JP2006281356A - Manufacturing method of rare earth magnet powder compact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cut a rare earth magnet powder compact without clogging by using a wire saw without bad influence of oxygen and carbon. <P>SOLUTION: In forming raw material alloy powder containing rare earth element and cutting a formed compact 1 in a predetermined shape, cutting is performed using the wire saw 2. In cutting, high pressure gas is injected toward a wire row of the wire saw. As high pressure gas, inert gas such as nitrogen gas is used. The wire saw is a fixed abrasive grain type wire saw. After cutting using the wire saw, cut powder adhering to at least one of cut surfaces of the cut compact is removed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for cutting a rare earth magnet powder compact, and in particular, to an improvement in a cutting method using a wire saw.

  For example, an R-T-B system such as an Nd-Fe-B magnet (R is one or more rare earth elements including Y. T includes Fe as an essential element and other metal elements). In recent years, the demand has tended to increase more and more because it has advantages such as excellent magnetic properties and Nd as a main component, which is abundant in resources and relatively inexpensive. Under these circumstances, research and development for improving the magnetic properties of RTB-based sintered magnets and improvement of manufacturing methods for manufacturing high-quality rare-earth sintered magnets have been promoted in various fields. ing.

  As a method for producing a rare earth sintered magnet, powder metallurgy is known and widely used because it can be produced at low cost. In the method of manufacturing a rare earth sintered magnet by the powder metallurgy method, first, a raw material alloy ingot is first roughly pulverized and finely pulverized to obtain a raw material alloy powder having a particle size of about several μm. The raw material alloy powder obtained in this way is magnetically oriented in a static magnetic field, and molding is performed with a magnetic field applied. After molding in a magnetic field, the compact is sintered in a vacuum or in an inert gas atmosphere.

  In the production of the rare earth sintered magnet by the above-described powder metallurgy method, machining (cutting) for making the obtained rare earth sintered magnet into a predetermined shape is required. As this machining, a method is known in which a raw material alloy powder is pressed to form a block, and after the molded body is sintered, it is cut using a diamond grindstone or a cutter.

  However, when the method of cutting after sintering is employed, there are many problems in terms of manufacturing cost. For example, a large amount of swarf is generated from the sintered body by cutting, but since this swarf has already been sintered, it is extremely difficult to reuse, and depending on the processing method, the loss of the sintered body may occur. This increases the yield of the material. Since the material which comprises a rare earth sintered magnet is expensive, the fall of a material yield becomes a fatal defect with respect to cost. In addition, a sintered body of a rare earth sintered magnet is extremely hard and brittle and has a large processing load. Therefore, there is a problem that high-precision processing is difficult and a long processing time is required.

Under such circumstances, it has also been proposed to perform cutting at the stage of the molded body before sintering (see, for example, Patent Document 1 and Patent Document 2). Patent Document 1 discloses a method for producing a rare earth sintered magnet, a step of producing a magnet powder compact, and a step of processing the compact by spraying an inert gas (N ₂ gas) using a metal saw. A method of manufacturing a sintered magnet is disclosed that includes the step of sintering the compact. And the cutting time and processing cost of a rare earth sintered magnet are realized by cutting at the stage of the compact. In the invention described in Patent Document 2, a wire saw is used as the cutting means.
JP-A-53-899 JP 2003-303728 A

  The cutting with the wire saw is also known as a cutting method of a semiconductor ingot, for example, and uses a method in which a slurry containing abrasive grains is supplied (free abrasive method) or a wire to which abrasive grains are fixed. A method (fixed abrasive grain method) and the like are known.

  Among these, when considering application to a rare earth magnet powder compact, it is suitable to use a wire of a fixed abrasive system when cutting using a wire. In the free abrasive grain method, it is necessary to use a slurry, but there is a possibility that the composition of the sintered body may change due to the influence of oxygen and carbon contained in the slurry. In the case of the free abrasive grain method, an organic solvent or various oils are used as a liquid constituting the slurry. However, when the molded body is unfired and comes into contact with the organic solvent or oil at this stage, it remains and is baked. It is because it becomes an oxygen source and a carbon source at the time of condensing.

  On the other hand, when the fixed abrasive wire is used, it is not necessary to use slurry, and therefore, it is not affected by oxygen or carbon derived from the slurry. However, in the case of the fixed abrasive method, unlike the method using a rotating grindstone such as a metal saw, there is an advantage that there is less risk of ignition, but there is a problem of clogging of the wire, and there is a problem that stable cutting cannot be performed. is there. As means for solving this problem, Patent Document 2 uses a cutting fluid to eliminate clogging. However, when a cutting fluid or the like is used, the cutting fluid penetrates into the molded body and eventually oxygen contained in the cutting fluid or the like. Since the magnetic properties in the vicinity of the surface of the rare earth sintered magnet deteriorate due to the influence of carbon and carbon, it is not suitable for cutting processing to obtain a thin rare earth sintered magnet.

  As a means for eliminating the clogging, for example, as described in Japanese Patent Application Laid-Open No. 2003-113650, it is also proposed to perform cleaning by pressing a cleaning member such as a nylon brush on a wire. Since it is intended for hard and brittle materials, in order to perform sufficient cleaning, cleaning liquid cleaning must be used together, and when considering application to rare earth magnet powder compacts, the effects of oxygen and carbon are completely avoided. It ’s difficult.

  The present invention has been proposed in view of such a conventional situation, and when cutting a rare earth magnet powder compact, a rare earth magnet having excellent magnetic properties without being adversely affected by oxygen, carbon, etc. It is an object of the present invention to provide a method for producing a rare earth magnet powder compact that can be obtained. Another object of the present invention is to provide a production method capable of efficiently cutting a rare earth magnet powder compact without causing a reduction in cutting efficiency due to clogging.

  In order to achieve the above-described object, the manufacturing method of the present invention forms a raw material alloy powder containing a rare earth element, and cuts the formed body into a predetermined shape using a wire saw. And performing a step of spraying high-pressure gas toward the wire row of the wire saw and a step of removing the cutting powder adhering to at least one of the cut surfaces of the cut body subjected to the cutting process. It is characterized by.

  Since the manufacturing method of the present invention cuts the rare earth magnet powder compact before sintering, the material yield can be minimized, and the processing cost and processing time can be reduced. Further, if the wire saw is, for example, a fixed abrasive type wire saw, the influence of oxygen and carbon due to the use of the slurry can be avoided.

  In addition to these, in the manufacturing method of the present invention, in order to prevent clogging of the wire saw, a step of spraying high-pressure gas toward the wire row and removing the cutting powder adhering to the cut surface of the molded body is performed. ing. By the injection of the high-pressure gas, the cutting powder and the like adhering to the wire is effectively blown off, and the clogging is reliably eliminated. At this time, if, for example, an inert gas is used as the high-pressure gas, the molded body is not affected at all. Furthermore, since it is not necessary to use cutting oil or the like to prevent clogging, it is not affected by oxygen or carbon contained therein, and composition fluctuation does not occur after sintering. On the other hand, by cutting off the cutting powder, the cutting powder does not remain on the molded body, and the adverse effect on the molded body due to the remaining cutting powder is eliminated.

  According to the present invention, when a rare earth magnet powder compact is cut, it is possible to obtain a rare earth magnet having excellent magnetic properties after sintering without adverse effects such as oxygen and carbon. Further, since the cutting efficiency is not lowered due to clogging, the rare earth magnet powder compact can be efficiently cut. Furthermore, since the cutting powder does not adhere to the surface of the rare earth magnet powder compact, it is possible to prevent deformation of the sintered compact. The service life of the wire saw can be extended, and the processing cost can be reduced.

  Hereinafter, a method for producing a rare earth magnet powder compact to which the present invention is applied will be described in detail with reference to the drawings.

  In the production method of the present invention, the rare earth magnet powder compact to be cut is a rare earth magnet powder compact that is formed in the process of manufacturing a rare earth sintered magnet, and is a pressure-molded rare earth alloy powder. In the production of rare earth sintered magnets by powder metallurgy, rare earth alloy powders are formed into compacts and sintered to form rare earth sintered magnets. The cutting method of the present invention is a method of cutting a compact before sintering with a wire saw in the production of the rare earth sintered magnet.

  The finally produced rare earth sintered magnet has, for example, a rare earth element R, a transition metal element T, and boron as main components, but the magnet composition is not particularly limited, and can be arbitrarily selected according to the application. That's fine. For example, the rare earth element R specifically means Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu. 1 type (s) or 2 or more types can be used. Among these, it is preferable that the main component as the rare earth element R is Nd because it is abundant in resources and relatively inexpensive. Moreover, as the transition metal element T, any conventionally used transition metal element can be used. For example, one or more of Fe, Co, Ni and the like can be used. Among these, Fe and Co are preferable from the viewpoint of sinterability, and it is particularly preferable to mainly include Fe from the viewpoint of magnetic characteristics. In addition to the rare earth element R, transition metal element T, and boron B, for the purpose of improving characteristics such as coercive force, an element such as Al may be added. In addition to these elements, for example, carbon and oxygen may be contained as inevitable impurities or trace additives.

  Below, the manufacturing method of the rare earth sintered magnet by a powder metallurgy method is demonstrated, and the manufacturing method of this invention is demonstrated in it.

  As described above, rare earth sintered magnets are produced by powder metallurgy, but the manufacturing process is basically an alloying process, a coarse pulverization process, a fine pulverization process, a forming process in a magnetic field, and a compact cutting process. , A sintering process, an aging process, a machining process, and a surface treatment process. In order to prevent oxidation, most of the steps after sintering are performed in a vacuum or in an inert gas atmosphere (in a nitrogen gas atmosphere, an Ar gas atmosphere, etc.).

  In the alloying step, a raw material metal or alloy is blended according to the composition of the desired rare earth alloy powder, and melted in a vacuum or an inert gas, for example, Ar atmosphere, and cast to form an alloy. As the casting method, any method can be adopted, but the strip casting method (continuous casting method) in which a molten high-temperature liquid metal is supplied onto a rotating roll and the alloy thin plate is continuously cast is a viewpoint of productivity and the like. From the viewpoint of the form of the resulting alloy.

  As the raw material metal (alloy) used in the alloying, pure rare earth elements, rare earth alloys, pure iron, ferroboron, and alloys thereof can be used. As the alloy, a single alloy having almost the final magnet composition may be used, or a plurality of types of alloys having different compositions may be mixed so as to have the final magnet composition.

  In the coarse pulverization step, the previously cast raw alloy thin plate, ingot, or the like is pulverized until the particle size is about several hundred μm. As the pulverizing means, a stamp mill, a jaw crusher, a brown mill, or the like can be used. In order to improve the coarse pulverization property, it is effective to perform coarse pulverization after occlusion of hydrogen and embrittlement.

  After the aforementioned coarse pulverization step is completed, a lubricant is added to the coarsely pulverized raw material alloy powder. As the lubricant, for example, a fatty acid compound can be used, and in particular, by using a fatty acid or fatty acid amide having a melting point of 60 ° C. to 120 ° C. as a lubricant, good magnetic properties, in particular, a high degree of orientation. A rare earth sintered magnet having high magnetization can be obtained, and the strength of the compact can be adjusted to a predetermined value depending on the type and amount of addition. The addition amount of the lubricant is preferably about 0.03 to 0.2% by mass. If the addition amount of the lubricant is less than 0.03% by mass, a sufficient effect on the magnetic properties of the lubricant cannot be obtained, and the strength of the molded body is too high to make cutting difficult. If the addition amount is 0.2% by mass or less, the amount of residual carbon after sintering can be effectively suppressed and effective in improving the magnetic properties of the rare earth sintered magnet. If it exceeds 2% by mass, the strength of the molded product is lowered, and defects such as cracks occur during cutting.

  After the coarse pulverization step, a fine pulverization step is performed. This fine pulverization step is performed using, for example, an airflow pulverizer. The conditions for fine pulverization may be appropriately set according to the airflow pulverizer to be used, and the raw material alloy powder is finely pulverized until the average particle size becomes about 1 to 10 μm, for example, 3 to 6 μm. A jet mill or the like is suitable as the airflow pulverizer. A jet mill opens a high-pressure inert gas (for example, nitrogen gas) from a narrow nozzle to generate a high-speed gas flow, accelerates powder particles by this high-speed gas flow, and collides powder particles with each other. Or, it is a method of crushing by generating a collision with a collision plate or a container wall. Jet mills are generally categorized by action or mechanism, such as a jet mill that uses a fluidized bed or a jet mill that uses vortex flow, or a jet mill that uses a collision plate. The pulverized particle size and the like are set and controlled according to the combination and conditions of the airflow generation method and the action substance. Among these jet mills, a jet mill using a fluidized bed and a jet mill using a vortex are preferable, and a jet mill using a fluidized bed is particularly preferable. For example, the specific gravity of the raw material alloy powder and the grinding aid are greatly different, but in the fluidized bed and in the vortex, the grinding and mixing are performed well regardless of the difference in the specific gravity, and the difference in specific gravity is particularly problematic in the fluidized bed. It is because it does not become.

  After the pulverization step, the raw material alloy powder is formed in the magnetic field in the magnetic field forming step. Specifically, the raw material alloy powder obtained in the fine pulverization step is filled in a mold in which an electromagnet is arranged, and is molded in a magnetic field in a state where crystal axes are oriented by applying a magnetic field. The forming in the magnetic field may be either a vertical magnetic field forming in which the forming pressure and the magnetic field direction are parallel, or a horizontal magnetic field forming in which the forming pressure and the magnetic field direction are orthogonal to each other. Further, a pulse power source and an air-core coil can be employed as the magnetic field applying means. The forming in the magnetic field may be performed at a pressure of about 130 to 160 MPa in a magnetic field of 700 to 1300 kA / m, for example.

  Next, in the molded body cutting process, the molded body is processed into an arbitrary shape. In the case of the present invention, a wire saw is used for the cutting process, thereby performing a cutting process such as cutting to a predetermined thickness. FIG. 1 shows a state in which, for example, a rectangular parallelepiped shaped molded body 1 is cut with a wire saw 2, and the molded body 1 is predetermined by a plurality of (4 in this example) wires 2 a to 2 d of the wire saw 2. Slicing to a predetermined thickness at the cutting line.

  The wire saw 2 is composed of a wire 2a to 2d for cutting and a pair of guide rollers 3 and 4 provided with guide grooves for stable running of the wires 2a to 2d. , 4, the molded body 1 that is a workpiece is cut by the traveling of the wires 2 a to 2 d.

  Here, it is preferable that the wire saw 2 adopts a fixed abrasive type. For example, when a free abrasive grain type is adopted, it becomes necessary to supply a slurry containing abrasive grains, and oxygen and carbon such as organic solvent and oil contained in the slurry remain in the molded body, adversely affecting the properties after sintering. May cause effects. On the other hand, in the fixed abrasive method, it is not necessary to supply slurry as in the free abrasive method, and the cutting is performed by the abrasive particles fixed to the wires 2a to 2d.

  However, when the molded body 1 is cut using the fixed abrasive type wire saw 2, there is a high possibility that clogging occurs when cutting powder adheres to the wires 2 a to 2 d. When the wires 2a to 2d are clogged, efficient cutting becomes difficult, and in an extreme case, cutting is almost impossible.

  Therefore, when the wire saw 2 is cut, the clogging prevention measure is taken. Usually, as a measure for preventing clogging of the wire saw 2, for example, the clogging is avoided by removing cutting powder with a liquid, for example, by flowing cutting oil. Prevention of clogging using such cutting oil Then, oxygen and carbon of cutting oil remain in the molded body, which may adversely affect the characteristics after sintering.

  In the present invention, liquid such as cutting oil is not used to prevent clogging, and high pressure gas is sprayed toward the wire row of the wire saw 2. By spraying the high-pressure gas toward the wire row, the cutting powder adhering to each of the wires 2a to 2d can be blown off and removed to prevent clogging. In this example, nozzles 5a to 5d for high-pressure gas injection are installed facing the wires 2a to 2d, and the cutting powder adhered to the wires 2a to 2d by the high-pressure gas injected from the nozzles 5a to 5d. However, the present invention is not limited to this. For example, high-pressure gas may be jetted to the plurality of wires 2a to 2d by a slit-like nozzle or the like. Alternatively, a single nozzle may be moved or swung in the wire arrangement direction.

  In the injection of the high-pressure gas, it is preferable to use an inert gas such as nitrogen gas as the high-pressure gas. When air or the like is used as the high-pressure gas, oxygen is contained, so that the molded body 1 may be oxidized. As in the case of using the cutting oil or the like, there is a possibility of adversely affecting the characteristics after sintering. When raw material alloy powder with high activity (low oxygen concentration) is used, there is a risk of heat generation and ignition due to rapid oxidation.

  The injection pressure of the high pressure gas is preferably 1.0 to 3.0 MPa. If the spray pressure is too low, the cutting powder adhering to the wires 2a to 2d may not be sufficiently removed. Conversely, if the injection pressure is too high beyond the above range, the cutting powder removal efficiency will not change much, and it will be necessary to improve the structure of the device to increase the pressure, and to consider the influence on the surroundings. There may be a demerit in terms of capital investment. In addition, cutting powder rises and there is a risk of dust fire. In particular, when raw material alloy powder having high activity (low oxygen concentration) is used, the risk is higher.

  The high-pressure gas may be constantly injected from the nozzles 5a to 5d or may be intermittently injected. According to the former, the wires 2a to 2d can always be refreshed, and smooth cutting can be realized. In the latter case, the cutting powder firmly attached can be removed by the impact of intermittent injection, and the consumption of high-pressure gas can be minimized.

  Further, the high-pressure gas may be injected from a plurality of directions. In each wire 2a-2d, cutting powder adheres to the circumference | surroundings, and the attached cutting powder may not fully be removed only by injection of the high-pressure gas from one direction. In such a case, the cutting powder adhering to the wires 2a to 2d can be uniformly removed by injecting the high-pressure gas from a plurality of directions as described above. When high pressure gas is injected from a plurality of directions, the high pressure gas may be injected simultaneously from a plurality of directions, or may be sequentially injected from different directions with a time difference.

  When the high pressure gas injection nozzles 5a to 5d are installed and the cutting powder attached to the wires 2a to 2d is blown off by the high pressure gas injected from the nozzles 5a to 5d, the nozzles 5a to 5d are injected. It is preferable not to spray the high pressure gas directly on the molded body 1. When the high pressure gas is sprayed directly on the molded body 1, depending on the strength of the molded body 1, there is a possibility of deformation or collapse particularly when the strength of the molded body 1 is low.

  As described above, by using the wire saw 2 and cutting the molded body 1 while jetting high-pressure gas, clogging of the wires 2a to 2d can be eliminated, and cutting with high dimensional accuracy is possible. It is possible to obtain cut pieces with small variations. Moreover, since liquids, such as cutting oil, are not used for clogging prevention of the wires 2a-2d, it is not influenced by oxygen, carbon, etc. which are contained in them, and the composition fluctuation | variation of a sintered compact, etc. are in the next sintering process. Does not happen.

The molded body has been cut into a predetermined shape so far, but cutting powder may be attached to the surface of the molded body after cutting. Although the density of the compact is about 4 to 4.5 g / cm ³ , when cutting with a wire saw, the density of the cutting powder swells to about 1.8 to 2.2 g / cm ^3, so that it is about twice in the cutting groove. It is expected that cutting powder that cannot be removed only by running the wire saw remains and adheres to the molded body. Here, since it leads to deformation of the molded body, the cutting powder cannot be removed by directly injecting high pressure gas into the molded body. Therefore, for example, the cut molded body may be passed between rotating brushes and lightly rubbed on the surface of the molded body, thereby removing the cutting powder adhering to the surface. In this case, as shown in FIG. 2 (a), the cut molded body 10 is passed between brushes 11 and 12 having a rotation axis in the horizontal direction, or rotated in the vertical direction as shown in FIG. 2 (b). There is a method of passing between the brushes 13 and 14 having shafts. Alternatively, the surface of the molded body 10 is lightened to such an extent that the molded body 10 is not deformed, such as a method of using a sponge instead of a brush, or a method of passing between the elastic plates 15 (slits 15a) as shown in FIG. It is good to rub.

  After the above-described molded body cutting process, a sintering process is performed on the molded body processed into a predetermined shape in the sintering process. That is, the molded body processed into a desired shape with a high-pressure fluid as described above is sintered in a vacuum or in an inert gas atmosphere (such as in an Ar gas atmosphere).

In the sintering step, degreasing treatment is performed prior to sintering as necessary. The degreasing treatment is performed, for example, by maintaining at a temperature of 100 to 500 ° C. and a pressure of 10 ⁻¹ Torr or less for 30 minutes or more. By this treatment, fluids such as organic solvent and oil remaining in the molded body can be sufficiently removed. The holding temperature does not need to be fixed at one point in the temperature range of 100 to 500 ° C., and may be held at two or more different temperatures. For example, under the pressure of 10 ⁻¹ Torr or less, the same effect as the above-described treatment can be obtained by setting the rate of temperature increase from room temperature to 500 ° C. to 10 ° C./min or less, preferably 5 ° C./min or less. be able to.

  The sintering temperature needs to be adjusted according to various conditions such as composition, pulverization method, difference in particle size and particle size distribution, etc. For example, the sintering may be performed at 1000 to 1150 ° C. for about 1 to 5 hours. It is preferable to do.

  After the sintering, the obtained sintered body is preferably subjected to an aging treatment. This aging treatment is an important step in controlling the coercive force Hcj of the obtained rare earth magnet. For example, the aging treatment is performed in an inert gas atmosphere or in a vacuum. As the aging treatment, a two-stage aging treatment is preferable, and in the first aging treatment step, the temperature is maintained at a temperature of about 800 ° C. for 1 to 3 hours. Next, a first quenching step is provided for quenching to room temperature to 200 ° C. In the second stage aging treatment step, the temperature is maintained at about 550 ° C. for 1 to 3 hours. Next, a second quenching step for quenching to room temperature is provided. Since the coercive force Hcj is greatly increased by heat treatment at around 600 ° C., when aging treatment is performed in a single stage, it is advisable to perform aging treatment at around 600 ° C.

  After the aging step, a processing step and a surface treatment step are performed. The processing step is a step of mechanically forming into a desired shape, but in the present invention, since the formed body is processed into a shape close to the product shape by wire saw cutting, it may be omitted. Further, even when the processing step is performed, the processing amount after sintering and the load on the processing jig used for processing after sintering can be greatly reduced as compared with the conventional method. A surface treatment process is a process performed in order to suppress the oxidation of the obtained rare earth sintered magnet, for example, forms a plating film and a resin film on the surface of a rare earth sintered magnet.

  Next, specific examples of the present invention will be described based on experimental results.

Sample Preparation In this example, a rectangular NdFeB-based magnet was manufactured as follows. That is, first, a magnet raw material powder having a composition of Nd 30% by mass, Dy 4% by mass, B 1.0% by mass, Co 0.5% by mass, and the balance Fe was formed and molded in a magnetic field to obtain a compact. After cutting this, it was sintered to form a rare earth sintered magnet, and its surface was coated with an epoxy resin to obtain a permanent magnet sample.

Example The molded body was cut using a fixed abrasive grain type wire saw. Moreover, when cutting with a wire saw, high pressure nitrogen gas was sprayed on each wire to prevent clogging. Further, the molded body after cutting was brushed to remove the cutting powder adhering to the surface.

Comparative Example 1
The molded body was cut using a fixed abrasive grain type wire saw. Also, no clogging prevention measures were taken when cutting with a wire saw. The cutting powder was not removed by brushing on the molded body after cutting.

Comparative Example 2
The molded body was cut using a fixed abrasive grain type wire saw. Moreover, when cutting with a wire saw, cutting oil was poured into each wire to prevent clogging. About the molded object after a cutting | disconnection, the removal of the cutting powder by brushing was not performed.

Comparative Example 3
The molded body was cut using a loose abrasive wire saw. About the molded object after a cutting | disconnection, the removal of the cutting powder by brushing was not performed.

Comparative Example 4
The molded body was cut using a fixed abrasive grain type wire saw. Moreover, when cutting with a wire saw, high pressure nitrogen gas was sprayed on each wire to prevent clogging. However, in this example, the cutting powder was not removed by brushing the formed body after cutting.

Comparative Example 5
The molded body was cut using a fixed abrasive grain type wire saw. Also, no clogging prevention measures were taken when cutting with a wire saw. The molded body after cutting was brushed to remove cutting powder adhering to the surface.

  With respect to these Examples and Comparative Examples, the dimensional accuracy of the cut molded body pieces, the magnetic characteristics when the molded body cut pieces were sintered to form a rare earth sintered magnet, and the deformation amount of the sintered body were examined. The results are shown in Table 1.

  As is apparent from Table 1, in Comparative Example 1 in which no clogging prevention measure was taken, the cutting efficiency was lowered due to the occurrence of clogging, and the dimensional accuracy of the molded product cut piece was also low. On the other hand, in Comparative Example 2 in which clogging was prevented with cutting oil and Comparative Example 3 in which a loose abrasive wire saw was used, a decrease in magnetic properties was observed in the sintered rare earth sintered magnet. Further, in Comparative Example 4 in which the molded body was not brushed, the amount of deformation of the sintered body was large, and in Comparative Example 5 in which no gas was blown, a reduction in dimensional accuracy was observed. On the other hand, in the embodiment to which the present invention is applied, it is possible to obtain a molded piece with high dimensional accuracy without clogging, and the sintered rare earth magnet has excellent magnetic properties and little deformation. there were.

It is a schematic perspective view which shows the example of a cutting | disconnection of the molded object by a wire saw. It is a schematic diagram which shows the example of the removal method of the cutting powder adhering to a molded object, (a) is the method of passing between the brushes which have a rotating shaft in a horizontal direction, (b) is between brushes which have a rotating shaft in a vertical direction. (C) shows the method of passing the slit of an elastic board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 molded object, 2 wire saw, 2a-2d wire, 3,4 guide roller, 5a-5d high pressure gas injection nozzle, 10 molded object (after cutting), 11, 12, 13, 14 brush, 15 elastic board, 15a slit

Claims (9)

When forming a raw material alloy powder containing rare earth elements and cutting the formed compact into a predetermined shape,
While performing the cutting process using a wire saw, the step of injecting high-pressure gas toward the wire row of the wire saw, and the cutting attached to at least one of the cut surfaces of the molded body subjected to the cutting process A method for producing a rare earth magnet powder compact, comprising: a step of removing powder.   2. The method for producing a rare earth magnet powder compact according to claim 1, wherein the wire saw is a fixed abrasive wire saw.   3. The method for producing a rare earth magnet powder compact according to claim 1, wherein the high-pressure gas is an inert high-pressure gas.   4. The method for producing a rare earth magnet powder compact according to claim 3, wherein the inert gas is nitrogen gas.   The method for producing a rare earth magnet powder compact according to any one of claims 1 to 4, wherein the high-pressure gas is constantly injected.   The method for producing a rare earth magnet powder compact according to any one of claims 1 to 4, wherein the high-pressure gas is intermittently injected.   The method for producing a rare earth magnet powder compact according to any one of claims 1 to 6, wherein the high-pressure gas is injected from a plurality of directions.   8. The method for producing a rare earth magnet powder compact according to claim 7, wherein when the high pressure gas is injected from a plurality of directions, the high pressure gas is simultaneously injected from the plurality of directions.   8. The method for producing a rare earth magnet powder compact according to claim 7, wherein when the high-pressure gas is injected from a plurality of directions, the high-pressure gas is sequentially injected from different directions with a time difference.

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