JP3962450B2 - Inoculation filter and cast iron inoculation method - Google Patents

Description

【００３８】
【表２】

（注湯方案）
図１及び図２は本試験例に係る鋳型１の注湯方案を示す。本試験例では、鋳込み重量約３ｋｇｆに設定し、ねずみ鋳鉄（以下ＦＣともいう）の溶湯を、鋳型１に注湯した。同様に、球状黒鉛鋳鉄（以下ＦＣＤともいう）の溶湯も別の鋳型１に注湯した。
【００３９】
ＦＣの溶湯とＦＣＤの溶湯との成分を表３に示す。ＦＣＤの溶湯を得るにあたっては、鋳型１に注湯する前に、溶湯重量に対して１．５％の球状化剤をとりべの底に置き、その上部より溶湯を注入し、置き注ぎ方式により球状化処理を行った。
【００４０】
【表３】

なお球状黒鉛鋳鉄を球状化処理する球状化剤は、表４に示す組成のものを採用した。
【００４１】
【表４】

（試験条件）
次の表５及び表６に示すような接種条件に従い、接種フィルタ２を用いて溶湯を接種し、この溶湯を鋳型１の成形キャビティ１３に供給し、凝固させ、試験片を形成した。表５はねずみ鋳鉄の溶湯の接種条件を示す。表６は球状黒鉛鋳鉄の溶湯の接種条件を示す。接種剤（Ａ，Ｂ，Ｃ）の添加量は、溶湯の鋳込重量に対して、それぞれ０％、０．２５％、０．５％とした。添加量０％は『接種無し』を意味し、比較例となる。
【００４２】
以下において、接種剤Ａを添加したものは、ＦＣやＦＣＤの末尾に『Ａ』を付し、ＦＣＡ−１、ＦＣＡ−２、ＦＣＤＡ−１、ＦＣＤＡ−２のように示した。接種剤Ｂを添加したものは、ＦＣやＦＣＤの末尾に『Ｂ』を付し、ＦＣＢ−１、ＦＣＢ−２、ＦＣＤＢ−１、ＦＣＤＢ−２のように示した。接種剤Ｃを添加したものは、ＦＣやＦＣＤの末尾に『Ｃ』を付し、ＦＣＣ−１、ＦＣＣ−２、ＦＣＤＣ−１、ＦＣＤＣ−２のように示した。接種剤の添加量は表５に示されている。
【００４３】
接種剤で処理されていないものは、ＦＣやＦＣＤの末尾に『ＮＯ』を付し、ＦＣＮＯ１、ＦＣＮＯ２、ＦＣＤＮＯ１及びＦＣＤＮＯ２のように示した。
【００４４】
接種剤Ａと接種剤Ｂとを用いた試験では、注湯温度を１６６７Ｋとした。接種剤Ｃを用いた試験では注湯温度を１６３０Ｋとした。
【００４５】
【表５】

【００４６】
【表６】

（解析）
鋳型１の成形キャビティ１３で凝固したねずみ鋳鉄、球状黒鉛鋳鉄について、光学顕微鏡を用いて、共晶セル、黒鉛組成、基地組織等を観察した。更に、試験片に係る鋳鉄における反応生成物の化学成分を確認するため、ＥＰＭＡ定性分析を行った。鋳鉄の機械的性質については、丸棒試験片で引張試験を行い、引張強さと伸び率とを測定した。以下、［１］ねずみ鋳鉄、［２］球状黒鉛鋳鉄に分けて述べる。
［１］ねずみ鋳鉄について
（共晶セル）
接種フィルタ２を用いて鋳造したねずみ鋳鉄（ＦＣ）について、鋳造後の試験片を取り出し、研磨し、ステッド腐食液で腐食し、光学顕微鏡を用いて共晶セル組織を観察した。共晶セル数は、面算出法により測定した。共晶セル組織の観察結果を表７に示す。表７に示すように共晶セルの増加率（ｅｎｈａｎｃｅｍｅｎｔ ｒａｔｉｏ）は、接種剤無添加を基準とするものである（注湯温度が１６６７Ｋの場合にはＦＣＮＯ１、注湯温度が１６３０Ｋの場合にはＦＣＮＯ２）。
【００４７】
表７における共晶セルの増加率は、接種フィルタ２を用いた接種処理により、共晶セルサイズが細かくなった割合を意味する。表７から理解できるように、同一の接種剤に対しては、接種剤の添加量が多い場合には、共晶セルが細かくなっている。接種剤Ａ、接種剤Ｂを用いた試験片（ＦＣＡ−１、ＦＣＢ−１等）よりも、接種剤Ｃを用いた試験片（ＦＣＣ−１、ＦＣＣ−２）の共晶セル組織が細かかった。
【００４８】
【表７】

（黒鉛組織）
図５（Ａ）（Ｂ）はねずみ鋳鉄の黒鉛組織の顕微鏡観察写真を示す。図５（Ａ）は、接種剤Ａを被覆した接種フィルタ２を用いて接種処理したＦＣＡ−１の黒鉛組織を示す。図５（Ｂ）は、接種しないＦＣＮＯ１の黒鉛組織を示す。図５（Ｂ）に示すように、接種処理なしであるＦＣＮＯ１の場合には、黒鉛組織は微細なＤ型、Ｅ型黒鉛であった。しかし図５（Ａ）に示すように、接種剤Ａで接種処理したＦＣＡ−１の場合には、細かい黒鉛が消失し、黒鉛がほとんど均一な大きさで、方向性のないＡ型黒鉛になっていた。これは鋳物の機械的性質の向上において有利であると考えられる。
【００４９】
接種剤Ｂ、Ｃで接種した場合でも、同様に、接種により、細かい黒鉛が消失し、黒鉛がほとんど均一な大きさで、方向性のないＡ型黒鉛になっていた。
【００５０】
また、ＦＣＢー１では、接種フィルタ２の前方の湯道部分（＝before）と、接種フィルタ２の後方の湯道部分（＝after ）とについて、黒鉛組織を観察した。その結果を図６（Ａ）（Ｂ）に示す。図６（Ａ）は 接種フィルタ２の前方の湯道（＝before）の黒鉛組織を示す。図６（Ｂ）は 接種フィルタ２の後方の湯道（＝after ）の黒鉛組織を示す。図６（Ａ）に示すように、接種前の組織では、黒鉛は微細なＤ型、Ｅ型黒鉛であった。しかし図６（Ｂ）に示すように、接種後では、黒鉛がほとんど均一な大きさで、方向性のないＡ型黒鉛になっており、機械的性質の向上が期待できる。図６（Ａ）（Ｂ）の比較から理解できるように、接種フィルタ２を通過した鋳鉄では、接種効果により黒鉛組織の著しい改善が明らかとなった。
【００５１】
（基地組織）
５％ピクリン酸アルコ−ル溶液（ピクラル腐食液）で、試験片を腐食し、光学顕微鏡を用いてねずみ鋳鉄の基地組織を観察した。接種処理なしであるＦＣＮＯ１の組織では、オーステナイトと黒鉛が共晶として晶出する晶出黒鉛組織が存在していた。この組織には黒鉛とフェライトが析出している。この組織のものは抗張力ならびに弾性係数はＡ型黒鉛と同程度であるが、衝撃値と耐摩耗性が低いと推察される。
【００５２】
しかし接種剤Ｂで接種処理したＦＣＢ−１の場合には、微細な共晶組織が大幅に減少して黒鉛が均一となっている。故に衝撃値と耐摩耗性が高いと推察される。接種剤Ａ、Ｃで接種した鋳鉄についても、基本的には同様の結果が得られた。
【００５３】
（機械的性質）
図７はねずみ鋳鉄の引張試験の結果を示す。図７の縦軸は引張強度を示し、図７の横軸は試験片の番号を示す。図７によると、接種フィルタ２を用いていない鋳鉄（ＦＣＮＯ１、ＦＣＮＯ２）では、引張強度が低い。しかし、接種フィルタ２を用いた接種処理を行ったねずみ鋳鉄（ＦＣＡ−１、ＦＣＡ−２、ＦＣＢ−１、ＦＣＣ−１、ＦＣＣ−２）では、鋳鉄の引張強度がかなり増加している。これは前述したように黒鉛組織の改善によるものと考えられる。
［２］球状黒鉛鋳鉄について
（黒鉛組織）
図９（Ａ）（Ｂ）は球状黒鉛鋳鉄の球状黒鉛の分布状態を示す。図９（Ａ）は、接種剤Ｂを塗布した接種フィルタ２を用いて溶湯を接種処理した鋳鉄（ＦＣＤＢ−１）の黒鉛組織を示す。図９（Ｂ）は、接種フィルタ２を用いていない、つまり接種処理なしの鋳鉄（ＦＣＤＮＯ１）の黒鉛組織を示す。
【００５４】
接種処理なしの場合（ＦＣＤＮＯ１）には、微細黒鉛の他に多くの粗大黒鉛が分散しており、かなり不均一な黒鉛組織である。
【００５５】
一方、接種フィルタ２で接種処理した場合（ＦＣＤＢ−１）には、図９（Ａ）に示すように、微細黒鉛がほとんど消失し、かなり均一な大きさで、形状の良い球状黒鉛が分散している。
【００５６】
接種剤Ｂを用いた接種フィルタ２ばかりでなく、接種剤Ａ、接種剤Ｃを用いた接種フィルタ２の場合にも、黒鉛組織についてはほぼ同様な結果が得られた。
【００５７】
また画像解析装置を用い、黒鉛の平均径と黒鉛の形状係数ｆの分布とを測定した。形状係数とは、真円らしさを表現し、その値は０〜１までの数値で示され、形状係数が１のとき、完全な球状を意味する。この結果を表８及び図８に示した。図８の縦軸は、分散している黒鉛のうち、形状係数ｆが０．８を越える黒鉛の割合を示し、図８の横軸は試験片の種類を示す。
【００５８】
図８から理解できるように、接種剤Ａ〜Ｃで接種処理した球状黒鉛鋳鉄（ＦＣＤＡ−１、ＦＣＤＡ−２、ＦＣＤＢ−１、ＦＣＤＢ−２、ＦＣＤＣ−１、ＦＣＤＣ−２）では、形状係数が０．８を越える良好な球状黒鉛の割合が多かった。
【００５９】
一方、接種処理なしの球状黒鉛鋳鉄（ＦＣＤＮＯ１、ＦＣＤ
ＮＯ２）では、黒鉛の平均径の分布傾向をみると、平均径６．２５μｍ以下の微細黒鉛が多くなっていた。更に、接種処理なしの場合（ＦＣＤＮＯ１、ＦＣＤＮＯ２）には、図８から理解できるように、形状係数ｆが０．８以上の黒鉛の割合が低くなり、球状化不良の黒鉛が多くなっていることが明らかとなった。
【００６０】
【表８】

（機械的性質）
図１０は球状黒鉛鋳鉄の機械的性質を示す。図１０の縦軸は引張強度と伸びとを示し、横軸は試験片の種類を示す。図１０から理解できるように、球状黒鉛鋳鉄の引張強度は、接種処理していないＦＣＤＮＯ１、ＦＣＤＮＯ２がかなり高いが、伸びは必ずしも充分ではない。しかしながら、接種処理した場合には、多くの試験片において、伸びの向上が見られる。
【００６１】
さらにＣａ、Ａｌの他にＢａを含有する接種剤Ｂを用いた場合（ＦＣＤＢ−１、ＦＣＤＢ−２）には、伸びがかなり高い。接種剤Ｃを用いた球状黒鉛鋳鉄（ＦＣＤＣ−１）の場合においても、基本的には同様である。殊に、ＦＣＤＢ−１、ＦＣＤＢ−２の場合には、伸びは１４％以上である。これは黒鉛形状の改善及び黒鉛粒度分布の均一化によるものと考えられる。
【００６２】
［３］前フィルタ部２１及び後フィルタ部２２の併有効果
鋳造後に接種フィルタ２を鋳型１から取り出し、接種フィルタ２の内部を光学顕微鏡で観察した。更に、接種フィルタ２を構成する前フィルタ部２１と後フィルタ部２２との境界についても、光学顕微鏡で観察した。観察結果によると、前フィルタ部２１の表面に被覆していた接種剤は残留しておらず、従って、前フィルタ２１に被覆されていた実質的にすべての接種剤が溶湯との接種反応に寄与したものと推察される。
【００６３】
前記した前フィルタ部２１と後フィルタ部２２との境界にはケーキ層が生じていた。ケーキ層について、ＥＰＭＡ定性分析を行った。ＥＰＭＡ分析の結果によれば、ケーキ層はＡｌ、Ｃａ、Ｃ、Ｓｉ、Ｏ及びＳ等多くの元素を含有していた。即ち、接種処理により複雑な構造をもつ反応生成物が生成し、その反応生成物がケーキ層となり、成形キャビティ１３に流入することなく、後フィルタ部２２により捕獲されたものと考えられる。
【００６４】
ＥＰＭＡ定性分析によれば、反応生成物にはアルミ酸化物やシリコン酸化物が少なかった。このことから、前フィルタ部２１で接種処理した場合であっても、アルミ酸化物やシリコン酸化物があまり発生せず、従って接種剤の接種効率は高かったものと推察される。
【００６５】
以上の説明から理解できるように本実施例によれば、比表面積が大きい三次元網目構造をもつ接種フィルタ２における接種剤層と溶湯との接触頻度、接触面積が大きい。そのため、接種剤層と溶湯との反応効率が高くなり、溶湯における接種効果が向上する。よって、良好な鋳鉄材質を確保しつつ、接種剤の添加量を低減できる。
【００６６】
一定の粒度が要請される接種剤の製造工程においては、実際には使えない微小粉末の接種剤が残る。この微小粉末の接種剤は、一般的には廃棄したり、あるいは、再溶解のために回収したりしている。この場合には、コストがかかる。この点、接種フィルタ２を用いて溶湯を接種すれば、微小粉末の接種剤を、接種フィルタ製造用のスラリー原料として活用できる利点がある。
【００６７】
本実施例によれば、溶湯の鋳込が終了した時点において、前フィルタ部２１ではこれの接種剤層は消耗しているものの、後フィルタ部２２ばかりか、前フィルタ部２１の基体をなすセラミックスフォームが溶損せずに残存している。よって後フィルタ部２２による捕獲機能ばかりか、前フィルタ部２１のセラミックスフォームによる捕獲機能も確保され、接種反応で生成するドロスの捕獲性が確保される。
【００６８】
また図１及び図２から理解できるように、接種フィルタ２は、前方反応室１１ａに対面すると共に接種を主眼とする前フィルタ部２１と、接種で発生した反応生成物の捕獲除去を主眼とする後フィルタ部２２とからなる。そして、接種フィルタ２は、成形キャビティ１３の直前に設置している。故に、溶湯は前フィルタ部２１の接種剤と反応したら直ちに、或いは、反応しながら、後フィルタ部２２を通って成形キャビティ１３に充填される。よって、接種効果のフェーディング現象を防止するのに有利である。
【００６９】
更に本実施例では、図１、図２から理解できるように、接種フィルタ２の前方には通路断面積が大きな前方反応室１１ａが形成されている。そのため接種フィルタ２を通過する溶湯の速度を抑えることができ、従って溶湯と前フィルタ２１の接種剤層との接触時間が確保され、両者の接種反応を向上するのに有利である。
【００７０】
【発明の効果】
請求項１に係る接種フィルタによれば、前フィルタ部は、三次元網目構造をなす孔をもつフィルタ構造体の孔部分に三次元的に被覆された接種剤層をもつ。そのため、溶湯との接種反応に寄与する接種剤層の表面積が増大できる。
【００７１】
しかも前フィルタ部を通過する溶湯は、三次元的に曲がりつつ前フィルタ部を通過し易いため、溶湯が真っ直ぐに通過する場合に比較して、接種剤層と溶湯との接触頻度、ひいては両者の反応性が向上する。よって溶湯の接種効果が向上する。従って鋳鉄組織の改善、鋳鉄の機械的性質の改善に有利である。
【００７２】
請求項１に係る接種フィルタによれば、接種剤層は後フィルタ部よりも前フィルタ部に多く設けられているため、高温の溶湯を接種剤層に接触させるのに有利であり、接種効果の向上に有利である。
【００７３】
請求項１に係る接種フィルタによれば、前フィルタ部の接種剤層と溶湯との接種反応に基づく反応生成物に起因してドロスが溶湯に発生したとしても、そのドロスは後フィルタ部で捕獲され易い。よって鋳物へのドロス巻き込みを抑止するのに有利である。ドロスの巻き込みに起因する鋳鉄の機械的性質の低下を抑止するのに有利である。
【００７４】
請求項１に係る接種フィルタによれば、注湯開始前において、前フィルタ部の溶湯通過抵抗は、後フィルタ部の溶湯通過抵抗よりも大きく設定されている。そのため溶湯が前フィルタ部を通過する速度が過剰に速くなることは、抑制される。よって、前フィルタ部の接種剤と溶湯との接触時間が確保され、両者の反応性が向上し、溶湯の接種効果が向上し易い。従って鋳鉄組織の改善、鋳鉄の機械的性質の改善に有利である。
【００７５】
請求項２に係る鋳鉄溶湯接種方法によれば、接種フィルタの前フィルタ部はフィルタ構造体の孔部分に三次元的に被覆された接種剤層をもつため、溶湯との接種反応に寄与する接種剤層の表面積が増大している。しかも接種フィルタの前フィルタ部を通過する溶湯は、三次元的に曲がりつつ前フィルタ部を通過し易いため、溶湯が真っ直ぐに通過する場合に比較して、接種剤層と溶湯との接触頻度、ひいては両者の反応性が向上する。よって溶湯の接種効果が向上し易く、鋳鉄組織の改善、鋳鉄の機械的性質の改善に有利である。請求項２に係る鋳鉄溶湯接種方法によれば、接種剤層は後フィルタ部よりも前フィルタ部に多く設けられているため、高温の溶湯を接種剤層に接触させるのに有利であり、接種効果の向上に有利である。
【００７６】
更に、前フィルタ部の接種剤層と溶湯との接種反応に基づく反応生成物に起因してドロスが溶湯に発生したとしても、そのドロスは後フィルタ部で捕獲され易く、ドロスの混入の抑止に有利である。
【００７７】
請求項３に係る鋳鉄溶湯接種方法によれば、鋳型の成形キャビティへの溶湯供給の終了期に接種フィルタのフィルタ構造体を残存させる。そのため、特開平９−１９７４０号公報に係る技術とは異なり、溶湯供給工程における終了期、または終了期の近い時点においても、残存したフィルタ構造体による捕獲機能が維持される。従って接種処理の際に発生した反応生成物に起因するドロスが鋳型の成形キャビティに混入することを抑えるのに有利である。よってドロスに起因する鋳物の強度低下を防止するのに有利である。
【００７８】
請求項４に係る鋳鉄溶湯接種方法によれば、接種フィルタの前方には、接種フィルタと対面すると共に通路の他の部分よりも通路断面積が大きな反応室が設けられている。そのため、溶湯の速度は反応室で低下し易い。よって、反応室の溶湯と接種フィルタの接着剤層との接触時間が確保され、両者が反応し易い。よって溶湯の接種効果が向上し易く、鋳鉄組織の改善、鋳鉄の機械的性質の改善に有利である。
【図面の簡単な説明】
【図１】接種フィルタが配置された鋳型の縦断面図である。
【図２】接種フィルタが配置された鋳型の横断面図である。
【図３】接種フィルタの前フィルタ部に係り、スラリー被覆前と被覆後との粒子構造を示す写真でする。
【図４】被覆前のセラミックスフォームの粒子構造を模式的に示す斜視図である。
【図５】ねずみ鋳鉄の金属組織を示す顕微鏡写真である。
【図６】接種フィルタ前後に位置するねずみ鋳鉄の金属組織を示す顕微鏡写真である。
【図７】接種した試験片と接種していない試験片との引張強度を示すグラフである。
【図８】各試験片における形状係数が０．８を越える黒鉛の割合を示すグラフである。
【図９】接種した球状黒鉛鋳鉄と接種していない球状黒鉛鋳鉄との金属組織を示す顕微鏡写真である。
【図１０】接種した球状黒鉛鋳鉄と接種していない球状黒鉛鋳鉄との引張強度及び伸びを示すグラフである。
【図１１】従来技術に係る接種フィルタを鋳型に配置した状態を模式的に示す断面図である。
【符号の説明】
図中、１は鋳型、１０は溶湯口、１１は湯道（通路）、１３は成形キャビティ、２は接種フィルタ、２１は前フィルタ部、２２は後フィルタ部を示す。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inoculation filter and a cast iron melt inoculation method.
[0002]
[Prior art]
It is widely known that inoculation has great significance in the production of cast iron. For example, in gray cast iron, strength, machinability, etc. are improved by inoculation. Further, in spheroidal graphite cast iron, elongation and toughness are improved by reducing the chilling tendency and making the graphite grains uniform. However, there is a fading problem that the inoculation effect decreases with time. Here, considering the fading, it is preferable to inoculate the molten metal near the casting, that is, inside the mold.
[0003]
In view of the above points, Japanese Patent Laid-Open No. 9-19740 has conventionally disclosed a technique in which an inoculation filter 100 having a straight hole 101 extending in a straight line is formed from the inoculum itself, as shown in FIG. Yes. According to this publication technique, when the molten metal passing through the runner 201 of the mold 200 passes through the straight hole 101 of the inoculation filter 100, the molten metal reacts with the inoculum of the inoculation filter 100, and the molten metal is inoculated. In this case, since the inoculation filter 100 is disposed inside the mold 200, the molten metal immediately after the inoculation is supplied to the molding cavity of the mold 200, which is advantageous in improving the above-described fading problem.
[0004]
[Problems to be solved by the invention]
In the above-mentioned publication technique, since the inoculation filter 100 including the straight hole 101 is used, the contact frequency between the molten metal and the inoculum is low, and the inoculation effect of the molten metal is not always sufficient.
[0005]
Furthermore, the entire inoculation filter 100 is made of an inoculum, and is set so that the inoculation filter 100 disappears completely at the end of the molten metal supply process for supplying the molten metal to the mold. Therefore, as the end of the molten metal supply process approaches, the filter effect by the inoculation filter 100 cannot be expected, and the dross capturing effect is greatly reduced at the end. Therefore, there is a high possibility that dross is mixed into the molding cavity of the mold 200. Therefore, even if the material strength of the casting is increased by the inoculation effect, there is a possibility that the strength of the casting cannot be expected due to dross mixing.
[0006]
This invention is made | formed in view of the above-mentioned actual condition, The subject exists in providing the inoculation filter and cast iron molten metal inoculation method advantageous to provide the molten metal inoculation effect and the dross capture effect.
[0007]
[Means for Solving the Problems]
(1) Contract The inoculation filter according to claim 1 is
An inoculation filter composed of a filter structure having pores forming a three-dimensional network structure,
The front filter portion on the side close to the pouring port in the passage leading to the molding cavity of the mold and the rear filter portion adjacent to the filter portion in the passage of the mold and farther from the pouring port than the front filter portion. ,
The front filter part has a three-dimensionally coated inoculum layer in the pores of the filter structure, and the rear filter part has no inoculum layer or a smaller amount of inoculum layer than the front filter part. Also And ,
note Before the hot water starts, the molten metal passage resistance of the front filter portion is set to be larger than the molten metal passage resistance of the rear filter portion.
[0008]
Claim 2 The cast iron melt inoculation method according to claim 1 An arrangement step of arranging the inoculation filter according to 1 in the passage of the mold;
By pouring the molten metal from the pouring port of the mold, the molten metal is inoculated with the inoculant of the inoculation filter, and the molten metal supply step of supplying the inoculated molten metal to the molding cavity is performed.
[0009]
Claim 3 The cast iron melt inoculation method according to claim 2 The cast iron molten inoculation method described in 1) is characterized in that the filter structure of the inoculation filter is left at the end of the molten metal supply to the molding cavity of the mold in the molten metal supply step.
[0010]
Claim 4 The cast iron melt inoculation method according to claim 2 or 3 In the cast iron molten inoculation method according to claim 2, the passage of the mold is provided in front of the inoculation filter and has a reaction chamber that faces the inoculation filter and has a larger passage cross-sectional area than the other part of the passage. Is.
[0011]
Contract According to the inoculation filter according to claim 1, the front filter portion of the inoculation filter has an inoculum layer three-dimensionally coated on the hole portion of the filter structure. Therefore, the surface area of the inoculant layer contributing to the inoculation reaction with the molten metal is increased. Moreover, since the molten metal passing through the front filter part of the inoculation filter is easy to pass through the front filter part while bending three-dimensionally, compared to the case where the molten metal passes straight, the contact frequency between the inoculant layer and the molten metal, As a result, the reactivity of both improves.
[0012]
According to the inoculation filter according to claim 1, even if dross is generated in the molten metal due to a reaction product based on the inoculation reaction between the inoculant layer of the front filter portion and the molten metal, the dross is captured by the rear filter portion. It is easy to be done.
[0013]
Claim 1 According to the inoculation filter according to the above, before the start of pouring, the molten metal passage resistance of the front filter portion is set larger than the molten metal passage resistance of the rear filter portion. Therefore, it can suppress that the speed which a molten metal passes a front filter part becomes quick too much, the contact time of the inoculant and molten metal of a front filter part is ensured, and both reactivity is ensured.
[0014]
(2) Claim 2 According to the cast iron melt inoculation method according to the above, the front filter part of the inoculation filter has an inoculum layer three-dimensionally coated on the hole portion of the filter structure. Therefore, the surface area of the inoculant layer contributing to the inoculation reaction with the molten metal is increased. Moreover, since the molten metal passing through the front filter part of the inoculation filter is easy to pass through the front filter part while bending three-dimensionally, compared to the case where the molten metal passes straight, the contact frequency between the inoculant layer and the molten metal, As a result, the reactivity of both improves. Furthermore, even if dross is generated in the molten metal due to a reaction product based on the inoculation reaction between the inoculant layer of the front filter section and the molten metal, the dross is easily captured by the rear filter section.
[0015]
Claim 3 According to the cast iron melt inoculation method according to the above, the filter structure of the inoculation filter is left at the end of the melt supply to the molding cavity. Therefore, the dross capturing function by the inoculation filter is maintained even at the end of the molten metal supply or at a time close to the end.
[0016]
Claim 4 According to the cast iron melt inoculation method according to the above, the reaction chamber that faces the inoculation filter and has a larger passage cross-sectional area than other portions of the passage is provided in front of the inoculation filter. Therefore, the speed of the molten metal tends to decrease in the reaction chamber. Therefore, the contact time between the molten metal in the reaction chamber and the adhesive layer of the inoculation filter is secured, and both easily react.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The filter structure of the inoculation filter according to the present invention has holes that form a three-dimensional network structure. The filter structure can be generally formed of a ceramic foam. In this case, an organic porous body such as a resin that can be burned down by heating is used, and the organic porous body is heated and burned out in a state where the ceramic porous body is impregnated with the ceramic slurry. At the same time, it can be formed by leaving ceramics.
[0018]
The inoculation filter according to the present invention includes a front filter portion on the side close to the pouring port in the mold passage, and a rear filter portion on the side farther from the pouring port than the front filter portion provided adjacent to the front filter portion in the mold passage. It consists of and.
[0019]
For example, the ppi of the front filter unit can be smaller than the ppi of the rear filter unit. Specifically, the roughness of the front filter portion can be 5 to 40 ppi, particularly 10 to 25 ppi. The coarseness of the rear filter section can be 10 to 60 ppi, particularly 15 to 30 ppi. ppi means pores per inch, which is the number of holes per inch length.
[0020]
Before the start of pouring, the molten metal passage resistance of the front filter portion can be set larger than the molten metal passage resistance of the rear filter portion. If it does in this way, the time for a molten metal to pass through a front filter part will be ensured, and the contact time of the inoculant and molten metal of a front filter part, and also reaction time of both will be easy to be ensured.
[0021]
The molten metal passage resistance of the front filter part is set larger than the molten metal passage resistance of the rear filter part. For The porosity and the pore diameter of the front filter part can be made smaller than the porosity and the pore diameter of the rear filter part.
[0022]
As a typical inoculant constituting the inoculant layer of the inoculant filter, an Fe—Si alloy is preferable. The inoculant layer can contain at least one of barium, aluminum, lithium, calcium, strontium, rare earth elements, and carbon.
[0023]
The inoculation filter according to the present invention can be formed by a process including an operation of bringing a solution containing a powdery or granular inoculant into contact with the filter structure and an operation of drying the filter structure after the contact. In contacting, a method of applying the solution to the filter structure with a brush or spray, a method of immersing the filter structure in the solution, or the like can be adopted.
[0024]
The particle size of the inoculant constituting the inoculant layer can be appropriately selected according to the pore size of the filter structure, the casting method, the type of inoculant, etc., but generally the maximum value is 1 mm or less or 0.5 mm. The average value can be 0.75 mm or less, but is not limited thereto.
[0025]
The amount of the inoculum coated on the inoculation filter according to the present invention can be selected according to the type of molten metal, etc., but can be 0.1 to 0.4% by weight with respect to the amount of molten metal poured, or Although it can be made 0.05-0.5%, it is not limited to this.
[0026]
The molten metal inoculated by the inoculation filter may be a molten metal that requires inoculation treatment, and generally includes molten molten iron and spheroidal graphite cast iron.
[0027]
【Example】
Hereinafter, test examples according to examples of the present invention will be described together with comparative examples.
[0028]
(Inoculation filter)
Figure 1 shows a sand mold (CO ₂ A mold 1 made of a mold is shown. The mold 1 is composed of an upper mold 1X and a lower mold 1Y. The mold 1 has a molding cavity 13 connected to the runner 11 through a pouring gate 10, a runner 11 as a passage, and a weir 12. A filter installation part 14 is formed in the runner 11, and the inoculation filter 2 is installed in the filter installation part 14.
[0029]
A front reaction chamber 11 a having a passage cross-sectional area larger than that of the other part of the runner 11 is formed in front of the inoculation filter 2 in the runway 11. A rear reaction chamber 11c having a larger passage cross-sectional area than other portions is formed.
[0030]
The inoculation filter 2 includes a front filter portion 21 and a rear filter portion 22 that are stacked adjacent to each other.
[0031]
The front filter portion 21 is a ceramic foam filter made of alumina of about 10 ppi that functions as a filter structure, and the surface of the ceramic foam filter is covered with an inoculum layer. The rear filter portion 22 is an approximately 20 ppi alumina ceramic foam filter that functions as a filter structure. The rear filter part 22 is mainly intended to capture dross rather than inoculation, and unlike the front filter part 21, the inoculant layer is not substantially covered.
[0032]
FIG. 3 shows a photograph of the appearance of a ceramic foam filter that becomes the front filter portion 21. The left side of FIG. 3 shows the state before coating the slurry containing the inoculum. The right side of FIG. 3 shows the state after coating the slurry containing the inoculum.
[0033]
In the state after the ceramic foam filter is coated with the slurry containing the inoculum, the holes in the front filter portion 21 In The inoculating agent is clogged and the opening of the hole is crushed. Therefore, before the start of pouring, the molten metal passage resistance of the front filter portion 21 is larger than the molten metal passage resistance of the rear filter portion 22.
[0034]
FIG. 4 shows a schematic diagram of this ceramic foam filter. The ceramic foam filter 3 shown in FIG. 4 has a three-dimensional network structure and has a three-dimensional hole 30. Unlike the straight hole 101 extending linearly as shown in FIG. 11, the hole 30 of the ceramic foam filter 3 is bent three-dimensionally. The hole 30 is a communication hole that communicates the front portion 3 a and the back portion 3 b of the ceramic foam filter 3.
[0035]
The front filter part 21 was manufactured as follows. That is, by using an inoculant slurry in which a powdered inoculant is dispersed in a solvent, the inoculant slurry is coated on the ceramic foam filter 3 by impregnating the inside of the ceramic foam filter 3 with the inoculant slurry. Dried at an appropriate temperature (for example, about 473K).
[0036]
(Inoculum)
There are three types of inoculums (A, B, C) used in this test example. Table 1 shows the composition of the inoculants A to C, and Table 2 shows the particle size distribution of the inoculants A to C. As can be understood from Table 1, Ba is added in addition to Ca and Al in order to increase the inoculation effect in the inoculants B and C. As shown in Table 2, the size of the particle size is inoculum A <inoculum B <inoculum C.
[0037]
[Table 1]

[0038]
[Table 2]

(Pouring method)
FIG.1 and FIG.2 shows the pouring method of the casting_mold | template 1 which concerns on this test example. In this test example, the cast weight was set to about 3 kgf, and a molten cast iron (hereinafter also referred to as FC) was poured into the mold 1. Similarly, a melt of spheroidal graphite cast iron (hereinafter also referred to as FCD) was poured into another mold 1.
[0039]
Table 3 shows the components of the FC melt and the FCD melt. In order to obtain the molten FCD, before pouring into the mold 1, 1.5% of the spheroidizing agent is placed on the bottom of the ladle, and the molten metal is injected from the top of the ladle. Spheroidization treatment was performed.
[0040]
[Table 3]

As a spheroidizing agent for spheroidizing the spheroidal graphite cast iron, the composition shown in Table 4 was adopted.
[0041]
[Table 4]

(Test conditions)
In accordance with the inoculation conditions as shown in the following Table 5 and Table 6, the molten metal was inoculated using the inoculation filter 2, and this molten metal was supplied to the molding cavity 13 of the mold 1 and solidified to form a test piece. Table 5 shows the inoculation conditions for the molten gray cast iron. Table 6 shows the conditions for inoculating molten metal of spheroidal graphite cast iron. The addition amount of the inoculants (A, B, C) was 0%, 0.25%, and 0.5%, respectively, with respect to the casting weight of the molten metal. An added amount of 0% means “no inoculation” and is a comparative example.
[0042]
In the following, the inoculum A was added with “A” at the end of FC or FCD, and indicated as FCA-1, FCA-2, FCDA-1, FCDA-2. Those to which inoculum B was added were indicated by FCB-1, FCB-2, FCDB-1, and FCDB-2 with “B” at the end of FC or FCD. Those added with the inoculum C were marked with “C” at the end of the FC or FCD, such as FCC-1, FCC-2, FCDC-1, FCDC-2. The amount of inoculum added is shown in Table 5.
[0043]
Those not treated with the inoculum were marked with "NO" at the end of the FC or FCD, such as FCNO1, FCNO2, FCDNO1, and FCDNO2.
[0044]
In the test using inoculum A and inoculum B, the pouring temperature was set to 1667K. In the test using the inoculum C, the pouring temperature was 1630K.
[0045]
[Table 5]

[0046]
[Table 6]

(analysis)
For the gray cast iron and spheroidal graphite cast iron solidified in the molding cavity 13 of the mold 1, the eutectic cell, the graphite composition, the matrix structure, etc. were observed using an optical microscope. Furthermore, in order to confirm the chemical component of the reaction product in the cast iron according to the test piece, EPMA qualitative analysis was performed. About the mechanical property of cast iron, the tensile test was done with the round bar test piece, and the tensile strength and elongation rate were measured. Less than, [1] Gray cast iron, [2] It is divided into spheroidal graphite cast iron.
[1] About gray cast iron
(Eutectic cell)
For the gray cast iron (FC) cast using the inoculation filter 2, the test piece after casting was taken out, polished, corroded with a Sted corrosive solution, and the eutectic cell structure was observed using an optical microscope. The number of eutectic cells was measured by a surface calculation method. Table 7 shows the observation results of the eutectic cell structure. As shown in Table 7, the eutectic cell increase rate is based on the addition of no inoculum (FCNO1 when the pouring temperature is 1667K, and 1630K when the pouring temperature is 1630K). FCNO2).
[0047]
The increase rate of the eutectic cell in Table 7 means the rate at which the eutectic cell size is reduced by the inoculation process using the inoculation filter 2. As can be understood from Table 7, for the same inoculum, the eutectic cell is fine when the amount of the inoculum added is large. The eutectic cell structure of the test piece (FCC-1, FCC-2) using the inoculum C is finer than the test piece (FCA-1, FCB-1, etc.) using the inoculum A, B. It was.
[0048]
[Table 7]

(Graphite structure)
5 (A) and 5 (B) show micrographs of the graphite structure of gray cast iron. FIG. 5 (A) shows the graphite structure of FCA-1 inoculated with the inoculation filter 2 coated with the inoculum A. FIG. 5 (B) shows the graphite structure of FCNO1 that is not inoculated. As shown in FIG. 5 (B), in the case of FCNO1 without inoculation treatment, the graphite structure was fine D-type and E-type graphite. However, as shown in FIG. 5 (A), in the case of FCA-1 inoculated with inoculant A, fine graphite disappears, and graphite is almost uniform in size and becomes non-directional A-type graphite. It was. This is believed to be advantageous in improving the mechanical properties of the casting.
[0049]
Even when inoculated with the inoculums B and C, the fine graphite disappeared by the inoculation, and the graphite was almost uniform in size and became non-directional A-type graphite.
[0050]
In FCB-1, the graphite structure was observed in the runner part (= before) in front of the inoculation filter 2 and the runner part (= after) in the rear of the inoculation filter 2. The results are shown in FIGS. 6 (A) and 6 (B). FIG. 6A shows the graphite structure of the runner (= before) in front of the inoculation filter 2. FIG. 6B shows the graphite structure of the runner (= after) behind the inoculation filter 2. As shown in FIG. 6 (A), in the structure before inoculation, the graphite was fine D-type and E-type graphite. However, as shown in FIG. 6 (B), after inoculation, the graphite is almost uniform in size and becomes A-type graphite having no directionality, and improvement in mechanical properties can be expected. As can be understood from the comparison between FIGS. 6 (A) and 6 (B), in the cast iron that has passed through the inoculation filter 2, a remarkable improvement in the graphite structure was revealed by the inoculation effect.
[0051]
(Base organization)
The specimen was corroded with a 5% picric acid alcohol solution (picral corrosive solution), and the base structure of gray cast iron was observed using an optical microscope. In the structure of FCNO1 without inoculation treatment, there was a crystallized graphite structure in which austenite and graphite crystallized as eutectic. Graphite and ferrite are precipitated in this structure. This structure has the same tensile strength and elastic modulus as A-type graphite, but is presumed to have low impact value and wear resistance.
[0052]
However, in the case of FCB-1 inoculated with inoculum B, the fine eutectic structure is greatly reduced and the graphite is uniform. Therefore, it is assumed that the impact value and wear resistance are high. The same results were basically obtained for cast iron inoculated with inoculants A and C.
[0053]
(mechanical nature)
FIG. 7 shows the results of a tensile test of gray cast iron. The vertical axis in FIG. 7 indicates the tensile strength, and the horizontal axis in FIG. 7 indicates the number of the test piece. According to FIG. 7, the cast iron (FCNO1, FCNO2) not using the inoculation filter 2 has a low tensile strength. However, in the cast iron (FCA-1, FCA-2, FCB-1, FCC-1, FCC-2) subjected to the inoculation process using the inoculation filter 2, the tensile strength of the cast iron is considerably increased. As described above, this is considered to be due to the improvement of the graphite structure.
[2] About Spheroidal Graphite Cast Iron
(Graphite structure)
9A and 9B show the distribution of spheroidal graphite in spheroidal graphite cast iron. FIG. 9A shows a graphite structure of cast iron (FCDB-1) inoculated with molten metal using the inoculant filter 2 coated with the inoculant B. FIG. 9B shows a graphite structure of cast iron (FCDNO1) without using the inoculation filter 2, that is, without inoculation treatment.
[0054]
In the case of no inoculation treatment (FCDNO1), a large amount of coarse graphite is dispersed in addition to fine graphite, and a fairly non-uniform graphite structure.
[0055]
On the other hand, when the inoculation process is performed with the inoculation filter 2 (FCDB-1), as shown in FIG. 9A, the fine graphite almost disappears, and the spherical graphite having a good uniform shape is dispersed. ing.
[0056]
In the case of not only the inoculation filter 2 using the inoculant B but also the inoculant filter 2 using the inoculant A and inoculant C, almost the same results were obtained for the graphite structure.
[0057]
Further, the average diameter of graphite and the distribution of the shape factor f of graphite were measured using an image analysis apparatus. The shape factor expresses the true circularity, and the value is represented by a numerical value from 0 to 1. When the shape factor is 1, it means a perfect sphere. The results are shown in Table 8 and FIG. The vertical axis in FIG. 8 indicates the proportion of graphite in which the shape factor f exceeds 0.8 among the dispersed graphite, and the horizontal axis in FIG. 8 indicates the type of test piece.
[0058]
As can be understood from FIG. 8, in the spheroidal graphite cast iron (FCDA-1, FCDA-2, FCDB-1, FCDB-2, FCDC-1, FCDC-2) inoculated with the inoculums A to C, the shape factor is There were many proportions of good spheroidal graphite exceeding 0.8.
[0059]
On the other hand, spheroidal graphite cast iron without inoculation treatment (FCDNO1, FCD
In NO2), when the distribution tendency of the average diameter of graphite was observed, fine graphite having an average diameter of 6.25 μm or less was increased. Further, in the case of no inoculation treatment (FCDNO1, FCDNO2), as can be understood from FIG. 8, the ratio of graphite having a shape factor f of 0.8 or more is low, and the graphite with poor spheroidization is increased. Became clear.
[0060]
[Table 8]

(mechanical nature)
FIG. 10 shows the mechanical properties of spheroidal graphite cast iron. The vertical axis in FIG. 10 indicates tensile strength and elongation, and the horizontal axis indicates the type of test piece. As can be understood from FIG. 10, the tensile strength of spheroidal graphite cast iron is considerably high in FCDNO1 and FCDNO2 which are not inoculated, but the elongation is not always sufficient. However, when the inoculation treatment is performed, an improvement in elongation is observed in many test pieces.
[0061]
Furthermore, when the inoculum B containing Ba in addition to Ca and Al (FCDB-1, FCDB-2) is used, the elongation is considerably high. The same applies to the case of spheroidal graphite cast iron (FCDC-1) using the inoculum C. In particular, in the case of FCDB-1 and FCDB-2, the elongation is 14% or more. This is thought to be due to the improvement of the graphite shape and the homogenization of the graphite particle size distribution.
[0062]
[3] Combined effect of the front filter part 21 and the rear filter part 22
After casting, the inoculation filter 2 was taken out from the mold 1 and the inside of the inoculation filter 2 was observed with an optical microscope. Furthermore, the boundary between the front filter portion 21 and the rear filter portion 22 constituting the inoculation filter 2 was also observed with an optical microscope. According to the observation result, the inoculum coated on the surface of the front filter portion 21 does not remain, and therefore substantially all the inoculum coated on the front filter 21 contributes to the inoculation reaction with the molten metal. It is presumed that
[0063]
A cake layer was formed at the boundary between the front filter portion 21 and the rear filter portion 22 described above. EPMA qualitative analysis was performed on the cake layer. According to the result of EPMA analysis, the cake layer contained many elements such as Al, Ca, C, Si, O and S. That is, it is considered that a reaction product having a complicated structure is generated by the inoculation process, and the reaction product becomes a cake layer and is captured by the rear filter unit 22 without flowing into the molding cavity 13.
[0064]
According to the qualitative analysis of EPMA, the reaction products contained less aluminum oxide and silicon oxide. From this, even when the inoculation process is performed in the front filter part 21, it is presumed that aluminum oxide and silicon oxide are not generated so much and thus the inoculation efficiency of the inoculum is high.
[0065]
As can be understood from the above description, according to this embodiment, the contact frequency and contact area between the inoculum layer and the molten metal in the inoculation filter 2 having a three-dimensional network structure with a large specific surface area are large. Therefore, the reaction efficiency between the inoculant layer and the molten metal is increased, and the inoculation effect in the molten metal is improved. Therefore, the amount of inoculum added can be reduced while securing a good cast iron material.
[0066]
In the manufacturing process of an inoculum that requires a certain particle size, a micro-powder inoculum that cannot actually be used remains. This fine powder inoculum is generally discarded or recovered for re-dissolution. In this case, a cost is required. In this regard, if the molten metal is inoculated using the inoculation filter 2, there is an advantage that the fine powder inoculum can be used as a slurry raw material for producing the inoculation filter.
[0067]
According to the present embodiment, when the casting of the molten metal is finished, the inoculum layer of the front filter portion 21 is consumed, but not only the rear filter portion 22 but also the ceramics forming the base of the front filter portion 21. The foam remains without melting. Therefore, not only the capture function by the rear filter part 22 but also the capture function by the ceramic foam of the front filter part 21 is ensured, and the capture property of the dross generated by the inoculation reaction is ensured.
[0068]
As can be understood from FIGS. 1 and 2, the inoculation filter 2 faces the front reaction chamber 11 a and mainly focuses on the front filter portion 21 mainly for inoculation and capture and removal of reaction products generated by the inoculation. The rear filter unit 22 is included. The inoculation filter 2 is installed immediately before the molding cavity 13. Therefore, the molten metal is filled into the molding cavity 13 through the rear filter portion 22 immediately or while reacting with the inoculum of the front filter portion 21. Therefore, it is advantageous for preventing the fading phenomenon of the inoculation effect.
[0069]
Further, in this embodiment, as can be understood from FIGS. 1 and 2, a front reaction chamber 11 a having a large passage cross-sectional area is formed in front of the inoculation filter 2. Therefore, the speed of the molten metal passing through the inoculation filter 2 can be suppressed, and therefore the contact time between the molten metal and the inoculant layer of the front filter 21 is ensured, which is advantageous in improving the inoculation reaction between the two.
[0070]
【The invention's effect】
According to the inoculum filter of the first aspect, the front filter portion has the inoculum layer that is three-dimensionally coated on the hole portion of the filter structure having holes that form a three-dimensional network structure. Therefore, the surface area of the inoculant layer contributing to the inoculation reaction with the molten metal can be increased.
[0071]
Moreover, since the molten metal that passes through the front filter part is easy to pass through the front filter part while bending three-dimensionally, compared to the case where the molten metal passes straight, the contact frequency between the inoculum layer and the molten metal, and thus both The reactivity is improved. Therefore, the inoculation effect of the molten metal is improved. Therefore, it is advantageous for improvement of the cast iron structure and mechanical properties of the cast iron.
[0072]
According to the inoculation filter according to claim 1, since the inoculant layer is provided more in the front filter part than in the rear filter part, it is advantageous for bringing a high-temperature molten metal into contact with the inoculant layer. It is advantageous for improvement.
[0073]
According to the inoculation filter according to claim 1, even if dross is generated in the molten metal due to a reaction product based on the inoculation reaction between the inoculant layer of the front filter portion and the molten metal, the dross is captured by the rear filter portion. It is easy to be done. Therefore, it is advantageous in suppressing dross entrainment in the casting. This is advantageous in suppressing the deterioration of the mechanical properties of cast iron caused by dross entrainment.
[0074]
Claim 1 According to the inoculation filter according to the above, before the start of pouring, the molten metal passage resistance of the front filter portion is set larger than the molten metal passage resistance of the rear filter portion. Therefore, it is suppressed that the speed which a molten metal passes a front filter part becomes quick too much. Therefore, the contact time of the inoculant and molten metal of a front filter part is ensured, both reactivity improves, and the inoculation effect of molten metal tends to improve. Therefore, it is advantageous for improvement of the cast iron structure and mechanical properties of the cast iron.
[0075]
Claim 2 According to the cast iron melt inoculation method according to the present invention, since the front filter part of the inoculation filter has the inoculum layer three-dimensionally coated on the hole portion of the filter structure, the inoculum layer contributing to the inoculation reaction with the molten metal The surface area has increased. Moreover, since the molten metal passing through the front filter part of the inoculation filter is easy to pass through the front filter part while bending three-dimensionally, compared to the case where the molten metal passes straight, the contact frequency between the inoculant layer and the molten metal, As a result, the reactivity of both improves. Therefore, the inoculation effect of the molten metal is easily improved, which is advantageous for improving the cast iron structure and the mechanical properties of the cast iron. Claim 2 According to the cast iron melt inoculation method according to the present invention, since the inoculant layer is provided more in the front filter part than in the rear filter part, it is advantageous for bringing the hot melt into contact with the inoculant layer and improving the inoculation effect. Is advantageous.
[0076]
Furthermore, even if dross is generated in the molten metal due to a reaction product based on the inoculation reaction between the inoculant layer of the front filter section and the molten metal, the dross is easily captured by the rear filter section, which prevents the dross from being mixed. It is advantageous.
[0077]
Claim 3 According to the cast iron melt inoculation method according to the above, the filter structure of the inoculation filter is left at the end of the molten metal supply to the molding cavity of the mold. Therefore, unlike the technique according to Japanese Patent Laid-Open No. 9-19740, the capture function by the remaining filter structure is maintained even at the end of the molten metal supply process or at a time close to the end. Therefore, it is advantageous to suppress dross resulting from the reaction product generated during the inoculation process from being mixed into the molding cavity of the mold. Therefore, it is advantageous for preventing the strength reduction of the casting due to dross.
[0078]
Claim 4 According to the cast iron melt inoculation method according to the above, a reaction chamber that faces the inoculation filter and has a larger passage cross-sectional area than other portions of the passage is provided in front of the inoculation filter. Therefore, the speed of the molten metal tends to decrease in the reaction chamber. Therefore, the contact time between the molten metal in the reaction chamber and the adhesive layer of the inoculation filter is secured, and both easily react. Therefore, the inoculation effect of the molten metal is easily improved, which is advantageous for improving the cast iron structure and the mechanical properties of the cast iron.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a mold on which an inoculation filter is arranged.
FIG. 2 is a cross-sectional view of a mold in which an inoculation filter is arranged.
FIG. 3 is a photograph showing the particle structure before and after slurry coating, relating to the front filter part of the inoculation filter.
FIG. 4 is a perspective view schematically showing a particle structure of a ceramic foam before coating.
FIG. 5 is a photomicrograph showing the metal structure of gray cast iron.
FIG. 6 is a photomicrograph showing the metal structure of gray cast iron located before and after the inoculation filter.
FIG. 7 is a graph showing the tensile strength between the inoculated test piece and the non-inoculated test piece.
FIG. 8 is a graph showing the ratio of graphite having a shape factor exceeding 0.8 in each test piece.
FIG. 9 is a photomicrograph showing the metallographic structure of inoculated spheroidal graphite cast iron and non-inoculated spheroidal graphite cast iron.
FIG. 10 is a graph showing the tensile strength and elongation of inoculated spheroidal graphite cast iron and non-inoculated spheroidal graphite cast iron.
FIG. 11 is a cross-sectional view schematically showing a state in which an inoculation filter according to the prior art is arranged in a mold.
[Explanation of symbols]
In the figure, 1 is a mold, 10 is a molten metal inlet, 11 is a runner (passage), 13 is a molding cavity, 2 is an inoculation filter, 21 is a front filter part, and 22 is a rear filter part.

Claims (4)

An inoculation filter composed of a filter structure having pores forming a three-dimensional network structure,
A front filter portion on the side close to the pouring port in the passage connected to the molding cavity of the mold, and a rear filter portion on the side farther from the pouring port than the front filter portion provided adjacent to the front filter portion in the mold passage And consists of
The front filter portion has an inoculum layer three-dimensionally coated on the hole portion of the filter structure,
Or the rear filter unit has no inoculant layer, or Chi also a small amount of inoculant layer than the front filter unit, and,
Before the start of pouring , the inoculation filter is characterized in that the molten metal passage resistance of the front filter portion is set larger than the molten metal passage resistance of the rear filter portion . The inoculated filter mounting serial to claim 1 and arrangement step of arranging the passage of the mold,
A cast iron melt inoculation method for injecting molten metal with the inoculum of the inoculation filter by pouring molten metal from the pouring port of the mold and supplying the molten metal inoculated to the molding cavity of the mold . In the cast iron molten metal inoculation method of Claim 2 ,
A cast iron melt inoculation method, wherein the filter structure of the inoculation filter is left at the end of the melt supply to the molding cavity of the mold in the melt supply step. In the cast iron melt inoculation method according to claim 2 or 3 ,
Passage of the mold, cast iron inoculated method characterized by cross-sectional area than other portions of said passageway is provided with a large reaction chamber while facing the inoculated filter provided in front of the inoculum filter.

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