CENTERING MOUNT Russian patent published in 2001 - IPC

FIELD: drilling equipment, gears centering lower part of drill pipe string. SUBSTANCE: centering mount has body with internal concentric hole and three separable centering extending blades with external spiral-shaped centering or calibrating surfaces and internal flat surfaces. T-shaped grooves each housing two peripheral shanks of pistons of identical form mounted in parallel one another are cut on center. Two radial holes are made under blades. On opposite end face pistons are also provided with T-shaped shanks pressed by springy members into body. Blades of centering mount can self-countersink in body when tool is lowered into borehole, they start extend only in process of operation because of pressure difference inside string and in pipe clearance. EFFECT: increased operational reliability and improved functional characteristics of centering mount. 1 cl, 2 dwg