Working principle, method and structure of demagnetizer

Ac demagnetization

1 AC demagnetization pass method
For small and medium-sized workpiece batch demagnetization, it is best to put the workpiece on the demagnetization machine equipped with track and drag plate. When demagnetization, the workpiece is placed on the drag plate and 30cm in front of the coil. When the coil is energized, the workpiece is slowly passed from the coil along the track and away from the coil at least 1m away from the power off. For heavy or large workpieces that cannot be demagnetized on the demagnetization machine, it is also possible to trap the wire on the workpiece, slowly pass the coil through and away from the workpiece when powered on, and power off at least 1m away.

2 attenuation method

Since the direction of the alternating current is constantly reversed, the automatic attenuation demagnetization device or the voltage regulator can be used to gradually reduce the current to zero for demagnetization, such as placing the workpiece in the coil, between the two magnetizing chuck of the inspection machine, or using the support rod contact to contact the workpiece after the current is reduced to zero for demagnetization for the weld of large pressure equipment, AC electromagnetic yoke demagnetization can also be used.

Connect the two poles of the electromagnetic yoke on both sides of the weld, turn on the power, let the electromagnetic yoke move slowly along the weld, and when the power is off 1m away from the weld, demagnetization is carried out.

Direct current demagnetization

Direct current magnetized workpiece with direct current demagnetization, can use DC commutation attenuation or ultra-low frequency current automatic demagnetization.

1 DC commutation attenuation demagnetization

Demagnetization is carried out by constantly changing the direction of the direct current (including three-phase full wave rectifier) while decreasing the current through the workpiece to zero. The number of current attenuation should be as much as possible (generally more than 30 times), and the current amplitude of each attenuation should be as small as possible, if the attenuation amplitude is too large, it can not achieve the purpose of demagnetization.

2 Ultra-low frequency current automatic demagnetization

Ultra-low frequency usually refers to the frequency of 0.5 ~ 10Hz, which can be used to demagnetize the workpiece of three-phase full wave rectification electromagnetization.

Demagnetization of heating workpiece
Increasing the workpiece temperature to above the Curie point by heating is the most effective demagnetization method, but this method is not economical and practical.