Design and mathematical model of a rock crushing milling tooth

Abstract

To solve the challenge of mechanized excavation of power-transmission foundations and earthing trenches in hard rock mountainous areas, available studies on rock breaking by road-milling picks were critically reviewed. It was found that none of the existing investigations offer calculable relationships for determining fracture resistance; they merely allow preliminary parameter estimation for already-known machine layouts. Therefore, a coupled physical-mathematical model for the rock-breaking action of a single spherical-tipped pick has been developed and experimentally validated. By analysing the forces and stresses exerted by the spherical pick on a separating rock element at the limit state, the analytical expressions for each component of the full resistances were derived, forming the mathematical core of the model. Formulas for the tangential and normal parts of the fracture resistance of medium-strength rock were obtained and subsequently verified on a test bench with rocks of various hardness levels. Technical evaluation confirms the reliability of the proposed physical-mathematical model, providing a sound design basis for light-duty hard-rock milling and excavation equipment.