JP4471698B2 - Mold, permanent magnet magnetic field molding machine, and method for manufacturing permanent magnet - Google Patents

Description

  The present invention relates to a synchronous permanent magnet rotating machine such as a servo motor, a DC brushless motor, and a generator, a permanent magnet, and a permanent magnet magnetic field molding machine.

Permanent magnet rotating machines are used for control motors such as servo motors because of their high efficiency and good controllability. A method of manufacturing a C-shaped magnet having a parallel easy magnetization direction, which has been conventionally used in a permanent magnet rotating machine, will be described.
Ferrite magnets such as Ba ferrite and Sr ferrite, and rare earth magnets such as Sm-Co and Nd-Fe-B are widely used as anisotropic sintered magnets. The use of magnets is growing rapidly. In these anisotropic sintered magnets, the direction of easy magnetization of each crystal grain carrying magnetism is aligned in a certain direction, and therefore, the direction of easy magnetization of crystal grains is in a different direction, etc. Compared to isotropic magnets, the residual magnetic flux density is large when magnetized in the easy magnetization direction, and therefore the maximum energy product can be increased. In addition, since it is a sintered magnet, the amount of nonmagnetic substance is small compared to a bonded magnet bonded with resin or the like, so that the value of residual magnetic flux density is increased and the maximum energy product can be increased. Therefore, anisotropic sintered magnets are widely used as permanent magnet materials because they can obtain the largest maximum energy product among magnets using the same material.

Anisotropic sintered magnets pulverize the material until each pulverized powder becomes a single crystal and apply an external magnetic field to the pulverized powder in order to align the direction of easy magnetization of magnetic crystal grains in a certain direction. By doing so, the magnetization easy axis of the magnet powder is aligned in a direction parallel to the direction of the external magnetic field, and compression is performed by applying pressure. Thereafter, the molded magnet powder is sintered under a predetermined condition to produce an anisotropic sintered magnet. Depending on the material, heat treatment may be required after sintering. For example, in a Sm ₂ Co _17- based magnet, a solution treatment is performed after sintering, and an aging treatment is further performed. In the Nd—Fe—B system magnet, the magnet is manufactured by performing heat treatment at around 500 ° C. after sintering.

  The magnetic field press used in the molding process usually comprises a die, an upper punch, a lower punch and a magnetic field generating means. Magnet powder is supplied into a cavity composed of a die, upper punch and lower punch, and an orientation magnetic field is applied by a magnetic field generating means to align the easy magnetization direction of the magnet powder in one direction, and pressure is applied by the upper punch and lower punch. To form magnet powder in the cavity. The molding is generally performed by applying a static magnetic field with an electromagnet or the like and applying the static magnetic field. The direction in which an orientation magnetic field is applied to the magnet powder filled in the cavity includes vertical magnetic field shaping in which a magnetic field is applied in a direction parallel to the direction of pressure application by the upper and lower punches, and transverse magnetic field shaping in which a magnetic field is applied in the vertical direction. Whether to select transverse magnetic field shaping or longitudinal magnetic field shaping is determined by the material to be produced, characteristics, shape, magnetization direction, etc., but sintered magnets produced by longitudinal magnetic field shaping are Since magnetic characteristics are deteriorated as compared with the case, transverse magnetic field shaping is often used.

In order to form a C-shaped or D-shaped magnet for a rotating machine in a transverse magnetic field, a die having a cavity formed in consideration of shrinkage during sintering as shown in FIG. 11 is used. FIG. 11 shows a case where three magnets can be molded in the same direction at the same time. Actually, the size varies depending on the size of the molding machine and the size of the cavity, and as many cavities as possible are arranged to increase the molding efficiency. Not exclusively. Further, in order to make the orientation magnetic field in the cavity parallel, it is also disclosed in Patent Document 1, but the die is made of a material having a magnetization of saturation magnetization 4πIs of 500 to 12,000 gauss, and the die and the molded body are as if they are one. To be considered as a magnetic material. When the permanent magnet made in this manner is used, the easy magnetization direction is parallel to the reference line with the center line of the permanent magnet as shown in FIG. 12 as the reference line (the angle between the reference line and the easy magnetization direction is 0 °). ) Permanent magnet rotor can be obtained.
Japanese Patent Laid-Open No. 9-35977

  By the way, the torque of an AC servo motor or the like that requires high-accuracy torque control must have a small pulsation. Therefore, when the permanent magnet rotates, the cogging torque (torque in a state where no current flows through the coil) or the coil due to the change in the magnetic flux distribution in the gap is determined from the positional relationship between the stator slot and the permanent magnet. It is not preferable that torque ripple occurs when driven by passing an electric current. Torque ripple causes noise as well as poor controllability.

  An object of the present invention is to provide a permanent magnet rotating machine and a permanent magnet with high output and high precision control with reduced cogging torque.

  The present inventor has intensively studied to solve the above problems, and has made the following improvements to a rotating machine using an eccentric magnet having a small cogging torque, thereby realizing a smooth rotation without torque unevenness.

The present invention has a C shape composed of two lines connecting an outer arc with an arc facing outward and an inner arc with the arc facing inward and both arcs, or a D shape composed of an outer arc and three lines. The number of cavities is an integral multiple of 2, and (i) cavities arranged so that the outer arcs of the cavities are in symmetric contact with each other (for reference example (ii) (Iii) a cavity in which the outer arc side is symmetrically disposed across the magnetic piece, or (iii) a cavity in which the magnetic piece is arranged on the outer arc side of the cavity ) , a die forming the cavity, and the inside of the cavity is compressed In order to achieve this, a die comprising a punch that can be linked to a press is provided.
Further, the present invention provides the mold, at least two magnets arranged so as to sandwich the mold and applying a magnetic field in a certain direction to the mold, and the cavity in conjunction with the punch of the mold. A permanent magnet magnetic field molding machine comprising a press for compressing in a direction perpendicular to the direction, and as a reference example , the mold is filled with permanent magnet powder, and a magnetic field having a constant magnetic field direction is obtained. The mold is arranged so that the magnetic field direction is substantially parallel to the opposing two lines of the C-shaped cross section or D-shaped cross section of the mold, the easy magnetization direction of the permanent magnet powder is oriented, and the magnetic field direction is It performs compression molding in a direction perpendicular against, to provide a manufacturing how the permanent magnet and then sintered.

  According to the present invention, the driving torque can be improved while reducing the cogging torque, which is useful for improving the performance and miniaturization of an AC servo permanent magnet motor, a DC brushless permanent magnet motor, etc., and its utility value is extremely high in the industry.

Hereinafter, the present invention will be described in more detail with reference to the drawings.
Permanent magnet rotating machines are used for control motors such as servo motors because of their high efficiency and good controllability. For example, a radial air gap type permanent magnet rotating machine as shown in FIG. 1 is used for the AC servo motor. The permanent magnet rotating machine 1 shown in FIG. 1 includes a rotor 4 with a C-shaped permanent magnet 3 attached to the surface of a rotor yoke 2 and a plurality of slots arranged via gaps (gap) 5. The stator yoke includes a stator 8 including a coil 7 wound around a tooth 6. In the case of the permanent magnet rotating machine shown in FIG. 1, the number of poles of the permanent magnet is 6, the number of teeth is 9, and the arrow in the permanent magnet indicates the direction of magnetization of the permanent magnet. Further, the coil is wound around the teeth in a concentrated manner, and a three-phase Y-connection of the U phase, the V phase, and the W phase is made, and the number of turns of the coil is 50 turns per tooth. U + of the coil means that the winding direction of the U-phase coil is in front, and U- means that the winding direction of the U-phase coil is in the back.

As a reference example, a rotor including a rotor yoke and a plurality of permanent magnet segments attached to a side surface of the rotor yoke and having a P pole (P is an integer of 4 or more), and a concentric circle with the rotor A permanent magnet rotating machine including a stator wound around an iron core having a plurality of slots and disposed outside the rotor via a gap, the permanent magnet rotating machine comprising: In a cross section, each of the permanent magnet segments has a line connecting the center of the rotor and the center of each permanent magnet segment as a reference line, the center of the rotor is the center of rotation, and a counterclockwise direction is positive. The angle α formed between the easy magnetization direction and the reference line at the position of the angle θ in the positive direction from is in a range of α = (180 / P−90) ° to 0 ° and is symmetric with respect to the reference line. A permanent magnet rotating machine having an easy magnetization direction is provided.
In the example of the permanent magnet rotating machine 1, as shown in FIGS. 2 and 3, in the permanent magnet rotating machine having an eccentric magnet, the center 11 of the rotor is rotated with the center line of the permanent magnet as the reference line at an angle of 0 °. The angle α between the easy magnetization direction 12 and the reference line at the position of the angle θ in the positive direction with respect to the reference line with the counterclockwise direction as the center of is α = (180 / P−90) ° to 0 °. A permanent magnet rotor whose easy magnetization direction is symmetric with respect to the reference line is used. That is, a permanent magnet rotor in which the easy magnetization direction of the permanent magnet is directed toward the center line is used. As a result, smooth rotation without torque unevenness is achieved, and cogging torque is reduced.
Further, the magnet of the present application is inclined with respect to the reference line toward the arc end.

  As shown in FIG. 2, the permanent magnet rotor of the present invention has a structure in which permanent magnets 3 magnetized with N and S poles are alternately attached to the side surface of the rotor yoke 2. The shape of the permanent magnet is a C-shaped cross section in FIG. 2, but it may be D-shaped as shown in FIG. 4B, and the inner peripheral shape is an inner peripheral shape that matches the side surface of the rotor yoke. It may be adjusted by cutting and processing.

As a method for reducing the cogging torque, as shown in FIG. 4, there is a method using a permanent magnet in which the center of the outer diameter of the C-shape or D-shape is eccentric so that the end shape of the permanent magnet is thin. FIG. 4 shows an example of (a) C-shaped eccentric magnet and (b) D-shaped eccentric magnet having an eccentric amount c at the outer radius a connecting the vertices of the permanent magnet and the outer radius b of the permanent magnet. 4A shows the outer radius d of the rotating yoke, and FIG. 4B shows the inscribed circle radius e of the rotating yoke.
According to this method, the magnetic flux distribution at the end of the permanent magnet, which is the switching portion of the magnetic pole where the change of the magnetic flux distribution is large, becomes smooth, and the cogging torque can be reduced. However, since the magnet volume is reduced, the driving torque is also reduced. If the length is increased in the axial direction or the outer diameter is increased in order to obtain a target driving torque, the device becomes larger. Therefore, it is preferable to reduce the amount of eccentricity as much as possible in order not to increase the size of the device.
In addition, the point of each permanent magnet segment that is farthest from the center of the rotor at the angle θ and the distance between the center and the point of each permanent magnet segment that is farthest from the center of the rotor on the reference line It is preferable that the distance is smaller than the distance from the center and smaller as the angle θ increases. This is because the magnetic flux distribution at the switching portion of the magnetic pole becomes smooth as the thickness of the magnet end becomes thinner.

  In the permanent magnet rotating machine of FIG. 1, the angle formed between the easy magnetization direction and the reference line at the position of the angle θ ° with respect to the reference line is parallel to −θ °, with the center line of the permanent magnet as the reference line at an angle of 0 °. The relationship between the amount of eccentricity of the magnet (explained in FIG. 4) and the cogging torque was investigated using a rotor with 0 ° orientation. The driving conditions of the motor are the same as in the examples described later.

  FIG. 5 shows the relationship between the amount of eccentricity and the cogging torque. If the amount of eccentricity is increased, the cogging torque can be reduced. When the easy magnetization direction is −θ °, the cogging torque is small even if the eccentricity is small. Therefore, the amount of eccentricity when the target cogging torque is the same can be made smaller than that of the parallel orientation product.

  FIG. 6 shows the relationship between the amount of eccentricity and torque. When the amount of eccentricity is increased, the volume of the magnet is reduced, so that the torque is reduced. When compared with the same amount of eccentricity, the direction of easy magnetization of −θ ° is smaller than that of the parallel-oriented product, but the difference is not large.

  In order to realize a rotating machine with a small cogging torque and a large driving torque, it is important how the cogging torque can be reduced with a permanent magnet having a small eccentricity. 5 and 6, when the easy magnetization direction of the permanent magnet is toward the center line, the cogging torque can be reduced with a smaller amount of eccentricity than the conventional (θ = 0 °) parallel orientation, and the amount of eccentricity is small. Minute torque increases. That is, it has been found that a low cogging torque and a high torque rotating machine can be realized as long as the easy magnetization direction of the permanent magnet is directed toward the center line. Here, the angle formed between the easy magnetization direction and the reference line at a position of an angle θ ° from the reference line of the permanent magnet is at least (180 / P−90) °. If it is smaller than this, the polarity is reversed. For example, since the rotating machine of FIG. 1 has P = 6 poles, the minimum angle is −60 °. At the arc end of the 6-pole magnet, θ = 30 ° and the easy magnetization direction angle of −60 ° is directed in the circumferential direction. The maximum is smaller than 0 ° of parallel orientation. Further, the angle of the easy magnetization direction at the position of θ ° is not always linear and changing. For example, when the angle of the easy magnetization direction at θ = 10 °, 20 °, and 30 ° changes linearly as −10 °, −20 °, −30 °, or θ = 10 °, 20 °, 30 There are cases where the angle of the easy magnetization direction at ° changes non-linearly, such as −10 °, −10 °, and −20 °. Therefore, P is a pole number that is an integer of 4 or more.

  Next, a method for manufacturing a permanent magnet in which the easy magnetization direction of the permanent magnet is directed toward the center line will be considered. In a conventional method for forming a C-shaped or D-shaped magnet for a rotating machine in a transverse magnetic field, a permanent magnet having a parallel orientation is obtained using a magnetic die as described above. For example, FIG. 11 shows a mold 111 having a magnetic die 112 and a cavity 113 filled with magnet powder 114 and placed in an orientation magnetic field 115, and FIG. As a reference line, an easy magnetization direction 104 of the permanent magnet 103 on the side surface of the rotary yoke 102 at a position of an angle θ in the positive direction from the reference line with the center 101 of the rotor as the center of rotation and positive counterclockwise is shown. .

  FIG. 13 shows a die made of a non-magnetic material, and a die 121 having a non-magnetic die 122 and a cavity 123 is filled with magnet powder 124 and placed in an orientation magnetic field 125. If the die is made of a non-magnetic material, the orientation magnetic field tends to pass through the magnetic powder, which is a magnetic material. Therefore, the orientation magnetic field is located further away from the center line of the permanent magnet and the orientation magnetic field direction is directed toward the center line. Think. However, when there are a large number of cavities as shown in FIG. 13, the alignment magnetic fields in the individual cavities are different and the magnetic field varies. Variation in the orientation magnetic field is undesirable because it adversely affects the cogging torque.

  FIG. 14 shows a die made of a non-magnetic material and a single cavity, and a mold 131 having a non-magnetic die 132 and a cavity 133 is filled with magnet powder 134 and placed in an orientation magnetic field 135. . If one cavity is used, the variation in the orientation of the magnet is reduced, but there is a problem in productivity.

  Therefore, the number of the C-shaped cavities is an integral multiple of 2 and the upper limit is 18, preferably 4. The two cavities are arranged in contact with each other on the outer peripheral side of the cavity and symmetrically arranged. The orientation magnetic field when using this die is as shown in FIG. FIG. 7 shows a mold 21 having a nonmagnetic die 22 and a cavity 23 filled with magnet powder 24 and placed in an orientation magnetic field 25 generated by a magnet 26. Also in this case, since it tries to pass through the magnet powder which is a magnetic substance, the orientation magnetic field can be directed to the center line side of the permanent magnet. Even if there are a large number of cavities as shown in FIG. 7, the shape of the cavities is symmetrical, so there is no variation in orientation between the cavities. Furthermore, the angle of the orientation magnetic field becomes larger than that of FIG. 14 due to the shape effect. Although a nonmagnetic die is used in FIG. 7, the angle between the orientation magnetic field and the permanent magnet center line can be controlled by changing the magnetic characteristics of the die.

  FIG. 8 shows a case in which a magnetic die is used, in which a magnetic powder 34 is filled in a die 31 having a nonmagnetic die 32 and a cavity 33 and placed in an orientation magnetic field 35. In this case, the angle becomes smaller than the orientation magnetic field of FIG. The saturation magnetization 4πIs of the die is 12000 gauss or less. In the present invention, it is preferable that the saturation magnetization 4πIs of the magnetic material used as the die material is 12000 gauss or less. Even within this range, it is particularly preferable to use a magnetic material having a saturation magnetization in the range of 0 to 8000 gauss because the effects of the present invention remarkably appear. When the saturation magnetization 4πIs is greater than 12000 Gauss, the orientation magnetic field is an angle formed between the easy magnetization direction and the reference line at a position of an angle θ ° from the reference line with the center line of the permanent magnet as the reference line at an angle of 0 °. Becomes larger than 0 °.

  FIG. 9 shows a mold 41 having a die 42 and a cavity 43 filled with magnet powder 44 and placed in an orientation magnetic field 45. As shown in FIG. 9, the number of the C-shaped cavities is an integral multiple of 2 (illustrative is 4), and the outer peripheral side of the cavities are arranged symmetrically with the magnetic piece between them in pairs. Has the same effect. In this case, the orientation magnetic field can also be controlled by changing the shape and saturation magnetization of the magnetic piece placed between the cavities. The shape of the magnetic piece may be a rectangular parallelepiped, a cylinder, an elliptic cylinder, or the like, and may be a magnetic substance such as iron. Preferably, the saturation magnetization of the magnetic piece is larger than the saturation magnetization of the die, and if the saturation magnetization of the magnetic piece is larger than the saturation magnetization of the die, the magnetic flux concentrates on the magnetic piece and the orientation magnetic field is Effective for facing the center line. For the same reason, it is preferable that the magnetic piece is made of a material having magnetism larger than the saturation magnetization of the punch.

FIG. 10 shows a mold 51 having a die 52 and a cavity 53 filled with magnet powder 54 and placed in an orientation magnetic field 55. As shown in FIG. 10, when the C-shaped cavity has a shape in which magnetic pieces are arranged on the outer peripheral side of the cavity, the angle between the orientation magnetic field and the permanent magnet center line is larger than that of the conventional mold shown in FIG. In addition, the angle of the orientation magnetic field can be controlled by changing the size and shape of the saturation magnetization of the magnetic piece.
The cavities of FIGS . 7 to 8 of the present invention and FIGS . 9 to 10 of the reference example are C-shaped magnets, and the same applies to D-shaped magnets.

  In the present invention, it is preferable that not only the die but also the upper punch and the lower punch are made of a material having a saturation magnetization of 4πIs of 12000 gauss or less because the angle control of the orientation magnetic field is effective. At this time, the entire upper punch and lower punch may be made of a magnetic material, but only the tip portion in contact with the molded body may be made of a magnetic material.

As the material having a saturation magnetization 4πIs of 12000 gauss or less according to the present invention, cemented carbide or alloy carbon steel is desirable. Cemented carbide refers to carbide powder of metals belonging to groups IVa, Va, VIa such as WC, TiC, MoC, NbC, TaC, Cr ₃ C ₂ , Co, Ni, Mo, Fe, Cu, Pb, Sn, or These are alloys that are sintered and bonded using these alloys, and the magnetism depends on the amount of carbon contained in the cemented carbide and the amount of iron, cobalt, nickel, etc., and the type and amount of additives. It changes variously. Any cemented carbide can be applied to the present invention as long as it has predetermined magnetic properties.

  The alloy carbon steel is an alloy mainly composed of Fe-C, and in particular, die steel, carbon tool steel, alloy tool steel, high speed steel, and the like are preferably used. Any of these alloy carbon steels can be used as long as they have predetermined magnetic properties.

Moreover, as an anisotropic sintered magnet, ferrite magnets such as Ba ferrite and Sr ferrite, rare earth magnets such as Sm—Co and Nd—Fe—B, and the like can be used.
The average particle size of the magnet powder to be filled in the cavity is not particularly limited, but is preferably 1 to 20 μm. Aging treatment is performed to obtain a sintered magnet.
The sintering temperature varies depending on the magnet, but preferably 1150 to 1300 ° C. for ferrite, 1100 to 1250 ° C. for Sm—Co, and 1000 to 1100 ° C. for Nd—Fe—B.

Hereinafter, the embodiment will be described in detail. Although an Nd—Fe—B permanent magnet will be described, the present invention is not limited to an Nd—Fe—B based magnet. The permanent magnet was manufactured by the following process. Each of Nd, Fe, Co, and M (M is Al, Si, Cu) having a purity of 99.7% by weight and B having a purity of 99.5% by weight was melt-cast in a vacuum melting furnace to produce an ingot. The ingot was coarsely pulverized with a jaw crusher, and fine powder having an average particle size of 3.5 μm was obtained by jet mill pulverization in a nitrogen stream. In the comparative example, this fine powder was filled in the cavity of four molds made of the mold shown in FIG. 11 and in Example 1 made of a nonmagnetic cemented carbide shown in FIG. Molding was performed at a molding pressure of 0.0 t / cm ² . This molded body was sintered in Ar gas at 1090 ° C. for 1 hour, and subsequently heat-treated at 580 ° C. for 1 hour. The sintered body after the heat treatment is connected on the outer diameter side of the C-shaped magnet, but it can be easily broken by a tool because there are few joint surfaces. The fracture surface is along the outer diameter of the C-shaped magnet. Thereafter, grinding with a grindstone was performed to obtain a C-shaped permanent magnet. The characteristics of the permanent magnet were Br: 13.0 kG, iHc: 22 kOe, (BH) max: 40 MGOe.

  As a comparative example, the depth of the rotor and the stator in FIG. 1 is 40 mm, and the outer diameter of the rotor is 40 mm. Using a C-shaped permanent magnet made of a cemented carbide having a saturation magnetization of 4000 G, which is a magnetic material shown in FIG. 11, the cogging torque of a rotating machine having parallel easy magnetization directions shown in FIG. The driving torque when current was input to was measured. The cogging torque was measured by fixing the shaft of a permanent magnet rotating machine to a torque detector and rotating one of the shafts at a slow speed of 10 rpm or less with another permanent magnet rotating machine. The driving torque is obtained when a sine wave three-phase alternating current having an effective value of 2 A is input to each coil.

  The outer diameter of the permanent magnet is eccentric in order to reduce cogging torque. As shown in FIG. 5, when the amount of eccentricity is increased, the cogging torque is reduced, and the amount of eccentricity this time is set to 9 mm. Table 1 shows the values of the cogging torque and the driving torque. The cogging torque is the difference between the maximum value and the minimum value of the pulsating waveform, and the driving torque is an average value. In this permanent magnet rotating machine, the cogging torque is set to 0.01 Nm or less, and the cogging torque in the comparative example clears the target value. The driving torque at this time was 0.695 Nm.

  As Example 1, a C-shaped permanent magnet manufactured with the mold shown in FIG. 7 was used, and the rotor with the easy magnetization direction of the permanent magnet as shown in FIG. The cogging torque and driving torque of the rotating machine incorporated in the child were evaluated. The driving conditions were the same as in the comparative example.

  As in the comparative example, the outer diameter of the permanent magnet was decentered in order to reduce the cogging torque. As shown in FIG. 5, when the amount of eccentricity is increased, the cogging torque is reduced, and the amount of eccentricity this time is set to 6 mm. Table 1 shows the values of the cogging torque and the driving torque. The cogging torque is substantially the same as the comparative example, and is the target of 0.01 Nm or less. The driving torque at this time was 0.741 Nm, and the driving torque was improved by 6.6% from the comparative example.

As a reference example 2, a C-shaped permanent magnet manufactured with the mold shown in FIG. 9 was obtained, and the rotor with the easy magnetization direction of the permanent magnet as shown in FIG. The cogging torque and driving torque of the rotating machine incorporated in the child were evaluated. Note that the die of FIG. 9 uses a non-magnetic cemented carbide, and the saturation magnetization of the magnetic piece is 18000 gauss. The driving conditions were the same as in the comparative example.

  As in the comparative example, the outer diameter of the permanent magnet was decentered in order to reduce the cogging torque. As shown in FIG. 5, when the amount of eccentricity is increased, the cogging torque is reduced, and the amount of eccentricity this time is set to 6 mm. Table 1 shows the values of the cogging torque and the driving torque. The cogging torque is substantially the same as the comparative example, and is the target of 0.01 Nm or less. The driving torque at this time was 0.755 Nm, and the driving torque was improved by 8.6% from the comparative example.

A radial air gap type permanent magnet rotating machine is shown. 1 shows a permanent magnet rotor. The easy magnetization direction at an angle θ is shown. (A) shows a C-shaped eccentric magnet, and (b) shows a D-shaped eccentric magnet. The relationship between the amount of eccentricity and the relationship between cogging torque is shown. The relationship between the amount of eccentricity and the relationship of torque is shown. 2 shows the dice and orientation magnetic field of the present invention. 2 shows the dice and orientation magnetic field of the present invention. The dice | dies and orientation magnetic field of a reference example are shown. The dice | dies and orientation magnetic field of a reference example are shown. 1 shows a conventional die and orientation magnetic field. (A) A conventional permanent magnet rotor and (b) an easy magnetization direction at an angle θ of a conventional permanent magnet rotor are shown. 1 shows a conventional die and orientation magnetic field. 1 shows a conventional die and orientation magnetic field.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Permanent magnet rotating machine 2 Rotor yoke 3 Permanent magnet 4 Rotor 5 Air gap (gap)
6 Teeth 7 Coil 8 Stator 11 Rotor center 12 Easy magnetization direction 21 Mold 22 Nonmagnetic die 23 Cavity 24 Magnet powder 25 Orientation magnetic field 26 Magnet 31 Mold 32 Magnetic die 33 Cavity 34 Magnet powder 35 Orientation magnetic field 41 Mold 42 Nonmagnetic die 43 Cavity 44 Magnet powder 45 Orientation magnetic field 47 Magnetic piece 51 Mold 52 Nonmagnetic die 53 Cavity 54 Magnet powder 55 Orientation magnetic field 57 Magnetic piece 101 Rotor center 102 Permanent magnet 103 Rotor yoke 104 Easy magnetization Direction 111 Mold 112 Nonmagnetic die 113 Cavity 114 Magnet powder 115 Orientation magnetic field 116 Magnet 121 Mold 122 Nonmagnetic die 123 Cavity 124 Magnet powder 125 Orientation magnetic field 131 Mold 132 Nonmagnetic die 133 Cavity 134 Magnet powder 135 Orientation magnetic field a Permanent The top of the magnet Outer radius b to be connected Outer radius c of the permanent magnet c Eccentric amount d Outer radius of the rotating yoke e Inscribed circle radius of the rotating yoke

Claims (2)

C-shaped cross section consisting of two lines connecting the outer arc with the arc facing outward and the inner arc facing the arc with both arcs, or a D-shaped cross section consisting of the outer arc and three lines In order to compress the inside of the cavity, the number of the cavities is an integral multiple of 2 and the cavities are arranged so that the outer arcs of the cavities are in symmetric contact with each other, the dies forming the cavities, and the cavity in comprising a punch which can interlock in the press, oriented in a magnetic field compression molding die of the permanent magnet powder. The mold according to claim 1, at least two magnets arranged so as to sandwich the mold and applying a magnetic field in a certain direction to the mold, and the cavity in the direction of the magnetic field in conjunction with the punch of the mold And a press for compressing in a direction perpendicular to the permanent magnet magnetic field forming machine.

Images