ROTARY CUTTING DRILL BIT Russian patent published in 2005 - IPC

FIELD: mining industry, particularly for drilling blast holes in mines or open pits and for making technological holes.

SUBSTANCE: drill bit has body with ribs, axes secured in ribs by spline connections and eccentric bushes on which toothed disc cutters are installed. Outer surfaces of eccentric bushes are inclined at α angle to axis to provide α_v angles of cutters inclination to vertical plane and α_h angles of cutters inclination to vertical plane of hole bottom. Angles α_v and α_h may be changed in dependence of physical mechanical properties of rock to be drilled. Relation between above angles satisfies the following equation: α=α_v+α_h, wherein angle between side edges of toothed disc cutters α_c=2α. Cutters have longitudinal grooves with trapezoid cross-sections at bases thereof adapted for alternately receiving hard-alloy teeth and intermediate sections having the same trapezoid cross-section at bases thereof. Number of hard-alloy teeth N is determined in dependence of rigidity f of rock to be drilled as , where D_c is diameter of toothed disc cutter and D_t is diameter of working hard-alloy tooth part.

EFFECT: increased operational efficiency and extended range of efficient usage thereof in solid rock having composite structure with different physical mechanical properties and in karst massifs.

4 cl, 6 dwg, 2 tbl