WO2003102977A1

WO2003102977A1 - Compound core for reactor and method for fabricating the same

Info

Publication number: WO2003102977A1
Application number: PCT/KR2002/001050
Authority: WO
Inventors: Young Kwon; Byeong Hwa Chung
Original assignee: Lg Electronics Inc.
Priority date: 2002-06-03
Filing date: 2002-06-03
Publication date: 2003-12-11
Also published as: AU2002309308A1

Abstract

A compound core for a reactor and a method for fabricating the same are disclosed. The compound core for a reactor includes a compound produced by mixing a magnetic powder, which is treated with heat, with a high polymer resin at a constant ratio, wherein the compound core is extruded and injected in various forms.

Description

COMPOUND CORE FOR REACTOR AND

METHOD FOR FABRICATING THE SAME

TECHNICAL FIELD

The present invention relates to a compound core for a reactor and a method for fabricating the same.

BACKGROUND ART Generally, a reactor is to rectify overcurrent and includes one core provided with one winding. The core used for the reactor has been conventionally fabricated using silicon steel sheets or amorphous alloy.

The core based on silicon steel sheets, as shown in FIG. 1, has been fabricated by several silicon steel sheet layers fabricated by rolling. The core based on amorphous alloy has been fabricated by stacking several thin layers, which are made from alloy melt by quenching, to form a toroidal core and forming an air gap. The core based on silicon steel sheets or amorphous alloy has been generally used due to its relatively low cost and high investment rate. However, it has a problem in that great loss occurs at a high frequency band. Accordingly, it has been difficult for such a core to be used in the product which requires the high frequency.

Furthermore, some problems have occurred due to a heavy weight of the core when a reactor is arranged on a circuit board.

To solve such problems, there has been recently provided a core fabricated by coating metallic powder. The core, as shown in FIG. IB, is fabricated by respectively coating metal particles, such as Fe-Ni alloy, with high polymer and sintering them at high pressure. In this case, loss at a high frequency band can be reduced by adding a great quantity of Ni to the core. However, some problems still arise in that the fabricating cost increases due to the expensive cost of Ni and difficulties exist in the fabricating process such as coating metal particles and sintering them at high pressure.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention is directed to a compound core for a reactor and a method for fabricating the same that substantially obviates one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a compound core for a reactor and a method for fabricating the same that facilitates the fabricating process and has improved characteristics by using a compound material capable of carrying out both extrusion molding and injection molding.

Another object of the present invention is to provide a compound core for a reactor and a method for fabricating the same that can reduce weight and size by using a material having low specific gravity and excellent characteristics .

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a compound core for a reactor includes a compound produced by mixing a magnetic powder, which is treated with heat, with a high polymer resin at a constant ratio, wherein the compound core is extruded and injected in various forms. The magnetic powder is selected from any one of an oxide-based magnetic fine powder such as a magnetic iron oxide, a cobalt-containing magnetic iron oxide, chromium- containing magnetic iron oxide, and chrome oxide, a magnetic fine powder such as iron-based fine powder, nickel-based fine powder, cobalt-based fine powder, and silicon-based fine powder, a synthetic ferrite fine powder, and a magnetite fine powder. The high polymer resin is selected from any one of polyethylene, polypropylene, PVC, phenol resin, nylon, silicon resin, rubber, polyester, polystyrene, and acrylonitrile-butadiene-styrene (ABS) .

In another aspect of the present invention, a compound core for a reactor includes a compound produced by mixing a magnetic powder, which is treated with heat at a temperature between 900°C and 1500°C, with a high polymer resin at 85~95wt%, wherein the compound core is extruded and injected in various forms.

The compound core is injected by adding stearic acid to the compound so as to softness of the work process. In other aspect of the present invention, a method for fabricating a compound core for a reactor includes a) preparing a magnetic powder of a certain size and a high polymer resin, b) treating the magnetic powder with heat, c) mixing the magnetic powder treated with heat with the high polymer resin, and d) molding the compound produced by mixing the magnetic powder with the high polymer resin in a core form for the reactor.

The magnetic powder is treated with heat at a temperature between 900°C and 1500°C, and has a size within the range of lμm ~ lOOum. Also, the magnetic powder has a content of 85~95wt% when it is mixed with the high polymer resin.

The step d) includes dl) extruding the compound produced by mixing the magnetic powder with the high polymer resin in a predetermined bar form, d2) cutting the extruded- bar shaped compound into pieces of a certain size, and d3) injecting the piece shaped compound in the core form for the reactor.

According to the preferred embodiment of the present invention, the compound is produced by mixing the magnetic powder treated with heat with the high polymer resin at a constant ratio, the process can easily be carried out and mass production can be realized, thereby freely fabricating a reactor having various characteristics. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIGS. 1A and IB illustrate a method for fabricating a compound core for a reactor according to the related art;

FIG. 2 illustrates a method for fabricating a compound core for a reactor according to the present invention; and

FIG. 3 is a flow chart illustrating the fabricating process steps of a compound core for a reactor according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

In the present invention, it is intended to fabricate a core for a reactor suitable for mass production by enabling both extrusion molding and injection molding and using a compound produced by mixing a magnetic powder, which is treated with heat to enhance magnetic characteristic, with a high polymer resin at a constant ratio. FIG. 2 illustrates a method -for fabricating a compound core for a reactor according to the present invention, and FIG. 3 is a flow chart illustrating the fabricating process steps of a compound core for a reactor according to the present invention. As shown in FIGS. 2 and 3, a magnetic powder of a certain size and a high polymer resin are prepared (Sll) .

A hardening magnetic powder as well as a soft magnetic powder may be used as the magnetic powder. Preferably, an oxide-based magnetic fine powder, a metallic-based magnetic fine powder, a synthetic ferrite fine' powder, or a magnetite fine powder may be used as the magnetic powder. The oxide-based magnetic fine powder includes a magnetic iron oxide, a cobalt-containing magnetic iron oxide, a chromium-containing magnetic iron oxide, or chrome oxide. The metallic-based magnetic fine powder includes an iron-based fine powder, a nickel-based fine powder, a cobalt-based fine powder, or a silicon- based fine powder.

Especially, the metallic-based fine powder may lose magnetism as its surface is likely to be oxidized. Accordingly, it is preferable that an oxidized membrane is in advance formed on the surface of the metal so as not to oxidize the surface.

The magnetic force of the oxide-based magnetic body is within the range of 100-1000 Oe. The magnetic force of the metallic-based magnetic body is within the range of 500-2000 Oe.

Preferably, the magnetic powder has a size within the range of lμm ~ lOOμm. More preferably, all the magnetic powders have an equal size.

Meanwhile, the high polymer resin may be selected from any one of polyethylene, polypropylene, PVC, phenol resin, nylon, silicon resin, rubber, polyester, polystyrene, and acrylonitrile-butadiene-styrene (ABS) .

The magnetic powder is treated with heat at a temperature between 900°C and 1500°C (S12) , so that its characteristics may be prevented from being deteriorated by external stress. The magnetic powder treated with heat is mixed with the high polymer resin at a constant ratio to produce a compound (S13) .

. At this time, the magnetic powder in- the compound has a content of 85~95wt%. If the content of the high polymer resin is too smaller than that of the magnetic powder, the product is not molded in the process of injection. On the other hand, if the content of the high polymer resin is too greater than that of the magnetic powder, the magnetic characteristic is remarkably reduced. Accordingly, it is necessary that the magnetic powder is appropriately mixed with the high polymer resin.

The mixed ratio of the magnetic powder and the high polymer resin may depend on types of each material. Next, the compound produced by mixing the magnetic powder with the high polymer resin is extruded in a bar form having a predetermined length, and the extruded bar shaped compound is cut into pieces of a certain size (S14) . The piece shaped compound is molded by injection to fabricate a core for a reactor (S15) . At this time, to provide softness, stearic acid of about 1% that acts as a lubricant is added to the compound. Also, since bubbles may occur if moisture exists in the compound, the compound is molded after drying for four hours at a temperature of about 100°C.

INDUSTRIAL APPLICABILITY

As described above, the compound core for a reactor and the method for fabricating the same have the following advantages .

First, since mass production of the same product can be realized, the fabricating cost can be reduced.

Second, the product having various shapes can be obtained by simply varying the molding type.

Third, since the extrusion and injection molding methods are used, the process steps can be reduced.

Fourth, the magnetic powder having excellent characteristic can be mixed in various methods, the product having excellent magnetic characteristic can be fabricated.

Finally, since the lightweight and small sized product can be fabricated, it is applicable to various fields such as a circuit board. While the present invention has been described and illustrated herein with reference to the preferred embodiment thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from -the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents.

Claims

CLAIMED IS :

1. A compound core for a reactor comprising a compound produced by mixing a magnetic powder, which is treated with heat, with a high polymer resin at a constant ratio, wherein the compound core is extruded and injected in various forms.

2. The compound core of claim 1, wherein the magnetic powder is selected from any one of an oxide-based magnetic fine powder such as a magnetic iron oxide, a cobalt- containing magnetic iron oxide, chromium-containing magnetic iron oxide, and chrome oxide, a magnetic fine powder such as iron-based fine powder, nickel-based fine powder, cobalt-based fine powder, and silicon-based fine powder, a synthetic ferrite fine powder, and a magnetite fine powder.

3. The compound core of claim 1, wherein the magnetic powder is treated with heat at a temperature between 900°C and 1500°C.

4. The compound core of claim 1, wherein the magnetic powder has a size within the range of lμm ~ lOOμm.

5. The compound core of claim 1, wherein the magnetic powder has a content of 85~95wt%.

β. The compound core of claim 1, wherein the high polymer resin is selected from any one of polyethylene, polypropylene, PVC, phenol resin, nylon, silicon resin, rubber, polyester, polystyrene, and acrylonitrile- butadiene-styrene (ABS) .

7. The compound core of claim 1, wherein the compound core is injected by adding a lubricant to the compound.

8. The compound core of claim 7, wherein the lubricant is stearic acid.

9. A compound core for a reactor comprising a compound produced by mixing a magnetic powder, which is treated with heat at a temperature between 900°C and 1500°C, with a high polymer resin at 85~95wt%, wherein the compound core is extruded and injected in various forms.

10. The compound core of claim 9, wherein the magnetic powder is selected from any one of an oxide-based magnetic fine powder such as a magnetic iron oxide, a cobalt- containing magnetic iron oxide, chromium-containing magnetic iron oxide, and chrome oxide, a magnetic fine powder such as iron-based fine powder, nickel-based fine powder, cobalt-based fine powder, and silicon-based fine powder, a synthetic ferrite fine powder, and a magnetite fine powder.

11. The compound core of claim 9, wherein the high polymer resin is selected from any one of polyethylene, polypropylene, PVC, phenol resin, nylon, silicon resin, rubber, polyester, polystyrene, and ABS.

12. The compound core of claim 9, wherein the compound core is injected by adding stearic acid to the compound.

13. A method for fabricating a compound core for a reactor comprising: a) preparing a magnetic powder of a certain size and a high polymer resin; b) treating the magnetic powder with heat; c) mixing the magnetic powder treated with heat with the high polymer resin; and d) molding the compound produced by mixing the magnetic powder with the high polymer resin in a core form for the reactor.

14. The method of claim 13, wherein the magnetic powder is selected from any one of an oxide-based magnetic fine powder such as a magnetic iron oxide, a cobalt-containing magnetic iron oxide, chromium-containing magnetic iron oxide, and chrome oxide, a magnetic fine powder such as iron-based fine powder, nickel-based fine powder, cobalt- based fine powder, and silicon-based fine powder, a synthetic ferrite fine powder, and a magnetite fine powder.

15. The method of claim 13, wherein the high polymer resin is selected from any ^■ one of polyethylene, polypropylene, PVC, phenol resin, nylon, silicon resin, rubber, polyester, polystyrene, and ABS.

16. The method of claim 13, wherein the magnetic powder is treated with heat at a temperature between 900°C and 1500°C.

17. The method of claim 13, wherein the magnetic powder has a size within the range of Iμm ~ lOOμm.

18. The method of claim 13, wherein the magnetic powder has a content of 85~95wt% when it is mixed with the high polymer resin.

19. The method of claim 13, wherein the step d) includes: dl) extruding the compound produced by mixing the magnetic powder with the high polymer resin in a predetermined bar form; d2) cutting the extruded bar shaped compound into pieces of a certain size; and d3) injecting the piece shaped compound in the core form for the reactor.

20. The method of claim 19, wherein the step d3) includes adding stearic acid to the compound.