Grinding tool for buttons on a rock drill bit

Abstract

A grinding cup for detachable connection to the output drive shaft of a grinding machine for grinding buttons on drill bits or cutters, said grinding cup having top and bottom surfaces and consisting of a lower grinding section and an upper body section with a centrally disposed recess formed in the bottom surface of the grinding section; said body section having a centrally disposed upright drive section formed on the top surface of the grinding cup, said drive section shaped and sized to both driveably engage within a corresponding recess at end of the output drive shaft and provide axial and radial support and retaining means for detachably connecting the grinding cup to the output drive shaft wherein said drive section has a non-circular cross section and is tapered from the top surface of the grinding cup to the free end of the drive section.

1 . A grinding cup for detachable connection to the output drive shaft of a grinding machine for grinding buttons on drill bits or cutters, said grinding cup having top and bottom surfaces and consisting of a lower grinding section and an upper body section co-axial with said grinding section to form said grinding cup with a centrally disposed recess formed in the bottom surface of the grinding section having the desired profile for the button to be ground; the improvement characterized by said body section having a centrally disposed upright drive section, said drive section shaped and sized to driveably engage within a corresponding recess at end of the output drive shaft of said grinding machine and retaining means for detachably connecting the grinding cup to the output drive shaft of the grinding machine wherein said drive section has a non-circular cross section and is tapered from the top surface of the grinding section to the free end of the drive section. 
     
     
         2 . A grinding cup according to  claim 1  wherein the drive section has an elliptical cross section. 
     
     
         3 . A grinding cup according to  claim 1  or  2  wherein the upper body section has a base with the centrally disposed upright drive section formed on a top surface of the base. 
     
     
         4 . A grinding cup according to  claim 1 ,  2  or  3  wherein means to connect the grinding section to the upper body section are provided on the top surface of the grinding section. 
     
     
         5 . A grinding cup according to  claim 4  wherein the means to connect the grinding section to the upper body section consists of a generally cylindrical stub centrally located on the top surface of the grinding section, the stub being sized and shaped to be inserted into a corresponding cavity on the upper body section in a manner that will prevent the grinding section from rotating or spinning free relative to the upper body section and that will support axial, radial, torsion and feed forces associated with the use of the grinding cup. 
     
     
         6 . A grinding cup according to  claim 5  wherein the bottom surface of the base on the upper body section has cavity formed therein sized and shaped to accommodate the cylindrical stub centrally located on the top surface of the grinding section. 
     
     
         7 . A grinding cup according to any one of  claims 1 - 6  wherein retaining means for detachably connecting the grinding cup to the output drive shaft of the grinding machine are provided on the upright drive section. 
     
     
         8 . A grinding cup according to  claim 7  wherein the retaining means  38  comprises an annular groove in the outer surface of the upright drive section sized and shaped to retain an O-ring. 
     
     
         9 . A grinding cup according to  claim 3  wherein the grinding cup is one in a series of grinding cups for grinding the working tips or buttons of rock drill bits wherein the working tips or buttons have a diameter of about 6 mm to 26 mm and a desired profile, and wherein the base of the upper body section of each grinding cup in the series is sized so the distance from the top surface of the base to the center point of the radius of the convex recess in the grinding section is constant across the series of grinding cups. 
     
     
         10 . A holder device for detachable connection of a grinding cup to a grinding machine, said grinding machine having a pneumatically, hydraulically or electrically driven motor which drives an output shaft, the holder device comprising a rotatable drive member having a free end adapted to extend axially away from the the grinding machine, a non-circular recess in the free end of the drive member with a coaxial passageway extending from the recess the length of the drive member or part thereof and through which coolant fluid may be directed to a grinding cup supported thereon, the cross-section of the recess being tapered inwardly from the free end of the drive member.