送丝方式对步进填丝双脉冲TIG电弧增材成形精度的影响

针对电弧增材制造热质传输强耦合、成形尺寸精度低等共性关键问题，提出一种步进填丝双脉冲钨极氩弧(tungsten inert gas，TIG)电弧增材制造方法. 基于此方法建立增材成形试验系统，开展系列变化参数的直壁墙增材工艺试验. 利用同步采集的熔滴、熔池动态变化图像数据重点研究分析了送丝方式对焊丝熔化、熔滴过渡、熔池行为和成形尺寸精度的影响规律. 结果表明，前、后送丝方式下熔滴均以液桥过渡方式熔入到熔池；相比前送丝增材过程，后送丝方式下焊丝熔化效率和熔滴过渡频率明显增加，熔滴尺寸变小，熔池表面高度和宽度尺寸波动均减小；高频脉冲电弧使熔池体积略微增加，热稳定性明显增强，直壁墙沉积件成形精度明显提高.

Effect of wire feeding mode on additive forming precision of double-pulsed TIG process with stepped filling wire

To resolve the main issues of wire arc additive manufacturing, including the unstable heat and mass transfer, strong arc coupling and poor formation etc., a double-pulsed tungsten inert gas (TIG) with stepped filling wire additive manufacturing method was proposed. A series of deposited straight wall experiments with variable parameters were carried out. The image and thermal data of the droplet and weld pool surface were sampled simultaneously during the deposition process. The influence of wire feeding mode on the welding wire melting, droplet transition and molten pool behavior as well as the causes of the influence on the forming accuracy were analyzed in detail. The results show that the droplet transfer mode is the liquid bridge transfer in both the rear and lead wire feeding modes. Compared with the lead wire feeding process, in the rear wire feeding condition, the wire melting efficiency increases, the droplet transfer size decreases, the change of the molten pool height and width decreases, and the thermal stability is enhanced.The volume of molten pool is slightly increased by high-frequency pulsed arc. The straight wall deposition parts with high forming accuracy are obtained finally.