基于外加高频交变磁场下向MAG焊熔池成形控制

Downward Welding Pool Shape Control Based on Exterior High Frequency Alternative Magnetic Field

近年来,下向熔化极活性气体保护焊(Metal active gas,MAG)在石油化工、管道工程等工业中获得广泛应用,但是下向MAG焊中当焊接熔池体积增大时由于其所处空间位置受重力因素影响较大,易产生熔池失稳问题,影响到焊缝的良好成形。针对上述问题开展下向焊熔池力学行为分析和熔池成形的控制策略研究,提出一种对下向MAG焊接熔池施加高频交变磁场,利用该磁场的电涡流效应产生电涡流力来抵消熔池液态金属重力分量的方法,达到克服重力对熔池成形的不利影响。开展熔池外加高频交变磁场熔池内部电磁场、涡流场和电涡流力的数值模拟和分析。进行45°和90°下向焊试验,对上述理论分析进行试验验证,结果表明高频交变磁场对熔池流淌具有抑制作用,采用电涡流技术用于克服下向MAG焊中的熔池失稳方案是可行的。

Recent years, downward welding is used widely more and more in petrochemical, pipeline engineering and so on. However, with the increase in volume of weld pool during downward welding, weld pool becomes instable because of influence of gravity, even affecting the good bead shape. Weld pool mechanical behavior and the control strategy of the weld pool forming is analyzed and researched, on the base, a method is proposed in the welding that the Lorenz force produced to overcome bad effect of gravity component when the weld pool is exposed to exterior high frequency alternative magnetic field. The numerical simulation on electromagnetic field, eddy current field and electromagnetic force in the interior of weld pool are implemented. 45 degree and 90 degree downward welding experiments are carried out to verify the theory analysis. Experiment results show that it is feasible for using eddy current technology to overcome weld pool instable resulted by gravity component in downward metal active gas（MAG） welding.