JPH04307703A - Resin-bonded magnet and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a magnetic flux which is higher than that at isotropy by a method wherein-a magnetic substance whose ratio of a projection length on a long axis to a projection length on a short axis is at 2 or more is used and the direction of the projection length the long axis is arranged parallel to a magnetization direction. CONSTITUTION:An alloy which is composed of 31% of Nd, 68% of Fe and 1% of B in terms of their wt.% is used; it is quenched; a thin belt is manufactured by using a roll provided with a slender groove. The obtained thin belt is needle-shaped. The thin belt is kneaded with an epoxy resin at 3wt.%; this kneaded substance is compressed and molded in a radial magnetic field; a ring-shaped magnet whose outside diameter is at 21mm, whose inside diameter is at 18mm and whose height is at 3mm is formed. The needle-shaped thin belt inside the obtained ring-shaped magnet is made uniform in the radial direction. Regarding a magnetic characteristic by VSM, (BH)max values in the comparison example are nearly the same at 9.2 and 9.1 MGOe, and peak values of a surface flux density are at 4.2 and 3.2kG. Although the magnet is isotropic in terms of its magnetic characteristic, a high surface flux is obtained from the relationship of a permeance and a magnetic circuit when a multipolar magnetization operation is executed. A comparison specimen forms a ring-shaped magnet in a state that it is not magnetized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-bonded magnet and a method for manufacturing the same.

0002

[Prior Art] Conventionally, as a type of resin-bonded magnet, Nd-Fe-B is used as disclosed in Japanese Patent Application Laid-Open No. 59-211549.
There are magnets that use quenched ribbons.

0003

However, the Nd--Fe--B based quenched powder in the prior art has a problem in that it can only be used with isotropic properties due to the size of its crystal grains.

SUMMARY OF THE INVENTION The present invention aims to solve these problems, and its object is to provide a resin-bonded magnet that exhibits even higher characteristics and a method for manufacturing the same.

[0005]

[Means for Solving the Problems] The resin-bonded magnet of the present invention uses a magnetic material in which the ratio of the projected length to the long axis to the projected length to the short axis is 2 or more, and It is characterized by being aligned parallel to the magnetization direction.

[0006] The magnetic material is also characterized in that it is needle-shaped, rod-shaped, scale-shaped, or plate-shaped.

[0007] The method for manufacturing resin-bonded magnets involves aligning magnetic materials in which the ratio of the projected length on the long axis to the projected length on the short axis is 2 or more in a magnetic field by utilizing their shape anisotropy. Features.

[0008]

[Operation] According to the above structure of the present invention, a magnetic material whose ratio of the projected length to the long axis and the projected length to the short axis is 2 or more is used, and the projected length direction to the long axis is the magnetization direction. By arranging them in parallel, it is possible to obtain a higher magnetic flux than when they are isotropic due to the relationship of permeance and magnetic path, especially when multi-pole magnetization is applied.

[0009] Further, by making use of its shape anisotropy, it can be made uniform by molding in a magnetic field.

0010

EXAMPLES The present invention will be explained in detail below based on examples.

(Example 1) Nd 31%, Fe6 in weight%
A quenched ribbon was prepared from an alloy containing 8% B and 1% B using a so-called melt spinning method using a roll with narrow grooves. The obtained ribbon was acicular. This ribbon was kneaded with 3% by weight of epoxy resin and compression molded in a radial magnetic field to create a ring-shaped magnet with an outer diameter of 21 mm, an inner diameter of 18 mm, and a height of 3 mm. The needle-shaped thin ribbons within the obtained ring-shaped magnet were aligned in the radial direction.

Further, as a comparative example, a ring-shaped magnet was similarly prepared without a magnetic field. Naturally, the acicular ribbons were oriented in random directions.

These ring-shaped magnets were cut out to a width of 2 mm, and their magnetic properties were measured using a VSM. In addition, 24-pole multipole magnetization was performed and the surface magnetic flux density was measured.

Regarding the magnetic properties of the VSM, the (BH)max of the present invention and the comparative example are almost the same as 9.2 and 9.1 MGOe, respectively, but the peak values of the surface magnetic flux density are 4.2 and 3.1, respectively. It was 2kG. That is, although the magnetic properties of the present invention are isotropic, when multipolar magnetization is applied, a high surface magnetic flux is obtained due to the relationship between permeance and magnetic path.

(Example 2) Nd 27%, Fe6 in weight%
A scale-like quenched ribbon was produced from an alloy containing 8% Co, 4% Co, and 1% B using a normal roll. The present invention and a comparative example were prepared in the same manner as in Example 1, but the peak values of the surface magnetic flux density obtained by multipolar magnetization were 3.9 and 3.3 kG, respectively.

This shows that the present invention does not depend on the composition or shape of the magnetic material used.

(Example 3) A similar ring magnet was made by injection molding and extrusion using the needle-like quenched ribbon of Example 1.
A 0% higher surface magnetic flux density was obtained, indicating that the present invention does not depend on the molding method.

(Example 4) The ring-shaped magnet of Example 2 was fixed to a disk and a shaft, and rotated at 3600 rpm. Whereas the comparative example caused peeling-type failure after 120 hours,
There was no change in the present invention even after 1000 hours had elapsed.

This means that not only the magnetic flux density on the surface is improved, but also the mechanical strength is improved.

[0020]

Effects of the Invention As described above, according to the present invention, by using a magnetic material in which the ratio of the projected length to the long axis and the projected length to the short axis is 2 or more, the projected length direction to the long axis can be fixed. By aligning parallel to the magnetic direction, the surface magnetic flux density obtained by applying multi-pole magnetization increases and at the same time the mechanical strength also increases, making it possible to further improve the performance and miniaturize the motors and devices to which it is applied. This method has many practical effects, such as being able to be applied to high-speed rotating equipment.

Claims (4)

[Claims] [Claim 1] A magnetic material whose ratio of the projected length to the long axis and the projected length to the short axis is 2 or more is used, and the projected length direction to the long axis is aligned parallel to the magnetization direction. Resin bonded magnet. 2. The resin-bonded magnet according to claim 1, wherein the magnetic body is needle-shaped or rod-shaped. 3. The resin-bonded magnet according to claim 1, wherein the magnetic body is scale-shaped or plate-shaped. 4. A resin-bonded magnet characterized by aligning magnetic materials in which the ratio of the projected length on the long axis to the projected length on the short axis is 2 or more in a magnetic field by utilizing the shape anisotropy of the magnetic material. manufacturing method.