DRILL CROWN FOR PERCUSSION DRILLING AND BORING HEAD THEREOF Russian patent published in 2007 - IPC E21B10/56 

FIELD: drilling equipment, particularly percussion well drilling.

SUBSTANCE: drill crown comprises body having connection part formed at rear end thereof and adapted to be connected to percussion block, as well as a number of hard-alloy heads pressed in front end of the body. Each head has hard-alloy body with rear installation part and front end projected beyond crown body. Front end is of bent semi-spherical shape having curvature radius. Radius starts in point located behind plane defining maximal head diameter and axially spaced from the plane. The head projects beyond crown body for distance equal to not less than 50% of head diameter. Conical intermediate surface and enveloping surface of rear installation part define 13-19° angle in intermediate surface cross-section.

EFFECT: increased degree of rock penetration and extended service life.

8 cl, 6 dwg