CROWN BIT Russian patent published in 2014 - IPC E21B10/02 E21B10/48 

FIELD: process engineering.

SUBSTANCE: invention relates to rock cutting tool intended for exploration drilling with application of dual core barrels including detachable inner barrel. Crown bit cutters, their holders and shanks made integral with the latter feature cylindrical shape and common pivot pin arranged at mid diameter of crown bit body end. Said cylindrical shanks along with thrust bearing fit with minimum clearance in blind bores to spin on their pin, blind bores being made at crown bit body end, parallel with its axis. While cutters of top row are retained by steel ball fitted via bit body side bore in ring groove made at shank lower end.

EFFECT: longer life, higher mechanical speed, lower power input.

2 dwg