Patent ID: 8245798
Filing Date: 2012-08-21
Classification: E21B,Y10T

Abstract:
1. A female part for top hammer-drilling equipment, comprising a hollow space defined by a centre axis, said hollow space extends to an opening in a free end of the female part and is delimited by a surrounding wall and by a stop shoulder axially spaced from the free end, a female thread formed on an inside of the wall in the shape of a ridge, which has a rotationally symmetrical shape and extends helically along the inside of the wall, said ridge being concentric with the centre axis of the hollow space, and being delimited by a crest and two flanks between which a helical groove runs, said groove having a bottom, said thread having full profile along a main section of a predetermined length parallel to the centre axis, and comprising a thread end positioned between the full profile section and the stop shoulder and in which the groove runs out, wherein the depth of the groove successively diminishes towards said thread end and is carried out under a half-turn, said thread end being defined by a borderline, which separates the groove bottom from a part surface formed in the inside of the wall, said part surface having the same rotationally symmetrical shape as the thread by having a diameter corresponding with either a diameter of the crest of the thread or a diameter of the groove bottom of the thread.