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. Cutters, their holders and shanks made integral with the latter feature cylindrical shape and common rotational axis located at mid diameter of bit body or shifted towards larger bit body diameter on one side of cutters and towards smaller diameter on opposite part of cutters. Cylindrical shanks of holders with groove making the top and bottom ring ledges along with thrust bearing resting thereon and compression ring pack fit in blind holes from the 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 while first row cutters stay in permanent contact therewith in drilling. Cutter holders of all moving rows along, apart from the top one, 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. while shanks of top row are retained by steel ball fitted via bit body side bore in ring groove made at shank lower end.

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

4 dwg