共查询到19条相似文献,搜索用时 109 毫秒
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针对双弧脉冲MIG焊热源稳定性差的问题,本文对双弧脉冲MIG焊耦合电弧进行瞬态数值模拟,分析了不同脉冲电流参数下耦合电弧形态、温度和压力的分布及变化规律。研究表明:耦合电弧呈驼峰状,脉冲电流发生跳变时,耦合电弧伸展或收缩,并逐渐稳定,峰值电流越小,越快达到稳定;增大脉冲电流,耦合电弧温度和电弧压力随之升高;保持总电流不变,减小主弧电流,增大旁弧电流,主弧温度和电弧压力减小,旁弧温度和电弧压力增大,当旁弧电流足够大时,耦合电弧温度和电弧压力呈双峰分布。数值模拟结果与双弧脉冲MIG焊工艺实验结果吻合良好,模拟结果对调控双弧脉冲MIG焊脉冲电流参数,改善其耦合电弧稳定性及工艺性能具有重要意义。 相似文献
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离子镀膜中的弧电流对膜层质量的影响 总被引:1,自引:0,他引:1
论述了电弧电流对多弧离子镀膜层的硬度,厚度及其外观形貌的影响,并进一步阐述了电弧电流在实际应用中的作用,说明了镀制不同功能的膜层,应选择不同弧电流的重要性。 相似文献
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真空开关电弧电流过零前的电弧等离子体状态对真空开关能否顺利开断具有十分重要的影响。本文在建立小间隙真空电弧磁流体动力学(MHD)模型的基础上,采用通用计算流体力学仿真软件对电弧电流过零前0.5 ms时的电弧等离子体的特性进行数值仿真研究。计算得到了真空电弧等离子体压力、等离子体密度、离子纵向速度、阳极表面纵向电流密度和电弧电压等的空间分布。仿真结果表明:从阴极到阳极,真空电弧等离子体压力和密度逐渐增大,而等离子体速度逐渐减小;阳极表面电流密度存在较大径向梯度,最大值低于形成阳极斑点的极限收缩电流,阳极仍不活跃。仿真得到的等离子体密度分布与高速摄像机拍摄得到的CMOS图像光强基本吻合,计算得到的电弧电压与测得的电弧电压是一致的,从而验证了本模型的可行性。 相似文献
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为优化直流埋弧炉工业硅冶炼过程,建立二维轴对称等离子体电弧的磁流体动力学模型,运用有限元分析软件,计算得到了等离子体电弧的形态特征分布,并与已有的实验测量结果进行了比较。通过计算不同电流、弧长条件下电弧的温度、速度变化以及熔池表平面的热通量组成分布,分析了电弧的形态变化规律和电弧的传热方式,由此计算不同电流值、不同电弧弧长的条件时,电弧向阳极熔池表面传热的效率。结果表明:弧长越长,向熔池表面传热的效率越小;电流越大,向熔池表面传热的效率越高。基于结果分析,工业硅生产应采用长电弧低电流高电压的冶炼模式。 相似文献
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为了对真空开关电弧燃烧过程及热形态变化规律研究,本文采用粒子成像测速(PIV)技术对短间隙真空开关电弧进行了实验研究,观察分析了电弧流场的信息,有明显的漩涡区。实验结果表明,运用PIV技术能较好地获取真空开关电弧燃烧二维速度场分布;随着电弧电流不断增大,真空间隙中金属蒸气压力不断增大,电弧加速向四周扩散运动,当电弧电流增大到一定值时,在电弧四周产生明显的涡流区域;电弧电流峰值过后,涡流区域不断减小,当电弧电流减小到一定值时,电弧不再向外扩散,而是向弧柱中心做集聚运动。 相似文献
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利用朗缪尔双探针诊断电弧离子镀等离子体参数 总被引:1,自引:1,他引:1
本文利用朗缪尔双探针对电弧离子镀等离子体进行了诊断.双探针具有收集电流小的优点(小于离子饱和电流),可以避免探针在高密度电弧离子镀等离子体中被烧坏.利用离散傅里叶变换(DFT)对测量曲线进行平滑,有效地克服了电弧离子镀等离子体放电所固有的强烈波动.探针端部设计能够避免由薄膜沉积造成的探针与支撑杆短路问题.实验结果表明,等离子体密度随着弧电流和气压的增加而增加,而电子温度随着弧电流和气压变化不明显.另外,使用双靶放电等离子体密度和电子温度高于单靶放电.这些结果提供了电弧离子镀等离子体的基本参数,对于材料涂层工艺研究具有积极意义. 相似文献
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利用高速摄影技术,对磁控电弧离子镀中阴极斑点大小、寿命及运动轨迹进行了观测,得到了极斑点电流密度、运动速度随磁场、电弧电流及背景气体压力改变而变化的关系曲线。 相似文献
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利用高速摄影技术,对磁控电弧离子镀中阴极斑点大小、寿命及运动轨迹进行了观测,获得了阴极斑点电流密度、运动速度随磁场、电弧电流及背景气体压力改变而变化的关系曲线。 相似文献
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Jun-feng Hu Jian-guo Yang Hong-yuan Fang Guang-min Li Yong Zhang Xin Wan 《Computational Materials Science》2007,38(4):631-641
Although the air–arc cutting process has been widely used in the material processing engineering, little information about temperature, stress and microstructure in the plate air–arc cut is known. A three-dimensional finite element model including the material removal and the thermal effect of the arc is developed to study the temperature and stress fields of 10Ni5CrMoV steel plate during air–arc cutting process in this paper. The microstructures and micro-mechanical properties of the parts near the groove especially in heat affected zone (HAZ) are studied by experimental methods, and they also can be used as a method to verify the numerical results. Effects of stresses induced by air–arc cutting process on the initial residual stress fields of base materials are also researched. The results show that the cooling velocity in HAZ is higher than the one of the welding process for the same base material, and the zone with high temperature is very narrow, which means that the temperature gradients near the groove are very steep during the air–arc cutting process; this special temperature field depresses multiphase transformations and coarse microstructures. The evolution of the stress during the air–arc cutting is described, and the numerical results indicate that the characteristics of the evolution of stresses and the residual stresses distribution in the plate in air–arc cutting process seem to be similar to the ones of the butt welding for flat plates. The influences of air–arc cutting process on initial stress fields present two aspects: thermal effect and material removal effect, and the former plays a primary role. Both numerical temperature and stress fields are compared with the experimental ones. It is very important for researchers to clarify the temperatures, stresses and microstructures in the plate during air–arc cutting process, and understand fully the mechanism of influences of air–arc cutting on the plate; it is also very valuable for engineering application of the air–arc cutting process. 相似文献
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《Materials & Design》2005,26(6):508-516
Due to their higher welding speed, automation and weld pool protection against to the atmosphere gases, gas metal arc welding (GMAW) process is widely used in industry. Due to the less stable arc associated with the use of consumable electrodes, GMAW process is not clean as good as gas tungsten arc welding process. Furthermore, the greater arc length in GMAW process also reduces the protective effect of the shielding gas. Due to electrochemical and thermochemical reactions between weld pool and arc atmosphere, it is quite important, especially weld metal toughness and joining of reactive materials to entirely create inert atmosphere for GMAW process. Therefore, a controlled atmosphere cabinet was developed for GMAW process. Low carbon steel combinations were welded with classical GMAW process in argon atmosphere as well as controlled atmosphere cabinet by using similar welding parameters. The mechanical and metallurgical properties of both weldments were evaluated. Result shows that toughness of the weld metal that was obtained in the controlled atmosphere cabinet much higher than that of classical GMAW process. The metallographic examination also clarified that there was not any gas porosity and inclusion in the weld metal compared with classical process. 相似文献
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本文详细分析了粗丝CO_2气体保护潜弧焊熔滴过渡的特点和潜弧机理。潜弧状态可以分为三种类型:半潜弧(熔滴主要以较大的颗粒形式过渡)、临界潜弧(熔滴主要以较小颗粒的射滴形式过渡)和深潜弧(熔滴以细小射滴与射流混和形式过渡)。大电流、低电压、粗焊丝、反极性和氧化性气氛是形成潜弧过程的必要条件,其中电流是最重要的条件。潜弧后弧柱气氛改变,焊丝端部的弧根由集中形态扩展为覆盖整个端部形态,使得熔滴尺寸变得细小,熔滴过渡形式发生变化。采用临界潜弧区域的焊接规范参数施焊,飞溅小,工艺过程稳定,焊缝成形优良。 相似文献
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Guo-Jian He Lin Gu Ying-Mou Zhu Ji-Peng Chen Wan-Sheng Zhao K. P. Rajurkar 《先进制造进展(英文版)》2022,10(4):583-595
Electrical arc contour cutting (EACC) is a novel high-efficiency material cutting process that applies arc plasma to perform efficient and economical contour cutting of difficult-to-cut materials. Compared to conventional electrical arc machining (EAM), this process can remove the allowance of open structures and plates in bulk mode, rather than entirely in the form of debris. Compared with existing contour cutting methods, EACC possesses the advantages of high cutting efficiency and a deep cutting depth. Particularly, a compound arc breaking mechanism (CABM), which integrates hydrodynamic force and mechanical motion, has been applied to control the discharge arc column in EACC, while also strengthening the debris expelling effect in the narrow discharge gap. The CABM implementation conditions were studied, based on arc column distortion images captured by a high-speed camera and simulation results of the flow field and debris distribution. A set of machining experiments was designed and conducted to optimize the performance of the proposed process. Finally, a SiCp/Al metal matrix composite (MMC) space station workpiece was machined to verify the feasibility and efficiency of this process.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00406-0 相似文献
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Plasma deposition and etching processes are used for a wide range of applications as for example the production of semiconductor circuits, flat panel displays, solar cells, architectural glass and data storage media. To fulfill the special needs of each single process stable DC, MF and RF process power ranging from 50W to 200kW is needed. All generators need a high precision process control and a supreme arc management with adaptable parameters to provide minimal disturbances in the plasma process and to obtain optimized results in terms of film quality, homogeneity and uniformity over the whole substrate. The fast and flexible arc handling leads to an improvement in the film quality by minimizing flaws and defects and enables the use of very high sputter rates. To fit DC process demands a new concept for a modular DC system has been realized where up to four 30kW modules can be combined using master slave concept. The arc management and control of the DC module has an intelligent control enabling arc detection times of less than 1μs and a residual energy delivered to the process of only 6 mJ per kW. For MF processes a fast and effective arc management is an even more important tool for keeping reactive processes stable. The new generation of MF power supplies enables arc detection and shut off times of 5μs with a residual energy delivered to the process of only 5 mJ per kilowatt. This yields the additional advantage that even when the cathode material is almost used up and consequently the arc probability increases, the low residual energy values contribute to an extended service life of the cathode and to better utilization of the target material. Essentially, the outstanding feature of effective arc management is an undisturbed plasma during the whole operation time. The fast arc suppression minimizes the interruption in the sputtering process to negligibly small values. However, because arcs also serve to remove unwanted materials on the cathode, power supplies must be able to control and regulate the arc energy precisely. MF power supplies are available for process power up to 200kW. RF systems are based on two different concepts to fit the broad power range between 50W and 50kW. For the low energy range a fully transistorized and μC‐controlled RF generator was developed. This generator has been designed for a max. power of 3kW. Important features are the compact size, robustness, reliability and easy maintenance To have a cost effective design for a high power RF generator in this power range an oscillator ‐ amplifier concept has been chosen with a solid state driver in combination with a tube type end stage amplifier. To fit todays demands for advanced etching a dual frequency system consisting of a 13.6 MHz and a 3.4 MHz unit was developed. This enables the possibility to separately control plasma density and ion energy of the discharge. 相似文献
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目的 建立一种基于逆向成形的电弧增材制造表面质量评价方法,研究工艺参数对电弧增材表面质量的影响。方法 依据最小误差原则选用合适的函数建立理想模型,逆向成形各电弧增材试样并得到提取模型,比较提取模型与理想模型的差异,定量描述电弧增材试样表面的成形质量,分析电弧增材试样中缺陷出现的原因,评估各工艺参数对电弧增材试样表面质量的影响。结果 随着工艺参数的改变,电弧增材试样的宽度减小,高度增加,试样的标准偏差值在1.95~2.15之间,均平方根值在2.4~2.9之间。工艺参数经优化后,试样的标准偏差值和均方根值分别减小到1.738和1.878。结论 送丝速度和成形速度的匹配程度对电弧增材表面质量有较大影响,实际成形中出现的非理想情况在此方法的计算结果中均可得到反映,与实际成形情况较吻合。 相似文献
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Hybrid laser – metal active gas (MAG) arc welding is an emerging joining technology that is very promising for shipbuilding applications. This technique combines the synergistic qualities of the laser and MAG arc welding techniques, which permits a high energy density process with fit-up gap tolerance. As the heat input of hybrid laser – arc welding (HLAW) is greater than in laser welding, but much smaller than in MAG arc welding, a relatively narrow weld and restricted heat affected zone (HAZ) is obtained, which can minimize the residual stress and distortion. Furthermore, adding MAG arc can increase the penetration depth for a given laser power, which can translate to faster welding speeds or fewer number of passes necessary for one-sided welding of thick plates. In this work, a new hybrid fiber laser – arc welding system was successfully applied to fully penetrate 9.3 mm thick butt joints using a single-pass process through optimization of the groove shape, size and processing parameters. 相似文献
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Mechanism of Metal Transfer in DE-GMAW 总被引:1,自引:0,他引:1
Kehai Li) Chuansong Wu) ) Center for Manufacturing University of Kentucky Lexington Kentucky USA ) Institute of Materials Joining Sh ong University Ji nan China 《材料科学技术学报》2009,25(3):415-418
Modification of conventional gas metal arc welding (GMAW) process is of great potential to achieve high productivity with low cost and strong usability.Double-Electrode GMAW (DE-GMAW) is such a modified arc welding process which is formed by adding a bypass torch (gas tungsten arc welding torch) to a conventional GMAW system.The mechanism of metal transfer in DE-GMAW was proposed and verified in this paper.Experiments show that the critical current is decreased so that spray transfer can be obtained at a lower current level in DE-GMAW.Analysis of this significant change in metal transfer phenomena is conducted, and explanation is given out.It is found that the bypass arc in DE-GMAW lifts the anode point on the droplets such that the electromagnetic force becomes larger and squeezes the droplets so that spray transfer can take place under welding current lower than that in conventional GMAW. 相似文献