| 摘要 |
PURPOSE:To quickly demagnetize permanent magnets having different magnet performances by repeatedly and alternaltely supplying a DC current in the forward and backward directions to a coil from the power source and gradually lowering the level of such DC current. CONSTITUTION:An AC input 7 is converted to a DC current by a DC power supply 8 which can freely change an output voltage. A relay BOX10 comprises a switch and a timer for controlling a DC current to ON and OFF and for normal and reverse connections. A field generating coil is connected to an output terminal 11 and it is used as the demagnetization circuit of permanent magnet. The demagnetization circuit of this permanent magnet is connected to the demagnetization apparatus in order to generate demagnetization waveform. For demagnetization, a field is generated in the positive side by flowing a DC current to the demagnetization coil and then a field is generated in the negative side by changing the direction of current with the timer. Such operations are repeated for several times and intensity of magnetic field is gradually reduced by controlling a DC current. Thereby, demagnetization can be realized perfectly irrespective of a kind of demagnetization coil and even when a coersive force of magnet to be demagnetized is unclear. |
