Transition between relieved and unrelieved modes when cutting rocks with conical picks

Abstract

In the modern theory of rock cutting in production conditions, it is customary to distinguish two large classes of achievable cutting modes – relieved and unrelieved. The kinematics of rock-breaking machines in most cases determines the operation of the cutting tool in both modes in one cycle of the cutting tool. The currently available calculation methods have been developed for a stable, usually unrelieved cutting mode. In this article, the task is set to determine the conditions for the transition between cutting modes and the modernization of the calculation method for determining the forces on the cutting tool. The problem is solved by applying methods of algebraic analysis based on the search for the extremum of the force function on the cutter, depending on the ratio of the real cut spacing to the optimal spacing for the current chip thickness. As a result of solving the problem, an expression is obtained for determining the chip thickness, for which, at the specified parameters, the transition between the relieved and unrelieved cutting modes is provided. The obtained result made it possible to improve the method of calculating the forces on the cutting tool in the areas of the cutter movement with relieved cutting.