Production Method for Molded Coil

• US 20090250836A1
• Filed: 04/03/2009
• Published: 10/08/2009
• Est. Priority Date: 04/04/2008
• Status: Abandoned Application

• Current Assignee: TOKO Incorporated (Murata Manufacturing Co Limited)
• Original Assignee: TOKO Incorporated (Murata Manufacturing Co Limited)
• Inventors: FUKUI, Yoshizumi
• Application Number:
  US12/418,347
• Publication Number:
  US 20090250836A1
• Time in Patent Office: Days
• US Class Current: 264/272.150
• CPC Class Codes: B29C 2043/3618 plurality of counteracting elements
• CPC Class Codes: B29C 43/18 incorporating preformed parts or layers, e.g. compression moulding around inserts or for coating articles B29C43/206 takes precedence
• CPC Class Codes: B29C 43/36 Moulds for making articles of definite length, i.e. discrete articles
• CPC Class Codes: B29C 45/02 Transfer moulding, i.e. transferring the required volume of moulding material by a plunger from a "shot" cavity into a mould cavity
• CPC Class Codes: B29C 45/14073 using means being retractable during injection
• CPC Class Codes: B29K 2303/06 Metal powders, metal carbides or the like
• CPC Class Codes: B29K 2995/0008 Magnetic or paramagnetic
• CPC Class Codes: B29L 2031/3061 Number plates
• CPC Class Codes: B29L 2031/711 Coils
• CPC Class Codes: H01F 2017/046 helical coil made of flat wire, e.g. with smaller extension of wire cross section in the direction of the longitudinal axis
• CPC Class Codes: H01F 2017/048 with encapsulating core, e.g. made of resin and magnetic powder
• CPC Class Codes: H01F 27/027 specially adapted for combination of signal type inductors or transformers with electronic circuits, e.g. mounting on printed circuit boards
• CPC Class Codes: H01F 41/005 Impregnating or encapsulating insulating of windings H01F41/12
• CPC Class Codes: H01F 41/127 Encapsulating or impregnating encapsulating coil and core H01F41/005

Abstract

Disclosed is a method oft by using a plastic molding process, encapsulating an air-core coil with a moldable magnetic resin material prepared by kneading a mixture of a magnetic powder and a resin. The method comprises the steps of (a) preparing a molding die assembly which includes a plurality of dies adapted to define a cavity therewithin, and a positioning pin adapted to be movable in a vertical or horizontal direction within the cavity, (b) arranging the air-core coil at a given position within the cavity by the positioning pin, (c) charging the moldable magnetic resin material into the cavity and moving the positioning pin to a given retracted position in a course of the charging.

Claims

1. A method of producing, by using a plastic molding process, a molded coil having an air-core coil encapsulated with a moldable magnetic resin material prepared by kneading a magnetic powder and a resin, the method comprising the steps of:

preparing a molding die assembly including a plurality of dies adapted to define a cavity therewithin, a positioning pin and a support pin, each of the positioning pin and the support pin being adapted to be movable in a vertical direction within the cavity;

arranging the air-core coil within the cavity in such a manner that it is fixed relative to the cavity in a horizontal direction by the positioning pin, and held in midair by the support pin; and

charging the moldable magnetic resin material into the cavity and moving the positioning pin and the support pin to given positions thereof in a course of the charging.

2. The method as defined in claim 1, wherein the moldable magnetic resin material contains the magnetic powder in an amount of 60 volume % or more.

3. The method as defined in claim 1, wherein the air-core coil has a shape selected from the group consisting of a semicircular shape, a sector shape, an oval shape, an elliptical shape, a generally polygonal shape, and any combination thereof.

4. The method as defined in claim 1, wherein the plastic molding process is one selected from the group consisting of a compression molding process, a transfer molding process and an injection molding process.

5. The method as defined in claim 1, further comprising, during the step of charging the moldable magnetic resin material into the cavity, the steps of:

charging the moldable magnetic resin material into a part other than the part of the positioning pin and the support pin, followed by moving the positioning pin to the given position thereof;

charging the moldable magnetic resin material into a part of the positioning pin in an initial position thereof; and

moving the support pin to the given position thereof.

6. The method as defined in claim 5, further comprising, during the step of charging the moldable magnetic resin material into the cavity, the steps of:

pressurizing the charged moldable magnetic resin material at a pressure less than the immediately prior pressure, or placing the charged moldable magnetic resin material in a non-pressurized state;

moving the support pin to the given position thereof; and

subsequent to moving the support pin, re-pressurizing the charged moldable magnetic resin material.

7. The method as defined in claim 5, wherein the moldable magnetic resin material contains the magnetic powder in an amount of 60 volume % or more.

8. The method as defined in claim 5, wherein the air-core coil has a shape selected from the group consisting of a semicircular shape, a sector shape, an oval shape, an elliptical shape, a generally polygonal shape, and any combination thereof.

9. The method as defined in claim 5, wherein the plastic molding process is one selected from the group consisting of a compression molding process, a transfer molding process and an injection molding process.

10. A method of producing, by using a plastic molding process, a molded coil having an air-core coil encapsulated with a moldable magnetic resin material having a magnetic powder dispersed thereover, the method comprising the steps of:

attaching an external electrode to the air-core coil;

preparing a molding die assembly including a plurality of dies adapted to define a cavity therewithin, and a positioning pin adapted to be movable in a vertical direction within the cavity;

arranging the air-core coil within the cavity in such a manner that it is fixed relative to the cavity in a horizontal direction by the positioning pin, and held in midair by the external electrode; and

charging the moldable magnetic resin material into the cavity and moving the positioning pin to a given position thereof in a course of the charging.

11. The method as defined in claim 10, wherein the moldable magnetic resin material contains the magnetic powder in an amount of 60 volume % or more.

12. The method as defined in claim 10, wherein the air-core coil has a shape selected from the group consisting of a semicircular shape, a sector shape, an oval shape, an elliptical shape, a generally polygonal shape, and any combination thereof.

13. The method as defined in claim 10, wherein the plastic molding process is one selected from the group consisting of a compression molding process, a transfer molding process and an injection molding process.

14. A method of producing, by using a plastic molding process, a molded coil having an air-core coil encapsulated with a moldable magnetic resin material prepared by kneading a mixture of a magnetic powder and a resin, the method comprising the steps of:

preparing a molding die assembly including a plurality of dies, a cavity defined by the dies, and a positioning pin adapted to be movable in a horizontal direction within the cavity;

arranging the air-core coil at a given position within the cavity by use of the positioning pin; and

charging the moldable magnetic resin material into the cavity and moving the positioning pin to a given position thereof in a course of the charging.

15. The method as defined in claim 14, further comprising, during the step of charging the moldable magnetic resin material into the cavity, the step of charging the moldable magnetic resin material into the cavity in a vertical direction.

16. The method as defined in claim 14, wherein the moldable magnetic resin material contains the magnetic powder in an amount of 60 volume % or more.

17. The method as defined in claim 14, wherein the air-core coil has a shape selected from the group consisting of a semicircular shape, a sector shape, an oval shape, an elliptical shape, a generally polygonal shape, and any combination thereof.

18. The method as defined in claim 14, wherein the plastic molding process is one selected from the group consisting of a compression molding process, a transfer molding process and an injection molding process.

19. The method as defined in claim 14, wherein the molding die assembly further includes a plurality of support pins each adapted to be movable in a horizontal or vertical direction within the cavity, the method further comprising the steps of:

arranging the air-core coil at the given position within the cavity by use of the support pins in cooperation with the positioning pin; and

moving each of the support pins to a given retracted position thereof in the course of the charging.

20. The method as defined in claim 19, further comprising, during the step of charging the moldable magnetic resin material into the cavity, the steps of:

charging the moldable magnetic resin material into a part other than the part of the positioning pin and the support pin, followed by moving the positioning pin to the given position thereof;

charging the moldable magnetic resin material into a part of the positioning pin in an initial position thereof; and

moving the support pin to the given position thereof.

21. The method as defined in claim 19, further comprising, during the step of charging the moldable magnetic resin material into the cavity, the steps of:

pressurizing the charged moldable magnetic resin material at a pressure less than the immediately prior pressure, or placing the charged moldable magnetic resin material in a non-pressurized state;

moving the support pin to the given position thereof; and

subsequent to moving the support pin, re-pressurizing the charged moldable magnetic resin material.

22. The method as defined in claim 19, wherein the moldable magnetic resin material contains the magnetic powder in an amount of 60 volume % or more.

23. The method as defined in claim 19, wherein the air-core coil has a shape selected from the group consisting of a semicircular shape, a sector shape, an oval shape, an elliptical shape, a generally polygonal shape, and any combination thereof.

24. The method as defined in claim 19, wherein the plastic molding process is one selected from the group consisting of a compression molding process, a transfer molding process and an injection molding process.