DIAMOND REAMER Russian patent published in 2000 - IPC

FIELD: rock-breaking tools. SUBSTANCE: invention is meant for calibration of holes in process of rotary drilling. Diamond reamer includes body and diamond-carrying moulds separated by washing ducts whose cross-section area equals cross-section area of diamond-carrying moulds. External surface of body has stepped shape so that diameter of lower step joined to body of drill bit is not less than outer diameter of body of drill bit and diameter of upper step of body of reamer D₄ is found by formula , where D₁ is diameter of drill bit, mm; D₂ is diameter of lower step of body of reamer, mm; D₃ is diameter of reamer over diamond- carrying moulds, mm. Inlet edges of washing ducts are conical with acute angle α at vertex of cone. EFFECT: increased resistance of diamond reamers thanks to avoidance of drop of velocity of upward current of washing fluid after it goes out of washing ducts and thanks to prevention of jamming of reamer with abrasive mud in process of drilling. 1 dwg, 1 tbl