Magnetic blocks that have not been magnetized or have been magnetized need to be magnetized by a magnetizing machine. So what are the magnetizing directions of a magnet? How is a magnet magnetized? What should be paid attention to during magnetization? This article will be detailed.
Direction of magnetization of a magnet
There are two kinds of magnetization: radial magnetization and axial magnetization. There are also some others, such as multipole magnetization, radial magnetization and oblique magnetization. Most magnetic materials can be magnetized to saturation in the same direction, which is called the direction of magnetization (orientation). Non-oriented magnets (also called isotropic magnets) are much less magnetic than oriented magnets (also known as anisotropic magnets).
Large block magnet magnet steel
How does a magnet charge?
At present, there are two magnetization methods: DC magnetization and pulse current magnetization:
(1) The equipment used for DC magnetizing is an electromagnet magnetizing machine, whose structure is shown in FIG. 1. When working, the coil is fed with direct current, and the gap size between the two iron cores can be adjusted by adjusting the nut. Before magnetizing, clean the surface of the magnet with clean water, put the magnet into the gap between the core of the magnetizing machine and clamp it. Then pass the direct current into the excitation coil to reach the maximum value, and cut off the current in a stable 3 ~ 4s mode. The magnet has been magnetized. Due to the low residual magnetic sense after the magnetization of a single magnet, and the high residual magnetic sense of magnetic stacking combined magnetization, the magnetization field of the magnetization machine should be 5 ~ 7 times of the magnetization force of the magnet.
Magnetizing direction of magnet | how does magnet magnetize
Figure: DC magnetizing machine
1 -- Movable iron core; 2 -- Excitation coil; 3 - yoke iron; 4, nut
(2) Pulse current magnetization. The equipment used is pulse current magnetizing device, which is mainly composed of pulse device and magnetizing coil. It has a very high magnetization field, which can directly magnetize the magnetic stack. When working, a strong pulse current passes through the magnetizing coil, generating a powerful magnetic field for an instant, which magnetizes the magnetic stack in the magnetizing coil. Dc electromagnet has low magnetizing capacity, but its structure is simple and equipment cost is low. It is suitable for small and medium-sized magnetic separation plants. The pulsed current magnetizing device has large magnetizing capacity, complex equipment and high cost. It is suitable for large magnetic separation plants and manufacturers of magnetic separation equipment.
What problems should be paid attention to in magnetization?
When the length of the magnet is close to that of the magnetizing coil, the vertical center position of the magnet should coincide with the vertical center position of the magnetizing coil, so as to ensure that the magnetic field strength of both ends of the magnet is equal, and the symmetry of magnetizing is reduced, so that the magnetic field strength of both ends of the magnet is equal due to the magnetizing method.
Theoretical proof: the magnetic field strength at both ends of the magnetizing coil is 1/2 of the magnetic field strength at the center point of the coil. When the magnets approach the length of the magnetizing coil, it is possible that the products above H and SH may not be saturated with magnetizing. When the magnetic field strength is not high enough, even the products of M and N series cannot be saturated with magnetizing. In general, the length of the magnetizing magnet should be less than 2/3 of the magnetizing coil.
Deformed high difficulty strong magnet
Determination of easy magnetization direction (orientation direction) of magnets: For square square and vertical axial orientation cylinders, orientation (orientation easy to be magnetized) can be identified by using magnetized products or borrowed instruments. The specific methods are as follows:
1. Identify with magnetized products: For squares and cubes, due to the anisotropy of materials, the magnetic chip is arranged in the orientation direction, so it is easy to magnetize in the orientation direction. After magnetization, the suction of the heteropolar phase is large, while the suction of the non-oriented direction is small. The magnet used for inspection should be a little larger, and the difference of the suction force in the hours passing the magnet is not easy to be judged. For a cylinder with vertical axial orientation, generally, it can only be detected with the magnetized magnet: magnet is used to absorb the surface of the cylinder, and the direction perpendicular to the ground is the direction of orientation magnetization.
2. A magnet can be drawn on the square material. The direction of the magnet is perpendicular to the flux coil, the side with relatively large flux value is the orientation surface, and the direction perpendicular to the surface is the orientation direction.