气体保护焊烟尘的产生及颗粒分布特征

为了了解气体保护焊过程中烟尘的产生及颗粒分布特征,分别对实心焊丝的熔化极气体保护焊和药芯焊丝的CO2焊进行烟尘收集,采用光散射法测试烟尘粒度,分析焊接烟尘粒度大小和分布规律;应用光学显微镜和电镜观察烟尘粒子的微观形貌,对烟尘粒子进行分类并探索烟尘的形成机理.实验表明,烟尘粒度分布具有准量子化特性,最初形成的烟尘颗粒一般...     

气体保护焊参数与焊接烟尘产生的关系

通过试验研究了焊接速度、电弧电压和焊接电流等工艺参数对焊接烟尘发尘量的影响规律.分析了不同的焊接方法和熔滴过渡形态对焊接烟尘的影响.进一步探讨了气体保护焊参数与焊接烟尘产生的关系,使烟尘发尘量降到最低.     

浅谈熔化极气体保护焊保护气体的选择

本文介绍了几种混合气体的特性，混合比及其应用，同时阐明了如何选用及配比混合气体等问题。     

熔化极气体保护焊保护气体选择研究

系统总结了保护气体物理特性、混合种类与比例、气体流量等参数对熔化极气体保护焊焊缝外观与性能的影响。结果表明,保护气体对焊缝力学性能、化学组成和表面成型性有重要影响,正确选择保护气体种类、混合种类与比例和气体流量,对于熔化极气体保护焊至关重要。     

保护气体对实心焊丝气体保护焊性能的影响

通过采用不同的保护气体,确定了保护气体成分对实心焊丝气体保护焊的工艺性能、焊缝金属化学成分、力学性能等的影响。对锅炉、压力容器不锈钢附件气体保护焊选材作了论证,将不锈钢附件实心焊丝气体保护焊与焊条电弧焊的性能作了综合比较,间接论证了不锈钢附件实心焊丝气体保护焊气体的可行性,并确定了不同工作环境下不锈钢附件气体保护焊保护气体的选择。获得了各种保护气体下实心焊丝气体保护焊化学成分、工艺性能的差异,对指导实心焊丝气体保护焊生产,提升产品外观、内在质量具有重要的指导意义。     

二氧化碳气体保护焊焊接油缸

二氧化碳气体保护焊焊接油缸徐一鸣浙江杭州千斤顶厂（３１０００９）液压油缸是一般起升机械的重要部件，要求承受较大的压力，具有足够的刚度与韧性。我厂生产的油缸缸体部件与阀座联结部均采用焊接结构，其焊接质量直接影响产品使用安全和工件可靠性。１可焊性分析油缸...     

CO2气体保护焊单面焊双面成形

CO_2气体保护焊(以下简称CO_2焊)是一种高效率的焊接方法,与手工电弧焊比较其生产效率高,节约电能和焊接材料,质量可靠,操作方便。特别是半自动焊接还具有较大的机动性。在国外CO_2焊被广泛采用,在国内也受到重视。我国“七五”规划和将要实施的“八五”规划都把CO_2焊作为推广项目。目前,CO_2焊正在普遍推广,但就CO_2焊单面焊双面成形的操作技术介绍较少。本文根据全国CO_2焊邀请赛CO_2气体保护半自动焊操作比赛项目,作综合性叙述。叙述薄板试板平焊、中厚板试板立焊、中厚板试板仰焊、管子水平固定焊、管子垂直固定焊。     

CO2气体保护焊焊补铸铁的焊缝组织与性能

以手弧焊和CO_2气体保护焊对铸铁进行焊接,结果表明:两种方法得到的接头强度相近,白口区宽度、硬度变化趋势基本相同。说明了以CO_2气体保护焊进行铸铁的焊补是可行的和经济的。     

轴向磁场对非熔化极焊接电弧的影响

利用设计的轴向磁场产生装置,采用理论与试验相结合的思路,将其作用于非熔化极焊接过程,包括等离子焊接和钨极氩弧焊(TIG)两种焊接方法.利用高速摄像装置观察电弧形态变化,获得并对比两种电弧的变化情况.结果表明,由于等离子电弧本身组成的特殊性,导致其与TIG电弧在同样磁场作用下发生变化的程度不同.然后做出运动受力分析,建立了轴向磁场下的粒子运动模型,由于粒子轴向运动速度的差异性,导致轴向磁场下带电粒子的运动阶段的不同,给出了两者在磁场下不同变化的原因.     

Effects of welding voltage on process stability in hyperbaric gas metal arc welding

Based on hyperbaric gas metal arc welding （GMAW） experiments at ambient pressure of 0. 8 MPa, the process stability of different welding voltages was studied. The experiments were carried out with a high speed camera system including infrared laser backlight and electric signal acquisition system. Keeping wire feed speed at 8 m/min, arc length increases linearly with the increase of welding voltage in O. 8 MPa argon environment. Under this condition, all the metal transfer modes are droplet repelled transfer and the transfer frequency increases with increasing welding voltage. The number of deviating spatter is less with relatively high welding voltage. The results of electric signal waveforms show that the probabilities of short circuit and arc interruption decrease firstly and then increase with increasing welding voltage. When the welding voltage is 37 V, the hyperbaric welding process is the most stable with no probability of short circuit and arc interruption.     

Modelling of bead hump formation in high speed gas metal arc welding

Without any presupposed mechanism, a unified three-dimensional model is developed to predict the formation of humping bead in high speed gas metal arc welding, which considers the three phase coupling of solid, liquid and gas and the effect of shear stress exerting on weld pool surface caused by arc plasma. A strong backward fluid flow in weld pool is identified as the major factor for bead hump formation. The generation of thin liquid transition zone and its premature solidification are two conditions responsible for the occurrence of humped weld. In case of low inner contact angle between the liquid metal and workpiece surface, the bead hump is still generated. With increasing welding current, the bead hump can be suppressed.     

基于激光散射法的焊接烟尘粒径测量

简述了粒子测量的现状和进展。基于Mie散射理论的激光散射粒子测量技术运用于粒径小于10μm的焊接烟尘颗粒,这种方法因其具有众多优点而获得广泛应用。对应用激光散射方法检测焊接烟尘进行了理论分析,并给出了相应的检测手段。构建了一套基于Mie散射理论的实验光学装置．并用该装置测量出了焊接烟尘微粒的平均粒轻。     

焊接烟尘发尘机理及其影响因素

详细地阐述了焊接烟尘形成的蒸发、凝结、长大机制以及其形成后的扩散方式,对典型的焊接材料的烟尘性质进行了分析,介绍了有毒有害气体产生的原因和方式,对影响焊接烟尘产生的材料因素和工艺因素进行了分析.     

环保焊枪吸烟对小电流CO2气体保护电弧焊的影响

采用环保焊枪进行了小电流二氧化碳气体保护电弧焊平焊位置焊接,通过分析焊接过程中电弧形貌、电流电压和熔滴过渡方式变化以及焊缝成形、焊缝金属拉伸力学性能和X射线探伤结果,评估了吸烟功率变化时的吸烟效果以及吸烟行为对于焊接过程和焊缝质量的影响规律. 结果表明,使用环保焊枪可以显著降低小电流二氧化碳气体保护电弧焊时飘散在周围空间中的焊接烟尘. 吸烟过程虽然使得短路过渡熔滴频率略有增加,悬挂熔滴和电弧的稳定性略为变差,但对焊缝成形和焊接缺陷都无影响,焊缝金属屈服强度略有减小,抗拉强度略有增加.     

The humping phenomenon during high speed gas metal arc welding

Abstract

A commonly observed welding defect that characteristically occurs at high welding speeds is the periodic undulation of the weld bead profile, also known as humping. The occurrence of humping limits the range of usable welding speeds in most fusion welding processes and prevents further increases in productivity in a welding operation. At the present time, the physical mechanisms responsible for humping are not well understood. Thus, it is difficult to know how to suppress humping in order to achieve higher welding speeds. The objectives of this study were to identify and experimentally validate the physical mechanisms responsible for the humping phenomenon during high speed gas metal arc (GMA) welding of plain carbon steel. A LaserStrobe video imaging system was used to obtain video images of typical sequences of events during the formation of a hump. Based on these recorded video images, the strong momentum of the backward flow of molten metal in the weld pool that typically occurred during high speed welding was identified as the major factor responsible for the initiation of humping. Experiments with different process variables affecting the backward flow of molten weld metal were used to validate this hypothesis. These process variables included welding speed, welding position and shielding gas composition. The use of downhill welding positions and reactive shielding gases was found to suppress humping and to allow higher welding speeds by reducing the momentum of the backward flow of molten metal in the weld pool. This would suggest that any process variables or welding techniques that can dissipate or reduce the momentum of the backward flow of molten metal in the weld pool will facilitate higher welding speeds and productivity.     

Residual stresses in cold-wire gas metal arc welding

This work compares the welding residual stresses of the cold-wire gas metal arc welding and conventional gas metal arc welding processes. Two techniques were used to measure the residual stresses: X-ray diffraction and acoustic birefringence. The base metal used was carbon manganese steel plates of 9.5-?mm thickness. The results showed that the introduction of the cold-wire tends to decrease the residual stresses, suggesting that the introduction of the cold wire decreases the amount of heat given to the base metal, and consequently lowers residual stresses.     

Arc characteristics of twin-wire indirect arc gas shielded welding

Twin-wire indirect arc gas shielded welding is a novel welding method. By recording the arc shape and welding parameters, the effects of welding parameters and included angle on arc characteristics are discussed in this paper. The experimental results show increasing welding current can prompt centralized and straight of arc due to increasing plasma force and electric magnetic pinch effect. Increasing arc voltage can increase the size and brightness of the arc, as a result of increasing arc energy. The reducing of included angle increases the electric magnetic pinch effect, the arc becomes slender and supplies higher energy. It is thought the smaller included angle is beneficial to obtain perfect weld bead.