JP4284042B2 - Dust core - Google Patents
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- JP4284042B2 JP4284042B2 JP2002229712A JP2002229712A JP4284042B2 JP 4284042 B2 JP4284042 B2 JP 4284042B2 JP 2002229712 A JP2002229712 A JP 2002229712A JP 2002229712 A JP2002229712 A JP 2002229712A JP 4284042 B2 JP4284042 B2 JP 4284042B2
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Description
【０００１】
【発明の属する技術分野】
この発明は、圧粉磁心に関するものである。
【０００２】
【従来の技術】
モータの鉄心やトランスコア用として、磁性粒子を高純度の鉄粉とした圧粉磁心は、比較的高い磁束密度で鉄損が低いことが知られている。
このような圧粉磁心は、絶縁性の結合樹脂を混合した鉄粉を圧縮成形し、加熱処理して作られ、孔開け加工やねじ加工を施すことがある。
磁束密度は圧粉磁心の密度に依存するので、用いられる鉄粉はより高い密度が得られるアトマイズ鉄粉が用いられ、この鉄粉の表面には、圧粉磁心の鉄損を低くするため、燐酸化合物被膜が施されている。このような鉄粉はヘガネス社製の商品名Ｓｏｍａｌｏｙ５００が挙げられる。
樹脂は、熱硬化性フェノール、熱可塑性ポリアミド、エポキシ、ポリイミド、ポリフェニレンサルファイド（以下、ＰＰＳという。）等、各種の提案がある。
【０００３】
【発明が解決しようとする課題】
このような圧粉磁心は、用いられる周波数が比較的高いものとなっており、より高い磁束密度が得られ、かつ鉄損はできるだけ低いものの要求が高まっている。また、従来の圧粉磁心は、切削加工やドリル孔開け加工を行うと、割れや欠損を生じ易いことも解決すべき課題となっている。
【０００４】
【課題を解決するための手段】
これらの課題を解消すべく検討を重ねた結果、鉄粉及び結合樹脂の選定や添加量等を工夫することにより上記の課題を解消できるとの確証に至り、本発明を完成した。
【０００５】
請求項１の発明は、鉄粉と樹脂粉の混合物を圧縮成形した圧粉磁心において、前記鉄粉がアトマイズ鉄粉及び還元鉄粉で、前記樹脂粉が熱可塑性ポリイミド樹脂（以下、熱可塑性ＰＩという。）粉末、又は熱可塑性ＰＩ及びポリテトラフルオロエチレン（以下、ＰＴＦＥという。）粉末であることを特徴とする。
【０００６】
請求項２の発明は、鉄粉と樹脂粉の混合物を圧縮成形した圧粉磁心において、前記鉄粉がアトマイズ鉄粉と還元鉄粉とを含み、還元鉄粉が鉄粉質量の５〜５０質量％であり、前記樹脂粉が熱可塑性ＰＩで全質量に占める含有量が０.３質量％以下であることを特徴とする。
【０００７】
請求項３の発明は、鉄粉と樹脂粉の混合物を圧縮成形した圧粉磁心において、前記鉄粉がアトマイズ鉄粉と還元鉄粉とを含み、還元鉄粉が鉄粉質量の５〜５０質量％であり、前記樹脂粉が熱可塑性ＰＩ及びＰＴＦＥ粉末で、これら樹脂粉の合計含有量が全質量の０.３質量％以下であることを特徴とする。
【０００８】
【発明の実施の形態】
以上の発明を実施の形態及び実施例により詳しく説明する。
まず、実験に使用した粉末、圧粉磁心試料の製作方法及び特性の測定方法は次の通りである。
１．鉄粉
（１）へガネス社製の表面に燐酸系の極薄い絶縁被膜が形成された粒度２００μｍ以下のアトマイズ鉄粉
（２）へガネス社製の表面に燐酸系の極薄い絶縁被膜が形成された粒度２００μｍ以下の還元鉄粉
２．樹脂粉末
（１）熱可塑性ＰＩ粉末：平均粒径２０μｍ
（２）ＰＴＦＥ粉末：平均粒径５μｍ
３．粉末成形
温度１００℃に加熱された成形金型の内面に成形潤滑剤粉末をアルコールに分散した液を塗布、乾燥し、加熱された混合粉を充填し、１５６０ＭＰａの圧力で圧縮成形した。
４．成形体の熱処理
熱可塑性ＰＩを含む成形体は、窒素ガス中の温度４００℃で１時間加熱した。
５．試料
熱処理体の内径及び端面を切削加工し、内径１０ｍｍ、外径２３ｍｍ、高さ１０ｍｍの円筒形状とした。
６．特性
（１）磁束密度（Ｔ）は、磁場８０００Ａ／ｍにおける測定値である。
（２）鉄損（ｋＷ／ｍ３）は、印加磁束密度０.２５Ｔ（テスラー）、周波数５ｋＨにおける測定値である。
（３）圧環強さ（ＭＰａ）は、ＪＩＳ Ｚ２５０７−１９７９「焼結含油軸受の圧環強さ試験方法」による。
（４）密度（Ｍｇ／ｍ３）は、ＪＩＳ Ｚ２５０５−１９７９「焼結金属材料の焼結密度試験方法」による。
【０００９】
この発明は、実験により得られた下記のような知見を応用している。
（１）アトマイズ鉄粉を用いた圧粉磁心が切削加工性に課題があるのは、アトマイズ鉄粉の粉末の比表面積が比較的小さいため、切削したとき鉄粉粒子の脱落が容易であるためと考えられる。
（２）還元鉄粉を用い、同様に製作した圧粉磁心を切削加工した加工面はきれいなものとなる。ただし、還元鉄粉を用いると、圧縮性が比較して悪いため、圧粉磁心の磁束密度が劣る。
（３）結合樹脂は、ＰＰＳや熱可塑性ＰＩを用いると密度が高く磁束密度の高い圧粉磁心となるが、より鉄粒子間の絶縁性が良く鉄損がより低いものは熱可塑性ＰＩである。
（４）結合樹脂の含有量が多いほど鉄損が低くなるが、全質量において０.３質量％を越えると高い密度が得られ難くなり、従って高い磁束密度が得られ難くなる。
【００１０】
このような知見をもとに、アトマイズ鉄粉と還元鉄粉の混合物とすると共に、結合樹脂の含有量との組合せにおいて、磁束密度、鉄損、切削加工性のそれぞれの好適な条件を実験結果をもとにして検討する。
以下、特性グラフにより説明する。図１から図４は、鉄粉としてアトマイズ鉄粉のみと、アトマイズ鉄粉と還元鉄粉の混合割合を変化させたもの、及び樹脂として熱可塑性ＰＩ粉末を用いて樹脂含有量を変化させた組合せで作られた圧粉磁心の各種特性を示したものである。
【００１１】
まず、図１は圧粉磁心の密度で、還元鉄粉の量が増加すると密度が低くなり、樹脂含有量が増加すると密度が低くなっている。
また、図２は圧粉磁心の磁束密度で、図１の密度と同様に、還元鉄粉の量が増加、及び樹脂含有量が増加すると磁束密度が低くなる。密度と磁束密度とは、樹脂量及び還元鉄粉の量にかかわらず、おおよそ相関関係にあり、密度７.５２Ｍｇ／ｍ３のとき磁束密度１.６０Ｔ、密度が７.５５Mｇ／ｍ３のとき磁束密度が１.７Ｔ、密度が７.６１Ｍｇ／ｍ３のとき磁束密度１.８Ｔとなっている。また、還元鉄粉が５０質量％以下において、樹脂含有量が０.１５質量％以下のとき磁束密度が１.８Ｔ以上、樹脂含有量が０.３質量％以下のとき磁束密度が１.６５Ｔ以上を示している。
これと比較する圧粉磁心として、鉄粉がアトマイズ鉄粉で、樹脂がＰＰＳで０.３質量％含有するものの場合、磁束密度が１.７Ｔ程度である。樹脂が熱可塑性ＰＩでは、図２の還元鉄粉の量が０質量％で樹脂量０.３質量％の磁束密度が１.７９Ｔであるから、樹脂が熱可塑性ＰＩの方が優れていることが分かる。
磁束密度の高い圧粉磁心を得るには、樹脂の含有量が少なく、還元鉄粉の含有量が少ないものとすればよいことが分かる。
【００１２】
次に、図３は圧粉磁心の鉄損で、還元鉄粉の含有量が増加すると鉄損が高くなる。一方、樹脂量が多いほど鉄損が低くなり好ましくなる。樹脂量は０.３質量％を越えて含有していても鉄損は僅かに低下するだけである。
また、より一層低い鉄損を目標にする場合は、図３から次の領域にすればよいことが分かる。例えば、鉄損が約３５００ｋＷ／ｍ３以下を得るには、還元鉄粉の量が１０質量％では樹脂含有量が約０.０８質量％以上、還元鉄粉の量が２０質量％では樹脂含有量が約０.１２５質量％以上、還元鉄粉の量が３０質量％では樹脂含有量が約０.１５質量％以上の領域にある含有量の組合せにすればよい。換言すると、鉄粉はアトマイズ鉄粉と還元鉄粉との混合物で還元鉄粉が鉄粉質量の３０質量％以下とし、そして、熱可塑性ＰＩは、全質量に占める含有量が０.３質量％以下で、且つ還元鉄粉量１０質量％のとき樹脂含有量０.０８質量％及び還元鉄粉量が３０質量％のとき樹脂含有量０.１５質量％である比例関係から求められる樹脂含有量より多い樹脂含有量にすることである。
【００１３】
図４は圧粉磁心の圧環強さである。還元鉄粉の含有量が増加すると圧環強さが向上する。
一方、樹脂含有量が多いと圧環強さが低くなる。
【００１４】
次に、旋盤により切削加工した圧粉磁心の外観を観察した結果は、還元鉄粉の含有量が５質量％以上で切削面が改善され、還元鉄粉が多くなるほど加工面がきれいになり欠け発生が無くなる。
【００１５】
以上の結果を取り纏めると次の通りである。
（１）アトマイズ鉄粉に還元鉄粉が混合されたものは、圧環強さが高く、切削加工による欠損がなくなり、還元鉄粉の量が５質量％以上で効果がある。
（２）樹脂粉は、熱可塑性ＰＩを用いると磁束密度が高いものとなる。
（３）磁束密度は、還元鉄粉量が５０質量％以下で、樹脂含有量が０.１５質量％以下のとき、磁束密度を１.８Ｔ以上、樹脂含有量が０.３質量％以下のとき、磁束密度を１.６５Ｔ以上が得られる。後者の磁束密度は、アトマイズ鉄粉とＰＰＳからなる圧粉磁心より約３％程度低いが、還元鉄粉の含有によって切削加工性がよい特長を兼ね備えている。
（４）鉄損は、還元鉄粉の含有量が少なく、樹脂の含有量が多いものが低い値を示す。樹脂の含有量を０.３質量％より多くしても効果が伴わない。
（５）これらのことから、鉄粉がアトマイズ鉄粉及び還元鉄粉、樹脂が熱可塑性ＰＩであって、還元鉄粉が鉄粉質量の５〜５０質量％、熱可塑性ＰＩが全質量の０.３質量％以下となっていることを発明の範囲とする。
【００１６】
次に、前記の圧粉磁心より高い密度が得られ、鉄損が低い圧粉磁心について説明する。
混合粉を圧縮成形するときの鉄粉粒子同士の潤滑を改善すると高い密度を得ることが容易になり、磁束密度をより高いものとすることができる訳であるが、このような粉末成形潤滑剤としては雲母、黒鉛、二硫化モリブデン、ＰＴＦＥが知られているが、樹脂系材料のＰＴＦＥを選択する。
【００１７】
実験方法は、前述したアトマイズ鉄粉と還元鉄粉の両方及び熱可塑性ＰＩを含む圧粉磁心の熱可塑性ＰＩの含有量の半分をＰＴＦＥに置き換えた圧粉磁心を同様な手順と方法で製作して特性を調べ、ＰＴＦＥを含まないものと比較する。還元鉄粉の含有量を１０質量％及び３０質量％とし、樹脂含有量は０.１５質量％とした場合の結果を表１に示す。
【００１８】
ＰＴＦＥを含むと、混合粉の圧縮性が良くなり、密度が０．０１Ｍｇ／ｍ３高くなる結果、磁束密度が０．０２Ｔ高くなっている。換言すると、圧縮成形の圧力を低くする選択肢が増えることにもなる。また、鉄損が僅かに低くなっており、このことはＰＴＦＥが熱可塑性ＰＩと比較して絶縁性がよいことを表している。
前記の説明では、熱可塑性ＰＩとＰＴＦＥの割合は質量で１：１としたが、密度を高くし鉄損を低くする効果があるので例えば３：１としたり、１：３にすることができる。
【００１９】
【表１】
【発明の効果】
この発明によれば、圧粉磁心の切削加工性が良好なものであるから、複雑な形状或いは寸法精度が必要な圧粉磁心部品を切削加工して仕上げるような場合に特に好適であり、しかも高い磁束密度で鉄損の低いものを提供することができるので、圧粉磁心を用いた電磁部品の小型化や消費電力が少ない電磁製品を製作することができる。
【図面の簡単な説明】
【図１】還元鉄粉及び樹脂の含有量と密度の関係を示すグラフである。
【図２】還元鉄粉及び樹脂の含有量と磁束密度の関係を示すグラフである。
【図３】還元鉄粉及び樹脂の含有量と鉄損の関係を示すグラフである。
【図４】還元鉄粉及び樹脂の含有量と圧環強さの関係を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dust core.
[0002]
[Prior art]
It is known that a powder magnetic core in which magnetic particles are made of high-purity iron powder for a motor core or a transformer core has a relatively high magnetic flux density and low iron loss.
Such a powder magnetic core is made by compression-molding iron powder mixed with an insulating binder resin and heat-treating it, and may perform drilling or screwing.
Since the magnetic flux density depends on the density of the dust core, the iron powder used is an atomized iron powder that can obtain a higher density, and on the surface of this iron powder, in order to reduce the iron loss of the dust core, A phosphate compound coating is applied. Examples of such iron powder include the product name Somaloy 500 manufactured by Höganäs.
There are various proposals for resins such as thermosetting phenol, thermoplastic polyamide, epoxy, polyimide, polyphenylene sulfide (hereinafter referred to as PPS).
[0003]
[Problems to be solved by the invention]
Such a powder magnetic core has a relatively high frequency to be used, so that a higher magnetic flux density can be obtained and the iron loss is as low as possible. In addition, when a conventional dust core is subjected to a cutting process or a drilling process, it is a problem to be solved that a crack or a chip tends to occur.
[0004]
[Means for Solving the Problems]
As a result of repeated studies to solve these problems, the present invention has been completed by demonstrating that the above problems can be solved by devising the selection and addition amount of iron powder and binding resin.
[0005]
According to the first aspect of the present invention, in a powder magnetic core obtained by compression molding a mixture of iron powder and resin powder, the iron powder is atomized iron powder and reduced iron powder, and the resin powder is a thermoplastic polyimide resin (hereinafter, thermoplastic PI). It is characterized by being a powder, or a thermoplastic PI and polytetrafluoroethylene (hereinafter referred to as PTFE) powder.
[0006]
According to a second aspect of the present invention, in the powder magnetic core obtained by compression molding a mixture of iron powder and resin powder, the iron powder includes atomized iron powder and reduced iron powder, and the reduced iron powder is 5 to 50 mass of the iron powder mass. The content of the resin powder in the total mass of the thermoplastic PI is 0.3% by mass or less.
[0007]
According to a third aspect of the present invention, in the powder magnetic core obtained by compression molding a mixture of iron powder and resin powder, the iron powder includes atomized iron powder and reduced iron powder, and the reduced iron powder is 5 to 50 mass of the iron powder mass. The resin powder is thermoplastic PI and PTFE powder, and the total content of these resin powders is 0.3% by mass or less of the total mass.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The above invention will be described in detail with reference to embodiments and examples.
First, the method of manufacturing the powder and powder magnetic core sample used in the experiment and the method of measuring the characteristics are as follows.
1. Iron powder (1) Phosphoric acid-based ultra-thin insulating film formed on the surface of Gunnes Co. Atomized iron powder (2) with a particle size of 200 µm or less Phosphoric acid-based ultra-thin insulating film is formed on the surface of Gunnes 1. Reduced iron powder having a particle size of 200 μm or less Resin powder (1) Thermoplastic PI powder:
(2) PTFE powder: average particle size 5 μm
3. A liquid obtained by dispersing a molding lubricant powder in alcohol was applied to the inner surface of a molding die heated to a powder molding temperature of 100 ° C., dried, filled with the heated mixed powder, and compression molded at a pressure of 1560 MPa.
4). Heat treatment of the molded body The molded body containing the thermoplastic PI was heated at a temperature of 400 ° C. in nitrogen gas for 1 hour.
5. The inner diameter and end face of the sample heat treatment body were cut into a cylindrical shape having an inner diameter of 10 mm, an outer diameter of 23 mm, and a height of 10 mm.
6). Characteristic (1) Magnetic flux density (T) is a measured value at a magnetic field of 8000 A / m.
(2) Iron loss (kW / m 3 ) is a measured value at an applied magnetic flux density of 0.25 T (Tessler) and a frequency of 5 kH.
(3) The crushing strength (MPa) is based on JIS Z2507-1979 “Method for testing crushing strength of sintered oil-impregnated bearing”.
(4) Density (Mg / m 3 ) is according to JIS Z2505-1979 “Sintered Density Test Method for Sintered Metal Material”.
[0009]
The present invention applies the following knowledge obtained through experiments.
(1) The reason why the powder magnetic core using atomized iron powder has a problem in cutting workability is that the specific surface area of the atomized iron powder is relatively small, so that the iron powder particles can be easily removed when cut. it is conceivable that.
(2) Using reduced iron powder, a machined surface obtained by cutting a similarly produced dust core is clean. However, when reduced iron powder is used, the compressibility is poor compared to the magnetic flux density of the dust core.
(3) When PPS or thermoplastic PI is used as the binder resin, it becomes a dust core having a high density and a high magnetic flux density. However, the one having better insulation between iron particles and lower iron loss is thermoplastic PI. .
(4) The iron loss decreases as the content of the binder resin increases. However, when the content exceeds 0.3% by mass in the total mass, it is difficult to obtain a high density, and thus it is difficult to obtain a high magnetic flux density.
[0010]
Based on such knowledge, the result of the experiment is a mixture of atomized iron powder and reduced iron powder and suitable conditions of magnetic flux density, iron loss, and machinability in combination with the content of binder resin. Consider based on.
Hereinafter, the characteristic graph will be described. 1 to FIG. 4 show only combinations of atomized iron powder as iron powder, a mixture ratio of atomized iron powder and reduced iron powder, and a resin content changed using thermoplastic PI powder as resin. This shows the various characteristics of the powder magnetic core made of
[0011]
First, FIG. 1 shows the density of the dust core. When the amount of reduced iron powder increases, the density decreases, and when the resin content increases, the density decreases.
FIG. 2 shows the magnetic flux density of the dust core. Similar to the density of FIG. 1, the magnetic flux density decreases as the amount of reduced iron powder increases and the resin content increases. The density and the magnetic flux density, regardless of the amount of the resin weight and the reduced iron powder, approximately located correlated, when the magnetic flux density 1.60T when density 7.52Mg / m 3, density of 7.55Mg / m 3 When the magnetic flux density is 1.7 T and the density is 7.61 Mg / m 3 , the magnetic flux density is 1.8 T. When the reduced iron powder is 50% by mass or less, the magnetic flux density is 1.8T or more when the resin content is 0.15% by mass or less, and the magnetic flux density is 1.65T when the resin content is 0.3% by mass or less. The above is shown.
As a powder magnetic core to be compared with this, when the iron powder is atomized iron powder and the resin contains PPS in an amount of 0.3% by mass, the magnetic flux density is about 1.7T. When the resin is thermoplastic PI, the amount of the reduced iron powder in FIG. 2 is 0% by mass and the magnetic flux density of the resin amount of 0.3% by mass is 1.79 T. Therefore, the resin is superior to the thermoplastic PI. I understand.
It can be seen that in order to obtain a dust core having a high magnetic flux density, the resin content is low and the reduced iron powder content is low.
[0012]
Next, FIG. 3 shows the iron loss of the dust core, and the iron loss increases as the content of the reduced iron powder increases. On the other hand, the higher the resin amount, the lower the iron loss, which is preferable. Even if the resin content exceeds 0.3% by mass, the iron loss is only slightly reduced.
In addition, it can be seen from FIG. 3 that the following region may be used when an even lower iron loss is targeted. For example, in order to obtain an iron loss of about 3500 kW / m 3 or less, the resin content is about 0.08 mass% or more when the amount of reduced iron powder is 10% by mass, and the resin content is about 20% by mass of reduced iron powder. If the amount is about 0.125% by mass or more and the amount of reduced iron powder is 30% by mass, the resin content may be a combination of contents in the region of about 0.15% by mass or more. In other words, the iron powder is a mixture of atomized iron powder and reduced iron powder, and the reduced iron powder is 30% by mass or less of the mass of the iron powder, and the thermoplastic PI has a total content of 0.3% by mass. Resin content calculated | required from the proportional relationship which is 0.08 mass% of resin content below when the amount of reduced iron powder is 10 mass% below, and resin content 0.15 mass% when the amount of reduced iron powder is 30 mass% It is to make more resin content.
[0013]
FIG. 4 shows the crushing strength of the dust core. When the content of the reduced iron powder is increased, the crushing strength is improved.
On the other hand, when the resin content is large, the crushing strength is lowered.
[0014]
Next, as a result of observing the appearance of the powder magnetic core cut by a lathe, the cutting surface was improved when the content of reduced iron powder was 5% by mass or more, and as the amount of reduced iron powder increased, the processed surface became clean and chipped. Disappears.
[0015]
The above results are summarized as follows.
(1) A mixture in which reduced iron powder is mixed with atomized iron powder has high crushing strength and is free from defects due to cutting, and is effective when the amount of reduced iron powder is 5% by mass or more.
(2) The resin powder has a high magnetic flux density when thermoplastic PI is used.
(3) When the amount of reduced iron powder is 50% by mass or less and the resin content is 0.15% by mass or less, the magnetic flux density is 1.8T or more and the resin content is 0.3% by mass or less. When the magnetic flux density is 1.65 T or more. The latter magnetic flux density is about 3% lower than the powder magnetic core made of atomized iron powder and PPS, but it also has the feature of good machinability due to the inclusion of reduced iron powder.
(4) The iron loss is low when the content of reduced iron powder is low and the content of resin is high. Even if the resin content is more than 0.3% by mass, the effect is not accompanied.
(5) From these, the iron powder is atomized iron powder and reduced iron powder, the resin is thermoplastic PI, the reduced iron powder is 5 to 50% by mass of the iron powder mass, and the thermoplastic PI is 0 of the total mass. It is within the scope of the invention to be less than 3 mass%.
[0016]
Next, a dust core having a higher density than that of the dust core and having a low iron loss will be described.
It is easy to obtain a high density and improve the magnetic flux density by improving the lubrication between the iron powder particles when the mixed powder is compression-molded. As mica, graphite, molybdenum disulfide, and PTFE are known, the resin-based material PTFE is selected.
[0017]
The experimental method is to manufacture a dust core in which the PTFE is replaced with half of the thermoplastic PI content of the dust core including both the atomized iron powder and the reduced iron powder and the thermoplastic PI described above in the same procedure and method. Then, the characteristics are examined and compared with those not containing PTFE. Table 1 shows the results when the content of the reduced iron powder is 10% by mass and 30% by mass, and the resin content is 0.15% by mass.
[0018]
When PTFE is included, the compressibility of the mixed powder is improved and the density is increased by 0.01 Mg / m 3. As a result, the magnetic flux density is increased by 0.02T. In other words, there are more options for lowering the pressure of compression molding. Also, the iron loss is slightly lower, which indicates that PTFE is better insulative than thermoplastic PI.
In the above description, the ratio of the thermoplastic PI and PTFE is 1: 1 by mass, but it has the effect of increasing the density and reducing the iron loss, so it can be set to, for example, 3: 1 or 1: 3. .
[0019]
[Table 1]
【The invention's effect】
According to the present invention, since the dust core has good cutting workability, it is particularly suitable for the case of cutting and finishing a dust core part that requires a complicated shape or dimensional accuracy. Since a high magnetic flux density and low iron loss can be provided, it is possible to reduce the size of an electromagnetic component using a dust core and to produce an electromagnetic product with low power consumption.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the content and density of reduced iron powder and resin.
FIG. 2 is a graph showing the relationship between the content of reduced iron powder and resin and the magnetic flux density.
FIG. 3 is a graph showing the relationship between the content of reduced iron powder and resin and the iron loss.
FIG. 4 is a graph showing the relationship between the content of reduced iron powder and resin and the crushing strength.
Claims (2)
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002229712A JP4284042B2 (en) | 2002-08-07 | 2002-08-07 | Dust core |
| US10/520,119 US20050265883A1 (en) | 2002-08-07 | 2003-07-09 | Dust ccre and process for producing the same |
| CNB038190877A CN100350519C (en) | 2002-08-07 | 2003-07-09 | Dust core and process for producing the same |
| EP03784478.4A EP1542242B1 (en) | 2002-08-07 | 2003-07-09 | Dust core and process for producing the same |
| PCT/JP2003/008730 WO2004015724A1 (en) | 2002-08-07 | 2003-07-09 | Dust core and process for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002229712A JP4284042B2 (en) | 2002-08-07 | 2002-08-07 | Dust core |
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| Publication Number | Publication Date |
|---|---|
| JP2004071860A JP2004071860A (en) | 2004-03-04 |
| JP4284042B2 true JP4284042B2 (en) | 2009-06-24 |
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| JP2002229712A Expired - Fee Related JP4284042B2 (en) | 2002-08-07 | 2002-08-07 | Dust core |
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| JP4850764B2 (en) * | 2007-03-19 | 2012-01-11 | 日立粉末冶金株式会社 | Manufacturing method of dust core |
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