双热丝MAG焊接设备及工艺

双热丝MAG焊接技术(Double Hot Wires MAG Welding Technology)是一种高效焊接方法。在焊接过程中有一根主焊丝和两根热丝。主焊丝和母材之间产生主弧,热丝加热电源的两个输出端子分别与两根焊丝连接,经焊接熔池构成闭合回路。该工艺采用电阻热预热焊丝,利用熔池的能量最终熔化焊丝,在增大熔敷效率的同时,有效降低焊接热输入。研究热丝电流I_(res)对焊丝熔敷速率的影响规律,并进行厚板的多层摆动焊接。结果表明,随着I_(res)的增大,焊丝熔化速度增大,并且每一个热丝电流对应一个最佳热丝送丝速度范围,最大熔敷速度可达25 kg/h以上,有效提高了焊接效率。     

铝合金Plasma-GMAW-P复合焊接电弧特性及熔滴过渡行为

研究了Plasma-GMAW复合焊接过程中的电弧特性以及熔滴过渡行为。结果表明,不同电流的等离子弧通过改变GMAW电弧的导电以及受力状态来影响GMAW电弧形态以及熔滴过渡行为。等离子弧电流较小时,GMAW电弧的等离子流效应对GMAW电弧形态影响显著,基值时期的GMAW电弧基本沿焊丝轴线燃弧,峰值时期由于在焊接方向上同时受到方向相反的2个力而被压缩,熔滴所受的等离子流力以及等离子流力垂直向下的分力因此增加,对熔滴过渡的促进作用增强,熔滴更易从焊丝脱落。等离子弧电流增加,氛围中金属蒸气增多,电荷流效应对GMAW电弧的影响增强,基值时期GMAW电弧偏向等离子弧方向燃弧,由于焊接电弧存在热惯性,MIG电弧在峰值时仍偏向等离子弧,熔滴所受等离子流力垂直向下的分力因此减小,熔滴脱离焊丝的时间增加。     

焊丝预热减少热输入并将焊缝金属稀释降至最低

威斯汀豪斯研究与开发机构开发了先进的GMAW(气体保护金属极电弧焊),是GMAW的一种改进型。该工艺在GMAW焊枪的标准电极头上方增设一个接触管头,并通以交流电。新增加的电流回路能够将焊丝预热并提高熔敷效率,无需采用常规的方法增大焊接电流或增加焊丝伸出长度。由詹姆斯·F·林肯弧焊基金会出版的“焊接革新季刊”第6卷第1期对该工艺进行     

采用填充焊丝的外加电流铝合金CO2激光焊接

在铝合金CO2激光焊接时,通过填充焊丝向焊接熔池注入外加电流,直流电源的一极与填充焊丝相连,另一极在熔池后方与工件相连,由此构成电流回路.研究结果表明,随着外加电流的增加,焊缝熔深和面积增大,且焊缝表面成形更加均匀,鱼磷纹更加细密,即外加电流提高了焊接效率,改善了焊接过程的稳定性.进一步研究表明,外加电流的电阻热对焊接结果的影响极小.外加电流对铝合金CO2激光焊接的影响归因于电流的磁流体效应.     

铝合金液态填充焊的工艺特性分析

采用高速摄像和工艺试验相结合的方法分析了液态填充焊的影响因素,进行了焊接接头质量分析.结果表明,激光液态填充焊有两种填充模式:焊丝半熔态、焊丝全熔态.焊接电流较小时,焊丝为半熔态,液态填材顺焊丝流向熔池;焊接电流较大时,焊丝为全熔态,依靠间隙的毛细作用,能稳定的流入熔池中.随着焊接速度的提高匙孔距熔池边缘的距离变小.为了使液态填材稳定的过渡到熔池中,光丝间距应控制在-0.5~2.0 mm范围内.经过接头质量分析发现:与激光填丝焊相比,液态填充焊接焊缝中的气孔率明显降低.     

空心钨极同轴填丝焊空间热场分布特征

利用理论建模与试验相结合的方法,系统研究了空心钨极同轴送丝焊接过程中焊丝熔化热量的来源. 结果表明,基于磁流体力学的理论模型分析结果和实际情况高度吻合;在高温电弧热辐射及钨极热传导共同作用下,钨极内孔形成的梯度式高温区会对焊丝起到一定的预热作用;环状空心钨极电弧中轴线上近几何中心区域的温度最高,焊接电流400 A时温度高达13 700 K;熔滴与液态熔池接触后电势相等,在最小电压原理作用下,部分高温电弧的阳极作用区会由液态熔池转变至焊丝表面,同时部分焊接电流会从焊丝流过,形成的电阻热也是高效熔丝的主要原因之一;熔滴过渡分析结果表明空心钨极同轴填丝焊接具有较高的工艺稳定性,是一种极具发展前景的焊接新方法.     

电弧热丝TIG焊工艺特点分析

介绍了一种电弧热丝TIG焊方法，在焊接时采用电弧对紫铜焊丝进行预热后，再将焊丝堆焊在20钢板上，焊接时在保证焊接电弧能量不变的同时，分别考查了焊丝温度升高与热丝电流之间的关系；焊丝温度升高与送丝速度之间的关系。试验表明，焊丝的温度随热丝电流的升高而升高，随送丝速度的升高而降低。并证实了热丝焊接技术可以提高钨极氩弧焊在堆焊时的熔敷速度，是一种高效的堆焊方法。     

TIG电弧热丝对铜、钢堆焊的工艺研究

针对某产品铜带焊接工艺,提出了一种电弧热丝方式应用于TIG堆焊铜、钢工艺的研究。电弧热丝可有效预热低电阻率的焊接材料,如铜;传统的电阻热丝只能加热具有高电阻率的焊接材料,如钢。采用电弧热丝系统,热丝电流小于50A时即可有效预热焊丝,与电阻热丝电流400A相当。在相同焊接电流下,能够大大提高焊接熔敷速度;在相同送丝速度下,降低焊接电流,大大降低焊接设备功率。同时证明2种热丝加热方式对钢基体、铜合金的影响相同,特别是对堆焊层铜合金中泛铁量的影响相当。     

高效多丝熔化极气体保护焊(GMAW)工艺的研究现状及进展

随着全球制造业竞争的日益激烈,我国提出了“中国制造2025”制造强国战略,其重点发展的十大领域中,与焊接技术密切相关的就高达八个,不仅极大地推动了焊接技术的革新发展,而且对焊接效率和质量均提出了更高的要求。由于熔化极气体保护焊(Gas metal arc welding, GMAW)易于实现自动化焊接,具有生产效率高、焊接质量好及位置适应性好等优点,所以广泛应用于机械制造业中。实现高效GMAW的主要途径有提高焊接速度以及焊接熔敷率。针对以上两种途径,国内外焊接工作者在双丝GMAW的基础上,引入了第三根甚至多根焊丝,研发了各种多丝GMAW工艺。本文针对国内外研发的各类多丝GMAW工艺进行了分析,重点介绍了多丝GMAW工艺的焊接原理、工艺特点及其应用,通过上述分析对各类多丝GMAW工艺进行归纳总结,并进一步展望了多丝焊接的发展方向,即多丝GMAW工艺亟需在电弧物理理论、设备开发和新焊材研发等方面展开深入的研究工作。     

伊萨ICETM集成冷丝埋弧焊

ICE (integrated cold electrode)集成冷丝埋弧焊是在双丝埋弧焊的基础上增加了一根不导电的焊丝(冷丝),冷丝置于同一个导电嘴中的两根平行的导电焊丝(热丝)中间,利用导电焊丝在焊接过程中产生的电弧热量熔化冷丝,在无需额外增加焊接热输入的情况下达到显著提高焊接熔敷率的埋弧焊接方法.通过伊萨专利技术的控制软件在控制系统中设定冷丝送丝比率以达到与热丝送丝速度的有效匹配,保证焊接过程的稳定性.焊接过程的稳定还得益于伊萨ICE焊枪的设计,即使干伸长度和弧长发生变化也能保证冷丝的熔化点始终在电弧的包围中.ICE具有焊接熔敷率高、焊剂消耗量少、节能环保、焊道成型易控等特点.     

Prediction of dilution in GMA and UGMA stainless steel single layer cladding using response surface methodology

Abstract

This paper describes the use of a variant of GMAW process named as UGMAW (universal gas metal arc welding) process for single layer stainless steel cladding, which makes use of a specially designed torch to preheat the filler wire, using an auxiliary welding power source, before its emergence from the torch. The experimental work undertaken was that of single layer cladding of 12 mm thick low carbon steel with the austenitic stainless steel 316L solid filler wire of 1·14 mm diameter. Dependence of dilution was investigated using four factor five level central composite rotatable design to develop relationship for predicting dilution, which enables to quantify the direct and interactive effects of four numerical factors, namely, wire feed rate, open circuit voltage (OCV), welding speed, electrode stickout and one categorical factor, preheat current. External preheating of the filler wire in UGMAW process resulted in greater contribution of arc energy by resistive heating owing to which significant drop in the main welding current and hence low dilution values were observed. Numerical optimisation was carried out and the optimal solutions generated indicate that for same levels of dilution, higher deposition rates are achievable in UGMAW process, thus making it a good choice for low cost surfacing applications.     

Effect of Auxiliary Preheating of the Filler Wire on Quality of Gas Metal Arc Stainless Steel Claddings

Weld cladding is a process for producing surfaces with good corrosion resistant properties by means of depositing/laying of stainless steels on low-carbon steel components with an objective of achieving maximum economy and enhanced life. The aim of the work presented here was to investigate the effect of auxiliary preheating of the solid filler wire in mechanized gas metal arc welding (GMAW) process (by using a specially designed torch to preheat the filler wire independently, before its emergence from the torch) on the quality of the as-welded single layer stainless steel overlays. External preheating of the filler wire resulted in greater contribution of arc energy by resistive heating due to which significant drop in the main welding current values and hence low dilution levels were observed. Metallurgical aspects of the as welded overlays such as chemistry, ferrite content, and modes of solidification were studied to evaluate their suitability for service and it was found that claddings obtained through the preheating arrangement, besides higher ferrite content, possessed higher content of chromium, nickel, and molybdenum and lower content of carbon as compared to conventional GMAW claddings, thereby giving overlays with superior mechanical and corrosion resistance properties. The findings of this study not only establish the technical superiority of the new process, but also, owing to its productivity-enhanced features, justify its use for low-cost surfacing applications.     

Welding current prediction in GMAW and UGMAW processes using response surface methodology

Abstract

Among all process variables in gas metal arc welding (GMAW) process, welding current is the most influential variable affecting heat input and weld quality. Its dependence on other process variables in GMAW and universal gas metal arc welding (UGMAW) processes (which makes use of a specially designed torch to preheat the filler wire independently, before its emergence from the torch) has been investigated using four factor five level central composite rotatable design to develop relationship for predicting welding current, which enables to quantify the direct and interactive effects of four numeric factors, namely wire feedrate, open circuit voltage, welding speed and electrode stickout and one categorical factor preheat current. Mathematical models developed show that welding current increased linearly with increaseing wire feedrate and open circuit voltage, whereas it decreased with increasing electrode stickout and preheat current. Numerical optimisation was carried out, and the optimal solutions generated indicate that under the same input conditions higher deposition rates are achievable in UGMAW process.     

Pulsed gas metal arc welding of Al–Cu–Li alloy

Abstract

An experimental Al–Cu–Li–Mg–Ag–Zr type alloy in the form of 13.7 mm thick plates was studied for its fusion characteristics using gas metal arc welding (GMAW) and pulsed gas metal arc welding (P-GMAW). High copper 2319 filler of 1.6 mm diameter was used. The burn-off characteristics of 2319 filler wire in GMAW and P-GMAW were experimentally determined, including the relation between pulse current and pulse duration for the desired one-drop detachment per pulse (ODPP) condition and feasible range of pulse parameters. The effect of welding parameters on bead geometry and shape relationships was investigated through beadon-plate experiments in the welding current range above the spray transition current. Reasonably good weld beads were obtained in P-GMAW at currents as low as 194 A and welding speeds of 45 cm min^–1. P-GMAW yielded significantly higher weld penetration compared to GMAW.     

Effects of processing parameters on figuration during the GMAW rapid prototyping process

As a deposition technology, gas metal arc welding （GMAW） has shown new promise for rapid prototyping of metallic parts. During the process of metal forming using the arc of GMA W, low heat input and stable droplet transition are critical to high quality figuration. The effects of various processing parameters on figuration quality were studied in the experiment of GMA W rapid prototyping using the wire of ERSO-6 , including welding voltage, wire feeding rate, welding speed and so on. The optimal parameters for ERSO-6 are obtained. Simultaneously, it is verified that the rapid prototyping parts with favorable structures and quality can be achieved under the conditions of low heat input and stable droplet transition.     

旁路耦合微束等离子弧热特性及焊缝成形特点

针对传统微束等离子弧焊中焊丝熔敷率与焊接电流不能解耦的局限,提出旁路耦合微束等离子弧焊方法.通过给外填焊丝添加一电流,使焊丝与焊枪钨极间产生一个旁路电弧,实现熔化母材热量与熔化焊丝热量的解耦,确保熔化母材电流稳定的同时提高填充焊丝的熔化速度.对旁路耦合微束等离子弧焊的熔敷率、母材热输入及焊缝成形质量进行试验研究.结果表明,该方法既保持了传统微束等离子弧焊的优点,又在提高焊丝熔敷率的同时降低母材的热输入;并在其它焊接参数保持不变时,随旁路电流的增加,焊缝的熔宽、熔深和稀释率减小,余高和成形系数增大.     

Arc heating hot wire assisted arc welding technique for low resistance welding wire

Abstract

An assistant arc was used to preheat the wire for hot wire tungsten inert gas (TIG) welding which was independent on the resistance of the welding wires and avoided the drawbacks of the traditional hot wire preheating method. The new method is suitable for low resistance wire such as copper and aluminium. The experimental results showed that the wire temperature varied linearly with preheating current and hyperbolically with wire feeding speed. The temperature of wires achieved 60% of their melting points when LF6, H90, HS201 and H08Mn2Si welding wires were used at a current less than 50 A. With arc assisted hot wire, the welding deposition efficiency of the HS201 wire was increased by 96% compared with the traditional TIG welding method, while its microstructure was similar to that of the cold wire welding.     

高强合金钢中厚板双丝焊接接头组织性能

针对轻型车辆中厚板高强合金钢高效化焊接特点,基于高效双丝熔化极气体保护焊系统,应用双电弧共熔池熔化极气体保护焊方法,采用奥氏体不锈钢焊丝进行高强合金钢的焊接工艺试验.确定了合适的焊接工艺参数,并对获得的对接接头的显微组织、成分及力学性能进行了分析.结果表明,采用双电弧共熔池熔化极气体保护焊工艺,能够获得良好的中厚板高合金钢焊接接头,力学性能满足使用要求.与焊条电弧焊和单丝电弧焊相比,焊接效率得到较大提高.     

熔化极气体保护焊的直接自适应控制

焊接电流和电弧长度是熔化极气体保护焊(GMAW)焊接过程的主要状态变量,决定了熔滴的过渡过程、热量输入和焊缝成形.文中在分析GAMW焊接工艺过程的基础上,建立了焊接电流和电弧长度的数学模型,采用基于二次型性能指标的直接自适应控制算法,通过调节焊接电源输出电压和送丝速度的大小,使焊接电流和电弧长度能跟踪参考模型的输出.同时,针对实际应用中难以检测的电弧长度,建立了电弧长度估计模型,实现了对电弧长度的软测量.结果表明,该算法可以实现弧长和电流的精确控制.     

软开关双电弧共熔池脉冲GMAW焊装备关键技术

双电弧共熔池脉冲GMAW焊集高速高效、优质和自动化于一体,近来备受重视,但国内对此研究不多.本文在系统分析双丝脉冲GMAW焊电弧形态、熔滴过渡以及熔池行为的基础上,对双电弧共熔池脉冲GMAW焊系统实现的关键问题如电源类型、动特性、外特性、控制模式、协同控制方式、双丝焊枪设计以及送丝系统等进行了较深入的探讨.