JPH08339917A - Magnet of motor - Google Patents

Abstract

PURPOSE: To provide the magnet of a motor which prevents the faults from occurring owing to the formation of a tin compound. CONSTITUTION: An electrodeposition painted film 2 of rust preventing paint, which does not contain tin, is formed on the outer surface of a magnet 1. The film is formed by using electrodeposition paint suitably mixed with hydrophilic solvent or using an ultraviolet hardening type electrodeposition paint, whose painted film is hardened by utilizing ultraviolet energy. The painted film can be formed by painting process or by baking finish process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor used for a magnetic disk drive spindle motor, a motor of a rotary polygon mirror drive, and the like, and more particularly to a rustproof motor magnet.

[0002]

2. Description of the Related Art In recent years, there has been a demand for miniaturization and higher performance in office automation equipment or audiovisual equipment, and in response thereto, performance is improved by narrowing the gap between the armature and the magnet of the motor. In motors for such motors, magnetic disk drive devices, and polygon mirror rotation drive devices, magnets such as neodymium, iron, and boron are subjected to rust prevention treatment such as electrodeposition coating.

Further, the magnets of motors used in the aerospace industry such as a space station and motors used in a special environment in a humid environment are often subjected to electrodeposition coating also as anti-corrosion treatment. .

A conventional magnet for a magnetic disk drive motor will be described below with reference to FIG.
In FIG. 2, 11 is a bracket, 12 is an iron core fixed to the outer periphery of the tubular portion, 13 is a shaft rotatably supported on the inner periphery of the tubular portion of the bracket 11, and 14 is the shaft 1.
A cup-shaped rotor hub fixed to 3, a magnet 15 arranged on the inner circumference of the rotor hub 14 so as to face the iron core 12, and a coil 16 wound around the iron core 12. Reference numeral 17 is a powder coating film formed on the surface of the iron core 12 for insulating treatment, 18 is an anticorrosion coating film formed on the surface of the iron core 12 facing the magnet 15, and 19 is formed on the outer surface of the magnet 15. It is an electrodeposition coating film.

The powder coating film 17 is formed by directly spraying a powdery insulating material made of a resin material such as epoxy resin on the surface of the iron core 12 formed by laminating magnetic materials, and then heat-treating the powder. Is formed by Also, iron core 1
The powder coating film 1 is provided on the outer peripheral surface facing the second magnet 15.
The rust preventive coating film 18 is formed by brush-coating a varnish such as knitol without forming 7.

An electrodeposition coating film 19 on the outer surface of the magnet 15
Is to put a water-soluble or water-dispersible paint in the bath, immerse the magnet 15 in the bath, attach an electrode to the conductive magnet 15 to be coated, and energize between the electrode and the counter electrode attached to the bath. The held resin particles are moved to the magnet 15 by electrophoresis to be deposited, washed with water, and baked to form the resin particles.

The surface of the magnet 15 is often subjected to cationic electrodeposition coating. The cationic electrodeposition coating uses an aqueous solution obtained by neutralizing a synthetic resin having a base such as an amino group with an organic acid or an inorganic acid or a colloidal dispersion type resin as a vehicle. Table 1 shows examples of electrodeposition coating materials.

[0008]

[Table 1]

The tin which is not shown in Table 1 is 200 to
It contains about 500 ppm. This is a catalyst for accelerating the curing of the paint, and the coating film of the electro-deposited magnet generally contains tin.

[0010]

However, in the magnet coated with electrodeposition as described above, tin contained in the electrodeposition coating is activated by chlorine and water to form a tin compound and is gasified. There is a problem in that the magnetic disk surface or the polygon mirror surface is fogged in the magnetic disk driving device or the rotary polygon mirror driving device due to the adsorption to the peripheral surface.

In view of the above conventional problems, it is an object of the present invention to provide a magnet for a motor that does not cause any trouble due to the formation of tin compounds.

[0012]

The motor magnet of the present invention is characterized in that an electrodeposition coating film of a rust preventive paint containing no tin is formed on the outer surface.

Preferably, the electrodeposition coating is carried out by using an electrodeposition coating containing a hydrophilic solvent or an ultraviolet curing type electrodeposition coating which cures the coating film by utilizing ultraviolet energy.

Further, a coating treatment may be applied with a tin-free coating material, or a baking coating treatment may be performed with a tin-free coating material.

[0015]

According to the present invention, since the electrodeposition coating film of the rust preventive paint is formed on the outer surface, the film thickness can be accurately controlled by the electrodeposition coating and the gap between the magnet and the motor iron core can be narrowed. In addition to improving performance, it is more mass-producible than plating and can be rust-proofed at a low cost, and since the rust-preventive paint does not contain tin, tin compounds are generated and There is no risk of fogging on the surface,
It is possible to prevent the occurrence of obstacles due to fogging.

In particular, when an electrodeposition coating containing a hydrophilic solvent is used, a coating film is easily attached even if it does not contain tin, and when an ultraviolet curing type electrodeposition coating is used, it is possible to obtain a quick coating without containing tin. A stable coating film can be obtained.

If a coating treatment or a baking coating treatment is carried out to form a tin-free rustproof coating film, it can be formed inexpensively with mass productivity.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a motor magnet of the present invention will be described below with reference to FIG.

(Embodiment 1) FIG. 1 shows a magnet of a motor of this embodiment, 1 is a magnet, and 2 is an electrodeposition coating film made of a rust preventive paint formed on the surface thereof.

Since tin contained in a general electrodeposition coating is for accelerating curing, the process of electrodeposition coating is almost the same as the conventional coating process even with a tin-free coating. An example of the process of applying the electrodeposition coating to the magnet 1 with the electrodeposition coating material containing no tin will be described below.

The electrodeposition coating is a cationic type electrodeposition coating, and since it does not contain tin, it is difficult for the coating to adhere, so a hydrophilic solvent is added. A water-soluble or water-dispersible tin-free cationic electrodeposition paint is placed in the bath, the magnet 1 is immersed in the bath, and a cathode electrode is attached at an appropriate position on the outer periphery of the magnet 1 so that a pole attached to the diaphragm chamber of the bath is attached. When a plate is used as an anode and a direct current is applied between the plates, charged resin particles move to the magnet 1 by electrophoresis and are deposited.
This is washed with water, dried and baked. The drying is effective for removing the solvent, hydrogen gas, and water existing in the electrodeposition coating film from the film.

When the magnet 1 is electrodeposited, a cation type electrodeposition paint is often used. The cationic electrodeposition coating uses, as a vehicle, an aqueous solution or a colloidal dispersion type resin in which a synthetic resin having a base such as an amino group is neutralized with an organic acid or an inorganic acid. If the bath composition, temperature, and current-carrying conditions are controlled to appropriate levels, the thickness of the coating film can be easily adjusted, and an electrodeposition coating film with little variation can be obtained. The thickness can be controlled to 5 to 40 μm and the tolerance ± 10 μm. An electrodeposition coating film is also attached to the inner circumference of the magnet 1,
If the coating film is managed, the gap between the magnet 1 and the motor iron core can be narrowed, and the output characteristics of the motor can be improved without causing any problems in the motor assembly characteristics.
In addition, the baking temperature must be set high for tin-free paints.

By thus subjecting the magnet of the motor to electrodeposition coating with a paint that does not contain tin, for example, in a magnetic disk drive motor, no gas is generated by tin even in a sealed state, and the surface of the magnetic disk is It will not fog up by being adsorbed on. Similarly, in the polygon mirror driving motor, the magnet is not electrodeposited without containing tin so that the gloss of the mirror surface of the polygon mirror is not deteriorated.

(Example 2) In the case of a tin-free electrodeposition coating, it is necessary to set a high baking temperature, and therefore a higher temperature than the curing temperature of a general electrodeposition coating and a long time are required. Higher furnace management and energy costs. Therefore, in this example, the magnet 1 was subjected to electrodeposition coating using an ultraviolet-curing type tin-free electrodeposition coating composition capable of curing the coating film in a short time by utilizing ultraviolet energy.

(Embodiment 3) In this embodiment, a rust preventive paint is applied to the magnet 1 by painting. Painting is a process of sol (coating liquid) to gel (coating) transfer, and due to the change in the molecular weight of the coating film main element during the transfer process
There are solution-type paints whose molecular weight does not change and cross-linked paints whose molecular weight increases. The paint used for the rust prevention of the magnet 1 is a cross-linking paint, and the cross-linking reaction of the baked paint is completed at the baking temperature, and the reaction is not promoted at a temperature lower than that. Therefore, the coating properties of the baking paint are relatively stable over a long period of time as compared with the naturally drying paint. In this embodiment, the magnet 1 is baked and coated with a paint that does not contain tin, so that it is necessary to set the baking temperature to a high level, as in the case of electrodeposition coating.

By thus applying the baking coating treatment to the magnet 1 of the motor using the tin-free paint, no gas is generated by tin even when the magnetic disk drive motor is hermetically sealed, and the surface of the magnetic disk is not generated. It does not cause the disc to be fogged by and is not fogged, and similarly, even in the polygon mirror driving motor, the gloss of the mirror surface of the polygon mirror is not deteriorated.

The rust-preventive coating film can be formed by spray coating with a paint that does not contain tin.

As described above, by coating the outer surface of the magnet 1 with a paint that does not contain tin by spray coating or baking coating, a rust preventive treatment film that does not cause fogging on the mirror surface of the disk or polygon mirror. Can be mass-produced at low cost.

[0029]

According to the magnet of the motor of the present invention,
As is clear from the above description, since the electrodeposition coating film of rust preventive paint is formed on the outer surface, the film thickness can be accurately controlled by electrodeposition coating and the gap between the magnet and the motor iron core can be narrowed. In addition to improving performance, it is more mass-producible than plating and can be rust-proofed at a low cost, and since the rust-preventive paint does not contain tin, tin compounds are generated and There is no fear of fogging on the surface, and in particular in a magnetic disk drive or a rotary polygon mirror drive, it is possible to prevent the phenomenon of fogging of the magnetic disk surface or polygon mirror surface, etc. it can.

Further, when the electrodeposition coating composition to which the hydrophilic solvent is added is used, the coating film is easily attached even if it does not contain tin, and when the ultraviolet curing type electrodeposition coating composition is used, it does not contain tin. A stable coating film can be quickly obtained.

Further, if a coating treatment or a baking coating treatment is performed to form a tin-free anticorrosion coating film, it can be formed inexpensively with mass productivity.

[Brief description of drawings]

FIG. 1 shows a magnet of a motor in an embodiment of the present invention, (a) is a perspective view, and (b) is a sectional view taken along the line I-I of (a).

FIG. 2 is a cross-sectional view of a motor of a conventional magnetic disk drive device.

[Explanation of symbols]

 1 magnet 2 electrodeposition coating film

Claims (5)

[Claims] 1. A magnet for a motor, characterized in that an electrodeposition coating film of anticorrosive paint containing no tin is formed on the outer surface. 2. A magnet for a motor according to claim 1, wherein electrodeposition coating is applied using an electrodeposition coating containing a hydrophilic solvent. 3. The magnet for a motor according to claim 1 or 2, wherein an electro-deposition coating is applied using an ultraviolet-curing type electro-deposition paint which cures the coating film by utilizing ultraviolet energy. 4. A magnet for a motor, the outer surface of which is coated with a paint that does not contain tin. 5. A magnet for a motor, characterized in that the outer surface of the magnet is baked and coated with a paint containing no tin.