JP4244377B2

JP4244377B2 - Surface coated cermet cutting tool with excellent wear resistance with high hard coating layer in high speed cutting

Info

Publication number: JP4244377B2
Application number: JP2003160224A
Authority: JP
Inventors: 和則佐藤; 裕介田中; 暁裕近藤
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2003-06-05
Filing date: 2003-06-05
Publication date: 2009-03-25
Anticipated expiration: 2023-06-05
Also published as: JP2004358610A

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層がすぐれた高温硬さおよび耐熱性を有し、さらに層間密着性にもすぐれ、したがって特に各種の鋼や鋳鉄などの高熱発生を伴い、かつ高負荷のかかる高速切削加工で、長期に亘ってすぐれた耐摩耗性を発揮する表面被覆サーメット製切削工具（以下、被覆サーメット工具という）に関するものである。
【０００２】
【従来の技術】
一般に、被覆サーメット工具には、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、被覆サーメット工具として、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サーメット基体の表面に、
（ａ）表面層として、０．５〜１０μｍの平均層厚を有する酸化クロム（以下、Ｃｒ_２Ｏ_３で示す）層、
（ｂ）下側層として、０．５〜１０μｍ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）からなる硬質被覆層を物理蒸着してなる被覆サーメット工具が知られており、この被覆サーメット工具における前記Ｃｒ_２Ｏ_３層が高温硬さと耐熱性、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することから、前記被覆サーメット工具を各種の鋼や鋳鉄など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、上記の被覆サーメット工具が、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サーメット基体を装入し、ヒータで装置内を、例えば５００℃の温度に加熱した状態で、それぞれカソード電極（蒸発源）として設置された、所定組成を有するＡｌ−Ｔｉ合金と金属Ｃｒのうちの前記Ａｌ−Ｔｉ合金とアノード電極との間に、例えば電流：１００Ａ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３Ｐａの反応雰囲気とし、一方上記サーメット基体には、例えば−１００Ｖのバイアス電圧を印加した条件で、前記サーメット基体の表面に、硬質被覆層の下側層として上記（Ａｌ，Ｔｉ）Ｎ層を蒸着し、ついで反応ガスを窒素ガスから酸素ガスに変え、装置内の雰囲気を１．５Ｐａの酸素雰囲気とし、前記サーメット基体には、例えば−１５０Ｖのバイアス電圧を印加し、前記金属Ｃｒとアノード電極との間に、例えば電流：１００Ａの条件でアーク放電を発生させ、前記サーメット基体の表面に、硬質被覆層の表面層としてＣｒ_２Ｏ_３層を蒸着することにより製造されることも知られている（例えば特許文献１参照）。
【０００５】
【特許文献１】
特開２０００−２３３３２４
【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、上記の従来被覆サーメット工具においては、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、これを高い発熱を伴ない、かつ高負荷のかかる高速切削に用いた場合、硬質被覆層の下側層である上記（Ａｌ，Ｔｉ）Ｎ層が高温硬さおよび耐熱性不足のために熱塑性変形を起こし易く、このように熱塑性変形を起こすと、前記（Ａｌ，Ｔｉ）Ｎ層と表面層であるＣｒ_２Ｏ_３層との密着性が十分でないことと相俟って、前記両層間に剥離が発生するのが避けられず、この結果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長期に亘ってすぐれた切削性能を発揮する被覆サーメット工具を開発すべく、上記の従来被覆サーメット工具を構成する硬質被覆層に着目し、研究を行った結果、
（Ａ）（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サーメット工具を構成する硬質被覆層のうちの（Ａｌ，Ｔｉ）Ｎ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サーメット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サーメット基体をリング状に装着し、この状態で装置内雰囲気を窒素雰囲気として前記回転テーブルを回転させると共に、蒸着形成される硬質被覆層の層厚均一化を図る目的でサーメット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、前記サーメット基体の表面に（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サーメット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、また前記サーメット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、サーメット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有し、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、すぐれた高温硬さと耐熱性を有し、一段とすぐれた熱塑性変形性を具備するようになること。
【０００９】
（Ｂ）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０．５〜１０μｍの平均層厚で下側層として蒸着形成し、これに重ねて中間層として０．１〜５μｍの平均層厚で窒化クロム（以下、ＣｒＮで示す）を蒸着形成した状態で、表面層としてのＣｒ_２Ｏ_３層を０．５〜１０μｍの平均層厚で蒸着形成すると、この結果の硬質被覆層では、下側層である上記繰り返し連続変化成分濃度分布構造の（Ａｌ，Ｔｉ）Ｎ層が上記従来（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し、この結果耐熱塑性変形性が一段と向上したものになり、さらに中間層であるＣｒＮ層が前記下側層の（Ａｌ，Ｔｉ）Ｎ層と表面層のＣｒ_２Ｏ_３層のいずれにも強固に密着することから、かかる硬質被覆層を形成してなる被覆サーメット工具は、高い発熱を伴い、かつ高負荷のかかる鋼や鋳鉄などの高速切削加工に用いた場合にも層間剥離の発生なく、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）および（Ｂ）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、装置中央部にサーメット基体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サーメット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、前記サーメット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、前記サーメット基体の表面に蒸着してなる、０．５〜１０μｍ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層からなる下側層、
（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サーメット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）として配置した金属Ｃｒとアノード電極との間アーク放電を発生させて、前記回転テーブル上の前記サーメット基体表面に蒸着形成した上記下側層に重ねて蒸着してなる、０．１〜５μｍの平均層厚を有するＣｒＮ層からなる中間層、
（ｃ）さらに装置内雰囲気を酸素ガス雰囲気として、同じく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サーメット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）として配置した金属Ｃｒ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サーメット基体表面に蒸着形成した上記中間層に重ねて蒸着してなる、０．５〜１０μｍの平均層厚を有するＣｒ _２Ｏ _３層からなる表面層、
以上（ａ）〜（ｃ）からなる硬質被覆層を蒸着形成してなる、高速切削加工で硬質被覆層がすぐれた耐摩耗性を発揮する被覆サーメット工具に特徴を有するものである。
【００１１】
つぎに、この発明の被覆サーメット工具において、これを構成する硬質被覆層の構成を上記の通りに限定した理由を説明する。
（ａ）下側層における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、相対的に高温硬さと耐熱性を向上させて、高速切削で発生する高熱にも塑性変形しないすぐれた高温硬さと耐熱性を具備せしめ、熱塑性変形が原因の層間剥離を防止するようにしたものであるが、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、相対的に高い高温強度を有する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、この結果切刃部に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、高速切削で熱塑性変形の発生を抑制するに足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ることから、Ｙ値を０．０５〜０．３０と定めた。
【００１２】
（ｂ）下側層における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、所望の高温強度を確保することができず、この場合切刃部にチッピングの発生が避けられず、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、熱塑性変形発生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）下側層における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、この結果下側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、熱塑性変形が原因の層間剥離が発生し易くなることから、その間隔を０．０１〜０．１μmと定めた。
【００１４】
（ｄ）下側層の平均層厚
その平均層厚が０．５μｍ未満では、硬質被覆層に上記下側層のもつすぐれた高温強度を十分に付与せしめることができず、この結果切刃部にチッピングが発生し易くなり、またその平均層厚が１０μｍを越えて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０．５〜１０μｍと定めた。
【００１５】
（ｄ）中間層の平均層厚
中間層のＣｒＮ層には、上記の通り下側層の（Ａｌ，Ｔｉ）Ｎ層および表面層のＣｒ_２Ｏ_３層のいずれにも強固に密着して、これら両層間の密着性を著しく向上させ、高発熱および高負荷を伴なう高速切削でも層間剥離の発生を防止する作用があるが、その平均層厚が０．１μｍ未満では、所望のすぐれた層間密着性を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、ＣｒＮ層自体相対的に軟質であるために、これが原因で硬質被覆層に熱塑性変形が発生し、この結果摩耗が摩耗促進の原因となる偏摩耗形態をとるようになることから、その平均層厚を０．１〜５μｍと定めた。
【００１６】
（ｅ）表面層の平均層厚
硬質被覆層は、上記の通り下側層のもつ高温強度と熱塑性変形を起こさない高温硬さおよび耐熱性、さらに表面層であるＣｒ_２Ｏ_３層のもつすぐれた高温硬さと耐熱性の共存によって、高発熱および高負荷を伴なう高速切削ですぐれた耐摩耗性を発揮するようになるものであるが、その平均層厚が０．５μｍ未満では、硬質被覆層のもつ上記特性を十分に発揮させることができず、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０．５〜１０μｍと定めた。
【００１７】
【発明の実施の形態】
つぎに、この発明の被覆サーメット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、ＶＣ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基超硬合金製のサーメット基体Ａ−１〜Ａ−１０を形成した。
【００１８】
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系サーメット製のサーメット基体Ｂ−１〜Ｂ−６を形成した。
【００１９】
ついで、上記のサーメット基体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、硬質被覆層の下側層形成に、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上側層および中間層形成用金属Ｃｒも装着し、前記金属Ｃｒはボンバード洗浄にも使用し、まず装置内を排気して０．５Ｐａの真空に保持しながら、ヒーターで装置内を７００℃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サーメット基体に−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、もってサーメット基体表面を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サーメット基体に−１００Ｖ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、もって前記サーメット基体の表面に、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層を硬質被覆層の下側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、３Ｐａの窒素雰囲気を維持した状態で、前記金属Ｃｒとアノード電極との間に１２０Ａの電流を流してアーク放電を発生させ、同じく表３，４に示される目標層厚のＣｒＮ層を硬質被覆層の中間層として蒸着形成し、さらに装置内に導入する反応ガスを酸素ガスに切り替えて、装置内を１．５Ｐａの酸素雰囲気とすると共に、前記サーメット基体に印可する電圧を−１５０Ｖのパルスバイアス電圧とし、かつカソード電極である前記金属Ｃｒとアノード電極との間には１２０Ａの電流を流してアーク放電を発生させ、同じく表３，４に示される目標層厚のＣｒ_２Ｏ_３層を硬質被覆層の表面層として蒸着形成することにより、本発明被覆サーメット工具としての本発明表面被覆サーメット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。
【００２０】
また、比較の目的で、これらサーメット基体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）および金属Ｃｒを装着し、前記金属Ｃｒはボンバード洗浄用にも使用し、まず、装置内を排気して０．５Ｐａの真空に保持しながら、ヒーターで装置内を７００℃に加熱した後、前記サーメット基体に−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、もってサーメット基体表面を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３Ｐａの反応雰囲気とすると共に、回転テーブル上で自転しながら回転する前記サーメット基体に−１００Ｖの直流バイアス電圧を印加し、かつ前記Ａｌ−Ｔｉ合金のカソード電極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、もって前記サーメット基体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層を硬質被覆層の下側層として蒸着形成し、さらに前記（Ａｌ，Ｔｉ）Ｎ層からなる下側層を蒸着形成したもののうちの半数について、３Ｐａの窒素雰囲気を維持した状態で、前記金属Ｃｒとアノード電極との間に１２０Ａの電流を流してアーク放電を発生させ、同じく表５に示される目標層厚のＣｒＮ層を硬質被覆層の中間層として蒸着形成し、ついで全数について、装置内に導入する反応ガスを酸素ガスに切り替えて、装置内を１．５Ｐａの酸素雰囲気とすると共に、前記サーメット基体に−１５０Ｖのパルスバイアス電圧を印加し、かつカソード電極である前記金属Ｃｒとアノード電極との間に１２０Ａの電流を流してアーク放電を発生させ、同じく表５に示される目標層厚のＣｒ_２Ｏ_３層を硬質被覆層の表面層として蒸着形成することにより、比較被覆サーメット工具としての比較表面被覆サーメット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。
【００２１】
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・Ｓ５０Ｃの丸棒、
切削速度：３５０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
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：２８０ｍ／ｍｉｎ．、
切り込み：２ｍｍ、
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切削加工試験、
被削材：ＪＩＳ・ＦＣ２５０の丸棒、
切削速度：４００ｍ／ｍｉｎ．、
切り込み：２ｍｍ、
送り：０．３ｍｍ／ｒｅｖ．、
切削時間：１０分、
の条件での鋳鉄の乾式連続高速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。
【００２２】
【表１】

【００２３】
【表２】

【００２４】
【表３】

【００２５】
【表４】

【００２６】
【表５】

【００２７】
【表６】

【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ＶＣ粉末、同１．０μｍの（Ｔｉ，Ｗ）Ｃ粉末、および同１．８μｍのＣｏ粉末を用意し、これら原料粉末をそれぞれ表７に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、１００ＭＰａの圧力で所定形状の各種の圧粉体にプレス成形し、これらの圧粉体を、６Ｐａの真空雰囲気中、７℃／分の昇温速度で１３７０〜１４７０℃の範囲内の所定の温度に昇温し、この温度に１時間保持後、炉冷の条件で焼結して、直径が８ｍｍ、１３ｍｍ、および２６ｍｍの３種のサーメット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基超硬合金製のサーメット基体（エンドミル）Ｃ−１〜Ｃ−８をそれぞれ製造した。
【００２９】
ついで、これらのサーメット基体（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８に示される目標組成のＡｌ最高含有点とＡｌ最低含有点とが交互に同じく表８に示される目標間隔で繰り返し存在し、かつ前記Ａｌ最低含有点から前記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８に示される目標層厚の（Ａｌ，Ｔｉ）Ｎ層からなる下側層と、同じく表８に示される目標層厚のＣｒＮ層からなる中間層およびＣｒ_２Ｏ_３層からなる表面層で構成された硬質被覆層を蒸着形成することにより、本発明被覆サーメット工具としての本発明表面被覆サーメット製エンドミル（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、上記のサーメット基体（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におけると同一の条件で、表９に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ）Ｎ層からなる下側層を蒸着形成し、さらに前記（Ａｌ，Ｔｉ）Ｎ層からなる下側層を蒸着形成したもののうちの半数について、同じく表９に示される目標層厚のＣｒＮ層を中間層として蒸着形成し、さらに全数について同じく表９に示される目標層厚のＣｒ_２Ｏ_３層を硬質被覆層の表面層として蒸着形成することにより、比較被覆サーメット工具としての比較表面被覆サーメット製エンドミル（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：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＣＭ４４０の板材、
切削速度：２００ｍ／ｍｉｎ．、
溝深さ（切り込み）：３ｍｍ、
テーブル送り：８５０ｍｍ／分、
の条件での合金鋼の乾式高速溝切削加工試験、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：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＫＤ６１（硬さ：５２ＨＲＣ）の板材、
切削速度：５０ｍ／ｍｉｎ．、
溝深さ（切り込み）：０．５ｍｍ、
テーブル送り：１８０ｍｍ／分、
の条件での工具鋼の乾式高速溝切削加工試験、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：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ５０Ｃの板材、
切削速度：５０ｍ／ｍｉｎ．、
溝深さ（切り込み）：８ｍｍ、
テーブル送り：３６０ｍｍ／分、
の条件での炭素鋼の乾式高速溝切削加工試験をそれぞれ行い、いずれの溝切削加工試験でも切刃部の外周刃の逃げ面摩耗幅が使用寿命の目安とされる０．１ｍｍに至るまでの切削溝長を測定した。この測定結果を表８、９にそれぞれ示した。
【００３２】
【表７】

【００３３】
【表８】

【００３４】
【表９】

【００３５】
（実施例３）
上記の実施例２で製造した直径が８ｍｍ（サーメット基体Ｃ−１〜Ｃ−３形成用）、１３ｍｍ（サーメット基体Ｃ−４〜Ｃ−６形成用）、および２６ｍｍ（サーメット基体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（サーメット基体Ｄ−１〜Ｄ−３）、８ｍｍ×２２ｍｍ（サーメット基体Ｄ−４〜Ｄ−６）、および１６ｍｍ×４５ｍｍ（サーメット基体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基超硬合金製のサーメット基体（ドリル）Ｄ−１〜Ｄ−８をそれぞれ製造した。
【００３６】
ついで、これらのサーメット基体（ドリル）Ｄ−１〜Ｄ−８の切刃に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図１に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、層厚方向に沿って表１０に示される目標組成のＡｌ最高含有点とＡｌ最低含有点とが交互に同じく表１０に示される目標間隔で繰り返し存在し、かつ前記Ａｌ最低含有点から前記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１０に示される目標層厚の（Ａｌ，Ｔｉ）Ｎ層からなる下側層と、同じく表１０に示される目標層厚のＣｒＮ層からなる中間層およびＣｒ_２Ｏ_３層からなる上側層で構成された硬質被覆層を蒸着形成することにより、本発明被覆サーメット工具としての本発明表面被覆サーメット製ドリル（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、上記のサーメット基体（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層を硬質被覆層の下側層として蒸着形成し、さらに前記（Ａｌ，Ｔｉ）Ｎ層を蒸着形成したもののうちの半数について、同じく表１１に示される目標層厚のＣｒＮ層を硬質被覆層の下側層として蒸着形成し、さらに全数について同じく表１１に示される目標層厚のＣｒ_２Ｏ_３層を硬質被覆層の表面層として蒸着形成することにより、比較被覆サーメット工具としての比較表面被覆サーメット製ドリル（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：平面寸法：１００ｍｍ×２５０、厚さ：５０ｍｍのＪＩＳ・ＳＫＤ６１（硬さ：５２ＨＲＣ）の板材、
切削速度：８０ｍ／ｍｉｎ．、
送り：０．０９ｍｍ／ｒｅｖ、
穴深さ：８ｍｍ、
の条件での工具鋼の湿式高速穴あけ切削加工試験、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：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ５５Ｃの板材、
切削速度：１２０ｍ／ｍｉｎ．、
送り：０．２３ｍｍ／ｒｅｖ、
穴深さ：１６ｍｍ、
の条件での炭素鋼の湿式高速穴あけ切削加工試験、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：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＣＭ４４０の板材、
切削速度：４０ｍ／ｍｉｎ．、
送り：０．２７ｍｍ／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、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１０、１１にそれぞれ示した。
【００３９】
【表１０】

【００４０】
【表１１】

【００４１】
この結果得られた本発明被覆サーメット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の硬質被覆層を構成する下側層におけるＡｌ最低含有点とＡｌ最高含有点の組成、並びに比較被覆サーメット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の硬質被覆層の下側層について、厚さ方向に沿ってＡｌおよびＴｉの含有量をオージェ分光分析装置を用いて測定したところ、前記本発明被覆サーメット工具の硬質被覆層では、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、一方前記比較被覆サーメット工具の硬質被覆層を構成する（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。
また、上記の硬質被覆層の表面層、中間層、および下側層の平均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値を示した。
【００４２】
【発明の効果】
表３〜１１に示される結果から、硬質被覆層が（Ａｌ，Ｔｉ）Ｎ層の下側層とＣｒＮ層の中間層、およびＣｒ_２Ｏ_３層の表面層で構成され、前記下側層が層厚方向に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本発明被覆サーメット工具は、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、前記硬質被覆層が前記下側層による高温強度と高温硬さおよび耐熱性向上に伴なうすぐれた耐熱塑性変形性、さらに前記表面層によるすぐれた高温硬さおよび耐熱性を具備し、かつ前記下側層と表面層の間には中間層であるＣｒＮ層によって著しく強固な層間密着性が確保されることと相俟って、高発熱および高負荷を伴なう高速切削でもすぐれた耐摩耗性を長期に亘って発揮するのに対して、硬質被覆層の下側層が層厚方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ）Ｎ層で構成された比較被覆サーメット工具においては、高速切削では前記下側層の高温硬さおよび耐熱性不足が原因で熱塑性変形を起こし、この結果中間層であるＣｒＮ層が存在しない場合には前記（Ａｌ，Ｔｉ）Ｎ層の下側層とＣｒ_２Ｏ_３層の表面層の間で剥離が発生し、また密着性のすぐれたＣｒＮ層が介在しても、層間剥離の発生はないが、摩耗を促進する偏摩耗形態をとるようになり、いずれも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、この発明の被覆サーメット工具は、特に各種の鋼や鋳鉄などの通常の切削条件では勿論のこと、切削加工を高速条件で行なった場合にもすぐれた耐摩耗性を長期に亘って発揮するものであるから、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】被覆サーメット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】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
This invention has a high temperature hardness and heat resistance with excellent hard coating layer, and also excellent interlaminar adhesion, and therefore, high-speed cutting that is accompanied by high heat generation such as various types of steel and cast iron, and is heavy. Thus, the present invention relates to a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool) that exhibits excellent wear resistance over a long period of time.
[0002]
[Prior art]
In general, for coated cermet tools, throwaway inserts that are detachably attached to the tip of a cutting tool for turning and planing of various steel and cast iron work materials, and drilling of the work material. Drills and miniature drills used in, etc., as well as solid type end mills used for chamfering, grooving, shouldering, etc. of the work material, and the solid type by attaching the throwaway tip detachably A slow-away end mill tool that performs a cutting process in the same manner as an end mill is known.
[0003]
Further, as a coated cermet tool, on the surface of a cermet base 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 layer, chromium oxide (hereinafter referred to as Cr) having an average layer thickness of 0.5 to 10 μm₂O₃Layer),
(B) The lower layer has an average layer thickness of 0.5 to 10 μm, and a composition formula: (Al_1-XTi_X) Al and Ti composite nitride satisfying N (wherein X is 0.35 to 0.60 in atomic ratio) [hereinafter referred to as (Al, Ti) N] layer;
A coated cermet tool obtained by physical vapor deposition of the hard coating layer comprising the above (a) and (b) is known, and the Cr in this coated cermet tool is known.₂O₃The layer has high-temperature hardness and heat resistance, and the (Al, Ti) N layer has high-temperature hardness and heat resistance due to the constituent component Al, and high-temperature strength due to the Ti. It is also known to exhibit excellent cutting performance when used for continuous cutting and intermittent cutting of cast iron or the like (see, for example, Patent Document 1).
[0004]
Further, the above-described coated cermet tool is used, for example, in which the above cermet substrate is loaded into an arc ion plating apparatus which is one type of physical vapor deposition apparatus schematically shown in FIG. Between the Al—Ti alloy and the anode electrode of the Al—Ti alloy and the metal Cr, each of which is installed as a cathode electrode (evaporation source) and heated to a temperature of 0 ° C. : Arc discharge is generated under the condition of 100 A, and simultaneously nitrogen gas is introduced into the apparatus as a reaction gas to obtain a reaction atmosphere of, for example, 3 Pa. On the other hand, a bias voltage of, for example, −100 V is applied to the cermet substrate. The (Al, Ti) N layer is deposited on the surface of the cermet substrate as a lower layer of the hard coating layer, and then the reaction gas is converted from nitrogen gas to acid. Instead of gas, the atmosphere in the apparatus is changed to an oxygen atmosphere of 1.5 Pa, a bias voltage of, for example, −150 V is applied to the cermet substrate, and a condition of, for example, current: 100 A is applied between the metal Cr and the anode electrode. Arc discharge is generated at the surface of the cermet substrate, Cr as the surface layer of the hard coating layer₂O₃It is also known that it is produced by depositing a layer (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP 2000-233324 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 a coated cermet tool, there is no problem when it is used under normal cutting conditions, but when it is used for high-speed cutting with high heat generation and high load, the lower side of the hard coating layer The (Al, Ti) N layer, which is a layer, easily undergoes thermoplastic deformation due to lack of high-temperature hardness and heat resistance, and when such thermoplastic deformation occurs, the (Al, Ti) N layer is a surface layer. Cr₂O₃In combination with the insufficient adhesion to the layers, it is inevitable that peeling occurs between the two layers, and 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 present inventors have developed a hard coating that constitutes the above-described conventional coated cermet tool in order to develop a coated cermet tool that exhibits excellent cutting performance over a long period of time, particularly in high-speed cutting. As a result of conducting research focusing on the layer,
(A) (a) The (Al, Ti) N layer of the hard coating layer constituting the conventional coated cermet tool formed using the arc ion plating apparatus shown in FIG. An arc ion plating apparatus having a structure having a uniform high temperature hardness, heat resistance, and high temperature strength but having a structure shown in, for example, a schematic plan view in FIG. 1A and a schematic front view in FIG. A cermet substrate mounting rotary table is provided at the center, and the Al-Ti alloy used as a cathode electrode (evaporation source) for forming the above-described conventional (Al, Ti) N layer on one side is sandwiched between the rotary tables. An arc ion plating apparatus in which a corresponding Al—Ti alloy and an Al—Ti alloy having a relatively low Ti content are arranged opposite to each other as a cathode electrode (evaporation source) on the other side is used. A plurality of cermet bases are mounted in a ring shape along the outer peripheral portion at a predetermined distance in the radial direction from the center axis of the rotary table, and the rotary table is rotated with the atmosphere in the apparatus as a nitrogen atmosphere in this state. At the same time, while rotating the cermet substrate itself for the purpose of uniforming the thickness of the hard coating layer formed by vapor deposition, arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides, When the (Al, Ti) N layer is formed on the surface of the cermet substrate, the resulting (Al, Ti) N layer has the cermet substrate arranged in a ring shape on the rotary table on the one side relative to the cermet substrate. When the cathode electrode (evaporation source) of the Al-Ti alloy having a high Ti content is closest, an Al minimum content point is formed in the layer, and the cermet substrate is When the Al-Ti alloy cathode electrode having a relatively low Ti content is closest to the other side of the metal, the highest Al content point is formed in the layer, and the rotation of the rotary table causes the layer to move in the layer thickness direction. Accordingly, the Al lowest content point and the Al highest content point appear alternately and repeatedly with a predetermined interval, and the Al and Ti content points from the Al lowest content point to the Al highest content point and from the Al highest content point to the Al lowest content point. It has a component concentration distribution structure in which the content ratio changes continuously.
[0008]
(B) In the (Al, Ti) N layer having the repeated continuous change component concentration distribution structure in (a) above, for example, the respective compositions of the cathode electrodes (evaporation sources) arranged opposite to each other are prepared, and a cermet substrate is mounted. By controlling 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, so that it has higher temperature hardness and heat resistance, while the Al content is higher. The lowest content point portion has the same composition as the conventional (Al, Ti) N layer, that is, the Al content is relatively low compared to the Al highest content point portion, and the composition has a high Ti content. The relatively high high-temperature strength is maintained, and the distance between the Al minimum content point and the Al maximum content point is extremely small. Therefore, excellent high-temperature hardness and heat resistance are maintained while maintaining high high-temperature strength as a characteristic of the entire layer. Have better thermoplastic deformation properties.
[0009]
(B) Furthermore, the (Al, Ti) N layer having the repeated continuous change component concentration distribution structure of the above (a) and (b) is deposited and formed as a lower layer with an average layer thickness of 0.5 to 10 μm. In a state where chromium nitride (hereinafter referred to as CrN) is deposited by vapor deposition with an average layer thickness of 0.1 to 5 μm as an intermediate layer, Cr as a surface layer₂O₃When the layer is formed by vapor deposition with an average layer thickness of 0.5 to 10 μm, in the hard coating layer as a result, the (Al, Ti) N layer having the repeated continuous change component concentration distribution structure as the lower layer is the conventional (Al , Ti) N has higher temperature hardness and heat resistance than the N layer. As a result, the heat plastic deformation is further improved, and the CrN layer as an intermediate layer is formed of the (Al , Ti) N layer and surface layer Cr₂O₃The coated cermet tool formed with such a hard coating layer is used for high-speed cutting such as steel and cast iron with high heat generation and high load. Demonstrating excellent wear resistance over a long period without delamination.
The research results shown in (A) and (B) above were obtained.
[0010]
  This invention was made based on the above research results,Using an arc ion plating device with a cermet substrate mounting rotary table 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 cermet bases 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 cermet bases themselves are rotated while the cathode electrodes (evaporation sources) on both sides are rotated. An arc discharge is generated between the anode electrode and the vapor deposited on the surface of the cermet substrate, and has an average layer thickness of 0.5 to 10 μm.,
  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 lower layer composed of an (Al, Ti) N layer in which 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, the arc ion plating apparatus faces the rotary table while rotating the rotary table by setting the atmosphere in the apparatus as a nitrogen atmosphere and rotating the cermet substrate itself mounted in a ring shape on the rotary table. An arc discharge is generated between the metal Cr arranged as a cathode electrode (evaporation source) and an anode electrode, and is deposited on the lower layer deposited on the surface of the cermet substrate on the rotary table. Intermediate layer comprising a CrN layer having an average layer thickness of 0.1 to 5 μm,
(C)Further, the atmosphere inside the apparatus is changed to an oxygen gas atmosphere, and the arc table is rotated while the cermet substrate itself mounted in a ring shape on the rotary table is also rotated, while facing the rotary table and the arc ions. An arc discharge is generated between the metal Cr arranged as the cathode electrode (evaporation source) of the plating apparatus and the anode electrode, and deposited on the intermediate layer deposited on the surface of the cermet substrate on the rotary table. Cr having an average layer thickness of 0.5 to 10 μm ₂ O ₃ Surface layer consisting of layers,
The present invention is characterized by a coated cermet tool which is formed by vapor-depositing a hard coating layer comprising the above (a) to (c) and exhibits excellent wear resistance in a high-speed cutting process.
[0011]
Next, in the coated cermet tool of the present invention, the reason why the configuration of the hard coating layer constituting the tool is limited as described above will be described.
(A) Composition of Al highest content point in lower 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. In addition, the Ti content is lowered, the Al content is increased, the high temperature hardness and heat resistance are relatively improved, and the excellent high temperature hardness and heat resistance that does not plastically deform even the high heat generated by high-speed cutting is achieved. In addition, it is intended to prevent delamination due to thermoplastic deformation, but when the Y value indicating the proportion of Ti is less than 0.05 in the proportion of the total amount with Al (atomic ratio, hereinafter the same), Even if the proportion of Al is relatively large, and the Al minimum content point having a relatively high high temperature strength is present adjacently, a decrease in the high temperature strength of the layer itself cannot be avoided. Chipping is likely to occur, while Ti If the Y value indicating the combination exceeds 0.30, the proportion of Al becomes relatively small, and it is possible to ensure excellent high-temperature hardness and heat resistance sufficient to suppress the occurrence of thermoplastic deformation at high speed cutting. The Y value was determined to be 0.05 to 0.30 because it was not possible.
[0012]
(B) Composition of the lowest Al content point in the lower 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 high-temperature strength cannot be secured, and in this case, the cutting edge portion On the other hand, if the occurrence of chipping is unavoidable, while the X value exceeds 0.60, the ratio of Ti to Al increases too much, resulting in insufficient high-temperature hardness and heat resistance at the Al minimum content point, and occurrence of thermoplastic deformation. Can cause It was defined as 0.35 to 0.60 the X value indicating the ratio of Ti in the Al lowest containing point.
[0013]
(C) Interval between the highest Al content point and the lowest Al content point in the lower 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, it is impossible to ensure high temperature hardness, heat resistance, and high temperature strength in the lower layer. In addition, when the distance exceeds 0.1 μm, the disadvantages of the respective points, that is, when the Al content is the highest, the high temperature strength is insufficient, and when the Al content is the minimum, the high temperature hardness and insufficient heat resistance are localized in the layer. Therefore, chipping is likely to occur in the cutting edge due to this, and delamination is likely to occur due to thermoplastic deformation. Therefore, the interval was set to 0.01 to 0.1 μm.
[0014]
(D) Average thickness of the lower layer
If the average layer thickness is less than 0.5 μm, the hard coating layer cannot be sufficiently imparted with the excellent high-temperature strength of the lower layer, and as a result, chipping tends to occur at the cutting edge, and the Since the average layer thickness exceeds 10 μm and chipping is likely to occur at the cutting edge, the average layer thickness was determined to be 0.5 to 10 μm.
[0015]
(D) Average layer thickness of the intermediate layer
The CrN layer of the intermediate layer includes the (Al, Ti) N layer of the lower layer and the Cr of the surface layer as described above.₂O₃The layer is firmly adhered to any of the layers, significantly improving the adhesion between these two layers, and prevents the occurrence of delamination even in high-speed cutting with high heat generation and high load. If the average layer thickness exceeds 5 μm, the CrN layer itself is relatively soft, so that the hard coating is difficult. Thermoplastic deformation occurs in the layer, and as a result, wear takes the form of uneven wear that causes wear acceleration, so the average layer thickness was determined to be 0.1 to 5 μm.
[0016]
(E) Average layer thickness of the surface layer
As described above, the hard coating layer is composed of the high temperature strength and heat resistance of the lower layer, which does not cause thermoplastic deformation, and Cr, which is a surface layer.₂O₃The coexistence of excellent high-temperature hardness and heat resistance of the layer makes it possible to exhibit excellent wear resistance in high-speed cutting with high heat generation and high load, but the average layer thickness is 0.5 μm. If it is less than 1, the above-mentioned properties of the hard coating layer cannot be fully exhibited. On the other hand, if the average layer thickness exceeds 10 μm, chipping tends to occur at the cutting edge portion. It was determined to be 5 to 10 μm.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated cermet 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, VC 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 Cermet substrates A-1 to A-10 made of a WC-base cemented carbide having a standard / CNMG120408 chip shape were formed.
[0018]
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 honing process of 0.03 was performed to form cermet bases B-1 to B-6 made of TiCN cermet having a chip shape of ISO standard / CNMG120408.
[0019]
Next, each of the cermet substrates A-1 to A-10 and B-1 to B-6 is ultrasonically cleaned in acetone and dried, and then in the arc ion plating apparatus shown in FIG. Attached along the outer circumference at a predetermined distance in the radial direction from the central axis on the rotary table, various component compositions are used as the cathode electrode (evaporation source) on one side to form the lower layer of the hard coating layer. Al-Ti alloy for forming the highest Al content point, and Al-Ti alloy for forming the lowest Al content point having various components as the cathode electrode (evaporation source) on the other side, facing each other across the rotary table Furthermore, an upper layer and intermediate layer forming metal Cr is also mounted as a cathode electrode, and the metal Cr is also used for bombard cleaning. First, the inside of the apparatus is evacuated and maintained at a vacuum of 0.5 Pa, After heating the inside of the apparatus to 700 ° C. with a heater, a DC bias voltage of −1000 V is applied to the cermet substrate that rotates while rotating on the rotary table, and 100 A is applied between the metal Cr and anode electrode of the cathode electrode. Current is caused to flow to cause arc discharge, and the surface of the cermet substrate is cleaned with Cr bombardment, and 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 −100 V is applied to the rotating cermet substrate, and between 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 is applied to the electrode to generate an arc discharge, so that the surface of the cermet substrate is aligned along the layer thickness direction. Thus, the highest Al content point and the lowest Al content point of the target composition shown in Tables 3 and 4 are alternately repeated at the target interval shown in Tables 3 and 4, and the highest Al content from the lowest Al content point. The content concentration distribution structure in which the content ratio of Al and Ti continuously changes from the Al content point to the Al minimum content point, and the target layer thickness (Al , Ti) N layer is vapor-deposited as the lower layer of the hard coating layer, and then the Al-Ti alloy for forming the highest Al content point and the Al-Ti alloy for forming the lowest Al content point are connected to the cathode electrode and the anode electrode. The arc discharge was stopped, and a current of 120 A was passed between the metal Cr and the anode electrode in a state where a nitrogen atmosphere of 3 Pa was maintained to generate arc discharge. Thick CrN Is vapor-deposited as an intermediate layer of the hard coating layer, the reaction gas introduced into the apparatus is switched to oxygen gas, the inside of the apparatus is set to an oxygen atmosphere of 1.5 Pa, and the voltage applied to the cermet substrate is −150 V. A current of 120 A is caused to flow between the metal Cr as the cathode electrode and the anode electrode to generate arc discharge, and Cr having the target layer thickness shown in Tables 3 and 4 is used.₂O₃By forming the layer as a surface layer of the hard coating layer, throwaway tips made of the surface coated cermet of the present invention (hereinafter referred to as the present coated chip) 1 to 16 as the coated cermet tool of the present invention were produced.
[0020]
For the purpose of comparison, these cermet substrates A-1 to A-10 and B-1 to B-6 were ultrasonically cleaned in acetone and dried, respectively, and the arc ion plating shown in FIG. The apparatus was charged with an Al-Ti alloy (only one side) and metal Cr having various component compositions as a cathode electrode (evaporation source), and the metal Cr was also used for bombard cleaning. While the inside of the apparatus was evacuated and maintained at a vacuum of 0.5 Pa, the inside of the apparatus was heated to 700 ° C. with a heater, and then a −1000 V DC bias voltage was applied to the cermet substrate, and the metal Cr of the cathode electrode and An arc discharge is generated by flowing a current of 100 A between the anode electrode and the cermet substrate surface is cleaned by Cr bombardment, and then nitrogen gas is introduced into the apparatus as a reaction gas. A -100 V direct-current bias voltage is applied to the cermet substrate that rotates while rotating on a rotary table, and a 100 A current is applied between the cathode electrode and the anode electrode of the Al-Ti alloy. Current is caused to flow and arc discharge is generated, so that each surface of the cermet substrates A-1 to A-10 and B-1 to B-6 has the target composition and target layer thickness shown in Table 5. And an (Al, Ti) N layer having substantially no composition change along the layer thickness direction is deposited as a lower layer of the hard coating layer, and a lower layer made of the (Al, Ti) N layer is further formed. About half of the vapor-deposited materials, while maintaining a nitrogen atmosphere of 3 Pa, a current of 120 A was passed between the metal Cr and the anode electrode to generate an arc discharge. The target layer thickness of CrN layer is vapor-deposited as an intermediate layer of the hard coating layer, and then the reaction gas introduced into the apparatus is switched to oxygen gas for the total number, and the inside of the apparatus is brought to an oxygen atmosphere of 1.5 Pa, A pulse bias voltage of −150 V is applied to the cermet substrate, and a current of 120 A is applied between the metal Cr as the cathode electrode and the anode electrode to generate an arc discharge. Cr₂O₃By forming the layers as vapor-deposited surface layers, comparative surface-coated cermet throwaway tips (hereinafter referred to as comparative coated chips) 1 to 16 as comparative coated cermet tools were produced.
[0021]
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 / S50C round bar,
Cutting speed: 350 m / min. ,
Incision: 1.5mm,
Feed: 0.2 mm / rev. ,
Cutting time: 10 minutes,
Dry continuous high speed cutting test of carbon steel under the conditions of
Work material: JIS / SNCM439 round bars with four equal grooves in the longitudinal direction,
Cutting speed: 280 m / min. ,
Cutting depth: 2mm,
Feed: 0.25 mm / rev. ,
Cutting time: 5 minutes
Dry interrupted high-speed cutting test of alloy steel under the conditions of
Work material: JIS / FC250 round bar,
Cutting speed: 400 m / min. ,
Cutting depth: 2mm,
Feed: 0.3 mm / rev. ,
Cutting time: 10 minutes,
The dry continuous high-speed cutting test of cast iron was performed under the conditions described above, and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 6.
[0022]
[Table 1]

[0023]
[Table 2]

[0024]
[Table 3]

[0025]
[Table 4]

[0026]
[Table 5]

[0027]
[Table 6]

[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_ThreeC₂Prepare powder, VC powder of 1.5 μm, (Ti, W) C powder of 1.0 μm, and Co powder of 1.8 μm, and blend these raw material powders into the composition shown in Table 7, respectively. Further, wax was added and mixed in a ball mill for 24 hours in acetone, dried under reduced pressure, and then pressed into various green compacts having a predetermined shape at a pressure of 100 MPa. These green compacts were placed in a 6 Pa vacuum atmosphere. The temperature is increased to a predetermined temperature within a range of 1370 to 1470 ° C. at a temperature increase rate of 7 ° C./min, held at this temperature for 1 hour, sintered under furnace cooling conditions, and having a diameter of 8 mm, 13 mm, and The three types of round bar sintered bodies for forming cermet substrates of 26 mm were formed, and further, from the above three types of round bar sintered bodies, by grinding, in combinations shown in Table 7, the diameter of the cutting edge portion × Each length is 6mm x 13mm, 10mm x 22mm And dimensions of 20 mm × 45 mm, as well as any twist angle of 30 degrees 4 flute square shape having a WC-based cemented carbide cermet substrate (end mill) C-1 through C-8 were prepared, respectively.
[0029]
Next, the surfaces of these cermet 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 8 along the layer thickness direction alternately and repeatedly exist at the target interval shown in Table 8, 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, which are also shown in Table 8. A lower layer composed of an (Al, Ti) N layer having a target layer thickness, an intermediate layer composed of a CrN layer having a target layer thickness also shown in Table 8, and Cr₂O₃By forming a hard coating layer composed of a surface layer composed of layers by vapor deposition, end mills made of the surface coated cermet of the present invention (hereinafter referred to as the present coated end mill) 1 to 8 as the coated cermet tool of the present invention were produced, respectively. .
[0030]
For the purpose of comparison, the surfaces of the cermet substrates (end mills) C-1 to C-8 are ultrasonically cleaned in acetone and dried, and then mounted on the arc ion plating apparatus shown in FIG. (Al, Ti) N layer having the target composition and target layer thickness shown in Table 9 and substantially unchanged in the layer thickness direction under the same conditions as in Example 1 above. The lower layer composed of the above-mentioned (Al, Ti) N layer, and the lower layer composed of the (Al, Ti) N layer is vapor-deposited, with the CrN layer having the target layer thickness shown in Table 9 as the intermediate layer. Vapor-deposited, and Cr with the target layer thickness shown in Table 9 for the total number₂O₃By forming the layer as a surface layer of the hard coating layer, comparative surface-coated cermet end mills (hereinafter referred to as comparative coated end mills) 1 to 8 as comparative coated cermet 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 dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SCM440 plate material,
Cutting speed: 200 m / min. ,
Groove depth (cut): 3 mm,
Table feed: 850 mm / min,
For the dry high-speed grooving test of the alloy steel under the conditions of the present invention, the coated end mills 4 to 6 and the comparative coated end mills 4 to 6 of the present invention,
Work material: Plane size: 100 mm × 250 mm, thickness: 50 mm JIS / SKD61 (hardness: 52 HRC) plate material,
Cutting speed: 50 m / min. ,
Groove depth (cut): 0.5 mm,
Table feed: 180mm / min,
With respect to the dry high-speed grooving test of the tool steel under the conditions of the present invention, the coated end mills 7 and 8 and the comparative coated end mills 7 and 8 of the present invention,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / S50C plate material,
Cutting speed: 50 m / min. ,
Groove depth (cut): 8 mm,
Table feed: 360 mm / min,
Carbon steel dry high-speed grooving test under the above conditions was conducted, and in each grooving test, the flank wear width of the outer peripheral edge of the cutting edge reached 0.1 mm, which is a guide for the service life. The cutting groove length was measured. The measurement results are shown in Tables 8 and 9, respectively.
[0032]
[Table 7]

[0033]
[Table 8]

[0034]
[Table 9]

[0035]
(Example 3)
The diameters produced in Example 2 above were 8 mm (for forming cermet substrates C-1 to C-3), 13 mm (for forming cermet substrates C-4 to C-6), and 26 mm (cermet substrates C-7 and C). -8 for forming), and from these three types of round bar sintered bodies, the diameter x length of the groove forming portion is 4 mm x 13 mm (cermet substrate D) by grinding. −1 to D-3), 8 mm × 22 mm (cermet bases D-4 to D-6), and 16 mm × 45 mm (cermet bases D-7 and D-8), and 2 with a twist angle of 30 degrees. Cermet substrates (drills) D-1 to D-8 made of a WC-base cemented carbide having a single blade shape were produced.
[0036]
Next, the cutting blades of these cermet substrates (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone, and dried to the arc ion plating apparatus shown in FIG. In the same conditions as in Example 1 above, the highest Al content point and the lowest Al content point of the target composition shown in Table 10 along the layer thickness direction alternately at the target interval shown in Table 10 It has a component concentration distribution structure that repeatedly exists and the content ratio of Al and Ti continuously changes from the Al lowest content point to the Al highest content point, from the Al highest content point to the Al lowest content point, And a lower layer made of an (Al, Ti) N layer having a target layer thickness also shown in Table 10, an intermediate layer made of a CrN layer having a target layer thickness also shown in Table 10, and Cr₂O₃The surface-covered cermet drills according to the present invention (hereinafter referred to as the present invention-coated drills) 1 to 8 as the present invention-coated cermet tools were produced by vapor-depositing a hard coating layer composed of an upper layer composed of layers. .
[0037]
For the purpose of comparison, honing is performed on the surfaces of the cermet substrates (drills) D-1 to D-8, ultrasonic cleaning is performed in acetone, and the arc ions shown in FIG. In the plating apparatus, under the same conditions as in Example 1, the target composition and the target layer thickness shown in Table 11 are obtained, and there is substantially no change in composition along the layer thickness direction (Al, Ti) N layer is vapor-deposited as the lower layer of the hard coating layer, and about half of the (Al, Ti) N layer is vapor-deposited, the CrN layer having the target layer thickness shown in Table 11 is hard. It is formed by vapor deposition as the lower layer of the coating layer, and the Cr of the target layer thickness shown in Table 11 is also shown for all the numbers.₂O₃By forming the layer as a surface layer of the hard coating layer, comparative surface-coated cermet drills (hereinafter referred to as comparative coated drills) 1 to 8 as comparative coated cermet 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 dimension: 100 mm × 250, thickness: 50 mm JIS SKD61 (hardness: 52 HRC) plate material,
Cutting speed: 80 m / min. ,
Feed: 0.09mm / rev,
Hole depth: 8mm,
About the wet high speed drilling cutting test of the tool steel under the conditions of the present invention, the present invention coated drills 4-6 and the comparative coated drills 4-6,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / S55C plate material,
Cutting speed: 120 m / min. ,
Feed: 0.23mm / rev,
Hole depth: 16mm,
For the wet high speed drilling test of carbon steel under the conditions of the present invention, the present invention coated drills 7 and 8 and the comparative coated drills 7 and 8,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SCM440 plate material,
Cutting speed: 40 m / min. ,
Feed: 0.27mm / rev,
Hole depth: 32mm,
Wet high-speed drilling test of alloy steel under the above conditions, each wet high-speed drilling cutting test (using water-soluble cutting oil) until the flank wear width of the cutting edge surface reaches 0.3mm The number of holes drilled was measured. The measurement results are shown in Tables 10 and 11, respectively.
[0039]
[Table 10]

[0040]
[Table 11]

[0041]
The lowest Al content in the lower layer constituting the hard coating layer of the present coated tip 1-16, the present coated end mill 1-8, and the present coated drill 1-8 as the present coated cermet tool obtained as a result of this. The composition of the point and the highest Al content point, and the lower layer of the hard coating layer of the comparative coated tips 1 to 16, the comparative coated end mills 1 to 8, and the comparative coated drills 1 to 8 as the comparative coated cermet tool The content of Al and Ti was measured using an Auger spectroscopic analyzer along the line, and in the hard coating layer of the coated cermet tool of the present invention, the Al minimum content point and the Al maximum content point were each substantially equal to the target value. To the Al highest content point from the Al lowest content point, and from the Al highest content point to the Al lowest content point. It is confirmed that each of the Ti and Ti content ratios has a component concentration distribution structure that continuously changes, while the (Al, Ti) N layer constituting the hard coating layer of the comparative coated cermet tool is along the thickness direction. Although no composition change was observed, the composition was substantially the same as the target composition.
Further, when the average layer thicknesses of the surface layer, the intermediate layer, and the lower layer of the hard coating layer were measured with a scanning electron microscope, all showed substantially the same value as the target layer thickness.
[0042]
【The invention's effect】
From the results shown in Tables 3 to 11, the hard coating layer is an intermediate layer between the lower layer of the (Al, Ti) N layer and the CrN layer, and Cr.₂O₃It is composed of a surface layer of the layer, and in the lower layer, the highest Al content point and the lowest Al content point are alternately present at predetermined intervals in the layer thickness direction, and the highest Al content from the lowest Al content point The present coated cermet tool having a component concentration distribution structure in which the content ratio of Al and Ti continuously changes from the highest Al content point to the lowest Al content point is high in cutting of steel and cast iron. Even if it is carried out at high speed with heat generation, the hard coating layer has excellent high temperature strength and high temperature hardness due to the lower layer and excellent heat plastic deformation accompanying improvement in heat resistance, and excellent high temperature hardness due to the surface layer. Combined with the fact that the intermediate layer CrN layer ensures extremely strong interlayer adhesion between the lower layer and the surface layer, it has high heat generation and high load. Now with high speed cutting A comparative example in which the lower layer of the hard coating layer is composed of an (Al, Ti) N layer that has substantially no composition change along the layer thickness direction while exhibiting excellent wear resistance over a long period of time. In a coated cermet tool, high-speed cutting causes thermoplastic deformation due to insufficient high-temperature hardness and heat resistance of the lower layer. As a result, when there is no CrN layer as an intermediate layer, the (Al, Ti) N Lower layer and Cr₂O₃Even if a CrN layer with excellent adhesion is interposed between the surface layers of the layers, there is no delamination, but it takes an uneven wear form that promotes wear. It is clear that the service life is reached in a short time.
As described above, the coated cermet tool according to the present invention has excellent wear resistance over a long period of time even when cutting is performed under high-speed conditions as well as various cutting conditions such as various steels and cast irons. Therefore, it is possible to satisfactorily meet the demands for higher performance of the cutting device, labor saving and energy saving of the cutting processing, and cost reduction.
[Brief description of the drawings]
FIG. 1 shows an arc ion plating apparatus used for forming a hard coating layer constituting a coated cermet 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 cermet substrate made of either a tungsten carbide base cemented carbide and a titanium carbonitride cermet or both 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 cermet bases 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 cermet bases themselves are rotated while the cathode electrodes (evaporation sources) on both sides are rotated. by generating arc discharge between the anode electrode, formed by deposition on the surface of the cermet substrate has an average layer thickness of 0.5~10μm
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 lower layer composed of a composite nitride layer of Al and Ti, wherein the distance between the adjacent Al minimum content point and the Al maximum content point adjacent to each other is 0.01 to 0.1 μm,
(B) The rotary table is rotated by setting the atmosphere in the apparatus to be a nitrogen atmosphere, and the arc ion facing the rotary table while rotating the cermet substrate itself mounted in a ring shape on the rotary table. An arc discharge is generated between the metal Cr arranged as the cathode electrode (evaporation source) of the plating apparatus and the anode electrode, and deposited on the lower layer deposited on the surface of the cermet substrate on the rotary table. An intermediate layer comprising a chromium nitride layer having an average layer thickness of 0.1 to 5 μm ,
(C) Further, the atmosphere inside the apparatus is an oxygen gas atmosphere, and the rotary table is similarly rotated, and the cermet substrate itself mounted in a ring shape on the rotary table is rotated while facing the rotary table, An arc discharge is generated between the metal Cr arranged as a cathode electrode (evaporation source) and an anode electrode of the arc ion plating apparatus, and is superimposed on the intermediate layer formed by vapor deposition on the surface of the cermet substrate on the rotary table. A surface layer comprising a chromium oxide layer having an average layer thickness of 0.5 to 10 μm ,
A surface-coated cermet cutting tool that exhibits high wear resistance in high-speed cutting processing, which is formed by vapor-depositing a hard coating layer comprising the above (a) to (c).