Screen printing plate for selective diffusion of screen printing of sintered neodymium-iron-boron magnet

Abstract

The utility model relates to the technical field of sintered neodymium iron boron grain boundary diffusion, and aims to solve the problem of controlling the use amount of a heavy rare earth material in a silk-screen printing process. The utility model discloses a sintered neodymium-iron-boron magnet silk-screen printing area-selecting diffusion screen printing plate which comprises a screen frame and a screen face, the screen face comprises a first area and a second area, the first area is an area where silk-screen printing materials do not pass through, and the second area is an area where the silk-screen printing materials pass through. Therefore, the use amount of the heavy rare earth material can be greatly reduced in the silk-screen printing process, so that the production cost is reduced, the drying time of the magnet after silk-screen printing is shortened, and the production efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of sintered NdFeB magnet screen printing grain boundary diffusion, in particular to a screen plate for sintered NdFeB magnet screen printing selected area diffusion. Background Art

[0002] Sintered NdFeB magnets are widely used in new energy, communications, wind power generation, robotics and intelligent manufacturing due to their excellent magnetic properties. How to improve the thermal stability of magnets to meet the requirements of the new energy field is a hot topic in the research of sintered NdFeB magnets. The simplest and most direct way to improve the thermal stability of magnets is to increase the coercive force of magnets. Grain boundary diffusion using screen printing is a coercive force enhancement technology. It has a great cost advantage in the preparation of small-sized high-coercive force magnets due to its simple process and low cost. Through grain boundary diffusion, the thin layer of rare earth-rich phase in the magnet becomes more continuous and smooth, which weakens the coupling effect between grains and is beneficial to the improvement of the coercive force of the magnet. At the same time, heavy rare earth elements diffuse into the interior of the magnet through the grain boundaries, partially replacing the rare earth elements at the edge of the main phase grains to form (Nd, HRE) 2 Fe 14 The B (HRE = Dy, Tb) shell increases the magnetocrystalline anisotropy field at the grain edge, increases the energy of the reverse magnetization domain-shaped nuclear field, and improves the coercive force of the magnet.

[0003] However, heavy rare earths are non-renewable resources and are expensive. How to reduce costs and maximize the role of heavy rare earth elements has become the focus of attention today. In the use of traditional printing screens, heavy rare earth Tb and Dy metal powders are mixed into ink. When printing, ink is poured into one end of the screen printing plate, and a scraper is used to apply a certain pressure to the ink part on the screen printing plate. At the same time, the screen printing plate moves at a constant speed toward the other end. The ink is squeezed from the mesh by the scraper to form a film on the magnetic sheet during movement. However, in reality, printing heavy rare earth elements in a fixed area on the outside of the magnet can significantly improve the coercive force of the magnet. The traditional process of printing heavy rare earth elements on the entire surface of the magnet in the screen printing not only does not significantly improve the performance of the magnet, but also causes a waste of heavy rare earth materials and increases production costs. Utility Model Content

[0004] (I) Purpose of the utility model

[0005] The utility model aims to provide a screen for screen printing selected area diffusion of sintered NdFeB magnets, which reduces the use of heavy rare earth elements by setting an area on the screen to block the passage of printed materials, while improving the coercive force of the magnet to achieve the same effect.

[0006] (II) Technical solution

[0007] In order to solve the above problems, the utility model provides a sintered NdFeB screen printing selected area diffusion screen, including a screen frame and a screen surface;

[0008] The mesh surface is fixed on the mesh frame, and the mesh surface includes a first area and a second area; the first area includes a plurality of parts, and the plurality of parts are arranged on the mesh surface in a matrix distribution; the second area closes and surrounds the plurality of parts of the first area;

[0009] The first area is an area where the screen printing material does not pass, and the second area is an area where the screen printing material passes.

[0010] Preferably, each of the parts is of the same axisymmetric pattern; the number of rows and columns of the matrix are both greater than or equal to 2.

[0011] Preferably, the shape of each of the parts matches the shape of the surface to be printed of the magnet to be printed, and the area of ​​each of the parts is smaller than the area of ​​the surface to be printed of the magnet to be printed.

[0012] Preferably, during the printing process, the center of each of the parts coincides with the center of the surface to be printed of the magnet to be printed.

[0013] Preferably, the screen is used to print a plurality of magnets simultaneously, the number of the plurality of magnets is the same as the number of the plurality of parts, and the plurality of magnets are arranged in a distribution form that is the same as the matrix distribution.

[0014] Preferably, the area of ​​the first region is smaller than the area of ​​the second region.

[0015] Preferably, the mesh size of the mesh is 150 to 200 meshes.

[0016] Preferably, the material of the first area is photosensitive adhesive.

[0017] Preferably, the material of the second region is nylon mesh.

[0018] Preferably, the mesh frame is made of aluminum or wood.

[0019] By such an arrangement, the screen surface of the screen is divided into areas where printing materials can pass through and areas where printing materials cannot pass through, thereby achieving selective printing of the magnet to be printed.

[0020] (III) Beneficial effects

[0021] The above technical solution of the utility model has the following beneficial technical effects:

[0022] (1) By partitioning the screen surface, the area through which the printed material passes is reduced, so that the coercive force of the magnet can achieve the same effect, while reducing the amount of heavy rare earth materials used and reducing production costs.

[0023] (2) By reducing the printing area on the magnet, the drying time of the magnet printing paste is reduced, the energy consumption is reduced and the production efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of a screen plate for screen printing selected area diffusion of sintered NdFeB magnets provided by an embodiment of the utility model;

[0025] Figure 2 It is a front view schematic diagram of a magnet after screen printing is completed by the screen plate according to the first embodiment of the utility model;

[0026] Figure 3 It is a schematic diagram of the structure of a common screen for screen printing of sintered NdFeB magnets in the prior art;

[0027] Figure 4 It is a schematic diagram of the front side of a magnet that is screen-printed using a common screen in the prior art.

[0028] Reference numerals:

[0029] 1. Screen frame; 2. Screen surface; 21. First area; 21a. Part; 22. Second area;

[0030] 1', frame; 2', screen; 21', printing area. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is further described in detail below in combination with specific implementation methods and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the utility model. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the utility model.

[0032] The accompanying drawings show schematic diagrams of structures according to embodiments of the utility model. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clarity. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0033] In the description of the present invention, it should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0034] The technical solution of the utility model is described in detail below with reference to the accompanying drawings. According to one embodiment of the utility model, a screen for screen printing selected area diffusion of sintered NdFeB magnets is provided. The structural schematic diagram of the screen is shown in FIG. Figure 1 As shown, the screen includes a screen frame 1 and a screen surface 2, the screen surface 2 includes a first area 21 and a second area 22, wherein the first area 21 includes a plurality of parts 21a, the plurality of parts 21a are arranged on the screen surface 2 in a matrix distribution, the second area 22 closes and surrounds the plurality of parts 21a of the first area 21, the first area 21 is an area where the screen printing material does not pass, and the second area 22 is an area where the screen printing material passes, preferably, the area of ​​the first area 21 is smaller than the area of ​​the second area 22. Through such an arrangement, the screen surface 2 of the screen is divided into an area where the printing material can pass and an area where the printing material cannot pass, so as to realize the selective printing of the magnet to be printed, thereby reducing the area of ​​screen printing, so that the coercive force of the magnet achieves the same effect while reducing the use of heavy rare earth materials, and realizing the purpose of saving heavy rare earth resources.

[0035] Combination Figure 1 In a preferred case, each part 21a is the same axisymmetric pattern, for example, it can be a rectangle, a circle or a polygon. The number of rows and columns arranged in a matrix is ​​greater than or equal to 2. It should be noted that the shape and size of part 21a are not limited here, and the number of rows and columns of the matrix arrangement of part 21a is adjusted according to the number of printed magnets. Further, the shape of each part 21a matches the shape of the surface to be printed of the magnet to be printed, the area of ​​part 21a is smaller than the area of ​​the surface to be printed of the magnet to be printed, and the center of part 21a coincides with the center of the surface to be printed of the magnet to be printed. For example, when the surface to be printed of the magnet to be printed is a rectangle, the shape of part 21a is also a rectangle, and the length and width of the rectangle of part 21a are slightly smaller than the length and width of the rectangle of the surface to be printed of the magnet to be printed, so that the heavy rare earth slurry is printed on the four sides of the magnet surface, the coercive force of the magnet is improved, and the heavy rare earth material is saved at the same time. Furthermore, the mesh number of the mesh surface 2 is 150 to 200 meshes. In the process of screen printing, the mesh surface 2 within this range is convenient for controlling the total weight gain of the heavy rare earth elements printed on the surface of the magnet to about 0.3% of the weight of the magnet. It should be noted that when screen printing is performed on the magnet, the two opposite sides of the magnet are usually printed. The total weight gain of the heavy rare earth elements here means that after printing on the two sides, the total weight gain of the heavy rare earth elements is about 0.3% of the weight of the magnet. Ensure that the coercive force of the magnet meets the requirements and save the amount of heavy rare earth.

[0036] The shape of the portion 21a in the first area 21 here is the same as the shape of the surface to be printed of the magnet to be printed. For magnets of different shapes, the first area 21 in the screen of the corresponding shape is processed and set, and at the same time, it is ensured that the portion 21a in the first area 21 is located at the center of the surface to be printed of the magnet during the magnet printing process. Preferably, the first area 21 is made of photosensitive adhesive material, which effectively blocks the printing paste from passing through the screen 2. At the same time, after the printing is completed, it is more conducive to the recovery of the remaining slurry on the screen 2, thereby improving the reuse rate of heavy rare earth materials. Further, the second area 22 is made of nylon screen material, and the printing slurry can pass through the screen 2 made of nylon screen material, and during the printing process, it can withstand the pressure on the surface of the screen 2. At the same time, the nylon screen is also conducive to the recovery of heavy rare earth slurry. Further, the screen frame 1 is made of aluminum or wood material, which is conducive to reducing the overall weight of the screen and is convenient for installation and fixing during the printing process. In a preferred case, the screen frame 1 and the screen 2 are fixedly connected to ensure the accuracy of printing.

[0037] Combination Figure 2 , the screen can print multiple magnets at the same time. The number of magnets is determined according to the size of the screen 2, which is the same as the number of parts 21a in the first area 21. The positions of the multiple magnets correspond to the positions of the parts 21a. When printing multiple magnets, each part 21a is located at the center of the surface to be printed of each magnet. For example, when printing multiple magnets at the same time, magnets of the same size are arranged in a matrix, and the surfaces to be printed of the magnets to be printed are pieced together into a plane. The screen is fixed above the surface to be printed, and the slurry containing heavy rare earth is poured on the screen. The slurry passes through the second area 22 to complete the printing of multiple magnets. Figure 2 It is a front view schematic diagram of a magnet after screen printing according to the screen of the first embodiment of the utility model. The surface of the magnet after printing is divided into two areas. The middle position is the area overlapping with part 21a during the printing process. No slurry is printed on the surface of this area. The surrounding area of ​​the magnet surface is a blank area overlapping with the second area 22 during the printing process. This area is the printing area through which the slurry passes.

[0038] Combination Figure 3 and Figure 4 , a common screen for screen printing of sintered NdFeB magnets in the prior art, and a magnet screen-printed using the screen are provided. The common screen in the prior art includes a frame 1' and a screen 2', wherein a printing area 21' is formed on the entire screen 2', and the screen 2' can pass heavy rare earth slurry, and the surface of the magnet printed using the screen is also fully covered with heavy rare earth slurry, and a large amount of heavy rare earth material is used in the process.

[0039] The above two screen printing Figure 2 and Figure 4The two magnets were dried and heat treated in the same process to obtain magnets after grain boundary diffusion. The magnetic properties of these magnets were tested, and the properties of the magnets before grain boundary diffusion are shown in Table 1 below:

[0040] Table 1 Original properties of magnets

[0041] Magnet Brand HkDJ Br / kGs (BH)max / MGOe Q 50H 16.47 13.63 45.77 0.968

[0042] Figure 2 The magnet performance test results are shown in Table 2 below:

[0043] Table 2 Properties of magnets after screen printing selected area grain boundary diffusion

[0044]

[0045] Figure 4 The magnet performance test results are shown in Table 3 below:

[0046] Table 3 Properties of magnets after grain boundary diffusion of common screen

[0047]

[0048] By comparing Table 2 and Table 3, it can be seen that when the screen printing selected area diffusion screen provided by the utility model is used, the area of ​​the printed area on the magnet is reduced, and the use amount of heavy rare earth materials is reduced, saving production costs; in the subsequent steps after the magnet printing is completed, due to the reduction in the printing area of ​​heavy rare earth, the time and energy consumption in the drying process are also reduced, improving production efficiency. Moreover, the performance of the magnet finally obtained is basically the same as that of the magnet obtained by ordinary screen printing.

[0049] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation on the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the claims attached to the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the attached claims, or the equivalent forms of such scope and boundaries.

Claims

1. A sintered NdFeB screen printing selected area diffusion screen, characterized in that: The screen comprises a screen frame (1) and a screen surface (2); The mesh surface (2) is fixed on the mesh frame (1), and the mesh surface (2) comprises a first area (21) and a second area (22); the first area (21) comprises a plurality of parts (21a), and the plurality of parts (21a) are arranged on the mesh surface (2) in a matrix distribution; the second area (22) encloses and surrounds the plurality of parts (21a) of the first area (21); The first area (21) is an area where the screen printing material does not pass, and the second area (22) is an area where the screen printing material passes; Each of the parts (21a) is of the same axisymmetric pattern; The number of rows and columns of the matrix are both greater than or equal to 2; The shape of each of the parts (21a) matches the shape of the surface to be printed of the magnet to be printed, and the area of ​​each of the parts (21a) is smaller than the area of ​​the surface to be printed of the magnet to be printed; During the printing process, the center of each of the portions (21a) coincides with the center of the surface to be printed of the magnet to be printed; The screen is used to print a plurality of magnets simultaneously, the number of the plurality of magnets is the same as the number of the plurality of parts (21a), and the plurality of magnets are arranged in a distribution form that is the same as the matrix distribution; The area of ​​the first region (21) is smaller than the area of ​​the second region (22).

2. The screen according to claim 1, characterized in that: The mesh number of the mesh surface (2) is 150 to 200 meshes.

3. The screen according to any one of claims 1 to 2, characterized in that: The material of the first region (21) is photosensitive adhesive.

4. The screen according to any one of claims 1 to 2, characterized in that: The material of the second region (22) is nylon mesh.

5. The screen according to any one of claims 1 to 2, characterized in that: The material of the mesh frame (1) is aluminum or wood.

Images