JP4244379B2

JP4244379B2 - Surface coated cemented carbide cutting tool with excellent wear resistance with high surface coating layer in high speed cutting

Info

Publication number: JP4244379B2
Application number: JP2003197658A
Authority: JP
Inventors: 和則佐藤; 暁裕近藤
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2003-07-16
Filing date: 2003-07-16
Publication date: 2009-03-25
Anticipated expiration: 2023-07-16
Also published as: JP2005034925A

Description

【０００１】
【発明の属する技術分野】
この発明は、特に表面被覆層のうちの耐摩耗硬質層がすぐれた高温硬さと耐熱性を有し、かつ表面潤滑性にもすぐれ、したがって特に各種の鋼や鋳鉄などの高熱発生を伴う高速切削加工で、長期に亘ってすぐれた耐摩耗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、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）基超硬合金または炭窒化チタン（以下、ＴｉＣＮで示す）基サーメットで構成された超硬基体の表面に、
（ａ）表面潤滑層として、０．５〜５μｍの平均層厚を有し、組成式：（Ｃｒ_1- _ＡＳｉ_Ａ）Ｎ（ただし、原子比で、Ａは０．０１〜０．２０を示す）、を満足するＣｒとＳｉの複合窒化物［以下、（Ｃｒ，Ｓｉ）Ｎで示す］層、
（ｂ）耐摩耗硬質層として、１〜１０μｍの平均層厚を有し、かつ、
組成式：（Ａｌ_1-XＴｉ_X）Ｎ（ただし、原子比で、Ｘ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、以上（ａ）および（ｂ）からなる表面被覆層を物理蒸着してなる被覆超硬工具が知られており、前記（Ａｌ，Ｔｉ）Ｎ層が、構成成分であるＡｌによって高温硬さと耐熱性、同Ｔｉによって高温強度を具備し、かつ、前記（Ｃｒ，Ｓｉ）Ｎ層が特に鋼や鋳鉄などに対する親和性がきわめて低く、すぐれた潤滑性を発揮することから、前記被覆超硬工具は、特に鋼や鋳鉄などの連続切削や断続切削加工で、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、前記装置内にはカソード電極（蒸発源）として所定組成を有するＡｌ−Ｔｉ合金およびＣｒ−Ｓｉ合金がそれぞれセットされ、まず、ヒータで装置内を、例えば５００℃の温度に加熱した状態で、アノード電極と前記Ａｌ−Ｔｉ合金のカソード電極との間に、例えば１００Ａの電流を流して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３Ｐａの反応雰囲気とし、一方上記超硬基体には、例えば−１０００Ｖ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、表面被覆層として上記（Ａｌ，Ｔｉ）Ｎ層からなる耐摩耗硬質層を蒸着し、ついでアノード電極と前記Ｃｒ−Ｓｉ合金のカソード電極との間に、例えば１００Ａの電流を流してアーク放電を発生させ、装置内の反応雰囲気は変化させずに、同じ窒素ガス雰囲気に保持した状態で、前記耐摩耗硬質層の上に（Ｃｒ，Ｓｉ）Ｎ層を表面潤滑層として形成することにより製造されることも知られている（例えば特許文献１参照）。
【０００５】
【特許文献１】
特開２００２−２８８０４号公報
【０００６】
【発明が解決しようとする課題】
近年の切削加工装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求は強く、これに伴い、切削加工は高速化の傾向にあるが、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、これを特に高い発熱を伴う高速切削条件で用いた場合、表面被覆層の摩耗進行が著しく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、特に高速切削加工ですぐれた耐摩耗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表面被覆層に着目し、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の表面被覆層を構成する（Ａｌ，Ｔｉ）Ｎからなる耐摩耗硬質層は、層厚全体に亘って均質な高温硬さと耐熱性、および高温強度を有するが、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、一方側に上記の従来（Ａｌ，Ｔｉ）Ｎ層の形成にカソード電極（蒸発源）として用いられたＡｌ−Ｔｉ合金に相当する組成を有する相対的にＴｉ含有量の高いＡｌ−Ｔｉ合金、他方側に相対的にＴｉ含有量の低いＡｌ−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の中心軸から半径方向に所定距離離れた位置に外周部に沿って複数の超硬基体をリング状に装着し、まず、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、蒸着形成される耐摩耗硬質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、前記の回転テーブルの両側に対向配置したカソード電極（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，Ｔｉ）Ｎ層を形成すると、この結果の（Ａｌ，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相対的にＴｉ含有量の高いＡｌ−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最低含有点が形成され、また前記超硬基体が上記の他方側の相対的にＴｉ含有量の低いＡｌ−Ｔｉ合金のカソード電極に最も接近した時点で層中にＡｌ最高含有点が形成され、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最低含有点とＡｌ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最低含有点から前記Ａｌ最高含有点、前記Ａｌ最高含有点から前記Ａｌ最低含有点へＡｌおよびＴｉ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，Ｔｉ）Ｎ層において、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最低含有点が、組成式：（Ａｌ_1-XＴｉ_X）Ｎ（ただし、原子比で、Ｘは０．３５〜０．６０を示す）、
上記Ａｌ最高含有点が、組成式：（Ａｌ_1-YＴｉ_Y）Ｎ（ただし、原子比で、Ｙは０．０５〜０．３０を示す）、
をそれぞれ満足し、かつ隣り合う上記Ａｌ最低含有点とＡｌ最高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，Ｔｉ）Ｎ層に比してＡｌ含有量が相対的に高くなることから、より一段とすぐれた高温硬さと耐熱性を示し、一方上記Ａｌ最低含有点部分は、上記従来（Ａｌ，Ｔｉ）Ｎ層と同等の組成、すなわち前記Ａｌ最高含有点部分に比して相対的にＡｌ含有量が低く、Ｔｉ含有量の高い組成をもつので、相対的に高い高温強度を保持し、かつこれらＡｌ最低含有点とＡｌ最高含有点の間隔をきわめて小さくしたことから、層全体の特性として高い高温強度を保持した状態で、一段とすぐれた高温硬さと耐熱性を具備するようになること。
【０００９】
（Ｃ）さらに、上記（Ａ）および（Ｂ）の繰り返し連続変化成分濃度分布構造の（Ａｌ，Ｔｉ）Ｎ層を１〜１０μｍの平均層厚で耐摩耗硬質層として蒸着形成し、ついで、同じく上記装置内にカソード電極（蒸発源）として配置したＣｒ−Ｓｉ合金とアノード電極との間にアーク放電を発生させて、前記（Ａｌ，Ｔｉ）Ｎ層に重ねて表面潤滑層として０．５〜５μｍの平均層厚で（Ｃｒ，Ｓｉ）Ｎ層を蒸着形成すると、この結果の表面被覆層は、これの耐摩耗硬質層を構成する（Ａｌ，Ｔｉ）Ｎ層が、上記の繰り返し連続変化成分濃度分布構造によって上記の従来（Ａｌ，Ｔｉ）Ｎ層に比して一段とすぐれた高温硬さと耐熱性を有するようになり、したがって表面被覆層がかかる（Ａｌ，Ｔｉ）Ｎ層と（Ｃｒ，Ｓｉ）Ｎ層からなる被覆超硬工具は、前記（Ｃｒ，Ｓｉ）Ｎ層による表面潤滑性向上効果と相俟って、特に高い発熱を伴う各種の鋼や鋳鉄などの高速切削加工に用いた場合にもすぐれた耐摩耗性を長期に亘って発揮するようになること。
以上（Ａ）〜（Ｃ）に示される研究結果を得たのである。
【００１０】
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、装置中央部に超硬基体の装着用回転テーブルを設けたアークイオンプレーティング装置を用い、
（ａ）上記回転テーブルを挟んで、上記アークイオンプレーティング装置のカソード電極（蒸発源）を両側に対向配置し、一方側のカソード電極（蒸発源）としてＡｌ最高含有点形成用Ａｌ−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−Ｔｉ合金をそれぞれ配置し、前記回転テーブル上の中心軸から半径方向に所定距離離れた位置にテーブルの外周部に沿って複数の上記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、前記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蒸着してなる、１〜１０μｍの平均層厚を有し、
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およびＴｉ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最低含有点が、組成式：（Ａｌ_1- _ＸＴｉ_Ｘ）Ｎ（ただし、原子比で、Ｘは０．３５〜０．６０を示す）、
上記Ａｌ最高含有点が、組成式：（Ａｌ_1- _ＹＴｉ_Ｙ）Ｎ（ただし、原子比で、Ｙは０．０５〜０．３０を示す）、
をそれぞれ満足し、かつ隣り合う上記Ａｌ最低含有点とＡｌ最高含有点の間隔が、０．０１〜０．１μmである、（Ａｌ，Ｔｉ）Ｎ層からなる耐摩耗硬質層、
（ｂ）同じく装置内雰囲気を窒素雰囲気として上記回転テーブルを回転させると共に、前記回転テーブル上に同じくリング状に装着した上記超硬基体自体も自転させながら、前記回転テーブルに面して、上記アークイオンプレーティング装置）のカソード電極（蒸発源）として配置したＣｒ−Ｓｉ合金とアノード電極との間にアーク放電を発生させて、前記回転テーブル上の前記超硬基体表面に蒸着形成した上記耐摩耗硬質層に重ねて蒸着してなる、０．５〜５μｍの平均層厚を有し、
組成式：（Ｃｒ_1- _ＡＳｉ_Ａ）Ｎ（ただし、原子比で、Ａは０．０１〜０．２０を示す）、
を満足する（Ｃｒ，Ｓｉ）Ｎ層からなる表面潤滑層、
以上（ａ）および（ｂ）からなる表面被覆層を蒸着形成してなる、高速切削加工で表面被覆層がすぐれた耐摩耗性を発揮する被覆超硬工具に特徴を有するものである。
【００１１】
つぎに、この発明の被覆超硬工具において、これを構成する表面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）耐摩耗硬質層におけるＡｌ最高含有点の組成
Ａｌ最高含有点の（Ａｌ，Ｔｉ）ＮにおけるＡｌ成分には高温硬さと耐熱性を向上させ、一方同Ｔｉ成分には、高温強度を向上させる作用があるので、前記Ａｌ最高含有点では相対的にＴｉ含有量を低くし、Ａｌ含有量を高くして、高熱発生を伴う高速切削に適合したすぐれた高温硬さと耐熱性を具備せしめたものであるが、Ｔｉの割合を示すＹ値がＡｌとの合量に占める割合（原子比、以下同じ）で０．０５未満になると、相対的にＡｌの割合が多くなり過ぎて、高温強度を有するＡｌ最低含有点が隣接して存在しても層自体の高温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Ｔｉの割合を示すＹ値が同０．３０を越えると、相対的にＡｌの割合が少なくなり過ぎて、高速切削に要求される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り、摩耗促進の原因となることから、Ｙ値を０．０５〜０．３０と定めた。
【００１２】
（ｂ）耐摩耗硬質層におけるＡｌ最低含有点の組成
上記の通りＡｌ最高含有点は高温硬さと耐熱性のすぐれたものであるが、反面高温強度の劣るものであるため、このＡｌ最高含有点の高温強度不足を補う目的で、上記の従来（Ａｌ，Ｔｉ）Ｎ層と同等の組成、すなわち相対的にＴｉ含有割合が高く、一方Ａｌ含有量が低く、これによって相対的に高い高温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Ｔｉの割合を示すＸ値がＡｌ成分との合量に占める割合で０．３５未満では、所望のすぐれた高温強度を確保することができず、一方同Ｘ値が０．６０を越えると、Ａｌに対するＴｉの割合が多くなり過ぎて、Ａｌ最低含有点の高温硬さと耐熱性が不十分となり、摩耗促進の原因となることから、Ａｌ最低含有点でのＴｉの割合を示すＸ値を０．３５〜０．６０と定めた。
【００１３】
（ｃ）耐摩耗硬質層における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、この結果耐摩耗硬質層にすぐれた高温硬さと耐熱性、および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最高含有点であれば高温強度不足、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、これが原因で切刃にチッピングが発生し易くなったり、摩耗進行が促進されるようになることから、その間隔を０．０１〜０．１μmと定めた。
【００１４】
（ｄ）耐摩耗硬質層の平均層厚
その平均層厚が１μｍ未満では、耐摩耗硬質層のもつすぐれた耐摩耗性を長期に亘って発揮するには不十分であり、一方その平均層厚が１０μｍ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１〜１０μｍと定めた。
【００１５】
（ｅ）表面潤滑層の組成および平均層厚
表面潤滑層である（Ｃｒ，Ｓｉ）Ｎ層は、鋼や鋳鉄などの被削材に対してすぐれた潤滑性を有するが、硬さの低いＣｒＮ（マイクロビッカース硬さで約１８００）の硬さを向上させるためにＳｉを含有させたものであるが、Ｓｉの割合を示すＡ値がＣｒ成分との合量に占める割合で０．０１未満では、十分な硬さ向上効果を発揮することができず、一方同Ａ値が０．２０を越えると、硬さはマイクロビッカース硬さで２５００を越えて高くなるが、層自体の強度が急激に低下し、チッピングが発生し易くなることから、Ｓｉの割合を示すＡ値を０．０１〜０．２０と定めた。
また、その平均層厚が０．５μｍ未満では、所望の潤滑性向上効果を長期に亘って確保することができず、一方その平均層厚が５μｍ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０．５〜５μｍと定めた。
【００１６】
【発明の実施の形態】
つぎに、この発明の被覆超硬工具を実施例により具体的に説明する。
（実施例１）
原料粉末として、いずれも１〜３μｍの平均粒径を有するＷＣ粉末、ＴｉＣ粉末、ＺｒＣ粉末、ＳｉＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃr₃Ｃ₂粉末、ＴｉＮ粉末、ＴａＮ粉末、およびＣｏ粉末を用意し、これら原料粉末を、表１に示される配合組成に配合し、ボールミルで７２時間湿式混合し、乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を６Ｐａの真空中、温度：１４００℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０３のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１２０４０８のチップ形状をもったＷＣ基超硬合金製の超硬基体Ａ−１〜Ａ−１０を形成した。
【００１７】
また、原料粉末として、いずれも０．５〜２μｍの平均粒径を有するＴｉＣＮ（重量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ₂Ｃ粉末、ＺｒＣ粉末、ＮｂＣ粉末、ＴａＣ粉末、ＷＣ粉末、Ｃｏ粉末、およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで２４時間湿式混合し、乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を２ｋＰａの窒素雰囲気中、温度：１５００℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０３のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１２０４０８のチップ形状をもったＴｉＣＮ系サーメット製の超硬基体Ｂ−１〜Ｂ−６を形成した。
【００１８】
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の中心軸から半径方向に所定距離離れた位置に外周部にそって装着し、表面被覆層の耐摩耗硬質層形成に、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−Ｔｉ合金、他方側のカソード電極（蒸発源）として、種々の成分組成をもったＡｌ最低含有点形成用Ａｌ−Ｔｉ合金を前記回転テーブルを挟んで対向配置し、さらに同じくカソード電極として表面潤滑層形成用Ｃｒ−Ｓｉ合金およびボンバード洗浄用金属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Ｔｉ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３Ｐａ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−８０Ｖ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−Ｔｉ合金およびＡｌ最低含有点形成用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、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最低含有点から前記Ａｌ最高含有点、前記Ａｌ最高含有点から前記Ａｌ最低含有点へＡｌおよびＴｉの含有割合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に示される目標層厚の（Ａｌ，Ｔｉ）Ｎ層を表面被覆層の耐摩耗硬質層として蒸着形成し、ついで上記のＡｌ最高含有点形成用Ａｌ−Ｔｉ合金およびＡｌ最低含有点形成用Ａｌ−Ｔｉ合金のカソード電極とアノード電極との間のアーク放電を停止し、装置内の反応雰囲気を３Ｐａの窒素ガス雰囲気とした状態で、カソード電極である前記Ｃｒ−Ｓｉ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、同じく表３，４に示される目標組成および目標層厚の（Ｃｒ，Ｓｉ）Ｎ層を表面被覆層の表面潤滑層として蒸着形成することにより、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、本発明被覆チップと云う）１〜１６をそれぞれ製造した。
【００１９】
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、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（一方側のみ）およびＣｒ−Ｓｉ合金、さらに金属Ｔｉを装着し、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Ｔｉ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Ｔｉ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３Ｐａ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−８０Ｖに下げて、前記Ａｌ−Ｔｉ合金の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Ａ−１〜Ａ−１０およびＢ−１〜Ｂ−６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，Ｔｉ）Ｎ層を表面被覆層の耐摩耗硬質層として蒸着形成し、ついで前記Ａｌ−Ｔｉ合金のカソード電極とアノード電極との間のアーク放電を停止し、装置内の反応雰囲気を３Ｐａの窒素ガス雰囲気とした状態で、カソード電極である前記Ｃｒ−Ｓｉ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、前記（Ａｌ，Ｔｉ）Ｎ層に重ねて、同じく表５，６に示される目標組成および目標層厚の（Ｃｒ，Ｓｉ）Ｎ層を表面被覆層の表面潤滑層として蒸着形成することにより、比較被覆超硬工具としての比較表面被覆超硬合金製スローアウエイチップ（以下、比較被覆チップと云う）１〜１６をそれぞれ製造した。
【００２０】
つぎに、上記の各種の被覆チップを、いずれも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、本発明被覆チップ１〜１６および比較被覆チップ１〜１６について、
被削材：ＪＩＳ・ＳＣＭ４４０の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３３０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．１８ｍｍ／ｒｅｖ．、
切削時間：７分、
の条件での合金鋼の乾式断続高速切削加工試験（通常の切削速度は２００ｍ／ｍｉｎ．）、
被削材：ＪＩＳ・ＦＣ３００の丸棒、
切削速度：３３０ｍ／ｍｉｎ．、
切り込み：１．４ｍｍ、
送り：０．２０ｍｍ／ｒｅｖ．、
切削時間：７分、
の条件での鋳鉄の乾式連続高速切削加工試験（通常の切削速度は２００ｍ／ｍｉｎ．）、
被削材：ＪＩＳ・Ｓ４５Ｃの丸棒、
切削速度：３５０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．２２ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での炭素鋼の乾式連続高速切削加工試験（通常の切削速度は２５０ｍ／ｍｉｎ．）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。
【００２１】
【表１】

【００２２】
【表２】

【００２３】
【表３】

【００２４】
【表４】

【００２５】
【表５】

【００２６】
【表６】

【００２７】
【表７】

【００２８】
（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ＳｉＣ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２４時間ボールミル混合し、減圧乾燥した後、１００ＭＰａの圧力で所定形状の各種の圧粉体にプレス成形し、これらの圧粉体を、６Ｐａの真空雰囲気中、７℃／分の昇温速度で１３７０〜１４７０℃の範囲内の所定の温度に昇温し、この温度に１時間保持後、炉冷の条件で焼結して、直径が８ｍｍ、１３ｍｍ、および２６ｍｍの３種の超硬基体形成用丸棒焼結体を形成し、さらに前記の３種の丸棒焼結体から、研削加工にて、表７に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法、並びにいずれもねじれ角３０度の４枚刃スクエア形状をもったＷＣ基超硬合金製の超硬基体（エンドミル）Ｃ−１〜Ｃ−８をそれぞれ製造した。
【００２９】
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、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最低含有点から前記Ａｌ最高含有点、前記Ａｌ最高含有点から前記Ａｌ最低含有点へＡｌおよびＴｉ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、同じく表９に示される目標層厚の（Ａｌ，Ｔｉ）Ｎ層からなる耐摩耗硬質層と、同じく表９に示される目標組成および目標層厚の（Ｃｒ，Ｓｉ）Ｎ層からなる表面潤滑層で構成された表面被覆層を蒸着形成することにより、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、本発明被覆エンドミルと云う）１〜８をそれぞれ製造した。
【００３０】
また、比較の目的で、上記の超硬基体（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、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，Ｔｉ）Ｎ層からなる耐摩耗硬質層と、同じく表１０に示される目標組成および目標層厚の（Ｃｒ，Ｓｉ）Ｎ層からなる表面潤滑層で構成された表面被覆層を蒸着形成することにより、比較被覆超硬工具としての比較表面被覆超硬合金製エンドミル（以下、比較被覆エンドミルと云う）１〜８をそれぞれ製造した。
【００３１】
つぎに、上記本発明被覆エンドミル１〜８および比較被覆エンドミル１〜８のうち、本発明被覆エンドミル１〜３および比較被覆エンドミル１〜３については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・ＳＫＤ６１の板材、
切削速度：１８０ｍ／ｍｉｎ．、
溝深さ（切り込み）：２ｍｍ、
テーブル送り：８００ｍｍ／分、
の条件での工具鋼の乾式高速溝切削加工試験（通常の切削速度は６０ｍ／ｍｉｎ．）、本発明被覆エンドミル４〜６および比較被覆エンドミル４〜６については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・Ｓ４５Ｃの板材、
切削速度：２６０ｍ／ｍｉｎ．、
溝深さ（切り込み）：３ｍｍ、
テーブル送り：１２００ｍｍ／分、
の条件での炭素鋼の乾式高速溝切削加工試験（通常の切削速度は１００ｍ／ｍｉｎ．）、本発明被覆エンドミル７，８および比較被覆エンドミル７，８については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・ＳＮＣＭ４３９の板材、
切削速度：２４０ｍ／ｍｉｎ．、
溝深さ（切り込み）：７ｍｍ、
テーブル送り：５５０ｍｍ／分、
の条件での合金鋼の乾式高速溝切削加工試験（通常の切削速度は１００ｍ／ｍｉｎ．）をそれぞれ行い、いずれの溝切削加工試験でも切刃部の外周刃の逃げ面摩耗幅が使用寿命の目安とされる０．１ｍｍに至るまでの切削溝長を測定した。この測定結果を表９、１０にそれぞれ示した。
【００３２】
【表８】

【００３３】
【表９】

【００３４】
【表１０】

【００３５】
（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ＷＣ基超硬合金製の超硬基体（ドリル）Ｄ−１〜Ｄ−８をそれぞれ製造した。
【００３６】
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最低含有点から前記Ａｌ最高含有点、前記Ａｌ最高含有点から前記Ａｌ最低含有点へＡｌおよびＴｉ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１１に示される目標層厚の（Ａｌ，Ｔｉ）Ｎ層からなる耐摩耗硬質層と、同じく表１１に示される目標組成および目標層厚の（Ｃｒ，Ｓｉ）Ｎ層からなる表面潤滑層で構成された表面被覆層を蒸着形成することにより、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、本発明被覆ドリルと云う）１〜８をそれぞれ製造した。
【００３７】
また、比較の目的で、上記の超硬基体（ドリル）Ｄ−１〜Ｄ−８の表面に、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、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，Ｔｉ）Ｎ層からなる耐摩耗硬質層と、同じく表１２に示される目標組成および目標層厚の（Ｃｒ，Ｓｉ）Ｎ層からなる表面潤滑層で構成された表面被覆層を蒸着形成することにより、比較被覆超硬工具としての比較表面被覆超硬合金製ドリル（以下、比較被覆ドリルと云う）１〜８をそれぞれ製造した。
【００３８】
つぎに、上記本発明被覆ドリル１〜８および比較被覆ドリル１〜８のうち、本発明被覆ドリル１〜３および比較被覆ドリル１〜３については、
被削材−平面：１００ｍｍ×２５０、厚さ：５０ｍｍの寸法をもったＪＩＳ・Ｓ５０Ｃの板材、
切削速度：１６０ｍ／ｍｉｎ．、
送り：０．１４ｍｍ／ｒｅｖ、
穴深さ：８ｍｍ、
の条件での炭素鋼の湿式高速穴あけ切削加工試験（通常の切削速度は８０ｍ／ｍｉｎ．）、本発明被覆ドリル４〜６および比較被覆ドリル４〜６については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・ＦＣ３００の板材、
切削速度：２００ｍ／ｍｉｎ．、
送り：０．２３ｍｍ／ｒｅｖ、
穴深さ：１６ｍｍ、
の条件での鋳鉄の湿式高速穴あけ切削加工試験（通常の切削速度は１２０ｍ／ｍｉｎ．）、本発明被覆ドリル７，８および比較被覆ドリル７，８については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・ＳＣＭ４４０の板材、
切削速度：８０ｍ／ｍｉｎ．、
送り：０．２２ｍｍ／ｒｅｖ、
穴深さ：３２ｍｍ、
の条件での合金鋼の湿式高速穴あけ切削加工試験（通常の切削速度は４０ｍ／ｍｉｎ．）、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。
【００３９】
【表１１】

【００４０】
【表１２】

【００４１】
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チップ１〜１６、本発明被覆エンドミル１〜８、および本発明被覆ドリル１〜８の表面被覆層を構成する耐摩耗硬質層におけるＡｌ最低含有点とＡｌ最高含有点の組成、並びに比較被覆超硬工具としての比較被覆チップ１〜１６、比較被覆エンドミル１〜８、および比較被覆ドリル１〜８の表面被覆層の耐摩耗硬質層について、厚さ方向に沿ってＡｌおよびＴｉの含有量を透過型電子顕微鏡を用いてのエネルギー分散型Ｘ線分析法により測定したところ、前記本発明被覆超硬工具の耐摩耗硬質層を構成する（Ａｌ，Ｔｉ）Ｎ層では、Ａｌ最低含有点とＡｌ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最低含有点から前記Ａｌ最高含有点、前記Ａｌ最高含有点から前記Ａｌ最低含有点へＡｌおよびＴｉ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、一方前記比較被覆超硬工具の耐摩耗硬質層を構成する（Ａｌ，Ｔｉ）Ｎ層では厚さ方向に沿って組成変化が見られなかったが、目標組成と実質的に同じ組成を示した。
同じく上記の表面被覆層を構成する表面潤滑層の組成を測定したところ、目標組成と実質的に同じ組成を示した。
また、上記の表面被覆層の表面潤滑層および耐摩耗硬質層の層厚を走査型電子顕微鏡を用いて断面測定したところ、いずれも目標層厚と実質的に同じ平均値（５ヶ所測定の平均値）を示した。
【００４２】
【発明の効果】
表３〜１２に示される結果から、表面被覆層の耐摩耗硬質層が、層厚方向にＡｌ最高含有点と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最低含有点から前記Ａｌ最高含有点、前記Ａｌ最高含有点から前記Ａｌ最低含有点へＡｌおよびＴｉ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，Ｔｉ）Ｎ層からなる本発明被覆超硬工具は、いずれも鋼や鋳鉄の切削加工を高い発熱を伴う高速で行っても、前記表面被覆層の耐摩耗硬質層が相対的にすぐれた高温硬さと耐熱性を具備することから、同表面潤滑層との共存と相俟って、切削時にすぐれた耐摩耗性を発揮するのに対して、表面被覆層の耐摩耗硬質層が層厚方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ）Ｎ層からなる比較被覆超硬工具においては、高熱発生を伴う高速切削加工では、前記耐摩耗硬質層の高温硬さおよび耐熱性不足が原因で、切刃部の摩耗進行が速く、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、各種の鋼や鋳鉄などの通常の切削条件での切削は勿論のこと、特に高速切削条件で行なった場合にもすぐれた耐摩耗性を発揮し、長期に亘ってすぐれた切削性能を示すものであるから、切削加工装置の高性能化、並びに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】被覆超硬工具を構成する表面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】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 particular, the present invention has a high-temperature hardness and heat resistance with excellent wear-resistant hard layers in the surface coating layer, and also has excellent surface lubricity, and therefore, high-speed cutting with high heat generation particularly in various steels and cast irons. The present invention relates to a surface-coated cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide tool) that exhibits excellent wear resistance over a long period of time.
[0002]
[Prior art]
Generally, for coated carbide tools, a throw-away tip that is attached to the tip of a cutting tool for turning or flattening of various steel and cast iron work materials, 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, on the surface of a carbide substrate composed of tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet,
(A) As a surface lubricating layer, it has an average layer thickness of 0.5 to 5 μm, and a composition formula: (Cr_1- _A Si_A ) N (provided that atomic ratio, A represents 0.01 to 0.20), a composite nitride of Cr and Si [hereinafter referred to as (Cr, Si) N] layer,
(B) the wear-resistant hard layer has an average layer thickness of 1 to 10 μm, and
Composition formula: (Al_1-XTi_X) Al and Ti composite nitride [hereinafter referred to as (Al, Ti) N] layer satisfying N (wherein X represents 0.35 to 0.60 in atomic ratio), (a) and A coated carbide tool formed by physically vapor-depositing a surface coating layer made of (b) is known, and the (Al, Ti) N layer has a high temperature hardness and heat resistance due to Al as a component, and a high temperature due to the Ti. The coated carbide tool is particularly steel or cast iron because it has strength and the (Cr, Si) N layer has particularly low affinity to steel and cast iron and exhibits excellent lubricity. It is also known that excellent cutting performance is exhibited by continuous cutting and intermittent cutting of the above (see, for example, Patent Document 1).
[0004]
Furthermore, the above-mentioned coated cemented carbide tool is loaded with the above-mentioned cemented carbide substrate in an arc ion plating apparatus which is one type of physical vapor deposition apparatus shown schematically in FIG. An Al—Ti alloy and a Cr—Si alloy having a predetermined composition are set as electrodes (evaporation sources). First, the anode electrode and the Al—Ti are heated in a state where the apparatus is heated to, for example, a temperature of 500 ° C. with a heater. A current of, for example, 100 A is passed between the cathode electrode of the alloy to generate an arc discharge, and at the same time, nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of, for example, 3 Pa. For example, under the condition that a bias voltage of −1000 V is applied, an abrasion-resistant hard layer composed of the (Al, Ti) N layer is deposited as a surface coating layer on the surface of the cemented carbide substrate. In this state, for example, a current of 100 A is passed between the anode electrode and the cathode electrode of the Cr—Si alloy to generate an arc discharge, and the reaction atmosphere in the apparatus is kept unchanged and maintained in the same nitrogen gas atmosphere. It is also known that it is produced by forming a (Cr, Si) N layer as a surface lubricating layer on the wear-resistant hard layer (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP 2002-28804 A
[0006]
[Problems to be solved by the invention]
In recent years, the performance of cutting devices has been dramatically improved, while on the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting, and with this, cutting tends to be faster. In coated carbide tools, there is no problem when used under normal cutting conditions, but when this is used under high-speed cutting conditions with particularly high heat generation, the progress of wear of the surface coating layer is significantly accelerated. As a result, the service life is reached in a relatively short time.
[0007]
[Means for Solving the Problems]
In view of the above, the inventors of the present invention have developed the above-mentioned conventional coated carbide tool in order to develop a coated carbide tool that exhibits excellent wear resistance particularly in high-speed cutting. As a result of conducting research with a focus on
(A) The wear resistant hard layer made of (Al, Ti) N constituting the surface coating layer of the conventional coated carbide tool formed using the arc ion plating apparatus shown in FIG. An arc ion plating apparatus having a structure shown in FIG. 1A in a schematic plan view and in FIG. 1B in a schematic front view, Al-Ti used as a cathode electrode (evaporation source) for forming the above-mentioned conventional (Al, Ti) N layer on one side with a turntable for mounting a carbide substrate provided in the center of the apparatus and sandwiching the turntable. An arc ion in which an Al—Ti alloy having a composition corresponding to an alloy and having a relatively high Ti content and an Al—Ti alloy having a relatively low Ti content are arranged opposite to each other as a cathode electrode (evaporation source) The Using a coating device, a plurality of carbide substrates are mounted in a ring shape along the outer periphery at a predetermined distance in the radial direction from the central axis on the rotary table of the device. The cathode is disposed opposite to both sides of the rotary table while rotating the rotary table in a nitrogen atmosphere and rotating the carbide substrate itself for the purpose of uniforming the thickness of the vapor-deposited wear-resistant hard layer. When an arc discharge is generated between the (evaporation source) and the anode electrode to form an (Al, Ti) N layer on the surface of the cemented carbide substrate, the resulting (Al, Ti) N layer is rotated. When the carbide substrate arranged in a ring shape on the table is closest to the cathode electrode (evaporation source) of the Al-Ti alloy having a relatively high Ti content on one side, the lowest Al content is contained in the layer. And the highest Al content point is formed in the layer when the cemented carbide substrate is closest to the cathode electrode of the Al-Ti alloy having a relatively low Ti content on the other side. In the layer, the Al minimum content point and the Al maximum content point alternately appear at predetermined intervals along the layer thickness direction in the layer, and from the Al minimum content point to the Al maximum content point, the Al maximum content point To have a component concentration distribution structure in which the content ratios of Al and Ti continuously change from the lowest Al content point.
[0008]
(B) In the (Al, Ti) N layer having the repeated continuous change component concentration distribution structure of (A) above, for example, the respective compositions of the cathode electrodes (evaporation sources) arranged opposite to each other are prepared, and a carbide substrate is mounted. Control the rotation speed of the rotating table
The Al minimum content point is the composition formula: (Al_1-XTi_X) N (however, in atomic ratio, X represents 0.35 to 0.60),
The Al maximum content point is the composition formula: (Al_1-YTi_Y) N (however, in atomic ratio, Y represents 0.05 to 0.30),
And the distance between the adjacent Al minimum content point and Al maximum content point adjacent to each other in the thickness direction is 0.01 to 0.1 μm,
In the Al highest content point portion, the Al content is relatively higher than that of the conventional (Al, Ti) N layer described above, so that the higher Al hardness and heat resistance are further improved, while the Al minimum The content point portion has the same composition as the conventional (Al, Ti) N layer, that is, the Al content is relatively lower than the Al highest content point portion, and the composition has a high Ti content. Highly high temperature strength is maintained, and the distance between the Al minimum content point and the Al maximum content point is extremely small. Being equipped with sex.
[0009]
(C) Further, the (Al, Ti) N layer having the repeated continuous change component concentration distribution structure of the above (A) and (B) is vapor-deposited as an abrasion-resistant hard layer with an average layer thickness of 1 to 10 μm. An arc discharge is generated between the Cr—Si alloy disposed as a cathode electrode (evaporation source) in the apparatus and an anode electrode, and 0.5 to 0.5 μm is formed as a surface lubrication layer on the (Al, Ti) N layer. When the (Cr, Si) N layer is deposited by vapor deposition with an average layer thickness of 5 μm, the resulting surface coating layer is composed of the (Al, Ti) N layer constituting the wear-resistant hard layer. Due to the concentration distribution structure, it has superior high-temperature hardness and heat resistance as compared with the above-mentioned conventional (Al, Ti) N layer, and therefore the (Al, Ti) N layer and (Cr, Si) over which the surface coating layer is applied. ) N-layer coated carbide tool Combined with the effect of improving surface lubricity due to the (Cr, Si) N layer, it has excellent wear resistance even when used in high-speed cutting of various steels and cast irons with particularly high heat generation. To come to show.
The research results shown in (A) to (C) above were obtained.
[0010]
  This invention was made based on the above research results,Using an arc ion plating device with a rotating table for mounting a carbide substrate in the center of the device,
(A) The cathode electrode (evaporation source) of the arc ion plating apparatus is disposed opposite to the both sides of the rotary table, and the Al-Ti alloy for forming the Al highest content point is formed as the cathode electrode (evaporation source) on one side. The Al-Ti alloy for forming the lowest Al content point is disposed as the cathode electrode (evaporation source) on the other side, and along the outer peripheral portion of the table at a position radially away from the central axis on the rotary table. A plurality of the above-mentioned carbide substrates are mounted in a ring shape, and in this state, the atmosphere inside the apparatus is changed to a nitrogen atmosphere, the rotary table is rotated, and the carbide substrates themselves are rotated, while the cathode electrodes (evaporation sources) on both sides are rotated. ) And an anode electrode, and having an average layer thickness of 1 to 10 μm formed by vapor deposition on the surface of the cemented carbide substrate.,
  Along the layer thickness direction, the Al highest content point and the Al lowest content point are alternately present at predetermined intervals, and the Al highest content point to the Al lowest content point, the Al lowest content point to the Al It has a component concentration distribution structure in which the content ratios of Al and Ti continuously change to the highest content point,
  Further, the Al minimum content point is the composition formula: (Al_1- _XTi_X) N (however, in atomic ratio, X represents 0.35 to 0.60),
  The Al maximum content point is the composition formula: (Al_1- _YTi_Y) N (however, in atomic ratio, Y represents 0.05 to 0.30),
A wear-resistant hard layer composed of an (Al, Ti) N layer, wherein the distance between the Al minimum content point and the Al maximum content point adjacent to each other is 0.01 to 0.1 μm,
(B)Similarly, while rotating the rotary table with the atmosphere inside the apparatus as a nitrogen atmosphere and rotating the carbide substrate itself, which is also mounted in a ring shape on the rotary table, facing the rotary table, the arc ion plating is performed. An arc discharge is generated between the Cr—Si alloy arranged as the cathode electrode (evaporation source) of the apparatus and the anode electrode, and the wear-resistant hard layer deposited on the surface of the carbide substrate on the rotary table is formed on the wear-resistant hard layer. Having an average layer thickness of 0.5 to 5 μm,
  Composition formula: (Cr_1- _ASi_A) N (however, in atomic ratio, A represents 0.01 to 0.20),
A surface lubrication layer comprising a (Cr, Si) N layer satisfying
The present invention is characterized by a coated carbide tool which is formed by vapor-depositing the surface coating layer comprising the above (a) and (b) and exhibits excellent wear resistance in the high-speed cutting process.
[0011]
Next, in the coated carbide tool of the present invention, the reason why the configuration of the surface coating layer constituting the tool is limited as described above will be described.
(A) Composition of Al highest content point in wear-resistant hard layer
The Al component in (Al, Ti) N at the highest Al content point improves high-temperature hardness and heat resistance, while the Ti component has the effect of improving high-temperature strength. The Ti content is reduced and the Al content is increased to provide excellent high-temperature hardness and heat resistance suitable for high-speed cutting with high heat generation, but the Y value indicating the Ti ratio is Al. When the ratio to the total amount with (the atomic ratio, the same shall apply hereinafter) is less than 0.05, the ratio of Al becomes relatively large, and even if the lowest Al content point having high temperature strength exists adjacently Decrease in high-temperature strength of the layer itself is inevitable, and as a result, chipping or the like is likely to occur. On the other hand, when the Y value indicating the Ti ratio exceeds 0.30, the Al ratio is relatively decreased. Excellent high-temperature hardness required for high-speed cutting It can not be ensured heat resistance, may cause abrasion accelerator, defining a Y value 0.05 to 0.30.
[0012]
(B) Composition of Al minimum content point in wear-resistant hard layer
As described above, the Al highest content point is excellent in high temperature hardness and heat resistance, but on the other hand, it is inferior in high temperature strength. Therefore, the above conventional (Al , Ti) The composition equivalent to that of the N layer, that is, the Ti content ratio is relatively high, while the Al content is low, and the Al minimum content point having a relatively high high-temperature strength is alternated in the thickness direction. Therefore, if the X value indicating the proportion of Ti is less than 0.35 in the total amount with the Al component, the desired excellent high-temperature strength cannot be secured, while the X value is the same. If it exceeds 0.60, the ratio of Ti to Al becomes too large, the high temperature hardness and heat resistance of the Al minimum content point becomes insufficient, and causes wear promotion. X value indicating the percentage of It was defined as .35～0.60.
[0013]
(C) The distance between the highest Al content point and the lowest Al content point in the wear-resistant hard layer
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, excellent high temperature hardness and heat resistance, and high temperature strength can be secured in the wear resistant hard layer. When the distance exceeds 0.1 μm, each point has defects, that is, high-temperature strength is insufficient at the highest Al content point, and high-temperature hardness and insufficient heat resistance are localized within the layer at the Al lowest content point. Therefore, the chipping is likely to occur on the cutting edge, and the progress of wear is promoted. Therefore, the interval is set to 0.01 to 0.1 μm.
[0014]
(D) Average layer thickness of the wear-resistant hard layer
If the average layer thickness is less than 1 μm, it is insufficient to exhibit the excellent wear resistance of the wear-resistant hard layer over a long period. On the other hand, if the average layer thickness exceeds 10 μm, chipping occurs at the cutting edge. Since it becomes easy to generate | occur | produce, the average layer thickness was set to 1-10 micrometers.
[0015]
(E) Composition and average layer thickness of the surface lubricating layer
The (Cr, Si) N layer, which is a surface lubrication layer, has excellent lubricity for work materials such as steel and cast iron, but has a low hardness of CrN (micro Vickers hardness of about 1800). However, when the A value indicating the proportion of Si is less than 0.01 in the total amount with the Cr component, a sufficient hardness improvement effect can be exhibited. On the other hand, if the A value exceeds 0.20, the hardness increases by over 2500 in terms of micro Vickers hardness, but the strength of the layer itself decreases rapidly, and chipping is likely to occur. The A value indicating the proportion of Si was determined to be 0.01 to 0.20.
If the average layer thickness is less than 0.5 μm, the desired lubricity improvement effect cannot be ensured over a long period of time. On the other hand, if the average layer thickness exceeds 5 μm, chipping tends to occur at the cutting edge. Therefore, the average layer thickness was set to 0.5 to 5 μm.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated carbide tool of the present invention will be specifically described with reference to examples.
Example 1
As raw material powders, WC powder, TiC powder, ZrC powder, SiC powder, TaC powder, NbC powder, Cr, all having an average particle diameter of 1 to 3 μm._ThreeC₂Powder, TiN powder, TaN powder, and Co powder are prepared. These raw material powders are blended in the blending composition shown in Table 1, wet-mixed by a ball mill for 72 hours, dried, and then compacted at a pressure of 100 MPa. The green compact was sintered in a vacuum of 6 Pa at a temperature of 1400 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.03 and ISO Cemented carbide substrates A-1 to A-10 made of a WC-based cemented carbide having a standard / CNMG120408 chip shape were formed.
[0017]
Moreover, as raw material powders, TiCN (TiC / TiN = 50/50 by weight) 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 in the blending composition shown in Table 2, and are wet-mixed for 24 hours in a ball mill 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 1500 ° C. for 1 hour. A 0.03 honing process was performed to form carbide substrates B-1 to B-6 made of TiCN cermet having ISO standard / CNMG120408 chip shape.
[0018]
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. Attached along the outer periphery at a predetermined distance in the radial direction from the center axis of the rotary table, various components can be used as a cathode electrode (evaporation source) on one side to form a wear-resistant hard layer of the surface coating layer An Al-Ti alloy for forming the highest Al content point having a composition, and an Al-Ti alloy for forming the lowest Al content point having various components as the cathode electrode (evaporation source) on the other side, sandwiching the rotary table. Furthermore, Cr-Si alloy for surface lubrication layer formation and metal Ti for bombard cleaning were also mounted as cathode electrodes, and the apparatus was first evacuated and kept at a vacuum of 0.5 Pa or less with a heater. After heating the interior to 500 ° C., a DC bias voltage of −1000 V is applied to a carbide substrate that rotates while rotating on the rotary table, and 100 A is applied between the metal Ti of the cathode electrode and the anode electrode. An electric current is applied to generate an arc discharge, and the surface of the carbide substrate is cleaned with Ti bombardment. Then, nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 3 Pa, while rotating on the rotary table. A DC bias voltage of −80 V is applied to the rotating carbide substrate, and each cathode electrode (the Al-Ti alloy for forming the highest Al content point and the Al—Ti alloy for forming the lowest Al content point) and the anode electrode A current of 100 A was passed between them to generate an arc discharge, so that the target composition A shown in Tables 3 and 4 along the layer thickness direction was formed on the surface of the carbide substrate. The highest content point and the lowest Al content point are alternately repeated at the target intervals shown in Tables 3 and 4, and from the lowest Al content point to the highest Al content point, from the highest Al content point to the lowest Al content. It has a component concentration distribution structure in which the content ratio of Al and Ti continuously changes to the point of inclusion, and the (Al, Ti) N layer having the target layer thickness shown in Tables 3 and 4 is also used for the wear resistance of the surface coating layer. Then, the arc discharge between the cathode electrode and the anode electrode of the Al-Ti alloy for forming the highest Al content point and the Al-Ti alloy for forming the lowest Al content point is stopped. In a state where the reaction atmosphere is a nitrogen gas atmosphere of 3 Pa, an arc discharge is generated by flowing a current of 100 A between the Cr—Si alloy as the cathode electrode and the anode electrode, which are also shown in Tables 3 and 4. By forming a (Cr, Si) N layer having a standard composition and a target layer thickness as a surface lubrication layer of the surface coating layer, a throwaway tip made of the surface coated cemented carbide of the present invention (hereinafter referred to as a cemented carbide tool of the present invention) 1 to 16) were produced.
[0019]
For the purpose of comparison, these carbide substrates A-1 to A-10 and B-1 to B-6 were ultrasonically cleaned in acetone and dried, respectively, and the arc ions shown in FIG. Inserted into the plating device and mounted as cathode electrode (evaporation source) with Al-Ti alloy (only one side) and Cr-Si alloy with various components, and metal Ti. Then, 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 DC bias voltage of −1000 V was applied to the cemented carbide substrate, and the metal Ti and anode electrode of the cathode electrode A current of 100 A is passed between them to generate an arc discharge, so that the surface of the carbide substrate is cleaned with Ti bombardment, and then nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 3 Pa. At the same time, the bias voltage applied to the cemented carbide substrate is lowered to −80 V, and arc discharge is generated between the cathode electrode and the anode electrode of the Al—Ti alloy, so that the cemented carbide substrates A-1 to A— 10 and B-1 to B-6 have the target compositions and target layer thicknesses shown in Tables 5 and 6 on the respective surfaces and substantially no composition change along the layer thickness direction (Al, Ti ) N layer is deposited as a wear-resistant hard layer of the surface coating layer, and then the arc discharge between the cathode electrode and the anode electrode of the Al-Ti alloy is stopped, and the reaction atmosphere in the apparatus is a nitrogen gas atmosphere of 3 Pa. In this state, a current of 100 A is passed between the Cr—Si alloy as the cathode electrode and the anode electrode to generate an arc discharge, which is also superimposed on the (Al, Ti) N layer, as shown in Tables 5 and 6 Goal group shown in And a comparative surface-coated cemented carbide throwaway tip (hereinafter referred to as a comparative coated tip) as a comparative coated carbide tool by vapor-depositing a (Cr, Si) N layer having a target layer thickness as a surface lubricating layer of the surface coating layer 1 to 16 were produced.
[0020]
Next, in the state where each of the above various coated chips is screwed to the tip of the tool steel tool with a fixing jig, the present coated chips 1-16 and the comparative coated chips 1-16,
Work material: JIS · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 330 m / min. ,
Incision: 1.5mm,
Feed: 0.18 mm / rev. ,
Cutting time: 7 minutes
Dry interrupted high-speed cutting test of alloy steel under the conditions of (normal cutting speed is 200 m / min.),
Work material: JIS / FC300 round bar,
Cutting speed: 330 m / min. ,
Cutting depth: 1.4mm,
Feed: 0.20 mm / rev. ,
Cutting time: 7 minutes
A dry continuous high speed cutting test of cast iron under the conditions of (normal cutting speed is 200 m / min.),
Work material: JIS / S45C round bar,
Cutting speed: 350 m / min. ,
Incision: 1.5mm,
Feed: 0.22 mm / rev. ,
Cutting time: 8 minutes
The dry continuous high-speed cutting test (normal cutting speed was 250 m / min.) Of carbon steel under the conditions of (2) was performed, and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 7.
[0021]
[Table 1]

[0022]
[Table 2]

[0023]
[Table 3]

[0024]
[Table 4]

[0025]
[Table 5]

[0026]
[Table 6]

[0027]
[Table 7]

[0028]
(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 SiC powder, 1.0 μm (Ti, W) C [mass ratio, TiC / WC = 50/50] powder, and 1.8 μm Co powder. Each powder was blended into the blending composition shown in Table 8, further added with wax, ball mill mixed in acetone for 24 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 each Carbide substrates (end mills) C-1 to C-made of WC-base cemented carbide having dimensions of mm × 13 mm, 10 mm × 22 mm, and 20 mm × 45 mm, and a four-blade square shape with a twist angle of 30 degrees. 8 were produced respectively.
[0029]
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. 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 are alternately present at the same target interval shown in Table 9, and It has a component concentration distribution structure in which the content ratios of Al and Ti continuously change from the lowest Al content point to the highest Al content point and from the highest Al content point to the lowest Al content point. Surface composed of a wear-resistant hard layer composed of an (Al, Ti) N layer having a target layer thickness and a surface lubricating layer composed of a (Cr, Si) N layer having the target composition and target layer thickness also shown in Table 9 Evaporate the coating layer And, the present invention surface-coated cemented carbide end mill of the present invention coated cemented carbide (hereinafter, the present invention refers to the coating end mill) 1-8 were prepared, respectively.
[0030]
For the purpose of comparison, the surfaces of the above-mentioned carbide substrates (end mills) C-1 to C-8 are ultrasonically cleaned in acetone and dried, and the arc ion plating apparatus shown in FIG. (Al, Ti) N layer having the target composition and target layer thickness shown in Table 10 and having substantially no composition change along the layer thickness direction under the same conditions as in Example 1 above. And a surface coating layer composed of a surface lubrication layer composed of a (Cr, Si) N layer having the target composition and target layer thickness shown in Table 10 by vapor deposition. Comparative surface-coated cemented carbide end mills (hereinafter referred to as comparative coated end mills) 1 to 8 as hard tools were produced.
[0031]
Next, of the present invention coated end mills 1-8 and comparative coated end mills 1-8, the present invention coated end mills 1-3 and comparative coated end mills 1-3 are as follows:
Work material-Plane: 100 mm x 250 mm, JIS SKD61 plate material with thickness: 50 mm,
Cutting speed: 180 m / min. ,
Groove depth (cut): 2 mm,
Table feed: 800mm / min,
With respect to the tool steel dry high-speed grooving test (normal cutting speed is 60 m / min.), The present invention coated end mills 4-6 and comparative coated end mills 4-6,
Work material-Plane: 100 mm x 250 mm, thickness: 50 mm JIS / S45C plate material,
Cutting speed: 260 m / min. ,
Groove depth (cut): 3 mm,
Table feed: 1200mm / min,
With respect to the dry high-speed grooving test of carbon steel under the conditions (normal cutting speed is 100 m / min.), The coated end mills 7 and 8 and the comparative coated end mills 7 and 8 of the present invention,
Work material-Plane: 100 mm x 250 mm, thickness: 50 mm JIS / SNCM439 plate material,
Cutting speed: 240 m / min. ,
Groove depth (cut): 7 mm,
Table feed: 550 mm / min,
The dry high-speed grooving test of the alloy steel under the conditions (normal cutting speed is 100 m / min.) Is performed, and the flank wear width of the outer peripheral edge of the cutting edge is the service life in any grooving test. The cutting groove length up to 0.1 mm as a standard was measured. The measurement results are shown in Tables 9 and 10, respectively.
[0032]
[Table 8]

[0033]
[Table 9]

[0034]
[Table 10]

[0035]
(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 made of a WC-base cemented carbide having a two-blade shape with a twist angle of 30 degrees were produced.
[0036]
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 a component concentration distribution structure in which the content ratios of Al and Ti continuously change from the lowest Al content point to the highest Al content point and from the highest Al content point to the lowest Al content point. And a wear-resistant hard layer composed of an (Al, Ti) N layer having a target layer thickness also shown in Table 11, and a surface composed of a (Cr, Si) N layer having a target composition and target layer thickness also shown in Table 11. Consists of a lubrication layer The surface coating layer by vapor deposition formation, the present invention surface-coated cemented carbide drills of the present invention coated cemented carbide (hereinafter, the present invention refers to the coating drills) 1-8 were prepared, respectively.
[0037]
For the purpose of comparison, the surfaces of the above-mentioned carbide substrates (drills) D-1 to D-8 are honed, ultrasonically cleaned in acetone and dried, and the arc shown in FIG. The sample was charged in the 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 no composition change along the layer thickness direction (Al , Ti) A wear-resistant hard layer composed of an N layer and a surface coating layer composed of a surface lubricating layer composed of a (Cr, Si) N layer having the target composition and target layer thickness shown in Table 12 by vapor deposition. The comparative surface-coated cemented carbide drills (hereinafter referred to as comparative coated drills) 1 to 8 as comparative coated carbide tools were produced.
[0038]
Next, of the present invention coated drills 1-8 and comparative coated drills 1-8, for the present invention coated drills 1-3 and comparative coated drills 1-3,
Work material-Plane: 100 mm × 250, thickness: 50 mm JIS / S50C plate,
Cutting speed: 160 m / min. ,
Feed: 0.14mm / rev,
Hole depth: 8mm,
The wet high speed drilling test of carbon steel under the conditions (normal cutting speed is 80 m / min.), The present invention coated drills 4-6 and comparative coated drills 4-6,
Work material-Plane: 100 mm x 250 mm, thickness: 50 mm plate material of JIS / FC300,
Cutting speed: 200 m / min. ,
Feed: 0.23mm / rev,
Hole depth: 16mm,
With regard to the cast iron wet high speed drilling cutting test under the conditions (normal cutting speed is 120 m / min.), The present invention coated drills 7 and 8 and the comparative coated drills 7 and 8,
Work material-Plane: 100 mm × 250 mm, thickness: 50 mm, JIS / SCM440 plate,
Cutting speed: 80 m / min. ,
Feed: 0.22mm / rev,
Hole depth: 32mm,
Wet high-speed drilling test (normal cutting speed is 40 m / min.) Of alloy steel under the above conditions, respectively. In any wet high-speed drilling test (using water-soluble cutting oil), the tip cutting edge surface The number of drilling processes until the flank wear width reached 0.3 mm was measured. The measurement results are shown in Tables 11 and 12, respectively.
[0039]
[Table 11]

[0040]
[Table 12]

[0041]
As a result, Al in the wear-resistant hard layer constituting the surface coating layer of the present coated chips 1-16, the present coated end mills 1-8, and the present coated drills 1-8 as the present coated carbide tool. Composition of lowest content point and highest Al content point, and wear resistant hard layer of surface coating layer of comparative coated tip 1-16, comparative coated end mill 1-8, and comparative coated drill 1-8 as comparative coated carbide tool Then, the content of Al and Ti along the thickness direction was measured by energy dispersive X-ray analysis using a transmission electron microscope. As a result, the wear-resistant hard layer of the coated carbide tool of the present invention was formed ( In the Al, Ti) N layer, the lowest Al content point and the highest Al content point are alternately and repeatedly present at substantially the same composition and interval as the target value, and the lowest Al content point from the lowest Al content point. It is confirmed that it has a component concentration distribution structure in which the content ratios of Al and Ti continuously change from the content point, the Al highest content point to the Al minimum content point, while the comparative coated carbide tool is hard to wear. In the (Al, Ti) N layer constituting the layer, no composition change was observed along the thickness direction, but the composition was substantially the same as the target composition.
Similarly, when the composition of the surface lubricating layer constituting the surface coating layer was measured, the composition was substantially the same as the target composition.
In addition, when the thickness of the surface lubrication layer and the wear-resistant hard layer of the surface coating layer was measured by cross-section using a scanning electron microscope, the average value was substantially the same as the target layer thickness (the average of five measurements). Value).
[0042]
【The invention's effect】
From the results shown in Tables 3 to 12, the wear-resistant hard layer of the surface coating layer has the Al highest content point and the Al lowest content point alternately present at predetermined intervals in the layer thickness direction, and the Al minimum content. A book composed of an (Al, Ti) N layer having a component concentration distribution structure in which the content ratio of Al and Ti continuously changes from the content point to the Al highest content point and from the Al highest content point to the Al minimum content point. Inventive coated carbide tools should have high-temperature hardness and heat resistance with relatively superior wear-resistant hard layers of the surface coating layer, even when cutting steel and cast iron at high speed with high heat generation. Therefore, combined with coexistence with the same surface lubrication layer, it exhibits excellent wear resistance during cutting, whereas the hard layer of the surface coating layer changes substantially in the thickness direction. Comparative coating consisting of an (Al, Ti) N layer without any For hard tools, in high-speed cutting with high heat generation, due to the high-temperature hardness and insufficient heat resistance of the wear-resistant hard layer, the wear of the cutting edge is fast and the service life is reached in a relatively short time. Is clear.
As described above, the coated carbide tool of the present invention exhibits excellent wear resistance not only when cutting under normal cutting conditions such as various types of steel and cast iron, but particularly when performed under high-speed cutting conditions. In addition, since it shows excellent cutting performance over a long period of time, it can sufficiently satisfactorily cope with higher performance of the cutting device, labor saving and energy saving of cutting, and further cost reduction.
[Brief description of the drawings]
FIG. 1 shows an arc ion plating apparatus used to form a surface coating layer constituting a coated carbide tool, wherein (a) is a schematic plan view and (b) is a schematic front view.
FIG. 2 is a schematic explanatory diagram of a normal arc ion plating apparatus.

Claims

Using an arc ion plating apparatus provided with a rotating table for mounting a cemented carbide substrate composed of either or both of a tungsten carbide base cemented carbide and a titanium carbonitride cermet in the center of the apparatus,
(A) The cathode electrode (evaporation source) of the arc ion plating apparatus is disposed opposite to the both sides of the rotary table, and the Al-Ti alloy for forming the Al highest content point is formed as the cathode electrode (evaporation source) on one side. The Al-Ti alloy for forming the lowest Al content point is disposed as the cathode electrode (evaporation source) on the other side, and along the outer peripheral portion of the table at a position radially away from the central axis on the rotary table. A plurality of the above-mentioned carbide substrates are mounted in a ring shape, and in this state, the atmosphere inside the apparatus is changed to a nitrogen atmosphere, the rotary table is rotated, and the carbide substrates themselves are rotated, while the cathode electrodes (evaporation sources) on both sides are rotated. ) And the anode electrode, and having an average layer thickness of 1 to 10 μm formed by vapor deposition on the surface of the cemented carbide substrate ,
Along the layer thickness direction, the Al highest content point and the Al lowest content point are alternately present at predetermined intervals, and the Al highest content point to the Al lowest content point, the Al lowest content point to the Al It has a component concentration distribution structure in which the content ratios of Al and Ti continuously change to the highest content point,
Furthermore, the Al minimum content point, the composition _{_{_{formula: (Al 1- X Ti X)}}} N ( provided that an atomic ratio, X is shows the 0.35 to 0.60),
The Al highest content point, the composition _{_{_{formula: (Al 1- Y Ti Y)}}} N ( provided that an atomic ratio, Y denotes the 0.05 to 0.30),
A wear-resistant hard layer made of a composite nitride layer of Al and Ti, wherein the distance between the Al minimum content point and the Al maximum content point adjacent to each other is 0.01 to 0.1 μm,
(B) The rotating table is rotated with the atmosphere in the apparatus as a nitrogen atmosphere, and the carbide substrate itself, which is also mounted in a ring shape on the rotating table, is rotated while facing the rotating table and the arc. The wear-resistant hard layer formed by vapor deposition on the surface of the cemented carbide substrate on the rotary table by generating an arc discharge between a Cr-Si alloy disposed as a cathode electrode (evaporation source) of the ion plating apparatus and an anode electrode Having an average layer thickness of 0.5 to 5 μm ,
Composition formula: (Cr _1- _A Si _A ) N (where A represents 0.01 to 0.20 in atomic ratio),
A surface lubrication layer comprising a composite nitride layer of Cr and Si satisfying
A surface-coated cemented carbide cutting tool that exhibits excellent wear resistance when the surface coating layer is formed by vapor deposition of the surface coating layer comprising the above (a) and (b).