An analytical model for engagement regions in machining of 3-d free-form surfaces

Abstract

In the machining simulations of 3D free-form surfaces with ball-end-mill process, determinations of instantaneously changing tool-workpiece contact regions and chip load play very critical roles in forces and surface quality predictions. Cutting force models for ball-end milling are based on the undeformed chip thickness. Undeformed chip thicknesses can be constructed from the boundaries of instantaneous contact region between the ball-end mill and workpiece. In order to predict the cutting forces accurately, determination of the varying contact region is important. In the literature, there are two main contact region constructing methods; one is the Z-mapping and the other one is using solid modeler based Boolean operation method. Both methods construct the contact region within accuracy limits but the computational time for these methods are long such that it is not possible to calculate the forces at the same time of (CL) points construction. This paper presents development of a new analytical method for the determination of the instantaneous contact regions and chip load in the 3-D machining of monotonic free-form surfaces.