Multi-layer Welding Off-line Programming For9-DOF Arc Welding Robot

In order to solve the welding problem of slab complex structures, the redundantdegrees of freedom robot system is needed. The9-DOF arc welding robot system iscomposed of three parts, a joint robot with6-DOF,2-DOF positioner and a horizontallinear motion guide.Firstly, according to the D-H method, the coordinate system of the redundantDOF of arc welding robot station was established. The forward and inverse solution tothe robot and positioner was solved. And most importantly, the optimal solutionproblem of inverse solution which often has more than one solution was explored.For the sake of achieving multi-layer/multi-pass welding of J-type groove shapeof a saddle weld, it takes the cross-section filling measures to plan the welding pathfor the J-type groove. In addition to the first pass, it proposes the theory that is used todetermine and modify the number of layers and passes by the increment, based onwhich the unknown weld trajectory can be inferred according to the geometricparameters of groove and the weld track of the first pass.At the same time, the offline programming system for multi-pass welding of9-DOF of arc welding robot was developed by VISUAL C++6.0. And it mainlyconsists of six modules, forward and inverse solution of kinematics modules, pathplanning module of multi-pass welding，welding job generation module, kinematicsimulation module ROTSY and communication module MOTOCOM32. The pathplanning module of multi-pass welding includes the planning of the saddle-shapedgeometry parameters, weld layout planning, welding sequence planning and torchposture planning. Not only can the system generate operating instructions step by step,but also generate job files automatically with many advantages such as a friendlyinterface, high integration, easy operation and so on.Finally, on the basis of the V-groove butt welds offline programming experiment,offline programming and motion simulation has been made based on the J-typegroove shape of a saddle weld.And the job files which has been simulated istransferred to the robot control cabinet for the actual welding. The experimentalresults show that the movement of the robot system is stable and the actual weldingfiller effect is consistent with the path planning.What’s more, the quality of weldedjoints can be ensured and the efficiency of programming is improved remarkably.