JP4531618B2 - Manufacturing method of ring-type sintered magnet - Google Patents

Description

  This invention is a ring-type sintered magnet obtained by applying a magnetic field in the radial direction and pressing a magnetic powder to form a radially oriented permanent magnet molded product, laminating a plurality of them, and integrating them by sintering. It is about.

  A conventional ring-shaped sintered magnet with a radial orientation uses a magnetic field molding machine for powder molding in which an electromagnetic coil is arranged, and a core and a lower punch are inserted to face a die and a lower punch in which a cavity is formed. The mold material powder composed of the upper punch is filled with the magnetic material molding powder, and the magnetic material molding powder is subjected to radial orientation by applying a magnetic field by a pair of coils disposed around the mold. However, it can be obtained by pressing with an upper punch to form a ring magnet molded body and sintering it.

  In general, when magnetically forming a radial anisotropic ring magnet often used in small motors, when forming a ring-shaped magnet long in the axial direction, sufficient magnetic field strength cannot be obtained, and the orientation rate of the magnetic powder is low. There is a problem that the high magnetic characteristics cannot be obtained.

  When the ring magnet is radially oriented, the magnetic flux passing through the core of the mold that forms the magnetic powder in a ring shape is generally equal to the magnetic flux passing through the inner diameter of the die. (Diameter) is Di, the outer diameter of the ring magnet (die inner diameter of the die) is Do, the height of the ring magnet (die height) is H, the magnetic flux density passing through the core of the die is Bc, and the die inner diameter is If the passing magnetic flux density is Bd, the relationship of the following formula (1) is established.

2 × π / 4 × Di ² × Bc = π × Do × H × Bd (1)

  When a steel material such as S45C is used for the core of the mold, the saturation magnetic flux density of this steel material is about 1.5T. Therefore, in the above formula (1), Bc = 1.5 and the magnetic field necessary for the magnetic field orientation is 1.0T. If it is above, it will be Bd = 1.0T and the height H of the ring magnet which can carry out magnetic field orientation shaping | molding will become following formula (2).

H = 3Di ² / 4Do (2)

  When a ring magnet is magnetically molded, if the axial length of the ring magnet exceeds the value of H in the above formula (2), a decrease in orientation becomes a problem. Therefore, conventionally, a ring magnet having a short axial length equal to or less than the value of H in the above formula (2) is manufactured, and this is joined with an adhesive or the like to manufacture a ring magnet having a required axial length.

  In addition, a method has been proposed in which a magnet molded body having a short magnetic field forming range is stacked in a mold to form a magnet having a required axial length (see, for example, Patent Document 1).

  In addition, a method has been proposed in which a preformed body is formed by magnetic field molding, and a plurality of preformed bodies are pressed and integrated with a pressure greater than the pressure applied during the preforming. (For example, refer to Patent Document 2).

JP-A-9-233776 (page 2-3, FIG. 1) JP-A-10-55914 (page 2-3)

  As described above, the ring magnet obtained by the method of laminating the molded body in the mold has a problem that the magnetic properties of the lamination boundary portion are poor. In addition, the method of repressurizing the preform with a pressurizing force larger than the pressurizing force at the time of preforming deteriorates productivity. Further, when a conventional sintered ring magnet having a long axial length is used by being bonded and fixed to the rotor shaft, there is a problem that the sintered ring magnet is cracked or cracked when the motor is subjected to a heat cycle.

  In order to solve this problem, methods such as increasing the strength of the sintered magnet and bringing the linear expansion coefficient of the sintered magnet closer to the linear expansion coefficient of the rotor shaft can be considered. It is difficult to change the characteristics.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a ring-type sintered magnet having excellent magnetic properties that does not break even when subjected to a heat cycle.

A method for manufacturing a ring-type sintered magnet according to the present invention includes: pressing a magnetic powder into a ring mold; and molding a radially oriented ring-shaped magnet molded body by applying a magnetic field in a radial direction of the ring mold; In a manufacturing method of a ring-type sintered magnet obtained by laminating a plurality of magnet-shaped magnets and integrating them by sintering, the degree of orientation in the radial direction when forming a ring-shaped magnet molded body is 80% or more. By stacking the ring-shaped magnet molded body, a gap is formed on the inner diameter side of the boundary surface of the ring-shaped magnet molded body when the stack is put into a sintering furnace and integrated by sintering. The strength after sintering is made weaker than the strength of the magnet in the portion other than the boundary portion.

In addition, the method for manufacturing a ring-type sintered magnet according to the present invention forms a ring-shaped magnet molded body that is radially oriented by applying a magnetic field in the radial direction of the ring mold while pressurizing the magnetic powder to the ring mold. In a method for manufacturing a ring-type sintered magnet obtained by laminating a plurality of ring-shaped magnet molded bodies and integrating them by sintering, a punch having a cross-sectional shape with a protruding inner diameter side is applied when magnetic powder is pressed onto the ring mold. By using the pressure so that the density of the molded body on the inner diameter side of the ring-shaped magnet molded body is larger than that on the outer diameter side, a gap is formed on the inner diameter side of the boundary surface when a plurality of ring-shaped magnet molded bodies are stacked. provided, a plurality of the magnet molding is sintered integrally put into a sintering furnace by simply stacked, characterized in Rukoto.

According to the method for manufacturing a ring-type sintered magnet of the present invention, the strength after sintering of the laminated boundary portion of the ring-shaped magnet molded body is weaker than the magnet strength of the portion other than the boundary portion. When an external stress such as the above is applied, the boundary portion of the ring-shaped magnet molded body is divided and the stress is relieved, so that it is possible to obtain a ring-type sintered magnet that does not cause defects such as damage to other portions. In addition, it is a ring type that has no effect on the magnetic properties and mechanical strength of the magnet without being cracked or broken in the circumferential direction of the ring simply by being cut at a plane perpendicular to the axis of the ring. A sintered magnet can be obtained . Furthermore, since the ring-shaped magnet molded body having an axial length with sufficient radial orientation is magnetically molded, a ring-shaped sintered magnet having excellent magnetic properties can be obtained .

Further, according to the method for manufacturing a ring-type sintered magnet of the present invention, a ring-type magnet molded body is formed by applying pressure so that the density of the molded body on the inner diameter side of the ring-shaped magnet molded body is larger than that on the outer diameter side. Since a gap is provided on the inner diameter side of the boundary surface when a plurality of layers are laminated, the boundary portion is securely bonded, and a ring-type sintered magnet that is resistant to heat shock and excellent in magnetic properties can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

Embodiment 1 FIG.
1 is a cross-sectional view showing a ring-type sintered magnet according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the ring-type sintered magnet 100 according to Embodiment 1 presses magnetic powder into a ring mold and applies a magnetic field in the radial direction of the ring mold to form a ring-shaped magnet. The body is molded, and a plurality of these ring-shaped magnet compacts are laminated and integrated by sintering. 1 shows an example in which the outer periphery and inner periphery of the ring-shaped cross section are circular, but as shown in FIGS. 22 and 23, the ring-shaped peripheral surface has irregularities (in the figure, the outer peripheral surface has irregularities). However, it may also be obtained by laminating ring molded bodies and integrating them by sintering. Note that the ring-type sintered magnet 220 in FIG. 22 is obtained by laminating a molded body having projections and depressions on the outer peripheral surface of the ring in the axial direction and integrating them by sintering. Further, the ring-type sintered magnet 230 in FIG. 23 is obtained by laminating formed bodies having skewed irregularities on the ring outer peripheral surface and integrating them by sintering.

  In this way, the ring-type sintered magnet obtained by laminating and sintering the short-axis ring-shaped magnet molded body was subjected to a heat cycle because the mechanical strength at the boundary between the ring-shaped molded bodies was reduced. Since the stress is relieved when the boundary portion breaks sometimes, the problem that the entire magnet is broken or a part of the magnet falls off due to a crack is not caused.

  As shown in FIG. 8, the magnet forming apparatus for the ring-type sintered magnet according to this embodiment measures and supplies magnetic powder into the belt conveyor 2 that conveys the conveyance mold 10 and the cavity of the conveyance mold 10. The powder feeding / filling unit 3 for filling and filling, the punch set unit 4 for setting the upper punch for pressurizing the magnetic powder filled in the cavity of the conveying mold 10, and the state where the upper punch is set and can be pressure-molded A magnetic field molding unit 5 for performing magnetic field pressure molding with the transporting mold 10, a demolding unit 6 for extracting the magnetic field pressure molded ring molded body from the transporting mold 10, and the extracted ring molding. A compact de-pulverization unit 7 for removing excess magnetic powder adhering to the body, a stacking unit 8 for stacking the ring compacts subjected to magnetic field pressure molding, and a magnet adhering to the conveyance mold 10 Powder is removed, and a mold removal flour / die set unit 9 to be set in the transport state the conveying molds 10.

  As shown in FIG. 9, the conveyance mold 10 includes a pallet 10a that moves on the belt conveyor 2, holders (first holders) 10b and 10c that hold the lower mold part, a core 10d, a lower punch 10e, A lower mold part consisting of a die 10f forming a cavity 10h to which magnetic powder is supplied by a lower punch 10e and a core 10d, and an upper punch 10g (upper mold) held by another holder (second holder) 10j Part). The annular portion 10c at the upper end of the first holder is a non-magnetic member, and the other portion 10b of the first holder is a ferromagnetic member.

  The positions and directions of the pallet 10a and the holders 10b and 10j, the holder 10b and the lower punch 10e, and the lower punch 10e and the die 10f are regulated by positioning mechanisms using positioning pins, respectively. By providing the positioning mechanism in this manner, positioning is performed when the mold parts are set on the pallet (the upper punch is inserted into the core and the die) or when the transfer mold 10 is transferred to the magnetic field forming unit 5. The process to be performed can be performed easily.

  Hereinafter, the configuration and operation of the permanent magnet molding apparatus according to this embodiment will be described with reference to FIG.

FIG. 10 is a cross-sectional view illustrating the configuration and operation of the powder supply / filling unit 3. FIG. 10A shows a magnetic powder weighing process, and FIGS. 10B and 10C show a powder feeding process to the conveyance mold 10.
As shown in FIG. 8, the powder feeding / filling unit 3 includes a weighing mechanism 3d for weighing the magnetic powder, a conveyance mechanism 3e for weighing and collecting the magnetic powder to the container 3c, and conveying the magnetic powder to the position of the conveyance mold 10. It has. As shown in FIG. 10, the powder supply / filling unit 3 includes a rotation mechanism 3f for rotating and tilting the container 3c, and a powder supply jig 3a for guiding the magnetic powder in the container 3c into the cavity 10h. And a vibration mechanism 3b made of a vibrator or the like that vibrates the powder feeding jig 3a.
When the conveying mold 10 is conveyed to the powder supply / filling unit 3, in the magnetic powder measurement step, the magnetic powder 11 having a constant weight is measured and stored in the container 3c using a vibration feeder and a weight meter.
10 (b) and 10 (c), a funnel-shaped powder feeding jig 3a that guides the magnetic powder to the cavity 10h of the conveyance mold 10 and a feather-shaped jig that stirs the magnetic powder supplied to the cavity 10h. (Not shown) is set on the die 10f of the transfer mold 10, and then the container 3c containing the magnetic powder is moved to the position of the funnel-shaped powder feeding jig 3a, and the container 3c is rotated and tilted. The magnetic powder in 3c is transferred to the funnel-shaped powder feeding jig 3a. Further, an impact is applied to the container 3c with a knocker, and the magnetic powder 11 in the container 3c is transferred to the funnel-shaped powder feeding jig 3a without remaining. Further, vibration is applied to the funnel-shaped powder feeding jig 3a by the vibration mechanism 3b to transfer all the magnetic powder on the powder feeding jig 3a into the cavity 10h, and the wings of the blade-shaped jig are rotated to rotate the cavity 10h. While stirring the magnetic powder 11 inside, the wings are raised to fill the cavity 10 h with the magnetic powder 11.
By rotating the wings of the wing jig and stirring the magnetic powder 11 in the cavity 10h, the wings are raised and the magnetic powder 11 is filled into the cavity 10h, so that the cavities in the magnetic powder in the cavity 10h or The bridge of the magnetic powder is broken and the magnetic powder 11 is uniformly filled in the cavity 10h.

FIG. 11 is a cross-sectional view illustrating the configuration and operation of the punch set unit 4. As shown in the figure, the punch set unit 4 includes a hand 4a that catches the upper punch 10g and a moving mechanism that moves the upper punch 10g that is caught by moving the hand 4a up and down.
The conveyance mold 10 can be set by the punch set unit 4 so that the magnetic powder 11 in the cavity 10h can be pressurized by the upper punch 10g.
When the magnetic powder 11 is filled in the cavity 10h, the pallet 10a is transported to the stage of the punch set unit 4 and positioned at a specified position as shown in FIG. Next, as shown in FIG. 11B, the hand 4a descends and catches the upper punch 10g. Then, as shown in FIG. 11 (c), the hand 4a lifts the upper punch 10g, moves to the lower mold as shown in FIG. 11 (d), descends and inserts the upper punch 10g into the core 10d. Then, the upper punch 10g is released, and the upper punch 10g fits into the cavity 10h. The diameter of the upper end of the core 10d is 0.02 mm smaller than the diameter in the cavity 10h, and a taper of 3 ° is given. Therefore, there is a deviation of less than 0.1 mm between the pallet and the hand 4a when the punch is inserted. However, such a defect that the punch 10g cannot be inserted into the core 10d does not occur. Next, after releasing the upper punch 10g, the hand 4a rises and moves to the original position.
The conveyance mold 10 on which the upper punch 10 g is set is conveyed to a predetermined position of the next magnetic field forming unit 5 by the belt conveyor 2.

FIG. 12 is a cross-sectional view illustrating the configuration and operation of the magnetic field forming unit 5. As shown in FIG. 12, the magnetic field forming unit 5 includes an electromagnetic coil 5a (fixed to the frame) that generates an orientation magnetic field for orienting the magnetic powder, an upper electromagnetic coil 5a, and an upper punch 10g. A compression molding mechanism 5b for raising and lowering the indenter 5c, a ring-shaped elastic member 5j, and a back yoke 5d that is driven by an air cylinder (not shown) and contacts the die 10f. The pressurizer 5c includes a movable rod 5f and a spring 5g that presses the movable rod 5f against the core 10d.
As shown in FIG. 12 (a), when the transport mold 10 is set in the magnetic field forming unit 5, as shown in FIG. 12 (b), the compression molding mechanism 5b is operated, and the upper electromagnetic coil 5a and the pressurizer are operated. 5c is lowered, the upper and lower frames are fixed by the chucking function, and the die 10f is fixed by the ring-shaped elastic member 5j attached to the lower part of the upper frame. Thereafter, the back yoke 5d moves from both sides of the die 10f, and comes into close contact with the outer periphery of the die 10f. Next, a current flows through the electromagnetic coil 5a to generate a radial orientation magnetic field, and the pressurizer 5c is lowered to pressurize the upper punch 10g. As shown in FIG. 12C, the upper punch 10g is moved into the cavity. By compressing and molding the magnetic powder, a radially oriented shaped body is obtained. The compression molding pressure is 10 to 100 MPa, preferably 40 MPa, and the orientation magnetic field is 1 T or more.
FIG. 17 is a cross-sectional view showing a state of magnetic flux in the radial orientation. The magnetic field generated by the upper electromagnetic coil 5a becomes a magnetic flux, passes through the pressurizer 5c that is a ferromagnetic material, enters the movable rod 5f that is also a ferromagnetic material, and the magnetic field generated by the lower electromagnetic coil 5a is And enters the core 10d through a holder made of a ferromagnetic material. The lower punch 10e and the upper punch 10g are nonmagnetic materials.
As shown in FIG. 17, the magnetic flux indicated by the broken-line arrow passes through the movable rod 5f, which is a ferromagnetic material, and the core 10d, passes through the cavity 10h of the die 10f, which is a ferromagnetic material, in the radial direction, and is radial into the cavity 10h. An orientation magnetic field is formed.

FIG. 13 is a cross-sectional view showing the configuration of the demolding unit 6. As shown in the figure, the demolding unit 6 includes a molded body pressurizing mechanism including an air cylinder 6a for pressing the molded body 13 and an upper punch abutting portion 6d, a table 6c for pushing the die 10f upward, A die push-up mechanism including an air cylinder 6b and the like.
As shown in FIG. 13 (a), the pallet 10a on which the mold part including the radially oriented molded body 13 is placed is conveyed to the demolding unit 6 by the belt conveyor 2 and stops at a specified position. Then, the air cylinder 6a lifts the pallet 10a, and the formed body 13 is pressurized by the formed body pressurizing mechanism in which the upper punch 10g hits the upper punch abutting portion 6d. The applied pressure is 0.1 to 1 MPa.
Next, as shown in FIG. 13B, the air cylinder 6b operates, the table 6c lifts the die 10f, and the molded body 13 is extracted from the die 10f.
Next, as shown in FIG. 13C, the air cylinder 6 a is lowered and the pallet 10 a is placed on the belt conveyor 2. The belt conveyor 2 moves the pallet 10a to a position where it is placed on another holder 10j placed on the pallet 10a when the die 10f supported by the table 6c is lowered, as shown in FIG. 13 (d). Thus, the table pressurizing cylinder 6b is operated, the table 6c is lowered, and the die 10f is placed on the holder 10j.
In the process of extracting the molded body 13 from the conveying mold 10, if there is an internal stress difference between the upper portion of the molded body 13 extracted from the conveying mold 10 and the lower portion of the molded body 13 in the conveying mold 10, cracks will occur. However, in this demolding unit 6, since the molded body 13 is extracted from the die 10f in a state where the molded body 13 is pressurized, the internal stress difference between the upper part and the lower part of the molded body 13 is reduced. The generation of cracks is prevented.

14 and 15 are cross-sectional views illustrating the configuration and operation of the compact de-dusting unit 7. As shown in the figure, the compact de-dusting unit 7 includes a table 7a and an elevating mechanism including an air cylinder 7b for elevating and lowering the table 7a, a nozzle 7c for injecting nitrogen gas, and sucking magnetic powder and collecting it in a dust collector. A dust suction duct 7d.
As shown in FIG. 14A, the molded body 13 from which the die 10 f has been extracted is transferred to the molded body de-dusting unit 7 by the belt conveyor 2 and stopped at a predetermined position. Then, the air cylinder 7b is actuated to raise the table 7a. As shown in FIG. 14B, the lower core 10e is supported by the table 7a and rises, and the molded body 13 is extracted from the core 10d. At this time, since the molded body 13 is extracted while the magnetic powder adhering to the outer periphery of the core 10 d is scraped off, the magnetic powder adheres to the inner peripheral end surface portion of the molded body 13. At this time, the upper punch 10g is also simultaneously extracted and placed on another holder 10j.
As shown in FIGS. 15A to 15C, in the process of extracting the molded body 13 from the core 10d, when the upper surface of the molded body 13 slightly protrudes from the core 10d, nitrogen gas is ejected from the nozzle 7c to form the molded body. The magnetic powder adhering to the surface 13 is blown off and sucked by the suction duct 7d. Thereafter, the molded body 13 is extracted from the core 10d as shown in FIG.
By removing the excess magnetic powder adhering to the molded body 13 by the molded body de-dusting unit 7 as described above, it is possible to prevent the molded body 13 from being inclined or displaced in the stacking of the next process. it can.

FIG. 16 is a cross-sectional view for explaining the configuration and operation of the stacking unit 8. As shown in the figure, the stacking unit 8 includes a hand 8a as a mechanism for chucking the molded bodies 13, a table 8b for stacking the molded bodies 13, and a hand 8a, which is not shown, and is moved up and down. And a mechanism for moving the table 8b and a mechanism such as a motor for rotating the table 8b.
As shown in FIG. 16A, the hand 8a is moved immediately above the molded body 13 extracted from the core 10d. Next, as shown in FIG. 16B, the hand 8a is lowered to chuck the molded body 13 with the hand 8a. The chucking force is 0.1 to 4N. Next, the hand 8a is raised, and as shown in FIG. 16C, the hand 8a is moved so that the center thereof is directly above the rotation center of the table 8b. Next, as shown in FIG. 16D, the hand 8a is lowered to place the molded body 13 on the table 8b. At this time, the center of the molded body 13 coincides with the rotation center of the table 8b.
Further, similarly, as shown in FIGS. 16E and 16F, the second-stage and third-stage molded bodies 13 are laminated on the first-stage molded body 13, and this lamination step is performed. Repeatedly, the molded body 13 is laminated by the required number of steps.
When variations occur in the heights of the molded bodies 13, unnecessary pressure is applied to the molded bodies 13 during stacking (when the height is high), and the molded bodies 13 are crushed or the hands 8a are in the air. In this embodiment, the weight of the molded body 13 formed at one time is the measuring step of the magnetic powder of the powder feeding / filling unit 3 shown in FIG. Therefore, the height of the molded body 13 is constant, and no unnecessary force or impact force is applied to the molded bodies during stacking.

When the stacking process is completed, the mold part is returned to the pallet 10a by the transfer mechanism, and conveyed to the mold de-dusting / mold set unit 9 for performing the next process.
The mold powder removal / mold set unit 9 is configured to remove the magnetic powder adhering to the conveyance mold 10 and to supply the magnetic powder in the powder supply / filling unit 3 to the initial state of the conveyance mold 10. And a setting mechanism for setting each part.
The dust removal mechanism sucks the magnetic powder blown by the nitrogen gas (having a mechanism for moving the nitrogen gas to each part of the transport mold) that can inject nitrogen gas to each part of the transport mold 10 and collects the dust. A suction mechanism.
By the powder removal mechanism and the set mechanism, the steps up to the molding and stacking of the next cycle can be performed smoothly.
The setting mechanism is a mechanism that lifts the die 10f placed on the holder 10j shown in FIG. 9 and moves it onto the lower punch 10e placed on the holder 10b after the stacking process is completed. Since the die 10f is tapered on the inner diameter portion of the lower end face thereof, it can be easily inserted into the lower punch 10e. The height of the taper portion is smaller than the height of the convex portion in the radial direction of the lower punch 10e.
The laminated molded body in which the molded bodies 13 are stacked is transferred to a sintering / heat treatment furnace, subjected to sintering / heat treatment at a predetermined temperature, and then subjected to finishing and surface treatment as necessary. A ring-shaped sintered magnet 100 is obtained.

  The ring-type sintered magnet according to the present embodiment is manufactured through the process as described above, and the ring-type magnet molded body is simply stacked and put into a sintering furnace and integrated with the sintering. The probability of sintering and integration over the entire boundary surface of the molded body is low, and the bonding area at the boundary surface is inevitably reduced, so that the bonding strength is reduced.

  FIG. 24 is a diagram showing the relationship between the bonding area at the boundary surface of the ring-shaped magnet molded body and the degree of orientation in the radial direction. Here, the degree of orientation is an index indicating how much the crystals in the magnet are oriented in the orientation direction, and is represented by the degree of orientation = Br (residual magnetic flux density) / Bs (saturated magnetic flux density). As shown in FIG. 24, by setting the degree of orientation in the radial direction to 80% or more, preferably 90% or more, the entire boundary surface is not uniformly bonded during sintering. In this case, as shown in the detailed view of the ring-type sintered magnet in FIG. 25, the boundary surface of the inner diameter portion of the ring is not joined, and the mechanical strength of the sintered magnet molded body lamination boundary is lowered. In order to obtain such an orientation degree, the strength of the orientation magnetic field at the time of magnetic field shaping is set to 1.0 T or more. Preferably it is 1.2T or more, and the higher one is preferable.

  In the conventional ring-type magnet, the strength of the lamination boundary is equal to the strength of the sintered magnet, but the strength of the lamination boundary of the ring-type sintered magnet of this embodiment is the strength of the other part of the magnet (sintered magnet). Is less than 2/3 of the original strength).

  As described above, after processing and surface treatment of the ring-type sintered magnet 100 of the present embodiment, as shown in FIG. 6, when the rotor shaft 105 is fixed to the rotor shaft 105 with an adhesive and mounted on a motor, and subjected to a heat cycle However, since the stress is relieved when the boundary portion breaks first, the entire magnet is broken, or the magnet is cracked and part of it is missing and caught in the air gap with the stator core. It is possible to prevent a failure such that the motor cannot rotate.

  5 is a cross-sectional view of a conventional ring-type sintered magnet 500, and FIG. 7 is a cross-sectional view of a rotor using the conventional ring-type sintered magnet. The ring-type sintered magnet 500 and the rotor shaft 505 have a difference in linear expansion coefficient. When subjected to a heat cycle, the long-axis ring-type sintered magnet may be cracked or cracked, and the magnetic characteristics are deteriorated.

  Thus, by using the ring-type sintered magnet of the first embodiment, it is possible to obtain a rotor that is strong against heat shock and excellent in magnetic properties.

  In addition, since the ring-type sintered magnet in the present embodiment is manufactured through the process as described above, the boundary portion is compared with the conventional ring-type sintered magnet integrally formed in the mold. Magnetic properties do not deteriorate. Moreover, since each process of a shaping | molding process is processed efficiently by a dedicated apparatus separately, productivity is good.

Embodiment 2. FIG.
FIG. 2 is a cross-sectional view showing a ring-type sintered magnet according to Embodiment 2 of the present invention. The manufacturing method of the ring-type sintered magnet of the present embodiment is the same as that of the first embodiment, but when forming the lowermost and second-stage molded bodies among the laminated molded bodies (three stages), FIG. An upper punch 1800 having a cross-sectional shape with a protruding inner diameter side is used. The ring-shaped sintered magnet 200 of FIG. 2 is obtained by laminating the molded body molded using the upper punch 1800 and sintering and integrating them.

  Since the ring-type sintered magnet 200 of the second embodiment has a gap 201 of 0.005 mm to 0.5 mm (axial distance) on the inner diameter side of the boundary surface of the molded body, the area in contact with the lamination boundary is small. Thus, the bonding strength at the boundary surface is reduced.

  In addition, since the contact area of the boundary when the molded body is laminated is small, the surface pressure is larger than when the entire surface of the cross section of the ring is in contact, and the degree of bonding of the contacted part during sintering is high. Therefore, it is possible to join the boundary portions that are in reliable contact.

  When the gap 201 on the inner diameter side is 0.005 mm or less in the axial direction, it is difficult to produce a mold, and it is difficult to obtain the effect of opening the gap. If the gap 201 is 0.1 mm or more, the magnetic characteristics may be deteriorated. The boundary gap 201 is suitably 0.01 mm to 0.1 mm. In addition, it is preferable for maintaining the magnetic characteristics that the radial length R1 of the gap 201 is set to be equal to or less than half of the radial length R2 when there is no gap.

  Further, in the case of a radially oriented ring magnet, the sintering shrinkage on the inner diameter side tends to be larger than the sintering shrinkage on the outer diameter side during sintering, but is formed by the upper punch 1800 with the inner diameter side protruding as shown in FIG. Then, the molded body density on the inner diameter side becomes larger than that on the outer diameter side. As a result, the sintering shrinkage on the inner diameter side becomes smaller than that of normal molding, and the sintering shrinkage in the molded body can be made uniform. Thereby, not only the shape accuracy of the sintered body is improved, but also the boundary can be reliably joined because the deformation is small. That is, it is possible to suppress defects such as separation of boundaries and a decrease in bonding area due to deformation caused by sintering shrinkage.

  Moreover, since the outer peripheral side which opposes a stator core is reliably joined, when it evaluates as a motor, the magnetic characteristic of a ring type sintered magnet does not fall. Even compared with the ring-type sintered magnet of the first embodiment, there is almost no decrease in induced voltage.

  As described above, the ring-type sintered magnet of the second embodiment is provided with a gap on the inner diameter side of the boundary surface of the ring-type magnet molded body, so that a rotor that is more resistant to heat shock and excellent in magnetic properties is obtained. be able to.

Embodiment 3 FIG.
FIG. 3 is a cross-sectional view showing a ring-type sintered magnet according to Embodiment 3 of the present invention. The manufacturing method of the ring-type sintered magnet 300 of the present embodiment is the same as that of the first embodiment, but when forming the lowermost and second-stage molded bodies among the laminated molded bodies (three stages), FIG. An upper punch 1900 having a cross-sectional shape having a tapered shape with a protruding inner diameter side as shown in FIG. 19 is used. The ring-shaped sintered magnet 300 shown in FIG. 3 is obtained by laminating the molded bodies formed using the upper punch 1900 and integrating them by sintering.

  The ring-type sintered magnet 300 of the present embodiment has the same effect as that of the second embodiment, but the inner diameter side of the upper punch 1900 has a tapered cross section. A gap 301 is formed, and a substantially linear density distribution is formed. That is, since the density of the molded body increases toward the inner diameter side, the sintering shrinkage during sintering can be made uniform, and a more accurate sintered body can be obtained and the joining at the boundary can be ensured. it can.

  As described above, in the ring-type sintered magnet of the third embodiment, a gap is provided on the inner diameter side of the boundary surface of the ring-shaped magnet molded body, and the gap is increased toward the inner diameter side (particularly, tapered). Therefore, a rotor that is more resistant to heat shock and excellent in magnetic properties can be obtained.

Embodiment 4 FIG.
4 is a sectional view showing a ring-type sintered magnet according to Embodiment 4 of the present invention. The manufacturing method of the ring-type sintered magnet 400 of the present embodiment is the same as that of the first embodiment, but the upper punch 2000 having a sectional shape in which the inner diameter side protrudes and the side surface of the protrusion has a tapered shape shown in FIG. A lower punch 2100 having a cross-sectional shape in which the side is recessed and the side surface of the recess is tapered is used. Both taper shapes are dimensioned so as to be fitted when the molded bodies are laminated.

  The upper punch 2000 is used when forming the lowermost and second-stage molded bodies of the laminated molded body (three steps), and the lower punch 2100 is used when forming the second and third steps. The ring-shaped sintered magnet 400 of FIG. 4 is obtained by laminating the molded bodies molded in this manner and integrating them by sintering.

  The ring-type sintered magnet of the fourth embodiment can obtain the same effects as those of the second embodiment. In addition, since the gap between the boundaries, particularly the taper shape, is fitted, when the molded body is transferred to the molded body storage or sintering furnace after stacking, each molded body is transferred when the molded body is transferred in the sintering furnace. Therefore, it is possible to prevent deterioration of the shape accuracy of the sintered ring magnet after sintering.

  The present invention relates to a permanent magnet used for a rotary electric motor such as a motor, for example.

It is sectional drawing which shows the ring-type sintered magnet by Embodiment 1 of this invention. It is sectional drawing which shows the ring type sintered magnet by Embodiment 2 of this invention. It is sectional drawing which shows the ring type sintered magnet by Embodiment 3 of this invention. It is sectional drawing which shows the ring type sintered magnet by Embodiment 4 of this invention. It is sectional drawing which shows the conventional ring-type sintered magnet. It is sectional drawing of the rotor using the ring sintered magnet of this invention. It is sectional drawing of the rotor using the conventional ring type sintered magnet. It is a top view which shows the structure of the permanent magnet shaping | molding apparatus of this invention. It is the top view (a) and sectional drawing (b) which show the structure of the conveyance metal mold | die in FIG. It is sectional drawing explaining a powder supply and filling unit and its operation | movement. It is sectional drawing explaining the structure and operation | movement of a punch set unit. It is sectional drawing explaining the structure and operation | movement of a magnetic field shaping | molding unit. It is sectional drawing for demonstrating the operation | movement in a mold removal unit. It is sectional drawing explaining the structure and operation | movement of a molded object powdering unit. It is sectional drawing explaining the structure and operation | movement of a molded object powdering unit. It is sectional drawing for demonstrating the structure and operation | movement of a stacking unit. It is sectional drawing which shows the state of the magnetic flux in radial orientation. 6 is a cross-sectional view of an upper punch used in Embodiment 2. FIG. 6 is a cross-sectional view of an upper punch used in Embodiment 3. FIG. 6 is a cross-sectional view of an upper punch used in Embodiment 4. FIG. 6 is a cross-sectional view of a lower punch used in Embodiment 4. FIG. 1 is a perspective view of a ring-type sintered magnet having irregularities on the peripheral surface of the present invention. 1 is a perspective view of a ring-type sintered magnet having irregularities on the peripheral surface of the present invention. It is a figure which shows the relationship between the joining area in the interface of a ring type magnet molded object, and the orientation degree of a radial direction. It is a detailed sectional view showing a ring type sintered magnet according to Embodiment 1 of the present invention.

Explanation of symbols

100, 200, 300, 400 Ring-type sintered magnet,
201, 301, 401 gap.

Claims (5)

While pressing the magnetic powder into the ring mold and applying a magnetic field in the radial direction of the ring mold to form a radially oriented ring mold magnet molded body, laminating a plurality of the ring mold magnet molded bodies, In the method for producing a ring-type sintered magnet obtained by sintering integration,
When the ring-shaped magnet molded body is formed, the degree of orientation in the radial direction is set to 80% or more, so that the ring-shaped magnet can be integrated into the sintering furnace after being stacked and integrated by sintering. A gap is formed on the inner diameter side of the boundary surface of the molded body, and the strength after sintering of the boundary portion where the ring-shaped magnet molded body is laminated is made weaker than the magnet strength of a portion other than the boundary portion. To manufacture a ring-type sintered magnet. While pressing the magnetic powder into the ring mold and applying a magnetic field in the radial direction of the ring mold to form a radially oriented ring mold magnet molded body, laminating a plurality of the ring mold magnet molded bodies, In the method for producing a ring-type sintered magnet obtained by sintering integration,
When pressurizing the magnetic powder to the ring mold, by using a punch with a cross-sectional shape projecting from the inner diameter side , pressurizing so that the molded body density on the inner diameter side of the ring-shaped magnet molded body is larger than the outer diameter side, said a clearance ring-shaped powder compact on the inner diameter side of the boundary surface when the plurality of stacked, plurality of the magnet molding is sintered integrally put into a sintering furnace just stacked Rukoto A method for manufacturing a ring-type sintered magnet. The method for producing a ring-type sintered magnet according to claim 2, wherein the gap is larger toward the inner diameter side. The method for manufacturing a ring-type sintered magnet according to claim 3, wherein the gap has a tapered shape. The method for producing a ring-type sintered magnet according to any one of claims 2 to 4, wherein a part of a boundary surface of the ring-shaped magnet molded body is fitted.

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