JPH02308512A - R-fe-b permanent magnet having biased anisotropy and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain desired biased anisotropic direction by applying magnetic- field-free warm plastic working to a specified alloy based permanent magnet of a specified average crystal grain diameter. CONSTITUTION:Between opposed magnetic pole faces whose average crystal grain diameter is 0.01-1.0mum, if magnetic-field-free warm plastic working is applied to one alloy permanent magnet, which has a vector in the magnetic direction different from the other and high residual magnetic flux density being shown by formula R-Fe-B, the orientation of particles changes. Hereby, the desired biased anisotropic direction can be obtained, and various kinds of magnetic circuits can be made efficient easily. Among the formula, R is one kind or two or more kinds of rare earth elements which include yttrium.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention uses magnetically anisotropic R-Fe-B, which has superior corrosion resistance compared to sintered magnets, has less processing deterioration and hydrogen deterioration, and has a large coercive force.
Regarding permanent magnets, especially improving the direction of magnetic anisotropy,
The present invention relates to a manufacturing method thereof.

[Conventional technology]

An R-Fe-B sintered magnet that essentially does not require Sm, which is a scarce resource, and has a large maximum energy product is disclosed in Japanese Patent Publication No. 61-
It is described in Publication No. 34242 and the like.

However, these conventional magnetically anisotropic sintered permanent magnets have various drawbacks, such as significant processing deterioration and hydrogen deterioration, as well as problems in corrosion resistance.

On the other hand, alloy powder or ribbon produced by ultra-rapidly solidifying a melt of R-Fe-B alloy at a cooling rate of 104°C/S or more has a small average crystal grain size of 0.01 to 1.0 μm. It has a high intrinsic coercive force due to a mechanism different from that of a magnet. This alloy powder or ribbon is warmly compacted and made magnetically anisotropic by warm plastic working to create a plate-like or disk-like magnet with a metal structure (hereinafter referred to as an anisotropic ultrafine structure) with an average crystal grain size of 0.01 to 1 μm. ) with a coercive force of 15 kGe
, residual magnetic flux density 11kG, maximum energy product 3QMGO
It has high magnetic properties of e or higher, and is superior in corrosion resistance compared to the sintered magnets mentioned above, with significantly less processing deterioration and hydrogen deterioration.

(Problems to be Solved by the Invention) In the conventional R-Fe-B permanent magnet having an anisotropic ultrafine structure described above, a special process of imparting magnetic anisotropy by warm plastic working without using a foundation magnetic field is required. In order to take
For example, in the magnetic anisotropy direction of a disc-shaped magnet, the C-axis is the normal direction perpendicular to the disc surface throughout the magnet, and in the case of a cylindrical magnet, the C-axis is uniformly radially aligned by extrusion processing. It was limited to things that could be oriented.

However, when designing a magnetic circuit using a permanent magnet as an applied product using a permanent magnet, for example, a disc-shaped magnet has anisotropy in which the direction of easy magnetization is biased toward its central axis. Using the attached magnet results in a more efficient circuit design. In addition, in flat magnets used in voice coil actuators (hereinafter referred to as VCM), etc., the direction of easy magnetization on the side joined to the soft magnetic yoke is biased toward the center with respect to the direction of voice coil movement. It is more efficient to use oriented magnets. In addition, for arc segment-shaped magnets used as stators of rotating machines, it is better to use magnets whose magnetization direction is easily offset from the center of the arc, rather than using permanent magnets whose entire magnetization is uniformly magnetized in the normal direction of the arc. This results in a more effective design with less cogging torque.

[Means for solving problems]

The present invention has an average crystal grain size of 0.01 to 1 μm and has a magnetic anisotropy perpendicularity greater than that of one of the two opposing magnetic pole surfaces, The present invention relates to an R-Fe-8-based permanent magnet and a method for producing the same, characterized in that the properties are imparted by particle orientation through warm plastic working.

The present invention makes it possible to design an efficient magnetic circuit by imparting biased anisotropy to an anisotropic ultrafine structure type R-Fe-B magnet that cannot use an orienting magnetic field.

In the present invention, the average grain size refers to R2Fel, which is the main phase.
This is the average diameter of 30 or more crystal grains when the crystal grains are approximated to be spherical when viewed from the C-axis direction of the 4B type intermetallic compound. When the average crystal grain size is less than 0.01 μm, the coercive force is low, and even when it exceeds 1 μm, the coercive force similarly decreases, making it impossible to obtain satisfactory permanent magnetic properties.

In the present invention, as a means for imparting bias anisotropy, for example, in the case of an arc segment-shaped bias anisotropic magnet, between upper and lower punches having parallel end surfaces, 550 to s o o
The rough material, which has been given anisotropy in the direction perpendicular to the flat plate surface by compression upsetting in 'c, is plastically deformed again at 500 to 800°C in a die with arc-shaped upper and lower punches. It is possible to obtain a permanent magnet whose orientation direction is continuously offset with respect to a circular arc. (Fig. 1) For example, in the case of a biased plate magnet, a permanent magnet that has been plastically worked at 600 to 800°C is placed between the upper and lower punches having curvature.
By plastically deforming the magnet again in a die having parallel upper and lower punches at 00 to 800°C, a magnet having anisotropy in which the anisotropy direction is inclined with respect to the plate surface can be obtained. (
Fig. 2) Furthermore, in order to obtain a plate-shaped or disc-shaped magnet in which the direction of easy magnetization is locally shifted, a side pressure of 300 kg/c1i1 or more is applied from the side of the die during compression upsetting to the edge of the magnet. It is possible to obtain a permanent magnet in which the anisotropy direction is locally biased.

〔Example〕

[Example 1] An alloy having a composition of Nd13.5FebafCO+oGa+B6 was ultra-quenched by melt spinning to a thickness of approximately 30 mm.
A thin strip having a width of 5 mm and a length of 10 to 30 μm was obtained using am. As a result of X-ray diffraction, this ribbon was found to be a mixture of amorphous and crystalline materials.

Next, this ribbon was coarsely ground to 500 μm or less and cold-milled for 3
After compaction by applying a pressure of 1 ton/d in a mold while heating the obtained green compact to a powder compact (15 x 10 x 8 mm) at a pressure of 1 ton/C, the height was adjusted between parallel punches. 174
Perform compression upsetting until the compression ratio reaches 75%.
A flat magnet of 30×20×2 InI11 was obtained.

This flat magnet body was heated to 600°C again, and plastically deformed in a die with arc-shaped upper and lower punches.
A disc-shaped arc-shaped magnet body was obtained.

This arc-shaped magnet body was saturated and magnetized in a magnetizer having a magnetic pole face having the same curvature as the curvature of the magnet body to impart bias anisotropy. FIG. 3 shows a field waveform of a two-pole brushless smoke in which a permanent magnet magnetized in this manner is incorporated as a field magnet. In the conventional technology shown in the comparative example, the field waveform becomes a trapezoidal waveform, and a large cogging torque is applied. It can be seen that by using the permanent magnet having bias anisotropy according to the present invention, a field waveform close to a positive arc wave can be obtained, and the cogging torque of the motor can be reduced.

[Example 2] 20X30 obtained by consolidating an ultra-steep ribbon in the same manner as in Example 1
A compacted body of x20tmm was compressed and upturned at 750°C in a die space with arc-shaped upper and lower punches to form a compact with a thickness of 10m.
An arc-shaped magnet body of m was obtained. This magnet body is 750 again
It was heated to .degree. C. and then compressed and upset in a die space having parallel upper and lower punches to obtain an anisotropic magnet with a thickness of 5 plates and 1. This flat magnet was magnetized by applying a magnetic field parallel to its thickness direction.

FIG. 4 shows the results of measuring the magnetic flux density on the surface of this magnet.

As is clear from FIG. 4, according to the present invention, an extremely uniform magnetic field can be obtained over the entire effective length of the magnet.

〔Effect of the invention〕

According to the present invention, it is possible to easily improve the efficiency of various magnetic circuits.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a method of anisotropy of an arc-shaped biased anisotropic magnet according to the present invention, FIG. 2 is a schematic diagram showing a method of anisotropy of a flat magnet, and FIG. The figure is a comparison diagram of the field waveform of a motor incorporating a biased anisotropic magnet shown in Figure 1 as a stator and the field waveform of a motor using a Yohira anisotropic magnet as a stator. FIG. 3 is a surface magnetic flux waveform diagram of a flat magnetic flux having anisotropy. Figure 1 Figure 2

Claims (3)

[Claims] (1) R- with an average crystal grain size of 0.01 to 1.0 μm and one of the opposing magnetic pole surfaces has a magnetic direction vector different from the other magnetic pole surface and a high residual magnetic flux density.
Fe-B permanent magnet (here R is 1 containing yttrium)
or two or more kinds of rare earth elements, B is boron, and T is a transition metal), and the magnetic anisotropy is due to particle orientation by magnetic field-free warm plastic processing. An R-Fe-B permanent magnet. (2) The above alloy composition consists essentially of Nd or Pr, a rare earth element of 11 to 18 at%, and boron of 4 to 11a.
An R-Fe-B permanent magnet alloy having a biased anisotropic direction according to claim 1, which is composed of a transition metal mainly consisting of Fe and inevitable impurities. (3) Melt of R-Fe-B alloy at 10^4^℃/S
After producing an amorphous or partially or fully crystallized alloy by solidifying it by ultra-quenching as described above, the compacted powdered body is warmly deformed plastically at 550 to 800°C by applying pressure with upper and lower punches. This results in an average particle size of 0.01 to 1.0.
After obtaining a plate-shaped or arc-shaped magnet member having magnetic anisotropy almost perpendicular to the upper and lower punch surfaces in μm,
R-, which is characterized by imparting bias anisotropy by plastic working into an arc shape or a plate shape at a temperature of 00°C.
Method for manufacturing Fe-B permanent magnet.