Adaptive path and process planning method for multi-layer and multi-pass welding of medium-thick plates with robots

Abstract Large steel structures inherently have errors such as clamping and continuous thermal deformation, which complicate traditional robotic multi-layer multi-pass (MLMP) welding of medium-thick plates to ensure quality, efficiency, and universality. To address these conditions, this paper proposes an adaptive process and path planning method for MLMP welding of V-grooves utilizing line laser displacement sensors. First, dimensions and profile of the groove are obtained, feature points are extracted, and the robotic path and welding process for the root welding are planned based on the V-groove’s feature information. Then, reference process parameters is used for filling and cover welding. After each pass/layer, feature points of the V-groove will be extracted, and the previous pass/layer formation will be analyzed. And then algorithm proposed in this paper will be used to adjust the process and robotic path to ensure that, before cover welding, the average groove depth will remain within a specific range. Finally, MLMP experiments have been conducted on two V-grooves of different sizes. The results indicate that this method effectively fills the groove. Maintain the average remaining depth of the groove between 1 and 2.5 mm before cover welding, meeting the requirements of different sizes of V-grooves. The entire surface and cross-section of the weld seam are free of defects, and the fusion between the weld seam and the sidewall exceeds 1.5 mm, meeting the requirements for industrial use.