Integral self-regulation in arc welding processes

As a result of the development of processes of gas-shielded consumable electrode arc welding with a constant electrode wire feed rate, characterized by different mechanisms of electrode metal transfer and large changes in the arc power with time, this study is carried out to supplement and generalize the concept of self-regulation of different arc welding processes.     

熔化极气体保护焊电流与电压调节

在应用熔化极气体保护焊的基础上,分析焊接电流和电弧电压对焊缝成形的影响,探究焊接电流与电弧电压匹配对焊接电弧特性的影响规律,总结正确调节焊接电流与电弧电压的基本方法和操作技能,正确调节焊接电流与电弧电压是熔化极气体保护焊技术推广与应用的关键因素。     

Special features of pulsed arc welding of titanium

The special features of pulsed arc welding of titanium are described.     

Computer-based sensing and visualizing of metal transfer mode in gas metal arc welding

Using Xenon lamp lights to overcome the strong interference from the welding arc, a computer-based system is developed to sense and visualize the metal transfer in GMAW. This system combines through-the-arc sensing of the welding current and arc voltage with high speed imaging of the metal transfer. It can simultaneously display the metal transfer processes and waveforms of electrical welding parameters in real-time The metal transfer videos and waveforms of electrical welding parameters can be recorded. Metal transfers under various welding conditions have been investigated with the system developed.     

Multipass pulsed current gas metal arc welding of P91 steel

Conventional gas metal arc welding of modified 9Cr–1Mo steels referred to as P91 steels is considered difficult due to loss of alloying elements and degradation of weld joint properties. In comparison to the conventional process, pulsed current gas metal arc welding allows more accurate control of heat input per unit length and electrode deposition and, thus, can be more suitable for the joining of P91 steel. A detailed experimental study is therefore undertaken to examine the roles of welding current, speed and groove angle in the weld bead profiles and joint properties in multipass pulsed current gas metal arc welding of 12?mm thick P91 steel. The results show that the joint properties are strongly influenced by the heat input per unit length and the groove angle. A groove angle of 75° and an appropriate choice of process conditions resulted in fairly acceptable bead profiles and joint properties.     

熔化极气体保护焊焊缝成形的关键工艺条件

目前熔化极气体保护焊在广泛应用于很多行业,但由于缺乏系统全面介绍该焊接方法工艺的资料,同时熔化极气体保护焊工艺又较为复杂,导致不少多年从事熔化极气体保护焊的工作人员也很难将焊接工艺编制和焊接参数调节工作做得较圆满,阻碍了熔化极气体保护焊的应用与推广,因此研究总结熔化极气体保护焊工艺具有现实意义。在应用熔化极气体保护焊的基础上,用实验验证了焊接电流、电弧电压、干伸长度和焊接速度对焊缝成形的影响,分析总结了其对焊缝形状的影响规律,为熔化极气体保护焊技术的推广应用提供了技术参考。     

A dynamic welding heat source model in pulsed current gas tungsten arc welding

A time-dependent welding heat source model, which is defined as the dynamic model, was established according to the characteristic of PCGTAW. The parabolic model was proposed to describe the heat flux distribution at the background times. The recommended Gaussian model was used at the peak times due to the bell-shaped temperature contour. The dynamic welding heat source was composed of these two models with a function of time.     

Self-regulation of the arc in consumable electrode welding

The characteristic features, criteria and algorithm of the currently available method of self-regulation of the arc in mechanised arc welding with a constant consumable electrode feed rate are investigated. The main problem is that when it is necessary to reduce the welding current, for example with an increase of the thickness of the welded edges or the leg length of the fillet welded joint, welding should be carried out with a wire with a smaller diameter, down to 0.5 mm or even 0.3 mm. This complicates welding technology and increases the price of the wire because of multiple drawing of the wire to the small diameter. Therefore, the main task is to improve the algorithm of self-regulation of the arc and, consequently, reduce the minimum value of the current density, lower than 30 A/mm² for a steel wire with a diameter of 5 mm at which self-regulation of the arc is still possible, in order to widen the technological possibilities of the method and reduce the cost of technology. The authors believe that this approach would make it possible to produce efficient tools for understanding physical processes accompanying the formation of permanent joints by different arc welding methods.     

Determining chaotic invariant properties of short-circuiting gas metal arc welding from an observed time series

The experimental time series of welding current produced by carbon dioxide gas metal arc welding with shortcircuiting transfer were recorded and subsequently evaluated. Based on phase space reconstruction, the correlation dimensions and Kolmogorov entropies of the corresponding system have been numerically calculated using the Grassberger-Procaccia algorithm at different time delays. It was found out that the time delay has little effect on the estimation of correlation dimension; conversely,it plays a key role in producing precise results on the estimation of Kolmogorov entropy.     

Shunting of the arc current in plasma-arc consumable electrode welding (plasma-MIG welding)

ABSTRACT

Special features of the process of shunting plasma arc current with a consumable electrode are investigated. The effect of the diameter of the consumable electrode, its visible extension and plasma arc current on the shunting current is determined. The effect of shunting current on the electrode metal transfer and the rate of electrode melting is determined.     

轨道车辆不锈钢气体保护拉弧螺柱焊

介绍电弧螺柱焊焊接方法的分类及焊接工艺原理,阐述气体保护拉弧螺柱焊在轨道车辆不锈钢材料上的应用。采用BMK-12W电弧式螺柱焊机进行工艺试验,焊后根据相关标准进行外观检验、弯曲试验和宏观检验。结果表明,气体保护拉弧螺柱焊技术在轨道车辆不锈钢材料的应用良好,能够获得优质的焊接接头。     

基于方差分析法的C-276合金脉冲电流自动化钨极气体保护电弧焊参数优化

优化C-276合金脉冲电流自动化钨极气体保护电弧焊参数有着重要的意义。采用田口方法,设计了拥有4个焊接参数(脉冲电流、基值电流、脉冲电流占空比和脉冲频率),3个水平等级,9组实验方案的正交实验,利用方差分析每个焊接参数的贡献百分比。实验结果表明,当脉冲电流、基值电流、脉冲电流占空比和脉冲频率分别为165 A、77 A、60%和5 Hz时,焊件具有最大的熔深。     

细丝CO2气体保护铸铁冷焊

对灰口铸铁的缺陷，人们一直使用Z308焊条来焊补，这是十分昂贵的焊接方法．利用CO2气体保护焊，能够解决同样的问题，能产生较大的经济效益。     

Modelling physical processes in arc welding with a stationary consumable electrode

The model of physical phenomena taking place in welding in a narrow slit-like gap is discussed. It is shown that the main process that determines heating of the electrode and melting in the modelling of the physical phenomena taking place in the electrode is the passage of welding current through the electrode. Measures for producing high-quality welded joints in arc welding with a stationary consumable electrode are proposed.     

Controlled bridge transfer (CBT) gas metal arc process for steel sheets joining

In non-pulsed gas metal arc welding (GMAW), spatter can be reduced by lowering the short-circuit current to a low level just before the re-arcing. The reduction in spatter requires an improvement in the accuracy of predicting the re-arcing by stabilizing the metal transfer and improving the robustness of the accuracy against disturbances. The controlled bridge transfer (CBT) process optimizes the accuracy of predicting the re-arcing in real time in response to the metal transfer, realizes spatter reduction and stable arc in non-pulsed GMAW. Traditionally, GMAW is carried out using electrode positive polarity. However, this polarity is not sufficient for welding extra-thin steel sheets, specifically those thinner than 1.0 mm. With electrode negative (EN) CBT process, although slight arc voltage fluctuation occurs caused by the behaviour of cathode spots on the tip of the wire during EN polarity GMAW, instantaneous voltage uses command computation to improve the transient response against the disturbance. Consequently, a stable arc can be obtained without increasing the number of short circuits in a unit time to obtain spatter-free welds.     

Study on chaos in short circuit gas metal arc welding process

Based on the chaos theory, an idea is put forward to analyze the short circuit Gas Metal Arc Welding （ GMAW-S） process. The theory of phase space reconstruction and related algorithms such as mutual information and so on, are applied to analyze the chaos of the GMAW-S process. The largest Lyapunov exponents of some current time series are calculated, and the results indicate that chaos exists in the GMAW-S process. The research of the chaos in the GMAW-S process can be help to get new knowledge of the process.     

手工电弧焊电压控制的研究

手工电弧焊的电弧电压是一个难以控制的参数,有时能对焊接质量产生较大影响。当电弧电压高于设定值时,通过焊接电源外特性曲线的转换,使电流从焊接电源跳变到较小电流,由此通知操作者去调节弧长,从而把电弧电压维持在设定值之下。     

保护气体对激光+双丝MAG复合焊焊缝形貌和电弧特性的影响

在激光+单电弧复合焊工艺的基础上,通过再添加一个电弧的方式,形成激光+双丝脉冲MAG复合焊工艺。研究了保护气体为φ(Ar)80%+φ(CO2)20%(情况A)和φ(Ar)40%+φ(CO2)10%+φ(He)50%(情况B)时对激光+双丝MAG复合焊焊缝表面成形和电弧特性的影响。利用LabVIEW信号采集系统和高速摄像系统同步采集焊接电流、电弧电压波形和电弧形态。结果表明,在焊缝表面和焊道两侧边缘处,肉眼可见斑点状、不连续的氧化物,情况A与情况B相比,情况A氧化物含量高,熔宽小;而情况B焊道平整,鱼鳞纹清晰。情况A中由于CO2含量较高,使其对电弧的冷却作用增强,减弱了激光对电弧的稳定作用,断弧次数比情况B多。     

焊丝直径和保护气体对GMAW熔滴过渡形态的影响

综述了焊丝直径和保护气体对GMAW熔滴过渡影响的新发现。研究表明,对于直径小于0.90 mm焊丝,转变电流后熔滴的平均直径并未小于原来的焊丝直径。随着焊丝直径的减小,临界电流呈减小趋势,但超细焊丝未测出这种趋势。直径小于0.90 mm的焊丝,增大电流不发生转变,是因为焊丝直径不能明显改变阳极斑点面积,电弧无法爬上熔滴。CO_2对较细焊丝熔滴过渡转变的影响,并未遵循随着CO_2含量的增大,转变电流提高的一般焊丝的模式。无论焊丝直径如何,用含30﹪以上的CO_2保护气体时,排斥过渡仍占主导地位。     

磁控电弧焊接工艺在非熔化极气体保护焊中的应用

针对非熔化极气体保护焊,介绍了作用于焊接过程中的平行磁场、横向磁场、纵向磁场、双尖角磁场和旋转磁场的特点及磁场发生装置的组成,分析了磁偏弧工艺、磁摆弧工艺、均匀纵向磁场作用下的磁旋弧工艺、非均匀纵向磁场作用下的磁旋弧工艺、旋转磁场作用下的磁旋弧工艺、磁再压缩技术等国内外典型的磁控电弧焊接工艺的基本原理、应用范围及存在的问题.并对焊接电弧外形的变化和运行机制,焊接电弧外加磁场强度的变化关系进行了研究.