Thermal-mechanical model for cutting with negative rake angle based on a modified slip-line field approach

Abstract

A comprehensive demonstration of fictional behaviors at the chip-tool interface promotes better understanding about cutting force, stress distribution and heat generation. However, previous attention was paid mainly on the positive rake angle cutting, while the study on large negative rake angle cutting is still limited and challenging due to the significant stagnant effect beneath the inclined tool rake face. In this paper, an analytical slip-line field model with corresponding hodograph is presented based on material plasticity and ploughing theory. Two main modifications on the dead metal zone (DMZ) are incorporated to demonstrate the material flow mechanism in primary and secondary deformation zones for negative-rake-angle cutting process. Detailed illustrations of the tribology behaviors at the interfaces of chip, tool and DMZ are carried out by introducing friction factor angles. Based on the systematic analysis of the interactions between the slip-line field geometry and varying negative rakes and feed rates, two approaches to the prediction of cutting forces and temperature fields are developed with imaginary heat source theory. To validate the proposed model, the extracted slip-line field geometries, cutting forces and the temperature distribution from two-dimensional finite element (FE) simulations are served as the simulation validation for the proposed-slip-line field model. Besides, experimental validations including measured cutting forces from orthogonal cutting experiments and released experimental data from literatures are involved to verify the applicability of the developed force prediction approach.