DRILLING TOOL (ITS VERSIONS) Russian patent published in 2011 - IPC E21B10/16 

FIELD: mining.

SUBSTANCE: drilling tool includes housing with blind holes, rock cutting bits with working head and shank, which are fixed in holes of the housing by means of bushing. Bushing has longitudinal cut and is installed so that it can contact the lower edge of working head the diametre of which is more than diametre of shank; at that, length of bushing is less than that of shank. As per the first version, bushings have inner taper surface corresponding to outer surface of shank of rock cutting bit, and as per the other version the bushing has outer taper surface corresponding to side surface of blind holes of the housing. At that, contact surfaces of lower edge of working head of rock cutting bit and upper edge of bushing are made in the form of cone.

EFFECT: increasing efficiency of drilling operations owing to more reliable fixture of bits.

4 cl, 3 dwg