JP2014090125A - Iron yoke integrally fitted outer rotor and manufacturing method of magnet therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an iron yoke integrally fitted outer rotor magnet which has reliability such as high dimensional accuracy at an actual use temperature of an outer rotor or high weather resistance in an outer rotor magnet in which an annular iron yoke and an annular rare earth-iron based bond magnet are integrally fitted.SOLUTION: The manufacturing method includes: a first step of manufacturing an annular green compact containing a rare earth-iron based magnet foil, a thermosetting resin composition which is a solid at the normal temperature, and a residual cavity through compression molding; and a second step of inserting the annular green compact inside of an annular iron yoke, heating the green compact to expand an outer diameter of the annular green compact through thermal expansion of the thermosetting resin composition constituting the annular green compact, bringing an outer circumferential surface of the annular green compact and an inner circumferential surface of the annular iron yoke into a restricted state at a predetermined position before initiating a two-dimensional crosslinking reaction of the thermosetting resin composition, and thermally hardening the thermosetting resin composition constituting the annular green compact in the restricted state into an annular bond magnet.

Description

  The present invention relates to a method for manufacturing an iron-yoke integral fitting outer rotor magnet using a magnetically isotropic annular rare earth-iron-based bonded magnet widely used in small motors. More specifically, a compression molding is used to form a high-mechanical strength, low-springback annular green compact comprising a rare earth-iron-based magnet flake, a thermosetting resin composition that is solid at room temperature, and residual voids. The outer peripheral surface of the annular green compact before gelation of the thermosetting resin composition constituting the annular green compact by inserting and heating the annular green compact inside the annular iron yoke in step 1 And a second step of constraining (adhering) the inner peripheral surface of the annular iron yoke at a predetermined position, and gelling and thermosetting the thermosetting resin composition in the constrained state to form a bonded magnet. The present invention relates to a method for manufacturing an iron rotor integrated fitting outer rotor magnet.

An outer rotor magnet using a magnetically isotropic annular rare earth-iron bond magnet widely used for a small motor is manufactured as follows, for example. First, a nanocrystalline ribbon having an average crystal grain size of 60 nm or less obtained by rapidly solidifying an Nd ₁₂ Fe ₇₇ Co ₅ B ₆ (atomic%) molten alloy having an alloy composition close to the stoichiometric composition of Nd ₂ Fe ₁₄ B The magnet flakes crushed are compressed into a predetermined shape together with a thermosetting resin composition such as an epoxy resin to produce an annular green compact. Next, the annular green compact is heated, and the epoxy resin composition in the green compact is thermoset to obtain an annular bonded magnet. If necessary, after subjecting the annular bond magnet to surface treatment, the outer peripheral surface of the annular bond magnet is bonded and fixed to the inner peripheral surface of the annular iron yoke, thereby obtaining an outer rotor magnet. In addition to the above, various methods have been proposed, such as using a thermoplastic resin composition such as nylon instead of the thermosetting resin composition, or creating a bonded magnet by injection molding instead of compression molding. ing. In general, the clearance between the outer circumferential surface of the annular bonded magnet and the inner circumferential surface of the annular iron yoke is usually 20 to 30 μm.

  By the way, the annular rare earth-iron-based bonded magnet used for the outer rotor as described above is used to compensate for the rotational movement of the outer rotor and the decrease in the permeance coefficient as the outer rotor is made thinner. It is necessary to increase the dimensional accuracy such as roundness, cylindricity, and coaxiality of the inner surface of the bond magnet facing the iron core. Many improvements and proposals have heretofore been made for improving the dimensional accuracy of the inner surface of the outer rotor magnet.

  For example, using a springback (elastic recovery phenomenon) of a molded body (annular green compact) produced by compression molding, there is a technique for integrally fitting an annular iron yoke and an annular bonded magnet without using an adhesive. It has been proposed [Patent Document 1]. Specifically, a step of arranging a ring-shaped yoke having an inner diameter equal to or larger than the outer diameter of the cavity near the opening of the mold cavity, and a step of compressing the compound filled in the cavity; And a step of taking out the molded body formed by compressing the compound from the opening of the cavity, press-fitting into the ring-shaped yoke, and integrating (integrated fitting) using a spring back, and the integrated ring-shaped iron There has been proposed a technique for manufacturing a yoke-integrated rare earth bonded magnet by a process in which a heat treatment is performed on the yoke and the molded body to cure the thermosetting resin in the molded body to form a bonded magnet.

International Publication No. 2006/001304 Pamphlet

By compressing and thermosetting the Nd-Fe-B magnet flakes together with an epoxy resin or the like, the volume fraction of the magnet flakes of the annular bonded magnet is 80.5 vol. %, And at this time, the residual void was 11 vol. % Is known to exist.
Since the residual void tends to increase the amount of spring back in the green compact before hardening and the bonded magnet as the amount increases, in the case of the technique disclosed in Patent Document 1, an appropriate amount The residual void amount seems to work favorably at the time of integrally fitting the yoke and the bonded magnet.
However, the residual voids are a factor that decreases the mechanical strength of the green compact. In the technique of Patent Document 1, when a thin molded body (annular green compact) having a thickness of 1 mm or less obtained by compression molding is taken out from an opening of a cavity, for example, and simultaneously press-fitted into a ring-shaped yoke, a residual void amount With the increase in the thickness, cracks, breakage, deformation of the annular green compact, or adhesion of foreign matters to the annular green compact (granular compound leaking around the mold) is likely to occur. Therefore, the residual void can be an unstable factor that hinders the stabilization of the quality of the molded body when the molding operation is performed on an industrial scale, and as a result, the yield in magnet manufacturing is reduced.

Further, it is known that the rare earth-iron-based bonded magnet according to the present invention has a magnetic flux loss that does not recover even if it is exposed to a high temperature for a long period of time and then returned to room temperature and re-magnetized. This is generally called permanent demagnetization. Regardless of the production method such as injection molding, compression molding, etc., rare earth-iron-based bonded magnets have a linear correlation between the volume fraction of the residual voids of the magnet and permanent demagnetization. Also decreases. The main cause of such permanent demagnetization is that oxygen, moisture, etc. taken into voids (that is, residual voids) inside the magnet promote structural changes such as oxidation and corrosion of the magnet flakes inside the magnet. ing. That is, an increase in residual air gap can lead to an increase in permanent demagnetization.
In addition, an annular green compact with a large residual void amount, that is, a springback amount, means that when the green compact is released from the cavity, the frictional force on the outer peripheral surface of the green compact also increases. Magnet flakes present in the vicinity of the outer peripheral surface of the annular green compact serving as a press-fitting surface with the iron yoke are easily exposed on the outer peripheral surface. For this reason, oxygen, moisture, etc. present in the outer peripheral surface of the bonded magnet (fitting surface) or in the residual voids in the vicinity of the magnet after being integrally fitted with the annular iron yoke in the subsequent heat treatment are also present in the exposed magnet flakes. Promotes structural changes such as oxidation and corrosion.
As described above, the residual air gap may seriously affect the maintenance and securing of the reliability of the integrally fitted outer rotor magnet, such as dimensional stability, mechanical strength, and irreversible magnetic flux loss after long-term high temperature exposure.

The present invention has been made in view of such circumstances, and is intended for a method for manufacturing an outer rotor magnet. The purpose of the present invention is as a residual magnet Mr and a bond magnet used for an outer rotor magnet. Bond magnet with high performance as a magnet and high dimensional accuracy and weather resistance by reducing the residual gap of the bond magnet while maintaining the maximum energy product (BH) _max level at the original magnet flake level In particular, in the glass state of the thermosetting resin cured material that becomes the binder in the bonded magnet, the linear expansion coefficient of the annular iron yoke in a close contact state and the linear expansion coefficient of the annular bonded magnet with almost no residual void The reliability of high dimensional accuracy and high weather resistance at the actual operating temperature of the outer rotor, such as long-term high-temperature exposure and low-temperature exposure. The manufacturing method of the iron rotor integral fitting outer rotor magnet which has the property is provided.

As a result of intensive studies in order to achieve the above object, the present inventors have adopted a bonded magnet having a very small amount of residual voids as a magnet material in an iron yoke-integrated outer rotor magnet,
In addition, a configuration in which the yoke and the bonded magnet have substantially the same linear expansion coefficient was examined. And the volume fraction of the rare earth-iron-based magnet flakes is 80 vol. %, And the amount of residual voids is extremely small. At the curing point of the thermosetting resin composition constituting the bonded magnet, the linear expansion coefficient of the cyclic bonded magnet, the liquid phase of the curing transient, and After the thermosetting treatment is performed until the linear expansion coefficient of the annular iron yoke brought into close contact with the magnet becomes almost equal before the start of the two-dimensional crosslinking reaction, the annular bond is brought into close contact with the annular iron yoke by returning to room temperature. It has been found that the magnets can achieve substantially the same linear expansion coefficient in the actual operating temperature range. And it discovered that it became an iron yoke integrated outer rotor magnet which has high dimensional accuracy and a weather resistance by actual use temperature by such structure, and completed this invention.

That is, the present invention provides a first step of producing an annular green compact comprising a rare earth-iron-based magnet flake, a thermosetting resin composition that is solid at room temperature, and residual voids by compression molding, and an annular iron yoke. By inserting and heating the annular green compact inside, the outer diameter of the annular green compact is expanded by the thermal expansion of the thermosetting resin composition constituting the annular green compact, and the thermosetting Before starting the two-dimensional crosslinking reaction of the conductive resin composition, the outer peripheral surface of the annular green compact and the inner peripheral surface of the annular iron yoke are constrained at predetermined positions, and in the constrained state, And a second step of thermosetting the thermosetting resin composition constituting the annular green compact to form an annular bonded magnet.
In the above manufacturing method, the annular green compact obtained in the first step has a volume fraction of rare earth-iron-based magnet flakes of 80 vol. % And the volume fraction of residual voids is 3 vol. The thermosetting resin composition is preferably composed of less than% and the balance being solid at room temperature.
Moreover, in the obtained iron yoke integral fitting outer rotor magnet, it is preferable that the linear expansion coefficient of the cyclic bond magnet in which the cured thermosetting resin composition is in a glass state is 12 × 10 ⁻⁶ ° C. ⁻¹ or less. .

  In the first step, a granule-shaped composite magnet material containing a thermosetting resin composition and a rare earth-iron-based magnet flake is filled in a mold cavity, and the temperature is equal to or lower than the melting point of the granule-shaped composite magnet material. By applying uniaxial pressure to the granular composite magnet material, the residual voids are reduced by the brittle fracture of the magnet flakes and the interaction with the plastic deformation (flow) of the thermosetting resin composition. At the same time, it is preferable that the granular composite magnetic material is laminated in the pressure axis direction to produce an annular green compact in which the positional relationship between the magnet flakes is substantially fixed.

  Further, the thermosetting resin composition comprises a unsaturated polyester resin having fluidity with yield stress that is a completely dissolved product of an unsaturated polyester alkyd and an allylic copolymerizable monomer, an organic peroxide, In this case, it is preferable that the allylic copolymerizable monomer is triallyl isocyanurate.

On the other hand, the rare earth-iron-based magnet flakes according to the present invention include R-Fe-B-based magnets, R-Fe (Co) -B-based magnets in which part of Fe is substituted with Co, and further R-Fe. -B-M-based magnet or R-Fe (Co) -B- M -based magnet,, _R 2 _Fe 14 _B having the alloy composition consisting of unavoidable _{impurities, R 2 Fe (Co) 14} B nanocrystalline structure, or a αFe R ₂ Fe _{14 B,} nanocomposite texture (the R and R 2 Fe _{(Co) 14} B represents any rare earth element selected Ce containing Y, Pr, Nd, Gd, Tb, of Dy and Ho Wherein M represents one or a combination of two or more selected from Si, Al, Nb, Zr, Hf, Mo, Ga, P and C). A rapidly solidified flake is preferred.
Alternatively, the rare earth-iron-based magnet flakes are Sm ₂ Fe ₁₇ Nx (x≈3) nanocrystals having an alloy composition consisting of an Sm—Fe—N magnet, an Sm—Fe—M′—N magnet, and inevitable impurities. Nanocrystalline, or nanocomposite of αFe and Sm ₂ Fe ₁₇ Nx (x≈3), where M ′ is Hf, Zr, Si, Nb, Ti, Ga, Al,
It is preferably a magnetically isotropic rare earth-iron rapidly solidified flake containing one or a combination of two or more selected from Ta and C).

The annular green compact obtained in the first step preferably has a crushing strength of 20 MPa or more.
And in the obtained iron yoke integral fitting outer rotor magnet, it is preferable that an annular bond magnet has a thickness of 1 mm or less.
The annular bonded magnet preferably has a residual magnetization Mr of 0.74 T or more and a maximum energy product (BH) _max of 90 kJ / m ³ or more in an external magnetic field Hm of 2.4 MA / m.

  And this invention is an outer rotor type | mold provided with the outer rotor magnet which integrally fits the iron yoke integral fitting outer rotor magnet obtained by the above-mentioned manufacturing method, ie, the rare earth-iron type bonded magnet on the inner diameter side of the rotor yoke. Motor rotors are also targeted.

  According to the manufacturing method of the present invention, the thermal expansion of the thermosetting resin composition constituting the annular green compact is performed by inserting and heating the annular green compact as a bond magnet inside the annular iron yoke. The outer peripheral surface of the annular green compact and the inner peripheral surface of the annular iron yoke are brought into close contact (restraint), and an iron yoke integrated outer rotor magnet in which the annular iron yoke and the annular bond magnet are integrally fitted in this constrained state is manufactured. can do. For this reason, the contact area of an annular iron yoke and an annular bond magnet can be increased, and the fitting force between the two can be increased.

Further, according to the manufacturing method of the present invention, the volume fraction of the magnet material (magnet flake) is set to 80 vol. The residual air gap can be reduced while maintaining the level of the residual magnetization Mr and the maximum energy product (BH) _{max at} a high level while maintaining the ratio higher than%. The reduction of the residual void amount leads to suppression of the elastic recovery phenomenon (spring back) of the annular bond magnet and improvement of the crushing strength, and an annular bond magnet having high dimensional accuracy can be obtained. For this reason, the obtained annular iron yoke integrated fitting outer rotor magnet can improve the dimensional accuracy in terms of coaxiality and the like, and a state where the clearance between the yoke and the bond magnet is constant (a substantially zero state) can be ensured.
Furthermore, the reduction of the residual air gap can also reduce the residual air gap remaining on the outer peripheral surface (surface) of the annular bond magnet, thereby increasing the real contact area between the inner peripheral surface of the annular iron yoke and the outer peripheral surface of the annular bond magnet. The fitting force can be further improved.
Moreover, the reduction of residual voids leads to a decrease in moisture, oxygen, etc. that can exist in the residual voids, which is the main cause of permanent demagnetization, and it can suppress the corrosion and structural changes of rare earth magnet materials due to these components. The durability (namely, weather resistance) of the bonded magnet can be improved.

  Furthermore, according to the manufacturing method of the present invention, in the obtained annular iron yoke integrated outer rotor magnet, in the glass state of the cured product of the thermosetting resin composition constituting the annular bond magnet, the annular bond magnet and the annular iron The linear expansion coefficient of the yoke can be made substantially equal. For this reason, the fitting state in the joint surface of an iron yoke and a bonded magnet can be maintained favorably, and the true contact area on the fitting surface can be maintained in an increased state as compared with the prior art.

  As described above, the annular iron yoke-integrated outer rotor magnet obtained by the manufacturing method of the present invention can maintain and ensure its performance over a long period of time at the actual use temperature including high temperature exposure and low temperature exposure. .

FIG. 1 is a conceptual diagram showing changes in the outer diameter of the thermosetting resin composition contained in the annular green compact during the curing transient. FIG. 2 is a characteristic diagram showing the relationship between the volume fraction Va of the residual void and the volume fraction Vm of the magnet flakes with respect to the volume fraction Vr of the thermosetting resin composition. FIG. 3 is a characteristic diagram showing a change in the clearance between the annular green compact (annular bonded magnet) and the annular iron yoke during the curing transition of the thermosetting resin composition.

Hereinafter, the present invention will be described in more detail.
The present invention relates to a method for manufacturing an outer yoke magnet integrated with an iron yoke, and specifically, an annular iron yoke and an annular bond magnet constituting the magnet are in close contact without using an adhesive, and the annular The present invention relates to a method of manufacturing an iron yoke integrated fitting outer rotor magnet in which the linear expansion coefficients of the iron yoke and the annular bonded magnet are substantially equal in the actual use temperature range.

[First step]
This step is a step of manufacturing an annular green compact (green compact) that is the basis of the bonded magnet.
First, for the green compact according to the present invention, a conventional granular composite magnet material, for example, an alloy composition Nd ₁₂ Fe ₇₇ Co ₅ B ₆ (atomic%) close to the stoichiometric composition of Nd ₂ Fe ₁₄ B A magnet material composed of a magnet flake (density 7.59 Mg / m ³ ) obtained by rapidly solidifying the alloy and an epoxy resin composition that is solid or liquid at room temperature is filled into a mold ring cavity and compression molded. The following description is based on the viewpoint of the difference from the obtained green compact.

Conventional granule composite magnet materials (magnet flakes) using conventional thermosetting resin compositions (such as epoxy oligomers that are solid at room temperature) cause brittle fracture when filled with cavities and then subjected to compression pressure. , While separating, the surrounding gaps are filled and densification proceeds. At the same time, some of them rotate to be stacked in the pressure axis direction. Here, the positional relationship between the granules (magnet flakes) becomes almost stable. Of course, if the compression pressure is small, the degree of brittle fracture and gap filling of the granules (magnet flakes) will be small, and the density of the green compact (green compact) will also be small.
After that, at the stage where the compression pressure is released and the green compact is released from the mold cavity, the granules (magnet flakes) with an angle in the pressure axis direction, which is basically in the elastic range, are returned to their original positions. When the phenomenon of rotating to return occurs, generally the released green compact exhibits an elastic recovery phenomenon (spring back).
2 wt. % Of a composite magnet material containing about 1% epoxy resin is compressed at a pressure of about 1 GPa, and the volume fraction of the magnet flakes is 80 vol. %, The spring back is about 0.4% and the residual voids are 8 to 11 vol. %.

On the other hand, in the present invention, in order to reduce the residual void of the annular green compact, instead of a conventional thermosetting resin composition containing an epoxy resin as a binder for the magnet material, at a temperature below the melting point of the composition. One characteristic is that a resin composition having a property of causing plastic deformation (flow) due to a pressure exceeding the yield stress, that is, a property of causing Bingham flow (flow with yield stress) is employed.
For this reason, in the first step of the present invention, for example, an alloy composition Nd ₁₂ Fe ₇₇ Co ₅ B ₆ (atomic%) close to the stoichiometric composition of Nd ₂ Fe ₁₄ B is rapidly cooled and solidified. 7.75Mg / m ³ ) and a thermosetting resin composition having the above-mentioned properties are filled with a predetermined amount of granulated composite magnet material in a mold ring cavity by a conventional method, and the composite magnet material is uniaxially loaded. A pressure higher than the yield stress of the thermosetting resin composition is applied. Then, in the composite magnet material according to the present invention, in the initial stage of densification transient (compression), the granules are brought into close contact with each other. Subsequently, at the same time as the brittle fracture of the magnet flakes contained in the granule, Causes deformation (flow), which expands the contact surface of adjacent granules, reduces the gap, and at the same time causes a part of the granules (magnet flakes) to rotate and stack in the pressure axis direction Become. Here, the positional relationship between the granules (magnet flakes) is almost stable and fixed. As a result, a green compact with very little residual voids can be obtained.
In the first step of the present invention, such a densification action occurs in a densification transient (compression). Therefore, for example, in an annular green compact that is compression-molded at about 1 GPa, the residual voids can easily be 3 vol. % Or less.

  As the thermosetting resin constituting the thermosetting resin composition having flowability with yield stress as described above according to the present invention, the completion of unsaturated polyester alkyd and allylic copolymerizable monomer is completed. Examples thereof include unsaturated polyester resins that are solutes. And the thermosetting resin composition concerning this invention contains the said unsaturated polyester resin and the organication oxide used as the polymerization initiator in the case of heat-hardening.

  The thermosetting resin composition is preferably an unsaturated polyester alkyd (A) that is solid at room temperature and is not sticky, has a melting point of 80 to 120 ° C. and an acid value of 20 or less, and a melting point of 30 ° C. or less. The thermosetting resin composition comprised including the complete solution with an allylic copolymerizable monomer (B) and an organic peroxide can be mentioned.

  The above-mentioned unsaturated polyester alkyd (A) which is solid at ordinary temperature and has no tackiness, and has a melting point of 80 to 120 ° C. and an acid value of 20 or less comprises a dicarboxylic acid component and a glycol (diol) component.

The dicarboxylic component is preferably composed of phthalic acid and fumaric acid, and phthalic acid or a derivative thereof and fumaric acid are used as raw materials. In the following description, the term “phthalic acid” includes the meaning of “phthalic acid or a derivative thereof”. For example, if maleic anhydride or maleic acid is used instead of fumaric acid, a granular composite magnet material having no tackiness at room temperature and excellent blocking resistance cannot be obtained.
The use ratio of phthalic acid / fumaric acid is preferably 5/5 to 1/9, particularly 4/6 to 2/8 (molar ratio).

The glycol component is preferably 1,4-butanediol alone, or 1,4-butanediol and other glycols in combination. At this time, the ratio of 1,4-butanediol / other glycol is preferably 7/3 to 10/0, more preferably 8/2 to 9.5 / 0.5 (molar ratio).
Other glycol components used in combination with 1,4-butanediol include ethylene glycol, propylene glycol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, 1, 5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-3-hydroxypropyl, 2,2-dimethyl-6,3-hydroxypropionate, hydrogenated bisphenol A, ethylene oxide or propylene of bisphenol A An oxide adduct can be mentioned. Here, propylene glycol, neopentyl glycol, or dipropylene glycol can be preferably used as the other glycol component.

Here, even if the molar ratio of diphthalic acid component phthalic acid / fumaric acid is in the range of 5 / 5-9 / 1, the molar ratio of 1,4-butanediol / other glycol as the glycol component is 7 / If it is smaller than 3 (1,4-butanediol molar ratio exceeds 7), a granular composite magnet material having no tackiness at room temperature and excellent in blocking resistance cannot be obtained.
Further, even if the molar ratio of 1,4-butanediol of the diol component / other glycol is in the range of 7/3 to 10/0, the molar ratio of terephthalic acid / fumaric acid which is the dicarboxylic acid component is 5/5. When larger (molar ratio of phthalic acid exceeds 5) or smaller than 1/9 (molar ratio of phthalic acid is less than 1), there is no stickiness at room temperature and excellent blocking resistance Although a granular composite magnet material can be obtained, the thermal and mechanical properties of the annular bonded magnet obtained later are not sufficient.

  The unsaturated polyester alkyd (A) according to the present invention preferably has a melting point of 80 to 120 ° C. When the melting point is lower than 80 ° C., not only does it become a granular composite magnet material having no stickiness at room temperature and excellent blocking resistance, but even a homogeneous granular composite magnet material cannot be obtained. In addition, when the melting point is higher than 120 ° C., a granular composite magnet material having no stickiness at room temperature and excellent in blocking resistance can be obtained, but plastic deformation (fluidity) at 1 GPa or less at room temperature, that is, Bingham flow (flow with yield stress) is reduced, which is not preferable.

  Examples of the allyl copolymerizable monomer (B) according to the present invention include bifunctional monomers such as diallyl isophthalate, diallyl terephthalate and diallyl orthophthalate, or triallyl isocyanurate which is a triazine ring compound. A trifunctional monomer etc. are mentioned. These can be used singly or in combination of two or more, it is possible to adjust the fluidity with yield stress.

In general, the copolymerizable monomer is classified into a monomer having a vinyl group (CH ₂ ═CH—) and a monomer having an allyl group (CH ₂ ═CH—CH ₂ —). In the latter monomer, the allyl group is stabilized by the resonance structure even when activated by the peroxide radical as a polymerization initiator (degenerate chain transfer reaction˜R · + CH ₂ ═CH—CH ₂ − X → ~ RH + C
_{H 2 = CH- · CH-X⇔} · CH 2 -CH = CH-X), a chain reaction of the polymerization reaction is inhibited. By this resonance action, the monomer having an allyl group is inactive in the normal temperature range, which is advantageous in the storage stability at normal temperature of the green compact (bonded magnet material before curing) to be prepared later. In addition, all of the allyl copolymerizable monomer has a high vapor pressure and hardly volatilizes. From these points, the use of an allylic copolymerizable monomer as the copolymerizable monomer constituting the unsaturated polyester resin provides a granular composite magnet material with excellent storage stability at room temperature. It is done.

Further, the crosslink density of the cured product of the thermosetting resin composition is increased to increase the glass transition temperature, and the linear expansion coefficient of the bonded magnet in which the cured product is in the glass state is approximately the same as the linear expansion coefficient of iron. In order to secure a certain value of about 12 × 10 ⁻⁶ ° C.− ¹ , the volume fraction of the magnet flakes is set to 80 vol. It is preferable to use triallyl isocyanurate which is a trifunctional monomer having a triazine ring as the allyl copolymerizable monomer.

  The ratio (concentration) of the unsaturated polyester alkyd (A) and the allylic copolymerizable monomer (B) was B / (A + B) = 5 to 40 wt. %. For example, the concentration of the allylic copolymerizable monomer (B) is 5 wt. If it is less than%, a non-adhesive granular composite magnet material can be obtained, but the plastic deformability (flow) at 1 GPa or less at normal temperature is lowered (bingham fluidity is reduced), which is not preferable. The concentration of the allylic copolymerizable monomer (B) is 40 wt. If the ratio exceeds 50%, the crushing strength (rigidity) of the annular green compact (green compact) to be prepared later is lowered, which is not preferable.

An organic peroxide can be illustrated as a polymerization initiator contained in the thermosetting resin composition concerning this invention. Examples of the organic peroxide include methyl ethyl ketone peroxide, cyclohexanone peroxide, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, p- Menthane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxylaurate , T-butyl peroxybenzoate and the like.

  Furthermore, the thermosetting resin composition according to the present invention includes p-benzoquinone, naphthoquinone, p-toluquinone, 2,5-diphenyl-p-benzoquinone, 2,5-acetoxy-p-benzoquinone, hydroquinone as a polymerization inhibitor. , P-t-butylcatechol, 2,5-di-t-butylhydroquinone, di-t-butyl-p-cresol, hydroquinone monomethyl ether, and the like. These polymerization inhibitors can be used in combination of two or more. In addition, the usage-amount of a polymerization inhibitor is 0.5 mass part or less with respect to 100 mass parts of total mass of the said unsaturated polyester alkyd (A) and the said allylic copolymerizable monomer (B).

The rare earth-iron magnet flake according to the present invention is an R—Fe—B magnet (where R is a rare earth element such as Ce, Pr, Nd, Gd, Tb, Dy, Ho, etc., including Y) or R—Fe (Co) —B based magnet partially substituted with Co (where R represents the above-mentioned meaning), and further Si, Al, Nb, Zr, Hf, Mo, Ga, P, C 1 R-Fe-BM type magnet or R-Fe (Co) -BM type magnet using a seed or a combination of two or more types (where R represents the aforementioned meaning, M represents Si, Al, Nb, Zr, Hf, Mo, Ga, P, C represents one or a combination of two or more), R ₂ Fe ₁₄ B, R ₂ Fe (Co) ₁₄ B nanocrystalline structure having an alloy composition composed of inevitable impurities ( nanocrystalline), or αFe and R ₂ F
Magnetically isotropic rare earth-iron rapidly solidified flakes containing a nanocomposite with e ₁₄ B and R ₂ Fe (Co) ₁₄ B (wherein R represents the aforementioned meaning) are preferred.
Alternatively, the rare earth-iron-based magnet flake according to the present invention includes a Sm—Fe—N-based magnet and a combination of one or more of Hf, Zr, Si, Nb, Ti, Ga, Al, Ta and C. Sm—Fe—M′—N-based magnet used (where M ′ represents one or a combination of two or more of Hf, Zr, Si, Nb, Ti, Ga, Al, Ta and C), and unavoidable including _Sm 2 _Fe 17 Nx having an alloy composition consisting of impurities (x ≒ 3) nanocrystal structure (nanocrystalline), or αFe and _{Sm 2 Fe 17 Nx (x ≒} 3) and nanocomposite structure of the (nanocomposite), magnetic It is possible to use isotropic rare earth-iron rapidly solidified flakes.
In general, as a magnet mounted on a small motor, the coercive force at room temperature is 600 kA / m or more, the saturation magnetization Ms is high, and the residual magnetization Mr is a nanostructure or nanocomposite structure in which remanence enhancement is expressed. The magnet flakes are preferred.

  The step of producing the annular green compact from the above-mentioned thermosetting resin composition and rare earth-iron-based magnet flakes is preferably carried out as follows.

First, the thermosetting resin composition is made into a molten state using, for example, a mixing roll, and a predetermined amount of the rare earth-iron-based magnet flakes are added and kneaded to obtain a melt-kneaded product. A composite magnetic material (hereinafter, also simply referred to as “granule”) is obtained. Alternatively, the unsaturated polyester alkyd (powder), the copolymerizable monomer (liquid), the polymerization initiator (liquid or powder), etc., and the rare earth-iron magnet flakes constituting the resin composition are previously bundled together. For example, using a mixing roll at a temperature near the melting point of the unsaturated polyester alkyd, simultaneously with the production of the molten unsaturated polyester resin that is a copolymerizable monomer solution of the unsaturated polyester alkyd, The magnet flakes may be kneaded.
Here, by kneading the magnet flakes in the molten state of the thermosetting resin composition, the voids in each granule can be reduced. From this point of view, all of this step is performed without a solvent. It is desirable to carry out in a solvent-free type.

Subsequently, the granule-shaped composite magnet material thus obtained is filled into a mold cavity, and at a temperature not higher than the melting point of the granule-shaped composite magnet material, for example, normal temperature (20 ° C. ± 15 ° C. (5-35 ° C.)) Uniaxial pressure is applied to form an annular green compact.
This process will be described in detail. First, the granule-like composite magnetic material is filled in a cavity, and at a temperature not higher than the melting point of the granule, uniaxial pressure is applied to the granule, that is, the thermosetting resin composition. A pressure higher than the yield stress, for example, a pressure of about 0.8 GPa to 1.0 GPa is applied. Then, the granule according to the present invention is more than the yield stress of densification transient (compression), and simultaneously with the brittle fracture of the magnet flakes contained in the granule, the thermosetting resin composition is plastically deformed (flowed), Their synergistic effect fills (decreases) the gap around the granule. At the same time, a part of the granules (magnet flakes) rotate to be stacked in the pressure axis direction. Here, the positional relationship between the granules (magnet flakes) is almost stable and fixed.
Next, the pressure is released, and the annular green compact is released from the mold cavity. At this stage, basically, a granule (magnet flake) with a certain angle in the direction of the pressure axis in the elastic range rotates to return to its original position, that is, exhibits an elastic recovery phenomenon (spring back). However, in the annular green compact according to the present invention, the elastic recovery phenomenon (spring back) can be suppressed to be lower than that in the prior art after releasing from the mold cavity.

The annular green compact thus obtained has a volume fraction of magnet flakes in the annular green compact of 80 vol. %, The volume fraction of residual voids is 3 vol. % Or less, and the balance can be the thermosetting resin composition. With such a configuration, in the bonded magnet according to the present invention in which at least the cured product of the thermosetting resin composition is in a glass state, the value of the linear expansion coefficient of the magnet is 12 × equivalent to the linear expansion coefficient of the annular iron yoke. It can be made into 10 <^{-6> (degreeC) -1} or less.

[Second step]
This step is a step in which the annular green compact obtained in the first step is heated in combination with the annular iron yoke, and the green compact is thermally cured in a state of being in close contact with the yoke to form an annular bonded magnet. Specifically, in the curing process of the thermosetting resin composition constituting the annular green compact, the linear expansion coefficient of the annular iron yoke that is in close contact with the green compact and the linear expansion coefficient of the annular bonded magnet are It is a process of thermosetting up to a curing point that is almost equal (12 × 10 ⁻⁶ ° C. ⁻¹ or less).

  Here, in FIG. 1, the conceptual diagram which shows the outer-diameter change in the thermosetting transition of the thermosetting resin composition which comprises the cyclic | annular green compact concerning this invention is shown. Before such heat curing treatment, the outer peripheral surface of the annular green compact according to the present invention and the inner peripheral surface of the annular iron yoke according to the present invention have a clearance of, for example, 20 to 30 μm at predetermined positions in the axial direction. Opposite coaxially. Here, the annular iron yoke is opposed to the annular green compact at a predetermined position in the axial direction of the inner peripheral surface of the annular iron yoke in a state where the diameter of the inner peripheral surface is expanded from room temperature by preheating. It can be positioned. In the second step according to the present invention, after making the assembly of the annular iron yoke and the annular green compact as described above, the thermosetting resin composition of the annular green compact is subjected to a heat curing treatment.

In FIG. 1, symbol A is the outer diameter of the thermosetting resin composition (annular green compact) at room temperature at the start of heating. Further, symbol B is a melting point of the thermosetting resin composition, symbol C is a two-dimensional crosslinking reaction starting point of the thermosetting resin composition, symbol D is a gel point of the thermosetting resin composition, and symbol E is a heat. The curing point of the curable resin composition, symbol F, indicates the glass transition point (and the outer diameter at each temperature) of the thermosetting resin cured product. And the code | symbol G shows the outer diameter of the thermosetting resin hardened | cured material (cyclic bond magnet) at the time of returning hardened | cured material to normal temperature.
Considering the assembly of the annular iron yoke and the annular green compact, the outer peripheral surface of the annular compact is expanded by thermal expansion, and the outer peripheral surface of the green compact is formed by the inner peripheral surface of the annular iron yoke. The constrained contact (restraint) points, C ′ and D ′, respectively, are two-dimensional crosslinking reaction start points in a state where the outer peripheral surface of the annular green compact is constrained by the inner peripheral surface of the annular iron yoke, and It is a gel point.

As shown in FIG. 1, the section AB shows the expansion of the outer diameter due to the thermal expansion of the annular green compact mainly due to the thermal expansion of the thermosetting resin composition that is solid at room temperature. The annular green compact has almost no residual voids in the first step according to the present invention, and the solid thermosetting resin composition forms a continuous phase.
Section B-C shows expansion of the outer diameter of the annular green compact due to thermal expansion of the thermosetting resin composition in a liquid phase. In this section, the expansion speed of the outer diameter increases as the viscosity of the liquid-phase thermosetting resin composition decreases due to temperature rise. In the present invention, at the contact point CNT in the section BC, the inner peripheral surface of the annular iron yoke is brought into close contact (restraint) with the outer peripheral surface of the annular green compact. In addition, the expansion | extension (expansion) rate of the outer diameter in area BC can be suitably adjusted with selection of the polymerization initiator in a thermosetting resin composition. In addition, in order to further strengthen the integral fitting of the annular iron yoke and the annular green compact according to the present invention, the surface roughness of the inner peripheral surface of the annular iron yoke that serves as a contact surface with the annular green compact is streaked. It is desirable to increase the contact area (true contact area) of the annular green compact according to the present invention by roughening by knurling or blasting.

As shown in the section CD, the outer diameter expansion rate based on the thermal expansion of the annular green compact is reduced by the progress of the two-dimensional crosslinking reaction (gelation) of the thermosetting resin composition in the unconstrained state. Or the outer diameter will shrink somewhat. However, in the section C′-D ′ according to the present invention, gelation occurs while the outer peripheral surface of the annular green compact is constrained to the inner peripheral surface of the annular iron yoke.
Then, as shown in the section D-E, the thermosetting resin composition behaves as a solid in an unconstrained state, and strictly increases the crosslinking density to cause a slight shrinkage (change amount: S1) to cause the curing point E. To. However, the annular green compact in the constrained state according to the present invention changes as in the section D′-E, and the curing point E in a state in which the amount of change in shrinkage (S1) is suppressed as compared with the unconstrained state. To. Here, the volume fraction of the magnet flakes is 80 vol. % Of the annular green compact according to the present invention having a linear expansion coefficient value equal to the linear expansion coefficient value of the cyclic iron yoke is 12 × while the cured product of the thermosetting resin composition is in a glass state. It becomes 10 <^{-6> (degreeC) -1} or less, and becomes a cyclic | annular bond magnet formed by integral fitting with a cyclic | annular iron yoke and almost no space | gap.

  In the section EF, the annular bond magnet contracts due to the linear expansion coefficient above the glass transition point (Tg) of the cured product of the thermosetting resin composition, and in the section FG, the annular iron yoke and the annular bond magnet are separated. Since it is cooled to room temperature and the values of the linear expansion coefficients of both are substantially the same, it shrinks by the same amount. The amount of change in contraction of the annular bonded magnet in the section E-F-G is S2.

  The difference between the outer diameter A of the annular green compact at normal temperature and the outer diameter G of the annular bonded magnet at normal temperature is based on the expansion of the outer diameter due to thermal expansion of the thermosetting resin composition during the curing transient. The volume fraction of the magnet flakes according to the present invention is 80 vol. In the case of a green compact exceeding 100%, the expansion rate ((GA) / A) × 100 (%) in the section A-B-C-D-E-F-G (unconstrained state) is 0.06% The expansion rate is substantially the same in the section AB- (CNT) -C'-D'-EFG (restrained state). By this outer diameter expansion, a configuration in which the annular bonded magnet is integrally fitted along the inner peripheral surface of the annular iron yoke is completed. In addition, since the values of the linear expansion coefficients of the annular iron yoke and the annular bonded magnet are approximately the same, the dimensional accuracy such as coaxiality is improved.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to this.

[First step: Manufacturing process of green compact]
In this example, as the thermosetting resin composition having plastic deformation (fluidity) having a yield stress according to the present invention, the acid component is phthalic acid / fumaric acid = 4/6 (molar ratio), and the glycol component is 1,4-butanediol / other glycol = 10/0 (molar ratio), unsaturated polyester alkyd (A) having a melting point of 102 ° C., and melting point of 23 to 27 ° C. as an allylic copolymerizable monomer Triallyl isocyanurate (B), blending ratio: B / (A + B) is 25 wt. %, And melt-kneaded to make a completely dissolved material. To 100 parts by weight of the completely dissolved material, 1.5 parts by weight of dicumyl peroxide is added as a polymerization initiator, and melt-kneaded to prepare. The obtained thermosetting resin composition was used. In addition, the true density by the Archimedes method of the hardened | cured material of this thermosetting resin composition was 1.25 Mg / m < ³ >.

In this embodiment, Nd ₂ Fe ₁₄ is used as a nanocrystalline magnet flake.
A true density of 7.59 Mg / m ³ obtained by rapidly solidifying an Nd ₁₂ Fe ₇₇ Co ₅ B ₆ (atomic%) molten alloy having an alloy composition close to the stoichiometric composition of B, and a particle diameter of 150 μm or less (dry sieving method (JIS Z 8815)), a magnetic flake having a residual magnetization Mr: 0.90 T and a coercive force HcJ: 0.8 MA / m was used.

<A) Production of granular composite magnet material>
The magnet flakes and the thermosetting resin composition were melt-kneaded using a 8-inch twin roll mill having a surface temperature set to 100 ° C. in the absence of a solvent to obtain a melt-kneaded product. Here, the ratio of the thermosetting resin composition is 2.5, 3.0, 3.5, 4.0 wt.% In the melt-kneaded product (that is, based on the total mass of the composite magnet material). %, Various magnetic flakes and a thermosetting resin composition were blended.
Subsequently, the melt-kneaded product was adjusted to a thickness of 1 mm or less using a constant speed roll mill having a surface temperature of 80 ° C., and coarsely pulverized with a Henschel mixer. Furthermore, it was set as the granule-shaped composite magnet material with a particle diameter of 53-250 micrometers by crushing with an electric stone mill and classification with a sieve.
The obtained granule-like composite magnet material became a granule-like composite magnet material having no stickiness at room temperature and excellent blocking resistance. This material had a powder flow of 40 seconds / 50 g without an external lubricant. For this reason, in <b) Production of green compact> described later, it was possible to fill the mold ring cavity from the feeder cup of an existing powder molding machine by a conventional method.

<B) Production of green compact>
3.3 g of the granular composite magnet material obtained in the above-described process was filled in a mold cavity (inner diameter 10.08 mm) and compressed at a normal pressure of 1.0 GPa to obtain a green compact.
FIG. 2 shows the relationship between the volume fraction Va of the residual void to the volume fraction Vr of the thermosetting resin composition constituting the obtained green compact (Example) (indicated by □ in the figure), and Vr The characteristic view which shows the relationship (indicated by ○ in the figure) of the volume fraction Vm of the magnet flakes is shown.
In place of the thermosetting resin composition described above, an epoxy resin that is solid at room temperature (diglycidyl ether bisphenol A type epoxy oligomer: epikote 1002 and 4-4 ′ diphenylmethane diisocyanate regenerated material with OH / NCO = 1) ) Is mixed with the magnetic flakes as an organic solvent solution, desolvated, crushed, classified, and adjusted in particle size. Granular composite magnet material containing an epoxy resin composition (epoxy resin relative to the total mass of the composite magnet material) The volume fraction of the epoxy resin composition in the green compact (comparative example) produced under the same conditions as in <a) Production of granular composite magnet material> using 2.0 wt. The relationship between the volume fraction Va of the residual void with respect to Vr (indicated by ■ in the figure), and the relationship between the volume fraction Vm of the magnet flakes with respect to Vr (with ● in the figure). The display is also shown in FIG.
Here, the true density by the Archimedes method of the sample which heat-cured only the said epoxy resin composition which is a prior art example was 1.16 Mg / m < ³ >.

As shown in FIG. 2, in the green compact of the example, when the volume fraction of the thermosetting resin composition is increased, the volume fraction Vm of the magnetic flakes of the green compact is 80 vol. As a result, only the volume fraction Va of the residual voids was reduced while maintaining at about%, that is, the result that the residual voids in the green compact were replaced with the resin composition was obtained. For example, the volume fraction Vm of the magnet flakes of the green compact of this example
80.05 vol. %, The volume fraction of the thermosetting resin composition was 17.97 vol. % (3.5 wt.%), The volume fraction of residual voids is 1.97 vol. %, The spring back of the green compact is 0.2 to 0.3% and the crushing strength is 20 to 22 MPa. Compared with the conventional example (comparative example), the spring back is reduced by 40%. The crushing strength was increased by 200%.

Table 1 shows the configurations of the magnetic flakes, residual voids, and volume fraction of the resin composition of the green compacts of the present invention example (containing the unsaturated polyester resin composition) and the comparative example (containing the epoxy resin composition). The magnetic properties (retention force, residual magnetization, maximum energy product) of the green compact are shown. The magnetic characteristics are values measured with a DCB-H tracer (measuring magnetic field ± 2.4 MA / m).
As shown in Table 1, while the green compact of the example according to the present invention is a green compact produced by a compression molding method, the volume fraction of the magnet flakes is 80 vol. % And the volume fraction of residual voids is reduced to 1.97 vol%, which can reduce the residual voids to a level equivalent to that of a bonded magnet produced by injection molding and It shows that the volume fraction was increased.

[Second step (integrated fitting)]
A cold rolled steel sheet having a thickness of 1.0 mm, a 10 mm deep drawing process, an inner peripheral surface having a surface roughness of 8 to 10 μm Rz, an inner diameter of 500.035 mm, an inner diameter of 50.005 mm, a thickness The annular green compact obtained by the above-mentioned process of 0.9 mm and height 5 mm was inserted into a predetermined position at room temperature to form an assembly of the annular iron yoke and the annular green compact having the configuration shown in Table 1. .

  Next, the assembly was heated in air at 130 ° C. for 10 minutes, further heated at 170 ° C. for 20 minutes, and allowed to cool naturally to room temperature. As a result, an outer rotor magnet according to the present invention in which an annular iron yoke and a rare earth-iron bond magnet were integrally fitted was obtained.

Here, the behavior of the curing transient of the thermosetting resin composition of the integrally fitted outer rotor magnet according to this example was investigated.
First, the thermosetting resin composition of the example has a melting point B near 90 ° C., and a two-dimensional crosslinking reaction (gelation) starting point C around 150 ° C. (C ′ in a restrained state). ), A gel point D of about 20 seconds at 160 ° C. (D ′ in a constrained state), a curing point E within 180 seconds at 170 ° C., and a glass transition point F of the cured product of the composition around 150 ° C. Was.
Further, the magnet flakes according to the present invention are 80 vol. The average linear expansion coefficient from room temperature to 130 ° C. of the annular green compact containing 1% is about 16 × 10 ⁻⁶ ° C.− ¹ , and the linear expansion coefficient of one cold-rolled steel sheet is 11.8 to 12 × 10 ⁻⁶ ° C. ^-1 .
From these, the temperature change of the clearance in the assembly of the annular iron yoke and the annular green compact according to the present invention was estimated. A characteristic diagram showing the temperature change of the clearance is shown in FIG. Note that the reference numerals in FIG. 3 correspond to those in FIG.

As shown in FIG. 3, due to the difference in coefficient of linear expansion between the annular iron yoke and the annular green compact, the adhesion (restraint) point CNT where the outer peripheral surface of the annular green compact is in close contact with the inner peripheral surface of the annular iron yoke is 120 ° C. This temperature is higher than the melting point B (around 90 ° C.) of the thermosetting resin composition and lower than the two-dimensional crosslinking reaction start point C (around 150 ° C.) of the thermosetting resin composition. Therefore, in the adhesion point CNT, the thermosetting resin composition is in a liquid phase state and is in close contact with the annular iron yoke in a state where the outer diameter of the annular green compact is expanded, and the surface roughness is 8 to 10 μm Rz. It is estimated that the real contact area between the inner peripheral surface of the annular iron yoke and the annular green compact can be increased.
Furthermore, the clearance between the annular iron yoke and the annular green compact is zero until the gelation point D ′ and the curing point E of the thermosetting resin composition are constrained, and the thermosetting resin composition is cured. In natural cooling from point E to room temperature G, it passes the glass transition point F (around 150 ° C.) of the cured product of the thermosetting resin composition. Here, the magnet flakes are 80 vol. % Of the bonded bond magnets of the present invention example exceeding 1% has a linear expansion coefficient of 11.8 × 10 ⁻⁶ ° C.− ¹ when the cured product of the thermosetting resin composition is in a glass state, and includes the glass transition region. The average linear expansion coefficient from 170 ° C. to room temperature was 20 × 10 ⁻⁶ ° C. ⁻¹ or less. Therefore, apparently, the clearance between the annular iron yoke and the annular bonded magnet remains substantially zero during the cooling process from the curing point E to the room temperature G of the thermosetting resin composition.

  Further, the roundness of the inner diameter of the obtained outer rotor magnet according to the present invention is 20 μm or less, and the fitting strength at 100 ° C. (the unloading load when the yoke is fixed and a shear load is applied to the entire surface of the magnet) is 500 N or more.

As described above, the manufacturing method of the annular iron yoke-integrated outer rotor magnet according to the present invention achieves a reduction in the amount of residual voids in the annular bonded magnet constituting the magnet by performing the above-described steps, and 80 vol. . In addition to the volume fraction of high magnet flakes exceeding%, in the glass state of the thermosetting resin composition constituting the annular bonded magnet, the linear expansion coefficient of the annular bonded magnet is set to the linear expansion coefficient (11.8 to 12 × 10 ⁻⁶ ° C. ⁻¹ ), which is approximately equal to 12 × 10 ⁻⁶ ° C. ⁻¹ or less.
And 1) As an effect due to the reduction of the residual gap, 1-1) Improvement of dimensional accuracy such as concentricity (by reduction of springback and improvement of pressure ring strength), 1-2) Improvement of fitting force (by fitting surface) 1-3) Suppression of permanent demagnetization (due to reduction of oxygen, moisture, etc. contained in residual voids) 1-4) Improvement of corrosion resistance (injection even in compression molding method) Residual void amount (for example, less than about 3 vol.%), Which is the same as the molding method, can be realized. 2) 80 vol. 2-1) Improvement of integral fitting and its dimensional stability, 2-2) Effects of volume fraction of magnet flakes exceeding 50% and linear expansion coefficient of annular bonded magnet and iron yoke being comparable. Residual magnetization, high stability of the initial characteristics of the bonded magnet such as (BH) _max (due to a high filling rate of the magnet flakes), etc. can be realized.
For this reason, the magnet performance, dimensional change, opportunity strength, etc. are long-term at the actual use temperature including high temperature exposure and low temperature exposure (for example, about -30 ° C to + 80 ° C when considering both operation and storage). The industrial utility value is extremely large. These effects annular yoke (11.8~12 × ^{10 -6} ℃ ^-1) and injection molded bonded magnet (43 × ^{10 -6} ℃ about ^-1) adjuvant difference coefficient of linear expansion can not be ignored and, The volume fraction is 9-11 vol. This is an effect peculiar to the present invention that cannot be obtained when a compression-molded bonded magnet according to the prior art having as many% residual voids is used.
According to the manufacturing method of the present invention, an integrally fitted outer rotor magnet having high magnetic performance, high dimensional accuracy, and high mechanical strength can be manufactured with good yield and stable on an industrial scale. An integrally fitted outer rotor magnet of a rare earth-iron-based bond magnet and an annular iron yoke that can maintain and ensure high reliability in the entire range of actual use temperatures such as high temperature exposure and low temperature exposure during a period can be provided.

Symbol A: Outer diameter symbol B of thermosetting resin composition (annular green compact) at normal temperature at the start of heating B: Melting point symbol C of thermosetting resin composition Two-dimensional crosslinking of thermosetting resin composition Reaction starting point code D: Gelation point code of thermosetting resin composition E: Curing point code of thermosetting resin composition F: Glass transition point code of thermosetting resin cured product G: Thermosetting returned to room temperature Outer diameter code CNT in the cured resin (annular bonded magnet): adhesion (constraint) point code in which the outer peripheral surface of the annular green compact is constrained by the inner peripheral surface of the annular iron yoke C ′: 2 in a constrained state Dimensional cross-linking reaction start point code D ′: gel point in a constrained state

Claims (12)

A first step of producing an annular green compact comprising a rare earth-iron-based magnet flake, a thermosetting resin composition that is solid at room temperature, and residual voids by compression;
By inserting the annular green compact inside the annular iron yoke and heating,
The outer diameter of the annular green compact is expanded by the thermal expansion of the thermosetting resin composition constituting the annular green compact, and before the two-dimensional crosslinking reaction of the thermosetting resin composition is started, While keeping the outer peripheral surface of the powder and the inner peripheral surface of the annular iron yoke at a predetermined position,
A second step of thermosetting the thermosetting resin composition constituting the annular green compact in the constrained state to form an annular bonded magnet. Production method. The annular green compact obtained in the first step has a volume fraction of rare earth-iron-based magnet flakes of 80 vol. % And the volume fraction of residual voids is 3 vol. The manufacturing method of the iron-yoke integral fitting outer rotor magnet of Claim 1 which consists of a thermosetting resin composition which is less than% and a remainder is solid at normal temperature. In the obtained iron yoke integrated fitting outer rotor magnet, the linear expansion coefficient of the annular bond magnet in which the cured thermosetting resin composition is in a glass state is 12 × 10 ⁻⁶ ° C. ⁻¹ or less. The manufacturing method of the iron yoke integral fitting outer rotor magnet of description. In the first step, a granule-shaped composite magnet material containing a thermosetting resin composition and a rare earth-iron-based magnet flake is filled into a mold cavity, and the temperature is equal to or lower than the melting point of the granule-shaped composite magnet material. In addition, by applying uniaxial pressure to the granular composite magnet material, the residual voids are reduced by the brittle fracture of the magnet flakes and the interaction with plastic deformation (flow) of the thermosetting resin composition. The annular composite magnetic material is laminated in the pressure axis direction to produce an annular green compact in which the positional relationship between the magnet flakes is substantially fixed.
The manufacturing method of the iron rotor integral fitting outer rotor magnet of Claim 1. The thermosetting resin composition comprises a flowable unsaturated polyester resin having a yield stress, which is a complete solution of an unsaturated polyester alkyd and an allylic copolymerizable monomer, and an organic peroxide. Including,
The manufacturing method of the iron rotor integral fitting outer rotor magnet of Claim 1. The method for producing an iron rotor-integrated outer rotor magnet according to claim 5, wherein the allylic copolymerizable monomer is triallyl isocyanurate. The rare earth-iron-based magnet flakes are R-Fe-B-based magnets, R-Fe (Co) -B-based magnets in which part of Fe is replaced with Co, and further R-Fe-BM-based magnets. R ₂ Fe ₁₄ B, R ₂ Fe (Co) ₁₄ B nanocrystalline structure having an alloy composition of inevitable impurities, or αFe and R ₂ Fe ₁₄ B, R ₂ Fe (Co) ₁₄ B and nanocomposite structure (wherein R represents any of rare earth elements selected from Ce, Pr, Nd, Gd, Tb, Dy and Ho containing Y, and M represents Si, A magnetically isotropic rare earth-iron rapidly solidified flake containing one or a combination of two or more selected from Al, Nb, Zr, Hf, Mo, Ga, P and C). The iron yoke integrated fitting outer rotor magnet according to claim 1. Method. The rare earth-iron-based magnet flakes are Sm ₂ Fe ₁₇ Nx (x≈3) nanocrystal structure having an alloy composition composed of Sm—Fe—N magnet, Sm—Fe—M′—N magnet, and inevitable impurities. (Nanocrystalline) or a nanocomposite of αFe and Sm ₂ Fe ₁₇ Nx (x≈3) (wherein M ′ is selected from Hf, Zr, Si, Nb, Ti, Ga, Al, Ta and C) The method for producing an iron-yoke integrated fitting outer rotor magnet according to claim 1, which is a magnetically isotropic rare earth-iron rapidly solidified flake. The method for manufacturing an iron-yoke integrated fitting outer rotor magnet according to claim 1, wherein the annular green compact has a crushing strength of 20 MPa or more. The manufacturing method of the iron rotor integrated fitting outer rotor magnet according to claim 1, wherein the annular bonded magnet has a thickness of 1 mm or less. 2. The iron yoke integrated body according to claim 1, wherein the annular bonded magnet has a residual magnetization Mr of 0.74 T or more and a maximum energy product (BH) _max of 90 kJ / m ³ or more in an external magnetic field Hm of 2.4 MA / m. Manufacturing method of fitting outer rotor magnet. An iron yoke integrated fitting outer rotor magnet obtained by integrally fitting a rare earth-iron-based bond magnet to the inner diameter side of the rotor yoke, manufactured by the manufacturing method according to any one of claims 1 to 11. An outer rotor type motor rotor.

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