Study on diamond bit for hard and compact rock

High hardness, fine petrogenetic mineral grains and compact structure are the three characteristics of hard and compact rock. In this kind of rock, common diamond bit can only obtain very low drilling efficiency. Aiming at this kind of rock, this paper presents a method to increase bit specific pressure and self-sharpening ability, with the precondition of maintenance of the bulk strength, gauge-keeping ability and no increase of power consumption. In the diamond-contained layer, cylinder-shaped grinding aids were distributed with certain pattern. Cylinder-shaped grinding aid was made up of adhesive and grinding medium. Its specification, number and performance were adjusted to different rock and performance of diamond-impregnated layer. It was proved by both laboratory and field test to be a kind of effective diamond bit for hard and compact formation.