FOUR-STAGE THREE-BLADED ROTARY BIT FOR ROTARY BLASTHOLE DRILLING Russian patent published in 2015 - IPC E21B10/42 E21B10/44 E21B10/58 

FIELD: mining.

SUBSTANCE: four-stage three-bladed rotary bit for rotary blasthole drilling includes a cutting stage, a drill cuttings excavation stage, a locking stage for fastening on a drilling rod. The cutter is also fitted with a clamping stage located between the excavation stage and the locking stage providing the strength joint of the cutter with the rod, and heights of all four stages along the geometrical axis of rotation of the cutter are designed in the ratios 2/10:3/10:2/10:3/10 of the total height of the cutter with the tolerance per each stage ±0.5/10. The cutting stage has hard-alloy plates designed as heptahedrons, two sides of which are designed mutually perpendicular and used for their fastening by means of solder on a congruent body of the cutter, two frontal sides, forming together an obtuse angle, are intended for direct contact with drilled rock, and three other sides form with two frontal ones cutting edges with various angles of cutting. The flange of the drill cutting excavation stage screw is designed by height with the changing step and with the decreasing radius from the cutting step to the clamping stage. The clamping stage intended for fastening on the drilling rod is designed with six pairwise-parallel flat sides the distances between which are set according to the ready-to-operate standard sizes. The locking stage is designed as a threaded connection with an internal hole which can be designed cylindrical or according to the parabolic or conic law with diameter decrease towards the clamping stage.

EFFECT: improvement of working capacity and creation of design of a cutter capable to blasthole drilling in massifs of rocks.

4 cl, 9 dwg