Die and profiled magnetic steel manufacturing method

Abstract

The present application relates to a die and a profiled magnetic steel manufacturing method. The die is used for producing profiled magnetic steel, and comprises: a powder filling device, the powder filling device being provided with a plurality of die cavities each having an open end, and each die cavity having a first predetermined shape; a powder spreading device, the powder spreading device being provided with a powder spreading area, the powder spreading area being provided therein with a plurality of powder spreading passages, the powder spreading passages passing through the powder spreading device in a first direction, each powder spreading passage having a second predetermined shape, the powder spreading passages corresponding to the die cavities in position, the first predetermined shape being the same as the second predetermined shape, and the first direction being parallel to the height direction of the powder spreading devices; and a cover plate, the cover plate being used for sealing the die cavities. The die of the present application enables formed green bodies to be subjected to reinforced forming during orientation processes, so as to improve the forming density and the degree of orientation of magnetic steel, thus obtaining magnetic steel products of high remanence and high coercivity.

Description

A method for preparing a mold and irregularly shaped magnets Technical Field

[0001] This application relates to the field of permanent magnet technology, and more specifically, to a mold and a method for preparing irregularly shaped magnets. Background Technology

[0002] With the development of permanent magnet materials, microelectronics, automatic control, and power electronics, electric motors have made significant progress. Electric motors utilize electronic commutation instead of traditional mechanical commutation. Due to their advantages such as reliable performance, zero wear, low failure rate, small size, and high efficiency, they have rapidly expanded from their initial military applications to aerospace, medical, home appliance, and industrial automation fields.

[0003] For permanent magnet motors, they achieve their function by generating an air gap magnetic field through permanent magnets (i.e., magnets). No additional electrical energy is required, nor are additional windings needed. In the existing manufacturing process of magnets, the shape of the magnets not only includes regular cuboid shapes, but also irregular shapes such as bread-shaped and tile-shaped (irregular magnets). This requires the magnets to be cut during the manufacturing process, resulting in some waste of raw materials, low utilization rate of magnets, and low process efficiency. In addition, during the manufacturing process of magnets, they are inevitably oxidized, and the oxidized and deformed parts need to be removed by cutting, resulting in low utilization rate of magnets.

[0004] In recent years, researchers have studied the use of mold design for manufacturing irregularly shaped magnets. Generally, the blank size is first determined based on the order dimensions and machining allowance. The dimensions in the pressing direction are calculated according to a fixed shrinkage ratio, and the mold is designed. Then, the powder is loaded into the mold cavity, and a blank is formed through pressing, isostatic pressing, and firing. Because magnets have a relatively fine particle size, high viscosity, and poor flowability, when the powder is loaded into the irregularly shaped mold cavity, it is easy for the powder to become suspended in the small spaces of the irregular shape. This results in a high density in the filled powder areas and a low density in the suspended powder areas of the formed blank, leading to poor overall density and orientation of the magnet. Technical issues

[0005] Existing molds for preparing irregularly shaped magnets must employ an isostatic pressing process, resulting in poor remanence and coercivity of the irregularly shaped magnets prepared by the molds. Technical solutions

[0006] In view of this, this application proposes a mold and a method for preparing irregularly shaped magnets. Using the mold of this application to prepare irregularly shaped magnets eliminates the need for isostatic pressing, enabling the molding and sintering of fine-grained powder, thereby obtaining magnet products with high remanence and high coercivity. Simultaneously, it allows for direct molding and sintering of the product's size and shape, reducing the processing steps of the blank, improving material utilization, and increasing production efficiency.

[0007] In a first aspect, embodiments of this application provide a mold for producing irregularly shaped magnets, the mold comprising:

[0008] A powder filling device having a plurality of mold cavities with one end open, the mold cavities having a first preset shape;

[0009] A powder distribution device has a powder distribution area and a plurality of powder distribution channels are provided in the powder distribution area. The powder distribution channels penetrate the powder distribution device along a first direction and have a second preset shape. The powder distribution channels correspond to the position of the mold cavity. The first preset shape and the second preset shape are the same. The first direction is parallel to the height direction of the powder distribution device.

[0010] A cover plate, which is used to close the mold cavity.

[0011] Optionally, the powder filling device includes a base plate and a powder filling plate disposed on the base plate. The powder filling plate has a powder filling channel that extends through the powder filling plate along the first direction. The powder filling channel and the powder distribution channel are positioned opposite each other, and the powder filling channel and the base plate surround the mold cavity.

[0012] Optionally, the powder distribution device includes a support plate and a powder distribution plate disposed on one side of the support plate, the powder distribution channel is disposed on the powder distribution plate, the support plate has a first hollow area, and the first hollow area corresponds to the powder distribution channel.

[0013] Optionally, the length of the support plate along the second direction is greater than the length of the powder distribution plate along the second direction, and the second direction is perpendicular to the first direction.

[0014] Optionally, the powder dispensing device further includes a reinforcing plate disposed on one side of the support plate. The reinforcing plate and the powder dispensing plate are respectively disposed on both sides of the support plate. The reinforcing plate is disposed on the side of the support plate opposite to the powder filling device. The reinforcing plate has a second hollow region, which corresponds to the first hollow region.

[0015] The length of the reinforcing plate along the first direction is greater than the length of the supporting plate along the first direction, and the length of the reinforcing plate along the first direction is greater than the length of the powder distribution plate along the first direction.

[0016] Optionally, the mold further includes a fixing device for locking the cover plate and the powder distribution device along the first direction and the second direction, wherein the second direction is perpendicular to the first direction.

[0017] Optionally, the powder filling device and the powder dispensing device are detachably connected; and / or the powder dispensing device and the cover plate are detachably connected.

[0018] Optionally, the first preset shape includes at least one of bread shape, tile shape, and tile-like shape.

[0019] Secondly, embodiments of this application provide a method for preparing irregularly shaped magnets, which uses the mold described in the first aspect for preparation, and includes the following steps:

[0020] Provide the mold described in the first aspect;

[0021] The powder distribution device and the powder filling device are stacked in layers, so that the mold cavity and the powder distribution channel correspond one-to-one;

[0022] The magnetic material is introduced into the mold cavity through the powder distribution channel for near-pressureless molding, so that the magnetic material forms a blank of a first preset shape in the mold cavity;

[0023] Remove the powder application device and seal the mold cavity with the cover plate;

[0024] The magnetic material inside the mold cavity is subjected to magnetic orientation treatment to obtain a magnetic steel intermediate.

[0025] The intermediate magnetic steel body is heat-treated to form a permanent magnet block, thereby obtaining an irregularly shaped magnetic steel.

[0026] The near-pressureless forming process, magnetic orientation treatment, and heat treatment are all carried out in a low-oxygen atmosphere, where the oxygen content is less than or equal to 10 ppm.

[0027] Optionally, before performing magnetic orientation treatment on the magnetic material in the mold cavity, the fixing device is used to lock the cover plate and the powder filling device along the first and second directions.

[0028] Optionally, the near-pressureless forming process includes at least one of gas impact, vibration, and permanent magnet material surface compaction treatment;

[0029] The median particle size of the magnetic raw material is 1 μm to 4 μm;

[0030] The magnetic material is introduced into the mold cavity through the powder distribution channel with a powder density of 2.7 g / cm³ to 4.0 g / cm³; the density distribution of the magnetic material in the mold cavity of the powder filling device is less than or equal to 3%.

[0031] The orientation degree of the billet is greater than or equal to 97%;

[0032] The magnetic induction intensity of the magnetic orientation treatment is 2T~7T, and the magnetic orientation treatment method includes pulse orientation. Beneficial effects

[0033] The mold of this application, through the combined use of a powder filling device and a powder distributing device, ensures a one-to-one correspondence between the powder distribution channel and the mold cavity. This allows for the uniform distribution of magnetic raw materials into the mold cavity of the powder filling device via near-pressureless near-forming, eliminating the need for traditional isostatic pressing. Furthermore, the initial preset shape of the mold cavity is the shape of the magnet product, eliminating the need for cutting and effectively improving the utilization rate of the magnetic raw materials. After powder filling, the mold cavity is sealed with a cover plate, preventing the magnetic raw materials inside from being exposed to air. Therefore, small-particle-size magnetic raw materials can be used for magnetic orientation treatment under the influence of a large orientation field. Moreover, the forming process and magnetic orientation treatment are prepared using different mold components, allowing the formed blank to be strengthened during the orientation process, increasing the forming density and orientation degree of the magnet, thereby obtaining a magnet product with high remanence and high coercivity.

[0034] This application utilizes a mold-assisted, near-pressureless forming process to obtain a blank with controllable dimensions and morphology. The mold shape can be designed according to the finished size of the irregularly shaped magnet, eliminating the need for blank cutting and significantly improving production efficiency. Furthermore, the near-pressureless forming process is performed under normal or minimal pressure, resulting in less material loss and lower internal stress and warping deformation in the prepared blank, which is beneficial for improving the mechanical stability of the prepared irregularly shaped magnet. Further, the blank undergoes magnetic orientation treatment to acquire magnetism. Finally, heat treatment yields the irregularly shaped magnet. This application employs a two-stage process—forming followed by magnetic orientation—allowing the formed blank to be strengthened during the orientation process, increasing the magnet's forming density and orientation degree, thereby obtaining irregularly shaped magnet products with high remanence and high coercivity. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 is a schematic diagram of the powder filling device provided in an embodiment of this application;

[0037] Figure 2 is a schematic diagram of the powder distribution device provided in this application.

[0038] Figure 3 is a schematic diagram of the powder distribution device provided in this application.

[0039] Figure 4 is a schematic diagram of the cover plate provided in an embodiment of this application;

[0040] Figure 5 is a schematic diagram of the structure of the powder filling device and the powder distributing device provided in the embodiment of this application used together;

[0041] Figure 6 is a schematic diagram of the structure of the powder filling device and the cover plate used in conjunction with the embodiment of this application;

[0042] Figure 7 is a schematic diagram of the powder-filling plate provided in an embodiment of this application;

[0043] Figure 8 is a structural schematic diagram of the base plate provided in an embodiment of this application;

[0044] Figure 9 is a structural schematic diagram of the support plate provided in an embodiment of this application;

[0045] Figure 10 is a schematic diagram of the powder distribution plate provided in an embodiment of this application;

[0046] Figure 11 is a schematic diagram of the structure of the reinforcing plate provided in an embodiment of this application;

[0047] Figure 12 is a structural schematic diagram of the fixing device for fixing the powder filling device and the cover plate provided in the embodiment of this application;

[0048] Figure 13 is a structural schematic diagram of the first preset shape provided in an embodiment of this application;

[0049] Figure 14 is a flowchart of the preparation process of the magnet provided in this embodiment.

[0050] In the attached image:

[0051] 1-Powder filling device; 101-Mold cavity;

[0052] 11-Powder filling plate;

[0053] 111 - Filling channel;

[0054] 12-Base plate;

[0055] 2-Powder distribution device; 2a-Powder distribution area;

[0056] 21-Support plate;

[0057] 21a - First hollow region;

[0058] 22-Powdering board;

[0059] 221 - Powder distribution channel;

[0060] 23-Reinforcing plate;

[0061] 23a - Second hollow region;

[0062] 3-Cover plate;

[0063] 4-Fixing device;

[0064] 41-First fixing plate;

[0065] 42 - Second fixing plate;

[0066] 43-Locking component. The best embodiment of the present invention

[0067] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0068] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0069] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0070] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0071] Magnets are magnetic materials made from alloys of metals such as iron, nickel, and cobalt. They possess strong magnetic properties and play an important role in various applications. Magnets have many unique properties, such as strong magnetism, high permeability, and magnetic saturation magnetic induction. Magnets have wide applications in fields such as motors, electronic equipment, and magnetic materials.

[0072] The methods for preparing magnets in related technologies usually include the following two: (1) Using permanent magnet blanks as raw materials, cutting, grinding and electrical discharge machining are performed on the blanks to prepare blanks of a preset shape, and then post-processing is performed to obtain magnets. (2) Permanent magnet powder is placed in a magnetic field for orientation molding, and then isostatic pressing is performed to obtain green blanks, and then the green blanks are sintered to obtain magnets.

[0073] Of the two preparation methods mentioned above, method (1) results in significant waste of blank material during processing, and the low efficiency of the electrical discharge machining process requires the installation of multiple machines, leading to higher costs. Method (2) with medium static pressure treatment exposes the product to the risk of exposure to air, reducing the remanence and coercivity of the magnet.

[0074] In view of this, the present application provides a mold, a magnet and a method for manufacturing the same, which does not use isostatic pressing or molding pressing processes, but uses a near-pressureless molding process and a mold to pre-treat the magnetic raw materials, and maintains a low-oxygen atmosphere throughout the entire preparation process, which can achieve the preparation of magnet products with high remanence and high coercivity.

[0075] This application provides a mold for preparing irregularly shaped magnetic steel. The mold includes a powder filling device 1, a powder distributing device 2, and a cover plate 3. Figure 1 is a structural schematic diagram of the powder filling device provided in this application embodiment, Figure 2 is a structural schematic diagram of the powder distributing device provided in this application (one type), Figure 3 is a structural schematic diagram of the powder distributing device provided in this application (another type), and Figure 4 is a structural schematic diagram of the cover plate provided in this application embodiment. The powder filling device 1 is used to load magnetic raw materials, the powder distributing device 2 is used to distribute the magnetic raw materials into the powder filling device 1, and the cover plate 3 is used to seal the powder filling device 1 containing the magnetic raw materials. Specifically:

[0076] Please refer to Figure 1. The powder filling device 1 has a plurality of mold cavities 101 with one end open. The mold cavity 101 is used to load magnetic raw materials. The mold cavity 101 has a first preset shape, which is the shape of the final irregularly shaped magnet.

[0077] Please refer to Figures 2 and 3. The powder distribution device 2 has a powder distribution area 2a, and a plurality of powder distribution channels 221 are provided in the powder distribution area 2a. The powder distribution channels 221 penetrate the powder distribution device 2 along a first direction. The powder distribution channels 221 have a second preset shape. The powder distribution channels 221 are positioned corresponding to the mold cavity 101. The first preset shape and the second preset shape are the same. The first direction is parallel to the height direction of the powder distribution device 2. During the use of the mold, Figure 5 is a structural schematic diagram of the powder filling device and the powder distribution device used together. Please refer to Figure 5. The powder distribution device 2 and the powder filling device 1 are set together to fill the powder filling device 1 with magnetic raw materials through the powder distribution channels 221. Each mold cavity 101 corresponds to one powder distribution channel 221. The same amount of magnetic raw materials can be placed in each powder distribution channel 221 by uniform weighing, thereby achieving uniform powder filling.

[0078] After the powder filling operation is completed, Figure 6 is a structural diagram of the powder filling device and the cover plate used together. Please refer to Figures 3 and 6. The powder filling device 1 and the cover plate 3 are set together so that the cover plate closes the mold cavity 101 of the powder filling device 1.

[0079] The mold of this application, through the combined use of the powder filling device 1 and the powder distributing device 2, ensures a one-to-one correspondence between the powder distribution channel 221 and the mold cavity 101. This allows the magnetic raw material to be uniformly distributed within the mold cavity of the powder filling device 1 using a near-pressureless molding process, eliminating the need for traditional isostatic pressing. Furthermore, the first preset shape of the mold cavity 101 is the shape of the magnet product to be manufactured, eliminating the need for cutting and effectively improving the utilization rate of the magnetic raw material. After powder filling, the mold cavity 101 is sealed by the cover plate 3, preventing the magnetic raw material within the mold cavity 101 from being exposed to air. Therefore, small-particle-size magnetic raw materials can be used for magnetic orientation treatment under a large orientation field to achieve the preparation of irregularly shaped magnets with high remanence and high coercivity.

[0080] In this application, the first direction refers to the height direction of the powder distribution device 2, that is, the first direction is the Z-axis direction shown in Figure 1. The second direction refers to the direction perpendicular to the first direction. The second direction can be the X-axis direction shown in Figure 1 or the Y-axis direction shown in Figure 1. The following will use the first direction as the Z-axis direction and the second direction as the X-axis direction as an example for explanation.

[0081] Optionally, the powder filling device 1 serves as a support platform for the mold cavity 101. The powder filling device 1 includes a base plate 12 and a powder filling plate 11 disposed on the base plate 12. Figure 7 is a structural schematic diagram of the powder filling plate 11, and Figure 8 is a structural schematic diagram of the base plate. Please refer to Figures 7 and 8. The powder filling plate 11 has a powder filling channel 111 with a first preset shape. The powder filling channel 111 penetrates the powder filling plate 11 along a first direction. The base plate 12 and the powder filling channel 111 surround and form the mold cavity 101. Thus, the mold cavity 101 can be formed by the combination of the base plate 12 and the powder filling plate 11 for loading magnetic raw materials. Alternatively, the powder filling plate 11 and the base plate 12 can be separated after the magnetic raw materials are prepared and the magnets are removed to achieve the removal of the magnets.

[0082] Optionally, the base plate 12 and the powder filling plate 11 can be detachably connected. For example, bolt holes can be provided in the area of ​​the powder filling plate 11 where the powder filling channel 111 is not provided, and bolt holes can also be provided at the corresponding positions on the base plate 12, so that the base plate 12 and the powder filling plate 11 can be fixed by bolts.

[0083] Optionally, the powder distribution channel 221 and the powder filling channel 111 have the same shape, which is the irregular shape used to prepare the irregular magnet. When the powder filling device 1 and the powder distribution device 2 are stacked, the positions of the powder distribution channel 221 and the powder filling channel 111 are completely corresponding to ensure the accuracy of powder distribution by the powder distribution device 2.

[0084] Optionally, the number of powder distribution channels 221 and powder filling channels 111 is the same. The number of powder distribution channels 221 is the same as the number of mold cavities 101. There can be multiple mold cavities 101. The size of the powder distribution channels 221 and powder filling channels 111 can be designed according to the quality and volume of the magnet product to improve the adaptability of the mold and make the mold of this application applicable to the preparation of magnets of different specifications. The number of mold cavities 101 is generally 1 to 200, which can effectively improve the batch production of magnet products and greatly improve the production efficiency of magnets.

[0085] Optionally, the powder filling plate 11 has a plate-like structure with a specific thickness, the thickness of which corresponds to the thickness of the prepared irregularly shaped magnet.

[0086] Optionally, the powder distribution device 2 includes a support plate 21 and a powder distribution plate 22. Figure 9 is a structural schematic diagram of the support plate, and Figure 10 is a structural schematic diagram of the powder distribution plate. Please refer to Figures 3, 9, and 10. The support plate 21 and the powder distribution plate 22 are stacked. A first hollow region 21a is provided on the support plate 21, and a powder distribution channel 221 is provided on the powder distribution plate 22, penetrating through the powder distribution plate 22. The first hollow region 21a and the powder distribution channel 221 correspond to each other. During the use of the mold, the powder distribution device 2 and the powder filling device 1 are stacked so that the powder distribution plate 22 and the powder filling plate 11 are in contact to achieve precise powder distribution.

[0087] Optionally, the powder distribution plate 22 and the powder filling plate 11 are identical in shape and size, so that the powder distribution channel 221 and the powder filling channel 111 correspond one-to-one, which is beneficial to the accuracy of the powder distribution device 2 in distributing powder into the mold cavity 101.

[0088] Optionally, referring to Figure 2, the length of the support plate 21 along the X-axis is greater than the length of the powder distribution plate 22 along the X-axis. That is, the length of the support plate 21 is greater than the length of the powder distribution plate 22. This facilitates the operation of the powder distribution device 2 during the preparation of irregularly shaped magnets using the mold, and makes it easier for the powder distribution device 2 to be placed on the powder filling device 1 and removed from the filling device. Furthermore, the support plate 21 can simply satisfy the condition that its length along the Y-axis is greater than the length of the powder distribution plate along the Y-axis. Alternatively, the support plate 21 can simultaneously satisfy both the condition that its length along the X-axis is greater than the length of the powder distribution plate 22 along the X-axis and that its length along the Y-axis is greater than the length of the powder distribution plate 22 along the Y-axis. This application does not impose any restrictions here; it is sufficient that the larger dimension of the support plate 21 is greater than the dimension of the powder distribution plate 22.

[0089] Optionally, the powder distribution channel 221 also includes a reinforcing plate 23. Figure 11 is a schematic diagram of the reinforcing plate. Please refer to Figures 3 and 11. The reinforcing plate 23 is disposed on the side of the support plate 21 away from the powder distribution plate 22. The reinforcing plate 23 and the powder distribution plate 22 are located on both sides of the support plate 21, so as to extend the powder distribution path and improve the uniformity of powder distribution. When the powder distribution device 2 and the powder filling device 1 are stacked, that is, the powder distribution device 2 is located on top of the powder filling device 1, and the powder distribution channel 221 is completely aligned with the mold cavity 101 along the direction from the powder distribution device 22 to the powder filling device 1. This allows the magnetic material to smoothly enter the powder distribution frame 21 through the powder distribution channel 221 and pass through the second side of the powder distribution frame 21 into the mold cavity 101, realizing the filling process of the magnetic material in the mold cavity 101. Since the powder distribution channel 221 and the mold cavity 101 have the same shape, the accuracy of the magnetic material filling into the mold cavity 101 is guaranteed. Moreover, the magnetic material reaches the mold cavity 101 after passing through the powder distribution device 22, which extends the filling path of the magnetic material and improves the density of the magnetic material in the mold cavity 101, which is beneficial to improving the forming density of the magnet.

[0090] Optionally, the length of the reinforcing plate 23 along the Z-axis is greater than the length of the support plate 21 along the Z-axis, and the length of the reinforcing plate 23 along the Z-axis is greater than the length of the powder distribution plate 22 along the Z-axis. The length along the Z-axis is the thickness, meaning the thickness of the reinforcing plate 23 is greater than the thickness of the support plate 21 and the powder distribution plate 22. This helps to extend the powder distribution path and improve the uniformity of powder distribution. Since the support plate 21 enables portable operation of the powder distribution device 2, this application does not limit the length and width of the reinforcing plate 23; those skilled in the art can set them as needed.

[0091] Optionally, in the powder distribution device 2, the support plate 21 and the powder distribution plate 22 are detachably connected, and the support plate 21 and the reinforcing plate 23 are detachably connected to avoid the problem of decreased powder distribution accuracy caused by the displacement of a certain component during the use of the powder distribution device 2. Preferably, the support plate 21, the powder distribution plate 22, and the reinforcing plate 23 are detachably connected.

[0092] Optionally, the mold also includes a fixing device 4. Figure 12 is a structural schematic diagram of the fixing device 4 fixing the powder filling device 1 and the cover plate 3. The fixing device includes a first fixing plate 41 set on the top of the cover plate 3, a second fixing plate 42 set on the bottom of the powder filling device, and a locking member 43 for fixing the first fixing plate 41 and the second fixing plate 42. The locking member 43 is used to lock the cover plate 3 and the powder filling device 2 along the X-axis, Y-axis, and Z-axis directions to avoid uneven distribution of the magnetic material loaded in the mold cavity 101 due to shaking. It can be understood that multiple locking members 43 are provided, and multiple locking members 43 are arranged around the cover plate 3 and the powder filling device 2 for fixing. The locking member 43 can be, for example, a locking rod used in conjunction with the first fixing plate 41 and the second fixing plate 42. The locking rod passes through the first fixing plate 41 and the second fixing plate 42 and is detachably connected to the first fixing plate 41 and the second fixing plate 42 to realize locking and unlocking operations.

[0093] Optionally, Figure 13 is a structural schematic diagram of the first preset shape. Please refer to Figure 13. The first preset shape includes at least one of bread shape, tile shape and tile-like shape. Specifically, Figure 13(a) is a structural schematic diagram of the bread shape, Figure 13(b) is a structural schematic diagram of the tile shape, and Figure 13(c) is a structural schematic diagram of the tile-like shape.

[0094] In the mold of this application, each component is a detachable structure, which facilitates the setting of the mold cavity 101 before molding and the demolding of the green blank after molding, thereby improving production efficiency.

[0095] Figure 14 is a flowchart of the preparation process of an irregularly shaped magnet provided in this embodiment. Referring to Figure 14, the irregularly shaped magnet of this application is prepared using the above-mentioned mold, including the following steps:

[0096] The powder distribution device 2 and the powder filling device 1 are stacked, so that the mold cavity 101 and the powder distribution channel 221 correspond one-to-one;

[0097] The magnetic material is introduced into the mold cavity 101 through the powder distribution channel 221, and the magnetic material is formed into a blank of the first preset shape in the mold by a near-pressureless molding process.

[0098] Remove the powder application device 2 and seal the mold cavity 101 with the cover plate 3;

[0099] The billet is subjected to magnetic orientation treatment to obtain a magnetic steel intermediate.

[0100] The intermediate magnetic steel is heat-treated to form a permanent magnet block, thus obtaining an irregularly shaped magnetic steel.

[0101] The near-pressureless forming process, magnetic orientation treatment, and heat treatment are all carried out in a low-oxygen atmosphere with an oxygen content of less than or equal to 10 ppm.

[0102] In the above-mentioned scheme, this application obtains a blank with controllable size and shape by using mold-assisted and near-pressureless forming processes. The shape of the mold can be designed according to the finished size of the irregularly shaped magnet, eliminating the need for blank cutting and greatly improving production efficiency. Simultaneously, the near-pressureless forming process is carried out under normal pressure or slight pressure, resulting in less raw material loss and lower internal stress and warping deformation in the prepared blank, which is beneficial to improving the mechanical stability of the prepared irregularly shaped magnet. Furthermore, the blank undergoes magnetic orientation treatment to acquire magnetism. Finally, the irregularly shaped magnet is obtained through heat treatment. This application uses a two-stage process of forming followed by magnetic orientation treatment, which strengthens the formed blank during the orientation process, increasing the forming density and orientation degree of the magnet, thereby obtaining irregularly shaped magnet products with high remanence and high coercivity.

[0103] The preparation method of the magnet will now be clearly and completely described with reference to the accompanying drawings of the embodiments of the present invention. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0104] S100 provides the aforementioned mold.

[0105] S200, the powder distribution device 2 and the powder filling device 1 are stacked, so that the mold cavity 101 and the powder distribution channel 221 correspond one-to-one.

[0106] Optionally, before stacking the powder distribution device 2 and the powder filling device 1, the assembly step of the powder distribution device 2 and the powder filling device 1 is included. Specifically, the reinforcing plate 23, the supporting plate 21, and the powder distribution plate 22 are stacked sequentially, aligning the second hollow region 23a, the first hollow region 21a, and the powder distribution channel 221, and the reinforcing plate 23, the supporting plate 21, and the powder distribution plate 22 are bolted together. The base plate 12 and the powder filling plate 11 are stacked and bolted together.

[0107] S300, the magnetic material is introduced into the mold cavity 101 through the powder distribution channel 221 for near-pressureless molding, so that the magnetic material forms a blank of the first preset shape in the mold cavity 101.

[0108] Optionally, magnetic raw materials refer to mixed fine powder obtained by sequentially passing magnetic raw materials through a rapid solidification process, a hydrogen crushing process, and an air jet milling process; magnetic raw materials are obtained by batching, mixing, smelting, and casting rare earth element raw material blocks through processes such as batching, mixing, smelting, and casting.

[0109] Optionally, the magnetic raw material includes metal powder or alloy powder composed of at least one element selected from iron, aluminum, nickel, cobalt, and copper. For example, the magnetic raw material includes neodymium iron boron alloy powder, ferrite powder, aluminum nickel cobalt powder, and iron chromium cobalt powder, etc. Of course, it can also be other powders with permanent magnetism. This application does not limit the raw materials of the magnetic raw material, which can be obtained through commercial channels, and those skilled in the art can also formulate it themselves.

[0110] Optionally, since the billet in this application has not undergone pressure treatment or isostatic pressing before magnetic orientation, the stress distribution inside the billet is uniform. Therefore, this application can select raw materials with smaller particle sizes for preparation, which is beneficial for obtaining the remanence of the magnet. The median particle size of the magnetic raw material is 1μm to 4μm, for example, it can be 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, or 4μm, etc., and of course, other values ​​within the above range are also possible; this application does not impose any limitations on this. Within the above range, it indicates that the particle size of the magnetic raw material in this application is small, which is beneficial for improving the stability of the magnetic permeability frequency of the magnetic raw material during subsequent magnetic orientation processing, and improving the magnetic permeability stability of the magnet.

[0111] Optionally, the density of the magnetic material filled into the mold cavity 101 is 2.7 g / cm³ to 4.0 g / cm³, for example, it can be 2.7 g / cm³, 3 g / cm³, 3.3 g / cm³, 3.5 g / cm³, 3.8 g / cm³, or 4.0 g / cm³, etc., and of course, other values ​​within the above range are also possible, which are not limited here. Within the above range, the density of the magnetic material in the mold cavity 101 is relatively low, and a product with a high degree of orientation can be obtained through subsequent magnetic orientation treatment.

[0112] Optionally, the magnetic raw material powder filling density distribution in each mold cavity 101 is less than or equal to 3%, for example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%, etc., and of course, it can be other values ​​within the above range, which are not limited here. The filling density distribution refers to the difference between the powder filling density in each mold cavity 101 and the average powder filling density of all mold cavities 101. Within the above-defined range, it indicates that the powder distribution in the multiple mold cavities 101 of this application is relatively uniform, which is beneficial to improving the quality uniformity of mass-produced magnets.

[0113] Optionally, when filling the mold cavity 101 with magnetic material through multiple powder distribution channels 221, the uniformity of the distribution of magnetic material in each powder distribution channel 221 should be ensured, so that the difference in the filling amount of magnetic material in multiple powder distribution channels 221 is less than 1%.

[0114] Optionally, the magnetic raw material is introduced into the mold cavity 101 using a near-pressureless forming method, including but not limited to gas impact injection, vibration, and compaction of surface powder with a punch. The process of forming the blank in this application is carried out under normal pressure or minimal pressure, resulting in less raw material loss and lower internal stress and warping deformation in the prepared blank, which is beneficial for improving the mechanical stability of the magnet.

[0115] Optionally, the mold and magnet manufacturing method of this application are mainly used in the manufacturing process of magnets with special shapes. The first preset shape includes, but is not limited to, at least one of bread-shaped magnets, tile-shaped magnets, and tile-like magnets. It can be understood that the first preset shape is the shape of the magnet finally prepared in this application. Compared with traditional rectangular magnets, the bread-shaped magnets, tile-shaped magnets, and tile-like magnets have the advantages of uniform air gap density distribution, small cogging torque, low noise, and easy fixation. They can be widely used in motors for power steering systems and further applied in automobiles containing motors for power steering systems.

[0116] S400, remove powder distribution device 2, and seal mold cavity 101 with cover plate 3.

[0117] This application removes the powder distribution device 2 and then places the cover plate 3 on the powder filling device 1, so that the cover plate 3 closes the mold cavity 101, and the cover plate 3 and the mold cavity 101 form a closed mold cavity.

[0118] Optionally, the cover plate 3 and the powder filling device 1 can be fixed with bolts, which is beneficial for subsequent magnetic orientation processing.

[0119] S500 is used to perform magnetic orientation treatment on the billet to obtain a magnetic steel intermediate.

[0120] In this step, the orientation direction of the billet needs to be determined in advance. After confirming the orientation direction, the powder-filling device 1 with the billet and the cover plate 3 are placed into a coil through which direct current flows. The coil can form a magnetic field, and the magnetic field is applied to the billet along the orientation direction. The magnetic field strength is gradually increased until the magnetic field of the billet reaches a saturation state, that is, magnetism is obtained. Optionally, the orientation direction of the billet in this application includes, but is not limited to, radial orientation and radial orientation, etc. Of course, other orientation directions are also possible, and this application does not limit them.

[0121] Optionally, the magnetic induction intensity for the magnetic orientation treatment is 2T to 7T, for example, 2T, 3T, 4T, 5T, 6T, or 7T, or other values ​​within the above range, which are not limited here. Since the billet of this application has not undergone pressure treatment or isostatic pressing treatment before magnetic orientation, the stress distribution inside the billet is uniform, allowing the billet of this application to undergo orientation treatment in an ultra-high magnetic field, ensuring the orientation degree and strength of the magnet.

[0122] Optional magnetic orientation methods include, but are not limited to, pulse orientation. Pulse orientation generates a short-term, ultra-strong magnetic field in the coil by discharging a high-voltage, small-capacity capacitor. High coercivity magnets can be obtained through the pulse orientation process. Furthermore, pulse orientation does not have special requirements for the power supply configuration of the work site and is convenient and flexible to use.

[0123] Optionally, during the magnetic orientation process of the billet, the powder filling device 1 and the cover plate 3 are fixed in position beforehand using the fixing device 4 to prevent the powder filling device 1 from shaking during the orientation process and affecting the orientation effect.

[0124] S600 involves heat-treating the intermediate magnetic steel to form a permanent magnet block, thus obtaining a magnetic steel.

[0125] Optionally, before heat treating the magnetic steel intermediate, remove the cover plate 3, invert the powder filling device 1 onto the firing plate, and loosen the fixation between the bottom plate 12 and the powder filling plate 11, so that the magnetic steel intermediate is placed on the firing plate.

[0126] Optionally, before heat treating the magnet intermediate, remove the cover plate 3 and loosen the fixation between the bottom plate 12 and the powder filling plate 11, so that the magnet intermediate is placed on the bottom plate 12. In this way, the bottom plate 12 can be used to close the mold cavity 101 and also as a firing plate for heat treatment sintering.

[0127] Optionally, the heat treatment temperature is 1000℃~1100℃, specifically 1000℃, 1010℃, 1020℃, 1030℃, 1040℃, 1050℃, 1060℃, 1070℃, 1080℃, 1090℃ or 1100℃, etc. Within the above-mentioned range, it can be ensured that the magnetic steel intermediate is completely sintered, and magnetic steel products with high hardness and good magnetic properties are obtained.

[0128] In some embodiments, the heat treatment time is 2h to 6h, specifically 2h, 3h, 4h, 5h or 6h, etc., and of course other values ​​within the above range are also possible. This application does not limit this.

[0129] In some embodiments, the near-pressure-free forming process, magnetic orientation treatment, and heat treatment of this application are all carried out in a low-oxygen atmosphere. The oxygen content in the low-oxygen atmosphere is less than or equal to 10 ppm, for example, it can be 1 ppm, 3 ppm, 5 ppm, 7 ppm, 9 ppm, or 10 ppm, etc. Within the above range, the risk of oxidation of the magnetic raw material is reduced, and it is also beneficial to improve the crystal orientation degree of the blank during the orientation process. At the same time, it ensures uniform stress distribution of the blank, reduces the orientation difficulty, avoids the introduction of impurities during the heat treatment process, reduces the purity of the magnet, and improves the quality of the magnet.

[0130] The preparation method of this application differs from the traditional molding process. The pressing and orientation of the magnetic raw material are carried out separately. The pressing is achieved through a near-pressure-free process, which does not require cutting or pressure. This results in a uniformly distributed stress in the blank, avoiding the risk of cracking and deformation in the blank during subsequent processing. At the same time, the near-pressure-free molding process is simple and has a high raw material utilization rate. It can shorten the process flow and improve product utilization. The blank before orientation is protected by a mold and then oriented in an ultra-strong magnetic field of 3T~7T to ensure the orientation degree and magnetic field strength of the magnet.

[0131] This application also provides a magnetic steel, which is prepared according to the above-described mold and preparation method, and has the characteristics of uniform stress distribution, high density, good orientation, high remanence, and high coercivity.

[0132] In some embodiments, the density of the magnet is 2.0 g / cm3 to 4.2 g / cm3; specifically, it can be 2.0 g / cm3, 2.5 g / cm3, 2.8 g / cm3, 3.2 g / cm3, 3.5 g / cm3, 3.8 g / cm3 or 4.2 g / cm3, etc., and of course, it can be other values ​​within the above range, which are not limited here.

[0133] In some embodiments, the orientation degree of the magnet is greater than or equal to 97%, specifically 97%, 97.5%, 98%, 98.5% or 99%, etc., and of course, other values ​​within the above range are also possible, which are not limited here.

[0134] This application also provides an electric motor that includes the magnet described above. The magnet has the advantages of high remanence, high coercivity, uniform air gap magnetic density, low cogging torque, low noise, and easy installation. It can be widely used in various drive motors of electronic devices such as automobiles.

[0135] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0136] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be defined by the scope of the claims of this application.

Claims

1. A mold, characterized in that, The mold is used to produce irregularly shaped magnets, and the mold includes: A powder filling device (1) has a plurality of mold cavities (101) with one end open, and the mold cavity (101) has a first preset shape; The powder distribution device (2) has a powder distribution area (2a) and a plurality of powder distribution channels (221) are provided in the powder distribution area (2a). The powder distribution channels (221) penetrate the powder distribution device (2) along a first direction. The powder distribution channels (221) have a second preset shape. The powder distribution channels (221) are positioned opposite to the mold cavity (101). The first preset shape and the second preset shape are the same. The first direction is parallel to the height direction of the powder distribution device (2). Cover plate (3), the cover plate (3) is used to close the mold cavity (101).

2. The mold according to claim 1, characterized in that, The powder filling device (1) includes a base plate (12) and a powder filling plate (11) disposed on the base plate (12). The powder filling plate (11) has a powder filling channel (111). The powder filling channel (111) passes through the powder filling plate (11) along the first direction. The powder filling channel (111) and the powder distribution channel (221) are positioned opposite each other. The powder filling channel (111) and the base plate (12) surround and form the mold cavity (101).

3. The mold according to claim 1, characterized in that, The powder distribution device (2) includes a support plate (21) and a powder distribution plate (22) disposed on one side of the support plate (21). The powder distribution channel (221) is disposed on the powder distribution plate (22). The support plate (21) has a first hollow region (21a), which corresponds to the powder distribution channel (221).

4. The mold according to claim 3, characterized in that, The length of the support plate (21) along the second direction is greater than the length of the powder distribution plate (22) along the second direction, and the second direction is perpendicular to the first direction.

5. The mold according to claim 3, characterized in that, The powder distribution device (2) further includes a reinforcing plate (23) disposed on one side of the support plate (21). The reinforcing plate (23) and the powder distribution plate (22) are respectively disposed on both sides of the support plate (21). The reinforcing plate (23) is disposed on the side of the support plate (21) away from the powder filling device (1). The reinforcing plate (23) has a second hollow region (23a), which corresponds to the first hollow region (21a). The length of the reinforcing plate (23) along the first direction is greater than the length of the support plate (21) along the first direction, and the length of the reinforcing plate (23) along the first direction is greater than the length of the powder distribution plate (22) along the first direction.

6. The mold according to claim 1, characterized in that, The mold also includes a fixing device (4), which is used to lock the cover plate (3) and the powder distribution device (2) along the first direction and the second direction, wherein the second direction is perpendicular to the first direction.

7. The mold according to claim 1, characterized in that, The powder filling device (1) and the powder dispensing device (2) are detachably connected; and / or the powder dispensing device (2) and the cover plate (3) are detachably connected.

8. The mold according to any one of claims 1 to 7, characterized in that, The first preset shape includes at least one of bread shape, tile shape, and tile-like shape.

9. A method for preparing irregularly shaped magnets, characterized in that, The preparation is carried out using the mold according to any one of claims 1 to 8, comprising the following steps: Provide a mold as described in any one of claims 1 to 8; The powder distribution device (2) and the powder filling device (1) are stacked together so that the mold cavity (101) and the powder distribution channel (221) correspond one-to-one; The magnetic material is introduced into the mold cavity (101) through the powder distribution channel (221) for near-pressureless molding, so that the magnetic material forms a blank of a first preset shape in the mold cavity (101); Remove the powder distribution device (2) and close the mold cavity (101) with the cover plate (3); The magnetic raw material in the mold cavity (101) is subjected to magnetic orientation treatment to obtain a magnetic steel intermediate; The intermediate magnetic steel body is heat-treated to form a permanent magnet block, thereby obtaining an irregularly shaped magnetic steel. The near-pressureless forming process, magnetic orientation treatment, and heat treatment are all carried out in a low-oxygen atmosphere, where the oxygen content is less than or equal to 10 ppm.

10. The preparation method according to claim 9, characterized in that, Before performing magnetic orientation treatment on the magnetic material in the mold cavity (101), the cover plate (3) and the powder filling device (1) are locked along the first and second directions using the fixing device (4).

11. The preparation method according to claim 9, characterized in that, The near-pressureless molding process includes at least one of gas impact, vibration, and permanent magnet raw material surface compaction treatment; The median particle size of the magnetic raw material is 1 μm to 4 μm; The magnetic material is introduced into the mold cavity (101) through the powder distribution channel (221) with a powder distribution density of 2.7 g / cm³. 3 ~4.0g / cm 3 The density distribution of magnetic raw materials in the mold cavity (101) of the powder filling device (1) is less than or equal to 3%. The orientation degree of the billet is greater than or equal to 97%; The magnetic induction intensity of the magnetic orientation treatment is 2T~7T, and the magnetic orientation treatment method includes pulse orientation.

Images