| 摘要 |
[Object] To provide a method for forming an anchor hole and a diameter expansion device by which a centrifugal force can be appropriately adjusted when a cutting-blade portion is moved in a radial direction by the centrifugal force to grind a diameter expansion portion. [Solution Means] In a method for forming an anchor hole 1 for a post-installed anchor 100 in which a diameter expansion drill bit 20 is inserted and rotated in a prepared-hole portion 3 bored in a concrete fixing body 2 and a cutting-blade portion 31 of the diameter expansion drill bit 20 is moved in a radial direction by a centrifugal force to grind a part of the prepared-hole portion 3 to form a diameter expansion portion 4, the minimum value of the centrifugal force applied to grind the diameter expansion portion 4 is 0.75 N and preferably 1.1 N. |
