BOREHOLE FISHING DEVICE Russian patent published in 2007 - IPC E21B31/08 

FIELD: mining, particularly fishing devices for freeing pipe string having head part stuck in well cavity.

SUBSTANCE: device comprises body with axial channel and stepped outer surface, through cone and milling crown fixedly connected with the body, guiding means having end slot for damaged string receiving and connected with body through shear member, fixing unit for guiding means retaining relatively well wall, as well as centrator for damaged string arranged in milling crown interior. Minimal inner diameter of centrator is less than inner diameter of lower through cone end. Fixing unit is made as dies spring-loaded in radial direction and pivotally retained in through slots made in guiding means and drive cooperating with dies. The drive is made as bush with conical end rotary secured to outer surface of milling cone.

EFFECT: increased operational reliability and efficiency.

4 cl, 1 dwg