JPH0459761B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a permanent magnet that is controlled to have a desired magnetic flux distribution between magnetic poles by applying a special magnetization method to an integrally formed material. It relates to magnets and their manufacturing methods.

[Prior art] Conventionally, permanent magnets have strong remanence at both ends of the N and S poles, and as they get closer to the neutral point in the center of the magnet, the remanence becomes weaker. I couldn't have expected it. As a technique for compensating for the drawbacks of conventional magnets, that is, for obtaining residual magnetism in any part other than the ends of the magnet, the invention disclosed in Japanese Patent Application Laid-open No. 107809/1983 is known. There is. In this invention, a material to be magnetized is magnetized by closely adhering a metal having a higher magnetic permeability than the material to be magnetized, thereby creating a multipolar magnet having magnetic poles in areas other than the ends of the material to be magnetized. .

[Problems to be Solved by the Invention] The above invention can strengthen the residual magnetism in any part other than the end, and is effective in applications where it is desirable to concentrate magnetic absorption power in any part. . However, in the above invention, it is difficult to move the neutral point of the magnetic pole to an arbitrary position and to accurately set the residual magnetic flux distribution between the magnetic pole and the neutral point to a desired position and value.

The present invention has been made in view of the above-mentioned prior art, and aims to provide a permanent magnet in which the movement of the neutral point and the distribution of residual magnetic flux can be set to desired positions and values, and a method for manufacturing the same.

[Means for Solving the Problems] The permanent magnet of the first invention performs a magnetic field analysis of a desired magnetic flux distribution when magnetizing a material to be magnetized, and a predetermined magnet is manufactured based on the calculated data. A magnetic material having a higher permeability than the magnetized material and having a shape of Manufactured under controlled conditions.

A second invention is an invention of a method for manufacturing the permanent magnet according to the first invention, wherein when manufacturing the permanent magnet by magnetization, at least a part of the magnetized material is subjected to a desired magnetic field analysis. The position, size, number, etc. of the residual magnetic flux in the magnetized material can be changed by locally adhering a high permeability magnetic material that is set in a predetermined shape to correspond to the characteristics of the magnetic flux distribution between the magnetic poles. It is something that makes you At this time, the instantaneous magnetic flux that brings the high permeability magnetic material and the magnetized material into close contact with each other and magnetizes the material is greatly influenced by the shape of the magnetic material. Figure 1 shows some aspects of the magnetic flux distribution when a magnet has a desired residual magnetic flux distribution between the magnetic pole and the neutral point, for example, when the center of a bar-shaped magnetized material is the neutral point and one end is the magnetic pole. . In the figure, the horizontal axis indicates the distance in the longitudinal direction from the center (neutral point) of the magnetized material, and the vertical axis indicates the residual magnetic flux density G. FIGS. 2a and 2b show the shapes of magnetic materials used to obtain magnets with magnetic flux distributions as shown in FIGS. 1A and 2B.
Note that c in Figure 1 shows the characteristics when magnetized without using a magnetic material, and its shape is shown in c in Figure 2.
This is shown below.

The shape of the magnetic material shown in FIG. 2 is obtained as follows. That is, in the magnetization method of the present invention, in order to correspond to the desired characteristics of magnetic flux distribution between magnetic poles, a magnetic material having a higher magnetic permeability than the material to be magnetized (hereinafter referred to as high magnetic permeability material) is first Must be set to shape. Therefore, the desired magnetic flux distribution can be determined using the finite element method, Galerkin method, Newton method, etc.
The shape of the highly permeable material is determined by performing a magnetic field analysis using the Raphson method or the like, and then performing an inverse magnetic field analysis from the records obtained by this method.

The analytical formula using the finite element method is as follows.

In finite element analysis, 〓=μ(B ¹ )+〓+〓(〓) is discretized using the Galerkin method and Newtonian
Applying the Rafson method, u _i = _J 〓 ^K=1 S _ik A _pk magnetic flux density is B _z ^(e) = 1/3r ₀ ^(e) ₃ 〓 ^K=1 A _pk + ₃ 〓 ^K=1 b _k ^{( e)} A _pk /2Δ ^(e) B Determined from the demagnetization curve of the magnet as a function of _z .

First, the magnetic flux distribution during magnetization is determined using the above discretized formula. The shape of the highly permeable material can be determined by back-analyzing the obtained records.

The materials to be magnetized according to the present invention include alnico, ferrite, KS copper, carbon steel, rare earth magnets, plastic (rubber) magnets, and other known permanent magnet materials. It also includes those in which the same magnetized material is bonded or glued in front of the magnet.

[Function] By applying the above analysis method to design the shape of a highly permeable material, a permanent magnet having an arbitrary magnetic flux distribution curve between magnetic poles can be obtained. Furthermore, since the shape of the highly permeable material is determined by an analytical method, desired characteristics can be obtained more easily and efficiently than in the past. Note that the above method is applicable not only to manufacturing a two-pole bar magnet having poles at both ends, but also to manufacturing a permanent magnet having an arbitrary number of poles in any form. Therefore, the scope of the present invention is not limited to the embodiments shown below.

[Example] An example of the present invention will be described with reference to FIGS. 2 to 5. FIG. 2 is a diagram showing the magnetization method. In the figure, 1 is a material to be magnetized, and in this example, a rod-shaped alnico 5 with a diameter of 12 mm and a length of 100 mm was used. 2 is a highly permeable material, and a ring made of pure iron was used. As mentioned above, Fig. 2 a and b show the shape of the highly permeable material to obtain the characteristics shown in Fig. 1 a and b, and c shows the shape of only the magnetized material 1. It is. In addition, Figure 3 is similar to Figures 2 a to c.
is a diagram seen from the apsis OB.

For magnetization, an excitation coil was installed around the inside of the iron yoke using the usual method, and a highly permeable material was combined with the material to be magnetized as shown in Figure 2 a and b, and placed inside the yoke. . The direction of the magnetic field was set in the direction of the arrow in Figure 2, and a direct current of 3.2 kA was instantaneously passed through the excitation coil. The magnetic flux distribution of the bar magnet magnetized in this manner is shown in FIG. 1 described above.

FIG. 4 is a diagram showing another embodiment of the present invention.
FIG. 4 is a diagram showing a magnetized material 1 equipped with a highly permeable material 2 having a gear-shaped groove in the long axis direction, and FIGS. FIG. 3 is a diagram showing magnetic flux distribution density in a cross section using lines of magnetic force. If you attach a highly permeable material with this shape,
A permanent magnet can be obtained that has a specific magnetic flux distribution both in the longitudinal direction and in the radial direction.

[Effects of the Invention] As explained above, according to the present invention, by closely adhering and magnetizing a highly permeable material having a predetermined shape obtained by magnetic field analysis, the movement of the neutral point and the The position, value, etc. of the residual magnetic flux distribution between the magnetic poles of the magnetized material can be set arbitrarily. Also,
The magnetization method according to the present invention has a unique effect that it is possible to obtain a uniform single magnetic pole on the circumferential surface of a bar magnet or the like, that is, a magnetic pole having only an N pole or an S pole.

[Brief explanation of drawings]

FIG. 1 is a graph showing the magnetic flux distribution of the magnet after the magnetized material has been magnetized, and FIGS. 2 to 5 are diagrams showing examples of the present invention. 1... Material to be magnetized, 2... Highly permeable material.

Claims (1)

[Claims] 1. When magnetizing a material to be magnetized, a magnetic material having a magnetic permeability higher than that of the material to be magnetized and having a predetermined shape determined by magnetic field analysis is closely attached locally. , a permanent magnet characterized in that the magnetic flux distribution between the magnetic poles of a magnetized material is controlled so as to have preset characteristics. 2. When locally magnetizing a magnetic material with higher magnetic permeability than the material to be magnetized, the shape of the highly permeable material is determined by magnetic field analysis in order to correspond to the desired magnetic flux distribution characteristics between the magnetic poles. A method for producing a permanent magnet, the method comprising forming a permanent magnet into a predetermined shape.