CN100413572C - Apparatus for producing granulated powder of rare earth alloy - Google Patents

Apparatus for producing granulated powder of rare earth alloy Download PDF

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CN100413572C
CN100413572C CNB200610078182XA CN200610078182A CN100413572C CN 100413572 C CN100413572 C CN 100413572C CN B200610078182X A CNB200610078182X A CN B200610078182XA CN 200610078182 A CN200610078182 A CN 200610078182A CN 100413572 C CN100413572 C CN 100413572C
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powder
flow
granulation
air
groove
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CN1861247A (en
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国吉太
大谷智郁
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Proterial Ltd
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Hitachi Metals Ltd
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Abstract

The invention discloses a preparing device of rare earth alloy granulating powder, which comprises the following parts: platform groove to contain rare earth alloy powder, first flow path of first flow in the groove to flow platform from downwards to upwards, second flow path of second flow in the groove to flow platform from upwards to downwards, wherein the first and second flow paths connect the groove individually.

Description

The manufacturing installation of granulated powder of rare earth alloy
This case is On November 27th, 2002, application number is 02804993.4, denomination of invention is Rare earth alloy granulation The manufacture method of the manufacture method of powder, the manufacturing installation of granulated powder of rare earth alloy and rare earth alloy sintered compactDivide an application
Technical field
The present invention relates to a kind of manufacturing installation of granulation powder of manufacture method, rare earth alloy of granulation powder of rare earth alloy and the manufacture method of rare earth alloy sintered compact.
Background technology
The sintered magnet of rare earth alloy (permanent magnet) is normally with the formed body of the powder pressing forming of rare earth alloy, the resulting powder of sintering, make by Ageing Treatment again.Now, these two kinds of terres rares-cobalt series magnet and rare earth-iron-boron based magnets are widely-used in every field.Wherein, since rare earth-iron-boron based magnet (hereinafter referred to as " R-Fe-B series magnet ".R is the rare earth element that contains Y, and Fe is an iron, and B is a boron.) in various magnets, demonstrating the highest maximum magnetic energy product, price is also relatively more cheap, therefore actively is used for various e-machines.
The R-Fe-B based sintered magnet is mainly by R 2Fe 14The rich R phase of formation such as the principal phase that B regular crystal compound forms, Nd, reach rich B and constitute mutually.Also have, the part of Fe also can be replaced with the transition metal of Co or Ni etc., and the part of boron (B) also can be replaced by carbon (C).The R-Fe-B based sintered magnet that the present invention is suitable for for example is documented in the 4th, 770, No. 723 specifications of United States Patent (USP) and the 4th, 792, No. 368 specifications of United States Patent (USP).
In order to make the R-Fe-B that forms such magnet is alloy, uses ingot casting method at present.Utilize common ingot casting method, the high frequency dissolving is made alloy pig by relatively slowly cooling off with resulting liquation as rare earth metal, electrolytic iron and the ferroboron of initiation material in mold.
In recent years, inner face by making alloy liquation and single roller, two roller, rotating circular disk or rotor mold etc. contacts, cooling more quickly, what make the solidified superalloy (be called " alloy sheet ") thinner than ingot by the alloy liquation is that the quench of representative is extremely gazed at thin strip casting method and centre spinning.The thickness of the alloy sheet of making by such quench, normally about 0.03mm is above, the scope below about 10mm.By quench, the alloy liquation begins to solidify from the face (roller contact-making surface) of contact chill roll, and crystallization is column from the roller contact-making surface towards thickness direction and grows up.Its result by the quick cooling alloy of making such as thin strip casting method, has the following R of the above about 100 μ m of the about 0.1 μ m of the size that the contains short-axis direction above about 500 μ m of the about 5 μ m of size following, long axis direction 2Fe 14B crystalline phase and dispersion are present in R 2Fe 14The tissue of the rich R phase in the intergranular of B crystalline phase.Rich R is the higher non magnetic phase of concentration ratio of rare earth element R mutually, and its thickness (width that is equivalent to intergranular) is about below the 10 μ m.
Quick cooling alloy is compared with the alloy of making by existing ingot casting method (die casting method) (ingot alloy), because can be in short relatively time (cooling velocity: 10 2More than ℃/second, 10 4Below ℃/second) cooling, so have the miniaturization organized, characteristics that the crystallization particle diameter is little.Therefore in addition, the area of intergranular is bigger, and rich R is widely expansion in intergranular, even also have reasonable advantage aspect rich R phase dispersed.Because these features by using quick cooling alloy, can be made the magnet with excellent magnetism feature.
In addition, we also know the method that is called as Ca reducing process (or reduction-diffusion process).The method comprises following operation.At first, contain in the mixed powder of alloyed powder that at least a, iron powder in the rare-earth compounds and at least a mixed powder in pure boron powder, iron boron powder and the boron oxide compound or ratio in accordance with regulations contain above-mentioned formation element or mixed oxide in accordance with regulations ratio, hybrid metal calcium (Ca) and calcium chloride (CaCl) reduce DIFFUSION TREATMENT under inert gas environment.With resulting reaction product slurryization, by water treatment, obtaining R-Fe-B thus is the solid of alloy it.
Also have, in this manual, the piece of solid alloy is called " alloy block ", be not only the solidified superalloy that the liquation of alloy sheet that the alloy pig that obtains by existing ingot casting method and cooling obtain by quench such as thin strip casting methods etc. obtains, also comprise the solid alloy of the various forms such as solid alloy that obtain by the Ca reducing process.
The alloy powder that offers compression moulding obtains as follows, promptly, (for example utilize hydrogen preservative for example and/or various mechanical crushing method, use disc grinder) these alloy blocks are pulverized, it is broken to utilize the dry type comminuting method for example use jet mill that resulting corase meal (for example, average grain diameter 10 μ m~500 μ m) is carried out micro mist again.
Offer the average grain diameter of the R-Fe-B series alloy powder of compression moulding, from the viewpoint of magnetic characteristic, preferably in the scope of 1.5 μ m~6 μ m.Also have, " average grain diameter " of powder is so long as when not specifying in advance, just be meant the FSSS particle diameter at this.Yet if mobile, compression moulding (comprising die cavity filling and compressibility) is poor when using the little powder of average grain diameter, productivity is poor.
As ways of addressing this issue, studying the technology on the surface of covering alloy powder particle with lubricator.For example, open flat 08-111308 communique and United States Patent (USP) the 5th the spy, 666, following technology is disclosed in No. 635 specifications, that is, be in the corase meal of alloy at the R-Fe-B of average grain diameter 10 μ m~500 μ m, add the lubricant of 0.02 quality %~5.0 quality % with the liquefaction of at least a fatty acid ester after, using the jet mill of inert gas to pulverize, is the technology of the micropowder (for example average grain diameter 1.5 μ m~5 μ m) of alloy thereby make R-Fe-B.
Lubricant is when improving the flowability of powder, mouldability (compressibility), owing to have the effect of the bond of giving formed body hardness (intensity), in sintered body, become the reason that makes magnetic low in addition, so require to have the excellent bond that takes off as remaining carbon residue.For example, open in the 2000-306753 communique,, disclose the mixture of depolymerization polymer, depolymerization polymer and hydrocarbon system solvent and the mixture of depolymerization polymer and low viscosity mineral oil and hydrocarbon system solvent as the lubricant that takes off the bond excellence the spy.
Yet,,, be difficult to evenly filling in die cavity, and can not obtain sufficient mouldability though can get to a certain degree the effect of improving according to the method for using above-mentioned lubricant.Particularly, with quench (cooling velocities 10 such as thin strip casting methods 2/ second~10 4/ second) powder of making is compared with the powder of making by ingot casting method, because not only average grain diameter is little, have sharp grain size distribution (precipitous) is so flowability is poor especially.Therefore, the volume production that is filled in the powder in the die cavity changes moving, surpasses allowed band, and the packing density in the die cavity is inhomogeneous.Its result, the quality of formed body, size produce change, surpass allowed band, and formed body goes out breach and fracture phenomena.
As other method of flowability that is used to improve the R-Fe-B series alloy powder and mouldability, attempt using the granulation powder.
For example, open in the clear 63-237402 communique the spy and to disclose following content, promptly, add the alkane mixture of liquid condition at room temperature of 0.4~4.0 quality % and the mixture of aliphatic carboxylic acid with respect to powder, after mixing,, can improve mouldability by using the granulation powder that obtains by granulation.In addition, we also know the method for use as the PVA (polyvinyl alcohol) of granulating agent.Also have, granulating agent is also the same with lubricant, plays the effect of bond, helps to strengthen the intensity of formed body.
Yet, when using above-mentioned spy to open the disclosed granulating agent of clear 63-237402 communique,, under the situation of R-Fe-B based sintered magnet, exist because of residue carbon in sintered body to make the problem of magnetic characteristic reduction because it is poor to take off bond.
In addition, use PVA and utilize the granulation powder of jet drying manufactured, on the contrary, because adhesion is strong, resulting granulation powder is really up to the mark, even apply outside magnetic field, the granulation powder can not be crumbled fully.Therefore, can not make primary particle carry out sufficient field orientation, its result, existence can not obtain having the problem of the magnet of excellent magnetism feature.PVA to take off bond also relatively poor, the carbon that PVA brought remains in the magnet easily.In order to address this problem, also to have and under hydrogen environment, take off the method that bond is handled, but be difficult to remove fully carbon elimination.
In addition, the present inventor, be difficult to the problem that crumbled by directional magnetic field in order to solve the granulation powder, proposed by applying the method (opening flat 10-140202 communique) of carrying out granulation under the state of magnetostatic field, each particle (primary particle) of field orientation being utilized the making granulation powder of granulating agent combination with reference to the spy.If use this granulation powder, compare with the situation of using the granulation powder that will utilize the granulating agent combination without the primary particle of field orientation and make, although can improve magnetic characteristic, but during owing to compression moulding, be difficult to carry out sufficient field orientation, so compare with the situation of the rare earth alloy powder that uses not granulation, magnetic characteristic is low.
As mentioned above, studying various granulating agents and prilling process at present, but also untapped to go out can make flowability, compression moulding excellent and have a method of the industrial granulated powder of rare earth alloy of energy of the magnet of excellent magnetic characteristic.
On the other hand, the needs of the miniaturization of magnet, slimming and high performance have improved, and wish the manufacture method of exploitation with the small-sized or slim high performance magnet of high efficiency manufacturing.Usually, if rare earth alloy sintered compact (or carry out magnetized magnet with it) is carried out machining, because of the influence of machining deformation, magnetic characteristic is low, but with regard to small-sized magnet, can not ignore the low of this magnetic characteristic.Therefore, strong wish to resemble small-sized magnet, do not need to carry out the dimensional accuracy of machining, make sintered body with employed net shape with essence.From such background, stronger to rare earth alloy powder, particularly R-Fe-B series alloy powder demand mobile, the compression moulding excellence.
Summary of the invention
The present invention is in view of premises exploitation, and its main purpose is to provide a kind of flowability and compression moulding excellence and can makes the manufacture method of the granulated powder of rare earth alloy of the magnet with excellent magnetic characteristic, and makes the method for high-quality rare earth alloy sintered compact with high production efficiency.
The manufacture method of granulated powder of rare earth alloy of the present invention comprises: the operation of preparing rare earth alloy powder; Above-mentioned powder is given the operation of remanent magnetism; The operation that utilization is carried out granulation by the cohesiveness of the remanent magnetism generation of above-mentioned powder.Achieve the above object thus.
Preferred above-mentioned granulating working procedure comprises gives operation to above-mentioned powder particle with kinergety, the process that the rotary action that above-mentioned particle utilization is produced by the kinergety of giving is grown up, and essence takes place under zero magnetic field
Above-mentioned manufacture method also can comprise: preparation has the operation of the above-mentioned powder of remanent magnetism in groove; In above-mentioned groove, essence is under zero magnetic field, give operation to above-mentioned powder particle with kinergety.Perhaps, also can comprise: the operation of in groove, preparing above-mentioned powder; By the operation that the above-mentioned powder in the above-mentioned groove is applied magnetic field, above-mentioned powder given remanent magnetism; In above-mentioned groove, essence is under zero magnetic field, give operation to the above-mentioned powder particle with remanent magnetism with kinergety.
The operation that granulating agent is imparted to above-mentioned powder can be also comprised, also the operation that granulating agent is imparted to above-mentioned powder can be do not comprised.
Preferably the operation of giving remanent magnetism to above-mentioned powder is undertaken by applying alternation decay magnetic field.
Preferred above-mentioned rare earth alloy be contain Dy be the above or Tb of 2 quality % be 1 quality % above or Dy and Tb to add up to the above R-Fe-B of 1 quality % be alloy.
The average grain diameter of preferred above-mentioned powder is more than 1.5 μ m in the scope below the 6 μ m.
Preferred above-mentioned granulating working procedure is to make the operation that average grain diameter is in the granulation powder in the following scope of the above 3.0mm of 0.05mm.
The manufacture method of rare earth alloy sintered compact of the present invention comprises: the operation of using the manufacture method manufacturing granulation powder of above-mentioned arbitrary granulated powder of rare earth alloy; Above-mentioned granulation powder is not applied the rare earth alloy powder that takes off magnetic magnetic field, will comprise above-mentioned granulation powder and be filled in operation in the die cavity; Under the state that the rare earth alloy powder that comprises above-mentioned granulation powder is applied directional magnetic field, by compression moulding, form the operation of formed body; The operation of the above-mentioned formed body of sintering.Achieve the above object thus.
Granulated powder of rare earth alloy of the present invention is characterised in that: comprising the average grain diameter with remanent magnetism is the following rare earth alloy powders of the above 6 μ m of 1.5 μ m, in the scope of average grain diameter below the above 3.0mm of 0.05mm, above-mentioned powder utilization is interosculated by the cohesiveness that above-mentioned remanent magnetism produces.
The manufacture method of the granulated powder of rare earth alloy of certain embodiment of the present invention is characterised in that: comprising: the operation of (a) preparing to have the rare earth alloy powder of remanent magnetism with the state of mounting on the platen with aeration in groove; (b) in above-mentioned groove, generate from the operation of following the 1st air-flow that upwards flows of above-mentioned platen; (c) give kinergety, utilization by the cohesiveness of the remanent magnetism generation of above-mentioned powder with by the rotary action of above-mentioned kinergety generation, essence is carried out granulation under zero magnetic field operation by above-mentioned the 1st air-flow to above-mentioned powder particle; (d) in above-mentioned groove, generate operation with respect to above-mentioned platen the 2nd air-flow from the top down; (e) on above-mentioned platen, form the powder bed that forms by above-mentioned powder, compress the operation of above-mentioned powder bed by above-mentioned the 2nd air-flow; Carry out at least a portion of operation (d) and at least a portion of operation (b) simultaneously.Achieve the above object thus.
In certain preferred implementation, carry out simultaneously operation (d) and operation (b) during, while comprise the flow that makes above-mentioned the 1st air-flow reduce, make above-mentioned the 2nd air-flow the flow increase during.
Operation (a) can comprise: configuration does not have the operation of the rare earth alloy powder of remanent magnetism in above-mentioned groove; By the above-mentioned powder that does not have remanent magnetism that is configured in the above-mentioned groove is applied the operation that remanent magnetism is given in magnetic field.Perhaps, operation (a) also can comprise: the operation of preparing the rare earth alloy powder with remanent magnetism in advance; Configuration has the operation of the above-mentioned powder of remanent magnetism in above-mentioned groove.
In certain preferred implementation, undertaken repeatedly by the reiteration of operation (b), operation (c), operation (d) and operation (e).
In certain preferred implementation, comprise: above-mentioned repeatedly during, at least once operation (e) afterwards, (f) under the state that generates above-mentioned the 2nd air-flow in case stop above-mentioned the 1st air-flow, then, stopping under the state of above-mentioned the 2nd air-flow, by generating above above-mentioned the 1st air-flow of the flow of the average discharge of above-mentioned the 1st air-flow in the operation (c), the operation of separating the broken above-mentioned powder bed that on above-mentioned platen, forms.
In certain preferred implementation, above-mentioned rare earth alloy is that R-Fe-B is an alloy.
In certain preferred implementation, the average grain diameter of above-mentioned powder is more than 1.5 μ m in the scope below the 6 μ m.
In certain preferred implementation, make the granulation powder in the scope of average grain diameter below the above 3.0mm of 0.05mm.
The manufacture method of rare earth alloy sintered compact of the present invention is characterised in that: comprising: the operation of using the manufacture method manufacturing granulation powder of above-mentioned arbitrary granulated powder of rare earth alloy; Above-mentioned granulation powder is not applied the rare earth alloy powder that takes off magnetic magnetic field, will comprise above-mentioned granulation powder and be filled in operation in the die cavity; Under the state that the rare earth alloy powder that comprises above-mentioned granulation powder is applied directional magnetic field, by compression moulding, form the operation of formed body; The operation of the above-mentioned formed body of sintering.
The manufacturing installation of granulated powder of rare earth alloy of the present invention is characterised in that: have: the groove that is provided with the platen that holds rare earth alloy powder; Connect above-mentioned groove, in above-mentioned groove, can generate from the 1st stream of following the 1st air-flow that upwards flows of above-mentioned platen; Connect above-mentioned groove, in above-mentioned groove, can generate from the 2nd stream of the 2nd air-flow that flows downward of above-mentioned platen; Above-mentioned the 1st stream and above-mentioned the 2nd stream are connected in above-mentioned groove independently of each other.Achieve the above object thus.
Preferably in above-mentioned the 1st stream, also have register and air-supply arrangement.
It also can be the structure that in above-mentioned the 2nd stream, also has buffer container.
Preferably have the thermometer that detects gas temperature in the above-mentioned groove, and have if detected temperature surpasses the control loop that the temperature of regulation then makes the action of above-mentioned air-supply arrangement stop at least.
Keep malleation in the above-mentioned groove in the preferred motion.
Also can be also to have the structure that can apply the field generator for magnetic in magnetic field to the above-mentioned powder of mounting on above-mentioned platen.
Description of drawings
Fig. 1 (a) is the schematic diagram of structure of the granulation powder of expression embodiment of the present invention, and Fig. 1 (b) and Fig. 1 (c) are the structural maps that expression is used for the existing granulation powder of comparison.
Fig. 2 is the known prilling granulator 20 of granulation is carried out in expression with the fluidized bed comminution granulation a schematic diagram.
Fig. 3 is that R-Fe-B that expression is used for embodiment of the present invention is the schematic diagram of the prilling granulator 100 made of alloy granulation powder.
Fig. 4 (a) and (b) be the schematic diagram of the state (time of flow changes) that is illustrated in the air-flow in the groove in the granulation powder manufacture method of embodiment of the present invention.
Fig. 5 is the figure that the residual flux density Br of the sintered magnet that the granulation powder of the granulation powder of the embodiment of the invention and comparative example obtains is used in expression.
The specific embodiment
Below, with reference to accompanying drawing, the manufacture method of granulation powder of embodiment of the present invention and the manufacture method of rare earth alloy sintered compact are described.In the explanation of following embodiment, with the reverse side of magnetic characteristic excellence, particularly use the manufacture method of the sintered magnet of the mobile low R-Fe-B series alloy powder of making by the thin strip casting method feature of the present invention to be described as example, but the invention is not restricted to this, also can use the rare earth alloy powder of making by additive method.
The R-Fe-B of embodiment of the present invention is the manufacture method of alloy sintered compact, comprising: the operation of making R-Fe-B and be the powder (below, be called " material powder " or " primary particle powder ") of alloy; Material powder is given the operation of remanent magnetism; The operation that utilization is carried out granulation by the cohesiveness of the remanent magnetism generation of material powder; Under the state that the R-Fe-B series alloy powder that contains the granulation powder is applied magnetic field, form the operation of formed body by compression moulding; The operation of sintered moulded body.By resulting sintered body being magnetized, can obtain the R-Fe-B based sintered magnet with known method.Also have, the magnetization operation can be carried out any time behind sintering, for example, can be carried out before will using by the user of sintered magnet.Here, unmagnetized person is also referred to as sintered magnet.
At the R-Fe-B of embodiment of the present invention is in the manufacture method of alloy sintered compact, and utilization is carried out granulation because of the cohesiveness of the remanent magnetism generation of material powder.Therefore, can reduce granulating agent addition or, use adhesion than low bond now.And, even the interpolation that can omit granulating agent.
With reference to Fig. 1 (a) and (b) and (c), the manufacture method of granulation powder of embodiment of the present invention and the feature of resulting granulation powder are described.The left side of Fig. 1 is the schematic diagram of expression granulation powder structure, and the right side of Fig. 1 is to be illustrated in the schematic diagram that applies the granulation powdery attitude behind the directional magnetic field in the die cavity that is used for compression moulding.The granulation powder 12a of Fig. 1 (a) expression embodiment of the present invention, (b) the existing granulation powder 12b of granulating agent is used in expression, (c) the granulation powder 12c that obtains of the expression method of utilizing above-mentioned spy to open flat 10-140202 communique record.
Shown in Fig. 1 (a), the granulation powder 12a of embodiment of the present invention is that the primary particle 10a with remanent magnetism carries out weak combination by magnetic cohesiveness.Here illustration is not used the situation of granulating agent.Primary particle 10a with remanent magnetism carries out the magnetic combination in the mode that forms the magnetic loop circuit, the remanent magnetism of granulation powder 12a very small (for example greater than 0mT, below the 10mT about (milli tesla)).The direction of the remanent magnetism of the primary particle 10a among the granulation powder 12a is different with the granulation powder 12c shown in Fig. 1 (c), irregularly directed.For example, the average grain diameter of primary particle 10a is below the above 6.0 μ m of 1.5 μ m, and the average grain diameter of granulation powder 12a is from about the 0.05mm to 3.0mm.Remanent magnetism can insert the probe of gaussmeter in the granulation powder and measure.
Because this granulation powder 12a has the particle diameter of appropriateness, thus good fluidity, and remanent magnetism is also low, can be filled in the die cavity equably easily, and can not cause bridge joint (bridging).And, because primary particle 10a only carries out combination by magnetic cohesiveness, as the left side diagram of Fig. 1 (a), by directional magnetic field (for example 0.1T~0.8T) apply the primary particle 10a that crumbles really, primary particle 10a carries out field orientation.In addition, because do not contain granulating agent, so can not increase the carbon amount of sintered body.By the resulting magnet of sintered body that magnetization uses this granulation powder 12a to make, have with material powder (remanent magnetism essence is zero) not being carried out the identical in fact magnetic characteristic of the resulting magnet of granulation.That is, the granulation powder of the application of the invention embodiment can not make magnetic characteristic reduce, and can improve liquidity and mouldability.Certainly, on purpose, also can add granulating agent for intensity of improving formed body etc.Because granulating agent is auxiliary the use, so do not need strong adhesion, reduce in order not make magnetic characteristic, can select its amount and kind.
Relative therewith, shown in Fig. 1 (b), make the granulation powder 12b of the primary particle 10b combination of material powder by granulating agent 14, in directional magnetic field, do not crumble fully, its result, the magnetic characteristic of resulting sintered magnet reduces.With material powder is not carried out granulation and compares with regard to the situation of using, for example, remanent magnetism reduces about 1%~10%.Also have, the primary particle 10b among the granulation powder 12b of Fig. 1 (b), owing to do not have remanent magnetism, so there is not marker arrow.
In addition, shown in Fig. 1 (c), in magnetostatic field, make the directed granulation powder 12c that makes primary particle 10c combination, fixedly forms with granulating agent 14 of primary particle 10c on one side on one side as if using, though can suppress the reduction of magnetic characteristic, but because granulation powder 12c not exclusively crumbles to primary particle 10c, so with material powder is not carried out granulation and compares with regard to the situation of using, for example, remanent magnetism reduces about 1%~number %.Also have, shown in Fig. 1 (c), granulation powder 12c is elongated shape along pole orientation, is disadvantageous from the viewpoint of flowability.And, because granulation powder 12c has bigger remanent magnetism,,, bridge joint just can not be fills up in the die cavity in case taking place if do not take off magnetic (demagnetization).
Relative therewith, the granulation powder 12a of embodiment of the present invention, subglobular, and because remanent magnetism is little need not take off magnetic, can be filled in the die cavity equably easily.Therefore, adopting in advance, the granulation powder of metering definite quality is filled in the interior what is called " metering filling method " of die cavity afterwards.As mentioned above, the granulation powder 12a of embodiment of the present invention, the mobile filling excellence that reaches die cavity, and, can make the undiminished sintered magnet of magnetic characteristic in fact.
The granulation powder of embodiment of the present invention is by comprising that to give the prilling process of the process that rotary action that kinergety, particle cause by the kinergety that is endowed grows up to the material powder particle with remanent magnetism resultant.Also have, as required, also can add granulating agent.
In the manufacture method of the granulation powder of embodiment of the present invention, the operation of giving material powder remanent magnetism can be carried out before the filling material powder in the groove (granulation groove) of prilling granulator, also can prepare (filling) in groove and carry out afterwards.But, the primary particle 10a of the granulation powder 12a of present embodiment is because the magnetic cohesiveness of utilizing remanent magnetism to produce is carried out combination, so if apply magnetic field from the outside, then granulation powder 12a crumbles.Therefore, the developmental process of particle is to carry out under essence zero magnetic field.This be with in the manufacture method of the granulation powder 12c shown in Fig. 1 (c), before final granulation agent of granulation powder 12 14 are fixing, directed and need apply magnetic field continuously and contrast in order to make primary particle 10c.Also have, the what is called in this specification " essence zero magnetic field " is meant in the process that particle is grown up by rotary action, can have influence on remanent magnetism that remanent magnetism by powder forms the degree that obtains of granulation powder of magnetic loop circuit and the powder magnetic field a little less than like this.
Various magnetic fields can be used in the magnetic field that applies in order to give remanent magnetism.Also have,, preferably use alternation decay magnetic field because the remanent magnetism that primary particle had is very small.Also have, the magnetic field that is used to give remanent magnetism is not limited to alternation decay magnetic field, also can use monotonic decay magnetic field, other pulsed magnetic field, magnetostatic field.
If even it is also little to give the coercivity of remanent magnetism, material powder, obtain so before the final granulation powder during demagnetization, can not keep the shape of granulation powder.Therefore, preferred coercivity is than higher material powder.Specifically, material powder is filled in the container, makes that bulk density is 2.0g/cm 3, the coercitive value that will measure with the BH gage outfit is as the apparent coercivity of material powder, and material powder preferably has the above coercivity of 70kA/m, more preferably has the above coercivity of 80kA/m.For example, be under the situation of alloy at R-Fe-B, what preferably contain the above Dy of 2 quality % or the above Tb of 1 quality % or Dy and Tb adds up to the above alloy of 1 quality %.
As for being the powder of alloy, from the viewpoint of flowability and mouldability, preferably only use above-mentioned such granulation powder of making, but also granulation powder and material powder (primary particle powder) mixing can be used in the R-Fe-B of compression moulding.But, the ratio of material powder is then mobile to be reduced if increase, and therefore improves effect in order fully to obtain by the flowability that granulation produces, and preferably in fact only uses the granulation powder.In addition, in being mixed in the granulation powder and use under the situation of material powder, the preferred particulates surface with lubricator covers.By with lubricator covering the surface of primary particle, can improving R-Fe-B is the flowability of powder, can prevent that R-Fe-B from being the oxidation of alloy simultaneously.In addition, also can improve directionality in the suppression process of magnetic field.Also have, in this manual, be not only the powder (oxide layer that can contain the surface) of rare earth alloy in fact, the confession that also will contain granulating agent and lubricant with the powder of rare earth alloy is called " powder of rare earth alloy " in the powder of compression moulding.
Using the R-Fe-B of embodiment of the present invention by the process sequence explanation below is the manufacture method of the magnet of alloy sintered compact.
At first, use the thin strip casting method, making R-Fe-B is alloy sheet (for example with reference to United States Patent (USP) 5,383, No. 978).Specifically, will be that alloy utilizes the high frequency dissolving to form liquation by the R-Fe-B of known method manufacturing.Also having, is alloy as R-Fe-B, except above-mentioned, can suitably use the alloy of the composition of putting down in writing in the specification of No. the 4th, 792,368, for example No. the 4th, 770,723, United States Patent (USP) and United States Patent (USP).In the typical composition of R-Fe-B based rare earth alloy, mainly use Nd or Pr as R, Fe can be by the displacement of part transition elements (for example Co) part, and B can be replaced by C.
After the liquation of this alloy remained on 1350 ℃, being about 1m/ second, cooling velocity in the roller peripheral speed was that 500 ℃/second, degree of supercooling are that chilling on single roller obtains the alloy sheet that thickness is 0.3mm under 200 ℃ the condition.Make this alloy sheet absorb hydrogen, obtain the alloy corase meal by making it embrittlement.Broken by using jet mill under nitrogen environment this alloy corase meal to be carried out micro mist, the specific area that for example obtain that average grain diameter is 1.5 μ m~6 μ m, is recorded by the BET method is about 0.45m 2/ g~about 0.55m 2The alloy powder of/g (material powder).The real density of this material powder is 7.5g/cm 3
Then, give remanent magnetism to resulting material powder.Here, apply the alternation decay magnetic field that magnetic field, peak is 1.0T.
Then, the material powder with remanent magnetism is carried out granulation.Here, use the fluidized bed comminution granulation.If use the fluidized bed comminution granulation, can obtain the granulation powder of subglobular shape, can obtain the granulation powder of appropriate hardness simultaneously.If the granulation powder has the shape of subglobular, flowability and mouldability are preferred so.In addition, the hardness of granulation powder also is subjected to the influence of granulating agent, as mentioned above, crosses as hard as soft all bad.
Fig. 2 schematically shows the known prilling granulator 20 that carries out granulation with the fluidized bed comminution granulation.Prilling granulator 20 has: air-supply air blast 21, conditioning device 22, the groove 23 that flows, transfer valve 24, the contrary pressure with air blast 26.As such prilling granulator 20, for example can suitably use the swing type processing equipment (swing-processor) of " only パ ウ ダ Le Co., Ltd. " system.
At first, utilize by air-supply and flow, in the groove 23 that flows, carry out common liquidation with the air that air blast 21 forms.At this moment, utilize malleation to make the direction of arrow mobile (flow process) of air stream by solid line.Then, transfer valve 24 is switched, utilize contrary the pressure to make air by direction shown in the arrow of the dotted line among the figure mobile (densification process) with air blast 26.In the densification process, utilize downward air stream, powder bed forms and is compressed, and the hardness of granulation powder increases.On the other hand, in flow process, utilize air stream upwards, the powder bed that forms in the densification process is crumbled, and by the milling action of liquidation air, can generate the granulation powder of subglobular shape.Also can carry out the switching of transfer valve 24 repeatedly, reach the cycle repeatedly, can adjust the hardness of granulation powder by the control air capacity.In addition, by the time of control granulating working procedure, can adjust the average grain diameter of granulation powder.
Also have, in existing mobile groove comminution granulation, utilize in groove from bottom to top airflow flowing to make the operation (flow process) of flow of powder (being also referred to as " rectification ") and utilize from top to bottom the operation of airflow flowing compressing powder layer (densification process) to carry out as operation respectively.For example, in the mobile compression set of in No. 3019953 communique of patent (for example Fig. 3), putting down in writing, have the structure that air-flow (being called " the 1st air-flow ") that is used to carry out flow process and the air-flow (being called " the 2nd air-flow ") that is used to carry out the densification process can change, these two kinds of air-flows can not take place in groove simultaneously.
The inventor has carried out various experiments, and its result by making the 1st air-flow that carries out flow process and carrying out the 2nd air-flow existence simultaneously in groove of densification process, can more effectively make the granulation powder of rare earth alloy as can be known.
Can think that this is because the true specific gravity of rare earth alloy is greater than 7.5g/cm 3, and/or, utilize this more weak power of remanent magnetism to make the granulation powder.This is based on following experimental fact: under the situation without bond, after the state that in groove, coexists through the 1st air-flow and the 2nd air-flow, if do not carry out the densification process, then the fabrication yield of granulation powder reduces, in contrast, using under the situation of bond, can not confirm favourable poor with existing method.Yet, not clear by the reason that the 1st air-flow and the coexistence of the 2nd air-flow improve the manufacturing efficient of granulation powder.
With reference to Fig. 3 and Fig. 4, describe the manufacture method and the manufacturing installation of the granulation powder of embodiment of the present invention in detail.
Fig. 3 is the structural representation of granulation powder manufacturing installation 100 of the manufacture method of the expression granulation powder that is suitable for embodiment of the present invention.Fig. 4 (a) and (b) be the schematic diagram that is illustrated in the stream condition (time of flow changes) in the groove in the manufacture method of granulation powder of embodiment of the present invention.
The manufacturing installation 100 of granulation powder shown in Figure 3 has: groove (groove flows) 30; Can in groove 30, be created on the 1st stream 40 (a) of the 1st air-flow that flows from bottom to top continuously in the groove 30; Can in groove 30, be created on the 2nd stream 50 (b) of groove 30 continuous the 2nd air-flows that flow from the top down.The 1st stream 40 (a) is connected with groove 30 independently of each other with the 2nd stream 50 (b).Also have, reference marks 40 and 50 is used for the situation that main finger constitutes the physique of the 1st stream and the 2nd stream separately, and reference marks a and b are used for mainly finger in the situation of the 1st stream and the 2nd stream air flow path separately.
Groove 30 has the structure of holding the container 62 that is filled with rare earth alloy powder in its bottom.The base plate of container 62 (platen) 62b has aeration, is for example formed by net, cloth to obtain.From the viewpoint of operability, preferably use container 62 as described above, also can be other structure if groove 30 has the platen of aeration.
Be positioned in the rare earth alloy powder on the base plate 62b of container 62, can be endowed kinergety, carry out liquidation by the 1st air-flow that flows from bottom to top with respect to base plate 62b.At this moment, utilization is carried out granulation process by the cohesiveness of the remanent magnetism generation of rare earth alloy powder and the rotary action that is produced by the kinergety of giving powder by the 1st air-flow under essence zero magnetic field.In addition, utilize the deadweight of powder and/or the 2nd air-flow on base plate 62b, to form powder bed, compress this powder bed by the 2nd air-flow and carry out the densification process.
The 1st stream 40 has register 42, air-supply arrangement (for example air-supply air blast) 44 and pipe arrangement 46, connects (binding) groove 30 by valve 47 and 48, forms the 1st stream a (with reference to arrow A among Fig. 31 and A2) that makes the gas circulation in the groove 30.In order to suppress the oxidation of rare earth alloy powder, preferably use inert gas (rare gas or nitrogen), use nitrogen here.Also have, the volume fraction of the oxygen that contains in the preferred gas is controlled at below 0.1%.
In addition, if the temperature of rare earth alloy powder is too high, then coercivity reduces, the result that the cohesiveness of powder reduces, be difficult to form the granulation powder, and/or, in order to suppress the oxidation of rare earth alloy powder, the temperature of preferred control gas more preferably is controlled at more than 20 ℃ in the scope below 30 ℃ in the scope below 40 ℃ more than 10 ℃.Certainly, as required,, also humidity control device can be set in order from gas, to remove moisture.
Air-supply arrangement 44, use is carried out temperature controlled gas by register 42 and is generated the 1st air-flow.The flow of the 1st air-flow that generates in groove 30 is undertaken by the output of adjustment air-supply arrangement 44 and/or the aperture of valve 47.
The 2nd stream 50 has buffer container 52 and pipe arrangement 56, connects (binding) groove 30 by valve 57 and 58, forms the 2nd stream b (with reference to arrow B among Fig. 31 and B2) that makes the gas circulation in the groove 30.Also have, buffer container 52 is connected in former pipe arrangement (for example factory's nitrogen pipe arrangement) 54 by adjuster 53.Be supplied to the nitrogen gas pressure of former pipe arrangement 54, for example be about 7kg/cm 2, count kg/cm by adjuster 53 step-downs 2The flow of the 2nd air-flow that generates in groove 30 is undertaken by the aperture of adjusting valve 57 and 58.
The two ends of the 1st stream 40 and the 2nd stream 50 are connected to groove 30, and the stream essence of gas is sealed.Therefore, the state (temperature-humidity) of the nitrogen in the control flume 30 etc. the time, can hang down the consumption that subtracts nitrogen efficiently.Yet, if form closed system completely because the adjusting of air-flow is difficult, so preferred adopt by valve 66 with blast pipe 64 be connected in groove 30, with the structure of the nitrogen in the resistance drain tank 30 of regulation.At this moment, when work, preferably adjust the resistance of blast pipe 64 at least, environmental pressure (atmospheric pressure) height outside the feasible pressure ratio groove of keeping in the groove 30 30.
And, because the easy oxidation of rare earth alloy powder has the danger of outburst if temperature anomaly rises.Therefore, be provided for detecting the thermometer 38 of temperature in the groove 30, the preferred setting when if the temperature in the groove 30 surpass the temperature of predesignating, the control circuit of the action of out-of-blast at least device 44.Certainly, also can carry out following such control, that is, constitute valve 47,48,57,58 and 66, when surpassing the temperature of predesignating, close these valves with magnetic valve.By various experiences, when using R-Fe-B to be alloy,, be set at 50 ℃ so preferably will above-mentionedly stop to move the temperature that begins if owing to surpass 50 ℃ then possibility that abrupt oxidization (have to follow and get angry and the situation of blast) takes place and uprise.
Also have, groove 30, the bottom of storage container 62 and near and be positioned at the main part on their top, internal diameter difference.As shown in Figure 3, the inside diameter D 1 of the bottom of groove 30 is littler than the inside diameter D 2 of main part, and is big more near main part more.If use the groove 30 of this spline structure, the flow velocity of the 1st air-flow that generates in groove 30 by the 1st stream 40 is owing to along with reducing toward the top, so the powder efficient utilization that is floated by the 1st air-flow is fallen well.The length (highly) of the bottom that internal diameter is littler than the inside diameter D 2 of main part, for example, be groove 30 all length about 20%, the minimum of a value of the inside diameter D 1 of bottom (internal diameter of base plate 62b part of living in) for example, is about 50% of D2.
Granulation powder manufacturing installation 100, also having can be to being filled in the field generator for magnetic 60 that container 62 interior rare earth alloy powders apply magnetic field.Field generator for magnetic 60 is, for example has the electromagnet of coil and deflection coil (yoke), and alternation decay magnetic field preferably can take place.Certainly, in the outside of groove 30, when using the powder of the rare earth alloy of giving remanent magnetism, can omit field generator for magnetic 60.
Then, reach (b) explanation stream condition in the groove 30 in the manufacture method of the granulation powder of embodiment of the present invention with reference to Fig. 4 (a).Fig. 4 (a) expression is from the action series of processes of the zero hour (1 circulation), and Fig. 4 (b) expression contains the series of processes (1 circulation) of separating broken operation.
The state of the air-flow in the groove 30 after container 62 that filling has a rare earth alloy powder of remanent magnetism is fixed on the assigned position of device 100 at first, is described with reference to Fig. 4 (a).
With container 62 fixing after, the flow a of the 1st air-flow a 0And the flow b of the 2nd air-flow b 0All be zero.Make the action that begins of register 42 and air-supply arrangement 44, open valve 47 and 48, in groove 30, generate the 1st air-flow a.The flow of the 1st air-flow a rises slowly, reaches the flow a of rated condition 1At this state, while powder is subjected to the cohesiveness granulation that rotary action is produced by remanent magnetism in groove 30.During this, near the central powder (comprising the particle that is in granulation process) that is present in groove 30 is floating against gravity by the 1st air-flow, and near the slow powder of the flow velocity the inwall of groove 30 falls by own wt.
The flow of keeping the 1st air-flow a (for example about 20 minutes) at the appointed time is close under certain state, opens valve 57 and 58, begins generation (the flow b of starting point of the 2nd air-flow b 1).Slowly increase the flow of the 2nd air-flow b, arrive specified flow b 2Before, (flow that reduces starting point is a to reduce the flow of the 1st air-flow a 2).That is, while exist the flow reduce by the 1st air-flow a increase the 2nd air-flow b flow during (in Fig. 4 (a), be equivalent to a 2~b 2During).Like this, by exist the 1st air-flow a and the 2nd air-flow b in groove 30 simultaneous during, granulation powder that can more effective manufacturing rare earth alloy.Its reason may not be clear, but it is generally acknowledged, owing to stop the 1st air-flow a sharp, perhaps, if the granulation powder is fallen sharp, so crumble because of bump makes the granulation pruinescence with respect to the flow of flow the 2nd air-flow b of the 1st air-flow a.In addition,, form negative pressure in the groove 30 so if after stopping the 1st air-flow a fully, begin the generation of the 2nd air-flow b, owing to be difficult to controlled pressure, so inadvisable.
As mentioned above, if Yi Bian reduce the flow of the 1st air-flow a slowly, Yi Bian increase the flow of the 2nd air-flow b, when the granulation powder falls on the base plate 62b, can not form powder bed because of bump is crumbled, thereafter, by the 2nd air-flow b compression, powder bed is by densificationization.By this densification process, the hardness of granulation powder increases.
By carrying out the circulation shown in Fig. 4 (a) repeatedly, can obtain the granulation powder of appropriate hardness.But, in the zero hour of the 2nd later circulation, it is zero a like that the flow of the 1st air-flow a does not need shown in Fig. 4 (a) 0, can be the end of a period flow a constantly of the circulation shown in Fig. 4 (a) 3
Only carry out the circulation shown in Fig. 4 (a) repeatedly, can not fully separate the broken powder bed that on base plate 62b, compresses, generate big particle.So, separate comminuted powder layer, the circulation shown in preferred practice Fig. 4 (b) for more certain.
Some b from Fig. 4 (b) 1' later operation describes.Here, the some b among Fig. 4 (b) 1' before, carry out Fig. 4 (a) mid point b 1Operation before thereafter, illustrates the situation of the operation of carrying out Fig. 4 (b).
With above-mentioned same, beginning (the flow b of the zero hour 1') generation of the 2nd air-flow b, the flow of the 2nd air-flow b arrives the flow b of rated condition 2' before, beginning (the flow a that reduces the zero hour 2') reduce the flow of the 1st air-flow a.Thereafter, shut off valve 47 and 48 is kept state (the some a among Fig. 4 (a) that stops the 1st air-flow a 3A '~a 4': α minute).If remain in operation air-supply arrangement 44 during this, the pressure rises in 47 the pipe arrangement 46 from air-supply arrangement 44 to valve so.Anti-speech, the authorized pressure that obtains being used to separating the comminuted powder layer before during, shut off valve 47 in advance.Thereafter, shut off valve 57 and 58 stops (the some b of Fig. 4 (b) 0') the 2nd air-flow b, open valve 47 and 48 simultaneously, the 1st air-flow a (the some a of Fig. 4 (b) takes place 0').At this moment, the flow a of the 1st air-flow a that generates in the groove 30 0', become flow a above the 1st specified air-flow a among Fig. 4 (a) 1(=a 2) flow, can effectively separate the comminuted powder layer.Be used to obtain the flow of the 1st air-flow a of rotary action, typical being close to like that as Fig. 4 (a) shown in keeps necessarily (a 1=a 2), but also can change.At this moment, be preferred for separating the flow of the 1st air-flow a of comminuted powder layer, more than the average discharge of the 1st air-flow a that is used to obtain rotary action.
In above-mentioned example,, generate flow a by operation valve 57 and 58 0' the 1st air-flow a, but both can regulate the flow of the 1st air-flow a by the draft capacity of control air-supply arrangement 44, also can make up with the valve operation.Also has the flow a among Fig. 4 (b) 1' and flow a 2', respectively with the flow a of Fig. 4 (a) 1And flow a 2Be all good mutually.
If the granulation powder that utilizes remanent magnetism to form greatly to a certain degree, then forms the loop circuit of magnetic, and the magnetic attracting force that works between the granulation powder dies down, and does not therefore need the circulation of separating broken usefulness shown in Fig. 4 (b).Therefore, for example, by carrying out separating in the broken process that adds up to the granulation powder that obtains stipulating for 30 times with circulation shown in the basic circulation shown in Fig. 4 (a) and Fig. 4 (b) repeatedly, preferably in 20 times initial circulation, comprise and separate broken 5 times~10 times with circulation.
Also have,, compare, (for example make an appointment with the time of half a minute) at short notice and can obtain desirable granulation powder with the situation of using the material powder that does not have remanent magnetism if use material powder with remanent magnetism.This is because if use the material powder with remanent magnetism, then utilize the magnetic cohesiveness between primary particle can easily generate the nuclear that is used to generate the granulation powder by inference.
The average grain diameter of preferred granulation powder is in the scope of 0.05mm~3.0mm.Usually, the primary particle that contains in the granulation powder is very small, and in addition, because the above high order granulation powder of three particles is also very little, the average grain diameter of second particle can be treated as the average grain diameter of representing the granulation powder in fact.Here, as the average grain diameter of granulation powder, use the average grain diameter of the second particle of trying to achieve by microscopic examination.If the average grain diameter of granulation powder is littler than 0.05mm, the then mobile effect of improving reduces, and is difficult to obtain the full and uniform formed body of density.On the other hand, if the average grain diameter of granulation powder is bigger than 3mm,, be difficult to obtain the full and uniform formed body of density then to the filling reduction of die cavity.More preferably the average grain diameter of granulation powder is in the scope of 0.1mm~2.0mm.
Then, resulting granulation powder is pressed, forms formed body.Here, only use the granulation powder to form formed body.Can use known compression molding device in compression moulding, typically can use the single shaft compression molding device, this device is used the interior powder of die cavity (nib) of bottom punch compacting tool set.The handover of prilling powder for example, in the high container of air-tightness, being full of nitrogen or making under the state that nitrogen flows through, is carried out in batches.
Filling granulation powder in the die cavity of the mould of single shaft press-forming machine.The operation of filling granulation powder in die cavity for example can be used existing placement method or utilize special public clear 59-40560 communique, spy to open flat 10-58198 communique, open the placement method that clear 63-110521 communique, spy are opened disclosed such charging box in the 2000-248301 communique in fact.
Particularly, when forming little formed body, preferably use the granulation powder of the corresponding amount of internal volume of die cavity metering and die cavity.For example, the charging box that the below is had peristome moves on the die cavity, make the granulation powder by gravity fall (whereabouts) naturally after, be supplied to the remaining granulation powder of die cavity by strickling, granulation powder that can more uniform filling ormal weight.Certainly, also can use funnel etc. to be filled in the die cavity according to the granulation powder of another kind of method metering.
In die cavity, behind the filling granulation powder, fall the upper punch of single shaft pressure setting, under the state of the peristome that has stopped up die cavity, apply directional magnetic field, when making the granulation powder crumble into primary particle, make primary particle carry out field orientation.The granulation powder of embodiment of the present invention, certain primary particle that crumbles under the more weak magnetic field of 0.1T~0.8T.But, if consider sufficient degree of orientation, be preferably about 0.5T~1.5T.The direction in magnetic field is for example vertical with pressing direction direction.Apply magnetic field on one side like this, with the pressure of for example 98MPa use bottom punch single shaft pressed powder on one side.Its result obtains relative density (formed body density/real density) and is 0.5~0.7 formed body.Also have, the direction in magnetic field also can be parallel with pressing direction as required.
Then, with the formed body that obtains, in a vacuum or in the inert gas environment, under for example about 1000 ℃~about 1180 ℃ temperature, about 1 hour to 6 hours of sintering.The granulation powder of present embodiment owing to do not contain granulating agent or only be included in the granulating agent that essence can be removed in the sintering circuit, does not need to be provided with in addition to take off the bond operation.Also have, the existing bond operation of typically taking off under the inert gas environment of about 200 ℃~800 ℃ temperature, the pressure of about 2Pa, was carried out about 3 hours~6 hours.
With the sintered body that obtains, in for example about 450 ℃~about 800 ℃ temperature, the Ageing Treatment by about 1 hour~8 hours can obtain the R-Fe-B based sintered magnet.Afterwards, in stage arbitrarily, finally finish the R-Fe-B based sintered magnet by magnetizing.
According to the present invention, as mentioned above, owing to use the granulation powder of flowability and mouldability excellence, so the variation of charging quantity is little, and can filling equably in die cavity.Therefore, the variation of the quality of the formed body that obtains by compression moulding and size is little.In addition, breach and break also few takes place in the formed body.
And the primary particle of the granulation powder of present embodiment carries out combination by surplus magnetic cohesiveness in fact, and therefore by the applying of directional magnetic field, primary particle crumbles really.Therefore, the degree of orientation of primary particle can not reduce.In addition,, the carbon of granulating agent also can be suppressed to Min., so can obtain having the sintered magnet of excellent magnetic characteristic because remaining in the reduction of the magnetic characteristic that causes in the sintered body.Like this, according to the present invention, can make high-quality R-Fe-B with high production efficiency is the alloy sintering magnet.
(embodiment)
Below, embodiments of the invention are described.
By following making R-Fe-B series alloy powder.As initiation material, use electrolytic iron, the ferroboron that contains 19.8%B, Nd and the Dy of purity more than 99.7% of purity 99.9%, modulation alloy liquation.Is the thin slice of alloy by this alloy liquation with the R-Fe-B that forms that the thin strip casting method obtains 30.0 quality %Nd, 5.0 quality %Dy, 64.0 quality %Fe, 1.0 quality %B.This thin slice is used jet mill (N for example in inert gas 2Gas, air pressure 58.8MPa) micro mist is broken, obtains the raw meal that average grain diameter is 3 μ m.
Then, the material powder that embodiment is used applies alternation decay magnetic field (magnetic field, peak is 1.0T), gives remanent magnetism.
Then, with fluidized bed comminution granulation (for example, the swing type processing equipment of only パ ウ ダ Le Co., Ltd. system) modulation granulation powder.In the manufacturing of the granulation powder of embodiment 2~3 and comparative example 2 and 3, use spy by the applicant to be willing to that the polybutene of 2001-96572 document record and isomerization alkanes are as granulating agent.Under the situation of any of embodiment and comparative example, all setting the average grain diameter that makes the granulation powder is the such condition of 0.5mm.The remanent magnetism of the granulation powder that obtains is about 0.2mT.The granulating working procedure of embodiment 1~3 is about 15 minutes, and comparative example 2 and 3 granulating working procedure need about 30 minutes.Also have, comparative example 1 is used for material powder (not carrying out applying of magnetic field) not being carried out granulation.The modulation condition table of induction of the pressing powder separately of embodiment 1~3 and comparative example 1~3 is shown in the table 1.
(table 1)
Pressing powder Granulation Remanent magnetism Granulating agent Angle of repose
Embodiment 1 Have Have 0 quality % About 47 °
Embodiment 2 Have Have 1 quality % About 46
Embodiment 3 Have Have 2 quality % About 44 °
Comparative example 1 Do not have Do not have 0 quality % About 52 °
Comparative example 2 Have Do not have 1 quality % About 49 °
Comparative example 3 Have Do not have 2 quality % About 44 °
In addition, in the table 1, merge the angle of repose of expression pressing powder separately.The powder flowbility that angle of repose is big is poor, and angle of repose small flow more is good more.Shown in comparative example 1, if material powder is not carried out granulation, angle of repose is about 52 ° of sizes, and is mobile low.In contrast, carry out the embodiment 1~3, comparative example 2 of granulation and any pressed powder of 3, angle of repose all is reduced to 50 ° of less thaies.Particularly, embodiment 1 and 2 pressed powder are compared with the pressed powder (addition of granulating agent is 1 quality %) of comparative example 2, and angle of repose is little, good fluidity.That is, utilize remanent magnetism, because compared with prior art, the interpolation of granulating agent is less, has improved flowability as can be known.Also having, is among the embodiment 3 and comparative example 3 of 2 quality % at the addition of granulating agent, can't see difference on the flowability.
With each pressing powder shown in the table 1, utilize the method for using above-mentioned charging box, be filled in the die cavity of long 20mm, wide 15mm, dark 10mm, carry out single shaft compression moulding (98MPa at right angles applies directional magnetic field (0.8T) with pressing direction).This filling procedure and compression moulding operation are all carried out for all embodiment and comparative example under the same conditions.Also have, change pressing conditions and form the different formed body of moulding volume density (green density).
Estimate the mass deviation (%) and the charging quantity deviation (σ) of the compression moulding body of embodiment 1 and comparative example 1.The mass deviation of formed body is obtained with { (biggest quality-minimum mass)/average quality (n=50) } * 100 (%).In addition, the standard deviation of the Mass Distribution of 50 formed bodys of charging quantity deviation (σ) expression.The mass deviation of the formed body of embodiment 1 is about 5%, has compared significant improvement with the mass deviation of comparative example 1 about 15%.This be because, identical down in charging quantity deviation (σ), the charging quantity deviation (σ) of comparative example 1 is about 0.33, and is relative therewith, the charging quantity deviation (σ) of embodiment 1 is 0.18, has greatly improved, and can improve liquidity by granulation.Certainly, by granulation, can improve mouldability too, the ratio that breach takes place in the formed body and break is compared also with comparative example 9 and obviously to be tailed off.The effect of these granulations also is identified in other embodiments.
With the formed body that obtains in the Ar atmosphere, 1060 ℃ of following sintering are after about 4 hours, 600 ℃ of Ageing Treatment of carrying out 1 hour, obtain sintered body.And, this sintered body is passed through magnetization under the condition of 2387kA/m, obtain sintered magnet.In embodiment and comparative example separately, sample number is taken as 50.
Fig. 5 represents the remanent magnetism Br (T) of the sintered magnet that obtains.As shown in Figure 5, with regard to the Br of embodiment 1 (bullet among Fig. 5), can not confirm and the difference of the Br essence of comparative example 1 (the white round dot among Fig. 5) to have excellent magnetic characteristic.Add the embodiment 2 of granulating agent and the Br of embodiment 3, with the Br that uses the granulating agent that adds with amount not have the comparative example 2 of material powder of remanent magnetism and a comparative example 3 much at one.When utilizing the remanent magnetism granulation, granulating agent is few as far as possible for preferred.
As mentioned above, by utilizing magnetic cohesiveness making granulation powder by the remanent magnetism generation of primary particle, with only use situation and compare with the granulation powder of the adhesion of granulating agent, even also can obtain equal above flowability owing to reduce the addition of granulating agent, so in existing equal above productivity, can make the sintered magnet that has than the magnetic characteristic that has excellence now.And, if only use the remanent magnetism of primary particle to make the granulation powder, can there be the reduction of magnetic characteristic substantially.
Then, the embodiment 4~6 that uses above-mentioned manufacturing installation 100 manufacturing granulation powder is described.Raw meal is identical with embodiment 1~3.
The internal diameter of groove 30 (D2) is 300mm, and internal volume is about 7 * 10 4Cm 3Flow a during Fig. 4 (a) reaches (b) 1=a 2=a 1'=a 2' be about 1m 3/ min, flow a 0' be about 2.0m 3/ min, flow b 2=b 3=b 2'=b 3' be about 0.75m 3/ min.The input amount of rare earth alloy material powder is about 5kg, and the temperature of nitrogen controls to about 30 ℃.
Also have, same with embodiment 2 and 3 in the manufacturing of the granulation powder of embodiment 5 and 6, use spy by the applicant to be willing to that the polybutene of 2001-96572 document record and isomerization alkanes are as granulating agent.Here, set that to make the average grain diameter of granulation powder be the such condition of 0.5mm.The remanent magnetization of the granulation powder that obtains is about 0.2mT.The granulating working procedure of embodiment 4~6 is about 15 minutes.The modulation condition and the angle of repose of the pressing powder separately of embodiment 4~6 are summarized in the table 2.
(table 2)
Pressing powder Granulation Remanent magnetism Granulating agent Angle of repose
Embodiment 4 Have Have 0 quality % About 45 °
Embodiment 5 Have Have 1 quality % About 45 °
Embodiment 6 Have Have 2 quality % About 44 °
As shown in Table 2, embodiment 4 and 5 pressing powder are compared with the pressing powder of embodiment 1 and 2, and angle of repose is littler, by using manufacturing installation 100, more can improve liquidity.By the advantage of using manufacturing installation 100 to obtain, diminish with angle of repose and to compare, the stability of granulation process (repeatability) improves.For example, if the deviation of the angle of repose of more resulting granulation powder, the angle of repose of embodiment 1 is 45 °~49 °, and is relative therewith, is 44 °~45 ° among the embodiment 4, and deviation is less.When using the prilling granulator shown in known prilling granulator shown in Figure 2, No. 3019953 communique of patent (for example Fig. 3 of this communique), utilization in groove from bottom to top airflow flowing make the operation (flow process) of flow of powder and utilize in groove from top to bottom the operation of airflow flowing compressing powder layer (densification process) to carry out as operation in addition, in contrast, use prilling granulator 100, by making the 1st air-flow that carries out flow process and carrying out the 2nd air-flow existence simultaneously in groove of densification process, can more effectively make the granulation powder of rare earth alloy as can be known.Particularly, as shown in Example 4, can obtain significant effect when not using granulating agent.
The pressing powder separately of embodiment 4~6 shown in the use table 2 forms formed body similarly to Example 1, estimates the mass deviation (%) and the charging quantity deviation (σ) of formed body.The mass deviation of the formed body of embodiment 4 is about 4%, compares with embodiment 1, has further improved.Too, the charging quantity deviation (σ) of embodiment 4 is improved as 0.16 for charging quantity deviation (σ) for this.The mass deviation (%) and the charging quantity deviation (σ) of embodiment 5 and 6 formed body, compare with embodiment 2 and 3 be equal more than.
With the formed body of embodiment 4~6 in the Ar gaseous environment, 1060 ℃ of following sintering are after about 4 hours, carry out 1 hour Ageing Treatment under 600 ℃, obtain sintered body.And, by this sintered body is magnetized, obtain sintered magnet under the condition of 2387kA/m.The sample number separately of embodiment 4~6 is 50.The remanent magnetism Br of the sintered magnet of embodiment 4~6 has the remanent magnetism Br (T) with each embodiment 1~3 same degree.If use manufacturing installation 100, owing to can make compared with prior art stable granulation powder, make the granulation powder so can use few compared with prior art granulating agent (or not using granulating agent), its result can obtain the compared with prior art excellent sintered magnet of magnetic characteristic (particularly remanent magnetism Br).
Utilizability on the industry
It is excellent and can make the manufacture method of the granulated powder of rare earth alloy of the magnet with excellent magnetic characteristic to the invention provides a kind of flowability, compressing property. Provide a kind of by using this pelletizing, can making with high production efficiency the method for high-quality rare earth alloy sintered compact.
According to the present invention, owing to can improve the flowability of rare earth alloy powder and mouldability magnetic characteristic is reduced, so can improve present magnetic characteristic take the sacrifice magnetic characteristic as the sintered magnet that is difficult to compressing shape of cost. And the shortening of granulation time, the omission of taking off the bond operation become possibility, and can improve the productivity of rare-earth sintered magnet.

Claims (6)

1. the manufacturing installation of a granulated powder of rare earth alloy is characterized in that: have:
Be provided with the groove of the platen that holds rare earth alloy powder;
Connect described groove, in described groove, can generate from the 1st stream of following the 1st air-flow that upwards flows of described platen;
Connect described groove, in described groove, can generate from the 2nd stream of the 2nd air-flow that flows downward of described platen;
Described the 1st stream and described the 2nd stream are connected in described groove independently of each other.
2. manufacturing installation as claimed in claim 1 is characterized in that: also have register and air-supply arrangement in described the 1st stream.
3. manufacturing installation as claimed in claim 1 or 2 is characterized in that: also have buffer container in described the 2nd stream.
4. manufacturing installation as claimed in claim 2 is characterized in that: have the thermometer that detects gas temperature in the described groove, and have if detected temperature surpasses the control loop that the temperature of regulation then makes the action of described air-supply arrangement stop at least.
5. manufacturing installation as claimed in claim 2 is characterized in that: in the action of described air-supply arrangement, keep malleation in the described groove.
6. manufacturing installation as claimed in claim 1 or 2 is characterized in that: also have the field generator for magnetic that can apply magnetic field to the described powder of mounting on described platen.
CNB200610078182XA 2001-11-28 2002-11-27 Apparatus for producing granulated powder of rare earth alloy Expired - Lifetime CN100413572C (en)

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DE602004022051D1 (en) * 2003-05-27 2009-08-27 Hitachi Metals Ltd METHOD AND DEVICE FOR PRODUCING GRANULAR POWDER OF A RENEERAL ALLOY AND METHOD FOR PRODUCING A SINTERED OBJECT FROM A RARE-DYE ALLOY
JP4391897B2 (en) 2004-07-01 2009-12-24 インターメタリックス株式会社 Manufacturing method and manufacturing apparatus for magnetic anisotropic rare earth sintered magnet
WO2006062039A1 (en) * 2004-12-06 2006-06-15 Sunrex Kogyo Co., Ltd. Process for producing metal product and metal product
JP4819103B2 (en) * 2008-07-28 2011-11-24 インターメタリックス株式会社 Manufacturing method and manufacturing apparatus for magnetic anisotropic rare earth sintered magnet
JP4819104B2 (en) * 2008-08-04 2011-11-24 インターメタリックス株式会社 Manufacturing method and manufacturing apparatus for magnetic anisotropic rare earth sintered magnet
CN106111998A (en) * 2016-08-15 2016-11-16 覃士杰 Stream pressure granulation device and stream pressure method of granulating

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JP3019953B2 (en) * 1990-08-16 2000-03-15 不二パウダル株式会社 Fluid compression granulator
JPH11131101A (en) * 1997-10-29 1999-05-18 Tokyo Seiko Co Ltd Method for granulation of metallic powder for powder metallurgy and granulation apparatus therefor
CN1303108A (en) * 1999-12-21 2001-07-11 住友特殊金属株式会社 Ferrous alloy permanent magnet powder and its making method

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