Path Planning Of Four-Axis Welding Robot For PipePpipe Intersecting Welding Seams

Pipe-pipe intersecting welding seams is a typical complex space weld,which is an intersection formed by the intersection of two pipe bodies.The welding operation of the pipepipe intersecting welding seams widely exists in the fields of nuclear power,aerospace,ships,petroleum and pressure vessels.Due to the particularity of the industry,the welding quality is strictly required.Therefore,the high-quality automatic welding of intersecting welds has always been are problems in this field.The existing equipment is mainly a six-axis robot equipped with a two-axis tilting positioner.This method has disadvantages such as large footprint and poor flexibility,and it is difficult to meet the welding requirements of welding seams.Up to now,it is basically welded by hand.The operating environment of manual welding is harsh,and the welding quality and stability are difficult to guarantee.Especially when multilayer and multi-pass welding is required,the labor intensity of workers is unimaginable.Therefore,combined with the urgent demand for advanced automation equipment for intersecting welds in the welding field,the development of efficient,flexible and reliable welding machines,and the realization of automatic welding of intersecting welds through multilayer and multi-path path planning is of great importance to promoting the manufacturing industry in my country’s welding field.Developmental significance.Aiming at the problems faced by the automatic welding of pipe and pipe welds,this paper firstly analyzes the characteristics of the welds by establishing a mathematical model of the offset oblique intersecting welds on the basis of a comprehensive analysis of the automatic welding machines at home and abroad,and designs a This four-degree-of-freedom welding robot adopts the form of cylindrical coordinate motion.The welding torch moves along the trajectory of the intersecting line through the coordination of the rotating spindle,the axial lifting axis and the radial feed axis.The fourth axis is the welding torch swing axis.Realize the function of adjusting the welding posture in real time during the welding process.Secondly,through the reasonable simplification of the structure of the four-axis welding machine,the robot connecting rod coordinate system and DH parameter table are established,and the instantaneous position and attitude expression equation of the center point of the robot welding torch tool under the robot base is deduced.According to the welding process angle requirements and the strokes of the joint variables determine the uniqueness of the inverse kinematics solution of the robot.Based on the Monte Carlo method,the Cartesian workspace of the robot is analyzed using MATLAB,which lays a foundation for the subsequent welding trajectory planning in the Cartesian space.Then,in view of the problem of deviation of welding trajectory caused by poor consistency of welding workpieces,processing errors and welding thermal deformation,a strategy based on laser ranging is proposed to scan the position and posture at equal intervals.The influence of deformation on the position of the weld ensures the adaptability and dynamics of the trajectory.The calibration matrix of the laser displacement sensor is solved,a trajectory planning method is given by the modified equidistant tangent method and linear ZYX Euler angle interpolation,and the preaching strategy of one-way sequential welding is determined from the point of view of welding technology The location of the arc starting point of each weld is planned.Finally,the correctness of the weld mathematical model,robot kinematics model and trajectory planning algorithm is verified by simulation.The welding test was carried out on the actual workpiece by making a prototype and building a test platform.The welding robot is firmly anchored and positioned accurately,and the welding process runs smoothly without crawling and shaking.After the welding is completed,the welding seam is compact and beautiful,without defects,and the welding bead arrangement is not heavy or leaking.The work of the thesis lays the foundation for the realization of high-quality and highefficiency automatic welding of multi-layer,multi-pass,all-position,intersecting line welds.