Verbesserungen an Rollenbohrmeisseln

摘要

A rolling cutter drill bit comprises a body (12) and three legs (14), each leg having a cantilevered bearing spindle (16), a rolling cutter (18) rotatably mounted on the bearing spindle, lubricant delivering means (22,24,26) within the bearing spindle, and a floating thrust bearing element (46) configured to carry onward thrust loads from the rolling cutter (18) onto the bearing spindle (16). Each floating thrust bearing element (46) is formed of a wrought alloy material consisting primarily of chromium carbide and cobalt and having a yield strength of less than 120,000 psi and a ductility of at least 4%, both at room temperature. $$