| 摘要 |
The present invention relates to a rock drill bit for percussive drilling, comprising a head (11) and a shank (12). The shank (12) has a central boring in which a thread (14) is provided. The thread (14) is provided to cooperate with a corresponding thread in a drill string driven by a top hammer. The boring is connected to at least one fluid passage (15), which emerges in or in the vicinity of a front face (16) of the head (11). The fluid passage connects to a first groove (17), which connects to a second groove (18) wherein at least three second grooves are provided and form between them axially forward lands. Each land carries a gauge insert (21). The gauge inserts (21) are asymmetrically positioned on the drill bit and the second groove (18) extends radially inwards to or beyond an imaginery circle (C) touching the radially innermost points of the inserts (21) generally in the plane of the front surface (16). |
