激光增强水下MIG焊接熔滴过渡控制的机理与特性研究

Offshore oil ＆ gas development and nuclear power plant construction is currently the main energy development direction of China, maintains of submarine pipelines and nuclear power facilities urgently need advanced underwater welding technology as support. MIG welding is the main development direction because of its high efficiency and easy to realize automatic underwater welding.But due to the underwater environment influence, stability of welding process is poor and good metal transfer state is difficult to achieve,so the current research and application is restricted. This project aims to using the laser recoil pressure as an auxiliary detaching force to detach the droplet by introduce laser into underwater MIG welding process, and achieve a stable and controllable MIG welding metal transfer mode at a lower welding current by regulating laser parameters,establish a model to correlate metal transfer variables with laser parameters,ambient pressure and welding current.For laser enhanced metal transfer,image processing algorithms will be developed to extracting clear edge of the droplet and calculating its size. A arc sound signal sensing system will be established to study the relativity between arc sound signal and laser enhanced MIG welding metal transfer mode.The research result will enrich the connotation of underwater welding theory research,and lay the foundation for a stable underwater MIG welding metal transfer and its precision closed loop control.

海洋油气开发及核电建设是目前中国能源发展的主要方向，海底管道及核电站内部设施的修复急需先进的水下焊接技术作为支撑。MIG焊具有高效率和便于实现自动化等优点，是水下焊接主要发展方向，但其受水下环境影响显著，焊接过程稳定性差，良好熔滴过渡状态难以实现，因此目前研究和应用受到较大限制。本项目拟通过在水下MIG焊接过程中引入激光，利用激光照射熔滴时产生的反冲压力作为辅助力分离熔滴，通过调节激光作用参数，在较低焊接电流下实现稳定可控的MIG焊接熔滴过渡，并建立激光参数、环境压力、焊接电流与熔滴过渡变化之间的关联模型；开发图像处理算法对激光增强水下MIG焊接熔滴过渡图像进行处理，提取清晰熔滴边缘并计算熔滴尺寸；建立电弧声信号传感系统，研究激光增强水下MIG焊接熔滴过渡状态与电弧声信号之间的对应关系。项目成果能够丰富水下焊接理论研究内涵，为稳定的水下MIG焊接熔滴过渡状态实现并对其精确闭环控制奠定基础。

针对高压干法水下MIG焊接时由于受到环境压力影响而造成的焊接过程稳定性差、焊接质量难于保证的现象，基于激光作用于熔滴时所形成的力的作用，研究了激光的引入对压力环境下焊接熔滴过渡状态改善的影响效果及作用机理，解决的主要问题和创新性研究成果概述如下:自主研制了常压环境和高压环境下激光增强水下MIG焊接熔滴过渡控制试验研究平台，搭建了基于高压焊接试验舱的激光穿舱系统和压力环境下的高速摄像系统，并编制了图像处理软件，实现了对激光增强水下MIG焊接熔滴图像的拍摄和熔滴提取；建立了包含焊接电流、电压、电弧声以及熔滴过渡图像在内的多信号同步采集分析系统，实现了对采集所得熔滴图像、电流、电压和电弧声数据的整理和同步分析显示；以此为基础开展了不同环境压力、焊接工艺参数和辅助增强激光参数对焊接熔滴过渡状态影响的综合研究，确定了不同压力环境下熔滴过渡状态与电弧声信号之间的相关性，得到了影响激光增强焊接效果的三个主要因素及影响规律，确认了高压环境下实现激光精确控制熔滴过渡的策略，研究结果为优化高压干法水下焊接工艺参数、稳定焊接过程、提高焊接质量奠定了坚实基础。