Drill crown used in mining - has shaft with cone-shaped faceted end and suitably recessed head

摘要

The drill crown used in mining is composed of a shaft (4) and a head (5) which are detachably fixed together. A polygonal ended shaft (4) fits into the head (5) which is similarly shaped, and its facets (6) run longitudinally with rounded arrises, the contact surfaces (43) overall being cone shaped. When the shaft end is fitted in the recess in the head, it is secured by transverse pins (11) driven in to grooves (15) in the shaft end, at right angles to the long axis. USE/ADVANTAGE - Detachable drill crown uses shaft and head which are easily assembled or exchanged and are resistant to wear.