JP2006041041A - Method for manufacturing sintered magnet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a sintered magnet while effectively removing cutting powder produced by cutting a molding. <P>SOLUTION: The method for manufacturing the sintered magnet includes a stage of pressurizing and compacting powder for the sintered magnet charged in a cavity in an orientating magnetic field; a stage of cutting the pressure-compacted body GB obtained by the pressure compacting; a cutting powder removing stage including a step of vibrating cutting powder sticking on the compact body GB by applying an AC magnetic field to the cut compact body GB from an air-core coil 32, and a step of blowing nitrogen gas to the vibrated cutting powder from a nitrogen gas supply nozzle 34; and a stage of sintering the compact body GB after the cutting powder removing stage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a sintered magnet, and more particularly to a method for manufacturing a sintered magnet that employs a step of sintering after cutting a molded body obtained by pressing metal powder in a magnetic field. .

  There are several methods for processing a rare earth sintered magnet into a predetermined shape and size. One of them is a method of producing a sintered body that approximates a predetermined shape and size, and finishing the surface by processing such as grinding. In addition, there is a method in which a block-shaped sintered body is prepared, and the block-shaped sintered body is cut using a diamond grindstone and a cutter to obtain a plurality of sintered bodies having a predetermined shape. Even in this case, processing such as grinding may be performed on the cut surface or the non-cut surface after the cutting processing.

Since the sintered body has a high hardness, attempts have been made to cut it at the stage of a green body that is easy to process. For example, in Patent Document 1 (Japanese Patent Laid-Open No. 53-899), a molded body in the process of manufacturing an Sm—Co based sintered magnet is made of a cemented carbide in a nitrogen gas atmosphere to prevent oxidation. Proposals for cutting with a blade saw have been made. Further, in Patent Document 2 (Japanese Patent Laid-Open No. 8-181028), for the purpose of preventing oxidation, clogging due to grinding stone chips, and continuous discharge of chips, the formed body and a rotating processing blade are made of mineral oil or the like. There has been proposed a method of cutting while immersed in a processing liquid.
However, according to the processing method using a blade saw, there is a problem that the cutting cost of the molded body is large and the product yield is poor. In addition, a degreasing process that removes mineral oil and the like from the molded body after cutting and before sintering is indispensable. When degreasing is insufficient, carbon contained in the oil functions as an impurity during the sintering process, resulting in magnet characteristics. It will deteriorate.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2003-303728) discloses a method for solving the above problems, a step of producing a molded body of magnet powder, a step of processing a molded body using a wire saw, and a molded body. A method of manufacturing a sintered magnet including a step of sintering is disclosed. According to Patent Document 3, since the molded body in a relatively soft state before sintering is processed with a thin wire saw, the processing load is reduced, and heat generation of the molded body can be suppressed. For this reason, even when a magnet is manufactured using magnet powder that is easily oxidized, the time for processing can be greatly shortened and the manufacturing cost can be greatly reduced without degrading the final magnet characteristics. Moreover, since the cutting allowance can be reduced compared with the case of using a conventional rotary blade, the yield of the material is improved.

JP-A-53-899 JP-A-8-181028 JP 2003-303728 A

Although the cutting with the wire saw disclosed in Patent Document 3 has the excellent effects as described above, it has been pointed out that the cutting powder remains and adheres to the cut surface. The cutting powder remaining on the cut surface causes the compacts (sintered bodies) to fuse together when sintering is performed in a state where the compacts are in contact with each other. Therefore, Patent Document 3 proposes that the wire saw is moved relative to the cut surface once formed. Patent Document 3 proposes supplying cutting fluid to a wire saw. However, when the wire saw is thin, for example, when the wire saw is as low as 0.2 to 0.5 mm, it has been found that the above-mentioned proposal has a small effect of removing the cutting powder.
Then, an object of this invention is to provide the method of manufacturing a sintered magnet, removing effectively the cutting powder produced by the cutting | disconnection of a molded object.

  In the process in which the cut molded body is exposed to an alternating magnetic field, the present inventors have made it easy to remove the cutting powder adhering to the molded body and remove the gas in a state where the removal is easy. It was found that cutting powder can be efficiently removed by spraying. The present invention is based on this finding, the step of pressure-molding the sintered magnet powder filled in the cavity in an orientation magnetic field, the step of cutting the molded body obtained by pressure molding, and the cutting A cutting powder removing process including a step of vibrating the cutting powder attached to the molded body by applying an alternating magnetic field to the molded body, a step of blowing an inert gas to the vibrating cutting powder, and a cutting powder removal And a step of sintering the molded body that has undergone the step. The method for producing a sintered magnet of the present invention is particularly effective when applied to a method for producing a rare earth sintered magnet using a powder for a rare earth sintered magnet. The AC magnetic field is preferably set to a frequency of 25 to 120 Hz.

  In the method for producing a sintered magnet according to the present invention, after the anti-fusing agent is attached to a predetermined surface of the molded body that has undergone the cutting powder removing step, the molded body is sintered in a state of being overlapped with the anti-fusing agent. It is desirable to improve manufacturing efficiency.

In the present invention, the step of cutting the molded body includes a step (a) of cutting the molded body by a predetermined amount while pressing a cutting means traveling in a predetermined direction against the molded body, and cutting to a predetermined position in the direction of releasing the press. It is desirable to use a cutting method that repeats the step (b) of relatively moving the means backward.
Further, in the present invention, the step of cutting the molded body includes the step (c) of pressing the first cutting means that travels in a predetermined direction against the molded body, and the first cutting means based on the molded body. It is desirable to include a step (d) of scraping cutting powder generated by cutting by moving the second cutting means disposed rearward in the cutting completion region.
According to this cutting method, it is possible to reduce the amount of cutting powder remaining on the formed body after the end of cutting.

  As described above, according to the present invention, the cutting powder generated by cutting the molded body can be effectively removed. Furthermore, according to this invention, the quantity of the cutting powder which remains in a molded object by cutting | disconnection of a molded object can be reduced.

Hereinafter, the present invention will be described in detail based on embodiments.
Rare earth sintered magnets are usually produced through the basic steps of producing a raw material alloy, pulverizing the raw material alloy, forming the pulverized powder in a magnetic field, and sintering the compact. The present invention is based on the premise that the molded body is cut to a predetermined size before sintering, and a measure for removing defects caused by cutting powder generated by cutting the molded body between this cutting and sintering. Is to provide. One of the measures is a method of removing cutting powder remaining on the formed body after cutting. Moreover, the cutting method which can reduce the quantity which cutting powder remains in the molded object cut | disconnected with the other measures is provided. Hereinafter, the manufacturing method will be described in the order of the processes including the above measures, taking an Nd—Fe—B magnet as an example of the rare earth sintered magnet.

  The raw material alloy can be produced by a strip casting method or other known melting methods in a vacuum or an inert gas, preferably in an Ar atmosphere. In the strip casting method, a molten metal obtained by melting a raw metal in a non-oxidizing atmosphere such as an Ar gas atmosphere is jetted onto the surface of a rotating roll. The melt rapidly cooled by the roll is rapidly solidified into a thin plate or a thin piece (scale). This rapidly solidified alloy has a homogeneous structure with a crystal grain size of 1 to 50 μm. The raw material alloy can be obtained not only by the strip casting method but also by a melting method such as high frequency induction melting.

  The raw material alloy is subjected to a grinding process. The pulverization process includes a coarse pulverization process and a fine pulverization process. First, the raw material alloy is coarsely pulverized until the particle size becomes about several hundred μm. The coarse pulverization is desirably performed in an inert gas atmosphere using a stamp mill, a jaw crusher, a brown mill or the like. Prior to coarse pulverization, it is effective to perform pulverization by allowing hydrogen to be stored in the raw material alloy and then releasing it. This hydrogen pulverization can be regarded as coarse pulverization, and mechanical coarse pulverization can be omitted.

After the coarse pulverization process, the process proceeds to the fine pulverization process. A jet mill is mainly used for the fine pulverization, and the coarsely pulverized powder having a particle size of about several hundreds of μm has an average particle size of 2.5 to 6 μm, preferably 3 to 5 μm. The jet mill releases a high-pressure inert gas from a narrow nozzle to generate a high-speed gas flow, accelerates the coarsely pulverized powder with this high-speed gas flow, collides with the coarsely pulverized powder, and collides with the target or the container wall. It is a method of generating a collision and crushing.
By adding about 0.01 to 0.3 wt% of a lubricant such as zinc stearate before and after pulverization or both, fine powder with high orientation can be obtained at the time of molding in the next magnetic field.

The fine powder obtained as described above is subjected to molding in a magnetic field. The forming in the magnetic field may be performed at a pressure of about 50 to 200 MPa (0.5 to ² t / cm ² ) in a magnetic field of 800 to 1360 kA / m (10 to 17 kOe).

  The molded body obtained above is cut. In the present invention, it is recommended to employ cutting methods according to first to third embodiments described below. These cutting methods can reduce the amount of cutting powder remaining in the molded body after cutting. However, the present invention is not limited to the following cutting method.

<First form>
First, a cutting method in which the traveling wire saw itself has a cutting powder removing function will be described.
As shown in FIG. 1, the cutting apparatus 10 includes a wire saw 1 that cuts an object to be cut. The wire saw 1 is stretched around a frame 2 having a U-shaped cross section. The frame 2 is fixed to a pair of pulleys 3 and 4 that are rotatably supported by a column, for example. The pulleys 3 and 4 can be rotated synchronously by the wound timing belt 5. The timing belt 5 can also be a chain belt. A pulley 6 having a diameter larger than that of the pulley 4 is arranged coaxially with the pulley 4. A timing belt 7 is wound around the pulley 6, and the timing belt 7 is rotationally driven by a motor 8. However, the pulley 4 does not need to have a larger diameter than the pulley 6. Further, the timing belt 7 may be a chain belt or a normal belt.

  Now, in the cutting device 10 having the above configuration, when the motor 8 is driven, the pulley 6 rotates in the arrow direction, and the pulleys 3 and 4 also rotate in the arrow direction along with this rotation. As the pulleys 3 and 4 rotate, the frame 2 also moves. This motion is equivalent to the motion by the parallel link mechanism having the rotation centers c1 and c2 of the pulleys 3 and 4 and the pulleys 3 and 4 and the fixing points c3 and c4 of the frame 2 as nodes. The wire saw 1 is disposed at the position of the connecting rod of this parallel link mechanism. 1 to 4 sequentially show the process of this movement. FIG. 2 shows a state where the pulleys 3 and 4 are rotated by 90 ° from the state of FIG. 1, and FIG. 2 shows that the pulleys 3 and 4 are rotated by 90 ° from the state of FIG. 3 shows a state where the pulleys 3 and 4 are rotated by 90 ° from the state shown in FIG.

  As can be understood from FIGS. 1 to 4, the wire saw 1 travels in the arrow direction (vertical direction) and reciprocates in the horizontal direction. More specifically, assuming that the state of FIG. 1 is an initial state, the wire saw 1 moves from the initial state (movement start end) by a predetermined distance L in the left direction in the figure (movement end), and then in the right direction in the figure. It moves by a predetermined distance L and returns to the movement start end. The predetermined distance L is L = 2r, where r is the distance from the rotation center c1 (c2) of the pulley 3 (pulley 4) to the pulley 3 (pulley 4) and the fixed portion c3 (c4) of the frame 2.

  FIG. 5 shows a movement locus of a predetermined fixed point (indicated by a black circle) on the wire saw 1 when the cutting device 10 performs the operations of FIGS. In FIG. 5, the fixed point on the wire saw 1 moves on a virtual circle with a radius r. At this time, the wire saw 1 reciprocates in the vertical direction. This vertical reciprocation corresponds to the bidirectional traveling of the wire saw 1. The wire saw 1 reciprocates between the movement start end on the right side in the figure and the movement end point on the left side in the figure.

  Furthermore, the wire saw 1 exhibits a function of cutting the molded body GB mainly by moving from the position (4) to the position (1). Thereafter, the wire saw 1 moves from the position (1) to the position (2), and further moves to the position (3). The movement of the wire saw 1 scrapes off the cutting powder from the cut surface. Thus, the wire saw 1 has both the function of cutting the molded body GB and the function of discharging cutting powder. By the way, the wire saw 1 has two velocity components in the vertical direction and the horizontal direction in the process of movement. By having two velocity components in this way, cutting and movement can be continuously performed by a single movement called a circular movement.

<Second form>
Although the 1st form gave the cutting function and the cutting powder discharge function to the wire saw 1 using the parallel link mechanism, the example which gives the cutting function and the cutting powder discharge function by a mechanism different from the 1st form in the 2nd form. Show.
FIG. 6 is a diagram for explaining a wire saw cutting method according to the second embodiment.
As shown in FIG. 6, a plurality of wire saws 11 are stretched on a frame 12 having a U-shaped cross section. The frame 12 can reciprocate in the vertical direction by an actuator (not shown). The frame 12 can be reciprocated in the horizontal direction by an actuator (not shown). The formed body GB that is a workpiece can be moved forward and backward with respect to the wire saw 11 while being held by a chuck (not shown). The shaped body GB is cut by pressing the wire saw 11 against the shaped body GB while reciprocating the frame 12 in the vertical direction.

In the second embodiment, when the wire saw 11 is cut into the formed body GB by a predetermined amount, the wire saw 11 is moved backward by a predetermined distance from the cutting position of the formed body GB. After retreating, cut a predetermined amount again. In the second embodiment, the molded body GB is cut by repeating the above operation, and FIG. 7 shows the relationship between the elapsed time from the start of cutting and the cutting amount of the wire saw 11 into the molded body GB. As is clear from FIG. 7, the second embodiment repeats the predetermined amount of cutting, the wire saw 11 retracting, the predetermined amount of cutting, the wire saw 11 retracting, the predetermined amount of cutting, etc., but when the wire saw 11 is retracted, scraping of cutting powder Is done effectively. In the second embodiment, when performing the cutting, the wire saw 11 is pressed against the compact GB for a predetermined time, and when the predetermined time has elapsed, the wire saw 11 is moved backward. After retreating by a predetermined amount, the wire saw 11 is advanced for cutting and pressed against the cut portion of the molded body GB. In the second form, the wire saw 11 is reciprocating in the vertical direction even when it is retracted, that is, is traveling, so that the cutting powder removal effect is high.
In the first embodiment, the time for pressing the wire saw 1 against the molded body cannot be ensured for a long time because the rotary motion is used, whereas the second embodiment presses the wire saw 11 against the molded body GB. In other words, there is an advantage that the cutting time can be set arbitrarily.

<Third form>
In the first embodiment and the second embodiment, the wire saw 1 (11) that performs the cutting function is also provided with a cutting powder removing function. However, the third embodiment has a cutting powder removing function in addition to the wire saw that performs the cutting function. An example of separately preparing a wire saw will be described.
FIG. 8 is a diagram for explaining a wire saw cutting method according to the third embodiment.
As shown in FIG. 8, a plurality of wire saws 21 are stretched on a frame 22 having a U-shaped cross section. This wire saw 21 is a wire saw that performs a cutting function. In the cutting device according to the third embodiment, a plurality of wire saws 23 are further stretched on the frame 22. The wire saw 23 is disposed behind the wire saw 21 with reference to the molded body GB that is a workpiece. Further, the wire saw 23 may be disposed in parallel with the wire saw 21, but it is desirable that the wire saw 23 be disposed at a predetermined angle with the wire saw 21, as shown in FIG. As the wire saw 21 and the wire saw 23, it is possible to use ones having different wire diameters or abrasive grain sizes described later.

  The frame 22 can reciprocate in the vertical direction by an actuator (not shown). The frame 22 can be reciprocated in the horizontal direction by an actuator (not shown). The molded body GB that is a workpiece can be moved forward and backward with respect to the wire saw 21 while being held by a chuck (not shown). The shaped body GB is cut by pressing the wire saw 21 against the shaped body GB while reciprocating the frame 22 in the vertical direction.

  A 3rd form removes cutting powder with the wire saw 23, cutting the molded object GB with the wire saw 21. FIG. This will be described with reference to FIG. As shown in FIG. 9, the wire saw 21 reciprocates in the vertical direction to cut the formed body GB. The wire saw 23 reciprocates in synchronization with the reciprocating motion of the wire saw 21. Since the wire saw 23 forms a predetermined angle with the wire saw 21, the cutting powder remaining in the cutting completion region can be scraped out from the cutting completion region by reciprocating. In order to cut the molded body GB, the number of cuts by the wire saw 21 is increased. In the process, the wire saw 22 scrapes off the cutting powder.

  Although the 3rd form provided the wire saw 23 as a wire saw which exhibits a cutting powder removal function, providing the wire saw 24 which exhibits a cutting powder removal function further as shown in FIG. 10 improves the cutting powder removal effect. Can do.

Although three forms of the cutting method according to the present invention have been described above, items common to the three forms will be described below.
The wire saw used in the present invention is obtained by fixing abrasive grains such as diamond on the surface of a wire saw core wire.
The wire saw core wire is made of a material having high tensile strength, such as a hard steel wire (piano wire), a Ni—Cr-based or Fe—Ni-based alloy, a refractory metal such as W or Mo. Not only metal but also a resinous wire saw core can be used.
On the other hand, if the diameter of the wire saw core wire is too large, the cutting amount of the workpiece is increased and the material yield is lowered. On the other hand, if the wire saw wire is too thin, the wire saw core wire may be cut by a load during cutting. For this reason, the outer diameter of the wire saw core wire used in the present invention is preferably 0.1 to 0.6 mm, and more preferably 0.15 to 0.5 mm.
As the abrasive grains fixed to the wire saw core wire, it is preferable to use a high hardness material such as diamond, SiC or Al ₂ O ₃ , and the particle diameter is typically 10 to 500 μm, desirably 20 to 300 μm. .
The abrasive grains are preferably fixed to the surface of the wire saw core with a metal bond such as Cu or Ni, or a resin such as phenol resin, epoxy resin or polyimide resin.

  The traveling speed of the wire saw greatly affects the machining load. In order to keep the processing load within a practically appropriate range, this speed is preferably set to, for example, 10 to 100 m / min, and more preferably set to 20 to 50 m / min. Further, the cutting speed by the wire saw is preferably set to 10 to 400 mm / min, and more preferably set to 50 to 200 mm / min. Although the wire saw has been described above as an example, the present invention can also be applied to a band saw having a plate thickness of about 1 mm or less.

  Now, even if it is a molded object cut | disconnected by the above cutting method, the cutting powder inevitably remains (attaches) to the molded object. In the present invention, an alternating magnetic field is applied to the cut compact. The cutting powder adhering to the compact is vibrated in an alternating magnetic field and is easily removed. The exciting current of this alternating magnetic field may be in the range of 25 to 120 Hz. When the frequency is lower than 25 Hz, the vibration of the cutting powder is insufficient and it is difficult to leave the molded body. Moreover, when it becomes 120 Hz or more, the vibration of the cutting powder does not follow this frequency.

  The cutting powder that has been vibrated by application of an alternating magnetic field may fall off the molded body, but there are also those that are merely vibrating on the molded body. Therefore, in order to remove the cutting powder from the molded body, in the present invention, gas is blown against the molded body. The gas to be sprayed is an inert gas such as nitrogen gas because the molded body contains an element that is easily oxidized. By blowing the gas, the cutting powder vibrating on the molded body can be easily removed.

The molded body that has been subjected to the above cutting powder removal treatment is then sintered.
When the molded body has a thin plate shape, the main surface of the molded body is sintered in the vertical direction, that is, in a state where the molded body is erected, and the main surface of the molded body is horizontal, that is, the molded body is There is a method of sintering in the laid state. The present invention may be sintered in any state, but in order to prevent deformation after sintering, it is desirable to sinter the molded body in a laid state. In this case, it is advantageous for improving the production efficiency that a plurality of molded bodies are stacked and sintered. Here, if cutting powder adheres to the main surface of the molded body, it may melt during the sintering process, and the adjacent molded bodies may be fused. As described above, since the present invention performs a process of reducing the cutting powder adhering to the compact, the possibility of fusion between the compacts is extremely low. However, it goes without saying that it is desirable to interpose an anti-fusing agent between the molded bodies when the molded bodies are stacked and sintered. As the anti-fusing agent, refractory metal powders such as W, Mo and Fe, and ceramic powders such as Y ₂ O ₃ and Al ₂ O ₃ can be used.

Sintering is performed in a vacuum or an inert gas atmosphere. Although it is necessary to adjust sintering temperature by various conditions, such as a composition, a grinding | pulverization method, the difference of an average particle diameter, and a particle size distribution, what is necessary is just to sinter at 1000-1100 degreeC for about 1 to 10 hours.
After sintering, the obtained sintered body can be subjected to an aging treatment. This step is an important step for controlling the coercive force. In the case where the aging treatment is performed in two stages, holding for a predetermined time at around 800 ° C. and around 600 ° C. is effective. In addition, since the coercive force is greatly increased by the heat treatment near 600 ° C., the aging treatment near 600 ° C. is preferably performed when the aging treatment is performed in one stage.

  FIG. 11 shows a system configuration example for performing the cutting powder removing process on the cut molded body GB. The cutting powder removing system 30 includes a mesh belt 31 that conveys the compact GB. An air core coil 32 is disposed below a predetermined position of the conveyance path formed by the mesh belt 31. The air-core coil 32 generates an AC magnetic field on the mesh belt 31 when an AC current is supplied from a power source (not shown). A cutting powder collection tray 33 is disposed below the air core coil 32.

A nitrogen gas supply nozzle 34 is disposed above the air-core coil 32 with the mesh belt 31 interposed therebetween. The nitrogen gas supply nozzle 34 blows nitrogen gas supplied from a gas supply source (not shown) toward the mesh belt 31.
An anti-fusing agent storage container 35 is disposed on the downstream side of the mesh belt 31 with respect to the nitrogen gas supply nozzle 34. The anti-fusing agent container 35 contains the anti-fusing agent such as W described above, and the anti-fusing agent can be appropriately dropped from the bottom floor toward the mesh belt 31. Yes. For example, a vibrating screen can be used.

  In the cutting powder removal system 30 having the above configuration, the compact GB arrives between the air-core coil 32 and the nitrogen gas supply nozzle 34 in the process of being conveyed on the mesh belt 31. The state at this time is shown in FIG. The compact GB is present in the alternating magnetic field generated from the air-core coil 32. The cutting powder adhering to the compact GB is magnetized because it has been molded in a magnetic field. Therefore, this cutting powder performs an inversion operation by alternately receiving an alternating magnetic field, that is, a positive and negative magnetic field. By this reversal operation, the cutting powder vibrates on the compact GB. The cutting powder dropped from the compact GB by this vibration passes through the hollow portions of the mesh belt 31 and the air core coil 32 and falls onto the cutting powder collection tray 33.

  When the molded body GB is located in the alternating magnetic field generated by the air-core coil 32, the nitrogen gas supplied from the nitrogen gas supply nozzle 34 is blown onto the molded body GB. The cutting powder that has not fallen off from the compact GB due to vibration is also scattered from the compact GB by blowing nitrogen gas.

  The molded body GB that has been subjected to the above processing is placed on the mesh belt 31 and moves below the anti-fusing agent storage container 35. The anti-fusing agent falling from the anti-fusing agent storage container 35 adheres to the surface of the molded body GB, and then the molded body GB is further transported by the mesh belt 31 and the series of processes is completed. The compact GB having the anti-fusing agent attached to the surface is subjected to sintering in a state of being stacked via the anti-fusing agent. The spraying of the anti-fusing agent on the molded body GB is not limited to the mesh belt 31, and the molded bodies GB may be stacked while being sprayed in the sintering container.

As described above, according to the present invention, an AC magnetic field is applied to the compact GB, the cutting powder adhering to the compact GB is vibrated, and an inert gas is blown to cut the compact GB from the compact GB. It is possible to effectively remove the powder.
Moreover, if the cutting method which can reduce the quantity of the remaining cutting powder is employ | adopted for this invention, it will become possible to reduce the cutting powder finally remaining on the molded object GB as much as possible.

Hereinafter, the present invention will be described based on specific examples.
The alloy was dissolved so as to have a composition of 31 wt% Nd-1 wt% Dy-1 wt% B-0.5 wt% Co-balance Fe, and coarse pulverization by hydrogen treatment and fine pulverization by a jet mill were performed to obtain an average particle size of 4 μm. A fine powder was obtained. This fine powder was molded in a magnetic field at a pressure of 150 MPa in a magnetic field of 1.5 T to obtain a molded body of 45 mm × 35 mm × 60 mm (magnetic field orientation direction). This molded body was cut by different methods using a wire saw.

<Example>
The said molded object was cut | disconnected using the cutting device 10 shown in FIG. The wire saw used has an outer diameter of 0.25 mm to which diamond abrasive grains having an average particle diameter of 100 μm are fixed.
The compact was fed into the wire saw at a speed of 100 mm / min, and the rotational frequency of the wire saw was 20 Hz. As a result, the cutting allowance of the molded body was 0.32 mm.
The cut molded body was processed by a cutting powder removing system 30 shown in FIG. The current supplied to the air core coil 32 is 50 Hz. When the compact GB reached on the air-core coil 32, the cutting powder adhering to the compact GB vibrated and separated from the surface of the compact GB. While the cutting powder vibrates, nitrogen gas is supplied from the nitrogen gas supply nozzle 34 with such a strength that the molded body GB does not break against the cut surface of the cut molded body GB, thereby forcing the cutting powder. Removed. The weight of the removed cutting powder was 2.9 g.
W powder is adhered as an anti-fusing agent to the main surface of the molded body from which the cutting powder has been removed, and the same molded body is overlaid through the surface to which the W powder is adhered, and in that state in vacuum, 1100 ° C. For 4 hours. After sintering, the two sintered bodies could be easily separated.

<Comparative example>
A wire saw having an outer diameter of 0.25 mm to which diamond abrasive grains were fixed was run in both directions at a maximum speed of 150 m / min, and the compact was cut into the wire saw at a speed of 100 mm / min.
After cutting, the molded body was moved once again in the direction opposite to the cutting direction along the cut surface. At this time, the traveling direction of the wire saw is the same as that at the time of cutting. An AC magnetic field was applied to the cut molded body in the same manner as in the example, but the cutting powder did not vibrate because it was firmly attached to the molded body.
Thereafter, the cutting gas was forcibly removed by supplying nitrogen gas from the nitrogen gas supply nozzle 34 with such a strength that the molded body did not break on the cut surface of the cut molded body, but the weight of the removed powder Was 0.4 g, and the attached cutting powder was hardly removed.
W powder is adhered as an anti-fusing agent to the main surface of the above molded body, and the same molded body is superimposed through the surface to which this W powder is adhered, and in this state, the powder is baked at 1100 ° C. for 4 hours. I concluded. After sintering, the two sintered bodies were fused and could not be separated.

It is a figure explaining the wire saw cutting method by a 1st form. It is another figure explaining the wire saw cutting method by a 1st form. It is another figure explaining the wire saw cutting method by a 1st form. It is another figure explaining the wire saw cutting method by a 1st form. It is a figure explaining operation | movement of the wire saw by a 1st form. It is a figure explaining the wire saw cutting method by a 2nd form. In a 2nd form, it is a graph which shows the relationship between the elapsed time from the start of cutting, and the cutting amount to the molding of a wire saw. It is a figure explaining the wire saw cutting method by a 3rd form. It is a figure explaining operation | movement of the wire saw in the wire saw cutting method by a 3rd form. It is a figure explaining the other wire saw cutting method by a 3rd form. It is a figure which shows the structure of a cutting powder removal system. It is a figure which shows the principal part of a cutting powder removal system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 11, 21, 23, 24 ... Wire saw, 2, 12, 22 ... Frame, 3, 4, 6 ... Pulley, 5, 7 ... Timing belt, 8 ... Motor, 10 ... Cutting device, 30 ... Cutting powder removal system 31 ... Mesh belt, 32 ... Air-core coil, 33 ... Cutting powder collection tray, 34 ... Nitrogen gas supply nozzle, 35 ... Anti-fusing agent storage container, GB ... Molded body

Claims (6)

Pressure-molding the sintered magnet powder filled in the cavity in an orientation magnetic field;
Cutting the molded body obtained by the pressure molding;
A cutting powder removing process including a step of oscillating cutting powder attached to the molded body by applying an alternating magnetic field to the cut molded body, and a step of blowing an inert gas to the oscillating cutting powder; ,
A step of sintering the molded body that has undergone the cutting powder removing step;
A method for producing a sintered magnet, comprising:   2. The sintered body is sintered in a state where the molding is overlapped with the anti-fusing agent after adhering an anti-fusion agent to a predetermined surface of the molding after the cutting powder removing step. The manufacturing method of the sintered magnet of description. The step of cutting the molded body includes:
Cutting the molded body by a predetermined amount while pressing a cutting means traveling in a predetermined direction against the molded body;
Retreating the cutting means relatively to a predetermined position in the direction of releasing the pressing (b);
The method for producing a sintered magnet according to claim 1, wherein the method is repeated. The step of cutting the molded body includes:
(C) performing cutting by pressing the first cutting means traveling in a predetermined direction against the molded body;
Scraping off the cutting powder generated by cutting by moving the second cutting means disposed behind the first cutting means with respect to the molded body in the cutting completion region (d);
The manufacturing method of the sintered magnet of Claim 1 or 2 characterized by the above-mentioned.   The method for producing a sintered magnet according to claim 1, wherein the sintered magnet powder is a rare earth sintered magnet powder.   The method for producing a sintered magnet according to any one of claims 1 to 5, wherein the alternating magnetic field of 25 to 120 Hz is applied.

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