Composite member, method for manufacturing the same, and rotor of a motor

Abstract

The present invention relates to a method for producing a composite member, said method including: a step in which a first molded body is fitted together with a first composite body including a rare earth magnet and a member in contact with the rare earth magnet so that said first molded body covers at least the entire surface of the rare earth magnet in the first composite body, and a second composite body is thereby produced; and a step in which the second composite body is inserted in a mold, at least the entire surface not covered by the first molded body in the first composite body is covered, a thermoplastic resin is injection molded so as to be in contact with the first molded body, and a second molded body is formed.

Description

Technical Field

[0001] The present invention relates to a composite member containing a rare earth magnet and a method for manufacturing the same.

Background Art

[0002] In order to prevent corrosion of a permanent magnet at low cost, a method of covering the entire permanent magnet with resin is known. For example, Patent Document 1 discloses a magnet body for a rotor, in which a member composed of a permanent magnet and a ring-shaped yoke is installed in a mold together with a spacer made of polyphenylene sulfide (PPS) resin, and the PPS resin is injection-molded to cover the entire permanent magnet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when injection molding is performed on a rare earth magnet, there is a problem that the rare earth magnet comes into direct contact with the resin and the magnetic properties of the permanent magnet deteriorate due to heat. In addition, since the injection-molded resin shrinks upon solidification, a gap is generated between the resin and the spacer, and there is also a problem that the entire permanent magnet cannot be completely covered.

[0005] An object of the present invention is to provide a composite member in which a rare earth magnet is sealed and a method for manufacturing a composite member in which a decrease in magnetic properties during manufacturing is suppressed.

Means for Solving the Problems

[0006] A method for manufacturing a composite member according to an aspect of the present invention is A step of fitting a first molded body to the first composite body so as to cover at least the entire surface of the rare earth magnet among the first composite body including the rare earth magnet and the member in contact with the rare earth magnet to produce a second composite body, and, The method includes inserting the second composite body into a mold, injection molding a thermoplastic resin so as to cover at least the entire surface of the first composite body not covered by the first molded body and to be in contact with the first molded body to form a second molded body.

[0007] A composite member according to one aspect of the present invention is a first composite body including a rare earth magnet and a member in contact with the rare earth magnet, a first molded body that covers at least the entire surface of the rare earth magnet among the first composite body, and, a second molded body that covers at least the entire surface of the first composite body not covered by the first molded body and is in contact with the first molded body and has.

Advantages of the Invention

[0008] According to the above aspect, it is possible to provide a composite member in which a rare earth magnet is sealed and a method for manufacturing a composite member that suppresses a decrease in magnetic properties during manufacturing.

Brief Description of the Drawings

[0009]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 2C

Figure 3A

Figure 3B

Figure 3C

Figure 3D

Figure 4A

Figure 4B

Figure 4C

Figure 5A

Figure 5B

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments shown below are merely examples for embodying the technical idea of the present invention, and the present invention is not limited to the following. In this specification, the term "step" includes not only an independent step but also the term if the intended purpose of the step is achieved even when it cannot be clearly distinguished from other steps. Also, in the embodiments, expressions such as up and down, left and right, etc. only describe the relative positional relationship and do not have to match the relationship during use.

[0011] The manufacturing method of the composite member of the present embodiment includes a step of fitting a first molded body to the first composite body so as to cover at least the entire surface of the rare earth magnet in the first composite body including the rare earth magnet and the member in contact with the rare earth magnet to produce a second composite body, and a step of inserting the second composite body into a mold and injection molding a thermoplastic resin so as to cover at least the entire surface of the first composite body not covered by the first molded body and to be in contact with the first molded body to form a second molded body. FIGS. 2A, 2B, and 2C are cross-sectional views of the composite body and the composite member obtained in each step for a disc-shaped composite member in the manufacturing method of the composite member of the present embodiment. FIG. 2A shows a cross-sectional view of the first composite body obtained in the step of producing the first composite body, FIG. 2B shows a cross-sectional view of the second composite body obtained in the step of producing the second composite body, and FIG. 2C shows a cross-sectional view of the composite member of the present embodiment obtained in the step of forming the second molded body. According to the manufacturing method of the present embodiment, after covering the entire surface of the rare earth magnet of the first composite body with the first molded body, the remaining entire surface of the first composite body is covered with a thermoplastic resin by injection molding. Therefore, the rare earth magnet and the thermoplastic resin do not come into direct contact during injection molding, and it is possible to suppress a decrease in the magnetic properties of the rare earth magnet due to heat and deformation of the bonded magnet due to heat, and to obtain a composite member in which the rare earth magnet is sealed.

[0012] <Step of producing the first composite body> Before the step of producing the second composite, there may be a step of producing the first composite. In the step of producing the first composite, a rare earth magnet (first member) and a member (second member) are brought into contact with each other to produce a first composite having a joint surface. The joint surface means the surface where both of them are in contact. In a later step, since the rare earth magnet and the member are held by the first molded body and the second molded body, the joint surface does not need to be fixed, adsorbed by magnetic force, or adhered by an adhesive. However, from the viewpoint of handling property when fitting the first composite and the first molded body, or when inserting the second composite produced by fitting the first composite and the first molded body into a mold, it is preferable to adsorb by magnetic force, fix, or adhere with an adhesive. Further, in addition to adsorption, fixing, and adhesion, the first composite may be produced by injection molding a bonded magnet directly onto a member having a plurality of grooves formed therein. The magnetic field direction of the rare earth magnet in the first composite is not particularly limited. For example, when used for an axial gap type rotor, a rare earth magnet magnetized parallel to the height direction of the first composite can be used. When used for a radial gap type rotor, a rare earth magnet magnetized perpendicular to the height direction can be used.

[0013] The rare earth magnet constituting the first composite is not particularly limited, and examples include bonded magnets and sintered magnets. When the rare earth magnet constituting the first composite is a bonded magnet, after the first molded body is fitted so as to cover the entire surface of the bonded magnet, the thermoplastic resin is injection molded in the step of forming the second molded body. Therefore, in addition to suppressing the decrease in magnetic properties due to heat without the bonded magnet coming into direct contact with the high-temperature resin, deformation of the bonded magnet can also be suppressed.

[0014] The rare earth magnetic powder used for the bonded magnet or the sintered magnet is not particularly limited, but SmFeN-based, NdFeB-based, and SmCo-based rare earth magnetic powders can be used. As the rare earth magnetic powder, it is more preferable to use SmFeN-based magnetic powder because it is superior in terms of heat resistance compared to NdFeB-based, and does not use rare metals compared to SmCo-based. As the SmFeN-based magnetic powder, it has a Th2Zn 17 type crystal structure, and the general formula is Sm x Fe100-x-y N y It is a nitride composed of rare earth metal samarium Sm, iron Fe, and nitrogen N represented by y . Here, the x value of the atomic percentage of rare earth metal Sm is in the range of 8.1% or more and 10% or less, and the y value of the atomic percentage of N is in the range of 13.5% or more and 13.9% or less, with the balance mainly being Fe. Also, as magnetic powder, in addition to the SmFeN system, rare earth magnetic powders such as the NdFeB system and the SmCo system, and ferrite magnetic powders can be used in combination.

[0015] The SmFeN-based magnetic powder can be manufactured, for example, by the method disclosed in Patent No. 3698538. Thereby, those with an average particle size of the SmFeN-based magnetic powder of 2 μm or more and 5 μm or less and a standard deviation of within 1.5 can be preferably used.

[0016] On the other hand, for the NdFeB-based magnetic powder, it can be manufactured, for example, by the HDDR method described in Patent No. 3565513. This NdFeB-based magnetic powder has an average particle size of 40 μm or more and 200 μm or less, and a maximum energy product of 34 MGOe or more and 42 MGOe or less (270 kJ / m 3 or more and 335 kJ / m 3 or less) and can be preferably used. Furthermore, for the SmCo-based magnetic powder, it can be manufactured, for example, by the method disclosed in Patent No. 3505261, and those with an average particle size of 10 μm or more and 30 μm or less can be used.

[0017] The average particle size of the magnetic powder is preferably 10 μm or less, more preferably 1 μm or more and 5 μm or less. If the average particle size is larger than 10 μm, there is a possibility that unevenness, cracks, etc. may occur on the surface of the bonded magnet, resulting in inferior appearance. On the other hand, if the average particle size is smaller than 1 μm, the cost of the magnetic powder will increase. The average particle size is measured as the particle size corresponding to 50% of the volume cumulative from the small particle size side in the particle size distribution.

[0018] The magnetic material can also be surface-treated with a silane coupling agent. By surface-treating with a silane coupling agent or the like, an increase in viscosity during injection molding can be suppressed.

[0019] As the silane coupling agent, the general formula; X-Si-(OR) n (wherein X is an alkyl group having a polar group at the terminal, R is an alkyl group having 1 to 3 carbon atoms, and n is an integer of 1 to 3), and those having an amino group, a ureido group, an epoxy group, a thiol group, or a methacryloxy group as the polar group in X are preferred. When using a nylon resin as the thermoplastic resin, it is preferable to use a coupling agent having an amino group with high affinity for the nylon resin. In particular, it is preferable to use 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, or 3-(2-aminoethyl)aminopropylmethyltriethoxysilane.

[0020] The resin used for the bonded magnet is not particularly limited, and for example, a thermosetting resin or a thermoplastic resin can be used. Examples of the thermosetting resin include epoxy resin. Also, as the thermoplastic resin, since the entire surface of the bonded magnet of the first composite is covered by the first molded body and the bonded magnet does not come into direct contact with the high-temperature resin during injection molding, resins with a low melting point can also be used. As the thermoplastic resin for the bonded magnet, for example, a resin having a melting point of 240°C or lower can be used, and particularly a resin having a melting point of 120°C or higher and 200°C or lower can be used. Examples of the thermoplastic resin include polypropylene, polyethylene, polyvinyl chloride, polyester, polyamide, polycarbonate, polyphenylene sulfide, acrylic resin, etc. Also, among the thermoplastic resins, it is preferable to use crystalline polypropylene or crystalline polyamide which has a relatively low melting point, a low water absorption rate, and good moldability, and particularly it is preferable to use crystalline polypropylene. Also, it is possible to use these by appropriately mixing them. Also, the content of the resin used for the bonded magnet is not particularly limited, but is preferably 3 mass% or more and 20 mass% or less, and more preferably 5 mass% or more and 15 mass% or less with respect to the entire magnet. If it is less than 3 mass%, it becomes difficult to produce the bonded magnet because the amount of the resin with respect to the rare earth magnetic powder is small, and if it exceeds 20 mass%, a sufficient magnetic flux density cannot be obtained as a magnet.

[0021] For the bonded magnet, components generally blended in the bonded magnet, such as an antioxidant, a lubricant, a heavy metal inactivator, etc., can be blended. Also, the magnetic powder used in this embodiment is preferably surface-treated for the purpose of improving oxidation resistance, water resistance, wettability with the resin, and chemical resistance. Note that these treatments can be used in combination as needed. The surface treatment method is performed by wet method, dry method such as a mixer, plating, or vapor deposition as needed. Furthermore, a weathering agent, a plasticizer, a flame retardant, an antistatic agent, etc. can also be added as needed.

[0022] For the sintered magnet, components generally blended in the sintered magnet, such as a metal binder, etc., can be blended.

[0023] The member (the second member) constituting the first composite is not particularly limited as long as it is a material durable against the injection molding temperature in the step of forming the second molded body, and examples thereof include magnetic steel materials which are magnetic materials, non-magnetic steel materials which are non-magnetic materials, resins, ceramics, and the like. Among them, magnetic steel materials (yokes) are preferable from the viewpoint of being able to increase the magnetic flux density. As an example of using a magnetic steel material, it is a case where a rare earth magnet is magnetized parallel to the height direction of the first composite, and by using a magnetic steel material, the magnetic flux density can be increased. Further, as an example of using a non-magnetic material, it is a case where a rare earth magnet is magnetized perpendicular to the height direction of the first composite, and by using a non-magnetic material, the leakage magnetic flux near the working surface can be increased. The material constituting the member (the second member) is not the same as the material constituting the rare earth magnet (the first member). For example, the member does not contain magnetic powder. Or, when the member and the rare earth magnet are composed of only the same material, the composition ratio of the material of the member is different from the composition ratio of the material of the rare earth magnet. When the member contains magnetic powder, the mass ratio of the magnetic powder in the whole member can be made smaller than the mass ratio of the magnetic powder in the whole rare earth magnet. When the member contains magnetic powder, the member may contain a different type of magnetic powder (for example, ferrite-based magnetic powder) from the magnetic powder (for example, SmFeN-based magnetic powder) contained in the rare earth magnet. The member may be composed of a plurality of parts. The member may be all parts other than the rare earth magnet in the first composite.

[0024] <Step of manufacturing the second composite> The second composite body is produced by fitting the first molded body to the first composite body so as to cover at least the entire surface of the rare earth magnet in the first composite body. That is, the first molded body covers all of the portions of the surface of the rare earth magnet that coincide with the surface of the first composite body. The first molded body covers all of the surfaces of the rare earth magnet that are exposed from the member (second member). The material of the first molded body is not particularly limited as long as it covers the entire surface of the rare earth magnet, and examples thereof include non-magnetic steel materials, magnetic steel materials, resins, and ceramics. The material constituting the first molded body does not have to be the same as the material constituting the rare earth magnet. For example, the first molded body does not contain magnetic powder. The first molded body is a solid component that can be fitted to the first composite body, and is, for example, a resin molded body.

[0025] The environmental resistance of the first molded body is higher than that of the rare earth magnet. When the first molded body and the rare earth magnet are composed of only the same materials, the composition ratio of the materials of the first molded body can be made different from the composition ratio of the materials of the rare earth magnet. When the first molded body contains magnetic powder, the mass ratio of the magnetic powder in the first molded body can be made smaller than the mass ratio of the magnetic powder in the rare earth magnet. When the first molded body contains magnetic powder, the first molded body may contain a different type of magnetic powder from the magnetic powder contained in the rare earth magnet. The rare earth magnet includes a first magnetic powder that is a rare earth magnetic powder and a first resin, and the first molded body can include a second magnetic powder and a second resin. By the first molded body containing magnetic powder, the magnetic force of the composite member can be improved. In this case, it is preferable to satisfy one or more selected from the following (1) to (3). (1) The mass ratio of the second magnetic powder to the second resin is smaller than the mass ratio of the first magnetic powder to the first resin. (2) The environmental resistance of the second resin is higher than that of the first resin. (3) The environmental resistance of the second magnetic powder is higher than that of the first magnetic powder. Thereby, the magnetic force of the composite member can be improved, and the environmental resistance of the composite member can be improved. As an example of the above (2), using 12 nylon resin as the first resin and polyphenylene sulfide as the second resin can be mentioned. As an example of the above (3), using rare earth magnetic powder as the first magnetic powder and ferrite-based magnetic powder as the second magnetic powder can be mentioned. When the first molded body contains magnetic powder and resin, the content of the resin with respect to the entire first molded body can be 20% by mass or more, and may be 50% by mass or more.

[0026] The rare earth magnet has a first main surface, a second main surface on the side opposite thereto and joined to a member (second member), and side surfaces connecting the first main surface and the second main surface. The first molded body needs to cover the entire surface of the opposite surface (first main surface) and the side surfaces that are not in contact with the member of the rare earth magnet. However, since the adhesion force increases as the contact area with the second molded body increases, it is preferable to cover the entire side surface of the first composite body. The member (second member) of the first composite body has a third main surface joined to the rare earth magnet, a fourth main surface on the side opposite thereto, and side surfaces connecting the third main surface and the fourth main surface. The fourth main surface of the member is exposed from the first molded body.

[0027] FIG. 1A is a perspective view of the disc-shaped composite member 8 of the present embodiment in a mode where the first molded body covers the entire side surface of the first composite body. FIGS. 1B and 1C are cross-sectional views of the A-A' portion of FIG. 1A, with the left side being the A side. In FIGS. 1B and 1C, the solidification shrinkage direction of the injection-molded thermoplastic resin is indicated by an arrow. The shape of the side surface of the first molded body 5 is not particularly limited. However, since the second molded body 7 is less likely to come off, it is preferable that the thickness of the side surface is non-uniform. Such modes include a mode where the side surface has a fold, a mode where the side surface has a protrusion as shown in FIG. 1C, a mode where the side surface has a concave shape, and a mode where the thickness gradually decreases in either the upper or lower direction of the side surface. Since the adhesion force increases as the contact area with the second molded body 7 increases, it is particularly preferable that the first molded body 5 has one or more selected from a fold, a protrusion, and a concave shape. The fold, protrusion, and concave shape of the first molded body 5 are in contact with the second molded body 7.

[0028] FIG. 3A is a perspective view of the ring-shaped composite member 8 of the present embodiment in a mode where the first molded body covers the entire side surface of the first composite body. FIGS. 3B, 3C, and 3D are cross-sectional views of the B-B' portion of FIG. 3A, with the left side being the B side. In FIGS. 3B, 3C, and 3D, the solidification shrinkage direction of the injection-molded thermoplastic resin is indicated by an arrow. The shape of the side surface of the first molded body 5 is not particularly limited, but since the second molded body 7 is less likely to come off, it is preferable that the thickness of the side surface is non-uniform. Such modes include a mode having protrusions as shown in FIG. 3C, a mode having a fold as shown in the side surface on the inner circumference side of the ring in FIG. 3D, a mode having a concave shape on the side surface, and a mode in which the thickness gradually decreases in either the upper or lower direction of the side surface. Since the adhesive force increases due to an increase in the contact area with the second molded body 7, it is particularly preferable that the first molded body 5 has one or more selected from folds, protrusions, and concave shapes. The folds, protrusions, and concave shapes of the first molded body 5 are in contact with the second molded body 7. In FIG. 3D, there is a gap filled with injection-molded thermoplastic resin between the first composite body 4 on the inner circumference side of the ring and the first molded body 5.

[0029] When the first molded body is a resin molded body, the material constituting the resin molded body is not particularly limited as long as it can maintain fitting with the first composite body with respect to the injection molding temperature in the step of forming the second molded body. Examples of the resin constituting the resin molded body include crystalline thermoplastic resins, amorphous thermoplastic resins, and thermosetting resins. Among them, the resin constituting the resin molded body is preferably a crystalline thermoplastic resin. The crystalline thermoplastic resin preferably has a melting point of 120°C or higher and 340°C or lower, and more preferably has a melting point of 250°C or higher and 300°C or lower from the viewpoint of the heat resistance of the obtained composite member. Examples of the thermoplastic resin include polyphenylene sulfide, polyether ether ketone, etc., and polyphenylene sulfide is preferable because of its low water absorption and excellent chemical resistance.

[0030] When the first molded body is a resin molded body, it is preferable that the resin molded body has compatibility with the thermoplastic resin used for injection molding in the step of forming the second molded body. That is, it is preferable that the resin constituting the first molded body has compatibility with the thermoplastic resin used for injection molding in the step of forming the second molded body. Examples of such resins include combinations of resins with a difference in solubility parameter SP value of 3 or less, preferably 2 or less, between the two resins, but it is preferable that they are the same resin. The first molded body consists of, for example, only resin. The method for manufacturing the composite member may include a step of forming the first molded body before the step of manufacturing the second composite. For example, in the step of forming the first molded body, a first molded body having one or more selected from protrusions, folds, and concave shapes and a concave portion for fitting the first composite is formed, and then, in the step of manufacturing the second composite, the first composite is fitted into the concave portion of the first molded body. In the step of forming the first molded body, the first molded body may be formed by injection molding a thermoplastic resin. In this case, the first molded body is formed by injection molding using a mold, the first molded body is taken out from the mold, and then the step of manufacturing the second composite is performed.

[0031] <Step of forming the second molded body> The second composite is inserted into the mold, and the thermoplastic resin is injection molded so as to cover at least all the surfaces of the first composite that are not covered by the first molded body and to be in contact with the first molded body, thereby forming the second molded body. The thermoplastic resin may be injection molded so as to be in contact with the first molded body, but it is preferable to injection mold so as to overlap only a part of the first molded body. For example, Fig. 2C shows a mode in which the thermoplastic resin overlaps the entire side surface of the first molded body. In Fig. 2C, the second molded body 7 covers the lower surface and the side surface of the second composite 6, but does not cover the upper surface of the second composite 6. The shape of the obtained composite member is not particularly limited, and examples include a disc shape and a ring shape.

[0032] In the case of the disk-shaped composite member shown in Fig. 1A, in the aspect of the first molded body 5 shown in Fig. 1B, when the thermoplastic resin injection-molded so as to overlap on the side surface of the first molded body 5 solidifies and shrinks, it shrinks in the direction of the arrows from the left and right, and clamps the first molded body 5, so that the first composite body 4 can be sealed. In the aspect of the first molded body 5 shown in Fig. 1C, compared with the aspect of the first molded body 5 shown in Fig. 1B, since it has protrusions on the side surface, it also solidifies and shrinks in the vertical direction of the protrusions to clamp the first molded body 5, and the first composite body 4 can be firmly sealed.

[0033] In the case of the ring-shaped composite member shown in Fig. 3A, in the aspect of the first molded body 5 shown in Fig. 3B, when the thermoplastic resin injection-molded so as to overlap on the side surface on the outer peripheral side (B) of the ring solidifies and shrinks, it shrinks in the direction of the center of the composite member 8, and seals the first composite body 4. In the aspect of the first molded body 5 shown in Fig. 3C, compared with the aspect of the first molded body 5 shown in Fig. 3B, since it has protrusions on the side surface, it also shrinks in the vertical direction of the protrusions to clamp the first molded body 5, and the first composite body 4 can be firmly sealed. Further, in the aspect of the first molded body 5 shown in Fig. 3D, compared with the aspect of the first molded body 5 shown in Fig. 3B, it has protrusions on the side surface on the outer peripheral side (B) of the ring and has a fold on the side surface on the inner peripheral side (B') of the ring. Also, in the aspect shown in Fig. 3D, before the step of forming the second molded body 7, there is a gap between the fold of the first molded body 5 and the member 2. Then, in the step of forming the second molded body 7, thermoplastic resin is injection-molded into the gap between the fold of the first molded body 5 on the inner peripheral side of the ring and the member 2. When this injection-molded thermoplastic resin solidifies and shrinks, it shrinks in the direction of the center of the composite member 8 and also shrinks in the vertical direction so as to sandwich the fold. Also, in the protrusions on the side surface on the outer peripheral side of the ring, it also shrinks in the vertical direction of the protrusions to clamp the first molded body 5, so that the first composite body 4 can be sealed more firmly.

[0034] The resin used for the injection molded body that becomes the second molded body is not particularly limited, and examples include crystalline thermoplastic resins and amorphous thermoplastic resins. However, due to a large solidification shrinkage rate, crystalline thermoplastic resins are preferred. The thermoplastic resin preferably has a melting point of 120°C or higher and 340°C or lower, and more preferably has a melting point of 250°C or higher and 300°C or lower from the viewpoint of the heat resistance of the obtained composite member. Examples of the thermoplastic resin include polyphenylene sulfide, polyether ether ketone, etc. Polyphenylene sulfide is preferred because of its low water absorption and excellent chemical resistance. For example, the material constituting the second molded body is not the same as the material constituting the rare earth magnet. For example, the second molded body does not contain magnetic powder. Or, when the second molded body and the rare earth magnet are composed of only the same material, the composition ratio of the material of the second molded body is different from the composition ratio of the material of the rare earth magnet. When the second molded body contains magnetic powder, the mass ratio of the magnetic powder in the second molded body can be made smaller than the mass ratio of the magnetic powder in the rare earth magnet. When the second molded body contains magnetic powder, the second molded body may contain a different type of magnetic powder from the magnetic powder contained in the rare earth magnet. The second molded body is composed of, for example, only a thermoplastic resin. When the first molded body contains magnetic powder and the second molded body does not contain magnetic powder, the magnetic force of the composite member can be further improved by the upper surface of the first molded body being exposed from the second molded body.

[0035] <Composite member> The composite member of this embodiment includes a first composite including a rare earth magnet (first member) and a member (second member) in contact with the rare earth magnet, a first molded body that covers at least the entire surface of the rare earth magnet in the first composite, and a second molded body that covers at least the entire surface of the first composite that is not covered by the first molded body and is in contact with the first molded body. Since the entire surface of the first composite including the rare earth magnet is sealed in the composite member of this embodiment, it has excellent environmental resistance (for example, heat resistance, water resistance, oil resistance, hot water resistance, chemical resistance, etc.).

[0036] The composite member can be produced, for example, by the method for producing a composite member of the above-described embodiment. Each component is as described above. The composite member of the present embodiment can adopt, for example, the following configuration. The rare earth magnet is a bonded magnet containing rare earth magnetic powder and a resin. The first molded body has one or more selected from protrusions, folds, and concave shapes. The side surface of the member of the first composite is covered by the first molded body, and the side surface of the first molded body is covered by the second molded body. Alternatively, at least a part of the side surface of the member of the first composite is exposed from the first molded body, and the portion of the side surface of the member exposed from the first molded body is covered by the second molded body.

[0037] Examples of the composite member of the present embodiment are shown in FIGS. 1B, 1C, 3B, 3C, and 3D as described above, and other examples are shown in FIGS. 4A, 4B, 4C, 5A, and 5B. FIGS. 4A to 5B are cross-sectional views showing a part of the composite member and may be adopted for a composite member having a disk shape, a ring shape, or other shapes. FIGS. 4A to 5B show a part of the left side of the composite member, but such a structure may be adopted only on the right side of the composite member or on both the left and right sides. The method for producing the composite member shown in FIGS. 4A to 5B can adopt the same method as the method for producing the composite member described above.

[0038] FIG. 4A is a cross-sectional view showing Modification 1 of the composite member of the present embodiment. In the first molded body 5 shown in FIG. 4A, the corner connecting the upper surface and the side surface has a concave shape recessed toward the inside of the composite member, and a part of the second molded body 7 is provided in the concave portion. The thickness of the portion covering the side surface of the second composite body of the second molded body 7 is greater than the thickness of the portion (upper end portion) provided in the concave shape of the second molded body 7 and the thickness of the portion below it. In other words, the second molded body 7 has a protrusion protruding inward of the composite member at its upper end. Thereby, the second molded body 7 and the second composite body can be fixed more firmly. Also, by increasing the thickness of the second molded body 7, the strength of the composite member can be improved. However, if the thickness of the second molded body 7 in the left-right direction is increased as a whole, one or both of an increase in the size of the composite member in the left-right direction and a decrease in the size of the rare-earth magnet in the left-right direction will occur. As shown in FIG. 4A, by partially increasing the thickness of the second molded body 7, one or both of them can be suppressed, and the strength of the composite member can be improved. By suppressing an increase in the size of the composite member in the left-right direction, an increase in the stirring resistance when the composite member is used as a rotor of a motor can be suppressed. By suppressing a decrease in the size of the rare-earth magnet in the left-right direction, a decrease in the function of the composite member as a magnet can be suppressed. In FIG. 4A, the lower end of the concave portion (corner portion) of the first molded body 5 is located above the upper surface of the first composite body. In other words, the concave portion of the first molded body 5 is located at the portion connecting the portion sandwiched between the side surface of the first composite body and the second molded body 7 and the portion in contact with the upper surface of the first composite body in the first molded body 5. With such a positional relationship, it is easy to provide the protrusion of the second molded body 7 so that the second molded body 7 does not come into direct contact with the first composite body.

[0039] FIG. 4B is a cross-sectional view showing Modification 2 of the composite member of the present embodiment. Similar to Modification 1 shown in FIG. 4A, the first molded body 5 in FIG. 4B has a concave shape recessed toward the inside of the composite member. Thereby, Modification 2 shown in FIG. 4B can obtain the same effect as Modification 1 shown in FIG. 4A. The concave shape in FIG. 4A is a quadrangular shape, while the concave shape in FIG. 4B is a triangular shape.

[0040] FIG. 4C is a cross-sectional view showing a modification 3 of the composite member of the present embodiment. The first molded body 5 shown in FIG. 4C has a plurality of concave shapes recessed toward the inside of the composite member. As a result, it is possible to improve the strength of the composite member by increasing the thickness of the second molded body 7 in the left-right direction without affecting the size of the composite member and / or the rare earth magnet in the left-right direction. Further, since there are a plurality of concave shapes in the first molded body 5, the first composite body can be more firmly sealed by the second molded body 7. In FIG. 4C, the contact interface between the side surface of the first molded body 5 and the second molded body 7 is wavy.

[0041] FIG. 5A is a cross-sectional view showing a modification 4 of the composite member of the present embodiment. The side surface of the member 2 shown in FIG. 5A is not covered by the first molded body 5. The side surface of the member 2 is in contact with the second molded body 7. The side surface of the member 2 is located outside the side surface of the first molded body 5. The portion of the member 2 that protrudes outside the side surface of the first molded body 5 is covered by the second molded body 7. By bringing the side surface of the member 2 into contact with the second molded body 7 in this way, it may be possible to reduce the probability of peeling of the first composite body from the second molded body 7. For example, the configuration of FIG. 5A can be achieved by making the size of the member 2 in the left-right direction larger than the size of the rare earth magnet 1 in the left-right direction. When the side surface of the member 2 is not covered by the first molded body 5 as shown in FIG. 5A, the member 2 cannot be fixed by the first molded body 5. Therefore, in this case, as a method of joining the member 2 and the rare earth magnet 1, a method such as adhesion with an adhesive is used so that the member 2 does not fall off from the rare earth magnet 1.

[0042] FIG. 5B is a cross-sectional view showing Modification 5 of the composite member of the present embodiment. Similar to Modification 4 shown in FIG. 5A, the side surface of the member 2 in FIG. 5B is in contact with the second molded body 7. Accordingly, Modification 5 shown in FIG. 5B can obtain the same effects as Modification 4 shown in FIG. 5A. In FIG. 5B, the side surface of the member 2 has a concave shape, and a part of the second molded body 7 is provided in the concave portion. Thereby, since the second molded body 7 can be partially thickened, an improvement in the strength of the composite member by the second molded body 7 can be expected. In FIG. 5B, the side surface of the member 2 is located inside the side surface of the first molded body 5. The side surface of the member 2 may be located outside the side surface of the first molded body 5, and the side surface of the member 2 may have a concave shape.

[0043] The composite member of the present embodiment is suitable as a rotor of a motor, and the composite member of the present embodiment can be used as a rotor of a motor. The rotor of the motor having the composite member of the present embodiment can be used for an in-vehicle inverter, a water pump of a radiator, a fuel pump, or the like.

Example

[0044] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

[0045] Production Example 1 Production of rare earth bonded magnet To 91.96% by mass of samarium iron nitride magnetic powder (manufactured by Nichia Chemical Industries, Ltd., Z12-C1, average particle size 3 μm), 7.74% by mass of 12 nylon resin powder and 0.3% by mass of phenolic antioxidant powder were mixed with a mixer, and then the mixed powder was put into a twin-screw kneader and kneaded at 210° C. to obtain a kneaded product. After cooling the obtained kneaded product, it was cut into an appropriate size to obtain a composition for bonded magnet. Using the obtained composition for bonded magnet, in a mold for producing a molded product having a diameter of 30 mm and a height of 4 mm, injection molding was performed at 250° C. while applying a magnetic field of 716 kA / m in parallel with the height direction to obtain the rare earth magnet 1 shown in FIG. 2A. The obtained rare earth magnet 1 was multi-pole magnetized in a magnetic field of 3T.

[0046] Production of the first composite On the diamagnetic pole surface of the obtained rare earth magnet, a member 2 (yoke) made of SS400 with a diameter of 30 mm and a height of 2 mm was adsorbed by the magnetic force of the rare earth magnet so that the diameters overlapped, thereby producing a joint surface 3, and a first composite body 4 shown in Fig. 2A was obtained.

[0047] Production of the first molded body A base material made of polyphenylene sulfide was machined on a lathe to obtain a first molded body 5 in the shape of a vessel with a diameter of 32 mm, a height of 7 mm, and a thickness of 1 mm.

[0048] Example 1 Production of the second composite body As shown in Fig. 2B, the first molded body and the first composite body were fitted together to obtain a second composite body 6. The magnetic pole surface sandwiching the first molded body of the second composite body was scanned in the circumferential direction with a Hall element, and the surface magnetic flux density distribution was measured. The maximum value of the surface magnetic flux density distribution was designated as Bm1.

[0049] Production of the second molded body The second composite body 6 was inserted into a mold, and polyphenylene sulfide was injection-molded at 320 °C around the member and the first molded body as shown in Fig. 2C to obtain a composite member 8 having a second molded body 7. The magnetic pole surface sandwiching the first molded body of the second composite body was scanned in the circumferential direction with a Hall element, and the surface magnetic flux density distribution was measured. The maximum value of the surface magnetic flux density distribution was designated as Bm2. The evaluation of thermal degradation (Bm2 / Bm1) was 0.98.

[0050] Comparative Example 1 Production of the second composite body The same first composite body as in Example 1 was inserted into a mold, and polyphenylene sulfide was injection-molded at 320 °C around the first composite body to obtain a second composite body having the same dimensions and structure as in Example 1. Also, for the obtained second composite body, the surface magnetic flux density distribution (Bm1) was measured in the same manner as in Example 1.

[0051] Production of the second molded body A composite member of Comparative Example 1 having a second molded body was obtained for the second composite body obtained by injection molding in the same manner as in Example 1. Thereafter, Bm2 was measured for the composite member of Comparative Example 1. The evaluation of thermal degradation (Bm2 / Bm1) was 0.89, and it was confirmed that the magnetic properties (surface magnetic flux density distribution) of the composite member of Comparative Example 1 were lower than those of the composite member of Example 1.

Industrial Applicability

[0052] For the composite member of the present embodiment, even when a high-temperature resin is injection-molded onto a heat-sensitive permanent magnet, a decrease in magnetic properties can be suppressed, so that it can be suitably applied as a rotor of a motor or the like.

Explanation of Signs

[0053] 1: Rare earth magnet (first member) 2: Member (second member) 3: Bonding surface 4: First composite 5: First molded body 6: Second composite 7: Second molded body 8: Composite member

Claims

1. A step of fitting a first molded body to the first composite body so as to cover at least the entire surface of the rare earth magnet among the first composite body including the rare earth magnet and the member in contact with the rare earth magnet to produce a second composite body, and A method for manufacturing a composite member including a step of inserting the second composite body into a mold, injecting and molding a thermoplastic resin so as to cover at least the entire surface of the first composite body not covered by the first molded body and to be in contact with the first molded body, and forming a second molded body.

2. The method for manufacturing a composite member according to claim 1, wherein the first molded body is a resin molded body and is compatible with the thermoplastic resin of the second molded body.

3. The method for manufacturing a composite member according to claim 1 or 2, wherein in the step of forming the second molded body, the thermoplastic resin is injection molded so as to overlap a part of the first molded body.

4. The method for manufacturing a composite member according to any one of claims 1 to 3, wherein the thermoplastic resin is a crystalline thermoplastic resin.

5. The method for manufacturing a composite member according to any one of claims 1 to 4, wherein in the step of forming the second molded body, the thermoplastic resin is injection molded so that the injection molded thermoplastic resin compresses a part of the first molded body due to solidification shrinkage.

6. The method for manufacturing a composite member according to any one of claims 1 to 5, wherein the first molded body has one or more selected from protrusions, folds, and concave shapes.

7. The method for manufacturing a composite member according to any one of claims 1 to 6, wherein the rare earth magnet is a bonded magnet.

8. The rare earth magnet includes a first magnetic powder which is a rare earth magnetic powder and a first resin, The first molded body includes a second magnetic powder and a second resin, The method for manufacturing a composite member according to claim 7, satisfying one or more selected from the following (1) to (3). (1) The mass ratio of the second magnetic powder to the second resin is smaller than the mass ratio of the first magnetic powder to the first resin. (2) The environmental resistance of the second resin is higher than the environmental resistance of the first resin. (3) The environmental resistance of the second magnetic powder is higher than the environmental resistance of the first magnetic powder.

9. A first composite body including a rare earth magnet and a member in contact with the rare earth magnet, A first molded body that covers at least the entire surface of the rare earth magnet among the first composite body, and A second molded body that covers at least all surfaces of the first composite body that are not covered by the first molded body and that is in contact with the first molded body and has the first molded body contains magnetic powder, a composite member in which the environmental resistance of the first molded body is higher than the environmental resistance of the rare earth magnet. **Claim 10**: A first composite body including a rare earth magnet and a member in contact with the rare earth magnet, a first molded body that covers at least all surfaces of the first composite body that cover the rare earth magnet, and a second molded body that covers at least all surfaces of the first composite body that are not covered by the first molded body and that is in contact with the first molded body and has the rare earth magnet includes a first magnetic powder that is a rare earth magnetic powder and a first resin, the first molded body includes a second magnetic powder and a second resin, a composite member that satisfies one or more selected from the following (1) to (3). (1) The mass ratio of the second magnetic powder to the second resin is smaller than the mass ratio of the first magnetic powder to the first resin. (2) The environmental resistance of the second resin is higher than the environmental resistance of the first resin. (3) The environmental resistance of the second magnetic powder is higher than the environmental resistance of the first magnetic powder. **Claim 11** The composite member according to claim 9 or 10, wherein the first molded body has one or more selected from projections, folds, and concave shapes. **Claim 12** A side surface of the member of the first composite body is covered by the first molded body, The composite member according to any one of claims 9 to 11, wherein a side surface of the first molded body is covered by the second molded body. **Claim 13** At least a part of a side surface of the member of the first composite body is exposed from the first molded body, The composite member according to any one of claims 9 to 11, wherein a portion of the side surface of the member that is exposed from the first molded body is covered by the second molded body. **Claim 14**: A first composite body including a rare earth magnet and a member in contact with the rare earth magnet, a first molded body that covers at least all surfaces of the first composite body that cover the rare earth magnet, and a second molded body that covers at least all surfaces of the first composite body that are not covered by the first molded body and that is in contact with the first molded body and has a rotor of a motor in which a side surface of the first molded body is covered by the second molded body.

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