CROWN DRILLING BIT Russian patent published in 2008 - IPC E21B10/48 

FIELD: machine building.

SUBSTANCE: invention relates to rock destructing tools, namely, to crown drilling bits reinforced by synthetic diamonds designed for drilling with extracting cores. The crown bit includes a casing and a matrix divided by the flushing slots into separate sectors furnished with well-forming, central and core-forming superhard inserts and protective elements. Note here that well-forming and core-forming inserts are set up with a negative angle of inclination and with a lag in height relative to the central inserts. Note that the diameter of the central, well-forming and core-forming inserts d_c, d_w and d_cr are interrelated by the following ratio: d_c=(1.15-1.25)d_cr, with d_w=d_cr. Mind that the central inserts, depending upon physical and mechanical properties of bored rocks, can be arranged vertically, horizontally, with a negative-angle inclination and a radial shift towards the well-forming inserts.

EFFECT: higher efficiency of crown bit operation.

4 cl, 6 dwg