Method for controlling directionality when manufacturing injection-molded magnets using flat magnetic flakes

Abstract

The present invention provides a method for manufacturing magnets by an injection molding process, comprising: (a) a step of providing a first mold, wherein an injection gate (111) is formed at a side portion of the first mold; (b) a step of injecting an injection material into the first mold at a first injection speed in the lateral direction through the injection gate (111) of the first mold; (c) a step of providing a second mold on the first injection-molded product (100) produced in step (b), wherein injection gates (211, 212, 213) are formed at the top of the second mold; and (d) a step of injecting an injection material downward into the second mold at a second injection speed through the injection gates (211, 212, 213) of the second mold.

Description

Directional control method when manufacturing injection-molded magnetic materials using flat magnetic flakes

[0001] The present invention relates to a magnetic material manufacturing technology, specifically a method for minimizing the magnetic neutral region of an injection-molded magnetic material when manufacturing an injection-molded magnetic material using magnetic flakes.

[0002]

[0003] Although discussions regarding wireless charging have long been ongoing as an effort to overcome the inconvenience of conventional wired charging, the initial wireless charging methods failed to gain traction due to their extremely low efficiency. However, as the number of electrical devices increased and the usage environments for electronic products expanded, improvements in charging methods were required to ensure seamless operation. Consequently, wireless charging was proactively introduced in environments requiring waterproofing, such as for kettles and electric toothbrushes, and has since developed and become popularized, driven by advancements in smartphones.

[0004] Wireless charging is achieved through a process in which a transmitter sends electrical energy in the form of radio waves and a receiver converts it back into electrical energy. In this process, the transmitter and receiver consist of a magnetic material and a coil surrounding it. In other words, wireless charging requires a magnetic material that matches the shape of the desired product.

[0005] Since it is difficult to industrially process natural magnets into desired shapes, magnetic flakes are generally manufactured using an injection molding method. However, when manufactured in this way, there is a problem in that the flakes do not align due to interactions between them, resulting in an inability to achieve industrially suitable permeability.

[0006]

[0007] Examine the relevant patent publications.

[0008] Korean Registered Patent Publication No. 10-1755607 relates to a magnetic field shielding material for a wireless power transmission device and a method for manufacturing the same, specifically a method for producing a composite material by hot-press molding soft magnetic metal powder. However, the problem persisted as there was no improvement regarding the arrangement of the metal powders.

[0009] Japanese Patent Publication No. 2005-237096 relates to a ring-shaped sintered magnet and a method for manufacturing the same, and relates to a molded body with a double cylindrical structure composed of two types of powders having different permeabilities and a method for manufacturing the same. The invention proposes double injection to improve the permeability of the molded body, but there is a problem that it is unsuitable for application to obtain a magnetic injection molded body in the shape of a thin flat plate.

[0010]

[0011] (Patent Document 1) Korean Registered Patent Publication No. 10-1755607 (July 3, 2017)

[0012] (Patent Document 2) Japanese Registered Patent Publication No. 2005-237096 (September 2, 2005)

[0013]

[0014]

[0015] The present invention was devised to improve the manufacturing efficiency of injection-molded magnetic materials and to solve the problems of conventional technology, in which it is difficult to achieve high permeability in a specific direction and difficult to secure a magnetic path due to the arrangement of planar magnetic flakes in random directions.

[0016] In addition, it was devised to solve the problem of reduced design freedom in the production of conventional magnetic injection molded products by improving the manufacturing method of magnetic injection molded products.

[0017]

[0018] One embodiment of the present invention for solving the above-mentioned problems is,

[0019] (a) a step of providing a first mold, wherein the first mold has an injection gate (111) formed on its side; (b) a step of introducing an injection product laterally into the first mold at a first injection speed through the injection gate (111) of the first mold; (c) a step of providing a second mold on the first injection product (100) produced in step (b), wherein the second mold has an injection gate (211, 212, 213) formed on its upper side; and (d) a step of introducing an injection product downwardly into the second mold at a second injection speed through the injection gate (211, 212, 213) of the second mold; the present invention provides a method for manufacturing a magnetic material, comprising: (a) a step of providing a first mold, wherein the first mold has an injection gate (211, 212, 213) formed on its upper side; and (d) a step of introducing an injection product downwardly into the second mold at a second injection speed through the injection gate (211, 212, 213) of the second mold.

[0020] In addition, in another embodiment of the present invention, the injection molding gate (111) of the first mold may be formed as a single number.

[0021] In addition, in another embodiment of the present invention, the second injection speed may be faster than the first injection speed.

[0022] Additionally, in another embodiment of the present invention, the injection molded product (200) produced through step (d) comprises an annular outer frame (221); and an annular inner frame (222) connected to the outer frame (221) via a bridge (229), and the length along the lateral direction of the inner frame (222) may be shorter than the length along the height direction.

[0023] Additionally, in another embodiment of the present invention, the injection molded product (200) produced through step (d) may further include a plurality of gates (211, 212, 213) formed above the bridge (229).

[0024] Additionally, in another embodiment of the present invention, a first cooling step between step (b) and step (c); and a second cooling step after step (d) are further included, and the time for performing the second cooling step may be shorter than the time for performing the first cooling step.

[0025] In addition, one embodiment of the present invention provides a magnetic material manufactured through a method for manufacturing a magnetic material.

[0026]

[0027] By the method for manufacturing a magnetic material according to the present invention, planar magnetic flakes can be oriented in the height direction, thereby securing a magnetic path in the height direction and realizing high permeability in the height direction.

[0028] In addition, when using a material with the same inductance, it is possible to produce an injection-molded product having a higher inductance than a magnetic material produced using a conventional method.

[0029]

[0030] FIG. 1 is a perspective view of a first injection-molded product according to the present invention.

[0031] FIG. 2 is a perspective view of a second injection-molded product according to the present invention.

[0032] FIG. 3 is a cross-sectional view of a second injection-molded product according to the present invention.

[0033] FIG. 4a is a perspective view of a first injection molded product and a second injection molded product according to the present invention.

[0034] FIG. 4b is a perspective view of an injection-molded magnetic body according to the present invention.

[0035] FIG. 5 shows the flow and arrangement direction of magnetic flakes in the first injection molding step according to the present invention.

[0036] FIG. 6 shows the flow and arrangement direction of magnetic flakes on the wall surface of the injection molded product during the first injection molded product manufacturing step according to the present invention.

[0037] FIG. 7 shows the flow and arrangement direction of magnetic flakes in the second injection molding step according to the present invention.

[0038] FIG. 8 shows a cross-section of an injection-molded magnetic body according to the present invention.

[0039] FIG. 9 shows a cross-section of an injection-molded magnetic body according to the present invention divided into a first injection-molded product and a second injection-molded product.

[0040] FIG. 10 is experimental data comparing the inductance of an injection-molded magnetic material in a double injection method according to the present invention and a conventional single injection method.

[0041]

[0042] Hereinafter, a method for manufacturing a magnetic material according to the present invention will be described in detail with reference to the drawings. In this invention, the components constituting the present invention may be used as a single unit or separately as needed. Additionally, depending on the form of use, some components may be omitted. Various modifications are also possible regarding the form of the present invention and the number of components.

[0043]

[0044] A method for manufacturing a magnetic material according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

[0045]

[0046] A method for manufacturing a magnetic body according to an embodiment of the present invention may include: (a) a step of providing a first mold, wherein the first mold has an injection gate (111) formed on its side; (b) a step of introducing an injection product laterally into the first mold at a first injection speed through the injection gate (111) of the first mold; (c) a step of providing a second mold on the first injection product (100) produced in step (b), wherein the second mold has an injection gate (211, 212, 213) formed on its upper side; and (d) a step of introducing an injection product downwardly into the second mold at a second injection speed through the injection gate (211, 212, 213) of the second mold.

[0047]

[0048] First, in order to manufacture the mold provided in steps (a) and (c), the shape of the injection molded product to be obtained by the magnetic material manufacturing method is set, and a flat portion (120) (corresponding to the first injection molded product described later) and a remaining portion (220) (corresponding to the second injection molded product described later) are separated from the shape of the injection molded product. Subsequently, the mold corresponding to the flat portion is designated as the first mold, and the mold corresponding to the remaining portion is designated as the second mold.

[0049] In the first mold, a single gate (111) is formed on the side of the first mold. Accordingly, an injection molded product can be fed in the lateral direction (xy direction) through the gate (111).

[0050] In the second mold, a plurality of downward-facing gates (211, 212, 213) are formed on the upper part of the second mold. Accordingly, an injection molded product can be introduced in the height direction (z direction) through the plurality of gates (211, 212, 213). At this time, the second injection molded product (200) to be obtained with the second mold can be divided into an annular outer frame (221) and an inner frame (222) due to the structure of the injection molded product. If the outer frame (221) and the inner frame (222) are not connected to each other and it is necessary to form a bridge (229) connecting them for injection molding, a configuration corresponding to the bridge (229) can be added to the mold, and at the same time, the plurality of gates (211, 212, 213) can be manufactured to be connected to the bridge (229).

[0051] Additionally, regarding the inner frame (222) of the second mold, the shape of the inner frame (222) can be selected such that the length (d1) along the lateral direction of the inner frame (222) is shorter than the length (d2) along the height direction.

[0052]

[0053] (b) As a step, a first injection molded product (100) is produced using the first mold. The first injection molded product (100) is formed by introducing the injection molded product into the gate (111) of the first mold formed on the side of the mold at a first injection speed. At this time, the first injection speed can be selected from the injection speed used in conventional injection molding using magnetic flakes, and can be changed as needed.

[0054] A first cooling step may be performed on the first injection molded product (100) produced through the first mold, in which cooling is performed at a first cooling rate. At this time, the first cooling rate may also be selected from the cooling rate used in conventional injection molding using magnetic flakes, and may be changed as needed.

[0055]

[0056] Afterward, as step (c), the first injection molded product is combined with the second mold, and as step (d), the second injection molded product (200) is produced. The second injection molded product (200) is formed by introducing the injection molded product into the gates (211, 212, 213) of the second mold, which are formed downwardly on the upper part of the mold, at a second injection speed. At this time, the second injection speed may be faster than the first injection speed.

[0057] A second cooling step may be performed on the second injection molded product (200) produced through the second mold, in which cooling is performed at a second cooling rate. At this time, the second cooling rate may be faster than the first cooling rate.

[0058]

[0059] Finally, a magnetic material can be obtained by removing the gates (111, 211, 212, 213) of the injection molded product.

[0060]

[0061] With reference to FIGS. 5 to 9, the characteristics of a magnetic material manufactured according to the method for manufacturing a magnetic material according to the present invention will be explained.

[0062] FIG. 5 illustrates the process of producing a first injection molded product (100) through injection molding using a first mold. The first injection molded product (100) is produced at a first injection speed, which is lower than the injection speed of the second injection molded product (200). Accordingly, as magnetic flakes are introduced relatively slowly through the first mold with a flat shape and the gate (111) formed on its side, the magnetic flakes are arranged horizontally and smoothly.

[0063] FIG. 6 is a cross-sectional view showing the flow of magnetic flakes when they come into contact with the mold wall during the process of producing a first injection molded product (100) through injection molding using a first mold. Since the magnetic flakes are supplied through the side of the mold, they come into contact with the wall and rise upward, and as the direction of the magnetic flakes is aligned through the interaction between the magnetic flakes, a neutral region is formed as a result. The above process can be achieved by providing sufficient time for the magnetic flakes to rearrange as the first injection molded product (100) is cooled by a first cooling rate that is slower than the second cooling rate.

[0064] FIG. 7 illustrates the process of producing a second injection molded product (200) through injection molding using a second mold. The second injection molded product (200) is produced at a second injection speed, which is faster than the first injection molded product (100). In addition, the internal frame (222) of the second injection molded product (200) is designed so that its length in the height direction is longer than its length in the horizontal direction. Therefore, as magnetic flakes are supplied at a high speed from the top to the bottom of the mold, the magnetic flakes can be filled and arranged in the height direction. In this state, by cooling the second injection molded product (200) at a second cooling speed faster than the first cooling speed, the time for the magnetic flakes to rearrange through mutual interaction is minimized, and the state of being arranged in the vertical (height, z-axis) direction is maintained. Furthermore, since the second mold has multiple gates, the flow characteristics of the magnetic flakes are enhanced.

[0065] FIG. 8 shows a cross-section of the second injection molded product (200) produced by injection molding through the second mold. As magnetic flakes are rapidly fed from the upper to the lower part of the second mold at the second injection speed, they are arranged in the height direction, and as a result, the neutral area is minimized compared to the first injection molded product (100).

[0066] FIG. 9 shows a cross-section of the first injection molded product (100) and the second injection molded product (200) combined. In the first injection molded product (100), magnetic flakes are injected through the side of the mold at a first injection speed and cooled at a first cooling speed, providing sufficient time for the magnetic flakes to rearrange and thus forming a magnetic neutral region. However, in the second injection molded product (200), magnetic flakes are injected through the upper part of the mold at a second injection speed and cooled at a second cooling speed, so it can be seen that the formation of a magnetic neutral region is minimized.

[0067]

[0068] Figure 10 is experimental data comparing the weight, density, and inductance when magnetic materials are manufactured using a conventional single injection method and a double injection method according to the present invention, respectively, in the manufacture of magnetic materials using magnetic flakes.

[0069] When identical injection-molded products were manufactured using the same magnetic flakes but with different injection molding methods, it was confirmed that there was a significant improvement in inductance despite no major differences in weight and density. Therefore, the effect of improving the magnetic properties of the magnetic material through the fabrication of the magnetic material using magnetic flakes, as intended in this invention, was confirmed.

[0070]

[0071] (Explanation of symbols)

[0072] 10: Injection magnetic material

[0073] 100: First injection molded part

[0074] 110: Runner

[0075] 111: Gate

[0076] 120: First magnetic body

[0077] 200: Second injection molded part

[0078] 210: Runner

[0079] 211: Gate

[0080] 212: Gate

[0081] 213: Gate

[0082] 220: Second magnetic body

[0083] 221: External frame

[0084] 222: Internal Frame

[0085] 229: Bridge

Claims

1. A method for manufacturing a magnetic material by injection molding, (a) A first mold providing step, wherein the first mold has an injection molding gate (111) formed on its side; (b) a step in which an injection product is injected laterally into the first mold at a first injection speed through the injection product gate (111) of the first mold; (c) a step of providing a second mold on the first injection molded product (100) produced in step (b) above, wherein the second mold has an injection molded product gate (211, 212, 213) formed on its upper surface; and (d) a step of introducing an injection molded product downwardly into the second mold at a second injection speed through the injection molded product gates (211, 212, 213) of the second mold; comprising, Method for manufacturing a magnetic material.

2. In Paragraph 1, The injection molding gate (111) of the first mold is formed as a single number, Method for manufacturing a magnetic material.

3. In Paragraph 1, The second injection speed is faster than the first injection speed. Method for manufacturing a magnetic material.

4. In Paragraph 1, The injection molded product (200) produced through the above step (d) is, annular outer frame (221); and It includes an annular inner frame (222) connected to the outer frame (221) and a bridge (229); The length along the lateral direction of the inner frame (222) is shorter than the length along the height direction. Method for manufacturing a magnetic material.

5. In Paragraph 4, The injection molded product (200) produced through the above step (d) is, A plurality of gates (211, 212, 213) formed above the bridge (229); further comprising Method for manufacturing a magnetic material.

6. In Paragraph 1, A first cooling step between the above (b) step and the above (c) step; and A second cooling step after the above (d) step; further comprising, The execution time of the second cooling step is shorter than the execution time of the first cooling step. Method for manufacturing a magnetic material.

7. A magnetic material manufactured through a method for manufacturing a magnetic material according to any one of claims 1 to 6.

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