JP2007059445A - Manufacturing method of annular magnetic material, and the annular magnetic material manufactured by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of continuously manufacturing an annular magnetic material with excellent magnetic characteristics, in particular high (BH)max, with high yield. <P>SOLUTION: The manufacturing method of the annular magnetic material is characterized by that relations of 0<(1-D<SB>1</SB>/D<SB>2</SB>)×100≤70 and 30≤ä1-(D<SB>2</SB><SP>2</SP>-d<SB>2</SB><SP>2</SP>)/(D<SB>1</SB><SP>2</SP>-d<SB>1</SB><SP>2</SP>)}×100≤94 are concurrently satisfied when inserting, from a second through hole 1B of a die 2 having a through hole 1 including a first through hole 1A with a diameter of D<SB>1</SB>, the second through hole 1B with a diameter of D<SB>2</SB>(where D<SB>1</SB><D<SB>2</SB>) and a tapered hole 1C located between the first and second through holes 1A and 1B, a mandrel 3 having a cylindrical tip 3A with a diameter of d<SB>1</SB>, a cylindrical base with a diameter of d<SB>2</SB>(where d<SB>1</SB><d<SB>2</SB><D<SB>2</SB>) and a tapered part 3C located between the tip 3A and the base 3B, and plastic-forming a preform 5 by a pressure punch 4 with an outer diameter D<SB>1</SB>and an inner diameter d<SB>1</SB>to manufacture the annular magnetic material in a gap between the through hole 1 of the die 2 and the mandrel 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a ring-shaped magnet material and a ring-shaped magnet material manufactured by the method. More specifically, the present invention relates to a ring-shaped magnet material having excellent magnetic properties, continuously or at a high yield. The present invention relates to a method of manufacturing a ring-shaped magnet material that can be manufactured with a handle and can be manufactured with a large degree of design freedom with respect to required characteristics.

Among Nd—Fe—B magnets, those having radial anisotropy by extrusion are particularly useful as materials for ring magnets.
Conventionally, such a ring-shaped magnet material is manufactured as follows. First, for example, an ultra-quenched ribbon of a rare earth magnet alloy is pulverized into a powder, and this powder is cold pressed to form a green compact. Next, the green compact is warm-pressed or hot-pressed to increase the density to obtain, for example, a cylindrical body having a desired size.

And, for example, by performing backward extrusion molding in a warm manner to this cylindrical body, the crystal axis is aligned and magnetic anisotropy is expressed, and once, a cup-shaped body having a desired dimensional shape is formed, A portion corresponding to the bottom of the cup is punched by a punch to obtain a target ring-shaped magnet material.
This ring-shaped magnet material is put to practical use as a magnet having radial anisotropy by being magnetized in a subsequent process.

However, since the above-described manufacturing method is a batch system, its productivity is inherently low. In addition, since backward extrusion molding is applied, sufficient processing distortion is not applied to the cylindrical body in the initial stage of molding, and the tip portion molded in the initial stage deteriorates in magnetic characteristics as compared with other parts. Therefore, it is necessary to excise the part for commercialization.
That is, there is a loss due to punching at the bottom, and the yield of products is very low in the above manufacturing method.

In order to solve such a problem, the following magnet material manufacturing method has been proposed (see Patent Document 1).
In this method, a ring-shaped magnet material is manufactured as follows. As shown in FIG. 9, a cylindrical mandrel having a flat end 12a in the through hole 11A of the die 11 in which the through hole 11A having a constant cross section is formed and having a smaller diameter than the through hole 11A. 12 is placed, a compact of magnetic powder is loaded on the mandrel, and the compact is pressed by the press punch 13. The formed body is press-fitted into a gap formed between the mandrel 12 and the die 11. As shown in FIG. 9, when the molded body is formed into the cup-shaped body 14 ′, the pressing punch 13 is pulled up, a new magnetic powder molded body is loaded on the cup-shaped body, and the pressing punch 13 again. Press. In the process in which the newly loaded molded body is plastically processed to be molded into a new cup-shaped body 14 ', the upper-stage cup-shaped body 14' is the lower end of the cup-shaped body 14 'whose upper end is newly molded. It is pushed out downward of the through hole 11A while forming a ring shape in close contact with and connected to the portion.

Therefore, in the case of this manufacturing method, the ring-shaped magnet material 14 is continuously formed by sequentially repeating the above-described operations, and its productivity is high. Then, the punching of the bottom part and the cutting of the tip part, which are performed with respect to individual magnet materials as in the case of the batch method, are unnecessary, and the yield increases accordingly.
JP-A-9-129463

However, the above-described continuous molding method of Patent Document 1 has the following problems.
The first problem is that the connecting portion between the ring-shaped molded body 14 positioned below and the new cup-shaped body 14 'positioned above is formed as shown in FIG.
That is, at the connecting portion, the material of the ring-shaped molded body 14 wraps around from the inside to the outside along the mandrel 12, and the material of the new cup-shaped body 14 ′ wraps around from the outside to the inside along the die 11. The upper end surface of the body 14 and the lower end surface of the cup-shaped body 14 'do not become flat end surfaces orthogonal to the longitudinal direction.

For this reason, it is necessary to cut off the location of the connecting portion from the obtained continuous molded body, which eventually eliminates the effect of eliminating the bottom portion in the batch method and improving the product yield. It ends up.
The second problem is that the degree of design freedom for the required magnetic properties is extremely narrow.

Generally, if a compact of magnet powder as a raw material is processed with a large area reduction rate (processing amount), the magnetic properties of the obtained ring-shaped magnet material are also improved.
However, when this apparatus is used, if the specifications (outer diameter and inner diameter) of the target product are determined, the diameter of the through hole of the die and the diameter of the mandrel are uniquely determined. Therefore, the area reduction rate is also uniquely determined. Therefore, when the target dimension and shape are determined, it is impossible to increase the surface area reduction ratio of the raw material and design the improvement of the magnetic characteristics in the first place.

The third problem is that the manufactured ring-shaped magnet material is likely to be misaligned.
This is because the mandrel disposed in the through hole of the die is relatively long and is used only in a state where the base end portion is supported at one point by a mandrel backup means (not shown). That is, since the mandrel is in a single-point support state, the tip of the mandrel 12 may slightly swing during the process of loading the powder compact onto the tip of the mandrel and the subsequent pressing by the pressing punch 13. As a result, it is considered that misalignment occurs and the dimensional accuracy of the product is lowered.

The fourth problem is that the magnetic characteristics of the manufactured ring magnet are not necessarily high.
Recently, demands for miniaturization and high functionality in electric and electronic devices are increasing, and along with this, for ring magnets incorporated in such devices, for example, (BH) max is 400 kJ / m. ^3. Magnetic characteristics of 1.45T for Br and about 1220 kA / m for iHc are required.

However, it is difficult to manufacture a ring-shaped magnet having such high magnetic properties by the above-described prior art methods. Therefore, there is a need for a new method for manufacturing a ring magnet that further improves the magnetic properties.
The present invention can solve all of the first to third problems described above, and at the same time, by optimizing the dimensional shape relationship between the die and mandrel, it performs effective plastic working on the molded body, An object is to provide a method for producing a ring-shaped magnet material that is superior in magnetic properties compared to the prior art and can solve the above-mentioned fourth problem, and to provide a ring-shaped magnet material obtained by the method.

In order to achieve the above-described object, in the present invention, a first through hole having a hole diameter D _1, a second through hole having a hole diameter D ₂ (where D ₁ <D ₂ ), and the first through hole, From the second through hole of the die having a through hole consisting of a tapered hole located between the second through holes,
Cylindrical tip having a diameter d _1, the diameter d _{2 (however, d 1 <d 2 <D} 2 is a) a cylindrical base portion, and a tapered portion located between said cylindrical distal end portion of the cylindrical proximal portion Insert a mandrel with
After inserting the ring-shaped magnet preform from the first through hole and mounting it on the cylindrical tip of the mandrel, the preform is subjected to plastic working with a press punch having an outer diameter D ₁ and an inner diameter d _1. When manufacturing a ring-shaped magnet material in the gap formed by the through hole of the die and the mandrel,
The values of D ₁ , D ₂ , d ₁ , d ₂ are expressed by the following formula:
0 <(1-D ₁ / D ₂ ) × 100 ≦ 70 (1) and
30 ≦ {1- (D ₂ ² −d ₂ ² ) / (D ₁ ² −d ₁ ² )} × 100 ≦ 94 (2)
A method for manufacturing a ring-shaped magnet material is provided, in which the relationship is set to a value that satisfies the above relationship.

Further, in the present invention, a ring-shaped magnet material that is plastically processed by enlarging both the outer diameter and the inner diameter of a cylindrical preform.
Provided is a ring-shaped magnet material characterized in that the outer diameter enlargement ratio is 70% or less (excluding 0%) and the area reduction ratio is 30 to 94% with respect to the preform. The

According to the present invention, since the mandrel is in a two-point support state during the plastic working of the preform, no runout occurs. Therefore, a ring-shaped magnet material with high dimensional accuracy can be manufactured.
In addition, since a trumpet-shaped gap is formed between the die and the mandrel, the loaded preform is subjected to plastic processing that is squeezed into this gap at the same time as pressing by the pressing punch, and compressive strain and elongation strain Is given. Therefore, the magnetic properties of the obtained ring-shaped magnet material are improved.

In that case, the diameter (D ₁ ) of the first through hole in the die, the diameter (D ₂ ) of the second through hole, the diameter (d ₁ ) of the cylinder tip of the mandrel, and the diameter (d ₂ ) of the cylinder base end By changing each, the width and taper angle in the trumpet-shaped gap can be changed, so that the magnetic characteristics can be changed even if the outer diameter (D ₂ ) of the obtained magnet material is constant. This increases the degree of freedom in designing the magnetic characteristics.

Then, by setting the values of D ₁ , D ₂ , d ₁ , and d ₂ to values that simultaneously satisfy the expressions (1) and (2), for example, (BH) max is 400 kJ / m ³ , Br A ring-shaped magnet material having excellent magnetic properties of about 1.20 T / iHc and about 1220 kA / m can be manufactured.
In addition, since the preformed body has a cylindrical shape, it is difficult for the conventional material to wrap around at the connecting portion with the next molded body, and as a result, the cutting portion at the tip portion is reduced and the yield is reduced. Becomes higher.

FIG. 1 shows an example of a manufacturing apparatus used in the method of the present invention as a conceptual schematic diagram.
The apparatus of FIG. 1 has a die 2 having a through-hole 1 to be described later, a mandrel 3 that is coaxially inserted into the through-hole 1 and arranged there, and a pressing punch 4 for pressing and pressing the preform. Basic configuration.
In Figure 1, although the second through-hole 1 in the vertical direction is formed, the through-hole 1 is provided with a first through-hole 1A of the diameter D _1, the diameter D _{2 (However,} D 1 _<D 2) The second through hole 1B and a tapered hole 1C positioned between the two through holes. Accordingly, the diameter of the upper end of the tapered hole 1C is D _1, the diameter of the lower end has a D _2.

The die 2 has a die portion 2A in which the first through-hole 1A is formed, another die portion 2B in which the second through-hole 1B is formed, and a tapered hole 1C formed between both die portions. It is preferable that the die part 2C is interposed.
Here, as shown in FIG. 1, when the taper angle of the tapered hole 1C is θ ₁ (°) and the taper angle of the tapered portion 3C is θ ₂ (°), the values of θ ₁ and θ ₂ are θ It is designed to meet the ₁ <theta ₂ relationship.

A mandrel 3 is inserted coaxially from the second through hole 1B of the die 2. The mandrel 3 has a cylindrical distal end portion 3A of the diameter d _1, the diameter d _{2 (However, D 2> d 2> d} 1) and the cylindrical base portion 3B of, consists of a tapered portion 3C located therebetween Yes. Therefore, the diameter of the upper end of the tapered portion 3C is d ₁ and the diameter of the lower end is d ₂ .
The height dimension of the tapered portion 3C of the mandrel is set to be the same as the thickness dimension of the tapered hole 1C of the die described above.

The diameter d ₁ of the above-mentioned cylindrical tip 3A is the same as or slightly smaller than the diameter of a through-hole formed in the center of the in-plane of the preform described later. The cylindrical tip 3A can be fitted into the hole.
The mandrel 3 has a cylindrical base end portion 3B connected to a mandrel driving mechanism (not shown), and can be inserted into and removed from the through hole 1 through the second through hole 1B.

The pressing punch 4 is a cylindrical body having an outer diameter that is substantially the same as the diameter (D ₁ ) of the first through hole 1A and an inner diameter that is substantially the same as the diameter (d ₁ ) of the cylindrical tip 3A of the mandrel. The base end portion is connected to a pressure device (not shown), and can be inserted into and removed from the through hole 1 via the first through hole 1A of the die.
In the present invention, a ring-shaped magnet material is manufactured as follows using this apparatus.

First, for example, an Nd—Fe—B-based magnet powder is formed into a green compact by a conventional method, and further subjected to warm pressing to produce a cylindrical preform having a high density.
This preform has a cylindrical body whose outer diameter is substantially the same as or slightly smaller than the diameter (D ₁ ) of the first through hole 1A, and whose inner diameter is substantially the same as or slightly larger than the diameter (d ₁ ) of the cylindrical tip 3A of the mandrel. As molded.

Although it does not specifically limit as magnetic powder to be used, For example, Nd: 20-40 mass%, Fe: 40-70 mass%, Co: 30 mass% or less, B: 0.3-3.0 mass Nb-Fe-B-based ones having a composition of% are preferred.
Next, a mandrel driving mechanism (not shown) is driven to insert the mandrel 3 coaxially into the second through hole 1B of the die 2, and the upper end and lower end of the tapered portion 3C are respectively connected to the upper end and lower end of the tapered hole 1C. The insertion of the mandrel 3 is stopped at the matching position, and the mandrel 3 is placed and fixed at that position.

In this way, in the first through hole 1A, the width is (D ₁ −d ₁ ) / 2 between the cylindrical tip 3A and the wall surface of the first through hole 1A, and the cross-sectional area is ( D ₁ ² −d ₁ ² ) π / 4 annular spaces are formed. Further, in the second through hole 1B, the width is (D ₂ −d ₂ ) / 2 and the cross-sectional area is (D ₂ ² − between the column base end 3B and the wall surface of the second through hole 1B. An annular gap of d ₂ ² ) / 4 is formed.

Between the tapered portion 3C and the tapered hole 1C, the width at the upper end of the tapered portion 3C is (D ₁ -d ₁ ) / 2 and the cross-sectional area is (D ₁ ² -d ₁ ² ) π / 4. A trumpet-shaped gap having a width of (D ₂ −d ₂ ) / 2 and a cross-sectional area of (D ₂ ² −d ₂ ² ) π / 4 is formed at the lower end of the tapered portion 3C.
It should be noted that between D ₁ , d ₁ , D ₂ , and d ₂ , θ ₁ <θ ₂ along with the above-described relationship of D ₁ <D ₂ , d ₁ <d ₂ <D _2. Accordingly, the values of D ₁ , d ₁ , D ₂ , and d ₂ are designed so that the relationship of (D ₂ −d ₂ ) <(D ₁ −d ₁ ) is also established.

Therefore, in the trumpet-shaped gap formed between the tapered portion 3C and the tapered hole 1C, the cross-sectional area at the upper end of the tapered portion 3C is larger than the cross-sectional area at the lower end.
By establishing this relationship (D ₂ -d ₂ ) <(D ₁ -d ₁ ), strain can be imparted during plastic working of the preform.
Next, the preform is inserted into the first through hole 1 </ b> A and loaded into the cylindrical tip 3 </ b> A of the mandrel 3. At this time, since the inner diameter and the outer diameter of the preform 5 are substantially the same as the diameter of the cylindrical tip 3A and the diameter of the first through hole 1A, the preform 5 is indicated by a virtual line in FIG. Thus, it is arranged in the first through hole 1A while being held at the upper end of the tapered portion 3C of the mandrel.

Next, a pressing device (not shown) is driven, and the preform 5 is pressed by the pressing punch 4 as indicated by an arrow to perform plastic working.
At that time, plastic working of the preform 5 with the pressing punch proceeds with the cylindrical tip 3A of the mandrel inserted into the inner diameter portion of the pressing punch 4.
The pressing punch 4 descends in the first through hole 1A with the cylindrical tip 3A of the mandrel as a guide, and finally stops at the upper end of the tapered portion 3C.

In the process, the preform 5 passes through the trumpet-shaped gap formed by the tapered hole 1C of the die 2 and the tapered portion 3C of the mandrel, and the cylindrical base end of the second through-hole 1B of the die and the mandrel. 3B is gradually pushed towards the annular gap to be formed and plastic working in the molded body 5 ₁ as shown in FIG.
At this time, the trumpet-shaped gap described above has the largest cross-sectional area at the upper end and the smallest cross-sectional area at the lower end, so that the preform 5 is narrowed down to an annular shape with a reduced surface area. That is, the deformation process is reliably realized.

In this process, since the mandrel 3 is supported at two points by the mandrel driving device (not shown) on the cylinder base end 3B side and the pressing punch 4, the runout does not occur.
Next, the pressing punch 4 is retracted, and a new preform 5 is loaded into the first through hole 1A of the die, as indicated by the phantom line in FIG. Then, the pressing punch 4 is actuated again to press the molded body 5.

As a result, when the pressing punch 4 is lowered until the upper end of the tapered portion 3C, as shown in FIG. 5, the molded body 5 ₁ of previously been further pushed downward becomes perfectly cylindrical shape, the preform 5 is plastically processed into moldings 5 ₂ having the shape shown in FIG.
In this way, the ring-shaped magnet material is continuously manufactured by repeating the operation of the press punch retreat-loading of a new preform-press press punch.

In the case of the present invention, since the relationship of D ₁ <D ₂ , d ₁ <d ₂ , and (D ₂ -d ₂ ) <(D ₁ -d ₁ ) is established, the loaded preform 5 is In the process in which the gap formed by the taper portion 3C and the taper hole 1C is being pushed out, it is reliably squeezed to accumulate distortion, and undergoes deformation processing in which both the outer diameter and the inner diameter of the preform are expanded. In the process of passing through the gap and passing through the gap formed by the cylindrical base end portion 3B and the second through hole 1B, the state subjected to the deformation processing is always maintained.

Therefore, the magnetic properties of the molded shaped body (ring-shaped magnetic material) 5 ₁ is improved, and since has received also sufficient deformation thereof tip, be suppressed deterioration of the magnetic properties, the prior art Thus, it becomes unnecessary to excise the tip.
Further, since the pre-formed body to be loaded has a cylindrical shape having a through-hole having substantially the same diameter as the diameter (d ₁ ) of the cylindrical tip portion 3A of the mandrel, the material is processed in the process of pressing by the pressing punch 4. It is pushed downwards almost straight.

As a result, in the connecting portion of the molded body 5 ₁ and the next molded body 5 _2, material mutual wraparound phenomenon as shown in FIG. 9 is no longer occur, the end face of each other for coupling in a state orthogonal to the longitudinal direction become.
As shown in FIG. 1, the effect of improving the magnetic characteristics and the effect of suppressing the wraparound phenomenon at the connecting portion are as follows. The taper angle (θ ₂ ) of the taper portion 3C of the mandrel and the taper angle (θ of the taper hole 1C of the die) ₁ ) It is affected by the size. These θ ₁ and θ ₂ are designed in relation to D ₁ , D ₂ , d ₁ , and d ₂ in relation to the magnetic characteristics, but in general in relation to the wraparound phenomenon of the connecting portion, the taper angle θ _1, significantly its effective to reduce the theta ₂ is expressed. For example, when the taper angle θ ₂ of the taper portion 3C is set to about 1 °, the end surfaces of the connecting portions of the molded bodies are connected in a substantially completely flat state (a state orthogonal to each other).

However, reducing the taper angle θ ₂ means that the mandrel 3 becomes very long and the die 2 becomes very thick correspondingly, so in the present invention, the relationship with the effect of improving the magnetic characteristics is shown. Including, it is preferable to set the taper angle θ ₂ of the tapered portion 3C within a range of 20 to 80 °. When this taper angle θ ₂ is greater than 80 °, the decrease in (BH) max at the tip of the product increases, and the wraparound phenomenon as shown in FIG. 9 cannot be ignored. As a result, the number of parts to be excised increases, resulting in a decrease in yield, which is not preferable.

In the case of the present invention, both the outer diameter D ₁ and the inner diameter d ₁ of the preform 5 are expanded, and a molded body 5 ₁ (5 ₂ ) having an outer diameter D ₂ and an inner diameter d ₂ is obtained. . However, the thickness decreases from (D ₁ -d ₁ ) / 2 to (D ₂ -d ₂ ) / 2.
Further, the cross-sectional area decreases from (D ₁ ² -d ₁ ² ) π / 4 of the preform 5 to (D ₂ ² -d ₂ ² ) / 4 of the compact 5 ₁ .

At this time, in the present invention, the outer diameter enlargement ratio (%) of the molded body based on the outer diameter of the preform represented by (1-D ₁ / D ₂ ) × 100 is 0 to 70% ( The area reduction rate (%) represented by {1- (D ₂ ² -d ₂ ² ) / (D ₁ ² -d ₁ ² )} × 100 is 30. The values of D ₁ , d ₁ , D ₂ , d ₂ , and hence θ ₁ , θ ₂ are set to be in the range of ˜94%.

This is because it is difficult to improve the magnetic properties of the obtained ring-shaped magnet material when either the outer diameter enlargement ratio or the area reduction ratio does not satisfy the above-described value.
In particular, when the dimensions of the die 2 and the mandrel 3 are designed so that the outer diameter enlargement ratio is greater than 70% and the area reduction ratio is greater than 94%, not only the problem of magnetic properties but also the pressing of the preform 5 Occasionally, for example, the press punch is broken or the mandrel is burned out.

Incidentally, as shown in FIG. 6, already molded body 5 ₁ plastic working is finished by the pressing punch 4 when loading the next preform 5, during the molding body 5 ₁ a preform 5, For example, it is preferable to interpose an iron annular plate 6.
The annular plate 6 functions as a pressure receiving dummy, thereby preventing the occurrence of fine cracks by adding a back pressure to the molding member 5 _1, 5 _2, increasing the separation of the molded body 5 ₁ and the molded body 5 _2.

In particular, when a ring-shaped magnet material is manufactured for the purpose of picking one piece, this pressure-receiving dummy is suitable. In addition, when manufacturing continuously, this pressure receiving dummy does not need to be interposed at the time of the 3rd and subsequent manufacture.
Further, as shown in FIG. 7, already if plastic working by the press punch charges the next preform 5 on the molded body 5 ₁ ended, chamfered outer peripheral corners of the lower portion of the preform 5 It is preferable to keep it. When plastic working by pressing a punch 4, because the mutual wraparound phenomenon at the junction of the molded body 5 ₁ a preform 5 can be reliably prevented.

Furthermore, as shown in FIG. 8, while the preform 5 and the molded body 5 ₁ shown in FIG. 7, when the still corners of the outer periphery is interposed receiving dummy 6 described above which are chamfered, the connecting This not only prevents the mutual wraparound phenomenon in the part, but also facilitates the mutual separation work.

A plurality of devices having the structure shown in FIG. 1 were assembled by changing D ₁ , d ₁ , D ₂ , and d ₂ as shown in Table 1. Also shown in Table 1 taper angle theta ₁ of the taper angle theta ₂ and the tapered hole 1C of the tapered portion 3C in these devices.
On the other hand, a magnetic alloy consisting of Nd: 29.5% by mass, Co: 5.0% by mass, B: 0.9% by mass, Ga: 0.6% by mass, and the balance substantially consisting of Fe is melted. A magnetic powder having a particle size of 300 μm or less was obtained by rapidly cooling with a roll method to form flakes and then pulverizing. This is designated as magnetic powder A.

In addition, a magnetic alloy consisting of Nd: 30.6% by mass, Co: 6.0% by mass, B: 0.89% by mass, Ga: 0.57% by mass, and the balance substantially consisting of Fe is melted to obtain magnetic properties. In the same manner as for powder A, a magnetic powder having a particle size of 300 μm or less was obtained. This is designated as magnetic powder B.
Magnetic powder A is a raw material powder for a magnet having a high residual magnetization (Br), and magnetic powder B is a raw material powder for a magnet having a high coercive force (iHc).

First, a manufacturing apparatus having the structure shown in FIG. 1 having the dimensional specifications shown in Table 1 was assembled.
On the other hand, each of the magnetic powders described above is compacted in a cold state, and further hot-pressed at a temperature of 800 ° C. and a pressure of 196 MPa in an Ar atmosphere. The dimensions and shapes shown in Table 1 are used in each manufacturing apparatus. A preform was produced.

Subsequently, each preform was loaded into each manufacturing apparatus at a temperature of 800 ° C., and the press punch was operated to continuously form ring-shaped magnet materials having the dimensions shown in Table 2. For each of the obtained ring-shaped magnet materials, the maximum energy product ((BH) max: kJ / m ³ ), residual magnetization (Br: T), and coercive force of the IH curve (iHc: kA / m) were measured.
The results are shown in Table 2 together with the outer diameter expansion rate (%) and the area reduction rate (%) at the time of molding.

From Tables 1 and 2, the following is clear.
Comparing Example 1 and Comparative Example 1 using the same magnetic powder A, Example 1 expands the outer diameter of the preform, and Comparative Example 1 does not increase the diameter of the ring-shaped magnets having the same size and shape. Although the material is molded, the (BH) max of the obtained ring-shaped magnet material is greatly improved although the area reduction rate of Example 1 is smaller than the area reduction rate of Comparative Example 1. Br is also a high value. Similarly, in Example 2 and Comparative Example 2 using magnetic powder B, Example 2 is compatible with Comparative Example 2 in which both iHc and Br are both high.

Thus, according to the present invention, it is possible to manufacture a magnet having excellent magnetic properties in a wide range from a high (BH) max to a high iHc region.
As is clear by comparing Example 1, Comparative Example 1 and Comparative Example 3, even when the dimensional shape of the molded ring-shaped magnet material is the same, the comparison was made by reducing the outer diameter of the preform. Although Example 3 is manufactured with a large reduction in area, its magnetic properties, particularly (BH) max, are inferior to those of Comparative Example 1.

Comparative Example 4 is an example of plastic working with a small area reduction ratio. In this case, iHc holds a value close to the coercive force of the preform before processing, but Br and (BH) max is low and does not reach the value required for the product.
Example 3 is an example in which the present invention is applied to a large product and Example 4 is a small product. In any case, excellent magnetic characteristics are obtained. From this, it can be seen that the present invention is useful as a method for producing a magnet material having excellent magnetic properties in a wide range of dimensions.

Example 5, Comparative Example 5, and Comparative Example 6 are all examples of producing a thin product that is difficult to extrude.
In the case of Comparative Example 5, the extrusion was performed with a surface area reduction ratio of 10% and an outer diameter enlargement ratio of 73%. However, the pressing punch could not withstand the extrusion load, and the extrusion was impossible and the extrusion was impossible.
In the case of Comparative Example 6, the extrusion was performed with a reduction in area of 95% and an outer diameter enlargement ratio of 0%. Unable to follow, mandrel seizure occurred, and extrusion was impossible.

On the other hand, in the case of Example 5, extrusion is performed with a surface area reduction rate of 90% and an outer diameter enlargement ratio of 23%, and the degree of processing of the inner diameter and the outer diameter is dispersed. Extrusion is possible without occurrence, and a magnet material with excellent magnetic properties can be produced.
For this reason, in order to increase the magnetic properties of the ring-shaped magnet material, in particular (BH) max, it is effective to perform molding to increase the inner diameter and outer diameter of the preform used. Recognize.

  In addition, about the obtained continuous molded object, the state of the connection part of each molded object was visually observed. In both the examples and the comparative examples, the connecting end surfaces of the molded bodies were substantially connected to each other, and separation from each other was easy. In addition, the decrease in (BH) max at the extrusion tip was small and was in a range where there was no practical problem.

  According to the present invention, compared with the conventional continuous molding method, it is possible to continuously manufacture a ring-shaped magnet material having excellent magnetic properties and high dimensional accuracy with a high yield, a large degree of design freedom regarding magnetic properties. it can. Therefore, according to this invention, the ring magnet which has the outstanding magnetic characteristic can be manufactured at low cost.

It is the schematic which shows the principal part of this invention apparatus example. It is the schematic which shows the state which loaded the preform of the magnetic powder in the apparatus of this invention. It is the schematic which shows the state which pressed the preform with the press punch. It is the schematic which shows the state which loaded the next new preforming body. It is the schematic which shows the state which pressed the new preforming body. It is the schematic which shows the state which interposed the pressure receiving dummy between the molded object already plastic-processed, and the next new molded object. It is the schematic which shows the state which loaded the new preforming body which chamfered the corner | angular part of the outer periphery. It is the schematic which shows the state which interposed the pressure-receiving dummy between the molded object already plastic-processed, and the next new preforming body shown in FIG. It is the schematic for demonstrating the conventional continuous shaping | molding method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Through-hole 1A 1st through-hole 1B 2nd through-hole 1C Tapered hole 2 Die 2A, 2B, 2C Die part 3 Mandrel 3A Cylindrical tip part 3B Cylindrical base end part 3C Tapered part 4 Press punch 5 Pre-formed body 5 ₁ , 5 ₂ Molded body 6 Ring plate

Claims (6)

A first through hole having a hole diameter D _1, a second through hole having a hole diameter D ₂ (where D ₁ <D ₂ is satisfied), and a tapered hole located between the first through hole and the second through hole. From the second through hole of the die having the through hole,
Cylindrical tip having a diameter d _1, the diameter d _{2 (however, d 1 <d 2 <D} 2 is a) a cylindrical base portion, and a tapered portion located between said cylindrical distal end portion of the cylindrical proximal portion Insert a mandrel with
After inserting the ring-shaped magnet preform from the first through hole and mounting it on the cylindrical tip of the mandrel, the preform is subjected to plastic working with a press punch having an outer diameter D ₁ and an inner diameter d _1. When manufacturing a ring-shaped magnet material in the gap formed by the through hole of the die and the mandrel,
The values of D ₁ , D ₂ , d ₁ , d ₂ are expressed by the following formula:
0 <(1-D ₁ / D ₂ ) × 100 ≦ 70, and
30 ≦ {1- (D ₂ ² −d ₂ ² ) / (D ₁ ² −d ₁ ² )} × 100 ≦ 94
A method for manufacturing a ring-shaped magnet material, wherein the relationship is set to a value that satisfies the above relationship simultaneously. When the taper angle of the taper hole is θ ₁ and the taper angle of the taper portion is θ ₂ , θ ₁ and θ ₂ satisfy the following expressions: θ ₁ <θ ₂ and 20 ° ≦ θ ₂ ≦ 80 °. The manufacturing method of the ring-shaped magnet raw material of Claim 1.   The manufacturing method of the ring-shaped magnet raw material of Claim 1 or 2 which manufactures a ring-shaped magnet raw material continuously in the gap | interval which the said die | dye and the said mandrel form.   The ring-shaped magnet material according to any one of claims 1 to 3, wherein an annular pressure-receiving dummy is inserted between the pressing punch and the preform and plastic processing is performed on the preform while applying back pressure. Production method.   The manufacturing method of the ring-shaped magnet raw material in any one of Claims 1-4 by which the outer peripheral corner | angular part of the said preform is chamfered. A ring-shaped magnet material that is plastically processed by enlarging both the outer diameter and the inner diameter of a cylindrical preform.
A ring-shaped magnet material having an outer diameter enlargement ratio of 0 to 70% and an area reduction ratio of 30 to 94% with respect to the preform.

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