TIG-MIG复合焊电弧间相互作用对焊接过程的影响

根据毕奥-萨伐尔定律,对惰性气体钨极保护-熔化极惰性气体保护(Tungsten inert gas-metal inert gas,TIG-MIG)复合焊TIG-MIG电弧间相互作用模型进行改进;结合不同倾斜电弧下电流密度分布的自适应模型,建立TIG-MIG复合焊的电弧力-热模型。对不同焊接电流下TIG-MIG复合焊电弧倾角展开计算,分析复合焊电弧间相互作用力对工件上热流密度分布和焊缝成形的影响,发现两电弧之间存在的排斥力能够增加TIG电弧的垂直度,从而提高TIG电弧热流密度,同时MIG电弧是影响TIG-MIG复合焊焊缝成形的主要因素。研究复合焊焊枪间距和两焊枪的前后位置对焊接过程的影响,发现TIG焊枪在前、MIG焊枪在后的方式更有利于焊接过程稳定。计算结果与试验结果的对比表明,所建立的模型能够较好地描述TIG-MIG复合焊接物理过程,这对优化其焊接工艺参数具有一定的指导意义和实际应用价值。     

活性剂增加铝合金交流FZ-TIG焊熔深机理

针对铝合金材料提出一种新型活性TIG焊,即分区活性TIG(FZ-TIG)焊,可同时保证焊缝熔深显著增加和焊缝成形良好.利用氦气保护钨极电弧焊观察电弧行为变化,通过分析电弧电压随弧长的变化规律研究活性剂影响电弧的方式,采用焊缝偏移试验分析活性剂对导电通道电阻的影响,进行焊缝表面焊渣X射线衍射分析和热力学计算,分析活性剂与表面氧化膜或熔池金属之间可能的化学反应.通过以上试验研究铝合金交流FZ-TIG焊中活性剂增加熔深的机理,得出活性剂强烈收缩电弧弧根和弧柱是SiO2+FZ108活性剂增加铝合金交流FZ-TIG焊熔深的主要机理.     

横向磁场对TIG焊不锈钢焊缝成形影响

增大钨极氩弧焊的焊速可以提高生产率,但由此而产生的电弧弧柱过度后傾和阳级斑点滞后使焊缝咬肉严重、成形不良,利用外加横向磁场作用在电弧上,能有效地控制电弧弧柱的后倾程度,改善焊缝成形并使熔深有所增加。     

厚板硬铝合金焊接工艺设计和接头分析

本课题研究并制定了10mm厚板硬铝合金的TIG焊与A-TIG焊的焊接工艺,并对TIG焊与A-TIG焊在不同电流条件下的焊接接头进行了分析。本文着重研究了当采用TIG焊和活性化钨极氩弧焊(A-TIG)方法焊接厚板硬铝合金时,焊接电流的变化对组织及焊缝成形的影响,以及活性剂的加入对提高厚板硬铝合金熔深和金相组织的影响。     

薄壁不锈钢管列置双TIG电弧高速焊接工艺

单钨极惰性气体保护焊(Tungsten inert gas,TIG)是目前工业用薄壁不锈钢管主要生产工艺,但其存在生产效率低的问题。针对高速TIG焊出现的驼峰焊道、咬边等焊缝表面成形缺陷产生的原因,提出列置双TIG电弧高效节能焊接新工艺。试验结果表明,采用双TIG电弧高效焊接新工艺,48 mm×1.2 mm和42 mm×1.5 mm两种规格的409L铁素体不锈钢管在获得良好焊缝成形的条件下焊接速度分别可达5.1 m/min和3.2 m/min;与单TIG焊接生产工艺相比,生产效率分别提高了240%和140%,能耗也分别降低44%和29%。两种规格铁素体不锈钢管膨胀率分别达到14.1%和33.7%,高于单TIG电弧焊的11.2%和21.4%,满足生产要求。分析表明,辅助TIG电弧加热主TIG电弧熔池后部堆积的液态金属,从热和力两方面延长熔池存在时间、促使液态金属回流填平主TIG电弧产生的熔池凹陷,从而有效抑制驼峰焊道和咬边的产生,在高速焊接条件下获得良好的焊缝成形,实现薄壁不锈钢管优质高效节能的焊接生产。     

低电流TIG电弧辅助MIG高速焊咬边缺陷抑制机理及措施的研究

基于温度场、流场、熔滴过渡以及电弧形态检测,开展低电流钨极氩弧焊(Tungsten inert gas welding,TIG)辅助熔化极惰性气体保护(Metal inert gas welding,MIG)高速焊工艺试验。从传热、传质以及受力等角度分析低电流TIG辅助电弧对高速MIG咬边缺陷的抑制机理,并分析各工艺参数对最终焊缝成形的影响。相比常规MIG高速焊,低电流TIG辅助电弧能有效降低MIG高速焊前部熔池边缘的温度梯度,延长熔池存在时间,促进液态金属向焊缝边缘填充。电弧力和熔滴冲击力是影响高速焊咬边缺陷的主要作用力,低电流TIG辅助电弧对MIG熔滴冲击力改变较小,但两电弧耦合后,电弧静、动压力明显降低,可有效地抑制MIG高速焊中咬边缺陷的产生。此外,正交工艺试验显示,丝-极间距和焊枪倾角是影响复合焊工艺的重要参数,而钨极距工件距离和TIG焊接电流则对咬边缺陷的影响较小,通过对丝-极间距和焊枪倾角的调节能快速实现该复合焊工艺参数的优化,抑制咬边缺陷。     

铝合金变极性TIG焊焊接参数对焊缝形貌的影响

变极性钨极惰性气体保护焊(VP-TIG)在铝合金焊接时涉及大量的工艺参数,文章系统的研究了焊接速度和峰值电流幅值对熔深、熔宽及阴极清理宽度的影响规律。结果表明,随着焊接速度的增大,阴极清理宽度减小、富裕清理宽度变化不显著,且熔宽对焊接速度响应迅速;随着峰值电流的增大,阴极清理宽度与直流钨极接正(DCEP)阶段的电弧最大直径存在正相关关系;对于特定焊接电流参数,可以采用改变焊接速度补偿焊缝形貌。研究结论为单道焊缝形貌控制及后期多道堆焊成形奠定工艺基础。     

活性剂焊接技术的研究

活性剂焊接是近十年来发展起来的增大焊接熔深，改善焊缝成形和焊接质量，提高焊接生产效率的新技术。早期主要集中在A—TIG焊，已在碳钢、不锈钢、高温合金、钛合金的焊接中有了成功的应用，对于铝镁合金的活性剂焊接技术也在研究中。目前研究认为活性剂提高熔深的机理一是活性剂可影响电弧特性，提高电弧的能量密度和作用于熔池的电弧力，二是活性剂影响了熔池的表面张力而提高了焊接熔深，或是2种原因兼而有之。随着A—TIG焊应用的成熟，活性剂焊接拓展到MIG焊、等离子弧焊和激光焊中的应用成为活性剂焊接发展的一个方向，在提高熔深，改善焊缝成形方面有了初步的效果。     

空心钨极中心负压电弧基础特性研究

为了提高传统钨极惰性气体保护(Tungsten inert gas,TIG)焊电弧的能量密度和热源边界的能量梯度,保证焊接热输入均衡,规避输入能量分散,提出空心钨极中心负压电弧焊接方法,设计并构建空心钨极中心负压电弧焊接系统,介绍系统的组成及操作方法。利用高速摄像机拍摄空心钨极中心负压电弧的宏观形态,进行定点焊接烧蚀试验,并对阳极表面熔池尺寸和焊接接头的宏观形貌进行分析。试验结果表明,在电弧自身刚性的作用下,空心钨极中心负压电弧能够稳定地建立于空心钨极和阳极工件之间;与传统TIG焊电弧相比,在宏观形态上,空心钨极中心负压电弧的弧柱沿径向收缩,呈现拘束状,空心钨极的尖端呈现白炽状态;在焊接接头的宏观形貌上,空心钨极中心负压电弧对应焊接接头的熔深大,熔宽小,焊缝成形好。     

TIG和MIG焊在铝镁合金污水处理设备上的应用

我公司为石家庄污水处理厂生产的铝镁合金污水处理设备——刮泥机,是与国外的合作项目,按奥地利标准、图样制造,材料为铝镁合金,由奥地利进口。该设备技术要求高,焊接难度大,必须采用TIG(钨极氩弧焊)和MIG(熔化极氩弧焊)焊。该焊接方法对焊缝保护好,成形美观,电弧热量集中,生产效率高,可完全满足污水处理设备的焊接质量要求。 该设备通过我公司制造,成本是进口设备的     

Gas Pool Coupled Activating TIG Welding Method with Coupling Arc Electrode

Gas pool coupled activating TIG(GPCA?TIG) welding put forward in?house can dramatically enhance weld penetration of TIG welding through introducing active element oxygen to reverse the Marangoni convection flow in the molten pool. In order to further improve the welding productivity, the normal solid tungsten electrode is replaced by a kind of coupling arc electrode. The changes of arc pressure distribution along anode surface and the weld appearance were evaluated. On this basis, the dependences of weld shape characterized with weld depth, width and undercut on the main welding parameters were discussed. The results indicate, the substitution of coupling arc electrode can lead to an obvious decrease of arc pressure. Compared to hollow tungsten electrode and twin tungsten electrodes, the coupling arc electrode is much easier to manufacture and has more compacter structure. Combined with the symmetric distribution of arc pressure in di erent directions, this electrode has extensive adaptability. In the GPCA?TIG welding with coupling arc electrode, both the substitution of coupling arc electrode and the introduction of outer active gas oxygen can reduce the possibilities of producing humping bead and undercut. Their joint action makes this welding method have the capability of realizing high travel speed and deep penetration welding.     

活性剂增加铝合金交流A-TIG焊熔深机理研究

采用多组元活性剂AF305进行铝合金交流A-TIG焊时,熔深达到传统TIG焊的3倍以上。进行了交流、直流正接和直流反接A-TIG焊,发现极性不同时活性剂对熔深的影响也不同。研究了强制电弧收缩对交流焊熔深的影响,发现弧根整体收缩并不是AF305增加交流A-TIG焊熔深的主要机理,熔深显著增加主要与焊渣成片分布有关。对焊渣进行了SEM形貌观察和EDS成分分析,并采用氦弧焊证实了焊接过程中焊渣在熔池表面成片分布,电弧斑点极大收缩。向AF305活性剂中添加铝粉改变焊渣分布,研究焊渣分布与熔深的关系,证实了焊渣成片分布能增加焊接熔深。认为焊渣成片分布使得电弧斑点极大收缩,斑点压力以及电弧和熔池内的Lorentz力增强,最终焊接熔深显著增加。     

考虑金属蒸汽的定点活性钨极惰性气体保护焊电弧与熔池交互作用三维数值分析

建立包括钨极、电弧和阳极的定点活性钨极惰性气体保护(Activating tungsten inert gas,A-TIG)焊电弧熔池交互作用统一数学模型。通过麦克斯韦方程组、连续性方程、动量守恒方程、能量守恒方程和组分输运方程的耦合求解,得到了电弧和熔池的温度、等离子体运动速度、熔池流动速度、电弧压力、电势、电流密度和金属蒸汽分布等结果。因为在A-TIG焊中,熔池的内向流动造成了大量的热被传入到熔池底部,热量的利用率更高,导致焊接熔池的表面温度比TIG焊的表面温度要高,从而引起了金属蒸汽浓度的增加,所以考虑金属蒸汽的A-TIG焊的电弧等温线较考虑金属蒸汽的TIG焊的电弧等温线有一定程度收缩。结果表明,考虑金属蒸汽对A-TIG焊熔深的模拟结果具有一定的影响,熔深减小约6%,该结果与有关试验研究结果吻合良好。     

Study of mechanism of activating flux increasing weld penetration of AC A-TIG welding for aluminum alloy

When multi-component flux AF305 is used as surface activating flux for an aluminum alloy, the weld penetration of activating flux-tungsten inert-gas (A-TIG) welding is over two times more than that of conventional TIG welding. Using A-TIG welding with the modes of alternating current (AC), direct current electrode negative (DCEN) and direct current electrode positive (DCEP), respectively, the flux differently affects weld penetration when the polarity is different. After studied the effect of compelled arc constriction on weld penetration of AC welding, it is believed that the constriction of the whole arc root is not the main mechanism that flux AF305 dramatically improves weld penetration. The penetration has a relationship with the separate distribution of slag on the weld surface. Then, an observation of scanning electron microscopy (SEM) and an electronic data systems (EDS) analysis of slag were performed respectively. The separate distribution of slag on the weld pool during welding and the great constriction of arc spots were confirmed by TIG welding with helium shielding gas. The relationship between slag distribution and weld penetration was studied by adding aluminum powder into flux AF305 to change the distribution of slag. During welding, the separate distribution of slag on the weld pool results in the great constriction of arc spots, an increase in arc spot force, and an increase in Lorentz force within the arc and weld pool. Finally, the weld penetration is increased. __________ Translated from Chinese Journal of Mechanical Engineering, 2006, 42(5): 45–49 [译自: 机械工程学报]     

Optimisation of the weld bead geometry in gas tungsten arc welding by the Taguchi method

In this paper, determination of the welding process parameters for obtaining an optimal weld bead geometry in gas tungsten arc welding is presented. The Taguchi method is used to formulate the experimental layout, to analyse the effect of each welding process parameter on the weld bead geometry, and to predict the optimal setting for each welding process parameter. Experimental results are presented to explain the proposed approach.     

Mathematical models for control of weld bead penetration in the GMAW process

This paper presents the effects of welding process parameters on weld bead penetration for the gas metal arc welding (GMAW) process. Welding process parameters included wire diameter, gas flow rate, welding speed, arc current and welding voltage. The experimental results have shown that weld bead penetration increased as wire diameter, arc current and welding voltage increased, whereas an increase in welding speed was found to decrease the weld bead penetration. However, the weld bead penetration is not affected significantly by gas flow rate changes. Mathematical equations for study of the relationship between welding process parameters and weld bead penetration have also been computed by employing a standard statistical package program, SAS.     

Obtaining weld pool vision information during aluminium alloy TIG welding

An image sensing system for the TIG (tungsten inert-gas arc) welding process of aluminium alloy was established. The relationships between the image sensing system and the characteristic of welding current were discussed in detail. Front and back images of the weld pool were obtained with different welding parameters. In order to process the image, the characteristics of an aluminium alloy were analysed. Image processing and pattern recognition were first used to obtain information from the TIG welding process for aluminium alloy. The image of the weld pool was pre-processed using a series of methods: a weighted median filter, a statistical threshold by expectation and the projection method. A neural network method was used to extract the edge of the images of the weld pool. The result of detecting the edge with a BP neural network were excellent. The symmetry of the weld pool for aluminium alloy was studied when the welding current is large. The edge of the image of the whole weld pool is obtained in a single side image and an accurate method for measuring the weld pool geometry parameter is provided. Experiments show that using the image sensing to control the TIG weld width for aluminium alloy is an effective method.     

Fuzzy pattern recognition of tungsten inert gas weld quality

In this paper, a fuzzy pattern recognition technique is applied to classifying aluminium weld quality in tungsten inert gas (TIG) welding. The pattern vector includes three components, that is, the front height, the back height, and the front width of weld. Based on the values of the pattern vector, good, fair, and poor weld qualities can be automatically classified by using the fuzzy pattern recognition technique. Experimental results under different welding parameters are presented to illustrate the proposed method.     

飞机起落架的TIG焊接工艺研究

对用手工鸽极氩弧焊（TIG焊）代替目前航空部队采用的手工电弧焊（SMAW焊）焊修飞机起落架进行了初步探讨，经试验得出了TIG焊最佳焊接工艺参数。在改进焊接方法与工艺上进行了初步尝试，采取TIG焊代替SMAW焊，工艺简便、快速，焊接效果比较理想。该工艺的应用与推广，对于我军野外现场抢修具有显著的军事、经济效益。     

低功率激光诱导电弧复合焊接钛合金薄板工艺研究

采用低功率脉冲YAG激光诱导非熔化极惰性气体保护(Tungsten inert gas,TIG)焊电弧复合热源实现了1 mm厚TC4钛合金薄板的优质焊接,研究激光诱导电弧复合焊接过程中热源能量匹配、热源间角度、对接间隙对焊缝成形的影响规律。结果表明,钛合金薄板低功率脉冲YAG激光诱导TIG电弧复合热源焊接过程中,激光能量与电弧能量之间的相互匹配将显著影响焊缝的表面成形。相对于电弧功率的变化,焊缝成形对激光功率变化的敏感度更高。随着热源间角度减小,激光诱导电弧复合热源传热能力增强;由于复合焊接速度快、热输入小、焊接试板横向变形小,当对接间隙为0~0.5 mm范围内时均能获得良好的焊缝成形。为了使焊缝成形均匀连续,焊接过程中需要对焊缝背面采用氩气进行保护,当保护气体流量为5~8L/min时获得最佳焊接接头。