WELL EXPANDER Russian patent published in 2016 - IPC E21B7/28 

FIELD: oil industry.

SUBSTANCE: invention relates to devices for enlargement of wells diameter within specified limits. Rounder includes a hollow housing with an inner ledge and radial holes. Holes accomodate extending hinged cutting elements with internal shanks and hard-alloy teeth on the working surface. Inside the housing cavity there is a hollow pusher with a device for connection to the drill string and cone-shaped holder. Retainer is configured to interact with the shanks of cutting elements in order to pull them out during the downward movement of the pusher. Pusher above the projection has a running thrust no-go thread on the outer surface. Housing is equipped with a spring-loaded inside element interacting with recesses of the running thread. In non-operating position the cutting elements retainer has the shape of an interacting in the upper position of the pusher internal projections of a cutting element shank with an outer retainer ring catch. Latter is configured to enable disengagement from projections of the shank during downward movement of the pusher. This excludes wear of the rounder caused by abrasive substances, pumped with cleaning fluid. Invention allows to perform intermediate washing of the well shaft.

EFFECT: ensures complete opening of the device in working position.

1 cl, 2 dwg