| 摘要 |
PURPOSE:To dispense with the setup of a position sensor and simplify a drill in structure, by detecting a current variation in a drill motor, and also detecting a cutting end of the drill. CONSTITUTION:Avoiding a starting current, the no-load current value is stored by a punching end discriminating system. On the basis of this no-load current, whether it is during drilling or completion or not is discriminated. When punching is started by a drill 9, a current in a drill motor 2 is increased, and the current is monitored by a current detector. When the drilling is cover, a fact that the current comes into a no-load state is detected so that drill rotation is stopped by the drilling end discriminating system, and a feed motor 4 is turned to a reverse mode, whereby a drill 3 goes up and stops, thus drilling operation comes to an end.
|
