| 摘要 |
PROBLEM TO BE SOLVED: To provide a core drill by which a water passage to the apex of a drill head is formed regardless of relative positions of the drill head and a shank in the circumferential direction in the core drill in which the drill head is removably fitted to the shank. SOLUTION: The main body of a drill head 3 is constituted of an inner cylinder 9 and an outer cylinder 11 to form an annular space (the second passage) 13 between them. Diamond chips 15 are fitted on the apexes of the inner cylinder and the outer cylinder to form an opening between adjoining chips. A channel 29 extending in the axial direction is formed on the outer periphery of a shank 5 and a pipe (the first passage) 33 is arranged in this channel. When a fitting part of the drill head is fitted on a part to be fitted of the shank, the first passage and the second passage are communicated with each other to form a water passage communicated with the apex of the drill head.
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