JP4211500B2

JP4211500B2 - Surface coated cermet cutting tool with excellent wear resistance due to high hard cutting layer in high speed cutting

Info

Publication number: JP4211500B2
Application number: JP2003165895A
Authority: JP
Inventors: 孝小山; 夏樹一宮; 一樹泉
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2003-06-11
Filing date: 2003-06-11
Publication date: 2009-01-21
Anticipated expiration: 2023-06-11
Also published as: JP2005001043A

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と耐熱性を有し、したがって特にステンレス鋼や高マンガン鋼、さらに軟鋼などの難削材の高速切削加工でも、一段と高い熱発生を伴い、かつ高負荷がかかるにもかかわらず、硬質被覆層の熱塑性変形が著しく抑制され、この結果切刃部の摩耗は正常摩耗形態をとるようになることから、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）上側層として、０．５〜５μｍの平均層厚を有し、かつ組成式：（Ｔｉ_1- _ＺＳｉ_Ｚ）Ｎ（ただし、原子比で、Ｚは０．１０〜０．５０を示す）を満足するＴｉとＳｉの複合窒化物［以下、（Ｔｉ，Ｓｉ）Ｎで示す］層、
（ｂ）下側層として、０．８〜８μｍ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の硬質被覆層においては、前記（Ｔｉ，Ｓｉ）Ｎ層が構成成分であるＳｉによって高温硬さと耐熱性、さらにＴｉによって高温強度、さらに前記（Ａｌ，Ｔｉ）Ｎ層が、同じく構成成分である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を熱発生の高い高速切削条件で用いた場合にもすぐれた耐対摩耗性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）として並列設置された、所定組成を有するＡｌ−Ｔｉ合金とＴｉ−Ｓｉ合金のうちの前記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、３Ｐａの窒素雰囲気を維持した状態で、前記Ｔｉ−Ｓｉ合金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、（Ｔｉ，Ｓｉ）Ｎ層を硬質被覆層の上側層として蒸着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２０００−３３４６０７
【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、被削材の材質にできるだけ制約されない汎用性のある切削工具の開発が望まれているが、上記の従来被覆サーメット工具においては、これを通常の合金鋼や炭素鋼、さらに鋳鉄などの被削材の高速切削に用いた場合には問題はないが、これを一段と高い発熱を伴ない、かつ高い負荷のかかるステンレス鋼や高マンガン鋼、さらに軟鋼などの難削材の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、このように硬質被覆層が熱塑性変形を起こすと、摩耗促進の原因となる偏摩耗形態をとるようになり、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、特にステンレス鋼や高マンガン鋼、さらに軟鋼などの難削材の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有するようになり、この結果耐熱塑性変形性の一段の向上が図られるようになること。
【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０．８〜８μｍの平均層厚で下側層として蒸着形成し、これに重ねて上側層としての（Ｔｉ，Ｓｉ）Ｎ層を０．５〜５μｍ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、一段と高い発熱を伴い、かつ高負荷のかかるステンレス鋼や高マンガン鋼などの難削材の高速切削加工に用いた場合にも、前記硬質被覆層に摩耗促進の原因となる偏摩耗の発生が防止され、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、サーメット基体の表面に、装置中央部に前記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）下側層として、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、
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であり、平均層厚が０．８〜８μｍである（Ａｌ，Ｔｉ）Ｎ層、
（ｂ）上側層として、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Ｔｉ−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り、かつ、
組成式：（Ｔｉ_1- _ＺＳｉ_Ｚ）Ｎ（ただし、原子比で、Ｚは０．１０〜０．５０を示す）、
を満足し、平均層厚が０．５〜５μｍである（Ｔｉ，Ｓｉ）Ｎ層、
以上（ａ）および（ｂ）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、難削材の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偏摩耗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、難削材の高速切削で熱塑性変形の発生を抑制するに足る十分な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、この結果下側層に一段とすぐれた高温硬さと耐熱性、さらに高温強度を確保することができなくなり、またその間隔が０．１μmを越えるとそれぞれの点がもつ欠点、すなわちＡｌ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偏摩耗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０．８μｍ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８μｍ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０．８〜８μｍと定めた。
【００１５】
（ｅ）上側層の組成
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すぐれた高温硬さと耐熱性、さらに上側層である（Ｔｉ，Ｓｉ）Ｎ層のもつＳｉによるすぐれた高温硬さと耐熱性、およびＴｉによる高温強度の共存によって、高発熱および高負荷を伴なう難削材の高速切削で、摩耗促進の原因となる熱塑性変形の発生なく、すぐれた耐摩耗性を長期に亘って発揮するようになるものであるが、Ｓｉの割合を示すＺ値がＴｉとの合量に占める割合で０．１０未満では、所望のすぐれた高温硬さと耐熱性を確保することができず、この結果硬質被覆層に熱塑性変形が発生し易くなり、一方Ｓｉの割合を示すＺ値が同０．５０を越えると、相対的にＴｉの割合が少なくなり過ぎて、高温強度が低下し、切刃部にチッピングが発生し易くなることから、Ｚ値を０．１０〜０．５０と定めた。
【００１６】
（ｆ）上側層の平均層厚
その平均層厚が０．５μｍ未満では、上側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。
【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種々の成分組成をもった上側層形成用Ｔｉ−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、もってサーメット基体表面を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Ｔｉ−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（Ｔｉ，Ｓｉ）Ｎ層を硬質被覆層の上側層として蒸着することにより、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）を装着し、さらに同じくカソード電極として種々の成分組成をもった上側層形成用Ｔｉ−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、もってサーメット基体表面を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、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５，６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層を硬質被覆層の下側層として蒸着形成し、さらに３Ｐａの窒素雰囲気を維持した状態で、前記Ｔｉ−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５，６に示される目標組成および目標層厚の（Ｔｉ，Ｓｉ）Ｎ層を硬質被覆層の上側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・Ｓ２０Ｃの丸棒、
切削速度：２８０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．２２ｍｍ／ｒｅｖ．、
切削時間：１０分、
の条件での軟鋼の乾式連続高速切削加工試験、
被削材：ＪＩＳ・ＳＵＳ３０４の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３００ｍ／ｍｉｎ．、
切り込み：１．７ｍｍ、
送り：０．１９ｍｍ／ｒｅｖ．、
切削時間：１０分、
の条件でのステンレス鋼の乾式断続高速切削加工試験、
被削材：ＪＩＳ・ＳＣＭｎＨ１の丸棒、
切削速度：２８０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．２４ｍｍ／ｒｅｖ．、
切削時間：１２分、
の条件での高マンガン鋼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７に示した。
【００２２】
【表１】

【００２３】
【表２】

【００２４】
【表３】

【００２５】
【表４】

【００２６】
【表５】

【００２７】
【表６】

【００２８】
【表７】

【００２９】
（実施例２）
原料粉末として、平均粒径：５．５μｍを有する中粗粒ＷＣ粉末、同０．８μｍの微粒ＷＣ粉末、同１．３μｍのＴａＣ粉末、同１．２μｍのＮｂＣ粉末、同１．２μｍのＺｒＣ粉末、同２．３μｍのＣｒ₃Ｃ₂粉末、同１．５μｍのＶＣ粉末、同１．０μｍの（Ｔｉ，Ｗ）Ｃ（質量比で、Ｔｉ／Ｗ＝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８に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法、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。
【００３０】
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層からなる下側層と、同じく表９に示される目標組成および目標層厚の（Ｔｉ，Ｓｉ）Ｎ層を硬質被覆層の上側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。
【００３１】
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層からなる下側層を蒸着形成し、さらに同じく表１０に示される目標組成および目標層厚の（Ｔｉ，Ｓｉ）Ｎ層を硬質被覆層の上側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。
【００３２】
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・ＳＵＳ３１６の板材、
切削速度：１５０ｍ／ｍｉｎ．、
溝深さ（切り込み）：１．８ｍｍ、
テーブル送り：７００ｍｍ／分、
の条件でのステンレス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・ＳＣＭｎＨ２の板材、
切削速度：１３０ｍ／ｍｉｎ．、
溝深さ（切り込み）：３ｍｍ、
テーブル送り：３００ｍｍ／分、
の条件での高マンガン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・Ｓ１５Ｃの板材、
切削速度：１６０ｍ／ｍｉｎ．、
溝深さ（切り込み）：７ｍｍ、
テーブル送り：２００ｍｍ／分、
の条件での軟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９，１０にそれぞれ示した。
【００３３】
【表８】

【００３４】
【表９】

【００３５】
【表１０】

【００３６】
（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。
【００３７】
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層からなる下側層と、同じく表１１に示される目標組成および目標層厚の（Ｔｉ，Ｓｉ）Ｎ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。
【００３８】
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層を硬質被覆層の下側層として蒸着形成し、さらに同じく表１２に示される目標組成および目標層厚の（Ｔｉ，Ｓｉ）Ｎ層を硬質被覆層の上側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。
【００３９】
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・Ｓ２０Ｃの板材、
切削速度：２００ｍ／ｍｉｎ．、
送り：０．２ｍｍ／ｒｅｖ、
穴深さ：２５ｍｍ、
の条件での軟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・ＳＵＳ３０４の板材、
切削速度：１９０ｍ／ｍｉｎ．、
送り：０．２２ｍｍ／ｒｅｖ、
穴深さ：２０ｍｍ、
の条件でのステンレス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・ＳＣＭｎＨ２の板材、
切削速度：２１０ｍ／ｍｉｎ．、
送り：０．１５ｍｍ／ｒｅｖ、
穴深さ：３５ｍｍ、
の条件での高マンガン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１１，１２にそれぞれ示した。
【００４０】
【表１１】

【００４１】
【表１２】

【００４２】
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、同じく上記の硬質被覆層の上側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、さらに上記の下側層および上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。
【００４３】
【発明の効果】
表３〜１２に示される結果から、硬質被覆層の下側層を構成する（Ａｌ，Ｔｉ）Ｎ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、いずれもステンレス鋼や高マンガン鋼、さらに軟鋼の切削加工を高発熱および高負荷を伴う高速で行っても、前記硬質被覆層の前記下側層の成分濃度分布構造がもたらす一段とすぐれた高温硬さと耐熱性によって硬質被覆層自体が一段とすぐれた耐熱塑性変形性を示し、この結果偏摩耗の発生なく、摩耗が正常摩耗形態をとるようになることから、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前記硬質被覆層に熱塑性変形が発生し、この結果摩耗形態が偏摩耗形態をとり、摩耗進行が促進するようになることから、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被削材の高速切削加工は勿論のこと、被削材がステンレス鋼や高マンガン鋼、さらに軟鋼などの難削材の高速切削加工であっても、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 an excellent hard coating layer. Therefore, even with high-speed cutting of difficult-to-cut materials such as stainless steel, high manganese steel, and even mild steel, it is accompanied by higher heat generation and high heat resistance. Despite the load being applied, the thermoplastic deformation of the hard coating layer is remarkably suppressed, and as a result, the wear of the cutting edge portion takes a normal wear form, and thus exhibits excellent wear resistance over a long period of time. The present invention relates to a surface-coated cermet cutting tool (hereinafter referred to as a coated cermet tool).
[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 an upper layer, it has an average layer thickness of 0.5 to 5 μm, and a composition formula: (Ti_1- _Z Si_Z ) Ti and Si composite nitride [hereinafter referred to as (Ti, Si) N] layer satisfying N (wherein Z represents 0.10 to 0.50 in atomic ratio),
(B) The lower layer has an average layer thickness of 0.8 to 8 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 formed by physical vapor deposition of the hard coating layer comprising the above (a) and (b) is known, and in the hard coating layer of this coated cermet tool, the (Ti, Si) N layer is a constituent component. Because Si has a high temperature hardness and heat resistance, Ti further has a high temperature strength, and the (Al, Ti) N layer also has a high temperature hardness and heat resistance due to the same constituent component Al, and the Ti has a high temperature strength. It is also known that the coated cermet tool exhibits excellent wear resistance even when continuous cutting and intermittent cutting of various steels and cast iron are used under high-speed cutting conditions with high heat generation (for example, patents) Reference 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 Ti-Si alloy having a predetermined composition, which are installed in parallel as cathode electrodes (evaporation sources), respectively, while being heated to a temperature of 0C. For example, arc discharge is generated under the condition of current: 100 A, and nitrogen gas is introduced as a reaction gas into the apparatus at the same time to form a reaction atmosphere of, for example, 3 Pa, while 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 Al—Ti The arc discharge between the gold cathode electrode and the anode electrode is stopped, and an arc discharge is generated by flowing a current of 120 A between the Ti-Si alloy and the anode electrode while maintaining a nitrogen atmosphere of 3 Pa. , (Ti, Si) N layer is also known to be produced by vapor deposition as the upper layer of the hard coating layer (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP 2000-334607 A
[0006]
[Problems to be solved by the invention]
In recent years, the performance of cutting machines has been dramatically improved, while on the other hand, there are strong demands for labor saving, energy saving, and cost reduction for cutting work. Although development of a tool is desired, in the above-mentioned conventional coated cermet tool, there is no problem when it is used for high-speed cutting of work materials such as ordinary alloy steel, carbon steel, and cast iron, When this is used for high-speed cutting of difficult-to-cut materials such as stainless steel, high-manganese steel, and mild steel with higher heat generation and high load, the above (Al, Ti ) The N layer is susceptible to thermoplastic deformation due to high temperature hardness and insufficient heat resistance, and when the hard coating layer undergoes thermoplastic deformation in this way, it takes an uneven wear form that causes accelerated wear. The result in comparatively short time service life at present.
[0007]
[Means for Solving the Problems]
In view of the above, the inventors of the present invention have a coated cermet tool that exhibits excellent wear resistance over a long period of time in high-speed cutting of difficult-to-cut materials such as stainless steel, high manganese steel, and even mild steel from the above viewpoint. As a result of conducting research, focusing on the hard coating layer that constitutes the conventional coated cermet tool described above,
(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 made extremely small, so that the high-temperature hardness and heat resistance are further improved while maintaining the high-temperature strength as a characteristic of the entire layer. As a result, the heat resistance plastic deformation property can be further improved.
[0009]
(B) 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 a lower layer with an average layer thickness of 0.8 to 8 μm. When the (Ti, Si) N layer as the upper layer is formed by vapor deposition with an average layer thickness of 0.5 to 5 μm, the hard coating layer as a result of the repeated continuous change component concentration distribution structure as the lower layer is formed. Since the (Al, Ti) N layer has higher temperature hardness and heat resistance than the conventional (Al, Ti) N layer, this results in further improved heat-resistant plastic deformation. The coated cermet tool formed by forming a hard coating layer is also used for high-speed cutting of difficult-to-cut materials such as stainless steel and high manganese steel with higher heat generation and high load. The occurrence of uneven wear that causes wear It is prevented and it exhibits excellent wear resistance over a long period of time.
The research results shown in (A) and (B) above were obtained.
[0010]
  This invention was made based on the above research results, and on the surface of the cermet substrate,Using an arc ion plating apparatus provided with a rotating table for mounting the cermet substrate in the center of the apparatus,
(A) As a lower layer,The cathode electrode (evaporation source) of the arc ion plating apparatus is opposed to both sides across the rotary table, the Al-Ti alloy for forming the highest Al content point as the cathode electrode (evaporation source) on one side, the other side Al-Ti alloys for forming the lowest Al content point are respectively disposed as cathode electrodes (evaporation sources) of the above, and a plurality of the above-mentioned components are disposed along the outer peripheral portion of the table at a position spaced apart from the central axis on the rotary table by a predetermined distance in the radial direction. A cermet base is mounted in a ring shape, and in this state, the rotary table is rotated with the atmosphere inside the apparatus being a nitrogen atmosphere, and the cermet base itself is rotated, while the cathode electrodes (evaporation sources) and anode electrodes on both sides are rotated. Arc discharge is generated during,
  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),
(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 and the average layer thickness is 0.8 to 8 μm ,
(B) As an upper layer,While rotating the rotary table with the atmosphere inside the apparatus as a nitrogen atmosphere and rotating the cermet substrate itself mounted in the same ring shape on the rotary table, facing the rotary table, the arc ion plating apparatus An arc discharge is generated between the Ti-Si alloy arranged as a cathode electrode (evaporation source) and the anode electrode, and deposited on the lower layer deposited on the surface of the cermet substrate on the rotary table. And,
  Composition formula: (Ti_1- _ZSi_Z) N (however, in atomic ratio, Z represents 0.10 to 0.50),
A (Ti, Si) N layer having an average layer thickness of 0.5 to 5 μm,
The present invention is characterized by a coated cermet tool which is formed by vapor-depositing a hard coating layer comprising the above (a) and (b) 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. Low Ti content, high Al content, relatively improved high-temperature hardness and heat resistance, excellent high-temperature hardness and heat resistance that does not plastically deform even the high heat generated by high-speed cutting of difficult-to-cut materials The Y value indicating the proportion of Ti accounts for the total amount with Al (atomic ratio, the same shall apply hereinafter) of 0.05. If the ratio is less than 1, the proportion of Al is relatively large, and even if there is an adjacent Al minimum content point having a relatively high high-temperature strength, a decrease in the high-temperature strength of the layer itself cannot be avoided. Chipping is likely to occur at the cutting edge, If the Y value indicating the ratio of i exceeds 0.30, the ratio of Al becomes relatively small, and sufficient high-temperature hardness and heat resistance are sufficient to suppress the occurrence of thermoplastic deformation in high-speed cutting of difficult-to-cut materials. Therefore, the Y value was set to 0.05 to 0.30.
[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 possible to secure higher temperature hardness, heat resistance, and high temperature strength in the lower 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 uneven wear due to thermoplastic deformation is likely to occur. Therefore, the interval is set to 0.01 to 0.1 μm.
[0014]
(D) Average thickness of the lower layer
If the average layer thickness is less than 0.8 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 If the average layer thickness exceeds 8 μm, chipping is likely to occur at the cutting edge, so the average layer thickness was set to 0.8 to 8 μm.
[0015]
(E) Composition of upper layer
As described above, the hard coating layer has the high temperature strength and heat resistance of the lower layer, which does not cause thermoplastic deformation, and the excellent high temperature hardness by Si of the (Ti, Si) N layer which is the upper layer. Due to the coexistence of heat resistance and high-temperature strength due to Ti, high-speed cutting of difficult-to-cut materials with high heat generation and high load ensures excellent wear resistance for a long time without the occurrence of thermoplastic deformation that causes wear promotion. However, if the Z value indicating the proportion of Si is less than 0.10 in the total amount with Ti, the desired excellent high-temperature hardness and heat resistance cannot be ensured. As a result, thermoplastic deformation is likely to occur in the hard coating layer. On the other hand, when the Z value indicating the proportion of Si exceeds 0.50, the proportion of Ti is relatively decreased, and the high-temperature strength is reduced. Chipping is likely to occur at the cutting edge. , It was determined to 0.10 to 0.50 of Z values.
[0016]
(F) Average layer thickness of the upper layer
If the average layer thickness is less than 0.5 μm, the above-mentioned properties of the upper layer cannot be fully exhibited, while if the average layer thickness exceeds 5 μm, chipping tends to occur at the cutting edge portion. The average layer thickness was set to 0.5 to 5 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]
In addition, as raw material powder, 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 forming Ti—Si alloy and bombard cleaning metal Ti having various component compositions are also mounted as cathode electrodes, and the apparatus is first evacuated and maintained at a vacuum of 0.5 Pa. After heating the inside of the apparatus to 500 ° 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 between the metal Ti and the anode electrode of the cathode electrode A current of 100 A is applied to generate an arc discharge, thereby cleaning the surface of the cermet substrate with Ti bombardment, and then introducing nitrogen gas as a reaction gas into the apparatus to form a reaction atmosphere of 3 Pa and rotating on the rotary table. A DC bias voltage of −100 V is applied to the rotating cermet 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 is passed between them to generate an arc discharge, so that the thickness of the layer on the surface of the cermet substrate Along the direction, the Al highest content point and the Al lowest content point of the target composition shown in Tables 3 and 4 alternately and repeatedly exist at the target intervals shown in Tables 3 and 4, and from the Al lowest content point Al maximum content point, having a component concentration distribution structure in which the content ratio of Al and Ti continuously changes from the Al maximum content point to the Al minimum content point, and also having the target layer thickness shown in Tables 3 and 4 The (Al, Ti) N layer is deposited and formed 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 cathode and anode electrodes The arc discharge between the Ti-Si alloy and the anode electrode was caused to flow while the arc discharge was stopped and a nitrogen atmosphere of 3 Pa was maintained. Goal indicated A (Ti, Si) N layer having a composition and a target layer thickness is vapor-deposited as an upper layer of the hard coating layer, so that the throwaway tip made of the surface-coated cermet of the present invention (hereinafter referred to as the present coated chip) 1) to 16 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 upper layer forming Ti having various component compositions as the cathode electrode was mounted in the apparatus and mounted with Al-Ti alloys (only one side) having various component compositions as the cathode electrode (evaporation source). -Si alloy and bombard cleaning metal Ti were also mounted. First, the inside of the apparatus was heated to 500 ° C. with a heater while evacuating the inside of the apparatus and maintaining a vacuum of 0.5 Pa, and then −1000 V on the cermet substrate. A dc bias voltage was applied, and a current of 100 A was passed between the metal Ti and the anode electrode of the cathode electrode to generate an arc discharge. i-bombard cleaning, then introducing nitrogen gas as a reaction gas into the apparatus to make a reaction atmosphere of 3 Pa, applying a DC bias voltage of −100 V to the cermet substrate rotating while rotating on a rotary table, and A current of 100A is passed between the cathode electrode and the anode electrode of the Al-Ti alloy to generate an arc discharge, and thereby the respective surfaces of the cermet substrates A-1 to A-10 and B-1 to B-6 Further, an (Al, Ti) N layer having the target composition and the target layer thickness shown in Tables 5 and 6 and having substantially no composition change along the layer thickness direction is deposited as the lower layer of the hard coating layer. In a state where a nitrogen atmosphere of 3 Pa is formed, an arc discharge is generated by flowing a current of 100 A between the Ti-Si alloy and the anode electrode. (Ti, Si) N layer having a target composition and a target layer thickness is deposited as an upper layer of the hard coating layer, thereby producing a comparative surface-coated cermet throwaway tip (hereinafter referred to as a comparative coated tip) as a comparative coated cermet tool. 1) to 16 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 / S20C round bar,
Cutting speed: 280 m / min. ,
Incision: 1.5mm,
Feed: 0.22 mm / rev. ,
Cutting time: 10 minutes,
Dry continuous high-speed cutting test of mild steel under the conditions of
Work material: JIS / SUS304 lengthwise equidistant four round grooved round bars,
Cutting speed: 300 m / min. ,
Incision: 1.7 mm,
Feed: 0.19 mm / rev. ,
Cutting time: 10 minutes,
Stainless steel dry interrupted high-speed cutting test,
Work material: JIS / SCMnH1 round bar,
Cutting speed: 280 m / min. ,
Incision: 1.5mm,
Feed: 0.24 mm / rev. ,
Cutting time: 12 minutes,
The dry continuous high-speed cutting test of high-manganese steel under the above conditions 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.
[0022]
[Table 1]

[0023]
[Table 2]

[0024]
[Table 3]

[0025]
[Table 4]

[0026]
[Table 5]

[0027]
[Table 6]

[0028]
[Table 7]

[0029]
(Example 2)
As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, ZrC of 1.2 μm Powder, 2.3 μm Cr_ThreeC₂Prepared powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C (mass ratio, Ti / W = 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. The three types of cermet substrate forming round bar sintered bodies having diameters of 8 mm, 13 mm, and 26 mm were formed, and further, the above three kinds of round bar sintered bodies were ground by grinding. In the combination shown in Fig. 8, the diameter x length of the cutting edge is Cermet substrates (end mills) C-1 to C-8 made of a WC-based 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. Were manufactured respectively.
[0030]
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 9 along the layer thickness direction alternately and repeatedly exist at the target interval shown in Table 9, and It has a component concentration distribution structure in which the 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 9. The lower layer composed of the (Al, Ti) N layer having the target layer thickness and the (Ti, Si) N layer having the target composition and the target layer thickness shown in Table 9 are vapor-deposited as the upper layer of the hard coating layer. Due to this departure The present invention surface coating cermet end mill as coated cermet tool (hereinafter, the present invention refers to the coating end mill) 1-8 were prepared, respectively.
[0031]
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 10 and substantially unchanged in the layer thickness direction under the same conditions as in Example 1 above. As a comparative coated cermet tool, a lower layer made of is vapor-deposited and a (Ti, Si) N layer having the target composition and thickness shown in Table 10 is vapor-deposited as the upper layer of the hard coating layer. Comparative surface-coated cermet end mills (hereinafter referred to as comparative coated end mills) 1 to 8 were produced.
[0032]
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 size: 100 mm × 250 mm, thickness: 50 mm JIS / SUS316 plate material,
Cutting speed: 150 m / min. ,
Groove depth (cut): 1.8 mm,
Table feed: 700mm / min,
With respect to the dry high-speed grooving test of stainless 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 dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SCMnH2 plate material,
Cutting speed: 130 m / min. ,
Groove depth (cut): 3 mm,
Table feed: 300mm / min,
For high manganese steel dry high-speed grooving test under the conditions of the present invention, the coated end mills 7 and 8 and the comparative coated end mills 7 and 8
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / S15C plate,
Cutting speed: 160 m / min. ,
Groove depth (cut): 7 mm,
Table feed: 200 mm / min,
Each of the dry high-speed grooving tests of mild steel under the above conditions was performed, and in each grooving test, cutting was performed until 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 groove length was measured. The measurement results are shown in Tables 9 and 10, respectively.
[0033]
[Table 8]

[0034]
[Table 9]

[0035]
[Table 10]

[0036]
(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.
[0037]
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 11 along the layer thickness direction alternately at the target interval shown in Table 11 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, In addition, a lower layer made of an (Al, Ti) N layer having a target layer thickness shown in Table 11 and an upper layer made of an (Ti, Si) N layer having a target composition and target thickness also shown in Table 11. Configured By depositing form the quality coating layer, the present invention surface-coated cermet drill as the present invention coated cermet tool (hereinafter, the present invention refers to the coating drills) 1-8 were prepared, respectively.
[0038]
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 compositions and target layer thicknesses shown in Table 12 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 (Ti, Si) N layer having the target composition and thickness shown in Table 12 is vapor-deposited as the upper layer of the hard coating layer. Thus, comparative surface-coated cermet drills (hereinafter referred to as comparative coated drills) 1 to 8 as comparative coated cermet tools were produced, respectively.
[0039]
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 / S20C plate material,
Cutting speed: 200 m / min. ,
Feed: 0.2mm / rev,
Hole depth: 25mm,
About the wet high-speed drilling test of mild steel under the conditions of the present invention, the present coated drills 4-6 and the comparative coated drills 4-6,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 190 m / min. ,
Feed: 0.22mm / rev,
Hole depth: 20mm,
About the wet high speed drilling cutting test of stainless steel under the conditions of the present invention, the coated drills 7 and 8 and the comparative coated drills 7 and 8 of the present invention,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SCMnH2 plate material,
Cutting speed: 210 m / min. ,
Feed: 0.15mm / rev,
Hole depth: 35mm,
Wet high-speed drilling test of high manganese steel under the above conditions, each flank wear width of the cutting edge surface reaches 0.3mm in any wet high-speed drilling test (using water-soluble cutting oil) The number of drilling processes up to was measured. The measurement results are shown in Tables 11 and 12, respectively.
[0040]
[Table 11]

[0041]
[Table 12]

[0042]
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.
Similarly, when the composition of the upper layer of the hard coating layer was measured, it showed substantially the same composition as the target composition, and the average layer thickness of the lower layer and the upper layer was further determined using a scanning electron microscope. When the cross section was measured, all showed substantially the same value as the target layer thickness.
[0043]
【The invention's effect】
From the results shown in Tables 3 to 12, in the (Al, Ti) N layer constituting the lower layer of the hard coating layer, the Al maximum content point and the Al minimum content point are alternately spaced at a predetermined interval in the layer thickness direction. And a component concentration distribution structure in which the content ratio of Al and Ti continuously changes 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. Invented coated cermet tools can be obtained by the component concentration distribution structure of the lower layer of the hard coating layer even if cutting of stainless steel, high manganese steel, and mild steel is performed at high speed with high heat generation and high load. The hard coating layer itself exhibits even more excellent heat-resistant plastic deformation due to its superior high-temperature hardness and heat resistance.As a result, wear takes the normal wear form without occurrence of uneven wear. 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 coated cermet tools, high-speed cutting causes thermoplastic deformation in the hard coating layer due to the lack of high-temperature hardness and heat resistance of the lower layer. As a result, the wear form takes an uneven wear form and promotes the progress of wear. Therefore, it is clear that all of them reach the service life in a relatively short time.
As described above, the coated cermet tool of the present invention can be used not only for high-speed cutting of work materials such as various steels and cast iron, but also for difficult work such as stainless steel, high manganese steel, and mild steel. Even in high-speed cutting of materials, excellent wear resistance will be demonstrated over a long period of time, so the performance of the cutting machine will be improved, and the labor and energy saving of cutting will be further reduced. It can respond satisfactorily.
[Brief description of the drawings]
FIG. 1 shows an arc ion plating apparatus used for forming a hard coating layer constituting a coated 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

On the surface of a cermet substrate made of tungsten carbide based cemented carbide or titanium carbonitride-based cermet, an arc ion plating apparatus provided with the rotary table for mounting the cermet substrate at the center of the apparatus is used.
(A) As the lower layer, the cathode electrode (evaporation source) of the arc ion plating apparatus is disposed opposite to both sides across the rotary table, and the highest Al content point is formed as the cathode electrode (evaporation source) on one side. An Al-Ti alloy for forming Al and an Al-Ti alloy for forming the lowest Al content point are disposed as the cathode electrode (evaporation source) on the other side, respectively, and the table is positioned at a predetermined radial distance from the central axis on the rotary table. A plurality of the cermet bases are mounted in a ring shape along the outer periphery, and in this state, the rotary table is rotated with the atmosphere inside the apparatus being a nitrogen atmosphere, and the cathode electrodes on both sides are rotated while the cermet base itself is rotated. An arc discharge is generated between the (evaporation source) and the anode electrode ,
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),
Al and Ti composite nitride 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 and the average layer thickness is 0.8 to 8 μm layer,
(B) As the upper layer, while rotating the rotary table with the atmosphere inside the apparatus as a nitrogen atmosphere, the cermet base body mounted in a ring shape on the rotary table also faces the rotary table while rotating itself, The lower side formed by vapor deposition on the surface of the cermet substrate on the rotary table by generating an arc discharge between a Ti-Si alloy disposed as a cathode electrode (evaporation source) of the arc ion plating apparatus and an anode electrode. Vapor deposited over the layers, and
_{_{_{Formula: (Ti 1- Z Si Z)}}} N ( provided that an atomic ratio, Z is shows the 0.10-0.50)
A composite nitride layer of Ti and Si having an average layer thickness of 0.5 to 5 μm,
A surface-coated cermet cutting tool that exhibits excellent wear resistance by high-speed cutting, which is formed by vapor-depositing a hard coating layer comprising the above (a) and (b).