Molding and wet pressing die for permanent magnetic ferrite

Abstract

The invention provides a permanent magnetic ferrite forming wet pressing mold, belongs to the technical field of permanent magnet production, and aims to solve the technical problems that the magnetic powder directionality is poor in the permanent magnet magnetic shoe forming process, and the magnetic flux density distribution of a finished product magnet does not reach the standard. Comprising an upper die, the bottom of the upper die is provided with a plurality of first embedding blocks, the bottom surface of each first embedding block is matched with the outer arc side of a permanent magnet in shape, and the bottom surface of each first embedding block is provided with a water absorption hole which is connected to the outside of the upper die; the cavity piece is provided with a plurality of vertically-through working cavities, the positions of the working cavities correspond to those of the first embedded blocks, each working cavity comprises a pouring area at the upper end and a sliding area at the lower end, the peripheral side walls of the pouring areas are matched with the peripheral side walls of the permanent magnets, and the sliding areas are further provided with runners communicating with the exterior of the cavity piece; the die head is slidably arranged in the sliding area, and the shape of the top of the die head is matched with the inner arc side of the permanent magnet. The method has the technical effects of improving the permanent magnet production qualification rate and reducing the defects of finished magnetic shoes.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet production technology, specifically to a wet pressing mold for forming permanent magnet ferrite. Background Technology

[0002] Permanent magnets, as an indispensable functional material in modern industry, are widely used in high-precision fields such as motors, sensors, and medical devices. Their core performance indicator—magnetic flux distribution—directly determines the energy efficiency and stability of the final product. Current technologies are limited by mold structure and process parameter control, making it difficult to guarantee the directional alignment accuracy of magnetic powder within the mold cavity, leading to problems such as localized magnetic performance defects in the finished magnets.

[0003] In the wet pressing process of permanent magnet tiles, the orientation of magnetic powder is a key factor affecting the magnetic flux density distribution. In traditional mold structures, the cavity design and magnetic powder filling are prone to generating eddies due to uneven flow resistance, leading to disordered orientation. At the same time, improper fit between the mold head and the cavity will further aggravate the local segregation of magnetic powder distribution, ultimately causing the magnetic flux fluctuation of the finished magnet to exceed the standard range. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a wet pressing mold for permanent magnet ferrite molding, which solves the technical problem of poor magnetic powder orientation during the molding process of permanent magnet tiles, resulting in substandard magnetic flux density distribution in the finished magnet.

[0005] The technical solution adopted in this invention is: a wet pressing mold for forming permanent magnet ferrite, comprising: The upper mold has multiple first insert blocks at its bottom. The bottom surface of the first insert block matches the outer arc side of the permanent magnet. The bottom surface of the first insert block has water absorption holes that are connected to the outside of the upper mold. The cavity component has multiple vertically penetrating working cavities, the positions of which correspond to the first insert block. Each working cavity includes an upper casting area and a lower sliding area. The four sides of the casting area match the outer side walls of the permanent magnet. The sliding area is also provided with a flow channel that connects to the outside of the cavity component. And a mold head, which is slidably disposed in the sliding area, with the top shape of the mold head matching the inner arc side of the permanent magnet.

[0006] Optionally, the water-absorbing holes are arranged vertically, with the lower end penetrating the first inlay block and the upper end penetrating the upper mold; in each corresponding area of ​​the casting area, a set of water-absorbing holes is arranged on each side along the width direction of the casting area, and multiple water-absorbing holes are arranged in each set along the length direction of the casting area.

[0007] Optionally, both the upper mold body and the first insert block are made of magnetically conductive material.

[0008] Optionally, the first insert block is arc-shaped, with its convex arc back fitting into the upper mold and its concave inner arc surface facing the casting area. The inner arc surface is also provided with a plane around it that fits against the top surface of the cavity component.

[0009] Optionally, on the cavity component, a second inlay block is provided on both sides of each of the casting areas in the width direction. The second inlay block is surrounded by the material of the cavity component. The top surface of the second inlay block is flush with the top surface of the cavity component. The second inlay block is made of magnetic material, while the cavity component is made of non-magnetic material.

[0010] Optionally, on the cavity component, the working cavities are arranged in rows and columns, with the width direction of a single working cavity being a row and the length direction being a column. The working cavities in the same column are connected by the same flow channel, which runs through the sliding area of ​​the working cavities in the same column.

[0011] Optionally, the mold head includes a head end forming body and a tail rod connected to the tail end of the forming body. The side of the forming body is sealed and slidably fitted with the sliding area. The top surface of the forming body matches the shape of the inner arc side of the permanent magnet, and the top surface of the forming body is made of a non-magnetic material.

[0012] Optionally, the middle part of the molded body is arc-shaped, and there are flat shoulders on both sides in the width direction, with the arc shape and flat shoulders smoothly transitioning.

[0013] Optionally, along the top view of the mold, the projected cross section of the first insert block covers the projected cross section of the working cavity, and the dimension of the second insert block along the length of the casting area is larger than that of the casting area.

[0014] As can be seen from the above technical solution, the beneficial technical effects of the present invention are as follows: This wet-pressing mold for permanent magnet ferrite molding significantly improves the molding quality of magnetic tiles through structural innovation. The precise matching design of the upper mold insert block and the cavity casting area effectively constrains the magnetic powder filling path, and the water absorption holes remove excess water in real time, preventing magnetic powder agglomeration. The mold head structure with connected sliding zones can dynamically adjust the pressing pressure distribution, resulting in more uniform directional arrangement of the magnetic powder, thus solving the technical problem of substandard magnetic flux density distribution. In practical applications, this mold can also reduce defects such as surface cracks and localized weak magnetism, improving the production qualification rate and significantly reducing production costs. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0016] Figure 1 This is a cross-sectional view of the upper mold, cavity components, and mold head assembly.

[0017] Figure 2 for Figure 8 Schematic diagram of section AA.

[0018] Figure 3 for Figure 8 Schematic diagram of the BB section.

[0019] Figure 4 This is a schematic diagram of the mold head.

[0020] Figure 5 for Figure 4 A magnified view of a portion of point A in the middle.

[0021] Figure 6 This is a top view of the upper mold.

[0022] Figure 7 This is a side view of the upper mold.

[0023] Figure 8 This is a top view of the cavity component.

[0024] Figure 9 This is a top view of the assembly of the upper mold, cavity parts, and mold head.

[0025] Figure 10 This is a schematic diagram of the cross-section of a permanent magnet.

[0026] Reference numerals: Upper mold 1, First insert block 11, Water absorption hole 12, Cavity component 2, Working cavity 21, Casting area 211, Sliding area 212, Flow channel 22, Second insert block 23, Mold head 3, Molded body 31, Flat shoulder 311, Tail rod 32, Permanent magnet 4. Detailed Implementation

[0027] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0028] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0029] A wet pressing mold for molding permanent magnet 4 ferrite, please refer to the appendix. Figure 1 One possible implementation method is as follows: The upper mold 1 has multiple first insert blocks 11 at its bottom. The bottom surface shape of the first insert blocks 11 matches the outer arc side of the permanent magnet 4. The bottom surface of the first insert blocks 11 is provided with water absorption holes 12, which are connected to the outside of the upper mold 1. Both the upper mold 1 and the first insert blocks 11 are made of magnetically conductive materials. In a preferred embodiment, the upper mold 1 and the first insert blocks 11 are made of 45 steel and 50Mn steel, respectively. Cavity component 2, which is provided with multiple vertically penetrating working cavities 21, the positions of the working cavities 21 correspond to the first inlay block 11, the working cavity 21 includes an upper casting area 211 and a lower sliding area 212, the four sides of the casting area 211 match the outer side of the permanent magnet 4, and the sliding area 212 is also provided with a flow channel 22 that connects to the outside of the cavity component 2; And the mold head 3, which is slidably set in the sliding area 212, and the top shape of the mold head 3 matches the inner arc side of the permanent magnet 4.

[0030] This wet pressing mold is used for tile-shaped magnets. The width refers to the direction of the arc-shaped cross section of the magnet tile, and the length refers to the axial direction of the arc-shaped magnet tile.

[0031] The main production process of the magnet is as follows: First, raw materials are prepared by mixing the metal powders required for the permanent magnet in a certain proportion, followed by ball milling. Mechanical force is used to refine the powder particles and ensure uniform mixing, thereby improving the activity of the magnetic powder. Next, the milled magnetic powder is mixed with binders, lubricants, and other additives to form a wet material, which is then injected into a wet pressing mold as described in the aforementioned technical solution. After pressing, the mold is removed to obtain a magnetic tile blank. This blank then undergoes sintering, heat treatment, and other processes to enhance its magnetic properties. Finally, surface processing and inspection are performed.

[0032] The wet pressing mold in this scheme mainly involves the molding stage, and the specific steps are as follows: First, assemble the upper mold 1, cavity component 2, and mold head 3 according to the above scheme, ensuring that each working cavity 21 in the cavity component 2 is equipped with a mold head 3. In the initial state, the mold head 3 is located at the rear of the working cavity 21 to prevent blockage of the flow channel 22. Next, wet material (a mixture of magnetic powder, binder, lubricant, etc.) is injected into the working cavity 21 through the flow channel 22. Subsequently, the mold head 3 slides to block the flow channel 22 and continues to slide and compress the working cavity 21 until only the space of the casting area 211 remains in the working cavity 21. During this process, the wet material is extruded and shaped, and the water in the wet material is discharged through the water suction hole 12. It should be noted that the water suction hole 12 should be specially designed, or a filter cloth or other protective measures should be set at the water suction hole 12 to prevent the wet material powder from being squeezed out of the water suction hole 12 under the extrusion pressure of the mold head 3.

[0033] The improved technical effect in the above embodiments is mainly due to the following reasons: The materials and structure of the upper mold and the first insert block play a role in the filling of magnetic powder and the removal of moisture. Since the upper mold 1 and the first insert block 11 are made of 45 steel and 50Mn steel respectively, both are magnetically conductive materials. During mold operation, when an external magnetic field is applied, the magnetically conductive upper mold and the first insert block can guide the magnetic field lines to distribute evenly. Magnetic powder is paramagnetic and will arrange itself into chains along the direction of the magnetic field lines under the influence of the magnetic field. This orderly chain arrangement is an important basis for the subsequent directional molding of the magnetic powder, providing a prerequisite for obtaining uniform magnetic properties. The bottom shape of the first insert block 11 precisely matches the outer arc side of the permanent magnet 4, and the four sides of the casting area 211 also match the outer peripheral sidewalls of the permanent magnet 4, providing a strict constraint on the filling of magnetic powder.

[0034] In a more specific embodiment, the working cavities 21 on the cavity component 2 are arranged in rows and columns. The width direction of a single working cavity 21 is a row, and the length direction is a column. The working cavities 21 in the same column are connected by the same flow channel 22, which runs through the sliding area 212 of the working cavities 21 in the same column. When wet material is injected into the working cavity 21, the magnetic powder can only flow along a specific path adapted to the shape of the permanent magnet, avoiding disordered diffusion and turbulence of the magnetic powder during the filling process. In this way, the magnetic powder can be evenly filled into all parts of the cavity, greatly improving the uniformity and accuracy of magnetic powder filling, and laying a good foundation for subsequent pressing and molding.

[0035] The water-absorbing holes 12 on the bottom surface of the first insert block 11 connect to the outside of the upper mold 1 and play a crucial role in the magnetic powder filling and pressing process. The wet material contains a certain amount of moisture, which is a significant factor leading to magnetic powder agglomeration. After the wet material is injected into the working cavity, excess moisture can be promptly discharged outside the mold through the water-absorbing holes 12. Timely removal of moisture effectively prevents the magnetic powder from sticking together and agglomerating due to moisture, ensuring the dispersion and flowability of the magnetic powder particles. This allows the magnetic powder to better align as required during subsequent magnetic field action and pressing, improving the molding quality.

[0036] The die head structure plays a crucial role in the distribution of pressing pressure and the orientation of magnetic powder. The sliding area 212 has a flow channel 22 connecting to the outside of the cavity 2. The die head 3 is slidably positioned within the sliding area 212, a design that allows the die head 3 to dynamically adjust the pressing pressure distribution. During the wet material injection stage, the die head 3 is initially positioned towards the rear to prevent blockage of the flow channel 22, ensuring the wet material can be smoothly injected into the working cavity 21 and maintain its fluidity. After the wet material injection is complete, the die head 3 slides to block the flow channel 22 and continues to slide and extrude the working cavity 21. During extrusion, the die head 3 can flexibly adjust the pressing pressure according to the filling status of the wet material and the pressing requirements. This dynamic adjustment ensures that the wet material receives uniform and appropriate pressure throughout the working cavity, avoiding the problem of uneven magnetic powder arrangement due to discontinuous pressure, and improving the uniformity and consistency of magnetic powder pressing. The top shape of the die head 3 matches the inner arc side of the permanent magnet 4, playing a vital role in guiding the magnetic powder formation during the pressing process. When the die head 3 applies pressure to the wet material, its top shape guides the magnetic powder to form the inner arc shape of the permanent magnet 4. Simultaneously, combined with the magnetic guiding effect of the upper die and the first insert block, and the water-absorbing holes' ability to expel moisture, the magnetic powder, under the combined influence of the magnetic field, pressure, and moisture control, can achieve a more uniform directional arrangement. This uniform directional arrangement makes the magnetic domain structure inside the magnetic tile more ordered, thus solving the technical problem of insufficient magnetic flux density distribution and improving the magnetic properties of the magnetic tile.

[0037] In one possible implementation, see Appendix Figure 1 The water-absorbing holes 12 are vertically arranged, with their lower ends penetrating the first insert block 11 and their upper ends penetrating the upper mold 1. In each corresponding area of ​​the casting zone 211, a set of water-absorbing holes 12 is arranged on each side along the width of the casting zone 211, and multiple water-absorbing holes 12 are arranged along the length of the casting zone 211 in each set. This layout allows the water-absorbing holes to cover all parts of the casting zone, ensuring that moisture is drained promptly from both the edges and the center of the wet material, greatly improving drainage efficiency and ensuring appropriate moisture content before pressing. Furthermore, multiple water-absorbing holes 12 effectively prevent localized water accumulation. Uneven drainage can lead to residual moisture in certain areas, affecting the flowability and directional alignment of the magnetic powder. A proper arrangement ensures uniform moisture drainage throughout the casting zone, creating a relatively consistent environment for the magnetic powder during pressing, which improves molding quality. Moisture can cause magnetic powder particles to agglomerate, affecting uniform filling and directional alignment. The 12 water-absorbing holes allow for rapid drainage, maintaining the dispersion of magnetic powder particles and ensuring a more uniform distribution when filling the casting area. This avoids uneven filling due to agglomeration and creates favorable conditions for subsequent directional arrangement.

[0038] In one possible implementation, the first insert 11 is arc-shaped, with its convex arc back fitting into the upper mold 1 and its concave inner arc surface facing the casting area 211. The inner arc surface also has a plane around its perimeter that fits against the top surface of the cavity component 2. This fitting method ensures a tight connection between the two, effectively withstanding the enormous pressure generated during mold operation, reducing loosening or deformation caused by pressure, ensuring the long-term precision and reliability of the mold, reducing the risk of mold damage, and extending its service life. The concave inner arc surface facing the casting area 211 conforms to the arc shape requirements of permanent magnets, precisely constraining the magnetic powder filling path. During injection and pressing, the magnetic powder fills evenly along the shape of the inner arc surface, avoiding uneven or disordered filling, improving the accuracy and uniformity of magnetic powder filling, and laying the foundation for obtaining high-quality magnetic tiles. The plane around the inner arc surface that fits against the top surface of the cavity component 2 enhances sealing. During pressing, it can effectively prevent wet material from leaking from the connection between the first insert block 11 and the cavity part 2, ensuring stable pressure in the working cavity, so that the magnetic powder can be oriented and formed under suitable pressure environment, further improving the quality and production efficiency of the magnetic tile.

[0039] In one possible implementation, see Appendix Figure 8 On the cavity component 2, a second inlay block 23 is provided on both sides of the width direction of each casting area 211. The second inlay block 23 is surrounded by the material of the cavity component 2, and the top surface of the second inlay block 23 is flush with the top surface of the cavity component 2. The second inlay block 23 is made of magnetically conductive material, while the cavity component 2 is made of non-magnetically conductive material. Non-magnetically conductive material does not affect the spatial distribution of the magnetic field. Only magnetically conductive material will produce a magnetic binding effect, binding part of the magnetic field lines inside the material, causing a redistribution of the spatial magnetic field. That is, the magnetic field lines are dense in some places (magnetic field increases) and sparse in some places (magnetic field decreases). From the perspective of magnetic powder filling and arrangement, since the second inlay block 23 is made of magnetically conductive material, under the action of an external magnetic field, it can guide the magnetic field lines to form a specific distribution on both sides of the width direction of the casting area 211. Magnetic powder is paramagnetic and will arrange itself in an orderly manner along the direction of magnetic field lines. This ensures that when filling the casting area 211, the magnetic powder is also neatly arranged in the desired direction, avoiding disordered arrangement and improving the uniformity of magnetic powder filling and the accuracy of directional arrangement, thereby enhancing the magnetic properties of the magnetic tile. From a cost control perspective, the cavity component 2 uses a non-magnetic material, which reduces the manufacturing cost of the mold compared to using all magnetic materials, while not affecting the guiding effect of the second insert 23 on the arrangement of magnetic powder, achieving a balance between cost and performance.

[0040] In one possible implementation, see Appendix Figure 4The mold head 3 includes a head forming body 31 and a tail rod 32 connected to the tail of the forming body 31. The side of the forming body 31 is sealed and slidably fitted with the sliding area 212. The top surface of the forming body 31 matches the shape of the inner arc side of the permanent magnet 4, and the top surface of the forming body 31 is made of a non-magnetic material. The middle part of the forming body 31 is arc-shaped, and there are flat shoulders 311 on both sides in the width direction, with a smooth transition between the arc and the flat shoulders 311. In the top view of the mold, the projected cross section of the first insert block 11 covers the projected cross section of the working cavity 21, and the dimension of the second insert block 23 along the length direction of the casting area 211 is larger than that of the casting area 211.

[0041] The projected cross section of the first inlay block 11 covers the projected cross section of the working cavity 21, guiding more magnetic field lines to concentrate and pass through the casting area. This places the casting area in a strong magnetic field environment, providing sufficient magnetic field power for the orderly arrangement of magnetic powder, which helps the magnetic powder to arrange quickly and neatly along the direction of the magnetic field lines. The top surface of the molded body 31 is made of a non-magnetic material, which does not hinder the magnetic field lines, ensuring that the magnetic field lines can pass smoothly through the casting area, maintaining the continuity and stability of the magnetic field, allowing the magnetic powder to align under a stable magnetic field, and avoiding disordered arrangement due to interference from the material's magnetic permeability. The dimensions of the second inlay blocks 23 on both sides along the length of the casting area 211 are larger than that of the casting area 211, which can constrain and regulate the magnetic field lines on both sides. It can limit the diffusion range of the magnetic field lines, making the magnetic field lines act more concentratedly on the wet material in the casting area, further optimizing the distribution of magnetic field lines in the casting area, thereby prompting the magnetic powder in the wet material to align in a specific and more uniform way, which is beneficial to improving the magnetic properties and quality of the final finished magnetic tile.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A wet pressing mold for forming permanent magnet (4) ferrite, characterized in that, include: The upper mold (1) has multiple first insert blocks (11) at its bottom. The bottom surface shape of the first insert block (11) matches the outer arc side of the permanent magnet (4). The bottom surface of the first insert block (11) is provided with water absorption holes (12), which are connected to the outside of the upper mold (1). Cavity component (2), the cavity component (2) is provided with multiple vertically penetrating working cavities (21), the position of the working cavity (21) corresponds to the first inlay block (11), the working cavity (21) includes an upper casting area (211) and a lower sliding area (212), the four sides of the casting area (211) match the outer side of the permanent magnet (4), the sliding area (212) is also provided with a flow channel (22) connected to the outside of the cavity component (2); And a mold head (3), which is slidably disposed in the sliding area (212), and the top shape of the mold head (3) matches the inner arc side of the permanent magnet (4).

2. The wet pressing mold for forming permanent magnet (4) ferrite as described in claim 1, characterized in that: The water-absorbing holes (12) are arranged vertically, with the lower end penetrating the first inlay block (11) and the upper end penetrating the upper mold (1); in each area corresponding to the casting area (211), a set of water-absorbing holes (12) is arranged on each side along the width direction of the casting area (211), and multiple sets of water-absorbing holes (12) are arranged along the length direction of the casting area (211).

3. The wet pressing mold for forming permanent magnet (4) ferrite as described in claim 1, characterized in that: Both the upper mold body and the first insert block (11) are made of magnetically conductive material.

4. The wet pressing mold for forming ferrite in permanent magnet (4) as described in claim 1, characterized in that: The first inlay block (11) is arc-shaped, with its convex arc back fitting into the upper mold (1) and its concave inner arc surface facing the casting area (211). The inner arc surface is also provided with a plane that fits against the top surface of the cavity part (2).

5. The wet pressing mold for forming ferrite in permanent magnet (4) as described in claim 1, characterized in that: On the cavity component (2), a second inlay block (23) is provided on both sides of the width direction of each casting area (211). The second inlay block (23) is surrounded by the material of the cavity component (2). The top surface of the second inlay block (23) is flush with the top surface of the cavity component (2). The second inlay block (23) is made of magnetic material, while the cavity component (2) is made of non-magnetic material.

6. The wet pressing mold for forming permanent magnet (4) ferrite as described in claim 1, characterized in that: On the cavity component (2), the working cavities (21) are arranged in rows and columns. The width direction of a single working cavity (21) is a row, and the length direction is a column. The working cavities (21) in the same column are connected by the same flow channel (22). The flow channel (22) passes through the sliding area (212) of the working cavities (21) in the same column.

7. The wet pressing mold for permanent magnet (4) ferrite molding as described in claim 1, characterized in that: The mold head (3) includes a head end molding body (31) and a tail rod (32) connected to the tail of the molding body (31). The side of the molding body (31) is sealed and slidably fitted with the sliding area (212). The top surface of the molding body (31) matches the shape of the inner arc side of the permanent magnet (4). The top surface of the molding body (31) is made of non-magnetic material.

8. The wet pressing mold for permanent magnet (4) ferrite molding as described in claim 7, characterized in that: The middle part of the molded body (31) is arc-shaped, and there are flat shoulders (311) on both sides in the width direction. The arc shape and the flat shoulders (311) are smoothly transitioned.

9. A wet pressing mold for forming ferrite in permanent magnet (4) as described in claim 5, characterized in that: Along the top view of the mold, the projected cross section of the first insert (11) covers the projected cross section of the working cavity (21), and the dimension of the second insert (23) along the length of the casting area (211) is larger than that of the casting area (211).

10. A wet pressing mold for forming ferrite in permanent magnet (4) as described in claim 3, characterized in that: The upper mold (1) is made of 45 steel; and / or the first insert (11) is made of 50Mn steel.

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