Design and contact analysis of gripper for tube inspection robots

Abstract

Automatic robots have been extensively employed to inspect steam generator (SG) tubes. Positioning and fixation of robots underneath tube-sheet plates are enabled by tube grippers. In this paper, configuration design and performance analysis of a new tube gripper were carried out. To calculate the gripper's load capacity, numerical analysis was used to establish finite element (FE) model of the gripper. Furthermore, orthogonal experiment and statistical methods combined with FE analysis were adopted to explore the influence on contact between the gripper and the tube's inner wall by manufacturing tolerance. Three factors of dimension and form tolerance were selected in sensitivity analysis. The influencing factors of contact stress were analysed by analysis of variance (ANOVA). Physical prototype experiment results were provided to validate the design rationality. Results of analysis and actual tests proved that the gripper with inelastic fingers exhibited excellent load capacity, superior contact performance and longer service life time.