Research into the ‘Critical State’ of Rock Cutting Tools

Abstract

Every year billions of cubic metres of intact rock forming the Earth’s crust are excavated in the framework of mining and civil engineering activities, using various techniques of rock disintegration. Without consideration given to rock disintegration using explosives, the application of mechanical rock breaking technologies is in progress, being developed as a future technology allowing full mechanisation, automation and robotics, likely to be applicable even in future space research programs. One of the oldest rock disintegration technologies is based on the “cutting tool-rock” interaction. This technology has been accompanying mankind from antiquity to present days. Yet it is still worth studying and improving. From the very broad range of “tool-rock” problems, an analysis of the “tool-rock” interaction, determination of rock resistance by means of measurements and assessment of rock workability and abrasiveness, definition of an ideal speed and a critical state of a cutting tool, analyses of geometrical ratios of a conical bit during rock disintegration, graphical representation of an ideal advance rate of a cutting machine, and evaluation of a critical state of a cutting tool, this is the area covered by this paper, based on a theoretical solution combined with experimental procedures.