JP2002226998A - Electrodeposition coating method and apparatus for rare earth bond magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrodeposition coating film with high corrosion resistance by preventing the generation of electrodes or the film. SOLUTION: An anode 18 is immersed into an electrodeposition coating tank 16 stored with an electrodeposition solution 14. The inside of the electrodeposition coating tank 16 is stepwise provided with a plurality of belt conveyers 22, 24 and 26 as cathodes capable of being mounted with rare earth bond magnet stocks 12 and conveying them. The rare earth bond magnet stocks 12 fallen from the downstream edge of the belt conveyer onto the upstream side are transferred to the belt conveyer on the downstream side and are successively conveyed to the downstream side. Prescribed voltage is applied to the space between the belt parts 28 of the belt conveyers 22, 24 and 26 and the anode 18, so that the rare earth bond magnet stocks 12 in contact with the belt parts 28 are energized to electrodeposit the whole of the surfaces with electrodeposition coating films.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for electrodeposition coating of a rare earth bonded magnet, and more particularly, to an electrodeposition coating method for a rare earth bonded magnet material while transferring the material between the plurality of belt conveyors. The present invention relates to a method and an apparatus for electrodeposition coating of a rare earth bonded magnet for electrodepositing an electrodeposition coating film by coating.

[0002]

2. Description of the Related Art A mixture of a powder of a magnetic material containing one or more rare earth elements such as Sm, Nd, Pr and the like and a resin binder in a required ratio is formed into a required shape by a press. Rare-earth bonded magnet materials used in, for example, motor rotors obtained by heat-curing the sapphire material contain raw material components that are easily oxidized, and therefore rust is likely to occur over time if the surface is bare. Therefore, if it is used as it is for a motor part or the like, it causes a decrease in durability and a cause of failure. Therefore, in order to prevent rust, a measure is generally taken to cover the surface of the rare earth bonded magnet material with a resin film by an electrodeposition coating method.

In the electrodeposition coating method, a solution in which an electrodeposition coating material (resin) is dissolved is stored in a storage tank at a required level, and the rare earth bonded magnet material held by a holding electrode is immersed in the solution. Then, by applying a predetermined voltage to the electrode facing the storage tank, a current is applied to the rare-earth bonded magnet material through a contact portion with the holding electrode, and a resin film having a predetermined thickness is formed on the surface of the magnet material. (Electrodeposition coating film).

[0004]

In the above-mentioned electrodeposition coating, the rare earth bonded magnet material is held in a state where the holding electrode is in contact with the outer surface, and therefore, the contact portion between the holding electrode and the rare earth bonded magnet material is held. The electrodeposition coating film is not electrodeposited on
Due to the contact traces (electrode traces), there was a problem that the corrosion resistance was lowered or the magnetic powder flowed out. In addition, there is a limitation on the shape of a component that can withstand holding of the holding electrode. For example, there is a disadvantage that it is not suitable for a component having low strength and thinness, a component having a small or large size, or a component that is not annular.

[0005] As a method of forming a resin film on the surface of a rare-earth bonded magnet material, spray coating or dip coating is known in addition to electrodeposition coating. It is possible to form a resin coating on a minute or maximal part or a part that is not annular. However, in spray coating, it is possible to secure practically satisfactory corrosion resistance by selecting an appropriate resin paint and recoating, but depending on the shape of a complicated part, the coating is liable to be enlarged and a thin coating is formed. In such a case, it is difficult to maintain the uniformity of the film thickness, and there is a disadvantage that the dimensional accuracy is reduced. In addition, spray coating increases the loss of paint and necessitates the reversal of parts, which increases the number of processes and increases the cost. In addition, although dip coating has the advantage of being inexpensive and requires only a small number of steps, it is pointed out that it has poor corrosion resistance as compared with electrodeposition coating and spray coating, and has low uniformity of film thickness and low dimensional accuracy.

That is, in such a situation, an electrodeposition coating method capable of forming a resin film having a uniform film thickness and obtaining high corrosion resistance without limiting the properties and size of the target component. It is the present situation that is desired.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks inherent in the prior art, and has been proposed in order to solve the problem suitably. Accordingly, an object of the present invention is to provide a method and an apparatus for electrodeposition coating of a rare-earth bonded magnet that can obtain high corrosion resistance.

[0008]

[Means for solving the problems] To overcome the above-mentioned problems,
In order to suitably achieve the intended purpose, the electrodeposition coating method of the rare earth bonded magnet according to the present invention is a method of electrodepositing an electrodeposition coating film on the surface of the rare earth bonded magnet material, and The magnet material is sequentially transferred by dropping and transferring the magnet material from an upstream belt conveyor that transfers the rare earth bonded magnet material in a state of being immersed in the stored electrodeposition solution to a downstream belt conveyor. An electrodeposition coating film is electrodeposited on the surface of the rare earth bonded magnet material by coating.

Further, in order to overcome the above-mentioned problems and appropriately achieve the intended object, an electrodeposition coating apparatus for a rare earth bonded magnet according to another invention of the present application comprises an electrodeposition coating film on the surface of a rare earth bonded magnet material. An electrodeposition coating tank in which an electrodeposition solution is stored, and disposed inside the electrodeposition coating tank, for transferring the rare-earth bonded magnet material in a state of being immersed in the electrodeposition solution. A plurality of belt conveyors, wherein the plurality of belt conveyors are arranged such that the rare-earth bonded magnet material is dropped and transferred from an upstream belt conveyor to a downstream belt conveyor, and the plurality of belt conveyors are electrically connected to the rare-earth bonded magnet material. The apparatus is characterized in that an electrodeposition coating film is electrodeposited on the surface of the rare earth bonded magnet material by electrodeposition coating while being transported by each belt conveyor while being immersed in the electrodeposition solution.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a method and an apparatus for electrodeposition coating of a rare earth bonded magnet according to the present invention will be described with reference to preferred embodiments.

FIG. 1 shows a schematic configuration of an electrodeposition coating apparatus according to an embodiment. The rare-earth bonded magnet material 12 to be subjected to electrodeposition coating by the electrodeposition coating apparatus 10 according to the embodiment is, for example, Nd-Fe-B, Sm-Fe-N, Sm
-Rare earth bonded magnet material powder such as Co and nylon 1
2. A material obtained by compression-molding a material obtained by mixing a resin binder such as nylon 6, nylon 66, polyphenyl sulfide (PPS), epoxy, or the like at a required ratio into a ring shape.

The electrodeposition coating apparatus 10 includes an electrodeposition coating tank 16 in which a required amount of the electrodeposition solution 14 is stored.
(Electrode) 18 is immersed. Further, inside the electrodeposition paint tank 16, a plurality of (three in this embodiment) belt conveyors 22, 24, 26 as cathodes (electrodes) capable of carrying a plurality of rare-earth bonded magnet materials 12 thereon in a stepwise manner. Provided,
Each of the conveyors 22, 24, 26 is entirely immersed in the electrodeposition solution 14. Further, each belt conveyor 22, 24, 2
As shown in FIG. 1, the transfer upstream end of the belt conveyor installed on the downstream side is separated from the downstream end of the belt conveyor on the upstream side in the transfer direction by a predetermined height as shown in FIG. The rare-earth bonded magnet material 1 that has been dropped from the downstream end of the belt conveyor on the upstream side.
2 is transferred to a downstream belt conveyor and sequentially transferred to the downstream side. In addition, as the electrodeposition solution 14, for example, an epoxy resin: 9 to 11 wt%, a solvent: 3 to
5 wt%, pigment: 3-5 wt%, pure water: 70-80 wt
% Is preferably used, but may have another composition. Also, as described above, the belt conveyor
By providing more than one base, the magnet material 1
The position where 2 can be received changes, so that unevenness of the coating film hardly occurs.

The belt portion 28 on which the rare-earth bonded magnet material 12 is placed and transported in each of the belt conveyors 22, 24 and 26 is made of a conductive material (for example, SUS304 or the like, but is made of another material. And a predetermined voltage is applied between the anode 18 and the belt portion 28 so that the rare-earth bonded magnet material 12 contacting the belt portion 28 is energized, and The electrodeposition coating film is configured to electrodeposit over the entire surface. Also,
The portions of the belt conveyors 22, 24, 26 other than the belt portion 28 are covered with a non-conductive material or formed of a non-conductive material so that the electrodeposition coating film is not electrodeposited on the surface. It is composed. The mounting surface of the belt conveyor on which the magnet material 12 is mounted is not limited to the mesh shape, but may be any surface having irregularities other than a flat surface.

The electrodeposition conditions (set voltage, set current, conveyor speed, etc.) depend on the target rare-earth bonded magnet material 1.
The composition is appropriately set depending on the composition and size of No. 2, the thickness of the electrodeposition coating film to be electrodeposited, and the like.

By providing the plurality of belt conveyors 22, 24, 26 in a step-like manner as described above, when the rare-earth bonded magnet material 12 is transferred from the upstream belt conveyor to the downstream belt conveyor. By dropping and rotating, the contact area between the belt portion 28 of the belt conveyors 22, 24 and 26 and the rare-earth bonded magnet material 12 changes, so that electrode marks are not generated on the electrodeposition coating film. . The lower portion of each of the belt conveyors 22, 24, 26 has a removal contacting the surface (the surface on which the rare-earth bonded magnet material 12 is placed) of the belt portion 28 which is inverted at the downstream end and travels upstream. A removing brush 30 is provided as a means, and the electrodeposited coating film electrodeposited on the surface of the belt portion is removed by the brush 30 so that the rare-earth bonded magnet material 12 comes into direct contact with the surface of the belt portion. .

Above the electrodeposition coating tank 16, there is provided a carry-in conveyor 32 which drops the rare-earth bonded magnet material 12 from the previous step to the first belt conveyor 22 on the most upstream side and transfers it. Further, on the side wall (the left side wall in FIG. 1) on the downstream side in the transfer direction in the electrodeposition paint tank 16, a carry-out port 34 is opened at a position below the third belt conveyor 26 on the most downstream side,
The upstream end of the unloading conveyor 36 extends into the electrodeposition coating tank 16 via the unloading port 34. And
The rare-earth bonded magnet material 12 that has fallen from the downstream end of the third belt conveyor 26 is configured to be transferred to a carry-out conveyor 36 and transferred to a subsequent process.

Below the electrodeposition paint tank 16, a liquid storage tank 38 for storing the electrodeposition solution 14 flowing out from the carry-out port 34.
Is disposed, and the electrodeposition solution 14 in the liquid storage tank is returned to the electrodeposition coating tank 16 via the pump 40 so as to keep the level of the electrodeposition solution in the coating tank constant. Is done.
By circulating the electrodeposition solution 14 between the electrodeposition coating tank 16 and the liquid storage tank 38, the electrodeposition solution 14 in the electrodeposition coating tank is agitated so that the liquid concentration becomes uniform. I have.

[0018]

Next, the operation of the electrodeposition coating apparatus according to the embodiment will be described in relation to an electrodeposition coating method. A plurality of rare-earth bonded magnet materials 12 molded from a material in which a rare-earth bonded magnet material powder and a resin binder are mixed at a required ratio are subjected to pretreatment such as cleaning with pure water, and then loaded on the carry-in conveyor 32. Placed and transported. Each of the rare-earth bonded magnet materials 12 falls from the downstream end of the carry-in conveyor 32 into the interior of the electrodeposition paint tank 16 and is placed on the upstream belt portion 28 of the first belt conveyor 22.
The whole is immersed in the electrodeposition solution 14 and transferred to the downstream side. The anode 18 and the first belt conveyor 22
A predetermined voltage is applied between the belt member 28 and the rare earth bonded magnet material 12 that is in direct contact with the belt portion 28, and an electrodeposition coating film is applied to the entire surface of the magnet material 12. Is electrodeposited.

The rare earth bonded magnet material 12 that has fallen from the downstream end of the first belt conveyor 22 is placed on the upstream belt portion 28 of the second belt conveyor 22 and is completely immersed in the electrodeposition solution 14. While being transferred to the downstream side, an electrodeposition coating film is electrodeposited on the surface in the same manner as described above. In this case, when the rare-earth bonded magnet material 12 is transferred from the first belt conveyor 22 to the second belt conveyor 24 and falls and rotates, the contact portion of the rare-earth bonded magnet material 12 with the belt portion 28 is formed. Is changed, and the electrodeposition coating film is electrodeposited on the contact portion with the belt portion 28 that has not been electrodeposited during the transfer on the first belt conveyor 22. Also, at the time of delivery from the second belt conveyor 24 to the third belt conveyor 26, the contact portion of the rare-earth bonded magnet material 12 with the belt portion 28 similarly changes, so that the electrodeposition coating film of the rare-earth bonded magnet material 12 The contact trace (electrode trace) with the belt portion 21 is prevented from being attached. That is, since the rare-earth bonded magnet material 12 is always in contact with the belt portion 28 of the belt conveyor at the same position, the electrodeposition coating film is not formed on that portion, and rust is generated from the contact trace and the outflow of the magnet powder is prevented. This can be reliably prevented from occurring.
Also, the rare-earth bonded magnet material 12 is transferred to the belt conveyor 22,
Since the electrodeposition is applied while being transferred at 24 and 26, no load is applied to the magnet material 12, and the electrodeposition coating film is efficiently deposited on the rare earth bonded magnet material 12 having various shapes, dimensions and properties. Can be.

Each of the rare-earth bonded magnet materials 12 that have been subjected to the electrodeposition coating as described above is attached to the third belt conveyor 2.
6 is delivered to the unloading conveyor 36 from the downstream end, is unloaded from the electrodeposition coating tank 16 by the conveyor 36, and is transferred to a subsequent process. This rare earth bonded magnet material 12
After washing with pure water and baking and drying at the set temperature, by natural cooling, the electrodeposition coating film with a uniform thickness and no electrode traces on the surface is electrodeposited and baked, has high corrosion resistance A rare earth bond material is obtained.

Here, each of the belt conveyors 22, 24,
At 26, an electrodeposition coating film is also electrodeposited on the surface of the belt portion 28, but since the electrodeposition coating film is conductive unless it is baked, the rare earth bond is applied to the belt portion 28 via the electrodeposition coating film. Even if the magnet material 12 is in contact, an electrodeposition coating film is electrodeposited on the surface of the material 12. In the embodiment, the electrodeposition coating film electrodeposited on the surface of the belt portion 28 is removed before the rare-earth bonded magnet material 12 is put on by the removing brush 30.
Is always in direct contact with the belt portion 28 to achieve efficient electrodeposition.

[0022]

Test Example An annular rare earth bonded magnet material having an outer diameter of 25 mm, an inner diameter of 23 mm, and an axial length of 7 mm was formed from a mixture of Nb-Fe-B and nylon 12. Then, this magnet material was electrodeposited by the electrodeposition coating apparatus of the example using an epoxy resin as the electrodeposition paint. The electrodeposition conditions at this time were set voltage: 250 V, set current: 1 A, baking drying temperature: 180 ° C., and baking drying time: 30 minutes.

With respect to a plurality of rare earth bonded magnet materials electrodeposited with an electrodeposition coating film under the above-described conditions, 80 ° C. × 95% × 3
A 36-hour wet test was performed. As a result, it was confirmed that no rust was generated for all the materials and sufficiently high corrosion resistance was obtained.

[0024]

FIG. 2 schematically shows an electrodeposition coating apparatus according to a first alternative embodiment. Since the basic structure of the apparatus is the same as that of the above-described embodiment, different parts will be described. Will be described only. The same members described above are denoted by the same reference numerals.

In the first alternative embodiment, the third belt conveyor 26 (a belt conveyor disposed at the most downstream side)
A lifting conveyor 42 that is inclined upward from the upstream side to the downstream side is disposed on the downstream side. The upstream portion of the lifting conveyor 42 is positioned so as to be spaced apart and overlap below the downstream portion of the third belt conveyor 26, and the downstream portion extends above the electrodeposition paint tank 16. Be composed. Therefore, the rare-earth bonded magnet material 12 dropped from the downstream end of the third belt conveyor 26
Is transferred to the lifting conveyor 42 and carried out of the electrodeposition paint tank 16 by the conveyor 42. Then, the rare-earth bonded magnet material 12 that has fallen from the downstream end of the lifting conveyor 42 is transported toward a subsequent process by the transport conveyor 44 disposed outside the electrodeposition paint tank 16.

That is, in the first alternative embodiment, the rare earth bonded magnet material 12 which has been electrodeposited is lifted and carried out of the electrodeposition coating tank 16 by the lifting conveyor 42. There is no need to provide a liquid storage tank or the like, and the configuration can be simplified. In this case, since the electrodeposition solution 14 in the electrodeposition paint tank is not stirred, it is recommended to provide an appropriate stirring means. For example, a diffuser pipe 48 connected in a communicating state between lower ends of a pair of pipes 46, 46 spaced apart in the front-rear direction is disposed near the bottoms on both sides in the width direction of the inside of the electrodeposition paint tank 16, respectively. The supplied air is diffused from a plurality of holes (not shown) formed in the diffuser tube 48 to stir the electrodeposition solution 14 stored in the electrodeposition paint tank 16 to make the liquid concentration uniform. Means can be adopted. By providing three or more belt conveyors and providing a mounting surface with an uneven surface such as a mesh, even if there is a contact portion with the magnet material 12, coating film unevenness is further improved.

FIG. 3 schematically shows an electrodeposition coating apparatus according to a second alternative embodiment. The basic structure of the apparatus is the same as that of the above-mentioned first alternative embodiment, and is therefore different. Only the parts will be described. The same members described above are denoted by the same reference numerals.

In the second alternative embodiment, all of the belt conveyors 22, 24, 26 functioning as cathodes disposed inside the electrodeposition coating tank 16 are each arranged from the upstream side to the downstream side. While being arranged in a posture inclined upward, the transfer upstream end of the belt conveyor installed on the downstream side is separated from the transfer downstream end of the belt conveyor on the upstream side in the transfer direction by a predetermined height. It is positioned so as to overlap. Then, similarly to the above-described embodiment, the rare-earth bonded magnet material 12 dropped from the downstream end of the upstream belt conveyor is transferred to the downstream belt conveyor and sequentially transferred to the downstream side.

That is, in the second alternative embodiment, the upstream end level and the downstream end level of each of the belt conveyors 22, 24, 26 are the same without arranging the plurality of belt conveyors 22, 24, 26 in a stepwise manner. Since the height can be set, the height of the entire apparatus (the height of the electrodeposition paint tank 16) can be set short, and the size can be reduced.

The polarity in the electrodeposition coating has been described in the embodiment when the rare earth bonded magnet material is a cathode (cation electrodeposition), but the rare earth bonded magnet material is an anode (anion electrodeposition).
It is also possible to adopt a configuration in which: When the rare earth bonded magnet material is used as the anode, the cathode (electrode) is disposed in the electrodeposition paint tank in a state of being immersed in the electrodeposition solution. Further, the shape of the rare earth bonded magnet material to be subjected to the electrodeposition coating is not limited to the annular shape, but may be various shapes, dimensions and properties. Furthermore, the number of belt conveyors disposed inside the electrodeposition paint tank may be at least two, but may be four or more. The posture of each belt conveyor may be any as long as the rare-earth bonded magnet material falling from the downstream end of the upstream belt conveyor can be transferred so as to be placed on the downstream belt conveyor. Furthermore, the removing means is not limited to the brush, but may be a scraper or the like.
A belt conveyor capable of removing the electrodeposition coating film can be appropriately used.

[0031]

As described above, according to the method and apparatus for electrodepositing a rare-earth bonded magnet according to the present invention, the rare-earth bonded magnet material is immersed in the electrodeposition solution while being transported by the belt conveyor. Since the electrodeposition coating film is electrodeposited, the electrodeposition coating film can be suitably applied to parts having a weak strength that cannot be held by the holding electrode, such as thin parts, small and large parts, or parts that are not annular. It can be worn, and the target range is expanded. In addition, when the rare-earth bonded magnet material falls between a plurality of belt conveyors and is delivered, the contact area of the material with the conveyor changes, so that the contact marks (electrode marks) on the rare-earth bonded magnet material with the belt conveyor are changed. It can be reliably prevented from remaining. That is, it is possible to prevent contamination due to outflow of magnetic powder from electrode traces and the like,
High corrosion resistance is obtained by reliably preventing rust. Furthermore,
Since the electrodeposition coating is used, an electrodeposition coating film having a uniform thickness can be electrodeposited on the surface of the rare-earth bonded magnet material, and a product having high dimensional accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an electrodeposition coating apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an electrodeposition coating apparatus according to a first different embodiment.

FIG. 3 is a schematic configuration diagram illustrating an electrodeposition coating apparatus according to a second different embodiment.

[Explanation of symbols]

 Reference Signs List 12 rare earth bonded magnet material 14 electrodeposition solution 16 electrodeposition paint tank 22 first belt conveyor 24 second belt conveyor 26 third belt conveyor 30 removal brush (removal means)

Claims (3)

[Claims] 1. A method for electrodepositing an electrodeposition coating film on a surface of a rare earth bonded magnet material (12), wherein said rare earth bonded magnet is added to an electrodeposition solution (14) stored in an electrodeposition coating tank (16). The belt conveyor (22, 24) on the upstream side, which transports the material (12) in a state of being immersed, is moved from the belt conveyor (2, 24) on the downstream side.
4, 26), the magnet material (12) is sequentially transferred by being dropped and delivered, and the rare earth bonded magnet material (1
An electrodeposition coating method for a rare earth bonded magnet, wherein an electrodeposition coating film is electrodeposited on the surface of 2). 2. An apparatus for electrodepositing an electrodeposition coating film on a surface of a rare earth bonded magnet material (12), comprising: an electrodeposition coating tank (16) for storing an electrodeposition solution (14); A plurality of belt conveyors (22, 24, 26) disposed inside the paint tank (16) and transporting the rare earth bonded magnet material (12) in a state of being immersed in the electrodeposition solution (14), The plurality of belt conveyors (22, 24, 26) are arranged from the upstream belt conveyor (22, 24) to the downstream belt conveyor (24, 26).
The rare earth bonded magnet material (12) is arranged so as to be dropped and delivered, and transferred by each belt conveyor (22, 24, 26) in a state where the rare earth bonded magnet material (12) is immersed in the electrodeposition solution. An electrodeposition coating apparatus for rare earth bonded magnets, wherein an electrodeposition coating film is electrodeposited on the surface of the rare earth bonded magnet material (12) by electrodeposition coating. 3. An electrodeposition coating of a rare earth bonded magnet according to claim 2, further comprising removing means (30) for removing an electrodeposition coating film electrodeposited on the surface of the belt conveyor (22, 24, 26). apparatus.