Research Initiation Award: Scan Welding; Process Modeling and Adaptive Control

传统的焊接方法具有顺序移动的局部热输入，对焊接质量和生产率的多个特征提供有限的同时控制。这项研究将集中在发明一种新的平行技术-扫描焊接，通过沿焊接表面快速重复循环焊枪来提供有规律的连续热分布。这种新方法将同时产生完整的焊缝长度，并产生纵向均匀的焊缝热性能。通过对扫描焊接温度场、相变场和应力应变场的解析和数值模拟，研究了扫描焊接的动力学过程。在此基础上，设计了具有过程参数辨识的分布式自适应控制系统，对火炬的功率和运动进行调制，以获得指定的热场。扫描焊接也将在机器人等离子焊接系统上实施，红外高温计提供热反馈，并将进行模型验证和扫描焊接与传统技术的比较。预期的优点包括加工速度和效率高，消除了预热和退火要求，并对焊道几何形状、材料组织和性能以及接头的残余应力和变形进行了密切的同步控制。这些优点为优化焊接生产率和质量提供了潜力，尤其是在关键和高要求的应用中。

Traditional welding methods with a sequentially moving, localized heat input, offer limited simultaneous control over the multiple features of weld quality and productivity. This research will focus on the invention of a novel parallel technique, scan welding, implemented by fast repetitive cycling of the torch along the weld surface to provide a regulated continuous heat distribution. This new method will produce the full bead length simultaneously, and yield longitudinally uniform thermal properties of the weld. The dynamics of scan welding will be studied by analytical and numerical modeling of its temperature, phase and stress-strain field. On this basis, a distributed adaptive control system with in-process parameter identification will be designed to modulate the torch power and motion, so as to obtain the specified thermal field. Scan welding will also be implemented on a robotic plasma welding system with thermal feedback from an infrared pyrometer, and experiments will be performed for model verification and comparison of scan welding to conventional techniques. The expected advantages include high process speed and efficiency, elimination of preheat and annealing requirements, and close simultaneous control of weld bead geometry, material microstructure and properties, and residual stresses and distortions of the joint. These benefits provide the potential for optimization of the welding productivity and quality, especially in critical and highly demanding applications.