Method for demagnetizing a neodymium-iron-boron permanent magnet

Abstract

The application provides a method for demagnetizing a neodymium-iron-boron permanent magnet, and relates to the technical field of permanent magnet demagnetization methods.The method comprises the following steps: (I) coating: coating the outside of the magnetized product with foil paper; (II) boxing: placing the coated product into a containing box; (III) furnace entry: placing the containing box in a high-temperature furnace and adjusting the operation parameters of the high-temperature furnace; the high-temperature furnace demagnetizes the product at high temperature; (IV) furnace exit: taking out the containing box, opening the foil paper, and taking out the demagnetized product; the method demagnetizes the magnetized product by high-temperature heating, and the product is double-protected by foil paper coating and boxing before high-temperature demagnetization, so that the problem of a sharp decline in the magnetic properties and the bearing capacity of the product caused by directly high-temperature heating of the product can be effectively avoided; the demagnetized product has good magnetic properties, and the maximum bearing capacity of the product does not decline, and the demagnetization effect is remarkable.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet demagnetization methods, and in particular to a method for demagnetizing a neodymium iron boron permanent magnet. Background Art

[0002] Neodymium iron boron permanent magnet is a kind of neodymium iron boron magnetic material. It has extremely high magnetic energy product and coercive force. At the same time, its high energy density makes neodymium iron boron permanent magnet material widely used in modern industry, electronic technology and medical industry.

[0003] During the use of NdFeB magnets after magnetization, they are very prone to scratches, or problems such as incorrect magnetization polarity and weak magnetism may occur, making them unusable. If they are directly discarded, it will lead to waste of raw materials. Therefore, demagnetization technology has come into being. Existing demagnetization processes usually include current demagnetization and high-temperature demagnetization. Existing high-temperature demagnetization usually uses an oven or a muffle furnace to directly bake the magnets at high temperatures for a long time to achieve the purpose of demagnetization. Using the existing high-temperature demagnetization method, after the product is demagnetized, its magnetic properties and bearing capacity are severely damaged. Even after re-magnetization, it cannot achieve the original use effect, and its demagnetization effect is poor. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for demagnetizing NdFeB permanent magnets to solve the technical problem in the prior art that the magnetized products are directly demagnetized using a high-temperature furnace, resulting in poor magnetic properties and reduced bearing capacity of the demagnetized products; the preferred technical solution among the many technical solutions provided by the present invention can produce many technical effects; see the details below.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] The present invention provides a method for demagnetizing a NdFeB permanent magnet, comprising at least the following steps:

[0007] (I) Wrapping: Wrapping the magnetized product with foil;

[0008] (II) Cartoning: placing the wrapped product into the container;

[0009] (III) placing the container in a high-temperature furnace, and adjusting the operating parameters of the high-temperature furnace, wherein the high-temperature furnace performs high-temperature demagnetization on the product;

[0010] (IV) Unloading: Take out the containing box, open the foil, and take out the demagnetized product.

[0011] Preferably, the foil is tin foil or aluminum foil.

[0012] Preferably, the containing box comprises a box body and a cover body detachably arranged on the box body; the box body and the cover body enclose a closed containing cavity.

[0013] Preferably, the containing box is made of stainless steel.

[0014] Preferably, in the step (III) of entering the furnace, after the containing box is placed, a vacuum button of the high-temperature furnace is opened, and a cold circulation system is opened.

[0015] Preferably, in the step (III) of entering the furnace, the high-temperature demagnetization comprises primary heating and holding and secondary heating and holding.

[0016] Preferably, the primary heating and holding comprises adjusting the high-temperature furnace to have a temperature above 380 DEG C and performing periodic holding.

[0017] Preferably, the secondary heating and holding comprises, after the primary heating and holding is completed, adjusting the high-temperature furnace to have a temperature of 350 DEG C and performing periodic holding.

[0018] Preferably, in the step (IV) of taking out the furnace, the containing box is taken out when the temperature is reduced to below 60 DEG C.

[0019] The method for demagnetizing the Nd-Fe-B permanent magnet provided by the application has at least the following beneficial effects:

[0020] The method for demagnetizing the Nd-Fe-B permanent magnet comprises the following steps: (I) coating, coating foil paper on the outside of the magnetized product, pre-protecting the magnetized product by the foil paper coating before entering the furnace; (II) boxing, placing the coated product into a containing box to protect the magnetized product twice by the containing box; (III) entering the furnace, placing the containing box in a high-temperature furnace and adjusting the operation parameters of the high-temperature furnace, demagnetizing the product at high temperature under the action of the high-temperature furnace; and (IV) taking out the furnace, taking out the containing box and opening the foil paper after the demagnetization is completed, and taking out the demagnetized product.

[0021] The application demagnetizes the magnetized product by high-temperature heating, and the product is double-protected by foil paper coating and boxing before high-temperature demagnetization, which can effectively avoid the problem that the magnetic property and bearing capacity of the product are greatly reduced due to direct high-temperature heating of the product, and the demagnetized product has good magnetic property and its maximum bearing capacity does not decrease, and the demagnetization effect is remarkable. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings described below only illustrate some of the embodiments of the present application, and all other embodiments obtained by a person of ordinary skill in the art without creative effort based on the embodiments of the present application shall fall within the scope of the present application.

[0023] Figure 1 is a method block diagram of the present application;

[0024] Figure 2 is an experimental data graph about product magnetic properties and bearing force before and after demagnetization of the present application and the prior art. DETAILED DESCRIPTION

[0025] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings described below only illustrate some of the embodiments of the present application, and all other embodiments obtained by a person of ordinary skill in the art without creative effort based on the embodiments of the present application shall fall within the scope of the present application.

[0026] Embodiment 1:

[0027] The present application provides a method for demagnetizing a neodymium-iron-boron permanent magnet, as shown in the figure, the method for demagnetizing the neodymium-iron-boron permanent magnet at least comprises the following steps: Figure 1

[0028] (I) Coating: coating foil paper on the outside of the magnetized product;

[0029] (II) Box packing: putting the coated product into a containing box;

[0030] (III) Furnace entry: placing the containing box in a high-temperature furnace, and adjusting the operation parameters of the high-temperature furnace, the high-temperature furnace demagnetizes the product at high temperature;

[0031] (IV) Furnace exit: taking out the containing box, opening the foil paper, and taking out the demagnetized product.

[0032] The present application adopts high-temperature demagnetization, and the magnetized product is double-protected by foil paper coating and box packing before furnace entry. The demagnetized product has good magnetic properties and large product bearing force, and the demagnetization effect is remarkable.

[0033] Embodiment 2:

[0034] The present application provides a method for demagnetizing a neodymium-iron-boron permanent magnet, at least comprising the following steps:

[0035] (I) Coating: coating foil paper on the outside of the magnetized product;​

[0036] The foil paper is tin foil paper or aluminum foil paper, has good heat insulation effect, and performs primary protection on the high-temperature demagnetization process of the product.

[0037] (II) boxing: the coated product is placed into a containing box.

[0038] The containing box effectively contains the product, performs secondary protection on the product, double protection, and effectively guarantees the magnetic performance and bearing force of the product after demagnetization.

[0039] The containing box comprises a box body and a cover body detachably arranged on the box body, and the box body and the cover body enclose a closed containing cavity to effectively contain the product.

[0040] The containing box is made of stainless steel material, has good heat preservation performance and sealing performance, and is durable.

[0041] (III) into the furnace: the containing box is placed in a high-temperature furnace, and the operating parameters of the high-temperature furnace are adjusted, and the high-temperature furnace demagnetizes the product.

[0042] The high-temperature furnace is a vacuum muffle furnace, which has cold cycle and vacuum pumping functions and can be temperature and time controlled.

[0043] When demagnetizing at high temperature, after the containing box is placed, the vacuum button of the high-temperature furnace is opened, the vacuum degree is adjusted to a suitable one, and the cold cycle system is opened.

[0044] The high-temperature demagnetization comprises two stages of primary heating and secondary heating.

[0045] The primary heating comprises adjusting the high-temperature furnace to make the temperature of the high-temperature furnace rise to above 380 DEG C, and rising for about 30 min, and then periodically heating and preserving for about 60 min.

[0046] The secondary heating comprises adjusting the high-temperature furnace to make the temperature of the high-temperature furnace be about 350 DEG C after the primary heating is completed, and then periodically heating and preserving for about 60 min.

[0047] (IV) out of the furnace: after the preservation is completed, when the temperature is reduced to below 60 DEG C, the containing box is taken out, the foil paper is opened, and the demagnetized product is taken out.

[0048] The Nd-Fe-B permanent magnet product with the specification of 7.765*0.375*2.91 mm is demagnetized by the present application and the prior art, and the magnetic performance (magnetic moment, unit: muwb*cm) data table (data corresponds Figure 2 ) before and after demagnetization is as follows:

[0049]

[0050]

[0051] According to the above table, the difference between the magnetic moment of the product after demagnetization and the magnetic moment before demagnetization is smaller than the difference between the magnetic moment of the product after demagnetization by the prior art demagnetization method and the magnetic moment before demagnetization, so the magnetic performance of the product after demagnetization is less reduced compared with the prior art.

[0052] The product after demagnetization by the present application still has good magnetic performance.

[0053] The neodymium-iron-boron permanent magnet products with the specifications of 7.765*0.375*2.91mm are demagnetized by the present application and the prior art, and the data table of the bearing force (unit: N) of the products before and after demagnetization (the data corresponds to Figure 2 ) is as follows:

[0054]

[0055]

[0056] According to the above table, the difference between the bearing force of the product after demagnetization and the bearing force of the product before demagnetization is smaller than the difference between the bearing force of the product after demagnetization by the prior art demagnetization method and the bearing force of the product before demagnetization, so the bearing force of the product after demagnetization will not be reduced compared with the prior art.

[0057] The product after demagnetization by the present application has a larger bearing force.

[0058] In summary, the present application has little effect on the magnetic performance and bearing force of the product, and the demagnetization effect is remarkable.

[0059] In the description of the present application, it should be understood that the terms “upper”, “lower”, “inner”, “outer” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0060] In the present application, unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connection”, “fixing” and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be directly connected, or indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0061] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of demagnetizing a neodymium-iron-boron permanent magnet, characterized in that, At least comprising the following steps: (I) Coating: coating the outside of the magnetized product with foil paper, which is tin foil paper or aluminum foil paper, to provide primary protection for the high-temperature demagnetization process of the product; (II) Boxing: placing the coated product into a containing box to provide secondary protection for the product; (III) Into the furnace: placing the containing box in a high-temperature furnace and adjusting the operating parameters of the high-temperature furnace, which demagnetizes the product at high temperature; After the containing box is placed, open the vacuum button of the high-temperature furnace and open the cold circulation system; The high-temperature demagnetization includes primary heating and secondary heating. (IV) Out of the furnace: taking out the containing box, opening the foil paper, and taking out the demagnetized product.

2. The method of demagnetizing a neodymium-iron-boron permanent magnet according to claim 1, characterized in that The containing box comprises a box body and a cover body detachably arranged on the box body. The box body and the cover body enclose a closed containing cavity.

3. The method of demagnetizing a neodymium-iron-boron permanent magnet according to claim 1, characterized in that The primary heating includes adjusting the high-temperature furnace to have a temperature above 380℃ and performing periodic heat preservation.

4. The method of demagnetizing a neodymium-iron-boron permanent magnet according to claim 1, characterized in that The secondary heating includes adjusting the high-temperature furnace to have a temperature of 350℃ after the primary heating is completed and performing periodic heat preservation.

5. The method of demagnetizing a neodymium-iron-boron permanent magnet according to claim 1, characterized in that In step (IV) out of the furnace, the containing box is taken out when the temperature is reduced to below 60℃.

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