JP2005072112A - Forming method of dust core - Google Patents
Forming method of dust core Download PDFInfo
- Publication number
- JP2005072112A JP2005072112A JP2003296993A JP2003296993A JP2005072112A JP 2005072112 A JP2005072112 A JP 2005072112A JP 2003296993 A JP2003296993 A JP 2003296993A JP 2003296993 A JP2003296993 A JP 2003296993A JP 2005072112 A JP2005072112 A JP 2005072112A
- Authority
- JP
- Japan
- Prior art keywords
- powder
- molding
- mold
- resin
- die
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Powder Metallurgy (AREA)
Abstract
Description
この発明は、トランスコア等に用いられる高周波特性に優れる圧粉磁心の成形方法に関する。 The present invention relates to a method for forming a powder magnetic core excellent in high frequency characteristics used for a transformer core or the like.
リアクトルやトランスコア等に用いられる圧粉磁心には、磁性粒子として鉄粉を用い、該鉄粉に絶縁性の樹脂を混合した混合粉を圧縮成形し、加熱処理して作られるものがある。鉄粉としては、純鉄粉の他、圧粉磁心の鉄損をより少なくするため、燐酸化合物被膜を形成して絶縁性を向上した鉄粉（例えば、ヘガネス社製の商品名Ｓｏｍａｌｏｙ５００）が市販されている。また、特開平１０−１５４６１３号公報に記載されているような燐酸化合物被膜が形成されたものが挙げられる。 Some dust cores used for reactors, transformer cores, and the like are made by using iron powder as magnetic particles, compression-molding a mixed powder obtained by mixing an insulating resin into the iron powder, and heat-treating the powder. As iron powder, in addition to pure iron powder, in order to reduce the iron loss of the powder magnetic core, iron powder (for example, trade name Somaloy 500 manufactured by Höganäs Co., Ltd.) in which a phosphoric acid compound film is formed to improve insulation is commercially available. Has been. Moreover, the thing in which the phosphoric acid compound film as described in Unexamined-Japanese-Patent No. 10-154613 was formed is mentioned.
絶縁物としての樹脂は、シリコーン樹脂、エポキシ樹脂、フェノール樹脂、ポリアミド樹脂、ポリイミド樹脂など種々提案されているが（例えば、文献１を参照）、耐熱性に優れるものとしては熱硬化性ポリイミド樹脂（例えば、文献２を参照）が挙げられる。樹脂の含有量は、少ないほど高い密度に成形することができ、磁束密度を高いものとすることができるが、リアクトルやトランスコア等に用いられる圧粉磁心では、２０〜４００ｋＨｚ程度の高周波に耐えられる（高周波渦電流電力損失が少ない）絶縁性が必要である。また、リアクトルやトランスコア等に用いられる圧粉磁心は、大電流までの直流重畳特性が安定していることが求められるため、絶縁物としての樹脂量は１〜５質量％程度とされる。樹脂量が多すぎると圧粉磁心の鉄粉充填密度が下がり磁束密度および透磁率が低くなる（例えば、文献１を参照）ことが知られている。 Various resins such as silicone resins, epoxy resins, phenolic resins, polyamide resins, and polyimide resins have been proposed as insulators (see, for example, Reference 1), but thermosetting polyimide resins ( For example, see Document 2. The smaller the resin content, the higher the density and the higher the magnetic flux density. However, in the dust core used for the reactor, the transformer core, etc., the resin core can withstand high frequencies of about 20 to 400 kHz. It must be insulated (with low high-frequency eddy current power loss). Moreover, since the powder magnetic core used for a reactor, a transformer core, etc. is calculated | required that the direct current | flow superimposition characteristic to a large electric current is stable, the resin amount as an insulator shall be about 1-5 mass%. It is known that when the amount of the resin is too large, the iron powder filling density of the dust core decreases and the magnetic flux density and permeability become low (see, for example, Document 1).
以上の混合粉は金型を用いて圧縮成形される。この成形では、混合粉の圧縮性および成形体の離型性をよくするため、混合粉にステアリン酸亜鉛やステアリン酸リチウム等の成形潤滑剤を添加する方法（例えば、文献２や３を参照）がある。 The above mixed powder is compression molded using a mold. In this molding, a method of adding a molding lubricant such as zinc stearate or lithium stearate to the mixed powder in order to improve the compressibility of the mixed powder and the mold releasability (see, for example, References 2 and 3). There is.
混合粉の圧縮成形は、常温で行うか、又は、金型と混合粉とを１００℃程度に加熱して行う温間成形方法（例えば、文献４を参照）がある。得られた圧縮成形体は、樹脂が硬化する温度、例えば、ポリイミド樹脂では２００℃程度で加熱処理される（文献２を参照）。 The compression molding of the mixed powder is performed at room temperature, or there is a warm molding method (for example, see Document 4) in which the mold and the mixed powder are heated to about 100 ° C. The obtained compression-molded body is heat-treated at a temperature at which the resin is cured, for example, about 200 ° C. with a polyimide resin (see Document 2).
上記した従来技術の中で、鉄粉に熱硬化性ポリイミド樹脂を約１〜５質量％と成形潤滑剤とを添加した混合粉を圧縮成形し、樹脂硬化加熱処理した圧粉磁心は、高周波特性に優れるものであるが、以下のような課題がある。
（１）混合粉にステアリン酸亜鉛等の成形潤滑剤を添加すると、圧縮性が良くなるが粉末成形体の強度が低くなり（文献３を参照）、樹脂の熱処理で成形潤滑剤が溶融して樹脂の硬化を阻害し易くなる。
（２）成形潤滑剤の添加量を少なくし、常温下で圧縮成形すると、成形体を金型から抜き出す圧力が高くなり、金型と成形体がかじりなどを生じ易くなる。
（３）一方、圧縮性をよくするため、圧縮成形を金型と混合粉とを加熱した温間成形で行うと、樹脂が軟化して変形し易くなり、樹脂の含有量が１〜５質量％の場合では、樹脂量が比較的多いため成形金型のパンチに成形体が付着したり、成形体表面が樹脂の多い状態となったり、成形体の側面にクラックが発生するなどの諸問題が発生する。
Among the above-described conventional technologies, a powder magnetic core obtained by compression-molding a mixed powder obtained by adding about 1 to 5% by mass of a thermosetting polyimide resin to iron powder and a molding lubricant and heat-treating the resin has high frequency characteristics. However, there are the following problems.
(1) When a molding lubricant such as zinc stearate is added to the mixed powder, the compressibility is improved, but the strength of the powder molded body is reduced (see Reference 3), and the molding lubricant is melted by heat treatment of the resin. It becomes easy to inhibit hardening of resin.
(2) When the amount of molding lubricant added is reduced and compression molding is performed at room temperature, the pressure for extracting the molded body from the mold increases, and the mold and the molded body tend to galling.
(3) On the other hand, in order to improve the compressibility, when the compression molding is performed by warm molding in which the mold and the mixed powder are heated, the resin is softened and easily deformed, and the resin content is 1 to 5 mass. %, The amount of resin is relatively large, so the molded body adheres to the punch of the molding die, the surface of the molded body becomes rich in resin, and cracks occur on the side of the molded body. Will occur.
この発明は、以上のような課題を解消して、樹脂量が比較的多い圧粉磁心の場合にも、圧縮成形後の抜出し圧力が低く、金型かじりやひび割れを生じない高性能の圧粉磁心を安定して量産できるようにすることを目的としている。 This invention eliminates the above-mentioned problems, and even in the case of a powder magnetic core having a relatively large amount of resin, the high-performance dust that does not cause mold galling or cracking because the extraction pressure after compression molding is low. The purpose is to enable stable mass production of magnetic cores.
請求項１の発明は、温度が６０℃〜１００℃の範囲で加熱した粉末成形用金型のキャビティ壁面に、成形潤滑剤粉末を単位面積当たり０．２〜２．０ｍｇ／ｃｍ２ の範囲内で塗布しておき、鉄粉又は絶縁皮膜を形成した鉄粉に１〜５質量％の樹脂粉を混合した混合粉を該キャビティに充填し、圧縮成形することを特徴としている。
以上の圧粉磁心の成形方法は、圧粉成形の際の金型温度および金型用成形潤滑剤を適量に制御することにより、従来の諸問題を一掃して高周波特性に優れた圧粉磁心を安定して成形可能にしたものである。ここで、成形潤滑剤粉末の金型への塗布方法は、均一化および作業効率から潤滑剤粉末を静電塗布或いはアルコール分散液にして塗布することである。
According to the first aspect of the present invention, the molding lubricant powder is placed in the range of 0.2 to 2.0 mg / cm 2 per unit area on the cavity wall surface of the powder molding die heated at a temperature of 60 ° C. to 100 ° C. It is characterized in that the cavity is filled with a mixed powder obtained by mixing 1 to 5% by mass of a resin powder with an iron powder or an iron powder having an insulating film formed thereon, and compression molding.
The dust core molding method described above is a dust core having excellent high-frequency characteristics by eliminating the conventional problems by controlling the mold temperature and mold molding lubricant at the time of dust molding. Can be molded stably. Here, the method of applying the molding lubricant powder to the mold is to apply the lubricant powder as an electrostatic coating or an alcohol dispersion in view of homogenization and work efficiency.
以上の成形方法において、前記樹脂粉は、請求項２に記載のように、熱硬化性ポリイミド樹脂粉又はエポキシ樹脂粉が好適である。混合粉中の成形潤滑剤は、請求項３に記載のように、含まないことが好ましいが、０．１質量％以下で添加しても高周波特性にさほど影響を与えないため差し支えない。金型構造としては、請求項４に記載のように、金型のダイ内面又はコアロッド外面が、１／１００〜１／５０００のテーパを付与したものを用いること、請求項５に記載のように、金型がダイ内面又はコアロッド外面にＣｒＮ，ＴｉＮ，ＴｉＣ，Ａｌ２Ｏ３ ，ＴｉＣＮ，ＨｆＮ，Ｗ２Ｃ，ＤＬＣ（Diamond Like Carbon）のいずれか又はこれら複合のコーティング層を付与したもの、或いは、浸硫窒化による表面改質を行ったものを用いることがより好適である。 In the above molding method, the resin powder is preferably thermosetting polyimide resin powder or epoxy resin powder as described in claim 2. As described in claim 3, it is preferable not to include the molding lubricant in the mixed powder. However, even if it is added in an amount of 0.1% by mass or less, the high frequency characteristics are not affected so much. As the mold structure, as described in claim 4, a die inner surface or a core rod outer surface having a taper of 1/100 to 1/5000 is used, as described in claim 5. A mold provided with a coating layer of CrN, TiN, TiC, Al 2 O 3 , TiCN, HfN, W 2 C, DLC (Diamond Like Carbon) or a composite of these on the inner surface of the die or the core rod, or It is more preferable to use one that has been surface-modified by nitrosulfiding.
以上の発明方法は、所定温度に加熱された金型に成形潤滑粉末を適正な量で塗布し、常温の混合粉を充填して圧縮成形するため、量産時の制御ないしは管理が簡単であり、圧縮成形による材料欠陥がなく、高密度な圧粉磁心を提供することができる。 The above invention method is easy to control or manage at the time of mass production because the molding lubricant powder is applied to a mold heated to a predetermined temperature in an appropriate amount, filled with normal temperature mixed powder and compression molded. There is no material defect due to compression molding, and a high-density powder magnetic core can be provided.
以下、本発明の最良の形態を詳しく説明する。
（１）混合粉
鉄粉は絶縁処理されたものが好ましい。これは、リアクトルやトランスコア等は高周波領域で用いられるためである。市販品としては、例えば、ヘガネス社製の商品名Ｓｏｍａｌｏｙ５００、Ｐｅｒｍｉｔｅ７５が挙げられる。より好ましくは、特開平１０−１５４６１３号公報に記載されているような無機系酸化物の絶縁被膜が形成された鉄粉を用いることである。鉄粉に混合される樹脂は、ポリイミド、エポキシ、ポリフェニレンサルファイド（ＰＰＳ）等が挙げられるが、耐熱性が良好な熱硬化性ポリイミド又はエポキシ樹脂が好ましい。添加量は、許容される鉄損に応じて適宜決定されるが、１〜５質量％の範囲内であり、好ましくは２〜３質量％である。混合粉中の成形潤滑剤は、添加しない方が磁性特性に悪影響を与えるおそれがなく好ましいが、０．１質量％以下で添加してもさほど影響を与えないため差し支えない。
Hereinafter, the best mode of the present invention will be described in detail.
(1) Mixed powder The iron powder is preferably subjected to insulation treatment. This is because a reactor, a transformer core, and the like are used in a high frequency region. As a commercial item, the brand names Somaloy500 and Permite75 by a Heganess company are mentioned, for example. More preferably, iron powder having an inorganic oxide insulating film as described in JP-A-10-154613 is used. Examples of the resin mixed with the iron powder include polyimide, epoxy, polyphenylene sulfide (PPS), and the like, but thermosetting polyimide or epoxy resin having good heat resistance is preferable. The amount added is appropriately determined according to the allowable iron loss, but is in the range of 1 to 5% by mass, preferably 2 to 3% by mass. It is preferable not to add the molding lubricant in the mixed powder because there is no risk of adversely affecting the magnetic properties, but even if it is added at 0.1% by mass or less, it does not affect so much.
（２）粉末成形
成形方法は、成形金型のキャビティに混合粉（鉄粉と樹脂粉）を充填し、上下のパンチで圧縮成形し、離型される。この場合、混合粉を充填する前にダイキャビティを形成し、ダイキャビティ内壁面（ダイ内面やコア外面）に後述する成形潤滑剤を塗布したのち、混合粉を充填して圧縮する。このような成形では、電気ヒータ等の加熱手段を持つ金型および粉末フィーダを用いて行われる。混合粉は加熱しない。金型の温度は各種試験より６０〜１００℃であり、好ましくは８０〜９０℃である。金型温度６０℃は、成形の初期段階で金型を加熱昇温しておくと、成形の摩擦熱でその温度をほぼ維持することができる場合がある。金型用成形潤滑剤および樹脂との関係では、例えば、ステアリン酸亜鉛やステアリン酸リチウムのような成形潤滑剤だと、圧縮成形体を金型から抜き出す際の圧力が常温では高く、金型の温度が８０〜９０℃のとき最も低くなる。１００℃を超えると抜出し性が悪くなったり、混合粉中の樹脂が軟化して、前述したような圧縮成形体に不具合が生じ易くなる。
(2) Powder molding In the molding method, a mixed powder (iron powder and resin powder) is filled in a cavity of a molding die, compression-molded with upper and lower punches, and released. In this case, the die cavity is formed before the mixed powder is filled, and the molding lubricant described later is applied to the inner surface of the die cavity (the inner surface of the die and the outer surface of the core), and then the mixed powder is filled and compressed. Such molding is performed using a mold having a heating means such as an electric heater and a powder feeder. The mixed powder is not heated. The temperature of a metal mold | die is 60-100 degreeC from various tests, Preferably it is 80-90 degreeC. When the mold temperature is 60 ° C. and the mold is heated and heated in the initial stage of molding, the temperature may be substantially maintained by the frictional heat of molding. In relation to molding lubricants and resins for molds, for example, when molding lubricants such as zinc stearate and lithium stearate are used, the pressure at which the compression molded product is extracted from the mold is high at room temperature. It becomes the lowest when the temperature is 80 to 90 ° C. When the temperature exceeds 100 ° C., the drawability is deteriorated, or the resin in the mixed powder is softened, and the above-described compression molded body is liable to have a defect.
（３）成形潤滑剤
金型に塗布する成形潤滑剤は、前記したステアリン酸亜鉛やステアリン酸リチウム以外にも、エチレンビスステアロアマイド等を用いることができる。能率良く安定した塗布のためには、成形潤滑剤粉を静電塗布或いはアルコール分散液にして塗布することが望ましい。金型に成形潤滑剤を塗布する方法では、混合粉（鉄粉と樹脂粉）に成形潤滑剤が混入されるおそれなしに、高い成形密度と、金型ダイキャビティとの摩擦を低減することができる。
(3) Molding lubricant As the molding lubricant applied to the mold, ethylene bisstearamide or the like can be used in addition to the aforementioned zinc stearate and lithium stearate. For efficient and stable application, it is desirable to apply the molded lubricant powder as an electrostatic application or an alcohol dispersion. In the method of applying molding lubricant to the mold, high molding density and friction with the mold die cavity can be reduced without the risk of mixing the molding lubricant into the mixed powder (iron powder and resin powder). it can.
（４）成形潤滑剤の金型塗布量
金型キャビティ壁面に塗布する成形潤滑剤の量は、混合粉の圧縮性および圧粉磁心の磁束密度に影響を及ぼす。成形潤滑剤の塗布の状況によっては、圧粉体にかじり傷が付いたり、抜出し圧力が高かったり、圧粉体の密度の割には期待する磁束密度が得られなくなる。成形潤滑剤が少ないと、混合粉の圧縮性および成形体の抜出し性が悪くなり、圧粉体の表面にかじり傷を生じ易くなる。したがって、金型キャビティ壁面に塗布される潤滑剤の量は、各種試験から少なくとも０．２ｍｇ／ｃｍ２以上が必要である。一方、成形潤滑剤量の塗布量が多すぎると、成形体が塗布されていた成形潤滑剤を巻き込み、表面部分において鉄粉充填密度が下がる。磁束密度および透磁率は、圧粉磁心の鉄粉充填密度に依存するので、成形潤滑剤の巻き込みは鉄粉間の磁気的空隙を大きくすることになり、磁気特性を悪化させる要因となるので、金型キャビティ壁面に塗布する成形潤滑剤の量としては２ｍｇ／ｃｍ２以下にすることが必須となる。
(4) Mold application amount of molding lubricant The amount of molding lubricant applied to the mold cavity wall surface affects the compressibility of the mixed powder and the magnetic flux density of the dust core. Depending on the state of application of the molding lubricant, the green compact may be scratched, the extraction pressure is high, or the expected magnetic flux density cannot be obtained for the density of the green compact. When the molding lubricant is small, the compressibility of the mixed powder and the extractability of the molded product are deteriorated, and the surface of the green compact tends to be galling. Therefore, the amount of lubricant applied to the mold cavity wall surface needs to be at least 0.2 mg / cm 2 or more from various tests. On the other hand, when there is too much application quantity of a shaping | molding lubricant amount, the shaping | molding lubricant with which the molded object was apply | coated is involved, and an iron powder filling density falls in the surface part. Since the magnetic flux density and permeability depend on the iron powder filling density of the powder magnetic core, the entrainment of the molding lubricant will increase the magnetic gap between the iron powders, which will deteriorate the magnetic properties. It is essential that the amount of molding lubricant applied to the mold cavity wall surface be 2 mg / cm 2 or less.
（５）粉末成形金型
粉末成形金型は、ダイ内面又はコアロッド外面にテーパを付与したものを用いると、金型から成形体を抜出すときの圧力を少なくすることができるので、より好ましく実施できる。これは、圧粉磁心は高密度が望ましいので、より高い圧力で成形されるため成形体の抜出し圧力が比較的高いものになるからである。テーパとしては１／１００〜１／５０００の範囲内で、ダイ内径が入り口に向かって拡がるように、コア外径が入り口に向かって細くなるように形成される。テーパが１／５０００より小さいと抜出し圧力低減効果が得られない。テーパが１／１００より大きいと成形体にテーパが形成されるだけではなく、加圧時にダイおよびコアロッドが受ける加圧方向に平行な圧力が大きくなり好ましくない。このため、適切なテーパは１／１００〜１／５０００の範囲内であり、より好ましくは１／１２５０〜１／２５００である。
(5) Powder Molding Mold A powder molding mold is more preferable because it can reduce the pressure when the molded body is extracted from the mold when the die inner surface or the core rod outer surface is tapered. it can. This is because the powder magnetic core desirably has a high density, and is molded at a higher pressure, so that the extraction pressure of the molded body becomes relatively high. The taper is formed within a range of 1/100 to 1/5000 so that the outer diameter of the core becomes narrower toward the entrance so that the inner diameter of the die expands toward the entrance. If the taper is less than 1/5000, the extraction pressure reduction effect cannot be obtained. When the taper is larger than 1/100, not only the taper is formed in the molded body, but also the pressure parallel to the pressurizing direction that the die and the core rod receive during pressurization becomes unfavorable. For this reason, a suitable taper is in the range of 1/100 to 1/5000, more preferably 1/1250 to 1/2500.
また、成形金型の表面に硬質なコーティング層や改質層を形成したものを用いれば、金型の耐摩耗性が向上し、圧縮性および離型性が安定するので高密度成形を実現し易くなる。この場合、金型材料は金型工具鋼ＳＫＤ系、高速度鋼ＳＫＨ系、粉末ハイス、超硬合金などが用いられる。その表面にはＣｒＮ，ＴｉＮ，ＴｉＣ，Ａｌ２Ｏ３ ，ＴｉＣＮ，ＨｆＮ，Ｗ２Ｃ，ＤＬＣのいずれか又は複合のコーティング層を付与し、又は、浸硫窒化による表面改質処理が行われる。 Also, if a hard coating layer or modified layer is formed on the surface of the mold, the wear resistance of the mold will be improved, and the compressibility and mold release will be stable, enabling high-density molding. It becomes easy. In this case, die tool steel SKD type, high speed steel SKH type, powder high speed steel, cemented carbide or the like is used as the die material. The surface is provided with a coating layer of any one of CrN, TiN, TiC, Al 2 O 3 , TiCN, HfN, W 2 C, and DLC or a composite, or is subjected to surface modification treatment by nitronitriding.
（５）圧縮成形体の後処理
得られた圧縮成形体は、従来と同様に添加された樹脂の種類に応じた温度で加熱処理される。加熱温度は、例えば、熱硬化性ポリイミド樹脂を用いた場合だと２００℃程度である。また、複雑な形状をした圧粉磁心では、後処理として切削加工や金型を用いてサイジングすることができる。
(5) Post-treatment of compression molded body The obtained compression molded body is heat-treated at a temperature corresponding to the type of resin added in the same manner as in the prior art. The heating temperature is, for example, about 200 ° C. when a thermosetting polyimide resin is used. In addition, a powder magnetic core having a complicated shape can be sized using a cutting process or a mold as post-processing.
実施例１は、金型用成形潤滑剤の塗布量を一定にして、金型温度変化による抜出し圧の影響を調べたときの一例である。
（混合粉）リン酸被膜絶縁処理アトマイズ鉄粉（ヘガネス社製Ｓｏｍａｌｏｙ５００）に、粒度が２０μm以下の熱硬化性ポリイミド粉を２質量％添加し混合した。この混合粉には成形潤滑剤を添加していない。
（成形金型）成形金型は、金型のダイキャビティ直径が２０ｍｍで、電気ヒータが付設れており、所定温度に保持できるようになっている。
（成形条件）圧縮成形では、金型の温度を４０℃、７０℃、９０℃、１００℃、１２０℃の各温度において、金型のキャビティ内壁に成形潤滑剤粉を静電塗布法により付着させ、常温の混合粉４３．０ｇを充填したのち、圧力７００ＭＰａで圧縮し、成形体を金型から抜き出した。使用した成形潤滑剤は、ステアリン酸亜鉛粉（Ｓｔ−Ｚｎ）と、ステアリン酸リチウム粉（Ｓｔ−Ｌｉ）とを用い、単位面積当たりの塗布量を１．５ｍｇ／ｃｍ２とした。この成形潤滑剤の塗布量は、静電塗布する際の噴射時間と単位面積当たりの塗布量の関係を予め測定しておき、対応する時間を噴射したものである。
Example 1 is an example in which the influence of the extraction pressure due to a change in mold temperature was examined while the application amount of the molding lubricant for the mold was made constant.
(Mixed powder) 2 mass% of thermosetting polyimide powder having a particle size of 20 μm or less was added to and mixed with phosphoric acid coating insulating atomized iron powder (Somaloy 500 manufactured by Höganäs). A molding lubricant is not added to the mixed powder.
(Molding Die) The molding die has a die cavity diameter of 20 mm and is provided with an electric heater so that it can be maintained at a predetermined temperature.
(Molding conditions) In compression molding, molding lubricant powder is attached to the inner wall of the mold cavity by electrostatic coating at temperatures of the mold of 40 ° C, 70 ° C, 90 ° C, 100 ° C, and 120 ° C. Then, after filling 43.0 g of mixed powder at room temperature, the mixture was compressed at a pressure of 700 MPa, and the compact was extracted from the mold. Molding lubricant used include zinc stearate powder and (St-Zn), using lithium stearate powder (St-Li), the coating amount per unit area was 1.5 mg / cm 2. The application amount of the molding lubricant is obtained by measuring in advance the relationship between the spraying time for electrostatic coating and the coating amount per unit area, and spraying the corresponding time.
表１は、前記金型の各温度において、成形潤滑剤が成形体の抜出し圧に及ぼす影響と、成形体を２００℃で熱処理した圧粉磁心の外観に及ぼす影響を示したものである。各値は、ステアリン酸亜鉛粉を塗布した試験、ステアリン酸リチウム粉を塗布した試験、合計２回の試験結果を平均した値であるが、成形潤滑剤の種類による相違はほとんど認められなかった。表１からは、金型温度が高いほど抜出し圧として低下するが、金型温度が１２０℃だと成形体表面に樹脂が吹き出し膨れたような外観を示したり、ひび割れが認められるようになる。このように金型潤滑成形では、まず、金型温度が高いほど抜出し性が良好となるが、１００℃を超えないことが必須となる。金型温度の下限値は、通常の成形温度である約４０℃でも可能であるが、抜き出し圧を小さくして外観を維持する上で６０℃以上にすることが好ましい。 Table 1 shows the influence of the molding lubricant on the extraction pressure of the molded body and the influence on the appearance of the dust core obtained by heat-treating the molded body at 200 ° C. at each temperature of the mold. Each value is a value obtained by averaging a test result obtained by applying a zinc stearate powder, a test applying a lithium stearate powder, and a total of two test results, but almost no difference was observed depending on the type of molding lubricant. From Table 1, the higher the mold temperature is, the lower the extraction pressure is. However, when the mold temperature is 120 ° C., the appearance is such that the resin blows and swells on the surface of the molded body, or cracks are recognized. In this way, in the mold lubrication molding, first, the higher the mold temperature, the better the drawability, but it is essential not to exceed 100 ° C. The lower limit of the mold temperature can be about 40 ° C., which is a normal molding temperature, but is preferably 60 ° C. or higher in order to maintain the appearance by reducing the extraction pressure.
実施例２は、成形潤滑剤の塗布量を変えたときに、抜き出し圧、圧粉磁心の物性への影響を調べたときの一例である。
（混合粉）前記と同様に、リン酸被膜絶縁処理アトマイズ鉄粉に、粒度が２０μm以下の熱硬化性ポリイミド粉末を２質量％添加し混合した。混合粉には成形潤滑剤を添加していない。
（成形金型）金型は、キャビティ入り口寸法が１１０×２５ｍｍの長方形で、電気ヒータが付設れており、所定温度に保持できるようになっている。
（成形条件）この成形では、金型温度を９０℃に加熱し、金型キャビティ内壁に成形潤滑剤としてステアリン酸亜鉛粉を静電塗布法により付着させて、常温の混合粉３５０ｇを充填した。そして、圧力６８６ＭＰａで圧縮し、成形体を金型から抜き出した。なお、ステアリン酸亜鉛粉の塗布量は、前述したと同様に、静電塗布する際の噴射時間と単位面積当たりの塗布量の関係を予め測定しておき、噴射時間に対応して塗布量とした。
Example 2 is an example when the influence on the physical properties of the extraction pressure and the dust core is examined when the application amount of the molding lubricant is changed.
(Mixed powder) In the same manner as described above, 2% by mass of a thermosetting polyimide powder having a particle size of 20 μm or less was added to and mixed with the phosphoric acid coating insulating atomized iron powder. A molding lubricant is not added to the mixed powder.
(Molding Die) The mold has a rectangular shape with a cavity entrance dimension of 110 × 25 mm, and an electric heater is attached so that the mold can be maintained at a predetermined temperature.
(Molding Conditions) In this molding, the mold temperature was heated to 90 ° C., and zinc stearate powder as a molding lubricant was attached to the inner wall of the mold cavity by an electrostatic coating method, and 350 g of mixed powder at room temperature was filled. And it compressed with the pressure of 686 Mpa, and the molded object was extracted from the metal mold | die. In addition, the coating amount of zinc stearate powder is measured in advance in the same manner as described above, the relationship between the spraying time and the coating amount per unit area at the time of electrostatic coating, and the coating amount corresponding to the spraying time. did.
試験では、塗布量を表２の８通りに変えて、圧縮成形後の金型からの抜出し圧力、成形体を温度２００℃で加熱処理して得られた圧粉磁心の各試料について密度と磁束密度並びに外観状態を観察した。表２はその結果を示している。なお、密度は、圧粉磁心の重量と寸法測定値から計算された体積とから算出した値である。磁束密度は、直流ＢＨアナライザーを用いてＢ10,000Ａ／ｍの値（Ｔ：テスラー）である。外観状態は、かじりの有無、肌荒れや変形等を目視で行った。 In the test, the density and magnetic flux of each sample of the powder magnetic core obtained by changing the coating amount to 8 in Table 2 and extracting the pressure from the mold after compression molding and heating the molded body at a temperature of 200 ° C. The density and appearance were observed. Table 2 shows the results. The density is a value calculated from the weight of the dust core and the volume calculated from the dimension measurement value. The magnetic flux density is a value of B10,000 A / m (T: Tessler) using a DC BH analyzer. The appearance was visually checked for galling, rough skin, deformation, and the like.
表２において、各試料（圧粉磁心）を比較すると、成形潤滑剤の塗布量が多いほど密度および磁束密度がともに少しずつ低下しており、又、塗布量が０．１８ｍｇ／ｃｍ２から２．０２ｍｇ／ｃｍ２の範囲では塗布量の減少に伴って抜出し圧が次第に低くなるが、外観に欠点が認められず、金型潤滑の程度が最適で圧粉磁心の密度および磁束密度に悪影響がないことを示している。しかし、塗布量が２．０２ｍｇ／ｃｍ２を超えると、密度および磁束密度ともに低下し、又、金型と成形体との潤滑は良好であるが、成形潤滑剤が成形体に悪影響している。これは、混合粉を圧縮成形する過程で成形体の表層部に潤滑剤を巻き込んで成形され、成形体表層部の密度が低くなったものと考えられる。すなわち、塗布量が０．１８ｍｇ／ｃｍ２より少ない０．１０ｍｇ／ｃｍ２の場合では、抜出しの圧力が２４．８ＭＰａと高く、成形体にかじり傷などが発生し易く、成形潤滑剤の塗布量が少なすぎると金型と成形体との潤滑が不足することが分かる。このように、金型と成形体との摩擦低減のためには塗布量０．２ｍｇ／ｃｍ２ 以上が必要であり、逆に、２．０ｍｇ／ｃｍ２ を超える塗布量では外観を維持できず、期待する磁束密度が得られないことが分かる。 In Table 2, when comparing each sample (powder magnetic core), both the density and the magnetic flux density are gradually decreased as the molding lubricant application amount is increased, and the application amount is from 0.18 mg / cm 2 to 2. In the range of 0.02 mg / cm 2, the extraction pressure gradually decreases as the coating amount decreases, but there are no defects in appearance, the degree of mold lubrication is optimal, and the density and magnetic flux density of the dust core are adversely affected. It shows no. However, when the coating amount exceeds 2.02 mg / cm 2 , both the density and the magnetic flux density decrease, and the lubrication between the mold and the molded body is good, but the molding lubricant has an adverse effect on the molded body. . This is considered to be because the lubricant was formed in the surface layer portion of the molded body in the process of compression molding the mixed powder, and the density of the surface layer portion of the molded body was lowered. That is, in the case the coating amount is 0.18 mg / cm 2 less than 0.10 mg / cm 2, high pressure extraction is the 24.8MPa, liable like occurs scratches galling in the molded body, the coating amount of the molded lubricant It can be seen that if the amount is too small, the lubrication between the mold and the molded body is insufficient. Thus, in order to reduce the friction between the mold and the molded body, an application amount of 0.2 mg / cm 2 or more is necessary. Conversely, when the application amount exceeds 2.0 mg / cm 2 , the appearance cannot be maintained. It can be seen that the expected magnetic flux density cannot be obtained.
（ダイ側テーパによる影響）次に、ダイ側テーパによる影響を調べたときの一例を挙げる。成形金型は、ダイ内面にテーパを付けないものと、ダイ内面に１／１２５０のテーパを付与したもの（それ以外は同じもの）を用いて、ステアリン酸亜鉛粉を実施例１と同様に静電塗布により塗布量１．５ｍｇ／ｃｍ２ となるよう塗布した。成形では、実施例１や２と同じ混合粉を用い、温度６０℃の金型ダイキャビテイに充填し、圧力６８６ＭＰａで圧縮成形した。抜出し圧力は、テーパを付けたダイではテーパを付けないダイに比べて約１０％程度低くなった。テーパを付けたダイの成形体は、外周にかじり傷が一切認められず、テーパを付けないダイの成形体に比べ光沢面となっていた。各成形体を温度２００℃で加熱処理して得られた圧粉磁心の密度は、テーパの有無によって変化なく同じであった。 (Influence by die side taper) Next, an example of examining the influence by the die side taper will be given. As the molding die, a zinc stearate powder was statically fixed in the same manner as in Example 1 using a die inner surface not tapered and a die inner surface having a taper of 1/1250 (the same is otherwise). It apply | coated so that it might become a coating amount of 1.5 mg / cm < 2 > by electrocoating. In the molding, the same mixed powder as in Examples 1 and 2 was used, filled in a die die cavity having a temperature of 60 ° C., and compression molded at a pressure of 686 MPa. The extraction pressure was about 10% lower in the tapered die than in the non-tapered die. The die-formed body with the taper had no galling scratches on the outer periphery, and had a glossy surface compared to the die-shaped body without the taper. The density of the dust core obtained by heat-treating each molded body at a temperature of 200 ° C. was the same without change depending on the presence or absence of a taper.
（表面処理による影響）次に、ダイ内面に表面処理を施したときの影響を調べたときの一例を挙げる。成形金型は、ダイ内面に窒化クロム（ＣｒＮ）処理を施したものと、処理を施さないもの（それ以外は同じもの）を用いて、前記と同じ混合粉を同じ条件で圧縮成形した。この成形体の抜出し力は、窒化クロム処理を施した方は処理を施さない場合に比べ約５％程度低く、成形体の外周はより光沢があった。各成形体を温度２００℃で加熱処理して得られた圧粉磁心の密度は、前記テーパの場合と同様に表面処理の有無によっても変化なく同じであった。 (Influence of surface treatment) Next, an example of examining the influence of surface treatment on the inner surface of the die will be given. As the molding die, the same mixed powder as described above was compression-molded under the same conditions using a chromium nitride (CrN) treatment on the inner surface of the die and a non-treated one (others were the same). The extraction force of the molded body was about 5% lower when the chromium nitride treatment was performed than when the treatment was not performed, and the outer periphery of the molded body was more glossy. The density of the powder magnetic core obtained by heat-treating each molded body at a temperature of 200 ° C. was the same without change depending on the presence or absence of surface treatment as in the case of the taper.
以上のことから、金型キャビティの壁面（ダイ内面やコアロッド外面）にテーパを設けたり、窒化クロム等の硬質表面処理を施すと抜出し圧力が低下し、成形体の外周にかじり傷などがなく、光沢面となることから、より高い成形圧力を適用して高密度成形する際に好適な手段であることが分かる。
From the above, if the wall surface (die inner surface or core rod outer surface) of the mold cavity is tapered, or the hard surface treatment such as chromium nitride is applied, the extraction pressure is reduced, and the outer periphery of the molded body is free from galling. Since it becomes a glossy surface, it turns out that it is a suitable means at the time of applying high molding pressure and performing high density molding.
Claims (5)
The mold has a die inner surface or a core rod outer surface coated with any one of CrN, TiN, TiC, Al 2 O 3 , TiCN, HfN, W 2 C, and DLC or a composite coating layer, or by oxynitriding The method for forming a powder magnetic core according to claim 1, wherein the surface is modified.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003296993A JP4353512B2 (en) | 2003-08-21 | 2003-08-21 | Molding method of powder magnetic core |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003296993A JP4353512B2 (en) | 2003-08-21 | 2003-08-21 | Molding method of powder magnetic core |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2005072112A true JP2005072112A (en) | 2005-03-17 |
| JP4353512B2 JP4353512B2 (en) | 2009-10-28 |
Family
ID=34402977
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2003296993A Expired - Fee Related JP4353512B2 (en) | 2003-08-21 | 2003-08-21 | Molding method of powder magnetic core |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4353512B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011042844A (en) * | 2009-08-21 | 2011-03-03 | Hitachi Powdered Metals Co Ltd | Powder molding method |
| JP2012092385A (en) * | 2010-10-26 | 2012-05-17 | Daihatsu Motor Co Ltd | Method of manufacturing metal green compact |
| JP2014114487A (en) * | 2012-12-10 | 2014-06-26 | Sumitomo Electric Ind Ltd | Powder-compressed molded body, manufacturing method of powder-compressed molded body, heat-treated body, and coil component |
| WO2014136587A1 (en) | 2013-03-08 | 2014-09-12 | Ntn株式会社 | Magnetic core powder, powder magnetic core, and method for producing magnetic core powder and powder magnetic core |
| WO2014175555A1 (en) * | 2013-04-25 | 2014-10-30 | 배은영 | High-performance sendust powder core and method for production thereof |
| CN106925775A (en) * | 2017-04-17 | 2017-07-07 | 河南工业大学 | A kind of method of diadust plated surface chromium carbide |
-
2003
- 2003-08-21 JP JP2003296993A patent/JP4353512B2/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011042844A (en) * | 2009-08-21 | 2011-03-03 | Hitachi Powdered Metals Co Ltd | Powder molding method |
| JP2012092385A (en) * | 2010-10-26 | 2012-05-17 | Daihatsu Motor Co Ltd | Method of manufacturing metal green compact |
| JP2014114487A (en) * | 2012-12-10 | 2014-06-26 | Sumitomo Electric Ind Ltd | Powder-compressed molded body, manufacturing method of powder-compressed molded body, heat-treated body, and coil component |
| WO2014136587A1 (en) | 2013-03-08 | 2014-09-12 | Ntn株式会社 | Magnetic core powder, powder magnetic core, and method for producing magnetic core powder and powder magnetic core |
| WO2014175555A1 (en) * | 2013-04-25 | 2014-10-30 | 배은영 | High-performance sendust powder core and method for production thereof |
| CN106925775A (en) * | 2017-04-17 | 2017-07-07 | 河南工业大学 | A kind of method of diadust plated surface chromium carbide |
| CN106925775B (en) * | 2017-04-17 | 2019-01-25 | 河南工业大学 | A kind of method of diadust surface plating chromium carbide |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4353512B2 (en) | 2009-10-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105659337B (en) | The pressing mold and the lubricating composition of die device and compressed-core stamper for manufacturing that compressed-core, magnetic core are manufactured with the manufacture method of powder compact, compressed-core | |
| JP5906054B2 (en) | Molding method of green compact | |
| JP4723442B2 (en) | Powder cores and iron-based powders for dust cores | |
| JP2009302420A (en) | Dust core and manufacturing method thereof | |
| JP2002280209A (en) | High-intensity dust core powder, high-intensity dust core, and its manufacturing method | |
| WO2013175929A1 (en) | Powder core, powder core manufacturing method, and method for estimating eddy current loss in powder core | |
| JP2016171167A (en) | Magnetic sheet material arranged by use of powder compact, and method for manufacturing the same | |
| JP4353512B2 (en) | Molding method of powder magnetic core | |
| JP5965190B2 (en) | Method for producing green compact and green compact | |
| JP6322938B2 (en) | Dust core, method for producing powder for core, mold and mold device for producing dust core, and lubricating liquid for mold for producing dust core | |
| JP5023041B2 (en) | Powder magnetic core and manufacturing method thereof | |
| JP2001223107A (en) | Method of compression molding soft magnetic powder | |
| JP2003318014A (en) | Dust core powder, high-strength dust core, and method of manufacturing the same | |
| JP2004146804A (en) | Manufacturing method for dust core | |
| JP7066586B2 (en) | Manufacturing method of composite magnetic material, metal composite core, reactor, and metal composite core | |
| JP2004342937A (en) | Method of forming dust core | |
| JP6152002B2 (en) | Method for producing a green compact | |
| CN107615411B (en) | Mixed powder for dust core and dust core | |
| JP6437900B2 (en) | Manufacturing method of dust core | |
| JP2006114695A (en) | Magnetic body | |
| JP2005248274A (en) | Soft magnetic material and method for producing green compact | |
| US11794244B2 (en) | Method for manufacturing dust core and raw material powder for dust core | |
| JP5732027B2 (en) | Compressed green body, manufacturing method of compacted body, heat treatment body and coil component | |
| JP6174954B2 (en) | Method for producing a green compact | |
| WO2015045561A1 (en) | Dust core, method for producing dust core and coil component |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20060330 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20081007 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20081014 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20081105 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20090727 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20090727 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 4353512 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120807 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120807 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130807 Year of fee payment: 4 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313111 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| LAPS | Cancellation because of no payment of annual fees |