JP2003053596A - Method for packing magnetic powder material and method for producing magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for packing a magnetic powder material into a cavity of a press device uniformly, quickly and excellently in reproducibility. SOLUTION: This method for packing magnetic powder material 14 into the cavity 112 of a press device 100 contains a process (a) of supplying the magnetic powder material to an upper part of the cavity and a process (b) of actuating a force which directs the bottom part of the cavity to the magnetic powder material by applying an alternating decay pulse magnetic field to the space containing the cavity. The magnetic powder material is quickly packed by magnetic attracting force, at the same time, is subjected to demagnetizing action of the alternating decay pulse magnetic field and, therefore, is packed uniformly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for filling a cavity of a press machine with a magnetic powder material and a method for producing a magnet, and more particularly, a method for filling a magnetic powder material suitably used for producing an anisotropic magnet. Regarding

[0002]

2. Description of the Related Art Currently, rare earth sintered magnets are used as rare earth sintered magnets.
Two types of magnets are widely used in each field: cobalt magnets and rare earth / iron / boron magnets. Among them, rare earth / iron / boron magnets (hereinafter referred to as "RT- (M) -B magnets". R is a rare earth element containing Y, T is Fe or a mixture of Fe and Co and / or Ni. , M is an additive element (for example, Al, Ti, Cu, V, Cr, Ni, Ga, Z
At least one of r, Nb, Mo, In, Sn, Hf, Ta and W) and B are boron or a mixture of boron and carbon. ) Indicates the highest maximum magnetic energy product among various magnets, and the price is relatively low, and is therefore actively used in various electronic devices.

A sintered magnet using a rare earth alloy is, for example,
It is manufactured as follows.

(1) A raw material metal is melted at a high temperature to obtain a rare earth alloy lump having a predetermined composition.

(2) This alloy lump is pulverized to obtain a fine rare earth alloy powder (also called "magnetic powder material" for simplicity).

(3) The obtained magnetic powder material (the surface of which is provided with a lubricant if necessary) is press-molded in a magnetic field to obtain a molded product having a predetermined shape.

(4) This molded body is heated to a high temperature (for example, about 100).
Sintered at 0 ° C. or higher) to obtain a sintered magnet.

(5) In order to improve the magnetic properties of the obtained sintered magnet, a heat treatment called an aging treatment is further performed.

(6) The surface of this sintered magnet is ground to adjust its size and shape.

In order to efficiently produce a sintered magnet, it is necessary to efficiently produce a molded product having a predetermined shape. For that purpose, a predetermined amount of magnetic powder material is reproducibly provided in the cavity, and It is desirable to fill the magnetic powder material in the cavity so that the packing density is uniform. If the filling amount in the cavity varies, the weight of the obtained molded body varies. Further, if the packing density of the magnetic powder material in the cavity is not uniform, a molded product having a predetermined shape may not be obtained, or density variations may be formed in the molded product.

Conventionally, in order to supply magnetic powder into a cavity (molding space) of a press machine, a feeder box (or feeder cup) is slid onto the cavity,
The powder was dropped into the cavity by using the powder's own weight in the feeder box (sometimes called the natural filling method).

1A to 1C schematically show a conventional powder filling method using a feeder box. According to this conventional method, as shown in FIGS. 1A to 1C, the feeder box 1 is placed above the cavity 12 formed by the die 10 and the lower punch 11 of the powder pressing apparatus.
When 3 slides laterally, feeder box 13
The magnetic powder 14 therein was filled in the cavity 12.
In this method, the upper part of the filling powder is moved downward (in the direction of arrow A) by a pressurizing means such as an agitator (not shown) provided in the feeder box 13 for the purpose of reducing the dispersion of the single weight.
(For example, Japanese Patent Laid-Open No. 2000-248301)
(See the official gazette).

According to such a conventional filling method using the feeder box, the powder can be reliably filled in the cavity, and the volume of the filling powder by the bottom of the feeder box is controlled to be almost constant by "slipping". It is possible to Further, by using such a filling method, it is possible to realize low density filling to the extent that magnetic field orientation is possible.

[0014]

However, when the above-mentioned scraping and filling method is used, one filling step requires about 20 to 30 seconds or more.

Further, as a method for improving the filling speed of the magnetic powder material, a method utilizing a magnetic attractive force has been studied. For example, in Japanese Patent Publication No. 7-11013, in order to fill a cylindrical cavity with magnetic powder at a high speed,
A method is disclosed in which a magnetic pole is provided in the center of a cylindrical cavity and magnetic powder is filled in the cavity using a magnetic field formed by a solenoid coil provided above the cavity. By using this method, the outer diameter 1
It is described that a cylindrical cavity having a diameter of 8 mm, an inner diameter of 16 mm and a height of 15 mm was filled with the magnetic powder material in 3 to 5 seconds. However, in order to execute this filling method, since the solenoid coil and the like are arranged on the upper surface of the mold, there is a problem that the mechanism of the feeder box becomes complicated.

The present invention has been made in view of the above points, and a method of uniformly filling a cavity of a press machine with a magnetic powder material at high speed and with good reproducibility, and manufacturing a magnet using such a filling method. The purpose is to provide a method.

[0017]

A method of filling a magnetic powder material according to the present invention is a method of filling a magnetic powder material into a cavity of a press machine, and (a) a step of supplying the magnetic powder material above the cavity. And (b) applying an alternating damping pulse magnetic field to the space containing the cavity to exert a force on the magnetic powder material toward the bottom of the cavity, thereby achieving the above object. .

It is preferable that the magnetic powder material filled in the cavity in this step (b) is substantially demagnetized.

The alternating damping pulse magnetic field is preferably formed by an electromagnetic coil provided below the bottom of the cavity.

The alternating damping pulse magnetic field includes a plurality of pulses, and the absolute value of the k-th (k is an integer of 1 or more) peak of the plurality of pulses is at a level equal to or higher than the coercive force of the magnetic powder material. And the absolute value of the peak of the pulse after the k + 1th pulse is lower than the coercive force of the magnetic powder material, and the absolute value of the k + 1th peak is 40% or more and 95% or less of the absolute value of the kth peak. It is preferable to satisfy the relationship.

A yoke made of a ferromagnetic material is preferably arranged at the bottom of the cavity.

In a preferred embodiment, the step (a) includes a step of dropping the magnetic powder material into the cavity by its own weight.

In the method for manufacturing a magnet according to the present invention, a step of filling the cavity with the magnetic powder material using any one of the filling methods described above, and (c) uniaxially filling the cavity with the magnetic powder material A step of producing a molded product by press molding, whereby the above object is achieved.

Before the step (c), a step of applying an orientation magnetic field to the magnetic powder material filled in the cavity may be further included.

A method of manufacturing a magnet according to a preferred embodiment further includes a step of sintering the compact.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Hereinafter, a method for manufacturing a rare earth sintered magnet to which the present invention is preferably used will be described, but the present invention is not limited to this.

The press molding process (including the step of filling the magnetic powder material) in the method of manufacturing the magnet according to the present embodiment will be described with reference to FIGS. 2 (a), 2 (b) and 3. 2A and 2B are diagrams schematically showing the operation in the press forming process, and FIG. 3 shows the center P of the cavity 112 in the press forming process.
1 (see FIG. 2) shows the change over time of the magnetic field.

First, as the magnetic powder material, for example, R-
A T- (M) -B based magnetic powder material is prepared. For example, US Pat. No. 4,770,723 and US Pat. No. 4,7.
The magnetic powder material described in the specification of No. 92,368 can be preferably used. The average particle diameter (mass median diameter) of the magnetic powder material used for press molding is preferably in the range of 1.5 μm to 10 μm from the viewpoint of magnetic properties.

Next, as shown in FIG. 2A, the magnetic powder material 14 is supplied above the bottom 112b of the cavity 112 of the pressing apparatus 100.

Here, the press device 100 may be a known uniaxial press molding device, for example, a hydraulic press device is used. The pressing apparatus 100 has a die 110, a lower punch 111a, and an upper punch 111b. A cavity (molding space) 112 is defined by the opening 110a of the die 110 and the lower punch 111a. For example, the cavity 112 is cylindrical and has a diameter of 25 mm and a depth of 15 mm.

The magnetic powder material 14 is preferably supplied by a natural filling method, for example, a feeder box 220.
The magnetic powder material 14 contained therein is fed above the bottom 112b of the cavity 112 in a manner similar to that described with reference to FIGS. 1 (a) and 1 (b).
At this time, the magnetic powder material 14 falls by gravity into the cavity 112 due to its own weight. However, the packing density of the magnetic powder material 14 in the cavity 112 is affected by the weight of the magnetic powder material 14 existing thereon. Here, in the feeder box 220, the depth (1
A magnetic powder material 14 having a height about 2 to 10 times (5 mm) is prepared. The magnetic powder material 14 is RT-
When a material that is easily oxidized, such as (M) -B magnetic powder, is used, the feeder box 2 is used to suppress the oxidation.
It is preferable to replace the inside of 20 with an inert gas or to let the inert gas flow.

Next, with the feeder box 220 arranged so as to cover the cavity 112, the cavity 1
By applying an alternating damped pulse magnetic field to the space containing 12, the magnetic powder material 14 is applied to the bottom 11 of the cavity 112.
A force toward 2b is applied (period T1 in FIG. 3). This magnetic field is sometimes referred to as a "filling magnetic field H _1".

The pressing apparatus 100 has an electromagnetic coil 130 below the bottom 112b of the cavity 112, and a predetermined current is passed through the electromagnetic coil 130 to form a magnetic field in the space including the cavity 112.
For example, inner diameter 135 mm, outer diameter 340 mm, height 120
An electromagnetic coil 130 having a diameter of 8 mm, an outer diameter of 8 mm, an inner diameter of 4 mm, and a winding number of 120 turns is used. The electromagnetic coil 130 can form a maximum magnetic field of about 6.2T at the center P ₀ between the magnetic poles, at which time the center P ₁ of the cavity 112 is about 0.8T.
Form a magnetic field of T. The direction of the magnetic field at P ₁ is approximately the direction toward the bottom 112 of the cavity 112, and causes the magnetic powder material 14 to exert a force toward the bottom 112 b of the cavity 112. The magnetic attraction force causes the magnetic powder material 14 to be filled into the cavity 112 at a high speed.

This alternating damping pulse magnetic field is, for example, as shown in FIG.
It has a profile as shown in (a). Here, the maximum value of the strength of the filling magnetic field H ₁ (this may be simply referred to as “the strength of the filling magnetic field”) is 0.80 T (Tesla), and alternating to 0 T (Tesla) in 0.05 seconds. While applying the filling magnetic field H ₁ which attenuates. Due to the magnetic attractive force acting on the magnetic powder material 14 while the filling magnetic field H ₁ is being applied, the magnetic powder material 14 is moved to the cavity 112.
Filled inside. Further, since the filling magnetic field H ₁ is an alternating damping pulse magnetic field, it has a function of demagnetizing the magnetic powder material 14 in the cavity 112 and the feeder box 220 in the magnetic field.

For example, as shown in FIG. 4B, the filling magnetic field H is a pulsed magnetic field that monotonically attenuates (without polarity reversal).
Even when applied as ₁ , it was possible to improve the filling speed and reduce the variation in the weight of the single body as in the case where the alternating damping pulse magnetic field shown in FIG. 4A was applied.
However, since the filled magnetic powder material 14 is magnetized, the magnetic powder material 14 continues in the direction of the filling magnetic field H ₁ to form needle-like aggregates. As a result, the packing density of the magnetic powder material 114 in the cavity 112 became non-uniform, and it was not possible to manufacture a molded body having a uniform density. In some cases, cracks may occur and a molded product having a desired shape may not be obtained. Further, when a feeder box such as the feeder box 220 is used, the magnetic powder material in the feeder box is also magnetized, and continuous powder feeding may not be possible in some cases.

In the filling method of the present invention, the alternating damping pulse magnetic field having a demagnetizing effect is applied as the filling magnetic field H ₁ to generate a monotonically decaying pulse magnetic field (see FIG. 4B). Cavity 112
The problem of non-uniformity of packing density inside is prevented.
Further, although the magnetic powder material in the feeder box 220 is once magnetized, it is demagnetized, so that continuous powder feeding becomes possible. It is preferable that the magnetic powder material 14 is substantially demagnetized in a state of being filled in the cavity 112. However, as long as it is possible to secure the uniformity of the filling density that does not cause a problem in the pressing process, the magnetic powder material 14 may be slightly demagnetized. The magnetization may remain. This depends on the shape and density of the molded body, the moldability of the magnetic powder material, the pressing conditions, and the like, so that the profile of the alternating damping pulse magnetic field may be set appropriately. Further, the alternating decay pulse magnetic field may be applied a plurality of times, and the profiles of the alternating decay pulse magnetic field when applied a plurality of times may be different from each other. However, in order to fully exert the demagnetizing action of the alternating damping pulse magnetic field, it is preferable to satisfy the following conditions.

First, the alternating damping pulse magnetic field includes at least two pulses having different polarities, and preferably includes three or more pulses. The absolute value of the k-th (k is an integer of 1 or more) peak of a plurality of pulses included in the alternating damping pulse magnetic field is at a level equal to or higher than the coercive force of the magnetic powder material 14, and of the k + 1-th and subsequent pulses. The absolute value of the peak is at a level lower than the coercive force of the magnetic powder material 14, and k +
The absolute value of the 1st peak is 4 of the absolute value of the kth peak
It is preferable to satisfy the relationship of 0% or more and 95% or less.
When this is expressed by an attenuation factor, it is preferable that the attenuation factor is 5% or more and 60% or less. It is preferable that the number of pulses is large, but if the application time of the filling magnetic field H ₁ is long, the process time is unnecessarily extended, and therefore the number is appropriately set. At least the first pulse has a magnetic field strength equal to or higher than the coercive force of the magnetic powder material 14, the second pulse has the opposite polarity to the first pulse, and the absolute value is 40% or more and 95% or less of the absolute value of the first pulse. You only have to have

The time for applying the filling magnetic field H ₁ (period T1 in FIG. 3) is preferably 0.01 second or more and 1 second or less. If it is shorter than 0.01 seconds, the effect of improving the filling speed and the demagnetizing effect cannot be sufficiently obtained. On the contrary, even if the filling magnetic field H ₁ is applied for a time exceeding 1 second, these effects are not further improved. Therefore, from the viewpoint of shortening the process time, the application time T 1 is 1 second or less. It is enough.

In order for the filling magnetic field H ₁ to effectively act on the magnetic powder material 14 in the cavity 112, the upper portion of the lower punch 111a (the bottom portion 112b of the cavity 112).
It is preferable that the portion constituting) is made of a ferromagnetic material. If this portion is made of a non-magnetic material, the direction of the filling magnetic field H ₁ is disturbed and the desired effect cannot be obtained. Therefore, the lower punch 111a is preferably formed using a ferromagnetic material (for example, high manganese steel). Cavity 11
In order to enhance the uniformity of the strength and the direction of the magnetic field (including the orientation magnetic field H ₂ and the demagnetizing magnetic field H ₃ described later) formed in the No. ₂ , at least the upper layer portion of the lower punch 11a (the depth of the cavity 112 is approximately the same as Is preferably formed of a ferromagnetic material.

After the application of the filling magnetic field H ₁ is finished, FIG.
By moving the feeder box 220, as described with reference to FIG.
The extra magnetic powder material 14 on the upper side is scraped off, and the magnetic powder material 14 of the content integral of the cavity 112 is removed.
2 is filled. At this time, since the magnetic powder material 14 in the cavity 112 is hardly magnetized because it is filled by using the alternating damping pulse magnetic field, its surface is almost flat and the filling density of the cavity 112 is highly uniform.

After that, as shown in FIG. 2B, the upper punch 116 is lowered to close the opening 110a of the die 110 and the orientation magnetic field H ₂ (for example, 0.8T to 1.4).
T) is applied, the upper punch 116 is further lowered,
The magnetic powder material 14 is uniaxially pressed. When the orientation magnetic field H ₂ parallel to the pressing direction is applied, the orientation magnetic field H ₂ can be formed by using the coil 130 for forming the filling magnetic field H ₁ . Of course, another coil may be provided to form the orientation magnetic field H ₂ . Here, the orientation magnetic field H ₂
Is parallel to the pressing direction, the orientation magnetic field H _{2 in the} direction perpendicular to the pressing direction may be applied. In this case, it is preferable in view of magnetic characteristics that the filling magnetic field H ₁ is also applied in the direction perpendicular to the pressing direction.

With the orientation magnetic field H ₂ applied, the upper punch 111b is lowered and a predetermined pressure (for example, 10 MPa to 150 MPa) is applied to the magnetic powder material 14 to perform uniaxial press molding. A demagnetizing magnetic field (for example, 1.6 T) is applied before the end of the uniaxial pressing process. The period for applying the orientation magnetic field H ₂ and the demagnetizing magnetic field H ₃ (T2 in FIG. 3) is appropriately set within the pressing time of the uniaxial pressing process. A pulse magnetic field or a static magnetic field can be used as the applied magnetic field, and a combination of the pulse magnetic field and the static magnetic field may be used. Depending on the type of magnetic field applied, the period T2 depends on the type of press machine, but is, for example, 0.01 seconds to.
It is in the range of 30 seconds. The period T2 is, for example, 5 seconds when only the pulse magnetic field is used, 10 seconds when only the static magnetic field is used, and 10 seconds when the pulse magnetic field and the static magnetic field are used in combination. .

Thereafter, the upper punch 111b is retracted, the lower punch 111a is raised, and the opening 110 of the die 110 is opened.
The molded body exposed from a is transferred from the press device 100,
Move on to the next step.

Thereafter, according to a known method, a sintered magnet is obtained through a sintering step and an aging treatment step. The sintering step is performed at a temperature of, for example, about 1000 ° C. to about 1100 ° C. in an inert gas (rare gas or nitrogen gas) atmosphere or in vacuum for about 1 to 5 hours. The aging treatment is, for example, about 4
It is carried out at a temperature of 50 ° C. to about 800 ° C. for about 1 to 8 hours. Note that, in order to reduce the amount of carbon contained in the sintered body and improve the magnetic characteristics, the lubricant covering the surface of the magnetic powder may be removed by heating before the above-mentioned sintering step, if necessary. . The heating and removing step is performed, for example, at a temperature of about 100 ° C. to 600 ° C. in a reduced pressure atmosphere for about 3 to about 6 hours, depending on the type of the lubricant. After that, surface treatment is performed if necessary.

Specific examples will be described below.

First, as magnetic powder materials, Nd: 16% by mass, Dy: 5% by mass, B: 1% by mass, Co: 1% by mass, Al: 0.2% by mass, Cu: 0.1% by mass, The rest:
Magnet powder having an iron alloy composition (FSSS particle size: 3.0
˜3.2 μm, saturation magnetization: 1.6 T) was prepared.

As mentioned above, the diameter is 25 mm and the depth is 1.
The feeder box 220 is installed in the 5 mm cavity 112.
After supplying the magnetic powder material 14 using
And applying an alternating damping pulsed magnetic field having a profile shown in FIG. 4 (a) as _1. Filling magnetic field H ₁ with different strength (maximum value) (0.36T, 0.62T, 0.82T)
5 (a) and (b) show the variation coefficient ((standard deviation / average value) × 100) of the filling amount and the filling density, respectively, when the voltage was applied once (0.05 seconds) (Example). It was Further, FIG. 5 (a) and 5 (b), are shown together the results of the applied with no filling magnetic field H ₁ (i.e., to the filling magnetic field H ₁ and zero magnetic field) if (Comparative Example 1) .

A yoke made of high manganese steel was placed on the lower punch 111a of the used pressing apparatus 100. Further, the molded body density by using the pressing device 100 to form a compact of ^{4.0g / cm 3 ~4.5g / cm 3} . The number of samples, including the comparative example, is 20
And The cycle time of the press molding process (see FIG. 3) was 5 seconds. The obtained molded body was sintered by a known method to obtain a sintered magnet.

As can be seen from FIG. 5A, the filling magnetic field H
By applying ₁ (0.36 T or more), the variation in the filling amount was significantly reduced. Filling magnetic field H of 0.82T
_{When 1} was applied (see FIG. 3, application time was 2 seconds), the coefficient of variation of the filling amount was 1.48%, which was extremely low.

Further, the magnetic powder material 14 in the cavity 112 is not magnetized by the application of the filling magnetic field H ₁ , and the magnetic powder so that the surface of the cavity 112 becomes flat after the feeder box 220 is retracted. Material 14
Were uniformly filled.

When the filling magnetic field H ₁ was not applied (Comparative Example 1), it took about 5 seconds to fill the magnetic powder material 14, and the variation coefficient of the filling amount was as high as 4.59%. .

For comparison, when the filling magnetic field H ₁ is a magnetic field which has a maximum value of 0.82T and monotonically attenuates according to the profile shown in FIG. 4B, is applied once (0.05 seconds). (Comparative Example 2) The coefficient of variation of the packing density was as small as that of the example, but the magnetic powder material 14 was magnetized, resulting in an uneven distribution, and it was difficult to obtain a desired compact. .

Further, according to the embodiment of the present invention, FIG.
As shown (b), the the strength of the filling magnetic field H ₁ is increased, than when applied with no filling magnetic field H _1,
The packing density increased (2.3 g / cm ^{3 at} 0.82T), but these were at a level that did not hinder magnetic field orientation.

For example, as shown in FIG. 6, 0.82T
Of the orientation magnetic field H _{2 of} 0.80T after applying the filling magnetic field H ₁ of
By applying (a pulsed magnetic field as shown in FIG. 3, application time 5 seconds), the orientation of the magnetic powder particles is further increased, and the residual magnetic flux density Br of the finally obtained sintered magnet is increased. You can see that Further, as shown in FIG. 6, it is understood that the orientation of the magnetic powder particles is improved by applying the filling magnetic field H ₁ even when the orientation magnetic field H ₂ is not applied. That is, the filling magnetic field H ₁
Has a function of filling the cavity 112 with the magnetic powder material 14 at a high speed, and is capable of sufficiently demagnetizing the magnetic powder material, so that an excellent compact can be produced with high efficiency. To Furthermore, the filling magnetic field H
₁ also functions to magnetically orient magnetic powder particles.

Although the embodiment of the present invention has been described by taking the method of manufacturing a sintered magnet as an example, the present invention is not limited to this and can be applied to the manufacture of other magnets such as anisotropic bonded magnets. Further, the effect of demagnetization by the alternating damping pulse magnetic field in the filling method according to the present invention is, as shown in the embodiment, a thin molded body is molded by parallel pressing (the direction of the orientation magnetic field and the pressing direction are substantially parallel). Although notable at this time, the effect is exerted also in the molding of a molded body having another shape or in the orthogonal pressing (the direction of the orientation magnetic field is orthogonal to the pressing direction). Note that a thin molded body refers to one in which the square root of the pressed surface area of the molded body (typically corresponding to the bottom area of the cavity) is larger than the height (corresponding to the cavity depth). And

In this embodiment, only the alternating damping pulse magnetic field is applied to fill the cavity with the magnetic powder material. However, the present invention is not limited to this, and a static magnetic field may be further applied together with the alternating damping pulse magnetic field.

[0057]

According to the present invention, there is provided a method of uniformly filling a cavity of a press machine with a magnetic powder material at high speed and with good reproducibility. In particular, according to the present invention, a rare earth alloy powder produced by a quenching method such as a strip casting method can be used to form a compact having a uniform density with high efficiency, so that a rare earth sintered magnet can be produced with high productivity. Can be manufactured.

[Brief description of drawings]

1A to 1C are process cross-sectional views schematically showing a powder supply method using a conventional feeder box.

2A and 2B are schematic views for explaining a press molding process according to the present invention.

FIG. 3 is a schematic diagram showing a time profile of magnetic field application in the press molding process according to the present invention.

FIG. 4 (a) is a diagram showing a profile of an alternating damping pulse magnetic field used as a filling magnetic field H ₁ in the filling method according to the present invention, and FIG. 4 (b) is a diagram showing a profile of a monotonically damping pulse magnetic field for comparison. is there.

5A is a graph showing the relationship between the strength of the filling magnetic field H ₁ and the variation coefficient of the filling amount, and FIG. 5B is the filling magnetic field H ₁
3 is a graph showing the relationship between the strength of the and the packing density.

FIG. 6 is a graph showing the relationship between the strength of the filling magnetic field H ₁ and the residual magnetic flux density.

[Explanation of symbols]

10,110 dies 11,111a Lower punch 12,112 Cavity (molding space) 13,220 feeder box 14 Magnetic powder material 100 Press machine (powder press molding machine) 110a Die opening 111b Upper punch 112b bottom of cavity 130 electromagnetic coil

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Atsushi Ogawa             2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka Prefecture             Sumitomo Special Metals Co., Ltd. Yamazaki Works F-term (reference) 4K018 CA04 KA45                 5E062 CC05 CE04 CF04 CG01

Claims (9)

[Claims] 1. A method for filling a cavity of a press machine with a magnetic powder material, comprising: (a) supplying the magnetic powder material above the cavity; and (b) an alternating damping pulse magnetic field in a space including the cavity. Applying a force to the magnetic powder material toward the bottom of the cavity by applying the magnetic powder material. 2. The method of filling a magnetic powder material according to claim 1, wherein the alternating damped pulse magnetic field is formed by an electromagnetic coil provided below the bottom portion of the cavity. 3. The alternating damping pulse magnetic field includes a plurality of pulses, and the absolute value of a k-th (k is an integer of 1 or more) peak of the plurality of pulses is equal to or higher than a coercive force of the magnetic powder material. And the absolute value of the peak of the pulse after the (k + 1) th is at a level lower than the coercive force of the magnetic powder material, and the absolute value of the (k + 1) th peak is 40% or more of the absolute value of the kth peak. The filling method of the magnetic powder material according to claim 1 or 2, which satisfies the following relation. 4. The method of filling a magnetic powder material according to claim 1, wherein a yoke made of a ferromagnetic material is arranged at the bottom of the cavity. 5. The magnetic powder material filled in the cavity in step (b) is substantially demagnetized.
The filling method of the magnetic powder material according to claim 1. 6. The magnetic powder material according to claim 1, wherein the step (a) includes a step of dropping the magnetic powder material into the inside of the cavity by the weight of the magnetic powder material. Filling method. 7. A step of filling the cavity with the magnetic powder material by using the magnetic powder material filling method according to claim 1, (c) the magnetic powder filled in the cavity. And a step of producing a molded body by uniaxially press-molding a material. 8. The method for manufacturing a magnet according to claim 7, further comprising a step of applying an orientation magnetic field to the magnetic powder material filled in the cavity before the step (c). 9. The method for producing a magnet according to claim 7, further comprising a step of sintering the compact.