Manufacturing method of magnetic core

Abstract

The present invention provides a method for manufacturing magnetic cores that eliminates the need for insulating coating on magnetic powder and shortens the manufacturing process. [Solution] The method for manufacturing the magnetic core 1 according to this embodiment includes a kneading step of kneading magnetic powder, such as iron powder 2, with a thermosetting resin 3 to form a compound 6; a placement step of placing a lower mold 8 corresponding to the shape of the magnetic core 1 on the inner circumference of a heating yoke 7 which is formed in an annular shape and whose inner circumference can be heated; a filling step of filling the lower mold 8 with the compound 6; a molding step of placing an upper mold 10 on top of the filled compound 6 and engaging it with the lower mold 8 to form the compound 6; and a heating step of heating the formed compound 6 with the heating yoke 7, wherein the molding step and the heating step are carried out in parallel.

Description

Technical Field

[0001] Embodiments of the present invention relate to a method for manufacturing a magnetic core.

Background Art

[0002] In recent years, as the awareness of circular economy has increased, improving the material utilization rate during manufacturing has become a key point. For example, in fields such as motors and transformers, in order to increase the material utilization rate, there has been an increasing demand to switch from magnetic cores manufactured by pressing conventional electromagnetic steel sheets to powder-compressed magnetic cores manufactured by compression molding iron powder as described in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the powder-compressed magnetic core uses iron powder that has been pre-coated with an insulating coating on the surface, the manufacturing process becomes longer.

[0005] Therefore, a method for manufacturing a magnetic core that does not require an insulating coating on the magnetic powder and can shorten the manufacturing process is provided.

Means for Solving the Problems

[0006] The method for manufacturing a magnetic core according to this embodiment includes a kneading step of kneading magnetic powder and thermosetting resin to form a compound, a placement step of placing a lower mold corresponding to the shape of the magnetic core on the inner side of a heating yoke which is formed in an annular shape and whose inner side can be heated, a filling step of filling the lower mold with the compound, a molding step of placing an upper mold on the compound filled in the lower mold to form the compound, and a heating step of heating the formed magnetic core with the heating yoke, wherein the molding step and the heating step are carried out in parallel. [Brief explanation of the drawing]

[0007] [Figure 1] A diagram showing the main steps in the manufacturing method of a magnetic core according to an embodiment. [Figure 2] A schematic diagram showing an example of the equipment configuration for manufacturing magnetic cores. [Modes for carrying out the invention]

[0008] The embodiments will now be described with reference to the drawings. As shown in Figures 1 and 2, in the method for manufacturing the magnetic core 1 according to this embodiment, first, a magnetic powder of a soft magnetic material, such as iron powder 2, and a thermosetting resin 3 are put into a kneading device 5 having a stirring member 4, as indicated by arrows F1 and F2, to form a kneaded product 6 (S1). As a result, the thermosetting resin 3 is arranged around the iron powder 2, insulating the iron powders 2 from each other.

[0009] Next, the lower mold frame 8 is placed on the inner circumference side of the heating yoke 7. The heating yoke 7 has a heating coil 7a inside, which is connected to the power supply unit 9. The heating yoke 7 is heated on its inner circumference by energizing the heating coil 7a. The lower mold frame 8 has a cylindrical wall portion 8a that forms the outer shape of the magnetic core 1 and a structural portion 8b that forms the hollow portion 1a of the magnetic core 1. These wall portion 8a and structural portion 8b are connected and integrated at the bottom (not shown) of the lower mold frame 8.

[0010] Next, as indicated by arrow F3, the mixture 6 is filled into the lower mold 8 (S3), the upper mold 10 is placed on top of the filled mixture 6, and the mixture 6 is pressurized and molded through the upper mold 10 by the pressurizing device 11 (S4). The upper mold 10 comprises a cylindrical body portion 10a, a hole portion 10b formed in the body portion 10a into which the structural portion 8b of the lower mold 8 is inserted, and a flange portion 10c provided at the upper end of the body portion 10a.

[0011] In other words, the upper mold 10 is formed in a shape that interlocks with the lower mold 8. Therefore, by interlocking the upper mold 10 with the lower mold 8 and placing it on top of the mixture 6, a space for forming the magnetic core 1 is created between it and the lower mold 8, and the height of the mixture 6, i.e., the height of the magnetic core 1, is determined. Note that the shapes of the magnetic core 1, the lower mold 8, and the upper mold 10 are examples and are not limited thereto.

[0012] Then, when the compound 6 is pressure-molded, the compound 6 is simultaneously heated by the heating yoke 7 (S5). In other words, in this embodiment, the magnetic core 1 is sequentially heated and molded by repeatedly performing in parallel the molding process (S4) for molding the compound 6 and the heating process (S5) for heating the molded compound 6 to cure the thermosetting resin 3.

[0013] Subsequently, pressurization and heating are continued until a predetermined heating time for curing the thermosetting resin 3 has elapsed (S6:NO). Once the heating time has elapsed (S6:YES), pressurization and heating are stopped (S7), and the magnetic core 1 is removed from the lower mold 8 (S8), thus completing the manufacturing process for the magnetic core 1. Post-processing such as deburring and surface polishing may be performed on the removed magnetic core 1 as needed.

[0014] According to the embodiments described above, the following effects can be obtained. The method for manufacturing the magnetic core 1 according to this embodiment includes a kneading step of kneading magnetic powder, such as iron powder 2, with a thermosetting resin 3 to form a compound 6; a placement step of placing a lower mold 8 corresponding to the shape of the magnetic core 1 on the inner circumference of a heating yoke 7 which is formed in an annular shape and whose inner circumference can be heated; a filling step of filling the lower mold 8 with the compound 6; a molding step of placing an upper mold 10 on top of the filled compound 6 and engaging it with the lower mold 8 to form the compound 6; and a heating step of heating the formed compound 6 with the heating yoke 7, wherein the molding step and the heating step are carried out in parallel.

[0015] As a result, the thermosetting resin 3 enables insulation of the magnetic powder, eliminating the need for a pre-insulating coating process for the magnetic powder. Since the compound 6 is not used in areas other than the magnetic core 1, the consumption of unnecessary materials can be suppressed. Furthermore, because the thermosetting resin 3 hardens when heated during molding, the shape of the magnetic core 1 is maintained even after molding, eliminating the need for drying and curing processes, and significantly shortening the manufacturing lead time compared to conventional methods. Therefore, insulating coating of the magnetic powder is unnecessary, and the manufacturing process can be shortened.

[0016] Furthermore, in this embodiment, the molding process involves pressurizing the mixture 6 using the upper mold 10. In other words, the molding of the mixture 6 and the effect of the thermosetting resin 3 are carried out in parallel, and the magnetic core 1 is sequentially heated and molded. This allows the magnetic core 1 to be precisely defined in height and increases the density of iron powder within the magnetic core 1.

[0017] In the embodiment, a configuration in which the compound 6 is molded while being pressurized is illustrated, but without actively pressurizing using the pressurizing device 11, the height of the magnetic core 1 can be defined by placing the upper mold 10 on top of the compound 6 and fixing it in a predetermined position.

[0018] Although not shown in the diagram, the molding and heating can also be performed while applying vibration, or while molding and heating are performed in a vacuum degassing device. These configurations can increase the density of iron powder within the magnetic core 1.

[0019] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0020] In the drawing, 1 represents the magnetic core, 2 represents iron powder, 3 represents thermosetting resin, 6 represents the compound, 7 represents the heating yoke, 8 represents the lower mold, and 10 represents the upper mold.

Claims

1. A mixing process in which magnetic powder and thermosetting resin are kneaded together to form a compound, A placement step involves arranging a lower mold frame corresponding to the shape of the magnetic core on the inner circumference side of a heating yoke that is formed in an annular shape and capable of heating its inner circumference, A filling step of filling the lower mold with the kneaded material, A molding process in which an upper mold is placed on the filled mixture and interlocked with the lower mold to form the mixture, The heating step includes heating the molded magnetic core with the heating yoke, A method for manufacturing a magnetic core, wherein the molding step and the heating step are carried out in parallel.

2. The method for manufacturing a magnetic core according to claim 1, wherein in the molding step, the kneaded material is molded under pressure using the upper mold.

Images