| 摘要 |
<p>The handpiece for a dental drill has an angle head with a tool holder sleeve (5) projecting from it. Immediately adjacent to the projecting part, is a jet for a spray of cooling liquid. To prevent liquid from entering the head at this point, a conical sealing ring (7) is mounted on the projecting part. For the same reason, the interior of the projecting part incorporates a helical groove (8). The threads of the helix are suitable handed in the opposite direction to that of tool rotation to prevent liquid entry. Alternative methods use various types of slots around the tip of the sleeve, and behind them, a shorter conical sealing ring.</p> |
