JPH11238620A - Permanent magnet and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet, capable of suppressing the reduction of a magnetic characteristic due to coating layers and allowed to be easily manufactured, without generating jig traces. SOLUTION: This permanent magnet 1 is constituted of forming coating layers 3 on the end faces 21, 22, inner periphery 23 and outer periphery 24 of a magnetic body 2 formed like a ring by an electrostatic coating. The coating layer 3 formed on the end face 21 and that formed on the end face 22 and the inner and outer peripheries 23, 24 are formed by respectively different processes. The preferable film thickness of these layers is 2 to 45 μm. The average grain size of powder in powder coating to be used for electrostatic coating is preferably less than or equal to 35 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet having a coating layer and a method for manufacturing the same.

[0002]

2. Description of the Related Art Permanent magnets include sintered magnets obtained by sintering magnetic powders, bonded magnets obtained by bonding magnetic powders with an organic binder, and cast magnets obtained by subjecting a cast ingot to predetermined processing. There is.

[0003] In these permanent magnets, the surface of the magnet is covered with a coating layer in order to prevent rust and prevent dust generation due to detachment of the magnetic powder.

Conventionally, this coating layer is formed by dipping a permanent magnet in a flowable organic material and solidifying the organic material adhered to the magnet surface by thermosetting or the like to form a coating layer. There is also a method in which a liquid organic material is attached to the surface of the permanent magnet by a spray method, and this is solidified to form a coating layer.

In general, in forming such a coating layer, it must be noted that the thickness of the coating layer becomes too large. If the coating layer is too thick, the magnetic flux is blocked by the coating layer,
Alternatively, the approach distance to the magnet must be increased, and the magnetic characteristics of the permanent magnet and various characteristics exhibited when installed in a device such as a motor (hereinafter, these are collectively referred to as “magnetic characteristics”) Is reduced.

[0006] When a thin coating layer is formed by the above method, the thickness of the coating layer becomes uneven or defects such as pinholes and peeling occur. The effect cannot be sufficiently obtained, and the intended purpose of forming the coating layer cannot be achieved.

In the above method, since the coating layer is formed while the permanent magnet is held by the jig, a mark of the jig remains on a part of the coating layer after completion. This jig mark is not only unfavorable in appearance, but also causes rust from near the jig mark. Therefore, a repair work for filling the jig trace is required, which takes time and increases the manufacturing cost.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to suppress a decrease in magnetic properties due to a coating layer.
An object of the present invention is to provide a permanent magnet and a method for manufacturing the permanent magnet that do not cause a jig trace and are easy to manufacture.

[0009]

This and other objects are achieved by the present invention which is defined below as (1) to (16).

(1) A permanent magnet having a coating layer on the surface of a magnet body, wherein the coating layer is formed by electrostatic coating and has a thickness of 2 to 45 μm.

(2) A permanent magnet having a coating layer on the surface of a magnet body, wherein the coating layer has an average particle size of 35 μm.
A permanent magnet characterized by being formed by electrostatic coating using the following powder coating.

(3) A permanent magnet having a coating layer on a magnet surface including at least both end faces of a magnet main body having a pair of opposed end faces, wherein the coating layer is formed by electrostatic coating, and A permanent magnet, wherein a coating layer formed on one end face of both end faces and a coating layer formed on the other end face are formed through different processes.

(4) The permanent magnet according to any one of the above (1) to (3), wherein the coating layer has no trace of a jig for holding the magnet main body when the coating layer is formed. magnet.

(5) The magnetic material forming the magnet body is a material containing a rare earth element.
The permanent magnet according to any one of the above.

(6) The permanent magnet according to any one of (1) to (5), wherein the magnet main body is a bonded magnet.

(7) After the powder coating is electrostatically adsorbed on the surface of the magnet main body, the powder coating is baked to have a film thickness of 2-45.
A method for producing a permanent magnet, comprising forming a coating layer having a thickness of μm.

(8) The average particle size is 35 on the surface of the magnet body.
A method for producing a permanent magnet, comprising: a step of electrostatically adsorbing a powder coating having a particle size of not more than μm and then firing the powder coating to form a coating layer.

(9) The entire surface of the magnet main body is divided into a plurality of regions, and the powder coating is electrostatically attracted and fired for each region to form a coating layer on the entire surface of the magnet main body. The method for producing a permanent magnet according to the above (7) or (8).

(10) After forming a coating layer by electrostatic painting on one end face of a magnet main body having a pair of opposed end faces, forming a coating layer by electrostatic coating on an exposed surface of the magnet main body including the other end face. A method of manufacturing a permanent magnet.

(11) A magnet main body having a pair of opposed end surfaces is disposed so that one end surface thereof is directed forward in the flow direction of the powder coating material, and the powder coating material is electrostatically attracted to the one end surface. One step, baking the powder coating material covering the one end face to form a coating layer, and installing the magnet body such that the other end face faces forward in the flow direction of the powder coating material. A third step of electrostatically adsorbing the powder coating on the exposed surface of the magnet main body including the other end face, and a fourth step of firing the powder coating covering the exposed surface to form a coating layer. A method for producing a permanent magnet.

(12) The method according to (11), wherein the first step and / or the third step is performed in a state where the magnet main body is placed on a support member through which the powder coating material can pass. Of manufacturing permanent magnets.

(13) In the third step and / or the fourth step, the magnet main body is mounted on a supporting member through which the powder coating material can pass through a coating layer formed in the second step. The method for producing a permanent magnet according to the above (11) or (12), wherein the method is performed in a state where the permanent magnet is placed.

(14) The shape of the magnet main body is cylindrical or columnar, and the flow direction of the powder paint in the first step and the third step is parallel to a central axis of the magnet main body. The method for producing a permanent magnet according to any one of the above (11) to (13), which is a direction.

(15) The production of the permanent magnet according to any one of (11) to (14), wherein the flow rate of the powder coating in the first step is higher than the flow rate of the powder coating in the third step. Method.

(16) The coating layer has a thickness of 2 to 45 μm.
The method for producing a permanent magnet according to any one of the above (8) to (15).

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a permanent magnet and a method for manufacturing the same according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 is a partially cutaway perspective view showing an embodiment of the permanent magnet of the present invention. As shown in the figure, the permanent magnet of the present invention is obtained by forming a coating layer 3 on the surface of a magnet main body 2.

The magnet main body 2 has a ring shape (cylindrical shape), and has opposed end surfaces 21 and 22, an inner peripheral surface 23, and an outer peripheral surface 24. The shape of the magnet body 2 is
The shape is not limited to the ring shape as shown in the figure, and may be any other shape such as a column shape, a plate shape, a block shape, a curved plate shape (a tile shape), a rod shape, and the like.

The magnet body 2 may be any of a sintered magnet obtained by sintering magnetic powder, a bonded magnet obtained by bonding magnetic powder with an organic binder, a cast magnet obtained by subjecting a cast ingot to a predetermined processing, and the like. However, a bonded magnet is preferable because it has a wide degree of freedom in shape.

The magnetic material constituting the magnet main body 2 may be any material such as ferrite and alnico, but is preferably a material containing a rare earth element because of exhibiting high magnetic properties.

As such a magnetic material (magnetic powder), a material made of an alloy containing a rare earth element and a transition metal is preferable, and the following <1> to <4> are particularly preferable.

<1> A rare earth element mainly composed of Sm and C
a transition metal mainly composed of o (hereinafter, referred to as a basic component)
Sm-Co alloy).

<2> R (where R is at least one of rare earth elements including Y), a transition metal mainly composed of Fe, and B as basic components (hereinafter, R-Fe-B
System alloy).

<3> A rare earth element mainly composed of Sm and F
A material mainly composed of a transition metal mainly composed of e and an interstitial element mainly composed of N (hereinafter, referred to as an Sm-Fe-N-based alloy).

<4> A mixture of at least two of the compositions of <1> to <3>. In this case, the advantages of the respective magnetic powders to be mixed can be obtained, and more excellent magnetic properties can be easily obtained.

Typical examples of the Sm-Co alloy include SmCo ₅ and Sm ₂ TM ₁₇ (where TM is a transition metal).

Representative R-Fe-B alloys include Nd-Fe-B alloys, Pr-Fe-B alloys, and N-Fe-B alloys.
d-Pr-Fe-B-based alloy, Ce-Nd-Fe-B-based alloy, Ce-Pr-Nd-Fe-B-based alloy, in which part of Fe is replaced by another transition metal such as Co or Ni And the like.

[0038] Typical examples of the Sm-Fe-N based _alloy, Sm ₂ produced by nitriding a Sm 2 _{Fe 17} alloy
Fe ₁₇ N ₃ is mentioned.

The rare earth elements in the magnetic material include Y, La, Ce, Pr, Nd, Pm, Sm, Eu,
Examples include Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and misch metal, and one or more of these may be included. Further, as the transition metal, F
e, Co, Ni and the like, and one or more of these can be included. Further, in order to improve magnetic properties, B, Al, Mo,
Cu, Ga, Si, Ti, Ta, Zr, Hf, Ag, Z
n or the like can be contained.

In the case of the magnet main body 2 made of a bonded magnet, the content of the magnetic powder in the magnet main body 2 is preferably about 70 to 99 wt% in consideration of compatibility between the moldability of the magnet main body 2 and magnetic properties, and is preferably 80 to 99 wt%. About 98 wt% is more preferable.

The average particle size of the magnetic powder is not particularly limited, but is preferably about 0.5 to 100 μm.
About 0 μm is more preferable.

The organic binder (binding resin) in the bonded magnet is not particularly limited, and any of a thermoplastic resin and a thermosetting resin may be used.

The coating layer 3 is mainly composed of an organic material. The purpose (function) of forming the coating layer 3 is not particularly limited, but typical examples of the purpose of formation include rust prevention and prevention of dust generation due to detachment of the magnetic powder.

This coating layer 3 is formed by electrostatic coating. Details of the electrostatic coating will be described later.

In the electrostatic coating, the thickness of the coating layer 3 can be made thinner and more uniform as compared with the conventional immersion method or the like.
Further, since the organic solvent contained in the immersion liquid does not volatilize, it is also useful for environmental protection.

The thickness of the coating layer 3 is preferably about 2 to 45 μm, more preferably about 5 to 40 μm, and further preferably about 10 to 35 μm.

If the thickness of the coating layer 3 is too small,
If the purpose of the formation is not sufficiently achieved, and if the film thickness is too large, the magnetic properties are significantly reduced.

The constituent material of the coating layer 3 depends on the composition of the powder coating 10 used in the electrostatic coating. Specific examples thereof include epoxy resins, phenol resins, acrylic resins, polyurethanes, polyamides, polyesters, polyvinyl chloride, polyethylene, polypropylene, and fluorine resins such as polytetrafluoroethylene.

The average particle size (particle size) of the powder coating material 10 used in the electrostatic coating is preferably 35 μm or less, more preferably 25 μm or less, and even more preferably 15 μm or less.

If the average particle size of the powder coating 10 is too large,
The thickness of the coating layer 3 tends to increase, and may exceed the upper limit of the thickness described above.

When the purpose of forming the coating layer 3 is to prevent rusting or dust generation, the coating layer 3 is preferably formed on the entire surface of the magnet main body 2, that is, on the end surfaces 21, 22, the inner peripheral surface 23 and the outer peripheral surface 24. It is preferred that It goes without saying that there may be a portion where the coating layer 3 is not formed on the surface of the magnet main body 2.

Further, the coating layer 3 formed on the end face 21,
It is preferable that the coating layer 3 formed on the end face 22 is formed in a separate step. This point will be described in detail in a method of manufacturing a permanent magnet described later.

The coating layer 3 is a trace of a jig for holding the magnet main body 2 at the time of forming the coating layer (in particular, a defect of the coating layer 3 or a defect whose thickness is extremely reduced). It is preferred that they have no. As a result, the appearance is improved, and rust generation near the jig trace is also prevented. Furthermore, the process of repairing such jig traces is not required,
Productivity is improved.

Next, an example of the method for producing a permanent magnet of the present invention will be described. 2 to 6 are longitudinal sectional views showing steps of a method for manufacturing a permanent magnet of the present invention. The arrows in FIGS. 2, 4 and 5 indicate the flow of the powder paint and the air.

First, the configuration of the electrostatic coating device 4 will be described. The electrostatic coating apparatus 4 mainly includes a housing 5 defining a space for performing electrostatic coating, a support member 6 installed in the housing 5, and a duct 7 connected to a lower end of the housing 5 in the drawing. And a powder paint collecting section 8 installed in the middle of the duct 7.

The support member 6 can mount the magnet main body 2 thereon.
Further, it is a material through which the powder coating material can pass, and is constituted by, for example, a reticulated body (mesh) or a frame member. The support member 6 is locked and fixed to a locking portion 51 formed to protrude from the inner surface of the side wall of the housing 5.

Examples of the constituent material of the support member 6 include metals such as stainless steel, hard resins, and ceramics.

A cover 52 which can be opened and closed is provided on the side wall of the housing 5. Open this lid 52,
The magnet main body 2 can be taken in and out of the housing 5.

The powder paint recovery section 8 has a built-in filter, and has a function of separating and removing the powder paint 10 from the gas flowing through the duct 7 by the filter. The separated and removed powder coating 10 is returned to a powder coating supply source (not shown) via the pipe 9 and is reused. Powder paint 1
The air from which 0 has been removed is further transferred or exhausted through a duct 7 downstream of the powder paint collection unit 8.

Above the housing 5 in the figure, a nozzle (not shown) for spraying the powder paint 10 sent from the powder paint supply source is installed.

The composition (type) of the powder coating 10 to be used
The average particle size is as described above.

Hereinafter, each manufacturing process will be described.

1) As shown in FIG. 2, the magnet main body 2 manufactured by a predetermined method is placed on the holding member 6, and the electrostatic coating is started. As the powder coating 10, the one described above is used.

During the electrostatic coating, a flow of the powder coating 10 is formed in the housing 5. The direction of this flow is
The direction is substantially parallel to the center axis C of the magnet main body 2. That is, the magnet main body 2 is installed such that the end face 21 faces forward in the flow direction of the powder coating material 10.

The powder coating material 10 contained in the airflow is, for example, negatively charged, is electrostatically attracted to the end face 21 of the magnet body 2 having a positive charge, and is deposited.

At this time, by setting the exhaust speed of the duct 7 to be relatively high, the powder coating 1
0 (for example, 0.3 to 5 m / sec). As a result, the powder coating material 10 is mainly deposited on the end face 21, and is not deposited on the inner peripheral face 23, the outer peripheral face 24, and the end face 22, or is deposited in a small amount.

In this case, the powder coating 1 on the end face 21
0 is the thickness of the coating layer 3 to be formed (target thickness)
Is performed in consideration of, for example, 1 / the target thickness of the coating layer 3.
It can be about 4 to 1/2.

2) When the deposition of the powder coating material 10 on the end face 21 is completed, the electrostatic coating device 4 is stopped, the lid 52 is opened, and the magnet main body 2 is placed on the support member 6. Take it out of the housing 5. Then, this is put into a heating furnace (not shown), and the powder coating material 10 is fired. This allows
As shown in FIG. 3, the coating layer 3 having the above-described thickness is formed on the end face 21 of the magnet main body 2. In this case, the thickness of the coating layer 3 is as described above.

The sintering conditions are not particularly limited, but may be usually 100 to 350 ° C. for about 2 to 30 minutes.

This firing can be performed in the housing 5. In this case, a heat source such as a lamp and a heater is provided in the housing 5, and the heat source is operated to heat and sinter the powder coating material 10 deposited on the surface of the magnet main body 2. In the case of such a configuration, there is no need to take the magnet body 2 into and out of the housing 5, and the permanent magnet 1 can be manufactured more easily.

Further, the magnet main body 2 is placed on a transfer means such as a belt conveyor, and the electrostatic coating section for applying electrostatic coating (application of powder coating) and the firing section (heating furnace) for firing are appropriately moved. It is also possible to adopt a configuration for obtaining the above.

3) As shown in FIG. 4, the magnet main body 2 having the coating layer 3 formed on the end face 21 is placed upside down on the support member 6 and set in the housing 5 again.

4) As shown in FIG. 5, the electrostatic coating is started again.

At the time of electrostatic coating, the flow of the powder coating 10 is formed in the housing 5 in the same manner as described above, and the magnet body 2 is oriented such that its end face 22 faces forward in the flow direction of the powder coating 10. is set up.

The powder coating material 10 contained in the air current is electrostatically adsorbed and deposited on the end face 22, the inner peripheral face 23 and the outer peripheral face 24 of the magnet main body 2 in the same principle as described above.

At this time, the exhaust speed of the duct 7 is set lower than that in the step 1), and the flow rate of the powder coating material 10 in the housing 5 is made relatively low. This flow rate
For example, to the extent that the powder coating material 10 can be recovered (for example,
0.1 to 2 m / sec). Thereby, the powder coating 1
0 indicates not only the end face 22 but also the inner circumferential face 23 and the outer circumferential face 2.
4 is also deposited.

In this case, the powder coating 1 on the end face 22
It is preferable that the deposition thickness of 0 is substantially equal to the thickness when deposited on the end face 21.

5) If necessary, the surface of the coating layer 3 formed on the end face 21 is cleaned using a brush or the like, and the adhered powder paint 10 is removed. Powder coating 10 on coating layer 3
If baking is performed in the next step with the particles adhered, fine irregularities may be formed on the surface of the coating layer 3. By performing this cleaning, the appearance quality of the coating layer 3 can be improved.

Note that this step may be omitted.

6) The lid 52 is opened, the magnet body 2 is taken out of the housing 5 with the magnet body 2 placed on the support member 6, and the magnet body 2 is placed in a heating furnace (not shown) in the same manner as in the step 2). And the powder coating material 10 is fired. Thereby, as shown in FIG. 6, the coating layer 3 having the above-described thickness is formed on the end face 22, the inner peripheral face 23, and the outer peripheral face 24 of the magnet main body 2. In this case, the thickness of the coating layer 3 is as described above.

The newly formed coating layer 3 is combined with the coating layer 3 on the end face 21 which has already been formed. As a result, the coating layer 3 is formed on the entire surface of the magnet main body 2 and the permanent magnet 1 Is completed.

The firing conditions are the same as in the step 2).

Also, in the same manner as described in the step 2), this baking is performed in the housing 5 or the baking section is moved between the electrostatic coating section and the baking section by a transfer means such as a belt conveyor. Configuration.

According to the manufacturing method as described above, the entire surface of the magnet main body 2 is divided into a plurality of regions, and the electrostatic attraction of the powder coating material 10 and firing of the powder coating 10 are performed for each region, thereby completing the entire magnet main body 2. Forming the coating layer 3 on the surface, in particular, after forming the coating layer 3 by electrostatic coating on one end face 21 of the magnet body 2 having a pair of opposed end faces, exposing the magnet body 2 including the other end face 22 By forming the coating layer 3 by electrostatic coating on the surface, a uniform and uniform coating layer 3 can be easily formed on the entire surface of the magnet main body 2.

In this case, the magnet body 2 is installed so that one end face 21 faces forward in the flow direction of the powder coating material, and
A step of electrostatically adsorbing the powder coating on the substrate, and installing the magnet main body 2 so that the other end face 22 faces forward in the flow direction of the powder coating, and applies the powder coating 10 on the end face 22 and other exposed surfaces. Since the method includes the step of adsorbing, the film quality, film thickness, and the like of the coating layer 3 on the end face 21 and the end face 22 of the magnet main body 2 can be made equal.

At this time, by adjusting the flow rate of the powder coating material 10 as described above, the same film quality and film thickness can be applied to the side surfaces of the magnet body, that is, the inner peripheral surface 23 and the outer peripheral surface 24. Can be formed.

When the coating layer 3 is formed on the end face 22 and other exposed surfaces of the magnet main body 2 (in the step 4) and / or in the step 6), the coating layer 3 is already formed on the end face 21. Since the magnet main body 2 is placed on the support member 6 via the coating layer 3, no trace of the jig is formed on the coating layer 3.

[0088]

As described above, according to the present invention, the thickness of the coating layer can be reduced, and the thickness and film quality can be made uniform. For this reason, it is possible to suppress a decrease in the magnetic properties due to the coating layer, for example, without impairing the purpose of forming the coating layer such as rust prevention and dust generation. And the permanent magnet which has such an advantage can be manufactured easily.

Further, since no jig marks are formed on the coating layer, the appearance quality and rust resistance are excellent, and a repair work for filling the jig marks is not required, so that the manufacturing process can be simplified and the cost can be reduced.

Further, since the coating layer is formed by electrostatic coating, the adhesion of the coating layer is higher than other methods, and the effects of forming the coating layer such as rust prevention and dust generation are more effectively exhibited. In particular, the adhesion of the coating layer to the bonded magnet is much better.

Further, in the present invention, since the coating layer is formed by electrostatic coating, a volatile solvent is not used unlike the conventional immersion method, so that the safety at the time of manufacture is high and the environment is protected.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a permanent magnet of the present invention.

FIG. 2 is a longitudinal sectional view showing steps in an embodiment of the method for manufacturing a permanent magnet according to the present invention.

FIG. 3 is a longitudinal sectional view showing steps in an embodiment of the method for manufacturing a permanent magnet according to the present invention.

FIG. 4 is a longitudinal sectional view showing steps in an embodiment of the method for manufacturing a permanent magnet according to the present invention.

FIG. 5 is a longitudinal sectional view showing steps in an embodiment of the method of manufacturing a permanent magnet according to the present invention.

FIG. 6 is a longitudinal sectional view showing steps in an embodiment of the method for manufacturing a permanent magnet according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Permanent magnet 2 Magnet main body 21 End surface 22 End surface 23 Inner peripheral surface 24 Outer peripheral surface 3 Coating layer 4 Electrostatic coating device 5 Housing 51 Engagement part 52 Lid 6 Support member 7 Duct 8 Powder paint collection part 9 Pipe 10 Powder Paint C center axis

Claims (16)

[Claims] 1. A permanent magnet having a coating layer on a surface of a magnet main body, wherein the coating layer is formed by electrostatic coating and has a thickness of 2
A permanent magnet having a size of about 45 μm. 2. A permanent magnet having a coating layer on a surface of a magnet main body, wherein the coating layer is formed by electrostatic coating using a powder coating having an average particle diameter of 35 μm or less. Features permanent magnet. 3. A permanent magnet having a coating layer on a magnet surface including at least both end faces of a magnet body having a pair of end faces facing each other, wherein the coating layer is formed by electrostatic coating, and A permanent magnet, wherein the coating layer formed on one end face of the surface and the coating layer formed on the other end face are formed through different processes. 4. The permanent magnet according to claim 1, wherein the coating layer has no trace of a jig for holding a magnet main body when forming the coating layer. 5. The permanent magnet according to claim 1, wherein the magnetic material forming the magnet main body is a material containing a rare earth element. 6. The permanent magnet according to claim 1, wherein the magnet main body is a bonded magnet. 7. A method for producing a permanent magnet, comprising: a step of electrostatically adsorbing a powder coating on the surface of a magnet main body; and firing the powder coating to form a coating layer having a thickness of 2 to 45 μm. Method. 8. A method for producing a permanent magnet, comprising: a step of electrostatically adsorbing a powder coating having an average particle diameter of 35 μm or less on the surface of a magnet body; and firing the powder coating to form a coating layer. Method. 9. A coating layer is formed on the entire surface of the magnet main body by dividing the entire surface of the magnet main body into a plurality of regions and electrostatically adsorbing and baking the powder coating for each region. Item 10. The method for producing a permanent magnet according to item 7 or 8. 10. A coating layer formed by electrostatic coating on one end surface of a magnet body having a pair of opposed end surfaces, and then a coating layer formed by electrostatic coating on an exposed surface of the magnet body including the other end surface. A method for producing a permanent magnet, comprising: 11. A first magnet body having a pair of opposed end surfaces such that one end surface thereof is directed forward in the flow direction of the powder coating material, and the first end surface electrostatically adsorbs the powder coating material on the one end surface. Baking the powder coating covering the one end face to form a coating layer; and installing the magnet body such that the other end face faces forward in the flow direction of the powder coating and the other end. A third step of electrostatically adsorbing the powder coating on an exposed surface of the magnet main body including the end surface of the magnet, and a fourth step of baking the powder coating covering the exposed surface to form a coating layer. Manufacturing method of a permanent magnet. 12. The permanent according to claim 11, wherein the first step and / or the third step are performed in a state where the magnet main body is placed on a support member through which the powder coating material can pass. Manufacturing method of magnet. 13. The third step and / or the fourth step, wherein the magnet main body is placed on a support member through which the powder coating material can pass through a coating layer formed in the second step. The method for producing a permanent magnet according to claim 11, wherein the method is performed in a state where the permanent magnet is set. 14. A shape of the magnet main body is cylindrical or columnar, and a flow direction of the powder paint in the first step and the third step is parallel to a central axis of the magnet main body. The method for producing a permanent magnet according to any one of claims 11 to 13, wherein 15. The method for manufacturing a permanent magnet according to claim 11, wherein the flow rate of the powder coating in the first step is higher than the flow rate of the powder coating in the third step. 16. The method for manufacturing a permanent magnet according to claim 8, wherein said coating layer has a thickness of 2 to 45 μm.