| 摘要 |
<p>The invention relates to a drill bushing for engagement with a drilling steel, wherein said drill bushing ( 2 ) has contact surfaces ( 4 ) for contact with a drilling steel ( 1 ), said contact surfaces ( 4 ) having interior, inwards curved shapes, whereby edge abutment of a drilling steel ( 1 ) against said contact surfaces ( 4 ) is avoided. By way of the invention, a better wear picture is obtained for the shank of a drilling steel.</p> |
