Dual-wire additive manufacturing (AM) couples traditional wire-based AM for part fabrication and the molten pool metallurgy for material-preparation with high deposition efficiency and material utilization. However, compared with traditional single-wire AM technology, it has a more complex and sensitive dual-droplet transition distance (TD), which not only affects the forming quality but also the metallurgical quality. Therefore, it is necessary and urgent to monitor and control its TD value online. In this study, we systematically investigated the sensing, controlling, and influential mechanism of the TD value in dual-wire AM technology, and Ti₂AlNb was taken as the target alloy owing to its great application prospects in the aerospace field. Specifically, a deposition experiment with different initial TD value was conducted to study the effect on the morphology and composition distribution of the as-printed part. Based on the optimal distance, the related image extraction algorithms and closed-loop control methods are developed. The closed-loop controlled verification experiment on the slope and step substrate, as well as the multi-layer deposition test, were carried out and analyzed. The results indicate that the developed system can control the TD to the desired value with good robustness. In addition, the controlled deposited multi-layer part exhibited good morphology and composition homogenizing in the post-characterization experiment. This study is of great significance for the intelligent and industrial development of dual-wire AM technology.

双线增材制造 (AM) 将用于零件制造的传统线材增材制造与用于材料制备的熔池冶金相结合，具有高沉积效率和材料利用率。然而，与传统的单线增材制造技术相比，它具有更加复杂和敏感的双熔滴过渡距离（TD），这不仅影响成形质量，而且影响冶金质量。因此，对其TD值进行在线监测和控制是必要且紧迫的。在本研究中，我们系统地研究了双线增材制造技术中TD值的传感、控制和影响机制，并选择Ti ₂ AlNb作为目标合金，因为它在航空航天领域具有巨大的应用前景。具体来说，进行了不同初始TD值的沉积实验，以研究对打印零件的形貌和成分分布的影响。基于最佳距离，开发了相关的图像提取算法和闭环控制方法。对斜坡和台阶基板进行了闭环控制验证实验以及多层沉积实验并进行了分析。结果表明，所开发的系统可以将TD控制到期望值，并且具有良好的鲁棒性。此外，受控沉积多层部件在后表征实验中表现出良好的形貌和成分均质化。该研究对于双线增材制造技术的智能化和产业化发展具有重要意义。