| 摘要 |
<p>The drill (231) produces a radial enlargement (24) along a cylindrical elementary drilled hole (22) in concrete masonry. It comprises at least one cutter (246) mounted in a slot (244) in a drill sleeve (242) which enters the hole. This cutter is held to be fixed in the peripheral direction and axially but movable radially by an inner spreader (237) . This has chamfered surfaces, which is movable axially relatively to the drill sleeve. This spreader is in one piece with the tool shank (236) which is directly rotatively driven. It is movable axially relatively to the drill sleeve and is close-fitted in the peripheral direction.</p> |
