摘要
CO2气体保护焊因成本低、生产率高等特点,广泛应用于制造业。随着制造业节能减排的需求日益增加及汽车轻量化概念的推广,制造业对薄板焊接的要求不断提高,传统的焊接方式已不能满足其要求。CO2短路过渡焊相对于传统的焊接方式(钨极氩弧焊、熔化极氩弧焊、激光焊等),具有高热稳定性、低热输入、低熔深等特点,但其焊接飞溅大、焊缝成形差,从而限制了其广泛应用。CO2短路过渡焊接过程是由燃弧阶段与短路阶段组成的复杂的非线性时变系统,熔滴过渡过程决定了焊接过程的稳定性与焊缝成形的优劣。燃弧阶段熔滴在电磁收缩力、表面张力、等离子流力、金属蒸发反作用力等多种力的共同作用下长大并与熔池接触短路,同时形成稳定液桥。短路阶段,液桥在表面张力、电磁收缩力和粘滞力的作用下形成缩颈并断开。燃弧阶段的熔滴尺寸、振荡特性,短路阶段熔池的振荡特性、峰值电流都对熔滴过渡稳定性有十分重要的影响。针对短路过渡焊飞溅产生机制的研究表明,熔滴、熔池的氧化还原反应、短路前期产生的瞬时短路和短路末期液桥电爆炸是导致焊接过程不稳定及产生飞溅的主要因素。国内外众多焊接研究者针对CO2短路过渡焊熔滴过渡过程及控制技术进行了大量的研究与探索,研究工作主要分为四个方向:焊接材料成分的优化,基于焊接电源输出电信号的熔滴过渡建模及控制,基于视觉传感技术的熔滴过渡控制和基于磁控技术的CO2短路过渡焊接技术。活性焊丝和药性焊丝的推广可有效降低焊接飞溅;波控技术及衍生的CMT技术在使用小电流参数焊接时取得了优异的焊接效果;中、小电流参数条件下,磁控焊接技术可有效解决焊接飞溅和成形差问题。本文从焊丝、电源、外加磁场形式和工艺四个方面综述了国内外CO2气体保护焊短路过渡控制技术的研究现状,首先分析了CO2短路过渡焊焊接飞溅的产生机理,其次介绍了典型的CO2气体保护焊短路过渡控制技术的原理、特点和局限性,分析了不同短路过渡控制技术的特点,最后阐述了目前短路过渡控制技术在研究和应用过程中存在的问题及解决办法,并对该领域下一步发展趋势进行了展望。
The features of low cost and high productivity enable the widespread application of CO2 gas shielded welding in manufacturing industry.With the increasing demand for energy saving and emission reduction in the manufacturing industry and the promotion of the concept of lightweight automobile,the requirements of thin plate welding in manufacturing are continuously raising,which cause the traditional welding method can hardly meet the new requirements.Compared with the conventional welding approaches(traditional tungsten argon arc welding,argon-arc welding,laser welding,etc.),CO2 short-circuit transition welding is superior due to its high thermal stability,low heat input,low penetration depth,etc.Yet,the large welding spatter and poor weld formation have blocked its promotion and wide application.The CO2 short-circuit transition welding process is a complex nonlinear time-varying system composed of the arcing phase and the short-circuit phase.The droplet transfer process plays a dominant role in affecting the stability of the welding process and the quality of weld molding.In the arcing stage,the droplets grow under the combined action of electromagnetic contraction force,surface tension,plasma flow force,metal evaporation reaction force,and are short-circuited with the molten pool to form a stable liquid bridge.In the short-circuit phase,as a result of the action of surface tension,electromagnetic contraction force and viscous force,the liquid bridge necks down and finally breaks.The size of droplets and oscillating characteristics in arcing phase,the oscillating characteristics of the molten pool and peak current in the short-circuit phase all profoundly impact the stability of the droplet transition.The research on the spatter generation mechanism of short-circuit transition welding shows that the primary factors causing the instability and splashing in the welding process lie in the redox reaction of the molten droplet pool,the instantaneous short circuit generated in the early stage of short circuit and the liquid bridge electrical explosion at the end of short circuit.Great efforts have been put into the research and exploration on the CO2 short-circuit transition welding droplet transfer process and its control technology.Specifically speaking,the research work can be divided into four aspects,including optimizing the composition of welding materials,modeling and controlling droplets transfer based on output electrical signals of welding power,controlling droplet transfer based on vision sensing technology and CO2 short-circuit transition welding technology based on magnetron technology.The promotion of active welding wire and medicinal welding wire can effectively reduce welding spatter.Wave control technology and CMT technology achieve excellent welding effect under small welding current parameters.Magnetron welding technology exhibits notable advantage in solving welding spatter and forming problems under medium and small current parameters.This paper summarizes the research status of the short-circuit transition control technology for CO2 gas shielded welding both at home and abroad from four aspects:welding wire,power supply,external magnetic field form and technology.Firstly,the spatter generation mechanism of short-circuit transition in CO2 welding is analyzed.Then,several typical principles,characteristics as well as limitations of short-circuit transition control technology for CO2 gas shielded welding are introduced in detail.Besides,the characteristics of diverse short-circuit transition control techniques are analyzed.Finally,the existing problems and corresponding solutions in the current process of research and application of the short-circuit transition control technology are elaborated,and the developing trend in this field are also put forward.
作者
陈涛
薛松柏
孙子建
翟培卓
陈卫中
郭佩佩
CHEN Tao;XUE Songbai;SUN Zijian;ZHAI Peizhuo;CHEN Weizhong;GUO Peipei(College of Materials Science and Technology,Nanjing University of Aeronautics and Astronautics,Nanjing 210016;Kunshan Huaheng Welding Equipment Corporation,Suzhou 215300)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2019年第9期1431-1442,共12页
Materials Reports
基金
国家自然科学基金(51675269)
江苏高校优势学科建设工程资助项目~~
关键词
CO2气体保护焊
短路过渡
焊接飞溅
焊缝成形
CO2 gas shielded welding
short circuit transition
welding spatter
weld molding
作者简介
陈涛,2016年6月毕业于中国石油大学(华东),获得工学学士学位。现为南京航空航天大学材料科学与技术学院博士研究生,在薛松柏教授的指导下进行研究。目前主要研究领域为先进连接技术;薛松柏,南京航空航天大学材料科学与技术学院二级教授、研究员、博士研究生导师,享受政府特殊津贴专家。长期以来专注于焊接材料及焊接工艺的研究,制定了五项国家标准、五项机械工业部行业标准并发布实施;主持完成了三十多项国家、部、市课题的研究,共取得主要科研成果三十余项。获得2016年国家科技进步奖二等奖、2014年教育部技术发明二等奖、国防科技进步奖三等奖、江苏省科技进步三等奖等。在国内外学术刊物上发表论文320余篇,SCI收录120余篇,EI收录160余篇,论文他引300余次,单篇他引38次。
