BORKRONE.

摘要

A drill bit for use in a drill string comprising a set of a plurality of central rod members and a set of a plurality of tubular members surrounding said rod members. The drill bit is provided with a longitudinally extending flushing channel which communicates with an annular space between the rod members and the tubular members via a transverse passage. The flushing channel comprises at least two end passages terminating in the bit front. The cross section area of each of the end passages is smaller than the overall cross section area of the portion of the flushing channel located between the end passages and the transverse passage.