Wolf Robotics
Ft. Collins, Colo.
wolfrobotics.com

An existing, heavy-duty two-axis positioner and new robot rotating tower and travel track join old but functional parts with new technology at a cost less than a totally new welding system.

Caterpillar's new robotic system layout uses two preexisting positioners mounted to the floor on each side of the travel track. One control box is needed to coordinate the welding process and positioner movements because new servomotors are integrated for each axis of the positioners. A Wolf Robotics system controls five axes simultaneously in addition to the robot's six axes of movement. Because the motion is coordinated, the robot and positioners can weld seams that are off-center with a fully controlled process speed.

The robotic welding systems' 25-year-old robots were obsolete at Caterpillar Inc.'s off-the-road equipment manufacturing plant in Aurora, Ill. The six welding cells functioned acceptably, but locating replacement parts was increasingly difficult because the robots' manufacturer was no longer in business. In addition, new technology could be added to improve the manufacturing process, but the old robots could not handle the new features.

Caterpillar called in the engineers at Wolf Robotics, Fort Collins, Co., a strategic partner of ABB for robotic arc welding and cutting systems in the United States, to help it with its systems analysis.

Engineers at Wolf Robotics determined that Caterpillar's existing Aronson positioners just needed new motors and gearboxes to make them compatible with new robot technology. "We had good physical components that, with a little bit of work, could still handle the positioning of the heavy weldments," said Kent Sorenson, Wolf Robotics project manager.

Wolf engineers determined that reconfiguring new robots with existing positioners cost substantially less than building totally new systems. Caterpillar could have the latest in robot technology, as well as new software, warrantees and components, at a reduced because it did not have to replace entire systems. Wolf engineers designed a system to have an inverted ABB IRB 2400L robot suspended from a rotating travel column with an S4Cplus robot controller, an adaptive, advanced weld control (AWC) with adaptive fill thruthearc capability, a Servo Robot laser vision system, Smar-Tac tactile sensing capability, BullsEye torch calibration, RobotStudio off-line part programming, and a Lincoln PowerWave CV 655 power source interfaced to the robot controller. The positioners were refitted with new AC servo, brushless motors on their axes, and their motion was coordinated with the robot's motion.

Caterpillar shipped the one cell's cell's two-axis positioner to Wolf's facility for the integration of the robot's electronics with the positioners, and additional tuning was performed at Aurora to insure the positioner operated smoothly with maximum weight requirements.

Caterpillar now has ordered retrofits for the five emaining welding systems. With the new technology, Caterpillar's weld quality and cycle time have improved at a cost 35 to 40% less than replacing the entire system.