车用薄镀锌板CMT搭接工艺特性

针对车用薄镀锌板材料，为了进一步降低冷金属过渡(cold metal transfer,CMT)时产生的飞溅，研究分析了薄镀锌板CMT搭接焊接工艺特性.采用Baumer HX 13工业级高速摄像机拍摄了CMT焊接熔滴过渡图像，利用NI PXI数据采集系统采集了CMT焊接电流电压信号.主要研究了短路前期阶段与短路后期阶段电流电压对CMT熔滴过渡的影响规律，同时分析了焊枪倾角对薄镀锌板CMT搭接焊接熔滴过渡行为的影响.结果表明，当CMT短路阶段电流小于基值阶段电流时，电信号波形未出现扰动现象，焊接过程稳定；当降低短路后期电流约5 A时，能够有效降低CMT搭接产生的飞溅；当焊枪与垂直平面呈30°夹角时，能够获得平稳的熔滴过渡，焊接飞溅最小，焊缝熔深最大，焊缝成形最佳.故短路阶段电流小于基值阶段电流且降低短路后期电流约5 A时，采用焊枪倾角30°的焊接工艺能够实现较小的焊接飞溅，为生产实践提供理论依据.

Characteristics of CMT lap joint process for thin galvanized sheet for vehicles

In order to further reduce the spatter generated during cold metal transfer (CMT), the characteristics of CMT lap welding process of thin galvanized sheet were studied and analyzed for automotive thin galvanized sheet materials. Baumer HX 13 industrial high-speed camera was used to capture the CMT welding droplet transition images, and the CMT welding current and voltage signals were collected using NI PXI data acquisition system. The influence of current and voltage on the droplet transfer of CMT in the early stage and late stage of short circuit is mainly studied, and the influence of welding gun inclination on the droplet transfer behaviour of CMT lap welding of thin galvanized sheet was analysed. The results show that when the current in the short-circuit stage of CMT is less than the base stage current, there is no disturbance in the current and voltage waveform, and the welding process is stable. When the current at the later stage of short circuit is reduced by about 5 A, the spatter generated by the CMT lap can be effectively reduced. A smooth droplet transition can be obtained with minimum welding spatter, maximum weld depth of fusion and best weld formation when the torch is at an angle of 30° to the vertical plane. Therefore, when the short-circuit phase current is less than the base stage current and the short-circuit current is reduced by about 5 A, the welding process with 30° welding gun inclination can achieve less metal splash, providing a theoretical basis for production practice.