Multi-Body dynamic simulation of a machining robot driven by CAM

Abstract

The use of industrial robots for milling processes has been targeted by many industries lately, as they are able to significantly increase the flexibility and lower the production cost over conventional CNC machines. However, the serial, open kinematic chain of industrial robots leads to a compromised structural stiffness, which in turn affects machining accuracy. Apart from that, the dependency of robot dynamic behavior on its posture requires time and cost intensive simulations and experiments to determine its dynamic behavior over its whole working envelope by using traditional methods. To this end, this work aims to develop an integrated model using the Multi-Body Simulation method for a machining robot, considering the elastic behavior of both the joints and the links. The links are modelled through the Finite Elements Method and the Craig-Bampton method is used to reduce the size of the model and enhance the computational efficiency. Moreover, the simulation is linked with a commercial CAM software to enable a rapid evaluation of the expected deflections over the programmed toolpaths and assist the process planning stage. Finally, a case study on a feed rate scheduling algorithm based on the simulation results is presented to showcase the capabilities of the developed model.