| 摘要 |
<p>For forming a through bore through a board (2) of asbestos, two plates (4) of plastics material are adhered on opposite surfaces thereof. Apertures (6) in the plates (4) are aligned. A respective container (8) is supported on each plate (4) such that each container opening (14) surrounds the plate (4). The interior of each container (8) is connected to a respective vacuum cleaner (16) by way of a hose (18). With the vacuum cleaners (16) switched on a drill (24) is extended through one of the containers (8), and through the aperture (6) in the respective plate (4) into the board (2) and drilling is commenced. Material removed from the board (2) by the drilling enters the containers (8) and is extracted to the vacuum cleaners (16) in which it is collected. Once drilling is complete, the bore (28) produced may have its surface sealed or lined.</p> |
