Forces and Plastic Work in Cutting

Abstract

Prolific considerations in C.I.R.P. give rise to a further step in the development of a plastic cutting model. Basically two different primary shear zone geometries are assumed: with one and with two shear planes respectively. For both geometries two energetically different approaches are developed. This leads to expressions for dimensionless friction force numbers. These are defined as the quotient of the friction force and the product of specific stress, feed and width of cut. An additional assumption that the supplied power is completely dissipated in the plastic deformation of the chip material provides expressions for dimensionless cutting force and feed force numbers. These three force numbers depend on the shear angle and the rake angle of the tool for a given value of the strain hardening exponent. All theoretical models are verified experimentally for several workpiece materials, tool rake angles and cutting conditions. The plasticity values of the material necessary to quantify the force numbers are separately determined in tensile tests. Some of the numerous cutting experiments are represented graphically and they illustrate the general tendency of a satisfying agreement of theory and experiment, especially for the model based on two shear planes.