JPH06330102A - Method for compacting magnet powder in magnetic field and manufacture of magnet - Google Patents

Abstract

PURPOSE:To manufacture a rare earth magnet in which the reduction in the magnetic characteristic due to the defective orientation, etc., can be prevented from occurring, by subjecting a magnet powder contg. a rare earth element and a transition element to 'magnetic field compacting' while providing the surface of each of the punches with a ferromagnetic body having a specified thickness and applying a magnetic field to the magnet powder. CONSTITUTION:The magnet powder 6 contg. R (an element selected from the rare earth elements including Y) and a transition element is subjected to 'magnetic field compacting' in the space between the upper and lower punches 4 and in a magnetic field having its component in the axial direction of the above punches 4 which is effected by the coils 2. At this time, the surface of each of the upper punch 4 and/or lower punch 4 is provided with a ferromagnetic body 5. The total thickness of the ferromagnetic bodies 5 in the above axial direction (Lm) is selected so as to meet the following relational expressions: (CL-Lc)>=Lm>=1 mm, CL>=(Lm+Lc)>20mm and 20>=Lc>=1mm, wherein CL is the effective length of the coil 2 and Lc is the thickness of the compact out of the magnetic powder 6. As the above ferromagnetic body 5, that having >=10000G saturation magnetization (Bs) is preferred. Further as the above magnetic field, a pulsed magnetic field, the applying direction of which is almost identical to the applying direction of the compacting pressure and which has >=20kOe field strength and 10mus to 0.5s duration time, is preferred.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of molding a rare earth magnet and a method of manufacturing a rare earth magnet.

[0002]

2. Description of the Related Art As a rare earth magnet having high performance, an Sm-Co type magnet manufactured by powder metallurgy has an energy product of 32M.
GOe's are in mass production. In recent years, Nd-Fe
-B magnets and RTB-based magnets such as Nd-Fe-Co-B magnets (R is at least one kind of rare earth element including Y and T is Fe or Fe and Co) have been developed. Japanese Patent Application Laid-Open No. 59-46008 discloses a sintered magnet. Further, in recent years, R-TN magnets and the like have also been actively developed.

When manufacturing these anisotropic magnets, a magnetic field molding method is used as a molding method. At this time, in order to improve the residual magnetic flux density of the anisotropic magnet, it is important to improve the degree of orientation during magnetic field molding. If the degree of orientation is high, the squareness is improved and the magnetizability is also improved.

In order to improve the degree of orientation, a method of increasing the applied magnetic field strength during magnetic field shaping is adopted. But,
It is difficult to apply an extremely large magnetic field because the heat generation of the magnetic field generation coil becomes large. Therefore, a method of applying a high magnetic field by utilizing a pulsed magnetic field having a short magnetic field application time has been proposed (Japanese Patent Laid-Open No. 61-208809). When applying a high magnetic field such as the pulsed magnetic field,
Generally used punches and dies are made of non-magnetic material,
This is placed in the air core coil.

The inventors of the present invention, in Japanese Patent Application No. 4-72581, apply a high pulse magnetic field for orientation, and when the relative density of the magnet powder compact is within the range of 25 to 55%. We have proposed a method of applying a pulsed magnetic field at least three times. By this method, the degree of orientation is improved and a magnet having a high residual magnetic flux density can be obtained. However, when a die and upper and lower punches are arranged in the air-core coil, and so-called longitudinal magnetic field molding is performed in which a magnetic field is applied in the punch axis direction to perform magnetic field molding, even if such a high pulse magnetic field is applied,
It was found that when trying to obtain a compact having a small thickness in the axial direction of the upper and lower punches, the magnetic properties such as the residual magnetic flux density became extremely low and it could not be put to practical use.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to form a magnetic powder containing the above R and a transition element between upper and lower punches in a magnetic field having a component in the upper and lower punch axis directions. It is an object of the present invention to provide a molding method in which deterioration of magnetic properties due to poor orientation or the like is obtained when obtaining a molded body for a rare earth magnet that is thin in the direction, and a method of manufacturing a magnet using the molding method.

[0007]

These objects are achieved by the present invention described in (1) to (8) below. (1) When magnetic field molding of magnet powder containing R (R is at least one kind of rare earth element including Y) and a transition element between upper and lower punches in a magnetic field having this upper and lower punch axial component On the punch surface of the upper punch and / or the lower punch, the total thickness Lm in the axial direction is (CL−Lc) ≧ Lm ≧ 1 mm and CL ≧ (Lm + Lc)> 20 mm (CL applies a magnetic field. Is the effective length of the coil used for the above, and Lc is the thickness in the axial direction after the molding of the magnet powder) is arranged, and a magnetic field is applied and pressed by the upper and lower punches. A magnetic powder magnetic field molding method for obtaining a molded body of ≧ 1 mm. (2) The magnetic field molding method for magnet powder according to (1), wherein the ferromagnetic material has a saturation magnetization Bs of 10000 G or more. (3) The magnetic powder magnetic field molding method according to (1) or (2), wherein the applied direction of the magnetic field is substantially the same as the applied direction of the molding pressure. (4) The magnetic field molding method for magnet powder according to any one of (1) to (3), wherein the magnetic field has an intensity of 20 kOe or more. (5) The magnetic field molding method for magnet powder according to any of (1) to (4), wherein the magnetic field is a pulsed magnetic field having a duration of 10 μs to 0.5 sec. (6) For the magnet according to (5), the pulsed magnetic field applies the pulsed magnetic field at least three times to the molded body when the relative density of the molded body of the magnet powder is within the range of 25 to 55%. Magnetic field forming method of powder. (7) The magnet powder is an RTB-based magnet powder (T
Is Fe or Fe and Co. ), The magnetic field molding method of the magnet powder according to any one of the above (1) to (6), which is either the R-Co magnet powder or the R-TN magnet powder. (8) A method for producing a magnet molded by the method according to any one of (1) to (7) above.

[0008]

[Operation and effect] When a magnetic field is applied by the coil using the air-core coil type molding apparatus, the demagnetizing field generated in the magnet powder in the coil reduces the orientation effect of the magnet powder due to the applied magnetic field and is obtained. The magnetic characteristics of the magnet are deteriorated.

Such an effect of the demagnetizing field is caused by the punch,
It depends on the shape of the cavity between the dies, and generally the cavity thickness between punches, that is, the thinner the thickness of the compact in the vertical punch axial direction, the larger. Therefore, in the present invention, a ferromagnetic material is arranged on at least one punch surface of the punch to be used, and the thickness of the magnetic material in the cavity is apparently increased. Therefore, it is possible to reduce the influence of the demagnetizing field generated in the magnet powder on the orientation of the magnet powder, and it is possible to prevent the deterioration of the magnetic characteristics due to the orientation failure.

In Japanese Unexamined Patent Publication No. 61-272915, in manufacturing an anisotropic permanent magnet, press molding is performed in the presence of a pulsed magnetic field using a punch of which at least one of the upper and lower sides is a ferromagnetic material. A method is disclosed. The purpose of using the ferromagnetic punch is to move / pressurize the ferromagnetic punch by a magnetic attraction force by an applied pulse magnetic field to form the punch. However, such punch suction is not preferable because it is difficult to control the molding pressure, the molding density cannot be made constant, and the shape variation after sintering becomes large.

[0011]

Specific Structure The specific structure of the present invention will be described in detail below.

The magnetic field molding method of the present invention is applied to a magnet powder containing R (R is at least one kind of rare earth element containing Y) and a transition element.

The composition of the magnet powder is not particularly limited as long as it contains a rare earth element and a transition element, but in the present invention, an RTB-based magnet (T is Fe or Fe and Co)), R-Co type magnet or R-T-N type magnet.

In the R-T-B type magnet powder, R is usually 2
7-38 wt%, T 51-72 wt%, B 0.5-
It is preferable to contain 4.5% by weight. If the R content is too low, a phase rich in iron precipitates and high coercive force cannot be obtained, and if the R content is too high, high residual magnetic flux density cannot be obtained. If the B content is too small, a high coercive force cannot be obtained, and if the B content is too large, a high residual magnetic flux density cannot be obtained. The amount of Co in T is preferably 30% by weight or less. Further, in order to improve the coercive force, Al,
Cr, Mn, Mg, Si, Cu, C, Nb, Sn, W,
Elements such as V, Zr, Ti and Mo may be added,
If the added amount exceeds 6% by weight, the residual magnetic flux density will decrease.

In addition to these elements, the magnet powder may contain carbon and oxygen as unavoidable impurities or trace additives.

The magnet powder having such a composition has a main phase having a substantially tetragonal crystal structure. It usually contains a non-magnetic phase in a volume ratio of about 0.5 to 10%.

The method for producing the magnet powder is not particularly limited, but it is usually produced by casting a mother alloy ingot and crushing it, or by crushing the alloy powder obtained by the reduction diffusion method. The average particle size of the magnet powder is usually 1 to
It is about 10 μm.

The R-Co type magnet powder is composed of R, Fe and N.
at least one metal selected from i, Mn and Cr, and C
contains o and. In this case, preferably, in addition to the above, Cu or Nb, Zr, Ta, Hf, Ti and V
Containing at least one metal selected from among the above, particularly preferably Cu, Nb, Zr, Ta, Hf, and T in addition to the above.
and one or more metals selected from i and V.
Among them, intermetallic compounds of Sm and Co, preferably SmCo ₅ intermetallic compounds and Sm ₂ Co ₁₇ intermetallic compounds are the main phases, and particularly Sm ₂ Co ₁₇ intermetallic compounds are the main phases. It is preferable that the main phase has a substantially rhombohedral crystal structure. When the Sm ₂ Co ₁₇ intermetallic compound is used as the main phase, the grain boundary has a subphase mainly composed of the SmCo ₅ system. The specific composition may be appropriately selected according to the production method, required magnetic properties, etc., but preferable composition examples in the case of using, for example, an Sm ₂ Co ₁₇ intermetallic compound as the main phase are shown below.

R: 20 to 30% by weight, particularly about 22 to 28% by weight, one or more of Fe, Ni, Mn and Cr: 1
~ 35 wt%, one or more of Nb, Zr, Ta, Hf, Ti and V: 0-6 wt%, especially 0.5-4 wt%
%, Cu: 0 to 10% by weight, particularly about 1 to 10% by weight, Co: balance.

Specific examples of the rare earth element include, for example, Y, La, Ce, Pr, Nb, Sm, Eu, Gd,
Examples thereof include Tb, Dy, Ho, Er, Tm, Yb and Lu, and it is particularly preferable that Sm and / or Ce are contained.

Further, as one or more kinds of Fe, Ni, Mn and Cr, Fe is preferable, and particularly, it is preferable to contain Fe and optionally one or more kinds of Ni, Mn and Cr.

Further, Zr is preferable as one or more of Nb, Zr, Ta, Hf, Ti and V. Particularly, Zr is contained and, if necessary, one or more of Nb, Ta, Hf, Ti and V is contained. Is preferred.

In addition to the above elements, Si,
One or more of other elements such as Mo, Ca, O, and C can be added to the total 3
You may add about less than weight%. Note that these may be contained as impurities in an amount of about 3% by weight or less based on the whole.

The method for producing the R-Co magnet powder is not particularly limited. The average particle size of the magnet powder is usually 1 to 20.
It is about μm.

The R-T-N magnet powder contains R, N and T.

R is Sm alone or one or more of Sm and other rare earth elements. Examples of rare earth elements other than Sm include Y, La, Ce, Pr, Nd, and E.
u, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu
Etc. If the amount of rare earth elements other than Sm is too large, the crystal magnetic anisotropy decreases, so the content of rare earth elements other than Sm is preferably 70% or less of R. The content rate of R is
It is 5 to 15 atom%, preferably 7 to 14 atom%. R
If the content is less than the above range, the coercive force will decrease, and if it exceeds the above range, the residual magnetic flux density will decrease.

The N content is 0.5 to 25 atom%, preferably 5 to 20 atom%. In the present invention, a part of N may be replaced with C and / or Si. In this case, the N content is 0.5 atomic% or more,
The total content of N, C and Si is 25 atomic% or less. If the N content is less than the above range, the Curie temperature is not sufficiently increased and the saturation magnetization is not improved enough. If the total content of N, C and Si exceeds the above range, the residual magnetic flux density is reduced. C and / or Si contained in place of a part of N exhibits an effect of improving saturation magnetization, coercive force and Curie temperature. The lower limit of the total content of C and Si is not particularly limited, but if the total content is 0.25 atom% or more, the above-mentioned effects are sufficiently exhibited.

The Curie temperature of the magnet is about 430 to 650 ° C. although it depends on the composition.

The balance is substantially T. T is Fe, or Fe and Co, and the content of Fe in T is preferably 20 atom% or more, and more preferably 30 atom% or more.
When the content of Fe in T is less than the above range, the residual magnetic flux density decreases. There is no particular upper limit to the Fe content in T, but if it exceeds 80 atomic%, the residual magnetic flux density tends to decrease.

The element M contained in the mother alloy is contained in the magnet.
Alternatively, elements other than the above, such as Mn, Ni, and Zn, may be contained, and elements such as B, O, P, and S may be contained.

The magnet has a Th ₂ Zn ₁₇ type rhombohedral crystal structure as a main phase.

The method for producing the R-T-N magnet powder is not particularly limited as long as it is a commonly used method. The average particle size of the magnet powder is usually about 1 to 10 μm.

Next, the molding process will be described with reference to FIG.
The example shown in FIG. 1 is an example for explaining the present invention, and the structure and the like are not particularly limited as long as so-called pressurizing direction and applied magnetic field direction are substantially parallel to each other as long as longitudinal magnetic field molding is performed.

According to the present invention, there is provided a molded body having a thickness (punch 4, 4 pressing direction thickness) Lc of the magnet powder 6 after molding at the time of magnetic field molding of a magnet using the rare earth magnet powder of 20 mm ≧ Lc ≧ 1 mm. To get it. Lc is a value obtained by dividing the volume of the magnet powder 6 after molding by the area of the punch surface, and the area of the punch surface in this case is the projected area. When Lc is larger than this range, the influence of the demagnetizing field and the like on the orientation is almost eliminated, and the effect of the present invention is almost eliminated.
Also, molding with a thickness less than the above is practically impossible.

In the present invention, the forming apparatus 1 is provided with the punches 4 and 4 in which the ferromagnetic material 5 is arranged on at least one punch surface of the upper and lower punches 4 and 4. In this case, the punches 4, 4 having the ferromagnetic material 5 only on the top or bottom
, The punch 4 having the ferromagnetic bodies 5 and 5 on the upper and lower sides,
4 may be used.

The total thickness Lm of the ferromagnetic bodies 5, 5 arranged is
When the effective length of the coil 2 used for applying the magnetic field installed in the molding apparatus 1 is CL, (CL−Lc) ≧
Lm ≧ 1 mm.

If Lm is in this range, it is sufficient to cancel the influence of the demagnetizing field, and if Lm is too short, the effect of the present invention will be lost. Further, if it is too long, improvement in magnetic properties based on the orientation of the obtained magnet cannot be expected, and it becomes difficult to control the molding pressure due to the force of attracting the ferromagnetic bodies 5, 5 generated by the magnetic field, and the shape of the magnet Variations tend to be large.

Further, the sum of Lc and Lm is CL ≧ (L
c + Lm)> 20 mm. If Lc + Lm is shorter than this range, orientation failure tends to occur due to the influence of the demagnetizing field,
Further, if it is too long, improvement in magnetic properties based on the orientation of the obtained magnet cannot be expected.

In the present specification, the effective length CL of the coil used for applying the magnetic field is the length from one end of the winding portion of the coil 2 in the punch axis direction to the other end. .

In the present invention, the ferromagnetic material used for the ferromagnetic bodies 5 and 5 forming a part of the punch has a saturation magnetization Bs of 1000.
It is possible to use die steel or cemented carbide of 0 G or more. As the ferromagnetic material, the higher the saturation magnetization Bs is, the more preferable. However, in the case of a commonly used material, it is about 15,000 G or less.

Saturation magnetization B of the material used for the ferromagnetic bodies 5 and 5
If s is lower than the above value, the magnetic field is magnetically saturated by the high magnetic field applied, and the influence of the demagnetizing field generated in the magnet powder 6 cannot be reduced.

Further, since the ferromagnetic bodies 5 and 5 constitute at least a part of the punch, it is preferable that the hardness value on the C scale in the Rockwell hardness test has a strength of about HRC 40 or more. preferable.

These ferromagnetic materials are integrated with the punch 4 by a method such as brazing.

In the molding apparatus 1 used in the present invention, the ferromagnetic bodies 5 and 5 are usually provided on the entire punch surface of the punches 4 and 4 made of a non-magnetic material, but if necessary, only a part of the punch surface is provided. Can also be a ferromagnetic material. When only a part of the punch surface is made of a ferromagnetic material, the area ratio between the ferromagnetic material 5 and the non-magnetic material portion and the shape of the punch surface of the ferromagnetic material 5 may be arbitrary.

Further, these punch surfaces do not necessarily have to be perpendicular to the magnetic flux direction generated by the applied magnetic field. That is, by forming these surface portions and the ferromagnetic material into various shapes, for example, the magnetic flux direction of the magnetic field applied to the magnet powder 6 can be changed, and control such as partially changing the orientation direction can also be performed. It is easily possible. Also, the joint surface between the ferromagnetic body 5 and the punch 4 does not necessarily have to be a flat surface. In these cases, the thickness Lm of the ferromagnetic bodies 5 and 5 is a value obtained by dividing the total volume of the ferromagnetic bodies by the punch area, and the punch area in this case is the projected area.

The magnetic powder 6 used for magnetic field molding is usually preferably substantially only the above-mentioned magnetic powder when a molded body for forming a sintered magnet is molded, for example, because it is a bonded magnet. When molding the molded body of (1), it is usually preferable to mix the magnetic powder 6 with an epoxy-based or phenol-based resin in advance and disperse the resin, and then perform magnetic field molding. The mixing amount of these resins is 1 to
5% by weight is preferred.

In the present invention, the application direction of the applied magnetic field is
It is preferable to be substantially parallel to the pressure application direction for molding described later. In the so-called transverse magnetic field forming method in which the magnetic field applying direction and the pressure applying direction are substantially orthogonal to each other, in the forming apparatus having the punches 4 and 4 having the ferromagnetic bodies 5 and 5 of the present invention, the magnet powder of the demagnetizing field generated by the magnetic field application It is impossible to prevent the influence on the orientation of.

In the present invention, the strength of the magnetic field applied for orientation during molding using the punches 4 and 4 having such ferromagnetic materials 5 and 5 is preferably 20 kOe or more, more preferably 30 kOe. That is all.

As a method of applying such a high magnetic field, it is preferable to use a pulsed magnetic field. When a pulsed magnetic field is applied a plurality of times and the pulsed magnetic field is applied a plurality of times, the pulsed magnetic field is at least once, and preferably all of the pulsed magnetic fields are within the above range. If the strength of the applied magnetic field is less than the above range, the orientation of the magnet powder 6 tends to be insufficient. In addition,
Although there is no particular upper limit to the strength of the applied magnetic field, it is usually 50 because the size of the magnetic field generator becomes large and there is almost no improvement in the orientation degree even when the strength exceeds 50 kOe.
kOe or less.

When a pulsed magnetic field is used, the duration is usually preferably about 10 μs to 0.5 sec.
If the duration is less than the above range, the orientation tends to be insufficient, and if it exceeds the above range, the heat generation of the magnetic field applying coil 2 tends to be too large. In this specification, the duration is the time from the start to the end of the magnetic field application.

The interval for applying the pulse magnetic field is not particularly limited.

The molding pressure may be constant from the start to the end of molding, may be gradually increased or decreased, and may be irregularly changed. There is no particular limitation on the molding pressure. The lower the molding pressure is, the better the orientation is. However, when the molding pressure is too low, the strength of the molded product is insufficient, which causes a problem in handling. Therefore, it is usually preferably about 0.5 to ⁴ ton / cm ^2. .

In the present invention, when the pulsed magnetic field is applied at the time of molding, there is no particular limitation as long as it is within the above conditions,
By satisfying the following conditions, the effect of orientation increases.

That is, when the relative density of the compact of the magnet powder 6 is within the range of 25 to 55%, preferably 30 to 45%, the pulse magnetic field under the above conditions is applied to the compact at least three times. In this specification, the relative density is a percentage of a value obtained by dividing the measured density by the theoretical density. The measured density is calculated from the weight of the magnet powder 6 filled in the molding space of the molding apparatus 1 and the internal volume of the molding space.

The pulse magnetic field applied when the relative density of the compact is outside the above range has a low contribution to the improvement of the orientation degree of the magnet powder 6. Therefore, the number of pulsed magnetic fields applied is 3
If the pulsed magnetic field is not applied at least three times when the relative density of the compact is within the above range,
A sufficient degree of orientation cannot be obtained.

Further, the pulse magnetic field may be applied at least three times while increasing the density of the compact, or the pulse magnetic field may be applied at least three times while keeping the density of the compact substantially constant.

Further, the magnetic field may be applied even when the relative density of the molded body is out of the above range. That is, a pulse magnetic field, a steady magnetic field, an intermittent magnetic field, etc. may be applied before and / or after applying the pulse magnetic field in the density range.

The final relative density of the molded body, that is, the relative density of the molded body is usually about 50 to 60%. Further, there is no limitation on the plane size, shape, etc. of the molded body.

The molded body obtained as described above is sintered as described later to form a sintered magnet, or the molded body which is magnetically molded after previously mixing the resin or the like is subjected to a curing treatment or the like. And make it a bond magnet.

There are no particular restrictions on the various conditions during sintering of the sintered magnet, but it is, for example, 0.5 at 1000 to 1250 ° C.
It is preferable to sinter for about 12 hours, particularly for about 1 to 5 hours, and then quench. The sintering atmosphere is preferably vacuum or a non-oxidizing gas atmosphere such as Ar gas. Further, after the sintering, an aging treatment, a magnetizing treatment and the like are performed if necessary.

[0061]

EXAMPLES The present invention will be described in more detail below by showing specific examples of the present invention.

Example 1 The composition was 31.0 Nd-1.5 Dy-68.5 Fe-1.
A 0B (wt%) alloy ingot was made by casting. This alloy ingot was roughly crushed to-# 32 by a jaw crusher and a brown mill, and then finely crushed by a jet mill to obtain a magnet powder 6 having an average particle diameter of 4 µm.

A part of the molding apparatus used has the structure shown in FIG. The mold part of this device is a die 3 made of non-magnetic material.
And a punch 4 and 4 made of non-magnetic metal and having a ferromagnetic material 5 in a part and the rest being 3.2 cm × 3.2 cm in a plane perpendicular to the magnetic flux direction generated by the applied magnetic field. It has a molding space (cavity) of area. CL = 1
It is 20 mm.

Punches 4 and 4 with a die steel having a saturation magnetization (Bs) of 12 kG and a thickness of 10 mm as the ferromagnetic bodies 5 and 5.
(That is, Lm is 20 mm) and the punches 4 and 4 having no ferromagnetic materials 5 and 5 are used to obtain the thickness (Lc) of the magnet powder 6 after molding as shown in Table 1. The amount was changed to fill the molding space, and magnetic field molding was performed under the following conditions.

The magnetic field molding conditions were that the applied pressure was 1 ton / cm ² , the applied strength of the pulse magnetic field at the center of the molding space was 30 kOe, and the relative density of the magnet powder was 30 to 45%.
In the meantime, the pulsed magnetic field was applied 6 times. The final density of the obtained molded body was 53% as a relative density. In addition,
In order to obtain the measured density, the required internal volume of the molding space is
It was calculated from the moving amount of the punch 4. The theoretical density is 7.
It was set to 62 g / cm ² .

The molded body thus obtained was treated with 110
Vacuum sintering was performed at 0 ° C. for 2 hours, and aging treatment was performed to obtain a sintered magnet. The magnets obtained were molded with punches 4 and 4 equipped with a die steel having Bs of 12 kG. Sample Nos. 1 to 6
And the residual magnetic flux density (Br) in the orientation direction was measured using samples punched with punches 4 and 4 having no ferromagnetic material as sample numbers 7 to 12. The results are summarized in Table 1. The display unit was kG.

[0067]

[Table 1]

From Table 1, Bs is 1 as the ferromagnetic materials 5 and 5.
In samples Nos. 1 to 6 using punches 4 and 4 equipped with a die steel of 2 kG, Br was not decreased even when Lc ≦ 20 mm. On the other hand, in Sample Nos. 7 to 12 using the punches 4 and 4 having no ferromagnetic materials 5 and 5, the magnetic characteristics were deteriorated when Lc ≦ 20 mm. Therefore, when Lc ≦ 20 mm, the designed magnetic properties cannot be obtained, and when the molding method of the present invention is not used, it is necessary to take measures such as changing the composition.

Comparative Example 1 In the ferromagnetic materials 5 and 5, a magnetic cemented carbide having a saturation magnetization Bs of 6 kG and a thickness of 10 mm was used instead of the die steel used in Example 1, and the other examples were used. In the same manner as in 1, magnetic field molding, sintering and aging treatment were performed to obtain a sintered magnet. Br of the obtained magnet was measured in the same manner as in Example 1. As a result, in the sample with Lc ≦ 20 mm, the result that the magnetic characteristics were deteriorated was obtained similarly to the sample numbers 7 to 11.

Example 2 The composition was 26.0 Sm-15.0Fe-7.0Cu-2.
5Zr-Bal. An alloy ingot of Co (wt%) was created by casting. The alloy ingot was crushed using a brown mill and a jet mill to obtain a magnet powder 6 having an average particle size of 4 μm.

This magnet powder 6 was provided with punches 4 and 4 (that is, Lm is 20 mm) and ferromagnets 5 and 5 which were made of die steel having Bs of 12 kG and a thickness of 10 mm as ferromagnets 5 and 5. Using the punches 4 and 4 which were not provided, Lc was changed as shown in Table 2 using the apparatus of Example 1, and magnetic field molding was performed under the following conditions.

The magnetic field molding conditions were an applied pressure of 3 ton / cm ² and the same magnetic field as in Example 1 was applied to obtain a molded body. This molded body was sintered at 1200 ° C. for 1 hour in an Ar gas atmosphere and subjected to an aging treatment to obtain a sintered magnet. About the obtained magnet, punches 4 and 4 with die steel having Bs of 12 kG
Samples Nos. 13 and 15 using
Br was measured using Samples Nos. 14 and 16 in which punches 4 and 4 not including No. 5 were used. The results are summarized in Table 2. The display unit was kG.

[0073]

[Table 2]

From Table 2, even in the R-Co type magnet, the magnet using the molding method of the present invention showed no deterioration of the magnetic characteristics when Lc≤20 mm, and the effect of the present invention was recognized.

Example 3 A magnet powder 6 having a composition of 24.0Sm-72.5Fe-3.5N (wt%) and an average particle size of 2 μm was prepared.

Epoxy resin was mixed with this magnet powder 6 so as to be 3% by weight, and Bs was 12 as the ferromagnetic materials 5 and 5.
Using punches 4 and 4 (that is, Lm is 20 mm) provided with die steel having a thickness of 10 mm and a thickness of 10 mm and punches 4 and 4 having no ferromagnetic materials 5 and 5, Lc was obtained by the same apparatus as in Example 1.
Was changed as shown in Table 3, magnetic field molding was performed under the same conditions as in Example 1, and a curing treatment was performed to obtain a bonded magnet. Of the obtained magnets, punches 4 and 4 having die steel having Bs of 12 kG were used as sample numbers 17 and 19,
Br using the punches 4 and 4 having no ferromagnetic material was measured as sample numbers 18 and 20. The results are shown in Table 3.
Are shown together. The display unit was kG.

[0077]

[Table 3]

From Table 3, also in the R-T-N magnet,
In the magnet using the molding method of the present invention, the magnetic characteristics were not deteriorated when Lc ≦ 20 mm, and the effect of the present invention was confirmed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a part of a molding apparatus having an example of a preferable punch used in a molding method of the present invention.

[Explanation of reference numerals] 1 molding device (part) 2 coil 3 die 4 punch 5 ferromagnetic material 6 magnet powder

Claims (8)

[Claims] 1. Magnetic field forming in a magnetic field having an upper and lower punch axial component magnetic powder containing R (R is at least one rare earth element including Y) and a transition element between upper and lower punches. In this case, the total thickness Lm in the axial direction is (CL-Lc) ≧ Lm ≧ 1 mm and CL ≧ (Lm + Lc)> 20 mm on the punch surface of the upper punch and / or the lower punch (CL applies a magnetic field). The effective length of the coil used for this purpose, and Lc is the thickness in the axial direction after the magnet powder has been molded.), A magnetic field is applied and pressed by the upper and lower punches, 20 mm A magnetic powder magnetic field molding method for obtaining a molded body of ≧ Lc ≧ 1 mm. 2. The ferromagnetic material has a saturation magnetization Bs of 100.
The magnetic field molding method for magnet powder according to claim 1, which has a magnetic field strength of at least 00G. 3. The magnetic powder magnetic field molding method according to claim 1, wherein the magnetic field has an application direction substantially coinciding with a molding pressure application direction. 4. The magnetic field molding method for magnet powder according to claim 1, wherein the magnetic field has an intensity of 20 kOe or more. 5. The magnetic field has a duration of 10 μs to 0.
The magnetic field molding method for magnet powder according to any one of claims 1 to 4, wherein the pulsed magnetic field is 5 sec. 6. The magnet according to claim 5, wherein the pulsed magnetic field applies the pulsed magnetic field to the compacted body at least three times when the relative density of the compacted body of the magnet powder is within the range of 25 to 55%. Magnetic field molding method for powders. 7. The magnet powder is an RTB-based magnet powder (T is Fe or Fe and Co), R—.
The magnetic field molding method for magnet powder according to any one of claims 1 to 6, which is either a Co magnet powder or an RTN magnet powder. 8. A method for manufacturing a magnet molded by the method according to claim 1.