Sintered material box capable of reducing one-time forming cracks of sintered neodymium iron boron

Abstract

The utility model discloses a sintering material box capable of reducing one-time forming cracks of sintered neodymium iron boron, which belongs to the technical field of neodymium iron boron preparation and comprises a box body, and a plurality of protrusions are fixedly arranged at the bottom of the box body in an array mode. And the contact area with the bottom surface of the box body can be greatly reduced, so that cracks of a one-time formed blank can be greatly reduced, the size consistency of products can be improved, meanwhile, spreading of aluminum oxide powder is replaced, and the production cost is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of neodymium iron boron preparation technology, specifically relating to a sintering material box for reducing cracks in one-time molding of sintered neodymium iron boron. Background Technology

[0002] The one-step molding technology for sintered NdFeB magnets represents a significant technological innovation in the field of rare earth permanent magnet materials. Its development is closely related to industry demands, technological bottlenecks, and the trend towards green manufacturing. This one-step molding technology directly prepares near-net-shape magnets by integrating magnetic field orientation, pressing, and sintering processes, significantly optimizing the production process. It reduces molding pressure and internal stress, lowering the green body cracking rate from 15% in traditional processes to below 5%, while also reducing additive usage and carbon content. Traditional sintered NdFeB production processes involve multiple steps, including melting, hydrogen crushing, powdering, molding, isostatic pressing, and sintering, resulting in complex processes, high costs, and low material utilization. For example, the isostatic pressing process commonly used by domestic companies not only increases the green body's corner-breaking rate and contamination risk but also reduces magnet orientation due to residual hydraulic oil or moisture, leading to remanence loss.

[0003] Existing sintering boxes have a flat bottom structure. When the formed green blank is placed at the bottom of the sintering box, it is in complete contact with the bottom of the sintering box. The industry generally uses alumina powder to evenly spread on the bottom of the sintering box to prevent the green blank from sticking to the sintering box during the sintering process. During sintering shrinkage, the green blank may shrink unevenly due to friction, which may cause cracks or result in a large difference in size between the surface of the green blank that is attached to the box and other surfaces.

[0004] Therefore, it is necessary to propose a sintering box that reduces cracks in one-time molding of sintered NdFeB to solve the above problems. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a sintering box that reduces cracks in one-time molding of sintered NdFeB, in order to solve the problem that in the prior art, the bottom of the sintering box has a planar structure, and during sintering shrinkage, the blank is likely to shrink unevenly due to friction, which will cause cracks or lead to large differences in size between the blank's box-attached surface and other surfaces.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] This utility model provides a sintering box for reducing cracks in one-time molding of sintered NdFeB, comprising: a box body, wherein the bottom of the box body is provided with an array of protrusions.

[0008] Furthermore, the protrusion includes any one of hemispherical protrusion, conical protrusion, and cylindrical protrusion;

[0009] Furthermore, a base plate is movably disposed within the box, and the protrusion is fixedly disposed on the base plate.

[0010] Furthermore, the box body is provided with a loading position for placing the green embryo and a limiting position arranged around the loading position. The hemispherical protrusion is arranged in the loading position, and multiple spherical protrusions are arranged in an array in the limiting position. The distance between the center of the spherical protrusion and the bottom wall of the box body is greater than the distance between the apex of the hemispherical protrusion and the bottom wall of the box body.

[0011] Furthermore, the bottom wall of the box is arrayed with multiple hemispherical grooves that cooperate with the spherical protrusions and through holes that communicate with the hemispherical grooves. The spherical protrusions are placed in the hemispherical grooves to form hemispherical protrusions at the bottom of the box. A sliding rod that is fixedly connected to the spherical protrusions is slidably connected in the through holes. Sliding the sliding rod can adjust the height of the spherical protrusions.

[0012] Furthermore, the box body is provided with a plurality of threaded holes that are coaxially arranged and connected with the through holes, and a threaded rod that is rotatably connected to the slide rod is threaded into the threaded hole.

[0013] Furthermore, the threaded hole extends through the bottom of the box.

[0014] Furthermore, the outer diameter of the threaded rod is larger than the diameter of the slide rod.

[0015] Furthermore, the circular spherical protrusion of the threaded rod extends out of the bottom of the box and is fixedly connected to a knob.

[0016] Furthermore, the diameter of the knob is larger than the diameter of the threaded rod.

[0017] The beneficial effects of this utility model are as follows:

[0018] 1. By setting protrusions at the bottom of the box, the contact area between the pressed green blank and the bottom surface of the box can be greatly reduced when it is directly placed into the box. Therefore, the generation of cracks in the one-time molding blank can be greatly reduced, and the product dimensional consistency can be improved. At the same time, it can replace the spreading of alumina powder and reduce production costs.

[0019] 2. By setting a loading position, after the green embryo is placed in the loading position, the spherical protrusion can surround the green embryo to limit the side wall of the green embryo, thereby ensuring the stability of the green embryo during the movement of the box and avoiding the problem of poor stability of the green embryo due to reduced contact friction.

[0020] 3. The corresponding spherical protrusion is moved upward by the sliding rod to form a limiting position around the green embryo. The area formed by the limiting position is the loading position, which enables the stable placement of green embryos of different sizes and shapes.

[0021] Other advantages, objectives, and features of this invention will be set forth in the following description and will be apparent to those skilled in the art to some extent, or may be learned by practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description

[0022] To make the objectives, technical solutions, and beneficial effects of this utility model clearer, the following drawings are provided for illustration:

[0023] Figure 1 This is a schematic diagram of the box structure of Embodiment 3 of this utility model;

[0024] Figure 2 This is a schematic diagram of the box structure of Embodiment 4 of this utility model;

[0025] Figure 3 This is a schematic diagram of the box structure of Embodiment 1 of this utility model;

[0026] Figure 4 This is a schematic diagram of the box structure of Embodiment 2 of this utility model;

[0027] Figure 5 This is a schematic diagram of the base plate structure of Embodiment 5 of this utility model;

[0028] Figure 6 This is a side sectional view of the box structure in Embodiment 6 of this utility model;

[0029] Figure 7 This is an embodiment of the present utility model. Figure 6 A magnified view of part A in the middle;

[0030] Figure 8 This is a schematic diagram of the box structure as a comparative example of this utility model.

[0031] The following are the markings in the attached diagram: box body 1, loading position 101, limiting position 102, hemispherical groove 103, through hole 104, threaded hole 105, protrusion 2, hemispherical protrusion 201, conical protrusion 202, cylindrical protrusion 203, spherical protrusion 3, slide bar 4, threaded bar 5, knob 6, base plate 7. Detailed Implementation

[0032] Example 1, such as Figure 3This utility model provides a sintering box for reducing cracks in one-time molding of sintered NdFeB, comprising: a box body 1, wherein the bottom of the box body 1 is provided with a plurality of protrusions 2, the protrusions 2 including conical protrusions 202. When the pressed green blank is placed on the conical protrusions 202 in the box body 1, it is not necessary to spread alumina powder at the bottom of the sintering box. However, due to the small contact area, the bottom of the green blank is subjected to greater force, and the one-time molded blank has not undergone isostatic pressing process, so the density of the blank is lower than that of isostatic pressed blank. Some blanks with tiny scratches and cracks appear on the box surface, but the overall crack rate is lower than that of ordinary sintering boxes.

[0033] Example 2, as Figure 4 This utility model provides a sintering box for reducing cracks in one-time molding of sintered NdFeB, comprising: a box body 1, wherein the bottom of the box body 1 is provided with a plurality of protrusions 2, the protrusions 2 including cylindrical protrusions 203, and the pressed green blank is placed on the cylindrical protrusions 203 of the box body 1, which eliminates the need to spread alumina powder at the bottom of the sintering box. Compared with embodiment 1, the bottom cylindrical protrusions 203 of this embodiment have a larger contact area with the one-time molded green blank, which can avoid the small contact area and excessive force causing micro-cracks at the bottom of the green blank.

[0034] Example 3, as Figure 1 This utility model provides a sintering material box for reducing cracks in one-time molding of sintered NdFeB, comprising: a box body 1, wherein the bottom of the box body 1 is provided with a plurality of protrusions 2 arranged in an array, the protrusions 2 including hemispherical protrusions 201, the spacing between two adjacent hemispherical protrusions 201 is 30mm, and the pressed green blank is placed on the hemispherical protrusions 201 in the box body 1, eliminating the need to spread alumina powder at the bottom of the sintering material box. Compared with embodiment 2, this embodiment replaces the cylindrical protrusions 203 with hemispherical protrusions 201 with a spacing of 30mm, resulting in a smaller contact area with the green blank without causing excessive local stress and cracks, but the spacing difference is large, and some blanks may experience dimensional deformation.

[0035] Example 4, as Figure 2This invention provides a sintering box for reducing cracks in one-time molding of sintered NdFeB iron boron iron. The box includes a box body 1 with multiple protrusions 2 arranged in an array at the bottom. Each protrusion 2 includes hemispherical protrusions 201, with a spacing of 10mm between adjacent hemispherical protrusions 201. The pressed green blank is placed on the hemispherical protrusions 201 in the box body 1, eliminating the need to spread alumina powder at the bottom of the sintering box. Compared to Embodiment 3, this embodiment replaces the 30mm-spaced hemispherical protrusions 201 with 10mm-spaced hemispherical protrusions 201, thus avoiding the problem of deformation at the bottom of the blank and further reducing the crack rate. In this embodiment 4, the diameter of the hemispherical protrusion 201 is 4mm. A cover is movably disposed on the box body 1. The cover is rotatably disposed on the box body 1. The box body 1 can be opened or closed by flipping the cover. The cover can also be slidably disposed on the box body 1. The box body 1 can be opened or closed by sliding the cover. The movable cooperation and connection methods of the box body 1 and the cover are conventional technical means in the art and will not be described in detail here. In this solution, by setting the hemispherical protrusion 201 at the bottom of the box body 1, the contact area between the pressed green blank and the bottom surface of the box body 1 can be greatly reduced when it is directly placed into the box body 1. Therefore, the generation of cracks in the one-time molding blank can be greatly reduced, and the product dimensional consistency can be improved. At the same time, it replaces the spreading of alumina powder and reduces production costs.

[0036] Example 5, as Figure 4 and Figure 5 This utility model provides a sintering material box for reducing cracks in one-time molding of sintered NdFeB, comprising: a box body 1, a bottom plate 7 movably placed inside the box body 1, and a plurality of protrusions 2 arranged in an array on the bottom plate 7, the protrusions 2 including any one of hemispherical protrusions 201, conical protrusions 202, and cylindrical protrusions 203.

[0037] In this embodiment, the base plate 7 enables the sintering box to be detachable. When a one-time molding production is required, the base plate 7 is installed inside the box. After use, the base plate 7 can be removed, and the sintering box can be restored to a normal box for use.

[0038] Comparative example: such as Figure 8 This comparative example uses a conventional sintering box, not the sintering box of Example 4. Alumina powder is evenly spread at the bottom of the sintering box, and the pressed green billets are placed inside. All other processes are the same as in Example 4. After sintering, the bottom of the green billets in the comparative example shows scratches and cracks of varying depths, and the overall crack rate is significantly higher than in the example. Specific data are shown in Table 1.

[0039]

[0040] Table 1: Statistics of Crack Rate in One-Step Molding of Examples and Comparative Examples

[0041] Example 6, based on Example 4, such as Figure 6 The box body 1 is provided with a loading position 101 for placing the green embryo and a limiting position 102 surrounding the loading position 101. The hemispherical protrusion 201 is disposed in the loading position 101. Multiple spherical protrusions 3 are arranged in an array in the limiting position 102. The distance between the center of the spherical protrusion 3 and the bottom wall of the box body 1 is greater than the distance between the apex of the hemispherical protrusion 201 and the bottom wall of the box body 1.

[0042] In this solution, by setting the loading position 101, after the green embryo is placed in the loading position 101, the spherical protrusion 3 can be set around the green embryo to limit the side wall of the green embryo, thereby ensuring the stability of the green embryo during the movement of the box 1, thus avoiding the problem of poor stability of the green embryo caused by the reduction of contact friction.

[0043] The bottom wall of the box body 1 is provided with a plurality of hemispherical grooves 103 and through holes 104 communicating with the hemispherical grooves 103. A spherical protrusion 3 is placed in the hemispherical groove 103. The spherical protrusion 3 is placed in the hemispherical groove 103 to form a hemispherical protrusion 201 at the bottom of the box body 1. A sliding rod 4 is slidably connected to the through hole 104 and fixedly connected to the spherical protrusion 3. Sliding the sliding rod 4 can adjust the height of the spherical protrusion 3.

[0044] In this scheme, based on the shape and size of the green embryo, after placing the green embryo on the hemispherical protrusion 201 inside the box 1, the slide rod 4 surrounding the green embryo is slid, and the corresponding spherical protrusion 3 is moved upward by the slide rod 4 to form a limiting position 102 surrounding the green embryo. The area formed by the limiting position 102 is the loading position 101. This scheme enables the stable placement of green embryos of different sizes and shapes.

[0045] like Figure 7 The box body 1 is provided with a threaded hole 105 that is coaxially arranged and connected with a plurality of through holes 104. The threaded hole 105 is provided through the bottom of the box body 1. A threaded rod 5 that is rotatably connected to the slide rod 4 is threaded in the threaded hole 105. The outer diameter of the threaded rod 5 is larger than the diameter of the slide rod 4.

[0046] In this scheme, rotating the threaded rod 5 can drive the slide rod 4 to slide along the through hole 104, so as to ensure the stability of the spherical protrusion 3 after it moves to the preset position.

[0047] The threaded rod 5 extends from the end away from the spherical protrusion 3 and is fixedly connected to the bottom of the box body 1 with a knob 6. The diameter of the knob 6 is larger than the diameter of the threaded rod 5 so as to facilitate the rotation of the threaded rod 5. When the knob 6 contacts the bottom of the box body 1, it limits the upward movement height of the threaded rod 5.

[0048] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although the utility model has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of this utility model.

Claims

1. A sintering material box for reducing cracks in one-time molding of sintered NdFeB, comprising a box body, characterized in that: The bottom of the box is provided with multiple protrusions.

2. The sintering material box for reducing cracks in one-time molding of sintered NdFeB as described in claim 1, characterized in that: The protrusions include hemispherical protrusions.

3. The sintering material box for reducing cracks in one-time molding of sintered NdFeB as described in claim 1, characterized in that: A base plate is movably disposed inside the box, and the protrusion is fixedly disposed on the base plate.

4. The sintering material box for reducing cracks in one-time molding of sintered NdFeB as described in claim 2, characterized in that: The box body is provided with a loading position for placing the green embryo and a limiting position arranged around the loading position. The hemispherical protrusion is arranged in the loading position, and multiple spherical protrusions are arranged in an array in the limiting position. The distance between the center of the spherical protrusion and the bottom wall of the box body is greater than the distance between the apex of the hemispherical protrusion and the bottom wall of the box body.

5. The sintering material box for reducing cracks in one-time molding of sintered NdFeB as described in claim 4, characterized in that: The bottom wall of the box is provided with a plurality of hemispherical grooves that cooperate with the spherical protrusions and through holes that communicate with the hemispherical grooves. The spherical protrusions are placed in the hemispherical grooves to form hemispherical protrusions at the bottom of the box. A sliding rod that is fixedly connected to the spherical protrusions is slidably connected in the through holes. Sliding the sliding rod can adjust the height of the spherical protrusions.

6. The sintering material box for reducing cracks in one-time molding of sintered NdFeB as described in claim 5, characterized in that: The box body is provided with a plurality of threaded holes that are coaxially arranged and connected with the through hole, and a threaded rod that is rotatably connected to the slide rod is threaded in the threaded hole.

7. The sintering material box for reducing one-time forming cracks in sintered NdFeB as described in claim 6, characterized in that: The threaded hole is provided through the bottom of the box.

8. The sintering material box for reducing cracks in one-time molding of sintered NdFeB as described in claim 7, characterized in that: The outer diameter of the threaded rod is larger than the diameter of the slide rod.

9. The sintering material box for reducing cracks in one-time molding of sintered NdFeB according to claim 8, characterized in that: The circular spherical protrusion of the threaded rod extends out of the bottom of the box and is fixedly connected to a knob.

10. The sintering material box for reducing cracks in one-time molding of sintered NdFeB according to claim 9, characterized in that: The diameter of the knob is larger than the diameter of the threaded rod.

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