纵向磁场作用下的钨极氩弧焊电弧温度场

摘要

通过采集钨极氩弧焊电孤单色图像,采用Fowler-Milne法得到了纵向磁场作用下的电弧温度场,研究了磁感应强度、焊接电流和弧长对电弧温度场的影响.结果表明:在纵向磁场作用下,电弧温度整体降低,电孤体下部出现低温腔；电孤温度场受磁感应强度、焊接电流及弧长的影响.结合电弧图像及温度场在纵向磁场作用下的变化规律,对纵向磁场作用下电弧的演变过程进行了描述:随着磁感应强度增大,在洛仑兹力与自磁收缩力的共同作用下电弧出现先扩张后收缩的现象；随着弧长变长,低温腔变大,阳极附近电孤中心温度变低,且温度半径变大；随着焊接电流的增大,电孤作用半径及电弧的温度半径变大.%By the spectral images of arc, the temperature field of welding arc in longitudinal electromagnetic field (LEMF) is revealed with Fowler-Milne method. It is shown that LEMF makes the temperature of arc getting lower, and a low-temperature cavity appears in the underpart of arc body. The influences of magnetic flux density, arc length, and welding current on the temperature field are discussed. The arc evolution process for different magnetic flux density is explained according to the changing regularity of arc images and temperature field. With the increasing magnetic flux density, the arc expands firstly then contracts due to the resultant of Lorenz force and self-magnetic contracting force. When the arc length gets longer, the low-temperature cavity becomes bigger, the radius of temperature near the anode increases, and the temperature gets lower at the arc centre. Both the radius of arc body and the radius of temperature field increase with the strengthening welding current.