WELL REAMER Russian patent published in 2013 - IPC E21B7/28 

FIELD: oil and gas industry.

SUBSTANCE: well reamer includes a hollow housing with an internal projection and radial holes, in which there installed are movable rolling cutters with shanks, an annular piston with a side hole arranged in the housing cavity and fixed against being rotated, with upper and lower props on outer surface and a connection device to a drill column, a cylinder connected to the housing and forming together with the annular piston a hydraulic chamber interconnected with its side hole to the housing cavity, a fastener installed in the annular piston with possibility of interaction with shanks of rolling cutters and the inner projection of the housing and device for locking of rolling cutters in a non-working position, which contains additional annular piston located in the reamer hydraulic chamber below the side hole of the main piston; at that, the device for locking of rolling cutters in the non-working position is made in the form of radially spring-loaded segments located in external slots of the piston, and counter cavities of those segments in the cylinder, and between additional piston and annular segments of the device for locking of rolling cutters there installed is a pusher for disengagement of segments from the reamer cylinder. From above the annular projection of the housing there arranged on inner side are elements that are elastic in axial direction, which have the possibility of interacting with lower end of the annular piston at its downward movement relative to the housing.

EFFECT: improving durability and serviceability of the reamer, reducing vibrations of a drilling tool during reaming process of the well, and increasing service life of rolling cutters of the reamer.

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