Rotary drill bit for use in drilling holes in subsurface earth formations

摘要: A rotary drill bit for use in drilling holes subsurface earth formations comprises a body having shank at one end connection to string and an operating face the other end. plurality of first cutting structures, each comprising preform element, is mounted thereof, has superhard front face. The includes protuberances projecting outwardly from adjacent portions face, forming second structures disposed generally trailing relation, respectively, least some structures. Each impregnated with particles through significant depth measured outermost extremity protuberance. At major operative portion circumferencially separated respective leading structure by open space, likewise radially separatred nearest or