| 摘要 |
<p>PURPOSE:To enable to slidably move a pipe A and a pipe B extending over a long time to obtain an effective dust collecting device by directly connecting an expansion hose to a feed pipe B to pass dust. CONSTITUTION:A spring 11 and a pipe B6 are arranged on the inner circumfer ence of a pipe A5, and an expansion hose 8 directly connected to the pipe B6 is fitted inside the spring 11. Accompanied with progress of drilling, a main body 1 is advanced, and a hood is relatively retreated against the main body 1 in the condition of contacting with the surface of drilled material. In this case, the pipe B6 is slidably moved in the inner circumference of the pipe A5 to push the spring 11 backward. Dust generated by drilling is passed through the hood, the pipe B6, and the hose 8. Hereby, dust is not intruded between the pipe A5 and the pipe B6, and the sliding part can not be clogged.</p> |
