DRILL HEAD FOR SHORT HOLE DRILLING IN FROZEN GROUND Russian patent published in 2007 - IPC E21B10/43 

FIELD: rock-cutting tools, particularly drilling bits.

SUBSTANCE: drill head comprises two-wing body 2, blades 2 with hard-alloy cutting plates 5 installed on blade bodies, stem 1 and starting borer 6 with guiding member 7. Working surfaces of cutting plates are sharpened. Two blade rows 3, 4 are arranged on the two-wing body so that each blade row is connected to each body wing. Wings are located so that 180° angle is defined in-between. Pitch between blades 3 of the first row is equal to that of the second row. Blades 4 of the second row are shifted with respect to blades 3 of the first row for value equal to 1/2 of blade pitch. Blade 4 diameter is twice as large as that of blade 3. Cutting edges of blades 3 and 4 are inclined towards head rotation direction. Working surfaces of hard-alloy cutting plates 5 are inclined towards bodies at angle of 20° to provide forward stress concentration in head rotation direction.

EFFECT: conversion of hole drilling operation into high contact stress creation method along with following crack formation accompanied by large particle chipping, collapse, crumbling and generation of dispersed mass, which flows around steel blade bodies.

7 dwg