CUTTING-TYPE DRILLING BIT Russian patent published in 2004 - IPC

FIELD: mining industry. SUBSTANCE: cutting- type drilling bit has body and mobile blades coupled to body by means of axles and reinforced by wear-resistant plates forming nonrectilinear convex cutting edge, cutting with angle α in central part of bit between mobile blades which diameter can narrow, springy inserts placed in spaces of body between body and mobile blades. Mobile blades are mounted for turn in plane of their front faces around axles which are located in peripheral part of body and change of form of cutting by decrease of cutting angle from α to 0 degrees. Tangent line drawn through cutting edge of wear- resistant plates in peripheral part of cutting edge of blades forms with axle of bit angle equal to half-angle α/2 of cutting. Springy inserts come in the form of wedge with angle equal to half-angle α/2 of cutting facing peripheral part of body. Body and mobile blades are faired by surfaces made by radii of circumference with centers in axles and have thrust collars on matched surfaces positioned for interaction with maximal diameter of cutting. EFFECT: increased efficiency of drilling of rocks alternating by hardness thanks to change of form of cutting of bit. 3 dwg