Effects of current waveform parameters during droplet transfer on spatter in high speed waveform controlled Short-circuiting GMAW

Aim at improving the stability of the Short-circuiting Gas Metal Arc Welding （GMAW-S） process for the enhanced speed usage, effects of current waveform parameters during short-term on the welding stability have been investigated by experimental method. The welding power source used for the research is an inverter with a special current waveform control. It is shown that the spatter decreases at first then increases with each increase of the low current period, current increase rate and the maximum current limit. The test results are provided for welding of 1 mm and 3 mm mild steel at speed of 1.2 m/min. The stable GMA W-S process under high speed welding condition has been achieved by optimizing the parameters.     

基于药芯焊丝飞溅率模型决策分析的药芯配方的评判

在简要介绍了定量指标模糊综合决策方法的基础上，提出并建立了二级定量指标模糊综合决策模型，并将该模型应用于药芯焊丝药芯粉配方对飞溅率影响的评判问题中，试验结果表明，模糊决策模型的评判结论与试验结果吻合良好，这说明该模型能够较为准确地通过对药芯焊丝飞溅率的评判来确定药芯粉配方的优劣，从而也证明了模糊决策方法应用于焊接领域中的可行性与有效性。     

减小CO2气体保护焊飞溅的研究现状与展望

简述了CO2短路过渡焊的飞溅机理，主要从改善电源外特性、波形控制、一元化控制、智能控制等方面综述了当前广泛使用的电控方法。随着以新型功率电子器件为基础的逆变技术的发展，智能型的波控方法是当前减小CO2短路过渡焊飞溅的主要电控方法。     

Effects of material combination on laser beam drilling of a metal foil using a cover plate

This research investigated the microdrilling characteristics of metal foils depending on the materials of the cover plates and metal foils in the cover plate-laser beam machining (c-LBM) process, which is a method to achieve better quality in metal foil machining with a given piece of equipment. Laser beam drilling using a nanosecond pulsed laser was carried out on 10-µm-thick stainless steel 304 (STS304), nickel, and copper foils with 100-µm-thick cover plates of each material. Consequently, STS304 was found to be an effective cover plate material for reducing the hole diameter and spatter deposition on metal foils. Compared to the results without using a cover plate, the average hole diameter and the area of spatter deposition decreased by up to 77% and 96%, respectively, by using the STS304 cover plate. Meanwhile, the thermal deformation of the STS304 and nickel foils was prevented by using a cover plate, while the copper foil was barely deformed even without a cover plate. Lastly, it was remarkable that the copper foil was drilled with approximately 67% lower pulse energy than the effective minimum pulse energy required to drill it by using the STS304 cover plate, resulting in a smaller hole with little spatter.     

高频交变磁场对大电流GMAW熔滴过渡和飞溅率的影响

在熔化极气体保护焊过程中,采用大送丝速度,增大焊接电流和焊丝伸出长度是提高焊接熔敷率的直接途径.但当熔滴过渡转变为旋转射流过渡时,电弧不稳,飞溅增大,焊缝成形变差.施加不同频率的纵向交变磁场,对焊缝成形进行控制.采用高速摄像技术,拍摄焊接过程中的电弧形态和熔滴过渡,研究不同频率的磁场对熔滴过渡和焊接飞溅率的影响规律.结果表明,熔滴过渡形式不同,产生飞溅的机理不同;外加频率为1 000 Hz纵向交变磁场时,电弧的旋转半径减小,电弧的挺度增大,旋转射流过渡时电弧更稳定,焊接飞溅率降低,焊缝成形改善.     

Study on arc characteristics and behavior of metal transfer in pulse current flux-cored arc welding of mild steel

The variation in arc characteristics and behavior of metal transfer with the change in pulse parameters has been studied by high speed video camera during pulse current flux cored arc weld deposition. A comparative study of similar nature has also been carried out during flux-cored arc weld deposition in globular and spray transfer modes. The effect of pulse parameters has been studied by considering their mean current and arc voltage. The arc characteristics studied by its root diameter, projected diameter and length, and the behavior of metal transfer noted by the metal transfer model and the droplet diameter have been found to vary significantly with the pulse parameters. The observation may help in understanding the arc characteristics with respect to the variation in pulse parameters which may be beneficial in using pulse current FCAW to produce desired weld quality.     

自保护硬面药芯焊丝药芯成分对焊接飞溅的影响

用正交试验法探讨了自保护硬面药芯焊丝药芯粉中金红石、氟化物、硅灰石、氧化锆和镁砂对焊接飞溅的影响,对含氮自保护硬面药芯焊丝药芯粉的最佳配比进行了优化.结果表明:随着药芯中氟化物、氧化锆含量的增加,焊接飞溅增大;随着药芯中金红石、硅灰石和镁砂含量增加,焊接飞溅减少;当金红石、氟化物、氧化锆、镁砂和硅灰石质量分数分别为8.0%,4.0%,4.0%,5.0%和2.0%时,含氮自保护硬面药芯焊丝焊接工艺性能最佳.     

CO_2焊熔滴短路过渡过程的分析与控制

根据飞溅机理，对短路液桥收缩过程进行了深入分析和定量描述，指出短路液桥收缩过程规律并对液桥收缩程度进行了实时检测．在此基础上，首次提出了一种恒压与陡降复合的电源外特性，实现了对液桥收缩过程的实时控制，显著地降低了焊接飞溅，取得了优异的工艺效果     

Rheology parameters controlling spray atomization and roll misting behavior of waterborne coatings

Formation of small coating droplets is a phenomenon common to spray and roll application of coatings. Generation of small droplets, referred to as atomization, is the mechanism of controlling the quality and thickness of the applied coating layer in spray technology. In roll coating application, small coating droplets are formed at the nip–exit region under certain conditions. Because of the high-shear rates at roll nips and spray nozzles, it is common to relate high-shear viscosity with atomization and roll misting behavior of coatings. This paper will review the relative importance of shear and extensional flows, and the response of coatings to such flows, in affecting misting and atomization behavior. Experimental efforts to quantify the effect of shear and extensional rheological parameters have clearly established a lack of correlation of high-shear viscosities with both spray atomization and roll misting behavior of coatings. However, extensional viscosity is shown to have a strong correlation. Finally, how rheology modifiers can be selected to circumvent misting problems in roll coating applications and atomization problems in spray applications is discussed.     

国产高压变频器在水渣系统上的应用

文中介绍嘉兴发电厂为了节能降耗，对水力排渣系统的高压水泵进行变频改造。阐述高压变频器的具体方案、选型和变频原理，并分析应用高压变频调速产生的经济效益。