MODEL BASED COMPENSATION OF GEOMETRICAL DEVIATIONS DUE TO PROCESS FORCES

Machining accuracy can be considerably affected by deflections of machine tool components and the workpiece. This work presents a new approach for real-time deflection compensation, based on control integrated models. A real-time material removal rate (MRR) simulation determines the depth of cut which is used for process force calculation by Kienzle-Equations. Machine tool and workpiece deflections are then derived from a mechanical model using the calculated process forces. For this purpose, control based signals are used as model inputs. The total deviation is sent to the position controller as a setpoint offset. A dynamometer was applied to validate the simulated process forces. The presented approach was validated for cylindrical turning operations on chucked steel shafts. The experiments were carried out on a high-precision slant bed lathe. The results show, that geometrical errors could be reduced by more than 70% on average.