激光-变极性等离子弧(Laser beam-variable polarity plasma arc,LB-VPPA)属双高能束新型复合焊接热源。采用Y4-S2型高速摄像检测了LB-VPPA复合焊接热源形态,在理论分析复合热源产热机理的基础上,利用Fortran语言对SYSWELD软件热源模型进行二次开发,建立能够实现正、反极性循环加载的LB-VPPA复合焊接热源模型。经与实际焊接熔池形状对比研究发现,熔池上部采用双椭球体热源,下部采用三维锥体热源,同时在小孔根部植入圆柱体热源的组合式热源模型与实际LB-VPPA复合焊接热源吻合。从模拟6 mm厚7A52铝合金板的VPPA焊和LB-VPPA复合焊接温度场分布结果发现,LB-VPPA复合焊能量更为集中,可以在平焊位置下实现穿孔型焊接。经实际焊接工艺试验验证了上述模拟结果的准确性。因此建立精确的LB-VPPA复合焊接热源模型对开展厚板铝合金LB-VPPA复合高效焊接提供强有力的理论支持。
Laser beam-variable polarity plasma arc(LB-VPPA) hybrid welding belongs to New type of welding heat source with double high energy beam. Arc shape of LB-VPPA hybrid welding is analyzed by Y4-S2 high-speed camera, Based on mechanism of the hybrid heat source, heat source model of LB-VPPA hybrid welding, which is developed secondarily by Fortran language in SYSWELD software, is set up to achieve positive and reverse polarity cycle loading. Compared with the actual welding molten pool shape, the hybrid heat source model is combinded by double ellipsoid heat source in the upper part of weld pool and 3-D conical heat source with cylindrical heat source at keyhole in the lower part, the results show that the combinded heat source model meets with the actual hybrid heat source. The VPPA welding and LB-VPPA hybrid welding temperature field of the 6mm thickness 7A52 aluminum alloy is simulated by SYSWELD, This demonstrated LB-VPPA hybrid welding has obvious advantage in energy concentration, so it can keyhole welding at the flat position. Accuracy of the numerical simulations are proved by the comparison of the actual welding experiment and the simulation results. Therefore, heat source model of LB-VPPA hybrid welding is established accurately, it can provide strongly support for LB-VPPA hybrid welding of thick aluminum alloy.
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