JP4150913B2

JP4150913B2 - Cutting tool made of surface-coated cemented carbide that exhibits excellent wear resistance of hard coating layer under high-speed heavy cutting conditions and manufacturing method thereof

Info

Publication number: JP4150913B2
Application number: JP2003141463A
Authority: JP
Inventors: 和則佐藤
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2003-05-20
Filing date: 2003-05-20
Publication date: 2008-09-17
Anticipated expiration: 2023-05-20
Also published as: JP2004344990A

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層が一段とすぐれた高温硬さと耐熱性、並びに高温強度を有し、したがって各種の鋼や鋳鉄などの切削加工を、特に高い発熱を伴う高速で、かつ高い機械的衝撃を伴な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、硬質被覆層の高温強度不足が原因のチッピング（微少欠け）などが切刃部に発生することなく、すぐれた耐摩耗性を長期に亘って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）およびその製造方法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、前記被削材の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、さらに前記被削材の面削加工や溝加工、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）基超硬合金の超硬基体または炭窒化チタン（以下、ＴｉＣＮで示す）基サーメットの超硬基体（以下、これらの超硬基体を総称して「超硬基体」という）の表面に、
組成式：（Ａｌ_{1 -} _ＦＴｉ_Ｆ）Ｎ（ただし、原子比で、Ｆは０．３５〜０．６０を示す）を満足するＡｌとＴｉの複合窒化物［以下、（Ａｌ，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、前記硬質被覆層を構成する前記（Ａｌ，Ｔｉ）Ｎ層が、Ａｌ成分による高温硬さおよび耐熱性と、Ｔｉ成分による高温強度を有することから、これを蒸着してなる被覆超硬工具が各種の鋼や鋳鉄などの被削材の連続切削や断続切削加工に用いた場合にすぐれた切削性能を発揮することも知られている（例えば特許文献１参照）。
【０００４】
さらに、上記の被覆超硬工具が、例えば図２に概略説明図で示される物理蒸着装置の１種であるアークイオンプレーティング装置に上記の超硬基体を装入し、ヒータで装置内を、例えば５００℃の温度に加熱した状態で、アノード電極と所定組成を有するＡｌ−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：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、前記超硬基体の表面に、上記（Ａｌ，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良く知られるところである。（例えば、特許文献１参照）。
【０００５】
【特許文献１】
特許第２６４４７１０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、切削加工は一段と高速化し、かつ高切り込みや高送りなどの重切削条件での加工を強いられる傾向にあるが、上記の従来被覆超硬工具においては、切削加工を、特に高い発熱を伴う高速で、かつ高い機械的衝撃を伴なう高切り込みや高送りなどの重切削条件で行なうのに用いた場合、硬質被覆層である（Ａｌ，Ｔｉ）Ｎ層の具備する高温強度、さらに高温硬さおよび耐熱性が十分でないために、切刃部にチッピングが発生し易く、かつ前記硬質被覆層の摩耗が一段と促進するようになることから、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、切刃部にチッピングなどの発生なく、すぐれた耐摩耗性を長期に亘って発揮する被覆超硬工具を開発すべく、研究を行った結果、
（ａ）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物理蒸着装置に属するアークイオンプレーティング装置、すなわち装置中央部に超硬基体装着用回転テーブルを設け、前記回転テーブルを挟んで、一方側に相対的にＡｌ含有割合の高いＡｌ−Ｃｒ合金、他方側に相対的にＣｒ含有割合の高いＣｒ−Ａｌ合金をいずれもカソード電極（蒸発源）として対向配置し、さらにいずれも前記Ａｌ−Ｃｒ合金に比してＡｌ含有割合が低く、かつ前記Ｃｒ−Ａｌ合金に比してＣｒ含有割合が低い中間Ａｌ／Ｃｒ合金と中間Ｃｒ／Ａｌ合金を同じくカソード電極（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、前記回転テーブルの中心軸から半径方向に離れた位置に偏心して前記超硬基体を装着し、
この状態で装置内の反応雰囲気を酸素と窒素の混合雰囲気とするが、前記酸素と窒素の装置内への相対導入割合を上記超硬基体の回転移動位置に対応して調整して、前記超硬基体が上記の相対的にＡｌ含有割合の高いＡｌ−Ｃｒ合金のカソード電極に最も接近した時点での反応雰囲気を酸素導入割合が最も高く、窒素導入割合が最も低い、望ましくは酸素の相対導入割合が９０〜９７容量％で、残りが窒素からなる反応雰囲気とする一方、前記超硬基体が上記の相対的にＣｒ含有割合の高いＣｒ−Ａｌ合金のカソード電極に最も接近した時点での反応雰囲気を窒素導入割合が最も高く、酸素導入割合が最も低い、望ましくは窒素の相対導入割合が９０〜９７容量％で、残りが酸素からなる反応雰囲気とすると共に、前記超硬基体が前記Ａｌ−Ｃｒ合金のカソード電極最接近位置から上記中間Ａｌ／Ｃｒ合金のカソード電極最接近位置を経て前記Ｃｒ−Ａｌ合金のカソード電極最接近位置に回転移動する間の反応雰囲気を、酸素の導入割合を連続的に減少させ、これに対応して窒素の導入割合を連続的に増加させる連続変化雰囲気とし、一方前記超硬基体が前記Ｃｒ−Ａｌ合金のカソード電極最接近位置から上記中間Ｃｒ／Ａｌ合金のカソード電極最接近位置を経て前記Ａｌ−Ｃｒ合金のカソード電極最接近位置に回転移動する間の反応雰囲気を、窒素の導入割合を連続的に減少させ、これに対応して酸素の導入割合を連続的に増加させる連続変化雰囲気とし、上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前記超硬基体自体も自転させながら、前記のそれぞれのカソード電極（蒸発源）とアノード電極との間にアーク放電を発生させる条件で、
ＡｌとＣｒの複合酸窒化物［以下、（Ａｌ，Ｃｒ）ＯＮで示す］層を形成すると、
上記超硬基体の表面には、回転テーブル上の中心軸から半径方向に離れた位置に偏心して配置された前記超硬基体が上記の一方側の相対的にＡｌ含有量の高いＡｌ−Ｃｒ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および酸素の最高含有点が形成され、また前記前記超硬基体が上記の他方側の相対的にＣｒ含有量の高いＣｒ−Ａｌ合金のカソード電極に最も接近した時点で層中にＣｒおよび窒素の最高含有点が形成されることから、上記回転テーブルの回転によって層中には厚さ方向にそって前記Ａｌおよび酸素の最高含有点とＣｒおよび窒素の最高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および酸素の最高含有点から前記Ｃｒおよび窒素の最高含有点、前記Ｃｒおよび窒素の最高含有点から前記Ａｌおよび酸素の最高含有点へＡｌと酸素およびＣｒと窒素の含有割合がそれぞれ連続的に変化する成分濃度分布構造をもった（Ａｌ，Ｃｒ）ＯＮ層からなる硬質被覆層が形成されるようになること。
【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）ＯＮ層の形成に際して、例えば対向配置のカソード電極（蒸発源）のそれぞれの組成、並びに装置内で連続変化する反応雰囲気の組成、すなわち酸素と窒素の相互導入割合を調製すると共に、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および酸素の最高含有点が、
組成式：（Ａｌ_1- _ＡＣｒ_Ａ）Ｏ_1-DＮ_D（ただし、原子比で、Ａは０．０５〜０．３５、Ｄは０．０２〜０．１０を示す）、
上記Ｃｒおよび窒素の最高含有点が、
組成式：（Ｃｒ_1- _ＢＡｌ_Ｂ）Ｎ_1-EＯ_E（ただし、原子比で、Ｂは０．０５〜０．３０、Ｅは０．０２〜０．１０を示す）、
を満足し、かつ隣り合う上記Ａｌおよび酸素の最高含有点と上記Ｃｒおよび窒素の最高含有点の間隔を、０．０１〜０．１μmとすると、
上記Ａｌおよび酸素の最高含有点部分では、Ａｌおよび酸素がきわめて高い割合で含有し、かつこれらＡｌおよび酸素には共存した状態で高温硬さと耐熱性を著しく向上させる作用があることから、一段とすぐれた高温硬さと耐熱性を示し、一方上記Ｃｒおよび窒素の最高含有点部分では、Ｃｒおよび窒素がＡｌおよび酸素に比して一段と高い割合で含有し、これらＣｒおよび窒素には共存した状態で高温強度を著しく向上させる作用があることから、一段とすぐれた高温強度を保持するようになり、しかも前記Ａｌおよび酸素の最高含有点と上記Ｃｒおよび窒素の最高含有点の間隔をきわめて小さくしたので、層全体の特性として一段とすぐれた高温硬さと耐熱性、さらにすぐれた高温強度を具備するようになり、また前記両点間でＡｌと酸素およびＣｒと窒素の含有割合がそれぞれ連続的に変化（成分濃度分布構造）することにより、硬質被覆層内には層界面が存在しないことになり、したがって、かかる構成の（Ａｌ，Ｃｒ）ＯＮ層を硬質被覆層として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高い発熱を伴なう高速で、かつ高い機械的衝撃を伴なう高切り込みや高送りなどの重切削条件で切削加工を行なった場合にも、切刃部にチッピングなどの発生なく、すぐれた耐摩耗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、
（１）超硬基体の表面に、アークイオンプレーティング装置を用い、（Ａｌ，Ｃｒ）ＯＮ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にして、前記硬質被覆層を、層厚方向にそって、Ａｌおよび酸素の最高含有点とＣｒおよび窒素の最高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および酸素の最高含有点から前記Ｃｒおよび窒素の最高含有点、前記Ｃｒおよび窒素の最高含有点から前記Ａｌおよび酸素の最高含有点へＡｌと酸素およびＣｒと窒素の含有割合がそれぞれ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および酸素の最高含有点が、
組成式：（Ａｌ_1- _ＡＣｒ_Ａ）Ｏ_1-DＮ_D（ただし、原子比で、Ａは０．０５〜０．３５、Ｄは０．０２〜０．１０を示す）、
上記Ｃｒおよび窒素の最高含有点が、
組成式：（Ｃｒ_1- _ＢＡｌ_Ｂ）Ｎ_1-EＯ_E（ただし、原子比で、Ｂは０．０５〜０．３０、Ｅは０．０２〜０．１０を示す）、
を満足し、かつ隣り合う上記Ａｌおよび酸素の最高含有点と上記Ｃｒおよび窒素の最高含有点の間隔が、０．０１〜０．１μmである、
硬質被覆層で構成してなる、高速重切削条件で硬質被覆層がすぐれた耐摩耗性を発揮する被覆超硬工具。
（２）（ａ）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、前記回転テーブルの中心軸から半径方向に離れた位置に偏心して超硬基体を自転自在に装着し、
（ｂ）また、上記回転テーブルを挟んで、いずれもカソード電極（蒸発源）として、相対的にＡｌ含有割合の高いＡｌ−Ｃｒ合金と、相対的にＣｒ含有割合の高いＣｒ−Ａｌ合金を対向配置すると共に、それぞれ前記Ａｌ−Ｃｒ合金に比してＡｌ含有割合が低く、かつ前記Ｃｒ−Ａｌ合金に比してＣｒ含有割合が低い中間Ａｌ／Ｃｒ合金と中間Ｃｒ／Ａｌ合金を同じく対向配置し、
（ｃ）上記回転テーブルを挟んで対向配置した上記のカソード電極と、前記カソード電極のそれぞれに並設されたアノード電極との間にアーク放電を発生させ、
（ｄ）上記アークイオンプレーティング装置内の反応雰囲気を酸素と窒素の混合雰囲気とするが、前記装置内への酸素と窒素の相対導入割合を上記超硬基体の回転移動位置に対応して調整して、前記超硬基体が上記の相対的にＡｌ含有割合の高いＡｌ−Ｃｒ合金のカソード電極に最も接近した時点での反応雰囲気を酸素導入割合が最も高く、窒素導入割合が最も低い反応雰囲気とする一方、前記超硬基体が上記の相対的にＣｒ含有割合の高いＣｒ−Ａｌ合金のカソード電極に最も接近した時点での反応雰囲気を窒素導入割合が最も高く、酸素導入割合が最も低い反応雰囲気とすると共に、前記超硬基体が前記Ａｌ−Ｃｒ合金のカソード電極最接近位置から上記中間Ａｌ／Ｃｒ合金のカソード電極最接近位置を経て前記Ｃｒ−Ａｌ合金のカソード電極最接近位置に回転移動する間の反応雰囲気を、酸素導入割合が連続的に減少し、これに対応して窒素導入割合が連続的に増加する連続変化雰囲気とし、一方前記超硬基体が前記Ｃｒ−Ａｌ合金のカソード電極最接近位置から上記中間Ｃｒ／Ａｌ合金のカソード電極最接近位置を経て前記Ａｌ−Ｃｒ合金のカソード電極最接近位置に回転移動する間の反応雰囲気を、窒素導入割合が連続的に減少し、これに対応して酸素導入割合が連続的に増加する連続変化雰囲気とし、
（ｅ）もって、上記回転テーブル上で自転しながら偏心回転する上記超硬基体の表面に、層厚方向にそって、Ａｌおよび酸素の最高含有点とＣｒおよび窒素の最高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および酸素の最高含有点から前記Ｃｒおよび窒素の最高含有点、前記Ｃｒおよび窒素の最高含有点から前記Ａｌおよび酸素の最高含有点へＡｌと酸素およびＣｒと窒素の含有割合がそれぞれ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および酸素の最高含有点が、
組成式：（Ａｌ _{1- Ａ} Ｃｒ _Ａ）Ｏ _1-D Ｎ _D （ただし、原子比で、Ａは０．０５〜０．３５、Ｄは０．０２〜０．１０を示す）、
上記Ｃｒおよび窒素の最高含有点が、
組成式：（Ｃｒ _{1- Ｂ} Ａｌ _Ｂ）Ｎ _1-E Ｏ _E （ただし、原子比で、Ｂは０．０５〜０．３０、Ｅは０．０２〜０．１０を示す）、
を満足し、かつ隣り合う上記Ａｌおよび酸素の最高含有点と上記Ｃｒおよび窒素の最高含有点の間隔が、０．０１〜０．１μ m である、（Ａｌ，Ｃｒ）ＯＮ層からなる硬質被覆層を物理蒸着すること、
以上（ａ）〜（ｅ）の工程により高速重切削条件で硬質被覆層がすぐれた耐摩耗性を発揮する被覆超硬工具を製造する方法。
以上（１）および（２）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、硬質被覆層である（Ａｌ，Ｃｒ）ＯＮ層の構成を上記の通りに限定した理由を説明する。
（ａ）Ａｌおよび酸素の最高含有点
上記（Ａｌ，Ｃｒ）ＯＮ層において、Ａｌおよび酸素の最高含有点部分では高含有のＡｌと酸素の作用で一段とすぐれた高温硬さと耐熱性を示し、一方Ｃｒおよび窒素の最高含有点部分では、相対的に高い含有割合のＣｒと窒素の作用ですぐれた高温強度を示し、したがってＡｌおよび酸素の最高含有点では、ＣｒのＡｌとの合量に占める含有割合を示すＡ値が、原子比で０．０５未満になったり、窒素の酸素との合量に占める含有割合を示すＤ値が、同じく原子比で（以下、同じ）０．０２未満になったりすると、Ａｌおよび酸素の相対割合が多くなり過ぎて、すぐれた高温強度を有するＣｒと窒素の最高含有点が隣接して存在しても層自体の高温強度はきわめて低いものとなり、この結果チッピングなどが発生し易くなり、一方同Ａ値が０．３５を越えたり、同Ｄ値が０．１０を越えたりすると、高温硬さおよび耐熱性が急激に低下し、摩耗促進の原因となることから、Ｃｒの含有割合を示すＡ値を０．０５〜０．３５、および窒素の含有割合を示すＤ値を０．０２〜０．１０とそれぞれ定めた。
【００１１】
（ｂ）Ｃｒおよび窒素の最高含有点
上記の通りＡｌおよび酸素の最高含有点は一段とすぐれた高温硬さと耐熱性を有するが、反面高温強度の低いものであるため、このＡｌおよび酸素の最高含有点の高温強度不足を補う目的で、相対的にすぐれた高温強度を有するＣｒおよび窒素の最高含有点を厚さ方向に交互に介在させるものである。しかし、ＡｌのＣｒとの合量に占める含有割合を示すＢ値が０．０５未満になると、Ｃｒおよび窒素の最高含有点での高温硬さおよび耐熱性不足が原因で、硬質被覆層の摩耗が促進されるようになり、また同Ｂ値が０．３０を越えると、高温強度が急激に低下し、特に重切削条件下では硬質被覆層にチッピングが発生し易くなり、一方酸素の窒素との合量に占める含有割合を示すＥ値が０．０２未満になると、Ｃｒおよび窒素の最高含有点での高温硬さおよび耐熱性不足が原因で、摩耗が促進するようになり、また同Ｅ値が０．１０を越えると、高温強度が急激に低下し、これが同じくチッピング発生の原因となることから、Ａｌの含有割合を示すＢ値を０．０５〜０．３０、酸素の含有割合を示すＥ値を０．０２〜０．１０と定めた。
【００１２】
（ｃ）Ａｌおよび酸素の最高含有点とＣｒおよび窒素の最高含有点間の間隔
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すぐれた高温硬さと耐熱性、さらに高温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および酸素の最高含有点であれば高温強度不足、Ｃｒおよび窒素の最高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、これが原因で切刃部にチッピングが発生し易くなったり、摩耗進行が一段と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、切刃部に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およびその製造方法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６０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：１４２０℃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すことにより、ＩＳＯ規格・ＣＮＭＧ１２０４１２のチップ形状をもったＷＣ基超硬合金製の超硬基体Ａ−１〜Ａ−１０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（質量比で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６０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：１５２０℃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すことにより、ＩＳＯ規格・ＣＮＭＧ１２０４１２のチップ形状をもったＴｉＣＮ系サーメット製の超硬基体Ｂ−１〜Ｂ−６を形成した。
【００１６】
ついで、上記の超硬基体Ａ−１〜Ａ−１０およびＢ−１〜Ｂ−６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、前記回転テーブルの中心軸から半径方向に離れた位置に偏心して自転自在に装着し、いずれもカソード電極（蒸発源）として、種々の成分組成をもったＡｌおよび酸素最高含有点形成用Ａｌ−Ｃｒ合金と、同じく種々の成分組成をもったＣｒおよび窒素最高含有点形成用Ｃｒ−Ａｌ合金を前記回転テーブルを挟んで対向配置し、さらにそれぞれ前記Ａｌ−Ｃｒ合金に比してＡｌ含有割合が低く、かつ前記Ｃｒ−Ａｌ合金に比してＣｒ含有割合が低い中間Ａｌ／Ｃｒ合金と中間Ｃｒ／Ａｌ合金を同じく対向配置し、またボンバード洗浄用金属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、かつカソード電極の前記金属Ｃｒとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＣｒボンバード洗浄し、ついで、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−３０Ｖ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および酸素最高含有点形成用Ａｌ−Ｃｒ合金、前記Ｃｒおよび窒素最高含有点形成用Ｃｒ−Ａｌ合金、さらに前記中間Ａｌ／Ｃｒ合金および中間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、かつ装置内の反応雰囲気の圧力を３Ｐａに保持しながら、前記超硬基体が上記の相対的にＡｌ含有割合の高いＡｌ−Ｃｒ合金のカソード電極（蒸発源）に最も接近した時点での反応雰囲気を酸素導入割合が最も高く、窒素導入割合が最も低い反応雰囲気とする一方、前記超硬基体が上記の相対的にＣｒ含有割合の高いＣｒ−Ａｌ合金のカソード電極に最も接近した時点での反応雰囲気を窒素導入割合が最も高く、酸素導入割合が最も低い反応雰囲気とすると共に、前記超硬基体が前記Ａｌ−Ｃｒ合金のカソード電極最接近位置から上記中間Ａｌ／Ｃｒ合金のカソード電極最接近位置を経て前記Ｃｒ−Ａｌ合金のカソード電極最接近位置に回転移動する間の反応雰囲気を、酸素導入割合が連続的に減少し、これに対応して窒素導入割合が連続的に増加する連続変化雰囲気とし、一方前記超硬基体が前記Ｃｒ−Ａｌ合金のカソード電極最接近位置から上記中間Ｃｒ／Ａｌ合金のカソード電極最接近位置を経て前記Ａｌ−Ｃｒ合金のカソード電極最接近位置に回転移動する間の反応雰囲気を、窒素導入割合が連続的に減少し、これに対応して酸素導入割合が連続的に増加する連続変化雰囲気とした条件で本発明法を実施し、もって前記超硬基体の表面に、厚さ方向に沿って表３，４に示される目標組成のＡｌおよび酸素最高含有点とＣｒおよび窒素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および酸素最高含有点から前記Ｃｒおよび窒素最高含有点、前記Ｃｒおよび窒素最高含有点から前記Ａｌおよび酸素最高含有点へＡｌと酸素およびＣｒと窒素の含有割合がそれぞれ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に示される目標層厚の硬質被覆層を蒸着形成してなる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Ａ−１〜Ａ−１０およびＢ−１〜Ｂ−６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−Ｔｉ合金を装着し、さらにボンバード洗浄用金属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、かつカソード電極の前記金属Ｃｒとアノード電極との間に１００Ａの電流を流してアーク放電を発生させて超硬基体表面をＣｒボンバード洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して２Ｐａの反応雰囲気とすると共に、超硬基体に−１００Ｖの直流バイアス電圧を印加し、前記カソード電極のＡｌ−Ｔｉ合金とアノード電極との間に１００Ａの電流を流してアーク放電を発生させる条件で従来法を実施し、もって前記超硬基体Ａ−１〜Ａ−１０およびＢ−１〜Ｂ−６のそれぞれの表面に、表５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，Ｔｉ）Ｎ層からなる硬質被覆層を蒸着形成してなる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、上記本発明法および従来法により得られた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・Ｓ４５Ｃの丸棒、
切削速度：３２０ｍ／ｍｉｎ．、
切り込み：２．５ｍｍ、
送り：０．２ｍｍ／ｒｅｖ．、
切削時間：１０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・ＳＮＣＭ４３９の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３００ｍ／ｍｉｎ．、
切り込み：２．４ｍｍ、
送り：０．２５ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での合金鋼の乾式断続高速高切り込み切削加工試験、さらに、
被削材：ＪＩＳ・ＦＣ３００の長さ方向等間隔４本縦溝入り丸棒、
切削速度：４００ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．５０ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での鋳鉄の乾式断続高速高送り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６０時間ボールミル混合し、減圧乾燥した後、１００ＭＰａの圧力で所定形状の各種の圧粉体にプレス成形し、これらの圧粉体を、６Ｐａの真空雰囲気中、７℃／分の昇温速度で１３７０〜１４７０℃の範囲内の所定の温度に昇温し、この温度に１時間保持後、炉冷の条件で焼結して、直径が８ｍｍ、１３ｍｍ、および２６ｍｍの３種の超硬基体形成用丸棒焼結体を形成し、さらに前記の３種の丸棒焼結体から、研削加工にて、表７に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法、並びにいずれもねじれ角：３０度の４枚刃スクエア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の表面を、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と同一の条件で本発明法を実施し、もって前記超硬基体（エンドミル）の表面に、厚さ方向に沿って表８に示される目標組成のＡｌおよび酸素最高含有点とＣｒおよび窒素最高含有点とが交互に、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および酸素最高含有点から前記Ｃｒおよび窒素最高含有点、前記Ｃｒおよび窒素最高含有点から前記Ａｌおよび酸素最高含有点へＡｌと酸素およびＣｒと窒素の含有割合がそれぞれ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に示される目標層厚の硬質被覆層を蒸着形成してなる本発明被覆超硬工具としての本発明被覆超硬エンドミル１〜８を製造した。
【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と同一の条件で従来法を実施し、もって、表９に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ）Ｎ層からなる硬質被覆層を蒸着形成してなる従来被覆超硬工具としての従来表面被覆超硬合金製エンドミル（以下、従来被覆超硬エンドミルと云う）１〜８をそれぞれ製造した。
【００２８】
つぎに、上記本発明法および従来法により得られた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・ＳＣＭ４４０の板材、
切削速度：１６０ｍ／ｍｉｎ．、
軸方向切り込み：８ｍｍ、
径方向切り込み：２．０ｍｍ、
テーブル送り：６５０ｍｍ／分、
の条件での合金鋼の湿式高速高切り込み側面切削加工試験、上記の本発明法および従来法により得られた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・Ｓ５５Ｃの板材、
切削速度：１２０ｍ／ｍｉｎ．、
軸方向切り込み：１２ｍｍ、
径方向切り込み：１．５ｍｍ、
テーブル送り：９５０ｍｍ／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、本発明法および従来法により得られた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・ＳＫＤ６１（硬さ：Ｈ_ＲＣ５２）の板材、
切削速度：７０ｍ／ｍｉｎ．、
軸方向切り込み：２０ｍｍ、
径方向切り込み：２．０ｍｍ、
テーブル送り：２６０ｍｍ／分、
の条件での工具鋼の湿式高速高切り込みおよび高送り側面切削加工試験をそれぞれ行い、いずれの湿式側面切削加工試験（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、並びにいずれもねじれ角：３０度の２枚刃形状をもった超硬基体（ドリル）Ｄ−１〜Ｄ−８をそれぞれ製造した。
【００３３】
ついで、これらの超硬基体（ドリル）Ｄ−１〜Ｄ−８の切刃に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図１に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で本発明法を実施し、もって前記超硬基体（ドリル）の表面に、厚さ方向に沿って表１０に示される目標組成のＡｌおよび酸素最高含有点とＣｒおよび窒素最高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および酸素最高含有点から前記Ｃｒおよび窒素最高含有点、前記Ｃｒおよび窒素最高含有点から前記Ａｌおよび酸素最高含有点へＡｌと酸素およびＣｒと窒素の含有割合がそれぞれ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に示される目標層厚の硬質被覆層を蒸着形成してなる本発明被覆超硬工具としての本発明被覆超硬ドリル１〜８それぞれを製造した。
【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と同一の条件で従来法を実施し、もって、表１１に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ）Ｎ層からなる硬質被覆層を蒸着形成してなる従来被覆超硬工具としての従来表面被覆超硬合金製ドリル（以下、従来被覆超硬ドリルと云う）１〜８をそれぞれ製造した。
【００３５】
つぎに、上記本発明法および従来法により得られた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×２５０、厚さ：５０ｍｍのＪＩＳ・ＳＫＤ６１（硬さ：Ｈ_ＲＣ５２）の板材、
切削速度：９０ｍ／ｍｉｎ．、
送り：０．１５ｍｍ／ｒｅｖ、
穴深さ：８ｍｍ、
の条件での工具鋼の湿式高速高送り穴あけ切削加工試験、上記の本発明法および従来法により得られた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・ＳＮＣＭ４３９の板材、
切削速度：８０ｍ／ｍｉｎ．、
送り：０．２８ｍｍ／ｒｅｖ、
穴深さ：１６ｍｍ、
の条件での合金鋼の湿式高速高送り穴あけ切削加工試験、本発明法および従来法により得られた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・Ｓ５０Ｃの板材、
切削速度：４０ｍ／ｍｉｎ．、
送り：０．５０ｍｍ／ｒｅｖ、
穴深さ：２４ｍｍ、
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、をそれぞれ行い、いずれの湿式高速高送り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】
上記の本発明法で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、並びに従来法で得られた従来被覆超硬工具としての従来被覆超硬チップ１〜１６、従来被覆超硬エンドミル１〜８、および従来被覆超硬ドリル１〜８を構成する硬質被覆層について、厚さ方向に沿ってＡｌ、Ｃｒ、およびＴｉ、さらに酸素および窒素の含有割合をオージェ分光分析装置を用いて測定したところ、前記本発明被覆超硬工具の硬質被覆層では、Ａｌおよび酸素の最高含有点とＣｒおよび窒素の最高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および酸素の最高含有点から前記Ｃｒおよび窒素の最高含有点、前記Ｃｒおよび窒素の最高含有点から前記Ａｌおよび酸素の最高含有点へＡｌと酸素およびＣｒと窒素の含有割合がそれぞれ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、さらに硬質被覆層の平均層厚も目標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、目標組成と実質的に同じ組成および目標層厚と実質的に同じ平均層厚を示すものの、厚さ方向に沿った組成変化は見られず、層全体に亘って均質な組成を示すものであった。
【００３９】
【発明の効果】
表３〜１１に示される結果から、上記本発明法で得られた、硬質被覆層が層厚方向に、相対的に一段とすぐれた高温硬さと耐熱性を有するＡｌおよび酸素の最高含有点とすぐれた高温強度を有するＣｒおよび窒素の最高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および酸素の最高含有点から前記Ｃｒおよび窒素の最高含有点、前記Ｃｒおよび窒素の最高含有点から前記Ａｌおよび酸素の最高含有点へＡｌと酸素およびＣｒと窒素の含有割合がそれぞれ連続的に変化する成分濃度分布構造を有する（Ａｌ，Ｃｒ）ＯＮ層からなる被覆超硬工具は、いずれも切削加工を、特に高い発熱を伴う高速で、かつ高い機械的衝撃を伴なう重切削条件で行なった場合にも、切刃部にチッピングの発生なく、すぐれた耐摩耗性を示し、長期に亘ってすぐれた切削性能を発揮するのに対して、上記従来法で得られた、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，Ｔｉ）Ｎ層からなる従来被覆超硬工具においては、前記の高速重切削条件では、前記硬質被覆層の高温硬さおよび耐熱性、さらに高温強度不足が原因で、いずれも切削開始間もなく、切刃部にチッピングが発生し、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、この発明の方法によれば、各種の鋼や鋳鉄などの通常の条件での切削加工は勿論のこと、特に高速重切削条件で行なった場合にも、チッピングの発生なく、長期に亘ってすぐれた耐摩耗性を示す被覆超硬工具を製造することができ、したがって、この結果の被覆超硬工具は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することができるものである。
【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 excellent high-temperature hardness, heat resistance, and high-temperature strength. Therefore, cutting of various steels and cast irons can be performed at high speed with high heat generation and high mechanical impact. When performed under heavy cutting conditions such as high depth of cut and high feed, chipping due to insufficient high-temperature strength of the hard coating layer does not occur on the cutting edge and has excellent wear resistance. The present invention relates to a surface-coated cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide tool) and a method for producing the same.
[0002]
[Prior art]
In general, coated carbide tools include a throw-away tip that is attached to the tip of a cutting tool for turning and planing of various steels and cast irons, and drilling of the work material. There are drills and miniature drills used for processing, etc., and solid type end mills used for chamfering, grooving, shoulder processing, etc. of the work material. A slow-away end mill tool that performs cutting work in the same manner as a type end mill is known.
[0003]
Further, as a coated carbide tool, a tungsten carbide (hereinafter referred to as WC) based cemented carbide substrate or a titanium carbonitride (hereinafter referred to as TiCN) based cermet substrate (hereinafter referred to as these carbide substrates). Are collectively referred to as the “carbide substrate”)
Composition formula: (Al_1- _FTi_F) A hard coating layer composed of a composite nitride of Al and Ti [hereinafter referred to as (Al, Ti) N] satisfying N (wherein F represents 0.35 to 0.60 in atomic ratio) A coated carbide tool formed by physical vapor deposition with an average layer thickness of 1 to 15 μm has been proposed, and the (Al, Ti) N layer constituting the hard coating layer is composed of high-temperature hardness and heat resistance due to an Al component, Ti Because it has high-temperature strength due to its components, the coated carbide tool that is vapor-deposited on it exhibits excellent cutting performance when used for continuous cutting and intermittent cutting of various steels and cast irons. Is also known (see, for example, 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, in the state heated to a temperature of 500 ° C., an arc discharge is generated between the anode electrode and the cathode electrode (evaporation source) in which an Al—Ti alloy having a predetermined composition is set, for example, under a current of 90 A, At the same time, nitrogen gas is introduced into the apparatus as a reaction gas to give a reaction atmosphere of, for example, 2 Pa. On the other hand, the carbide substrate is applied with a bias voltage of, for example, −100 V on the surface of the carbide substrate. It is also well known that it is produced by vapor-depositing a hard coating layer composed of an (Al, Ti) N layer. (For example, refer to Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent No. 2644710
[0006]
[Problems to be solved by the invention]
In recent years, the performance of cutting devices has been dramatically improved, while there is a strong demand for labor saving, energy saving, and cost reduction for cutting processing. Accordingly, cutting processing has been further increased in speed, and high cutting depth, high feed, etc. However, in the above conventional coated carbide tools, cutting is performed at high speed with high heat generation and high cutting depth and high mechanical impact. When used under heavy cutting conditions such as feeding, the cutting edge is chipped because the high temperature strength, high temperature hardness and heat resistance of the (Al, Ti) N layer, which is a hard coating layer, are not sufficient. Is likely to occur, and the wear of the hard coating layer is further promoted, so that 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 coated carbide tool that exhibits excellent wear resistance over a long period of time, without the occurrence of chipping or the like in the cutting edge portion, particularly in high-speed heavy cutting. As a result of research,
(A) For example, an arc ion plating apparatus belonging to a physical vapor deposition apparatus having a structure shown in FIG. 1 (a) in a schematic plan view and in FIG. A table is provided, and an Al—Cr alloy with a relatively high Al content ratio on one side and a Cr—Al alloy with a relatively high Cr content ratio on the other side are both cathode electrodes (evaporation source) with the rotary table in between. The intermediate Al / Cr alloy and the intermediate Cr / Al alloy have a lower Al content ratio than the Al-Cr alloy and a lower Cr content ratio than the Cr-Al alloy. Is also used as the cathode electrode (evaporation source) arc ion plating device
On the rotary table of this apparatus, the carbide substrate is mounted eccentrically at a position radially away from the central axis of the rotary table,
In this state, the reaction atmosphere in the apparatus is a mixed atmosphere of oxygen and nitrogen. The relative introduction ratio of oxygen and nitrogen into the apparatus is adjusted in accordance with the rotational movement position of the carbide substrate, and the super The reaction atmosphere when the hard substrate is closest to the cathode electrode of the above Al-Cr alloy having a relatively high Al content is the highest oxygen introduction rate and the lowest nitrogen introduction rate, preferably the relative introduction of oxygen. While the ratio is 90 to 97% by volume and the remainder is a reaction atmosphere consisting of nitrogen, the reaction when the cemented carbide substrate comes closest to the cathode electrode of the above-mentioned Cr-Al alloy having a relatively high Cr content ratio The atmosphere has the highest nitrogen introduction ratio and the lowest oxygen introduction ratio, desirably a nitrogen relative introduction ratio of 90 to 97% by volume, and the remainder being oxygen, and the carbide substrate is the Al- The reaction atmosphere during the rotational movement from the closest cathode electrode of the r alloy to the closest cathode electrode of the Cr-Al alloy through the closest cathode electrode of the intermediate Al / Cr alloy is continuously introduced. And a continuously changing atmosphere in which the nitrogen introduction rate is continuously increased correspondingly. On the other hand, the cemented carbide substrate is moved from the closest proximity of the cathode electrode of the Cr-Al alloy to the intermediate Cr / Al alloy. During the rotational movement of the Al-Cr alloy to the cathode electrode closest position through the cathode electrode closest position, the nitrogen introduction ratio is continuously reduced, and the oxygen introduction ratio is continuously increased accordingly. Continuously rotating atmosphere, rotating the rotary table and rotating the carbide substrate itself for the purpose of uniforming the thickness of the hard coating layer formed by vapor deposition. Reluctant, the conditions for generating an arc discharge between each cathode (evaporation source) and an anode electrode of said,
When an Al and Cr composite oxynitride [hereinafter referred to as (Al, Cr) ON] layer is formed,
On the surface of the cemented carbide substrate, the cemented carbide substrate arranged eccentrically at a position radially away from the central axis on the rotary table is an Al-Cr alloy having a relatively high Al content on the one side. When the closest cathode electrode (evaporation source) is formed, the highest content point of Al and oxygen is formed in the layer, and the carbide substrate is Cr-Al having a relatively high Cr content on the other side. Since the highest content point of Cr and nitrogen is formed in the layer when it is closest to the cathode electrode of the alloy, the highest content of Al and oxygen along the thickness direction in the layer by the rotation of the rotary table. The point and the highest content point of Cr and nitrogen appear alternately with a predetermined interval, and from the highest content point of Al and oxygen to the highest content point of Cr and nitrogen, and from the highest content point of Cr and nitrogen A hard coating layer composed of an (Al, Cr) ON layer having a component concentration distribution structure in which the content ratios of Al, oxygen, and Cr and nitrogen continuously change to the highest content point of Al and oxygen is formed. To become a.
[0008]
(B) When forming the (Al, Cr) ON layer having the repeated continuous change component concentration distribution structure of (a) above, for example, the composition of each of the cathode electrodes (evaporation sources) arranged opposite to each other and the reaction continuously changing in the apparatus While adjusting the composition of the atmosphere, that is, the mutual introduction ratio of oxygen and nitrogen, and controlling the rotation speed of the rotary table on which the carbide substrate is mounted,
The maximum content point of Al and oxygen is
Composition formula: (Al_1- _ACr_A) O_1-DN_D(However, in atomic ratio, A shows 0.05-0.35, D shows 0.02-0.10),
The maximum content point of Cr and nitrogen is
Composition formula: (Cr_1- _BAl_B) N_1-EO_E(However, in atomic ratio, B is 0.05-0.30, E shows 0.02-0.10),
And the distance between the highest content point of Al and oxygen adjacent to each other and the highest content point of Cr and nitrogen is 0.01 to 0.1 μm,
The Al and oxygen maximum content points contain a very high proportion of Al and oxygen, and these Al and oxygen have the effect of significantly improving the high-temperature hardness and heat resistance in the coexisting state. High temperature hardness and heat resistance, while the highest content point of Cr and nitrogen contains Cr and nitrogen at a higher ratio than Al and oxygen. Since it has the effect of remarkably improving the strength, it is possible to maintain a further excellent high-temperature strength, and the distance between the highest content point of Al and oxygen and the highest content point of Cr and nitrogen is extremely small. As a whole, it has excellent high-temperature hardness and heat resistance, and excellent high-temperature strength. Since the content ratios of elemental and Cr and nitrogen continuously change (component concentration distribution structure), there is no layer interface in the hard coating layer. Therefore, (Al, Cr) ON having such a configuration is present. Cemented carbide tools that are formed as a hard coating layer are used to cut various steel and cast iron at high speed with high heat generation and high cutting and high feed with high mechanical impact. Even when cutting under heavy cutting conditions, the cutting edge must have excellent wear resistance without chipping.
The research results shown in (a) and (b) above were obtained.
[0009]
  This invention was made based on the above research results,
(1) On the surface of the carbide substrate,Using arc ion plating equipmentA hard coating layer made of (Al, Cr) ON layer is physically deposited by physical vapor deposition with an average layer thickness of 1 to 15 μm, and the hard coating layer is made of Al and oxygen along the layer thickness direction. The highest content point of Cr and the highest content point of Cr and nitrogen are alternately present at predetermined intervals, and from the highest content point of Al and oxygen, the highest content point of Cr and nitrogen, the highest content of Cr and nitrogen A component concentration distribution structure in which the content ratios of Al, oxygen, and Cr and nitrogen continuously change from the content point to the highest content point of Al and oxygen, respectively.
  Furthermore, the highest content point of Al and oxygen is
  Composition formula: (Al_1- _ACr_A) O_1-DN_D(However, in atomic ratio, A shows 0.05-0.35, D shows 0.02-0.10),
  The maximum content point of Cr and nitrogen is
  Composition formula: (Cr_1- _BAl_B) N_1-EO_E(However, in atomic ratio, B is 0.05-0.30, E shows 0.02-0.10),
And the distance between the highest Al and oxygen content points adjacent to each other and the highest Cr and nitrogen content point is 0.01 to 0.1 μm.
A coated carbide tool composed of a hard coating layer that exhibits excellent wear resistance under high-speed heavy cutting conditions.
(2) (a) On the rotary table in the arc ion plating apparatus, a carbide base is eccentrically mounted at a position away from the central axis of the rotary table in a radial direction, and the carbide substrate is rotatably mounted.
  (B) Further, with the rotary table sandwiched between them, as a cathode electrode (evaporation source), an Al—Cr alloy having a relatively high Al content and a Cr—Al alloy having a relatively high Cr content are opposed to each other. In addition, an intermediate Al / Cr alloy and an intermediate Cr / Al alloy, which have a lower Al content ratio than the Al-Cr alloy and a lower Cr content ratio than the Cr-Al alloy, face each other. And
  (C) generating an arc discharge between the cathode electrode disposed opposite to the rotary table and the anode electrode arranged in parallel with each of the cathode electrodes;
  (D) The reaction atmosphere in the arc ion plating apparatus is a mixed atmosphere of oxygen and nitrogen, and the relative introduction ratio of oxygen and nitrogen into the apparatus is adjusted according to the rotational movement position of the carbide substrate. The reaction atmosphere when the cemented carbide substrate is closest to the cathode electrode of the Al-Cr alloy having a relatively high Al content is the reaction atmosphere having the highest oxygen introduction ratio and the lowest nitrogen introduction ratio. On the other hand, the reaction atmosphere when the cemented carbide substrate is closest to the cathode electrode of the Cr-Al alloy having a relatively high Cr content is the reaction with the highest nitrogen introduction rate and the lowest oxygen introduction rate. The cathode of the Cr-Al alloy passes through the cathode electrode closest position of the intermediate Al / Cr alloy from the cathode electrode closest position of the Al-Cr alloy to the atmosphere. The reaction atmosphere during the rotational movement to the closest electrode position is a continuously changing atmosphere in which the oxygen introduction rate continuously decreases and the nitrogen introduction rate continuously increases correspondingly, while the carbide substrate is The reaction atmosphere during the rotational movement from the closest cathode electrode of the Cr—Al alloy to the closest cathode electrode of the Al—Cr alloy through the closest cathode electrode of the intermediate Cr / Al alloy has a nitrogen introduction ratio of A continuously changing atmosphere that continuously decreases and correspondingly increases the oxygen introduction rate continuously,
(E) Therefore, on the surface of the cemented carbide substrate that rotates eccentrically while rotating on the rotary table,Along the layer thickness direction, the highest content point of Al and oxygen and the highest content point of Cr and nitrogen are alternately present at predetermined intervals, and from the highest content point of Al and oxygen, It has a component concentration distribution structure in which the content ratios of Al and oxygen and Cr and nitrogen continuously change from the highest content point, the highest content point of Cr and nitrogen to the highest content point of Al and oxygen, respectively.,
  Furthermore, the highest content point of Al and oxygen is
Composition formula: (Al _{1- A} Cr _A ) O _1-D N _D (However, in atomic ratio, A is 0.05 to 0.35, D represents 0.02 to 0.10),
The maximum content point of Cr and nitrogen is
Composition formula: (Cr _{1- B} Al _B ) N _1-E O _E (However, in atomic ratio, B is 0.05-0.30, E shows 0.02-0.10),
The distance between the highest Al and oxygen content points adjacent to each other and the highest Cr and nitrogen content points is 0.01 to 0.1 μm. m IsPhysical vapor deposition of a hard coating layer comprising an (Al, Cr) ON layer,
A method for producing a coated carbide tool exhibiting excellent wear resistance with a hard coating layer under high-speed heavy cutting conditions by the steps (a) to (e).
The above (1) and (2) are characteristic.
[0010]
Next, the reason why the structure of the (Al, Cr) ON layer, which is a hard coating layer, is limited as described above in the coated carbide tool of the present invention will be described.
(A) Maximum content point of Al and oxygen
In the (Al, Cr) ON layer, the highest content point portion of Al and oxygen exhibits a higher temperature hardness and heat resistance due to the action of the high content of Al and oxygen, while the highest content point portion of Cr and nitrogen, It shows excellent high temperature strength due to the action of relatively high content of Cr and nitrogen. Therefore, at the highest content point of Al and oxygen, the A value indicating the content of the total content of Cr with Al is the atomic ratio. When the D value indicating the content ratio in the total amount of nitrogen and oxygen is less than 0.05, or the atomic ratio (hereinafter the same) is less than 0.02, the relative ratio of Al and oxygen is Even if the maximum content point of Cr and nitrogen having excellent high-temperature strength is adjacent to each other, the high-temperature strength of the layer itself is extremely low, and as a result, chipping and the like are likely to occur. value .35 or when the D value exceeds 0.10, the high-temperature hardness and heat resistance are abruptly reduced, which causes accelerated wear. The D value indicating the content ratio of 05 to 0.35 and nitrogen was determined to be 0.02 to 0.10, respectively.
[0011]
(B) Maximum content point of Cr and nitrogen
As described above, the highest content point of Al and oxygen has excellent high-temperature hardness and heat resistance, but on the other hand, since it has a low high-temperature strength, in order to compensate for the lack of high-temperature strength of the highest content point of Al and oxygen, The highest content point of Cr and nitrogen having relatively high temperature strength is alternately interposed in the thickness direction. However, when the B value indicating the content ratio of the total amount of Al with Cr is less than 0.05, the hard coating layer is worn due to high temperature hardness and insufficient heat resistance at the highest content point of Cr and nitrogen. When the B value exceeds 0.30, the high-temperature strength decreases sharply, and chipping tends to occur in the hard coating layer particularly under heavy cutting conditions, while oxygen nitrogen and When the E value indicating the content ratio in the total amount is less than 0.02, wear is promoted due to high temperature hardness and insufficient heat resistance at the highest content point of Cr and nitrogen. If the value exceeds 0.10, the high-temperature strength rapidly decreases, which also causes chipping. Therefore, the B value indicating the Al content ratio is 0.05 to 0.30, the oxygen content ratio is The indicated E value was determined to be 0.02 to 0.10.
[0012]
(C) The distance between the highest Al and oxygen content points and the highest Cr and nitrogen content points
If the distance is less than 0.01 μm, it is difficult to clearly form each point with the above composition, and as a result, the desired excellent high temperature hardness and heat resistance, and further high temperature strength cannot be secured. In addition, when the distance exceeds 0.1 μm, the disadvantages of the respective points, that is, if the highest content point of Al and oxygen is insufficient, the high temperature strength is insufficient, and if the highest content point of Cr and nitrogen, the high temperature hardness and heat resistance are insufficient. Appear locally in the layer, and this makes it easier for chipping to occur at the cutting edge and further promotes the progress of wear, so the interval was set to 0.01 to 0.1 μm. .
[0013]
(D) Average thickness of hard coating layer
If the layer thickness is less than 1 μm, the desired wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 15 μm, chipping tends to occur at the cutting edge. It was determined as 1 to 15 μm.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated carbide tool and the manufacturing method thereof according to the present invention will be specifically described with reference to examples.
Example 1
WC powder, TiC powder, VC powder, TaC powder, NbC powder, Cr having an average particle diameter of 1 to 3 μm as raw material powders_ThreeC₂Powder and Co powder are prepared, and these raw material powders are blended in the blending composition shown in Table 1, wet mixed by a ball mill for 60 hours, dried, and then pressed into a compact at a pressure of 100 MPa. The green compact was sintered in a vacuum of 6 Pa at a temperature of 1420 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03, whereby ISO standard / CNMG120212 Cemented carbide substrates A-1 to A-10 made of WC-based cemented carbide having a chip shape were formed.
[0015]
In addition, as raw material powder, TiCN (mass ratio of TiC / TiN = 50/50) powder having an average particle diameter of 0.5 to 2 μm, Mo₂C powder, ZrC powder, NbC powder, TaC powder, WC powder, Co powder, and Ni powder are prepared. These raw material powders are blended into the blending composition shown in Table 2 and wet mixed in a ball mill for 60 hours and dried. After that, the green compact was press-molded into a green compact at a pressure of 100 MPa, and this green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1520 ° C. for 1 hour. : By performing a honing process of 0.03, cemented carbide substrates B-1 to B-6 made of TiCN-based cermets having a chip shape of ISO standard / CNMG120412 were formed.
[0016]
Next, each of the above-mentioned carbide substrates A-1 to A-10 and B-1 to B-6 was ultrasonically cleaned in acetone and dried, and then in the arc ion plating apparatus shown in FIG. The rotary table is eccentrically mounted at a position away from the central axis of the rotary table in a radial direction so that it can rotate freely. Both of them have the highest content of Al and oxygen with various component compositions as cathode electrodes (evaporation sources). The point-forming Al-Cr alloy, Cr having the same various component compositions, and the highest nitrogen-containing point-forming Cr-Al alloy are arranged opposite to each other with the rotary table interposed therebetween, and further compared to the Al-Cr alloy, respectively. An intermediate Al / Cr alloy and an intermediate Cr / Al alloy that are low in Al content and low in Cr content compared to the Cr-Al alloy are disposed opposite to each other, and a bombard cleaning metal C First, the inside of the apparatus is evacuated and kept at a vacuum of 0.5 Pa or less, and the inside of the apparatus is heated to 500 ° C. with a heater, and then the carbide substrate that rotates while rotating on the rotary table is set to −1000 V. And applying a current of 100 A between the metal Cr of the cathode electrode and the anode electrode to generate an arc discharge, thereby cleaning the surface of the carbide substrate with Cr bombardment, and then rotating the rotary table. A DC bias voltage of −30 V is applied to the carbide substrate that rotates while rotating above, and each cathode electrode (the Al—Cr alloy for forming the highest point of Al and oxygen and the point for forming the highest content of Cr and nitrogen) A current of 150 A is passed between the anode electrode and a Cr-Al alloy (and the intermediate Al / Cr alloy and intermediate Cr / Al alloy) to generate an arc discharge. When the cemented carbide substrate is closest to the cathode electrode (evaporation source) of the Al-Cr alloy having a relatively high Al content while maintaining the pressure of the reaction atmosphere in the apparatus at 3 Pa. The reaction atmosphere is made the reaction atmosphere having the highest oxygen introduction ratio and the lowest nitrogen introduction ratio, while the cemented carbide substrate is closest to the cathode electrode of the above-mentioned relatively high Cr content Cr-Al alloy. The reaction atmosphere in which the nitrogen introduction ratio is the highest and the oxygen introduction ratio is the lowest, and the carbide substrate is the intermediate Al / Cr alloy cathode electrode from the closest proximity of the cathode electrode of the Al-Cr alloy. During the rotational movement of the Cr-Al alloy to the closest cathode electrode of the Cr-Al alloy through the closest position, the oxygen introduction ratio continuously decreases, and the nitrogen introduction ratio correspondingly. A continuously changing atmosphere which continuously increases, while the carbide substrate passes through the cathode electrode closest approach position of the intermediate Cr / Al alloy from the cathode electrode closest proximity position of the Cr-Al alloy cathode electrode of the Al-Cr alloy. The method of the present invention was carried out under the condition that the reaction atmosphere during the rotational movement to the closest position was a continuously changing atmosphere in which the nitrogen introduction ratio decreased continuously and the oxygen introduction ratio increased correspondingly. Thus, Al and oxygen highest content points and Cr and nitrogen highest content points of the target composition shown in Tables 3 and 4 along the thickness direction are alternately arranged on the surface of the cemented carbide substrate in Tables 3 and 4 as well. Al and acid which are repeatedly present at the indicated target intervals and from the Al and oxygen highest content point to the Cr and nitrogen highest content point, from the Cr and nitrogen highest content point to the Al and oxygen highest content point Further, the coated carbide tool of the present invention having a component concentration distribution structure in which the content ratios of Cr and nitrogen are continuously changed, and formed by vapor-depositing a hard coating layer having a target layer thickness shown in Tables 3 and 4 The present invention surface-coated cemented carbide throwaway tips (hereinafter referred to as the present invention coated carbide tips) 1 to 16 were produced.
[0017]
For comparison purposes, these carbide substrates A-1 to A-10 and B-1 to B-6 were ultrasonically cleaned in acetone and dried, and each of the ordinary arcs shown in FIG. Inserted into an ion plating apparatus, mounted with an Al-Ti alloy having various component compositions as a cathode electrode (evaporation source), and further mounted with a bombard cleaning metal Cr. The inside of the apparatus was heated to 500 ° C. with a heater while maintaining a vacuum of 0.5 Pa or less, and then a −1000 V DC bias voltage was applied to the cemented carbide substrate, and between the metal Cr of the cathode electrode and the anode electrode A current of 100 A is applied to the electrode to generate arc discharge to clean the surface of the carbide substrate with Cr bombardment, and then nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 2 Pa. And applying a DC bias voltage of −100 V to the cathode electrode, and applying a current of 100 A between the Al—Ti alloy of the cathode electrode and the anode electrode to generate arc discharge. Each surface of A-1 to A-10 and B-1 to B-6 has the target composition and target layer thickness shown in Table 5, and substantially no composition change along the layer thickness direction. Conventional surface-coated cemented carbide throwaway tips (hereinafter referred to as conventional coated carbide tips) 1 to 16 as conventional coated carbide tools formed by vapor-depositing a hard coating layer composed of (Al, Ti) N layers. Each was manufactured.
[0018]
Next, the coated carbide chips 1 to 16 and the coated carbide chips 1 to 16 of the present invention obtained by the method of the present invention and the conventional method are screwed to the tip of the tool steel tool with a fixing jig. In state,
Work material: JIS / S45C round bar,
Cutting speed: 320 m / min. ,
Incision: 2.5mm,
Feed: 0.2 mm / rev. ,
Cutting time: 10 minutes,
Carbon steel dry continuous high-speed high-cut cutting test under the conditions of
Work material: JIS / SNCM439 round bars with four equal grooves in the longitudinal direction,
Cutting speed: 300 m / min. ,
Incision: 2.4 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 5 minutes
Dry interrupted high-speed high-cut cutting test of alloy steel under the conditions of
Work material: JIS / FC300 lengthwise equidistant 4 bars with vertical grooves,
Cutting speed: 400 m / min. ,
Incision: 1.5mm,
Feed: 0.50 mm / rev. ,
Cutting time: 5 minutes
The dry interrupted high-speed high-feed 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 of the cutting tests. The measurement results are shown in Table 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_ThreeC₂Prepared 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. Each powder was blended in the blending composition shown in Table 7, added with wax, ball mill mixed in acetone for 60 hours, dried under reduced pressure, and then pressed into various compacts of a predetermined shape at a pressure of 100 MPa, 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 vacuum atmosphere of 6 Pa, kept at this temperature for 1 hour, and then subjected to furnace cooling conditions. In order to form three types of cemented carbide substrate-forming round bar sintered bodies having diameters of 8 mm, 13 mm, and 26 mm, and further grinding from the above three types of round bar sintered bodies, In the combinations shown in Table 7, the diameter x length of the cutting edge is 6 respectively. m × 13mm, 10mm × 22mm, and dimensions of 20 mm × 45 mm, as well as any twist angle: 30 degrees carbide substrate having a 4 flute square shape (end mills) C-1 through C-8 were prepared, respectively.
[0026]
Then, the surfaces of these carbide substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and then charged into the arc ion plating apparatus shown in FIG. The method of the present invention was carried out under the same conditions as in Example 1 above, so that on the surface of the cemented carbide substrate (end mill), the Al and oxygen maximum content points and Cr of the target composition shown in Table 8 along the thickness direction. And the nitrogen highest content point alternately and repeatedly at the target intervals shown in Table 8, and from the Al and oxygen highest content point, the Cr and nitrogen highest content point, and from the Cr and nitrogen highest content point, the Al. In addition, a hard coating layer with a target layer thickness as shown in Table 8 is formed by vapor deposition, having a component concentration distribution structure in which the content ratios of Al, oxygen, and Cr and nitrogen continuously change to the highest oxygen content point. The present invention coated cemented carbide end mills 1 to 8 as the present invention coated cemented carbide comprising Te was 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 conventional method was carried out under the same conditions as in Example 1 above, so that the target composition and target layer thickness shown in Table 9 were obtained, and the composition change substantially along the layer thickness direction. Conventional surface-coated cemented carbide end mills (hereinafter referred to as conventional coated carbide end mills) 1 to 8 as conventional coated carbide tools formed by vapor-depositing a hard coating layer composed of no (Al, Ti) N layer, respectively. Manufactured.
[0028]
Next, among the coated carbide end mills 1 to 8 and the conventional coated carbide end mills 1 to 8 obtained by the method of the present invention and the conventional method, the coated carbide end mills 1 to 3 and the conventional coated carbide of the present coated carbide. For end mills 1 to 3,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SCM440 plate material,
Cutting speed: 160 m / min. ,
Axial cut: 8mm,
Radial notch: 2.0mm,
Table feed: 650 mm / min,
About the wet high speed high cutting side cutting test of alloy steel under the conditions of the present invention, the inventive coated carbide end mills 4 to 6 and the conventional coated carbide end mills 4 to 6 obtained by the method of the present invention and the conventional method described above,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / S55C plate material,
Cutting speed: 120 m / min. ,
Axial cut: 12mm,
Radial notch: 1.5mm,
Table feed: 950 mm / min,
With respect to the carbon steel wet high-speed high-feed side cutting test, the present invention and the conventional coated carbide end mills 7 and 8 and the conventional coated carbide end mills 7 and 8 obtained by the conventional method,
Work material: Plane dimension: 100 mm x 250 mm, thickness: 50 mm JIS SKD61 (Hardness: H_RC52) plate material,
Cutting speed: 70 m / min. ,
Axial cut: 20mm,
Radial notch: 2.0mm,
Table feed: 260 mm / min,
Wet high speed high cutting and high feed side cutting test of tool steel under the above conditions, both wet side cutting test (using water soluble cutting oil), the flank wear width of the outer peripheral edge of the cutting edge is used The cutting length up to 0.1 mm, which is the standard of life, was measured. 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 and D-8), and all Carbide substrates (drills) D-1 to D-8 having a two-blade shape with a twist angle of 30 degrees were produced.
[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. Then, the method of the present invention was carried out under the same conditions as in Example 1 above, so that Al and oxygen having the target composition shown in Table 10 along the thickness direction were formed on the surface of the carbide substrate (drill). The highest content point and the highest Cr and nitrogen content point are alternately repeated at the target intervals shown in Table 10, and from the highest Al and oxygen content point, the highest Cr and nitrogen content point, and the highest Cr and nitrogen content The component concentration distribution structure in which the content ratios of Al, oxygen, and Cr and nitrogen change continuously from the point to the Al and oxygen maximum content point, respectively, and the hard coating of the target layer thickness similarly shown in Table 10 Was prepared present invention coated cemented carbide drills 1-8 respectively as the present invention coated cemented carbide comprising depositing a layer.
[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. A conventional arc ion plating apparatus was charged and the conventional method was carried out under the same conditions as in Example 1. Thus, the target composition and the target layer thickness shown in Table 11 were obtained, and along the layer thickness direction. Conventional surface-coated cemented carbide drill (hereinafter referred to as conventional coated carbide drill) as a conventional coated carbide tool formed by vapor-depositing a hard coating layer composed of an (Al, Ti) N layer having substantially no composition change. 1) -8 were produced respectively.
[0035]
Next, among the coated carbide drills 1 to 8 and the conventional coated carbide drills 1 to 8 obtained by the method of the present invention and the conventional method, the coated carbide drills 1 to 3 and the conventional coated carbide of the present invention. For drills 1-3,
Work material: Plane size: 100 mm x 250, thickness: 50 mm JIS SKD61 (Hardness: H_RC52) plate material,
Cutting speed: 90 m / min. ,
Feed: 0.15mm / rev,
Hole depth: 8mm,
With respect to the tool steel wet high-speed high-feed drilling test, the present invention method and the conventional coated carbide drills 4 to 6 and the conventional coated carbide drills 4 to 6 obtained by the conventional method described above,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SNCM439 plate material,
Cutting speed: 80 m / min. ,
Feed: 0.28mm / rev,
Hole depth: 16mm,
With respect to the present invention coated carbide drills 7 and 8 and the conventional coated carbide drills 7 and 8 obtained by the wet high speed high feed drilling test of the alloy steel under the conditions of the present invention, the present invention method and the conventional method,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / S50C plate material,
Cutting speed: 40 m / min. ,
Feed: 0.50mm / rev,
Hole depth: 24mm
Wet high-speed high-feed drilling machining test of carbon steel under the conditions described above, and the flank wear width of the tip cutting edge surface is 0 for any wet high-speed high-feed drilling test (using water-soluble cutting oil). The number of drilling processes up to 3 mm 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 1-16, the present coated carbide end mills 1-8, the present coated carbide drills 1-8, and the present coated carbide drills 1-8 as the present coated carbide tools obtained by the above method of the present invention, and the conventional About the hard coating layer which comprises the conventional coated carbide tips 1-16, the conventional coated carbide end mills 1-8, and the conventional coated carbide drills 1-8 as the conventional coated carbide tool obtained by the above method The content ratios of Al, Cr, and Ti, and oxygen and nitrogen were measured using an Auger spectroscopic analyzer, and the hard coating layer of the coated carbide tool of the present invention had the highest Al and oxygen content points. The highest content points of Cr and nitrogen alternately and repeatedly exist at substantially the same composition and interval as the target values, respectively, and from the highest content point of Al and oxygen, the highest content point of Cr and nitrogen, C It is confirmed that it has a component concentration distribution structure in which the content ratios of Al and oxygen and Cr and nitrogen change continuously from the highest content point of nitrogen and nitrogen to the highest content point of Al and oxygen, respectively. The layer thickness also showed substantially the same value as the target layer thickness. On the other hand, the hard coating layer of the conventional coated carbide tool shows a composition substantially the same as the target composition and an average layer thickness substantially the same as the target layer thickness, but there is no composition change along the thickness direction. The composition showed a homogeneous composition throughout the entire layer.
[0039]
【The invention's effect】
From the results shown in Tables 3 to 11, the hard coating layer obtained by the above-described method of the present invention has excellent high-temperature hardness and heat resistance, which are relatively superior in the layer thickness direction, and the highest content point of Al and oxygen. The highest content point of Cr and nitrogen having high temperature strength is alternately present at predetermined intervals, and from the highest content point of Al and oxygen, the highest content point of Cr and nitrogen, the highest content of Cr and nitrogen A coated carbide tool composed of an (Al, Cr) ON layer having a component concentration distribution structure in which the content ratios of Al, oxygen, and Cr and nitrogen continuously change from the content point to the highest content point of Al and oxygen, Both show excellent wear resistance without chipping on the cutting edge even when cutting is performed at high speed with high heat generation and heavy cutting conditions with high mechanical impact. While exhibiting excellent cutting performance over the period, the hard coating layer obtained by the above conventional method is composed of an (Al, Ti) N layer having substantially no composition change along the layer thickness direction. In conventional coated carbide tools, under the high-speed heavy cutting conditions described above, chipping occurs at the cutting edge portion soon after the start of cutting due to the high-temperature hardness and heat resistance of the hard coating layer and insufficient high-temperature strength. It is clear that the service life is reached in a relatively short time.
As described above, according to the method of the present invention, not only cutting under normal conditions such as various types of steel and cast iron, but also when performed under high speed heavy cutting conditions, there is no occurrence of chipping and long-term operation. Coated carbide tools exhibiting excellent wear resistance can be manufactured over a long period of time. Therefore, the coated carbide tools as a result of this can sufficiently satisfy the labor-saving and energy-saving of cutting, as well as cost reduction. It is something that can be done.
[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

On the surface of a cemented carbide substrate made of tungsten carbide base cemented carbide or titanium carbonitride cermet, an average layer of 1 to 15 μm is formed with a hard coating layer made of a composite oxynitride layer of Al and Cr using an arc ion plating apparatus. A surface-coated cemented carbide cutting tool formed by physical vapor deposition with a thickness, and along the thickness direction of the hard coating layer, the highest content point of Al and oxygen and the highest content point of Cr and nitrogen have a predetermined interval. And alternately from the highest content point of Al and oxygen to the highest content point of Cr and nitrogen, and from the highest content point of Cr and nitrogen to the highest content point of Al and oxygen. And a component concentration distribution structure in which the content ratios of nitrogen and nitrogen continuously change,
Furthermore, the highest content point of Al and oxygen is
Composition formula: (Al ₁ _-A Cr _A ) O _{1 -D} N _D (where A represents 0.05 to 0.35, D represents 0.02 to 0.10 in atomic ratio),
The maximum content point of Cr and nitrogen is
Composition formula: (Cr _1- _B Al _B ) N _1-E O _E (however, in atomic ratio, B is 0.05 to 0.30, E is 0.02 to 0.10),
And the distance between the highest Al and oxygen content points adjacent to each other and the highest Cr and nitrogen content point is 0.01 to 0.1 μm.
A surface-coated cemented carbide cutting tool that exhibits excellent wear resistance under high-speed heavy cutting conditions characterized by comprising a hard coating layer.

(A) A cemented carbide substrate of tungsten carbide base cemented carbide and a cemented carbide of titanium carbonitride cermet on a rotating table in the arc ion plating apparatus eccentric to a position away from the central axis of the rotating table in the radial direction. One or both of the bases are mounted for rotation,
(B) Further, with the rotating table sandwiched between them, as a cathode electrode (evaporation source), an Al—Cr alloy having a relatively high Al content and a Cr—Al alloy having a relatively high Cr content are opposed to each other. In addition, an intermediate Al / Cr alloy and an intermediate Cr / Al alloy, which have a lower Al content compared to the Al-Cr alloy and a lower Cr content compared to the Cr-Al alloy, are also arranged opposite to each other. And
(C) generating an arc discharge between the cathode electrode disposed opposite to the rotary table and the anode electrode arranged in parallel with each of the cathode electrodes;
(D) The reaction atmosphere in the arc ion plating apparatus is a mixed atmosphere of oxygen and nitrogen, and the relative introduction ratio of oxygen and nitrogen into the apparatus is adjusted according to the rotational movement position of the carbide substrate. The reaction atmosphere when the cemented carbide substrate is closest to the cathode electrode of the Al-Cr alloy having a relatively high Al content is the reaction atmosphere having the highest oxygen introduction ratio and the lowest nitrogen introduction ratio. On the other hand, the reaction atmosphere when the cemented carbide substrate is closest to the cathode electrode of the Cr-Al alloy having a relatively high Cr content is the reaction with the highest nitrogen introduction rate and the lowest oxygen introduction rate. In addition, the cathode substrate of the Cr—Al alloy passes through the cathode electrode closest approach position of the intermediate Al / Cr alloy from the cathode electrode closest proximity position of the Al—Cr alloy. The reaction atmosphere during the rotational movement to the closest position is a continuously changing atmosphere in which the oxygen introduction rate continuously decreases and the nitrogen introduction rate continuously increases correspondingly, while the carbide substrate is the Cr substrate. The reaction atmosphere during the rotational movement from the Al alloy cathode electrode closest position through the intermediate Cr / Al alloy cathode electrode closest position to the Al-Cr alloy cathode electrode closest position, with a continuous nitrogen introduction rate Corresponding to this, a continuously changing atmosphere in which the oxygen introduction rate continuously increases,
(E) Therefore, on the surface of the cemented carbide substrate that rotates eccentrically while rotating on the rotary table, the highest content point of Al and oxygen and the highest content point of Cr and nitrogen are set at predetermined intervals along the layer thickness direction. And from the highest content point of Al and oxygen to the highest content point of Cr and nitrogen, from the highest content point of Cr and nitrogen to the highest content point of Al and oxygen, and It has a component concentration distribution structure in which the content ratios of Cr and nitrogen change continuously,
Furthermore, the highest content point of Al and oxygen is
Composition formula: (Al _{1 -A} Cr _A ) O _{1 -D} N _D (where A represents 0.05 to 0.35, D represents 0.02 to 0.10 in atomic ratio),
The maximum content point of Cr and nitrogen is
Composition formula: (Cr _{1- B} Al _B ) N _1-E O _E (however, in atomic ratio, B is 0.05 to 0.30, E is 0.02 to 0.10),
Satisfied, and spacing of the best content point of maximum content point adjacent the Al and oxygen and the Cr and nitrogen, is 0.01～0.1Myu m, made of a composite oxynitride layer of Al and Cr Physical vapor deposition of hard coating layer,
A method for producing a surface-coated cemented carbide cutting tool that exhibits excellent wear resistance under a high-speed heavy cutting condition characterized by comprising the above (a) to (e).