DRILL BIT Russian patent published in 2015 - IPC E21B10/18 

FIELD: mining.

SUBSTANCE: claimed drill bit comprises the body with central stepped bore, rolling cutters arranged at legs and branch pipe of resilient material fitted in said central bore. Outlet of the latter is provided with the adapter fitted at the inner surface and the bushing fitted at the outer surface. Spacing between the legs is covered by the webs, inner surface of the latter and inner faces of the legs making the closed circular surface to contact with resilient pipe outer surface in the working position. Note here that the contact surfaces of the bushing and circular surface are provided with mating ledges and recesses while branch pipe is arranged in the body to turn about its axis.

EFFECT: higher efficiency.

2 dwg