Bonded magnet manufacturing device, bonded magnet manufacturing method, and bonded magnet

Abstract

To provide a device capable of manufacturing a bond magnet with a desired form at low cost.SOLUTION: Each of bond magnet manufacturing devices (10 and 20), comprises: bases (11 and 21); base powder accumulation parts (121 and 221) that accumulates base powder (P) into which magnetic powder and powder of a binder of which a fusion point is lower than that of the magnetic powder are mixed without scattering the powder of the binder into a solvent; base powder supply parts (12 and 22) that supply an organic powder (P) into a predetermined powder supply region on the bases (11 and 21) from the organic powder accumulation parts (121 and 221); and beam irradiation parts (13 and 23) that irradiate a beam for heating the organic powder (P) to a temperature for melting or hardening the powder of the binder without melting the magnetic powder to an irradiation region that is a region corresponded to the form of a bond magnet of the organic powder supply parts (12 and 22) to be manufactured. According to the bond magnet manufacturing devices (10 and 20), since a bond magnet with a desired form without using a molding, a manufacturing cost can be suppressed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for manufacturing a bonded magnet, and to a bonded magnet obtained by the apparatus and method. [Background technology]

[0002] Bonded magnets are made by crushing magnetic material that has magnetic properties into a powder, mixing the powder with a binder, and solidifying it. Bonded magnets have features such as not needing to be heated to high temperatures (around 1000°C for sintered magnets) during production, and being less prone to cracking or chipping.

[0003] Conventionally, methods such as compression molding and injection molding have been used to manufacture bonded magnets (see, for example, Patent Document 1). In compression molding, a mixture of magnet powder and binder is filled into the cavity of a mold, and then compressed and heated to harden. In injection molding, the mixture of magnet powder and binder is heated to melt the binder, and then injected into the cavity of the mold. In most cases, compression molding uses a thermosetting resin such as phenol resin or epoxy resin as the binder, while injection molding uses a thermoplastic resin such as nylon. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-057017 A [Patent Document 2] JP 2018-167565 A [Non-patent literature]

[0005] [Non-Patent Document 1] "Basic knowledge of metal 3D printers that you should know ~ A simple introduction from the modeling principle and raw materials to the advantages and disadvantages ~ Everyone's Prototype Plaza", [online], 2018, Hitachi High-Technologies Corporation, [Retrieved May 14, 2019], Internet<URL:https: / / minsaku.com / category01 / post40 / > Summary of the Invention [Problem to be solved by the invention]

[0006] These compression molding and injection molding methods use a mold with a cavity shaped to correspond to the shape of the bonded magnet to be manufactured, making it possible to obtain a bonded magnet of the desired shape without mechanical processing after compression molding or injection molding. However, users require a wide variety of bonded magnet shapes, and in order to meet these requirements, a mold must be prepared for each shape. This has led to the problem that small-lot production of bonded magnets is expensive.

[0007] The problem to be solved by the present invention is to provide an apparatus and method capable of manufacturing a bonded magnet of a desired shape at low cost, and also to provide a bonded magnet obtained by said apparatus and said method. [Means for solving the problem]

[0008] The bond magnet manufacturing apparatus according to the present invention, which has been developed to solve the above problems, is as follows: a) a base; b) a raw powder supply unit that supplies raw powder, which is a mixture of magnet powder and binder powder having a melting point lower than that of the magnet powder, to a predetermined powder supply area on the base; c) a beam irradiation unit that irradiates an irradiation area, which is an area of ​​the powder supply area that corresponds to the shape of the bonded magnet to be manufactured, with a beam that heats the raw material powder to a temperature that melts or hardens the binder powder without melting the magnet powder; The present invention is characterized by comprising:

[0009] In the bond magnet manufacturing apparatus according to the present invention, first, the raw material powder is supplied to a predetermined powder supply area on the base by the raw material powder supply unit. Next, a beam for heating the raw material powder is irradiated to an irradiation area, which is an area of ​​the powder supply area that corresponds to the shape of the bond magnet to be manufactured. The beam irradiated here can be a laser beam, an electron beam, or the like. The temperature for heating the raw material powder is a temperature that does not melt the magnet powder (i.e., below the melting point) and, if the binder is made of a material that melts when heated such as a thermoplastic resin, the temperature is a temperature that melts the binder powder (i.e., above the melting point), and if the binder is made of a material that hardens when heated such as a thermosetting resin, the temperature is a temperature that hardens the binder powder. If the binder is made of a material that melts when heated, heat is taken away by the surroundings after irradiation with the beam, and the binder is cooled below the melting point, and if the binder is made of a material that hardens when heated, the raw material powder in the irradiation area of ​​the powder supply area is hardened by irradiation with the beam, and a part of the bond magnet is formed. The diameter of the beam irradiated to the irradiation area is equal to or less than the minimum across dimension of the irradiation area.

[0010] After that, raw material powder is supplied from the raw material powder supply unit onto a part of the formed bonded magnet (the formed portion) and the surrounding area containing raw material powder that has not been irradiated with the beam. Then, the area corresponding to the shape of the bonded magnet to be formed above the formed portion is set as the irradiation area, and the beam is irradiated from the beam irradiation unit. In this way, by repeating the supply of raw material powder by the raw material powder supply unit and the irradiation of the beam by the beam irradiation unit, the formed portion is enlarged, and finally, a bonded magnet having the desired three-dimensional shape can be manufactured. Note that if the bonded magnet to be manufactured is thin (its height above the base is low and its dimensions in the beam irradiation direction are small), the supply of raw material powder and the irradiation of the beam by the beam irradiation unit may be performed only once.

[0011] The bonded magnet manufacturing apparatus of the present invention does not use dies, which eliminates the costs incurred by preparing dies for each bonded magnet shape in conventional bonded magnet manufacturing apparatus, making it possible to manufacture bonded magnets of desired shapes at low cost even in small lot production.

[0012] Examples of the magnet powder that can be used include powder of RFeB-based magnets (particularly NdFeB-based magnets having neodymium (Nd) as the main R element) whose main constituent elements are rare earth elements (referred to as "R"), iron (Fe), and boron (B); powder of SmFeN-based magnets whose main constituent elements are samarium (Sm), iron, and nitrogen (N); and powder of SmCo-based magnets whose main constituent elements are samarium and cobalt (Co).

[0013] For example, powders of the following resins can be used as the binder. Thermoplastic resins include polyester elastomer (TPC), polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethersulfone (PES), polyamide-imide (PAI), polyvinylidene fluoride (PVDF), polylactic acid (PLA), ethyl cellulose (EC), nylon 6, and nylon 12. Thermosetting resins include epoxy resin and phenol resin.

[0014] Conventionally, a metal object has been produced by supplying metal powder to a predetermined powder supply area on a base, irradiating an irradiation area of ​​the powder supply area with a laser beam, an electron beam, or the like to melt the metal powder in the irradiation area, and then cooling it (see, for example, Patent Document 2 and Non-Patent Document 1). However, most magnetic materials, including the above-mentioned RFeB magnets, SmFeN magnets, and SmFeN magnets, decompose when melted. If decomposed in this way, they do not return to their original magnetic material even if they are subsequently cooled, and the desired magnetic properties as a magnet cannot be obtained. Therefore, in the present invention, a mixed powder of magnet powder and binder powder is used as a raw material powder, and the raw material powder is heated to a temperature that melts or hardens the binder powder without melting the magnet powder, thereby making it possible to produce a bonded magnet without decomposing or denaturing the magnet powder (magnetic material).

[0015] In the bonded magnet manufacturing apparatus according to the present invention, the powder supply area may be wider than the irradiation area, or may be the same as the irradiation area. An example of a powder supply area wider than the irradiation area is powder bed fusion (powder additive fusion bonding method). In powder bed fusion, the raw powder supply unit forms a layer of raw powder on a base, and the beam irradiation unit irradiates a beam onto a part of the layer as an irradiation area. On the other hand, an example of a powder supply area that is the same as the irradiation area is laser metal deposition (directed energy deposition method). In laser metal deposition, the raw powder supply unit ejects raw powder from a nozzle toward a powder supply area having a shape corresponding to the bonded magnet to be manufactured. At the same time, the beam irradiation unit irradiates a beam onto the raw powder supplied from the nozzle to the powder supply area (= irradiation area). This melts or hardens the binder powder without melting the magnet powder, and deposits the material of the bonded magnet in the powder supply area.

[0016] The bonded magnet manufacturing apparatus according to the present invention may further include a pressure application unit that applies pressure to the raw material powder supplied to the powder supply area. By applying pressure to the raw material powder using the pressure application unit before irradiating the raw material powder with a beam, the spaces between the raw material powder particles can be reduced, thereby increasing the density of the bonded magnet produced. It is also possible to apply pressure after irradiating the beam.

[0017] When the raw material powder is heated, the magnet powder does not melt, but some of the elements contained in the magnet powder may be released, and the magnet powder may be altered. In this case, the resulting bonded magnet has magnetic properties as a magnet, but the numerical values ​​that represent the magnetic properties (residual magnetic flux density, coercive force, maximum energy product, etc.) may decrease. For this reason, it is desirable for the beam irradiation unit to heat the raw material powder to a temperature lower than the temperature at which the magnet powder is altered.

[0018] The method for producing a bonded magnet according to the present invention comprises the steps of: a raw material powder supplying step of supplying a raw material powder obtained by mixing magnet powder and binder powder having a melting point lower than that of the magnet powder to a predetermined powder supplying area on a base; a beam irradiation step of irradiating an irradiation area, which is an area of ​​the powder supply area that corresponds to the shape of the bonded magnet to be manufactured, with a beam that heats the raw material powder to a temperature that melts or hardens the binder powder without melting the magnet powder; The present invention is characterized by having the following.

[0019] In the bonded magnet manufacturing method according to the present invention, the raw material powder supplying step and the beam irradiation step may each be performed once, or the raw material powder supplying step and the beam irradiation step may be performed alternately multiple times.

[0020] In the bonded magnet manufacturing method according to the present invention, a pressure applying step of applying pressure to the raw material powder supplied to the powder supply region may be carried out between the raw material powder supplying step and the beam irradiation step.

[0021] In the bonded magnet manufacturing method according to the present invention, the raw material powder supplying step forms a layer of raw material powder on the base, and the beam irradiating step can be a step of irradiating the irradiation area of ​​a part of the layer with the beam (powder bed fusion). In this case, it is preferable that the thickness of the raw material powder layer is equal to or greater than the maximum diameter of the magnetic powder particles. This can prevent the magnetic powder particles from getting caught on tools and peeling off when forming the raw material powder layer, and can form a uniform layer.

[0022] In the bonded magnet manufacturing method of the present invention, the raw material powder supplying process can involve using a nozzle to supply raw material powder to the powder supply area having a shape corresponding to the bonded magnet to be manufactured, and the beam irradiation process can involve irradiating a beam onto the irradiation area which is the same area as the powder supply area (laser metal deposition).

[0023] In the bonded magnet manufacturing method according to the present invention, the particles of the binder powder are preferably spherical, which can improve the flowability of the raw powder containing irregularly shaped (non-spherical) magnetic powder particles in the raw powder supplying step.

[0024] When the raw material powder supplying section of the bonded magnet manufacturing apparatus according to the present invention forms a layer of raw material powder, and when the raw material powder layer is formed in the raw material powder supplying step of the bonded magnet manufacturing method according to the present invention, a bonded magnet having the following characteristics can be obtained: This bonded magnet is characterized in that it has a plurality of stacked layers in which magnetic powder particles are bound together by a binder, and each of the layers has a density distribution in which the density of the binder increases in a common direction, and this direction is from one side of the stacking direction to the other.

[0025] Such a structure in which multiple layers are stacked is formed by repeatedly performing the raw powder supplying step and the beam irradiation step multiple times in the bonded magnet manufacturing method according to the present invention. In this case, in the beam irradiation step, the attenuation rate of the energy of the beam reaching the side where the beam is incident in the thickness direction of the raw powder layer (corresponding to the "other" side) is lower than that of the opposite side (corresponding to the "one" side), so the binder powder melts well. As a result, the density of the binder hardened after melting is higher on the side where the beam is incident than on the opposite side. Therefore, the obtained bonded magnet has a configuration in which the binder density of each layer increases from the one side to the other side in the stacking direction. As a result, the bonded magnet has stripes in which the parts with high binder density become walls with high mechanical strength, and the overall mechanical strength can be increased. Effect of the Invention

[0026] The bonded magnet manufacturing apparatus and method according to the present invention can manufacture bonded magnets of desired shapes at low cost because they do not require a mold. In addition, the bonded magnet manufacturing apparatus and method according to the present invention can be used to obtain bonded magnets with high mechanical strength. [Brief description of the drawings]

[0027] [Figure 1] 1 is a schematic diagram showing the configuration of a first embodiment of a bonded magnet manufacturing apparatus according to the present invention. [Figure 2A] FIG. 3 is a schematic diagram showing a part of a raw material powder supplying process in the operation of the bonded magnet manufacturing apparatus of the first embodiment. [Figure 2B] FIG. 4 is a schematic diagram showing another part of the raw material powder supplying step in the operation of the bonded magnet manufacturing apparatus of the first embodiment. [Figure 2C] FIG. 4 is a diagram showing a pressure application process in the operation of the bonded magnet manufacturing apparatus of the first embodiment. [Figure 2D] FIG. 4 is a diagram showing a beam irradiation process in the operation of the bonded magnet manufacturing apparatus of the first embodiment. [Figure 2E]FIG. 4 is a schematic diagram showing a part of a second raw material powder supplying step in the operation of the bonded magnet manufacturing apparatus of the first embodiment. [Figure 2F] FIG. 4 is a diagram showing a second beam irradiation step in the operation of the bonded magnet manufacturing apparatus of the first embodiment. [Figure 2G] FIG. 4 is a diagram showing a state after the operation of the bonded magnet manufacturing apparatus of the first embodiment has been completed. [Diagram 3] 1 is a flowchart showing one embodiment of a method for producing a bonded magnet according to the present invention. [Figure 4] FIG. 4 is a schematic diagram showing the configuration of a second embodiment of a bonded magnet manufacturing apparatus according to the present invention. [Diagram 5] Photographs of an example of a manufactured bonded magnet taken from the top and side. [Figure 6] 1 is a schematic cross-sectional view of a bonded magnet according to the present invention. [Figure 7] FIG. 4 is a schematic diagram for explaining the reason why a density distribution of the binder occurs in the bonded magnet according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] 1 to 7, an embodiment of a bonded magnet manufacturing apparatus, a bonded magnet manufacturing method, and a bonded magnet according to the present invention will be described.

[0029] (1) Configuration of the bonded magnet manufacturing apparatus of the first embodiment The configuration of a first embodiment of a bonded magnet manufacturing apparatus according to the present invention is shown in Figure 1. This bonded magnet manufacturing apparatus 10 has a base 11, a raw material powder supply unit 12, a beam irradiation unit 13, a pressure application unit 14, a surplus powder recovery unit 15, and a control unit (not shown).

[0030] Base 11 is a stand that holds on its upper surface raw material powder P (described in detail later) of the bonded magnet, which is supplied by raw material powder supply unit 12 as described below. Base 11 is raised and lowered by base lifting mechanism 111.

[0031] The raw powder supplying unit 12 includes a raw powder storage tank 121, a storage tank bottom lifting mechanism 122, and a roller 123. The raw powder storage tank 121 is a storage tank for raw powder P composed of a bottom 1211 and a side wall 1212, and only the bottom 1211 is lifted and lowered by the storage tank bottom lifting mechanism 122. The roller 123 moves laterally at the height of the upper end of the raw powder storage tank 121 from the end opposite the base 11 to the end on the base 11 side, and further moves while rotating from the end of the raw powder storage tank 121 on the base 11 to the end opposite the raw powder storage tank 121, thereby supplying the raw powder P in the raw powder storage tank 121 to the upper surface of the base 11.

[0032] The beam irradiation unit 13 has a laser light source 131, a reflecting mirror 132, and a scanning mechanism 133. The reflecting mirror 132 is movable between a use position, which is a position above the base 11, and a standby position that is off the top side of the base 11. When the reflecting mirror 132 is disposed at the use position, the reflecting mirror 132 reflects the laser beam emitted from the laser light source 131 and irradiates the upper surface of the base 11 (more specifically, the raw material powder P formed on the upper surface as described later). The scanning mechanism 133 is a device that changes the orientation of the reflecting mirror 132 (the angle with respect to the upper surface of the base 11), and by changing the orientation of the reflecting mirror 132, the position of the spot of the laser beam on the upper surface of the base 11 is moved. The orientation of the reflecting mirror 132 can be changed three-dimensionally, and the position of the spot of the laser beam moves not only in the left-right direction of FIG. 1 but also in the depth direction.

[0033] The pressure applying unit 14 has a lower surface shaped to correspond to the upper surface of the base 11, and is a member that applies pressure to the raw material powder P supplied to the upper surface of the base 11 from above.

[0034] The surplus powder recovery section 15 is provided on the opposite side of the base 11 from the raw material powder storage tank 121, and is a tank that recovers the raw material powder P that is supplied from the raw material powder storage tank 121 to the upper surface of the base 11 by the rollers 123 and that becomes surplus without forming a layer on the upper surface of the base 11.

[0035] The control unit controls the operations of the base lifting mechanism 111, the reservoir bottom lifting mechanism 122, the rollers 123, the laser light source 131, the scanning mechanism 133, and the pressure application unit .

[0036] (2) Operation of the bonded magnet manufacturing apparatus and the bonded magnet manufacturing method of the first embodiment 1 to 3, the operation of the bonded magnet manufacturing apparatus 10 of the first embodiment and the bonded magnet manufacturing method carried out by this operation will be described.

[0037] First, the bottom 1211 of the raw powder storage tank 121 is raised to an appropriate height by the storage tank bottom lifting mechanism 122, and the raw powder P is poured into the raw powder storage tank 121 until it is level (FIG. 1). The raw powder P is a powder obtained by mixing magnet powder and binder powder. The magnet powder may be RFeB magnet powder, SmFeN magnet powder, SmCo magnet powder, or the like. The binder powder may be a powder of thermosetting resin such as phenol resin or epoxy resin, or a powder of thermoplastic resin such as nylon or polyphenylene sulfide (PPS). Here, PPS has a high melting point of 285°C among thermoplastic resins, and is therefore a binder material that can be suitably used for bonded magnets used in automobile motors that require heat resistance up to about 200°C. The binder powder is preferably granulated so that the particles are spherical. This ensures the necessary fluidity of the raw powder P when forming the raw powder layer PL as described below. The mixing ratio of the magnet powder and binder powder may be the same as that of conventional bonded magnets, for example, a volume ratio of 9:1 (the former being magnet powder and the latter being binder powder) to 6:4.

[0038] Next, a layer PL of raw material powder having a predetermined thickness d (described in detail later) is formed on the upper surface of the base 11 by the following method. First, the base lifting mechanism 111 moves the base 11 so that the position of the upper surface of the base 11 is d below the upper end of the raw material powder storage tank 121. At the same time, the storage tank bottom lifting mechanism 122 lifts the bottom 1211 of the raw material powder storage tank 121 (FIG. 2A). Here, the position of the bottom 1211 is set so that the volume of the raw material powder P protruding from the upper end of the side wall 1212 of the raw material powder storage tank 121 is slightly larger than the volume obtained by multiplying the area of ​​the upper surface of the base 11 by the thickness d.

[0039] In this state, the roller 123 is moved as described above (FIG. 2B). As a result, the raw material powder P that has protruded above the upper end of the side wall 1212 is moved to the upper surface of the base 11, and a layer PL of raw material powder having a thickness d is formed over the entire upper surface of the base 11. Therefore, in this embodiment, the entire upper surface of the base 11 corresponds to the powder supply area. The remaining raw material powder P is thrown by the roller 123 into the surplus powder recovery section 15 and recovered. Through the operations up to this point, the raw material powder supplying step (step S1 in FIG. 3) is completed.

[0040] Next, with the reflecting mirror 132 disposed at the standby position, pressure is applied to the raw material powder layer PL by the pressure application unit 14 (FIG. 2C, step S2 in FIG. 3, pressure application step). This increases the density of the raw material powder P in the raw material powder layer PL. The pressure applied to the raw material powder layer PL may be determined as appropriate, but usually does not need to be as high as that applied by a hydraulic press, and may be a pressure that can be applied when compressing powder by hand.

[0041] Next, the reflecting mirror 132 is placed in the use position, and the laser beam LB is emitted from the laser light source 131. The laser beam LB is reflected by the reflecting mirror 132 and irradiated onto the raw material powder layer PL on the upper surface of the base 11. Then, the position of the spot of the laser beam LB on the raw material powder layer PL is moved by changing the orientation of the reflecting mirror 132 with the scanning mechanism 133 (FIG. 2D). By this operation, in the irradiation region of the raw material powder layer PL, which is the region irradiated with the laser beam LB (where the spot of the laser beam LB has passed), the powder of the binder in the raw material powder P is hardened (if the binder is a thermosetting resin or the like) or melted and then cooled and hardened (if the binder is a thermoplastic resin or the like), and a part of the bonded magnet (formed portion BMP) is formed (step S3 in FIG. 3, beam irradiation process).

[0042] Here, the intensity of the laser beam LB is set by performing a preliminary experiment so that the raw powder P can be heated to a temperature that melts or hardens the binder powder without melting the magnet powder. In this preliminary experiment, it is not necessary to directly measure the temperature of the raw powder P when the laser beam LB is irradiated. In other words, whether or not the binder powder has been melted or hardened by irradiating the laser beam LB of a certain intensity is determined by visually checking whether or not the raw powder P has hardened after irradiation with the laser beam LB, and whether or not the magnet powder has melted is determined by measuring the magnetic properties of the obtained bonded magnet and then checking whether or not it has the desired magnetic properties as a magnet. As a result, if the raw powder P has hardened after irradiation with the laser beam LB and the obtained bonded magnet has the desired magnetic properties as a magnet, it can be said that the laser beam LB of that intensity can heat the raw powder P to the desired temperature.

[0043] When the three-dimensional shape of the bonded magnet to be manufactured is not yet complete at the stage where step S3 is completed ("NO" in step S4), the process returns to step S1, and the operations from step S1 to S3 are performed again. Specifically, in step S1 from the second time onwards, the base 11 and the bottom 1211 of the raw material powder storage tank 121 are moved in the same manner as in step S1 of the first time, and a new layer of raw material powder (a layer marked with the symbol "PL2" in FIG. 2E) is formed on the formed portion BMP formed in the previous steps and the raw material powder P remaining around the formed portion BMP without being irradiated with the laser beam LB. Then, pressure is applied to the raw material powder layer PL2 (not shown), and the layer PL2 is irradiated with the laser beam LB while being scanned, thereby forming a part of the bonded magnet (the formed portion BMP2) in the layer PL2 (FIG. 2F). Here, the time for which the laser beam LB is irradiated at each position of the raw material powder layer PL2 (the speed at which the beam is moved) and the output of the laser beam LB are adjusted in a preliminary experiment so that the binder powder in the raw material powder P in the layer PL2 can be melted or hardened, but the binder powder in the raw material powder P in the layer of raw material powder below the layer PL2 does not melt or harden.

[0044] In this manner, the operations from steps S1 to S3 are repeated to form the three-dimensional shape of the bonded magnet.

[0045] Then, when the three-dimensional shape of the bonded magnet BM to be manufactured is completed at the stage where step S3 is finished ("YES" in step S4 of FIG. 2G), the series of operations of the bonded magnet manufacturing apparatus 10 ends. After that, the obtained bonded magnet BM is taken out from the top of the base 11, and the raw material powder P remaining around the bonded magnet without being irradiated with the laser beam is collected in the surplus powder collection section 15. At that time, if the bonded magnet BM and the base 11 are fused together, the bonded magnet BM is cut off from the base 11 using an electric band saw or the like. Note that by forming a layer of raw material powder that is not irradiated with the laser beam BL on the base 11 (for example, 2 to 3 layers), and then stacking layers of raw material powder that are to be irradiated with the laser beam BL on top of that, the bonded magnet BM can be easily taken out without being fused to the base 11.

[0046] Although Figures 2D to 2G show the production of one bonded magnet BM, multiple bonded magnets BM can also be produced simultaneously by irradiating multiple irradiation areas corresponding to multiple bonded magnets BM on one layer PL of raw material powder with a laser beam.

[0047] If the value of the thickness d is made small, it has the advantage that the three-dimensional shape of the bonded magnet BM can be precisely formed, but it has the disadvantage that the number of operations from the raw material powder supply process to the beam irradiation process increases, lengthening the time required for manufacture. The value of the thickness d can be determined appropriately taking these advantages and disadvantages into consideration.

[0048] (3) Bonded magnet manufacturing apparatus according to the second embodiment The configuration of a second embodiment of a bonded magnet manufacturing apparatus according to the present invention is shown in Figure 4. This bonded magnet manufacturing apparatus 20 has a base 21, a raw material powder supply unit 22, a beam irradiation unit 23, and a control unit (not shown).

[0049] The base 21 is similar to that of the first embodiment in that it is a base for holding the raw material powder P on its upper surface, but unlike the first embodiment, it may be fixed or movable as described below.

[0050] The raw powder supplying section 22 has a raw powder storage section 221, a raw powder delivery section 222, a nozzle 223, and a nozzle moving mechanism 224. Note that FIG. 4 shows an enlarged view of the nozzle 223, and the size ratio of each section in the drawing is different from the actual one. The raw powder storage section 221 stores the raw powder P. The raw powder delivery section 222 sends the raw powder P stored in the raw powder storage section 221 to the nozzle 223 by carrying it on an air flow. The nozzle 223 is disposed on the upper side of the base 21, and is moved three-dimensionally (up and down, front and back, left and right) on the upper surface side of the base 21 by the nozzle moving mechanism 224. At that time, the base 21 may be fixed, or may be moved three-dimensionally independent of the nozzle 223. Alternatively, the base 21 may be moved three-dimensionally with the nozzle 223 fixed. The nozzle 223 has a double structure having two coaxial spaces, and the raw material powder P delivered from the raw material powder delivery part 222 passes through the outer space and is sprayed from the tip of the nozzle 223 onto the upper surface of the base 21.

[0051] The beam irradiation unit 23 has a laser light source 231, a laser light guide 232, and a laser beam emission unit 233. The laser beam emission unit 233 corresponds to the inner part of the two coaxial spaces in the nozzle 223. The laser light guide 232 is an optical fiber that connects the laser light source 231 and the laser beam emission unit 233.

[0052] The control unit controls the operations of the raw material powder delivery unit 222 , the nozzle moving mechanism 224 and the laser light source 231 .

[0053] The operation of the bonded magnet manufacturing apparatus 20 of the second embodiment will be described. The configuration of the raw material powder P is the same as that used in the first embodiment. The raw material powder P is stored in advance in the raw material powder storage section 221. When the operation of the bonded magnet manufacturing apparatus 20 is started, the nozzle moving mechanism 224, under the control of the control section, moves the nozzle 223 two-dimensionally along the surface of the base 21 within a powder supply area corresponding to the shape of the bonded magnet to be manufactured on the surface of the base 21. At the same time, the raw material powder delivery section 222 delivers the raw material powder P from the raw material powder storage section 221 to the nozzle 223. As a result, the raw material powder P is scattered from the nozzle 223 into the powder supply area on the upper surface of the base 21. At the same time, the laser light source 231 emits a laser beam. The laser beam passes through the laser beam guide 232 and reaches the laser beam emission section 233. Then, the raw material powder P scattered on the surface of the base 21 is immediately irradiated with a laser beam from the laser beam emission section 233. As a result, the binder powder in the raw material powder P hardens (if the binder is a thermosetting resin or the like) or melts and then cools and hardens (if the binder is a thermoplastic resin or the like) on the surface of the base 21. In this embodiment, the laser beam is irradiated to all positions on the surface of the base 21 where the raw material powder P has been supplied, so the irradiated area and the powder supply area coincide with each other.

[0054] When nozzle 223 has moved over the entire powder supply area by the operations up to this point, a part of a bonded magnet having the same shape as the powder supply area is formed on the surface of base 21. Then, by repeating the same operations up to this point on the part of the already formed bonded magnet, a three-dimensional shape is formed, and a bonded magnet of the desired shape is manufactured.

[0055] (4) Experimental results Below, a bonded magnet was manufactured using the bonded magnet manufacturing apparatus of the first embodiment, and the results of measuring the magnetic properties of the resulting bonded magnet will be described.

[0056] (Experiment 1) In experiment 1, the raw powder P used contained SmFeN magnet powder as the magnet powder and PPS powder as the binder powder. The magnet powder was prepared by melting an alloy mixed to have a composition of Sm: 19.30 (mass%, the same below), Zr: 1.65, Co: 3.95, Al: 0.30, N: 3.29, Fe: balance, using a single roll quenching device, and then dropping the molten metal onto a roll to quench it. The ribbon-like flakes obtained were crushed in a pin mill and classified using a sieve with a mesh size of 150 μm. The particles of the obtained magnet powder were flat, and their particle size was 109.5 μm in median D50. The particles of the binder powder were spherical with a particle size of 50 μm. The mixing ratio of the magnet powder and the binder powder is 98:2 (the former is magnet powder, the latter is binder powder. The same applies below.) to 90:10 in mass ratio, and 90:10 to 61:39 in volume ratio. The thickness d of the raw powder layer PL is 150 μm, and the raw powder supplying process and the beam irradiation process are repeated 34 times to manufacture a bonded magnet BM with a thickness of 5 mm. Note that the pressure application process is not performed in Experiment 1. The irradiation area is a circle with a diameter of 10 mm at the same position in the plane in each raw powder layer PL, and the three-dimensional shape of the bonded magnet BM is a disk shape. A carbon dioxide laser is used as the laser light source 131. This laser light source 131 has the ability to emit a laser beam with a wavelength of 10.6 μm and a laser spot diameter of 220 μm at a maximum output intensity of 60 W, but in this embodiment, the output intensity is narrowed to a range of 5 to 40 W. The moving speed of the laser spot is 5 m / sec. The laser beam was irradiated 1 to 4 times to the irradiation area in one raw material powder layer PL. In this experiment, PPS, a thermoplastic resin, was used as the binder material, so when the same position in the raw material powder layer PL was irradiated with the laser beam multiple times, the binder melted and hardened each time.

[0057] Table 1 shows the results of attempts to manufacture bonded magnets BM under multiple conditions, with different mixing ratios of magnet powder and binder powder, as well as different laser beam output strengths and irradiation times. Here, in order to investigate whether the raw material powder had been altered by the laser output, a portion of the manufactured compact was scraped off and powdered, which was then packed into a special container and the magnetic properties (residual magnetic flux density B r , coercive force H cj and maximum energy product (BH) max ) was measured. [Table 1]

[0058] In all cases, bonded magnets that maintained their disk-like shape were obtained, and it can be said that the binder powder melted and then hardened under all of the laser irradiation conditions in this experiment. Figure 5 shows photographs of an example of a bonded magnet obtained, taken from the top and side.

[0059] However, as a result of measuring the magnetic properties using VSM, the residual magnetic flux density B r , coercive force H cj and maximum energy product (BH) max All of these were significantly lower than the other samples, and no magnetic properties as a magnet were obtained. In Samples 1 and 2, the output intensity of the laser beam was 30 to 40 W, which was higher than the other samples, and it is believed that the magnet powder was subjected to high heat during irradiation with the laser beam, causing it to change in quality. For this reason, Samples 1 and 2 were used as Comparative Examples. In contrast, Samples 3 to 11 obtained magnetic properties as a magnet, and were used as Examples.

[0060] Among the examples, the magnetic properties of Samples 5 to 9 in particular are as follows: the residual magnetic flux density B r (8.03kG), coercive force H cj (9.45kOe) and maximum energy product (BH) maxThe obtained values ​​are almost the same as (13.0), and it is considered that the magnet powder did not change during production. On the other hand, the magnetic properties of samples 3 and 4 are lower than that of the raw material powder, but since the magnetic properties improve in samples 1 to 6 as the laser output decreases, it is considered that the magnet powder is gradually heated less during production, and the change in the properties is prevented. Therefore, when producing a bonded magnet from this raw material powder P in the device used in experiment 1, it is desirable to set the laser intensity to 5 to 15 W.

[0061] Samples 6 to 9 differed from one another only in the number of times they were irradiated with the laser beam, and the other conditions were the same, but no significant differences were observed in the density or magnetic properties among the samples.

[0062] (Experiment 2) The results of Experiment 2 are shown, in which a bonded magnet (Sample 12) was manufactured by carrying out a pressure application process between the raw material powder supply process and the beam irradiation process. In this experiment, the pressure application process was carried out by manually pressing the members of pressure application unit 14 against the raw material powder layer PL. The experimental results of Sample 12 are shown in Table 2, along with those of Sample 10. Except for the pressure application process, the manufacturing conditions in this experiment were the same as those for Sample 10. In Experiment 2 and Experiment 3 described below, the magnetic properties were measured using a DC BH tracer on the compact as is. [Table 2]

[0063] The sample 12, which underwent the pressure application process, has a higher bonded magnet density and better magnetic properties, particularly the residual magnetic flux density B r and maximum energy product (BH) max has become more expensive.

[0064] (Experiment 3) Experiment 3 was carried out to manufacture a bonded magnet (sample 13) using NdFeB magnet powder instead of SmFeN magnet powder. The NdFeB magnet powder used had flat particles with a median particle size D50 of 59.7μm. Conditions other than the magnet powder were the same as for sample 12 (so a pressure application process was carried out). The experimental results for sample 13 are shown in Table 3 together with sample 12. Sample 13 had density and magnetic properties close to those of sample 12. [Table 3]

[0065] (Experiment 4) Next, an experiment was conducted to visually confirm the state of layer PL when the layer PL was produced under different conditions of maximum particle size of magnet powder and thickness d of layer PL of raw material powder. In this experiment, SmFeN magnet powder was used as the magnet powder, and magnet powders with different maximum particle sizes were prepared by using sieves with different mesh sizes. The binder powder was made of PPS and had spherical particles. The mixture ratio of magnet powder to binder powder was 90:10. The experimental results are shown in Table 4. [Table 4]

[0066] From Table 4, it can be seen that when the thickness d of the raw powder layer PL is less than the size of the sieve opening, i.e., thinner than the maximum diameter of the magnet powder, line scratches are observed in the raw powder layer PL. Line scratches are thought to be caused when magnet powder particles larger than d in the raw powder P get caught on the roller 123 and peel off when the raw powder layer PL is formed. If such line scratches are present in the raw powder layer PL, defects (holes, cracks, etc.) are likely to occur when the laser beam LB is irradiated, and the density becomes non-uniform, resulting in a decrease in the mechanical strength of the bonded magnet. On the other hand, when the thickness d of the raw powder layer PL is equal to or larger than the size of the sieve opening, i.e., equal to or smaller than the maximum diameter of the magnet powder, a good raw powder layer PL without line scratches can be produced, and the decrease in the mechanical strength of the bonded magnet can be suppressed.

[0067] From Table 4, when the thickness d of each layer of the raw material powder layer PL when producing the bonded magnet BM is 150 μm, it is desirable that the maximum diameter of the magnet powder is 150 μm or less and the average particle size (D50) of the binder powder is 50 μm or less. Also, when the thickness d of each layer of the raw material powder layer PL is 100 μm, it is desirable that the maximum diameter of the magnet powder is the same as d, 100 μm or less, and more desirable that it is 53 μm or less. In this case, it is desirable that the average particle size of the binder powder is 15 μm or less. When the thickness d of each layer of the raw material powder layer PL is 50 μm, it is desirable that the maximum diameter of the magnet powder is the same as d, 50 μm or less, and more desirable that it is 32 μm or less. In this case, it is desirable that the average particle size of the binder powder is 15 μm or less.

[0068] FIG. 6 shows a schematic cross section of a bonded magnet obtained by the bonded magnet manufacturing apparatus and bonded magnet manufacturing method of the first and second embodiments. This bonded magnet 30 is composed of a plurality of layers 31 that are distinguished from one another by the density of the binder. In each of the layers 31, the binder density increases from one side to the other in the lamination direction. In FIG. 6, the binder density is shown by a schematic shade of color. Here, the direction from one side to the other corresponds to the direction in which the layers 31 are laminated in order when the bonded magnet 30 is produced. In this bonded magnet 30, the parts 311 with high binder density in each layer 31 exist in stripes as walls with high mechanical strength, so that the overall mechanical strength is high.

[0069] The reason why the bonded magnet 30 has such a layered structure will be explained using FIG. 7. In the bonded magnet manufacturing method of the first and second embodiments, as described above, the raw material powder layer PL is formed in the raw material powder supplying step, and the raw material powder layer PL is irradiated with a beam (laser beam LB) in the beam irradiation step. The operation is repeated to produce the bonded magnet 30. In this case, in the beam irradiation step, the side where the beam is incident in the thickness direction of the raw material powder layer PL (the upper side of FIG. 1, FIG. 4, FIG. 7, the "other" side) has a lower attenuation rate of the energy of the beam that reaches it, so the powder of the binder 33 melts better than the opposite side (the lower side of each figure, the "one" side). As a result, when focusing on one layer 31 (corresponding to one layer of the raw material powder layer PL), the binder 33 hardened after melting has a higher density in the binder 331 closer to the side where the beam is incident than in the binder 332 on the opposite side, as shown in FIG. 7 (note that the one marked with the reference numeral 32 in FIG. 7 is a particle of magnet powder). As a result, each layer 31 of bonded magnet 30 has a configuration in which the binder density increases in the direction opposite to the incident direction of the beam (from one side to the other side).

[0070] The present invention is not limited to the above-described embodiments. For example, the pressure application unit 14 may be omitted from the bonded magnet manufacturing apparatus 10 of the first embodiment, and the pressure application step may be omitted from the bonded magnet manufacturing method.

[0071] In the bonded magnet manufacturing apparatus 10 of the first embodiment, a spatula may be used instead of the roller 123. Also, the beam irradiation unit 13 may be one that irradiates the raw material powder P with an electron beam instead of one that irradiates the raw material powder P with a laser beam. The electron beam converts the kinetic energy of the electrons into heat by colliding them with the particles of the raw material powder P, thereby heating the raw material powder P. When an electron beam is used, a scanning mechanism that changes the direction of electron travel by a magnetic field can be used.

[0072] The shape of the bonded magnet to be manufactured is an upwardly convex arc-shaped cross section in FIG. 2G, and a disk shape in FIG. 5, but is not limited to these and can be formed into any three-dimensional shape.

[0073] In the bonded magnet manufacturing apparatus 20 of the second embodiment, the laser beam emitting part 233 may not be provided on the nozzle 223, and a laser beam may be irradiated separately from the laser beam emitting part 233 onto the raw material powder scattered on the upper surface of the base 21 by the nozzle 223. [Explanation of symbols]

[0074] 10, 20... Bonded magnet manufacturing equipment 11, 21…Foundation 111...Base lifting mechanism 12, 22...Raw material powder supply section 121...raw powder storage tank 1211…Bottom of raw powder storage tank 1212: Side wall of raw powder storage tank 122...Storage tank bottom lifting mechanism 123…Laura 13, 23...Beam irradiation unit 131, 231...Laser light source 132...Reflector 133...Scanning mechanism 14...Pressure application section 15…Excess powder collection section 221...raw powder storage section 222...Raw material powder delivery section 223…Nozzle 224...Nozzle movement mechanism 232...Laser light guide 233...Laser beam emission part 30...Bonded magnet 31…Layer in bonded magnet 311...Part of the bonded magnet where the binder density is high 32...Magnetic powder particles 33, 331, 332...Binder BM: Bonded magnet BMP: Preformed part LB: Laser beam P...Raw material powder PL: Layer of raw powder

Claims

1. a) a base; b) a raw powder supply unit that supplies a mixed raw powder containing magnet powder and binder powder having a melting point lower than that of the magnet powder, and does not contain a solvent, to a predetermined powder supply area on the upper surface of the base; c) a pressure applying unit that applies pressure to the mixed raw material powder supplied to the powder supply region and has a pressing surface that corresponds to the shape of the upper surface of the base; d) a beam irradiation unit that irradiates an irradiation area, which is an area of ​​the powder supply area that corresponds to the shape of the bonded magnet to be manufactured, with a beam that heats the mixed raw material powder to a temperature that melts the binder powder without melting the magnet powder; A bonded magnet manufacturing apparatus comprising:

2. The apparatus further includes a raw material powder storage unit for storing the mixed raw material powder, 2. The bonded magnet manufacturing apparatus according to claim 1, wherein the raw material powder supplying section supplies the mixed raw material powder from the raw material powder reservoir to the powder supplying area.

3. The raw material powder supplying unit forms a layer of mixed raw material powder on the base, The beam irradiation unit irradiates a part of the layer of the mixed raw material powder as the irradiation area with the beam.

3. The bonded magnet manufacturing apparatus according to claim 1 or 2.

4. a) a base; b) a raw powder supply unit that supplies a mixed raw powder containing magnet powder and binder powder having a melting point lower than that of the magnet powder, and does not contain a solvent, to a predetermined powder supply area on the base; c) a beam irradiation unit that irradiates an irradiation area, which is an area of ​​the powder supply area that corresponds to the shape of the bonded magnet to be manufactured, with a beam that heats the mixed raw material powder to a temperature that melts the binder powder without melting the magnet powder; d) A nozzle with a double structure having two coaxial spaces. Equipped with One of the two spaces is a part of the raw material powder supplying part and is a passage through which the mixed raw material powder supplied to the powder supplying region passes, The other of the two spaces is a part of the beam irradiation unit and is a passage through which the beam passes to be irradiated to the irradiation area. A bonded magnet manufacturing apparatus comprising:

5. 5. A bonded magnet manufacturing apparatus according to claim 1, wherein the beam irradiation unit heats the mixed raw material powder to a temperature lower than a temperature at which the magnet powder is altered.

6. a raw material powder supplying step of supplying a mixed raw material powder containing a magnet powder and a binder powder having a melting point lower than that of the magnet powder, the mixed raw material powder not containing a solvent, to a predetermined powder supplying area on an upper surface of a base; a pressure applying step of applying pressure to the mixed raw material powder supplied to the powder supply region by a pressure applying unit having a pressing surface shaped to correspond to the upper surface of the base; a beam irradiation step of irradiating an irradiation area, which is an area of ​​the powder supply area corresponding to the shape of the bonded magnet to be manufactured, with a beam for heating the mixed raw material powder to a temperature that melts the binder powder without melting the magnet powder; A method for producing a bonded magnet comprising the steps of:

7. 7. The method for producing a bonded magnet according to claim 6, wherein in the raw material powder supplying step, the mixed raw material powder is stored in a raw material powder storage section, and the mixed raw material powder is supplied from the raw material powder storage section to the powder supplying region.

8. The raw material powder supplying step forms a layer of mixed raw material powder on the base, The beam irradiation step is a step of irradiating a part of the layer with the beam as the irradiation region.

8. The method for producing a bonded magnet according to claim 6 or 7.

9. 9. The method for producing a bonded magnet according to claim 8, wherein the thickness of the layer of the mixed raw material powder is equal to or greater than the maximum diameter of the particles of the magnetic powder.

10. 10. The method for producing a bonded magnet according to claim 6, wherein the particles of the binder powder are spherical.

11. 11. A method for producing a bonded magnet according to claim 6, wherein the beam irradiation step heats the mixed raw material powder to a temperature lower than a temperature at which deterioration of the magnet powder occurs.

Images