纵向磁场频率对TIG焊电弧特性的影响

发布时间：2018-07-10 00:04

本文选题：电弧特性 + 纵向磁场　；参考：《沈阳工业大学》2015年硕士论文

【摘要】：TIG焊因焊接性良好，无飞溅等优点，被广泛应用于核电站及航空航天等重要领域。但TIG焊电弧能量分散，电弧力小以及钨极受许用电流的影响，导致焊缝熔深浅，限制了该焊接方法在中厚板以及高效化方面的应用。本文在TIG焊电弧周围施加纵向磁场，以改变电弧特性，提高电弧能量密度，从而增大焊缝熔深，进而实现高效化及高质量焊接。本课题将低频、高频磁场结合，研究了磁场频率的变化对焊接电弧特性影响规律；利用高速摄像装置对TIG焊电弧形态进行拍摄；利用自制水冷铜阳极测试电弧压力径向分布；利用自制环形同心分裂阳极装置测试电弧热量分布；采用探针法测试电弧电流密度径向分布。通过测试不同磁场频率作用下电弧压力、电流密度及电弧热量分布等特性，并与传统TIG电弧特性进行对比，从而得到了磁控TIG焊的最佳焊接磁场参数。实验结果表明：焊材为铜板时，且外加直流或低频磁场作用下，电弧形态由锥形变为钟罩型；电弧压力分布由正态分布变为环形双峰分布，随着磁场频率的提高，环形双峰奇异消失；电流密度分布与电弧压力具有相同变化特征。在外加高频磁场作用下，电弧形态由钟罩型变为柱形；电弧中心压力与传统电弧压力相比大幅提高；电流密度分布与电弧压力具有相同变化特征。焊接电流有效值为70A，磁感应强度为30mT，磁场频率为1200Hz左右时，稳定燃烧的TIG焊接电弧高速旋转的旋转半径最小，电弧中心压力从自由电弧时的0.29KPa增大为0.44KPa，，热量分布系数从自由电弧时的34.5%升高到52.9%，电流密度由18A/mm2提高到50.2A/mm2。高频磁场作用下的焊接电弧产生了磁压缩现象。
[Abstract]:TIG welding is widely used in nuclear power plants, aerospace and other important fields because of its good weldability and no spatter. However, TIG welding arc energy is dispersed, arc force is small and tungsten electrode is affected by allowable current, which leads to shallow weld melting depth, which limits the application of this welding method in medium and thick plate and high efficiency. In this paper, the longitudinal magnetic field is applied around the arc of TIG welding to change the characteristics of the arc and increase the energy density of the arc, so as to increase the weld penetration and achieve high efficiency and high quality welding. In this paper, we combine low frequency and high frequency magnetic field to study the influence of magnetic field frequency on welding arc characteristics; use high speed camera to photograph TIG welding arc shape; use self-made water-cooled copper anode to test arc pressure radial distribution; The arc heat distribution was measured by a self-made ring concentric split anode device, and the radial distribution of arc current density was measured by the probe method. By measuring the characteristics of arc pressure, current density and arc heat distribution under different magnetic field frequencies, and comparing with the traditional TIG arc characteristics, the optimum magnetic field parameters of magnetically controlled TIG welding are obtained. The experimental results show that the arc shape changes from conical to bell cover when the welding material is copper plate and the applied DC or low frequency magnetic field is applied, the arc pressure distribution changes from normal distribution to circular double peak distribution, and with the increase of magnetic field frequency, the arc shape changes from normal distribution to annular bimodal distribution. The annular bimodal singularity disappears, and the current density distribution has the same characteristics as the arc pressure. Under the action of high frequency magnetic field, the arc shape changed from bell-shaped to cylindrical, the central pressure of arc increased significantly compared with the traditional arc pressure, and the current density distribution and arc pressure had the same change characteristics. When the effective value of welding current is 70A, the magnetic induction intensity is 30mTand the frequency of magnetic field is about 1200Hz, the arc rotation radius of stable combustion TIG welding arc at high speed is the smallest. The central pressure of the arc increases from 0.29 KPA to 0.44 KPA, the heat distribution coefficient increases from 34.5% to 52.9, and the current density increases from 18A/mm2 to 50.2 A / mm2. The welding arc under the action of high frequency magnetic field produces the phenomenon of magnetic compression.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG444.74

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