| 摘要 |
PROBLEM TO BE SOLVED: To provide a core drill capable of extending the axial length corresponding to the depth of the hole to be bored. SOLUTION: The core drill includes a blade body 1 equipped with a cylindrical drum 1A, a blade 1B formed at its forefront, and an engagement part 1C formed at the base end of the drum 1A, a drive shaft side attaching part 2 equipped with a cylindrical drum 2A, a part to be engaged 2B formed at its forefront for making engagement with engagement parts 1C and 3C, and an attaching part 2R to be attached to the drive shaft side of a rotary tool formed at the base end of the drum 2A, and at least one extension cylinder part 3 to be put in service selectively equipped with a cylindrical drum 3A, a part to be engaged 3B formed at its forefront and able to be engaged with the engagement part 1C, and the engagement part 3C formed at the base end of the drum 3A and able to be engaged with the part to be engaged 2B, wherein the drive shaft side attaching part 2 is coupled with the base end of the blade body 1 directly or through the extension cylinder part 3 in such a way as complying with the depth of the hole to be bored. COPYRIGHT: (C)2007,JPO&INPIT
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