| 摘要 |
<p>An object of the present invention is to provide a shank attachment structure capable of, for example, supplying coolant even if a drill without a center pin is attached. In the shank attachment structure, a shank 30 can be detachably attached to a shank attachment hole 2 with a single motion. The outer diameter of the shank 30 is set such that the shank 30 can be inserted into the shank attachment hole 2. A chamfered portion 33 is formed around an outer peripheral edge of a base end of the shank, and an elongated concave portion 31 is formed on a tip end of the shank. A coolant supplying hole 3 is formed at a body portion 1B on a base end side of the shank attachment hole 2, and a valve body 5 is disposed in the hole 3. A sealing member 4 is disposed at a position that is closer to the tip end side than the valve body 5. A first sleeve 20 is disposed in the shank attachment hole such that: a base end of the shank contacts a tip end of the first sleeve 20 to cause the first sleeve 20 to move, so that a base end of the first sleeve 20 contacts the valve body to cause the valve body to be separated from the sealing member; and in a state in which the shank is not in contact with the tip end of the first sleeve 20, an outer peripheral surface of the first sleeve 20 having an outer diameter substantially equal to a diameter of the shank attachment hole causes the engaging member 15 to move radially outwardly from an inner peripheral surface of the shank attachment hole 2.</p> |
