CROWN BIT Russian patent published in 2015 - IPC E21B10/48 

FIELD: process engineering.

SUBSTANCE: invention relates to crown bits for drilling hard rocks and frozen abrasive soils. Circular crown bit comprises body with coupling thread, sectors made at said body and separated by flushing grooves, inserts with wearproof coating at least 0.7 mm thick at leading face arranged at negative cutting angle in plan to cutting inner and outer surfaces and negative cutting angle to the wall face end surface, cylindrical wedges and lock screws fitted to lock wedges in cylindrical grooves. Said inserts have hemispherical shank, rectangular side edges and working face blade shaped to conjugated arched lines. Insert rear face is coated with ply in depth equal to coating at cutting face. Note here that both coatings are made of superhard, shockproof and heatproof material.

EFFECT: higher rate and efficiency of drilling, decreased consumption of flushing fluid.

2 cl, 3 dwg