JPS6184806A - Molding device of anisotropic ferrite magnet - Google Patents

Abstract

PURPOSE:To enlarge difference of magnetic property between both face of a magnet and to improve steeply magnetic property of peripheral face thereof by a method wherein compression molding is performed by installing nonmagnet ic substance, which has convex curved face at forming space side on the surface of forming space side of a lower punch at contact face portion with usable powder loaded. CONSTITUTION:A forming space is formed by inserting to a square piller state lower punch 2, which consists of magnetic substance inside square piller state space section installed a die 1 made by nonmagnetic substance and has convex curved face, then usable power is loaded inside the said space. A square piller state upper punch 4, which has concave curved face, is abutted on the upper edge face of the die 1 and a nonmagnetic substance 3, whose upper face size is the same as the lower punch 2 and is flat at forming space side, also is concave lens shape with concave curved face at the lower punch side, is sticked to magnetic pole surface of the lower punch 2. In this forming device, after slurry state usable power is loaded to forming space in the die 1, an electromagnetic coil 5 is excited and then magnetic field is formed, thereafter compression molding is performed lowering the die 1 and the upper punch 4.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention relates to a molding device for a ferrite magnet.
The present invention relates to an anisotropic ferrite magnet molding device that can increase the difference in magnetic properties between both warm curved surfaces of an anisotropic ferrite magnet having an arcuate or semi-cylindrical cross section, and can significantly improve the magnetic properties on the outer peripheral surface side.

Background technology For example, an anisotropic ferrite magnet with an arcuate cross section is molded.
A molding device that is commonly used as an A-type molding device fills a molding space in a die with slurry-like raw material powder, and passes the raw material powder in a magnetic field through an upper punch having a concave curved surface and a lower punch having a convex curved surface. It is configured to be compression molded.

Generally, when an anisotropic ferrite magnet is molded using a molding device with the above configuration, the inner peripheral surface becomes a ferromagnetic surface due to the influence of water handling during compression molding or the difference in molding density between the upper punch side and the lower punch side. The outer peripheral surface was a weakly magnetic surface, and there was a difference in magnetic properties between the inner peripheral surfaces.

When a magnet with such a difference in magnetic properties is used in a motor, etc., the inner peripheral surface side, which is a ferromagnetic surface, should face the drive coil. In addition, in recent years, there has been a strong demand for miniaturization and improved characteristics of various devices, and there is a strong desire to improve the total magnetic flux (ΦT) on the outer peripheral surface side of the arcuate magnet.

However, no means has been established to actively provide desired differences in the strength of magnetic properties to the inner peripheral surface of an anisotropic ferrite magnet with an arcuate or semi-cylindrical cross section.
No. 8541 proposes a method of controlling the strength of the magnetic properties of a flat plate magnet by changing the area ratio of the upper and lower punch pole faces during compression molding in a magnetic field.

Purpose of the Invention The present invention relates to a molding device for an anisotropic ferrite magnet having an arcuate cross section or a kamaboko cross section. The aim is to create a molding device that can significantly improve magnetic properties.

Structure and Effects of the Invention The present invention has been made as a result of various studies on means for creating a difference in magnetic properties on the inner peripheral surface of an anisotropic ferrite magnet with an arcuate or semicircular cross section. For example, in the case of an anisotropic ferrite magnet with an arcuate cross section, By interposing a non-magnetic material with a bow-shaped cross section in a lower punch made of magnetic material and compression molding it, it is possible to increase the difference in magnetic properties between both sides of the resulting magnet, and to significantly improve the magnetic properties of the outer circumferential surface. This is what I learned about what I can do.

However, in this invention, a molding space in a die is filled with slurry-like raw powder, and the raw material powder is passed through an upper punch having a concave curved surface and a lower punch having a convex curved surface or a flat surface in a magnetic field. In a molding device for an anisotropic ferrite magnet having an arcuate cross section or a kamaboko cross section which is compression molded by compression molding, at least the contact surface with the filled raw material powder is placed on the molding space side surface of the lower punch, in the case of a molded body having an arcuate cross section. At least a non-magnetic material with a convex curved surface on the molding space side, and in the case of a molded body with a kamaboko cross section, a ferrite characterized by providing a non-magnetic material with a flat surface on the molding space side and a concave curved surface or a flat surface on the lower punch side. This is a magnet molding device.

In this invention, the non-magnetic material interposed between the magnetic pole surface of the lower punch and the raw material powder, for example, having a bow-shaped cross section, a semi-cylindrical cross-section, or a concave lens shape, should be prepared in advance from the lower punch's lI! ! A configuration in which it is provided on the pole surface is desirable. Furthermore, any known configuration of the compression molding device can be applied.

Punch the non-magnetic material above! The i magnetic pole surface can be provided, for example, by pasting a non-magnetic material with the same size as the +41 pole surface on the fi1 pole surface, or by attaching a non-magnetic material with the same size as the cross section of the molding space at the center of the magnetic pole surface.
Alternatively, when the lower punch comes into contact with the die, a non-magnetic material with a size slightly larger than the molding space may be fitted to at least the contact surface with the filled raw material powder on the inner circumferential surface of the lower punch on the molding space side. In order to prevent the raw material powder from leaking, a non-magnetic material having an arcuate cross section may be provided, and may be appropriately selected in consideration of the shape and dimensions of the object to be molded and the required magnetic properties.

In order to obtain a molded product with a bow-shaped cross-section, the shape of the non-magnetic material provided in the lower punch can be various shapes such as a bow-shaped cross-section, a kamaboko-shaped cross-section, a haiku-shaped cross-section, etc., where the central part of the cross-section is thick. By changing the thickness of the non-magnetic material portion with a bow-shaped cross section provided on the surface by varying the center point of the arc on the outer circumferential surface and the center point of the circular arc on the inner circumferential surface of the non-magnetic material (eccentricity amount Δ吏), the center portion is made thicker. This method is extremely effective in increasing the difference in magnetic properties of the inner circumferential surface of the obtained permanent magnet having an arcuate cross section, and greatly improving the magnetic properties of the outer circumferential surface.

In addition, when molding the magnet 5 having a kamaboko-shaped cross section, the shape of the non-magnetic material for the lower punch may be such that the molding space side is flat and the lower punch side is concavely curved or flat; for example,
The thickness of the concave lens-shaped non-magnetic material with a flat side surface of the molding space is:
It is sufficient that the thickness of the central part is thinner than the thickness of the surrounding area, and it is extremely effective in greatly improving the magnetic properties of the outer circumferential surface, and if selected appropriately taking into consideration the shape and dimensions of the object to be molded and the required magnetic properties. good.

Furthermore, the thickness (T>) of the non-magnetic material may be appropriately selected depending on the shape of the molded body, but if it is too thick, a large amount of current will be required to form an appropriate magnetic field, causing various problems in efficiency; Although a sufficient effect cannot be obtained if the temperature is too high, the present inventor has found that the conditions described below are preferable.

When installing a non-magnetic material of the same size on the magnetic pole surface of the lower punch: T: 5mm to 60mm.

Δi: 0.1 T to 1.5 mm Based on the drawings (Disclosure of the Invention) Figures 1 and 2 are longitudinal cross-sectional views of the molding apparatus according to the present invention, and Figure 1 shows the case of molding a magnet with an arch-shaped cross section. , second
The figure shows the case of molding a permanent magnet with a kamaboko cross section.

The molding space is formed by inserting a prismatic lower punch (21) made of a magnetic material and having a convex curved surface into a prismatic space provided in a die (1) made of a non-magnetic material, and the raw material powder is placed in the same space. filled inside.

In addition, a prismatic upper punch (4) having a concave curved surface is in contact with the upper end surface of the die (1), and a lower punch (21) is fitted into the die (1). body (3)
, use a non-magnetic material with an arch-shaped cross section whose upper surface dimension is the same as that of the lower punch (a), which is attached to the lower punch (21), and which is attached to the center point of the arc on the outer peripheral surface of the non-magnetic material (3). In Fig. 2, a concave lens with the same upper surface dimensions as the lower punch (2J), a flat surface on the molding space side, and a concave curved surface on the lower punch side. A non-magnetic material (3) made of a mold is pasted on the magnetic pole surface of the lower notch (2).

Roughly speaking, the upper punch (4) and lower punch (a) are equipped with hydraulic cylinders (not shown) that move vertically to apply pressure, and the outer peripheries of the upper punch (4) and lower punch (2) are An electromagnetic coil (5) for forming a magnetic field must be provided.

In the molding apparatus having the above configuration, after the molding space in the die (1) is filled with slurry-like raw material powder, the electromagnetic coil (5) is excited to form a magnetic field, and the die (1) is heated.

The upper punch (4) is lowered to perform compression molding.

At this time, water in the slurry-like raw material powder can be removed, for example, by draining water from the water intake hole installed in the upper punch (4), or by using a filter such as a filter cloth between the upper punch (4) and the raw material powder. Drain more water.

Also, lower punch IIT! The ratio of the cross-sectional area Su of the pole surface to the cross-sectional area 3d provided in the molding space in the die, Su
When /3d is 1 or more, the effects of the present invention are fully exhibited.

On the other hand, a case has been described in which the electromagnetic coils are provided on the outer peripheries of the upper punch and the lower punch, respectively, but in this case, it is preferable that the magnetomotive force balance of the upper and lower coils be equal or stronger on the upper side.

Alternatively, if the magnetomotive force is sufficiently large, it may be provided around only the upper punch. Further, an electromagnetic coil may be provided on the outer periphery of the die.

Using the molding apparatus according to the present invention shown in FIGS. 1 and 2 described in Example, a slurry-like raw material powder containing 10% of 5R0 and 88% of Fe2O3 was heated to 0.5 LJ in a magnetic field of 8 koa.
In the case of an arcuate cross-section magnet, the outer diameter R242+
+u++X Inner diameter Rt 36mm x Width 70mm x Height 45mm
In the case of a kamaboko type magnet, the outer diameter is R24.
It was molded into a size of 2 mm x width 70 mm x height 45 mm, and the resulting molded body was sintered at 1250° C. for 1 hour to obtain anisotropic ferrite magnets with an arcuate cross section and a kamaboko cross section.

In addition, an anisotropic ferrite magnet was obtained using a conventional apparatus that was molded and sintered under exactly the same conditions except that no non-magnetic material was interposed in the lower punch.

1! The measurement results (Br ratio ) and the total magnetic flux (Φ haze) on the outer circumferential surface are shown in Table 1, comparing the measurement results with those of the comparative example. It can be seen that the difference in magnetic properties between the cylindrical circumferential surfaces of the anisotropic ferrite magnets having a bow-shaped cross section and a semi-cylindrical shape increases, and the magnetic properties on the outer circumferential surface side are significantly improved.

[Brief explanation of drawings]

FIGS. 1 and 2 are longitudinal cross-sectional views of the molding apparatus according to the present invention, and FIG.
The figure shows the case of molding a permanent magnet with a kamaboko cross section. 1... Dice, 2... Lower punch, 3... Non-magnetic material, 4... Upper punch, 5... Electromagnetic coil.

Claims (1)

[Claims] 1. A molding space in a die is filled with slurry-like raw material powder, and the raw material powder is compressed and molded in a magnetic field by an upper punch having a concave curved surface and a lower punch having a convex curved surface. In an apparatus for molding an anisotropic ferrite magnet having an arcuate cross section, a nonmagnetic material having a convex curved surface at least on the molding space side is provided on the molding space side surface of the lower punch at least in the contact surface with the filled raw material powder. A molding device for anisotropic ferrite magnets. 2. The thickness of the non-magnetic material having a bow-shaped cross section provided on the molding space side surface of the lower punch is made thicker at the center by making the center point of the arc on the outer peripheral surface of the non-magnetic material eccentric and the center point of the arc on the inner peripheral surface of the non-magnetic material. An apparatus for molding an anisotropic ferrite magnet according to claim 1. 3 A molding space in a die is filled with a slurry-like raw material powder, and the raw material powder is compressed and molded in a magnetic field by an upper punch having a concave curved surface and a lower punch having a flat surface to produce an anisotropic ferrite whose one side is an arcuate surface. The magnet molding device is characterized in that a non-magnetic material is provided on the molding space side surface of the lower punch at least in the contact surface with the filled raw material powder, and the molding space side is flat and the lower punch side is a concave curved surface or flat surface. Anisotropic ferrite magnet molding equipment.