Machining deformation prediction of thin-walled workpieces in five-axis flank milling

Five-axis flank milling is the main processing method for manufacturing aerospace thin-walled workpieces. The sidewalls of such workpieces are prone to deformation during the milling process because of their low rigidity, which severely affects machining accuracy. Based on this fact, this paper proposes a novel model to predict surface form errors caused by milling force. This study describes an efficient cutter-workpiece engagement (CWE) extraction method for the computation of cutting forces and identification of machining geometry changes during the five-axis flank milling process. The paper then focuses on the establishment of an iterative scheme for machining deformation calculation. This procedure is carried out by considering the coupling effect between cutting forces and tool/workpiece (T/W) deformations, in which the radial cutting depth and the tool axis vector are taken as feedback variables for the iterative computation. Subsequently, the reliability of the proposed model is validated by a 3-mm S-shaped test piece machining with a high-speed steel end mill. The work shows that the surface deformation error comes from the joint effect of the instantaneous milling force and the local stiffness of the workpiece. The relative error rate of the simulation model is 18.8%, which shows good prediction accuracy compared with existing methods.