RU2779504C1 - Inductor for magnetising permanent magnets - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: inductor for magnetising double-pole permanent magnets comprises electric current conductors by reducing the deviation of the orientation of magnetisation of the magnets from the required direction. The conductors, interconnected in series at one end, forming an air gap using a bus made of a conductive material, and connected to a current source at the other end via inductor rods, constitute solid current conductors. The shape of the radial cross section of the conductors constitutes half-moons formed by crossing two circles of the same radius and subtracting the common area, said area being the working area of the inductor.

EFFECT: higher quality of magnetisation of permanent magnets.

1 cl, 4 dwg

Description

The invention relates to electrical engineering, in particular to devices for magnetizing bipolar permanent magnets.

For high material efficiency of bipolar permanent magnets, they must be uniformly magnetized throughout the entire volume. Prefabricated magnetic systems consist of a set of uniformly magnetized bipolar magnets, the direction of magnetization of which is oriented at the required angle to some fixed axis, edge or face [Multi-pole magnet: a.s. 662979 USSR, No. 2302336/24-07 / Rabinovich Ya.D.; dec. 12/23/75; publ. 05/15/79, Bull. 18. 2 p.]. Therefore, in order to magnetize the elements of prefabricated magnetic systems, inductors are needed that create a uniform field.

Bipolar permanent magnets are often magnetized in conductive solenoids with a working area in the form of a cylinder with a generatrix in the form of a circle, rectangle, etc. [2, p. 29]. The field of such inductors is not uniform in the entire volume of the working area. Therefore, in order to magnetize magnets, the volume of the working area is often made substantially larger than the volume of the magnet being magnetized. This leads to the need to increase the power of the inductor power source to create a field of the required magnitude.

Known inductor for thermomagnetic processing and magnetization of multi-pole rotor magnets, consisting of conductive rods installed parallel to the axis of the inductor at the same distance from it [Inductor for magnetization and thermomagnetic processing of multi-pole magnets: a.s. 1791858 A1 USSR, No. 4671380/07 / Stadnik I.P., Gorskaya I.Yu.; dec. 02/28/89; publ. 30.01.93, Bull. 4. 4 p.], chosen as a prototype.

This inductor does not provide uniform magnetization of bipolar magnets, because its field in the working area differs significantly from the homogeneous one.

The purpose of the invention is to improve the quality of magnetization of permanent magnets.

The technical problem solved by the invention is to reduce the deviation of the orientation of the magnetization of the magnets from the desired direction.

The solution of the problem is achieved by the fact that the inductor has two conductive rods, the shape of the radial section of which is a crescent, obtained after crossing two circles of the same radius and subtracting the total area. The working area of the inductor has a cross-sectional shape of the common part of two intersecting circles.

In FIG. 1 shows the radial section of the inductor, where the following designations are used: 1 - conductive rods, 2 - the working area of the inductor, filled with non-magnetic and non-conductive material for fixing magnetizable samples, 3 - magnetizable magnet.

In the inductor rods at the time of its operation, currents of the same magnitude and opposite directions must flow. The simplest way to meet this requirement is to connect the rods in series through the nearest ends (on one side of the inductor). A power source is connected to the free ends of the rods. The current in the inductor can be either constant or pulsed.

In FIG. 2 shows a general view of the inductor.

The inductor is made as follows. In a cylindrical rod of an electrically conductive material, for example, copper, longitudinal recesses are cut in the form of a part of a cylinder, the radius of which is equal to the radius of the rod. Then the rod is cut into two identical parts perpendicular to the longitudinal axis. On a sharp longitudinal edge of the rods, a chamfer is removed. Holes are drilled at the ends of the rods and threads are cut. Using a tire made of electrically conductive material, the rods are connected at one end so that there is an air gap between them. The other ends of the rods are connected to a current source. The axial length of the inductor must be greater than the axial size of the magnet being magnetized.

The inductor works as follows. A magnetizable sample is inserted into the hole. A current pulse is passed through the inductor rods, the field of which magnetizes the sample. The required value and duration of the current pulse depend on the material of the magnetized sample (its coercive force) and the volume of the working area. Typically, a pulse duration of the order of 10 ms is required [Nesterin V.A. Equipment for impulse magnetization and control of permanent magnets. M.: Energoatomizdat, 1986. 88 p.].

The magnetized magnet is removed from the inductor.

To fix the magnetizable sample in the working area, it is advisable to use an insert made of a non-magnetic and non-conductive material, for example, textolite (see Fig. 1), with a channel into which the magnetizable sample is placed (there can be more than one channel and sample).

Due to the fact that the inductor rods are solid current conductors of a relatively large size, in the pulsed mode of operation, a pronounced uneven distribution of current over the cross section of the rods (skin effect) can be observed. This will lead to the fact that the distribution of the magnetizing field in the working area of the inductor will deviate from uniform. To eliminate this effect and ensure high-quality magnetization of the magnets, the rods are replaced with a bundle made of parallel-connected conductors of the same diameter.

In the Cartesian coordinate system, the abscissa axis of which coincides with the symmetry axis of the inductor section (Fig. 1), the inductor field has only one component:

where μ ₀ is the magnetic constant,

δ is the current density in the inductor bars,

Y - distance from the axis (section center) of the bar to the center of the workspace section.

Manufacturing errors and the presence of an air gap between the tires leads to a slight distortion of the inductor field in the working area. To calculate the inductor field, you can use the Biot-Savart-Laplace formula:

where μ ₀ is the magnetic constant,

S is the total area of the radial section of the current conductors of the inductor,

- вектор плотности тока в стержнях индуктора (имеет только одну z - компоненту),

- current density vector in the inductor bars (has only one z - component),

- радиус-вектор, проведенный из точки интегрирования Р в точку наблюдения поля Q.

is the radius vector drawn from the integration point P to the observation point of the field Q.

Calculations show that the field of the inductor, calculated by formula (2), differs from the ideal value in the section of the working area, calculated by formula (1), by no more than 0.05%. That is, it is practically homogeneous in the workspace. The field of the prototype in the section of the working area deviates from the uniform by 5.9%.

In FIG. 3a shows a picture of the field of the prototype, and figb - the proposed inductor. As seen in FIG. 3a, when approaching the conductors of the prototype, its field loses its uniformity. Therefore, for high-quality magnetization of bipolar magnets in the prototype inductor, you can use only a relatively small working area, remote from the conductors. In addition, magnetizable samples must be centered in the working area of the inductor to ensure symmetrical (uniform) magnetization.

The field of the proposed inductor (see Fig. 3b) remains uniform throughout the entire working area. With an equal total current in the conductors of the prototype and the proposed inductor, the field in the working area of the latter will have a large value, because conductive busbars are close to the work area. For high-quality magnetization of the samples in the proposed inductor, the samples can not be centered in the working area, because the field is uniform throughout the region. This property of the proposed inductor allows you to simultaneously magnetize several samples (see Fig. 1).

Thus, the proposed inductor allows more efficient magnetization of bipolar permanent magnets than the prototype.

Claims (1)

An inductor for magnetizing bipolar permanent magnets, containing conductors of electric current, characterized in that, in order to improve the quality of the magnetization of magnets, the conductors are connected in series from one end with the formation of an air gap using a bus made of electrically conductive material, and from the other end attached to current source, the inductor rods are solid current conductors, the shape of the radial section of which is a crescent, obtained after crossing two circles of the same radius and subtracting the common area, which is the working area of the inductor.

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