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介绍一种新的表面强化方法,即高频脉冲电弧表面强化技术,以碳钢为基体,研究了渗铬强化层近表面的铬浓度变化,强化层相组成,了分析电极材料中碳和空气中氮的迁移现象,并对强化层做了耐磨性实验。 相似文献
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1.绪言近年来,为了得到高效率电弧焊接,对于多电极焊接做了各种探讨。但是,过去发表的都是在各电极上同时通电的方式,当电极接近并加大电流时,根据毕奥-萨伐尔定律可知,电极间产生的磁场使电弧间产生干扰。也就是说,各电极为同极性时,电弧在电极间相互吸引,电弧不能充分触及母材,因而不能形成良好的焊道。为了实现在各电极接近时能防止电弧干扰现象,研究了各电极不同时通电的 相似文献
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开发了一种耦合电弧钨极,可显著降低电弧压力,消除咬边和驼峰焊道等缺陷,实现较高速度的TIG焊接.针对这种钨极进行了TIG电弧压力测量,研究了主要工艺参数对电弧压力分布的影响规律.结果表明,与传统TIG电弧相比,在相同参数下耦合电弧钨极TIG电弧压力峰值明显降低,并且随着弧长的增加、钨极伸出长度的增加、焊接电流的减小、电极槽宽的增大以及钨极直径的增大,耦合电弧钨极TIG焊的电弧压力峰值减小.对电弧压力的影响由大到小依次为焊接电流、钨极伸出长度、弧长和钨极直径、电极槽宽. 相似文献
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最近研究的一种电弧焊方法,其焊接电流在TIG和MIG焊的两电极间交替转换,以防止电弧在两电极之间的相互影响。在这种焊接方法中,所观测到的电弧现象表明,MIG焊丝的尖端很容易熔化。由于TIG电弧的辐照的帮助,熔滴周期性地从焊丝过渡到熔池中而无飞溅。TIG和MIG焊的焊接电流可以单独地改变,而在两电极间电弧无相互 相似文献
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为了研究交流CMT焊接过程中的电弧形态及熔滴过渡过程,采用高速摄像技术结合焊接电参数采集系统,拍摄了清晰的交流CMT电弧及熔滴图像,同步采集了电参数的波形数据,将二者结合起来分析.结果表明,交流CMT电弧经历燃弧-形成熔滴-熄弧过程;正极性阶段焊丝端头电弧集中,工件表面电弧发散,形成"钟罩"形电弧;负极性阶段电弧有"上爬"现象,该现象会加速焊丝熔化;熔滴过渡经历冷-热-冷的转换,无缩颈形成;负极性阶段的焊丝熔化速度相对较快,熔滴过渡周期小于正极性阶段,熔滴直径比正极性阶段的略大. 相似文献
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C.C. Kao Albert J. Shih 《International Journal of Machine Tools and Manufacture》2006,46(15):1996-2008
Monitoring the gap voltage and current in micro-hole electrical discharge machining (EDM) using high-speed data acquisition with 0.5 ns sampling period is conducted. The spark and arc pulses at three stages, namely electrode dressing, drilling, and penetration, of the micro-hole EDM are recorded. The EDM process parameters are setup to use negative polarity to blunt the electrode tip and positive polarity for micro-hole drilling and penetration. A new phenomenon of pre-discharging current is discovered. In the first 20–30 ns of spark and arc pulses, the current starts to rise while the voltage remains the same. Effects of EDM process parameters, including the open voltage, electrode diameter, and polarity, on the rate of spark and arc pulses and electrode feed rate are investigated. A model based on the RLC circuit is developed to study the ringing effect at the end of a discharge. The intrinsic parasitic capacitance and resistance of a RLC circuit are calculated from the decaying voltage signal and compared under two sets of experiments with varying wire electrode diameter and gap voltage to validate the ringing model. The calculation and experimental results validate the proposed RLC model for ringing phenomenon. The model shows the electrode diameter has negligible effect on ringing and high open voltage increases the parasitic resistance and damping in ringing. The monitoring technique and ringing model developed in this research can assist in the selection and optimization of micro-hole EDM process parameters. 相似文献
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I.N. Ponomareva 《Welding International》2013,27(8):631-634
The main relationships governing the movement of the cathode (anode) spot of an electric arc, in particular, the effect of rotation of the arc spots, which can be visually investigated at low arc currents, are investigated. The reasons for this phenomenon are explained on the basis of the vortex electrodynamic model of the electric arc in which the current-conducting channel in the plasma arc column has the structure of the dynamic cylindrical coaxial condenser. This phenomenon must be taken in the analysis of the processes taking place in the weld pool because the rotation of the channel of the plasma arc column is the reason for the effective rotational displacement of the material of the weld pool. 相似文献
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Fuzhu Han Yongxain Wang Ming Zhou 《International Journal of Machine Tools and Manufacture》2009,49(1):20-24
A novel high-speed electrical discharge machining (EDM) milling method using moving electric arcs has been proposed in this study. We connected a copper electrode rotating rapidly around its axis and a work piece to a DC power supply to generate a moving electric arc. To ensure high relative speed of any point on the electrode with respect to the work piece, the electrode was shaped like a pipe. It was observed that the electric arcs move rapidly within the discharge gap due to the revolution of the tool electrode, removing the materials on the electrode along the track of the arc roots. To explore the characteristics of machining with moving electric arcs, an EDM milling apparatus was devised. Two planes with approximately the same roughness were machined separately by this equipment and a traditional EDM machine for comparison. It was found that a much higher material removal rate can be easily achieved by EDM milling with moving electric arcs. In the meanwhile, wear of the tool electrode in this new method is negligible, which is greatly favorable for machining accuracy. The microstructures of these surfaces were also investigated for further information. 相似文献
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采用一种新型的电场增强阴极弧沉积技术在304不锈钢表面制备了TiCN涂层。研究了附加电极电流对阴极弧放电特性、涂层相结构、截面形貌、耐磨性以及结合力的影响。结果表明:附加电极的引入显著增加真空室内等离子体密度,工件偏流提高近100%;只有超过一定阈值,附加电极电流才能有效减小晶粒尺寸、提高膜层致密性,同时也提高膜基结合力。附加电极电流为30 A时,膜基结合力达到HF1,相对于无附加电极情况样品表面摩擦系数降低了33%,磨痕宽度最小,耐磨性最好。可见电场增强阴极弧放电是一种非常有效的TiCN制备方法。 相似文献
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基于流体力学和麦克斯韦方程组,建立片状偏钨极电弧三维数学模型,计算得到电弧温度场、流场、电场及电流密度分布.结果表明,片状偏钨极厚度方向电弧温度场、流场、电场及电流密度呈对称分布;相同焊接工艺参数下,片状偏钨极电弧最高温度、最大流速及电流密度小于圆柱钨极电弧;电流密度受片状偏钨极前端斜边引导作用和电弧惯性后拖效应的共同影响,其分布范围沿钨极宽度方向扩展,且电弧等温线在该方向上扩张;片状偏钨极前端斜边倾角的改变,会引起电流密度在钨极前端局部集中,并导致阴极下方高温区和阴极射流沿斜边偏移. 相似文献
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