| 摘要 |
An electronic control, for automated earth drilling using a pneumatic hammer-operated bit, preliminarily weighs a drill string, and, during drilling, automatically maintains a desired weight on the bit, and also maintains a constant rate of drilling progress by regulating drill string rotation speed. The weight on the bit is automatically maintained at a fraction of the pre-established desired weight as the air pressure in the supply to the pneumatic hammer builds up to an operating level. The control detects voids and broken formations by monitoring air pressure and torque respectively, and responds by reducing the weight on the bit. The control automatically raises the drill bit though a short distance as the drill head reaches the lower limit of its travel, pauses until the air pressure drops, and then raises the drill string to a position for insertion of a new length of pipe.
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