| 主权项 |
1. A drilling system for drilling vertical holes in a mine roof, comprising:
a chuck configured to be driven in rotation by a motorized drill driving device, said chuck having a first polygonal inside perimeter; a drill member having an elongated hollow body having open ends, having a cross section defining a circular outside perimeter over most of its length and a constant, second polygonal inside perimeter along the entire length of said drill member, said drill member having at least one end region having a first polygonal outside perimeter sized to fit into said first polygonal inside perimeter to rotationally engage the drill member with the chuck; and a drill bit rotationally fixed to a base shank, extending rearward thereof, said base shank having a cross section with a second polygonal outside perimeter sized and configured to fit snugly inside said second polygonal inside perimeter; wherein when viewed in a longitudinally axial direction, the first polygonal outside perimeter of the at least one end region is sized and shaped for the at least one end region to be radially circumscribed within the circular outside perimeter of the elongated hollow body. |
