JP3969260B2

JP3969260B2 - Surface coated cemented carbide cutting tool with excellent chipping resistance with hard coating layer under high speed heavy cutting conditions

Info

Publication number: JP3969260B2
Application number: JP2002271298A
Authority: JP
Inventors: 秀充高岡; 惠滋中村
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2002-09-18
Filing date: 2002-09-18
Publication date: 2007-09-05
Anticipated expiration: 2022-09-18
Also published as: JP2004106108A

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と高靭性を有し、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も、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：（Ａｌ_1-(X+Z)Ｃｒ_XＴｉ_Z）Ｎ（ただし、原子比で、Ｘは０．１０〜０．２５、Ｚ：０．０５〜０．１５を示す）を満足するＡｌとＣｒとＴｉの複合窒化物［以下、（Ａｌ，Ｃｒ，Ｔｉ）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超硬工具が提案され、かかる被覆超硬工具が、硬質被覆層を構成する前記（Ａｌ，Ｃｒ，Ｔｉ）Ｎ層がＡｌによる高温硬さと耐熱性、さらにＣｒとＴｉの共存含有による強度を有することから、各種の鋼や鋳鉄などの連続切削や断続切削加工に用いられることも知られている（例えば、非特許文献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４００℃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Ａｌ−Ｃｒ−Ｔｉ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：１３５Ａ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（Ａｌ，Ｃｒ，Ｔｉ）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、非特許文献１参照）。
【０００５】
【非特許文献１】
平成１４年４月２２〜２６日開催の「インターナショナルコンファレンスオンメタラジカルコーティングアンドシィンフィルムス」で発表された「プロパーティスアンドカッティングパフォーマンスオブターナリイナイトライドコーティングデポジテッドバイニュウプラズマエンハンスドアーク−カソード」と題する論文
【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、切削加工は高速化の傾向を強め、かつ高切り込みや高送りなどの重切削条件での切削加工を余儀なくされる傾向にあるが、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、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（Ａｌ，Ｃｒ，Ｔｉ）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硬さと耐熱性、さらに強度を有するが、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Ａｌ最高含有点形成用Ａｌ−Ｃｒ−Ｔｉ合金、他方側にＡｌ最低含有点形成用Ａｌ−Ｃｒ−Ｔｉ合金をいずれもカソード電極（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に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（Ａｌ，Ｃｒ，Ｔｉ）Ｎ層を形成すると、この結果の（Ａｌ，Ｃｒ，Ｔｉ）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Ａｌ−Ｃｒ−Ｔｉ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、また前記超硬基体が上記の他方側のＡｌ−Ｃｒ−Ｔｉ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成分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（Ａｌ，Ｃｒ，Ｔｉ）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Ａｌ−Ｃｒ−Ｔｉ合金におけるＣｒおよびＴｉ含有量を上記の従来（Ａｌ，Ｃｒ，Ｔｉ）Ｎ層形成用Ａｌ−Ｃｒ−Ｔｉ合金のＣｒおよびＴｉ含有量に相当するものとし、同他方側のカソード電極（蒸発源）であるＡｌ−Ｃｒ−Ｔｉ合金におけるＣｒ含有量を上記の従来Ａｌ−Ｃｒ−Ｔｉ合金のＣｒ含有量に比して相対的に高いものとすると共に、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Ａｌ最高含有点が、組成式：（Ａｌ_1-(X+Z)Ｃｒ_XＴｉ_Z）Ｎ（ただし、原子比で、Ｘは０．１０〜０．２５、Ｚ：０．０５〜０．１５を示す）、
上記Ａｌ最低含有点が、組成式：（Ａｌ_1-(Y+Z)Ｃｒ_YＴｉ_Z）Ｎ（ただし、原子比で、Ｙは０．４０〜０．６０、Ｚ：０．０５〜０．１５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、上記の従来（Ａｌ，Ｃｒ，Ｔｉ）Ｎ層のもつ高温硬さと耐熱性に相当するすぐれた高温硬さと耐熱性を示し、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、相対的にＣｒ含有量の高いものとなるので、Ｔｉ成分との共存含有と相俟って一段と高い強度が確保され、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すぐれた高温硬さと耐熱性を保持した状態で一段とすぐれた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（Ａｌ，Ｃｒ，Ｔｉ）Ｎ層からなる被覆超硬工具は、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、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、（Ａｌ，Ｃｒ，Ｔｉ）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：（Ａｌ_1-(X+Z)Ｃｒ_XＴｉ_Z）Ｎ（ただし、原子比で、Ｘは０．１０〜０．２５、Ｚ：０．０５〜０．１５を示す）、上記Ａｌ最低含有点が、組成式：（Ａｌ_1-(Y+Z)Ｃｒ_YＴｉ_Z）Ｎ（ただし、原子比で、Ｙは０．４０〜０．６０、Ｚ：０．０５〜０．１５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、
高速重切削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（Ａｌ，Ｃｒ，Ｔｉ）ＮにおけるＣｒ成分は強度を向上させ、同Ａｌ成分は高温硬さと耐熱性を向上させ、さらに同Ｔｉ成分はＣｒ成分との共存において一段と強度を向上させる作用があり、したがってＣｒおよびＴｉ成分の含有割合が低くなればなるほど高温硬さと耐熱性は向上し、高熱発生を伴う高速切削に適合したものになるが、Ｃｒの含有割合を示すＸ値がＡｌとＴｉの合量に占める割合（原子比）で０．１０未満、またＴｉの含有割合を示すＺ値が同０．０５未満になると、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０．２５を越え、また同Ｚ値が０．１５を越えると、相対的にＡｌ含有量が低下し、所定のすぐれた高温硬さと耐熱性を確保することができなくなることから、Ｘ値を０．１０〜０．２５、Ｚ値を０．０５〜０．１５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すぐれた高温硬さと耐熱性を有するが、反面相対的に強度が不十分であるため、このＡｌ最高含有点の強度不足を補う目的で、相対的にＣｒ含有割合が高く、一方Ａｌ含有量が低く、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Ｃｒの割合を示すＹ値がＡｌおよびＴｉ成分との合量に占める割合（原子比）で０．４０未満では、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０．６０を越えると、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ることから、Ａｌ最低含有点でのＣｒの割合を示すＹ値を０．４０〜０．６０と定めた。
Ａｌ最低含有点におけるＴｉ成分も、上記の通りＣｒ成分との共存で強度を向上させ、耐チッピング性を向上させる目的で含有するものであり、したがってＺ値が０．０５未満では所望の強度向上効果が得られず、一方Ｚ値が０．１５を越えるとＡｌ最低含有点での高温硬さと耐熱性に低下傾向が現れるようになり、摩耗促進の原因となることから、Ｚ値を０．０５〜０．１５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温硬さと耐熱性、さらに高強度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および耐熱性不足が層内に局部的に現れ、これが原因で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０．８〜２．９μｍ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６６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・ＳＮＭＧ１２０４１２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７８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：０．０５のホーニング加工を施してＩＳＯ規格・ＳＮＭＧ１２０４１２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に、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最高含有点形成用Ａｌ−Ｃｒ−Ｔｉ合金、他方側のカソード電極（蒸発源）としてＡｌ最低含有点形成用Ａｌ−Ｃｒ−Ｔｉ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Ｔｉ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、かつカソード電極の前記金属Ｔｉとアノード電極との間に１２０Ａ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Ｔｉ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−７０Ｖの直流バイアス電圧を印加し、かつそれぞれのカソード電極(前記Ａｌ最高含有点形成用Ａｌ−Ｃｒ−Ｔｉ合金およびＡｌ最低含有点形成用Ａｌ−Ｃｒ−Ｔｉ合金)とアノード電極との間に９０Ａ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最高含有点とＡｌ最低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成分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Ａｌ−Ｃｒ−Ｔｉ合金を装着し、またボンバート洗浄用金属Ｔｉ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４００℃に加熱した後、前記超硬基体に−９００Ｖの直流バイアス電圧を印加し、カソード電極の前記金属Ｔｉとアノード電極との間に１３５Ａ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Ｔｉ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、前記超硬基体に印加するバイアス電圧を−２００Ｖに下げて、前記カソード電極とアノード電極との間に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（Ａｌ，Ｃｒ，Ｔｉ）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・Ｓ２０Ｃの丸棒、
切削速度：３３５ｍ／ｍｉｎ．、
切り込み：６．５ｍｍ、
送り：０．１０ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での炭素鋼の乾式連続高速高切り込み切削加工試験、
被削材：ＪＩＳ・ＳＳ４００の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３４０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．６２ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での軟鋼の乾式断続高速高送り切削加工試験、さらに、
被削材：ＪＩＳ・ＦＣ２００の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３４５ｍ／ｍｉｎ．、
切り込み：６．０ｍｍ、
送り：０．１０ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での鋳鉄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７に示した。
【００１９】
【表１】

【００２０】
【表２】

【００２１】
【表３】

【００２２】
【表４】

【００２３】
【表５】

【００２４】
【表６】

【００２５】
【表７】

【００２６】
（実施例２）
原料粉末として、平均粒径：４．５μｍ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２．０μｍ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８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６６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８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。
【００２７】
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９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９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成分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９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。
【００２８】
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１０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（Ａｌ，Ｃｒ，Ｔｉ）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。
【００２９】
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：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＦＣ２００の板材、
切削速度：３５０ｍ／ｍｉｎ．、
軸方向切り込み：１０ｍｍ、
径方向切り込み：１．８ｍｍ、
テーブル送り：７００ｍｍ／分、
の条件での鋳鉄の湿式高速切り込み側面切削加工試験、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：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＳ４００の板材、
切削速度：３５０ｍ／ｍｉｎ．、
軸方向切り込み：２０ｍｍ、
径方向切り込み：３ｍｍ、
テーブル送り：６５０ｍｍ／分、
の条件での軟鋼の湿式高速高切り込み側面切削加工試験、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：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ２０Ｃの板材、
切削速度：３３０ｍ／ｍｉｎ．、
軸方向切り込み：１１ｍｍ、
径方向切り込み：１．５ｍｍ、
テーブル送り：１６５０ｍｍ／分、
の条件での炭素鋼の湿式高速高送り側面切削加工試験をそれぞれ行い、いずれの切削加工試験（水溶性切削油使用）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に至るまでの切削長を測定した。この測定結果を表９、１０にそれぞれ示した。
【００３０】
【表８】

【００３１】
【表９】

【００３２】
【表１０】

【００３３】
（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。
【００３４】
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１１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１１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成分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１１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。
【００３５】
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１２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（Ａｌ，Ｃｒ，Ｔｉ）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。
【００３６】
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：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＳ４００の板材、
切削速度：２７０ｍ／ｍｉｎ．、
送り：０．５ｍｍ／ｒｅｖ、
穴深さ：８ｍｍ
の条件での軟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：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ１５Ｃの板材、
切削速度：２６０ｍ／ｍｉｎ．、
送り：０．６ｍｍ／ｒｅｖ、
穴深さ：１３ｍｍ
の条件での炭素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：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＦＣ２００の板材、
切削速度：２８０ｍ／ｍｉｎ．、
送り：０．６ｍｍ／ｒｅｖ、
穴深さ：２２ｍｍ
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、いずれの湿式高速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１１、１２にそれぞれ示した。
【００３７】
【表１１】

【００３８】
【表１２】

【００３９】
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におけるＡｌ最高含有点とＡｌ最低含有点の組成、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の硬質被覆層について、厚さ方向に沿ってＡｌ、Ｃｒ、Ｔｉの含有量をオージェ分光分析装置を用いて測定したところ、本発明被覆超硬工具の硬質被覆層では、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成分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。一方前記従来被覆超硬工具の硬質被覆層で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。
【００４０】
【発明の効果】
表３〜１２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最高含有点と相対的に高強度を有する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成分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（Ａｌ，Ｃｒ，Ｔｉ）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]
BACKGROUND OF THE INVENTION
In this invention, the hard coating layer has high strength and high toughness, and is excellent in high-temperature hardness and heat resistance. Therefore, high-speed cutting such as various steels and cast irons is particularly suitable for high cutting and high mechanical impact. 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 even when performed under heavy cutting conditions such as high feed.
[0002]
[Prior art]
In general, coated carbide tools are used for throwaway inserts that are detachably attached to the tip of a cutting tool for drilling and cutting of various materials such as steel and cast iron, and for flat cutting. There are drills, miniature drills, solid type end mills used for chamfering, grooving, shoulder processing, etc. Also, the throwaway tip is detachably attached and cutting is performed in the same way as the solid type end mill Throwaway end mill tools are known.
[0003]
Further, as a coated 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 carbide substrate). ) On the surface of the composition formula: (Al _{1-(X + Z)} Cr _x Ti _z ) N (wherein, X is 0.10 to 0.25, Z: 0.05 to 0.15 in atomic ratio) A hard coating layer composed of a composite nitride of Al, Cr and Ti (hereinafter referred to as (Al, Cr, Ti) N) layer satisfying the following conditions: physical vapor deposition with an average layer thickness of 1 to 15 μm A hard tool has been proposed, and in such a coated carbide tool, the (Al, Cr, Ti) N layer constituting the hard coating layer has high-temperature hardness and heat resistance due to Al, and also has strength due to coexistence of Cr and Ti. Used for continuous cutting and intermittent cutting of various steels and cast iron. It is also known (e.g., see Non-Patent Document 1).
[0004]
Furthermore, the above-mentioned coated carbide tool is, for example, the above-mentioned carbide substrate is inserted into an arc ion plating apparatus which is one type of physical vapor deposition apparatus schematically shown in FIG. For example, an arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) on which an Al—Cr—Ti alloy having a predetermined composition is set, for example, at a current of 135 A, while being heated to a temperature of 400 ° C. At the same time, nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of, for example, 2 Pa, while the cemented carbide substrate has a surface of the cemented carbide substrate under the condition that a bias voltage of, for example, −100 V is applied. In addition, it is also known to be manufactured by vapor-depositing a hard coating layer composed of the (Al, Cr, Ti) N layer (see, for example, Non-Patent Document 1).
[0005]
[Non-Patent Document 1]
Paper entitled "Propartments and Cutting Performance of Turner Nitride Coating Deposited by New Plasma Enhanced Arc-Cathode" published at "International Conference on Metaradical Coating and Thin Films" held from April 22 to 26, 2002 [0006]
[Problems to be solved by the invention]
In recent years, there has been a remarkable increase in the performance of cutting equipment, while there has been a strong demand for labor saving and energy saving and further cost reduction for cutting work. Although there is a tendency to be forced to perform cutting under heavy cutting conditions such as high feed, there is no problem when using the above conventional coated carbide tools under normal cutting conditions. Is performed at high speed and under heavy cutting conditions such as high cutting and high feed with high mechanical impact, chipping (microcracking) is likely to occur, especially due to insufficient strength of the hard coating layer. The current situation is that the service life is reached in a short time.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed the above-mentioned conventional coated carbide tool in order to develop a coated carbide tool that exhibits excellent chipping resistance with a hard coating layer particularly in high-speed heavy cutting. As a result of conducting research, focusing on the hard coating layer
(A) The (Al, Cr, Ti) N layer constituting the conventional coated carbide tool formed using the arc ion plating apparatus shown in FIG. 2 is substantially uniform over the entire thickness. Arc ion plating with a structure as shown in FIG. 1 (a) and a schematic front view, for example. An apparatus, that is, a rotating table for mounting a cemented carbide substrate is provided at the center of the apparatus, the Al-Cr-Ti alloy for forming the Al highest content point is formed on one side, and the Al for forming the lowest Al content point is formed on the other side across the rotating table. -An arc ion plating apparatus in which all of the Cr-Ti alloy is arranged as a cathode electrode (evaporation source) is used, and the outer periphery of the apparatus is positioned on the rotary table at a predetermined distance in the radial direction from the central axis. A plurality of cemented carbide substrates are attached in a ring shape along the surface of the substrate, and in this state, the atmosphere inside the apparatus is changed to a nitrogen atmosphere to rotate the rotary table, and the thickness of the hard coating layer formed by vapor deposition is made uniform. While rotating the hard substrate itself, an arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides to form an (Al, Cr, Ti) N layer on the surface of the carbide substrate. Then, in the resulting (Al, Cr, Ti) N layer, the carbide substrate disposed in a ring shape on the rotary table is the cathode electrode (evaporation source) of the above-mentioned one side Al—Cr—Ti alloy. The highest Al content point is formed in the layer when it is closest to the layer, and the lowest Al content point is present in the layer when the cemented carbide substrate is closest to the cathode electrode of the other Al-Cr-Ti alloy. Formed above times The rotation of the table causes the Al highest content point and the Al lowest content point to appear alternately in the layer thickness direction along the layer thickness, and the Al minimum content point, the Al minimum content point from the Al highest content point. It has a component concentration distribution structure in which the Al component content continuously changes from the point to the Al highest content point.
[0008]
(B) In the (Al, Cr, Ti) N layer of the repeated continuous change component concentration distribution structure of (a) above, Cr in the Al—Cr—Ti alloy which is the cathode electrode (evaporation source) on one side facing each other The Ti content corresponds to the Cr and Ti content of the conventional Al—Cr—Ti alloy for forming an Al layer (Al, Cr, Ti) N layer, and Al— which is the cathode electrode (evaporation source) on the other side. The Cr content in the Cr-Ti alloy is relatively higher than the Cr content in the conventional Al-Cr-Ti alloy, and the rotational speed of the turntable on which the carbide substrate is mounted is controlled. do it,
The highest Al content point is the composition formula: (Al _{1-(X + Z)} Cr _x Ti _z ) N (wherein X is 0.10 to 0.25 in terms of atomic ratio, Z: 0.05 to 0.00. 15)
The Al minimum content point is the composition formula: (Al _{1-(Y + Z)} Cr _Y Ti _Z ) N (however, in terms of atomic ratio, Y is 0.40 to 0.60, Z is 0.05 to 0. 15)
And the interval in the thickness direction of the adjacent Al highest content point and Al lowest content point adjacent to each other is 0.01 to 0.1 μm,
The Al highest content point portion exhibits excellent high temperature hardness and heat resistance corresponding to the high temperature hardness and heat resistance of the conventional (Al, Cr, Ti) N layer, while the Al minimum content point portion Since the Al content is lower than the highest Al content point and the Cr content is relatively high, a higher strength is ensured in combination with the coexistence with the Ti component. Since the distance between the content point and the Al minimum content point is extremely small, the layer has excellent strength as a whole layer while maintaining excellent high temperature hardness and heat resistance. The coated carbide tool composed of the (Al, Cr, Ti) N layer having such a configuration is particularly suitable for cutting various steels and cast irons at high speeds, such as high cutting and high feed with high mechanical impact. Line with cutting conditions When Tsu 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 on the basis of the above research results. A hard coating layer made of an (Al, Cr, Ti) N layer is physically applied on the surface of a cemented carbide substrate with an overall average layer thickness of 1 to 15 μm. In coated carbide tools formed by vapor deposition,
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, the composition _{formula: (Al 1- (X + Z} ) Cr X Ti Z) N ( provided that an atomic ratio, X is 0.10 to 0.25, Z: 0.05 to 0.15), the minimum Al content point is the composition formula: (Al _{1-(Y + Z)} Cr _Y Ti _Z ) N (however, in terms of atomic ratio, Y is 0.40 to 0.60, Z : 0.05 to 0.15)
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.
This is characterized by a coated carbide tool that exhibits excellent chipping resistance under high-speed 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 Al highest content point The Cr component in (Al, Cr, Ti) N with the highest Al content point improves strength, the Al component improves high-temperature hardness and heat resistance, and the Ti component is Cr. There is an action to further improve the strength in the coexistence with the component, so the lower the content ratio of Cr and Ti component, the higher the high temperature hardness and heat resistance, the more suitable for high speed cutting with high heat generation, When the X value indicating the Cr content is less than 0.10 in terms of the total amount of Al and Ti (atomic ratio), and when the Z value indicating the Ti content is less than 0.05, the strength is high. Even if the lowest Al content point exists adjacently, a decrease in the strength of the layer itself is inevitable, and as a result, chipping or the like is likely to occur, while the X value exceeds 0.25 and the Z value is Above 0.15, relative Since the Al content is lowered and it becomes impossible to ensure a predetermined excellent high temperature hardness and heat resistance, the X value is set to 0.10 to 0.25, and the Z value is set to 0.05 to 0.15. .
[0011]
(B) Composition of the lowest Al content point As described above, the highest Al content point has relatively high temperature hardness and heat resistance, but on the other hand, the strength is relatively insufficient. In order to make up for the shortage, the Al content is relatively high, while the Al content is low, and thus the Al minimum content point having high strength is alternately interposed in the thickness direction. If the Y value indicating the ratio of the proportion of the total amount of the Al and Ti components (atomic ratio) is less than 0.40, the desired excellent strength cannot be ensured, while the Y value is 0.60. If it exceeds, the desired minimum high temperature hardness and heat resistance cannot be achieved at the Al minimum content point, so the Y value indicating the proportion of Cr at the Al minimum content point is set to 0.40 to 0.60. .
The Ti component at the Al minimum content point is also included for the purpose of improving the strength by coexisting with the Cr component and improving the chipping resistance as described above. Therefore, if the Z value is less than 0.05, the desired strength is improved. On the other hand, if the Z value exceeds 0.15, the high temperature hardness and the heat resistance at the Al minimum content point tend to decrease, and this causes acceleration of wear. It was set as 05-0.15.
[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. Heat resistance and higher strength cannot be ensured, and if the distance exceeds 0.1 μm, each point has a defect, that is, if Al is the highest content point, the strength is insufficient, and if Al is the lowest content point, the temperature is high. Insufficient hardness and heat resistance appear locally in the layer, which makes it easier for chipping to occur and promotes the progress of wear. Therefore, the interval is set to 0.01 to 0.1 μm. It was.
[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
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 0.8 to 2.9 μm are prepared as raw material powders. Was blended in the composition shown in Table 1, wet-mixed for 66 hours with a ball mill, dried, and pressed into a green compact at a pressure of 100 MPa. Sintered under the condition of holding at 1 ° C. for 1 hour, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.03, and a cemented carbide made of a WC-based cemented carbide having an ISO standard / SNMG120212 chip shape Bases A1 to A10 were 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 78 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. After sintering, the cutting edge portion was subjected to a honing process of R: 0.05, and ISO standard / SNMG120212. TiCN-based cermet carbide substrates B1 to B6 having the following chip shape were formed.
[0016]
Next, each of the above-mentioned carbide substrates A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, and then the central axis is placed on the rotary table in the arc ion plating apparatus shown in FIG. Al-Cr-Ti alloy for forming the highest Al content point with various component compositions as a cathode electrode (evaporation source) on one side along the outer periphery at a predetermined distance in the radial direction from the other side As the cathode electrode (evaporation source) on the side, the Al-Cr-Ti alloy for forming the lowest Al content point is placed across the rotary table, and the bombard cleaning metal Ti is also mounted. A DC bias voltage of −1000 V is applied to a carbide substrate that rotates while rotating on the rotary table after heating the inside of the apparatus to 500 ° C. while maintaining a vacuum of 0.5 Pa or less. And applying a current of 120 A between the metal Ti of the cathode electrode and the anode electrode to generate an arc discharge, thereby cleaning the surface of the carbide substrate with Ti bombardment, and then supplying nitrogen gas as a reaction gas into the apparatus. Introducing a reaction atmosphere of 2 Pa, applying a DC bias voltage of −70 V to the carbide substrate rotating while rotating on the rotary table, and applying each cathode electrode (Al— An arc discharge is generated by flowing a current of 90 A between the Cr-Ti alloy and the Al-Cr-Ti alloy for forming the lowest Al content point) and the anode electrode, thereby forming a layer thickness direction on the surface of the cemented carbide substrate. And the Al highest content point and the Al lowest content point of the target composition shown in Tables 3 and 4 are alternately present at the target intervals shown in Tables 3 and 4 alternately, and the Al It has a component concentration distribution structure in which the Al component content continuously changes from the highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point, and also the targets shown in Tables 3 and 4 By vapor-depositing a hard coating layer of the entire layer thickness, 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 are produced, respectively. did.
[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. Attached are Al-Cr-Ti alloys having various components as cathode electrodes (evaporation sources), and are also equipped with bombard cleaning metal Ti. First, the apparatus is evacuated to a vacuum of 0.5 Pa or less. While being held, the inside of the apparatus was heated to 400 ° C. with a heater, a DC bias voltage of −900 V was applied to the cemented carbide substrate, and a current of 135 A was passed between the metal Ti of the cathode electrode and the anode electrode. An arc discharge is generated, and the surface of the carbide substrate is cleaned by Ti bombardment. Then, nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 2 Pa. The bias voltage applied to the substrate is lowered to -200 V, and arc discharge is generated between the cathode electrode and the anode electrode, so that the surfaces of the cemented carbide substrates A1 to A10 and B1 to B6 are formed on the surfaces of Tables 5 and 6, respectively. By depositing a hard coating layer made of an (Al, Cr, Ti) N layer having a target composition and a target layer thickness shown in FIG. Conventional surface-coated cemented carbide throwaway tips (hereinafter referred to as conventional coated carbide tips) 1 to 16 as hard tools were produced, respectively.
[0018]
Next, with the present invention coated carbide tips 1-16 and conventional coated carbide tips 1-16, in a state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / S20C round bar,
Cutting speed: 335 m / min. ,
Incision: 6.5 mm,
Feed: 0.10 mm / rev. ,
Cutting time: 5 minutes
Dry continuous high-speed high-cut cutting test of carbon steel under the conditions of
Work material: JIS / SS400 lengthwise equidistant 4 round bars with flutes,
Cutting speed: 340 m / min. ,
Incision: 1.5mm,
Feed: 0.62 mm / rev. ,
Cutting time: 5 minutes
Dry intermittent high-speed high-feed cutting test of mild steel under the conditions of
Work material: JIS ・ FC200 lengthwise equidistant 4 round bars with flutes,
Cutting speed: 345 m / min. ,
Cutting depth: 6.0 mm,
Feed: 0.10 mm / rev. ,
Cutting time: 5 minutes
A dry interrupted high-speed 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 Table 7.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
[Table 3]

[0022]
[Table 4]

[0023]
[Table 5]

[0024]
[Table 6]

[0025]
[Table 7]

[0026]
(Example 2)
As raw material powders, medium coarse WC powder having an average particle size of 4.5 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, 2.0 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 in the blending composition shown in Table 8, further added with wax, ball milled in acetone for 66 hours, dried under reduced pressure, and then shaped into a predetermined shape at a pressure of 100 MPa. The 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. After holding at temperature for 1 hour, sintering under furnace cooling conditions Three types of sintered carbide rod-forming bodies for forming a cemented carbide substrate having diameters of 8 mm, 13 mm, and 26 mm were formed, and further, the above three types of round rod sintered bodies were ground and shown in Table 8. In combination, the carbide blades have a four-blade square shape with diameters and lengths of the cutting edges of 6 mm × 13 mm, 10 mm × 22 mm, and 20 mm × 45 mm, respectively, and a twist angle of 30 degrees. Substrates (end mills) C-1 to C-8 were produced.
[0027]
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 9 along the layer thickness direction alternately and repeatedly exist at the target interval shown in Table 9, and It has a component concentration distribution structure in which the Al component 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, and is also the entire target shown in Table 9 By vapor-depositing a hard coating layer having a layer 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.
[0028]
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. And having the target composition and target layer thickness shown in Table 10 under the same conditions as in Example 1, and having substantially no composition change along the layer thickness direction (Al, Cr, Ti) ) End coat mills made of conventional surface-coated cemented carbide (hereinafter referred to as conventional coated cemented carbide end mills) 1 to 8 as conventional coated cemented carbide tools were produced by vapor-depositing a hard coating layer consisting of N layers.
[0029]
Next, of the present invention coated carbide end mills 1-8 and conventional coated carbide end mills 1-8, the present invention coated carbide end mills 1-3 and conventional coated carbide end mills 1-3 are as follows:
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / FC200 plate material,
Cutting speed: 350 m / min. ,
Axial cut: 10 mm
Radial notch: 1.8mm,
Table feed: 700mm / min,
For the cast iron wet high speed cutting side cutting test, the present coated carbide end mills 4-6 and the conventional coated carbide end mills 4-6,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SS400 plate material,
Cutting speed: 350 m / min. ,
Axial cut: 20mm,
Radial notch: 3mm,
Table feed: 650 mm / min,
For wet steel high-speed high-cut side cutting test of mild steel under the conditions of the present invention, the coated carbide end mills 7 and 8 of the present invention and the conventional coated carbide end mills 7 and 8
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / S20C plate material,
Cutting speed: 330 m / min. ,
Axial cut: 11 mm
Radial notch: 1.5mm,
Table feed: 1650 mm / min,
We performed wet high-speed, high-feed side cutting tests on carbon steel under the above conditions, and the flank wear width of the outer peripheral edge of the cutting edge was used as a guide for the service life in any cutting test (using water-soluble cutting oil). The cutting length up to 0.1 mm was measured. The measurement results are shown in Tables 9 and 10, respectively.
[0030]
[Table 8]

[0031]
[Table 9]

[0032]
[Table 10]

[0033]
(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.
[0034]
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 11 in which the Al highest content point and Al minimum content point of the target composition shown in Table 11 are alternately shown along the layer thickness direction. And having a component concentration distribution structure in which the Al component content continuously changes from the highest Al content point to the lowest Al content point, from the lowest Al content point to the highest Al content point, and By vapor-depositing a hard coating layer having a target overall layer thickness shown in Table 11, a drill made of the surface-coated cemented carbide of the present invention (hereinafter referred to as the present coated carbide drill) 1 to 1 as the coated carbide tool of the present invention. 8 each manufactured .
[0035]
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 sample was charged into a normal arc ion plating apparatus, had the target composition and target layer thickness shown in Table 12 under the same conditions as in Example 1, and substantially changed in composition along the layer thickness direction. Conventional surface-coated cemented carbide drills (hereinafter referred to as conventional coated carbide drills) 1 to 8 as conventional coated carbide tools are deposited by vapor-depositing a hard coating layer comprising no (Al, Cr, Ti) N layer. Were manufactured respectively.
[0036]
Next, of the present invention coated carbide drills 1-8 and conventional coated carbide drills 1-8, the present invention coated carbide drills 1-3 and conventional coated carbide drills 1-3,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SS400 plate material,
Cutting speed: 270 m / min. ,
Feed: 0.5mm / rev,
Hole depth: 8mm
About the wet high speed high feed drilling test of mild steel under the conditions of the present invention, the coated carbide drills 4-6 of the present invention and the conventional coated carbide drills 4-6,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / S15C plate,
Cutting speed: 260 m / min. ,
Feed: 0.6mm / rev,
Hole depth: 13mm
With respect to the carbon steel wet high-speed high-feed drilling test, the coated carbide drills 7 and 8 of the present invention and the conventional coated carbide drills 7 and 8,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / FC200 plate material,
Cutting speed: 280 m / min. ,
Feed: 0.6mm / rev,
Hole depth: 22mm
Wet high-speed high-feed drilling machining test of cast iron under the conditions of each, and in any wet high-speed drilling machining test (using water-soluble cutting oil), the flank wear width of the cutting edge surface reaches 0.3 mm The number of drilling processes up to was measured. The measurement results are shown in Tables 11 and 12, respectively.
[0037]
[Table 11]

[0038]
[Table 12]

[0039]
In the hard coating layer which comprises this invention coated carbide tips 1-16, this invention coated carbide end mills 1-8, and this invention coated carbide drills 1-8 as this invention coated carbide tool obtained as a result. Composition of Al highest content point and Al lowest content point, and conventionally coated carbide tips 1-16 as conventionally coated carbide tools, conventionally coated carbide end mills 1-8, and hard coating of conventionally coated carbide drills 1-8 About the layer, when the content of Al, Cr, Ti was measured along the thickness direction using an Auger spectroscopic analyzer, in the hard coating layer of the coated carbide tool of the present invention, the highest Al content point and the lowest Al content point Are alternately and repeatedly present at substantially the same composition and interval as the target value, and the Al content from the Al highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point. It was confirmed to have a continuously changing component concentration distribution structure, also showing the overall mean layer thickness even entire target layer thickness substantially the same value of the hard layer. On the other hand, the hard coating layer of the conventional coated carbide tool shows no composition change along the thickness direction, and shows substantially the same composition as the target composition and substantially the same total average layer thickness as the target total layer thickness. It was confirmed.
[0040]
【The invention's effect】
From the results shown in Tables 3 to 12, the Al maximum content point having relatively high temperature hardness and heat resistance and the Al minimum content point having relatively high strength alternate in the layer thickness direction of the hard coating layer. And a 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. The coated carbide tool of the present invention is hard even when cutting various steels and cast irons 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 composed of an (Al, Cr, Ti) N layer in which the hard coating layer has substantially no composition change along the layer thickness direction, whereas the coating layer exhibits excellent chipping resistance The hard coating layer is hot Although the To have heat resistance, since it is inferior in 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 is capable of cutting various steels and cast irons as well as cutting under normal conditions at a high speed and with high mechanical impact. Even under heavy cutting conditions such as high feed and high feed, it exhibits excellent chipping resistance and excellent wear resistance over a long period of time. It can cope with low cost sufficiently 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 to form a hard coating layer constituting a conventional coated carbide tool.

Claims

Surface coating formed by physical vapor deposition of a hard coating layer composed of a composite nitride layer of Al, Cr and Ti 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 cemented carbide 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. It has a component concentration distribution structure in which the Al component content continuously changes from the lowest content point to the Al highest content point,
Furthermore, the Al highest content point, composition _{formula: (Al 1- (X + Z} ) Cr X Ti Z) N ( provided that an atomic ratio, X is 0.10 to 0.25, Z: 0.05 to 0.15), the minimum Al content point is the composition formula: (Al _{1-(Y + Z)} Cr _Y Ti _Z ) N (however, in terms of atomic ratio, Y is 0.40 to 0.60, Z : 0.05 to 0.15)
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 high-speed heavy cutting conditions.