The commonly used demagnetization machine
There are several commonly used demagnetization machine:
(1) AC coil demagnetization machine for small and medium sized workpiece mass demagnetization, often using AC demagnetization coil device. It is the use of automatic reversing AC; principle of magnetic field intensity decays from the demagnetization coil. The central magnetic field strength of the coil is generally 16 ~ 20kA/m (E 200-250O), the coil frame is usually rectangular, the size of the workpiece is adapted to the workpiece, the power supply voltage can be 220V or 380V. Large stationary demagnetization coil often equipped with rail and carrying cart, and placing the workpiece in order to move. Demagnetization of the workpiece is placed in the car, turning on the power supply from the coil through and along the track from the near to the distant leaving the coil, cut the power beyond 1.5 m from the coil. Some equipment is also equipped with a timer, a switch and an indicator lamp, from the control of demagnetization process. Also the workpiece is placed within a coil, the coil current amplitude gradually reduced to zero by the method of demagnetization
(2) reversing DC attenuation demagnetization machine (ultra low frequency demagnetization) for DC electromagnetic workpiece, in order to make the inside of the workpiece can obtain good demagnetization is often used commutated DC attenuation demagnetization method. This device can change the polarity of the electric current through mechanical or electronic commutation, and the current can change the direction of the current to zero gradually when the current passes through the workpiece. This frequency can be adjusted to the low frequency, so it is called the ultra low frequency current. The ultra low frequency DC demagnetization current skin effect is very small, within the range of workpiece demagnetization. The frequency of its current is usually 0.5 ~ 10Hz, which can be used to turn on or turn on the switch of the alternating current or the thyristor. The attenuation obtained by different resistance resistor in series current phase, also can use the thyristor, and current attenuation. In this case, thyristor as well as reversing the contactless switch, in reversing the demagnetization current, safe and reliable and low noise. This kind of equipment to ensure the demagnetization current zero switching in the circuit, so that the equipment will not be damaged.
(3) AC buck attenuation demagnetization machine in addition to the current in the coil by the amplitude drop to zero the demagnetization method, the electromagnetic current from the amplitude gradually reduced to zero method for demagnetization. The method is to adjust the main transformer of the main transformer of a current, then from big to small gradually to zero. Because the AC itself constantly changing direction, and then decay current changing the size of the magnetic field, so as to achieve the purpose of demagnetization. There are two kinds of AC voltage regulation method. One is the mechanical method, which is mainly controlled by electric or manual mode. The other is the power to adjust the voltage, the trigger circuit of the thyristor automatically causes the voltage in the circuit to be from the big to the small to zero, this method is used for the electronic voltage regulation device. Buck used in AC electromagnetic attenuation demagnetization of the workpiece. In addition to AC magnetic blunt demagnetiser and flat coil demagnetization device, mainly used for steel plate and weld inspection after demagnetization.