变极性等离子弧焊电弧物理特性的数值模拟
发布时间：2018-10-21 11:05
【摘要】：基于磁流体动力学及Maxwell方程组,建立了变极性等离子电弧的三维瞬态计算模型,依据变极性等离子弧焊对铝合金板材穿孔焊接过程的物理特性,提出了随电弧极性变化的分时导电模型,通过计算得到了变极性等离子电弧的温度场、流场、电流密度和电弧压力的分布情况,以及电弧压力随时间的变化过程。通过实验测量了工件表面电弧中心压力,得到了不同极性时的电弧形态。结果表明:相同电流条件下,正极性时电弧温度场分布比反极性时更加分散,但正极性时电弧最高温度范围小于反极性时;反极性电弧压力和电流密度在电弧中心处均大于正极性,在径向距电弧中心一定距离处,2种极性时的电弧压力和电流密度的大小出现反转;电弧压力对焊接电流响应迅速,正极性电弧压力小于反极性电弧压力,焊接电流过零时,电弧压力会降低到较低的值,电流增加时电弧压力变化存在"过冲"现象;对实验与计算得到的变极性等离子电弧正反极性时电弧图像和工件表面电弧中心压力进行了对比,结果吻合良好。
[Abstract]:Based on magnetohydrodynamics and Maxwell equations, a three-dimensional transient calculation model of variable polarity plasma arc is established. According to the physical characteristics of the process of variable polarity plasma arc welding for aluminum alloy sheet perforation welding, the three dimensional transient calculation model of variable polarity plasma arc welding is established. A time-sharing conduction model with arc polarity is proposed. The temperature field, current density and arc pressure distribution of the plasma arc with variable polarity are calculated, as well as the variation process of arc pressure with time. The arc central pressure on the surface of the workpiece was measured experimentally, and the arc shape was obtained with different polarity. The results show that the distribution of arc temperature field in the positive polarity is more dispersed than that in the reverse polarity under the same current condition, but the maximum temperature range of the arc in the positive polarity is smaller than that in the reverse polarity. The reverse arc pressure and current density are larger than the positive electrode at the center of the arc. At a certain distance from the center of the arc, the arc pressure and current density of the two polarities are reversed, and the arc pressure has a rapid response to the welding current. The positive arc pressure is smaller than the reverse arc pressure. When the welding current is over 00:00, the arc pressure will be reduced to a lower value, and the arc pressure will overshoot when the current increases. The arc images obtained by experiments and calculations for the positive and negative polarity of variable polarity plasma arc are compared with the arc central pressure on the surface of the workpiece. The results are in good agreement with each other.
【作者单位】： 北京工业大学机电学院汽车结构部件先进制造技术教育部工程研究中心;
【基金】：国家自然科学基金项目No.51505008 国家科技重大专项项目No.2014ZX04001-171~~
【分类号】：TG456.2
[Abstract]:Based on magnetohydrodynamics and Maxwell equations, a three-dimensional transient calculation model of variable polarity plasma arc is established. According to the physical characteristics of the process of variable polarity plasma arc welding for aluminum alloy sheet perforation welding, the three dimensional transient calculation model of variable polarity plasma arc welding is established. A time-sharing conduction model with arc polarity is proposed. The temperature field, current density and arc pressure distribution of the plasma arc with variable polarity are calculated, as well as the variation process of arc pressure with time. The arc central pressure on the surface of the workpiece was measured experimentally, and the arc shape was obtained with different polarity. The results show that the distribution of arc temperature field in the positive polarity is more dispersed than that in the reverse polarity under the same current condition, but the maximum temperature range of the arc in the positive polarity is smaller than that in the reverse polarity. The reverse arc pressure and current density are larger than the positive electrode at the center of the arc. At a certain distance from the center of the arc, the arc pressure and current density of the two polarities are reversed, and the arc pressure has a rapid response to the welding current. The positive arc pressure is smaller than the reverse arc pressure. When the welding current is over 00:00, the arc pressure will be reduced to a lower value, and the arc pressure will overshoot when the current increases. The arc images obtained by experiments and calculations for the positive and negative polarity of variable polarity plasma arc are compared with the arc central pressure on the surface of the workpiece. The results are in good agreement with each other.
【作者单位】： 北京工业大学机电学院汽车结构部件先进制造技术教育部工程研究中心;
【基金】：国家自然科学基金项目No.51505008 国家科技重大专项项目No.2014ZX04001-171~~
【分类号】：TG456.2
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4 石s，
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