多曲面钛合金构件激光智能焊接技术基础

In aerospace manufacturing, robotization has been realized in the laser welding of titanium alloy components composed of multiple curved surfaces. The main problems in such robotized welding is the instability of welding quality, including porosity, spatter and poor weld formation, which lead to low primary pass rate. The formation of such defects is closely related to various factors, including the weld pool and keyhole behavior, changes in alignment and relative position and angle, control of laser welding process parameters, etc. This project proposes to carry out researches on the defects formation mechanisms and controlling measures, the motion planning of robotized laser welding system, the sensing and on-line fusion of multi-physics information, and the real time feedback and control of various parameters in the laser welding of complex three dimensional titanium alloy components. Through these researches, the inner mechanisms among ‘complex components-process parameters-fluid flow characteristics-welding quality’ are to be clarified, and the formation mechanisms and influencing factor of defects are to be revealed. In addition, key technologies are to be developed in developing precision motion control theme for multiple freedom welding system, self-tracking of weld seam in titanium alloy components with strong light-reflecting surfaces and/or ultra-narrow gaps, and real time multiple close-loop optimizing and controlling of welding process during the intelligent laser welding, so as to provide technical support for the developments of intelligent laser welding technology and system. This project is of great significances to the high quality manufacturing of spacecraft of China.

航天制造领域的多曲面钛合金结构激光焊接大多已实现机器人化操作，目前存在的主要问题在于质量稳定性，包括气孔、飞溅和焊缝成形缺陷等，导致一次合格率不高。缺陷的形成与包括小孔在内的熔池行为、焊接过程光束对中及相对位姿变化、激光焊接工艺参数控制等密切相关。本项目提出针对多曲面钛合金结构复杂三维焊缝激光焊接的缺陷形成机理与控制措施、机器人化激光焊接系统运动规划、多信息传感及在线融合处理、焊接过程多参数实时反馈控制等问题开展研究。旨在阐明“复杂工件结构-焊接工艺参数-熔池流动特征-激光焊接质量”之间的内在机制，揭示多曲面钛合金构件激光焊接过程缺陷形成机理及影响因素，突破多自由度焊接系统精确运动控制方案生成、强镜面反射（钛合金）工件和（激光焊接）超细隙坡口自动跟踪、多闭环实时优化控制等激光智能焊接的关键环节，为发展智能化激光焊接技术和系统提供基础。预期成果对我国航天飞行器的高质量制造具有重要意义。

航天制造领域的多曲面钛合金结构激光焊接已能实现机器人化操作，目前存在的主要问题是复杂结构的焊接工艺规划和实时控制智能化程度有限导致的质量稳定性不足，易出现气孔和飞溅等成形缺陷，难以满足航天构件的高标准要求，导致一次合格率不高。为此，亟需针对复杂钛合金构件激光焊接中缺陷形成机理及焊接质量智能控制开展研究。.本项目采用工艺试验、数值模拟、高速摄像、冶金质量分析、数据统计等研究方法，研究了焊接空间位置及激光焊接工艺参数等因素对钛合金激光焊接质量的影响规律及其机理，揭示了焊接冶金及工艺缺陷的形成机制，阐明了“复杂空间轨迹-焊接工艺参数-熔池流动特征-焊接质量”之间的内在联系，为多曲面钛合金构件激光焊接制造的焊前工艺规划及在线质量控制提供了依据。.针对航天多曲面钛合金构件复杂的二维平面曲线及三维空间曲线焊缝轨迹，考虑其激光焊接工艺要求、多曲面复杂工件的结构特征、机器人化多自由度焊接系统执行机构的可达性和可控性等因素，建立了多约束条件下焊接系统复杂空间曲线运动的运动学和动力学模型，以焊接质量为目标函数，对激光焊接过程运动轨迹及位姿进行离线预规划，实现了基于智能规划方法的离线编程激光焊接多曲面钛合金复杂构件。.针对钛合金材料表面强光学反射和激光焊超细隙坡口的特点，提出了基于球面光源漫反射的强镜面反射工件细窄坡口检测原理，开发了细隙焊道视觉传感器，实现了激光焊接细隙焊道位姿的检测；针对骨架-蒙皮类结构“盲焊”过程中焊道位置检测和自动跟踪的需求，阐明了背透型焊道射线检测和涡流检测的原理并建立了适用的焊缝检测和跟踪方法；针对高速激光焊接的驼峰成形缺陷，通过在线获取成形质量相关信息并采用高效算法进行融合处理，实现对焊接过程闭环控制，保证了多曲面钛合金复杂构件的焊接质量。.研究工作为智能化激光焊接技术和系统的发展提供了技术支撑，研究成果对我国航天飞行器的高质量制造具有重要意义。