DRILLING TOOL

• Main Authors: NAKAMURA KAZUYOSHI, HISADA KIMIYA
• Format: Patent
• Language: English
• Published: 16.08.2012
• Subjects: EARTH DRILLING; EARTH DRILLING, e.g. DEEP DRILLING; FIXED CONSTRUCTIONS; MINING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS

PROBLEM TO BE SOLVED: To provide a drilling tool for performing smooth boring at lower costs.SOLUTION: A drilling tool in the present invention comprises a casing top 1 that is connected to the tip of a casing pipe; and a ring bit 3 which is attached to the tip of a casing top 1 coaxially therewith and rotatably around the axis O of the casing top 1 and is engageable with an inner bit inserted through the casing pipe at the tip side on the axis O direction and around the axis O. A protruding streak portion 8 is formed on the outer peripheral surface of the ring bit 3 around the axis O, while an annular groove 9 is formed on the inner peripheral surface of the casing top 1 for accommodating the protruding streak portion 8. The casing top 1, having an elastically deformable C-shape cross section perpendicular to the axis O, is enlarged in diameter to accommodate the protruding streak portion 8 in its annular groove 9, and is then reduced in diameter to make a butt part 10 of the casing top 1 to be joined so that the ring bit 3 is engaged at the rear tip side on the axis O direction and rotatably around the axis O.