共查询到17条相似文献,搜索用时 171 毫秒
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在正面熔化半径RZ和板厚h一定的条件下,基于对有电弧作用的熔透型TIG焊接熔池三维液面行为的分析,获得了不同背面熔化半径RB的熔池三维形状模型,利用有限元分析软件surface evolver进行数值模拟,研究了电弧对熔透型TIG焊接熔池液面的影响.结果表明,电弧的作用与否对熔池下液面的大小和形状无显著的影响;在背面熔化尺寸较小时(RB≤2.5 mm附近),电弧对上液面特征量有较大作用;电弧的作用从整体上是使熔池上液面压低.在从脉冲基值过渡到脉冲峰值期间,电弧电压(或弧光光强)增加的部分是由电流增加和熔池上液面被压低两部分引起的. 相似文献
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通过高速摄像方法研究了钽薄板TIG焊接过程中,保护气体及工艺参数不同时电弧形态的变化规律及其对焊接质量的影响。结果表明:保护气体不同时,电弧形态明显不同。采用TIG焊焊接钽板时使用氦弧能得到更好的焊接质量;当弧长不变,增加焊接电流时,电弧有效作用范围变犬,电弧温度及能量密度高。熔池增大速度较快;当焊接电流不变,弧长增加时,电弧有效加热半径变大,但由于弧长增加而引起电孤热能分散。熔池增长速度较慢,热影响区范围增大。焊接工艺参数的变化时电弧形态的影响规律,对制定钽薄板TIG焊接过程中较为合理的工艺参数具有重要意义。 相似文献
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基于流体动力学方程,采用焓-孔隙度法来处理液-固相变,采用VOF方法追踪熔池自由表面变形,建立了固定电弧下的三维瞬态TIG焊熔池数学模型,求解获得了在浮力、Marangoni力、电磁力和电弧压力单独作用时的熔池表面变形行为及其温度场与速度场的分布.模拟结果表明,在大电流(I≥250 A)时,在浮力、表面张力温度系数为正时的Marangoni力、电磁力单独作用于熔池上表面将会产生凸起变形,在电弧压力、表面张力温度系数为负时的Marangoni力单独作用下,熔池上表面将会产生凹陷变形.在大电流下,TIG焊和活性TIG焊熔池均产生凹陷变形.TIG焊熔池的中心区域形成向内的涡流,边缘部位形成向外的涡流,而活性TIG熔池在熔池中心和熔池边缘则分别形成两种成因不同的内向涡流.熔池表面变形量并不是各个驱动力作用的简单叠加. 相似文献
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为了研究2219铝合金中厚板爬坡TIG焊熔池热场特征,建立了中厚板TIG焊温度场模型,进行爬坡TIG焊熔池温度场三维数值模拟,以及不同焊接工艺参数对温度场的影响数值分析,同时通过焊缝形状尺寸的测定以及热电偶测温,对模型及温度场数值模拟结果进行验证。结果表明,受熔池重力影响,厚板爬坡姿态下熔池热场长度要大于平焊姿态;爬坡TIG焊温度场受焊接电流、焊接速度影响明显,焊接电流增加或者焊接速度降低,均会导致温度场最高温度上升,熔池宽度和长度增加;测量的实际焊缝尺寸与熔池温度场数据和数值计算结果相符度高,建立的模型及爬坡焊温度场三维数值计算准确。 相似文献
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提出了超声复合焊接空间中声场参数的分析方法,根据超声复合焊接特性构建了分析模型,利用COMSOL有限元分析软件模拟分析了声场参数随着发射端半径的变化情况,同时模拟分析了声场参数在不同电弧空间高度的变化规律.采用静态小孔法对不同焊接参数下稳定燃烧的直流U-TIG焊和普通TIG焊的电弧压力分布进行了测量.结果表明,U-TIG焊电弧压力峰值明显高于普通TIG焊,复合电弧能够提高焊接时熔池表面上方的电弧压力水平,但是随着电流增加,U-TIG焊和普通TIG焊电弧压力峰值的差值减小.分析认为大电流时,弧柱中心区域温度很高,电流密度很大,使TIG焊电弧压力峰值明显升高,而U-TIG焊电弧等离子流力受到气体流量的限制,电弧压力峰值增幅减小. 相似文献
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针对铝合金钨极惰性气体保护电弧焊(tungsten inert gas arc welding,TIG焊)过程中,焊接工艺参数的实时状态与焊缝熔池三维尺寸间的非线性对应关系,研究建立一种基于信息物理融合的多传感器TIG焊过程熔池状态协同感知计算方法. 首先,构建由红外温度传感器、电弧形态传感器、电弧能量传感器和焊接位置传感器组成的TIG焊过程熔池状态信息物理融合系统架构. 其次,考虑焊接过程中焊枪电弧的运动特性和测量噪声影响,设计基于温度、位置、能量传感器信息交互的熔池长宽深三维参数状态感知策略,并基于多传感器数据的异步和异构特性,提出了基于无迹卡尔曼滤波的焊接过程中熔池状态的多传感器数据协同感知算法. 针对7075超硬铝合金TIG焊过程进行熔池参数在线测量与辨识试验,结果表明,所提算法能够根据TIG焊过程多传感器数据实时计算熔池参数结果,焊缝宽度和焊缝高度计算结果误差基本上控制在10%以内,该算法响应时间基本控制在0.3 s内,能够较为准确地评估焊接过程中熔池的实时状态. 相似文献
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基于中厚板打底焊接存在着自动化程度及效率低的问题,采用脉冲熔化极气体保护焊-钨极氩弧焊(MAG-TIG)双电弧热源焊接对板厚为24 mm的Q235-B进行打底焊接单面焊双面成形工艺研究及机制分析. 结果表明,脉冲MAG-TIG双电弧热源打底焊接时,利用TIG电弧与MAG电弧间的电磁力来调节MAG电弧在熔池前端的加热位置,使得一部分电弧热量直接作用于钝边上;结合焊接电弧放电行为与熔池流动分析发现,打底成形稳定性最佳时,利用TIG电弧与熔池的剪切力使得液态金属向后方流动,熔池前端底部液态金属减少,易于平衡稳定,可获得熔透均匀、连续、稳定的打底焊缝背面成形. 相似文献
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针对低碳钢材料焊接效率低的问题,提出了等离子-TIG耦合电弧焊接方法,通过设计集约化枪体结构促使等离子和TIG电弧在电磁力作用下实现稳定耦合,优化复合焊接热源特征,并研究了电弧形态、焊缝成形和力学性能.结果表明,等离子-TIG耦合电弧具有优异的深熔焊接特性,相对于等离子和TIG焊接方法具有更加合理的深宽比,且对熔滴、熔池有震荡搅拌效果,促使晶粒细化,并降低熔合区联生结晶倾向.使用5 mm厚Q235B钢板进行对接试验,实现了稳定的单面焊接双面成形,焊缝美观无缺陷且抗拉强度优于母材. 相似文献
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《Science & Technology of Welding & Joining》2013,18(7):594-600
AbstractTungsten inert gas (TIG) welding is most frequently used for arc study because it is clean and easy to control welding factor. Many researchers have been focused on the plasma stream to find out the relationship between vertex angle and penetration of the tungsten electrode in TIG welding. Moreover, researchers studied the characteristics of vertex angle and arc pressure and heat flux distribution of the tungsten electrode. In addition, they have carried out factors that have influence on the behaviour of the molten pool. Previous studies assumed that arc pressure was dominant for the force that physically works on the surface of the molten pool, neglecting the shield gas pressure. In addition, they have been focused on the protection of molten weld pool from exposure to the atmosphere. The object of this study is to investigate the effect of shield gas pressure on the surface of the molten pool by measuring the distribution of arc pressure and shield gas pressure compared with arc physical results of previous researches. In this study, we measured the distribution of arc pressure and shield gas pressure on the water cooled copper plate by changing the setting shield gas pressure and shield gas cup inside diameter. As the setting shield gas pressure increased and the shield gas cup diameter decreased, the arc radius got narrower due to the thermal pinch effect. Maximum arc pressure was slightly affected by setting the shield gas pressure and shield gas cup diameter. However, the shield gas pressure on arc surroundings was raised with the increasing setting shield gas pressure and the decreasing gas cup inside diameter. Orbital welding with convex back bead was successfully performed through molten pool control by shield gas pressure adjustment. 相似文献
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为探究旋转电弧GMAW堆焊短路过渡时熔池的温度和对流分布规律,利用Flow-3D软件建立三维数学模型,采用球形旋转热源模型,考虑重力、熔滴拖拽力、表面张力、浮力作用,模拟了堆焊状态下,工件材料为Q235的旋转电弧GMAW短路过渡的熔池成形规律. 采用流体体积法追踪熔滴过渡和熔池表面的自由变形,并分析熔滴进入熔池时熔池内部温度场和流场的变化. 结果表明,熔池形成过程中,旋转熔滴对熔池有搅拌作用,并使熔池内部液态金属活性增强,流速变快,熔池内部液态金属体积变大,熔池的宽度变大. 模拟预测的焊缝尺寸、形状与试验吻合良好. 为优化焊接工艺参数、改善旋转电弧GMAW堆焊焊缝质量提供参考依据. 相似文献
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M. Tanaka 《Welding International》2004,18(11):845-851
As is well known, arc discharges have been applied to various processes such as welding, cutting, spray coating, melting and refining. Unlike electrodeless discharge methods such as high frequency discharge of inductive coupling type (eg. RF discharge), arc discharge is a polarized discharge in which the arc is generated between the positive and negative electrodes.1 Accordingly, when the arc discharge is applied to welding processes, the material becomes one of the electrodes. In TIG welding, the material, that is, the molten pool, generally acts as the anode to the tungsten cathode. As shown in Fig. 1, TIG welding processes are based on the close energy balance between the 'electrode-arc plasma-molten pool'. On the other hand, for the formation of the molten pool, energy transfer from the arc is also important, but energy transfer in the molten pool after that is extremely important, too. In TIG welding of steels, in which energy transfer by convection current becomes dominant rather than thermal conduction,2 the penetration at the weld joint has hugely different geometries according to the difference in convective current phenomena at the molten pool. As a driving force of convective current in the molten pool in TIG welding, four forces have been considered,2-6 as shown in Fig. 1. They are the drag force (friction force) caused by plasma jet (cathode jet) generated by the arc, the buoyancy force induced by the density difference inside the molten pool, the electromagnetic force induced by the current flow inside the molten pool and Marangoni Force induced by the surface tension gradient of the molten pool. These four forces can be said to be also based on the close force balance of the 'electrode-arc plasma-molten pool', as with the energy balance. 相似文献