GMAW电弧等离子体电流密度及温度场分布测量

发布时间：2018-08-16 16:23

【摘要】：电弧诊断对于电弧理论模型的建立以及熔化极气保焊的改进和发展有着根本性的意义,其中最为重要的是对电流密度分布及温度场分布的诊断。本文分别以改进的分裂阴极法和激光干涉计量方法对熔化极气体保护焊(GMAW)电弧的电流密度分布及温度场分布进行了测量和计算。实验测得了电弧移动时绝缘的两极板上分布的电流,并对电流数据进行了拟合。利用拟合的电流进行计算,得出了GMAW电弧的电流密度分布呈现二阶高斯分布。电流密度随中心距而降低,边缘温度为中心温度的十分之一。实验中还发现电流密度分布曲线最后一点的电流密度很大,这是由于选取了有限的点和范围造成的。当认定电弧的半径为无限大时,该异常点就会消失。实验拍摄了不同焊接参数下的GMAW电弧全息干涉图,并给出了利用干涉图进行反演温度场分布的算法。GMAW电弧的温度场分布同样是二阶高斯分布的形式,其拟合优度可达0.99以上。随着中心距的增加,电弧等离子内部温度的下降趋势由陡峭变得舒缓。电弧温度场分布受到焊接电流、干伸长、保护气流量以及熔滴过渡阶段的影响。焊接电流升高时,电弧的半径增加,中心最高温度增加,边缘最低温度增加。温度下降速度及温度-中心距曲线与x轴包围的面积都随焊接电流增加而不同程度变大。而干伸长及保护气流量的增加一方面会增加电弧中心温度,另一方面却会导致电弧边缘温度降低。二者都会导致温度随中心距的下降速度变慢。不同的熔滴过渡阶段亦会对电弧温度场分布造成影响,这主要与电弧的建立及熔滴过渡时带走电弧的热量有关。在这些阶段中,电弧等离子体将不再满足电离平衡假设。
[Abstract]:Arc diagnosis is of fundamental significance for the establishment of arc theoretical model and the improvement and development of gas shielded welding of molten electrode. The diagnosis of current density distribution and temperature field distribution is the most important one among which the most important is the diagnosis of current density distribution and temperature field distribution. In this paper, the current density distribution and temperature field distribution of (GMAW) arc in gas shielded electrode welding are measured and calculated by the improved split cathode method and laser interferometry method respectively. The current distribution on the insulating bipolar plate is measured experimentally and the current data are fitted. The current density distribution of GMAW arc is found to be the second order Gao Si distribution by using the fitted current. The current density decreases with the center distance, and the edge temperature is 1/10 of the center temperature. It is also found that the current density at the last point of the current density distribution curve is very large, which is due to the selection of limited points and ranges. When the arc radius is determined to be infinite, the anomaly will disappear. The holographic interferogram of GMAW arc with different welding parameters is photographed experimentally. The algorithm of inversion of temperature field distribution by interferogram is given. The temperature field distribution of GMAW arc is also the form of second-order Gao Si distribution, and the fitting result is above 0.99. As the center distance increases, the arc plasma internal temperature declines from steep to slow. The distribution of arc temperature field is affected by welding current, dry elongation, protective gas flow and droplet transfer stage. When the welding current increases, the arc radius increases, the center maximum temperature increases, and the edge minimum temperature increases. The temperature drop velocity, the temperature-center distance curve and the area surrounded by the x axis increase with the increase of welding current. The increase of dry elongation and shielding gas flow will increase the center temperature of the arc on the one hand and decrease the temperature at the edge of the arc on the other. Both will cause the temperature to slow down with the center distance. The temperature distribution of the arc is also affected by the different droplet transfer stages, which is mainly related to the establishment of the arc and the heat taken away from the arc during the droplet transfer. At these stages, the arc plasma will no longer satisfy the ionization equilibrium hypothesis.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG444.7

【相似文献】