Blade-type drill bit

Claim 1

A DRILL BIT COMPRISING: A BIT BODY HAVING AT ITS UPPER END AN AXIAL RECESS AND AT ITS LOWER END A WORKING FACE, SAID WORKING FACE INCLUDING AN UPPER GENERALLY CYLINDRICAL ANNULAR REAMING PORTION AND A GENERALLY SPHERICAL LOWER SURFACE PORTION OF LESSER TRANSVERSE DIAMETER THAN SAID ANNULAR PORTION, SAID WORKING FACE BEING FORMED WITH A PLURALITY OF WATER GROOVES EXTENDING FROM NEAR THE MIDPOINT OF SAID LOWER SURFACE PORTION TO THE PERIPHERY THEREOF AND UPWARDLY THROUGH SAID ANNULAR PORTION, THE WORKING FACE ALONG CORRESPONDING LEADING EDGES OF RESPECTIVE GROOVES PROJECTING OUTWARDLY BEYOND THE TRAILING EDGES OF SAID RESPECTIVE GROOVES FOR SUBSTANTIALLY THE FULL EXTENTS OF SAID GROOVES OVER SAID LOWER SURFACE PORTION TO PROVIDE RIBS, ABRASIVE PARTICLES EMBEDDED IN AND ALONG SAID RIBS TO CONSTITUTE CUTTING EDGES, SAID TRAILING EDGES TOGETHER WITH SUBSTANTIALLY FLAT SURFACES EXTENDING THEREFROM BEING FREE OF ABRASIVE PARTICLES AND FUNCTIONING DURING THE DRILLING OPERATION AS BUMPERS TO DETERMINE THE EXTENT OF THE BITE TAKEN BY SAID CUTTING EDGES THERE BEING BORES EXTENDING FROM SAID AXIAL RECESS TO SAID GROOVES TO DISCHARGE DRILLING FLUID THEREINTO.