受控脉冲穿孔等离子弧焊接(PAW)过程中, 小孔形状随焊接电流动态变化,经历“形成-长大-缩小-闭合”的变化过程. 本文在对受控脉冲PAW瞬态温度场进行数值模拟的基础上, 通过分析焊接熔池表面的受力状态,建立了小孔形状的模型, 考虑了盲孔(小孔深度小于工件厚度)和穿透小孔2类情况.对焊接熔池内三维小孔在一个脉冲周期内的变化过程进行了数值计算.进行了受控脉冲PAW工艺实验, 验证了穿孔持续时间的数值分析结果.
During the controlled pulse key–holing plasma arc welding (PAW), keyhole shape and size change with the welding current dynamically, and undergo variation of the "establishing–expanding–contracting–closing" process. Numerical analysis on such dynamic variation process of keyhole shape and size can provide insight into the process mechanism and basic data for optimizing the process parameters. In this study, a three–dimensional transient model is developed to conduct numerical simulation of welding temperature field, weld pool geometry, and keyhole shape and size in controlled pulse PAW. The keyhole shape and size are computed by analyzing the force–action on the weld pool surface, and two situations are considered to deal with partial keyhole and open keyhole. The dynamic variation features of three–dimensional keyhole shapes in weld pool in a pulse cycle are numerically calculated. Experiments are conducted to validate the numerical simulation result of key–holing duration.
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