JP4066341B2

JP4066341B2 - Surface-coated cemented carbide cutting tool with a hard coating layer with excellent adhesion and wear resistance

Info

Publication number: JP4066341B2
Application number: JP2002371191A
Authority: JP
Inventors: 昌史福村; 夏樹一宮; 高橋　　慧
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2002-12-24
Filing date: 2002-12-24
Publication date: 2008-03-26
Anticipated expiration: 2022-12-24
Also published as: JP2004202587A

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密着性と共に、すぐれた高温特性を有し、したがって各種の鋼や鋳鉄などの切削加工を、特に高い機械的および熱的衝撃を伴なう高切込みや高送りなどの重切削条件で、かつ高速で行なっても前記硬質被覆層に剥離の発生なく、すぐれた耐摩耗性を発揮する表面被覆超硬合金製切削工具（以下、被覆超硬工具という）に関するものである。
【０００２】
【従来の技術】
一般に、被覆超硬工具には、各種の鋼や鋳鉄などの被削材の旋削加工や平削り加工にバイトの先端部に着脱自在に取り付けて用いられるスローアウエイチップ、前記被削材の穴あけ切削加工などに用いられるドリルやミニチュアドリル、さらに前記被削材の面削加工や溝加工、肩加工などに用いられるソリッドタイプのエンドミルなどがあり、また前記スローアウエイチップを着脱自在に取り付けて前記ソリッドタイプのエンドミルと同様に切削加工を行うスローアウエイエンドミル工具などが知られている。
【０００３】
また、被覆超硬工具として、炭化タングステン（以下、ＷＣで示す）基超硬合金からなる基体（以下、超硬基体と云う）の表面に、組成式：（Ａｌ_YＴｉ_1-Y）Ｎ（ただし、原子比で、Ｙは０．４０〜０．６５を示す）を満足するＡｌとＴｉの複合窒化物［以下、（Ａｌ，Ｔｉ）Ｎで示す］層からなる硬質被覆層を１〜１５μｍの平均層厚で蒸着してなる被覆超硬工具が知られており、これが各種の鋼や鋳鉄などの連続切削や断続切削加工に用いられることも良く知られるところである（例えば、特許文献１参照）。
【０００４】
さらに、上記の被覆超硬工具が、例えば図２に概略説明図で示される物理蒸着装置の１種であるアークイオンプレーティング装置に上記の超硬基体を装入し、ヒータで装置内を、例えば５００℃の温度に加熱した状態で、アノード電極と所定組成を有するＡｌ−Ｔｉ合金がセットされたカソード電極（蒸発源）との間に、例えば電流：９０Ａの条件でアーク放電を発生させ、同時に装置内に反応ガスとして窒素ガスを導入して、例えば２Ｐａの反応雰囲気とし、一方上記超硬基体には、例えば−１００Ｖのバイアス電圧を印加した条件で、前記超硬合金基体の表面に、上記（Ａｌ，Ｔｉ）Ｎ層からなる硬質被覆層を蒸着することにより製造されることも知られている（例えば、特許文献１参照）。
【０００５】
【特許文献１】
特許第２６４４７１０号
【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、切削加工は高速化および重切削化の傾向にあるが、上記の従来被覆超硬工具においては、これを通常の切削加工条件で用いた場合には問題はないが、これを高い機械的および熱的衝撃を伴なう、重切削条件での高速切削に用いた場合には、前記硬質被覆層の超硬基体表面に対する密着性不足のために、前記硬質被覆層に剥離が発生し易く、これが原因で切刃部に欠けやチッピング（微小欠け）が発生し易くなることから、硬質被覆層の高温特性（高温硬さおよび耐熱性）が不十分なために、摩耗進行が加速することと相俟って、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、密着性および耐摩耗性のすぐれた硬質被覆層を有する被覆超硬工具を開発すべく、上記の従来被覆超硬工具を構成する硬質被覆層に着目し、研究を行った結果、
（ａ）上記の超硬基体を、例えば図２に示されるアークイオンプレーティング装置（この場合図１に例示されるアークイオンプレーティング装置を用いてもよい）に装着し、まず、カソード電極を用いずに、
装置内雰囲気温度（超硬基体温度）：３００〜５００℃、
雰囲気ガス：Ａｒ、
雰囲気圧力：１〜１０Ｐａ、
アーク放電電流：（アーク電源−ＯＦＦ）、
超硬基体印加バイアス電圧：−８００〜−１０００Ｖ、
処理時間：２〜１０分、
の条件で上記超硬基体の表面を前処理した後で、さらに超硬基体表面に、カソード電極として、例えば金属Ｔｉを用い、
装置内雰囲気温度：４５０〜５５０℃、
雰囲気ガス：Ａｒ、
雰囲気圧力：１〜１０Ｐａ、
アーク放電電流：１００〜２００Ａ、
超硬基体印加バイアス電圧：−９００〜１２００Ｖ、
の条件でアークイオンプレーティング表面処理を施すと、上記超硬基体の表面上には、蒸着層としての金属Ｔｉ層の形成はなく、前記超硬基体自体の表面部に、透過型電子顕微鏡を用いて組織観察した結果に基く判別で、非晶質化層の形成が確認されること。
なお、アークイオンプレーティング装置を用いての金属Ｔｉ層の蒸着形成は、
装置内雰囲気温度：３００〜５００℃、
雰囲気ガス：（使用せず）、
雰囲気圧力：０．１Ｐａ以下の真空、
カソード電極：金属Ｔｉ、
アーク放電電流：５０〜１００Ａ、
超硬基体印加バイアス電圧：−３０〜−１００Ｖ、
の条件で一般に行われている。
【０００８】
（ｂ）上記の表面部に非晶質化層が形成された超硬基体表面に、前記非晶質化層を表面から１〜５０ｎｍの範囲内の平均深さに亘って形成した状態で、上記の従来被覆超硬工具の硬質被覆層を構成する（Ａｌ，Ｔｉ）Ｎ層を、同じくアークイオンプレーティング装置を用いて形成すると、前記非晶質化層は高い活性を有し、反応性の高いものであることから、前記硬質被覆層の蒸着形成時に、これと反応して前記超硬基体表面と硬質被覆層との間にはきわめて強固な密着性が確保されるようになること。
【０００９】
（ｃ）上記の図２に示されるアークイオンプレーティング装置を用いて形成された従来被覆超硬工具を構成する（Ａｌ，Ｔｉ）Ｎ層は、層厚全体に亘って均質な高温硬さと耐熱性、および強度を有するが、例えば図１（ａ）に概略平面図で、同（ｂ）に概略正面図で示される構造のアークイオンプレーティング装置、すなわち装置中央部に超硬基体装着用回転テーブルを設け、前記回転テーブルを挟んで、一方側に相対的にＡｌ含有量の高い（Ｔｉ含有量の低い）Ａｌ−Ｔｉ合金、他方側に相対的にＴｉ含有量の高い（Ａｌ含有量の低い）Ｔｉ−Ａｌ合金をカソード電極（蒸発源）として対向配置したアークイオンプレーティング装置を用い、この装置の前記回転テーブル上の中心軸から半径方向に所定距離離れた位置に外周部に沿って複数の超硬基体をリング状に装着し、この状態で装置内雰囲気を窒素雰囲気として前記回転テーブルを回転させると共に、蒸着形成される硬質被覆層の層厚均一化を図る目的で超硬基体自体も自転させながら、前記の両側のカソード電極（蒸発源）とアノード電極との間にアーク放電を発生させて、前記超硬基体の表面に（Ａｌ，Ｔｉ）Ｎ層を形成すると、この結果の（Ａｌ，Ｔｉ）Ｎ層においては、回転テーブル上にリング状に配置された前記超硬基体が上記の一方側の相対的にＡｌ含有量の高い（Ｔｉ含有量の低い）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最高含有点が形成され、また前記超硬基体が上記の他方側の相対的にＴｉ含有量の高い（Ａｌ含有量の低い）Ｔｉ−Ａｌ合金のカソード電極に最も接近した時点で層中にＡｌ最低含有点が形成され、上記回転テーブルの回転によって層中には層厚方向にそって前記Ａｌ最高含有点とＡｌ最低含有点が所定間隔をもって交互に繰り返し現れると共に、前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌおよびＴｉ含有量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。
【００１０】
（ｄ）上記（ｃ）の繰り返し連続変化成分濃度分布構造の（Ａｌ，Ｔｉ）Ｎ層において、例えば対向配置のカソード電極（蒸発源）のそれぞれの組成を調製すると共に、超硬基体が装着されている回転テーブルの回転速度を制御して、
上記Ａｌ最高含有点が、組成式：（Ａｌ_XＴｉ_1-X）Ｎ（ただし、原子比で、Ｘは０．７０〜０．９５を示す）、
上記Ａｌ最低含有点が、組成式：（Ａｌ_YＴｉ_1-Y）Ｎ（ただし、原子比で、Ｙは０．４０〜０．６５を示す）、
をそれぞれ満足し、かつ隣り合う上記Ａｌ最高含有点とＡｌ最低含有点の厚さ方向の間隔を０．０１〜０．１μmとすると、
上記Ａｌ最高含有点部分では、上記の従来（Ａｌ，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（高温特性）を示し、一方上記Ａｌ最低含有点部分では、前記Ａｌ最高含有点部分に比してＡｌ含有量が低く、Ｔｉ含有量の高いものとなるので、高強度が確保され、かつこれらＡｌ最高含有点とＡｌ最低含有点の間隔をきわめて小さくしたことから、層全体の特性として高強度を保持した状態ですぐれた高温特性を具備するようになり、さらに上記（ａ）および（ｂ）の超硬基体表面部に形成された非晶質化層によって前記硬質被覆層の超硬基体表面に対する密着性もきわめて強固なものとなり、したがって、硬質被覆層がかかる構成の（Ａｌ，Ｔｉ）Ｎ層からなり、かつかかる（Ａｌ，Ｔｉ）Ｎ層を表面部に非晶質化層が形成された超硬基体の表面に蒸着してなる被覆超硬工具は、特にこれを高い機械的および熱的衝撃を伴なう、高速重切削条件での切削に用いた場合にも、前記硬質被覆層に剥離発生がなく、すぐれた耐摩耗性を発揮するようになること。
以上（ａ）〜（ｄ）に示される研究結果を得たのである。
【００１１】
この発明は、上記の研究結果に基づいてなされたものであって、装置中央部に超硬基体装着用回転テーブルを設け、前記回転テーブルを挟んで、一方側にＡｌ最高含有点形成用Ａｌ−Ｔｉ合金、他方側にＡｌ最低含有点形成用Ｔｉ−Ａｌ合金をカソード電極（蒸発源）として対向配置し、さらにカソード電極として非晶質化層形成用金属Ｔｉも装着したアークイオンプレーティング装置を用い、この装置の前記回転テーブル上の中心軸から半径方向に所定距離離れた位置に外周部に沿って複数の超硬基体をリング状に装着し、前記回転テーブルを回転させると共に、前記超硬基体自体も自転させながら、
（ａ）金属Ｔｉ層の形成がない条件で、前記金属Ｔｉのカソード電極とアノード電極との間にアーク放電を発生させるアークイオンプレーティング表面処理により、上記超硬基体の表面部に、表面から１〜５０ｎｍの範囲内の平均深さに亘って、非晶質化層を形成した状態で、
（ｂ）装置内雰囲気を窒素雰囲気として、上記回転テーブルの両側のカソード電極（蒸発源）とアノード電極との間にアーク放電を発生させて、前記超硬基体の表面に、（Ａｌ，Ｔｉ）Ｎからなる硬質被覆層を１〜１５μｍの全体平均層厚で蒸着してなる被覆超硬工具にして、
上記硬質被覆層が、層厚方向にそって、Ａｌ最高含有点（Ｔｉ最低含有点）とＡｌ最低含有点（Ｔｉ最高含有点）とが所定間隔をおいて交互に繰り返し存在し、かつ前記Ａｌ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含有量が連続的に変化する成分濃度分布構造を有し、
さらに、上記Ａｌ最高含有点が、組成式：（Ａｌ_ＸＴｉ_１−Ｘ）Ｎ（ただし、原子比で、Ｘは０．７０〜０．９５を示す）、
上記Ａｌ最低含有点が、組成式：（Ａｌ_ＹＴｉ_１−Ｙ）Ｎ（ただし、原子比で、Ｙは０．４０〜０．６５を示す）、
を満足し、かつ隣り合う上記Ａｌ最高含有点とＡｌ最低含有点の間隔が、０．０１〜０．１μmである、
密着性および耐摩耗性のすぐれた硬質被覆層を形成してなる被覆超硬工具に特徴を有するものである。
【００１２】
つぎに、この発明の被覆超硬工具において、これの構成を上記の通りに数値限定した理由を説明する。
Ａ．非晶質化層の表面からの平均深さ
超硬基体の表面部に形成された非晶質化層には、上記尾通り硬質被覆層の超硬基体表面に対する密着性を著しく向上させる作用があるが、その深さが１ｎｍ未満では所望のすぐれた密着性を確保することができず、一方超硬基体表面に対する硬質被覆層の密着性向上効果は表面からの平均深さが５０ｎｍで十分であることから、その表面からの平均深さを１〜５０ｎｍと定めた。
【００１３】
Ｂ．硬質被覆層
（ａ）Ａｌ最高含有点の組成
（Ａｌ，Ｔｉ）Ｎ層におけるＡｌには、高温硬さおよび耐熱性（高温特性）を向上させる作用があり、したがってＡｌ最高含有点でのＡｌの割合（Ｘ）がＴｉとの合量に占める割合（原子比）で０．７０未満では所望のすぐれた高温特性を確保することができず、一方その割合が同じく０．９５を越えると、Ｔｉの割合が低くなり過ぎて、急激に強度が低下し、切刃にチッピング（微小欠け）などが発生し易くなることから、その割合を０．７０〜０．９５と定めた。
【００１４】
（ｂ）Ａｌ最低含有点の組成
上記の通りＡｌ最高含有点は高温特性のすぐれたものであるが、反面強度の劣るものであるため、このＡｌ最高含有点の強度不足を補う目的で、Ｔｉ含有割合が高く、これによって高強度を有するようになるＡｌ最低含有点を厚さ方向に交互に介在させるものであり、したがってＡｌの割合（Ｙ）がＴｉとの合量に占める割合（原子比）で０．６５を越えると、所望のすぐれた強度を確保することができず、一方その割合が同じく０．４０未満になると、相対的にＴｉの割合が多くなり過ぎて、Ａｌ最低含有点に所望の高温特性を具備せしめることができなくなることから、その割合を０．４０〜０．６５と定めた。
【００１５】
（ｃ）Ａｌ最高含有点とＡｌ最低含有点間の間隔
その間隔が０．０１μm未満ではそれぞれの点を上記の組成で明確に形成することが困難であり、この結果層に所望のすぐれた高温特性と高強度を確保することができなくなり、またその間隔が０．１μmを越えるとそれぞれの点がもつ欠点、すなわちＡｌ最高含有点であれば強度不足、Ａｌ最低含有点であれば高温特性不足が層内に局部的に現れ、これが原因で切刃にチッピングが発生し易くなったり、摩耗進行が促進されるようになることから、その間隔を０．０１〜０．１μmと定めた。
【００１６】
（ｄ）全体平均層厚
その層厚が１μｍ未満では、所望の耐摩耗性を確保することができず、一方その平均層厚が１５μｍを越えると、切刃にチッピングが発生し易くなることから、その平均層厚を１〜１５μｍと定めた。
【００１７】
【発明の実施の形態】
つぎに、この発明の被覆超硬工具を実施例により具体的に説明する。
（実施例１）
原料粉末として、いずれも１〜３μｍの平均粒径を有するＷＣ粉末、ＴｉＣ粉末、ＺｒＣ粉末、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基超硬合金製の超硬基体Ａ１〜Ａ１０を形成した。
【００１８】
ついで、これら超硬基体Ａ−１〜Ａ−１０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のアークイオンプレーティング装置、すなわち回転テーブルを挟んで、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最低含有点形成用Ｔｉ−Ａｌ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最高含有点形成用Ａｌ−Ｔｉ合金が対向配置され、また非晶質化層形成用金属Ｔｉも装着されたアークイオンプレーティング装置に、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そって装着し、前記回転テーブル上で自転しながら回転する前記超硬基体Ａ−１〜Ａ−１０のそれぞれに、まず、
装置内雰囲気温度（超硬基体温度）：４００℃、
雰囲気ガス：Ａｒ、
雰囲気圧力：３Ｐａ、
カソード電極：（使用せず）、
アーク放電電流：（アーク電源−ＯＦＦ）、
超硬基体印加バイアス電圧：−９００Ｖ、
処理時間：３分、
の条件で前処理を施した後で、さらに、
装置内雰囲気温度：５００℃、
雰囲気ガス：Ａｒ、
雰囲気圧力：３Ｐａ、
カソード電極：金属Ｔｉ、
アーク放電電流：１５０Ａ、
超硬基体印加バイアス電圧：−１０００Ｖ、
の条件でアークイオンプレーティング表面処理を施すことにより、表面部に非晶質化層を形成した。なお、前記非晶質化層の表面からの形成深さは上記の条件でのアークイオンプレーティング表面処理の処理時間を調整することにより行った。
また、上記超硬基体Ａ−１〜Ａ−１０の表面部に形成された非晶質化層を、透過型電子顕微鏡を用いて組織観察（倍率：５０万倍）し、この観察結果に基づいて判別および測定したところ、それぞれ表２に示される表面からの平均深さ（５点測定の平均値）を示した。
【００１９】
引き続いて、上記の図１のアークイオンプレーティング装置内の温度をヒーター加熱により５００℃に保持した状態で、装置内に反応ガスとして窒素ガスを導入して２Ｐａの反応雰囲気とすると共に、上記の回転テーブル上で自転しながら回転する非晶質化層形成の超硬基体に−１００Ｖの直流バイアス電圧を印加して、それぞれのカソード電極(前記Ａｌ最低含有点形成用Ｔｉ−Ａｌ合金およびＡｌ最高含有点形成用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、もって前記非晶質化層形成の超硬基体Ａ１〜Ａ１０の表面に、層厚方向に沿って表２に示される目標組成のＡｌ最低含有点とＡｌ最高含有点とが交互に同じく表２に示される目標間隔で繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌおよびＴｉ含有量がそれざ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２に示される目標全体層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製スローアウエイチップ（以下、本発明被覆超硬チップと云う）１〜１０をそれぞれ製造した。
【００２０】
また、比較の目的で、上記のアークイオンプレーティング表面処理を施さず、したがって、表面部に非晶質化層の形成がない前記超硬基体Ａ１〜Ａ１０を、アセトン中で超音波洗浄し、乾燥した状態で、それぞれ図２に示される通常のアークイオンプレーティング装置に装入し、カソード電極（蒸発源）として種々の成分組成をもったＡｌ−Ｔｉ合金を装着し、装置内を排気して０．５Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、Ａｒガスを装置内に導入して１０ＰａのＡｒ雰囲気とし、この状態で超硬基体に−８００ｖのバイアス電圧を印加して超硬基体表面をＡｒガスボンバート洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して２Ｐａの反応雰囲気とすると共に、前記超硬基体に印加するバイアス電圧を−１００Ｖに下げて、前記カソード電極とアノード電極との間にアーク放電を発生させ、もって前記超硬基体Ａ１〜Ａ１０のそれぞれの表面に、表３に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ）Ｎ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製スローアウエイチップ（以下、従来被覆超硬チップと云う）１〜１０をそれぞれ製造した。
【００２１】
つぎに、上記本発明被覆超硬チップ１〜１０および従来被覆超硬チップ１〜１０について、これを工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、
被削材：ＪＩＳ・ＳＮＣＭ４３９の丸棒、
切削速度：２８０ｍ／ｍｉｎ．、
切り込み：５．５ｍｍ、
送り：０．２０ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での合金鋼の乾式連続高速高切り込み切削加工試験、
被削材：ＪＩＳ・Ｓ２５Ｃの長さ方向等間隔４本縦溝入り丸棒、
切削速度：４００ｍ／ｍｉｎ．、
切り込み：１．０ｍｍ、
送り：０．３５ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での炭素鋼の乾式断続高速高送り切削加工試験、さらに、
被削材：ＪＩＳ・ＦＣ３００の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３５０ｍ／ｍｉｎ．、
切り込み：５．５ｍｍ、
送り：０．２０ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での鋳鉄の乾式断続高速高切り込み切削加工試験を行い、いずれの切削加工試験でも切刃の逃げ面摩耗幅を測定した。この測定結果をそれぞれ表２，３に示した。
【００２２】
【表１】

【００２３】
【表２】

【００２４】
【表３】

【００２５】
（実施例２）
原料粉末として、平均粒径：５．５μｍを有する中粗粒ＷＣ粉末、同０．８μｍの微粒ＷＣ粉末、同１．３μｍのＴａＣ粉末、同１．２μｍのＮｂＣ粉末、同１．２μｍのＺｒＣ粉末、同２．３μｍのＣｒ₃Ｃ₂粉末、同１．５μｍのＶＣ粉末、同１．０μｍの（Ｔｉ，Ｗ）Ｃ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４に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、１００ＭＰａの圧力で所定形状の各種の圧粉体にプレス成形し、これらの圧粉体を、６Ｐａの真空雰囲気中、７℃／分の昇温速度で１３７０〜１４７０℃の範囲内の所定の温度に昇温し、この温度に１時間保持後、炉冷の条件で焼結して、直径が８ｍｍ、１３ｍｍ、および２６ｍｍの３種の超硬基体形成用丸棒焼結体を形成し、さらに前記の３種の丸棒焼結体から、研削加工にて、表４に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法を有し、かついずれもねじれ角：３０度の４枚刃スクエア形状をもった超硬基体（エンドミル）Ｃ−１〜Ｃ−８をそれぞれ製造した。
【００２６】
まず、これらの超硬基体（エンドミル）Ｃ−１〜Ｃ−８の表面部に、同じく上記の図１のアークイオンプレーティング装置を用いて、上記実施例１における条件と同一の条件で、アークイオンプレーティング表面処理を施すことにより、それぞれ表５に示される表面からの平均深さ（５点測定の平均値）の非晶質化層を形成した。
引き続いて、上記の非晶質化層形成の超硬基体（エンドミル）Ｃ−１〜Ｃ−８の表面に、上記の同じアークイオンプレーティング装置にて、上記実施例１と同一の条件で、層厚方向に沿って表５に示される目標組成のＡｌ最低含有点とＡｌ最高含有点とが交互に同じく表５に示される目標間隔で繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌおよびＴｉ含有量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５に示される目標全体層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製エンドミル（以下、本発明被覆超硬エンドミルと云う）１〜８をそれぞれ製造した。
【００２７】
また、比較の目的で、表面部に非晶質化層の形成がない上記の超硬基体（エンドミル）Ｃ−１〜Ｃ−８の表面をアセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表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層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製エンドミル（以下、従来被覆超硬エンドミルと云う）１〜８をそれぞれ製造した。
【００２８】
つぎに、上記本発明被覆超硬エンドミル１〜８および従来被覆超硬エンドミル１〜８のうち、本発明被覆超硬エンドミル１〜３および従来被覆超硬エンドミル１〜３については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＫＤ６１の板材、
切削速度：１７０ｍ／ｍｉｎ．、
溝深さ（切り込み）：５ｍｍ、
テーブル送り：５００ｍｍ／分、
の条件での工具鋼の湿式高速高切り込み溝加工試験、本発明被覆超硬エンドミル４〜６および従来被覆超硬エンドミル４〜６については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＵＳ３１６の板材、
切削速度：１８０ｍ／ｍｉｎ．、
溝深さ（切り込み）：６ｍｍ、
テーブル送り：５５０ｍｍ／分、
の条件でのステンレス鋼の湿式高速高切り込み溝加工試験、本発明被覆超硬エンドミル７，８および従来被覆超硬エンドミル７，８については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＣＭ４４０の板材、
切削速度：３００ｍ／ｍｉｎ．、
溝深さ（切り込み）：１０ｍｍ、
テーブル送り：６００ｍｍ／分、
の条件での合金鋼の湿式高速高切り込み溝加工（いずれの試験も水溶性切削油使用）をそれぞれ行い、いずれの溝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。この測定結果をそれぞれ表５，６にそれぞれ示した。
【００２９】
【表４】

【００３０】
【表５】

【００３１】
【表６】

【００３２】
（実施例３）
上記の実施例２で製造した直径が８ｍｍ（超硬基体Ｃ−１〜Ｃ−３形成用）、１３ｍｍ（超硬基体Ｃ−４〜Ｃ−６形成用）、および２６ｍｍ（超硬基体Ｃ−７、Ｃ−８形成用）の３種の丸棒焼結体を用い、この３種の丸棒焼結体から、研削加工にて、溝形成部の直径×長さがそれぞれ４ｍｍ×１３ｍｍ（超硬基体Ｄ−１〜Ｄ−３）、８ｍｍ×２２ｍｍ（超硬基体Ｄ−４〜Ｄ−６）、および１６ｍｍ×４５ｍｍ（超硬基体Ｄ−７、Ｄ−８）の寸法を有し、かついずれもねじれ角：３０度の２枚刃形状をもった超硬基体（ドリル）Ｄ−１〜Ｄ−８をそれぞれ製造した。
【００３３】
まず、これらの超硬基体（ドリル）Ｄ−１〜Ｄ−８の表面を、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における条件と同一の条件で、アークイオンプレーティング表面処理を施すことにより、表面部にそれぞれ表７に示される表面からの平均深さ（５点測定の平均値）の非晶質化層を形成した。
引き続いて、上記の非晶質化層形成の超硬基体（ドリル）Ｄ−１〜Ｄ−８の表面に、同じアークイオンプレーティング装置にて、上記実施例１と同一の条件で、層厚方向に沿って表７に示される目標組成のＡｌ最低含有点とＡｌ最高含有点とが交互に同じく表７に示される目標間隔で繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌおよびＴｉ含有量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７に示される目標全体層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製ドリル（以下、本発明被覆超硬ドリルと云う）１〜８をそれぞれ製造した。
【００３４】
また、比較の目的で、上記の表面部に非晶質化層の形成がない超硬基体（ドリル）Ｄ−１〜Ｄ−８の表面に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表８に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ）Ｎ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製ドリル（以下、従来被覆超硬ドリルと云う）１〜８をそれぞれ製造した。
【００３５】
つぎに、上記本発明被覆超硬ドリル１〜８および従来被覆超硬ドリル１〜８のうち、本発明被覆超硬ドリル１〜３および従来被覆超硬ドリル１〜３については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＫＤ１１の板材、
切削速度：９０ｍ／ｍｉｎ．、
送り：０．２ｍｍ／ｒｅｖ、
穴深さ：８ｍｍ
の条件での工具鋼の湿式高速高送り穴あけ加工試験、本発明被覆超硬ドリル４〜６および従来被覆超硬ドリル４〜６については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＣＭ４４０の板材、
切削速度：１５０ｍ／ｍｉｎ．、
送り：０．４ｍｍ／ｒｅｖ、
穴深さ：１５ｍｍ
の条件での合金鋼の湿式高速高送り穴あけ加工試験、本発明被覆超硬ドリル７，８および従来被覆超硬ドリル７，８については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＦＣ３００の板材、
切削速度：２００ｍ／ｍｉｎ．、
送り：０．６ｍｍ／ｒｅｖ、
穴深さ：２０ｍｍ
の条件での鋳鉄の湿式高速高送り穴あけ加工試験、をそれぞれ行い、いずれの湿式高速穴あけ加工試験（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７，８にそれぞれ示した。
【００３６】
【表７】

【００３７】
【表８】

【００３８】
この結果得られた本発明被覆超硬工具としての本発明被覆超硬チップ１〜１０、本発明被覆超硬エンドミル１〜８、および本発明被覆超硬ドリル１〜８を構成する硬質被覆層、並びに従来被覆超硬工具としての従来被覆超硬チップ１〜１０、従来被覆超硬エンドミル１〜８、および従来被覆超硬ドリル１〜８の硬質被覆層について、厚さ方向に沿ってＡｌ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、本発明被覆超硬工具の硬質被覆層では、Ａｌ最高含有点とＡｌ最低含有点とがそれぞれ目標値と実質的に同じ組成および間隔で交互に繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌおよびＴｉ含有量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、また硬質被覆層の全体平均層厚も目標全体層厚と実質的に同じ値を示した。一方前記従来被覆超硬工具の硬質被覆層では厚さ方向に沿って組成変化が見られず、かつ目標組成と実質的に同じ組成および目標全体層厚と実質的に同じ全体平均層厚を示すことが確認された。
【００３９】
【発明の効果】
表３〜９に示される結果から、硬質被覆層が超硬基体表面に、これの表面部に形成した非晶質化層によってきわめて強固に密着すると共に、前記硬質被覆層が、層厚方向にＡｌ最低含有点とＡｌ最高含有点とが交互に所定間隔をおいて繰り返し存在し、かつ前記Ａｌ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含有量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によって、すぐれた高温特性を具備するようになる本発明被覆超硬工具は、いずれも鋼や鋳鉄の切削加工を高い機械的および熱的衝撃を伴なう、高速重切削条件で行っても、硬質被覆層に剥離の発生なく、すぐれた耐摩耗性を発揮するのに対して、超硬基体表面部に非晶質化層の形成がなく、硬質被覆層が層厚方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ）Ｎ層からなる従来被覆超硬工具においては、高速重切削条件の切削加工では硬質被覆層の密着性不足および高温特性不足が原因で、硬質被覆層に剥離が発生し、摩耗の進行が促進されることと相俟って、比較的短時間で使用寿命に至ることが明らかである。
上述のように、この発明の被覆超硬工具は、特に各種の鋼や鋳鉄などの高速重切削条件での切削加工でも硬質被覆層がすぐれた耐剥離性および耐摩耗性を発揮し、長期に亘ってすぐれた切削性能を示すものであるから、切削加工装置の高性能化、並びに切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。
【図面の簡単な説明】
【図１】この発明の被覆超硬工具を構成する硬質被覆層を形成するのに用いたアークイオンプレーティング装置を示し、（ａ）は概略平面図、（ｂ）は概略正面図である。
【図２】従来被覆超硬工具を構成する硬質被覆層を形成するのに用いた通常のアークイオンプレーティング装置の概略説明図である。[0001]
BACKGROUND OF THE INVENTION
This invention has excellent high-temperature properties as well as excellent adhesion to hard coating layers, and therefore makes it possible to cut various steels and cast irons with high depth of cut and high with particularly high mechanical and thermal shock. The present invention relates to a surface-coated cemented carbide cutting tool (hereinafter referred to as a coated carbide tool) that exhibits excellent wear resistance without causing peeling of the hard coating layer even under heavy cutting conditions such as feeding and at high speed. Is.
[0002]
[Prior art]
In general, coated carbide tools include a throw-away tip that is attached to the tip of a cutting tool for turning and planing of various steels and cast irons, and drilling of the work material. There are drills and miniature drills used for processing, etc., and solid type end mills used for chamfering, grooving, shoulder processing, etc. of the work material. A slow-away end mill tool that performs cutting work in the same manner as a type end mill is known.
[0003]
Further, as a coated carbide tool, on the surface of a substrate made of tungsten carbide (hereinafter referred to as WC) -based cemented carbide (hereinafter referred to as a carbide substrate), a composition formula: (Al_YTi_1-Y) A hard coating layer composed of a composite nitride of Al and Ti [hereinafter referred to as (Al, Ti) N] satisfying N (wherein Y represents 0.40 to 0.65 in atomic ratio). Coated carbide tools deposited with an average layer thickness of 1 to 15 μm are known, and it is well known that they are used for continuous cutting and intermittent cutting of various steels and cast irons (for example, patents) Reference 1).
[0004]
Furthermore, the above-mentioned coated carbide tool is, for example, the above-mentioned carbide substrate is inserted into an arc ion plating apparatus which is one type of physical vapor deposition apparatus schematically shown in FIG. For example, in the state heated to a temperature of 500 ° C., an arc discharge is generated between the anode electrode and the cathode electrode (evaporation source) in which an Al—Ti alloy having a predetermined composition is set, for example, under a current of 90 A, At the same time, nitrogen gas is introduced into the apparatus as a reaction gas to give a reaction atmosphere of, for example, 2 Pa, while the cemented carbide substrate is applied to the surface of the cemented carbide substrate with a bias voltage of, for example, −100 V applied. It is also known to be produced by vapor-depositing a hard coating layer composed of the (Al, Ti) N layer (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent No. 2644710
[0006]
[Problems to be solved by the invention]
In recent years, the performance of cutting machines has been dramatically improved, while on the other hand, there are strong demands for labor saving and energy saving and further cost reduction for cutting, and with this, cutting tends to be faster and more heavy-duty. In the above conventional coated carbide tool, there is no problem when it is used under normal cutting conditions, but this is high speed cutting under heavy cutting conditions with high mechanical and thermal shock. When used in the above, due to insufficient adhesion of the hard coating layer to the surface of the superhard substrate, the hard coating layer is likely to be peeled off, which causes chipping or chipping (micro chipping) in the cutting edge. Because it tends to occur, the high-temperature properties (high-temperature hardness and heat resistance) of the hard coating layer are insufficient, and in combination with the acceleration of wear, the service life is reached in a relatively short time. Is the current situation.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed a hard coating that constitutes the above conventional coated carbide tool in order to develop a coated carbide tool having a hard coating layer with excellent adhesion and wear resistance. As a result of conducting research focusing on the layer,
(A) The above carbide substrate is mounted on, for example, an arc ion plating apparatus shown in FIG. 2 (in this case, the arc ion plating apparatus illustrated in FIG. 1 may be used). Without using
In-apparatus atmosphere temperature (carbide substrate temperature): 300 to 500 ° C.
Atmospheric gas: Ar,
Atmospheric pressure: 1-10 Pa,
Arc discharge current: (Arc power source-OFF),
Carbide substrate applied bias voltage: -800 to -1000 V,
Processing time: 2-10 minutes
After pre-treating the surface of the cemented carbide substrate under the conditions of, for example, using a metal Ti as a cathode electrode on the surface of the cemented carbide substrate,
In-apparatus ambient temperature: 450-550 ° C.
Atmospheric gas: Ar,
Atmospheric pressure: 1-10 Pa,
Arc discharge current: 100-200A
Carbide substrate applied bias voltage: -900 to 1200 V
When the surface treatment of the arc ion plating is performed under the above conditions, there is no formation of a metal Ti layer as a vapor deposition layer on the surface of the superhard substrate, and a transmission electron microscope is formed on the surface of the superhard substrate itself. The formation of an amorphized layer should be confirmed by discrimination based on the results of the observation of the structure.
In addition, vapor deposition formation of the metal Ti layer using an arc ion plating apparatus is
In-apparatus ambient temperature: 300-500 ° C.
Atmospheric gas: (not used),
Atmospheric pressure: vacuum of 0.1 Pa or less,
Cathode electrode: Ti metal,
Arc discharge current: 50-100A,
Carbide substrate bias voltage: -30 to -100V
It is generally done under the conditions of
[0008]
(B) On the surface of the cemented carbide substrate on which the amorphized layer is formed on the surface portion, the amorphized layer is formed over an average depth within a range of 1 to 50 nm from the surface, When the (Al, Ti) N layer constituting the hard coating layer of the above conventional coated carbide tool is formed using the same arc ion plating apparatus, the amorphized layer has high activity and reactivity. Therefore, when the hard coating layer is formed by vapor deposition, it reacts with it to ensure extremely strong adhesion between the surface of the superhard substrate and the hard coating layer.
[0009]
(C) The (Al, Ti) N layer constituting the conventional coated carbide tool formed by using the arc ion plating apparatus shown in FIG. 2 has a uniform high temperature hardness and heat resistance over the entire thickness. For example, the arc ion plating apparatus having the structure shown in the schematic plan view of FIG. 1A and the schematic front view of FIG. A table is provided, and an Al-Ti alloy having a relatively high Al content (low Ti content) on one side and a relatively high Ti content (on Al content) on the other side, with the rotary table interposed therebetween A low) Ti-Al alloy is used as a cathode electrode (evaporation source), and an arc ion plating apparatus is used. The apparatus is arranged along the outer circumference at a predetermined distance in the radial direction from the central axis on the rotary table of the apparatus. Multiple The carbide substrate is mounted in a ring shape, and in this state, the atmosphere inside the apparatus is changed to a nitrogen atmosphere, the rotary table is rotated, and the carbide substrate itself is rotated for the purpose of uniforming the thickness of the hard coating layer formed by vapor deposition. Then, an arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides to form an (Al, Ti) N layer on the surface of the cemented carbide substrate. , Ti) In the N layer, the cemented carbide substrate arranged in a ring shape on the rotary table is a cathode electrode of an Al—Ti alloy having a relatively high Al content (low Ti content) on the one side. At the point closest to the (evaporation source), the highest Al content point is formed in the layer, and the carbide substrate has a relatively high Ti content (low Al content) on the other side. Closest contact with alloy cathode At that time, the lowest Al content point is formed in the layer, and by rotating the rotary table, the highest Al content point and the lowest Al content point appear alternately in the layer thickness direction along the layer thickness direction. A component concentration distribution structure in which the Al and Ti contents continuously change from the Al highest content point to the Al lowest content point, and from the Al lowest content point to the Al highest content point, respectively.
[0010]
(D) In the (Al, Ti) N layer having the repeated continuous change component concentration distribution structure of (c) above, for example, the respective compositions of the cathode electrodes (evaporation sources) arranged opposite to each other are prepared, and a carbide substrate is mounted. Control the rotation speed of the rotating table
The Al maximum content point is the composition formula: (Al_XTi_1-X) N (however, in atomic ratio, X represents 0.70 to 0.95),
The Al minimum content point is the composition formula: (Al_YTi_1-Y) N (however, in atomic ratio, Y represents 0.40 to 0.65),
And the interval in the thickness direction between the adjacent Al highest content point and Al lowest content point adjacent to each other 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, and thus exhibits a higher temperature hardness and heat resistance (high temperature characteristics). On the other hand, the Al minimum content point portion has a lower Al content and a higher Ti content than the Al highest content point portion, so that high strength is ensured, and these Al highest content points and Al minimum content points are also obtained. Since the interval between the contained points is extremely small, the layer as a whole has excellent high-temperature characteristics while maintaining high strength, and further on the surface of the carbide substrate of the above (a) and (b). The formed amorphized layer also makes the adhesion of the hard coating layer to the surface of the superhard substrate extremely strong. Therefore, the hard coating layer is composed of an (Al, Ti) N layer having such a structure, and such ( Al, i) A coated carbide tool formed by vapor-depositing an N layer on the surface of a cemented carbide substrate having an amorphized layer formed on the surface thereof is particularly suitable for high-speed heavy load with high mechanical and thermal shock. Even when used for cutting under cutting conditions, the hard coating layer has no peeling and exhibits excellent wear resistance.
The research results shown in (a) to (d) above were obtained.
[0011]
  This invention was made based on the above research results,A carbide base mounting rotary table is provided in the center of the apparatus, and the rotary table is sandwiched between the Al-Ti alloy for forming the highest Al content point and the Ti-Al alloy for forming the lowest Al content point on the other side. An arc ion plating apparatus, which is opposed to the electrode (evaporation source) and further equipped with a metal Ti for forming an amorphized layer as a cathode electrode, is used, and a predetermined distance in the radial direction from the central axis on the rotary table of the apparatus. While mounting a plurality of carbide substrates in a ring shape along the outer periphery at a distant position, rotating the rotary table, while rotating the carbide substrate itself,
(A)An arc discharge is generated between the cathode electrode and the anode electrode of the metal Ti under the condition that no metal Ti layer is formed.In a state where an amorphous layer is formed over the average depth within the range of 1 to 50 nm from the surface on the surface portion of the cemented carbide substrate by the arc ion plating surface treatment,
(B)The atmosphere inside the apparatus is a nitrogen atmosphere, and arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides of the rotary table, and the surface of the cemented carbide substrate is formed.Coated carbide tool formed by vapor-depositing a hard coating layer made of (Al, Ti) N with an overall average layer thickness of 1 to 15 μmIn,
  In the hard coating layer, the Al highest content point (Ti lowest content point) and the Al lowest content point (Ti highest content point) are alternately present at predetermined intervals along the layer thickness direction, and the Al Having a component concentration distribution structure in which the Al and Ti contents continuously change from the highest content point to the Al lowest content point, from the lowest Al content point to the highest Al content point,
  Furthermore, the Al highest content point is the composition formula: (Al_XTi_1-X) N (however, in atomic ratio, X represents 0.70 to 0.95),
  The Al minimum content point is the composition formula: (Al_YTi_1-Y) N (however, in atomic ratio, Y represents 0.40 to 0.65),
And the interval between the Al highest content point and the Al lowest content point adjacent to each other is 0.01 to 0.1 μm.
This is characterized by a coated carbide tool formed with a hard coating layer having excellent adhesion and wear resistance.
[0012]
Next, the reason why the configuration of the coated carbide tool of the present invention is numerically limited as described above will be described.
A. Average depth from the surface of the amorphized layer
The amorphized layer formed on the surface of the cemented carbide substrate has the effect of remarkably improving the adhesion of the tail hard coating layer to the surface of the cemented carbide substrate. While excellent adhesion cannot be ensured, on the other hand, the adhesion improvement effect of the hard coating layer on the surface of the carbide substrate is sufficient because the average depth from the surface is 50 nm. It was determined to be 1 to 50 nm.
[0013]
B. Hard coating layer
(A) Composition of the highest Al content point
Al in the (Al, Ti) N layer has the effect of improving the high-temperature hardness and heat resistance (high-temperature characteristics), and therefore the proportion (X) of Al at the highest Al content point accounts for the total amount with Ti. If the ratio (atomic ratio) is less than 0.70, the desired excellent high temperature characteristics cannot be secured. On the other hand, if the ratio exceeds 0.95, the Ti ratio becomes too low and the strength rapidly increases. The ratio is set to 0.70 to 0.95 because the cutting edge tends to cause chipping (small chipping) and the like.
[0014]
(B) Composition of Al minimum content point
As described above, the highest Al content point is excellent in high-temperature characteristics, but on the other hand, it is inferior in strength. Therefore, in order to compensate for the insufficient strength of this Al highest content point, the Ti content is high, thereby increasing the strength. When the Al content (Y) exceeds 0.65 in the ratio (atomic ratio) to the total amount with Ti, the Al minimum content point that has the following is alternately interposed in the thickness direction. The desired excellent strength cannot be ensured, while if the ratio is also less than 0.40, the ratio of Ti is excessively increased so that the lowest Al content point has desired high temperature characteristics. The ratio was determined to be 0.40 to 0.65.
[0015]
(C) Interval between the highest Al content point and the lowest Al content point
If the distance is less than 0.01 μm, it is difficult to clearly form each point with the above composition, and as a result, the desired excellent high-temperature characteristics and high strength cannot be secured in the layer, and the distance When the thickness exceeds 0.1 μm, the disadvantage of each point, that is, if the Al content is the highest, the strength is insufficient, and if the Al content is the minimum, the high temperature property is localized locally in the layer. Since the chipping easily occurs and the progress of wear is promoted, the interval is set to 0.01 to 0.1 μm.
[0016]
(D) Overall average layer thickness
If the layer thickness is less than 1 μm, the desired wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 15 μm, chipping tends to occur at the cutting edge. It was defined as ˜15 μm.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated carbide tool of the present invention will be specifically described with reference to examples.
Example 1
As raw material powders, WC powder, TiC powder, ZrC powder, 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 Cemented carbide substrates A1 to A10 made of WC-based cemented carbide having a chip shape of standard / CNMG120408 were formed.
[0018]
Next, each of these carbide substrates A-1 to A-10 is ultrasonically cleaned in acetone and dried, and the cathode on one side is sandwiched between the arc ion plating apparatus of FIG. Ti-Al alloy for forming Al minimum content point with various component compositions as an electrode (evaporation source), Al for forming Al maximum content point with various component compositions as a cathode electrode (evaporation source) on the other side -An arc ion plating apparatus in which a Ti alloy is arranged opposite to each other and a metal Ti for forming an amorphized layer is mounted on the outer peripheral portion at a predetermined distance in the radial direction from the central axis on the rotary table. First, each of the carbide substrates A-1 to A-10 rotating while rotating on the rotary table,
In-apparatus atmosphere temperature (carbide substrate temperature): 400 ° C.
Atmospheric gas: Ar,
Atmospheric pressure: 3 Pa,
Cathode electrode: (not used),
Arc discharge current: (Arc power source-OFF),
Carbide substrate bias voltage: -900V
Processing time: 3 minutes
After pre-processing under the conditions of
In-apparatus temperature: 500 ° C
Atmospheric gas: Ar,
Atmospheric pressure: 3 Pa,
Cathode electrode: Ti metal,
Arc discharge current: 150A,
Carbide substrate bias voltage: -1000V
By applying arc ion plating surface treatment under the conditions described above, an amorphous layer was formed on the surface portion. The formation depth of the amorphized layer from the surface was adjusted by adjusting the treatment time of the arc ion plating surface treatment under the above conditions.
Further, the amorphized layer formed on the surface portions of the above-mentioned carbide substrates A-1 to A-10 was subjected to a structure observation (magnification: 500,000 times) using a transmission electron microscope, and based on the observation result. As a result, the average depth from the surface shown in Table 2 (average value of five-point measurement) was shown.
[0019]
Subsequently, in the state where the temperature in the arc ion plating apparatus in FIG. 1 is maintained at 500 ° C. by heating with a heater, nitrogen gas is introduced into the apparatus as a reaction gas to obtain a reaction atmosphere of 2 Pa. A DC bias voltage of −100 V is applied to a cemented carbide substrate that rotates while rotating on a turntable, and each cathode electrode (the Ti—Al alloy for forming the lowest Al content point and the highest Al content) is applied. An arc discharge is generated by passing a current of 100 A between the anode-containing Al-Ti alloy) and the anode electrode, so that the surface of the amorphized layer-formed carbide substrates A1 to A10 has a layer thickness direction. The Al minimum content point and the Al maximum content point of the target composition shown in Table 2 are repeatedly present at the target intervals shown in Table 2 alternately and before the Al maximum content point. Al minimum content point, having a component concentration distribution structure in which the Al and Ti contents continuously vary from the Al minimum content point to the Al maximum content point, and also having the target total layer thickness shown in Table 2 By depositing the hard coating layer, throwaway tips made of the surface-coated cemented carbide of the present invention (hereinafter referred to as the present coated carbide tips) 1 to 10 as the coated carbide tools of the present invention were produced.
[0020]
Further, for the purpose of comparison, the carbide substrates A1 to A10 that are not subjected to the above-described arc ion plating surface treatment and therefore do not have an amorphous layer formed on the surface portion are ultrasonically cleaned in acetone. In the dry state, each is loaded into the normal arc ion plating apparatus shown in FIG. 2, and Al—Ti alloys having various composition are mounted as cathode electrodes (evaporation sources), and the inside of the apparatus is evacuated. The inside of the apparatus is heated to 500 ° C. with a heater while maintaining a vacuum of 0.5 Pa or lower, and Ar gas is introduced into the apparatus to form an Ar atmosphere of 10 Pa. A voltage is applied to clean the surface of the carbide substrate with Ar gas bombardment, and then nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 2 Pa. The target voltage and the target layer thickness shown in Table 3 are formed on the surfaces of the carbide substrates A1 to A10 by reducing arc voltage to -100V and generating arc discharge between the cathode electrode and the anode electrode. Made of a conventional surface-coated cemented carbide alloy as a conventional coated carbide tool by vapor-depositing a hard coating layer composed of an (Al, Ti) N layer having substantially no composition change along the thickness direction Slow away tips (hereinafter referred to as conventional coated carbide tips) 1 to 10 were produced.
[0021]
Next, for the above-described coated carbide chips 1 to 10 and the conventional coated carbide chips 1 to 10 in the state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SNCM439 round bar,
Cutting speed: 280 m / min. ,
Cutting depth: 5.5 mm,
Feed: 0.20 mm / rev. ,
Cutting time: 8 minutes
Dry-type continuous high-speed high-cut cutting test of alloy steel under the conditions of
Work material: JIS · S25C lengthwise equidistantly 4 vertical grooved round bars,
Cutting speed: 400 m / min. ,
Cutting depth: 1.0 mm,
Feed: 0.35 mm / rev. ,
Cutting time: 8 minutes
Dry intermittent high-speed high-feed cutting test of carbon steel under the conditions of
Work material: JIS / FC300 lengthwise equidistant 4 bars with vertical grooves,
Cutting speed: 350 m / min. ,
Cutting depth: 5.5 mm,
Feed: 0.20 mm / rev. ,
Cutting time: 8 minutes
A dry interrupted high-speed high-cut cutting test of cast iron was performed under the conditions described above, and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Tables 2 and 3, respectively.
[0022]
[Table 1]

[0023]
[Table 2]

[0024]
[Table 3]

[0025]
(Example 2)
As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, ZrC of 1.2 μm Powder, 2.3 μm Cr_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 4, 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 diameter of the cutting edge portion was formed by forming three types of 26 mm round bar sintered bodies for forming a carbide substrate and grinding the above three types of round bar sintered bodies in the combinations shown in Table 4. × Length is 6mm × 13mm, 10mm × 22mm, and Has dimensions of 20 mm × 45 mm, and both twist angle: 30 degrees carbide substrate having a 4 flute square shape (end mills) C-1 through C-8 were prepared, respectively.
[0026]
First, on the surface portions of these carbide substrates (end mills) C-1 to C-8, the arc ion plating apparatus of FIG. By performing ion plating surface treatment, an amorphous layer having an average depth (average value of five-point measurement) from the surface shown in Table 5 was formed.
Subsequently, the same arc ion plating apparatus as described above is used on the surfaces of the above-described amorphized layer-formed carbide substrates (end mills) C-1 to C-8, under the same conditions as in Example 1. Along the layer thickness direction, the Al minimum content point and the Al maximum content point of the target composition shown in Table 5 are alternately and repeatedly present at the target interval shown in Table 5, and from the Al maximum content point to the Al minimum content point. A hard coating layer having a component concentration distribution structure in which the Al and Ti contents continuously change from the content point, the Al minimum content point to the Al maximum content point, and also having the target total layer thickness shown in Table 5 The surface-coated cemented carbide end mills (hereinafter referred to as the present invention coated carbide end mills) 1 to 8 as the present invention coated carbide tools were produced, respectively.
[0027]
Further, for the purpose of comparison, the surfaces of the above-mentioned carbide substrates (end mills) C-1 to C-8, which do not have an amorphous layer formed on the surface, are ultrasonically washed in acetone and dried. Similarly, a normal arc ion plating apparatus shown in FIG. 2 is inserted, and has the target composition and target layer thickness shown in Table 6 under the same conditions as in Example 1, and along the layer thickness direction. By vapor-depositing a hard coating layer composed of an (Al, Ti) N layer having substantially no composition change, a conventional surface-coated cemented carbide end mill (hereinafter referred to as a conventional coated carbide end mill) is used as a conventional coated carbide tool. ) 1-8 were produced respectively.
[0028]
Next, of the present invention coated carbide end mills 1-8 and conventional coated carbide end mills 1-8, the present invention coated carbide end mills 1-3 and conventional coated carbide end mills 1-3 are as follows:
Work material: Plane dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SKD61 plate material,
Cutting speed: 170 m / min. ,
Groove depth (cut): 5 mm,
Table feed: 500 mm / min,
With respect to the tool steel wet high-speed and high-groove grooving test, the present invention coated carbide end mills 4-6 and the conventional coated carbide end mills 4-6,
Work material: Plane size: 100 mm × 250 mm, thickness: 50 mm JIS / SUS316 plate material,
Cutting speed: 180 m / min. ,
Groove depth (cut): 6 mm
Table feed: 550 mm / min,
With respect to the wet high speed high cutting groove processing test of stainless steel under the conditions of the present invention, the coated carbide end mills 7 and 8 of the present invention and the conventional coated carbide end mills 7 and 8 are as follows:
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SCM440 plate material,
Cutting speed: 300 m / min. ,
Groove depth (cut): 10 mm,
Table feed: 600 mm / min,
Wet high-speed, high-groove grooving of alloy steel under the above conditions (both tests use water-soluble cutting oil), and in each grooving test, the flank wear width of the outer peripheral edge of the cutting edge is a guide for service life The cutting groove length up to 0.1 mm was measured. The measurement results are shown in Tables 5 and 6, respectively.
[0029]
[Table 4]

[0030]
[Table 5]

[0031]
[Table 6]

[0032]
(Example 3)
The diameters produced in Example 2 above were 8 mm (for forming carbide substrates C-1 to C-3), 13 mm (for forming carbide substrates C-4 to C-6), and 26 mm (for carbide substrates C-). 7, for C-8 formation), from these three types of round bar sintered bodies, the diameter x length of the groove forming portion is 4 mm x 13 mm (by grinding), respectively. Carbide substrates D-1 to D-3), 8 mm × 22 mm (Carbide substrates D-4 to D-6), and 16 mm × 45 mm (Carbide substrates D-7, D-8), In addition, carbide substrates (drills) D-1 to D-8 each having a two-blade shape with a twist angle of 30 degrees were manufactured.
[0033]
First, the surfaces of these cemented carbide substrates (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone, and dried, and then applied to the arc ion plating apparatus shown in FIG. By charging and performing arc ion plating surface treatment under the same conditions as in Example 1 above, the average depth from the surface shown in Table 7 for each surface portion (average value of 5-point measurement) An amorphous layer was formed.
Subsequently, the layer thickness of the above-described amorphized layer-formed carbide substrates (drills) D-1 to D-8 on the same arc ion plating apparatus under the same conditions as in Example 1 above. Along the direction, the Al minimum content point and the Al maximum content point of the target composition shown in Table 7 alternately and repeatedly exist at the target intervals shown in Table 7, and from the Al maximum content point to the Al minimum content point A hard coating layer having a component concentration distribution structure in which the Al and Ti contents continuously change from the Al minimum content point to the Al maximum content point, respectively, and having the target total layer thickness shown in Table 7 is also deposited. As a result, drills made of the surface-coated cemented carbide of the present invention (hereinafter referred to as the present invention coated carbide drill) 1 to 8 as the coated carbide tool of the present invention were produced.
[0034]
Further, for the purpose of comparison, honing is performed on the surfaces of the carbide substrates (drills) D-1 to D-8 in which an amorphized layer is not formed on the surface portion, and ultrasonic cleaning is performed in acetone. In the dried state, the same arc ion plating apparatus as shown in FIG. 2 was charged, and under the same conditions as in Example 1, the target composition and target layer thickness shown in Table 8 were obtained. The conventional surface-coated cemented carbide drill (hereinafter referred to as conventional coating) is used as a conventional coated carbide tool by depositing a hard coating layer consisting of an (Al, Ti) N layer substantially unchanged in composition along the thickness direction. 1 to 8 were manufactured.
[0035]
Next, of the present invention coated carbide drills 1-8 and conventional coated carbide drills 1-8, the present invention coated carbide drills 1-3 and conventional coated carbide drills 1-3,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SKD11 plate material,
Cutting speed: 90 m / min. ,
Feed: 0.2mm / rev,
Hole depth: 8mm
With respect to the tool steel wet high-speed high-feed drilling test, the present invention coated carbide drills 4-6 and the conventional coated carbide drills 4-6,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SCM440 plate material,
Cutting speed: 150 m / min. ,
Feed: 0.4mm / rev,
Hole depth: 15mm
For the wet high-speed high-feed drilling test of alloy steel under the conditions of the present invention, the coated carbide drills 7 and 8 of the present invention and the conventional coated carbide drills 7 and 8
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS / FC300 plate material,
Cutting speed: 200 m / min. ,
Feed: 0.6mm / rev,
Hole depth: 20mm
We performed high-speed high-feed high-drilling drilling test of cast iron under the above conditions. In any wet high-speed drilling test (using water-soluble cutting oil), the flank wear width of the tip cutting edge surface reached 0.3 mm. The number of drilling operations was measured. The measurement results are shown in Tables 7 and 8, respectively.
[0036]
[Table 7]

[0037]
[Table 8]

[0038]
The present coated carbide tips 1-10 as the present coated carbide tool obtained as a result, the present coated carbide end mills 1-8, and the hard coating layer constituting the present coated carbide drills 1-8, In addition, with respect to the hard coating layers of the conventional coated carbide tips 1 to 10, the conventional coated carbide end mills 1 to 8, and the conventional coated carbide drills 1 to 8 as the conventional coated carbide tools, Al and Ti along the thickness direction In the hard coating layer of the coated carbide tool of the present invention, the Al maximum content point and the Al minimum content point are respectively substantially the same in composition and interval as the target values. A component concentration distribution structure in which Al and Ti contents are present alternately and continuously, and the Al and Ti contents continuously change from the highest Al content point to the lowest Al content point and from the lowest Al content point to the highest Al content point. The has been confirmed to have, also showed an overall average layer thickness even entire target layer thickness substantially the same value of the hard layer. On the other hand, the hard coating layer of the conventional coated carbide tool shows no composition change along the thickness direction, and shows substantially the same composition as the target composition and substantially the same total average layer thickness as the target total layer thickness. It was confirmed.
[0039]
【The invention's effect】
From the results shown in Tables 3 to 9, the hard coating layer adhered to the surface of the superhard substrate very firmly by the amorphized layer formed on the surface portion thereof, and the hard coating layer was Al lowest content point and Al highest content point alternately and repeatedly exist at predetermined intervals, and Al and Ti from the Al highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point The coated carbide tool of the present invention, which has excellent high-temperature characteristics by having a component concentration distribution structure in which the contents each continuously change, is capable of cutting both steel and cast iron with high mechanical and thermal properties. Even when performed under high-speed heavy cutting conditions with mechanical impact, the hard coating layer exhibits excellent wear resistance without delamination, whereas the surface of the carbide substrate has an amorphous layer. No formation, hard coating layer thickness In conventional coated carbide tools consisting of (Al, Ti) N layers with virtually no composition change along the direction, due to lack of adhesion and high temperature characteristics of the hard coating layer in high speed heavy cutting conditions It is clear that the service life is reached in a relatively short time in combination with the occurrence of peeling in the hard coating layer and the accelerated progress of wear.
As described above, the coated cemented carbide tool of the present invention exhibits excellent peeling resistance and wear resistance with a hard coating layer even in cutting processing under high-speed heavy cutting conditions such as various steels and cast iron, for a long time. Since it shows excellent cutting performance, it can sufficiently satisfy the high performance of the cutting device, the labor saving and energy saving of the cutting, and the 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 carbide tool of the present invention, wherein (a) is a schematic plan view and (b) is a schematic front view.
FIG. 2 is a schematic explanatory view of a normal arc ion plating apparatus used to form a hard coating layer constituting a conventional coated carbide tool.

Claims

A rotating table for mounting a tungsten carbide base cemented carbide substrate is provided in the center of the apparatus, and the Al-Ti alloy for forming the Al highest content point is formed on one side, and the Ti for forming the lowest Al content point is formed on the other side with the rotating table interposed therebetween. -An arc ion plating apparatus in which an Al alloy is disposed as a cathode electrode (evaporation source) facing each other, and an amorphized layer forming metal Ti is also mounted as a cathode electrode, from the central axis on the rotary table of the apparatus. A plurality of the bases are mounted in a ring shape along the outer peripheral portion at a position separated by a predetermined distance in the radial direction, while rotating the rotary table and rotating the base body itself,
(A) From the surface to the surface portion of the substrate by arc ion plating surface treatment for generating arc discharge between the cathode electrode and the anode electrode of the metal Ti under the condition that no metal Ti layer is formed . With the amorphized layer formed over an average depth in the range of 50 nm,
(B) The atmosphere inside the apparatus is a nitrogen atmosphere, and arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides of the rotary table , and a composite nitride of Al and Ti is formed on the surface of the substrate . in the surface-coated cemented carbide cutting tools of hard coating layer formed by depositing the whole average layer thickness of 1~15μm consisting
In the hard coating layer, the Al highest content point (Ti lowest content point) and the Al lowest content point (Ti highest content point) are alternately present at predetermined intervals along the layer thickness direction, and the Al Having a component concentration distribution structure in which the Al and Ti contents continuously change from the highest content point to the Al lowest content point, from the lowest Al content point to the highest Al content point,
Furthermore, the Al highest content point is the composition formula: (Al _X Ti _1-X ) N (however, in atomic ratio, X represents 0.70 to 0.95),
The Al minimum content point is a composition formula: (Al _Y Ti _1-Y ) N (however, Y is 0.40 to 0.65 in atomic ratio),
And the interval between adjacent Al highest content point and Al lowest content point adjacent to each other is 0.01 to 0.1 μm,
A surface-coated cemented carbide cutting tool formed by forming a hard coating layer having excellent adhesion and wear resistance.