JP2002237405A - Method of sealing void section of molded article and bonded magnet sealed by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of sealing a void section of a molded article by which the void section of the molded article, such a surface void section, etc,. of a bonded magnet can be sealed selectively, easily, and dryly and an excellent sealing effect can be exhibited without having any effect on the surface accuracy of the molded article. SOLUTION: In the method of sealing the void section, the molded article having void sections on its surface and a metallic powder producing material which produces metallic powder and has a length of 0.05-10 mm are housed in a processing chamber and the metallic powder having a length of 0.1-10 μm is produced from the metallic powder producing material by supplying kinetic energy to the material housed in the chamber. Then the produced metallic powder is press-fitted in and stuck to the void section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sealing a hole in a molded product, particularly a hole on a surface of a bonded magnet, and a bonded magnet sealed by the method.

[0002]

2. Description of the Related Art Rare-earth permanent magnets such as R-Fe-B permanent magnets represented by Nd-Fe-B permanent magnets use abundant and inexpensive materials as resources and have high magnetic properties. Is used in various fields today. In recent years, in the electronics and consumer electronics industries in which rare-earth permanent magnets are used, the miniaturization and downsizing of parts have progressed, and in response to this, the necessity for downsizing and complex shapes of the magnets themselves has been pressing. . From this viewpoint, bond magnets, which are mainly composed of a magnetic powder and a resin binder, and are easy to shape, have attracted attention, and have already been put to practical use in various fields.

[0003]

SUMMARY OF THE INVENTION Rare earth permanent magnets are:
Contains R that is easily oxidized and corroded in the atmosphere. Therefore, when used without surface treatment, corrosion progresses from the surface under the influence of a slight acid, alkali, moisture, etc., and rust is generated, which causes deterioration and variation in magnetic characteristics. Therefore, it is necessary to form a corrosion-resistant coating on the magnet surface by electroplating or the like.
However, for example, when the electroplating process is performed directly on a bonded magnet having a hole on the surface, a surface cleaning agent or a plating solution infiltrates the hole and remains, thereby causing corrosion of the magnet. become. In order to solve this problem, a method has been proposed in which pores on the surface of the magnet are subjected to a sealing treatment of impregnating with an inorganic substance such as glass or a resin, and then electroplating is performed (for example, Japanese Patent Application Laid-Open No. 7-1995). 201
620). However, if the magnet is immersed in an aqueous solution containing an inorganic component or a resin component when performing the sealing treatment, it is not desirable because the magnet may be corroded by moisture. Further, even when the magnet is immersed in the resin itself or a solution using a non-aqueous solvent, a curing process is necessarily required after the immersion process, which is not desirable from the viewpoint of simplifying the production process. Further, in the above method, it is impossible to impregnate only the pores on the magnet surface with the inorganic substance or the resin, and an adhered layer made of the inorganic substance or the resin is formed on the entire magnet surface. Since this adhered layer is not formed uniformly due to liquid dripping or the like, even if surface smoothing is performed in the subsequent process, it adversely affects the surface accuracy of the magnet,
It is difficult to form a plating film having excellent dimensional accuracy. The deposited layer may be removed, but this will increase the number of production steps. Japanese Patent Application Laid-Open No. 9-2050013 discloses that a blast medium and a metal powder are simultaneously projected onto a bond magnet, or a blast medium, a metal powder, and a bond magnet are placed in a container, and the entire container is rotated or vibrated. A method for sealing a void portion on the surface of a bonded magnet is described. However, in this method, even if the metal powder is once pressed into the hole on the surface of the magnet, the metal powder that has been pressed in falls off due to a subsequent collision with the contents in the container or a collision with the inner wall of the container. As a result, there is a problem that the pores are not sufficiently sealed. In addition, ring-shaped bonded magnets used in various small motors such as spindle motors and servo motors used in actuators are not limited to holes in the outer surface (including the end faces; the same applies hereinafter). In addition, it is necessary to perform a sufficient sealing treatment on the holes on the inner surface. Therefore, the present invention can be carried out selectively and simply and dryly on the voids of the molded body such as the voids on the surface of the bonded magnet, exhibiting an excellent sealing effect, and exhibiting an excellent sealing effect. It is an object of the present invention to provide a sealing method that does not affect accuracy.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above points, and a method of sealing a void of a molded article according to the present invention has the following features. A molded body having a hole and a long diameter of 0.05 mm to 1 for producing metal powder
A metal powder-producing substance having a diameter of 0 mm is accommodated in a processing container, and kinetic energy is supplied to the container in the processing container, so that the long diameter of the metal powder-producing substance is 0.1 μm to 10 μm.
The method is characterized in that a metal powder of μm is generated, and the generated metal powder is press-fitted and fixed in the hole. The sealing method according to a second aspect of the present invention is the sealing method according to the first aspect, wherein the metal powder generating substance is a copper powder generating substance that generates copper powder. In a third aspect of the present invention, the metal powder-forming substance has a needle shape and / or a columnar shape. The sealing method according to a fourth aspect is characterized in that, in the sealing method according to any one of the first to third aspects, fats and oils are further stored in a processing container. The sealing method according to a fifth aspect is characterized in that, in the sealing method according to the fourth aspect, the fats and oils are stored in the treatment container using a vegetable medium containing fats and oils. A sealing method according to a sixth aspect is characterized in that, in the sealing method according to the fourth aspect, an inorganic powder is further contained in a processing container. The sealing treatment method according to claim 7 is the sealing treatment method according to claim 6, wherein the inorganic powder and the oil and fat are placed in a processing vessel by using a vegetable medium in which the inorganic powder is adhered to the surface with the oil and fat. It is characterized by being housed in Further, the sealing treatment method according to claim 8 is a method according to claim 5 or 7.
In the above-mentioned method for sealing treatment, the vegetable medium is at least one selected from vegetable peelings, sawdust, firs, bran, fruit husks, and corn cobs. In addition, the sealing method according to the ninth aspect is directed to the first aspect.
9. The sealing method according to any one of items 1 to 8, wherein the molded body having a hole on the surface is a bonded magnet. Further, the sealing method according to claim 10 is:
The sealing method according to claim 9, wherein the bonded magnet is a ring-shaped bonded magnet. Also,
According to a eleventh aspect of the present invention, in the sealing method according to any one of the first to tenth aspects, by vibrating and / or stirring the contents in the processing container,
It is characterized in that kinetic energy is supplied to the stored items. In addition, the sealing method according to the twelfth aspect is directed to the first aspect.
2. The method according to claim 1, wherein the processing container is a processing chamber of a barrel device. Claim 1
The sealing method according to claim 3, wherein the ring-shaped bonded magnet is provided in the cylindrical processing container in the sealing method according to claim 10.
Kind energy is supplied to the container by housing the cylindrical processing container so that its central axis direction is parallel to the central axis direction of the cylindrical processing container, and rotating the cylindrical processing container around the central axis. It is characterized by the following. According to a fourteenth aspect of the present invention, in the sealing method of the thirteenth aspect, the rod-shaped member is inserted through the hollow portion of the ring-shaped bonded magnet so as to be parallel to the central axis direction. It is characterized by the following. In addition, the bonded magnet of the present invention,
According to a fifteenth aspect, a sealing process is performed by the sealing method according to the first aspect.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A method for sealing a pore portion of a molded article according to the present invention is a method for treating a molded article having a pore portion on its surface and a metal powder producing substance having a major diameter of 0.05 mm to 10 mm for producing metal powder. The metal powder is stored in a container, and kinetic energy is supplied to the container in the processing container to generate a metal powder having a long diameter of 0.1 μm to 10 μm from the metal powder generation material. Characterized by being press-fitted and fixed. According to this method, the metal powder generating substance has a role of generating the metal powder by collision between the metal powder generating substances, a collision with the compact, a collision with the inner wall of the processing container, and the like. It plays a role as a medium for press-fitting into the part, and together with these roles, exhibits an excellent sealing effect.

Examples of the molded article having a hole on its surface to which the sealing treatment method of the present invention can be applied include not only bonded magnets but also die casting. Among them, the sealing treatment method of the present invention is suitable for treating pores on the surface of the bonded magnet, and therefore, in the following description, the sealing treatment method of the present invention is applied to treatment of pores on the surface of the bonded magnet. The case will be described. When the present invention is applied to other molded products, processing conditions and the like may be appropriately set based on the following description.

The bonded magnet may be a magnetically isotropic bonded magnet or a magnetically anisotropic bonded magnet as long as it has magnetic powder and a resin binder as main components. Also,
In addition to those formed by bonding with a resin binder, those formed by bonding with a metal binder, an inorganic binder, or the like may be used. Further, the binder may include a filler.

[0008] Rare earth bonded magnets having various compositions and crystal structures are known, and all of them are the objects of the present invention. For example, Japanese Patent Application Laid-Open No. 9-9251
5, an anisotropic R-Fe-B-based bonded magnet as described in JP-A-5-203714, and a soft magnetic phase as described in JP-A-8-203714 (for example, α-Fe or Fe ₃
B) and Nd having a hard magnetic phase (Nd ₂ Fe ₁₄ B)
-Fe-B based nanocomposite magnet, isotropic Nd-F prepared by a liquid quenching method widely used conventionally
eB magnet powder (for example, trade name: MQP-B.MQ)
(Manufactured by I Company). Also,
(Fe _1-x R _x ) described in JP-B-5-82041
_1−y N _y (0.07 ≦ x ≦ 0.3, 0.001 ≦ y ≦
0.2), and the like.

The effect of the present invention does not differ depending on the composition, crystal structure, presence or absence of anisotropy, etc. of the magnetic powder constituting the bonded magnet. Therefore, the desired effect can be obtained in any of the above-described bonded magnets.

The magnetic powder constituting the bonded magnet is prepared by dissolving a rare-earth permanent magnet alloy and pulverizing after casting, a melting and pulverizing method, a method of once forming a sintered magnet and then pulverizing the sintered magnet, Direct reduction diffusion method to obtain magnetic powder directly by Ca reduction, Rare earth permanent magnet alloy ribbon foil obtained by melting jet caster, quenching alloy method of pulverizing and refining, Rare earth permanent magnet alloy Can be obtained by a method such as an atomizing method in which powder is atomized and heat-treated, or a mechanical alloying method in which a raw metal is pulverized, then finely pulverized by mechanical alloying and heat-treated. The magnetic powder constituting the R—Fe—N-based bonded magnet is obtained by pulverizing a rare earth permanent magnet alloy, nitriding the alloy in a nitrogen gas or an ammonia gas, and then pulverizing the alloy into a fine powder. But you can get it. Hereinafter, R-Fe-
The outline of each method will be described taking the production of magnetic powder for a B-based bonded magnet as an example.

(Melting and pulverizing method) This is a production method by a step of mechanically pulverizing raw materials after melting and casting. For example, as starting materials, electrolytic iron and B are contained, and the balance is Fe and Al.
Ferroboron alloys composed of impurities such as Si and C, rare earth metals, or raw material powders further blended with electrolytic Co, are melted by high frequency, then cast into water-cooled copper molds, and hydrogen-absorbed and pulverized. Coarse pulverization by mechanical pulverization. As the next fine pulverization process, dry pulverization using a ball mill, a jet mill or the like, or wet pulverization using various solvents can be employed. By this method, a fine powder having a tetragonal main phase and substantially consisting of a single crystal or several crystal grains and having an average particle size of 1 μm to 500 μm can be obtained. In addition, a finely pulverized powder having a required composition of 3 μm or less is subjected to orientation molding in a magnetic field, and then crushed, and further subjected to 800 ° C.
After heat treatment at 1100 ° C., the powder is crushed to obtain a magnetic powder having a high coercive force.

(Sintered body pulverization method) This is a method of sintering a required R-Fe-B-based alloy and pulverizing it again to obtain a magnetic powder. For example, electrolytic iron and B are contained as starting materials, and the balance is Fe.
A ferroboron alloy, a rare earth metal or a raw material powder mixed with electrolytic Co, which is composed of impurities such as Al, Si, C, etc., is alloyed in an inert gas atmosphere by high frequency melting or the like, and is roughly pulverized using a stamp mill or the like. ,further,
Finely pulverize with a ball mill or the like. The obtained fine powder is pressed under a magnetic field or without applying a magnetic field, sintered in a non-oxidizing atmosphere such as vacuum or inert gas, and pulverized again.
A fine powder having an average particle size of 0.3 μm to 100 μm is obtained. Thereafter, in order to increase the coercive force, at 500 ° C. to 1000 ° C.,
Heat treatment may be performed.

(Direct reduction diffusion method) At least one kind of metal powder composed of ferroboron powder, ferronickel powder, cobalt powder, iron powder, rare earth oxide powder and the like and / or a raw material alloy for which a raw powder composed of oxide powder is desired It is selected according to the composition of the powder, and metal Ca or CaH ₂ is mixed with the raw material powder in an amount of 1.1 to 4.0 times (weight ratio) the stoichiometric amount required for the reduction of the rare earth oxide powder. Then, the mixture is heated to 900 ° C. to 1200 ° C. in an inert gas atmosphere, and the obtained reaction product is poured into water to remove a reaction by-product, so that an average particle size of 10 μm to 200 μm that does not require coarse pulverization. Is obtained. The obtained powder may be further finely pulverized by dry pulverization using a ball mill, a jet mill or the like. In addition, a finely pulverized powder having a required composition of 3 μm or less is subjected to orientation molding in a magnetic field, and then crushed, and further, 800 ° C.
After heat treatment at a temperature of ° C., the powder is crushed to obtain a magnetic powder having a high coercive force.

(Quenching alloy method) A required R-Fe-B alloy is melted and melt-spun with a jet caster to obtain 2
A ribbon foil having a thickness of about 0 μm is obtained, pulverized, and then subjected to an annealing heat treatment to form a powder having fine crystal grains of 0.5 μm or less. Alternatively, the powder having fine crystal grains obtained from the ribbon foil may be hot-pressed and warm-upset to obtain a bulk magnet having anisotropy, and then finely pulverized.

(Atomizing method) A required R-Fe-B-based alloy is melted, a molten metal is dropped from a thin nozzle, atomized with a high-speed inert gas or liquid, sieved or pulverized, and then dried or annealed. This is a method of obtaining magnetic powder by heat treatment. Alternatively, the powder having the fine crystal grains may be hot-pressed and warm-upset to obtain a bulk magnet having anisotropy, and then finely pulverized.

(Mechanical alloy method) The required raw material powder is mixed and amorphousized at an atomic level in an inert gas by a ball mill, a vibration mill, a dry attritor, or the like.
Thereafter, annealing is performed to obtain magnetic powder. Alternatively, the powder having the fine crystal grains may be hot-pressed and warm-upset to obtain a bulk magnet having anisotropy, and then finely pulverized.

As a method for imparting magnetic anisotropy to a bulk or magnetic powder, alloy powder obtained by a quenching alloy method is sintered at a low temperature by a hot press or the like, and further subjected to a warm upsetting process. Warm working and pulverization method for pulverizing a bulk magnet body with magnetic anisotropy (Japanese Patent Publication No. 4-202)
No. 42 gazette), a pack rolling method in which the alloy powder obtained by the quenching alloy method is directly filled and sealed in a metal container, and magnetic anisotropy is imparted by plastic working such as warm rolling (Japanese Patent No. 2596835). ), An ingot hot working and pulverizing method for obtaining a magnetic powder having magnetic anisotropy by subjecting an alloy ingot to hot plastic working and then pulverizing (JP-B 7-668)
92), a rare earth permanent magnet alloy is heated in hydrogen to occlude hydrogen, then dehydrogenated, and then cooled to obtain a magnetic powder by the HDDR method (Japanese Patent Publication No. 6-8 / 1994).
2575) can be employed. It should be noted that the application of the magnetic anisotropy is not limited to the combination of the above-mentioned raw material alloy and the anisotropic means, but can be appropriately combined.

The composition of the magnetic powder obtained by the above method is, for example, R: 8 at% to 30 at% (where R is at least one kind of rare earth element containing Y, preferably N
d, Pr or other light rare earth elements or Nd,
B: 2 atomic% to 28 atomic% (B can be partially substituted with C), Fe:
65 atomic% to 84 atomic% (a part of Fe is replaced with 50% of Fe
The following Co and 8% or less of Fe are substituted with at least one of Ni).

Further, the obtained coercive force of the bond magnet can be increased,
To improve corrosion resistance, the raw material powder contains Cu: 3.5 atomic%.
Hereinafter, S: 2.5 at% or less, Ti: 4.5 at% or less, Si: 15 at% or less, V: 9.5 at% or less, N
b: 12.5 at% or less, Ta: 10.5 at% or less,
Cr: 8.5 atomic% or less, Mo: 9.5 atomic% or less,
W: 9.5 atomic% or less, Mn: 3.5 atomic% or less, A
l: 9.5 atomic% or less, Sb: 2.5 atomic% or less, G
e: 7 atomic% or less, Sn: 3.5 atomic% or less, Zr:
5.5 at% or less, Hf: 5.5 at% or less, Ca:
8.5 at% or less, Mg: 8.5 at% or less, Sr: 7
At least one of atomic% or less, Ba: 7 atomic% or less, Be: 7 atomic% or less, and Ga: 10 atomic% or less can be added and contained.

The magnetic powder for the Nd—Fe—B-based nanocomposite magnet has R of 1 to 10 atomic% and B of 5 atomic%.
It is desirable to select a composition within a range of about 28 atomic% and the balance substantially consisting of Fe.

When a resin binder is used as a binder for producing a bonded magnet, a resin suitable for each molding method may be used. For example, resins suitable for compression molding include epoxy resins, phenolic resins, diallyl phthalate, and the like. Suitable resins for the injection molding method include 6 nylon, 12 nylon, polyphenylene sulfide, polybutylene phthalate and the like. Examples of the resin suitable for the extrusion molding method and the roll molding method include polyvinyl chloride, acrylonitrile-butadiene rubber, chlorinated polyethylene, natural rubber, and Hypalon.

Various methods for producing a bonded magnet are known, such as a magnetic powder, a resin binder, a silane-based or titanium-based coupling agent as required, a lubricant for facilitating molding, and a resin-inorganic filler. After mixing and kneading binders in the required amount and kneading, compression molding is performed, and the resin is cured by heating. In addition to injection molding, extrusion molding, roll molding, etc. It is.

Specific examples of the metal powder producing substance for producing metal powder include Cu, Fe, Ni, Co, Cr,
A metal powder generating substance that generates a metal powder selected from Sn, Zn, Pb, Cd, In, Au, Ag, Al and the like can be given. The metal powder generated from these metal powder-producing substances, after sealing the pores, is a mechanochemical (mechanochemical) which is a unique surface chemical reaction caused by a pure metal surface (fresh surface) not subjected to oxidation or the like.
Since an adhesion layer made of a metal powder (using a metal powder as a forming source) is formed on the entire magnet surface by an electronic reaction, there is an advantage that sealing treatment and conductive treatment of the magnet surface can be performed at one time. . In particular, copper powder, for the plating film formed in the plating process performed after the conductive process,
This is advantageous from the viewpoint of conductivity and corrosion resistance, and is also desirable in terms of cost.

[0024] The metal powder-producing substance may be one that produces a metal powder composed of the above-mentioned single metal component.
It may be one that produces a metal powder composed of an alloy containing two or more metal components. Further, a metal powder composed of an alloy containing the above-described metal component as a main component and another metal component may be generated. Further, a metal powder containing impurities inevitable in industrial production may be generated. Needless to say, two or more kinds of metal powder producing substances that produce different metal powders may be mixed and used.

As the metal powder-forming substance, a metal piece made of only the desired metal, a composite metal piece obtained by coating a core material made of a different metal with the desired metal, and the like are used. These metal pieces have various shapes such as a needle shape (wire shape), a column shape, and a lump shape, but from the viewpoint of efficiently generating metal powder, a needle shape or a column shape having a sharp end is used. It is desirable to use Such a desirable shape can be easily obtained by employing a known wire cutting technique.

The size (major axis) of the metal powder forming substance is
It is 0.05 mm to 10 mm. Desirably 0.3mm
5 mm, more preferably 0.5 mm to 3 mm. This is because a metal powder-producing substance having such a size can efficiently generate metal powder having a major axis of 0.1 μm to 10 μm. The metal powder producing material may be of the same shape and the same size,
Mixtures of different dimensions may be used.

[0027] The total amount of the bonded magnet and the metal powder-forming substance contained in the processing container is 10 vol% to 10% of the volume in the processing container.
90 vol% is desirable. 10vol of processing container inner volume
If it is less than%, the amount of treatment is too small to be practical. On the other hand, when the volume exceeds 90% by volume of the processing container,
There is a possibility that the uniform mixing and stirring of the contents in the processing container does not occur efficiently, and that the metal powder is not sufficiently generated from the metal powder generation material, or that the metal powder is not sufficiently pressed and fixed to the hole. Because. The accommodation ratio of the metal powder-forming substance to the bonded magnet is desirably 3 or less in volume ratio (magnet / metal powder-forming substance). If the volume ratio exceeds 3, uniform mixing and stirring of the contents in the processing vessel does not occur efficiently, and sufficient time is required for the metal powder to be sufficiently generated and for the metal powder to be sufficiently pressed and fixed into the hole. This is because, in addition to being impractical, collision between the bonded magnets frequently occurs, which may cause cracks in the magnets, shedding of magnetic powder from the magnet surface, and the like.

As described above, in the method for sealing the pores of the molded article according to the present invention, an excellent sealing effect can be obtained without containing fats and oils in the processing container. However, in order to more firmly fix the metal powder pressed into the hole, it is desirable to further store the fat or oil in the processing container. The storage of the fat or oil in the processing container may be performed using, for example, a vegetable medium impregnated with the fat or oil. Alternatively, the inorganic powder may be accommodated in the processing container together with the oil or fat by using a vegetable medium in which the inorganic powder has been adhered to the surface with the oil or fat. Such a plant medium is convenient in that it also functions as a medium. It is desirable that the amount of the plant medium to be accommodated is 10 vol% to 90 vol% of the internal volume of the processing container as the total amount of the contents in the processing container. The reason is as described above. Further, the accommodation ratio of the vegetable medium and the metal powder-producing substance is desirably 0.1 to 2 in volume ratio (vegetable medium / metal powder-producing substance). If the volume ratio is less than 0.1, there is a possibility that the supply of the inorganic powder or the fat or oil from the vegetable medium may not be sufficiently performed,
If the volume ratio exceeds 2, the metal powder may not be sufficiently produced from the metal powder producing substance.

Oils and fats for firmly fixing the metal powder pressed into the pores are represented by head, lard, tallow, sheep, whale oil, fish oil, liver oil, olive oil, linseed oil, and cutting oil. Such animal and vegetable fats and oils can be used. It is preferable to use a fat or oil having a halogen content of 2% by weight or less so that the magnet is not corroded by the fat or oil. In order to prevent the generation of volatile components based on fats and oils, the boiling point is 170
It is desirable that the temperature is not less than ° C. In addition, candelilla wax, carnauba wax, stearic acid and the like may be appropriately blended in order to adjust the melting point of the fat or oil used.

The fats and oils may be contained alone in the treatment container. However, the fats and oils inherently contained in the vegetable medium may be used. Further, a separate fat or oil may be impregnated in the vegetable medium and stored. Further, a separate vegetable oil may be impregnated and stored in a vegetable medium originally containing the vegetable oil. When the fat or oil is supplied using the vegetable medium, the vegetable medium functions as a medium and also functions as a supply source of the fat or oil. Vegetable dander, sawdust, firs, bran, fruit husks, corn cobs and the like are used as plant media. Further, the surface of such a vegetable medium has an adhesive force due to fats and oils. Therefore, the vegetable medium in which the inorganic powder is adhered to the surface by using this adhesive force functions not only as a medium but also as a supply source of the inorganic powder and the fat and oil. By adopting such a mode in which the inorganic powder and the fats and oils are supported and stored in the vegetable medium, the amount of these stored in the treatment container may be set as the supported amount for the vegetable medium. Therefore, it is possible to supply the inorganic powder and the fat or oil simultaneously and in a desired ratio into the processing container, and it is convenient in that they can be easily and uniformly dispersed in the processing container. . The vegetable medium impregnated with oils and fats is, for example, a vegetable medium and 1% by weight to 5% by weight of the vegetable medium.
It can be prepared by kneading fats and oils by weight. A specific example of such a vegetable medium is corn cob impregnated with tallow. In addition, for example, a vegetable medium having an inorganic powder adhered to the surface thereof with fats and oils is obtained by kneading a vegetable medium, 15% by weight or less of inorganic powder and 1% to 5% by weight of fats and oils with respect to the vegetable medium. Can be prepared. As a specific example of such a plant medium, the major axis is 0.01 μm to 60 μm on the surface.
corn cob on which aluminum oxide of m is coated with beef tallow.

Examples of the inorganic powder that can be used in the above include powders of metal oxides such as aluminum oxide, zirconium oxide and magnesium oxide, powders of metal carbides such as silicon carbide, powders of metal nitrides such as aluminum nitride, Powder of metal carbonitride such as aluminum titanium carbonitride, aluminum carbonitride or silicon carbonitride, metal powder (for example, Cu, Fe, Ni, Co, Cr, Sn, Z
Powders of n, Pb, Cd, In, Au, Ag, Al, etc .:
Alloys containing these metal components may be used). Among these, it is desirable to use aluminum oxide powder or copper powder from the viewpoint of cost and the like. Needless to say, two or more kinds of inorganic powders may be used as a mixture. The inorganic powder is
Those having the same shape and the same size may be used, or those having different shapes and different sizes may be mixed and used, and the size is desirably 0.01 μm to 60 μm in the major axis.

Although the processing time depends on the processing amount, it is generally about 1 hour to about 10 hours.

The processing container that can be used in the present invention is not particularly limited as long as it can supply kinetic energy to the contents in the processing container.
A processing container capable of supplying kinetic energy to the container by applying vibration and / or stirring to the container in the processing container is desirable from the viewpoint of processing efficiency. Examples of such a processing container include a processing chamber of a barrel device and a ball mill device. Bond magnets, which cannot be said to have high strength, generate cracks and chips when the impact on the magnet is strong. From this viewpoint, it is desirable to use the processing chamber of the barrel device. As the barrel device, a known device such as a rotary type, a vibration type, a centrifugal type, or the like can be used. In the case of a rotary type, it is desirable that the number of rotations be 20 rpm to 200 rpm. In the case of the vibration type, it is desirable that the frequency be 50 Hz to 100 Hz and the vibration amplitude be 1 mm to 50 mm. In the case of the centrifugal type, it is desirable that the rotation speed be 70 rpm to 200 rpm.

In the case where the pores on the surface of the ring-shaped bonded magnet are sealed, the ring-shaped bonded magnet is placed in the cylindrical processing container so that the central axis direction thereof is parallel to the central axis direction of the cylindrical processing container. It is desirable to supply the kinetic energy to the stored object by storing and rotating the cylindrical processing container about its central axis. In this way, even in the case of a ring-shaped bonded magnet having a large L / D (L represents the length of the magnet in the central axis direction and D represents the inner diameter of the magnet), the hole on the outer surface of the ring-shaped bonded magnet has Needless to say, the pores on the inner surface can be easily and sufficiently sealed. FIG. 1 shows an example of an apparatus used in this method as a partially transparent view.

The apparatus shown in FIG. 1 is an apparatus for rotating a cylindrical processing container (hereinafter, also simply referred to as a container) 1 about its central axis. As a means, two rollers 2-a are used. A method of rotating 2-b in the same direction using a rotary ball mill device (not shown) or the like is adopted. The contents in the container 1 are a ring-shaped bonded magnet 3 and a metal powder generating substance 4.

The container 1 may be made of metal or resin, but it is desirable to use a container made of the same component as the metal powder to be press-fitted and fixed in the holes on the surface of the ring-shaped bonded magnet. Even if powder or the like is generated from the container itself due to collision between the inner wall of the container 1 and the contents, if the same component as the metal powder is used,
This is because they do not become impurities in relation to the contents.

As shown in FIG. 1, the ring-shaped bonded magnet 3 is housed in the container 1 such that the center axis direction of the magnet 3 is parallel to the center axis direction of the container 1. Although only one ring-shaped bonded magnet 3 is accommodated in the container in FIG. 1, it goes without saying that two or more ring-shaped bonded magnets 3 may be accommodated side by side. If a plurality is stored side by side,
In addition to suppressing the collision between the magnets and preventing the magnet surface from being roughened, an excellent effect in terms of the loading efficiency in a certain space can be obtained. Further, a plurality of ring-shaped bonded magnets having different diameters may be stacked and housed (that is, a smaller magnet is put in a hollow portion of a larger magnet).

When the ring-shaped bonded magnet 3 is accommodated in the container 1, it is desirable to insert and arrange the rod-shaped member 5 in the hollow portion of the magnet 3 so as to be parallel to the center axis direction of the magnet 3 (FIG. 2). reference). Due to the presence of this rod-shaped member, the behavior of the ring-shaped bonded magnet in the container can be calmed down. Therefore, when a plurality of magnets are accommodated, collision between the magnets is suppressed and the magnet surface is prevented from being roughened. .
Further, this rod-shaped member is convenient in that it also functions as a medium for press-fitting the metal powder into the hole. The rod-shaped member may be made of metal or resin, but it is desirable to use a rod-shaped member made of the same component as the metal powder to be press-fitted and fixed into the holes on the surface of the ring-shaped bonded magnet.

When the container 1 is rotated about its central axis by two rollers 2-a and 2-b (see the arrow in FIG. 1), the metal powder-forming substance 4 is transferred to the ring-shaped bonded magnet 3 with respect to the container. Flows in the same direction as the rotation direction. as a result,
The metal powder generated from the metal powder generating material 4 is efficiently pressed into the holes on the magnet surface and firmly fixed. In particular, since the metal powder generating substance 4 flowing in the hollow portion of the ring-shaped bonded magnet 3 comes into contact with the inner surface of the magnet in a flowing state, it is advantageous for press-fitting and fixing the metal powder into the holes on the inner surface. work.

The rotation speed of the container is desirably 50 rpm or more from the viewpoint that the metal powder-forming substance is brought into efficient and uniform flow contact with the pores on the surface of the ring-shaped bonded magnet. As the rotation speed of the container increases, the metal powder generating material located in the hollow portion of the ring-shaped bonded magnet efficiently comes into contact with the inner surface of the magnet in a flowing state, so that the pores on the inner surface are It works favorably for press-fitting and fixing metal powder to metal. However, if excessive rotation is applied to the container, a strong collision between the magnet and the inner surface of the container or the contents may occur, and the magnetic powder may be shed or the press-fitted metal powder may fall off. Therefore, the rotation speed of the container is desirably 300 rpm or less.

In a subsequent step, a corrosion-resistant coating having excellent dimensional accuracy is formed in a subsequent step on the bonded magnets whose surface pores have been sealed by the method of the present invention. be able to. The method for forming the corrosion resistant film is not particularly limited, and a known electroplating method or the like can be employed. Representative electroplating methods include, for example, Ni, Cu, Sn, Co, Zn, C
A plating method using at least one kind of metal selected from r, Ag, Au, Pb, Pt and the like or an alloy of the metals (which may contain B, S, and P) is exemplified. Plating thickness is 50 μm or less, desirably 10 μm to 30 μm
It is.

When performing the electric Ni plating treatment, it is desirable to perform the steps of washing, electrolytic Ni plating, washing, and drying. Various bathtubs can be used for the plating bath depending on the shape of the magnet. For example, in the case of a ring-shaped bonded magnet, it is desirable to use a bathtub for trapping plating or a bathtub for barrel plating. As the plating bath, a known plating bath such as a Watt bath, a sulfamic acid bath, a wood bath, or the like may be used. Although an electrolytic Ni plate is used for the anode, it is desirable to use an S-containing Estland nickel chip as the electrolytic Ni plate in order to stabilize the elution of Ni.
Hereinafter, details of the present invention will be described based on specific examples.

[0043]

EXAMPLES Reference Example 1: (Step A) Nd: 12 atomic%, produced by a quenched alloy method
After adding 2 wt% of epoxy resin to an alloy powder having a composition of Fe: 77 atomic%, B: 6 atomic%, and Co: 5 atomic% and having an average major diameter of 150 μm, kneading and compression molding at a pressure of 686 N / mm ² , Cure at 150 ° C for 1 hour, outer diameter 20
A ring-shaped bonded magnet having a size of 18 mm × 18 mm × 3 mm was prepared. The characteristics of the obtained ring-shaped bonded magnet (finished material) were as follows: Br: 0.67T, (BH) max: 7
0.8 kJ / m ³ and HcJ: 711 kA / m. (Step B) Ring-shaped bonded magnet 100 obtained in step A
Ceramic media (approximately 0.3 liter in weight, 130 g in weight) and 8 liters in apparent volume of ceramic media (a long diameter of 5 mm to 7 mm
mm: Granularity: True specific gravity 2.9-3.1 g / c
m ³ ), and a corn cob having an apparent volume of 8 liters of aluminum oxide powder adhered to the surface thereof with tallow (1 mm to a corn cob having a major axis of 1 mm to 2 mm).
0% by weight of aluminum oxide # 800 (having a major axis of 20 μm or less) and 3% by weight of tallow are kneaded in a processing chamber of a 20-liter vibrating barrel device (total capacity is 82 vol% of the processing chamber volume). ), Dry processing was performed for 2 hours under the conditions of a vibration frequency of 60 Hz and a vibration amplitude of 20 mm.
As a result, a ring-shaped bonded magnet in which the aluminum oxide powder was press-fitted and fixed in the holes on the magnet surface was obtained. From the surface observation with an electron microscope, it was found that most of the aluminum oxide powder pressed and fixed in the pores had a major axis of about 5 μm. The ring-shaped bonded magnet thus sealed is put in oil, and vacuum (0.1 T
(orr) or less for 10 minutes. When the porosity was measured from the oil content calculated from the weight change of the magnet by this operation, the porosity was 0.8%, and it was found that the porosity was very effectively sealed (untreated ring The porosity of the bonded magnet is 9.8%).

Example 1: Using a ring-shaped bonded magnet produced in the same manner as in Step A of Reference Example 1, in Step B of Reference Example 1, a ceramic medium having an apparent volume of 8 L Instead of containing a corn cob with aluminum oxide powder applied to the surface with tallow, an apparent volume of 8 liters and a diameter of 0.6
corn cob impregnated with short columnar copper powder producing material (cut wire) having a length of 0.6 mm × 0.6 mm and an apparent volume of 8 liters (major axis: 1 mm to 2 m)
Step B of Reference Example 1 except that 1.4% by weight of tallow was kneaded with respect to corn cobs of m.
The same processing was performed. As a result, the copper powder generated from the short columnar copper powder-producing substance is pressed and fixed in the holes, and a ring having an adhered layer made of copper powder (using copper powder as a source) is formed on the entire magnet surface. A bonded magnet was obtained.
Observation of the fracture surface with an electron microscope revealed that most of the copper powder pressed into and fixed to the holes had a major axis of about 1 μm to 2 μm.

Example 2: Using a ring-shaped bonded magnet produced in the same manner as in Step A of Reference Example 1, in Step B of Reference Example 1, a ceramic medium having an apparent volume of 8 L Instead of containing a corn cob having aluminum oxide powder coated on its surface with tallow, it has an apparent volume of 16 liters and a diameter of 0.1 liter.
The treatment was performed in the same manner as in step B of Reference Example 1 except that a short columnar copper powder-producing substance having a size of 6 mm × 0.6 mm in length (a wire cut) was accommodated. As a result, the copper powder generated from the short columnar copper powder-producing substance is pressed and fixed in the holes, and a ring having an adhered layer made of copper powder (using copper powder as a source) is formed on the entire magnet surface. A bonded magnet was obtained. Observation of the fracture surface with an electron microscope shows that most of the copper powder pressed and fixed in the holes has a long diameter of 1 μm to 2 μm.
m.

Reference Example 2 Reference Example 1 was placed in a copper cylindrical container (inner diameter 32 mm × length 50 mm) having a capacity of 40 ml.
Fourteen ring-shaped bonded magnets (weight: 18 g) produced in the same manner as in step A of (1) were accommodated such that the central axis direction was parallel to the central axis direction of the cylindrical container. Also,
Copper pipe (diameter 8mm x length 45m) in the hollow part of the magnet
m) was inserted and arranged. Further, a ceramic medium (abrasive grains mainly composed of aluminum oxide are sintered to be solidified into granules having a long diameter of 5 mm to 7 mm; produced: true specific gravity 2.9 to
3.1 g / cm ³ ) and a corn cob (major axis: 1 mm) having aluminum oxide powder adhered to the surface with tallow
A mixture of 10% by weight of aluminum oxide # 800 (having a major axis of 20 μm or less) and 3% by weight of tallow mixed with a corn cob of about 2 mm in a volume ratio of 1: 1. (The total capacity including the ring-shaped bonded magnet is 36 vol.
%). Using a rotary ball mill, the cylindrical container was rotated at 150 rpm about its central axis for 2 hours. As a result, a ring-shaped bonded magnet in which the aluminum oxide powder was press-fitted and fixed in the holes was obtained. From the surface observation with an electron microscope, it was found that most of the aluminum oxide powder pressed and fixed in the pores had a major axis of about 5 μm.

Example 3: Using a ring-shaped bonded magnet produced in the same manner as in Step A of Reference Example 1, a ceramic medium of Reference Example 2 was prepared with a diameter of 0.6 mm and a length of 0.6 m.
m, except that the material was changed to a short columnar copper powder-producing substance (cut wire).
A ring-shaped bonded magnet was obtained in which copper powder and aluminum oxide powder produced from a short columnar copper powder-producing substance were press-fitted and fixed in the holes. From observation of the surface with an electron microscope, most of the copper powder pressed and fixed in the pores has a major axis of 1 μm to 2 μm.
μm, and it was found that most of the aluminum oxide powder had a major axis of about 5 μm.

Example 4: A corn obtained by using a ring-shaped bonded magnet produced in the same manner as in step A of Reference Example 1 and applying a ceramics medium and aluminum oxide powder to the surface with tallow in Reference Example 2. The cob of
30vol of the volume in the container was mixed at a volume ratio of 1: 1.
0.6mm in diameter x 0.6mm in length instead of%
Corn cob impregnated with beef tallow (major axis 1)
A mixture prepared by kneading 1.4% by weight of beef tallow with respect to a corn cob having a diameter of 2 mm to 2 mm) in a volume ratio of 1: 1, 30 vol% of the volume in the container was accommodated, and the processing time was 4 hours.
Processing was performed in the same manner as in Reference Example 2 except that the time was changed, and copper powder generated from the short columnar copper powder-forming substance was pressed into the holes and fixed, and the entire magnet surface was made of copper powder (copper). A ring-shaped bonded magnet having a coating layer (using powder as a forming source) was obtained. Observation of the fracture surface with an electron microscope showed that most of the copper powder pressed and fixed in the holes had a major diameter of 1 μm.
It was found that the thickness was about 2 μm.

Example 5: A corn obtained by using a ring-shaped bonded magnet produced in the same manner as in Step A of Reference Example 1 and applying a ceramics medium and aluminum oxide powder to the surface with tallow in Reference Example 2. The cob of
30vol of the volume in the container was mixed at a volume ratio of 1: 1.
0.6mm in diameter x 0.6mm in length instead of%
The same procedure as in Reference Example 2 was carried out except that the short columnar copper powder-producing substance (the wire was cut) was accommodated at 30 vol% of the volume in the container, and the pores were formed from the short columnar copper powder-producing substance. The obtained copper powder was press-fitted and fixed, and a ring-shaped bonded magnet having an adhered layer made of copper powder (using copper powder as a forming source) on the entire magnet surface was obtained. Observation of the fracture surface with an electron microscope revealed that most of the copper powder pressed into and fixed to the holes had a major axis of about 1 μm to 2 μm.

[0050]

According to the present invention, a compact having a hole on its surface and a metal powder-generating substance having a major diameter of 0.05 mm to 10 mm for producing metal powder are accommodated in a processing vessel, and the contents are moved in the processing vessel. By supplying energy, a metal powder having a major axis of 0.1 μm to 10 μm is generated from the metal powder generating material, and the generated metal powder is pressed into the hole to be fixed. According to the sealing method, the metal powder generating material has a role of generating the metal powder by collision between the metal powder generating materials, collision with the compact, collision with the inner wall of the processing container, and the like, Plays a role as a medium for press-fitting into the hole portion, and these roles combine to exhibit an excellent sealing effect. Therefore, it is possible to selectively, easily and dryly perform a process of exhibiting an excellent sealing effect on the voids of the molded body such as the voids on the surface of the bonded magnet, which affects the surface accuracy of the molded body. And a corrosion resistant film such as a plating film having excellent dimensional accuracy can be formed in a later step.

[Brief description of the drawings]

FIG. 1 is a partial perspective view of an example of an apparatus used in the surface treatment method of the present invention.

FIG. 2 is a view showing a method for arranging a rod-shaped member on a workpiece according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing container 2-a, 2-b Roller 3 Ring-shaped bonded magnet 4 Metal powder generating material 5 Rod-shaped member

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Fumiaki Kikui 2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka Prefecture Inside the Yamazaki Works, Sumitomo Special Metals Co., Ltd. (72) Masahiro Asano Egawa, Shimamoto-cho, Mishima-gun, Osaka 2-15-17 Sumitomo Special Metals Co., Ltd. Yamazaki Works (72) Inventor Takahiro Isozaki 2-15-17 Egawa Shimamoto-cho, Mishima-gun, Osaka Sumitomo Special Metals Co., Ltd. Yamazaki Works F term 4K017 AA02 BB05 DA04 EA03 4K018 AA27 KA46 5E040 AA04 CA01 HB17 NN01

Claims (15)

[Claims] 1. A molded product having a hole portion on its surface and a metal powder-generating substance having a major diameter of 0.05 mm to 10 mm for producing metal powder are accommodated in a processing container, and the stored object is moved in the processing container. By supplying energy, a metal powder having a long diameter of 0.1 μm to 10 μm is generated from the metal powder generation material, and the generated metal powder is pressed into and fixed to the hole. Processing method. 2. The method according to claim 1, wherein the metal powder-forming substance is a copper powder-forming substance that forms copper powder. 3. The method according to claim 1, wherein the metal powder forming substance has a needle shape and / or a column shape. 4. The method according to claim 1, further comprising storing the fat or oil in a processing container. 5. The method according to claim 4, wherein the fats and oils are stored in the treatment container using a vegetable medium containing the fats and oils. 6. The method according to claim 4, further comprising storing the inorganic powder in a processing container. 7. The method according to claim 6, wherein the inorganic powder and the fat and oil are accommodated in a treatment container using a vegetable medium having the surface thereof coated with the inorganic powder and the fat and oil. 8. The vegetable medium, wherein the vegetable medium is vegetable debris, sawdust,
The method according to claim 5 or 7, wherein the method is at least one selected from fir, bran, fruit shell, and corn cob. 9. The method according to claim 1, wherein the molded body having a hole on the surface is a bonded magnet. 10. The sealing method according to claim 9, wherein the bonded magnet is a ring-shaped bonded magnet. 11. The hole according to claim 1, wherein kinetic energy is supplied to the container by applying vibration and / or stirring to the container in the processing container. Processing method. 12. The method according to claim 11, wherein the processing container is a processing chamber of a barrel device. 13. A ring-shaped bonded magnet is accommodated in a cylindrical processing container such that the central axis thereof is parallel to the central axis of the cylindrical processing container. 2. A kinetic energy is supplied to the stored object by rotating the container.
0. The sealing method according to item 0. 14. The sealing method according to claim 13, wherein a rod-shaped member is inserted through the hollow portion of the ring-shaped bonded magnet so as to be parallel to the central axis direction. 15. A bonded magnet which has been subjected to a sealing treatment by the sealing treatment method according to claim 1.