针对网架钢结构中管端环缝的焊接现状,以及焊接规范中基于MIG/MAG焊对焊接速度控制精度的要求,设计了环缝自动焊接专机中焊枪运动的控制机构,给出了无急回特性的曲柄摇杆机构存在的条件,建立了摇杆摆动运动的数学模型,并对一组不同参数的曲柄摇杆机构进行了运动特性仿真,得出了焊枪摆动机构的优化设计方案。理论分析和实验结果显示:此设计方案完全可以满足基于MIG/MAG焊对焊枪摆动控制的要求,并使曲柄摇杆机构具有最佳的运动特性。 In view of the current welding situation of pipe-end girth in the steel truss structure and the requirement of welding speed control accuracy based on MIG / MAG welding in the welding specification, the control mechanism of torch movement in the automatic welding machine with annular seam was designed. The characteristics of the crank rocker mechanism of the existence of the conditions, the establishment of a rocker swinging mathematical model, and a set of different parameters of the crank-rocker mechanism of the simulation of the kinematic characteristics of the optimal design of the gun swing mechanism. Theoretical analysis and experimental results show that this design scheme can fully meet the requirements of swing control of welding torch based on MIG / MAG welding and make the crank rocker mechanism have the best movement characteristics.