三电极高速CO_2焊焊接速度和焊接电流对焊缝成形影响

MAG角焊焊接在大型船舶制造中占有重要地位,目前应用最为广泛的是双电极角焊工艺,最大焊接速度为1.2m/min.为了提高焊接速度,进而提高焊接效率,研究了焊接速度可达1.8m/min的三电极高速CO2气保护角焊工艺.实验表明:采用DCEP/DCEN/DCEP极性组合的三电极CO2气保护角焊焊接过程稳定,成形良好,角焊焊缝上脚长、下脚长以及熔深均随着焊接速度的增大而减小,随着三电极焊接电流规范组合的增大而增大.在试验基础上,给出了焊接速度和三电极电流规范组合影响下的角焊缝脚长范围预测.     

AC MIG与DC MIG焊接工艺及控制的分析

比较分析了DCEP P MIG焊与DCEN MIG焊的焊接现象,在此基础上,解释了研究开发AC P MIG焊的意义。AC P MIG焊克服了DCEP MIG焊时容易产生的磁偏吹现象,且比DCEP P MIG焊的焊丝熔化速度快、焊缝熔深浅。AC P MIG焊有多种电流模式,其交流电流负极性比率AC I EN％主要用于控制焊缝熔深,其交流电流正极性脉冲Ip主要用于控制熔滴过渡,最理想的是1周1脉1滴的熔滴过渡形式。根据有关的研究表明,在相同送丝速度的条件下,AC P MIG焊的焊缝熔深随AC I EN％增加而减小,焊缝表面光泽好,焊丝熔化金属热含量低等,这些特点最适宜用于焊接薄板。     

VPTIG焊接电流参数对电弧形态及焊缝质量的影响

采用高速录像系统、记忆示波器同步实时采集变极性氩弧（VFFIG）焊接电流、电弧形态信息,比较分析了VFFIG焊接电流频率、直流电极接负（DCEN）时间和直流电极接正（DCEP）时间、DCEN及DCEP电流幅值5个参数对电弧形态及焊缝质量的影响。结果表明,通过调节以上5个参数,可以控制电弧形态、电弧力及焊接热输入,从而控制熔深及焊缝正反面成形;控制焊缝两侧清理区宽度;减少钨极烧损。采用平板对接低频脉冲调制铝合金VFFIG焊接工艺,单道焊熔深可达6min,焊缝成形良好、质量可靠。     

三电极高速CO_2双边角焊质量及稳定性分析

对三电极高速CO2双边角焊焊接工艺进行研究,通过LabVIEW电信号采集与高速摄影分析了焊接质量及过程稳定性.结果表明,焊接中引导电流应为最大,且引导焊枪与中间焊枪之间电流差距100A左右可获得理想的焊缝成形,中间焊枪与跟随焊枪的电流差距大小对焊接质量无明显影响,且焊枪指向位置在底板为宜.在同一工艺时,随着焊接速度增大,焊接过程变得不稳定,同一焊接速度时,试验电流400/300/300A组合时焊接过程最稳定.大电流组合时,应增大焊丝之间距离以减小电弧之间的干扰.     

送丝速度对三丝间接电弧焊稳定性及焊缝成形的影响

三丝间接电弧焊是一种新型的间接电弧焊方法,由2个焊接电源和3根焊丝组成,工件不连接电源,电弧建立在焊丝之间。3根熔化极焊丝对于建立稳定的焊接过程提出巨大挑战,确定稳定的焊接工艺参数区间十分必要。文中主要分析了送丝速度对电弧稳定性以及焊缝成形的影响,确定了稳定的焊接参数区间。研究表明,焊丝的送丝速度与熔化速度相匹配时可建立稳定的间接电弧;在稳定送丝速度区间,送丝速度的变化对焊接工艺参数波动影响较小,随着送丝速度的提高,电弧摆动范围减小,焊缝熔深增加。     

三丝焊接参数对电弧稳定性的影响研究

多丝焊接过程稳定性是评定焊接质量的重要指标之一。本文基于三丝焊接试验平台,利用Lab VIEW软件采集不同焊接参数条件下的引导电弧、中间电弧和跟随电弧的电流电压值,定性地观察焊接过程稳定性。为了定量地评定焊接稳定性,利用变异系数表征各个电弧的波动范围。通过对电弧电压的变异系数进行统计计算,得到在焊接电流组合试验中,跟随电弧的变异系数波动范围最大,焊接过程最不稳定;而在焊丝距离试验中,中间电弧的变异系数波动范围最大。当固定引导焊丝和中间焊丝距离时,中间电弧的稳定性随着中间焊丝和跟随焊丝距离的增大而变好,而引导电弧和跟随电弧的稳定性变化规律并不明显。     

单电源双丝焊接应用及其工艺分析

介绍和分析了单电源双丝系统(DeepenTwin)构成、焊接应用价值、焊接工艺试验以及实际焊接应用.单电源双丝焊接系统由焊接电源、双丝送丝机以及双丝焊枪组成,系统简单,便于操作,既可用于手工焊也可用于专机和机器人的自动焊接.单电源双丝焊接系统能够实现单双丝的自由切换,既能进行单丝的打底焊接也能进行双丝大电流高熔覆率的焊接,最高熔覆效率较单丝焊接可提升50％.由于两根焊丝形成了较宽的单一电弧,电弧热量分布更均匀,焊缝不易咬边,并且不存在电弧干扰的问题,焊接飞溅低成形好,可获得比单丝焊接质量更高的焊缝,是一种新型的高速高效焊接解决方案.     

SAW高速焊接焊丝和焊剂国产化替代的开发研究

卧式埋弧焊机高速焊接使用的焊丝和焊剂进行国产化替代,并在此基础上使用气保焊焊丝代替埋弧焊焊丝进行焊接,获得了成功。通过实践、理化试验相关金相证明,该焊接新工艺是可靠的。探索出的一条适合该卧式高速焊接的焊接工艺即ER50-6+SJ101的焊接新工艺,与旧工艺相比,新工艺应用广泛、取材广,应用价值和经济性更好。新工艺已经成熟,焊接质量稳定,焊接速度满足生产要求,焊接成本也大幅度下降,经济效益可观。     

焊接工艺参数对仰焊MAG堆焊成形的影响

以ER50-6碳钢焊丝作为堆焊焊丝,在Q235B基板上进行仰焊MAG堆焊试验。通过单因素法研究了送丝速度、焊接速度和焊丝伸出长度3个主要焊接工艺参数对仰焊单道焊缝熔宽和余高的影响,分析了不同焊接工艺参数下焊缝出现驼峰缺陷的原因。基于此,对仰焊单道多层堆焊提出了堆焊策略,即减小热输入、减少熔池冷却时间和熔池扰动。在此基础上,进行了仰焊单道多层连续堆焊10层成形,并进行了拉伸测试。结果表明,在送丝速度3.5 m/min、焊接速度0.25 m/min、焊丝伸出长度6 mm的焊接工艺参数下,成形质量相对稳定,抗拉强度达到518 MPa,能满足一些对精度要求不高的零件的使用要求,验证了所提出的仰焊单道多层堆焊策略的可行性,为仰焊堆焊成形零件焊接工艺参数的选择提供了参考。     

三电极MAG高速角焊焊接工艺实验研究

在实际船厂的角焊焊接工艺应用中,多电极焊接工艺主要集中于双电极MAG焊接,焊速最大目前可以达到1.2m/min.为了进一步提高焊接速度,本文采用焊速可达1.8m/min的三电极高速弧焊角焊明弧焊接工艺,进行了焊接规范组合与空间位置实验.实验表明:焊接线能量相近时,焊缝成形参数均在一定范嗣内波动.焊接参数对焊接过程的稳定性影响显著,不同的焊接规范组合时,PNP极性组合的稳定性比NPN的稳定性差;焊枪倾斜角度随着角度的增大稳定性变差;焊丝距离在20和45mm时稳定性最差,而在其范围之间的焊接稳定性随着距离的增大而变好;夹角在20°和50°时稳定性较好.     

三电极高速CO2双边角焊工艺参数对焊缝成形影响

在传统双电极角焊焊接工艺基础上,为了进一步提高焊接效率,采用三电极高速CO2双边角焊工艺,分析不同焊接工艺参数对焊缝成形参数的影响.结果表明,采用不同极性组合的焊缝成形参数差别不大;随着速度的减慢和焊接工艺参数的增大,脚长、熔深和熔宽均呈增大趋势,但焊脚长度有一个最大值限制.下脚长、上脚长受中间焊枪的指向位置影响更为明显,当左右两侧焊枪对中时,脚长最小.另外,随着焊丝之间距离的增大,脚长和熔宽逐渐减小,余高随焊丝距离增大而增大,但差别不大.     

焊接极性对水下高压干法GMAW影响分析

通过环境压力为0.1~2.0 MPa的水下高压干法熔化极气体保护焊(GMAW)试验,比较了直流反接与直流正接焊接过程特点.结果表明,直流反接时,当压力超过0.2 MPa后开始出现少量飞溅,随着环境压力增加,飞溅数量逐渐增多而尺寸逐渐减小.直流正接时,当环境压力大于0.4 MPa后,焊接过程稳定,几乎无飞溅产生.通过高速摄像分析总结了直流反接产生两种飞溅形式及其特征.熔滴偏离型飞溅是伴随着排斥过渡产生的;熔滴反弹型飞溅是由于熔滴接触母材后受向上方向电磁力作用,脱离母材而产生的,并分析了直流正接时飞溅较小的原因.     

极性对全位置自保护耐磨堆焊药芯焊丝工艺性能的影响

通过采集的焊接电流波形图、焊接电流概率密度分布曲线图和焊接电流变异系数评判了不同极性焊接时的电弧稳定性,结果表明,AP-55焊丝直流正接的电弧稳定性优于直流反接;通过飞溅率测试试验对比了不同极性焊接时的飞溅情况,结果表明,AP-55焊丝直流正接的飞溅小于直流反接,且直流正接的飞溅颗粒较小,容易清理。     

Effects of torch configuration and welding current on weld bead formation in high speed tandem pulsed gas metal arc welding of steel sheets

Abstract

Undercut and humping bead are the common defects that limit the maximum welding speed of tandem pulsed gas metal arc (GMA) welding. In order to increase the maximum welding speed, effects of the inclination angle, interwire distance and welding current ratio between the leading wire and trailing wire on bead formation in high speed welding are investigated. The undercut and humping bead is attributed to the irregular flow of molten metal towards the rear part of the weld pool. This irregular flow can be prevented by the trailing wire with a push angle from 5° to 13° , which provides an appropriate component of arc force in the welding direction. The irregular flow is also related to the distance between the leading wire and the trailing wire, and the flow becomes regular when the distance is in the range 9–12 mm. Moreover, the stabilisation of the bulge of the weld pool between the two wires, the presence of enough molten metal below the trailing arc, and the reduced velocity of molten metal flow towards the rear part of the weld pool, are essential to increase the maximum welding speed. These conditions can be obtained by adjusting the ratio of the leading arc current to the trailing arc current. A maximum welding speed as high as 4–4·5 m min^?1 is achieved by setting the current ratio to a value ranging from 0·31 to 0·5.     

Influence of process variables on weld bead quality in two wire tandem submerged arc welding of HSLA steel

Two-wire tandem submerged arc welding process involves simultaneous depositions from two electrode wires with the leading wire usually connected to a DC power source and the trailing wire connected to a pulsed AC power source. The weld bead profile and mechanical properties in the tandem submerged welding are significantly affected by the leading and trailing wire current transients and the welding speed. We present here a detailed experimental study on the influence of leading wire current, trailing wire current pulses, and welding speed on the weld bead dimensions and mechanical properties in single-pass tandem submerged welding of a typical HSLA steel. It is realized that the weld bead penetration is primarily influenced by the leading wire current while the weld bead width and the reinforcement height are sensitive to the trailing wire current pulses. Greater magnitude of trailing wire current pulses and shorter negative pulse duration increase the weld pool volume leading to reduced cooling rate and poor mechanical properties as the formation of the strengthening phases like acicular ferrite is inhibited. In contrast, increase in welding speed reduces the rate of heat input thereby enhancing the cooling rate and the weld bead mechanical properties. A set of empirical relations are developed to estimate the weld bead dimensions and mechanical properties as function of the welding conditions. The predictions from the empirical relations and the corresponding measured results are observed to be in fair agreement.     

Research on laser-arc hybrid welding of lap fillet joints of thin sheet

ABSTRACT

Laser welding is capable of welding at high speeds by high-density energy, while arc welding is an effective construction method from the viewpoint of tolerance of the gap and welding position. Laser-arc hybrid welding has both these features. The authors have researched suitable welding parameters and consumables for this hybrid welding process that couples laser beam with MAG arc for lap fillet weld joining of thin steel sheets. As a result, the following welding parameters have been proven to be the most appropriate for better bead shapes and root-gap tolerance, i.e. laser leading (kept at a right angle) and MAG trailing (kept at a push angle); the laser-arc distance was 3 mm and the laser beam focus size was 2 mm. In addition, it was proven that HT490-class welding wire of Si-Mn-Ti type (JIS YGW11) was the most appropriate for better bead shapes and root-gap tolerance. The bead shape was apt to be better in cases of higher surface tension of welding wire. The result of the tensile shear test of the joint by welding with HT490-class welding wire of Si-Mn-Ti type (JIS YGW11) under selected welding condition demonstrated that the value of the tensile strength of parent material was equal to that of lab fillet joints.     

立向角焊缝一次成形自动焊接技术

研究了立向角焊缝的一次成形自动焊接关键技术,包括:一套使焊点熔池上升速度与焊接小车上行速度匹配协调的自动控制系统;适应角缝焊接并能对焊缝强制冷却成形的特殊水冷滑块;一套能使焊枪和水冷滑块在水平面内进行转角调整的调整机构。借助于气电立焊技术对其创新,实现了立向角焊缝的一次成形自动焊接,填补了此项技术的空白。