DRAG-DRILLING BIT Russian patent published in 2007 - IPC E21B10/42 

FIELD: mining, particularly cutting tools for auger hole drilling, particularly for blast hole making.

SUBSTANCE: drilling bit comprises body, movable blades reinforced with wear-resistant plates, which form cut with certain angle in central bit part between movable blades, and curvilinear convex cutting edge. The cutting edge carries wear-resistant plates located at cutting edge periphery. Angle defined by tangent line passing through cutting edges of the plates and through hole-making apexes, and longitudinal bit axis is equal to half of the angle of the cut. Blades are connected to drag-drilling bit through fastening axes located below plane passing through hole-making apexes of wear-resistant plates transversal to longitudinal drag-drilling bit axis. The fastening axes are spaced equal distances from the apexes at maximal and minimal diameters of the cut.

EFFECT: increased efficiency of drag-drilling bit usage in auger rod assemblies during blast hole drilling in rock having varying hardness.

2 dwg