Core borer

Abstract

Abstract A CORE DRILL STRUCTURE INCLUDES A HOLLOW DRILL SHAFT AT THE END OF WHICN AN ANNULAR TOOL HEAD IS LOCATED. THE END FACE OF THE TOOL HEAD CARRIES A PLURALITY OF CIRCUMFERENTIALLY SPACED CUTTING PLATES THE EDGES OF WHICH SERVE TO DRILL AN ANNULAR HOLE LEAVING CENTRAL CORE WHICH IS ACCOMMODATED WITHIN THE HOLLOW DRILL SHAFT AS THE HOLE DEEPENS. TO PREVENT DAMAGE TO THE DRILL HEAD IN THE EVENT OF BREAKAGE OF THE CUTTING EDGE ON ONE OR MORE OF THE CUTTING PLATES, TWO SETS OF COMBINED STOP AND BRAKE MEANS ARE PROVIDED FOR THE HEAD. ONE SET IS CONSTITUTED BY A PLURALITY OF CIRCUMFERENTIALLY SPECED BRAKE SHOES SECURED TO THE END FACE OF THE DRILL HEAD WHERE THE DRILLING ACTION TAKES PLACE, AND WHICH PROJECT RADIALLY INWARD FOR A SLIGHT DISTANCE BEYOND THE INNER PERIPHERY OF THE ANNULAR DRILL HEAD AND ARE ENGAGEABLE WITH THE PERIPHERY OF THE CORE ONLY AS THE DIAMETER OF THE LATTER INCREASES UPON BREAKAGE OF ONE OR MORE CUTTING EDGES. THE OTHER SET IS CONSTITUTED BY A PLURALITY CIRCUMFERENTIALLY SPACED STRIPS SET INTO GROOVES IN THE OUTER SURFACE OF THE DRILL HEAD AND WHICH RUN PARALLEL WITH THE DRILL AXIS. THESE STRIPS PROJECT RADIALLY OUTWARD FOR A SLIGHT DISTANCE BEYOND THE OUTER PERIPHERY OF THE ANNULAR DRILL HEAD AND ARE ENGAGEABLE WITH THE PERIPHERY OF THE DRILL HOLE ONLY AS THE DIAMETER OF THE LATER DECREASES UPON BREAKAGE OF ONE OR MORE CUTTING EDGES. THE TWO SETS OF COMBINED STOP AND BRAKE MEANS SERVE TO PREVENT CONTACT AS BETWEEN EITHER THE INNER OR OUTER PERIPHERY OF THE ANNULAR DRILL HEAD AND THE SURFACE OF THE CORE OR DRILL HOLE, RESPECTIVELY, AND THEY ALSO IMPOSE A FRICTIONAL BRAKING FORCE ON THE ROTATING DRILL HEAD WHICH CAN BE USED AS A SIGNAL FOR CUTTING OFF THE DRIVING POWER TO THE DRILL SHAFT.

Inventors

• 👤 Alfred Kaser

Bibliographic Details