Influence of shielding gases on quality and efficiency in gas shielded arc welding

This article describes the physical principle of function and some examples of the application of the keyhole TIG (K-TIG) welding process.

Due to its specificity, this welding process has been shown to be valid for performing full penetration welds, even with a single pass, on various types of materials, particularly valuable materials: indeed, it is very well suited to being applied to such materials as austenitic stainless steel, titanium and its alloys, nickel alloys, the austeno-ferritic (duplex) steels, obviously in addition to the C–Mn steels.

This article describes the physical principle of functioning of K-TIG welding process, besides some examples of application in different working situations.

Such a welding process has proved itself to be suitable to execute Mel-nil-thickness welding of different kinds of metallic materials (also with a single pass). This welding process is particularly suited to be applied on the most valuable materials, like: inox stainless steel, titanium and its alloys, nickel alloys, duplex steel, C–Mn steels.     

焊接电流对双丝间接电弧焊电弧特性的影响

主要研究了焊丝伸出长度对焊接电流、电弧电压以及焊接电流对双丝问接电弧气体保护焊电弧特性的影响。结果表明,随着焊丝伸出长度的增加,焊接电流减小;双丝间接电弧气体保护焊负极焊丝的熔化速度随着焊接电流的增加而明显增大,正极焊丝的熔化速度随焊接电流的增加而缓慢增大,两者均随着电弧电压的增加而减小;随着焊接电流的增大熔滴变细;双丝问接电弧气体保护焊有多种电弧形态。     

脉冲电源双熔敷极焊条电弧焊焊缝熔深

脉冲电源应用于双熔敷极焊条电弧焊,采用正交试验研究分析脉冲参数对焊缝熔深的影响.结果表明,脉冲参数的变化引起焊缝熔深的相应变化,脉冲参数对焊缝熔深的影响程度由大到小的次序为峰值电流、频率、占空比、基值电流.在试验范围内获得较大熔深时的脉冲参数分别是峰值电流为230~240 A,频率为3.3~3.7 Hz,占空比为48%...     

Recent developments in arc welding with shielding gas of aluminium and its alloys

Summary

Aluminium and its alloys are frequently used in many sectors of industry. Arc welding should adapt to these metals, particularly with regard to productivity and quality. Optimisation of recent innovations are presented here.

In order to adapt to the technological developments of the various sectors of the transport industry (automotive, rail, shipbuilding, aircraft and aerospace), the electricity industry, and the chemical and food‐processing industries, welding processes must also adapt to light metals (aluminium and its alloys) in terms of the productivity and quality required by these industrial sectors.

Recent developments (refinements and innovations) in welding processes, notably MIG welding (dual‐wire welding, modulated spray MIG welding) due to a global approach (procedure, consumables, gas) enable useful alternative solutions to be found for the usual applications of the process.     

电弧摆动对焊接应力场的影响

摆动焊接已经广泛地应用于自动焊接过程中,以获得更高的焊接效率.在摆动焊接过程中,焊接电弧一边沿焊道长度方向运动,一边在焊道宽度方向作一定频率的摆动,这使得热源的坐标轴成"z"字形变化,从而导致摆动焊接数值模拟分析的困难.为了提高计算精度和了解电弧摆动对焊接残余应力场的影响,结合坐标变换的方法建立了摆动焊接的三维有限元模型.和无摆动焊接的残余应力结果对比表明,由于电弧摆动导致熔池附近更高的温度梯度,使得摆动焊接的横向残余应力增大,而对纵向应力场的影响较小.     

焊接小球对CO2焊引弧过程的影响

为了提高焊接生产效率和焊接质量,CO2焊接过程必须要有较高的引弧成功率。焊丝端部小球尺寸对CO2焊的引弧过程影响很大。在引弧过程中焊丝固态爆断时,会导致引弧不成功。当焊丝端部小球未剪除时,会引起电弧引燃到电弧稳定的调节时间过长,造成电弧不稳,焊接飞溅较大。本文借助汉诺威焊接质量分析仪,采集焊接电流和电压波形,并且应用MATLAB软件分析引弧过程,对引弧成功率进行评定。     

轨道车辆不锈钢气体保护拉弧螺柱焊

介绍电弧螺柱焊焊接方法的分类及焊接工艺原理,阐述气体保护拉弧螺柱焊在轨道车辆不锈钢材料上的应用。采用BMK-12W电弧式螺柱焊机进行工艺试验,焊后根据相关标准进行外观检验、弯曲试验和宏观检验。结果表明,气体保护拉弧螺柱焊技术在轨道车辆不锈钢材料的应用良好,能够获得优质的焊接接头。     

电抗器参数对弧焊过程动特性的影响分析

利用自行研制的焊接动态电孤小波分析仪时KR焊接电源的焊接过程的引孤、中间过程、熄孤的电信号进行采集.针对不同的电抗器材料,采用数理统计方法提取焊接过程电流波形的特征信息,从而对焊接过程的动特性进行分析.结果表明,该方法能综合反映孤焊电潭的动特性,可为改进焊接工艺和波形控制方法提供依据.     

Effects of shielding gas composition on arc characteristics and droplet transfer in tandem narrow gap GMA welding

The effects of shielding gas composition in tandem narrow gap gas metal arc welding were studied. The shielding gas included argon, carbon dioxide and helium. The arc characteristics and droplet transfer process were analysed. The results show that in the same welding parameters, the trail wire welding current is higher than the lead wire welding current. With the increase of carbon dioxide content, the welding currents of two wires decrease, and the trail wire droplet transfer mode transforms from spray transfer to projected transfer. With the increase of helium content, the welding currents increase and the lead wire droplet transfer mode transforms from projected transfer to spray transfer. The weld width is the largest when the shielding gas mixture is 80%Ar10%CO₂10%He.     

保护气体对激光+双丝MAG复合焊焊缝形貌和电弧特性的影响

在激光+单电弧复合焊工艺的基础上,通过再添加一个电弧的方式,形成激光+双丝脉冲MAG复合焊工艺。研究了保护气体为φ(Ar)80%+φ(CO2)20%(情况A)和φ(Ar)40%+φ(CO2)10%+φ(He)50%(情况B)时对激光+双丝MAG复合焊焊缝表面成形和电弧特性的影响。利用LabVIEW信号采集系统和高速摄像系统同步采集焊接电流、电弧电压波形和电弧形态。结果表明,在焊缝表面和焊道两侧边缘处,肉眼可见斑点状、不连续的氧化物,情况A与情况B相比,情况A氧化物含量高,熔宽小;而情况B焊道平整,鱼鳞纹清晰。情况A中由于CO2含量较高,使其对电弧的冷却作用增强,减弱了激光对电弧的稳定作用,断弧次数比情况B多。     

CO_2激光-MAG电弧复合焊过程中激光功率对电弧及熔滴行为的影响

利用高速摄像系统和电弧分析仪分析CO2激光-MAG电弧复合焊过程中激光功率对电弧及熔滴行为的影响。试验结果表明:焊接过程中的实际热源间距受到焊接电流大小的影响,且当其在2 mm时焊接效果最优;在导电通道中的带电粒子在运动过程中扰动、漂移以及熔滴过渡模式、焊接模式的改变造成了焊接过程中电弧电流及电压波形的紊乱;激光功率影响了熔滴行为,当采用160 A和180 A的焊接电流时,激光功率的增加导致熔滴过渡频率先减小后增大。     

Influence of longitudinal magnetic field on metal transfer in MIG arc welding

Metal transfer is an important phenomenon in metal inert gas (MIG) arc welding with longitudinal alternating magnetic field. It is of great significance to observe the metal transfer modes under different excitatory currents and frequencies. However, it is very difficult to view the metal transfer process directly during welding, due to the strong interference from the arc light. To obtain the relationship between the metal transfer modes and the different magnetic fields, a high-speed video camera was used to acquire the images of globules. Different metal transfer modes under the conditions of different magnetic fields and welding parameters were studied. The experiment shows clear images of droplet transfer as well as influence of longitudinal magnetic field on both metal transfer and globule shape.     

Influence of nozzle orifice diameter in keyhole plasma arc welding

Abstract

Keyhole welding with the plasma arc welding process occurs when the engineered nozzle and the plasma gas flowrate impart the arc pressure and heat distribution necessary for the formation of a keyhole weld pool. Experimental investigations were conducted to determine the influence of nozzle orifice diameter on weld width and weld stability for a range of substrate thicknesses in Ti-6Al-4V. The experimental results are compared with a semianalytical heat flow model. Both the experimental results and the semianalytical model show that the nozzle orifice diameter can significantly influence the top width and penetration for a given parameter set, particularly in relatively thin substrates.     

焊接电流对微弧等离子焊接修复2Cr13叶片接头组织的影响

为使焊接修复的叶片获得理想的接头组织和性能,利用微弧等离子焊接方法对预制缺口的2Cr13叶片采用ER410焊丝进行焊接修复。通过对比不同的电流大小和焊接方法对接头焊缝组织、热影响区宽度及显微硬度的影响,结果表明:当焊接电流大于45 A时,高温回火后的接头组织全为回火索氏体,显微硬度比母材稍高约20 HV10;但焊接电流小于45 A时,焊缝组织中残留大量的δ铁素体,显微硬度显著降低。残留大量δ铁素体是由于焊缝金属中铬当量与镍当量配比不当,且冷却过快,而δ铁素体未来得及相变直接保留至室温。     

多丝埋弧焊工艺条件对热源参数的影响

为获得多丝埋弧焊的不同电流、电压情况下的热源模型参数,对双椭球热源模型进行了改写.采用有限元的方法,考虑了双丝焊的电弧偏转,对多丝埋弧焊的温度场与热循环进行了计算.结合有限元模拟结果和试验测量结果,通过模式搜索法对不同工艺参数条件下的双椭球模型参数进行了反演计算,获得了双椭球热源模型参数的变化规律.对特定工艺情况以及三...     

窄坡口MAG焊摆动宽度对电弧行为特性的影响

以窄坡口焊枪摆动数学模型和焊丝熔化模型为基础,建立窄坡口MAG焊枪摆动系统的电弧长度数学模型。进行射流过渡和短路过渡条件下不同焊枪摆动宽度的焊接试验。通过高速摄像系统得到电弧和熔滴图像,分析焊枪摆动宽度对电弧和熔滴过渡的影响。利用建立的数学模型模拟电流、电压和弧长随时间变化的规律,对焊枪摆动宽度为3 mm时的短路过渡焊接试验中的电弧和熔滴现象进行理论解释。研究发现,在侧间距(焊丝到侧壁的距离)为0~0.5 mm时,电弧燃烧稳定,熔滴过渡平稳,焊缝质量良好。     

手工电弧焊电压控制的研究

手工电弧焊的电弧电压是一个难以控制的参数，有时能对焊接质量产生较大影响。当电弧电压高于设定值时，通过焊接电源外特性曲线的转换，使电流从焊接电源跳变到较小电流，由此通知操作者去调节弧长，从而把电弧电压维持在设定值之下。     

A numerical model of wire melting rate in variable-polarity submerged arc welding

Based on the pre-existing wire melting rate model of direct-current submerged arc welding （ DC-SAW） , a new numerical model of wire melting rate was developed for variable-polarity submerged are welding （VP-SAW） by accounting for the combined effects of duty cycle β and offset α. The experimental measurements are in a good agreement with the results calculated by this new wire melting rate model, with the maximum discrepancy being less than 10%. Therefore it is evident that this new numerical model can successfully describe the dependence of wire melting rate on the duty cycle β and offset α.