锂离子电池外壳光纤激光焊气孔的分析

Study on the porosity of fiber laser welding for casing of Li-ion battery

采用准连续光纤激光焊对锂离子电池外壳进行密封焊接,使用v|tome|x s 240检测焊缝内气孔的等效直径、球度及体积率,对气孔的等效直径和球度进行统计分析与正态分布拟合,还研究了工艺参量对气孔的体积率及形貌的影响。结果表明:锂离子电池外壳焊接为激光传导焊,主要产生冶金型气孔,冶金型气孔中既有近似球形的小气孔,又有由2个以上的小气孔合并贯穿而形成的不规则的大气孔;铝壳焊缝中气孔尺寸集中在250~550μm之间,球度在0.6~0.7之间;随着激光功率的降低和焊接速度的增加,气孔的体积率呈下降趋势,但气孔形貌即球度未发生明显改变;当激光功率为450 W,焊接速度为1500 mm/min时,气孔体积率最小为1.1%。

The QCW fiber laser welding was used for casing of Li-ion power battery. The effective diameter, sphericity and volume rate of porosity were observed by using v|tome|x s 240. The effective diameter and sphericity of porosity were statistically measured and fitted. The effect of process parameters on the volume rate and morphology of the porosity were studied. It showed that laser welding for casing of Li-ion power battery was heat-conduction welding, the weld pore was produced by metallurgical reactions. There were two types of pore in welding, i.e. small spherical pores and irregular large pores which were composed of more than two small pores. The size of welding porosity was between250~550 μm, the sphericity of porosity was between 0.6 to 0.7, the volume rate of porosity would reduce by lower laser power and higher welding speed, but the sphericity of porosity would not change by process parameters. The volume rate of porosity reached its minimum as 1.1% when the laser power was 450 W and the welding speed was1500 mm/min.