| 摘要 |
PROBLEM TO BE SOLVED: To provide a drill bit crushing a core generated in drilling work and discharging the crushed core to the outside. SOLUTION: In the drill bit 1 having a hard cutting blade 3 in a cylindrical body opening part 2a, a tapered protrusion 4 extended to a direction of the opening part 2a and having a distal end positioned in the inner space 2d of a cylindrical body part 2 is provided in the inner space 2d of the body part 2 storing the core generated in drilling a material to be cut. The protrusion 4 is formed into a conical or pyramidal shape, and a hard cutting blade 6 is provided on a distal end of the protrusion 4, and the generated core can be effectively crushed. COPYRIGHT: (C)2011,JPO&INPIT
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