The extension of a simple predictive model for orthogonal cutting to include flow below the cutting edge

Abstract

A predictive model for orthogonal cutting that is able to accommodate the analysis of flow under a cutting edge is described. The model uses an upper-bound approach, in which the boundaries to the primary and secondary deformation zones are defined in such a way that both force and moment equilibrium of the rigid body chip is achieved. The remainder of the field is allowed to adjust so as to minimize the power consuming force, and finally force equilibrium is applied to estimate the edge forces acting under the tool. Solutions and comparison with previous theoretical and experimental observations are presented for different rake angles and chamfer or edge geometries; the influence of edge rounding or flank wear on the process are of particular interest. The model predicts a considerable change in flow geometry at high chamfer length/wear; this evidently occurs as a result of the field adjusting to balance the work in the primary and tertiary zones. The changing flow zone indicates that the hydrostatic stress at the tool edge increases as the chamfer or wear length increases.