JP4278098B2 - Ferrite magnet manufacturing apparatus and manufacturing method - Google Patents

Description

  The present invention relates to a ferrite magnet manufacturing apparatus and manufacturing method.

In order to manufacture a ferrite (sintered) magnet that has become the mainstream magnet, a mixture of raw materials such as iron oxide and strontium carbonate at a predetermined blending ratio is calcined to form a ferrite, and the resulting calcined Grind the body to submicron size. Next, the pulverized powder is compression molded in a magnetic field (hereinafter referred to as magnetic field molding) and then sintered to obtain a ferrite magnet.
The magnetic field forming process is roughly divided into a dry type in which the material is dried and then formed, and a wet type in which the material is formed in a slurry state (see, for example, Patent Document 1).

Japanese Examined Patent Publication No. 46-17118

By the way, when the magnetic field forming is performed in a wet manner, the obtained ferrite magnet has a problem that the strength is suddenly reduced and cracks are generated, resulting in a decrease in yield.
The present invention has been made based on such a technical problem, and provides a ferrite magnet manufacturing apparatus and a manufacturing method capable of preventing a sudden drop in strength, stabilizing quality and improving yield. With the goal.

In order to solve the above problems, the present inventors have conducted intensive studies, and as a result, found that a ferrite magnet having a sudden drop in strength and cracking has a misalignment portion. It was.
The inventor has observed the vicinity of the cross section of the cracked ferrite magnet in detail. Then, as shown in FIG. 7, a portion A that seems to be a starting point at which cracking occurred was observed on the fracture surface S of the ferrite magnet fragments M1 and M2 that were split in two.
Then, when the structure was observed with a stereomicroscope about the portion A of the fracture surface S, as shown in FIGS. 8 and 9, the sintered density was lower than that of the other portion C1, and the orientation defect occurred ( The presence of a portion C2 was observed, in which no orientation in a specific direction was observed. As a precaution, component analysis by SEM-EDS was also performed on this portion C2, but no difference from other portions C1 was observed.
Further, as shown in FIG. 10, the portion A of the broken pieces M1 and M2 that were split into two was cut at a cross section P0 in a direction substantially perpendicular to the broken surface S, and further polished by 500 μm from the cross section P0. The polished surfaces (P1) to (P8) were observed.
Then, as shown in FIG. 11, one of the pieces M1 is visually different from the other parts in the portions indicated by reference numerals (B1) to (B8) in the polished surfaces (P1) to (P8). A portion showing was observed.
Based on these observations, the present inventor estimated that the cracks in the ferrite magnet originated from the portion where the orientation failure of the ferrite particles occurred.

Furthermore, the present inventor examined the cause of such orientation failure. As a result, it came to think that it was caused by the aggregate which mixes in during a manufacturing process. The agglomerates referred to here are those produced by solidifying the slurry by dehydration or drying in the step after pulverization. For example, in the case of a stock tank that temporarily accumulates slurry between processes, this agglomerate is a process in which the slurry adheres to the tank inner wall above the surface of the slurry liquid in the tank → dry, and further the process of adhesion of the slurry → dry occurs for a long time. It is thought that it produces | generates by the dry matter of a slurry depositing on a tank inner wall by repeating over. In addition, in the slurry transfer pipe, the flow velocity of the slurry is slow in the vicinity of the inner wall surface of the pipe, and it is considered that aggregates are also generated when the slurry accumulates and adheres to the inner wall surface of the pipe over a long period of time.
When these aggregates are collected from the manufacturing process and analyzed, the components dissolved in the slurry (Sr, Ca, etc.) may be higher than usual, so when the slurry dries, It is considered that the components (Sr, Ca, etc.) dissolved in the precipitate may precipitate to form aggregates.
These agglomerates may peel off from the inner wall of the tank or the pipe over time. Then, the peeled off aggregate is mixed in a normal slurry and flows to the subsequent process. However, since these agglomerates literally agglomerate and become strong, even if they are mixed in a normal slurry, they do not return to their original state and are likely to remain as they are.

In such an aggregate, since the ferrite particles are non-oriented and the density after firing is lower than the normal part, the part of the aggregate or the boundary surface between the aggregate and the normal part around the defect is a defect. It can be a starting point. Then, when external stress is applied to the product, the stress is concentrated on the defective portion, and it is considered that the fracture starts.
Since the fracture strength is determined by the size of the defect, the strength decreases when large agglomerates are mixed (according to the Griffith theory, the strength is proportional to c ^−1/2 when an elliptical crack having a length of 2c exists. ). Since the agglomerate corresponds to this defective portion, it can be said that the existence probability and size determine the product strength.
The size of the agglomerates is 0.01 to several mm compared to the ferrite primary particle diameter of about 0.001 mm, but those that reduce product strength and yield are 0.1 mm or more, particularly reduced. What is to be reduced is 0.3 mm or more, and more particularly that which is significantly reduced is 1 mm or more.
As for the existence probability, for example, a case where one 0.5 mm square aggregate is present in a 30 g product is assumed. If the specific gravity of the aggregate is about the same as that of the ferrite magnet (5 g / cm ³ ), the weight ratio is 0.05 × 0.05 × 0.05 × 5/30 = 2 × 10 ⁻⁵ = 20 ppm. That is, even if such a small amount of agglomerates is mixed, the strength may be reduced.

Moreover, it was also found that these agglomerates deteriorate the product strength and at the same time cause discoloration and stains when present on the surface of the product, or cause appearance defects due to fine cracks. Moreover, it becomes a cause of a crack in a processing process and a conveyance process, and also becomes a cause of a yield fall. In recent years, ferrite magnet products have been required to have extremely high quality, and even in the order of ppm, such defective products may become a problem.
Such agglomerates are especially harmful when wet magnetic field forming is performed in the ferrite magnet manufacturing process. This is because when the dry magnetic field forming is performed, there is a step of crushing the aggregate by a dispersion step after the drying step, but in the case of a wet type, there is usually no such crushing step.

Therefore, the present inventor has found that it is effective in solving the problem to provide a removal device for capturing and removing the aggregates of the slurry on the upstream side of the magnetic field forming process of the ferrite magnet.
The method for producing a ferrite magnet according to the present invention based on such knowledge includes a slurry generating step of obtaining a slurry by pulverizing a calcined body of a ferrite magnet and dispersing it in a dispersion medium, A slurry preparation step for adjusting the concentration, an agglomerate removal step for removing aggregates of components contained in the slurry from the slurry, and injecting the slurry into the mold, and applying pressure with the mold in a magnetic field in a predetermined direction. It has the shaping | molding process which obtains a molded object, and the baking process which obtains a ferrite magnet by baking the obtained molded object, It is characterized by the above-mentioned.
Thereby, the aggregate is removed from the slurry before the magnetic field forming. That is, the agglomerate removing step can be performed in order to prevent the occurrence of poorly oriented ferrite particles in the ferrite magnet obtained in the firing step.
As the dispersion medium, water is usually used, but a non-aqueous solvent may be used. Moreover, you may add a dispersing agent as needed.

Further, when the present invention is regarded as a ferrite magnet manufacturing apparatus, this apparatus has passed through a removal apparatus that removes aggregates of components contained in the slurry from the slurry in which ferrite particles are dispersed in a dispersion medium, and the removal apparatus. And a molding apparatus for compressing and molding the slurry in a magnetic field in a predetermined direction.
Of course, not only the molding apparatus, but also a pulverizing apparatus for pulverizing the ferrite calcined body, a dehydrating apparatus for dehydrating the slurry obtained by dispersing the pulverized ferrite calcined body in a dispersion medium, and feeding the dehydrated slurry to the molding apparatus. A pump or the like can be further provided. In this case, the removing device can be provided between the pulverizing device and the dehydrating device, between the dehydrating device and the pump, and between the pump and the molding device. However, it is most effective to provide such a removing device immediately before the molding device.
Further, in the case where a stock tank for storing the slurry in the process until the slurry is injected into the molding device is further provided, it can be understood that the removing device is provided on the rear stage side of the stock tank. Thereby, it becomes possible to effectively remove the aggregates deposited on the inner wall of the stock tank and falling into the slurry.
Any removal device may be used as long as it can effectively remove aggregates. However, a screen mesh may be provided at a position where the slurry passes. In this case, the opening size of the screen mesh is preferably set based on the concentration of the slurry passing through the screen mesh and the transfer pressure of the slurry. Specifically, the opening size of the screen mesh is preferably 0.01 to 10 mm, more preferably 0.1 to 1 mm, and further preferably 0.2 to 0.5 mm.

By the way, in general, as described above, when the ferrite magnet has a suddenly low strength portion and cracks or the like are generated, it is estimated that the foreign matter is caused by the outside, and this foreign matter is prevented from being mixed. It is usual to take measures for this. As an ultimate countermeasure, there is, for example, manufacturing a ferrite magnet in a clean room, which can eliminate the generation of foreign matter itself, but it takes a huge amount of money.
Moreover, even if a clean room is set up with enormous costs, this problem cannot be solved.
This time, we found out that the cause of the problem that the ferrite magnet had a suddenly low strength and cracks were caused by the poorly oriented part in the ferrite magnet, and the cause of the poor orientation was manufactured. It is clear that there is an originality of the efforts and ideas made by the present inventor in estimating and identifying the agglomerates generated in the process.

  According to the present invention, by providing a removal device for capturing and removing slurry agglomerates on the upstream side of the magnetic field forming process of the ferrite magnet, sudden strength reduction can be prevented, quality can be stabilized, and yield can be improved. It becomes possible.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a diagram showing an example of the flow of a manufacturing process of a ferrite magnet in the present embodiment. In addition, it cannot be overemphasized that the manufacturing process of the ferrite magnet shown in this Embodiment is only an example, and can change suitably.
As shown in FIG. 1, in order to manufacture a ferrite magnet, first, a material obtained by mixing raw materials such as iron oxide and strontium carbonate at a predetermined blending ratio is calcined to be ferrite (steps S101 and S102). As the raw material, oxide powder or a compound that becomes an oxide by firing, for example, carbonate, hydroxide, nitrate, or the like is used. The calcination is usually performed in an oxidizing atmosphere such as air.
Next, the obtained calcined body (ferrite calcined body) is pulverized to a submicron size through a coarse pulverization process and a fine pulverization process (steps S103 and S104) to obtain a calcined powder composed of ferrite particles. The coarse pulverization step and the fine pulverization step may be performed by a wet method or a dry method. However, since the calcined body is generally composed of granules, it is preferable to perform the coarse pulverization step dry and then the fine pulverization step wet. In that case, after roughly pulverizing the calcined body to a predetermined particle size or less in the coarse pulverization step, a pulverization slurry containing coarsely pulverized powder and water is prepared in the fine pulverization step, Fine grinding is performed until the particle size is reached.
Thereafter, a slurry having a predetermined concentration is prepared and magnetically molded. However, when wet pulverization is performed in the fine pulverization step, the slurry is concentrated in the dehydration step (step S105), so that the predetermined concentration is obtained. A slurry may be prepared. Then, after the slurry is kneaded (step S106), the slurry is poured into a mold and subjected to compression molding while applying a magnetic field in a predetermined direction (step S107). Thereafter, the obtained molded body is fired and sintered to obtain a ferrite magnet (step S108). Thereafter, a ferrite magnet as a product is completed through processing into a predetermined shape (steps S109 to S110).

FIG. 2 shows a schematic configuration of a ferrite magnet manufacturing facility (manufacturing apparatus) used in the manufacturing process as described above.
This manufacturing facility has a schematic configuration including a coarse pulverizer (pulverizer) 10, a fine pulverizer (pulverizer) 20, a dehydrator 50, a kneading device 60, a pump 70, and a molding device 80 in this order. The coarse pulverization apparatus 10, fine pulverization apparatus 20, dehydration apparatus 50, kneading apparatus 60, pump 70, and molding apparatus 80 are connected by piping or the like, and the raw materials are sequentially transferred.

For the coarse pulverization apparatus 10 and the fine pulverization apparatus 20 used in the coarse pulverization process and the fine pulverization process, for example, an attritor, a ball mill, a stamp mill, an atomizer, or the like can be used.
A filter press or a centrifuge can be used for the dehydrating apparatus 50 used in the dehydrating step.
The kneading device 60 is a mixer that further kneads the slurry in the previous stage of supplying the slurry to the molding device 80 used in the magnetic field molding step.

  As shown in FIG. 3, the pump 70 is for feeding the slurry kneaded by the kneading device 60 into the molding device 80. The slurry kneaded by the kneading device 60 is stored in the material container 71. The pump 70 sucks up the slurry from the material container 71 and sends it to the molding device 80.

The molding apparatus 80 is for subjecting the slurry prepared to a predetermined concentration to compression molding in a magnetic field, thereby orienting the ferrite particles and forming a ferrite magnet having a predetermined shape. A pair of upper and lower molds 81 and 82 are attached to the molding apparatus 80. The lower mold 81 is fixed on the base 83 of the molding apparatus 80. The upper die 82 is attached to the lower surface of a movable block 85 provided so as to be movable up and down along a guide shaft 84 extending upward from the base 83. The movable block 85 is moved up and down along the guide shaft 84 by a drive cylinder 86, whereby the molds 81 and 82 are opened and closed. The molding apparatus 80 is provided with a magnetic field generating coil (not shown) and the like so that a magnetic field in a predetermined direction can be generated in the molds 81 and 82.
The slurry delivered from the pump 70 is filled in a space formed between the molds 81 and 82 in a closed state. Then, in a magnetic field generated by a magnetic field generating coil or the like (not shown), a predetermined pressure is applied by the drive cylinder 86 to form. After completion of the molding, the molds 81 and 82 are opened and removed to obtain the ferrite magnet M molded into a predetermined shape.

Now, as shown in FIG. 2, in the ferrite magnet manufacturing facility as described above, for example, between the pulverizing apparatus 20 and the dehydrating apparatus 50, the slurry is absorbed in order to absorb the difference in the operation cycle time between the two. Stock tanks 30 and 40 for temporary storage are provided.
Immediately after each of the stock tanks 30 and 40, removal apparatuses 100A and 100B for capturing the aggregates of the raw materials mixed in the slurry are provided.
Also, removal devices 100C and 100D are provided immediately before the pump 70 and immediately before the molding device 80, respectively.
These removal devices 100A, 100B, 100C, and 100D are provided between the stock tanks 30 and 40, between the stock tank 40 and the dehydrating device 50, between the kneading device 60 and the pump 70, and between the pump 70 and the molding device 80. For example, a screen mesh is attached.

At this time, the size of the screen mesh (mesh opening size) of the removing devices 100A, 100B, 100C, and 100D is 0.01 to 10 mm, preferably 0.1 to 1 mm, and more preferably 0.2 to 0.5 mm. It is. As a matter of course, the smaller the mesh of the screen mesh, the finer aggregates can be captured, which is preferable in terms of quality. However, the resistance when the slurry passes increases, and it becomes difficult to feed the slurry. Furthermore, since the screen mesh wire diameter must be reduced, tearing due to wear or deformation is likely to occur. For this reason, the size of the screen meshes of the removal apparatuses 100A, 100B, 100C, and 100D is preferably set according to the concentration of the slurry passing, the transfer pressure, and the like. For example, when the slurry concentration is low or when the transfer pressure of the slurry flowing in the pipe is low, the mesh size is reduced to increase the agglomerate capturing efficiency, and when the slurry concentration is high or the slurry flowing in the pipe When the transfer pressure is high, the mesh size is increased so that the permeation of the slurry is not hindered.
Thus, in order to increase the trapping efficiency of the aggregate in the screen mesh and also ensure the permeability of the slurry, the slurry concentration supplied to the molding apparatus 80 is 50 to 85%, preferably 60 to 80%, Preferably it is 70 to 80%.

To give a more specific example, when the slurry concentration in the portions of the removing devices 100A and 100B is 30 to 60%, the mesh size of the screen mesh of the removing devices 100A and 100B is 0.01 to 0.2 mm. preferable.
In addition, in the portions of the removing devices 100C and 100D where the slurry concentration has increased through the dehydrating device 50, when the slurry concentration is 60 to 70%, the mesh of the screen mesh of the removing devices 100C and 100D is 0.1 to The thickness is preferably 1.0 mm. Further, when the slurry concentration in the portions of the removing devices 100C and 100D is 70 to 80%, the mesh of the screen mesh of the removing devices 100C and 100D is preferably 0.2 to 0.5 mm.

  Note that the installation location and the number of installations of the removal devices 100A, 100B, 100C, and 100D are not limited to those described above, but the removal device 100D is provided immediately before the slurry is fed into the molding device 80. Is effective.

Moreover, it is preferable that these removal apparatuses 100A, 100B, 100C, and 100D perform maintenance such as cleaning periodically.
For this reason, as shown in FIG. 3, the removal device 100D has a configuration in which the piping of the pump 70 and the molding device 80 is branched into two systems in the middle, and the removal devices 100D-1 and 100D-2 are provided in both the pipings. It is said that. Valves 102 and 103 are provided before and after the removal devices 100D-1 and 100D-2, respectively, and the removal devices 100D-1 and 100D-2 that allow the slurry to pass therethrough can be appropriately switched by opening and closing them. It can be done.
In such a configuration, the flow of the slurry on the downstream side of the removal devices 100D-1 and 100D-2 is monitored with a flowmeter or the like, and when the flow is stagnated, the valves 102 and 103 are opened and closed to remove the removal device. You may make it switch 100D-1 and 100D-2 automatically. Furthermore, an alarm or the like that prompts cleaning of the removal devices 100D-1 and 100D-2 on the side where the flow is stagnant may be output.

Here, the comparison for confirming the removal effect of the aggregate by the above screen mesh was performed.
A ferrite magnet M having a substantially C-shaped cross section as shown in FIG. 4 was manufactured by the process as shown in FIG. Here, the dimensions of the ferrite magnet M were an outer diameter d1 = 53 mm, an inner diameter d2 = 43 mm, a height H = 20 mm, and a length L = 43 mm.
When manufacturing such a ferrite magnet M, a screen mesh is installed in the middle of a pipe through which slurry is supplied into the molds 81 and 82 of the molding apparatus 80 (conditions 1, 2, and 3), and no screen mesh is installed. Compared to the case (comparison conditions). The installed screen mesh had three openings of 0.27 mm, 0.35 mm, and 0.45 mm. And the molded object obtained by performing magnetic field shaping | molding with the shaping | molding apparatus 80 was baked and processed, and the ferrite magnet M was formed.
The obtained ferrite magnet M was subjected to a three-point bending test with a strength tester, and as shown in FIG. 5, the breaking strength was measured when the pressure was applied by a pressure member 90 at a speed of 3 mm / min.
The results are shown in Table 1 and FIG. In FIG. 6, the pressure (kN) at the time when the ferrite magnet M breaks is classified into a class of 0.2 (kN) and the horizontal axis is a class of 0.2 (kN). The vertical axis represents the number of samples of the ferrite magnet M classified into the class.

As shown in Table 1 and FIG. 6, the ferrite magnet M samples are dispersed over a wide range of 0.8 to 1.6 (kN) under comparative conditions in which no screen mesh is installed. On the other hand, in the conditions 1 to 3 where the screen mesh is installed, the sample is dispersed in the range of 1.0 to 2.0 (kN), whereby the strength of the ferrite magnet M is obtained by providing the screen mesh. It can be seen that there is an overall improvement.
Furthermore, in the conditions 1 and 2 with a small mesh opening, the dispersion range is narrowed, and it can be seen that the strength of the ferrite magnet M is more stable.
Thus, it can be said that aggregates in the slurry are captured and removed by the screen mesh, and as a result, the strength of the manufactured ferrite magnet M can be improved and the quality thereof can be stabilized.

Next, a ferrite magnet M having a substantially C-shaped cross section was manufactured in the same manner as in Example 1. At this time, the ferrite magnet M had an outer diameter d1 = 92 mm, an inner diameter d2 = 83 mm, a height H = 10 mm, and a length L = 20 mm. And when manufacturing such a ferrite magnet M, a screen mesh is installed in the middle of the piping to which slurry is supplied into the mold 81 of the molding apparatus 80 (conditions 4 and 5), and no screen mesh is installed. Comparison (comparison conditions). Two screen meshes with an opening of 0.27 mm and 0.58 mm were used. And the ferrite magnet M obtained by baking and processing the molded object obtained by performing magnetic field shaping | molding with the shaping | molding apparatus 80 was formed as a sample.
Appearance selection was performed on a total of 256 samples formed, and the defect rate was calculated.
The results are shown in Table 2. Here, “exterior appearance” means that there is a defect that is visually recognized as having a different property from other parts, and “exfoliation failure” means that a trace (concave part) is formed on the surface of the sample. “Flawed cracking” indicates that a crack (including fine cracks) has occurred on the surface of the sample.

  As shown in Table 2, it can be seen that conditions 4 and 5 in which the screen mesh is installed are clearly reduced for any of the defects in appearance, peeling, and cracking, compared to the comparison condition in which the screen mesh is not installed.

As described above, the removal devices 100A, 100B, 100C, and 100D that capture and remove the aggregates of the slurry are provided on the upstream side of the magnetic field forming process of the ferrite magnet M. Thereby, the agglomerates in which the orientation of the ferrite particles is difficult can be removed in advance by magnetic field forming in the forming apparatus 80. As a result, it is possible to prevent the resulting ferrite magnet M from having an orientation failure portion that can be a starting point for occurrence of defects such as cracks, and to improve the strength of the ferrite magnet M. Furthermore, defects such as poor appearance and peeling can be suppressed. In this way, the quality of the ferrite magnet M can be improved, the quality can be stabilized, and the yield can be improved.
In addition, the removal devices 100A, 100B, 100C, and 100D can remove not only the agglomerates of the slurry that cause the alignment failure portion but also foreign matters mixed from the outside. This also contributes to improving the quality and stabilizing the quality of the ferrite magnet M.
Further, if a screen mesh is used for the removal devices 100A, 100B, 100C, and 100D, such a screen mesh can be installed relatively easily in the middle of the slurry transfer pipe, so that the above-mentioned can be achieved at low cost. The remarkable effect like this can be obtained.

In addition, in the said embodiment, although the installation place of removal apparatus 100A, 100B, 100C, 100D was illustrated, it is good also as a structure installed in a location other than this. Ideally, it is preferably provided for each process in which aggregates may be mixed, but it is effective to install at least immediately before the slurry is supplied into the mold 81 in the wet molding process. Moreover, you may install a screen mesh in a part of apparatus which applies a big shearing force to a slurry and crushes an aggregate.
Further, in the removing devices 100A, 100B, 100C, and 100D, a filter other than a screen mesh can be used as long as aggregates can be efficiently captured.
In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

It is a figure which shows the manufacturing process of the ferrite magnet in this Embodiment. It is a figure which shows schematic structure of the manufacturing equipment of a ferrite magnet. It is a figure which shows a shaping | molding apparatus and the removal apparatus provided just before that. It is a perspective view which shows the example of the ferrite magnet used in the Example of this invention. It is a figure which shows the method of a 3 point | piece bending test. It is a figure which shows the result of a 3 point | piece bending test. It is a figure which shows the cross section of the cracked ferrite magnet. It is a figure which shows the structure | tissue of a cross section. In the cross section of FIG. 8, it is a figure which shows the part from which the property of a structure | tissue differs, (C1) is a normal structure | tissue, (C2) is a structure | tissue in which the orientation defect has arisen. It is a figure for demonstrating the observation surface for further observing a cross section. It is a figure which shows each observation surface of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Coarse pulverizer (pulverizer), 20 ... Fine pulverizer (pulverizer), 30, 40 ... Stock tank, 50 ... Dehydrator, 60 ... Kneader, 70 ... Pump, 80 ... Molding device, 81, 82 ... Mold, 100A, 100B, 100C, 100D ... removal device, M ... ferrite magnet

Claims (7)

A ferrite magnet manufacturing apparatus,
A removal device for removing aggregates of components contained in the slurry from the slurry in which the ferrite particles are dispersed in the dispersion medium;
A molding device for compressing and molding the slurry that has passed through the removing device in a magnetic field in a predetermined direction;
Equipped with a,
The apparatus for producing a ferrite magnet is characterized in that the removal of the agglomerates in the removing device is performed in order to prevent occurrence of a poorly oriented portion of ferrite particles in the ferrite magnet obtained through the molding device. A grinding device for grinding the ferrite calcined body;
A dehydrator for dehydrating the slurry obtained by dispersing the calcined ferrite body pulverized by the pulverizer in the dispersion medium;
A pump for feeding the slurry dehydrated by the dehydrator into the molding device;
Further comprising
2. The production of a ferrite magnet according to claim 1, wherein the removing device is provided between the crushing device and the dehydrating device, between the dehydrating device and the pump, and between the pump and the molding device. apparatus. Further comprising a stock tank for storing the slurry in the course of pouring the slurry into the molding apparatus;
The apparatus for producing a ferrite magnet according to claim 1 or 2, wherein the removing device is provided on a rear stage side of the stock tank. The ferrite magnet manufacturing apparatus according to any one of claims 1 to 3, wherein the removing device is provided immediately before the molding device. The ferrite magnet manufacturing apparatus according to claim 1, wherein the removing device includes a screen mesh at a position where the slurry passes. The ferrite magnet manufacturing apparatus according to claim 5, wherein the mesh size of the screen mesh is set based on a concentration of the slurry passing through the screen mesh and a transfer pressure of the slurry. A slurry generation step of obtaining a slurry by pulverizing a calcined body of a ferrite magnet and dispersing it in a dispersion medium;
A slurry preparation step of preparing the slurry to a predetermined concentration;
An aggregate removal step of removing aggregates of the slurry components from the slurry;
A molding step of injecting the slurry into a mold and obtaining a molded body by applying pressure with the mold in a magnetic field in a predetermined direction;
A firing step of obtaining a ferrite magnet by firing the molded body,
Have
The method for producing a ferrite magnet is characterized in that the agglomerate removing step is performed in order to prevent occurrence of a poorly oriented portion of ferrite particles in the ferrite magnet obtained in the firing step .

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