Single movement double core tube internal and external tube has bearing isolation, pipe outer pipe driven only pick up bit rotation, and broken rock tube does not rotate, avoid to core friction, vibration, etc., with mechanical damage, so it in serious loose fractured formations.these, can be well protected cores.
Use double deck core tube take core, bits need to use wall thickness of the alloy drill or diamond bits.
Due to the rock drill contact surface area increased and the lip use double deck core tube than ordinary core tube drilling efficiency to reduce. In the ledge, coal, in order to guarantee rock (mineral) heart take rate, rules must be use double deck core tube coring. More complex double core tube, except to finish single movement, in addition, aluminum, steel tube placed plastic or qualitative buckled half close tube, have a better protection of the core role.
Double core tube card broken cores and seal block within the next port, the core tube by the drill is placed in the core card fault device (fern, card spring, claw reed, etc.) to finish.
