JP3206667B2 - Rare earth bonded magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth bonded magnet used in a rotating electric machine or the like.

[0002]

2. Description of the Related Art Various types of bonded magnets having been relatively inexpensive and having good magnetic properties have been developed. For example, Japanese Unexamined Patent Publication No. Sho 59-2111549 proposes a bonded magnet obtained by solidifying a rare earth-iron-boron magnetic powder with an adhesive.
No. 4 proposes a plastic magnet obtained by mixing a misch metal-transition metal-boron magnetic powder with a binder. Further, JP-A-63-274114 and JP-A-63-287003 disclose rare earth magnets.
A plastic magnet using a mixture of a conductive powder and a ferrite magnetic powder has been proposed.
No. 3 proposes a bonded magnet obtained by mixing rare earth magnetic powders .

[0003] Each of the above-mentioned bonded magnets is obtained by dispersing a magnetic powder in a resin binder by kneading.
No. 3 publication. According to the production method disclosed in the publication, the magnetic powder and the silane-based coupling agent are mixed in a resin binder little by little, and kneading is performed using a mixing roll. The obtained kneaded material is once pulverized and then rolled to form a sheet. The sheet-shaped magnet material is subjected to, for example, a heat treatment with steam to remove a strain generated in a rolling process or to cure by vulcanization.

[0004]

In such a bonded magnet, the present inventors obtained a flexible rare-earth bonded magnet material by dispersing a rare-earth magnetic powder in a flexible resin binder. Thereafter, the magnet material was roll-formed into a sheet shape, and the roll-formed surface of the resulting flexible bonded magnet was magnetized. In this case, if the surface magnetic flux density is excessively increased due to the magnetization, as shown in FIG. 3, the magnetic force of the bond magnet itself causes the magnet 1 to generate cracks 2 and round the ridges 3. Problem that magnet collapse or deformation occurs. This is because the magnetic force exceeds the binder holding force due to the magnetization being performed to the extent that the surface magnetic flux density exceeds the limit value, and the binder can overcome the magnetic force and fix the magnetic powder. It is thought to be gone. On the other hand, when the surface magnetic flux density due to the magnetization on the rolled surface is excessively reduced, the rare earth-transition metal-boron (R-
TB) The utility of using magnetic powder is lost. This is because it is sufficient to use a ferrite-based magnetic powder having a low production cost for a magnet having a low magnetic flux density.

According to the present invention, the ratio of the magnetic force of the bonded magnet itself to the binder coercive force is increased by increasing the filling ratio of the magnetic powder to the entire magnet, and the magnetic powder is weak in resisting repulsion due to the magnetic force of the magnetic powder. Provided is a rare-earth bonded magnet for a motor , which is a rare-earth bonded magnet formed by rolling into a sheet having a high rigidity that does not cause deformation or collapse, and has appropriate flexibility. The purpose is to:

[0006]

According to the present invention, there is provided a rare-earth bonded magnet according to the present invention, wherein a rare-earth-transition metal-boron-based magnetic powder is dispersed in a flexible resin binder by kneading, and a sheet-like material is prepared. In a rare-earth bonded magnet for a motor, wherein at least the above-mentioned roll-formed surface is magnetized, the magnetic powder is blended in an amount of 92 to 96% by weight based on the whole magnet. The above-mentioned rolled surface is used as a magnetized surface, and the magnetized surface of the rolled surface has a magnet with a surface magnetic flux density collapsed from 350 G.
The above magnetic powder can be fixed without fogging 14
It is characterized in that it is performed in the range up to 00G.

[0007]

In the means having such a configuration, the degree of magnetization in the rare earth bonded magnet is adjusted,
The magnetic force in the magnet and the binder holding force are balanced, and a rare-earth bonded magnet having appropriate flexibility and rigidity can be obtained. Then, the magnet is incorporated into a product such as a motor without causing insufficient rigidity and while being satisfactorily bent.

[0008] A more specific configuration of the above means will be described. First, a rare earth-transition metal magnetic powder is obtained by a super-quenching method. An example of the super-quenching method is a jet casting method. In this jet casting method, a magnetic alloy formed in an ingot shape is housed in a saucer, and the alloy is melted by high frequency or the like in an inert environment. The molten magnetic alloy is poured into a basin with a nozzle, and is dropped onto a rotating wheel through the nozzle. The rotating wheel is cooled by water, where rapid cooling takes place. The quenched magnetic alloy is solidified into ribbon-shaped magnetic powder, falls downward, and is collected in a container.

When the rare earth-transition metal based magnetic powder is used, one or more lanthanoids are used as the rare earth, and Fe, Co, or the like is used as the transition metal.
One or more of Ni are used. The rare earth-transition metal-based magnetic powder may contain boron to form a rare earth-transition metal-boron-based (RTB) magnetic powder. Specifically, Nd-Fe-B, Nd-Fe-Co-B, (Nd, Pr) as Nd-Fe-B-based magnetic powders
-Fe-B, (Nd, Pr) -Fe-Co-B and the like are used, and (Ce, L) -Fe-B based magnetic powders include (Ce, L
a) -Fe-B, (Ce, La) -Fe-Co-B, MM-Fe-
B, MM-Fe-Co-B, etc., and further Sm-Co
Sm-Co, Sm-Co-Fe, Sm-
Co-Mn or the like is used.

Next, as shown in FIG. 1, the rare earth-transition metal-boron based magnetic powder is weighed to 55 to 96% by weight based on the whole magnet. The reason why the content of the magnetic powder is set to 96% by weight or less with respect to the entire magnet is that when the filling ratio of the magnetic powder exceeds 96% by weight, the amount of the binder to the magnetic powder becomes insufficient, and the magnetic force of the magnet itself is reduced. The magnet may collapse due to loss of binder strength due to internal stress or internal stress, or the magnet may be too hard to be formed into a sheet shape, or it may not be able to be incorporated into products due to lack of flexibility Because you do. On the other hand, the reason why the magnetic powder is set to 55% by weight or more based on the whole magnet is that if the proportion of the magnetic powder is less than 55% by weight, the magnetic force becomes insufficient, and the usefulness of the rare earth magnetic powder for high magnetic force is useful. Is because there is no longer. At this time, if the magnetic powder is 92% by weight or more based on the whole magnet, the filling ratio of the magnetic powder can be increased to prevent the deformation of the magnet and to obtain the rigidity of the magnet required for assembling the product.

Rare earth-transition metal-boron (RT-
B) When a magnetic powder is used, it is necessary to grind the particle size of the magnetic powder to a fine powder having a median diameter of 78 μm or less in order to obtain the above filling rate. That is, when the particle size of the magnetic powder is set to be larger than the median diameter of 78 μm,
The amount of the magnetic powder relative to the binder, that is, the filler filling ratio is less than a required value, and the amount of the binder relatively increases, and the flexibility of the binder makes the whole magnet easily expand and contract, resulting in insufficient rigidity of the magnet. Therefore, by setting the particle size of the magnetic powder to a median diameter of 78 μm or less to increase the filling ratio of the magnetic powder to a required value or more, the deformation of the magnet is prevented, and the rigidity of the magnet required for assembling the product can be obtained. It is. The adjustment of the magnetic powder is performed using a ball mill, a roll, or the like, and the particle size is, for example, 42 μm.

In addition, since the magnetic properties of the rare earth magnetic powder are good, especially when the required magnetic force of the magnet is set to be small, the amount of the magnetic powder to be introduced is so small that a predetermined filling rate cannot be achieved. There is. In this case, a non-magnetic powder such as white carbon may be added as a reinforcing material together with the magnetic powder in a binder (described later). By using such a mixed filler, the so-called filler filling rate in the magnet can be increased to a required value, thereby improving the deformability of the magnet and increasing the rigidity of the magnet. At this time, the filling ratio of the filler including the magnetic powder and the non-magnetic powder is suitably in the range of 50 to 73% by volume percentage, and among them, rare earth-transition metal-boron (RT)
-B) The magnetic powder is in a range of 13 to 71% by volume, and the mixed filler is in a range of 2 to 60% by volume. As described above, the amount of the binder relative to the magnetic powder (filler) is prevented from being excessive or insufficient, thereby preventing the magnet from collapsing or over-curing.

As the non-magnetic filler, a chemically or physically stable powder such as talc, carbon black, carbon fiber and ferrite powder can be used in addition to the above-mentioned white carbon. The particle size of the mixed filler is 78 μm or less in median diameter. If the particle size of the mixed filler is set to be larger than the median diameter of 78 μm, the filler filling ratio for the binder is lower than a required value, and the amount of the binder is relatively increased more than necessary. The entire magnet easily expands and contracts, causing insufficient rigidity of the magnet. Therefore, when the filler filling rate is increased by setting the particle size of the mixed filler to a median diameter of 78 μm or less, the deformation of the magnet is prevented, and the rigidity of the magnet required for assembling the product can be obtained.

When an Nd-Fe-B-based magnetic powder is used as the magnetic powder, a rare earth-transition metal-boron-based (other than the Nd-Fe-B-based magnetic powder) is used instead of the above-mentioned nonmagnetic mixed filler. (RTB) It is preferable to use magnetic powder. This is because a magnet using the Nd-Fe-B-based magnetic powder has a problem that it is difficult to vulcanize (described later) and it is difficult to obtain necessary rigidity. As the mixed rare earth-transition metal-boron (RTB) magnetic powder in this case,
(Ce, La) -Fe-B, MM-Fe-B, etc. can be adopted. In particular, if (Ce, La) -Fe-B-based magnetic powder, which is easy to vulcanize, is mixed, vulcanization is promoted to the inside of the magnet, and the rigidity of the magnet is increased, and deformation of the magnet can be prevented.

The mixing ratio of the magnetic powders may be any ratio as long as the residual magnetic flux density Br is 2500 G or more and 6300 G or less. If the residual magnetic flux density Br exceeds 6300 G, the magnet strength and internal stress will degrade the binder strength due to the binder strength and cause the magnet to collapse, or the magnet will be too hard to be formed into a sheet. Magnetic flux density Br is 2
If it is less than 500 G, the magnetic flux density becomes too small, and the usefulness of using the rare earth-transition metal-boron (RTB) magnetic powder is lost.

In particular, Nd-Fe-B magnetic powder and (Ce, La)
When mixed with -Fe-B based magnetic powder, (Ce, L
a) If the -Fe-B-based magnetic powder is blended in an amount of 5% by weight or more based on the whole magnetic powder, a predetermined rigidity can be obtained.

It is also possible to increase the filler filling rate to a required value by adding the above-mentioned reinforcing material to a mixture of such magnetic powders. By doing so, the filler filling rate is complemented while suppressing an increase in magnetic force, whereby the deformability of the magnet can be improved and the magnet rigidity can be improved.

Next, a predetermined amount of a rust inhibitor and an epoxy main agent are mixed with the magnetic powder as described above, and an oxide film, an epoxy resin film and a rust preventive film are formed (film forming step). That is, first, an inert gas is injected into the mixing device, and the air in the mixing device is gas-replaced so that the oxygen concentration becomes 0.08 to 3%. As the mixing device, a ball mill, a V-type blender, a double cone type blender, or the like is used. As the inert gas, argon gas
(Ar), nitrogen gas (N ₂ ), carbon dioxide gas (CO ₂ ) and the like are used.

The rare earth-transition metal based magnetic powder, the epoxy main agent, and the rust inhibitor are charged into the mixing apparatus in which the gas replacement has been performed as described above, and the mixing is performed for about 2 hours. In mixing, first, an oxide film is formed on the surface of the magnetic powder by oxygen slightly remaining in the mixing device, and an epoxy resin film and a rust preventive film are further formed thereon. The reason why the oxygen concentration is set to 0.08% to 3% is that if the oxygen concentration is less than 0.08%, an oxide film cannot be formed, or if formed, the oxide film becomes extremely thin. If the concentration exceeds 3%, there is a risk of ignition due to oxygen.

As the epoxy main agent, one or more of bisphenol-based, phenoxy-based, novolak-based, polyphenol-based, polyhydroxybenzene-based or derivatives thereof are used, and as a rust inhibitor, sorbitan monooleate is used. And a mixture of mineral oil and synthetic oil.

The magnetic powder on which the oxide film, the epoxy resin film and the rust preventive film are formed is taken out and weighed,
It is kneaded with a flexible resin binder by a pressure kneader or the like for several minutes (kneading step). At this time, a curing agent and a curing accelerator for the epoxy resin are added. The reason why the curing agent and the curing accelerator are added at this stage is to prevent the magnetic powder from being hardened immediately after the magnetic powder mixture is taken out. By such a kneading step, the rare earth-transition metal based magnetic powder is substantially uniformly dispersed in the flexible resin binder.

At this time, the flexible resin binder includes natural rubber (NR), isoprene rubber (I
R), butadiene rubber (BR), styrene-butadiene rubber (SBR), butyl rubber (IIR), ethylene-propylene rubber (EPR), ethylene-vinyl acetate rubber (EV
A), nitrile rubber (NBR), acrylic rubber (A
R), urethane rubber (UR) and the like are used alone or in combination of two or more. That is, these resin binders are so-called ternary rubbers, and have a rubber component having no polarity (for example, IIR) and a rubber component having strong polarity (for example, NB).
R) is a rubber component containing halogen (for example, CR)
Is well mixed through. Non-polar rubber components have difficulty in oil resistance and weather resistance, and strong polar rubber components are very hard and require the addition of extender oil or plasticizer. Therefore, if both rubber components are mixed via a halogen-containing rubber component, the rubber components that complement the difficulties of each rubber component are easily mixed with each other, and the oil resistance and weather resistance are improved. is there.

The halogen-containing rubber component includes chloroprene rubber (CR), hypalone (CSM),
A material containing chlorine such as chlorinated polyethylene is used alone or in combination of two or more. In this case, the halogen-containing rubber component must be set to 15% by weight or less, preferably 6.2% by weight or less based on the total weight of the resin binder. If the rubber component containing halogen exceeds 15% by weight of the total weight of the resin binder, chlorine gas (Cl ₂ ) or hydrochloric acid gas (HCl) will be generated. This is because it causes corrosion, magnet rust and core rust. The halogen-containing rubber component accounts for 6.2% of the total weight of the resin binder.
If it is contained in excess of% by weight, the magnet becomes too hard and becomes brittle, and cannot be formed into a sheet shape, or has insufficient flexibility to be incorporated into a product. , Easily broken by external force or own magnetic force.

Examples of the curing agent include polyamines such as aliphatic polyamines and aromatic polyamines, acid anhydrides such as phthalic anhydride, polyamide resins, polysulfide resins, amine complexes such as boron trifluoride, and synthetic resins such as phenolic resins. One or more of the precondensates or derivatives thereof are used. As the curing accelerator, one or more of amines such as trisdimethylaminomethylphenol, imidazoles such as 1-isobutyl-2-methylimidazole, and derivatives thereof are used.

In the kneading step, the pressure kneader is cooled, and kneading is performed at a temperature of 95 ° C. or less, preferably 50 to 60 ° C. With this temperature setting,
The risk of ignition in the kneading process is avoided. That is, if the kneading is performed at a temperature exceeding 95 ° C., there is a risk of ignition due to heat generation.

The magnetic material as a kneaded material obtained by the above-described kneading process is taken out from the pressurized kneader and immediately divided into small lots of 10 kg or less. Each of these subdivided magnet materials is sealed and stored in a closed container, and is left as it is until the temperature of the magnet material decreases to room temperature (storage step). The danger of ignition is avoided by the heat radiation in this storage step.

The magnet material as a kneaded material that has been sufficiently radiated by the above preservation step is taken out and has a particle size of 5 mm.
Crushed to the following size (crushing process). In this pulverization process, argon gas (Ar), nitrogen gas (N ₂ ), carbon dioxide gas (CO
₂ ) It is performed under cooling by the flow of an inert gas such as
The temperature condition is set to 95 ° C. or less. A rotary blade or the like is used for crushing. That is, in this pulverization step, air cooling with an inert gas is performed, so that pulverization in the atmosphere is possible.

Then, the pulverized material obtained in the above-mentioned pulverizing step is subjected to rolling by a roll or the like, to obtain a sheet-like bonded magnet (sheet forming step). At this time, the surface temperature of the rolling roll is maintained at 20 to 80 ° C., whereby the tensile strength of the sheet-like magnet material is favorably maintained in a range where it can be wound, and the oxidation of the magnetic powder is suppressed. The deterioration of the magnetic characteristics is prevented.

Rare earth-transition metal-boron system (RT-
B) In the magnet using the magnetic powder, it is necessary to adjust the filler filling ratio of the magnetic powder or the like so that the density of the magnet material after rolling and forming is 4.9 to 5.8. If the density of the magnet is smaller than 4.9, the magnet becomes insufficient in rigidity and easily deformed, making it impossible to incorporate the magnet into a product. If it exceeds, the brittleness of the magnet becomes large, cracks and the like are likely to occur, and there arises a problem that the magnet is broken by the magnetization.

Further, the sheet-like magnet material obtained by the above-mentioned rolling step is subjected to a heat treatment after being preheated. This is because, in the preheating step, moisture, gas and the like unavoidably contained in the sheet-shaped magnet material are radiated to the outside.
The temperature condition and time condition in this preheating step are 30 ° C.
７０70 ° C. and 6 hours or more. At this time, entrainment of air in the sheet-like magnet material is suppressed as much as possible.

On the other hand, the temperature condition and the time condition in the heat treatment step after the preheating are 125 ° C. to 180 ° C. and 60 minutes or more.
The time is set within 80 minutes, and the sheet-shaped magnet material is left for 60 minutes to 180 minutes in a heating device formed by laminating iron plates in, for example, upper and lower three stages, or a thermostat formed of a steam can or the like. Thus, when vulcanization is performed, a predetermined tensile strength is imparted. At this time, the entrainment of air into the sheet-shaped magnet material is suppressed as much as possible in advance. In the case of performing such high-temperature heating, since moisture and gas in the sheet-shaped magnet material are diverted in advance in the above-described preheating step, defects such as air bubbling and the like in the sheet-shaped magnet material during the heating step. Will not occur.

At the time of this heating, the heating temperature is 180 ° C.
By weight, with oxidation of the magnetic powder to lead to deterioration of the magnetic properties becomes remarkable, the heating temperature Ah at 125 ° C. or less
Then, vulcanization does not proceed, and the required tensile strength cannot be obtained.
For the same reason, a heating time of 60 minutes to 180 minutes is required.

The heat-treated sheet-shaped magnet material is cut into an appropriate size to form a sheet-shaped magnet.
The heat treatment is performed again under the condition of 0 minutes. The reheat treatment after cutting promotes vulcanization not only from the original surface but also from the cut surface, thereby increasing the rigidity of the magnet. In this reheat treatment step, the inside of the thermostat is set to an inert atmosphere such as an N ₂ gas atmosphere, so that oxidation of the sheet-shaped magnet material is prevented. If the inside of the thermostat is not made to be an inert atmosphere, a means such as wrapping the periphery of the sheet-shaped magnet material with aluminum foil is applied so that the surface of the sheet-shaped magnet material is not exposed to the atmosphere as much as possible.

The above rare earth-transition metal-boron system (RT)
-B) sheet magnets material with magnetic powder, Shore hardness after reheating D (peak value) and is more than 45 ° <br/> Both tensile strength (pulling rate 50 mm / min) is 4. 5Kg / mm ² or more ing. Magnet having such a hardness and tensile strength are incorporated satisfactorily without causing insufficient rigidity against the motor. That is, the air gap between the core and the magnet changes in the motor.
Is maintained constant without any movement , and the motor characteristics stabilize .
You .

For the same reason, a sheet-like magnet material using the above-mentioned rare earth-transition metal-boron (RTB) magnetic powder has a deflection amount within 60 mm after reheat treatment. Here, the amount of deflection means that the cross-sectional dimension is 2.55 m
The base side 50 mm of a test piece molded to a size and shape of m × 2.45 mm and a length of 205.5 mm was fixed on a horizontal table, and the free end of the test piece was bent by its own weight after 15 seconds. The amount is defined as the amount measured at an ambient temperature of 15-25 ° C. If the heating step described above is not within the range of the temperature conditions described,
Either the magnetic properties decrease (when the temperature exceeds the temperature range) or vulcanization does not proceed (if the temperature falls below the temperature range), resulting in a decrease in hardness, a decrease in tensile strength, and an increase in the amount of deflection.

As shown in FIG. 2, the sheet-shaped magnet 11 obtained by the above-mentioned rolling process using the rare earth-transition metal-boron (RTB) magnetic powder has a roll-formed surface 11a. Alternatively, magnetization is performed on an end surface 11b orthogonal to the roll forming surface 11a. The case where the magnetization is performed on the roll forming surface 11a is, for example, the case where the magnetization is performed as the main magnetization for driving the motor.
The case where the magnetization is performed on 1b is, for example, the case where the magnetization is performed as FG magnetization for motor rotation detection.

At this time, the rolled surface 11a of the magnet is first magnetized in a range where the surface magnetic flux density is in the range of 350 G to 1400 G, and the end face 1 orthogonal to the rolled surface.
For 1b, magnetization is performed in a range where the surface magnetic flux density is 40G to 1400G. In any case of the roll-formed surface 11a and the end surface 11b orthogonal to the roll-formed surface 11a, when the surface magnetic flux density after magnetization exceeds 1400G, the binder in the magnet overcomes the magnetic force. This is because the magnetic powder cannot be fixed and the magnet collapses or the like (see FIG. 3). On the other hand, in the case where the rolled surface 11a is magnetized, if the surface magnetic flux density is 350 G or less, the magnetic flux density becomes too small and rare-earth-transition metal-boron (RTB) magnetic powder is used. Usefulness is lost. This is because a magnet having a low magnetic flux density of 350 G or less is sufficient if ferrite-based magnetic powder with low production cost is used. Also, the roll forming surface 11a
In the case where magnetization is performed on the end face 11b perpendicular to the above, if the surface magnetic flux density is equal to or less than 40 G, the magnetic flux density becomes too small to obtain a required FG waveform.

[0039]

Embodiments of the present invention will be described below in detail. Example 1 As a magnetic powder, Nd-Fe-, which was obtained by pulverizing MQP manufactured by General Motors Co. in advance by a wet ball mill and adjusting the particle size, was used.
B magnetic powder was used. Since this magnetic powder is a magnetic powder having a particle size of 2 mm or less as it is formed by the rapid quenching method,
This was pulverized to a particle size of 78 μm or less.
Rhodol SP-O10 manufactured by Kao Corporation was used as a rust inhibitor, and Epicoat manufactured by Yuka Shell Co., Ltd. was used as an epoxy main agent.
828 was used.

Then, in a ball mill container, magnetic powder,
An epoxy main agent, a rust inhibitor and alumina balls are put in, and the air in the container is replaced with N ₂ gas so that the oxygen concentration becomes 1.2%. A film, an epoxy resin film and a rust prevention film were formed.

Next, the mixture obtained as described above and a rubber binder were kneaded with a curing agent and a curing accelerator in a pressure kneader for 7 minutes. As the curing agent and the curing accelerator, YH-30 manufactured by Yuka Shell Co., Ltd.
2 and IBMI-12 were used.

Further, the obtained kneaded material was subdivided into small lots of 4 kg each and placed in a plastic bag. Thereafter, the mixture is left for an appropriate period of time, and the kneaded material is taken out of the sealed container, and the particle size is about 2.6 m using a crusher.
It was ground to about m. The crusher is U-140 manufactured by Horai Iron Works
A rotary blade type was used.

Rolling was performed while maintaining the surface temperature of the rolling roll used to obtain the sheet at about 50 ° C., to obtain a sheet-like magnet material. Then, after preheating this sheet magnet material under a temperature condition of about 50 ° C. for about 8 hours,
The rubber binder was vulcanized by heating to about 170 ° C.
Then, the sheet magnet was cut into a predetermined size to obtain a flexible sheet-like magnet.

The composition in this example is shown in Table 1 below.

[Table 1] The Nd-Fe-B magnetic powder in the above table is
It is set to 94.92% by weight.

The roll-formed surface of the bonded magnet according to such a blending example was magnetized with each surface magnetic flux density as shown in Table 2 below, and the collapse of the magnet in each case was observed.

[Table 2] As shown in Table 2, the surface magnetic flux density range was 14
It has been found that the magnet collapses due to the magnetic force at the point of time exceeding 00G.

In the kneading step of this embodiment, it was confirmed that according to the above-described blending example, the magnet was not collapsed by the magnetic force, and that a sufficient magnetic force necessary for, for example, a motor could be obtained. Furthermore, in the kneading step of this example, it was confirmed that the activity of the surface of the magnetic powder was reduced by the rust preventive film formed in advance, and that air was hardly entrained in the material. Furthermore, the kneaded material was pulverized to a predetermined small particle size under the flow of an inert gas in the pulverization step, and it was confirmed that almost no air was involved in the subsequent rolling step.

In the rolling step, the surface of the rolling roll was maintained at a predetermined temperature, so that the tensile strength of the sheet-like magnet was maintained well within a range in which it could be wound up, and the oxidation of the magnetic powder was suppressed, and the magnetic properties were reduced. Did not occur.

In the next high-temperature heating, it was confirmed that the sheet-like magnet material did not cause problems such as air foaming. If the heating temperature exceeds 180 ° C,
Oxidation of the magnetic powder became remarkable, leading to deterioration of magnetic properties. At a heating temperature of 125 ° C. or lower, vulcanization did not proceed, and a predetermined tensile strength could not be obtained.

Further, in this embodiment, the epoxy resin is put into the mixing step and mixed, and the epoxy resin coating is formed on the magnetic powder. Therefore, the entrapment of air is further reduced. Similar functions and effects were obtained by adding the epoxy resin in the kneading step.

The magnetic properties of the magnet obtained according to this embodiment are as follows: Br = 5.6 [KG], iHc = 9.9 [kOe], bHc = 4.5 [k]
Oe], (BH) max = 6.4 [MGOe]. When the obtained magnet was left in an atmosphere of 60 ° C. and 90% RH for 80 hours, no rust was observed on the surface. D with brush
When used as a driving magnet for C motor,
Even after the continuous rotation for 00 hours, no corrosion occurred on the brush material (Ag-Pd) and the commutator material (Ag-Cd).

[0051] As Example 2 Magnetic powder, and rapidly quenched ribbon by _{MM 14 (Fe 0. 9 Co} 0. 1) 79 B 7 becomes alloy composition of the single roll method, a material obtained by particle size control was pulverized by a wet ball mill Using. As a rust preventive, a mixed solution of Leodol SP-O10 manufactured by Kao Corporation and Anderol 456 manufactured by Tenneco Chemical Company, USA was used. Thereafter, a sheet-like flexible magnet was obtained in the same manner as in Example 1 described above.

In the magnet according to this embodiment, it was found that the magnet collapses due to the magnetic force when the surface magnetic flux density exceeds 1400 G.

Also in the kneading step according to this example, it was confirmed that the activity of the surface of the magnetic powder was reduced by the rust preventive film formed in advance, and that air was hardly entrained in the material. Further, the kneaded material was pulverized to a predetermined small particle size in a pulverizing step under the flow of an inert gas, so that almost no air was involved in the subsequent rolling step.

Further, also in the rolling step, the surface temperature of the rolling roll was maintained at a predetermined value, and a predetermined tensile strength was obtained. Further, the oxidation of the magnetic powder was similarly suppressed, and the magnetic characteristics did not deteriorate. Even in the next high-temperature heating, there was no problem such as air bubbling in the sheet-like magnet material.

The magnetic properties of the magnet obtained in Example 2 were as follows: Br = 4.7 [KG], iHc = 7.0 [kOe], bHc = 3.
1 [kOe] and (BH) max = 4.1 [MGOe]. Further, when the obtained magnet was left in an atmosphere of 60 ° C. and 90% RH for 80 hours, no rust was observed on the surface. When used as a driving magnet for a DC motor with a brush,
Brush material (Ag-Pd) even after continuous rotation at 200 ℃ for 200 hours
And no corrosion occurred in the commutator material (Ag-Cd).

As described above, it was confirmed that the sheet-like flexible bonded magnet according to the present invention was suitably attached to a rotating electric machine and used. If a metal powder having a high magnetic permeability such as an iron powder or an iron alloy is used instead of the permanent magnet powder, a flexible high magnetic permeability material can be formed.

[0057]

As described above, in the flexible rare earth bonded magnet according to the present invention, the magnetic powder is applied to the entire magnet in an amount of 92 to 90%.
96% by weight, the filling ratio of the magnetic powder is high, the ratio of the magnetic force of the bonded magnet itself to the binder holding power is high, and the magnet is liable to collapse. has been rolled formed into a sheet is a weak shape in combating repulsion by the magnetic force has a necessary and sufficient force for use in motor and in the range of surface magnetic flux density which does not cause the collapse 350-1
Magnetization was performed so as to be in the range of 400G .
For this reason , it is possible to prevent the magnet from collapsing that would make it impossible to commercialize it while maintaining the flexibility of the magnet, and to obtain a very useful rare earth bonded magnet for a motor .

[Brief description of the drawings]

FIG. 1 is a flow chart showing a manufacturing process of a rare-earth bonded magnet according to the present invention.

FIG. 2 is an external perspective explanatory view showing a magnet rolled into a sheet.

FIG. 3 is a perspective explanatory view showing the appearance of a bond magnet collapsed by magnetization.

[Explanation of symbols]

 11 Bond magnet 11a Roll forming surface 11b Rolling orthogonal surface

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hirotaka Sakamaki 14-888 Ako, Komagane-shi, Nagano Co., Ltd. Sankyo Seiki Seisakusho Komagane Plant (56) References JP-A-60-146313 (JP, A) JP-A-2-110904 (JP, A) JP-A-61-87304 (JP, A) JP-A-3-151604 (JP, A) JP-A-1-103806 (JP, A) JP-A-3-165504 (JP) , A) JP-B 47-34191 (JP, B1)

Claims (1)

(57) [Claims] A rare earth-transition metal-boron magnetic powder is dispersed in a flexible resin binder by kneading and roll-formed into a sheet, and is magnetized at least on the roll-formed surface. In the rare earth bonded magnet for a motor, the magnetic powder is blended in an amount of 92 to 96% by weight based on the whole magnet, and the rolled surface is used as a magnetized surface, and the rolled surface is magnetized. Indicates that the surface magnetic flux density caused the magnet to collapse from 350 G
The above magnetic powder can be fixed without fogging 14
A rare-earth bonded magnet, which is performed in a range up to 00G.