Active In-Process Control and Fabricating Precision Improvement of Weld Distortion by Using Temperature Distribution Control

众所周知，为了保证材料的可焊性、结构的可加工性和结构的完整性，评估焊接变形和残余应力是很重要的。为了控制焊接结构的尺寸，降低焊接结构的制造成本，焊接变形的预测和减小是必不可少的。因此，从制造效率的角度来看，焊接变形的过程控制比焊后纠偏或其他方法更可取。预测焊接变形和残余应力的方法有很多，这些方法对于开发控制焊接变形和残余应力的在线方法是有用的。通过热弹塑性分析，可以计算不同焊接条件和不同焊接结构形式下的焊接变形和残余应力。采用机械预应变、冷却、优化焊接顺序或振动等方法对S残馀…进行了试验研究在焊接中更多地控制应力。传统的焊接变形过程控制是通过使用拘束、弹性预应变、预热、预热或/和拉伸、或通过冷却进行热控制来实现的。这些方法已经应用于实际的焊接结构中，但由于这些技术大多只是针对特定条件下的经验建立的，因此减少焊接变形的机理还没有完全被研究。当考虑到防止变形所需的设备和通用性时，最容易减少焊接变形的方法是过程中的热控制。因此，在实际应用中，除焊枪外，通过使用加热或冷却源来控制焊接变形被认为是非常实用的。通过实验和焊接接头三维热弹塑性有限元分析，验证了该过程控制方法的有效性。通过研究减小焊接变形的机理，确定了合适的工艺条件，验证了焊接过程中方法的有效性。较少

It is well known that evaluating welding distortion and residual stress is important in order to assure material weldability, structural fabricability, and structural integrity. Prediction of welding distortion and its reduction are essential in order to control dimensions and reduce the fabrication cost of welded structures. Therefore, from the viewpoint of manufacturing efficiency, in-process control of welding distortion is more desirable than post-welding rectification or other methods. There are many methods for predicting welding distortion and residual stress, and they are useful for developing an in-process method for controlling weld distortion and residual stress. Welding distortion and residual stress can be calculated under various welding conditions and for various configurations of welded structures by the thermal elastic-plastic analysis. Methods using mechanical prestraining, cooling, optimizing the welding sequence, or using vibration have been developed for residual s … More tress control in welding. Conventional in-process control of weld distortion is performed by using restraint, elastic prestraining, preheating, preheating or/and stretching, or heat control by cooling. These methods have been applied to actual welded structures, but the reduction mechanism-of welding distortion has not been completely studied because most of these techniques were only experientially established for specific conditions. The easiest way to reduce welding distortion is in-process heat control, when both the equipments needed to prevent distortion and the applicability to general purpose are considered. Therefore, in-process control of welding distortion by using a heating or cooling source in addition to the welding torch is considered to be very practical for actual use. The effectiveness of the in-process controlling method is verified by experiment and by three-dimensional thermal elastic-plastic finite element analysis in a welded joint. The appropriate conditions are determined through studying the mechanism by which welding distortion is reduced, and the effectiveness of the in-process method during welding is finally validated. Less