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 molding step of extruding the compound 6 with an extrusion molding machine, and a step of heating the extruded compound 6 by passing it through the inner circumference of a heating yoke 10 which is formed in an annular shape and whose inner circumference can be heated.

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, enhancing 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 press-working 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 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 the embodiment includes a kneading step of kneading magnetic powder and a thermosetting resin to obtain a kneaded product, a molding step of extruding the kneaded product using an extrusion molding machine, and a heating step of heating the extruded kneaded product by passing it through the inner peripheral side of a heating yoke formed in a ring shape and capable of heating the inner peripheral side.

Brief Description of the Drawings

[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. [Figure 3] This diagram schematically shows a method for manufacturing individual magnetic cores by cutting a molded body. [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 compound 6 is supplied to the extrusion molding machine 7 as indicated by arrow F3 (S2). Then, the compound 6 is extruded through the cylinder 7a as indicated by arrow F4 and passed through the die 8 to form the magnetic core 1 (S3). However, since the compound 6 is extruded continuously, at this point, strictly speaking, a molded body 9 is formed in which multiple magnetic cores 1 are connected in the axial direction.

[0010] The die 8 is formed in an annular shape, as shown in the enlarged view of a portion of the region (R), and a core (not shown) for forming the hollow portion 1a is positioned inside it. The mixed material 6 is then extruded through the die 8 to form a molded body 9 whose cross-sectional shape and outer diameter match that of the magnetic core 1. Note that the cross-sectional shape of the hollow portion 1a is an example and is not limited thereto.

[0011] The molded body 9 is heated by a heating yoke 10 located downstream of the die 8, in parallel with the extrusion molding process. The heating yoke 10 has a heating coil 10a inside, which is connected to the power supply 11. The heating yoke 10 is heated on its inner circumference when the heating coil 10a is energized.

[0012] In other words, the molded body 9, which serves as the base material for the magnetic core 1, is manufactured by sequential heating molding, in which a molding process (S3) to create a predetermined shape by extrusion molding and a heating process (S4) to heat and harden the thermosetting resin 3 are carried out in parallel. These molding and heating processes are then repeated in parallel until the extrusion molding is completed (S5:NO).

[0013] The heated molded body 9 is supported, for example, by a roller stand 12 so as to be movable to the left in the figure. Once the extrusion molding is complete (S5:YES), the molded body 9 is cut to a predetermined length as shown in Figure 3 (S6). Note that the cutting of the molded body 9 may be performed at a different location, such as the transport destination, rather than on the roller stand 12.

[0014] For example, by cutting the molded body 9 at a cutting position (X), a predetermined number of magnetic cores 1A of a predetermined length can be manufactured. Furthermore, by cutting the molded body 9 at a different cutting position (Y), magnetic cores 1B of different lengths can be manufactured. Note that the cutting positions shown in Figure 3 are just examples; it is also possible to manufacture only magnetic cores 1A of the same length, or to manufacture three or more types of magnetic cores 1.

[0015] Once the molded body 9 is cut and the manufacturing of the magnetic core 1 is complete, the manufacturing process is finished. In this embodiment, the magnetic core 1 is manufactured by continuously molding and heat-curing the compound 6 by extrusion molding. Post-processing such as deburring and surface polishing can also be performed on the cut magnetic core 1 as needed.

[0016] 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 molding step of extruding the compound 6 with an extrusion molding machine, and a step of heating the extruded compound 6 by passing it through the inner circumference of a heating yoke 10 which is formed in an annular shape and whose inner circumference can be heated.

[0017] 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. Furthermore, since the compound 6 is not used in areas other than the magnetic core 1, the consumption of unnecessary materials can be suppressed. In addition, the magnetic core 1 can be continuously produced by extrusion molding. Moreover, if the cross-sectional shape differs while maintaining the same outer diameter, only the core needs to be replaced, allowing for mass production of multiple product types. Therefore, insulating coating of the magnetic powder is unnecessary, and the manufacturing process can be shortened.

[0018] Furthermore, by carrying out the molding process and the heating process in parallel, the shape of the magnetic core 1 is maintained even after molding as the thermosetting resin 3 hardens. This eliminates the need for drying and curing processes, significantly shortening the manufacturing lead time compared to conventional methods.

[0019] Furthermore, the molding process includes a cutting process in which a long molded body 9 is extruded and then cut to a predetermined size. By including this process of extruding a long molded body 9, it becomes possible to manufacture multiple base materials that will become magnetic cores 1 in a single extrusion molding process. Moreover, if the cross-sectional shape is the same but the length is different, the cutting position can be changed, thus enabling the production of multiple product types.

[0020] Although some embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0021] In the drawings, 1, 1A, and 1B denote magnetic cores, 2 denotes iron powder, 3 denotes thermosetting resin, 6 denotes a kneaded product, 7 denotes an extruder, 9 denotes a molded body, and 10 denotes a heating yoke.

Claims

1. A mixing process in which magnetic powder and thermosetting resin are kneaded together to form a compound, A molding step in which the kneaded material is extruded using an extrusion molding machine, A heating step in which the extruded kneaded material is passed through the inner circumference of a heating yoke that is formed in an annular shape and whose inner circumference can be heated, A method for manufacturing a magnetic core containing a magnetic core.

2. A method for manufacturing a magnetic core according to claim 1, wherein the molding step and the heating step are carried out in parallel.

3. In the molding process described above, a long molded body is extruded, The method for manufacturing a magnetic core according to claim 1 or 2, further comprising a cutting step of cutting the molded body to a predetermined size.

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