COMPLETE NOTES ON DRILLING & BLASTING_NPTEL
NOTES ON DRILLING AND BLASTING AS PREPARED BY NPTEL
CLASSIFICATION OF DRILLING MACHINES
Rotary percussivepercussive-DownDown-thethe-Hole ( Drilling The driving fluid of the hammer is compressed air that is supplied through a tube
which serves as support and makes the hammer turn. The rotation and thrust force are carried out by two separate hydraulic motors
(or pneumatic motors) mounted on the surface rig. Flushing is carried out with the exhaust air of the hammer through the holes in
the drill bit. Since the annulus between the drill pipes and the hole wall is comparative small, a high flushing velocity is maintained, which contributes
further to hole quality quality.
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