Abstract
Automated welding robots face challenges in unstructured field conditions, limiting their use in complex steel structures like pipelines, bridges, and buildings. Expandable convoluted pipe (ECP) poses unique welding challenges due to their confined spaces and irregular shapes. Manually performed butt-welding for ECPs is inefficient. To address this, a flexible mobile welding robot tailored for ECPs was developed. This paper analyses the robot's structure, working principle, and drive system, minimizing drive chain force-velocity angles to reduce power loss. Transmission modelling, finite element analysis, and life prediction using the Archard model yield promising results. Virtual simulations and prototype welding tests validate the robot's design, with satisfactory weld formation. Expanding the ECP with a hydraulic pump verifies the robot's reliability with no weld cracks observed.