Tri-dexel-based cutter-workpiece engagement: computation and validation for virtual machining operations

In the Industry 4.0 era, the modelling of machining operations happens to be a crucial aspect of production sector. With adequate models, predicting the appearance of chatter and selecting optimised operational parameters is possible. For the dynamics simulation of machine tools or robots performing 5-axis operations, modelling approaches are continuously in improvement. A robust method is proposed for the cutter-workpiece engagement (CWE) computation at each step of a dynamic simulation, by determining the machining forces as well as the resulting machined surface. The CWE is estimated based on the interference between the workpiece, modelled with tri-dexel approach, and the tool, considered as a triangle-mesh surface of the swept volume. The relative closest triangle algorithm is used for a robust intersection management, suited for 5-axis trajectories. A hybrid dexel-based-analytic method is presented for accurate estimation of the uncut chip thickness. Furthermore, an approach is proposed for a simulation-based evaluation of the part resulting from dynamic simulations by comparing dexel networks with each other. It allows to assess the impact of operational parameters on parts at the simulation level. The CWE determination method proposed is validated with experimental data from force measurements and benchmark tests of different scales from macro- to micro-milling.