Experimental investigation on the effect of wear flat inclination on the cutting response of a blunt tool in rock cutting

摘要

A vast majority of experimental researches focuses on the cutting action of a sharp cutter, while there has been limited experimental work devoted to the study of the contact process at the wear flat-rock interface. The specific objective of this study is to determine the effect of the wear flat inclination angle (beta) with respect to the cutter velocity vector (nu) on both the contact stress (sigma) and friction coefficient (mu) mobilized at the wear flat-rock interface. An extensive and comprehensive set of cutting experiments was carried out on thirteen different sedimentary quarry rock samples using a state-of-the-art rock cutting equipment. A unique cutter holder was purposely designed and manufactured along with a precise experimental protocol implemented in order to change the back rake angle and therefore the inclination beta by steps of 0.10 degrees. The experimental observations confirm the existence of three regimes of frictional contact (identified as elastic, elasto-plastic and plastic) for all rock samples. Further, the results suggest that the scaled contact stress is predominantly controlled by a dimensionless number eta = E* tan beta/q with E* the plane strain elastic modulus and q the rock strength.