| 摘要 |
FIELD: oil and gas production. ^ SUBSTANCE: drilling bit includes bit housing, head having longitudinal central axis and containing the front surface as to axis direction, front surface for rock crushing, and skirt, which as to axis direction, passes backwards from rock crushing surface. The latter includes several rock crushing devices. Circumferential external surface of skirt is comprised by grooves equally spaced in a circumferential direction and forming edges between each other. Grooves and edges pass in general in axial direction. Rear part of edge as to axis direction is equipped with guide surface facing radially outwards. Guide surface includes at least one projection or inclined surface for providing stepped or gradual decrease of diametre size. Guide surface includes the first guide part and the second guide part, which are located radially outwards from imaginary line passing from narrowing. Relative to central axis of drilling bit, the first guide part protrudes radially outwards more than the second part. ^ EFFECT: increasing service life of drilling bit, and drilling of straighter well bores. ^ 8 cl, 7 dwg |
