重载灵巧高刚度搅拌摩擦焊机器人动态特性分析及优化设计

This project focuses on the existing Friction Stir Welding (FSW) equipment with single function and lacking of flexible process, it is difficult to achieve the welding aiming to complex three-dimensional welding seam. Subjecting to the welding mechanism of heavy-load and strong-disturbance, a kind of roboticized FSW equipment (FSW Robot) was taken as research object. Study kinematics and dynamics of mechanism under giving welding task, analyze the accessibility and dexterity of workspace as well as the force and moment characteristics of joint space; Establish the hot -fluid-solid coupling model of welding head acting on workpiece, simulate the load change curve of welding head, reveal the multivariate coupling mechanism in the welding process; Establish three joints’ stiffness models including bearing, screw and guideway, obtain the six dimensions of stiffness under the different preload force and external load. Propose the concept of structure framework and structure unit, built a set of multi-objective optimization design method based on the large-scale and complex structure decomposition. And on this basis, put the trajectory planning, joint stiffness, structure flexibility, and load acting on welding head into the FSW robot's whole dynamic characteristics analysis and welding process simulation. At last, we put forward the comprehensive optimization design criteria. It provides important theoretical basis and design guidance for innovative design and welding performance study of FSW robot with heavy-load, dexterity and high-stiffness.

本项目针对于现有的搅拌摩擦焊设备功能单一、缺少工艺柔性，难以实现复杂三维焊缝焊接这一现实问题，受制于超重载和强扰动的焊接机理，以一种机器人化的搅拌摩擦焊设备（搅拌摩擦焊机器人）为研究对象，研究在给定焊接任务下机构的运动学和动力学，分析工作空间的可达性和灵巧性以及关节空间力和力矩特征；建立搅拌头-工件的热-流-固耦合模型，模拟搅拌头上的载荷变化规律，揭示焊接过程中的多元耦合机制；建立轴承、丝杠和导轨三种结合部的刚度模型，获取结合部在不同预紧力和外载作用下的六维刚度；提出结构框架和结构单元的概念，创建了一种基于结构分解的复杂大件结构多目标优化设计方法。在此基础上，把基于特定焊接工况下的轨迹规划、结合部的刚度、结构的柔度以及搅拌头所受的载荷用于机器人的整机动特性分析和焊接过程仿真，并提出综合的优化设计准则，为重载灵巧高刚度搅拌摩擦焊机器人的创新设计及焊接性能研究提供重要的理论依据和设计指导。

针对重载灵巧高刚度搅拌摩擦焊机器人，对其整体结构的组成和各项设计指标进行了完整的阐述。研究机器人在典型焊接条件下机构的运动学和动力学，分析工作空间的可达性和灵巧性以及关节空间力和力矩特征。通过特定工况下的虚拟样机仿真分析，验证数学模型和设计方案的正确性。采用网格自适应技术对2A14-T6高强铝合金的焊接过程进行数值模拟，研究焊接过程的流固耦合及和热力耦合规律。同时对搅拌头的主轴热传递进行分析，研究焊接过程对主轴内部的影响。应用优化的焊接参数对火箭贮箱顶盖进行焊接试验，结果获得了表面成性良好，无缺陷的优质接头。利用有限元的方法分别建立三种结合部的有限元静态和动态仿真模型，研究刚度与外载荷的非线性变化关系。提出了一种基于结构分解的大件结构动态优化设计方法，将复杂大件划分成外部的总体框架和内部组成的基本单元样式。分别对搅拌摩擦焊机器人XYZ轴组件的底座、立柱和滑枕大件结构进行了拓扑优化和尺寸优化。对搅拌摩擦焊机器人进行了模态分析和频率响应分析，得到了整机的模态频率和振型以及各测点的位移响应和加速度响应。搅拌摩擦焊机器人进行了最恶劣工况下的焊接精度仿真，通过分析焊接曲线的误差得到了实际焊缝的焊接精度，最终证实了搅拌摩擦焊机器人总体设计优化的可行性。

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