| 摘要 |
A rock drill for percussion drilling comprising a central button insert and a row of outer button inserts. The central button insert extends beyond the outer inserts. For purposes of increasing the drilling rate and the life of the rock drill the ratios of respectively this extent (X) to the diameter (D) of the hole; X:D, and the transverse distance (Y) between the central insert and one of the outer inserts and the diameter (D); Y:D, shall be within predetermined limits. |
