JPS5853041B2 - Method for manufacturing rare earth cobalt magnetic material moldings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method of manufacturing rare earth cobalt magnetic material moldings, and more particularly to a method of easily manufacturing molded products of desired dimensions.

L-R Co5. is currently in practical use as a rare earth cobalt magnet material. , RCo7, R2C007, etc., have extremely large magnetic anisotropy, so it is necessary to align the crystal directions by magnetic field orientation.

Therefore, in the past, fine powder of rare earth cobalt was placed in a mold, oriented by applying a magnetic field, and then molded.

However, the size of the fine powder of rare earth cobalt for magnetic field orientation is about 3 to 8μ, its specific gravity is 83 to 8.55, and it is also magnetic (・), so the fluidity when filling the mold is , and the filling properties were poor, and it was difficult to fill a mold with a certain amount of fine powder, especially when making small molded products such as disks with a diameter of 5 cylinders or less, and molded products with complex shapes.

Therefore, it has been extremely difficult to mass-produce small or complex-shaped products with little dimensional variation.

In addition, there is a risk of ignition during molding due to static electricity and impact caused by friction, so when an organic solvent to prevent ignition is mixed with rare earth cobalt fine powder, the fluidity and filling properties during molding become even worse.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing rare earth cobalt magnetic material moldings, which allows mass production of molded products having desired shapes.

The present invention for achieving the above object includes, for example, RCo5,
A step of press-molding fine powder of a rare earth cobalt raw material such as RCo7, R2Co12, etc. to create a non-oriented rare earth cobalt block, and breaking the rare earth cobalt block to create a non-oriented granular material consisting of a collection of the fine powders. , 5-15
5. Obtaining granules that pass through a sieve in the range of 0 mesh, immersing the granules that have passed through the sieve in a resin solution, taking them out, and then drying them to obtain resin-coated granules surrounded by resin; A step of obtaining resin-coated granules that passes through a sieve in the range of ~150 meshes, a step of filling the resin-coated granules into a mold for molding, and a step of applying a magnetic field to the resin-coated granules in the mold. The present invention relates to a method for producing a rare earth cobalt magnetic material molded article, which includes the steps of: breaking the resin-coated granules into fine powder, oriented them in a magnetic field, and then press-molding them.

According to the above invention, non-oriented granules consisting of a collection of fine powders are immersed in a resin solution, taken out and dried to obtain resin-coated granules, which are then filled into a mold, and after being filled, the granules are shaped using a magnetic field. Since it is broken into fine powder, it is possible to easily manufacture L magnets with less variation in dimensions and good characteristics.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, samanium is prepared by mixing SmCo5 and SmCo4 in a 1:1 ratio such that the co content is 64 weight φ.
The cobalt alloy composition is made into a fine powder with a particle size of 3 to 8 μm and an average particle size of 5 μm using a jet mill, a ball mill, a vibration mill, or the like.

At this time, the raw material is pulverized in nitrogen gas or an organic solvent to prevent ignition.

Next, as a preliminary step to granulation, fine powder of rare earth cobalt raw material is preferably 0.5 to 3 tons/cry.
A rare earth cobalt block 1 as shown in FIG. 1A is formed by pressure molding into a disk shape or a hexahedral shape, more preferably at a pressure of 6 ton/ci.

Note that this block 1 is formed without applying an orienting magnetic field.

Next, the rare earth cobalt block 1 is broken and the sieve opening is preferably about 011 in the range of 5 to 150 meshes.
In Figure 1 B, after passing through a sieve having a mesh size of 0.04 to 3.962 mm, more preferably a sieve having a mesh size of 20 to 80 mm (a sieve having a mesh size of approximately 0.175 to 0.833 mm). Make granules 2 as shown.

That is, granules 2, which are non-oriented aggregates of rare earth cobalt fine powder, are produced.

The granules 2 must be of such a size that they can be broken down into fine powder and oriented again by the particle movement caused by the orientation magnetic field in the subsequent orientation molding process. L-8 Next, the above granular material 2 is immersed for about 5 seconds in an ethyl alcohol solution containing about 0.5 weight of at least one cellulose resin selected from methylcellulose, ethylcellulose, nitrocellulose, etc. After that, the resin ethyl alcohol solution and the particulate matter 2 are separated by filtration, and vacuum dried at about 70 to 80°C for about 1 hour.
The granules are preferably equivalent to 20 to 80 mesh passes rather than 0 mesh pass, and resin-enclosed granules 4 are formed by surrounding the rare earth core granules 2 with a resin film 3, as illustrated in FIG. 1C. .

The resin-enclosed granules 4 are formed to have such a strength that they can be broken into fine powder by the orientation magnetic field in the subsequent orientation molding step.

Therefore, it is required to form an extremely thin resin film 3 using L-cellulose resin, which has a relatively weak bonding strength.

Next, for orientation molding, a mold 5 is used, for example, with a diameter of 3 mm and a depth of 7 mm, as shown in the first diagram. The #l recess 6 is filled with resin-enclosed granules 4.

This filling is not done in the form of fine powder as in the conventional case, but is done in the form of non-oriented resin-surrounding granules 4, so that the desired amount of filling can be carried out quickly at a temperature with good fluidity.

Next, an orienting magnetic field is applied with a strength of, for example, 6 kiloersteds (kOe) or more to align the direction of the crystal.

As a result, the granules 4 move due to the strong magnetic field, and the first
As shown in Figure E, it is broken into fine powder 7, and at the same time the crystal direction is aligned in the C-axis direction.

After that, for example, 7 tons of fine powder 7 oriented in a magnetic field is
/ci, and fired at, for example, 1140° C. for 1 hour to complete a cylindrical magnetic molded product 8 as shown in FIG. 1F.

According to the above method, the mold 5 is filled with the granular material 4 instead of the fine powder, which facilitates filling and improves mass productivity.

In addition, relatively accurate filling of a predetermined amount increases efficiency and reduces the variation in the dimensions of the molded product 80.

Furthermore, since the filling is performed using granular material 4, there is less loss of raw material than when filling with fine powder.

Further, since the resin film 3 is provided, the granules 4 are stabilized, ignition is prevented, and handling becomes easier.

The relationship between the weight of the granules 4 filled into the recesses 6 of the mold 5 and the pressure used to form the block 1 in the above-described method is shown in FIG. 2.

The filling increase rate on the vertical axis in FIG. 2 is the weight d when the conventional fine powder is directly filled into the recess 6 without vibration.

, dp-do/do
℃ ゛.

As is clear from FIG. 2, if the pressure when making the block 1 is set to 0.5 to 8 ton/cnf, the filling weight increases by more than 10%.

When the block forming pressure is increased to 6 ton/ci, the filling weight increases by about 37%, and when the block forming pressure is increased further, the filling weight decreases.

The reason for this decrease at 6 tons/crA or more is due to particulate matter 4
It is thought that the change in particle size distribution is related to the change in temperature.

Even if the pressure at the time of forming the block 1 is set to 8 ton/cm or more, the filling weight is still smaller than the weight of the fine powder filling, so that it becomes difficult to destroy the granules 4 in the subsequent magnetic orientation process.

Figure 3 shows the magnetic field when magnetically orienting the granules 4 and the maximum energy product (BH) max of the molded product formed with this orientation.
It shows the relationship between

However, granules formed by forming floc 1 at 3 ton/cfi, passing through a 20-mesh sieve, obtaining granules 2, immersing them in an ethyl alcohol solution of ethyl cellulose O-5 weight φ, and drying under vacuum. Measurement was carried out using Sample 4.

In the case of a powder, it is said that most of the particles are oriented by a magnetic field of 6 to 8 kOe, and when the granules 4 are destroyed and oriented by L.

At 6 to 8 kOe, it is not sufficiently destroyed and oriented, and 12
The magnetic field of koe is almost sufficient to destroy and orient the molded product, and a molded product with a large maximum energy product (BH) max can be obtained.

Therefore, it is desirable that the magnetic destruction of the granules 4 be carried out at 12 kOe or higher.

However, if it is 6 kOe or more, it is at a practical level (B
H) It is possible to obtain max.

Figure 4 shows the diameter of the granule 4 and the maximum energy product (B
H) max.

However, the floc 1 is formed at a pressure of 3 ton/c4, and the granules 2 that pass through the sieve of each mesh are made, and this is immersed in an ethyl alcohol solution of 0.5 weight part of ethyl cellulose and vacuum dried to produce 12 kOe. The properties are shown below after being broken and oriented in a magnetic field of 1,000 lbs., then molded at a pressure of 7 ton/c77 f, and then fired at 1140° C. for 1 hour.

From FIG. 4, it can be seen that the smaller the grains 2 and 4, the better the degree of orientation L.

However, even if granules 4 with a particle size of about 5 mesh baths are used, the maximum energy product (BH) ma that is sufficient for practical use
A magnet with x is obtained.

If the particle size is made smaller, the degree of orientation will improve and it will be possible to obtain a magnet with excellent characteristics, but this will approach the conventional method of filling with fine powder, making filling difficult, reducing mass productivity, and increasing the Variations may occur.

Therefore, it is desirable to use granules that have passed through a sieve with a mesh size of 150 or less, and it is further desirable that the granules have passed through a sieve with a mesh size of 80 or less.

On the other hand, if the particle size of the granular material 40 becomes too large, it becomes difficult to break and the degree of orientation deteriorates, resulting in a decrease in (BH)max, making it impossible to produce an L magnet with good characteristics.

Therefore, it is desirable to use granules 4 that have passed through a sieve with 5 meshes or more, and even more preferably to use granules 4 that have passed through a sieve with 20 meshes or more. The invention is not limited to this, but can be further modified.

For example, instead of cellulose resins such as methylcellulose, ethylcellulose, and nitrocellulose, polyvinyl alcohol, epoxy, polyurethane, phenolic resin, etc. may be used.

Also, depending on the case, the formation of the resin film 3 may be omitted.

Further, after the molding process, a demagnetization process or a magnetization process may be performed as necessary.

[Brief explanation of the drawing]

FIG. 1 is an explanatory sectional view sequentially showing the state of each process of a rare earth cobalt magnetic material molded product according to an embodiment of the present invention, and FIG.
The figure is a graph showing the relationship between block forming pressure and filling increase rate, and Figure 3 is a graph showing the relationship between the strength of the orienting magnetic field and the (BH) max of the molded product.
FIG. 4 is a graph showing the relationship between the diameter of the granule and (BH)max of the molded product. In the drawings, 1 is a rare earth cobalt block, 2 is a granule, 3 is a resin film, 4 is a resin-enclosed granule, 5 is a mold, 6 is a recess, 7 8 is a fine powder, and 8 is a molded product.

Claims (1)

[Scope of Claims] 1. A step of press-molding a fine powder of a rare earth cobalt raw material to produce a non-oriented rare earth cobalt block, and a step of destroying the rare earth cobalt floc to form non-oriented granules made of an aggregate of the fine powder. and obtaining granules that pass through a sieve in the range of 5 to 150 meshes; immersing the granules that have passed through the sieve in a resin solution;
a step of taking out the resin-coated granules, which is then dried to obtain resin-coated granules surrounded by resin, and passing through a sieve in the range of 5 to 150 meshes; and filling the resin-coated granules into a mold for molding. and a step of applying a magnetic field to the resin-coated granules in the mold to break the resin-coated granules into fine powder and magnetic field orientation, followed by pressure molding. A method for manufacturing rare earth cobalt magnetic material moldings.