MULTI-ROW CROWN BIT Russian patent published in 2014 - IPC E21B10/02 E21B10/48 

FIELD: process engineering.

SUBSTANCE: invention relates to rock crushing tool. Proposed crown bit comprises several rows of cutters located at different spacing from well work face. Top fixed row is arranged at their holders composed by ledges made at bit body end alternating with holders of several bottom moving rows of cutters. Note here that cylindrical shanks of said holders have a flat groove making upper and lower ledges and rigidly engaged with said holders fit, along with compression spring packs, in blind holes at bit body end, parallel with its axis. Compression force of springs in every row complies with axial load of rock crushing for given row to be crushed thereby. Note here that every next superlying row is intended for higher-hardness rocks compared with previous underlying row. Note here that the cutters of first row from work face stay in permanent contact therewith in drilling. Cutter holders of moving rows along with pre-contracted packs of springs are retained in place due to thrust of cylinder shank flat groove top ledge against top face of thrust ring welded of two halves, fitted in ring groove made at bit body outer surface. Top face of cutter holder of every moving row has cross-section shaped to a step with it ledge fitting in appropriate step made in cross-section of bit body.

EFFECT: longer life, higher mechanical rate, lower power input, fast round-trip.

5 dwg