| 摘要 |
A coupling device in extension drill equipment for percussive drilling is provided with means (2,3;2,24;2,30) which besides transmitting compressive pulses in the drill string in the direction towards the drill bit by reflection also transforms tensile pulses in the drill string into compressive pulses. Preferably, the joint device includes outer sleeve members (1;21,22;22,27;32,36) axially movable relative each other and provided with cooperating surfaces (2) and an inner rod element (3;24;30) connecting the members. Upon compressive stresses these surfaces (2) abut each other under pressure, while they become separated by tensile pulses. Also preferably, the joint device includes spring means (19) for absorbing torsion pulses in the drill string. |
