WELL REAMER Russian patent published in 2012 - IPC E21B7/28 

FIELD: mining.

SUBSTANCE: well reamer includes hollow housing with inner projection and radial holes, retractable rolling cutters with shanks, annular piston with side hole, bypass channels, inner jet nozzle, cylinder connected to the housing and forming together with annular piston a hydraulic chamber, device for fixing rolling cutters in non-working position, and retainer. Annular piston is spring-loaded upward from the cylinder. Retainer is equipped on the top with a cowling from wear-resistant material and connected to annular piston with possibility of restricted turn. Lower part of retainer is made in the form of a downward converging pyramid. At that, shanks of rolling cutters are made so that they can be moved along the appropriate taper surfaces of the pyramid. Jet nozzle is made on the inner side from below in the form of a downward diverging cone, and cowling is made in the form of a cone mating with cone of jet nozzle. Cross-section area of the through channel of jet nozzle, surface area of the through channel between taper surfaces of jet nozzle and cowling and surface area of bypass channels are almost equal.

EFFECT: uniform flow velocity of drilling fluid and minimisation of the wear of the mechanism setting the rolling cutters to working position.

2 cl, 4 dwg