In order to achieve automatic welding along a complex spatial trajectory in robotic multi-path/multi-layer welding, and increase processing quality and productivity of specific welding structures, path planning of intersecting welding seams for intermediate or thick wall pipes is implemented. Conforming to the welding technology principles, the welding groove model is established for the purpose of manufacturing the prefabricated pipes and devising the path planning algorithm. Through the analysis on the welding seams' section which convolutes around the insert pipe's axis at any angle, an arrangement strategy for multi-path/multi-layer welding beads is proposed with definite positions of each welding bead. Meanwhile, the position and orientation of welding gun tip is planned, and an off-line programming system for robotic multi-path/multi-layer welding is developed. The simulation results show the accurate positions of each welding bead. In actual welding experiments, good continuity and high productivity are realized with the robotic welding process, and uniform and compact welding seam filling with good appearance is achieved.
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