LOCK REVERSE CONNECTION OF HOLLOW SECTIONS OF DRILLING OR CASING STRING Russian patent published in 2018 - IPC E21B17/46 

FIELD: mining.

SUBSTANCE: connection comprises a nipple and a coupling interlocked with each other by a gear, splined or other surface capable of transmitting a torque and connected by, at least, one clip receiving an axial force. The clip is made in the form of a curved flexible rod located in an annular cavity formed by grooves made in one transverse plane on the round mating surfaces of the coupling and the nipple. A transverse groove is provided in the coupling wall for inserting a paper clip, which has a hook formed at its end for insertion into the said annular cavity as the string is extended and removed when it is dismantled. The hook is made in the form of a bend made in a plane perpendicular to the plane of curvature of the clip and is located between the outer surface of the coupling and its interface with the nipple in the groove of its wall having a shape corresponding to the shape of the hook.

EFFECT: excluding the force contact of the hook clip with the ground.

6 cl, 8 dwg