JP3969230B2

JP3969230B2 - Surface coated cemented carbide cutting tool with excellent chipping resistance with hard coating layer under heavy cutting conditions

Info

Publication number: JP3969230B2
Application number: JP2002214710A
Authority: JP
Inventors: 安彦田代
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2002-07-24
Filing date: 2002-07-24
Publication date: 2007-09-05
Anticipated expiration: 2022-07-24
Also published as: JP2004050381A

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層が高強度を有し、かつ高温硬さと耐熱性にもすぐれ、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、基体の表面に硬質被覆層を蒸着形成してなる表面被覆切削工具（以下、被覆工具という）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、被覆工具として、基体の表面に、ＣｒとＡｌの複合窒化物［以下、（Ｃｒ，Ａｌ）Ｎで示す］層からなる硬質被覆層を１〜１５μｍの平均層厚で物理蒸着してなる被覆工具が提案され、各種の鋼や鋳鉄などの連続切削や断続切削加工に用いられている（例えば特許文献１，２参照）。
【０００４】
さらに、上記の被覆工具が、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Ｃｒ−Ａｌ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：９０Ａ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、前記基体の表面に、上記（Ｃｒ，Ａｌ）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（例えば特許文献２参照）。
【０００５】
【特許文献１】
特開平９−０４１１２７号公報
【特許文献２】
特開２０００−２７１６９９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、上記の従来被覆工具においては、これを通常の切削加工条件で用いた場合には問題はないが、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工具を開発すべく、上記の従来被覆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工具を構成する（Ｃｒ，Ａｌ）Ｎ層は、層厚全体に亘って実質的に均一な組成を有し、したがって均質な強度および高温硬さと耐熱性を有するが、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Ａｌ含有量の高いＣｒ−Ａｌ合金、他方側に相対的にＡｌ含有量の低いＣｒ−Ａｌ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、前記基体の表面に（Ｃｒ，Ａｌ）Ｎ層を形成すると、この結果の（Ｃｒ，Ａｌ）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基体が上記の一方側の相対的にＡｌ含有量の高いＣｒ−Ａｌ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Ａｌ最高含有点が形成され、また前記基体が上記の他方側の相対的にＡｌ含有量の低いＣｒ−Ａｌ合金のカソード電極に最も接近した時点で層中にＡｌ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Ａｌ最高含有点とＡｌ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Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ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（Ｃｒ，Ａｌ）Ｎ層において、上記の基体を炭化タングステン（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）に特定した上で、対向配置の一方側のカソード電極（蒸発源）であるＣｒ−Ａｌ合金におけるＡｌ含有量をＣｒとの合量に占める割合で、原子比で、０．４０〜０．６０とし、かつ同他方側のカソード電極（蒸発源）であるＣｒ−Ａｌ合金におけるＡｌ含有量を相対的に低くして、同じくＣｒとの合量に占める割合で、原子比で、０．０５〜０．３０とする共に、前記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Ａｌ最高含有点が、組成式：（Ｃｒ_1-XＡｌ_X）Ｎ（ただし、原子比で、Ｘは０．４０〜０．６０を示す）、
上記Ａｌ最低含有点が、組成式：（Ｃｒ_1-YＡｌ_Y）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Ａｌ最高含有点とＡｌ最低含有点の厚さ方向の間隔を０．０１〜０．１μmとすると、
上記Ａｌ最高含有点部分では、相対的にＡｌ含有量が高くなることから、高温硬さと耐熱性の高いものとなり、一方上記Ａｌ最低含有点部分では、前記Ａｌ最高含有点部分に比してＡｌ含有量が低く、Ｃｒ含有量の高いものとなるので、相対的に一段と高い強度を示すようになり、かつこれらＡｌ最高含有点とＡｌ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高強度を保持した上で、高温硬さと耐熱性も具備するようになり、したがって、上記の超硬基体表面にかかる構成の（Ｃｒ，Ａｌ）Ｎ層からなる硬質被覆層を蒸着形成してなる被覆超硬工具は、各種の鋼や鋳鉄などの切削加工を、特に高い機械的衝撃を伴うので高強度が要求される、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、（Ｃｒ，Ａｌ）Ｎ層からなる硬質被覆層を１〜１５μｍ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、Ａｌ最高含有点とＡｌ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Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ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Ａｌ最高含有点が、組成式：（Ｃｒ_1-XＡｌ_X）Ｎ（ただし、原子比で、Ｘは０．４０〜０．６０を示す）、
上記Ａｌ最低含有点が、組成式：（Ｃｒ_1-YＡｌ_Y）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Ａｌ最高含有点とＡｌ最低含有点の間隔が、０．０１〜０．１μmである、
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）Ａｌ最高含有点の組成
Ａｌ最高含有点の（Ｃｒ，Ａｌ）ＮにおけるＣｒ成分は、層自体の強度を向上させ、またＡｌ成分は層の高温硬さと耐熱性を向上させる作用をもつものであり、したがってＡｌ成分の含有割合が高くなればなるほど高温硬さと耐熱性は向上したものになるが、Ａｌの割合を示すＸ値がＣｒ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Ａｌ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未満では高温硬さと耐熱性に所望の向上効果が得られないことから、Ａｌ最高含有点でのＡｌの割合を示すＸ値を０．４０〜０．６０と定めた。
【００１１】
（ｂ）Ａｌ最低含有点の組成
上記の通りＡｌ最高含有点は相対的に高い高温硬さと耐熱性を有するが、反面相対的に強度の劣るものであるため、このＡｌ最高含有点の強度不足を補う目的で、Ｃｒ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Ａｌ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Ａｌの割合を示すＹ値がＣｒとの合量に占める割合（原子比）で０．３０を越えると、Ａｌ最低含有点の強度が低下し、これが原因でチッピングが発生し易くなり、一方同Ｙ値が０．０５未満になると、相対的にＣｒの割合が多くなり過ぎて、Ａｌ最低含有点に所望の高温硬さと耐熱性を具備せしめることができなくなり、この結果摩耗の進行が急激に促進するようになることから、Ａｌ最低含有点でのＡｌの割合を示すＹ値を０．０５〜０．３０と定めた。
【００１２】
（ｃ）Ａｌ最高含有点とＡｌ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、さらに高温硬さと耐熱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Ａｌ最高含有点であれば強度不足、Ａｌ最低含有点であれば高温硬さと耐熱性不足が層内に局部的に現れ、これが原因で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１μｍ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１５μｍ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１〜１５μｍ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、Ｃｒ₃Ｃ₂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、Ｍｏ₂Ｃ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Ａｌ最低含有点形成用Ｃｒ−Ａｌ合金、他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Ａｌ最高含有点形成用Ｃｒ−Ａｌ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０．５Ｐａ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１５０Ａ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４Ｐａ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−１２０Ｖの直流バイアス電圧を印加し、それぞれのカソード電極(前記Ａｌ最低含有点形成用Ｃｒ−Ａｌ合金およびＡｌ最高含有点形成用Ｃｒ−Ａｌ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Ａｌ最低含有点とＡｌ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Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ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）として種々の成分組成をもったＣｒ−Ａｌ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０．５Ｐａ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１５０Ａ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４Ｐａの反応雰囲気とすると共に、超硬基体に−１２０Ｖの直流バイアス電圧を印加し、前記カソード電極のＣｒ−Ａｌ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（それぞれ本発明被覆超硬チップ１〜１６を構成する硬質被覆層のＡｌ最高含有点の目標組成および目標層厚と同じ）を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｃｒ，Ａｌ）Ｎ層からなる硬質被覆層を蒸着することにより、比較被覆超硬工具としての比較表面被覆超硬合金製スローアウエイチップ（以下、比較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および比較被覆超硬チップ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：１４０ｍ／ｍｉｎ．、
切り込み：５ｍｍ、
送り：０．２ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での合金鋼の乾式連続高切り込み切削加工試験、
被削材：ＪＩＳ・Ｓ４５Ｃの長さ方向等間隔４本縦溝入り丸棒、
切削速度：１７０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．７ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での炭素鋼の乾式断続高送り切削加工試験、さらに、
被削材：ＪＩＳ・ＦＣ２５０の長さ方向等間隔４本溝入り丸棒、
切削速度：２００ｍ／ｍｉｎ．、
切り込み：６ｍｍ、
送り：０．２５ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での鋳鉄の乾式断続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】

【００２０】
【表２】

【００２１】
【表３】

【００２２】
【表４】

【００２３】
【表５】

【００２４】
【表６】

【００２５】
（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の寸法を有し、かついずれもねじれ角：３０度の４枚刃スクエア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Ａｌ最高含有点とＡｌ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Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ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（それぞれ本発明被覆超硬エンドミル１〜８を構成する硬質被覆層のＡｌ最高含有点の目標組成および目標層厚と同じ）を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｃｒ，Ａｌ）Ｎ層からなる硬質被覆層を蒸着することにより、比較被覆超硬工具としての比較表面被覆超硬合金製エンドミル（以下、比較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および比較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および比較被覆超硬エンドミル１〜３については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＫＤ１１の板材、
切削速度：６０ｍ／ｍｉｎ．、
溝深さ（切り込み）：３ｍｍ、
テーブル送り：１５０ｍｍ／分、
の条件での工具鋼の湿式高送り溝切削加工試験、本発明被覆超硬エンドミル４〜６および比較被覆超硬エンドミル４〜６については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＵＳ３０４の板材、
切削速度：３５ｍ／ｍｉｎ．、
溝深さ（切り込み）：１２ｍｍ、
テーブル送り：７５ｍｍ／分、
の条件でのステンレス鋼の湿式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および比較被覆超硬エンドミル７，８については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＮＣＭ４３９の板材、
切削速度：９０ｍ／ｍｉｎ．、
溝深さ（切り込み）：２０ｍｍ、
テーブル送り：６００ｍｍ／分、
の条件での合金鋼の湿式高切り込みおよび高送り溝切削加工試験（いずれの溝切削加工試験でも水溶性切削油使用）をそれぞれ行い、いずれの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】

【００３０】
【表８】

【００３１】
【表９】

【００３２】
（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）の寸法を有し、かついずれもねじれ角：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Ａｌ最高含有点とＡｌ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Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ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（それぞれ本発明被覆超硬ドリル１〜８を構成する硬質被覆層のＡｌ最高含有点の目標組成および目標層厚と同じ）を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｃｒ，Ａｌ）Ｎ層からなる硬質被覆層を蒸着することにより、比較被覆超硬工具としての比較表面被覆超硬合金製ドリル（以下、比較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および比較被覆超硬ドリル１〜８のうち、本発明被覆超硬ドリル１〜３および比較被覆超硬ドリル１〜３については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＫＤ６１の板材、
切削速度：２０ｍ／ｍｉｎ．、
送り：０．２ｍｍ／ｒｅｖ、
穴深さ：８ｍｍ
の条件での工具鋼の湿式高送り穴あけ切削加工試験、本発明被覆超硬ドリル４〜６および比較被覆超硬ドリル４〜６については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＣＭ４４０の板材、
切削速度：４５ｍ／ｍｉｎ．、
送り：０．３５ｍｍ／ｒｅｖ、
穴深さ：１５ｍｍ
の条件での合金鋼の湿式高送り穴あけ切削加工試験、本発明被覆超硬ドリル７，８および比較被覆超硬ドリル７，８については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＦＣ３００の板材、
切削速度：６０ｍ／ｍｉｎ．、
送り：０．６ｍｍ／ｒｅｖ、
穴深さ：３０ｍｍ
の条件での鋳鉄の湿式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】

【００３７】
【表１１】

【００３８】
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、並びに比較被覆超硬工具としての比較被覆超硬チップ１〜１６、比較被覆超硬エンドミル１〜８、および比較被覆超硬ドリル１〜８をそれぞれ構成する硬質被覆層について、層厚方向に沿ってＣｒおよびＡｌ成分の含有量をオージェ分光分析装置を用いて測定し、この測定結果から各測定点におけるＣｒおよびＡｌ成分の含有量を検討したところ、本発明被覆超硬工具では、Ａｌ最高含有点とＡｌ最低含有点とがそれぞれ目標値と実質的に同じ組成および間隔で交互に繰り返し存在し、かつ、Ａｌ最高含有点からＡｌ最低含有点、前記Ａｌ最低含有点からＡｌ最高含有点へＡｌ含有量が連続的に変化する成分濃度分布構造を有することが確認され、また、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た。一方前記比較被覆超硬工具の硬質被覆層では、層厚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、相対的にすぐれた高温硬さと耐熱性を有するＡｌ最高含有点と、高強度を有するＡｌ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Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ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（Ｃｒ，Ａｌ）Ｎ層からなる比較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熱性を有するものの、強度に劣るものであるために、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、通常の条件での切削加工は勿論のこと、特に各種の鋼や鋳鉄などの切削加工を、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】比較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]
BACKGROUND OF THE INVENTION
In the present invention, the hard coating layer has high strength and is excellent in high-temperature hardness and heat resistance. Therefore, cutting of various steels and cast irons, particularly high cutting with high mechanical impact and high feed, etc. The present invention relates to a surface-coated cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide tool) that exhibits excellent chipping resistance when subjected to heavy cutting conditions.
[0002]
[Prior art]
In general, a surface-coated cutting tool (hereinafter referred to as a coated tool) formed by vapor-depositing a hard coating layer on the surface of a substrate (hereinafter referred to as a coated tool) is used for turning and planing of various materials such as steel and cast iron. Slow-away inserts that can be detachably attached to the part, drills and miniature drills that are used for drilling, etc., and solid types that are used for chamfering, grooving, shoulder processing, etc., where the cutting blade takes an intermittent cutting form In addition, there is known a slow-away end mill tool for performing a cutting process in the same manner as the solid-type end mill with the throw-away tip detachably attached thereto.
[0003]
Further, as a coating tool, a hard coating layer composed of a composite nitride of Cr and Al [hereinafter referred to as (Cr, Al) N] layer is physically vapor-deposited on the surface of the substrate with an average layer thickness of 1 to 15 μm. Coated tools have been proposed and used for continuous cutting and intermittent cutting of various steels and cast irons (see, for example, Patent Documents 1 and 2).
[0004]
Further, the above-mentioned coated tool, for example, inserts a substrate into an arc ion plating apparatus which is one of physical vapor deposition apparatuses shown schematically in FIG. 2, and the inside of the apparatus is heated to a temperature of, for example, 500 ° C. with a heater. In a heated state, an arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) on which a Cr—Al alloy having a predetermined composition is set, for example, at a current of 90 A, and at the same time, a reactive gas is generated in the apparatus. As an example, a nitrogen atmosphere is introduced to form a reaction atmosphere of 2 Pa, for example, while a bias voltage of, for example, −100 V is applied to the substrate, a hard layer made of the (Cr, Al) N layer on the surface of the substrate. It is also known that it is produced by depositing a coating layer (see, for example, Patent Document 2).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-041127 [Patent Document 2]
JP 2000-271699 A [0006]
[Problems to be solved by the invention]
In recent years, there has been a remarkable improvement in the performance of cutting devices. On the other hand, there are strong demands for labor-saving and energy-saving in cutting, and cost reductions. Accordingly, cutting is performed under heavy cutting conditions such as high cutting and high feed. In the above-mentioned conventional coated tool, there is no problem when it is used under normal cutting conditions, but the cutting process is heavy, such as high cutting with high mechanical impact and high feed. When performed under cutting conditions, chipping (microcracking) is likely to occur due to insufficient strength of the hard coating layer, and the service life is reached in a relatively short time.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed a hard coating that constitutes the above-mentioned conventional coated tool in order to develop a coated tool that exhibits excellent chipping resistance with a hard coating layer particularly excellent under heavy cutting conditions. As a result of conducting research focusing on the layer,
(A) The (Cr, Al) N layer constituting the conventional coated tool formed by using the arc ion plating apparatus shown in FIG. 2 has a substantially uniform composition over the entire layer thickness. Therefore, the arc ion plating apparatus having the structure shown in FIG. 1 (a) is a schematic plan view and FIG. A rotating table for mounting a substrate is provided on the part, and a Cr—Al alloy having a relatively high Al content is placed on one side and a Cr—Al alloy having a relatively low Al content is placed on the other side across the rotating table. Using an arc ion plating device arranged oppositely as an electrode (evaporation source), a plurality of substrates are ringed along the outer peripheral portion at a predetermined radial distance from the central axis on the rotary table of the device. In this state, the cathode is rotated on both sides of the cathode while rotating the rotary table with the atmosphere inside the apparatus as a nitrogen atmosphere and rotating the substrate itself for the purpose of uniforming the thickness of the hard coating layer formed by vapor deposition. When an arc discharge is generated between the electrode (evaporation source) and the anode electrode to form a (Cr, Al) N layer on the surface of the substrate, the resulting (Cr, Al) N layer has a rotating table. The highest Al content point is formed in the layer when the substrate arranged in a ring shape is closest to the cathode electrode (evaporation source) of the Cr-Al alloy having a relatively high Al content on one side. In addition, when the substrate is closest to the cathode electrode of the Cr—Al alloy having a relatively low Al content on the other side, a minimum Al content point is formed in the layer, In the layer thickness direction, the Al highest content point and the Al lowest content point appear alternately with a predetermined interval, and the Al highest content point to the Al lowest content point, the Al lowest content point to the Al highest content point. Have a component concentration distribution structure where the Al content changes continuously to the point of inclusion.
[0008]
(B) In the (Cr, Al) N layer having the repeated continuous change component concentration distribution structure of (a) above, the base is made of tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN). The content of Al in the Cr-Al alloy, which is a cathode electrode (evaporation source) on one side facing each other, specified as a substrate made of a base cermet (hereinafter collectively referred to as a carbide substrate). Is the proportion of the total amount of Cr with an atomic ratio of 0.40 to 0.60, and the Al content in the Cr—Al alloy which is the cathode electrode (evaporation source) on the other side is relatively low Then, in the ratio of the total amount with Cr, the atomic ratio is 0.05 to 0.30, and the rotational speed of the turntable on which the carbide substrate is mounted is controlled,
The Al highest content point is the composition formula: (Cr _1-X Al _X ) N (wherein X is 0.40 to 0.60 in atomic ratio),
The Al minimum content point is a composition formula: (Cr _1-Y Al _Y ) N (wherein Y represents 0.05 to 0.30 in atomic ratio),
And the interval in the thickness direction between the adjacent Al highest content point and Al lowest content point adjacent to each other is 0.01 to 0.1 μm,
In the Al highest content point portion, the Al content is relatively high, so that the high temperature hardness and heat resistance are high. On the other hand, in the Al minimum content point portion, Al is higher than the Al highest content point portion. Since the content is low and the Cr content is high, the strength becomes relatively higher and the distance between the Al highest content point and the Al lowest content point is extremely small. While maintaining high strength as a characteristic, it also has high-temperature hardness and heat resistance. Therefore, a hard coating layer composed of a (Cr, Al) N layer having a structure on the surface of the above-mentioned carbide substrate is formed by vapor deposition. Coated carbide tools made of these materials are used for cutting various steels and cast irons under heavy cutting conditions such as high depth of cut and high feed, which require high strength due to particularly high mechanical impact. , Hard coating layer To become possible to exert chipping resistance was gray.
The research results shown in (a) and (b) above were obtained.
[0009]
The present invention has been made based on the above research results. A hard coating layer composed of a (Cr, Al) N layer is physically deposited on the surface of a cemented carbide substrate with an overall average layer thickness of 1 to 15 μm. In the coated carbide tool
In the hard coating layer, the highest Al content point and the lowest Al content point are present alternately at predetermined intervals along the thickness direction, and the lowest Al content point, the Al content point, from the highest Al content point. A component concentration distribution structure in which the Al content continuously changes from the lowest content point to the Al highest content point,
Furthermore, the Al highest content point is the composition formula: (Cr _1-X Al _X ) N (wherein X is 0.40 to 0.60 in atomic ratio),
The Al minimum content point is a composition formula: (Cr _1-Y Al _Y ) N (wherein Y represents 0.05 to 0.30 in atomic ratio),
And the interval between the Al highest content point and the Al lowest content point adjacent to each other is 0.01 to 0.1 μm.
It is characterized by a coated cemented carbide tool that exhibits excellent chipping resistance under heavy cutting conditions.
[0010]
Next, in the coated carbide tool of the present invention, the reason why the structure of the hard coating layer constituting the tool is limited as described above will be described.
(A) Composition of the highest Al content point The Cr component in (Cr, Al) N having the highest Al content point improves the strength of the layer itself, and the Al component has the effect of improving the high temperature hardness and heat resistance of the layer. Therefore, the higher the content ratio of the Al component, the higher the high temperature hardness and heat resistance, but the X value indicating the ratio of Al accounts for 0% of the total amount with Cr (atomic ratio). When the value exceeds .60, even if the Al lowest content point having high strength exists adjacently, a decrease in the strength of the layer itself is unavoidable, and as a result, chipping or the like is likely to occur, while the X value is the same. If it is less than 0.40, the desired improvement effect cannot be obtained in high temperature hardness and heat resistance, so the X value indicating the proportion of Al at the highest Al content point was set to 0.40 to 0.60.
[0011]
(B) Composition of Al minimum content point As described above, the Al maximum content point has relatively high high-temperature hardness and heat resistance, but on the other hand, it is relatively inferior in strength, so the strength of the Al maximum content point is insufficient. In order to compensate for this, the minimum content of Al, which has a high Cr content and thereby has high strength, is alternately interposed in the thickness direction. Therefore, the Y value indicating the Al content is the same as that of Cr. When the ratio (atomic ratio) in the amount exceeds 0.30, the strength of the Al minimum content point decreases, and this tends to cause chipping, while when the Y value is less than 0.05, the relative Since the ratio of Cr is excessively increased, the Al minimum content point cannot be provided with the desired high temperature hardness and heat resistance, and as a result, the progress of wear is rapidly accelerated. The proportion of Al in The to Y value was defined as 0.05 to 0.30.
[0012]
(C) Interval between the highest Al content point and the lowest Al content point If the distance is less than 0.01 μm, it is difficult to clearly form each point with the above composition. As a result, the layer has a desired high strength, Furthermore, high temperature hardness and heat resistance cannot be ensured, and if the distance exceeds 0.1 μm, each point has a defect, that is, the strength is insufficient if the Al content is the highest, and the temperature is high if the Al content is the lowest. Insufficient hardness and heat resistance appear locally in the layer, which makes it easier for chipping to occur on the cutting edge and promotes the progress of wear, so the interval is 0.01 to 0.1 μm. It was determined.
[0013]
(D) Overall average layer thickness of hard coating layer If the layer thickness is less than 1 μm, desired wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 15 μm, chipping tends to occur. Therefore, the average layer thickness was determined to be 1 to 15 μm.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated 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, all having an average particle diameter of 1 to 3 μm, were prepared. And then wet-mixed with a ball mill for 72 hours, dried, and press-molded into a green compact at a pressure of 100 MPa. The green compact was vacuumed at 6 Pa at a temperature of 1400 ° C. for 1 hour. Sintered under the holding conditions, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03, and the carbide bases A1 to A10 made of WC-based cemented carbide having ISO / CNMG120408 chip shape Formed.
[0015]
In addition, as raw material powders, all are TiCN (weight ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed into a 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 ISO standard / CNMG120408. TiCN-based cermet carbide substrates B1 to B6 having the following chip shape were formed.
[0016]
Next, each of the above-described carbide substrates A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, and then from the central axis on the rotary table in the arc ion plating apparatus shown in FIG. Mounted along the outer periphery at a predetermined distance in the radial direction, as a cathode electrode (evaporation source) on one side, an Al minimum content point forming Cr—Al alloy having various composition, cathode on the other side As an electrode (evaporation source), a Cr-Al alloy for forming the highest Al content point with various component compositions is placed opposite to the rotary table, and a metallic Cr for bombard cleaning is also mounted. The inside of the apparatus is heated to 500 ° C. with a heater while being evacuated and kept at a vacuum of 0.5 Pa or less, and then applied to a carbide substrate that rotates while rotating on the rotary table, with a DC voltage of −1000 V. Asphalt voltage is applied, a current of 150 A flows between the metal Cr of the cathode electrode and the anode electrode to generate an arc discharge, and the surface of the carbide substrate is cleaned by Cr bombardment, and then nitrogen is used as a reactive gas in the apparatus. A gas is introduced to form a reaction atmosphere of 4 Pa, and a DC bias voltage of −120 V is applied to the carbide substrate rotating while rotating on the rotary table, and each cathode electrode (Cr for forming the Al minimum content point is formed). -An Al alloy and a Cr-Al alloy for forming the highest Al content point) and an anode electrode, an arc discharge is generated by flowing a current of 150 A, and the surface of the cemented carbide substrate is displayed along the layer thickness direction. The Al minimum content point and the Al maximum content point of the target composition shown in 3 and 4 are alternately repeatedly present at the target intervals shown in Tables 3 and 4, and the Al maximum content point is included. The target total layer thickness having a component concentration distribution structure in which the Al content continuously changes from the point to the Al minimum content point, from the Al minimum content point to the Al maximum content point, and also shown in Tables 3 and 4 The surface-coated cemented carbide throwaway tips (hereinafter referred to as the present invention coated carbide tips) 1 to 16 as the present invention coated carbide tools were produced, respectively.
[0017]
Further, for the purpose of comparison, these carbide substrates A1 to A10 and B1 to B6 are ultrasonically cleaned in acetone and dried, and then loaded into a normal arc ion plating apparatus shown in FIG. In addition, Cr—Al alloys with various component compositions are mounted as cathode electrodes (evaporation sources), and further Bombard cleaning metal Cr is mounted. First, the inside of the apparatus is evacuated and kept at a vacuum of 0.5 Pa or less. However, after heating the inside of the apparatus to 500 ° C. with a heater, a DC bias voltage of −1000 V was applied to the cemented carbide substrate, and a current of 150 A was passed between the metal Cr of the cathode electrode and the anode electrode to cause arc discharge. Thus, the surface of the carbide substrate is Cr bombard washed, and then nitrogen gas is introduced into the apparatus as a reaction gas to form a 4 Pa reaction atmosphere. A direct current bias voltage of 20 V was applied, and a current of 150 A was passed between the Cr—Al alloy of the cathode electrode and the anode electrode to generate an arc discharge, whereby each of the carbide substrates A1 to A10 and B1 to B6. The target composition and target layer thickness shown in Tables 5 and 6 (same as the target composition and target layer thickness of the Al highest content point of the hard coating layer constituting the coated carbide chips 1 to 16 of the present invention, respectively) Throw made of comparative surface-coated cemented carbide as a comparative coated carbide tool by vapor-depositing a hard coating layer consisting of a (Cr, Al) N layer that has substantially no composition change along the layer thickness direction Outer chips (hereinafter referred to as comparative coated carbide chips) 1 to 16 were produced.
[0018]
Next, with the present invention coated carbide chips 1-16 and comparative coated carbide chips 1-16, in a state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SCM440 round bar,
Cutting speed: 140 m / min. ,
Cutting depth: 5mm,
Feed: 0.2 mm / rev. ,
Cutting time: 8 minutes
Dry continuous high-cut cutting test of alloy steel under the conditions of
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 170 m / min. ,
Incision: 1.5mm,
Feed: 0.7 mm / rev. ,
Cutting time: 8 minutes
Carbon steel dry intermittent high feed cutting test under the conditions of
Work material: JIS / FC250 longitudinally spaced four-grooved round bars,
Cutting speed: 200 m / min. ,
Incision: 6mm,
Feed: 0.25 mm / rev. ,
Cutting time: 8 minutes
The dry interrupted high-cut cutting test of cast iron was performed under the conditions described above, and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Tables 3-6.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
[Table 3]

[0022]
[Table 4]

[0023]
[Table 5]

[0024]
[Table 6]

[0025]
(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, 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 (mass ratio TiC / WC = 50/50) powder, and 1. 8 μm Co powder was prepared, each of these raw material powders was blended into the blending composition shown in Table 7, further added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and then shaped into a predetermined shape at a pressure of 100 MPa. Various green compacts were press-molded, and these green compacts were heated to a predetermined temperature in the range of 1370 to 1470 ° C. at a rate of temperature increase of 7 ° C./min in a 6 Pa vacuum atmosphere. For 1 hour and then sintering under furnace cooling conditions Three types of sintered carbide rod-forming bodies for forming a carbide substrate having diameters of 8 mm, 13 mm, and 26 mm were formed, and the combinations shown in Table 7 were obtained from the above-mentioned three types of round rod sintered bodies by grinding. And a carbide substrate having a 4-blade square shape with a cutting edge portion diameter × length of 6 mm × 13 mm, 10 mm × 22 mm, and 20 mm × 45 mm, respectively, and a twist angle of 30 degrees. (End mill) C-1 to C-8 were produced.
[0026]
Then, these carbide substrates (end mills) C-1 to C-8 were ultrasonically washed in acetone and dried, and then charged into the arc ion plating apparatus shown in FIG. Under the same conditions as in Example 1, the highest Al content point and the lowest Al content point of the target composition shown in Table 8 along the layer thickness direction alternately and repeatedly exist at the target interval shown in Table 8, and The target overall layer having a component concentration distribution structure in which the Al content continuously changes from the Al highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point, and also shown in Table 8 By vapor-depositing a hard coating layer having a thickness, end mills made of the surface coated cemented carbide of the present invention (hereinafter referred to as the present coated carbide end mill) 1 to 8 as the coated carbide tool of the present invention were produced.
[0027]
For the purpose of comparison, the above-mentioned carbide substrates (end mills) C-1 to C-8 are ultrasonically cleaned in acetone and dried, and the ordinary arc ion plating apparatus shown in FIG. 2 is also used. The target composition and target layer thickness shown in Table 9 under the same conditions as in Example 1 above (the target of the highest Al content point of the hard coating layer constituting the coated carbide end mills 1 to 8 of the present invention, respectively) By depositing a hard coating layer consisting of a (Cr, Al) N layer having the same composition and the same target layer thickness) and having substantially no composition change along the layer thickness direction, as a comparative coated carbide tool Comparative surface-coated cemented carbide end mills (hereinafter referred to as comparative coated cemented carbide end mills) 1 to 8 were produced.
[0028]
Next, of the present invention coated carbide end mills 1-8 and comparative coated carbide end mills 1-8, the present invention coated carbide end mills 1-3 and comparative coated carbide end mills 1-3 are as follows:
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SKD11 plate material,
Cutting speed: 60 m / min. ,
Groove depth (cut): 3 mm,
Table feed: 150 mm / min,
About the wet high feed grooving cutting test of the tool steel under the conditions of the present invention, the coated carbide end mills 4 to 6 and the comparative coated carbide end mills 4 to 6 of the present invention,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 35 m / min. ,
Groove depth (cut): 12 mm,
Table feed: 75mm / min,
With respect to the stainless steel wet high-grooving groove cutting test under the following conditions, the coated carbide end mills 7 and 8 according to the present invention and the comparative coated carbide end mills 7 and 8:
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SNCM439 plate material,
Cutting speed: 90 m / min. ,
Groove depth (cut): 20 mm,
Table feed: 600 mm / min,
Wet high cutting and high feed grooving test (along with any water cutting oil in any grooving test) of alloy steel under the above conditions. The cutting groove length was measured until the surface wear width reached 0.1 mm, which is a guide for the service life. The measurement results are shown in Tables 8 and 9, respectively.
[0029]
[Table 7]

[0030]
[Table 8]

[0031]
[Table 9]

[0032]
(Example 3)
The diameters produced in Example 2 above were 8 mm (for forming carbide substrates C-1 to C-3), 13 mm (for forming carbide substrates C-4 to C-6), and 26 mm (for carbide substrates C-). 7, for C-8 formation), from these three types of round bar sintered bodies, the diameter x length of the groove forming portion is 4 mm x 13 mm (by grinding), respectively. Carbide substrates D-1 to D-3), 8 mm × 22 mm (Carbide substrates D-4 to D-6), and 16 mm × 45 mm (Carbide substrates D-7, D-8), In addition, 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 edges of these carbide substrates (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone and dried, and the arc ion plating apparatus shown in FIG. 1 is also used. In the same conditions as in Example 1 above, the target interval shown in Table 10 in which the Al highest content point and Al minimum content point of the target composition shown in Table 10 are alternately shown along the layer thickness direction. And a component concentration distribution structure in which the Al content continuously changes from the highest Al content point to the lowest Al content point, and from the lowest Al content point to the highest Al content point. By depositing a hard coating layer having a target overall layer thickness shown in FIG. 10, drills made of the surface coated cemented carbide of the present invention (hereinafter referred to as the present coated carbide drill) 1-8 as the coated carbide tool of the present invention. Were manufactured respectively.
[0034]
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, as shown in FIG. The target composition and target layer thickness shown in Table 11 (hard coating layers constituting the present invention coated carbide drills 1 to 8, respectively) were charged in a normal arc ion plating apparatus and under the same conditions as in Example 1 above. By depositing a hard coating layer composed of a (Cr, Al) N layer having the same composition as the Al highest content point and the target layer thickness) and having substantially no composition change along the layer thickness direction. Comparative surface coated carbide drills (hereinafter referred to as comparative coated carbide drills) 1 to 8 as comparative coated carbide tools were manufactured.
[0035]
Next, of the present invention coated carbide drills 1-8 and comparative coated carbide drills 1-8, for the present invention coated carbide drills 1-3 and comparative coated carbide drills 1-3,
Work material: Plane dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SKD61 plate material,
Cutting speed: 20 m / min. ,
Feed: 0.2mm / rev,
Hole depth: 8mm
About the wet high feed drilling test of the tool steel under the conditions of the present invention, the coated carbide drills 4-6 of the present invention and the comparative coated carbide drills 4-6,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SCM440 plate material,
Cutting speed: 45 m / min. ,
Feed: 0.35mm / rev,
Hole depth: 15mm
About the wet high feed drilling test of alloy steel under the conditions of the present invention, the coated carbide drills 7 and 8 of the present invention and the comparative coated carbide drills 7 and 8
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS / FC300 plate material,
Cutting speed: 60 m / min. ,
Feed: 0.6mm / rev,
Hole depth: 30mm
Each of the wet high-feed drilling tests of cast iron under the conditions of The number of drilling operations was measured. The measurement results are shown in Tables 10 and 11, respectively.
[0036]
[Table 10]

[0037]
[Table 11]

[0038]
The present coated carbide tips 1 to 16, the present coated carbide end mills 1 to 8, the present coated carbide drills 1 to 8 and the comparative coated carbide tools obtained as a result of the present coated carbide tool. About the hard coating layers constituting the comparative coated carbide tips 1 to 16, the comparative coated carbide end mills 1 to 8, and the comparative coated carbide drills 1 to 8, respectively, containing Cr and Al components along the layer thickness direction The amount was measured using an Auger spectroscopic analyzer, and the content of Cr and Al components at each measurement point was examined from the measurement results. In the coated carbide tool of the present invention, the highest Al content point and the lowest Al content point were obtained. Are alternately present at substantially the same composition and interval as the target value, and the Al content is linked from the Al highest content point to the Al lowest content point, and from the Al lowest content point to the Al highest content point. Manner to have a varying component concentration distribution structure is confirmed also showed an overall average layer thickness even entire target layer thickness substantially the same value of the hard layer. On the other hand, in the hard coating layer of the comparative coated carbide tool, no composition change is observed along the layer 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. It was confirmed to show.
[0039]
【The invention's effect】
From the results shown in Tables 3 to 11, the hard coating layer is alternately predetermined in the layer thickness direction with Al highest content points having relatively high temperature hardness and heat resistance and Al minimum content points having high strength. The present invention has a component concentration distribution structure that repeatedly exists at intervals and in which the Al content continuously changes from the Al highest content point to the Al lowest content point and from the Al lowest content point to the Al highest content point. All coated carbide tools have excellent chipping resistance even when cutting various steels and cast iron under heavy cutting conditions such as high cutting and high feed with high mechanical impact. In contrast, the hard coating layer was excellent in the comparative coated carbide tool composed of the (Cr, Al) N layer having substantially no composition change along the thickness direction. High temperature hardness and heat resistance Of the, because of inferior strength, chipping occurs and this is apparent that lead to a relatively short time service life due.
As described above, the coated carbide tool of the present invention can be used not only for cutting under normal conditions, but also for cutting various steels and cast irons. Even under heavy cutting conditions, it exhibits excellent chipping resistance and excellent wear resistance over a long period of time. It can respond satisfactorily.
[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 normal arc ion plating apparatus used for forming a hard coating layer constituting a comparative coated carbide tool.

Claims

Surface-coated carbide formed by physical vapor deposition of a hard coating layer composed of a composite nitride layer of Cr and Al on the surface of a tungsten carbide base cemented carbide substrate or a titanium carbonitride cermet substrate with an overall average layer thickness of 1 to 15 μm. In alloy cutting tools,
In the hard coating layer, the highest Al content point and the lowest Al content point are present alternately at predetermined intervals along the thickness direction, and the lowest Al content point, the Al content point, from the highest Al content point. A component concentration distribution structure in which the Al content continuously changes from the lowest content point to the Al highest content point,
Furthermore, the Al highest content point is the composition formula: (Cr _1-X Al _X ) N (wherein X is 0.40 to 0.60 in atomic ratio),
The Al minimum content point is a composition formula: (Cr _1-Y Al _Y ) N (wherein Y represents 0.05 to 0.30 in atomic ratio),
And the interval between the Al highest content point and the Al lowest content point adjacent to each other is 0.01 to 0.1 μm,
A surface-coated cemented carbide cutting tool that exhibits excellent chipping resistance under hard cutting conditions characterized by