H. B. Smartt, D. P. Pace, E. D. Larsen, T. R. McJunkin, C. I. Nichol, K. L. Skinner, M. L. Clark, T. G. Kaser, Idaho National Laboratory, Idaho Falls, ID
A modular, robotic welding and inspection system has been developed for remote welding of lids onto large diameter cylindrical vessels. The system consists of a pedestal-mounted six-degree-of-freedom articulated robot arm operating in conjunction with a rotating positioner. The system has four end effectors for gas tungsten arc welding, grinding and wire brushing, ultrasonic and eddy current inspection, and eddy current inspection of weld repair grooves. Visual inspection is performed by means of a video camera/laser line scan sensor and weld interpass temperature is measured by a contact thermocouple.The four end effectors are stored on a tool tray mounted behind the robot arm. Quick disconnect tool mounts are used between the robot arm and the end effectors. Electrical and other services are provided to the end effectors by means of free-standing umbilicals incorporating shape-controlling springs. Additional tools are on the tool tray for filler wire trimming, electrode changing, electrode stickout adjustment and inspection sensor validation.
System control is accomplished by means of graphical human machine interfaces for each of the major system functions (welding, grinding and brushing, and visual, eddy current, thermal and ultrasonic inspection). Ethernet communications is used for high level system integration with time-critical and non-critical subnets for control functions and data communications respectively.
Design features include video cameras for weld viewing, modular software, and text-based procedural files for process and motion trajectories. Procedure and motion primitives stored in the text files are interpreted and converted into executable code at run time in a manner that allows large preweld uncertainty in vessel positioning.
Summary: This paper presents a robotic system for GTA welding lids on cylindrical vessels. The system consists of an articulated robot arm, a rotating positioner, end effectors for welding, grinding, ultrasonic and eddy current inspection. Features include weld viewing cameras, modular software, and text-based procedural files for process and motion trajectories.
