| 摘要 |
<p>To provide a user-firiendly core drill which, when forming a large-diameter cut hole by the core drill with respect to an object to be drilled, such as concrete, is able to easily form, for example, a chamfered portion or a countersunk portion with respect to an opening end portion of the cut hole. In a core drill comprising a base body (1) including a shank (5) and a drill core body (2) including a drill cutting blade (13), a connection opening portion (11) of the drill core body (2) being attached to the base body (1), the connection opening portion (11) of the drill core body (2) is provided with a concave portion forming member (3) including a large-diameter hole cutting blade (15), and the large-diameter hole cutting blade (15) is provided outside the drill cutting blade (13) in a radial direction of the connection opening portion (11).</p> |
