| 摘要 |
<p>The present invention relates to an elongate roof bolt having an axially extending central bore and defining a leading end at one end thereof. The leading end includes a pair of axially extending abutment elements formed by machining, each of which includes an abutment face for engagement with a drill tip on opposite sides thereof, to support the drill tip during drilling. The drill tip extends across said leading end and is secured to the abutment elements by welding, soldering or brazing. The bore opens out of said bolt at or adjacent said leading end.</p> |
