JP5543630B2 - Sintered magnet manufacturing equipment - Google Patents

Description

  The present invention relates to an apparatus for producing a sintered magnet made of a sintered body such as a rare earth / iron / boron magnet (RFeB magnet) or a rare earth / cobalt magnet (RCo magnet).

  The RFeB magnet was discovered by Sagawa (the inventors of the present invention) in 1982 and has characteristics far exceeding those of the permanent magnets used so far. It can be manufactured from various raw materials. Therefore, RFeB magnets are used in various products such as voice coil motors such as hard disks, drive motors for hybrid and electric vehicles, motors for electric assist type bicycles, industrial motors, high-end speakers, headphones, and permanent magnet magnetic resonance diagnostic equipment. Is used.

The RFeB magnet is mainly composed of an R ₂ Fe ₁₄ B intermetallic compound having a tetragonal crystal structure and magnetic anisotropy (Patent Document 1). In order to enhance the magnetic properties of the RFeB magnet, it is necessary to make use of this magnetic anisotropy, and therefore, it is manufactured by a sintering method capable of obtaining a dense and homogeneous microstructure.

  Generally, in the sintering method, first, an alloy powder of an RFeB magnet is filled in a mold, and then a magnetic field is applied to the alloy powder while applying pressure with a press machine, and molding and orientation treatment are performed simultaneously. After being removed from the mold, it is heated and sintered. On the other hand, in Patent Document 2, an alloy powder of an RFeB magnet is filled in a filled firing container (filling step), and the alloy powder is oriented in a magnetic field without performing press forming (orientation step), and then heated as it is ( It is described that an RFeB sintered magnet is manufactured by a sintering process. According to this method, since the orientation of the alloy powder is not disturbed by press forming, an RFeB magnet having higher magnetic characteristics can be obtained.

  Further, in Patent Document 2, a filling means, an orientation means, and a sintering means are provided in a sealed container that holds the interior in an oxygen-free or inert gas atmosphere, and further, the filling means to the orientation means, and the orientation means to the sintering means. Describes a sintered magnet manufacturing apparatus provided with a conveying means for conveying a filled and fired container. According to this apparatus, since the alloy powder can be handled consistently in an oxygen-free or inert gas atmosphere throughout the entire process, its oxidation and deterioration of magnetic properties can be prevented.

JP 59-046008 JP 2006-019521 A

  Sintered magnets are manufactured in a flow process. That is, filling, orientation, and sintering operations are performed in parallel. In particular, it is difficult to prevent the magnetic field from leaking to the outside of the orientation means because the orientation means needs to apply a strong magnetic field having a magnetic flux density of several Tesla to the alloy powder. Therefore, a force acts on the alloy powder due to the leaked magnetic field, thereby disturbing the orientation of the alloy powder in the sintering means, or hindering the filling of the alloy powder in the filling means.

  In order to eliminate the influence of these leakage magnetic fields, it is conceivable to increase the distance between the aligning means and the sintering means, and between the aligning means and the filling means, but in that case, an increase in the size of the manufacturing apparatus is inevitable. When the entire apparatus is increased in size as described above, the space required for installing the apparatus increases, and the cost for maintaining an oxygen-free or inert gas atmosphere increases because it is necessary to increase the size of the sealed container. Problem arises.

  Up to this point, we explained RFeB magnets that are particularly susceptible to oxidation, but the problem of occupying a large space even when manufacturing magnets that are relatively insensitive to oxidation and do not require the use of sealed containers. Occurs as well.

  The problem to be solved by the present invention is to provide a sintered magnet manufacturing apparatus capable of preventing the influence of a magnetic field leaking in an orientation process.

The sintered magnet manufacturing apparatus according to the present invention, which has been made to solve the above problems,
a) filling means for filling the alloy powder into a filling and firing container;
b) it has an air core coil, and Oriented means Ru is oriented in a magnetic field without compressing the alloy powder of the filling firing container in the orientation position in the air core coil,
c) a sintering means for sintering the alloy powder;
d) Conveying means for conveying the filled firing container in the order of the filling means, the orientation means, and the sintering means;
With
e) the orientation means is arranged such that the filling means and the sintering means are not present on the extension of the axis of the air-core coil;
f) At least the filling means and the orientation position are in one sealed container, and the filling means, the orientation position , the sintering means, and the transport means are held in an oxygen-free or inert gas atmosphere. It is characterized by that.

  The intensity of the magnetic field leaking from the air-core coil is strongest on the extension of the axis of the air-core coil and is relatively weak around the axis. Therefore, when the filling means, the orientation means, and the sintering means are arranged in a straight line, the filling means and the sintering means are strongly affected by the leakage magnetic field. On the other hand, in the present invention, by disposing the axis of the air-core coil from the straight line connecting the filling means and the sintering means, the strength of the leakage magnetic field at the position of the filling means and the sintering means is set to the linear arrangement described above. Can be weaker than the case.

The transport means includes a main transport means for transporting the filling and firing container on a main transport line connecting the filling means and the sintering means, and a sub-transport line connecting a predetermined position on the main transport line and the orientation means. A sub-transporting means for transporting the filling and baking container can be used.

The orientation means can be arranged so that the axis of the air-core coil faces a direction different from the main transport line. In particular, it is preferable that the axis of the air-core coil is orthogonal to the main transfer line. On the other hand, the axis of the air-core coil can be arranged so as to be shifted in parallel from the main transfer line.

It is preferable that the filling means and the orientation means are accommodated in one sealed container, and the sealed container and the sintering means are in communication.
The orientation means may be a coil wound around a part of the outer wall of the sealed container.

  According to the present invention, the strength of the magnetic field leaking from the orientation means can be suppressed at the positions of the filling means and the sintering means. For this reason, it is possible to prevent the orientation of the alloy powder from being disturbed in the sintering means and the filling of the alloy powder from being hindered in the filling means.

  In addition, since the position of the filling means and the sintering means is shifted from the extension line of the axis of the air-core coil having the strongest leakage magnetic field strength, these means are more effective than the case where the filling means and the sintering means are on the extension line. It can approach the orientation means. Thereby, the apparatus can be reduced in size. In connection with it, when using an airtight container, the capacity | capacitance can be made small, the usage-amount of an inert gas can be reduced, and a running cost can be held down.

The top view which shows schematic structure of 1st Example of the sintered magnet manufacturing apparatus which concerns on this invention. Schematic which shows the leakage range of the magnetic field from the orientation means 12 in the sintered magnet manufacturing apparatus of (a) Comparative example 1, (b) Comparative example 2 and (c) 1st Example. The side view which shows schematic structure of 2nd Example of the sintered magnet manufacturing apparatus which concerns on this invention. The top view which shows schematic structure of 3rd Example of the sintered magnet manufacturing apparatus which concerns on this invention.

  An embodiment of a sintered magnet manufacturing apparatus according to the present invention will be described with reference to FIGS.

  FIG. 1 shows a first embodiment 10 of the sintered magnet manufacturing apparatus according to the present invention. This sintered magnet manufacturing apparatus 10 includes a filling means 11 for filling an alloy powder in a filling and firing container, an orientation means 12 for orienting the alloy powder filled in the filling and firing container, and a firing for sintering the oriented alloy powder. It has a linking means 13. The orientation means 12 is disposed at a position deviated from the straight line connecting the filling means 11 and the sintering means 13. Moreover, the sintered magnet manufacturing apparatus 10 has a conveying means 14 for conveying the filled and fired container. Furthermore, the sintered magnet manufacturing apparatus 10 includes a sealed container 15 that holds the filling means 11, the orientation means 12, the sintering means 13, and the conveying means 14 in an oxygen-free or inert gas atmosphere. Hereafter, each said means is demonstrated in detail.

The filling means 11 includes a powder feeding means 111 for feeding the alloy powder to the filling firing container, a leveling means 112 for flattening the pile of the alloy powder fed to the filling firing container, and a lid attached to the filling firing container. And vibrate means 113 for vibrating the alloy powder by an air vibrator, and tapping means 114 for impacting the alloy powder by hitting the filling and firing container against the table. The vibrating means 113 and the tapping means 114 can fill the alloy powder with high density without pressing. For example, a fine powder of NdFeB magnet having an average particle diameter of about 3 μm can be filled at a density of 3.5 to 4.0 g / cm ³ .

  The orientation means 12 is substantially on the same plane as the filling means 11 and the sintering means 13, but deviated from a straight line connecting the both, specifically from an intermediate point 143 between the filling means 11 and the sintering means 13. It is arranged at a position perpendicular to the straight line and proceeding in the lateral direction. Accordingly, the sealed container 15 has a protruding portion 151 from which a portion of the orientation means 12 protrudes. The orientation means 12 includes an air-core coil 121 that generates a magnetic field, and the axis of the air-core coil 121 is perpendicular to the straight line connecting the filling means 11 and the sintering means 13 (the direction indicated by the one-dot chain line in the figure). ). The air-core coil 121 is wound around the outer wall 152 of the projecting portion 151, and the outer wall 152 also serves as a coil bobbin. As described above, the outer wall 152 also serves as a coil bobbin, so that the inner diameter of the air-core coil can be made smaller than when a coil bobbin is separately provided outside the outer wall 152 and the generated magnetic field strength can be increased.

  The sintering means 13 is composed of a heating furnace that heats the filled baking container conveyed from the orientation means 12 as it is. The inside of the heating furnace communicates with the sealed container 15, and both the inside of the heating furnace and the sealed container 15 can be maintained in an oxygen-free or inert gas atmosphere. There is a heat insulating door (not shown) between the heating furnace and the sealed container 15, and during heating, the door is closed to suppress the temperature rise in the sealed container 15, and the heating furnace alone is free of oxygen or oxygen. An active gas atmosphere can be maintained.

  The conveying means 14 includes a main conveying line 141 that conveys the filling and firing container from the filling means 11 through the intermediate point 143 to the sintering means 13, and a direction perpendicular to the main conveying line 141 between the intermediate point 143 and the orientation means 12. And a sub-transport line 142 for transporting the filled firing container. A belt conveyor made of non-magnetic resin or the like is used for the conveying means 14 in order to avoid the influence on the oriented alloy powder.

The operation of the sintered magnet manufacturing apparatus 10 of the present embodiment will be described by taking as an example the case of manufacturing a NdFeB sintered magnet.
First, the filling and firing container is disposed in the filling unit 11 at the position of the powder supply unit 111. The powder feeding means 111 has a weighing device, and puts a predetermined amount of NdFeB alloy powder into the filling and firing container from the hopper. Next, the piles of the alloy powder in the filling and firing container are flattened by the leveling means 112. Then, the filling and firing container is covered, the alloy powder is vibrated by the vibrating means 113, and an impact is further given by the tapping means 114. By the operation of the vibration means 113 and the tapping means 114, the density of the alloy powder in the filling and firing container is increased to about 3.5 to 4.0 g / cm ³ .

Next, the conveying means 14 conveys the filled baking container from the filling means 11 to the orientation means 12 via the intermediate point 143. The orientation unit 12 applies a pulse magnetic field of 3 to 8 T to the alloy powder in a state where the filling and firing container is disposed in the air core of the air core coil 121. Then, the fine particles of the alloy powder are rotated by receiving a force from the magnetic field and are oriented so that the easy magnetization axes are aligned.
This orientation treatment is essentially different from the magnetization treatment performed by applying a magnetic field to the sintered body after the sintering treatment with many sintered magnets. The orientation process moves the fine particles with the force received from the magnetic field as described above, whereas the magnetization process aligns the direction of the electron spin without moving the fine particles. Therefore, the magnetization process is performed after the sintering process, while the orientation process is performed before the sintering process so that the fine particles can be moved.

  After the orientation process, the transport means 14 transports the filled firing container from the orientation means 12 to the sintering means 13 via the intermediate point 143. The sintering means 13 sinters the alloy powder by heating to 950 to 1050 ° C. while keeping the oriented alloy powder in the filled firing container (without applying a load such as pressure). Thereby, a NdFeB sintered magnet is obtained.

  In this apparatus, a large number of magnets are sequentially manufactured by a flow operation. Therefore, when the orientation treatment is performed on the alloy powder in the filling and firing container as the orientation means 12, the filling means 11 fills another filling and firing container with the alloy powder, and the sintering means 13 performs other processing. The process of sintering the alloy powder in the filled and fired container is performed in parallel.

  Next, the influence of the magnetic field leaking from the air-core coil will be described with reference to FIG. 2 for the sintered magnet manufacturing apparatus 10 of this embodiment and the comparative example. The magnetic field leaking from the air core coil is strongest on the extension of the axis of the air core coil and is relatively weak around the axis. Therefore, the range in which a strong leakage magnetic field that affects the alloy powder in the filled firing container exists (hereinafter referred to as “magnetic field leakage range 51”) is in the axial direction of the air-core coil as shown in FIG. It becomes a shape close to an ellipse with a long axis. Therefore, when the orientation unit 12 is arranged on the line connecting the filling unit 11 and the sintering unit 13 so that the axis of the air-core coil faces (Comparative Example 1: FIG. 2A), the filling unit 11 and the sintering unit 13 are arranged. Is included in the magnetic field leakage range 51, and other filled and fired containers being worked in parallel by the filling means 11 and the sintering means 13 are magnetized or the orientation of the alloy powder in the container is An adverse effect such as disturbance will occur. On the other hand, in order to prevent such an adverse effect, the distance between the filling means 11 and the sintering means 13 and the orientation means 12 is increased (Comparative Example 2: FIG. 2 (b)). There arises a problem that the cost for generating the oxygen / inert gas atmosphere increases.

  On the other hand, in the sintered magnet manufacturing apparatus 10 of the present embodiment, the axis of the air-core coil 121 is orthogonal to the straight line connecting the filling means 11 and the sintering means 13, and the filling means 11 is also on the extension of this axis. There is no sintering means 13 (FIG. 2 (c)). As a result, since the filling means 11 and the sintering means 13 are out of the magnetic field leakage range 51, there is no effect on the orientation of the alloy powder, and there is no need to increase the size of the apparatus.

  A second embodiment 20 of the sintered magnet manufacturing apparatus according to the present invention is shown in FIG. The sintered magnet manufacturing apparatus 20 includes a filling unit 21, an outer container housing unit 26, an orientation unit 22, a sintering unit 23, and a transport unit 24. Each of these means is accommodated in a sealed container 25. The filling means 21, the sintering means 23, and the sealed container 25 are the same as those in the first embodiment. Hereinafter, the outer container accommodating means 26, the conveying means 24, and the orientation means 22 will be described.

  The outer container accommodating means 26 performs an operation of accommodating the filled and fired container 52 in the outer container 53, and includes a filled and fired container elevator 261, a guide 262, and an outer container holder 263. Here, the outer container 53 is a container in which a plurality of filled and fired containers 52 are stacked and accommodated. Each time the filled baking container 52 is transported from the filling means 21, the filled baking container elevator 261 lowers the filled baking container 52 by one container and sequentially receives and stacks the filled baking containers 52. At that time, the guide 262 holds the side of the stacked baking containers 52. Then, after a predetermined number of filled and fired containers 52 are stacked, the filled and fired container elevator 261 raises the stacked filled and fired containers 52. At the same time, after the outer container holder 263 moves the outer container 53 in the lateral direction so that the opening provided below the outer container 53 is directly above the filling and baking container 52, the outer container 53 is lowered. The stacked baking containers 52 are accommodated in the outer container 53 by the operations of the filling baking container elevator 261 and the outer container holder 263.

  The transport unit 24 includes a main transport unit 241 that transports the filling and firing container 52 and the outer container 53 from the filling unit 21 through the outer container housing unit 26 to the sintering unit 23 in the lateral direction. At the same time, it is provided between the outer container housing means 26 and the sintering means 23, and is a sub-transport means for transporting the outer container 53 containing the filled and fired container 52 in the vertical direction between the main transport means 241 and the orientation means 22. 242. A belt conveyor made of non-metallic parts can be used for the main conveying means 241 as in the first embodiment. An elevator similar to the filling and firing container elevator 261 can be used for the sub-transport means 242.

  The orientation means 22 is provided immediately above the sub-transport means 242 and has an air-core coil 221 with the vertical direction as an axis (a chain line in the figure). In the air core of the air core coil 221, the outer container 53 is carried in / out by the sub transport means 242 as described above. In addition, although the example which arrange | positions a coil inside the airtight container 25 was shown in FIG. 3, a coil can also be wound around the applicable part of an airtight container like Example 1. FIG.

Operation | movement of the sintered magnet manufacturing apparatus 20 of a present Example is demonstrated. In the same way as in the first embodiment, the filling means 21 weighs the alloy powder by the powder feeding means and feeds it to the filling and firing container 52, and the alloy powder is 3.5 to 4.0 g / cm by the leveling means, the vibration means and the tapping means. Fill to a high density of ³ . The conveying means 24 sequentially conveys the filled and fired containers 52 filled with the alloy powder in this way to the outer container accommodating means 26, and the outer container accommodating means 26 accommodates the filled and fired containers 52 in the outer container 53 as described above. To do. Next, the transport unit 24 transports the outer container 53 into the air core coil of the orientation unit 22 by the main transport unit 241 and the sub transport unit 242. Then, the orientation means 22 orients the alloy powder by applying a pulse magnetic field of 3 to 8 T to the alloy powder in the filling and firing vessel 52 in the vertical direction. Thereafter, the conveying means 24 conveys the outer container 53 to the sintering means 23, and the sintering means 23 sinters the alloy powder by heating to 950 to 1050 ° C. with the alloy powder oriented. Thereby, a NdFeB sintered magnet is obtained.

  In the sintered magnet manufacturing apparatus 20 of the present embodiment, since the orientation means 22 is provided above the transport means 24, the installation area can be further reduced. In addition, since this apparatus simultaneously performs the alignment process on the plurality of filled baking containers 52, it is possible to further suppress the influence of the magnetic field on the area other than the alignment means 22.

  In addition, although the example which uses the outer container accommodating means 26 in order to perform the orientation process of several filling baking containers 52 here was shown, also when performing the orientation process one by one with respect to the filling baking containers 52, it is installed. In order to obtain the above effect of further reducing the area, the sub-transport means 242 that moves in the vertical direction of the present embodiment can be suitably used.

  FIG. 4 shows a third embodiment 30 of the sintered magnet manufacturing apparatus of the present invention. The sintered magnet manufacturing apparatus 30 of the present embodiment includes a filling means 31, a sintering means 33, and a sealed container 35 similar to those of the first embodiment. The orientation means 32 has the same configuration as in the second embodiment. However, the orienting means 32 is arranged so that the axis of the coil (the one-dot chain line in the figure) is oriented in a direction parallel to the straight line connecting the filling means 31 and the sintering means 33 and deviates from the straight line. By arranging the orientation means 32 in this way, the positions of the filling means 31 and the sintering means 33 deviate from the magnetic field leakage range 51 of the orientation means 32. The conveying means 34 conveys the filling and firing container from the filling means 31 through the orientation means 32 to the sintering means 33 in a non-linear manner according to the position of the orientation means 32. The operation of the sintered magnet manufacturing apparatus 30 of the present embodiment is the same as the operation of the sintered magnet manufacturing apparatus 10 of the first embodiment except for the above-described operation of the conveying means 34.

10, 20, 30 ... sintered magnet manufacturing apparatus 11, 21, 31 ... filling means 111 ... powder feeding means 112 ... smoothing means 113 ... vibration means 114 ... tapping means 12, 22, 32 ... orientation means 121, 221 ... empty Core coil 13, 23, 33 ... Sintering means 14, 24, 34 ... Conveying means 141 ... Main conveying line 142 ... Sub conveying line 143 ... Intermediate point 15, 25, 35 ... Sealed container 151 ... Protruding part 152 ... Outer wall 241 ... Main transport means 242 ... Sub-transport means 26 ... Outer container storage means 261 ... Filling and firing container elevator 262 ... Guide 263 ... Outer container holder 51 ... Magnetic leakage range 52 ... Filling and firing container 53 ... Outer container

Claims (9)

a) filling means for filling the alloy powder into a filling and firing container;
b) having an air-core coil, and orienting means for orienting the alloy powder in the filling and firing container in a magnetic field at the orientation position in the air-core coil without compressing;
c) a sintering means for sintering the alloy powder;
d) Conveying means for conveying the filled firing container in the order of the filling means, the orientation means, and the sintering means;
With
e) the orientation means is arranged such that the filling means and the sintering means are not present on the extension of the axis of the air-core coil;
f) At least the filling means and the orientation position are in one sealed container, and the filling means, the orientation position, the sintering means, and the transport means are held in an oxygen-free or inert gas atmosphere. The sintered magnet manufacturing apparatus characterized by the above-mentioned. 2. The sintered magnet manufacturing apparatus according to claim 1 , wherein the filling unit and the orientation unit are accommodated in one sealed container, and the sealed container and the sintering unit communicate with each other. On the main conveyance line which conveys the filling and baking container on the main conveyance line which connects the filling means and the sintering means, the conveyance means on the sub conveyance line which connects the predetermined position on the main conveyance line and the orientation means in the sintered magnet production system according to claim 1 or 2, characterized in that and a secondary transfer means for transferring the filling firing container. The sintered magnet manufacturing apparatus according to claim 3 , wherein an axis of the air-core coil faces a direction different from the main transfer line . The sintered magnet manufacturing apparatus according to claim 4 , wherein an axis of the air-core coil is orthogonal to the main transfer line . The sintered magnet manufacturing apparatus according to claim 3 , wherein an axis of the air-core coil is parallel to the main transfer line . The sintered magnet manufacturing apparatus according to any one of claims 3 to 6, wherein the sub-conveying line moves the filling and firing container in the vertical direction.   8. The alignment method according to claim 1, wherein after the plurality of filling and baking containers are conveyed from the filling means by the alignment means, the plurality of filling and baking containers are simultaneously subjected to an alignment treatment. 9. Sintered magnet manufacturing equipment. The sintered magnet manufacturing apparatus according to claim 8, further comprising an outer container housing unit that houses a plurality of filled and fired containers in an outer container between the filling unit and the orientation unit.

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