MILLING TOOL FOR CUTOUT OF WINDOW IN WELL CASING STRING Russian patent published in 2013 - IPC E21B29/06 

FIELD: oil and gas industry.

SUBSTANCE: device includes starting, straight-through and calibrating mills-reamers with cutting plates fixed in them. Starting and straight-through mills-reamers are made in the form of a single hollow housing. Calibrating mill-reamer is rigidly fixed on a hollow shaft. Cutting plates in the straight-through and calibrating mills-reamers are located with similar eccentricity and opposite on both sides relative to central longitudinal axis of the hollow shaft. The calibrating mill-reamer and the single housing of the starting and the straight-through mills-reamers are provided with screw channels. The calibrating mill-reamer with screw blades and the hollow shaft are made in the form of a single hollow calibrating module. In the front part of the calibrating module there made along the axis in front of screw blades are longitudinal cavities coinciding in circumferential position with longitudinal slots of screw blades. In each cavity there fixed is a front cutting plate with projection above outer surface of the front part of the calibrating module along the axis in front of screw blades, as well as with projection above the front surface of screw blade of the calibrating module.

EFFECT: increasing service life and improving reliability, thus providing uniform wear of cutting plates.

4 cl, 10 dwg