| 摘要 |
A drilling apparatus includes a drilling rod, a feed motor for advancing and retreating the rod in relation to an object to be drilled, and a control system for controlling the movement of the rod. The control system includes a pulse generator for producing one long duration pulse upon completion of each rotation of the drilling rod, an oscillator for producing high frequency pulses, a counter for counting the number of high frequency pulses during the long duration pulse, and a control circuit for controlling the feed motor in response to the counted number of pulses, the control system operating so that the counted number of high frequency pulses equals a predetermined number during the period of the long duration pulse. The control system is arranged to increase the advancing force of the drilling rod when its rotational speed increases (i.e.-when the counted number of high frequency pulses decrease) and the control system is arranged to decrease the advancing force of the drilling rod when its rotational speed decreases (i.e.-when the counted number of high frequency pulses increase). Thus, the control system stabilizes the rotational speed of the drilling rod by advancing and retreating the rod, thereby optimizing the drilling operation.
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