JP2018019081A - Sintered compact, manufacturing method thereof, press device and resin mold ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of sintered compact capable of manufacturing a sintered compact, subjected to polar anisotropic orientation regardless of whether the main magnetic flux generating position is inner diameter side or outer diameter side, easily with high processing yield, while reducing the process until obtaining a sintered compact, and to provide a press device, a sintered compact, and a resin mold ring.SOLUTION: A press device 10 includes a lower punch 14 forming a cavity 28 along with a die 12, an upper punch 16, yokes 18a, 18b provided on the opposite sides of the die 12, and a pair of coils 20 on the opposite sides of the cavity 28. Profile of the cavity 28 is circular arc-shape including a first arc 38a, a second arc 38b, a first side part 38c and a second side part 38d. The first arc 38a is closer to the lateral face of the die 12 than the second arc 38b, the cavity 28 is provided closer to any one coil 20 side than the center of the die 12 in the first direction, and a current is fed to the pair of coils 20 so that the orientation magnetic fields to be generated are opposite in polarity from each other.SELECTED DRAWING: Figure 3

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered body, a manufacturing method thereof, a pressing apparatus, and a resin mold ring, and more specifically, a polar anisotropically oriented sintered body used for a rotating machine, a manufacturing method thereof, a pressing apparatus, and a resin mold. Regarding the ring.

  In a rotating machine such as an SPM motor, a magnet rotor with a large amount of magnetic flux is required to achieve high torque characteristics. Further, in order to realize low cogging torque characteristics, a magnet rotor whose surface magnetic flux density distribution is sinusoidal is required. In response to these requirements, 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 for producing a surface multipolar anisotropic ring magnet after sintering in a magnetic field by providing six or more magnetic poles on the outer periphery of a molding space of a molding die, By this method, it is possible to obtain a polar anisotropic ring magnet that generates a main magnetic flux on the outer diameter side used for the inner rotor.

  Also, Patent Document 2 discloses a method for manufacturing a polar anisotropic segment magnet. In patent document 2, it has a central ferromagnetic body spaced apart on the outer arc surface side with respect to a cavity having an arc cross section, and a pair of side ferromagnetic bodies arranged so as to sandwich the cavity. A polar anisotropic segment magnet that generates a main magnetic flux on the outer diameter side used in the inner rotor can be obtained using a mold.

  Further, Patent Document 3 discloses the following manufacturing method. First, a magnet raw material is pulverized into magnet powder, and a compound is generated by mixing the pulverized magnet powder and a binder. And the produced | generated compound is shape | molded in a sheet form, and the oriented green sheet is produced by applying a magnetic field. Thereafter, the oriented green sheets are laminated, and the sintered body is obtained by being deformed and sintered into a shape that takes into account the final product shape and the direction of the easy magnetization axis required for the final product. Then, the sintered body of the final product shape is produced by processing the sintered body. As another method, the formed compound is formed into a sheet shape and oriented, and then punched into a shape that takes into account the final product shape and the direction of the easy axis required for the final product, and then punched It is also possible to produce a sintered body having a final product shape by laminating and sintering a shaped molded body to produce a sintered body and performing finish processing.

JP-A-9-330841 WO2012 / 90841 WO2015 / 186551

  However, in Patent Document 1, if a polar anisotropic ring magnet for generating a main magnetic flux on the inner diameter side used for the outer rotor is to be manufactured, it is necessary to arrange a yoke and a coil for generating an orientation magnetic field on the inner diameter side. In this case, problems such as a coil lead wire handling method and heat generation countermeasures occur. In addition, when the number of poles is increased, the teeth of the yoke are narrowed, and a problem of mold strength also occurs. For this reason, it is not easy to produce the ring magnet by extension of the prior art.

  When producing a polar anisotropic segment magnet that generates a main magnetic flux on the inner diameter side using the method of Patent Document 2, it is not easy to obtain a Halbach-like orientation distribution by simply arranging the ferromagnetic material. It is difficult to produce a polar anisotropic segment magnet that generates a main magnetic flux on the inner circumference side to be used.

By any of the methods described in 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 waste is generated in the material and the processing yield is poor, and the latter method has a problem that there are many steps until a sintered product having a final product shape is obtained.
Therefore, a main object of the present invention is to provide a sintered body that is polar-anisotropically oriented so as to generate a main magnetic flux on the inner diameter side, and a sintered body that is polar-anisotropically oriented so as to generate a main magnetic flux on the outer diameter side. A sintered body manufacturing method and press apparatus, a sintered body that can be suitably manufactured, and an easy manufacturing method that can easily manufacture any sintered body, improve the processing yield, and reduce the number of steps required to obtain a sintered body. It is providing the resin mold ring which can be produced.

  To achieve the above object, a die having a through-hole penetrating in the vertical direction and having an arc-shaped cross-section, a lower punch inserted into the through-hole of the die and forming a cavity having an upper surface opening together with the die, and above 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 cavity that is provided on a side surface that contacts the die in each of the pair of yokes. And a pair of coils arranged opposite to each other so that the cross-sectional shape of the cavity is in a second direction that is spaced from each other in the first direction in which the pair of coils face each other and that is orthogonal to the first direction. The first arc part and the second arc part extending, the first side part connecting the respective one end parts of the first arc part and the second arc part, and each of the first arc part and the second arc part And a second side part connecting the parts, the first arc part is closer to the side of the die than the second arc part, and the cavity is either in the first direction of the die or from the center in the first direction. Provided is a pressing device that is provided on one coil side and in which, when an orientation magnetic field is applied, a current flows through the pair of coils so that the orientation magnetic fields generated by the pair of coils have opposite polarities.

  A die having a through-hole penetrating in the vertical direction and having an arc-shaped cross-section; a lower punch inserted into the through-hole of the die and forming a cavity having an upper surface opening together with the die; A punch, a pair of yokes provided on both sides of the die so as to sandwich the cavity from the side, and a side surface in contact with the die in each of the pair of yokes, and disposed so as to sandwich the cavity And a cavity having a cross-sectional shape in which a first arc part and a second arc part are spaced from each other in a first direction orthogonal to the vertical direction and extend in a second direction orthogonal to the first direction. An arc part, a first side part connecting each end part of the first arc part and the second arc part, a second side part connecting each other end part of the first arc part and the second arc part; The A pressing device in which the first arc portion is closer to the side surface of the die than the second arc portion, and the cavity is provided on either coil side of the center in the first direction of the die. The method of manufacturing a sintered body used includes a step of filling a magnet powder into a cavity, and a pair of lowering an upper punch toward the cavity so that orientation magnetic fields generated by the pair of coils have opposite polarities. By applying an orientation magnetic field to the magnet powder in the cavity by passing an electric current through the coil, a step of further lowering the upper punch to obtain a compact, and a firing of the compact. And a step of obtaining a polar anisotropically-sintered sintered body.

  In the present invention, when an orientation magnetic field is applied, when an electric current is passed through the pair of coils so that the orientation magnetic fields generated by the pair of coils have opposite polarities, the orientation magnetic fields generated by the coils and passing through the die are mutually connected. Repel each other. As a result, the orientation magnetic field by one coil mainly passes one coil side from the center of the first direction in the die, and the orientation magnetic field by the other coil is mainly by the other coil side from the center of the first direction in the die. Pass through. Here, the cavity is provided on either coil side of the center of the die in the first direction, and the first arc part is provided closer to the side surface of the die than the second arc part. Therefore, the magnet powder filled in the cavity enters from the first arc portion toward the cavity and exits from the first side portion and the second side portion, based on the direction of the current flowing in the pair of coils. Or an orientation magnetic field is applied so that it may enter from the 1st side part and the 2nd side part, and may go out from a 1st arc part, and may go away from a cavity. That is, a magnetic field passing through the first arc part and the first side part and a magnetic field passing through the first arc part and the second side part are applied to the magnet powder filled in the cavity, and the magnet powder is oriented. Then, a compact is obtained by pressing the magnet powder with the upper punch and the lower punch, and the easy magnetization axis is converged from the first side surface and the second side surface toward the first arc surface by sintering the compact. Thus, a sintered body having a polar anisotropic orientation is 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 pressing device, the molded body that is polar-anisotropically oriented so as to generate the main magnetic flux on the inner diameter side, and thus the sintered body, is obtained. On the other hand, when the first arc portion of the cavity is made to correspond to the outer diameter side of the molded body, the molded body that is polar-anisotropically oriented so as to generate the main magnetic flux on the outer diameter side, and thus the sintered body. Can be easily produced. In addition, the shape of the molded body is pre-designed to be a sintered body that takes into account the final product shape and processing allowance after sintering, so the processing yield when processing from the sintered body to the final product shape is increased. It becomes good. Further, as in Patent Document 3, after forming the compound into a sheet shape, the sheet-shaped formed body is punched in advance into a shape that takes into consideration the final product shape and the direction of the easy axis required for the final product, and further punched out. Therefore, the number of processes for obtaining a sintered body can be reduced.

  According to the method for manufacturing a sintered body described above, the first arc surface and the second arc surface, which are arc-shaped in cross section and spaced from each other, and the respective one end portions of the first arc surface and the second arc surface are provided. A first side surface to be connected and a second side surface to connect the other end of each of the first arc surface and the second arc surface, the easy axis of magnetization from the first side surface and the second side surface to the first arc surface. Thus, 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 passing through the center of the die in the first direction and extending in the second direction. In this case, the pair of cavities are formed so that the respective second arc portions face each other, and one cavity is provided on one coil side from the center in the first direction of the die, and the other cavity is The die is provided on the other coil side of the die in the first direction, and each cavity is provided such 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., enters from the first arc part and exits from the first side part and the second side part toward the cavity, or from the first side part. And an orientation magnetic field is applied to enter from the second side and exit from the first arc and away from the cavity. As a result, it is possible to easily produce a sintered body that is polar-anisotropically oriented so that the easy magnetization axis converges from the first side surface and the second side surface toward the first arc surface from the molded body obtained in each cavity. , Improve productivity.

  Preferably, a plurality of pairs of cavities are formed in the die in parallel in the second direction, and the pair of cavities are sandwiched between the pair of cavities on each side of the pair of yokes that are in contact with the die. A pair of coils are arranged opposite to each other, and when an orientation magnetic field is applied, a current is passed through the coils so that the orientation magnetic fields generated by the coils adjacent in the second direction have the same polarity. In this case, a sintered body that is polar-anisotropically oriented so that the easy axis of magnetization converges from the first side surface and the second side surface toward the first arc surface is easily produced from the molded body obtained in a plurality of cavities. And productivity can be further improved.

  More preferably, the distance between the first arc portion and the second arc portion of the cavity is greater at the center than at both ends in the second direction of the cavity. When the arc-shaped molded body having polar anisotropy orientation is sintered, the contraction rate is larger in the central portion than in the arc-direction end portion of the molded body. Therefore, by setting the interval between the first arc portion and the second arc portion of the cavity so that the central portion is larger than both end portions in the second direction of the cavity, the molded body obtained in the cavity in advance. The thickness can be set so that the center portion is larger than the end portion in the arc direction. When this molded body is sintered, the thickness of the end portion in the arc direction of the sintered body and the thickness of the central portion can be made substantially equal due to the difference in shrinkage rate. Thus, 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 thickness), the sintered body having a desired shape is obtained. Is obtained.

  Preferably, the die is made of a nonmagnetic 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.

  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 the outer rotor that is polar-anisotropically oriented so as to generate the main magnetic flux on the inner diameter side can be easily produced.

  Preferably, the first arc portion corresponds to the outer diameter side of the molded body obtained by the pressing 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 that is polar-anisotropically oriented so as to generate a main magnetic flux on the outer diameter side can be easily produced.

  Preferably, the distance in the second direction from the center in the second direction of the cavity located at the end in the second direction to the end of the yoke on the cavity side is between the centers in the second direction of cavities adjacent in the second direction. 1/2 of the distance. In this case, the orientation magnetic field applied to the cavity located at the end portion in the second direction is the same as the orientation magnetic field applied to the other cavities, so that a similar molded body can be obtained in each cavity. Thus, it is possible to easily produce a sintered body having the same polar anisotropic orientation.

  Preferably, the second arc portion has a convex portion protruding into the cavity at the center in the second direction. In this case, a notch (recess) is formed at the center of the second arc surface (the surface corresponding to the second arc portion of the cavity) of the molded body formed by the cavity. Here, when an orientation magnetic field is applied, the magnet powder filled in the cavity enters from the first arc part and exits from the first side part and the second side part toward the cavity, or from the first side part and the second side part. An orientation 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 orientation 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 by the cavity does not contribute much to the formation of the main magnetic flux, and the central portion of the second arc surface of the molded body can be cut. Therefore, by forming a convex portion projecting into the cavity in the second direction central portion of the second arc portion of the cavity, a molded body having a notch formed in 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 substantially reducing the surface magnetic flux density of the sintered segment magnet produced from the compact.

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

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

  More preferably, in the sintered body, the second arc surface has a notch formed at the center thereof. As described above, in the sintered body with polar anisotropy orientation, the surface magnetic flux density is almost reduced by forming a notch in the arc direction center of the second arc surface opposite to the first arc surface (magnetic pole surface). A sintered segment magnet can be obtained in which the amount of magnet material used can be reduced without reduction. Further, the notch can be used for positioning and rotation prevention when configuring the rotor.

  Moreover, it is provided with a plurality of the above-mentioned sintered bodies arranged in a ring shape and a resin mold member that holds the plurality of sintered bodies, and the adjacent sintered bodies include the first side surface of one sintered body and the other side. A resin mold ring is provided in which the second side surface of the sintered body is arranged so as to be adjacent to each other with a space therebetween.

  In this invention, a resin mold ring can be easily produced with few manufacturing steps by resin-molding and holding a plurality of sintered bodies with a resin mold member.

  Preferably, in the resin mold ring, the resin mold member holds the 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. it can. Moreover, 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 mold ring, each sintered body includes 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. The chamfered portion is formed on at least one of the connecting portion and the connecting portion between the second arc surface and the second side surface, and the chamfered portion is covered with the resin mold member. In this case, each sintered body can be prevented from falling off from the resin mold member.

  More preferably, when each sintered body has a notch formed at the center of the second arc surface in the resin mold ring, the notch can be used for positioning of each sintered body. Further, in a sintered ring magnet obtained by magnetizing a resin mold ring including 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 anisotropic oriented so as to generate a main magnetic flux on the outer diameter side. Even so, it can be easily produced, the processing yield is improved, the number of steps required to obtain a sintered body can be reduced, and a resin mold ring can be easily produced.

The press apparatus which concerns on one Embodiment of this invention is shown, (a) is the perspective view, (b) is the sectional view on the AA line of (a). It is a cross-sectional solution figure which shows an example of the principal part and orientation magnetic field of the press apparatus of FIG. FIG. 2 is an enlarged cross-sectional view illustrating the vicinity of a cavity of the press device of FIG. 1. (A) is an illustrative view 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 apparatus of FIG. 1, and (b) is a sintered body after processing. FIG. A polar anisotropic ring magnet formed using a polar anisotropically 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 anisotropic ring magnet shown in FIG. It is a cross-sectional solution figure which shows an example of the principal part and orientation magnetic field of the press apparatus of other embodiment of this invention. FIG. 8 is an enlarged cross-sectional view illustrating the vicinity of a cavity of the press device of FIG. 7. (A) is an illustrative view 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 apparatus of FIG. 7, and (b) is a sintered body after processing. FIG. FIG. 6 is a cross-sectional view illustrating a modification of the cavity in the press apparatus of FIG. 2. (A) is an illustrative view 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 a sintered compact. (A) is a graph which shows the relationship between the surface magnetic flux density change rate and volume change rate in a molded object, (b) shows the relationship between the surface magnetic flux density change rate and volume change rate in the sintered compact after a process. It is a graph. It is a cross-sectional solution figure which shows the modification of the cavity in the press apparatus of FIG. (A) is an illustrative view 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 a sintered compact. It is a perspective view which shows an example of a resin mold ring. An example of a resin mold ring is shown, (a) is a plan view thereof, and (b) is a front view thereof. (A) is an illustration figure which shows the sintered compact by which resin molding is carried out, (b) is an illustration figure for demonstrating the manufacturing method of a resin mold ring. (A) is a graph which shows the surface magnetic flux density waveform of an adhesive fixing ring magnet, (b) is a graph which shows the surface magnetic flux density waveform of a resin mold ring magnet. (A) is a graph which shows distribution of the surface magnetic flux density peak by the side of an inner diameter of an adhesion fixing ring magnet, (b) is a graph which shows distribution of the surface magnetic flux density peak by the side of an inner diameter of a resin mold ring magnet.

  Embodiments of the present invention will be described below with reference to the drawings.

  Referring to FIGS. 1 and 2, a pressing device 10 according to an embodiment of the present invention includes a compact E1 and sintered bodies E2 and E3 (polarized anisotropically so as to generate a main magnetic flux on the inner diameter side). 4 is a device used for manufacturing a die 12, a plurality (six in this embodiment) of lower punches 14, a plurality (six in this embodiment) of upper punches 16, a pair of It includes yokes 18a and 18b and a coil 20 (in this embodiment, six poles are generated).

  The die 12 is made of, for example, a nonmagnetic cemented carbide, is formed in a substantially square plate shape, and is erected. The die 12 is provided with a plurality (six in this embodiment) of through holes 22 penetrating in the vertical direction and having a circular arc cross section. There are two through holes 22 in the first direction (indicated by arrow X) that is the short direction of the die 12, and three through holes 22 in the second direction (indicated by arrow Y) that is the long direction of the die 12. As a result, a total of six through holes 22 are formed in the die 12. The first direction and the second direction are orthogonal to each other.

  Further, a positioning projection 26a for the yoke 18a is provided below the side surface 24a of the die 12, and a positioning projection 26b for 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 a cavity 28 having an upper surface opening is formed by the die 12 and the lower punch 14. Accordingly, the cavity 28 is formed in the through hole 22 of the die 12, and the two cavities 28 are in the first direction (indicated by the arrow X) that is the short direction of the die 12, and the second direction is the longitudinal direction of the die 12. Three cavities 28 are formed in each (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 shape of the cavity 28.

  A pair of yokes 18a, 18b are provided on both side surfaces 24a, 24b of the die 12 in the first direction so as to sandwich each cavity 28 formed in the die 12 from the side (first direction). The pair of yokes 18a and 18b is formed in a square plate shape made of a magnetic material such as SS400 or silicon steel plate, for example, and is locked and positioned at the upper ends of the protrusions 26a and 26b. The dimension in the second direction of the pair of yokes 18a and 18b is equal to the dimension in the second direction of the die 12, and the one end 24c of the die 12 and the one end 30a and 30b of the pair of yokes 18a and 18b in the second direction are Similarly, the other end 24d of the die 12 and the other ends 32a and 32b of the pair of yokes 18a and 18b in the second direction are flush with each other in the first direction. Is done. A press plate (not shown) made of a nonmagnetic material such as SUS304 is provided so as to surround the die 12 and the pair of yokes 18a and 18b, thereby forming a mold.

  In addition, grooves 36 a and 36 b for accommodating the coil 20 are formed in the side surfaces 34 a and 34 b in contact with the die 12 in each of the pair of yokes 18 a and 18 b for each position corresponding to the cavity 28. The coil 20 is accommodated 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 side of the pair of yokes 18a and 18b, and the pair of coils are sandwiched between the pair of cavities 28 for each pair of the cavities 28 arranged in the first direction. 20 are arranged opposite to each other.

  Here, the cavity 28 will be described.

  A pair of cavities 28 formed in the die 12 and sandwiched between the pair of coils 20 are provided at symmetrical positions with respect to a 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 a pair 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 the one coil 20 side or the other coil 20 side in the first direction from the center (center line P1) in the first direction in the die 12.

  Referring also to FIG. 3, the cross-sectional shape of the cavity 28 is obtained by taking into account the polar anisotropic orientation direction and the shrinkage ratio in the direction parallel to the orientation direction and the direction perpendicular to the orientation direction in advance. It is designed to be a sintered body that takes into account the final product shape and processing cost after sintering. The cross-sectional shape of the cavity 28 is an arc shape such that the center portion is closer to the center line P1 than the both end portions of the cavity 28, and the pair of coils 20 are spaced apart from each other in the first direction. A first arc portion 38a and a second arc portion 38b extending in the second direction, a first side portion 38c connecting one end portions of the first arc portion 38a and the second arc portion 38b, and a first arc portion 38a, respectively. And a second side portion 38d connecting the other end portions of the second arc portions 38b. The second arc portion 38b is formed to be curved so that the center portion approaches the center line P1 (expands toward the center line P1 side) from both ends thereof. As for the first arc portion 38a, the vicinity of both end portions of the first arc portion 38a is formed substantially parallel to the vicinity of both end portions of the second arc portion 38b, but the center portion of the first arc portion 38a moves away from the center line P1 ( And curved so as to swell to the opposite side of the center line P1. Therefore, the distance between the first arc part 38a and the second arc part 38b in the cavity 28 is larger in the distance D2 in the center than in the distance D1 between both ends in the second direction.

  Of the pair of cavities 28 arranged in the first direction, for the cavity 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 closer to the yoke 18b side. For the cavity 28 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 in the second direction of the cavity 28 located at the 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. The distance D3 in the second direction from the center in the second direction to the one end portions 30a and 30b of the yokes 18a and 18b) is D1 / 2 of the distance D4 between the centers in the second direction of the cavities 28 adjacent 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 for producing the molded body E1 (sintered bodies E2, E3) using such a press apparatus 10 will be described.

  First, the magnet powder is filled into the cavity 28 of the press apparatus 10 from above. As the magnet powder, for example, Nd—Fe—B based sintered magnet alloy powder 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 enters the first powder side in the first arc portion 38 a with respect to the magnet powder in the cavity 28. An orientation magnetic field emerging from 38c and the second side 38d is applied to orient the magnet powder. When the orientation magnetic field is applied, the orientation magnetic fields generated by the coils 20 adjacent to each other in the second direction are mutually opposite so that the orientation magnetic fields generated by the pair of coils 20 arranged opposite to each other in the first direction have opposite polarities. A current is passed through each coil 20 so as to have the same polarity. As a result, a symmetrical orientation magnetic field can be applied to the center line P1, and a symmetrical orientation magnetic field can be applied to each cavity 28 with respect to the center line P2 passing through the center in the second direction and parallel to the first direction. . Preferably, the coil 20 is supplied with a pulse current generated by capacitor discharge, whereby a pulse magnetic field is applied to orient the magnet powder. Note that the direction of the current that flows through each coil 20 when an orientation magnetic field is applied is reversed to that described above, and enters the cavity 28 from the first side 38c and the second side 38d and exits from the first arc 38a. An orientation magnetic field may be applied to orient the magnet powder.

  Then, the upper punch 16 is further lowered so as to obtain a predetermined compact density. Thereby, the compact E1 (see FIG. 4A) is obtained. When the molded body E1 is sintered, a sintered body E2 (see FIG. 4A) is obtained, and the sintered body E3 is processed and surface-treated to process the sintered body E3 (see FIG. 4A). Is obtained. That is, the first arc surface 40a and the second arc surface 40b, which are arc-shaped in cross section and spaced from each other, and the first side surface 40c that connects the respective one end portions of the first arc surface 40a and the second arc surface 40b. And a second side surface 40d connecting the other end of each of the first arc surface 40a and the second arc surface 40b, the easy axis of magnetization from the first side surface 40c and the second side surface 40d to the first arc surface 40a. Preferred is a sintered body E3 (see FIG. 4 (b)) which is polar-anisotropically oriented so as to converge toward the surface, the first arc surface 40a is on the inner diameter side, and the second arc surface 40b is on the outer diameter side. Can be made. FIG. 4A also shows the orientation directions of the compact 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 thereafter NS is alternately magnetized to generate a main magnetic flux on the inner diameter side having a pole on the inner diameter side as shown in FIG. The sintered ring magnet 100 having polar anisotropy is used for the 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 configured as described above. 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 a position 0.5 mm from the center in the axial direction and 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 substantially zero as shown by the broken line. Thus, the sintered ring magnet 100 is generally Halbach-oriented, 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 orientation magnetic fields generated by the pair of coils 20 have opposite polarities when the orientation magnetic field is applied, the current is generated by each of the pair of coils 20. Thus, the orientation magnetic fields passing through the die 12 repel each other. As a result, the orientation magnetic field by one coil 20 mainly passes through one coil 20 side from the center (center line P1) in the first direction in the die 12, and the orientation magnetic field by the other coil 20 is mainly in the first direction 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 coil 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 to be close to. Therefore, the magnet powder filled in the cavity 28 enters the cavity 28 from the first arc portion 38a and enters 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 to exit from 38d, or to enter from first side 38c and second side 38d and exit from first arc 38a away from cavity 28. That is, to the magnet powder filled in the cavity 28, 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, and the magnet powder Are oriented. Then, the compact E1 is obtained by pressing the magnet powder with the upper punch 16 and the lower punch 14, and the easy axis of magnetization is changed from the first side surface 40c and the second side surface 40d by sintering and processing the compact E1. A sintered body E3 is obtained that is polar-anisotropically oriented so as to converge toward the first arc surface 40a. Here, if 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, the main inner diameter side will be increased. The molded body E1 for the outer rotor and the sintered bodies E2 and E3 that are polar-anisotropically oriented so as to generate magnetic flux can be easily produced. Since the molded body E1 is designed in advance to be a sintered body E2 in consideration of the final product shape and processing cost after sintering, the processing yield when processing from the sintered body E2 to the final product shape E3 is increased. It becomes good. In addition, after forming the compound into a sheet shape, a process of punching in advance into a shape considering the final product shape and the direction of the easy axis required for the final product, and further stacking the punched sheet-shaped molded body Since this is not necessary, the number of steps for obtaining the sintered body E3 can be reduced.

  The pair of cavities 28 are formed so that the respective second arc portions 38b face each other, and one of the cavities 28 is provided closer to the one coil 20 than the center of the die 12 in the first direction. 28 is provided on the other coil 20 side than the center in the first direction of the die 12, 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 to become. Therefore, the magnet powder filled in each cavity 28 has the same orientation magnetic field, that is, enters from the first arc portion 38a toward the cavity 28 and exits from the first side portion 38c and the second side portion 38d. Alternatively, the orientation magnetic field is applied so as to enter from the first side portion 38 c and the second side portion 38 d and to exit from the first arc portion 38 a and away from the cavity 28. As a result, from the compacts E1 obtained in the respective cavities 28, sintered bodies that are polar-anisotropically oriented so that the easy magnetization axes converge 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 the die 12 in parallel in the second direction. From the molded body E1 obtained in each cavity 28, the easy axis of magnetization is the first arc surface from the first side surface 40c and the second side surface 40d. The sintered body E3 that is polar-anisotropically oriented so as to converge toward 40a can be easily produced, and the productivity can be further improved.

  In the yokes 18a and 18b, since D3 = D4 / 2, the orientation magnetic field applied to the cavity 28 located at the end in the second direction is the same as the orientation magnetic field applied to the other cavities 28. Therefore, the same molded body E1 can be obtained in each cavity 28, and the same highly anisotropically oriented sintered bodies E2 and E3 can be easily manufactured.

  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 end portions in the second direction of the cavity 28, the cavity 28 is obtained in advance. The thickness of the molded body E1 can be set so that the central portion is larger than the end portion in the arc direction. When this molded body E1 is sintered, the thickness of the end portion in the arc direction and the thickness of the central portion of the sintered body E2 can be made substantially equal due to the difference in shrinkage rate. Thus, 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 thickness), the desired shape can be obtained. A sintered body E2 is obtained.

  When the die 12 is made of a nonmagnetic cemented carbide, the orientation 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.

  The coil 20 is supplied with a pulse current generated by capacitor discharge, and the magnetic powder can be oriented well by applying a pulse magnetic field to orient the magnetic 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 hardly generated, and the sintered body E2 is easily obtained. Can do.

  Moreover, in the rotor comprised using the segment-like sintered compact E3 by which the polar anisotropic orientation was carried out, the orientation direction in the connection surface (position between poles) of an adjacent sintered compact (sintered segment magnet) is the following. An orientation angle distribution that is perpendicular to the connection surface and is close to a Halbach array can be configured. 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, a magnetic back yoke for configuring the magnetic path is not required, so that the rotor inertia can be reduced and a highly responsive rotor can be obtained. It is done.

  Moreover, with reference to FIG. 7, the press apparatus 10a of other embodiment of this invention is demonstrated. The press apparatus 10a is an apparatus used for manufacturing a molded body F1 and sintered bodies F2 and F3 (see FIG. 9) that are polar-anisotropically oriented so as to generate a main magnetic flux on the outer diameter side. 1 and 2 is that a die 12a is used instead of the die 12, and a lower punch and an upper punch for the die 12a instead of the lower punch 14 and the upper punch 16 (both not shown). And the coil position is changed in accordance with the shape of the molded body. The difference between the die 12 a and the die 12 is that a through hole 22 a 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 that the lower punch 14 and the upper punch for the cavity 28a are included instead of the lower punch 14 and the upper punch 16. .

  Referring also to FIG. 8, the cavity 28 a is different from the cavity 28 in its 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 the both ends of the cavity 28a, and is mutually in the first direction (indicated by the arrow X) where the pair of coils 20 face each other. The first arc part 42a and the second arc part 42b that are located at intervals and extend in the second direction (indicated by the arrow Y) are connected to one end of each of the first arc part 42a and the second arc part 42b. First side portion 42c to be connected, and second side portion 42d connecting the other end portions of the first arc portion 42a and the second arc portion 42b. Each of the first arc portion 42a and the second arc portion 42b is formed to be curved so that the center portion is farther from the center line P1 than the both end portions (swells on the side opposite to the center line P1). The distance between the first arc part 42a and the second arc part 42b in the cavity 28a is larger in the center part distance D6 than in the distance D5 between both end parts in the second direction. The lower punch and the upper punch of the press device 10a are different from the lower punch 14 and the upper punch 16 of the press device 10 in the cross-sectional shape, and the cross-sectional shape of the lower punch and the upper punch in the press device 10a is the cross-section of the cavity 28a. It is almost 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 structure of the press apparatus 10a is the same as that of the press apparatus 10, the overlapping description is abbreviate | omitted.

  Since the method of manufacturing the molded body F1 using such a press apparatus 10a is the same as the method of manufacturing the molded body E1 using the press apparatus 10, the overlapping description is omitted.

  When the formed body F1 obtained by the pressing device 10a is sintered, a sintered body F2 (see FIG. 9A) is obtained, and the sintered body F3 (FIG. 9 ( a)) is obtained. In other words, the first arc surface 44a and the second arc surface 44b, which are arc-shaped in cross section and spaced from each other, and the first side surface 44c that connects the respective one end portions of the first arc surface 44a and the second arc surface 44b. And a second side surface 44d connecting the other end of each of the first arc surface 44a and the second arc surface 44b, the easy axis of magnetization from the first side surface 44c and the second side surface 44d to the first arc surface 44a. Preferred is a sintered body F3 (see FIG. 9B) that is polar-anisotropically oriented so as to converge toward the outer surface, the first arc surface 44a is on the outer diameter side, and the second arc surface 44b is on the inner diameter side. Can be made. FIG. 9A also shows the orientation directions of the compact 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 thereafter NS is alternately magnetized, thereby generating poles on the outer diameter side and generating a main magnetic flux on the outer diameter side. It becomes a sintered ring magnet having the 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 the press device 10 can be obtained.

  Further, when the first arc portion 42a of the cavity 28a is made to correspond to the outer diameter side of the molded body F1 obtained by the pressing device 10a and the second arc portion 42b is made to correspond to the inner diameter side of the molded body F1, the main diameter is increased to the outer diameter side. It is possible to easily produce the molded body F1 for the inner rotor that is polar-anisotropically oriented so as to generate magnetic flux, and thus the sintered bodies F2 and F3.

  In the press apparatus 10 shown in FIGS. 1 and 2, the cavity 28 may be changed to the cavity 28b shown in FIG. The cavity 28 b is different from the cavity 28 in its cross-sectional shape and includes the second arc portion 46 instead of the second arc portion 38 b. The second arc portion 46 has a semicircular convex portion 46a protruding into the cavity 28b at the center in the arc direction. That is, the cavity 28b is formed so that a protruding portion whose cross-sectional shape becomes the convex portion 46a extends in the vertical direction. The lower punch and the upper punch are appropriately changed so that the cross-sectional shape thereof is substantially equal to the cross-sectional shape 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. 11A) using such a press apparatus is the same as the method of manufacturing the molded body E1 using the press apparatus 10, the overlapping description is omitted. To do.

  By such a pressing device, a molded body G1 having a notch M1 in the center portion on the outer diameter side is obtained. When the compact G1 is sintered, a sintered body G2 (see FIG. 11A) having a notch M2 in the center portion on the outer diameter side is obtained. A sintered body G3 (see FIG. 11A) having a notch M3 at the center is obtained. In other words, the first arc surface 48a and the second arc surface 48b, which are arc-shaped in section and spaced from each other, and the first side surface 48c that connects the respective one end portions of the first arc surface 48a and the second arc surface 48b. And a second side surface 48d connecting the other end of each of the first arc surface 48a and the second arc surface 48b, the easy axis of magnetization 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 center thereof. A sintered body G3 (see FIG. 11B) having M3 can be suitably produced. Referring to FIG. 11, in order to form notch M3 in sintered body G3 after processing, when machining sintered body G2 into sintered body G3, the machining allowance (one side) is S1, forming When the depth of the notch M1 of the body G1 is S2, S2 may be S1 / 0.8 or more. The notched depth of the sintered body G3 after processing is desirably 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 compact 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 thereafter, NS is alternately magnetized, thereby providing polar anisotropy that has a pole on the inner diameter side and generates a main magnetic flux on the inner diameter side. It becomes the sintered ring magnet which has, and is used for an outer rotor. The sintered body G3 magnetized at this time corresponds to a polar anisotropic sintered segment magnet.

  The examination result in the case where the sintered ring magnet which has polar anisotropy is comprised from such a molded object G1 is 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 has 28 poles. The material of the sintered ring magnet is a material corresponding to NMX-48BH manufactured by Hitachi Metals, Ltd.

  FIG. 12 (a) shows the relationship between the volume change rate and the surface magnetic flux density change rate of the compact G1, and FIG. 12 (b) shows the volume change rate and surface magnetic flux density change rate of the sintered body G3 after processing. The relationship is shown. The surface magnetic flux density (fundamental peak) was measured after the sintered ring magnet was constructed. The surface magnetic flux density was measured with 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 and the post-processed sintered body E3 in which notches are not formed. Here, the case where the notch R was changed from 0.75 mm to 1.75 mm in 0.25 mm increments was examined. As can be seen from FIGS. 12A and 12B, the volume change rate of the compact G1 and the sintered body G3 after processing is larger than the rate of change of the surface magnetic flux density (fundamental peak). In the case of the notch R1.00 mm, the change rate of the surface magnetic flux density is -0.6%, whereas the change rate of the volume of the compact G1 is -2.9%. The rate is -1.8%. In the case of the notch R1.25 mm, the rate of change in the surface magnetic flux density is -1.2%, whereas the rate of change in volume of the compact G1 is -4.5%, and the change in volume of the sintered body G3 after processing. The rate is -3.4%. In the case of the notch R of 1.50 mm, the surface magnetic flux density change rate is -2.4%, whereas the volume change rate of the compact G1 is -6.4%, and the volume change of the sintered product G3 after processing. The rate is -5.4%. In the case of the notch R of 1.75 mm, the surface magnetic flux density change rate is −3.3%, whereas the volume change rate of the compact G1 is −8.8%, and the volume change of the sintered product G3 after processing is The rate is -7.8%. When the allowable range of change in the surface magnetic flux density (fundamental peak) is 3% or less, the notch R is preferably set to 0.75 mm or more and 1.50 mm or less. Thus, it is possible to reduce the volume of the formed body G1 and the post-processed sintered body G3 and thus the sintered ring magnet without significantly reducing the surface magnetic flux density change rate. Thereby, a raw material yield can be improved and the used weight of a raw material can be reduced. Moreover, the weight of the sintered body G3 after processing can be reduced.

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

  In addition, a notch M1 is formed at the center of the second arc surface (surface corresponding to the second arc portion 46 of the cavity 28b) of the molded body G1 molded by the cavity 28b. Here, in the press apparatus 10 shown in FIG. 1, when applying an orientation magnetic field, the magnet powder filled in the cavity 28 enters the cavity 28 from the first arc portion 38a and the first side portion 38c and the second side portion. An orientation magnetic field is applied to exit the portion 38d or to enter 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, and the center of the second arc portion 38b. Almost no orientation magnetic field is applied to the part. Therefore, the central portion of the second arc surface of the molded body E1 formed by the cavity 28 does not contribute 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 cut. Accordingly, as shown in FIG. 10, a notch M1 is formed at the center of the second arc surface by forming the convex portion 46a protruding into the cavity 28b at the center in the second direction of the second arc portion 46 of the cavity 28b. The molded body G1 thus obtained can be obtained. Accordingly, the amount of magnet material used can be reduced and the cost can be reduced without substantially reducing the surface magnetic flux density of the sintered segment magnet produced from the compact G1. That is, in the sintered body G3 oriented in the polar anisotropy, the surface magnetic flux density is formed by forming the notch M3 in the center in the arc direction of the second arc surface 48b opposite to the first arc surface 48a (magnetic pole surface). Thus, a sintered segment magnet can be obtained that can reduce the amount of magnet material used without substantially lowering the amount of magnet. Further, the notch M3 can be used for positioning and rotation stopping when configuring the rotor.

  Furthermore, in the press apparatus 10a shown in FIG. 7, the cavity 28a may be changed to the cavity 28c shown in FIG. The cavity 28c is different from the cavity 28a in its cross-sectional shape, and the cavity 28c includes the second arc portion 50 instead of the second arc portion 42b. The 2nd arc part 50 has the semicircle-shaped convex part 50a which protrudes in the cavity 28c in the circular arc direction center part. That is, the cavity 28c is formed so that the protruding portion whose cross-sectional shape becomes the convex portion 50a extends in the vertical direction. The lower punch and the upper punch are appropriately changed so that the cross-sectional shape thereof is substantially equal to the cross-sectional shape 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 is obtained. When the molded body H1 is sintered, a sintered body H2 (see FIG. 14A) having a notch N2 in the central portion on the inner diameter side is obtained, and the central portion on the inner diameter side is obtained by processing and surface-treating the sintered body H2. A sintered body H3 (see FIG. 14A) having a notch N3 is obtained. In other words, the first arc surface 52a and the second arc surface 52b, which are arc-shaped in cross section and spaced from each other, and the first side surface 52c that connects the respective one end portions of the first arc surface 52a and the second arc surface 52b. And a second side surface 52d connecting the other end of each of the first arc surface 52a and the second arc surface 52b, the easy axis of magnetization 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 at the center thereof. Sintered body H3 (refer to Drawing 14 (b)) which has N3 can be produced suitably. FIG. 14 (a) also shows the orientation directions of the compact 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 thereafter NS is alternately magnetized, thereby having a pole on the outer diameter side and generating a main magnetic flux on the outer diameter side. It becomes a sintered ring magnet having the 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 press apparatus, the same effect as the press apparatus 10a can be obtained.

  Further, a second arc surface (a surface corresponding to the second arc portion 50 of the cavity 28c) is formed by forming a convex portion 50a projecting into the cavity 28c at the center in the second direction of the second arc portion 50 of the cavity 28c. A molded body H1 in which a notch N1 is formed in the center portion of the first arc surface, and eventually a sintered body H3 in which a notch N3 is formed in the center portion in the arc direction of the second arc surface 52b opposite to the first arc surface 52a (magnetic pole surface). The same effect as that of the press device having the cavity 28b described above 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 anisotropic 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 the outer rotor type or the inner rotor type.

  Moreover, the resin mold ring 54 shown in FIG. 15 and FIG. 16 can be obtained using the some sintered compact G3 (refer FIG. 11).

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

  Referring to FIG. 17A, first, four corners of sintered body G3, that is, a connection portion between first arc surface 48a and first side surface 48c, and a connection portion between first arc surface 48a and 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 further deeply cut to form a notch M4. In this way, a sintered body G4 having chamfered portions C1 to C4 at the four corners and a notch M4 at the center of the second arc surface 48b is obtained.

  Then, referring to FIG. 17B, a mold die 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 (in this embodiment, 28) protrusions for positioning the sintered body G4 are formed on the inner surface of the groove 56. The parts 60 are formed at equal intervals.

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

  In that state, a resin mold member 62 is formed by injecting resin from the gap between adjacent sintered bodies G4.

  Thus, a resin mold ring 54 in which a plurality (28 in this embodiment) of the sintered bodies 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 include the first side surface 48c of one sintered body G4 and the second side surface 48d of the other sintered body G4. Are arranged adjacent to each other with a gap therebetween. The resin mold member 62 holds the 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 the respective end surfaces in the axial direction of each sintered body G4 when 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. The resin mold member 62 resin molds each sintered body G4 so as to cover the chamfered portions C1 to C4. On the outer peripheral surface of the resin mold member 62, recesses 64a and 64b connected to both ends of the notch M4 are formed. In addition, when the resin mold ring 54 is manufactured, both end surfaces of each sintered body G4 are supported by two pins, respectively. As a result, a plurality of holes 66 are formed at both axial ends of the resin mold member 62.

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

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

  Since each sintered body G4 has the notch M4 formed in the center part of the 2nd arc surface 48b, the notch M4 can be used for positioning of each sintered body G4.

  Further, the resin mold ring 54 is magnetized, that is, the plurality of sintered bodies G4 arranged in a ring shape are magnetized NS alternately, thereby generating a main magnetic flux on the inner diameter side. A sintered ring magnet having a directivity (hereinafter referred to as “resin-molded ring magnet”) is obtained. The obtained resin mold ring magnet is used for an 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 alternately magnetized NS, so that the sintered ring magnet 100 shown in FIG. A sintered ring magnet having poles and having polar anisotropy that generates a main magnetic flux on the inner diameter side (hereinafter referred to as an “adhesion-fixed ring magnet”) is obtained. And the examination result of a resin mold ring magnet and an adhesive fixing ring magnet is shown. The resin mold ring magnet and the adhesive fixing ring magnet have the same outer diameter (diameter) of 80 mm, inner diameter (diameter) of 74 mm, and height of 16 mm, and are configured with 28 poles. The height of the magnetized sintered body G4 is 12 mm.

  About the resin mold ring magnet and the adhesive fixing ring magnet, the surface magnetic flux density of the inner and outer diameters was measured using a gauss meter. Here, for each sintered ring magnet, the surface magnetic flux density on the inner diameter side (indicated as “inner diameter side R36” in FIGS. 18A and 18B) is measured at the center in the axial direction and 1 mm from the inner surface. The surface magnetic flux density on the outer diameter side (indicated as “outer diameter side R42” in FIGS. 18A and 18B) was measured at a position 2 mm from the outer center in the axial direction.

  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 mold ring magnet, the surface magnetic flux density waveform shown in FIG. 18B was obtained, and the distribution of the surface magnetic flux density peak on the inner diameter side shown in FIG. 19B was obtained. 19A and 19B corresponds to the 28 magnetized sintered bodies G4 included in the sintered ring magnet.

  Referring to FIGS. 18A and 18B, in any sintered ring magnet, 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 smaller as shown by the broken line, and it is understood that the Halbach orientation is generally achieved. Accordingly, in any sintered ring magnet, there is almost no magnetic flux leakage on the outer side in the radial direction of each integrated sintered body G4, and therefore, the outer periphery of the sintered ring magnet is made of a nonmagnetic 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 covered member) via the second arc surface 48b. Drive member) can be firmly attached. Moreover, when attaching another member to the resin mold ring magnet, the notch M4 can be used for positioning or preventing rotation of the resin mold ring magnet.

  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 swell of the surface magnetic flux density peak on the inner diameter side is reduced in the resin-molded ring magnet 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 of the resin mold ring magnet with a 3D measuring instrument, the inner diameter (diameter) of the upper side, the center, and the lower side in the axial direction is within 73.996 mm to 74.005 mm, and the outer diameter at the axial center is The (diameter) is 80.19 mm, the dimensional accuracy of the inner and outer diameters of the resin mold ring magnet is improved, and the roundness is improved.

  Thus, according to the resin mold ring magnet, the dimensional accuracy of the inner and outer diameters becomes good and the variation in the surface magnetic flux density distribution becomes small.

  In the embodiment described above, in the resin mold ring 54, the resin mold member 62 has been described as holding each sintered body G4 so that the first arc surface 48a and the second arc surface 48b are exposed. It is not limited to this. The resin mold member may hold each sintered body G4 so that one of the first arc surface 48a and the second arc surface 48b is exposed, or hold each sintered body G4 so as to cover the entire surface. May be.

  In the above-described embodiment, the case where the sintered body G4 includes the chamfered portions C1 to C4 has been described. However, the present invention is not limited thereto, and any one of the chamfered portions C1 to C4 may be included. Further, the notch included in the sintered body G4 may be a notch M3 instead of the notch M4, and may have an arbitrary dimension.

  In the above-described embodiment, the case where the resin mold ring 54 includes the sintered body G4 has been described. However, the present invention is not limited to this. The resin mold ring may include sintered bodies E3, F3, G3, H3, or those obtained by chamfering any of them.

  In the above-described embodiment, the case where six (three pairs) cavities are formed in the die has been described. However, the present invention is not limited to this. In the die, only one cavity may be provided closer to one of the coils 20 than the center line P1. Moreover, only a pair of cavities may be provided in the die at a symmetrical position with respect to the center line P1. In addition, 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 nonmagnetic 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. However, the present invention is not limited to this, and the end of the die and the end of the yoke It may not be flush with the first direction.

  Moreover, although the above-mentioned embodiment demonstrated the case where a coil was accommodated in the groove | channel formed in the yoke side surface, it is not limited to this. As long as it is on the side of the yoke that contacts the die, the coil may be provided in other manners such as being embedded in the yoke.

  In addition, as the magnet powder to be used, an alloy powder for Nd—Fe—B based sintered magnet is given as an example, but other than that, Sr based ferrite magnet, Ba based ferrite magnet, Sr—La—Co based ferrite magnet, An alloy powder used for a Ca—La—Co ferrite magnet is also applicable.

  In addition, the sintered body produced in the present invention may have a flat cross-sectional shape other than the circular arc shape used for the inner rotor and the outer rotor. By adopting a rectangular cross-sectional shape, it can be applied to a magnetic circuit of a linear motor and other magnetic field generators.

10, 10a Press device 12, 12a Die 14 Lower punch 16 Upper punch 18a, 18b Yoke 20 Coil 22, 22a Through hole 24a, 24b Die side surface 24c, 24d Die end portion 28, 28a, 28b, 28c Cavity 30a, 30b , 32a, 32b Yoke end 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 Protruding portion 54 Resin mold ring 62 Resin mold member 100 Sintered ring magnet C1, C2, C3, C4 Chamfered portions D1, D5 Ends of the first arc portion and the second arc portion Part spacing D2, D6 Distance between the central part of the first arc part and the second arc part D3 Distance from the center in the second direction of the cavity located at the extreme end to the end part of the die D4 between adjacent cavities in the second direction Distance between center in 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 First direction Y Second direction

Claims (18)

A die that penetrates in the vertical direction and has a through-hole having a circular arc cross section;
A lower punch that is inserted into the through hole of the die and forms a cavity of an upper surface opening together with the die;
An upper punch provided in the cavity so as to be insertable from above;
A pair of yokes provided on both sides of the die so as to sandwich the cavity from the side;
A pair of coils provided on the side surface 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 cross-sectional shape of the cavity includes a first arc portion and a second arc portion that are spaced apart from each other in a first direction in which the pair of coils face each other and extend in a second direction orthogonal to the first direction, respectively. , A first side connecting each one end of each of the first arc and the second arc, and a second side connecting each other end of the first arc and the second arc. And the first arc portion is closer to the side of the die than the second arc portion,
The cavity is provided on one of the coil sides with respect to the center of the die in the first direction,
A pressing apparatus in which, when an orientation magnetic field is applied, a current is passed through the pair of coils such that orientation magnetic fields generated by the pair of coils have opposite polarities. The die has a pair of cavities sandwiched between the pair of coils,
2. The press device according to claim 1, wherein the pair of cavities are provided at symmetrical positions with respect to a center line passing through the center of the first direction and extending in the second direction of the die. The die has a plurality of the pair of cavities formed in parallel in the second direction,
On each side surface of the pair of yokes in contact with the die, for each pair of the cavities, the pair of coils are disposed so as to sandwich the pair of cavities,
3. The press device according to claim 2, wherein when an orientation magnetic field is applied, a current is passed through the coils such that the orientation magnetic fields generated by the coils adjacent in the second direction have the same polarity.   The press device according to any one of claims 1 to 3, wherein a distance between the first arc portion and the second arc portion of the cavity is larger at a center portion than both end portions of the cavity in the second direction. .   The press device according to any one of claims 1 to 4, wherein the die is made of a nonmagnetic cemented carbide.   The press apparatus according to claim 2 or 3, wherein the first arc portion corresponds to an inner diameter side of a molded body obtained by the pressing apparatus, and the second arc portion corresponds to an outer diameter side of the molded body.   The press device according to claim 2 or 3, wherein the first arc portion corresponds to an outer diameter side of a molded body obtained by the pressing device, and the second arc portion corresponds to an inner diameter side of the molded body.   The distance in the second direction from the center in the second direction of the cavity located at the end in the second direction to the end of the yoke on the cavity side is the first of the cavities adjacent to the second direction. The press apparatus according to claim 3, which is ½ of the distance between the centers in the 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 a central portion in the second direction. A die having a through-hole penetrating in the vertical direction and having an arc-shaped cross-section, a lower punch inserted into the through-hole of the die and forming a cavity having an upper surface opening together with the die, and provided so as to be insertable into the cavity from above An upper punch, a pair of yokes provided on both side surfaces of the die so as to sandwich the cavity from the side, and a side surface in contact with the die in each of the pair of yokes, and the cavity A pair of coils facing each other so as to sandwich the cavity, and a cross-sectional shape of the cavity is a second that is spaced from each other in a first direction orthogonal to the vertical direction and orthogonal to the first direction. A first arc part and a second arc part extending in a direction, a first side part connecting each one end part of the first arc part and the second arc part, and the first arc part And a second side connecting each other end of the second arc part, the first arc part being closer to the side of the die than the second arc part, The cavity is a method for manufacturing a sintered body using a press device, which is provided on one of the coils side of the die in the first direction center,
Filling the cavity with magnet powder;
The upper punch is lowered toward the cavity, and an electric current is passed through the pair of coils so that the orientation magnetic fields generated by the pair of coils have opposite polarities, thereby causing the magnet powder in the cavity to Applying an orientation magnetic field to orient the magnet powder;
Further lowering the upper punch to obtain a molded body;
And sintering the molded body to obtain a sintered body that is polar-anisotropically oriented. A first arc surface and a second arc surface that are arc-shaped in cross section and spaced from each other; a first side surface that connects one end of each of the first arc surface and the second arc surface; An arc surface and a second side surface connecting the other end of each of the second arc surfaces;
A sintered body that is polar-anisotropically oriented so that an easy axis of magnetization converges from the first side surface and the second side surface toward the first arc surface.   The sintered body according to claim 11, wherein the first arc surface is on the inner diameter side and the second arc surface is on the outer diameter side.   The sintered body according to claim 11, wherein the first arc surface is on the outer diameter side and the second arc surface is on the inner diameter side.   The sintered body according to any one of claims 11 to 13, wherein the second arc surface has a notch formed in a central portion thereof. A plurality of sintered bodies according to claim 11 arranged in a ring shape;
A resin mold member holding the plurality of sintered bodies,
The adjacent sintered bodies are resin mold rings in which the first side face of one of the sintered bodies and the second side face of the other sintered body are arranged adjacent to each other with a gap therebetween.   The resin mold ring according to claim 15, wherein the resin mold member holds the plurality of sintered bodies so that the first arc surface and the second arc surface are exposed. 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 connection between the second arc surface and the first side surface. And a chamfered portion formed on at least one of the connecting portions between the second arc surface and the second side surface,
The resin mold ring according to claim 15 or 16, wherein the chamfered portion is covered with the resin mold member.   Each said sintered compact is a resin mold ring in any one of Claim 15 to 17 which has a notch formed in the center part of the said 2nd arc surface.

Images