双丝GMAW电弧干扰及焊接工艺研究

发布时间：2018-05-20 02:37

本文选题：双丝GMAW焊接 + 电弧干扰　；参考：《上海交通大学》2015年硕士论文

【摘要】：随着船舶、汽车、航空航天等现代制造业的飞速发展,对于高效焊接技术的需求迫在眉睫。为了提高焊接效率,可以采用双丝或多丝GMAW的方法。在双丝GMAW焊接中的一个突出问题是由电磁力而产生的电弧干扰。因此,如何有效抑制或克服电弧干扰,成为焊接工作者一个重要的研究课题,另外,双丝焊的焊接工艺参数匹配对焊缝成形、熔滴过渡的稳定性也存在很大的影响。本文构建了一套双丝GMAW焊接平台,包括自动焊接系统、电信号采集系统以及高速摄影系统;针对焊接过程中的电弧形态、熔滴过渡模式、电流电压波形进行系统的研究和分析,对电弧干扰的成因给出了解释和抑制方法;分析了在双丝GMAW焊接过程中弧长变化引起的稳定焊接工作点的迁移;分析了工艺参数匹配对焊缝成形的影响规律,最后,采用双丝GMAW对焊和jk焊E36钢,对比分析了单丝和双丝的焊接头显微组织、力学性能、焊接效率和极限速度。结果表明,单丝GMAW焊接电弧呈钟罩型,焊接过程稳定;双丝GMAW焊接电弧会产生一定偏移,增大引导弧(前弧)电流使之大于跟随弧(后弧),增大双丝间距,采用混合保护气替代纯氩保护气体都可以有效缓解电弧干扰现象,使焊接过程趋于稳定。单丝GMAW焊接熔滴过渡模式为射滴+射流过渡,熔滴过渡稳定。双丝GMAW焊接熔滴过渡躁动性增强,过渡路径向两弧中心偏离,增大引导弧(前弧)电流使之大于跟随弧(后弧),熔滴过渡过程会趋于稳定。采用FLOW-3D模拟与实验结合研究双丝焊工艺参数对焊缝成形的影响,得到引导弧电流大于跟随弧电流的这种电流配比下,熔池内部同时存在“推-拉”流动方式和向外流动方式,焊缝成形更优良,引导丝电流减小,不存在明显的“推-拉”方式,只存在向外流动方式,出现液态金属收缩和提前凝固现象,焊缝成型差。在双丝焊应用方面,对比单丝GMAW与双丝GMAW对接焊E36钢,发现单丝与双丝对接焊焊接接头金相组织、力学性能相近。在相同速度下,双丝焊接的效率要比单丝焊接高出37.5%;在相同电流电压参数下,双丝GMAW可以达到的无驼峰缺陷的极限焊接速度更高。将双丝GMAW应用于60mm深度坡口大厚板的横焊,采用最佳焊接规范参数可取得高效高质量的焊缝成形。
[Abstract]:With the rapid development of modern manufacturing industry, such as ship, automobile, aerospace and so on, the demand of high efficiency welding technology is urgent. In order to improve welding efficiency, double wire or multi-wire GMAW can be used. A prominent problem in double wire GMAW welding is the arc interference caused by electromagnetic force. Therefore, how to effectively suppress or overcome the arc interference has become an important research topic for welding workers. In addition, the matching of welding parameters of double-wire welding also has a great impact on the stability of weld formation and droplet transfer. In this paper, a two-wire GMAW welding platform is constructed, including automatic welding system, electrical signal acquisition system and high-speed photography system, and the research and analysis of arc shape, droplet transfer mode, current and voltage waveform in welding process are carried out systematically. The cause of arc interference is explained and the method of restraining arc interference is given. The migration of stable welding point caused by arc length variation during double wire GMAW welding is analyzed. The influence of process parameter matching on weld forming is analyzed. The microstructure, mechanical properties, welding efficiency and limit speed of single wire and double wire welding joint were compared and analyzed by using double wire GMAW butt welding and JK welding E36 steel. The results show that the arc of single-wire GMAW welding is bell-shaped, and the welding process is stable, and the arc of double-wire GMAW welding will have a certain deviation, which will increase the current of guide arc (front arc) so as to be larger than that of the following arc (back arc), and increase the distance between two wires. The arc interference can be effectively alleviated by using mixed protective gas instead of pure argon protection gas, and the welding process tends to be stable. Single wire GMAW welding droplet transfer mode is jet transfer, droplet transfer stability. The mania of droplet transfer in two-wire GMAW welding is enhanced, the transition path deviates to the center of the two arcs, and the current of the guide arc (front arc) is larger than that of the following arc (rear arc), and the droplet transfer process tends to be stable. FLOW-3D simulation and experiment were used to study the influence of welding process parameters on weld formation. The results show that there are "push-pull" flow modes and outward flow modes in the molten pool when the guiding arc current is larger than the following arc current. The weld is better in forming, the guiding wire current is reduced, there is no obvious "push-pull" mode, there is only outward flow mode, liquid metal shrinkage and early solidification appear, and the weld formation is poor. In the application of double wire welding, compared with single wire GMAW and double wire GMAW butt welding E36 steel, it is found that the microstructure of single wire and double wire butt welding joint is similar and the mechanical properties are similar. At the same speed, the efficiency of double wire welding is 37. 5% higher than that of single wire welding, and under the same current and voltage parameters, the limit welding speed of double wire GMAW without hump defect is higher than that of single wire welding. The double wire GMAW is applied to the transverse welding of 60mm deep groove thick plate. The high efficiency and high quality weld forming can be obtained by adopting the best welding specification parameters.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG444

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