JPH05239505A - Magnetic-field press die of ferrite magnet for micromotor - Google Patents

Abstract

PURPOSE:To provide a magnetic-field press die of a ferrite magnet for a micromotor by which the magnetic flux is directed almost at right angles to the inner periphery of a ferrite compacting part 6 and the distribution of the magnetic flux is fixed at the time of compacting an anisotropic ferrite magnet. CONSTITUTION:The magnetic-field press die is set in a die 2 of desired diameter and consists of a magnetic lower die 3 with Stellite welded to its surface and a magnetic upper die 5. In this press die, the width of the upper die 5 is made larger than that of the lower die 3 to the desired extent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a magnetic field press die in powder metallurgy.

[0002]

2. Description of the Related Art A magnetic field pressing die that has been conventionally used is provided in a die made of a non-magnetic material having the same diameter. Since the upper molds have the same width, in the anisotropic ferrite magnet to be molded (hereinafter simply referred to as a work), the easy axis of magnetization of the ferrite is oriented in the magnetic flux direction of the applied magnetic field. The magnetic flux densities at the left and right side ends of the magnetic disk become uneven, and when used in a micromotor, the magnetomotive force distribution becomes uneven, and power consumption is increased.

[0003]

In view of the above, the present invention has been made in view of the above problems.
(EN) A magnetic field press die in which the direction of magnetic flux in a work is a predetermined direction and the magnetic flux density distribution is constant.

[0004]

According to a first aspect of the present invention, there is provided a magnetic field pressing die for a ferrite magnet for a micromotor in a die having a required diameter and a lower side of a magnetic body having a surface thereof welded with stellite. In a magnetic field press die including a die and an upper die of a magnetic material, the width of the upper die is wider than the width of the lower die by a required amount.

A second aspect of the present invention is a magnetic field press die comprising a lower die of a magnetic material and an upper die of the magnetic material in a die having a required diameter, the surface of which has stellite deposited on the surface thereof. Is provided with a step portion composed of a lower width portion having the same width as the lower die and an upper width portion which is wider than the width portion, and an inner wall of a width direction for guiding the lower width portion of the upper die of the die. Is a magnetic body having a required width, and the upper end of the magnetic body faces the lower surface of the step portion.

[0006]

The width of the upper die is made wider than the width of the lower die, or the inner wall of the die is made of a magnetic material having a required width so that the upper end faces the lower surface of the step of the upper die. The distribution of the magnetic field during the magnetic field pressing is evenly distributed in the work, and the magnetic flux density is substantially equalized.

[0007]

EXAMPLES The present invention will be described with reference to Examples. A magnetic field press die a of a ferrite magnet for a micromotor (hereinafter, simply referred to as a magnetic field press die a) has an arc-shaped cross section having a required wall thickness. Since the work 1 having a required length is compression-molded, it is symmetrical with respect to the center of the arc cross section of the work 1, and for the sake of simplicity, it will be described in detail based on the main part of the left half. As shown in FIG. 1, a surface layer body 4 made of non-magnetic stellite whose surface shape is the inner surface shape of the work 1 is formed on the surface of the lower die 3 made of a magnetic material to be fitted in the die 2. The upper die 5 is brazed, and the inner surface of the upper die 5 is formed into an arcuate surface of the outer shape of the work piece 1 with the ferrite compression molding portion 6 interposed therebetween. Make it the same size as the width,
A horizontal surface 7 is formed on the right and left sides of the lower end, and the width between the outer ends of the horizontal surface 7 becomes the width dimension of the upper mold 5. In this embodiment, the width of the upper mold 5 is the width of the lower mold 3. It is 1.3 times the value.

Therefore, ferrite powder is put into the ferrite compression molding portion 6 of the magnetic field press die a shown in FIG.
When compression molding is performed while applying a magnetic field of about (T), the distribution of the magnetic field at this time becomes a magnetic flux diagram as shown in FIG. 2 when simulated by the finite element method. According to this magnetic flux diagram, the magnetic field distribution becomes a uniform magnetic field distribution in the ferrite compression molding portion 6, and the direction of the magnetic flux is in the molding portion 6
It is almost perpendicular to the inner circumference of. This means that the magnetic flux density does not increase at the left and right ends as seen in the magnetic flux diagram of the conventional magnetic field press die b shown in FIG. This indicates that the distribution has been improved.

Next, the second invention of the present invention will be described with reference to an embodiment. As shown in FIG. 3, the upper die 5 has a lower width portion 8 having the same width as that of the lower die 3 and the width portion 8 is required. A step portion 10 including a wide upper width portion 9 is provided, and the upper die 5 of the die 2 is provided.
In the inner wall of the width direction that guides the lower width portion 8 of
An upper end of the stepped portion 10 is opposed to the stepped portion 10, and a magnetic material 11 having a required width whose lower edge is an arc surface obtained by extending an arc surface of the outer periphery of the work 1 is embedded. In this case, the width dimension of the upper width portion 9 of the upper mold 5 is 1.3 times that of the lower mold 3.

The distribution of the magnetic field at the time of pressing by the magnetic field pressing die a1 constructed as described above becomes a magnetic flux diagram as shown in FIG. 4 when simulated by the finite element method, and a uniform magnetic field in the ferrite compression molding portion 6 is obtained. Distribution,
In addition, the direction of the magnetic flux is substantially perpendicular to the inner circumference of the molding portion 6, which shows that the magnetic field distribution is improved as described above. In addition, since it takes time to form the lower edge of the magnetic body 11 embedded in the inner wall of the die 2 and the fitting groove of the inner wall into which the lower edge is fitted, practically, as shown by phantom lines, mutual processing is performed linearly. The magnetic body 11 is joined to the left and right inner walls of the die 2, and in this case as well, it was confirmed that the magnetic field distribution has a magnetic flux diagram substantially similar to that shown in FIG. In addition, the width of the upper mold 5 is the lower mold 3
It was also confirmed that the magnetic field distribution can be improved satisfactorily if the width is 1.1 times or more.

[0011]

As described above, the magnetic field press die a of the present invention is used.
According to this, there is an effect that a magnetic field distribution in which the direction of the magnetic flux during pressing is substantially constant and the magnetic flux density distribution is constant, and an anisotropic ferrite magnet having a uniform and high orientation rate can be manufactured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of the main part of the left half of a magnetic field press die a according to the present invention.

FIG. 2 is a magnetic flux diagram of a simulation result by a finite element method when the magnetic field pressing die a shown in FIG. 1 is pressed.

FIG. 3 is a vertical cross-sectional view of the left half of the magnetic field press die a1 according to the present invention.

4 is a magnetic flux diagram of a simulation result by a finite element method when the magnetic field press die a1 shown in FIG. 3 is pressed.

FIG. 5 is a magnetic flux diagram of a simulation result by a finite element method at the time of pressing in a conventional magnetic field pressing die b.

[Explanation of symbols]

 1 Work 2 Die 3 Lower mold 4 Surface layer 5 Upper mold 6 Ferrite compression molding part 7 Horizontal plane 8 Lower width part 9 Upper width part 10 Stepped part 11 Magnetic material a Magnetic field press mold a1 Magnetic field press mold b Magnetic field press Mold

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsumi Tajima 12-10 Yamagata-cho, Tegata, Akita City, Akita Prefecture Yamazaki-juku (72) Inventor Takayuki Sakurai 176 (72) invention, Mitsuike-cho, Unuma, Kakamigahara-shi, Gifu Prefecture Koichi Sugawara, 41, Koko Denshi Co., Ltd., 26 Oiwake West, Tenno, Tenno-cho, Minami-Akita-gun, Akita Prefecture (72) Inventor Rank: 41, 26, Nishi, Tenno-cho, Tenno-cho, Minami-Akita-gun, Akita Prefecture

Claims (2)

[Claims] 1. A magnetic field press die comprising a lower die for a magnetic body and an upper die for a magnetic body in a die having a required diameter, the surface of which is welded with stellite, and the width of the lower die. On the other hand, a magnetic field press die for ferrite magnets for micromotors in which the width of the upper die is made as wide as necessary. 2. A magnetic field press die comprising a lower die for a magnetic body and a die for a magnetic body, the surface of which is welded with stellite in a die having a required diameter, and a lower die for the upper die. A step having a lower width portion having the same width as the die and an upper width portion wider than the width portion is provided, and an inner wall having a width in the width direction for guiding the lower width portion of the upper die of the die has a required width. A magnetic field press die of a ferrite magnet for a micromotor, which is made of a magnetic material, and the upper end of the magnetic material faces the lower surface of the step portion.