Rotary abrasive drilling bit

Claim 1

A rotary abrasive drilling bit comprising a bit body attached to a rotary drill pipe and a plurality of teeth equipped on the fore part of said bit body, wherein each of said teeth is composed of a plurality of tungsten carbide thin sticklike cutting elements and a matrix that is softer than and inferior in abrasion resistance to said elements, all said sticklike tungsten carbide elements extending along the cutting direction of said bit body and orderly arranged in each tooth with a desired space therebetween radially as well as circumferentially of the bit body with the ends located in a zig-zag path transverse to said cutting direction, said matrix surrounding the tungsten carbide thin sticklike elements and maintaining them in the aforesaid arrangement, and the cutting face of said tooth being composed of a compound surface consisting of the end faces of the tungsten carbide thin sticklike elements and the surface of the matrix, whereby when the edges of the tungsten carbide thin sticklike elements are worn down and shortened with the progress of drilling work the surface of the matrix is also worn down to the same extent in concert therewith to maintain the teeth suitable for drilling purposes.