| 摘要 |
PROBLEM TO BE SOLVED: To provide a core bit in which diamond tips are welded or soldered circumferentially for fixing at appropriate intervals along one edge of a body made of a thin steel tube and which can discharge cut powder smoothly even when the diamond tips wear and thus eliminate such trouble that clogging by the cut powder makes drilling impossible. SOLUTION: A groove 24 extending from one end to the other end of the body between diamond tips in the axial direction in the inner peripheral surface of the core bit is formed in each interval between the diamond tips 22. The formation of the grooves 24 ensures discharge passages for the cut powder even when the diamond tips wear and eliminate clearances between the inner peripheral surface of the core bit and the core 12 of a to-be-cut material. COPYRIGHT: (C)2010,JPO&INPIT
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