| 摘要 |
<p>A noncoring drill bit has a washer (2) attached to the head of a shank of a boring tool, a circular column-like first diamond grindstone body (3) fixed to the washer (2) and having cutout recess (10) open to one side, and a second diamond grindstone body (4) placed in the cutout recess (10). The head of the second diamond grindstone body (4) is located on the washer (2) side of the head of the first diamond grindstone body (3). The inner side of the head surface of the first diamond grindstone body (3) is preferably formed as a recess with a substantially mortar-like shape.</p> |
