JP6965609B2 - Sintered body, its manufacturing method, press equipment and resin molding ring - Google Patents

Description

The present invention relates to a sintered body, a method for producing the same, a pressing device and a resin molding ring, and more specifically, a sintered body having a polar anisotropic orientation used in a rotating machine, a method for producing the same, a pressing device and a resin molding. Regarding the ring.

In a rotating machine such as an SPM motor, a magnet rotor having a large amount of magnetic flux is required in order to realize high torque characteristics. Further, in order to realize low cogging torque characteristics, a magnet rotor having a sinusoidal surface magnetic flux density distribution is required. To meet these demands, polar anisotropic sintered ring magnets and polar anisotropic sintered segment magnets are often used as magnet rotors.

Here, a method for manufacturing a polar anisotropic sintered ring magnet is disclosed in Patent Document 1. Patent Document 1 discloses a method of manufacturing a surface multipolar anisotropic ring magnet by providing 6 or more magnetic poles on the outer periphery of a molding space of a molding die, performing molding in a magnetic field, and then sintering the magnet. By this method, a polar anisotropic ring magnet that generates a main magnetic flux on the outer diameter side used for the inner rotor can be obtained.

Further, a method for manufacturing a polar anisotropic segment magnet is disclosed in Patent Document 2. Patent Document 2 has a central ferromagnet arranged apart from the outer arc surface side of the cavity having an arcuate cross section, and a pair of side ferromagnets arranged so as to sandwich the cavity. Using a mold, it is possible to obtain a polar anisotropic segment magnet that generates a main magnetic flux on the outer diameter side used for the inner rotor.

Further, Patent Document 3 discloses the following manufacturing method. First, the magnet raw material is crushed into magnet powder, and the crushed magnet powder and the binder are mixed to produce a compound. Then, the produced compound is formed into a sheet, and an oriented green sheet is produced by applying a magnetic field. Then, the oriented green sheets are laminated, deformed into a shape considering the shape of the final product and the direction of the easy axis of magnetization required in the final product, and sintered to obtain a sintered body. After that, the sintered body is processed to produce a sintered body having a final product shape. As another method, the produced compound is formed into a sheet, oriented, and then punched into a shape in consideration of the shape of the final product and the direction of the easy-sintering axis required for the final product. It is also possible to produce a sintered body by laminating and sintering a shaped molded body, and to produce a sintered body having a final product shape by performing a finishing process.

Japanese Unexamined Patent Publication No. 9-330841 WO2012 / 90841 WO2015 / 186551

However, in Patent Document 1, in order to manufacture a polar anisotropic ring magnet that generates a main magnetic flux on the inner diameter side used for an outer rotor, it is necessary to arrange a yoke and a coil that generate an orientation magnetic field on the inner diameter side. In this case, problems such as how to route the coil leader wire and measures against heat generation occur. In addition, when the number of poles is increased, the teeth of the yoke become narrower, which causes a problem of mold strength. Therefore, it is not easy to manufacture the ring magnet as an extension of the conventional technique.

When a polar anisotropic segment magnet that generates a main magnetic flux on the inner diameter side is manufactured by using the method of Patent Document 2, it is not easy to obtain a Halbach-like orientation distribution only by arranging ferromagnets, and the outer rotor is used. It is difficult to fabricate a polar anisotropic segment magnet that generates a main magnetic flux on the inner peripheral side to be used.

By any of the above methods of Patent Document 3, it is possible to produce a polar anisotropic segment magnet that generates a main magnetic flux on the outer diameter side or the inner diameter side. However, the former method of Patent Document 3 has a problem that the material is wasted and the processing yield is poor, and the latter method has a problem that there are many steps until a sintered body having a final product shape is obtained.
Therefore, the main object of the present invention is a sintered body that is polar anisotropic oriented so as to generate a main magnetic flux on the inner diameter side and a firing that is polar anisotropic oriented so as to generate a main magnetic flux on the outer diameter side. A method and press device for producing a sintered body, a sintered body that can be preferably produced, and easy It is to provide a resin molding ring which can be manufactured in the above.

In order to achieve the above-mentioned objectives, a die having a through hole penetrating in the vertical direction and having an arcuate cross-section, a lower punch inserted into the through hole of the die and forming a cavity of the upper surface opening together with the die, and an upper part of the cavity. An upper punch that can be inserted from the side, a pair of yokes that are provided on both side surfaces of the die so as to sandwich the cavity from the side, and a pair of yokes that are provided on the side surface side that comes into contact with the die in each of the pair of yokes and have a cavity. It is provided with a pair of coils that are arranged so as to sandwich each other, and the cross-sectional shape of the cavity is such that the pair of coils are located at intervals from each other in the first direction facing each other and are orthogonal to the first direction. The extending first arc portion and second arc portion, the first side portion connecting one end portions of the first arc portion and the second arc portion, and the other end portion of each of the first arc portion and the second arc portion. It has an arc shape including a second side portion connecting the two arcs, the first arc portion is closer to the side surface of the die than the second arc portion, and the cavity is one of the centers of the die in the first direction. Provided is a press device provided on the coil side of the above, in which a current is passed through the pair of coils so that the alignment magnetic fields generated by the pair of coils have opposite polarities when the alignment magnetic field is applied.

Further, a die having a through hole penetrating in the vertical direction and having an arcuate cross-section, a lower punch inserted into the through hole of the die and forming a cavity with an upper surface opening together with the die, and an upper punch that can be inserted into the cavity from above. The punch and a pair of yokes provided on both side surfaces of the die so as to sandwich the cavity from the side, and a pair of yokes provided on the side surface side in contact with the die in each of the pair of yokes and arranged to face each other so as to sandwich the cavity. A pair of coils are provided, and the cross-sectional shapes of the cavities are located at intervals in the first direction orthogonal to the vertical direction and extend in the second direction orthogonal to the first direction, respectively. An arc portion, a first side portion connecting one end portions of the first arc portion and the second arc portion, and a second side portion connecting the other end portions of the first arc portion and the second arc portion. A press device having an arc shape including, the first arc portion is closer to the side surface of the die than the second arc portion, and the cavity is provided on one of the coil sides of the die than the center in the first direction. This is a method for manufacturing a sintered body using the above method, in which the step of filling the cavity with magnet powder and the upper punch are lowered toward the cavity so that the orientation magnetic fields generated by the pair of coils have opposite polarities. A step of applying an alignment magnetic field to the magnet powder in the cavity by passing a current through a pair of coils to orient the magnet powder, a step of further lowering the upper punch to obtain a molded body, and a step of obtaining a molded body. Provided is a method for producing a sintered body, which comprises a step of sintering to obtain a sintered body having a polar anisotropic orientation.

In the present invention, when a current is passed through a pair of coils so that the alignment magnetic fields generated by the pair of coils have opposite polarities when the alignment magnetic field is applied, the alignment magnetic fields generated by each coil and passing through the die are mutually opposite. Repel each other. As a result, the alignment magnetic field of one coil mainly passes through one coil side of the center of the die in the first direction, and the alignment magnetic field of the other coil mainly passes through the other coil side of the center of the die in the first direction. Pass through. Here, the cavity is provided on one of the coil sides of the die with respect to the center in the first direction, and the first arc portion is provided closer to the side surface of the die than the second arc portion. Therefore, the magnet powder filled in the cavity is entered from the first arc portion toward the cavity and exited from the first side portion and the second side portion toward the cavity based on the direction of the current flowing through the pair of coils. Alternatively, an orientation magnetic field is applied so as to enter from the first side and the second side and exit from the first arc and away from the cavity. That is, a magnetic field passing through the first arc portion and the first side portion and a magnetic field passing through the first arc portion and the second side portion are applied to the magnet powder filled in the cavity, and the magnet powder is oriented. Then, a molded body is obtained by pressing the magnet powder with the upper punch and the lower punch, and by sintering the molded body, the easily magnetized shaft is focused from the first side surface and the second side surface toward the first arc surface. As described above, a sintered body oriented in polar anisotropy can be obtained. Here, when the first arc portion of the cavity is made to correspond to the inner diameter side of the molded body obtained by the press device, the molded body and the sintered body which are polar anisotropically oriented so as to generate a main magnetic flux on the inner diameter side are obtained. It can be easily manufactured. On the other hand, when the first arc portion of the cavity corresponds to the outer diameter side of the molded body, the molded body and thus the sintered body are polar anisotropically oriented so as to generate a main magnetic flux on the outer diameter side. Can be easily produced. In addition, since the shape of the molded body is pre-designed to be a sintered body in consideration of the final product shape and the processing allowance after sintering, the processing yield when processing from the sintered body to the final product shape is high. It will be good. Further, as in Patent Document 3, after the compound is molded into a sheet shape, the compound is punched in advance into a shape considering the shape of the final product and the direction of the easy-to-magnetize axis required for the final product, and further punched into the sheet-shaped molded product. Since the step of laminating is not required, the number of steps for obtaining the sintered body can be reduced.

According to the above-mentioned method for manufacturing a sintered body, the first arc plane and the second arc plane which are arcuate in cross section and are spaced apart from each other, and one end of each of the first arc plane and the second arc plane are formed. A first side surface to be connected and a second side surface to connect the other ends of the first arc surface and the second arc surface are included, and the easily magnetized axis is directed from the first side surface and the second side surface to the first arc surface. A sintered body that is polar anisotropically oriented so as to be focused can be suitably produced.

Preferably, the die is formed with a pair of cavities sandwiched between a pair of coils, and the pair of cavities are provided symmetrically with respect to a center line in the die that passes through the center of the first direction and extends in the second direction. In this case, the pair of cavities are formed so that their second arcs face each other, one cavity is provided on one coil side of the center of the die in the first direction, and the other cavity is. It is provided on the other coil side of the die from the center in the first direction, and each cavity is provided so that the first arc portion is closer to the side surface of the die than the second arc portion. Therefore, the magnet powder filled in each cavity has a similar orientation magnetic field, i.e., entering from the first arc and exiting from the first and second sides towards the cavity, or the first side. And the alignment magnetic field is applied so as to enter from the second side and exit from the first arc and away from the cavity. As a result, from the molded product obtained in each cavity, it is possible to easily produce a sintered body in which the easily magnetized shaft is polar-anisotropically oriented so as to focus from the first side surface and the second side surface toward the first arc surface. , Productivity can be improved.

It is also preferable that a plurality of pairs of cavities are formed in parallel in the second direction on the die, and a pair of cavities are sandwiched between the pairs of cavities on the side surface side of each of the pair of yokes in contact with the die. A pair of coils are arranged so as to face each other, and when an alignment magnetic field is applied, a current is passed through the coils so that the alignment magnetic fields generated by the adjacent coils in the second direction have the same polarity. In this case, from the molded products obtained in the plurality of cavities, a sintered body in which the easily magnetized axis is focused from the first side surface and the second side surface toward the first arc surface can be easily produced. It can be done, and productivity can be further improved.

More preferably, the distance between the first arc portion and the second arc portion of the cavity is larger in the central portion than in both ends in the second direction of the cavity. When the arcuate molded body oriented in polar anisotropy is sintered, the shrinkage rate is larger in the central portion than in the arc direction end portion of the molded body. Therefore, by setting the distance between the first arc portion and the second arc portion of the cavity to be larger in the central portion than in both ends in the second direction of the cavity, the molded product obtained in the cavity can be obtained in advance. The thickness can be set so that the central portion is larger than the arc direction end portion. When this molded product is sintered, the thickness of the end portion in the arc direction and the thickness of the central portion of the sintered body can be made substantially equal due to the difference in shrinkage ratio. In this way, by setting the shape of the cavity in advance so that the sintered body obtained by sintering the molded body has a desired shape (for example, equal meat), the sintered body having a desired shape is obtained. Is obtained.

Preferably, the die is made of a non-magnetic cemented carbide. In this case, the orientation magnetic field generated by the pair of coils can be easily guided to the cavity filled with the magnet powder, and the magnet powder can be easily oriented.

Further, preferably, the first arc portion corresponds to the inner diameter side of the molded body obtained by the press device, and the second arc portion corresponds to the outer diameter side of the molded body. In this case, a sintered body for an outer rotor that is polar-anisotropically oriented so as to generate a main magnetic flux on the inner diameter side can be easily manufactured.

Further, preferably, the first arc portion corresponds to the outer diameter side of the molded body obtained by the press device, and the second arc portion corresponds to the inner diameter side of the molded body. In this case, a sintered body for an inner rotor oriented so as to generate a main magnetic flux on the outer diameter side can be easily manufactured.

Preferably, the distance in the second direction from the center of the cavity located at the farthest end in the second direction to the end of the yoke on the cavity side is between the centers of the cavities adjacent to each other in the second direction in the second direction. It is 1/2 of the distance. In this case, the alignment magnetic field applied to the cavity located at the end in the second direction and the alignment magnetic field applied to the other cavities are the same, so that a similar molded body can be obtained in each cavity. , A sintered body having the same polar anisotropy orientation can be easily produced.

Further, preferably, the second arc portion has a convex portion protruding into the cavity at the central portion in the second direction. In this case, a notch (recess) is formed in the central portion of the second arc surface (the surface corresponding to the second arc portion of the cavity) of the molded body formed in the cavity. Here, when the alignment magnetic field is applied, the magnet powder filled in the cavity enters the cavity from the first arc portion and exits from the first side portion and the second side portion, or the first side portion and the first side portion. The alignment magnetic field is applied so as to enter from the two side portions and exit from the first arc portion and away from the cavity, and almost no alignment magnetic field is applied to the central portion of the second arc portion. Therefore, the central portion of the second arc surface of the molded body formed in the cavity does not contribute so much to the formation of the main magnetic flux, and the central portion of the second arc surface of the molded body can be scraped. Therefore, by forming a convex portion protruding into the cavity at the central portion of the second arc portion of the cavity in the second direction, a molded product having a notch formed at the central portion of the second arc surface can be obtained. As a result, the amount of magnet material used can be reduced and the cost can be reduced without reducing the surface magnetic flux density of the sintered segment magnet produced from the molded body.

Preferably, in the sintered body, the first arc plane is on the inner diameter side and the second arc plane is on the outer diameter side. In this case, a sintered body for an outer rotor that is polar-anisotropically oriented so as to generate a main magnetic flux on the inner diameter side can be obtained.

Further, preferably, in the sintered body, the first arc plane is on the outer diameter side and the second arc plane is on the inner diameter side. In this case, a sintered body for an inner rotor that is polar-anisotropically oriented so as to generate a main magnetic flux on the outer diameter side can be obtained.

More preferably, in the sintered body, the second arc plane has a notch formed in the central portion thereof. In this way, in the polar anisotropic oriented sintered body, the surface magnetic flux density is almost reduced by forming a notch in the center of the second arc surface on the opposite side of the first arc surface (magnetic pole surface) in the arc direction. A sintered segment magnet can be obtained in which the amount of magnet material used can be reduced without reducing the amount. Further, the notch can be used for positioning and rotation stop when forming the rotor.

Further, a plurality of the above-mentioned sintered bodies arranged in a ring shape and a resin mold member for holding the plurality of sintered bodies are provided, and the adjacent sintered bodies are the first side surface of one sintered body and the other. A resin molding ring is provided in which the second side surface of the sintered body of the above is arranged so as to be adjacent to each other at a distance.

In the present invention, a plurality of sintered bodies are resin-molded and held by a resin mold member, so that a resin mold ring can be easily manufactured with a small number of manufacturing man-hours.

Preferably, in the resin mold ring, the resin mold member holds a plurality of sintered bodies so that the first arc surface and the second arc surface are exposed. In this case, when the sintered ring magnet obtained by magnetizing the resin mold ring is assembled as a rotor, the gap between the first arc surface of the sintered ring magnet and the stator can be reduced, and the motor characteristics can be improved. can. Further, another member (for example, a reinforcing ring or a driven member) can be firmly attached to the sintered ring magnet via the second arc surface.

Further, preferably, in the resin molding ring, each sintered body has a connection portion between the first arc surface and the first side surface, a connection portion between the first arc surface and the second side surface, and a second arc surface and the first side surface. A chamfered portion formed at at least one of a connecting portion and a connecting portion between the second arc surface and the second side surface is included, and the chamfered portion is covered with the resin mold member. In this case, it is possible to prevent each sintered body from falling off from the resin mold member.

More preferably, when each sintered body has a notch formed in the central portion of the second arc surface in the resin molding ring, the notch can be used for positioning each sintered body. Further, in the sintered ring magnet obtained by magnetizing a resin mold ring containing a sintered body having a notch, the dimensional accuracy of the inner and outer diameters is improved and the variation in the surface magnetic flux density distribution is reduced.

According to the present invention, either a sintered body that is polar-anisotropically oriented so as to generate a main magnetic flux on the inner diameter side or a sintered body that is polar-anisotropically oriented so as to generate a main magnetic flux on the outer diameter side. Even if it is, it can be easily produced, the processing yield is good, the number of steps until the sintered body is obtained can be reduced, and the resin mold ring can be easily produced.

A press device according to an embodiment of the present invention is shown, (a) is a perspective view thereof, and (b) is a sectional perspective view taken along line AA of (a). It is sectional drawing which shows the main part of the press apparatus of FIG. 1 and an example of an orientation magnetic field. It is sectional drawing which shows the vicinity of the cavity of the press apparatus of FIG. 1 enlarged. (A) is a schematic diagram showing an example of a molded body, a sintered body, a sintered body after processing, and an orientation direction thereof obtained by using the press device of FIG. 1, and (b) is a sintered body after processing. It is a perspective view which shows. A polar anisotropic ring magnet formed by using a polar anisotropically oriented sintered body is shown, (a) is a plan view thereof, and (b) is a side view thereof. It is a graph which shows the surface magnetic flux density distribution of the polar anisotropy ring magnet shown in FIG. It is sectional drawing which shows the main part of the press apparatus of another embodiment of this invention, and an example of an orientation magnetic field. FIG. 6 is an enlarged cross-sectional view showing the vicinity of the cavity of the press device of FIG. 7. (A) is a schematic diagram showing an example of a molded body, a sintered body, a sintered body after processing, and an orientation direction thereof obtained by using the press device of FIG. 7, and (b) is a sintered body after processing. It is a perspective view which shows. It is sectional drawing which shows the deformation example of the cavity in the press apparatus of FIG. (A) is a schematic diagram showing an example of a molded body, a sintered body, a sintered body after processing, and an orientation direction thereof obtained by using the press device having the cavity of FIG. 10, and (b) is a diagram after processing. It is a perspective view which shows the sintered body. (A) is a graph showing the relationship between the surface magnetic flux density change rate and the volume change rate in the molded product, and (b) shows the relationship between the surface magnetic flux density change rate and the volume change rate in the sintered body after processing. It is a graph. It is sectional drawing which shows the deformation example of the cavity in the press apparatus of FIG. (A) is a schematic diagram showing an example of a molded body, a sintered body, a sintered body after processing, and an orientation direction thereof obtained by using the press device having the cavity of FIG. 13, and (b) is a diagram after processing. It is a perspective view which shows the sintered body. It is a perspective view which shows an example of a resin molding ring. An example of the resin molding ring is shown, (a) is a plan view thereof, and (b) is a front view thereof. (A) is a schematic diagram showing a sintered body to be resin-molded, and (b) is a graphic diagram for explaining a method of manufacturing a resin mold ring. (A) is a graph showing the surface magnetic flux density waveform of the adhesive fixing ring magnet, and (b) is a graph showing the surface magnetic flux density waveform of the resin molded ring magnet. (A) is a graph showing the distribution of the surface magnetic flux density peak on the inner diameter side of the adhesive fixing ring magnet, and (b) is a graph showing the distribution of the surface magnetic flux density peak on the inner diameter side of the resin molded ring magnet.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

With reference to FIGS. 1 and 2, the press apparatus 10 according to the embodiment of the present invention includes molded bodies E1 and sintered bodies E2 and E3 (polarly anisotropically oriented so as to generate a main magnetic flux on the inner diameter side). A device used to manufacture (see FIG. 4), which includes a die 12, a plurality of (6 in this embodiment) lower punch 14, a plurality (6 in this embodiment) upper punch 16, and a pair. Includes yokes 18a, 18b, coil 20 (in this embodiment, six poles are generated).

The die 12 is made of, for example, a non-magnetic cemented carbide and is formed in a substantially square plate shape and is erected. The die 12 is provided with a plurality of (six in this embodiment) through holes 22 that penetrate in the vertical direction and have an arcuate cross section. Two through holes 22 are provided in the first direction (indicated by arrow X), which is the lateral direction of the die 12, and three through holes 22 are provided in the second direction (indicated by arrow Y), which is the longitudinal direction of the die 12. It is formed, and a total of 6 through holes 22 are formed in the die 12. The first direction and the second direction are orthogonal to each other.

Further, a protrusion 26a for positioning the yoke 18a is provided below the side surface 24a of the die 12, and a protrusion 26b for positioning the yoke 18b is provided below the side surface 24b of the die 12.

The lower punch 14 is inserted into the through hole 22 of the die 12, and the die 12 and the lower punch 14 form a cavity 28 having an upper surface opening. Therefore, the cavities 28 are formed in the through holes 22 of the die 12, and the two cavities 28 are formed in the first direction (indicated by the arrow X) which is the lateral direction of the die 12, and the two cavities 28 are in the second direction which is the longitudinal direction of the die 12. Three cavities 28 are formed in (indicated by arrow Y), and a total of six cavities 28 are formed in the die 12. Details of the cavity 28 will be described later. The upper punch 16 is provided in the cavity 28 so as to be insertable from above. The cross-sectional shapes of the lower punch 14 and the upper punch 16 are substantially equal to the cross-sectional shapes of the cavity 28.

A pair of yokes 18a and 18b are provided on both side surfaces 24a and 24b of the die 12 in the first direction so as to sandwich the cavities 28 formed in the die 12 from the side (first direction). The pair of yokes 18a and 18b are formed in the shape of a square plate made of a magnetic material such as SS400 or a silicon steel plate, and are locked and positioned at the upper ends of the protrusions 26a and 26b. The dimensions of the pair of yokes 18a and 18b in the second direction are equal to the dimensions of the die 12 in the second direction. , The other end 24d of the die 12 and the other ends 32a, 32b of the pair of yokes 18a, 18b in the second direction are formed flush with each other in the first direction. Will be done. A presser plate (not shown) made of a non-magnetic material such as SUS304 is provided so as to surround the die 12 and the pair of yokes 18a and 18b, and a mold is formed.

Further, on the side surfaces 34a and 34b of each of the pair of yokes 18a and 18b that come into contact with the die 12, grooves 36a and 36b for accommodating the coil 20 are formed at each position corresponding to the cavity 28. The coil 20 is housed in each of the grooves 36a and 36b. In this way, the plurality of coils 20 are provided on the side surfaces 34a and 34b of the pair of yokes 18a and 18b, and the pair of coils are arranged so as to sandwich the pair of cavities 28 for each pair arranged in the first direction of the cavities 28. 20 are arranged to face each other.

Here, the cavity 28 will be described.

The pair of cavities 28 formed on the die 12 and sandwiched between the pair of coils 20 are provided at symmetrical positions with respect to the center line P1 that passes through the center of the die 12 in the first direction and extends in the second direction. A plurality of such pairs of cavities 28 (three pairs in this embodiment) are formed in the die 12 in parallel in the second direction. Each cavity 28 is provided on one coil 20 side or the other coil 20 side in the first direction from the center (center line P1) in the first direction of the die 12.

With reference to FIG. 3, the cross-sectional shape of the cavity 28 is a molded body in which the orientation direction of polar anisotropy and the shrinkage ratio in the direction parallel to the orientation direction and the direction perpendicular to the orientation direction are taken into consideration in advance. After sintering, it is designed to be a sintered body in consideration of the final product shape and processing allowance. The cross-sectional shape of the cavity 28 is an arc shape such that the central portion of the cavity 28 is closer to the center line P1 than both ends of the cavity 28, and the pair of coils 20 are located at intervals in the first direction facing each other. The first arc portion 38a and the second arc portion 38b extending in the second direction, the first side portion 38c connecting one end portions of the first arc portion 38a and the second arc portion 38b, and the first arc portion 38a, respectively. And a second side portion 38d connecting the other ends of each of the second arc portions 38b. The second arc portion 38b is formed so as to be curved so that the central portion approaches the center line P1 (bulges toward the center line P1) from both end portions thereof. Regarding the first arc portion 38a, the vicinity of both ends of the first arc portion 38a is formed substantially parallel to the vicinity of both ends of the second arc portion 38b, but the central portion of the first arc portion 38a is away from the center line P1 ( It is formed so as to be curved so as to bulge on the side opposite to the center line P1). Therefore, the distance between the first arc portion 38a and the second arc portion 38b in the cavity 28 is larger at the central portion D2 than at both end portions D1 in the second direction.

Of the pair of cavities 28 arranged in the first direction, for the cavities 28 located on the yoke 18a side, the first arc portion 38a is closer to the side surface 24a of the die 12 than the second arc portion 38b, and is closer to the yoke 18b side. Regarding the cavities 28 to be located, the first arc portion 38a is closer to the side surface 24b of the die 12 than the second arc portion 38b. That is, the pair of cavities 28 are formed so that the second arc portions 38b face each other. Further, the distance from the center of the cavity 28 located at the farthest end in the second direction to the end of the die 12 on the cavity 28 side (for the cavity 28 located at the left end in FIG. 2, the cavity 28 The distance D3 in the second direction from the center of the second direction to the ends 30a and 30b of the yokes 18a and 18b is 1/2 of the distance D4 between the centers of the cavities 28 adjacent to each other in the second direction in the second direction. In this embodiment, the first arc portion 38a corresponds to the inner diameter side of the molded body E1 obtained in the cavity 28, and the second arc portion 38b corresponds to the outer diameter side of the molded body E1.

A method of manufacturing a molded body E1 (sintered body E2, E3) using such a press device 10 will be described.

First, the cavity 28 of the press device 10 is filled with magnet powder from above. As the magnet powder, for example, an alloy powder for Nd-Fe-B-based sintered magnets is used.

Then, the upper punch 16 is lowered toward the cavity 28, and at least the upper surface of the cavity 28 is closed by the upper punch 16, and then the magnet powder in the cavity 28 is entered from the first arc portion 38a and the first side portion. An alignment magnetic field emitted from 38c and the second side 38d is applied to orient the magnet powder. When the alignment magnetic field is applied, the alignment magnetic fields generated by the pair of coils 20 facing each other in the first direction have opposite polarities to each other, and the alignment magnetic fields generated by the adjacent coils 20 in the second direction are mutually opposite. A current is passed through each coil 20 so as to have the same polarity. Thereby, a symmetric magnetic field can be applied to the center line P1 and a symmetric magnetic field can be applied to the center line P2 passing through the center of the second direction and parallel to the first direction in each cavity 28. .. Preferably, a pulse current generated by capacitor discharge is passed through the coil 20, whereby a pulse magnetic field is applied to orient the magnet powder. The direction of the current flowing through each coil 20 when the alignment magnetic field is applied is reversed from the above-mentioned case, and the cavity 28 enters from the first side portion 38c and the second side portion 38d and exits from the first arc portion 38a. An alignment magnetic field may be applied to orient the magnet powder.

Then, the upper punch 16 is further lowered so as to have a predetermined molded body density. As a result, the molded product E1 (see FIG. 4A) is obtained. Sintering the molded body E1 gives the sintered body E2 (see FIG. 4 (a)), and the processed body E3 is processed and surface-treated to obtain the sintered body E3 (see FIG. 4 (a)). Is obtained. That is, the first side surface 40c which has an arcuate cross section and connects one ends of the first arc surface 40a and the second arc surface 40b and the first arc surface 40a and the second arc surface 40b which are spaced apart from each other. And a second side surface 40d connecting the other ends of the first arc surface 40a and the second arc surface 40b, and the easy-to-magnetize axis is changed from the first side surface 40c and the second side surface 40d to the first arc surface 40a. A sintered body E3 (see FIG. 4B), which is polar anisotropically oriented so as to focus toward the inner diameter side and the first arc surface 40a is on the inner diameter side and the second arc surface 40b is on the outer diameter side, is preferable. Can be made into. FIG. 4A also shows the orientation directions of the molded body E1 and the sintered bodies E2 and E3.

In this embodiment, the sintered bodies E3 are arranged in the circumferential direction and connected in a ring shape, and then NS is alternately magnetized to have a pole on the inner diameter side as shown in FIG. 5 and generate a main magnetic flux on the inner diameter side. It becomes a sintered ring magnet 100 having polar anisotropy, and is used for an outer rotor. The sintered body E3 magnetized at this time corresponds to a polar anisotropic sintered segment magnet. In the figure, the direction of the magnetic flux of the magnet is indicated by an arrow.

FIG. 6 shows the surface magnetic flux density distribution of the inner and outer diameters of the sintered ring magnet 100 thus constructed. A Gauss meter was used for the measurement. Here, for the sintered ring magnet 100 having an outer diameter (diameter) of 80 mm, an inner diameter (diameter) of 74 mm, and a height of 12 mm, the surface magnetic flux density on the inner diameter side is measured at the center in the axial direction and 0.5 mm from the inner surface. The surface magnetic flux density on the outer diameter side was measured at the center in the axial direction and at a position 1.5 mm from the outer surface. The surface magnetic flux density distribution on the inner diameter side is substantially sinusoidal as shown by the solid line, while the surface magnetic flux density distribution on the outer diameter side is approximately 0 as shown by the broken line. As described above, the sintered ring magnet 100 is substantially oriented in Halbach, and it is possible to design a motor without a back yoke.

According to the press device 10, when a current is passed through the pair of coils 20 so that the alignment magnetic fields generated by the pair of coils 20 have opposite polarities when the alignment magnetic field is applied, the current is generated by each of the pair of coils 20. Then, the oriented magnetic fields passing through the die 12 repel each other. As a result, the alignment magnetic field by one coil 20 mainly passes through one coil 20 side from the center (center line P1) of the first direction in the die 12, and the alignment magnetic field by the other coil 20 mainly passes through the first coil 12 in the die 12. It passes through the other coil 20 side from the center in one direction. Here, the cavity 28 is provided on one of the coils 20 side of the die 12 in the first direction, and the first arc portion 38a is closer to the side surface of the die 12 than the second arc portion 38b. It is provided so as to be close to. Therefore, the magnet powder filled in the cavity 28 enters from the first arc portion 38a toward the cavity 28 and enters the first arc portion 38a and the first side portion 38c and the second side portion based on the direction of the current flowing through the pair of coils 20. An orientation magnetic field is applied so as to exit the 38d, or enter from the first side 38c and the second side 38d and exit the first arc 38a and away from the cavity 28. That is, a magnetic field passing through the first arc portion 38a and the first side portion 38c and a magnetic field passing through the first arc portion 38a and the second side portion 38d are applied to the magnet powder filled in the cavity 28, and the magnet powder is applied. Is oriented. Then, the molded body E1 is obtained by pressing the magnet powder with the upper punch 16 and the lower punch 14, and the easily magnetized shaft is transferred from the first side surface 40c and the second side surface 40d by sintering and further processing the molded body E1. A sintered body E3 that is polar-anisotropically oriented so as to be focused toward the first arc plane 40a is obtained. Here, when the first arc portion 38a of the cavity 28 is made to correspond to the inner diameter side of the molded body E1 obtained by the press device 10 and the second arc portion 38b is made to correspond to the outer diameter side of the molded body E1, it is mainly on the inner diameter side. Molded bodies E1 and thus sintered bodies E2 and E3 for an outer rotor oriented so as to generate magnetic flux can be easily manufactured. Since the molded body E1 is pre-designed to be the sintered body E2 in consideration of the final product shape and the processing allowance after sintering, the processing yield when processing the sintered body E2 to the final product shape E3 is high. It will be good. In addition, after the compound is molded into a sheet shape, it is punched in advance into a shape that takes into consideration the shape of the final product and the direction of the easy-to-magnetize axis required for the final product, and then the punched sheet-shaped molded product is laminated. Since it is not required, the number of steps for obtaining the sintered body E3 can be reduced.

The pair of cavities 28 are formed so that their second arc portions 38b face each other, and one cavity 28 is provided on one coil 20 side of the center of the die 12 in the first direction and the other cavity 28. The 28 is provided on the other coil 20 side of the die 12 in the first direction, and each cavity 28 is closer to the nearest side surface of the die 12 in the first arc portion 38a than in the second arc portion 38b. It is provided so as to be. Therefore, the magnet powder filled in each cavity 28 has a similar orientation magnetic field, that is, entering from the first arc portion 38a toward the cavity 28 and exiting from the first side portion 38c and the second side portion 38d. Alternatively, an orientation magnetic field is applied so as to enter from the first side portion 38c and the second side portion 38d and exit from the first arc portion 38a and away from the cavity 28. As a result, from the molded body E1 obtained in each cavity 28, the sintered body is polar-anisotropically oriented so that the easy-magnetizing axis is focused from the first side surface 40c and the second side surface 40d toward the first arc surface 40a. E3 can be easily produced and productivity can be improved.

A plurality of pairs of cavities 28 are formed in parallel in the second direction on the die 12, and from the molded body E1 obtained in each cavity 28, the easy-to-magnetize axes are the first side surface 40c and the second side surface 40d to the first arc surface. The sintered body E3 that is polar-anisotropically oriented so as to be focused toward 40a can be easily produced, and the productivity can be further improved.

Since D3 = D4 / 2 in the yokes 18a and 18b, the alignment magnetic field applied to the cavity 28 located at the end in the second direction and the alignment magnetic field applied to the other cavities 28 are the same. Therefore, the same molded body E1 can be obtained in each cavity 28, and the same polar anisotropic oriented sintered bodies E2 and E3 can be easily produced.

By setting the distance between the first arc portion 38a and the second arc portion 38b of the cavity 28 so that the central portion is larger than both ends in the second direction of the cavity 28, the cavity 28 can be obtained in advance. The thickness of the molded body E1 can be set so that the central portion is larger than the arc direction end portion. When the molded body E1 is sintered, the thickness of the arc direction end portion and the thickness of the central portion of the sintered body E2 can be made substantially equal due to the difference in shrinkage ratio. In this way, by setting the shape of the cavity 28 in advance so that the sintered body E2 obtained by sintering the molded body E1 has a desired shape (for example, equal meat), the desired shape can be obtained. The sintered body E2 is obtained.

Since the die 12 is made of a non-magnetic cemented carbide, the alignment magnetic field generated by the pair of coils 20 can be easily guided to the cavity 28 filled with the magnet powder, and the magnet powder can be easily oriented.

A pulse current generated by capacitor discharge is passed through the coil 20, and the magnet powder can be satisfactorily oriented by applying a pulse magnetic field to orient the magnet powder.

Since the segment-shaped molded body E1 is sintered, unlike the case where the ring-shaped molded body is sintered, the stress during sintering is small and cracks and cracks are unlikely to occur, so that the sintered body E2 can be easily obtained. Can be done.

Further, in the rotor configured by using the segment-shaped sintered body E3 that is polar-anisotropically oriented, the orientation direction of the adjacent sintered bodies (sintered segment magnets) at the connection surface (inter-pole position) is set. The direction is perpendicular to the connection surface, and an orientation angle distribution close to the Halbach array can be constructed. Therefore, in the rotor, a surface magnetic flux density distribution having a sinusoidal shape and a high peak can be obtained on the magnetic flux generating surface, and good low cogging torque characteristics and high torque characteristics can be obtained. In addition, since the leakage flux is reduced on the surface opposite to the magnetic flux generating surface, the magnetic back yoke for forming the magnetic path is not required, so that the inertia of the rotor can be reduced and a highly responsive rotor can be obtained. Be done.

Further, the press device 10a of another embodiment of the present invention will be described with reference to FIG. 7. The press device 10a is a device used for manufacturing molded bodies F1 and sintered bodies F2 and F3 (see FIG. 9) that are polar-isolated so as to generate a main magnetic flux on the outer diameter side. The difference from the press device 10 shown in 1 and 2 is that the die 12a is used instead of the die 12, and the lower punch and the upper punch for the die 12a are used instead of the lower punch 14 and the upper punch 16 (both not shown). The point is that the coil position is changed according to the shape of the molded body. The difference between the die 12a and the die 12 is that the through hole 22a is formed instead of the through hole 22. That is, the press device 10a differs from the press device 10 in that the cavity 28a is formed instead of the cavity 28, and includes the lower punch and the upper punch for the cavity 28a instead of the lower punch 14 and the upper punch 16. ..

Also referring to FIG. 8, what makes the cavity 28a different from the cavity 28 is its cross-sectional shape. The cross-sectional shape of each cavity 28a is an arc shape in which the central portion is farther from the center line P1 than both ends of the cavity 28a, and the pair of coils 20 are opposed to each other in the first direction (indicated by arrow X). The first arc portion 42a and the second arc portion 42b, which are located at intervals and extend in the second direction (indicated by the arrow Y), and one end of each of the first arc portion 42a and the second arc portion 42b are connected. The first side portion 42c and the second side portion 42d connecting the other ends of the first arc portion 42a and the second arc portion 42b are included. Each of the first arc portion 42a and the second arc portion 42b is formed so as to be curved so that the central portion is away from the center line P1 (bulges to the side opposite to the center line P1) from both end portions. The distance between the first arc portion 42a and the second arc portion 42b in the cavity 28a is larger in the central portion D6 than in the gap D5 at both ends in the second direction. The lower punch and upper punch of the press device 10a are different from the lower punch 14 and upper punch 16 of the press device 10 in the cross-sectional shape thereof, and the cross-sectional shape of the lower punch and upper punch of the press device 10a is the cross section of the cavity 28a. Approximately equal to the shape. In this embodiment, the first arc portion 42a corresponds to the outer diameter side of the molded body F1 obtained from the cavity 28a, and the second arc portion 42b corresponds to the inner diameter side of the molded body F1. Since the other configurations of the press device 10a are the same as those of the press device 10, the overlapping description thereof will be omitted.

Since the method of manufacturing the molded body F1 using the press device 10a is the same as the method of manufacturing the molded body E1 using the press device 10, the overlapping description thereof will be omitted.

Sintering the molded body F1 obtained by the press device 10a gives the sintered body F2 (see FIG. 9A), and the sintered body F2 is processed and surface-treated to obtain the sintered body F3 (FIG. 9 (FIG. 9)). a)) is obtained. That is, the first side surface 44c which has an arcuate cross section and connects one ends of the first arc surface 44a and the second arc surface 44b and the first arc surface 44a and the second arc surface 44b which are spaced apart from each other. And a second side surface 44d connecting the other ends of the first arc surface 44a and the second arc surface 44b, and the easy-to-magnetize axis is transferred from the first side surface 44c and the second side surface 44d to the first arc surface 44a. A sintered body F3 (see FIG. 9B), which is polar anisotropically oriented so as to be focused toward the outside and the first arc surface 44a is on the outer diameter side and the second arc surface 44b is on the inner diameter side, is preferable. Can be made into. FIG. 9A also shows the orientation directions of the molded body F1 and the sintered bodies F2 and F3.

In this embodiment, the sintered bodies F3 are arranged in the circumferential direction and connected in a ring shape, and then NS is alternately magnetized to have a pole on the outer diameter side and generate a main magnetic flux on the outer diameter side. It becomes a sintered ring magnet with properties and is used for the inner rotor. The sintered body F3 magnetized at this time corresponds to a polar anisotropic sintered segment magnet.

According to the press device 10a, the same effect as that of the press device 10 can be obtained.

Further, when the first arc portion 42a of the cavity 28a corresponds to the outer diameter side of the molded body F1 obtained by the press device 10a and the second arc portion 42b corresponds to the inner diameter side of the molded body F1, the outer diameter side is mainly used. Molded bodies F1 for inner rotors and thus sintered bodies F2 and F3 for inner rotors oriented so as to generate magnetic flux can be easily manufactured.

In the press device 10 shown in FIGS. 1 and 2, the cavity 28 may be changed to the cavity 28b shown in FIG. What makes the cavity 28b different from the cavity 28 is its cross-sectional shape, which includes the second arc portion 46 instead of the second arc portion 38b. The second arc portion 46 has a semicircular convex portion 46a protruding into the cavity 28b at the central portion in the arc direction. That is, the cavity 28b is formed so that a protruding portion having a cross-sectional shape of a convex portion 46a extends in the vertical direction. The lower punch and the upper punch are appropriately modified so that their cross-sectional shapes are substantially equal to the cross-sectional shapes of the cavity 28b. Other configurations are the same as those of the press device 10.

Since the method of manufacturing the molded body G1 (see FIG. 11 (a)) using such a press device is the same as the method of manufacturing the molded body E1 using the press device 10, the overlapping description is omitted. do.

By such a pressing device, a molded body G1 having a notch M1 in the central portion on the outer diameter side can be obtained. When the molded body G1 is sintered, a sintered body G2 having a notch M2 in the central portion on the outer diameter side (see FIG. 11A) is obtained, and the sintered body G2 is processed and surface-treated to obtain a sintered body G2 on the outer diameter side. A sintered body G3 having a notch M3 in the central portion (see FIG. 11A) is obtained. That is, the first side surface 48c which has an arcuate cross section and connects one ends of the first arc surface 48a and the second arc surface 48b and the first arc surface 48a and the second arc surface 48b which are spaced apart from each other. And a second side surface 48d connecting the other ends of the first arc surface 48a and the second arc surface 48b, and the easy-to-magnetize axis is changed from the first side surface 48c and the second side surface 48d to the first arc surface 48a. The first arc surface 48a is on the inner diameter side and the second arc surface 48b is on the outer diameter side, and the second arc surface 48b is a notch formed in the central portion thereof. A sintered body G3 having M3 (see FIG. 11B) can be suitably produced. In addition, referring to FIG. 11, in order to form the notch M3 in the sintered body G3 after processing, the processing allowance (one side) is set to S1 when the sintered body G2 is processed into the sintered body G3. Assuming that the depth of the notch M1 of the body G1 is S2, S2 may be S1 / 0.8 or more. It is desirable that the notch depth of the sintered body G3 after processing is 0.1 mm or more (magnet thickness / 2) mm or less. The same applies to the molded body H1 and the sintered bodies H2 and H3 described later. FIG. 11A also shows the orientation directions of the molded body G1 and the sintered bodies G2 and G3.

In this embodiment, the sintered bodies G3 are arranged in the circumferential direction and connected in a ring shape, and then NS is alternately magnetized to create polar anisotropy having a pole on the inner diameter side and generating a main magnetic flux on the inner diameter side. It becomes a sintered ring magnet and is used for the outer rotor. The sintered body G3 magnetized at this time corresponds to a polar anisotropic sintered segment magnet.

The results of the study in the case where a sintered ring magnet having polar anisotropy is constructed from such a molded body G1 are shown. The dimensions of the sintered ring magnet are an outer diameter (diameter) of 80 mm, an inner diameter (diameter) of 74 mm, and a height of 10 mm, and the sintered ring magnet is composed of 28 poles. The material of the sintered ring magnet is a material corresponding to NMX-48BH manufactured by Hitachi Metals, Ltd.

FIG. 12A shows the relationship between the volume change rate of the molded body G1 and the surface magnetic flux density change rate, and FIG. 12B shows the volume change rate and the surface magnetic flux density change rate of the processed sintered body G3. The relationship is shown. The surface magnetic flux density (fundamental wave peak) was measured after the sintered ring magnet was constructed. The surface magnetic flux density was measured by a Gauss meter at the center in the axial direction and at a position 0.5 mm from the inner surface. The rate of change is the rate of change with respect to the molded body E1 in which the notch is not formed and the sintered body E3 after processing. Here, the case where the notch R is changed from 0.75 mm to 1.75 mm in 0.25 mm increments is examined. As can be seen from FIGS. 12 (a) and 12 (b), the volume change rate of the molded body G1 and the processed sintered body G3 is larger than the change rate of the surface magnetic flux density (fundamental wave peak). In the case of the notch R1.00 mm, the surface magnetic flux density change rate is -0.6%, whereas the volume change rate of the molded body G1 is -2.9%, and the volume change of the sintered body G3 after processing. The rate is -1.8%. In the case of the notch R1.25 mm, the surface magnetic flux density change rate is -1.2%, whereas the volume change rate of the molded body G1 is -4.5%, and the volume change of the sintered body G3 after processing. The rate is -3.4%. In the case of the notch R1.50 mm, the surface magnetic flux density change rate is -2.4%, whereas the volume change rate of the molded body G1 is -6.4%, and the volume change of the sintered body G3 after processing. The rate is -5.4%. In the case of the notch R 1.75 mm, the surface magnetic flux density change rate is -3.3%, whereas the volume change rate of the molded body G1 is -8.8%, and the volume change of the sintered body G3 after processing. The rate is -7.8%. Assuming that the permissible range of change in the surface magnetic flux density (fundamental wave peak) is 3% or less, the notch R is preferably 0.75 mm or more and 1.50 mm or less. In this way, it is possible to reduce the volumes of the molded body G1 and the post-processed sintered body G3, and thus the sintered ring magnet, without significantly reducing the rate of change in the surface magnetic flux density. As a result, the yield of raw materials can be improved and the weight of raw materials used can be reduced. In addition, the weight of the sintered body G3 after processing can be reduced.

According to such a pressing device, the same effect as that of the pressing device 10 can be obtained.

Further, a notch M1 is formed in the central portion of the second arc surface (the surface corresponding to the second arc portion 46 of the cavity 28b) of the molded body G1 formed in the cavity 28b. Here, in the press device 10 shown in FIG. 1, when the alignment magnetic field is applied, the magnet powder filled in the cavity 28 enters from the first arc portion 38a toward the cavity 28 and enters the first side portion 38c and the second side. An orientation magnetic field is applied so as to exit the portion 38d, or enter from the first side portion 38c and the second side portion 38d and exit the first arc portion 38a and away from the cavity 28, and is centered on the second arc portion 38b. Almost no alignment magnetic field is applied to the part. Therefore, the central portion of the second arc surface of the molded body E1 formed in the cavity 28 does not contribute so much to the formation of the main magnetic flux, and the central portion of the second arc surface of the molded body E1 can be scraped. Therefore, as shown in FIG. 10, a notch M1 is formed in the central portion of the second arc surface by forming a convex portion 46a protruding into the cavity 28b in the central portion of the second arc portion 46 of the cavity 28b in the second direction. The molded product G1 can be obtained. As a result, the amount of magnet material used can be reduced and the cost can be reduced without reducing the surface magnetic flux density of the sintered segment magnet produced from the molded body G1. That is, in the polar anisotropically oriented sintered body G3, the surface magnetic flux density is formed by forming a notch M3 at the center of the second arc surface 48b on the opposite side of the first arc surface 48a (magnetic pole surface) in the arc direction. A sintered segment magnet can be obtained in which the amount of magnet material used can be reduced with almost no reduction in magnetic flux. Further, the notch M3 can be used for positioning and rotation stop when forming the rotor.

Further, in the press device 10a shown in FIG. 7, the cavity 28a may be changed to the cavity 28c shown in FIG. The cavity 28c differs from the cavity 28a in its cross-sectional shape, and the cavity 28c includes a second arc 50 instead of a second arc 42b. The second arc portion 50 has a semicircular convex portion 50a protruding into the cavity 28c at the central portion in the arc direction. That is, the cavity 28c is formed so that a protruding portion having a cross-sectional shape of a convex portion 50a extends in the vertical direction. The lower punch and the upper punch are appropriately modified so that their cross-sectional shapes are substantially equal to the cross-sectional shapes of the cavity 28c. Other configurations are the same as those of the press device 10a.

The method of manufacturing the molded body H1 (see FIG. 14A) using such a pressing device is the same as the method of manufacturing the molded body F1 using the pressing device 10a.

By such a pressing device, a molded body H1 having a notch N1 in the central portion on the inner diameter side can be obtained. When the molded body H1 is sintered, a sintered body H2 having a notch N2 in the central portion on the inner diameter side (see FIG. 14A) is obtained, and the sintered body H2 is processed and surface-treated to obtain the central portion on the inner diameter side. A sintered body H3 having a notch N3 (see FIG. 14A) is obtained. That is, the first side surface 52c which has an arcuate cross section and connects one ends of the first arc surface 52a and the second arc surface 52b and the first arc surface 52a and the second arc surface 52b which are spaced apart from each other. And a second side surface 52d connecting the other ends of the first arc surface 52a and the second arc surface 52b, and the easy-to-magnetize axis moves from the first side surface 52c and the second side surface 52d to the first arc surface 52a. The first arc surface 52a is on the outer diameter side and the second arc surface 52b is on the inner diameter side, and the second arc surface 52b is a notch formed in the central portion thereof. A sintered body H3 having N3 (see FIG. 14B) can be suitably produced. FIG. 14A also shows the orientation directions of the molded body H1 and the sintered bodies H2 and H3.

In this embodiment, the sintered bodies H3 are arranged in the circumferential direction and connected in a ring shape, and then NS is alternately magnetized to have a pole on the outer diameter side and generate a main magnetic flux on the outer diameter side. It becomes a sintered ring magnet with properties and is used for the inner rotor. The sintered body H3 magnetized at this time corresponds to a polar anisotropic sintered segment magnet.

According to such a pressing device, the same effect as that of the pressing device 10a can be obtained.

Further, by forming a convex portion 50a protruding into the cavity 28c at the center portion of the second arc portion 50 of the cavity 28c in the second direction, a second arc surface (a surface corresponding to the second arc portion 50 of the cavity 28c) is formed. A molded body H1 having a notch N1 formed in the center of the above, and a sintered body H3 having a notch N3 formed in the center of the second arc surface 52b on the opposite side of the first arc surface 52a (magnetic pole surface) in the arc direction. It can be obtained, and the same effect as that of the press device having the above-mentioned cavity 28b can be obtained.

According to the present invention, either a sintered body that is polar-anisotropically oriented so as to generate a main magnetic flux on the inner diameter side or a sintered body that is polar-anisotropically oriented so as to generate a main magnetic flux on the outer diameter side. However, since it can be easily manufactured, a motor having high torque, low cogging torque and low inertia characteristics can be obtained regardless of whether it is an outer rotor type or an inner rotor type.

Further, the resin mold ring 54 shown in FIGS. 15 and 16 can be obtained by using a plurality of sintered bodies G3 (see FIG. 11).

The resin mold ring 54 is manufactured, for example, as follows.

With reference to FIG. 17A, first, the four corners of the sintered body G3, that is, the connecting portion between the first arc surface 48a and the first side surface 48c, and the connecting portion between the first arc surface 48a and the second side surface 48d. , The connecting portion between the second arc surface 48b and the first side surface 48c and the connecting portion between the second arc surface 48b and the second side surface 48d are chamfered to form chamfered portions C1, C2, C3 and C4. Further, the notch M3 is cut deeper to form the notch M4. In this way, the sintered body G4 having the chamfered portions C1 to C4 at the four corners and the notch M4 at the central portion of the second arc surface 48b is obtained.

Then, referring to FIG. 17B, a mold mold 58 having an annular groove 56 is prepared. The groove 56 has a ring shape corresponding to the outer shape of the resin mold ring 54 to be manufactured, and a plurality of (28 in this embodiment) protrusions for positioning the sintered body G4 are formed on the inner surface of the groove 56. The portions 60 are formed at equal intervals.

A plurality of (28 in this embodiment) sintered bodies G4 are fitted into the grooves 56 of the mold mold 58. At this time, each sintered body G4 is positioned so that a gap is formed between the adjacent sintered bodies G4 by fitting the notch M4 to the convex portion 60. Further, by supporting both end faces of the sintered body G4 in the groove 56 with two pins (not shown), positioning of the sintered body G4 in the groove 56 in the depth direction (axial direction) can be performed. Will be done.

In that state, the resin is injected from the gap between the adjacent sintered bodies G4 to form the resin mold member 62.

In this way, a resin mold ring 54 in which a plurality of (28 in this embodiment) sintered body G4 and the resin mold member 62 are integrated is obtained. In the resin mold ring 54, the plurality of sintered bodies G4 are arranged in a ring shape, and the adjacent sintered bodies G4 are the first side surface 48c of one sintered body G4 and the second side surface 48d of the other sintered body G4. Are placed next to each other at intervals. The resin mold member 62 holds a plurality of sintered bodies G4 so that the first arc surface 48a and the second arc surface 48b are exposed. That is, the resin mold member 62 fills the gaps between all the adjacent sintered bodies G4, and covers each of the sintered bodies in the axial direction when they are arranged in a ring shape. G4 is resin molded and held. The inner peripheral surface of the resin mold member 62 and the first arc surface 48a are formed flush with each other, and the outer peripheral surface of the resin mold member 62 and the second arc surface 48b are formed flush with each other. Further, the resin mold member 62 resin-molds each of the sintered bodies G4 so as to cover the chamfered portions C1 to C4. Recesses 64a and 64b connected to both ends of the notch M4 are formed on the outer peripheral surface of the resin mold member 62. Further, as a result of supporting both end faces of each sintered body G4 with two pins at the time of manufacturing the resin mold ring 54, a plurality of holes 66 are formed at both ends in the axial direction of the resin mold member 62.

According to such a resin mold ring 54, since the plurality of sintered bodies G4 are resin-molded and held by the resin mold member 62, the resin mold ring 54 can be easily manufactured with a small number of manufacturing man-hours.

Since the resin mold member 62 resin-molds each of the sintered bodies G4 so as to cover the chamfered portions C1 to C4, it is possible to prevent each of the sintered bodies G4 from falling off from the resin mold member 62.

Since each sintered body G4 has a notch M4 formed in the central portion of the second arc surface 48b, the notch M4 can be used for positioning each sintered body G4.

Further, by magnetizing the resin mold ring 54, that is, by magnetizing a plurality of sintered bodies G4 arranged in a ring shape alternately by NS, a pole is provided on the inner diameter side and a main magnetic flux is generated on the inner diameter side. A sintered ring magnet having anisotropy (hereinafter referred to as "resin molded ring magnet") can be obtained. The obtained resin molding ring magnet is used for the outer rotor.

Here, as a comparative example, the sintered bodies G4 are arranged in the circumferential direction, connected in a ring shape by adhesion, and then magnetized alternately with NS, so that the sintered ring magnet 100 is on the inner diameter side as in FIG. A sintered ring magnet (hereinafter referred to as "adhesive fixing ring magnet") having a pole and having polar anisotropy that generates a main magnetic flux on the inner diameter side is obtained. Then, the examination result of the resin mold ring magnet and the adhesive fixing ring magnet is shown. The dimensions of the resin molded ring magnet and the adhesive fixing ring magnet are the same at an outer diameter (diameter) of 80 mm, an inner diameter (diameter) of 74 mm, and a height of 16 mm, and are composed of 28 poles. The height of the magnetized sintered body G4 is 12 mm.

The surface magnetic flux densities of the inner and outer diameters of the resin molded ring magnet and the adhesive fixing ring magnet were measured using a Gauss meter. Here, for each sintered ring magnet, the surface magnetic flux density on the inner diameter side (indicated by "inner diameter side R36" in FIGS. 18 (a) and 18 (b)) is measured at the center in the axial direction and at a position 1 mm from the inner surface. The surface magnetic flux density on the outer diameter side (indicated by "outer diameter side R42" in FIGS. 18A and 18B) was measured at the center in the axial direction and at a position 2 mm from the outer surface.

As a result, the surface magnetic flux density waveform shown in FIG. 18A was obtained for the adhesive fixing ring magnet, and the distribution of the surface magnetic flux density peak on the inner diameter side shown in FIG. 19A was obtained. On the other hand, for the resin molding ring magnet, the surface magnetic flux density waveform shown in FIG. 18 (b) was obtained, and the distribution of the surface magnetic flux density peak on the inner diameter side shown in FIG. 19 (b) was obtained. The peak numbers on the horizontal axes of FIGS. 19A and 19B correspond to the 28 magnetized sintered bodies G4 included in the sintered ring magnet.

With reference to FIGS. 18A and 18B, the surface magnetic flux density distribution on the inner diameter side of each of the sintered ring magnets has a substantially sinusoidal shape as shown by the solid line, while the surface magnetic flux density distribution on the outer diameter side. Is smaller as shown by the broken line, and it can be seen that it is generally Halbach oriented. Therefore, since there is almost no magnetic flux leakage on the radial outer side of each of the sintered ring magnets integrated with each of the sintered ring magnets, the outer periphery of the sintered ring magnet is made of a non-magnetic material such as aluminum. Reinforcing rings can be fitted and other members, such as driven members, can be directly attached.

Since the resin mold member 62 holds the plurality of sintered bodies G4 so that the second arc surface 48b is exposed, the resin mold ring magnet is connected to another member (for example, a reinforcing ring or a cover) via the second arc surface 48b. The drive member) can be firmly attached. Further, when attaching another member to the resin molding ring magnet, the notch M4 can be used for positioning the resin molding ring magnet and preventing rotation.

Since the resin mold member 62 holds the plurality of sintered bodies G4 so that the first arc surface 48a is exposed, when the resin mold ring magnet is assembled as a rotor, the first arc surface 48a of the resin mold ring magnet and the stator The gap can be reduced and the motor characteristics can be improved.

Further, as can be seen by comparing FIGS. 19A and 19B, the waviness of the surface magnetic flux density peak on the inner diameter side is reduced in the resin molded ring magnet as compared with the adhesive fixing ring magnet, and the surface on the inner diameter side is reduced. The peak variation of the magnetic flux density is improved.

Furthermore, as a result of measuring the diameter dimension of the resin molding ring magnet with a 3D measuring instrument, the inner diameters (diameters) of the upper, center, and lower sides in the axial direction are within 73.996 mm to 74.005 mm, and the outer diameter in the center in the axial direction. The (diameter) is 80.19 mm, and the dimensional accuracy of the inner and outer diameters of the resin molding ring magnet is improved and the roundness is improved.

As described above, according to the resin molded ring magnet, the dimensional accuracy of the inner and outer diameters is improved, and the variation in the surface magnetic flux density distribution is reduced.

In the above-described embodiment, the case where the resin mold member 62 holds each of the sintered bodies G4 so that the first arc surface 48a and the second arc surface 48b are exposed in the resin mold ring 54 has been described. Not limited to this. The resin mold member may hold each sintered body G4 so that either one of the first arc surface 48a and the second arc surface 48b is exposed, or holds each sintered body G4 so as to cover the entire surface. You may.

In the above-described embodiment, the case where the sintered body G4 has the chamfered portions C1 to C4 has been described, but the present invention is not limited to this, and any one of the chamfered portions C1 to C4 may be provided. Further, the notch contained in the sintered body G4 may be notch M3 instead of notch M4, and may have arbitrary dimensions.

In the above-described embodiment, the case where the resin mold ring 54 contains the sintered body G4 has been described, but the present invention is not limited to this. The resin molding ring may include a sintered body E3, F3, G3, H3 or one of which is chamfered.

In the above-described embodiment, the case where six (three pairs) cavities are formed in the die has been described, but the present invention is not limited to this. Only one cavity may be provided on the die on the coil 20 side of either one of the center lines P1. Further, the die may be provided with only a pair of cavities symmetrical with respect to the center line P1. Further, the die may be provided with two pairs of cavities or four or more pairs of cavities.

The die is not limited to being made of a non-magnetic material, and may be made of a magnetic material.

In the above-described embodiment, the case where the end of the die and the end of the yoke are formed flush with each other in the first direction has been described, but the present invention is not limited to this, and the end of the die and the end of the yoke may be formed. It does not have to be flush with the first direction.

Further, in the above-described embodiment, the case where the coil is accommodated in the groove formed on the side surface of the yoke has been described, but the present invention is not limited to this. The coil may be provided in other ways, such as embedded in the yoke, as long as it is on the side of the yoke in contact with the die.

Further, as the magnet powder to be used, an alloy powder for Nd-Fe-B-based sintered magnet was given as an example, but other than that, Sr-based ferrite magnet, Ba-based ferrite magnet, Sr-La-Co-based ferrite magnet, etc. It can also be applied to alloy powder used for Ca-La-Co-based ferrite magnets.

Further, the sintered body produced in the present invention may have a flat cross section in addition to the arcuate cross section used for the inner rotor and the outer rotor. By making the cross section flat, it can be applied to the magnetic circuit of other magnetic field generators such as linear motors.

10,10a Press device 12,12a Die 14 Lower punch 16 Upper punch 18a, 18b York 20 Coil 22,22a Through hole 24a, 24b Die side surface 24c, 24d Die end 28, 28a, 28b, 28c Cavity 30a, 30b , 32a, 32b York ends 38a, 42a First arc 38b, 42b, 46, 50 Second arc 38c, 42c First side 38d, 42d Second side 40a, 44a, 48a, 52a First arc Surfaces 40b, 44b, 48b, 52b Second arc surface 40c, 44c, 48c, 52c First side surface 40d, 44d, 48d, 52d Second side surface 46a, 50a Convex part 54 Resin mold ring 62 Resin mold member 100 Sintered ring magnet C1, C2, C3, C4 Chamfered part D1, D5 Distance between the end part of the first arc part and the second arc part D2, D6 Distance between the center part between the first arc part and the second arc part D3 Position at the end Distance from the center of the second direction of the cavity to the end of the die D4 Distance between the center of the second direction of the cavity adjacent to the second direction E1, F1, G1, H1 Molded body E2, F2, G2, H2 Sintered body E3, F3, G3, G4, H3 Sintered body after processing M1, M2, M3, M4, N1, N2, N3 Notch P1, P2 Center line X 1st direction Y 2nd direction

Claims (10)

A die that penetrates in the vertical direction and has a through hole having an arc-shaped cross section, a lower punch that is inserted into the through hole of the die and forms a cavity with an upper surface opening together with the die, and a die that can be inserted into the cavity from above. The upper punch, a pair of yokes provided on both side surfaces of the die so as to sandwich the cavity from the side, and the cavity provided on the side surface side of each of the pair of yokes in contact with the die. A pair of coils are provided so as to be sandwiched from each other, and the cross-sectional shape of the cavity is such that the pair of coils are located at intervals in the first direction facing each other and are orthogonal to the first direction. The first arc portion and the second arc portion extending in two directions, the first side portion connecting one end portions of the first arc portion and the second arc portion, and the first arc portion and the second arc portion. It has an arc shape including a second side portion connecting the other ends of the portions, the first arc portion is closer to the side surface of the die than the second arc portion, and the cavity is the die. Is provided on one of the coils side of the center of the first direction, and when an alignment magnetic field is applied, a current is applied to the pair of coils so that the alignment magnetic fields generated by the pair of coils have opposite polarities. A press device that is swept away. A pair of the cavities sandwiched between the pair of coils is formed in the die, and the pair of cavities are positioned symmetrically with respect to a center line passing through the center of the die in the first direction and extending in the second direction. The press device according to claim 1, which is provided in 1. A plurality of the pair of cavities are formed in parallel in the second direction in the die, and the pair of cavities are formed on the side surface side of each of the pair of yokes in contact with the die, for each pair of the cavities. The pair of coils are arranged to face each other so as to sandwich the two coils, and when an alignment magnetic field is applied, a current is passed through the coils so that the alignment magnetic fields generated by the coils adjacent to each other in the second direction have the same polarity. The press device according to claim 2. The press device according to any one of claims 1 to 3, wherein the distance between the first arc portion and the second arc portion of the cavity is larger in the central portion than in both ends in the second direction of the cavity. .. The press device according to any one of claims 1 to 4, wherein the die is made of a non-magnetic cemented carbide. The press device according to claim 2 or 3, wherein the first arc portion corresponds to the inner diameter side of the molded body obtained by the press device, and the second arc portion corresponds to the outer diameter side of the molded body. The press device according to claim 2 or 3, wherein the first arc portion corresponds to the outer diameter side of the molded body obtained by the press device, and the second arc portion corresponds to the inner diameter side of the molded body. The distance in the second direction from the center of the cavity located at the end of the second direction to the end of the yoke on the cavity side of the yoke is the distance of the cavity adjacent to the second direction. The press device according to claim 3, which is 1/2 of the distance between the centers in two directions. The press device according to any one of claims 1 to 7, wherein the second arc portion has a convex portion protruding into the cavity at the central portion in the second direction. A die that penetrates in the vertical direction and has a through hole having an arc-shaped cross section, a lower punch that is inserted into the through hole of the die and forms a cavity with an upper surface opening together with the die, and a die that can be inserted into the cavity from above are provided. An upper punch to be formed, a pair of yokes provided on both side surfaces of the die so as to sandwich the cavity from the side, and a pair of yokes provided on the side surface side of each of the pair of yokes in contact with the die and the cavity. A pair of coils are provided so as to be sandwiched from each other, and the cross-sectional shape of the cavity is located at intervals in the first direction orthogonal to the vertical direction and is orthogonal to the first direction, respectively. A first arc portion and a second arc portion extending in a direction, a first side portion connecting one end portions of the first arc portion and the second arc portion, and the first arc portion and the second arc portion. It has an arc shape including a second side portion connecting the other ends of the above, the first arc portion is closer to the side surface of the die than the second arc portion, and the cavity is in the die. A method for manufacturing a sintered body using a press device, which is provided on one of the coil sides of the center of the first direction, in which a step of filling the cavity with magnet powder and the upper punch are provided in the cavity. The alignment magnetic field is applied to the magnet powder in the cavity by passing a current through the pair of coils so that the alignment magnetic fields generated by the pair of coils are opposite to each other. A step of orienting the magnet powder, a step of further lowering the upper punch to obtain a molded body, and a step of sintering the molded body to obtain a sintered body oriented in a polar anisotropic direction are provided. , A method for manufacturing a sintered body.

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