CROWN BIT Russian patent published in 2013 - IPC E21B10/06 

FIELD: mining.

SUBSTANCE: crown bit comprises body with axial channels at its end with core-forming rolling cutter shanks fitted in said channels. Shank ends interact with thrust bearings via ball bearings. Aforesaid axial channels have incline sidewall oriented in cutter rotational direction. Note also that resilient element is arranged between inclined wall and core-forming rolling cutter shank. Every core-forming rolling cutter shank can be rigidly coupled with ball bearing locked by thrust bearing against axial upward displacement and, against downward displacement, by sleeve rigidly coupled with body.

EFFECT: higher efficiency in drilling different-hardness rocks.

2 cl, 2 dwg