Analysis of surface quality during milling with industrial robots as a function of milling spindle orientation

Abstract

The range of tasks performed by industrial robots has become increasingly comprehensive in recent decades. This includes pick-and-place tasks with low to medium handling weights, as well as material processing tasks with medium to high processing forces. Milling in particular involves high-frequency excitation of the material, which results in vibration phenomena and therefor affects the surface quality of the product. These effects were investigated by milling tests at characteristic positions and in different orientations of the milling spindle, using aluminum. For this purpose, based on an experimental modal analysis, a prediction model of the robot's natural frequencies in dependence of the joint positions was developed. This allowed the determination of characteristic milling positions and milling spindle orientations. Subsequently, the milling results were related to a causal connection and were analyzed regarding the natural frequencies.