| 摘要 |
The present invention relates to a drill bit (11) intended to be included in a drill string (10) for top hammer drilling, said drill string (10) including a set of central rod members (12) for transferring impact energy to the drill bit (11) and a set of tubular members (13) surrounding the set of rod members (12) for transferring rotation to the drill bit (11). The invention also relates to a tubular member (13b) and to a drill string (10). In drilling equipments of the type mentioned above it is favourable - especially for greater diameters, preferably above 125 mm - to guide the flushing medium in an internal channel in the set of rod members (12). In order to guarantee lubrication of the splines coupling (14) through the lubricant that is mixed into the flushing medium, an intermediate section (16a) of the drill bit (11) is provided with branch channels (16c, 16d) to discharge the flushing medium to and from a recess (18) in the space between the drill bit (11) and the set of tubular members (13).
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