Full-tube pulse demagnetization device and method

Abstract

The invention provides a full-tube pulse demagnetization device and method, and the device comprises a demagnetization control unit and a demagnetization power supply; the demagnetization control unitis connected with a DC demagnetization switch and an AC demagnetization switch which are respectively used for switching on and switching off a DC demagnetization coil and an AC demagnetization coil;the demagnetization power supply comprises a demagnetization alternating-current power supply and a demagnetization direct-current power supply which are used for supplying power to the alternating-current demagnetization coil and the direct-current demagnetization coil respectively, and the central axis of the direct-current demagnetization coil and the central axis of the alternating-current demagnetization coil are located on the same horizontal line; the number of turns of the direct-current demagnetizing coil is gradually reduced from one end far away from the alternating-current demagnetizing coil to one end close to the alternating-current demagnetizing coil. The demagnetizing device is convenient to use, good in demagnetizing effect and capable of meeting the online use requirement.

Description

technical field [0001] The invention belongs to the technical field of steel pipe body demagnetization, and in particular relates to a pulse demagnetization device and method for a full pipe body. Background technique [0002] The main problem of demagnetization in the steel pipe industry is that the DC residual magnetism is difficult to meet the standard. According to the requirements of API 5L, the residual magnetism of the steel pipe after demagnetization is less than 30Gs. [0003] At present, the general method in China is demagnetization by DC hedging and AC supplementation, and the speed meets the online requirements. The principle is to magnetize the steel pipe with a DC coil to magnetic saturation, fix the direction of the magnetic field, and then hedge with a DC magnetic field with the same magnetic field size and opposite direction, and then Use AC demagnetization coils to supplement demagnetization. The problem with this method is that due to the different steel ...

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Problems solved by technology

[0002] The main problem of demagnetization in the steel pipe industry is that the DC residual magnetism is difficult to meet the standard. According to the requirements of API 5L, the residual magnetism of the steel pipe after demagnetization is less than 30Gs.

[0003] At present, the general method in China is demagnetization by DC hedging and AC supplementation, and the speed meets the online requirements. The principle is to magnetize the steel pipe with a DC coil to magnetic saturation, fix the direction of the magnetic field, and then hedge with a DC magnetic field with the same magnetic field size and opposite direction, and then Use AC demagnetization coils to supplement demagnetization. The problem with this method is that due to the different steel grades, thicknesses, and components of steel pipes, the residual magnetism produced after magnetic saturation is inconsistent. Sometimes it can be cleared after hedging with a fixed direction, and sometimes it cannot be cleared. , sometimes the excessive amount leads to the opposite direction of DC remanence, and it is difficult to remove the DC remanence when supplemented with AC. The coil must be in the center of the coil, but the effect is still unsatisfactory

In fact, steel pipes after eddy current magnetic saturation often have about 80Gs of residual magnetism after demagnetization. Baosteel also has advanced equipment from Germany. They use low-frequency methods for demagnetization, but they need 20 times of low-frequency polarity demagnetization. That is to say, steel pipes The transmission speed is about 0.1 m / s, which is an unbearable slow speed online

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