| 摘要 |
A rotary mine drilling bit for making blast holes having a connection at one end of the body for attachment to a drill string and the second end of the body having a plurality of longitudinally extending slots. A thrust shoulder is provided between the ends of the body and longitudinally extending supporting legs are positioned in each of the slots and are releasably connected to the body. One end of the supporting legs are positioned the adjacent the shoulders for receiving longitudinal thrust and for avoiding thrust on the connecting means. A roller bit is connected to the end of each supporting leg. |
