An experimental study of the effect of back rake angle in rock cutting

The objective of this paper is to investigate the influence of the rake angle on the magnitude of the intrinsic specific energy and the inclination of the force acting on the cutting face of a Polycrystalline Diamond Compact (PDC) sharp cutter while tracing a groove on the surface of a rock sample. An extensive and comprehensive set of cutting experiments was performed on a wide range of quarry rock samples using a state of the art rock cutting equipment (Wombat). The results conform with the previous studies by other researchers; the intrinsic specific energy is in good agreement with the uni-axial compressive strength of the rock samples when the cutter is positioned at back rake angles between 5° to 20°. New results on a few rock samples were also obtained by performing novel experimental tests at very large rake angles (θ > 70°) as well as negative rake angles, showing that the intrinsic specific energy increases dramatically once the back rake angle exceeds 75°. Results also indicate that the decrease of the apparent interfacial friction angle with increasing back rake angle seems to follow a “universal trend” weakly dependent on the rock sample

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

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 ( β ) with respect to the cutter velocity vector ( vv ) on both the contact stress ( σ ) and friction coefficient ( μ ) 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 β by steps of 0.10∘ . 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 η=E∗tanβq with E∗ the plane strain elastic modulus and q the rock strength