JP2004230498A - Cutting tool made of surface coated cemented carbide with hard coating layer exhibiting excellent chipping resistance in high-speed heavy cutting condition - Google Patents
Cutting tool made of surface coated cemented carbide with hard coating layer exhibiting excellent chipping resistance in high-speed heavy cutting condition Download PDFInfo
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【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層がすぐれた高温強度を有し、かつ高温硬さと耐酸化性にもすぐれ、したがって特に各種の鋼や鋳鉄などの切削加工を、高速で、かつ高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合に、硬質被覆層がすぐれた耐チッピング性を発揮する表面被覆超硬合金製切削工具（以下、被覆超硬工具という）に関するものである。
【０００２】
【従来の技術】
一般に、被覆超硬工具には、各種の鋼や鋳鉄などの被削材の旋削加工や平削り加工にバイトの先端部に着脱自在に取り付けて用いられるスローアウエイチップ、穴あけ切削加工などに用いられるドリルやミニチュアドリル、さらに切刃が断続切削加工形態をとる面削加工や溝加工、肩加工などに用いられるソリッドタイプのエンドミルなどがあり、また前記スローアウエイチップを着脱自在に取り付けて前記ソリッドタイプのエンドミルと同様に切削加工を行うスローアウエイエンドミル工具などが知られている。
【０００３】
また、被覆超硬工具として、炭化タングステン（以下、ＷＣで示す）基超硬合金または炭窒化チタン（以下、ＴｉＣＮで示す）基サーメットからなる基体（以下、これらを総称して超硬基体と云う）の表面に、組成式：（Ｔａ１−Ｘ ＢＸ ）Ｎ（ただし、原子比で、Ｘは０．４０〜０．６０を示す）を満足するＴａとＢの複合窒化物［以下、（Ｔａ，Ｂ）Ｎで示す］層からなる硬質被覆層を０．５〜１０μｍの平均層厚で物理蒸着してなる被覆超硬工具が提案され、特にこれら被覆超硬工具は、これの硬質被覆層がＴａ成分によるすぐれた高温強度、およびＢ成分によるすぐれた高温硬さと耐酸化性を具備することから、各種の鋼や鋳鉄などの連続切削や断続切削を高速加工条件で行なってもすぐれた切削性能を示すことが知られている（例えば特許文献１参照）。
【０００４】
さらに、上記の被覆超硬工具が、例えば図２に概略説明図で示される物理蒸着装置の１種であるアークイオンプレーティング装置に上記の超硬基体を装入し、ヒータで装置内を、例えば５００℃の温度に加熱した状態で、アノード電極と所定組成を有するＴａ−Ｂ合金がセットされたカソード電極（蒸発源）との間に、例えば電流：１５０Ａの条件でアーク放電を発生させ、同時に装置内に反応ガスとして窒素ガスを導入して、例えば２Ｐａの反応雰囲気とし、一方上記超硬基体には、例えば−１００Ｖのバイアス電圧を印加した条件で、前記超硬合金基体の表面に、上記（Ｔａ，Ｂ）Ｎ層からなる硬質被覆層を蒸着することにより製造されることも知られている。
【０００５】
【特許文献１】
特開平０６−０４１７６０号公報
【０００６】
【発明が解決しようとする課題】
近年の切削加工装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求は強く、これに伴い、切削加工は、高速で、かつ高切り込みや高送りなどの重切削条件で行なわれる傾向にあるが、上記の従来被覆超硬工具においては、これを高速切削加工条件で用いた場合には問題はないが、高速切削加工を高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合には、特に硬質被覆層の高温強度不足が原因でチッピング（微小割れ）が発生し易くなり、比較的短時間で使用寿命に至るのが現状である。
【０００７】
【課題を解決するための手段】
そこで、本発明者等は、上述のような観点から、特に高速重切削加工条件で硬質被覆層がすぐれた耐チッピング性を発揮する被覆超硬工具を開発すべく、上記の従来被覆超硬工具を構成する硬質被覆層に着目し、研究を行った結果、
（ａ）上記の図２に示されるアークイオンプレーティング装置を用いて形成された従来被覆超硬工具を構成する（Ｔａ，Ｂ）Ｎ層は、層厚全体に亘って実質的に均一な組成を有し、したがって均質な高温強度と、さらに高温硬さおよび耐酸化性を有するが、例えば図１（ａ）に概略平面図で、同（ｂ）に概略正面図で示される構造のアークイオンプレーティング装置、すなわち装置中央部に超硬基体装着用回転テーブルを設け、前記回転テーブルを挟んで、一方側に相対的にＢ含有量の高いＴａ−Ｂ合金、他方側に相対的にＢ含有量の低いＴａ−Ｂ合金をカソード電極（蒸発源）として対向配置したアークイオンプレーティング装置を用い、この装置の前記回転テーブル上の中心軸から半径方向に所定距離離れた位置に外周部に沿って複数の超硬基体をリング状に装着し、この状態で装置内雰囲気を窒素雰囲気として前記回転テーブルを回転させると共に、蒸着形成される硬質被覆層の層厚均一化を図る目的で超硬基体自体も自転させながら、前記の両側のカソード電極（蒸発源）とアノード電極との間にアーク放電を発生させて、前記超硬基体の表面に（Ｔａ，Ｂ）Ｎ層を形成すると、この結果の（Ｔａ，Ｂ）Ｎ層においては、回転テーブル上にリング状に配置された前記超硬基体が上記の一方側の相対的にＢ含有量の高いＴａ−Ｂ合金のカソード電極（蒸発源）に最も接近した時点で層中にＢ最高含有点が形成され、また前記超硬基体が上記の他方側の相対的にＢ含有量の低いＴａ−Ｂ合金のカソード電極に最も接近した時点で層中にＢ最低含有点が形成され、上記回転テーブルの回転によって層中には層厚方向にそって前記Ｂ最高含有点とＢ最低含有点が所定間隔をもって交互に繰り返し現れると共に、前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が連続的に変化する成分濃度分布構造をもつようになること。
【０００８】
（ｂ）上記（ａ）の繰り返し連続変化成分濃度分布構造の（Ｔａ，Ｂ）Ｎ層において、対向配置の一方側のカソード電極（蒸発源）である相対的にＢ含有量の高いＴａ−Ｂ合金におけるＢ含有量を上記の従来被覆超硬工具を構成する（Ｔａ，Ｂ）Ｎ層の形成に用いられたＴａ−Ｂ合金と同じＢ含有量とし、かつ同他方側のカソード電極（蒸発源）であるＴａ−Ｂ合金におけるＢ含有量を前記一方側のカソード電極であるＴａ−Ｂ合金のＢ含有量に比して相対的に低いものとする共に、超硬基体が装着されている回転テーブルの回転速度を制御して、
上記Ｂ最高含有点が、組成式：（Ｔａ１−Ｘ ＢＸ ）Ｎ（ただし、原子比で、Ｘは０．４０〜０．６０を示す）、
上記Ｂ最低含有点が、組成式：（Ｔａ１−Ｙ ＢＹ ）Ｎ（ただし、原子比で、Ｙは０．０５〜０．３０を示す）、
をそれぞれ満足し、かつ隣り合う上記Ｂ最高含有点とＢ最低含有点の厚さ方向の間隔を０．０１〜０．１μｍとすると、
上記Ｂ最高含有点部分では、上記の従来（Ｔａ，Ｂ）Ｎ層と同等のＢ含有量となることから、上記の従来硬質被覆層を構成する（Ｔａ，Ｂ）Ｎ層と同等のすぐれた高温硬さと耐酸化性を示し、一方上記Ｂ最低含有点部分では、前記Ｂ最高含有点部分に比してＢ含有量が低く、Ｔａ含有量の高いものとなるので、一段と高い高温強度が確保され、かつこれらＢ最高含有点とＢ最低含有点の間隔をきわめて小さくしたことから、層全体の特性としてすぐれた高温硬さと耐酸化性を保持した状態ですぐれた高温強度を具備するようになり、したがって、硬質被覆層がかかる構成の（Ｔａ，Ｂ）Ｎ層からなる被覆超硬工具は、各種の鋼や鋳鉄などの切削加工を、高速で、特に高い機械的衝撃を伴うので高い高温強度が要求される、高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング性を発揮するようになること。
以上（ａ）および（ｂ）に示される研究結果を得たのである。
【０００９】
この発明は、上記の研究結果に基づいてなされたものであって、超硬基体の表面に、（Ｔａ，Ｂ）Ｎ層からなる硬質被覆層を０．５〜１０μｍの全体平均層厚で物理蒸着してなる被覆超硬工具において、
上記硬質被覆層が、層厚方向にそって、Ｂ最高含有点とＢ最低含有点とが所定間隔をおいて交互に繰り返し存在し、かつ前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が連続的に変化する成分濃度分布構造を有し、
さらに、上記Ｂ最高含有点が、
組成式：（Ｔａ１−Ｘ ＢＸ ）Ｎ（ただし、原子比で、Ｘは０．４０〜０．６０を示す）、
上記Ｂ最低含有点が、
組成式：（Ｔａ１−Ｙ ＢＹ ）Ｎ（ただし、原子比で、Ｙは０．０５〜０．３０を示す）、
を満足し、かつ隣り合う上記Ｂ最高含有点とＢ最低含有点の間隔が、０．０１〜０．１μｍである、
高速重切削加工条件で硬質被覆層がすぐれた耐チッピング性を発揮する被覆超硬工具に特徴を有するものである。
【００１０】
つぎに、この発明の被覆超硬工具において、これを構成する硬質被覆層の構成を上記の通りに限定した理由を説明する。
（ａ）Ｂ最高含有点の組成
Ｂ最高含有点の（Ｔａ，Ｂ）ＮにおけるＴａ成分は、強度の向上に寄与し、一方Ｂ成分は高温硬さおよび耐酸化性（高温特性）を向上させる作用をもち、したがってＢ成分の含有割合が高くなればなるほど高温特性は向上したものになるが、Ｂの割合を示すＸ値がＴａとの合量に占める割合（原子比）で０．６０を越えて高くなると、高強度を有するＢ最低含有点が隣接して存在しても層自体の強度の低下は避けられず、この結果チッピングなどが発生し易くなり、一方同Ｘ値が同０．４０未満では前記高温特性に所望の向上効果が得られないことから、Ｂ最高含有点でのＢ成分の割合を示すＸ値を０．４０〜０．６０と定めた。
【００１１】
（ｂ）Ｂ最低含有点の組成
上記の通りＢ最高含有点は高温特性のすぐれたものであるが、反面強度の劣るものであるため、このＢ最高含有点の強度不足を補う目的で、相対的にＴａ含有割合が高く、これによって高強度を有するようになるＢ最低含有点を厚さ方向に交互に介在させるものであり、したがってＢの割合を示すＹ値がＴａとの合量に占める割合（原子比）で０．３０を越えると、所望のすぐれた強度を確保することができず、一方同Ｙ値が０．０５未満になると、相対的にＴａの割合が多くなり過ぎて、Ｂ最低含有点に所望の高温特性を具備せしめることができず、この結果層の摩耗が促進するようになることから、Ｂ最低含有点でのＢの割合を示すＹ値を０．０５〜０．３０と定めた。
【００１２】
（ｃ）Ｂ最高含有点とＢ最低含有点間の間隔
その間隔が０．０１μｍ未満ではそれぞれの点を上記の組成で明確に形成することが困難であり、この結果層に所望の高強度、さらに高温特性を確保することができなくなり、またその間隔が０．１μｍを越えるとそれぞれの点がもつ欠点、すなわちＢ最高含有点であれば強度不足、Ｂ最低含有点であれば高温特性不足が層内に局部的に現れ、これが原因で重切削条件では切刃にチッピングが発生し易くなったり、摩耗進行が促進されるようになることから、その間隔を０．０１〜０．１μｍと定めた。
【００１３】
（ｄ）硬質被覆層の全体平均層厚
その層厚が０．５μｍ未満では、所望の耐摩耗性を確保することができず、一方その平均層厚が１０μｍを越えると、チッピングが発生し易くなることから、その平均層厚を０．５〜１０μｍと定めた。
【００１４】
【発明の実施の形態】
つぎに、この発明の被覆超硬工具を実施例により具体的に説明する。
（実施例１）
原料粉末として、いずれも１〜３μｍの平均粒径を有するＷＣ粉末、ＴｉＣ粉末、ＶＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃｒ３ Ｃ２ 粉末、およびＣｏ粉末を用意し、これら原料粉末を、表１に示される配合組成に配合し、ボールミルで７２時間湿式混合し、乾燥した後、１００ＭＰａ の圧力で圧粉体にプレス成形し、この圧粉体を６Ｐａの真空中、温度：１４００℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０３のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１２０４０８のチップ形状をもったＷＣ基超硬合金製の超硬基体Ａ１〜Ａ１０を形成した。
【００１５】
また、原料粉末として、いずれも０．５〜２μｍの平均粒径を有するＴｉＣＮ（重量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ２ Ｃ粉末、ＺｒＣ粉末、ＮｂＣ粉末、ＴａＣ粉末、ＷＣ粉末、Ｃｏ粉末、およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで２４時間湿式混合し、乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を２ｋＰａの窒素雰囲気中、温度：１５００℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０３のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１２０４０８のチップ形状をもったＴｉＣＮ系サーメット製の超硬基体Ｂ１〜Ｂ６を形成した。
【００１６】
ついで、上記の超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６のそれぞれを、アセトン中で超音波洗浄し、乾燥した状態で、図１に示されるアークイオンプレーティング装置内の回転テーブル上の中心軸から半径方向に所定距離離れた位置に外周部にそって装着し、一方側のカソード電極（蒸発源）として、種々の成分組成をもったＢ最低含有点形成用Ｔａ−Ｂ合金、他方側のカソード電極（蒸発源）として、上記の従来（Ｔａ，Ｂ）Ｎ層形成に用いられたＴａ−Ｂ合金と同じ成分組成をもった種々のＢ最高含有点形成用Ｔａ−Ｂ合金を前記回転テーブルを挟んで対向配置し、またボンバート洗浄用金属Ｃｒも装着し、まず、装置内を排気して０．１Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、前記回転テーブル上で自転しながら回転する超硬基体に−１０００Ｖの直流バイアス電圧を印加し、カソード電極の前記金属Ｃｒとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＣｒボンバート洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して２Ｐａの反応雰囲気とすると共に、前記回転テーブル上で自転しながら回転する超硬基体に−１００Ｖの直流バイアス電圧を印加し、かつ前記Ｂ最低含有点形成用Ｔａ−Ｂ合金からなるカソード電極とアノード電極との間には１００Ａの電流、前記Ｂ最高含有点形成用Ｔａ−Ｂ合金のカソード電極とアノード電極との間には１５０Ａの電流をそれぞれ流してアーク放電を発生させ、もって前記超硬基体の表面に、層厚方向に沿って表３，４に示される目標組成のＢ最低含有点とＢ最高含有点とが交互に同じく表３，４に示される目標間隔で繰り返し存在し、かつ前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が連続的に変化する成分濃度分布構造を有し、かつ同じく表３，４に示される目標全体層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製スローアウエイチップ（以下、本発明被覆超硬チップと云う）１〜１６をそれぞれ製造した。
【００１７】
また、比較の目的で、これら超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６を、アセトン中で超音波洗浄し、乾燥した状態で、それぞれ図２に示される通常のアークイオンプレーティング装置に装入し、カソード電極（蒸発源）として上記の従来（Ｔａ，Ｂ）Ｎ層形成に用いられたＴａ−Ｂ合金と同じ成分組成をもった種々のＴａ−Ｂ合金を装着し、さらにボンバート洗浄用金属Ｃｒも装着し、まず、装置内を排気して０．１Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、前記超硬基体に−１０００Ｖの直流バイアス電圧を印加し、カソード電極の前記金属Ｃｒとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＣｒボンバート洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して２Ｐａの反応雰囲気とすると共に、超硬基体に−１００Ｖの直流バイアス電圧を印加し、前記カソード電極のＴａ−Ｂ合金とアノード電極との間に１５０Ａの電流を流してアーク放電を発生させ、もって前記超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６のそれぞれの表面に、表５，６に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔａ，Ｂ）Ｎ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製スローアウエイチップ（以下、従来被覆超硬チップと云う）１〜１６をそれぞれ製造した。
【００１８】
つぎに、上記本発明被覆超硬チップ１〜１６および従来被覆超硬チップ１〜１６について、これを工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、
被削材：ＪＩＳ・ＳＣＭ４４０の丸棒、
切削速度：３３０ｍ／ｍｉｎ．、
切り込み：３．５ｍｍ、
送り：０．１５ｍｍ／ｒｅｖ．、
切削時間：６分、
の条件での合金鋼の乾式連続高速高切り込み切削加工試験、
被削材：ＪＩＳ・ＳＵＳ３０４の長さ方向等間隔４本縦溝入り丸棒、
切削速度：２５０ｍ／ｍｉｎ．、
切り込み：１．０ｍｍ、
送り：０．４ｍｍ／ｒｅｖ．、
切削時間：３分、
の条件でのステンレス鋼の乾式断続高速高送り切削加工試験、さらに、
被削材：ＪＩＳ・Ｓ１５Ｃの長さ方向等間隔４本縦溝入り丸棒、
切削速度：３００ｍ／ｍｉｎ．、
切り込み：３．０ｍｍ、
送り：０．１ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での軟鋼の乾式断続高速高切り込み切削加工試験を行い、いずれの切削加工試験でも切刃の逃げ面摩耗幅を測定した。この測定結果を表３〜６に示した。
【００１９】
【表１】
【表２】
【表３】
【表４】
【表５】
【表６】
（実施例２）
原料粉末として、平均粒径：５．５μｍを有する中粗粒ＷＣ粉末、同０．８μｍの微粒ＷＣ粉末、同１．３μｍのＴａＣ粉末、同１．２μｍのＮｂＣ粉末、同１．２μｍのＺｒＣ粉末、同２．３μｍのＣｒ３Ｃ２粉末、同１．５μｍのＶＣ粉末、同１．０μｍの（Ｔｉ，Ｗ）Ｃ［質量比で、ＴｉＣ／ＷＣ＝５０／５０］粉末、および同１．８μｍのＣｏ粉末を用意し、これら原料粉末をそれぞれ表７に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、１００ＭＰａの圧力で所定形状の各種の圧粉体にプレス成形し、これらの圧粉体を、６Ｐａの真空雰囲気中、７℃／分の昇温速度で１３７０〜１４７０℃の範囲内の所定の温度に昇温し、この温度に１時間保持後、炉冷の条件で焼結して、直径が８ｍｍ、１３ｍｍ、および２６ｍｍの３種の超硬基体形成用丸棒焼結体を形成し、さらに前記の３種の丸棒焼結体から、研削加工にて、表７に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法、並びにいずれもねじれ角：３０度の４枚刃スクエアの形状をもった超硬基体（エンドミル）Ｃ−１〜Ｃ−８をそれぞれ製造した。
【００２６】
ついで、これらの超硬基体（エンドミル）Ｃ−１〜Ｃ−８を、アセトン中で超音波洗浄し、乾燥した状態で、同じく図１に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、層厚方向に沿って表８に示される目標組成のＢ最高含有点とＢ最低含有点とが交互に同じく表８に示される目標間隔で繰り返し存在し、かつ前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が連続的に変化する成分濃度分布構造を有し、かつ同じく表８に示される目標全体層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製エンドミル（以下、本発明被覆超硬エンドミルと云う）１〜８をそれぞれ製造した。
【００２７】
また、比較の目的で、上記の超硬基体（エンドミル）Ｃ−１〜Ｃ−８を、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表９に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔａ，Ｂ）Ｎ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製エンドミル（以下、従来被覆超硬エンドミルと云う）１〜８をそれぞれ製造した。
【００２８】
つぎに、上記本発明被覆超硬エンドミル１〜８および従来被覆超硬エンドミル１〜８のうち、本発明被覆超硬エンドミル１〜３および従来被覆超硬エンドミル１〜３については、
被削材：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・ＳＮＣＭ４３９の板材、
切削速度：２００ｍ／ｍｉｎ．、
溝深さ（切り込み）：８．０ｍｍ、
テーブル送り：１０００ｍｍ／分、
の条件での合金鋼の乾式高速高送り溝切削加工試験、本発明被覆超硬エンドミル４〜６および従来被覆超硬エンドミル４〜６については、
被削材：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・ＳＫＤ１１の板材、
切削速度：２５０ｍ／ｍｉｎ．、
溝深さ（切り込み）：６．０ｍｍ、
テーブル送り：５００ｍｍ／分、
の条件での工具鋼の乾式高速高切り込み溝切削加工試験、本発明被覆超硬エンドミル７，８および従来被覆超硬エンドミル７，８については、
被削材：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・Ｓ５０Ｃの板材、
切削速度：４００ｍ／ｍｉｎ．、
溝深さ（切り込み）：９．０ｍｍ、
テーブル送り：１５００ｍｍ／分、
の条件での炭素鋼の乾式高速高切り込みおよび高送り溝切削加工試験をそれぞれ行い、いずれの乾式溝切削加工試験でも切刃部の外周刃の逃げ面摩耗幅が使用寿命の目安とされる０．１ｍｍに至るまでの切削溝長を測定した。この測定結果を表８、９にそれぞれ示した。
【００２９】
【表７】
【表８】
【表９】
（実施例３）
上記の実施例２で製造した直径が８ｍｍ（超硬基体Ｃ−１〜Ｃ−３形成用）、１３ｍｍ（超硬基体Ｃ−４〜Ｃ−６形成用）、および２６ｍｍ（超硬基体Ｃ−７、Ｃ−８形成用）の３種の丸棒焼結体を用い、この３種の丸棒焼結体から、研削加工にて、溝形成部の直径×長さがそれぞれ４ｍｍ×１３ｍｍ（超硬基体Ｄ−１〜Ｄ−３）、８ｍｍ×２２ｍｍ（超硬基体Ｄ−４〜Ｄ−６）、および１６ｍｍ×４５ｍｍ（超硬基体Ｄ−７、Ｄ−８）の寸法、並びにいずれもねじれ角：３０度の２枚刃形状をもった超硬基体（ドリル）Ｄ−１〜Ｄ−８をそれぞれ製造した。
【００３３】
ついで、これらの超硬基体（ドリル）Ｄ−１〜Ｄ−８の切刃に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図１に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、層厚方向に沿って表１０に示される目標組成のＢ最高含有点とＢ最低含有点とが交互に同じく表１０に示される目標間隔で繰り返し存在し、かつ前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が連続的に変化する成分濃度分布構造を有し、かつ同じく表１０に示される目標全体層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製ドリル（以下、本発明被覆超硬ドリルと云う）１〜８をそれぞれ製造した。
【００３４】
また、比較の目的で、上記の超硬基体（ドリル）Ｄ−１〜Ｄ−８の切刃に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表１１に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔａ，Ｂ）Ｎ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製ドリル（以下、従来被覆超硬ドリルと云う）１〜８をそれぞれ製造した。
【００３５】
つぎに、上記本発明被覆超硬ドリル１〜８および従来被覆超硬ドリル１〜８のうち、本発明被覆超硬ドリル１〜３および従来被覆超硬ドリル１〜３については、
被削材：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・ＳＫＤ６１の板材、
切削速度：４５ｍ／ｍｉｎ．、
送り：０．１８ｍｍ／ｒｅｖ、
穴深さ：８ｍｍ
の条件での工具鋼の湿式高速高送り穴あけ切削加工試験、本発明被覆超硬ドリル４〜６および従来被覆超硬ドリル４〜６については、
被削材：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・ＦＣ４００の板材、
切削速度：１１０ｍ／ｍｉｎ．、
送り：０．３５ｍｍ／ｒｅｖ、
穴深さ：１６ｍｍ
の条件でのダクタイル鋳鉄の湿式高速高送り穴あけ切削加工試験、本発明被覆超硬ドリル７，８および従来被覆超硬ドリル７，８については、
被削材：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・ＦＣ３００の板材、
切削速度：１５０ｍ／ｍｉｎ．、
送り：０．４ｍｍ／ｒｅｖ、
穴深さ：３２ｍｍ
の条件での鋳鉄の湿式高速高送り穴あけ切削加工試験、をそれぞれ行い、いずれの湿式穴あけ切削加工試験（水溶性切削油使用）でも先端切刃面の逃げ面摩耗幅が０．３ｍｍに至るまでの穴あけ加工数を測定した。この測定結果を表１０、１１にそれぞれ示した。
【００３６】
【表１０】
【表１１】
この結果得られた本発明被覆超硬工具としての本発明被覆超硬チップ１〜１６、本発明被覆超硬エンドミル１〜８、および本発明被覆超硬ドリル１〜８を構成する硬質被覆層、並びに従来被覆超硬工具としての従来被覆超硬チップ１〜１６、従来被覆超硬エンドミル１〜８、および従来被覆超硬ドリル１〜８を構成する硬質被覆層について、厚さ方向に沿ってオージェ分光分析装置を用いてＴａおよびＢの含有量を測定した。これらの測定結果から、前記本発明被覆超硬工具の硬質被覆層では、厚さ方向に沿って目標組成と実質的に同じ組成を有するＢ最高含有点とＢ最低含有点とが目標間隔と実質的に同じ間隔で交互に存在し、かつ硬質被覆層の全体平均層厚も目標全体層厚と実質的に同じ値を示し、さらに前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が連続的に変化する成分濃度分布構造をもつことも確認された。一方前記従来被覆超硬工具の硬質被覆層においては、厚さ方向に沿って組成変化が見られず、かつ目標組成と実質的に同じ組成および目標全体層厚と実質的に同じ全体平均層厚を示すことが確認された。
【００３９】
【発明の効果】
表３〜１１に示される結果から、硬質被覆層が層厚方向に、すぐれた高温硬さと耐酸化性を有するＢ最高含有点と、高強度を有するＢ最低含有点とが交互に所定間隔をおいて繰り返し存在し、かつ前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が連続的に変化する成分濃度分布構造を有する本発明被覆超硬工具は、いずれも各種の鋼や鋳鉄などの切削加工を、高速で、かつ高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング性を発揮するのに対して、硬質被覆層が層厚方向に沿って実質的に組成変化のない（Ｔａ，Ｂ）Ｎ層からなる従来被覆超硬工具においては、前記硬質被覆層がすぐれた高温硬さと耐酸化性を有するものの、強度が不十分であるために、切刃部にチッピングが発生し、これが原因で比較的短時間で使用寿命に至ることが明らかである。
上述のように、この発明の被覆超硬工具は、特に各種の鋼や鋳鉄などの切削加工を、高速で、かつ高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、すぐれた耐チッピング性を発揮し、長期に亘ってすぐれた耐摩耗性を示すものであるから、切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。
【図面の簡単な説明】
【図１】この発明の被覆超硬工具を構成する硬質被覆層を形成するのに用いたアークイオンプレーティング装置を示し、（ａ）は概略平面図、（ｂ）は概略正面図である。
【図２】従来被覆超硬工具を構成する硬質被覆層を形成するのに用いた通常のアークイオンプレーティング装置の概略説明図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a hard coating layer having excellent high-temperature strength and excellent high-temperature hardness and oxidation resistance. Therefore, cutting of various steels and cast irons is particularly performed at high speed with high mechanical impact. The present invention relates to a surface-coated cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide tool) in which a hard coating layer exhibits excellent chipping resistance when performed under heavy cutting conditions such as high cutting and high feed.
[0002]
[Prior art]
In general, coated carbide tools are used for throw-away inserts, drilling, etc., which are removably attached to the tip of a cutting tool for turning or planing of various materials such as steel and cast iron. Drills and miniature drills, as well as solid-type end mills used for face milling, grooving, shoulder processing, etc., in which the cutting edge takes an intermittent cutting form, and the solid-type by detachably attaching the throw-away tip There is known a throw-away end mill tool for performing a cutting process in the same manner as the end mill.
[0003]
Further, as a coated cemented carbide tool, a substrate made of tungsten carbide (hereinafter, referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter, referred to as TiCN) -based cermet (hereinafter, collectively referred to as a cemented carbide substrate) ), A composite nitride of Ta and B satisfying the composition formula: (Ta 1−X B X ) N (where X represents 0.40 to 0.60 in atomic ratio) [hereinafter, ( Ta, B) N] coated hard carbide layer is formed by physical vapor deposition of a hard coating layer having an average layer thickness of 0.5 to 10 μm. Since the layer has excellent high-temperature strength due to the Ta component, and excellent high-temperature hardness and oxidation resistance due to the B component, it is excellent even when performing continuous or interrupted cutting of various steels or cast irons under high-speed machining conditions. It is known to show cutting performance (example Bas see Patent Document 1).
[0004]
Furthermore, the above-mentioned coated carbide tool is charged with the above-mentioned carbide substrate in an arc ion plating apparatus, which is a kind of physical vapor deposition apparatus shown schematically in FIG. 2, for example, and the inside of the apparatus is heated by a heater. For example, an arc discharge is generated between an anode electrode and a cathode electrode (evaporation source) on which a Ta-B alloy having a predetermined composition is set under a condition of, for example, a current of 150 A while being heated to a temperature of 500 ° C. At the same time, a nitrogen gas is introduced as a reaction gas into the apparatus, for example, to a reaction atmosphere of 2 Pa, while the cemented carbide substrate is subjected to, for example, a bias voltage of -100 V, on the surface of the cemented carbide substrate, It is also known to be manufactured by depositing a hard coating layer consisting of the (Ta, B) N layer.
[0005]
[Patent Document 1]
JP-A-06-041760
[Problems to be solved by the invention]
In recent years, the performance of cutting equipment has been remarkably improved, but on the other hand, there is a strong demand for labor saving, energy saving, and lower cost for cutting. However, in the above-mentioned conventional coated carbide tool, there is no problem when this is used under high-speed cutting conditions, but high-speed cutting is performed under high mechanical shock. Under heavy cutting conditions such as cutting and high feed, chipping (micro cracking) is likely to occur especially due to insufficient high-temperature strength of the hard coating layer, and the service life is relatively short. It is.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed the above-mentioned conventional coated cemented carbide tool in order to develop a coated cemented carbide tool in which the hard coating layer exhibits excellent chipping resistance especially under high-speed heavy cutting conditions. Focusing on the hard coating layer that constitutes
(A) The (Ta, B) N layer constituting the conventional coated carbide tool formed by using the arc ion plating apparatus shown in FIG. 2 described above has a substantially uniform composition over the entire layer thickness. Therefore, it has uniform high-temperature strength and high-temperature hardness and oxidation resistance. For example, arc ions having a structure shown in a schematic plan view in FIG. 1A and a schematic front view in FIG. A plating apparatus, that is, a rotating table for mounting a carbide substrate is provided at the center of the apparatus, and a Ta-B alloy having a relatively high B content on one side and a relatively B content on the other side with the rotating table interposed therebetween. An arc ion plating apparatus in which a small amount of a Ta-B alloy is disposed as a cathode electrode (evaporation source) is used, and is located along the outer periphery at a position radially away from a central axis on the rotary table of the apparatus. Multiple The hard base is mounted in a ring shape, and in this state, the rotary table is rotated while the atmosphere in the apparatus is a nitrogen atmosphere, and the super hard base itself is also rotated for the purpose of uniforming the thickness of the hard coating layer formed by vapor deposition. Meanwhile, an arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides to form a (Ta, B) N layer on the surface of the cemented carbide substrate. B) In the N layer, the cemented carbide substrate arranged in a ring shape on the turntable was closest to the Ta-B alloy cathode electrode (evaporation source) having a relatively high B content on the one side. At this point, a B maximum content point is formed in the layer, and when the cemented carbide substrate comes closest to the other side of the Ta-B alloy cathode electrode having a relatively low B content, the B minimum content is formed in the layer. The content point is formed and the rotary table The B maximum content point and the B minimum content point alternately and repeatedly appear at predetermined intervals in the layer along the layer thickness direction by rotation of the layer, and the B maximum content point and the B minimum content point from the B maximum content point From the above to the B maximum content point to have a component concentration distribution structure in which the B content continuously changes.
[0008]
(B) In the (Ta, B) N layer of the above-described (a) repeated continuous change component concentration distribution structure, Ta-B having a relatively high B content, which is a cathode electrode (evaporation source) on one side of the opposed arrangement. The B content of the alloy is the same as that of the Ta-B alloy used for forming the (Ta, B) N layer constituting the above-mentioned conventional coated carbide tool, and the cathode electrode (evaporation source) on the other side is used. ), The B content of the Ta-B alloy is relatively lower than the B content of the Ta-B alloy, which is the one-side cathode electrode, and the rotation of the Ta-B alloy on which the carbide substrate is mounted. By controlling the rotation speed of the table,
The B maximum content point, the composition formula: (Ta 1-X B X ) N ( provided that an atomic ratio, X is shows the 0.40 to 0.60),
The B minimum content point is determined by a composition formula: (Ta 1 -Y B Y ) N (however, in the atomic ratio, Y represents 0.05 to 0.30),
Each satisfying the above, and the interval in the thickness direction between the adjacent B highest content point and the B lowest content point is 0.01 to 0.1 μm
Since the B content is the same as that of the conventional (Ta, B) N layer, the B content is as high as the (Ta, B) N layer constituting the conventional hard coating layer. Shows high-temperature hardness and oxidation resistance. On the other hand, in the above-mentioned B lowest content portion, the B content is lower and the Ta content is higher than the B highest content portion, so that a higher high-temperature strength is secured. In addition, since the interval between the B highest content point and the B lowest content point is extremely small, the layer as a whole has excellent high temperature hardness while maintaining excellent high temperature hardness and oxidation resistance. Therefore, the coated carbide tool made of the (Ta, B) N layer having the hard coating layer can cut various kinds of steel and cast iron at a high speed, particularly with a high mechanical impact, and therefore has a high high-temperature strength. Is required, high infeed and high feed What if you made in heavy cutting conditions also be like exhibits chipping resistance of the hard coating layer has excellent.
The research results shown in (a) and (b) above were obtained.
[0009]
The present invention has been made based on the above-mentioned research results, and a hard coating layer composed of a (Ta, B) N layer is formed on a surface of a super-hard substrate at a total average layer thickness of 0.5 to 10 μm. In coated carbide tools made by evaporation,
In the hard coating layer, the B highest content point and the B lowest content point alternately and repeatedly exist at predetermined intervals along the layer thickness direction, and the B highest content point and the B lowest content point, A component concentration distribution structure in which the B content continuously changes from the lowest content point to the B highest content point,
Further, the B maximum content point is
Composition formula: (Ta 1-X B X ) N ( provided that an atomic ratio, X is shows the 0.40 to 0.60),
The B minimum content point is
Compositional formula: (Ta 1-Y B Y ) N (however, Y indicates 0.05 to 0.30 in atomic ratio),
And the interval between the adjacent B highest content point and B lowest content point is 0.01 to 0.1 μm,
The present invention is characterized by a coated carbide tool in which a hard coating layer exhibits excellent chipping resistance under high-speed heavy cutting conditions.
[0010]
Next, the reason why the configuration of the hard coating layer constituting the coated carbide tool of the present invention is limited as described above will be described.
(A) Composition of B highest content point The Ta component in (Ta, B) N having the highest content point of B contributes to improvement of strength, while B component improves high temperature hardness and oxidation resistance (high temperature properties). The higher the content of the B component, the higher the high-temperature characteristics. However, the ratio (atomic ratio) of the X value indicating the ratio of B to the total amount with Ta is 0.60. If it is higher than that, even if there is an adjacent B minimum content point having high strength, a decrease in the strength of the layer itself is unavoidable. If it is less than 40, a desired improvement effect cannot be obtained in the high-temperature characteristics. Therefore, the X value indicating the ratio of the B component at the B maximum content point is set to 0.40 to 0.60.
[0011]
(B) Composition of B minimum content point As described above, the B maximum content point is excellent in high-temperature properties, but is inferior in strength, but in order to compensate for the insufficient strength of the B maximum content point, In this case, the lowest B content point, which has a high Ta content ratio and thereby has a high strength, is alternately interposed in the thickness direction. Therefore, the Y value indicating the B content occupies the total amount with Ta. If the ratio (atomic ratio) exceeds 0.30, desired excellent strength cannot be ensured. On the other hand, if the Y value is less than 0.05, the proportion of Ta relatively increases too much. Since the desired high-temperature property cannot be provided at the B minimum content point, and the wear of the layer is accelerated as a result, the Y value indicating the proportion of B at the B minimum content point is set to 0.05 to 0. .30.
[0012]
(C) Interval between the B-highest content point and the B-lowest content point If the interval is less than 0.01 μm, it is difficult to clearly form each point with the above composition. Further, high-temperature characteristics cannot be ensured, and when the interval exceeds 0.1 μm, the disadvantages of the respective points, that is, insufficient strength at the highest B content point and insufficient high-temperature characteristics at the lowest B content point. Locally appearing in the layer, chipping is likely to occur on the cutting edge under heavy cutting conditions due to this, and the progress of wear will be promoted, so the interval is set to 0.01 to 0.1 μm Was.
[0013]
(D) Overall average thickness of the hard coating layer If the thickness is less than 0.5 μm, desired wear resistance cannot be ensured. On the other hand, if the average thickness exceeds 10 μm, chipping tends to occur. Therefore, the average layer thickness was determined to be 0.5 to 10 μm.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the coated cemented carbide tool of the present invention will be specifically described with reference to examples.
(Example 1)
As raw material powders, WC powder, TiC powder, VC powder, TaC powder, NbC powder, Cr 3 C 2 powder, and Co powder each having an average particle diameter of 1 to 3 μm were prepared. The mixture was wet-mixed for 72 hours in a ball mill, dried and pressed into a green compact at a pressure of 100 MPa, and the green compact was heated to 1400 ° C. for 1 hour in a vacuum of 6 Pa. Sintering is performed under the conditions of holding, and after sintering, the cutting edge portion is subjected to honing processing of R: 0.03, and a carbide substrate A1 to A10 made of a WC-based cemented carbide having a chip shape of ISO standard CNMG120408. Was formed.
[0015]
Further, as raw material powder, TiCN (TiC / TiN = 50/50 by weight) powder, Mo 2 C powder, ZrC powder, NbC powder, TaC powder, WC powder each having an average particle diameter of 0.5 to 2 μm , Co powder, and Ni powder were prepared, and these raw material powders were blended in the composition shown in Table 2, wet-mixed in a ball mill for 24 hours, dried, and then pressed into a green compact at a pressure of 100 MPa. The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to obtain an ISO standard CNMG120408. Carbide bases B1 to B6 made of TiCN-based cermet having the chip shape described above were formed.
[0016]
Next, each of the above-mentioned super-hard substrates A1 to A10 and B1 to B6 was ultrasonically cleaned in acetone and dried, and then, from the center axis on the rotary table in the arc ion plating apparatus shown in FIG. Attached along the outer periphery at a predetermined distance apart in the radial direction, as one cathode electrode (evaporation source), a Ta-B alloy for forming a B minimum content point having various component compositions, and a cathode on the other side As the electrode (evaporation source), various Ta-B alloys for forming the highest B content point having the same component composition as the Ta-B alloy used in the above-mentioned conventional (Ta, B) N layer formation were used for the rotary table. First, the inside of the apparatus was heated to 500 ° C. with a heater while the inside of the apparatus was evacuated and kept at a vacuum of 0.1 Pa or less. Up A DC bias voltage of -1000 V is applied to the super-hard substrate rotating while rotating, and a current of 100 A is caused to flow between the metal Cr of the cathode electrode and the anode electrode to generate an arc discharge. After performing Cr bombard cleaning, nitrogen gas was introduced as a reaction gas into the apparatus to obtain a reaction atmosphere of 2 Pa, and a DC bias voltage of -100 V was applied to the superhard substrate rotating while rotating on the rotary table, And, a current of 100 A is applied between the cathode electrode and the anode electrode made of the Ta-B alloy for forming the lowest B content point, and between the cathode electrode and the anode electrode of the Ta-B alloy for forming the highest B content point. An arc discharge was generated by applying a current of 150 A, and the target composition having the target composition shown in Tables 3 and 4 was applied to the surface of the cemented carbide substrate along the layer thickness direction. The minimum content point and the B maximum content point alternately and repeatedly exist at the target intervals shown in Tables 3 and 4, and the B maximum content point is the B minimum content point, and the B minimum content point is the B maximum content. By depositing a hard coating layer having a target total layer thickness also shown in Tables 3 and 4 having a component concentration distribution structure in which the B content continuously changes at points, Throwaway tips made of the surface-coated cemented carbide of the present invention (hereinafter referred to as the coated cemented carbide tips of the present invention) 1 to 16 were produced.
[0017]
For the purpose of comparison, these super-hard substrates A1 to A10 and B1 to B6 were ultrasonically cleaned in acetone, dried, and charged into a usual arc ion plating apparatus shown in FIG. As a cathode electrode (evaporation source), various Ta-B alloys having the same component composition as the Ta-B alloy used for forming the above-mentioned conventional (Ta, B) N layer are mounted. First, while the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, the inside of the apparatus is heated to 500 ° C. with a heater, and a DC bias voltage of −1000 V is applied to the super-hard substrate, An arc discharge is generated by passing a current of 100 A between the metal Cr of the cathode electrode and the anode electrode, thereby cleaning the surface of the cemented carbide substrate with Cr bombardment. To a reaction atmosphere of 2 Pa, a direct current bias voltage of -100 V is applied to the superhard substrate, and a current of 150 A flows between the Ta-B alloy of the cathode electrode and the anode electrode to cause arc discharge. Having the target composition and the target layer thickness shown in Tables 5 and 6 on the respective surfaces of the cemented carbide substrates A1 to A10 and B1 to B6, and having substantially the composition along the layer thickness direction. By depositing a hard coating layer composed of a (Ta, B) N layer that does not change, a conventional surface coated cemented carbide throw-away tip (hereinafter referred to as a conventional coated cemented carbide tip) 1 as a conventionally coated cemented carbide tool 1 ~ 16 were each manufactured.
[0018]
Next, with respect to the above-mentioned coated carbide tips 1 to 16 of the present invention and conventional coated carbide tips 1 to 16, in a state where they were screwed to the tip of a tool steel tool with a fixing jig,
Work material: JIS SCM440 round bar,
Cutting speed: 330 m / min. ,
Cut: 3.5 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 6 minutes,
Dry continuous high-speed high-cut cutting test of alloy steel under the following conditions:
Work material: Round bar with four vertical grooves at equal intervals in the length direction of JIS / SUS304,
Cutting speed: 250 m / min. ,
Cut: 1.0 mm,
Feed: 0.4 mm / rev. ,
Cutting time: 3 minutes,
Intermittent high-speed high-feed cutting test of stainless steel under the following conditions:
Work material: JIS S15C lengthwise round bar
Cutting speed: 300 m / min. ,
Cut: 3.0 mm,
Feed: 0.1 mm / rev. ,
Cutting time: 5 minutes,
A dry intermittent high-speed, high-cut cutting test was performed on mild steel under the following conditions, and the flank wear width of the cutting edge was measured in each cutting test. The measurement results are shown in Tables 3 to 6.
[0019]
[Table 1]
[Table 2]
[Table 3]
[Table 4]
[Table 5]
[Table 6]
(Example 2)
As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, and ZrC of 1.2 μm Powder, 2.3 μm Cr 3 C 2 powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C [TiC / WC = 50/50 by mass ratio] powder, and 1 μm 0.8 μm Co powder was prepared, and each of these raw material powders was blended in the blending composition shown in Table 7, further added with wax, ball-mixed in acetone for 24 hours, dried under reduced pressure, and then dried under reduced pressure at a pressure of 100 MPa. And press-molding these compacts to a predetermined temperature in the range of 1370 to 1470 ° C. at a rate of 7 ° C./min in a vacuum atmosphere of 6 Pa. After holding at temperature for 1 hour, sintering under furnace cooling condition Then, three types of round bar sintered bodies for forming a carbide substrate having a diameter of 8 mm, 13 mm, and 26 mm were formed. Carbide substrate having dimensions of 6 mm x 13 mm, 10 mm x 22 mm, and 20 mm x 45 mm, respectively, and a four-flute square shape with a twist angle of 30 degrees. (End mill) C-1 to C-8 were produced respectively.
[0026]
Then, these super-hard substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone, dried, and charged into an arc ion plating apparatus also shown in FIG. Under the same conditions as in Example 1, the B maximum content points and the B minimum content points of the target compositions shown in Table 8 alternately and repeatedly exist at the target intervals shown in Table 8 along the layer thickness direction, and A target overall layer having a component concentration distribution structure in which the B content continuously changes from the B highest content point to the B lowest content point, and the B content from the B lowest content point to the B highest content point, and also shown in Table 8 By depositing a thick hard coating layer, end mills 1-8 of the surface coated cemented carbide of the present invention (hereinafter referred to as coated carbide end mills of the present invention) as coated carbide tools of the present invention were manufactured.
[0027]
For the purpose of comparison, the above-mentioned ultra-hard substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and then a normal arc ion plating apparatus also shown in FIG. (Ta, B) N having the target composition and target layer thickness shown in Table 9 and having substantially no composition change along the layer thickness direction under the same conditions as in Example 1 described above. By depositing a hard coating layer composed of layers, end mills made of conventional surface-coated cemented carbide (hereinafter referred to as conventional coated carbide end mills) 1 to 8 as conventional coated cemented carbide tools were manufactured, respectively.
[0028]
Next, among the coated carbide end mills 1 to 8 of the present invention and the conventional coated carbide end mills 1 to 8, of the coated carbide end mills 1 to 3 and the coated carbide end mills 1 to 3 of the present invention,
Work material: JIS SNCM439 plate material with a plane dimension of 100 mm x 250 mm and a thickness of 50 mm
Cutting speed: 200 m / min. ,
Groove depth (cut): 8.0 mm,
Table feed: 1000 mm / min,
For the dry high-speed high feed groove cutting test of alloy steel under the conditions of the above, the coated carbide end mills 4 to 6 of the present invention and the conventionally coated carbide end mills 4 to 6,
Work material: JIS SKD11 plate material with a plane dimension of 100 mm x 250 mm and a thickness of 50 mm
Cutting speed: 250 m / min. ,
Groove depth (cut): 6.0 mm,
Table feed: 500 mm / min,
For the dry high-speed high-cut groove cutting test of tool steel under the following conditions, coated carbide end mills 7 and 8 of the present invention and conventional coated carbide end mills 7 and 8,
Work material: JIS S50C plate material with a plane size of 100 mm x 250 mm and a thickness of 50 mm
Cutting speed: 400 m / min. ,
Groove depth (cut): 9.0 mm,
Table feed: 1500 mm / min,
Dry high-speed, high-cut and high-feed-groove cutting tests were performed on carbon steel under the following conditions, and in any dry-groove cutting test, the flank wear width of the outer peripheral edge of the cutting edge is used as a guide for the service life. The cutting groove length up to 0.1 mm was measured. The measurement results are shown in Tables 8 and 9, respectively.
[0029]
[Table 7]
[Table 8]
[Table 9]
(Example 3)
The diameters produced in Example 2 were 8 mm (for forming the super-hard substrates C-1 to C-3), 13 mm (for forming the super-hard substrates C-4 to C-6), and 26 mm (for the super-hard substrates C-). 7, for forming C-8), the diameter x length of the groove forming portion was 4 mm x 13 mm (by grinding) from the three types of round rod sintered bodies by grinding. Carbide substrates D-1 to D-3), dimensions of 8 mm x 22 mm (carbide substrates D-4 to D-6), and 16 mm x 45 mm (carbide substrates D-7 and D-8), and any of them Carbide substrates (drills) D-1 to D-8 each having a two-blade shape with a twist angle of 30 degrees were manufactured.
[0033]
Next, the cutting blades of the super hard substrates (drills) D-1 to D-8 are honed, ultrasonically cleaned in acetone, and dried, and then the arc ion plating apparatus shown in FIG. Under the same conditions as in Example 1 described above, and the B-maximum content point and the B-minimum content point of the target composition shown in Table 10 are alternately arranged along the layer thickness direction in the same manner as in Example 10. And a component concentration distribution structure in which the B content continuously changes from the B highest content point to the B lowest content point, from the B lowest content point to the B highest content point, and By depositing a hard coating layer having a target overall layer thickness shown in 10, a drill made of the surface-coated cemented carbide of the present invention as the coated carbide tool of the present invention (hereinafter referred to as the coated carbide drill of the present invention) 1 to 8 Was manufactured respectively.
[0034]
Also, for comparison purposes, the cutting edges of the above-mentioned carbide substrates (drills) D-1 to D-8 are honed, ultrasonically cleaned in acetone, and dried, and are also shown in FIG. It was charged into a normal arc ion plating apparatus, and had the target composition and the target layer thickness shown in Table 11 under the same conditions as in Example 1 above, and the composition change substantially along the layer thickness direction. By depositing a hard coating layer consisting of a (Ta, B) N layer, conventional drills made of conventional surface-coated cemented carbide (hereinafter referred to as conventional coated carbide drills) 1 to 8 as conventional coated carbide tools are respectively provided. Manufactured.
[0035]
Next, of the coated carbide drills 1 to 8 of the present invention and the coated carbide drills 1 to 8 of the related art, the coated carbide drills 1 to 3 of the present invention and the covered carbide drills 1 to 3 of the present invention are:
Work material: JIS SKD61 plate material with a plane size of 100 mm x 250 mm and a thickness of 50 mm
Cutting speed: 45 m / min. ,
Feed: 0.18 mm / rev,
Hole depth: 8mm
For the wet-type high-speed and high-feed drilling cutting test of tool steel under the following conditions, the coated carbide drills 4 to 6 of the present invention and the conventionally coated carbide drills 4 to 6,
Work material: JIS FC400 plate material with a plane dimension of 100 mm x 250 mm and a thickness of 50 mm
Cutting speed: 110 m / min. ,
Feed: 0.35 mm / rev,
Hole depth: 16mm
For the wet-type high-speed and high-feed drilling cutting test of ductile cast iron under the following conditions, the coated carbide drills 7 and 8 of the present invention and the conventionally coated carbide drills 7 and 8,
Work material: JIS FC300 plate material with a plane dimension of 100 mm x 250 mm and a thickness of 50 mm
Cutting speed: 150 m / min. ,
Feed: 0.4 mm / rev,
Hole depth: 32mm
Welding high-speed and high-feed drilling cutting test of cast iron under the conditions described above, and in any of the wet drilling cutting tests (using water-soluble cutting oil), until the flank wear width of the tip cutting edge reaches 0.3 mm Was measured. The measurement results are shown in Tables 10 and 11, respectively.
[0036]
[Table 10]
[Table 11]
The resulting coated carbide tips 1-16, the coated carbide end mills 1-8, and the coated hard layers constituting the coated carbide drills 1-8 as the resulting coated carbide tools of the invention, In addition, the hard coating layers constituting the conventional coated carbide tips 1 to 16, the conventional coated carbide end mills 1 to 8 and the conventional coated carbide drills 1 to 8 as conventional coated carbide tools are Auger along the thickness direction. The contents of Ta and B were measured using a spectrophotometer. From these measurement results, in the hard coating layer of the coated carbide tool according to the present invention, the B highest content point and the B lowest content point having substantially the same composition as the target composition along the thickness direction are substantially equal to the target interval. At the same intervals, and the overall average layer thickness of the hard coating layer also shows substantially the same value as the target overall layer thickness, and further from the B maximum content point to the B minimum content point and the B minimum content. It was also confirmed that the composition had a component concentration distribution structure in which the B content continuously changed from the point to the B maximum content point. On the other hand, in the hard coating layer of the conventional coated carbide tool, there is no change in composition along the thickness direction, and the composition is substantially the same as the target composition and the overall average layer thickness is substantially the same as the target overall layer thickness. Was confirmed.
[0039]
【The invention's effect】
From the results shown in Tables 3 to 11, the hard coating layer has a B-highest content point having excellent high-temperature hardness and oxidation resistance and a B-lowest content point having high strength alternately in the layer thickness direction at a predetermined interval. Wherein the B content has a component concentration distribution structure in which the B content continuously changes from the highest B content point to the lowest B content point, and the lowest B content point to the highest B content point. The hard coating layer of the hard tool was excellent even when cutting various types of steel and cast iron at high speed and under heavy cutting conditions such as high cutting and high feed with high mechanical impact. In a conventional coated carbide tool having a (Ta, B) N layer in which the hard coating layer does not substantially change in composition along the layer thickness direction while exhibiting chipping resistance, the hard coating layer has Although it has excellent high-temperature hardness and oxidation resistance, For degree it is insufficient, chipping occurs in the cutting edge, which is clear may result in a relatively short time service life due.
As described above, the coated carbide tool of the present invention is particularly suitable for cutting various kinds of steel and cast iron at high speed and under heavy cutting conditions such as high cutting and high feed with high mechanical impact. In addition, since it exhibits excellent chipping resistance and exhibits excellent wear resistance over a long period of time, it can sufficiently cope with labor saving and energy saving of cutting work and further cost reduction. .
[Brief description of the drawings]
FIG. 1 shows an arc ion plating apparatus used for forming a hard coating layer constituting a coated carbide tool of the present invention, wherein (a) is a schematic plan view and (b) is a schematic front view.
FIG. 2 is a schematic explanatory view of a conventional arc ion plating apparatus used for forming a hard coating layer constituting a conventional coated carbide tool.
Claims (1)
上記硬質被覆層が、層厚方向にそって、Ｂ最高含有点とＢ最低含有点とが所定間隔をおいて交互に繰り返し存在し、かつ前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が連続的に変化する成分濃度分布構造を有し、
さらに、上記Ｂ最高含有点が、
組成式：（Ｔａ１−Ｘ ＢＸ ）Ｎ（ただし、原子比で、Ｘは０．４０〜０．６０を示す）、
上記Ｂ最低含有点が、
組成式：（Ｔａ１−Ｙ ＢＹ ）Ｎ（ただし、原子比で、Ｙは０．０５〜０．３０を示す）、
を満足し、かつ隣り合う上記Ｂ最高含有点とＢ最低含有点の間隔が、０．０１〜０．１μｍであること、
を特徴とする高速重切削加工条件で硬質被覆層がすぐれた耐チッピング性を発揮する表面被覆超硬合金製切削工具。Surface coating formed by physical vapor deposition of a hard coating layer composed of a composite nitride layer of Ta and B on the surface of a tungsten carbide-based cemented carbide substrate or a titanium carbonitride-based cermet substrate with a total average layer thickness of 0.5 to 10 μm. In cemented carbide cutting tools,
In the hard coating layer, the B highest content point and the B lowest content point alternately and repeatedly exist at predetermined intervals along the layer thickness direction, and the B highest content point and the B lowest content point, A component concentration distribution structure in which the B content continuously changes from the lowest content point to the B highest content point,
Further, the B maximum content point is
Composition formula: (Ta 1-X B X ) N ( provided that an atomic ratio, X is shows the 0.40 to 0.60),
The B minimum content point is
Composition formula: (Ta 1-Y B Y ) N ( provided that an atomic ratio, Y denotes the 0.05 to 0.30),
And the interval between the adjacent B-highest content point and B-lowest content point is 0.01 to 0.1 μm,
Surface coated cemented carbide cutting tool with a hard coating layer that exhibits excellent chipping resistance under high-speed heavy cutting conditions.
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| JP2003020616A JP4320707B2 (en) | 2003-01-29 | 2003-01-29 | Cutting tool made of surface-coated cemented carbide that exhibits excellent chipping resistance under high-speed heavy cutting conditions. |
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| JP2003020616A JP4320707B2 (en) | 2003-01-29 | 2003-01-29 | Cutting tool made of surface-coated cemented carbide that exhibits excellent chipping resistance under high-speed heavy cutting conditions. |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009147002A2 (en) * | 2008-06-02 | 2009-12-10 | H.C. Starck Gmbh | Process for producing electrolytic capacitors having a low leakage current |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009147002A2 (en) * | 2008-06-02 | 2009-12-10 | H.C. Starck Gmbh | Process for producing electrolytic capacitors having a low leakage current |
| WO2009147002A3 (en) * | 2008-06-02 | 2010-04-01 | H.C. Starck Gmbh | Process for producing electrolytic capacitors having a low leakage current |
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