| 摘要 |
PROBLEM TO BE SOLVED: To provide a bit attachment and detachment mechanism of a concrete drill or the like capable of preventing an attaching failure of a bit by temporarily fixing bit mounting without increasing the size of a chuck.SOLUTION: An engaged portion 33 is formed at the outer periphery of a mounting portion 32 of a core bit 30, and the engaged portion 33 is engaged with an engagement protrusion 25 of a chuck cover 24 and drawn, and thereby the core bit 30 is fixed to a chuck 20. In this case, mutually-engaged positioning mechanisms 28, 35 are provided on the end face of an engagement member 26 and on an end face outer periphery 32b of the mounting portion 32 of the core bit 30. The positioning mechanisms 28, 35 are engaged with each other to position a rotation direction of the core bit 30 and the chuck portion 20. |
