JP2016025222A - Method of manufacturing reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a reactor capable of manufacturing a reactor excellent in quality, without causing any damage on a coil or deformation thereof during the manufacturing process.SOLUTION: A method of manufacturing a reactor where a coil C is embedded in a resin core molded of a core material composed at least of a resin and soft magnetic powder comprises: a first step for setting the filling amount of the core material other than the resin, by multiplying the difference of volume between a first cavity 1a of a molding die 1 and the coil C, by a ratio equal to or larger than the ratio of bulk density/true specific gravity; a second step for filling the cavity 1a of a molding die 1 with the core material other than the resin by the setting amount, and disposing the coil C in the cavity 1a; and a third step for filling the cavity 1a of a molding die 1 with resin.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for manufacturing a reactor.

  More specifically, a reactor is applied as a component of a power conversion device such as an in-vehicle DC-DC converter, as a circuit component that performs voltage step-up or step-down control in the power conversion device.

  There are various types of reactors. For example, a U-shaped core and an I-shaped core are assembled in a ring shape through a gap, and a coil is formed around them. And a form in which a molded resin body is formed in the case. As a molding method of this mold resin body, a method of compression molding soft magnetic powder or the like is generally used.

  As another form of the reactor, there is a reactor in which a coil is embedded in a resin core in which a core material made of a resin and soft magnetic powder is molded.

  In this type of reactor, a core material made of resin and soft magnetic powder is used, so that a reactor having a higher degree of freedom in shape can be manufactured as compared with the compression molding method described above. A method for manufacturing a reactor by filling a core material made of a resin and soft magnetic powder into a molding die provided with a coil in this way is disclosed in Patent Document 1.

  There are thermosetting resins and thermoplastic resins in the resin that forms the core material. However, thermosetting resins have problems such as requiring a curing furnace for curing and a long curing time of about 1 hour. ing. On the other hand, the thermoplastic resin can be molded into the core material in a few minutes using an injection molding machine.

  However, when manufacturing a core material by mixing thermoplastic resin and soft magnetic powder, the thermoplastic resin and soft magnetic powder are kneaded by applying a high shear force in a high temperature atmosphere in order to melt the thermoplastic resin. However, there is a problem in that the soft magnetic powder remains strained and becomes a core material having a large hysteresis loss.

  Further, since the core material is generally filled with soft magnetic powder, the viscosity at the time of melting is high and the fluidity is poor. Therefore, it is necessary to perform injection molding at a high temperature and a high resin pressure. For this reason, there is a problem that the surface of the coil in the mold is damaged or the coil is deformed by the high resin pressure.

  As described above, since any of the thermosetting resin and the thermoplastic resin is applied to the resin forming the core material, there is a problem inherent to each, and therefore the reactor manufacturing method that can eliminate these problems. Development is desired.

JP 2012-199580 A

  The present invention has been made in view of the above-described problems, and provides a reactor manufacturing method capable of manufacturing a reactor having excellent quality without causing damage or deformation of a coil in the manufacturing process. With the goal.

  In order to achieve the above object, a method of manufacturing a reactor according to the present invention is a method of manufacturing a reactor in which a coil is embedded in a resin core formed of a core material composed of at least a resin and soft magnetic powder, The first step of setting the filling amount of the core material other than the resin by multiplying the difference between the volume of the cavity and the volume of the coil by the ratio of the bulk specific gravity / true specific gravity of the core material other than the resin, This comprises a second step of filling the mold material into the cavity of the set amount by the set amount and a coil in the cavity, and a third step of filling the cavity of the mold with resin.

  The manufacturing method of the reactor of the present invention is not a method of filling a molding die with a core material in which a resin and soft magnetic powder are kneaded. Is to be filled. Since the resin to be filled does not contain soft magnetic powder or the like, it has a low viscosity and good fluidity. Therefore, the resin can be filled at a low temperature and a low pressure. Damage and deformation are eliminated. As a result, a reactor excellent in quality can be manufactured.

  Here, “a core material composed of at least a resin and a soft magnetic powder” means that the core material other than the resin is only the soft magnetic powder, and the core material other than the resin is composed of the soft magnetic powder and the nonmagnetic powder or fiber. It is meant to include forms that are materials. In the form including non-magnetic powder or fiber material, the filling amount of the soft magnetic powder can be adjusted with these materials.

  The applied resin may be either a thermosetting resin or a thermoplastic resin. However, a thermoplastic resin that can be injection-molded and that can eliminate the need for a curing furnace and can reduce the manufacturing time is applied. Is preferred.

  When setting the filling amount of the core material other than the resin in the first step (in the case of only soft magnetic powder or in the case of a mixed material such as soft magnetic powder and nonmagnetic powder), the bulk specific gravity of the core material other than resin ( Apparent density) can be obtained by the method specified in JISZ2504. From the bulk specific gravity / true specific gravity ratio of the core material other than the resin, the closest packing ratio of the material is specified.

  The volume of the mold cavity can be specified from a design drawing or the like, and the volume of the coil can also be specified from a specification or the like.

  The filling amount of the core material other than the resin is set by multiplying the difference between the volume of the cavity of the mold and the volume of the coil by a ratio equal to or higher than the ratio of the bulk specific gravity / the true specific gravity of the core material other than the resin. As described above, the core material other than the resin is filled in the cavity at a ratio equal to or higher than the bulk specific gravity / true specific gravity ratio, so that the soft magnetic powder can be uniformly filled in the cavity.

  In the second step, the core material other than the resin may be filled after the coil is disposed in the mold, or the reverse order may be applied. Here, the “filling” of the core material other than the resin in the second step means that the core material other than the resin is accommodated in the cavity.

  Preferably, the core material other than the resin is filled so that the coil is covered with the core material other than the resin in the cavity. Here, after filling the core material other than resin in the mold and disposing the coil, if there is a gap in the mold, the core material other than resin is filled again to fill the gap. Is preferred.

  Moreover, it is preferable that the coil is positioned and fixed by a fixing means so that the coil does not move from a desired installation position in the cavity. The “fixing means” includes a fixing pin, a fixing needle, a fixing string, and the like.

  By filling only the resin in the third step, a resin having a relatively low temperature, low viscosity and good fluidity can be distributed in the cavity.

  Here, “filling” of the resin in the third step means injection by injection molding or the like.

  As can be understood from the above description, according to the method for manufacturing a reactor of the present invention, by filling only the soft magnetic powder other than the resin in the mold and applying the resin in the subsequent process, Since the resin to be filled does not contain soft magnetic powder or the like, the resin has a low viscosity and good fluidity. Therefore, the resin can be filled at a low temperature and a low pressure. This eliminates the damage and deformation of the coil during resin filling, and makes it possible to manufacture a reactor with excellent quality.

It is the flowchart explaining the manufacturing method of the reactor of this invention. It is the schematic diagram explaining the 2nd step of the manufacturing method. It is the schematic diagram explaining the 3rd step of the manufacturing method. It is a perspective view of the manufactured reactor.

  Hereinafter, an embodiment of a reactor manufacturing method of the present invention will be described with reference to the drawings.

(Embodiment of manufacturing method of reactor)
FIG. 1 is a flowchart illustrating a method for manufacturing a reactor according to the present invention, and FIGS. 2 and 3 are schematic diagrams illustrating a second step and a third step of the manufacturing method, respectively.

  The reactor to be manufactured by the manufacturing method of the present invention is a reactor in which a coil is embedded in a resin core made of resin and soft magnetic powder.

  First, as shown in FIG. 1, the filling amount of the core material other than the resin is set (first step S10). That is, the core material that is injection-molded into the cavity 1a of the mold 1 shown in FIGS. 2 and 3 is only a thermoplastic resin, and soft magnetic powder or the like is previously filled in the cavity 1a prior to the injection of the thermoplastic resin. Is done. In the first step S10, the filling amount of the core material other than the resin such as the soft magnetic powder is set.

  Here, as the soft magnetic powder, iron group metals such as Fe, Co, and Ni, alloy powders containing iron as a main component, and the like can be applied. In particular, Fe-Si alloys, Fe-Ni alloys, Fe-Al alloys, Fe-Co alloys, Fe-Cr alloys, Fe-Si-Al alloys, rare earth metals, ferrites, and the like can be applied.

  The soft magnetic powder is preferably subjected to a surface treatment such as an insulating coating in order to ensure insulation between the soft magnetic powders and reduce eddy current loss.

  In addition, when the core material other than the resin is formed of soft magnetic powder and non-magnetic powder or fiber material, this non-magnetic powder includes non-magnetic and insulating powder such as inorganic oxide such as silica and alumina, nitriding A nitride such as boron or aluminum nitride can be applied. By mixing the non-magnetic powder, the non-magnetic powder is arranged in the gap between the soft magnetic powders to provide a gap effect, and since it has high thermal conductivity, the heat dissipation of the resin core can be enhanced. . In addition, when nonmagnetic powder is mixed, the amount of soft magnetic powder can be reduced to keep magnetic permeability low.

  Moreover, the strength of the resin core can be increased by mixing fiber materials such as glass fibers and carbon fibers.

  When only soft magnetic powder is used as the core material other than resin, the bulk specific gravity of the soft magnetic powder is obtained by the method specified in JISZ2504, the ratio of bulk specific gravity / true specific gravity is specified, and the closest packing ratio is specified. .

  On the other hand, when using a mixed material such as soft magnetic powder and non-magnetic powder as the core material other than resin, after stirring these with a Henschel mixer, etc., the bulk specific gravity of the mixed powder is obtained by the method specified in JISZ2504. The ratio of specific gravity / true specific gravity is specified, and the closest packing ratio is specified.

  On the other hand, the volume of the mold cavity is specified from the design drawing, the coil volume is also specified from the specifications, etc., and the difference between the volume of the mold cavity and the volume of the coil is obtained.

  The filling amount of the core material other than the resin is set by multiplying the difference between the determined cavity volume of the mold and the volume of the coil by a predetermined ratio equal to or greater than the ratio of bulk specific gravity / true specific gravity.

For example, if the volume of the cavity is 700 cm ³ , the bulk specific gravity of the soft magnetic powder is 5 g / cm ³ , and the true specific gravity is 7 g / cm ³ , the filling amount of the soft magnetic powder is 700 × 5/7 = 500 cm ³ or more The quantity is set to, for example, 600 cm ³ and 700 cm ³ .

  Moreover, when using mixed materials, such as a soft magnetic powder and a nonmagnetic powder, the bulk specific gravity of mixed powder is applied.

  As described above, the core material other than the resin is filled in the cavity 1a at a ratio equal to or greater than the bulk specific gravity / true specific gravity ratio, so that the soft magnetic powder can be uniformly and uniformly filled in the cavity 1a. it can.

  When the filling amount of the core material other than the resin is set, next, as shown in FIG. 1, the coil is placed in the mold and the core material other than the resin is filled (second step S20).

  First, the core material F other than the resin of the set amount set in the first step S10 is filled in the cavity 1a of the mold 1.

  Next, the coil C is disposed at a predetermined position in the cavity 1a, and a plurality of fixing pins 2 are arranged between the coil C and the wall surface of the cavity 1a to position the coil C.

  The coil C is disposed so that the coil C is covered with a core material F other than resin. Here, when a gap is generated in the cavity 1a when the coil C is disposed, the core material F other than resin is filled again in the cavity 1a in order to fill the gap.

  When the coil C is disposed in the cavity 1a and the core material F other than resin is filled so as to cover the coil C, the mold 1 is filled with resin as shown in FIG. 1 (third step S30). .

  As shown in FIG. 3, the resin is injected into the cavity 1a from the filling hole 1b, thereby filling the cavity 1a with the resin (X1 direction) and spreading the entire area of the cavity 1a (X2 direction).

  Here, the resin to be filled may be either a thermosetting resin or a thermoplastic resin. However, a thermoplastic resin that can be injection-molded and that can eliminate the need for a curing furnace and can reduce manufacturing time is applied. It is preferable to do this.

  Examples of the thermoplastic resin to be applied include polyamide, polyester, polyphenylene sulfide, polyether ether ketone, polyethylene, polypropylene, methacryl, and polyimide resin.

  By waiting for the thermoplastic resin to harden and demolding, as shown in FIG. 4, a reactor R in which a coil C is embedded in a resin core M in which a core material made of resin and soft magnetic powder is molded is manufactured. Is done.

  In the third step, since only the resin not mixed with the soft magnetic powder or the like is filled in the cavity 1a, a resin having a relatively low temperature, low viscosity and good fluidity can be distributed in the cavity 1a. it can. Therefore, there is a problem when filling the cavity with a mixed material of soft magnetic powder etc. and resin, that is, the viscosity at the time of melting is high, the fluidity is bad, and it is necessary to perform injection molding at high temperature and high resin pressure. The problem that the surface of the coil in the mold is damaged or the coil is not deformed by this high resin pressure cannot occur.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Mold, 1a ... Cavity, 1b ... Filling hole, 2 ... Fixed pin (fixing means), C ... Coil, F ... Core material other than resin (soft magnetic powder, mixed material of soft magnetic powder and nonmagnetic powder) , M ... Resin core, R ... Reactor

Claims (6)

A method of manufacturing a reactor in which a coil is embedded in a resin core formed of a core material composed of at least a resin and soft magnetic powder,
A first step of setting the filling amount of the core material other than the resin by multiplying the difference between the volume of the cavity of the mold and the volume of the coil by a ratio of the bulk specific gravity / true specific gravity of the core material other than the resin;
A second step of filling the cavity of the mold with the core material other than the resin by the set amount, and disposing the coil in the cavity;
A method for manufacturing a reactor, comprising a third step of filling a cavity of a mold with a resin.   The method for manufacturing a reactor according to claim 1, wherein the core material other than the resin is only soft magnetic powder.   The reactor manufacturing method according to claim 1, wherein the core material other than the resin is a soft magnetic powder and a nonmagnetic powder or a fiber material.   The method for manufacturing a reactor according to claim 1, wherein in the second step, the core material other than the resin is filled so that the coil is covered with the core material other than the resin in the cavity.   The method for manufacturing a reactor according to any one of claims 1 to 4, wherein in the second step, the coil is positioned and fixed in the cavity by a fixing means.   The said resin is a thermoplastic resin, The manufacturing method of the reactor in any one of Claims 1-5.

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