| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a simply structured machining apparatus capable of accurately detecting a contact between a tool and a workpiece. <P>SOLUTION: An insulated electrode member 17e is disposed in proximity to a pressure receiving section 16a of a rotor shaft 16, and a capacitor C is formed between the pressure receiving section 16a and the electrode member 17e. When a current is supplied to a stator 19b from an inverter power supply 20, an axial voltage is induced to the rotor shaft 16. The axial voltage is also induced to the electrode member 17e via the capacitor C, and a detecting device 29 that detects the axial voltage is connected to the electrode member 17e. When a spindle moves down and the axial voltage having been detected is not detected any more because a leading end of a drill 5 is brought into contact with the grounded workpiece, the detecting device 29 outputs a detection signal to an NC device 30. When the detection signal is input, the NC device 30 determines that the drill 5 has been brought into contact with the workpiece, and forms a hole as far as a predetermined depth from that position, using the drill 5. <P>COPYRIGHT: (C)2012,JPO&INPIT |
