CROWN BIT Russian patent published in 2012 - IPC E21B10/48 

FIELD: mining.

SUBSTANCE: crown bit comprises a body, the working end of which is reinforced with wear-resistant radially arranged inserts with the cylindrical base and a trihedral prismatic blade aligned in parallel to the axis of the cylindrical base and having width that is less than the base diameter, at the same time the wear-resistant inserts are installed in radial slots of congruent shape at the end of the body. The wear-resistant inserts in plan are made as T-shaped. Besides, the transverse part of inserts is arranged at the side of periphery and is equipped at the external side with ledges, at the same time the lower end of the transverse part of each insert is displaced relative to the working edge of the blade towards the side, which is opposite to the bottom hole. Achievement of the specified purpose is also aided by the fact that the prismatic blade is equipped with a cone-shaped section, which connects the longitudinal and the transverse parts of the insert. Ledges on the external surface of the transverse part have in their cross section a wedge-like, or a trapezoidal or a rectangular or a hemispherical shape; besides, ledges are arranged in parallel to the axis of the crown bit casing.

EFFECT: increased resource of the drilling tool operation and reduced costs for performance of drilling works.

4 cl, 3 dwg