| 摘要 |
A core bit installed on a concrete drill and used for boring a concrete wall, stone, etc. A core bit has a hollow- cylindrical drill portion (12) at one end side of which a boring blade (11) is formed and has a hollow-cylindrical installation portion (13) formed at the other side and installed on a chuck portion of a concrete drill. An engagement member (16) engageable with an engagement portion of the chuck portion is formed on the outer periphery of the installation portion, and the rotation of the concrete drill is transmitted through the engagement member. The core bit is characterized in that a flange portion (15) with a larger diameter than the outer diameter of the engagement member is formed on the outer periphery of the installation portion that is nearer to the boring blade than the engagement member. The engagement portion is protected by the outer periphery of the flange portion; therefore the engagement portion is not damaged nor deformed when dropped or stored. As a result, the problem that the bit cannot be installed on the chuck portion or it is inadequately installed on the chuck portion is prevented from occurring, and boring work can be safely performed. |
