环境压力对GMAW电弧能量耗散的影响

Effect of ambient pressure on energy dissipation of GMAW arc

能量对电弧行为具有重要影响,开展高压环境下GMAW电弧能量耗散研究对指导焊接工艺和提升电弧稳定性具有重要意义.电弧的能量损失难以直接测量,为此创建以电弧中心一定距离的圆柱面的热流量作为参考,比较不同压力GMAW电弧的能量损失,基于流体力学和传热学理论,建立高压GMAW数值分析模型,计算电弧局部区域对外能量传输情况.建立了高压GMAW能量耗散测量试验平台,通过采集1/16圆柱面的能量传输量进行换算,获得整个圆柱面的能量传输情况,并采用圆管自然对流传热模型,对测量结果加以修正.将模拟和试验结果对比,分析环境压力对电弧能量耗散的影响规律.结果表明,随着环境压力增加,GMAW电弧局部区域对外能量耗散量增加,导致电弧高温区域向电弧中心聚集,电弧表现为收缩现象.同时随着环境压力的升高,处于阴极区附近的电弧能量耗散更大,阴极区电弧收缩更为明显,成为高压GMAW电弧趋于不稳定的诱因之一.

The behavior of arc is affected deeply by energy.The study on energy dissipation of GMAW arc in high pressure environment is of great importance to guide welding process and improve arc stability. The energy loss of the arc is difficult to be measured directly. Therefore, the heat flow of the cylinder at a certain distance from the center of the arc is used as a reference to compare the energy loss of GMAW arc under different pressures. Based on the hydrodynamics and heat transfer theory, a numerical analysis model of the high pressure GMAW was established to calculate the external energy transmission of the local area of the arc. The experimental platform of high pressure GMAW energy dissipation measurement was established, and the energy transmission of the whole cylinder was obtained by collecting the energy transmission amount of 1/16 cylinder for conversion, and the measured results were corrected by using the natural convection heat transfer model of the circular tube. The influence of ambient pressure on arc energy dissipation is analyzed by comparing the simulation and experiment results. The results show that the external energy dissipation of GMAW arc increases, The high temperature region of the arc gathers towards the center of the arc, and the arc appears to shrink at the same time. with the increase of ambient pressure, the energy dissipation of the arc near the cathode region enhances more, and the arc shrinkage in the cathode region is more obvious, which is one of the inducement of the instability of the high voltage GMAW arc.