Machining of large CFRP-components with industrial robots with hybrid drives

Abstract

The industrial robot with extended workspace offers an alternative concept for machining of large CFRP components. Due to their serial kinematics, robots have a good ratio of mounting space to workspace and provide high flexibility in the production line. Although the machining with industrial robots of thin aerospace shell components has already been successful, the next step for the growing utilization of robots in the scope of machining is increasing their robustness against process forces and their application in more demanding machining tasks.

In this work, an industrial robot with a linear axis designed for machining tasks is presented as a new approach for milling of large aircraft components. The use of an innovative hybrid drive train, consisting of an additional torque drive that is mounted parallel to the conventional gear drive, in the first three axes of the robot increases its dynamic behaviour by generating torque directly on the load side without mechanical transmission. This hybrid drive concept combines the ability to compensate for undesirable effects of the gearbox such as compliance caused vibrations and to dampen high-frequency excitations while at the same time ensuring high energy efficiency in static and quasi-static states. This work examines the behaviour of the robot during machining and shows that the use of hybrid drives in industrial robots significantly improves the machining quality and reduces the influence of the workspace position on the path accuracy.