| 摘要 |
A rock drilling bit for a pneumatic percussion hammer has a bit head and an anvil extending up from the bit head and slidable in the bit drive sub of the hammer. So the bit will be rotated with the hammer without unduly stressing the anvil, the upper part of the bit head is of non-round cross-section and slidable in a socket of corresponding cross-section in the bit drive sub. If the anvil is not integral with the bit head, but is screwed into it, the lower part of the anvil is of matching non-round cross-section so torque applied by the rotating hammer is applied equally to anvil and bit head. |
