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TIG焊熔池表面流动行为的研究 总被引:4,自引:0,他引:4
针对钨极惰性气体保护(Tungsten inert gas,TIG)焊熔池表面流动行为,在确定TIG焊熔池表面可采用粒子示踪的方法来进行其表面流动行为示踪的基础上,在以激光为试验背光光源,通过激光在TIG焊熔池表面镜面反射后,使得熔池及示踪粒子清晰成像于成像屏上。在此基础上,开展对304不锈钢和Q235普通碳钢的熔池表面流动行为的试验研究,对所获得这两种材料的TIG焊熔池试验数据进行处理与对比分析,探究熔池表面流动规律。研究结果表明:在TIG焊过程中,其焊接熔池存在两种运动模式,在304不锈钢焊接过程中熔池表面的液态金属由边缘向熔池中心流动;在Q235碳钢焊接过程中熔池表面的液态金属不定向、不规则地由熔池中心向熔池边缘流动,并测量304不锈钢TIG焊过程中熔池表面的液态金属流动速率为12 mm/s左右,Q235碳钢的熔池表面的流动速率为15 mm/s左右。 相似文献
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铝合金双丝脉冲焊接时,强烈的双弧光强和铝合金的强反射作用造成熔池视觉传感比较困难。建立一套双丝脉冲焊熔池双向同步视觉传感软硬件系统,通过近红外滤光技术和控制电荷耦合器(Charge-coupled device,CCD)快门曝光时间,获得清晰的尾部和侧面同步铝合金熔池图像。针对铝合金双丝脉冲焊熔池图像存在的高频横纹干扰,提出利用巴特沃斯低通加强滤波的方法进行去除,并通过灰度拉伸、阈值分割和边缘提取等图像处理方法,获得双向熔池轮廓。通过熔池几何形态分析,得到双丝脉冲焊前中部熔池形状为椭圆形,尾部形状为抛物线。在获得抛物线和椭圆曲线方程的基础上定义并计算熔池宽度、全长、面积、周长、尾部系数等熔池几何特征参数。 相似文献
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基于流体力学、热力学及电磁学等理论建立二维脉冲MIG焊熔池数学模型,在Fluent软件中通过用户自定义程序(UDF)添加模型所需的热源、动量源项以及定义材料的物性参数,对焊接过程进行数值模拟,分析各驱动力对脉冲MIG焊熔池行为的影响以及熔池在脉冲周期内的变化规律。模拟结果表明,在焊接过程中马兰戈尼力对熔池影响最大,其次为电弧压力,然后为电磁力,浮力影响相对较小。在各驱动力复合作用时,熔池表层的熔池形态以马兰戈尼力为主导,熔池内部以电磁力为主要作用力,造成熔池内形成了两种不同方向的环流。熔滴冲击力主要作用于熔池表层,对熔池内部影响较小。脉冲MIG焊高速摄像试验表明,实际熔池形态与模拟结果吻合良好,验证了熔池模型的合理性。 相似文献
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铝合金TIG焊熔池图像的获取与处理 总被引:10,自引:0,他引:10
研究建立了适用于铝合金TIG焊接过程中焊接熔池图像传感系统,探索了获取铝合金熔池图像的条件,详细论述了图像传感系统与焊接电源特性之间的匹配关系。给出了图像传感系统中各个部分之间的空间位置关系。在多种不同的焊接规范下进行了大量的图像获取试验,获得了不同规范下清晰的铝合金熔池正反两面图像。分析了铝合金焊接熔池图像的特征,设计了相关中值滤波和基于统计理论的双期望值阈值方法以及小波变换等方法对焊接熔池图像进行处理,获得了铝合金焊接熔池图像的准确边缘,为焊接过程的智能控制打下基础。 相似文献
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为提高中厚板核容器焊接制造效率、质量稳定性及满足无衬板打底单面焊双面成形的工艺新要求,设计小角度、大钝边Y型坡口平板对接焊接结构,建立双频调制脉冲TIG焊接试验控制系统,开展多组低频脉冲和双频调制脉冲焊接工艺对比试验,获得坡口角度60°、钝边5mm的试板对接可靠打底单面焊双面成形焊缝。进一步研究分析双频调制脉冲电弧、熔池动态行为变化及熔池表面温度场的演化规律,探究讨论双频调制脉冲电流作用下焊缝熔深增加的原因。结果表明,双频调制脉冲电弧因高频脉冲电磁压缩作用具有更高的能量密度和更强的电弧穿透力,使熔池底部极易形成液态金属薄膜并穿透形成熔孔;同时,双频调制脉冲电弧减弱了熔池顶底部液态金属能量波动,增强熔池热惯性,有效降低熔池凝固速率,增加了焊缝熔深,为熔池单面焊双面成形提供良好的热力动态平衡条件。 相似文献
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基于TIG焊电弧-熔池统一模型分析焊接电弧 总被引:1,自引:0,他引:1
以TIG焊电弧为研究对象,建立了电弧—熔池的统一模型,并在此模型的基础上对焊接电弧进行了分析。建立此模型就避免了对阳极表面温度的假定,使得对焊接电弧的分析与实际情况更近了一步,从而也为将焊接电弧和熔池作为一个整体来进行分析奠定了基础。采用ANSYS软件分析并得到了阳极表面温度的变化情况,阳极表面电流密度的分布状况,得出热流密度与电流密度分布规律的一致性。并从电磁力和流体流动的角度揭示了电弧压力产生的原因,并通过试验验证了电流密度和电弧压力的分布情况。 相似文献
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研究了YAG激光、GTAW电弧复合焊接铝合金时各种规范参数对焊缝成型的影响规律 ,探讨激光与电弧的复合作用机理。结果表明 ,采用YAG激光 +GTAW复合工艺焊接铝合金具有焊缝成型美观、热影响区小等优点 ,与GTAW焊接相比 ,焊速显著提高 ,可以显著增加熔深 ,达到采用小功率激光焊机实现铝合金的焊接目的 ,Laser、GTAW是铝合金焊接理想的工艺方法。 相似文献
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本文分析了铝合金3003HX8薄板(δ=1.2~1.8mm)长焊缝(2~2.4m)焊接的工艺特点,找出了三个焊接难点:薄板焊接容易烧穿;世接变形大,特别是波浪变形很难矫正;焊缝质量均一性差。为克服以上难点进行了大量的试验研究,通过试验探索出用脉冲TIG自动焊获得成功,并把这一技术在专用汽车制造中推广应用,生产效率提高3倍以上,使焊接质量达到国际同行业的先进水平。 相似文献
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Chen Zhixiang Song Yonglun Zhang Jun Zhang Wanchun Jiang Li Xia Xuxin 《Frontiers of Mechanical Engineering in China》2007,2(2):218-223
A laser vision sensing based on the adaptive tungsten inert gas (TIG) welding system for large-scale aluminum alloy components
was established to fit various weld groove conditions. A new type of laser vision sensor was used to precisely measure the
weld groove. The joint geometry data, such as the bevel angle, the gap, the area, and the mismatch, etc., aided in assembling
large-scale aerospace components before welding. They were also applied for automatic seam tracking, such as automatic torch
transverse alignment and torch height adjustment in welding. An adaptive welding process was realized by automatically adjusting
the wire feeding speed and the welding current according to the groove conditions. The process results in a good weld formation
and high welding quality, which meet the requirements of related standards.
Translated from Journal of Beijing University of Technology, 2006, 32(8): 714–718 [译自: 北京工业大学学报] 相似文献
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V. Balasubramanian V. Ravisankar G. Madhusudhan Reddy 《The International Journal of Advanced Manufacturing Technology》2008,36(3-4):254-262
High strength aluminum alloys (Al-Zn-Mg-Cu alloys) have gathered wide acceptance in the fabrication of lightweight structures
requiring high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway
transport systems. The preferred welding processes of high strength aluminum alloy are frequently the gas tungsten arc welding
(GTAW) process and the gas metal arc welding (GMAW) process due to their comparatively easy applicability and better economy.
Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal
solidification. This often results in inferior weld mechanical properties and poor resistance to hot cracking. In this investigation,
an attempt has been made to refine the fusion zone grains by applying a pulsed current welding technique. Rolled plates of
6 mm thickness were used as the base material for preparing single pass welded joints. A single ‘V’ butt joint configuration
was prepared for joining the plates. The filler metal used for joining the plates was AA 5356 (Al-5Mg (wt%)) grade aluminum
alloy. Four different welding techniques were used to fabricate the joints: (1) continuous current GTAW (CCGTAW), (2) pulsed
current GTAW (PCGTAW), (3) continuous current GMAW (CCGMAW) and (4) pulsed current GMAW (PCGMAW). Argon (99.99% pure) was
used as the shielding gas. Tensile properties of the welded joints were evaluated by conducting tensile tests using a 100 kN
electro-mechanical controlled universal testing machine. Current pulsing leads to relatively finer and more equi-axed grain
structure in GTA and GMA welds. In contrast, conventional continuous current welding resulted in predominantly columnar grain
structures. Grain refinement is accompanied by an increase in tensile strength and tensile ductility. 相似文献
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Study of mechanism of activating flux increasing weld penetration of AC A-TIG welding for aluminum alloy 总被引:1,自引:0,他引:1
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.
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Translated from Chinese Journal of Mechanical Engineering, 2006, 42(5): 45–49 [译自: 机械工程学报] 相似文献
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J. J. Wang T. Lin S. B. Chen 《The International Journal of Advanced Manufacturing Technology》2005,26(3):219-227
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. 相似文献
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《Measurement》2015
Friction stir welding could be considered as a suitable technique for joining of aluminum alloys due to the emerging of different problems in fusion welding of these alloys, especially in lap joint designs. For this purpose, it is necessary to optimize the process parameters while in this study, the combined effects of tool rotation and welding travel speed on the macrostructure and defect formation of friction stir lap welding of AA5456 was investigated. The rotating tool was plunged from the 5 mm-thick AA5456-H321 (top sheet) surface into the 2.5 mm-thick AA5456-O (bottom sheet) and lap joints were fabricated by rotational speeds of 300, 600, 800 and 1000 rpm and welding speeds of 15, 30, 60 and 100 mm min−1. The effect of tool rotation and welding speed on the macrostructure, material flow and defect formation, i.e. hooking, kissing-bond and cavity, were studied by optical microscopy and scanning electron microscope. The results declared that hooking height decreased as the welding speed increased while kissing-bond was formed at higher welding speeds. Moreover, hooking region was extended as the tool rotational speed increased. However, at a high rotational speed, cavity was even created. 相似文献
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