior) are studied according to the features of the welding process of new type, comprehenively revealing the mechanism of multi-arc rotating and coupling , thus providing the theory and application basis for the new arc welding process. The causes that lead to the high efficiency, quality and low power consumption of the new welding process is exposed, paving the way to promote the new arc welding process and equipment development.

缆式焊丝气保焊是以多根焊丝绞合的缆状式焊丝为熔化极的一种创新性弧焊新工艺，具有高效、优质和低耗等突出优点，应用前景广阔。申请者对其进行了初步研究，发现许多独特的焊接物理现象，如独特的多弧旋转耦合现象、稳定的细颗粒熔滴自由过渡或沿渣壁过渡形式、存在稳定的潜弧现象和熔池液态金属涡流型流动模式等。本研究采用实验与数值模拟相结合的方法，依据缆式焊丝气保焊工艺特点，通过对缆式焊丝气保焊过程中，焊接电流在缆式焊丝中各分丝的传导分配规律，多弧产生、旋转耦合进而合成为统一大弧（电弧组成规律）、电弧的产热产力规律（电弧行为规律1）、熔滴过渡规律（电弧行为规律2）和熔池流动规律（电弧行为规律3）等研究，揭示缆式焊丝气保焊多弧旋转耦合机理，从而为缆式焊丝气保焊工艺提供理论基础和应用工艺理论；揭示缆式焊丝气保焊高效、优质和低耗的产生原因，为缆式焊丝气保焊工艺的推广应用和焊接设备研制奠定理论基础。

缆式焊丝气保焊是一种以七根分焊丝绞合而成的缆状式焊丝为熔化极的新型电弧焊工艺，有着高效节能优质的优点。.（1）研究了缆式焊丝结构和捻制关键技术。制丝过程中通过张力调节装置、预变形装置、压线模装置以及去应力装置可以解决绞合过程中可能存在的张力不均匀、焊丝松散、焊丝直径大小不一以及残余应力等问题，保证了焊接过程的稳定性。.（2）建立了缆式焊丝产热数学模型，推导出缆式焊丝电阻与焊丝层数之间的关系，研究了缆式焊丝电流分配规律和多极区耦合机理。流过缆式焊丝中心丝的电流小于外围焊丝电流，随着焊丝层数的增加，流过中心焊丝的电流占流过缆式焊丝的电流比减小；阳极区是由三类多极区耦合而成，每类多极区的数量随着焊丝层数增加而增多。.（3）开展了缆式焊丝气保焊与传统埋弧焊对比工艺试验。相同焊接条件下，缆式焊丝气保焊与传统埋弧焊相比，熔敷速度提高35%左右，节约电能28%左右，缆式焊丝气保焊焊缝成形美观，焊接过程中焊接电弧旋转，对熔池产生强烈搅拌作用，使得缆式焊丝气保焊接头热影响区晶粒较细。.（4）研究了缆式焊丝气保焊熔滴过渡规律。随着焊接参数增大，缆式焊丝气保焊焊接电弧由钟罩状逐渐过渡到束状形态；7根分焊丝同时熔化汇聚形成一个熔滴并逐渐长大，依次呈排斥过渡、颗粒过渡和射滴过渡行为；熔滴过渡频率从18.17Hz增加到119.05Hz，熔滴直径由焊丝直径的1.5倍减小到0.3倍。.（5）建立了缆式焊丝气体保护焊对接焊的温度场和应力场有限元分析模型。计算出的焊缝横断面形状与实际结果吻合良好；相同焊接条件下，缆式焊丝气保焊与传统埋弧焊相比，缆式焊丝气体保护焊焊件上表面热影响区较埋弧焊窄，近缝区冷却速度较快，热循环峰值温度较低；焊件下表面高温区分布区域较埋弧焊稍大。对缆式焊丝气体保护焊和埋弧焊应力场进行了有限元分析，相同焊接条件下，缆式焊丝气保焊应力分布及大小与传统埋弧焊相近。.本项目获得了缆式焊丝气保焊多极区耦合机理、熔滴过渡规律及熔池流体动力学的影响机理，丰富和发展了缆式焊丝气保焊传热传质物理机制，具有重要的学术价值和实际意义。