Dust core and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-9396873-B2
Application number	US-201013132892-A
Country	US
Kind code	B2
Filing date	Apr 28, 2010
Priority date	Dec 25, 2009
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

Provided is a dust core and a method for manufacturing a thereof, having an effect that the soft magnetic powder is prevented from sintering and bonding together upon heating, the hysteresis loss can be effectively reduced, and the DC B-H characteristics is excellent. In a first mixing process, a soft magnetic powder composed mainly of iron and an inorganic insulating powder of 0.4 wt %-1.5 wt % are mixed by a mixer. A mixture obtained in the first mixing process is heated in a non-oxidizing atmosphere at 1000° C. or more and below a sintering temperature of the soft magnetic powder. In a binder addition process, a silane coupling agent of 0.1-0.5 wt % is added. A binder, e.g. a silicone resin of 0.5-2.0 wt % is added to the soft magnetic alloy powder to which the inorganic insulating powder is attached by the silane coupling agent, and the soft magnetic alloy powders are bonded to each other so as to be granulated. Then, the mixture is added with a lubricant resin and compression-molded so as to form a green compact. In an annealing process, the mold is annealed in a non-oxidizing atmosphere.

First claim

The invention claimed is:

1. A method for manufacturing a dust core comprising:
a first mixing process for mixing a soft magnetic powder and an inorganic insulating powder;
a heating process for heating a mixture of the soft magnetic powder and the inorganic insulating powder;
a binder addition process for adding a silane coupling agent and a silicone resin as a binder resin to the mixture of the soft magnetic powder and the inorganic insulating powder heated in the heating process;
a second mixing process for mixing a lubricant resin with a mixture of the soft magnetic powder, the inorganic insulating powder, the silane coupling agent and the silicone resin;
a molding process for compression-molding a mixture of the soft magnetic powder, the inorganic insulating powder, the binder resin, and the lubricant resin so as to form a mold; and
an annealing process for annealing the mold, wherein an added amount of the inorganic insulating powder is 0.4-0.8 wt % with respect to the soft magnetic powder,
the heating process is performed in a non-oxidizing atmosphere at 1000° C. or more and also below a sintering temperature of the soft magnetic powder.

2. The method for manufacturing a dust core according to claim 1 , wherein the soft magnetic powder has an average particle size of 5-30 μm, and contains 0-6.5 wt % silicon.

3. The method for manufacturing a dust core according to claim 2 , wherein the inorganic insulating powder is Al 2 O 3 powder or MgO powder having a melting point of 1500° C. or more, and has an average particle size of 7-500 nm.

4. The method for manufacturing a dust core according to claim 1 , wherein the inorganic insulating powder is Al 2 O 3 powder or MgO powder having a melting point of 1500° C. or more, and has an average particle size of 7-500 nm.

5. The method for manufacturing a dust core according to claim 1 , wherein the soft magnetic powder is prepared by a gas atomization method, a water/gas atomization method, or a water atomization method.

6. The method for manufacturing a dust core according to claim 5 , wherein the soft magnetic powder is prepared by the water atomization method and formed by a planarization treatment.

7. The method for manufacturing a dust core according to claim 1 , wherein in the binder addition process, the silane coupling agent is added firstly and the silicone resin is added secondly to the mixture of the soft magnetic powder and the inorganic insulating powder heated in the heating process.

8. The method for manufacturing a dust core according to claim 1 , wherein an added amount of the silane coupling agent is in a range of 0.1-0.5 wt % with respect to the soft magnetic powder and an added amount of the silicone resin is in a range of 0.5-2.0 wt % with respect to the soft magnetic powder.

9. The method for manufacturing a dust core according to claim 1 , wherein a mixing amount of the lubricant resin is 0.2-0.8 wt % with respect to the soft magnetic powder.

10. The method for manufacturing a dust core according to claim 1 , wherein an aspect ratio of the soft magnetic powder is between 1.0-1.5.

Assignees

• Oshima Yasuo
• Handa Susumu
• Akaiwa Kota
• Tamura Seisakusho Kk

Inventors

• Oshima Yasuo
• Handa Susumu
• Akaiwa Kota

Classifications

• B22F1/10

  Metallic powder containing lubricating or binding agents; Metallic powder containing organic material · CPC title

• B22F9/082

  atomising using a fluid (using centrifugal force B22F9/10) · CPC title

• B22F2998/10

  Processes characterised by the sequence of their steps · CPC title

• H01F41/0246 Primary

  Manufacturing of magnetic circuits by moulding or by pressing powder (magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36) · CPC title

• H01F1/33

  mixtures of metallic and non-metallic particles; metallic particles having oxide skin · CPC title