JP4320707B2

JP4320707B2 - Cutting tool made of surface-coated cemented carbide that exhibits excellent chipping resistance under high-speed heavy cutting conditions.

Info

Publication number: JP4320707B2
Application number: JP2003020616A
Authority: JP
Inventors: 強大上; 幸生青木; 裕介田中
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2003-01-29
Filing date: 2003-01-29
Publication date: 2009-08-26
Anticipated expiration: 2023-01-29
Also published as: JP2004230498A

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強度を有し、かつ高温硬さと耐酸化性にもすぐれ、したがって特に各種の鋼や鋳鉄などの切削加工を、高速で、かつ高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合に、硬質被覆層がすぐれた耐チッピング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、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、さらに切刃が断続切削加工形態をとる面削加工や溝加工、肩加工などに用いられるソリッドタイプのエンドミルなどがあり、また前記スローアウエイチップを着脱自在に取り付けて前記ソリッドタイプのエンドミルと同様に切削加工を行うスローアウエイエンドミル工具などが知られている。
【０００３】
また、被覆超硬工具として、炭化タングステン（以下、ＷＣで示す）基超硬合金または炭窒化チタン（以下、ＴｉＣＮで示す）基サーメットからなる基体（以下、これらを総称して超硬基体と云う）の表面に、組成式：（Ｔａ_1-XＢ_X）Ｎ（ただし、原子比で、Ｘは０．４０〜０．６０を示す）を満足するＴａとＢの複合窒化物［以下、（Ｔａ，Ｂ）Ｎで示す］層からなる硬質被覆層を０．５〜１０μｍの平均層厚で物理蒸着してなる被覆超硬工具が提案され、特にこれら被覆超硬工具は、これの硬質被覆層がＴａ成分によるすぐれた高温強度、およびＢ成分によるすぐれた高温硬さと耐酸化性を具備することから、各種の鋼や鋳鉄などの連続切削や断続切削を高速加工条件で行なってもすぐれた切削性能を示すことが知られている（例えば特許文献１参照）。
【０００４】
さらに、上記の被覆超硬工具が、例えば図２に概略説明図で示される物理蒸着装置の１種であるアークイオンプレーティング装置に上記の超硬基体を装入し、ヒータで装置内を、例えば５００℃の温度に加熱した状態で、アノード電極と所定組成を有するＴａ−Ｂ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：１５０Ａ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（Ｔａ，Ｂ）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。
【０００５】
【特許文献１】
特開平０６−０４１７６０号公報
【０００６】
【発明が解決しようとする課題】
近年の切削加工装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求は強く、これに伴い、切削加工は、高速で、かつ高切り込みや高送りなどの重切削条件で行なわれる傾向にあるが、上記の従来被覆超硬工具においては、これを高速切削加工条件で用いた場合には問題はないが、高速切削加工を高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合には、特に硬質被覆層の高温強度不足が原因でチッピング（微小割れ）が発生し易くなり、比較的短時間で使用寿命に至るのが現状である。
【０００７】
【課題を解決するための手段】
そこで、本発明者等は、上述のような観点から、特に高速重切削加工条件で硬質被覆層がすぐれた耐チッピング性を発揮する被覆超硬工具を開発すべく、上記の従来被覆超硬工具を構成する硬質被覆層に着目し、研究を行った結果、
（ａ）上記の図２に示されるアークイオンプレーティング装置を用いて形成された従来被覆超硬工具を構成する（Ｔａ，Ｂ）Ｎ層は、層厚全体に亘って実質的に均一な組成を有し、したがって均質な高温強度と、さらに高温硬さおよび耐酸化性を有するが、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Ｂ含有量の高いＴａ−Ｂ合金、他方側に相対的にＢ含有量の低いＴａ−Ｂ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（Ｔａ，Ｂ）Ｎ層を形成すると、この結果の（Ｔａ，Ｂ）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Ｂ含有量の高いＴａ−Ｂ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Ｂ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Ｂ含有量の低いＴａ−Ｂ合金のカソード電極に最も接近した時点で層中にＢ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Ｂ最高含有点とＢ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Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が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（Ｔａ，Ｂ）Ｎ層において、対向配置の一方側のカソード電極（蒸発源）である相対的にＢ含有量の高いＴａ−Ｂ合金におけるＢ含有量を上記の従来被覆超硬工具を構成する（Ｔａ，Ｂ）Ｎ層の形成に用いられたＴａ−Ｂ合金と同じＢ含有量とし、かつ同他方側のカソード電極（蒸発源）であるＴａ−Ｂ合金におけるＢ含有量を前記一方側のカソード電極であるＴａ−Ｂ合金のＢ含有量に比して相対的に低いものとする共に、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Ｂ最高含有点が、組成式：（Ｔａ_1-XＢ_X）Ｎ（ただし、原子比で、Ｘは０．４０〜０．６０を示す）、
上記Ｂ最低含有点が、組成式：（Ｔａ_1-YＢ_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Ｂ最高含有点とＢ最低含有点の厚さ方向の間隔を０．０１〜０．１μmとすると、
上記Ｂ最高含有点部分では、上記の従来（Ｔａ，Ｂ）Ｎ層と同等のＢ含有量となることから、上記の従来硬質被覆層を構成する（Ｔａ，Ｂ）Ｎ層と同等のすぐれた高温硬さと耐酸化性を示し、一方上記Ｂ最低含有点部分では、前記Ｂ最高含有点部分に比してＢ含有量が低く、Ｔａ含有量の高いものとなるので、一段と高い高温強度が確保され、かつこれらＢ最高含有点とＢ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すぐれた高温硬さと耐酸化性を保持した状態ですぐれた高温強度を具備するようになり、したがって、硬質被覆層がかかる構成の（Ｔａ，Ｂ）Ｎ層からなる被覆超硬工具は、各種の鋼や鋳鉄などの切削加工を、高速で、特に高い機械的衝撃を伴うので高い高温強度が要求される、高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング性を発揮するようになること。
以上（ａ）および（ｂ）に示される研究結果を得たのである。
【０００９】
この発明は、上記の研究結果に基づいてなされたものであって、超硬基体の表面に、（Ｔａ，Ｂ）Ｎ層からなる硬質被覆層を０．５〜１０μｍの全体平均層厚で物理蒸着してなる被覆超硬工具において、
上記硬質被覆層が、層厚方向にそって、Ｂ最高含有点とＢ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Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ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Ｂ最高含有点が、
組成式：（Ｔａ_1-XＢ_X）Ｎ（ただし、原子比で、Ｘは０．４０〜０．６０を示す）、
上記Ｂ最低含有点が、
組成式：（Ｔａ_1-YＢ_Y）Ｎ（ただし、原子比で、Ｙは０．０５〜０．３０を示す）、
を満足し、かつ隣り合う上記Ｂ最高含有点とＢ最低含有点の間隔が、０．０１〜０．１μmである、
高速重切削加工条件で硬質被覆層がすぐれた耐チッピング性を発揮する被覆超硬工具に特徴を有するものである。
【００１０】
つぎに、この発明の被覆超硬工具において、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）Ｂ最高含有点の組成
Ｂ最高含有点の（Ｔａ，Ｂ）ＮにおけるＴａ成分は、強度の向上に寄与し、一方Ｂ成分は高温硬さおよび耐酸化性（高温特性）を向上させる作用をもち、したがってＢ成分の含有割合が高くなればなるほど高温特性は向上したものになるが、Ｂの割合を示すＸ値がＴａとの合量に占める割合（原子比）で０．６０を越えて高くなると、高強度を有するＢ最低含有点が隣接して存在しても層自体の強度の低下は避けられず、この結果チッピングなどが発生し易くなり、一方同Ｘ値が同０．４０未満では前記高温特性に所望の向上効果が得られないことから、Ｂ最高含有点でのＢ成分の割合を示すＸ値を０．４０〜０．６０と定めた。
【００１１】
（ｂ）Ｂ最低含有点の組成
上記の通りＢ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Ｂ最高含有点の強度不足を補う目的で、相対的にＴａ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Ｂ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Ｂの割合を示すＹ値がＴａとの合量に占める割合（原子比）で０．３０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、一方同Ｙ値が０．０５未満になると、相対的にＴａの割合が多くなり過ぎて、Ｂ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ず、この結果層の摩耗が促進するようになることから、Ｂ最低含有点でのＢの割合を示すＹ値を０．０５〜０．３０と定めた。
【００１２】
（ｃ）Ｂ最高含有点とＢ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高強度、さらに高温特性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Ｂ最高含有点であれば強度不足、Ｂ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、これが原因で重切削条件では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。
【００１３】
（ｄ）硬質被覆層の全体平均層厚
その層厚が０．５μｍ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１０μｍを越えると、チッピングが発生し易くなることから、その平均層厚を０．５〜１０μｍと定めた。
【００１４】
【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、ＶＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃｒ₃Ｃ₂粉末、およびＣｏ粉末を用意し、これら原料粉末を、表１に示される配合組成に配合し、ボールミルで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。
【００１５】
また、原料粉末として、いずれも０．５〜２μｍの平均粒径を有するＴｉＣＮ（重量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ₂Ｃ粉末、ＺｒＣ粉末、ＮｂＣ粉末、ＴａＣ粉末、ＷＣ粉末、Ｃｏ粉末、およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで２４時間湿式混合し、乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を２ｋＰａの窒素雰囲気中、温度：１５００℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０３のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１２０４０８のチップ形状をもったＴｉＣＮ系サーメット製の超硬基体Ｂ１〜Ｂ６を形成した。
【００１６】
ついで、上記の超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６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、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Ｂ最低含有点形成用Ｔａ−Ｂ合金、他方側のカソード電極（蒸発源）として、上記の従来（Ｔａ，Ｂ）Ｎ層形成に用いられたＴａ−Ｂ合金と同じ成分組成をもった種々のＢ最高含有点形成用Ｔａ−Ｂ合金を前記回転テーブルを挟んで対向配置し、またボンバート洗浄用金属Ｃｒも装着し、まず、装置内を排気して０．１Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、前記回転テーブル上で自転しながら回転する超硬基体に−１０００Ｖの直流バイアス電圧を印加し、カソード電極の前記金属Ｃｒとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＣｒボンバート洗浄し、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、前記回転テーブル上で自転しながら回転する超硬基体に−１００Ｖの直流バイアス電圧を印加し、かつ前記Ｂ最低含有点形成用Ｔａ−Ｂ合金からなるカソード電極とアノード電極との間には１００Ａの電流、前記Ｂ最高含有点形成用Ｔａ−Ｂ合金のカソード電極とアノード電極との間には１５０Ａの電流をそれぞれ流してアーク放電を発生させ、もって前記超硬基体の表面に、層厚方向に沿って表３，４に示される目標組成のＢ最低含有点とＢ最高含有点とが交互に同じく表３，４に示される目標間隔で繰り返し存在し、かつ前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量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）１〜１６をそれぞれ製造した。
【００１７】
また、比較の目的で、これら超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６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）として上記の従来（Ｔａ，Ｂ）Ｎ層形成に用いられたＴａ−Ｂ合金と同じ成分組成をもった種々のＴａ−Ｂ合金を装着し、さらにボンバート洗浄用金属Ｃｒも装着し、まず、装置内を排気して０．１Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、前記超硬基体に−１０００Ｖの直流バイアス電圧を印加し、カソード電極の前記金属Ｃｒとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＣｒボンバート洗浄し、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、超硬基体に−１００Ｖの直流バイアス電圧を印加し、前記カソード電極のＴａ−Ｂ合金とアノード電極との間に１５０Ａの電流を流してアーク放電を発生させ、もって前記超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６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（Ｔａ，Ｂ）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）１〜１６をそれぞれ製造した。
【００１８】
つぎに、上記本発明被覆超硬チップ１〜１６および従来被覆超硬チップ１〜１６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・ＳＣＭ４４０の丸棒、
切削速度：３３０ｍ／ｍｉｎ．、
切り込み：３．５ｍｍ、
送り：０．１５ｍｍ／ｒｅｖ．、
切削時間：６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・ＳＵＳ３０４の長さ方向等間隔４本縦溝入り丸棒、
切削速度：２５０ｍ／ｍｉｎ．、
切り込み：１．０ｍｍ、
送り：０．４ｍｍ／ｒｅｖ．、
切削時間：３分、
の条件でのステンレス鋼の乾式断続高速高送り切削加工試験、さらに、
被削材：ＪＩＳ・Ｓ１５Ｃ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：３．０ｍｍ、
送り：０．１ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での軟鋼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。この測定結果を表３〜６に示した。
【００１９】
【表１】

【００２０】
【表２】

【００２１】
【表３】

【００２２】
【表４】

【００２３】
【表５】

【００２４】
【表６】

【００２５】
（実施例２）
原料粉末として、平均粒径：５．５μｍを有する中粗粒ＷＣ粉末、同０．８μｍの微粒ＷＣ粉末、同１．３μｍのＴａＣ粉末、同１．２μｍのＮｂＣ粉末、同１．２μｍのＺｒＣ粉末、同２．３μｍのＣｒ₃Ｃ₂粉末、同１．５μｍのＶＣ粉末、同１．０μｍの（Ｔｉ，Ｗ）Ｃ［質量比で、ＴｉＣ／ＷＣ＝５０／５０］粉末、および同１．８μｍのＣｏ粉末を用意し、これら原料粉末をそれぞれ表７に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、１００ＭＰａの圧力で所定形状の各種の圧粉体にプレス成形し、これらの圧粉体を、６Ｐａの真空雰囲気中、７℃／分の昇温速度で１３７０〜１４７０℃の範囲内の所定の温度に昇温し、この温度に１時間保持後、炉冷の条件で焼結して、直径が８ｍｍ、１３ｍｍ、および２６ｍｍの３種の超硬基体形成用丸棒焼結体を形成し、さらに前記の３種の丸棒焼結体から、研削加工にて、表７に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法、並びにいずれもねじれ角：３０度の４枚刃スクエアの形状をもった超硬基体（エンドミル）Ｃ−１〜Ｃ−８をそれぞれ製造した。
【００２６】
ついで、これらの超硬基体（エンドミル）Ｃ−１〜Ｃ−８を、アセトン中で超音波洗浄し、乾燥した状態で、同じく図１に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、層厚方向に沿って表８に示される目標組成のＢ最高含有点とＢ最低含有点とが交互に同じく表８に示される目標間隔で繰り返し存在し、かつ前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量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８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、上記の超硬基体（エンドミル）Ｃ−１〜Ｃ−８を、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表９に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔａ，Ｂ）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：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・ＳＮＣＭ４３９の板材、
切削速度：２００ｍ／ｍｉｎ．、
溝深さ（切り込み）：８．０ｍｍ、
テーブル送り：１０００ｍｍ／分、
の条件での合金鋼の乾式高速高送り溝切削加工試験、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：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・ＳＫＤ１１の板材、
切削速度：２５０ｍ／ｍｉｎ．、
溝深さ（切り込み）：６．０ｍｍ、
テーブル送り：５００ｍｍ／分、
の条件での工具鋼の乾式高速高切り込み溝切削加工試験、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：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・Ｓ５０Ｃの板材、
切削速度：４００ｍ／ｍｉｎ．、
溝深さ（切り込み）：９．０ｍｍ、
テーブル送り：１５００ｍｍ／分、
の条件での炭素鋼の乾式高速高切り込みおよび高送り溝切削加工試験をそれぞれ行い、いずれの乾式溝切削加工試験でも切刃部の外周刃の逃げ面摩耗幅が使用寿命の目安とされる０．１ｍｍに至るまでの切削溝長を測定した。この測定結果を表８、９にそれぞれ示した。
【００２９】
【表７】

【００３０】
【表８】

【００３１】
【表９】

【００３２】
（実施例３）
上記の実施例２で製造した直径が８ｍｍ（超硬基体Ｃ−１〜Ｃ−３形成用）、１３ｍｍ（超硬基体Ｃ−４〜Ｃ−６形成用）、および２６ｍｍ（超硬基体Ｃ−７、Ｃ−８形成用）の３種の丸棒焼結体を用い、この３種の丸棒焼結体から、研削加工にて、溝形成部の直径×長さがそれぞれ４ｍｍ×１３ｍｍ（超硬基体Ｄ−１〜Ｄ−３）、８ｍｍ×２２ｍｍ（超硬基体Ｄ−４〜Ｄ−６）、および１６ｍｍ×４５ｍｍ（超硬基体Ｄ−７、Ｄ−８）の寸法、並びにいずれもねじれ角：３０度の２枚刃形状をもった超硬基体（ドリル）Ｄ−１〜Ｄ−８をそれぞれ製造した。
【００３３】
ついで、これらの超硬基体（ドリル）Ｄ−１〜Ｄ−８の切刃に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図１に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、層厚方向に沿って表１０に示される目標組成のＢ最高含有点とＢ最低含有点とが交互に同じく表１０に示される目標間隔で繰り返し存在し、かつ前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量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１０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、上記の超硬基体（ドリル）Ｄ−１〜Ｄ−８の切刃に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表１１に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔａ，Ｂ）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：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・ＳＫＤ６１の板材、
切削速度：４５ｍ／ｍｉｎ．、
送り：０．１８ｍｍ／ｒｅｖ、
穴深さ：８ｍｍ
の条件での工具鋼の湿式高速高送り穴あけ切削加工試験、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：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・ＦＣ４００の板材、
切削速度：１１０ｍ／ｍｉｎ．、
送り：０．３５ｍｍ／ｒｅｖ、
穴深さ：１６ｍｍ
の条件でのダクタイル鋳鉄の湿式高速高送り穴あけ切削加工試験、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：平面寸法が１００ｍｍ×２５０ｍｍ、厚さが５０ｍｍのＪＩＳ・ＦＣ３００の板材、
切削速度：１５０ｍ／ｍｉｎ．、
送り：０．４ｍｍ／ｒｅｖ、
穴深さ：３２ｍｍ
の条件での鋳鉄の湿式高速高送り穴あけ切削加工試験、をそれぞれ行い、いずれの湿式穴あけ切削加工試験（水溶性切削油使用）でも先端切刃面の逃げ面摩耗幅が０．３ｍｍに至るまでの穴あけ加工数を測定した。この測定結果を表１０、１１にそれぞれ示した。
【００３６】
【表１０】

【００３７】
【表１１】

【００３８】
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１〜１６、本発明被覆超硬エンドミル１〜８、および本発明被覆超硬ドリル１〜８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１〜１６、従来被覆超硬エンドミル１〜８、および従来被覆超硬ドリル１〜８を構成する硬質被覆層について、厚さ方向に沿ってオージェ分光分析装置を用いてＴａおよびＢの含有量を測定した。これらの測定結果から、前記本発明被覆超硬工具の硬質被覆層では、厚さ方向に沿って目標組成と実質的に同じ組成を有するＢ最高含有点とＢ最低含有点とが目標間隔と実質的に同じ間隔で交互に存在し、かつ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、さらに前記Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が連続的に変化する成分濃度分布構造をもつことも確認された。一方前記従来被覆超硬工具の硬質被覆層においては、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３〜１１に示される結果から、硬質被覆層が層厚方向に、すぐれた高温硬さと耐酸化性を有するＢ最高含有点と、高強度を有するＢ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Ｂ最高含有点から前記Ｂ最低含有点、前記Ｂ最低含有点から前記Ｂ最高含有点へＢ含有量が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超硬工具は、いずれも各種の鋼や鋳鉄などの切削加工を、高速で、かつ高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング性を発揮するのに対して、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（Ｔａ，Ｂ）Ｎ層からなる従来被覆超硬工具においては、前記硬質被覆層がすぐれた高温硬さと耐酸化性を有するものの、強度が不十分であるために、切刃部にチッピングが発生し、これが原因で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切削加工を、高速で、かつ高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、すぐれた耐チッピング性を発揮し、長期に亘ってすぐれた耐摩耗性を示すものであるから、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
In the present invention, the hard coating layer has excellent high-temperature strength, and excellent high-temperature hardness and oxidation resistance. Therefore, cutting of various steels and cast irons is performed at high speed and with high mechanical impact. The present invention relates to a surface-coated cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide tool) that exhibits excellent chipping resistance when a hard coating layer is used under heavy cutting conditions such as high cutting and high feed.
[0002]
[Prior art]
In general, coated carbide tools are used for slow-away inserts that are detachably attached to the tip of a cutting tool for drilling and cutting of various materials such as steel and cast iron, and for flat cutting. There are drills, miniature drills, solid type end mills used for chamfering, grooving, shoulder processing, etc. where the cutting blade takes an intermittent cutting form, and the solid type with the throwaway tip detachably attached 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 carbide tool, a substrate made of tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet (hereinafter collectively referred to as a carbide substrate). ), A composite nitride of Ta and B satisfying the composition formula: (Ta _1-X B _X ) N (wherein X is 0.40 to 0.60 in atomic ratio) [hereinafter, ( Coated carbide tools formed by physically vapor-depositing a hard coating layer composed of a layer represented by Ta, B) N] with an average layer thickness of 0.5 to 10 μm have been proposed. Since the layer has excellent high-temperature strength due to the Ta component, and excellent high-temperature hardness and oxidation resistance due to the B component, it was excellent even when continuous cutting and intermittent cutting of various steels and cast irons were performed under high-speed processing conditions. It is known to show cutting performance (for example, special See Permissible Literature 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 a Ta—B alloy having a predetermined composition is set, for example, under a current of 150 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 (Ta, B) N layer.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 06-041760 [0006]
[Problems to be solved by the invention]
In recent years, the performance of cutting devices has been dramatically improved, while there is a strong demand for labor saving and energy saving and further cost reduction for cutting. Accordingly, cutting is performed at high speed, with high cutting depth and high feed. However, in the conventional coated carbide tool described above, there is no problem when it is used under high-speed cutting conditions. However, high-speed cutting is highly problematic with high mechanical impact. When heavy cutting conditions such as cutting and high feed are used, chipping (microcracks) is likely to occur, especially due to insufficient high-temperature strength of the hard coating layer, and the service life is reached in a relatively short time. It is.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed the above-mentioned conventional coated carbide tool in order to develop a coated carbide tool that exhibits excellent chipping resistance with a hard coating layer particularly under high-speed heavy cutting conditions. As a result of conducting research focusing on the hard coating layer that composes
(A) The (Ta, B) N layer constituting the conventional coated carbide tool formed using the arc ion plating apparatus shown in FIG. 2 has a substantially uniform composition throughout the layer thickness. Therefore, it has a uniform high-temperature strength, and further has a high-temperature hardness and oxidation resistance. For example, arc ions having a structure shown in a schematic plan view in FIG. 1A and a schematic front view in FIG. A plating apparatus, that is, a rotating table for mounting a carbide substrate at the center of the apparatus, sandwiching the rotating table, Ta-B alloy having a relatively high B content on one side, and relatively containing B on the other side Using an arc ion plating apparatus in which a Ta-B alloy having a low amount is disposed as a cathode electrode (evaporation source) and facing the outer peripheral portion at a predetermined radial distance from the central axis on the rotary table of the apparatus. Multiple In this state, the hard substrate is mounted in a ring shape, and the rotary table is rotated with the atmosphere inside the apparatus as a nitrogen atmosphere, and the carbide substrate itself is rotated for the purpose of uniforming the thickness of the hard coating layer formed by vapor deposition. However, when an arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides to form a (Ta, B) N layer on the surface of the cemented carbide substrate, this result (Ta, B) In the N layer, the cemented carbide substrate arranged in a ring shape on the rotary table is closest to the cathode electrode (evaporation source) of the Ta-B alloy having a relatively high B content on one side. At this point, the highest B content point is formed in the layer, and when the cemented carbide substrate is closest to the cathode electrode of the Ta-B alloy having the relatively low B content on the other side, the lowest B content is present in the layer. Containing point is formed, the above rotating table In the layer, the B highest content point and the B lowest content point alternately appear at predetermined intervals in the layer thickness direction, and the B highest content point, the B lowest content point, and the B lowest content point To have a component concentration distribution structure in which the B content continuously changes from the B highest content point.
[0008]
(B) In the (Ta, B) N layer of the repeated continuous change component concentration distribution structure of (a) above, Ta-B having a relatively high B content, which is a cathode electrode (evaporation source) on one side facing each other. The B content in the alloy is set to the same B content as that of the Ta-B alloy used for forming the (Ta, B) N layer constituting the conventional coated carbide tool, and the cathode electrode (evaporation source) on the other side. ) In which the B content in the Ta-B alloy is relatively lower than the B content in the Ta-B alloy that is the one-side cathode electrode, and the rotation in which the carbide substrate is mounted. Control the rotation speed of the table,
The B highest content point is a composition formula: (Ta _1-X B _X ) N (wherein X is 0.40 to 0.60 in atomic ratio),
The B minimum content point is a composition formula: (Ta _1-Y B _Y ) N (however, Y is 0.05 to 0.30 in atomic ratio),
And the distance in the thickness direction of the adjacent B highest content point and B lowest content point adjacent to each other is 0.01 to 0.1 μm,
The B highest content point portion has a B content equivalent to that of the conventional (Ta, B) N layer, and therefore, is superior to the (Ta, B) N layer constituting the conventional hard coating layer. Shows high-temperature hardness and oxidation resistance, while the B minimum content point has a lower B content and a higher Ta content than the B highest content point, ensuring even higher high-temperature strength. In addition, since the distance between the highest B content point and the lowest B content point is made extremely small, it has excellent high temperature strength while maintaining excellent high temperature hardness and oxidation resistance as the characteristics of the entire layer. Therefore, coated carbide tools composed of (Ta, B) N layers with a hard coating layer are used for cutting various steels and cast irons at high speeds, especially with high mechanical impact, so high high-temperature strength Is required, high depth of cut and high feed What if you made in heavy cutting conditions also be like exhibits chipping resistance of the hard coating layer has excellent.
The research results shown in (a) and (b) above were obtained.
[0009]
The present invention has been made on the basis of the above research results. A hard coating layer composed of a (Ta, B) N layer is formed on the surface of a cemented carbide substrate with an overall average layer thickness of 0.5 to 10 μm. In coated carbide tools formed by vapor deposition,
In the hard coating layer, the B highest content point and the B lowest content point are alternately present at predetermined intervals along the layer thickness direction, and the B lowest content point, the B A component concentration distribution structure in which the B content continuously changes from the lowest content point to the B highest content point,
Furthermore, the B highest content point is
Composition formula: (Ta _1-X B _X ) N (wherein X is 0.40 to 0.60 in atomic ratio),
B minimum content point,
Composition formula: (Ta _1-Y B _Y ) N (however, in atomic ratio, Y represents 0.05 to 0.30),
And the interval between the B highest content point and the B lowest content point adjacent to each other is 0.01 to 0.1 μm.
It is characterized by a coated carbide tool that exhibits excellent chipping resistance under high-speed heavy cutting conditions.
[0010]
Next, in the coated carbide tool of the present invention, the reason why the structure of the hard coating layer constituting the tool is limited as described above will be described.
(A) Composition of the highest B content point The Ta component in (Ta, B) N at the highest B content point contributes to the improvement of strength, while the B component improves high temperature hardness and oxidation resistance (high temperature characteristics). Therefore, the higher the content ratio of the B component, the higher the high temperature characteristics. However, the X value indicating the ratio of B is 0.60 in terms of the total amount with Ta (atomic ratio). If it exceeds the upper limit, even if the lowest B content point having high strength is present adjacently, a decrease in the strength of the layer itself is unavoidable, and as a result, chipping or the like is likely to occur, while the X value is the same as that of 0.1. If it is less than 40, a desired improvement effect cannot be obtained in the high temperature characteristics. Therefore, the X value indicating the ratio of the B component at the B highest content point is set to 0.40 to 0.60.
[0011]
(B) Composition of the lowest B content point As described above, the highest B content point has excellent high-temperature characteristics, but on the other hand, it is inferior in strength. In particular, the Ta content ratio is high, and the lowest B content points that have high strength thereby intervene alternately in the thickness direction. Therefore, the Y value indicating the ratio of B occupies the total amount with Ta If the ratio (atomic ratio) exceeds 0.30, the desired excellent strength cannot be ensured. On the other hand, if the Y value is less than 0.05, the Ta ratio is relatively increased. Since the desired high temperature characteristic cannot be provided at the lowest B content point, and as a result, wear of the layer is promoted, the Y value indicating the ratio of B at the lowest B content point is 0.05 to 0. .30.
[0012]
(C) Interval between the highest B content point and the lowest B content point If the distance is less than 0.01 μm, it is difficult to clearly form each point with the above composition. As a result, the layer has a desired high strength, Further, it becomes impossible to secure high temperature characteristics, and when the distance exceeds 0.1 μm, each point has a defect, that is, if the B maximum content point is insufficient, the strength is insufficient, and if the B content is low, the high temperature characteristics are insufficient. It appears locally in the layer, and this makes it easier for chipping to occur on the cutting edge under heavy cutting conditions, or promotes the progress of wear, so the interval is set to 0.01 to 0.1 μm. It was.
[0013]
(D) Overall average layer thickness of hard coating layer If the layer thickness is less than 0.5 μm, desired wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 10 μm, chipping is likely to occur. Therefore, the average layer thickness was determined to be 0.5 to 10 μm.
[0014]
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, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder, all having an average particle diameter of 1 to 3 μm, were prepared. And then wet-mixed with a ball mill for 72 hours, dried, and press-molded into a green compact at a pressure of 100 MPa. The green compact was vacuumed at 6 Pa at a temperature of 1400 ° C. for 1 hour. Sintered under the holding conditions, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03, and the carbide bases A1 to A10 made of WC-based cemented carbide having ISO / CNMG120408 chip shape Formed.
[0015]
In addition, as raw material powders, all are TiCN (weight ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed into a compact at a pressure of 100 MPa. The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to obtain ISO standard / CNMG120408. TiCN-based cermet carbide substrates B1 to B6 having the following chip shape were formed.
[0016]
Next, each of the above-described carbide substrates A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, and then from the central axis on the rotary table in the arc ion plating apparatus shown in FIG. A Ta-B alloy for forming the lowest B content point having various components as a cathode electrode (evaporation source) on one side, mounted along a peripheral portion at a predetermined distance in the radial direction, and the cathode on the other side As the electrode (evaporation source), various B—highest content point forming Ta—B alloys having the same composition as the Ta—B alloy used for forming the conventional (Ta, B) N layer are used as the rotary table. The metal plate for bombard cleaning is also mounted, and the inside of the apparatus is first evacuated and kept at a vacuum of 0.1 Pa or less, and the apparatus is heated to 500 ° C. with a heater, and then the rotary table. Up A DC bias voltage of -1000 V is applied to the rotating carbide substrate rotating while rotating, and an arc discharge is generated by flowing a current of 100 A between the metal Cr of the cathode electrode and the anode electrode. After cleaning with Cr bombardment, nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 2 Pa, and a DC bias voltage of −100 V is applied to the carbide substrate rotating while rotating on the rotary table, In addition, a current of 100 A is present between the cathode electrode and the anode electrode made of the Ta-B alloy for forming the lowest B content point, and a current between the cathode electrode and the anode electrode of the Ta-B alloy for forming the highest B content point is between Each of the currents of 150 A was supplied to generate arc discharge, and thus the target composition shown in Tables 3 and 4 along the layer thickness direction was formed on the surface of the cemented carbide substrate. The lowest content point and the highest B content point are alternately repeated at the target intervals shown in Tables 3 and 4, and from the highest B content point to the lowest B content point, from the lowest B content point to the highest B content. By depositing a hard coating layer having a target total thickness shown in Tables 3 and 4 as a component concentration distribution structure in which the B content continuously changes to the point, Throwaway tips made of the surface-coated cemented carbide of the present invention (hereinafter referred to as the present coated cemented carbide tips) 1 to 16 were produced, respectively.
[0017]
Further, for the purpose of comparison, these carbide substrates A1 to A10 and B1 to B6 are ultrasonically cleaned in acetone and dried, and then loaded into a normal arc ion plating apparatus shown in FIG. In addition, various Ta—B alloys having the same composition as the Ta—B alloy used in the conventional (Ta, B) N layer formation as described above are mounted as cathode electrodes (evaporation sources), and bombard cleaning metal Cr First, the inside of the apparatus was evacuated and kept at a vacuum of 0.1 Pa or less, and the inside of the apparatus was heated to 500 ° C. with a heater, and then a −1000 V DC bias voltage was applied to the cemented carbide substrate, A current of 100 A is passed between the metal Cr of the cathode electrode and the anode electrode to generate an arc discharge, thereby cleaning the surface of the carbide substrate with Cr bombardment, and then nitrogen as a reaction gas in the apparatus. In addition, a reaction atmosphere of 2 Pa is introduced, a DC bias voltage of −100 V is applied to the carbide substrate, and a current of 150 A is passed between the Ta—B alloy of the cathode electrode and the anode electrode to cause arc discharge. Therefore, each of the surfaces of the cemented carbide substrates A1 to A10 and B1 to B6 has the target composition and the target layer thickness shown in Tables 5 and 6 and is substantially composed along the layer thickness direction. A conventional surface-coated cemented carbide throwaway tip (hereinafter referred to as a conventional coated carbide tip) 1 as a conventional coated carbide tool is deposited by vapor-depositing a hard coating layer consisting of an unaltered (Ta, B) N layer. ~ 16 were produced respectively.
[0018]
Next, with the present invention coated carbide tips 1-16 and conventional coated carbide tips 1-16, in a state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SCM440 round bar,
Cutting speed: 330 m / min. ,
Cutting depth: 3.5mm,
Feed: 0.15 mm / rev. ,
Cutting time: 6 minutes
Dry-type continuous high-speed high-cut cutting test of alloy steel under the conditions of
Work material: JIS / SUS304 lengthwise equidistant four round grooved round bars,
Cutting speed: 250 m / min. ,
Cutting depth: 1.0 mm,
Feed: 0.4 mm / rev. ,
Cutting time: 3 minutes
Stainless steel dry interrupted high-speed high-feed cutting test,
Work material: JIS / S15C lengthwise equal length 4 vertical grooved round bars,
Cutting speed: 300 m / min. ,
Cutting depth: 3.0 mm,
Feed: 0.1 mm / rev. ,
Cutting time: 5 minutes
The dry interrupted high-speed, high-cut cutting test of mild 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 Tables 3-6.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
[Table 3]

[0022]
[Table 4]

[0023]
[Table 5]

[0024]
[Table 6]

[0025]
(Example 2)
As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, ZrC of 1.2 μm Powder, 2.3 μm Cr ₃ C ₂ powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C [by mass ratio, TiC / WC = 50/50] powder, and 1 Prepare 8 .mu.m Co powder, mix these raw material powders with the composition shown in Table 7, add wax, ball mill in acetone for 24 hours, dry under reduced pressure, and then press at a pressure of 100 MPa. The green compacts were press-molded, and 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 6 Pa vacuum atmosphere. After holding at temperature for 1 hour, sintering under furnace cooling conditions Three types of sintered carbide rod forming bodies for forming a carbide substrate having diameters of 8 mm, 13 mm, and 26 mm were formed, and further, the three types of round rod sintered bodies described above were subjected to grinding and shown in Table 7. In combination, a carbide substrate having a shape of a 4-flute square with a cutting blade portion diameter × length of 6 mm × 13 mm, 10 mm × 22 mm, and 20 mm × 45 mm, respectively, and a twist angle of 30 degrees ( End mill) C-1 to C-8 were produced.
[0026]
Then, these carbide substrates (end mills) C-1 to C-8 were ultrasonically washed 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 B content point and the lowest B content point of the target composition shown in Table 8 along the layer thickness direction are alternately present at the same target interval shown in Table 8, and A target total layer having a component concentration distribution structure in which the B content continuously changes from the highest B content point to the lowest B content point, from the lowest B content point to the highest B content point, and also shown in Table 8 By vapor-depositing a hard coating layer having a thickness, end mills made of the surface coated cemented carbide of the present invention (hereinafter referred to as the present coated carbide end mill) 1 to 8 as the coated carbide tool of the present invention were produced.
[0027]
For the purpose of comparison, the above-mentioned carbide substrates (end mills) C-1 to C-8 are ultrasonically cleaned in acetone and dried, and the ordinary arc ion plating apparatus shown in FIG. 2 is also used. (Ta, B) N having the target composition and target layer thickness shown in Table 9 and substantially no composition change along the layer thickness direction under the same conditions as in Example 1 above. By vapor-depositing a hard coating layer consisting of layers, conventional surface-coated cemented carbide end mills (hereinafter referred to as conventional coated carbide end mills) 1 to 8 as conventional coated carbide tools 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: JIS / SNCM439 plate material having a plane dimension of 100 mm × 250 mm and a thickness of 50 mm,
Cutting speed: 200 m / min. ,
Groove depth (cut): 8.0 mm,
Table feed: 1000 mm / min,
With respect to the dry high-speed high-feed groove cutting test of alloy steel under the conditions of the present invention, the coated carbide end mills 4 to 6 of the present invention and the conventional coated carbide end mills 4 to 6 are as follows:
Work material: JIS / SKD11 plate material having a plane dimension of 100 mm × 250 mm and a thickness of 50 mm,
Cutting speed: 250 m / min. ,
Groove depth (cut): 6.0 mm,
Table feed: 500 mm / min,
With respect to the dry high-speed and high-grooving groove cutting test of the tool steel under the following conditions, the coated carbide end mills 7 and 8 of the present invention and the conventional coated carbide end mills 7 and 8:
Work material: JIS / S50C plate material having a plane dimension of 100 mm × 250 mm and a thickness of 50 mm,
Cutting speed: 400 m / min. ,
Groove depth (cut): 9.0 mm,
Table feed: 1500mm / min,
Carbon steel dry high-speed high-cut and high-feed grooving cutting tests were performed under the conditions described above, and the flank wear width of the outer peripheral edge of the cutting edge is used as a guide for the service life in any dry grooving test. The cutting groove length up to 1 mm was measured. The measurement results are shown in Tables 8 and 9, respectively.
[0029]
[Table 7]

[0030]
[Table 8]

[0031]
[Table 9]

[0032]
(Example 3)
The diameters produced in Example 2 above were 8 mm (for forming carbide substrates C-1 to C-3), 13 mm (for forming carbide substrates C-4 to C-6), and 26 mm (for carbide substrates C-). 7, for C-8 formation), from these three types of round bar sintered bodies, the diameter x length of the groove forming portion is 4 mm x 13 mm (by grinding), respectively. Carbide substrates D-1 to D-3), 8 mm × 22 mm (Carbide substrates D-4 to D-6), and 16 mm × 45 mm (Carbide substrates D-7 and D-8), and all Carbide substrates (drills) D-1 to D-8 having a two-blade shape with a twist angle of 30 degrees were produced.
[0033]
Next, the cutting edges of these carbide substrates (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone and dried, and the arc ion plating apparatus shown in FIG. 1 is also used. In the same conditions as in Example 1 above, the target spacing shown in Table 10 in which the highest B content point and the lowest B content point of the target composition shown in Table 10 along the layer thickness direction are alternately shown in Table 10 And a component concentration distribution structure in which the B content continuously changes from the B highest content point to the B lowest content point, from the B lowest content point to the B highest content point, and By depositing a hard coating layer having a target overall layer thickness shown in FIG. 10, drills made of the surface coated cemented carbide of the present invention (hereinafter referred to as the present coated carbide drill) 1-8 as the coated carbide tool of the present invention. Were manufactured respectively.
[0034]
For comparison purposes, the cutting edges of the above-mentioned carbide substrates (drills) D-1 to D-8 are honed, ultrasonically cleaned in acetone, and dried, as shown in FIG. The sample was charged into a normal arc ion plating apparatus, had the target composition and target layer thickness shown in Table 11 under the same conditions as in Example 1, and substantially changed in composition along the layer thickness direction. By vapor-depositing a hard coating layer comprising no (Ta, B) N layer, conventional surface-coated cemented carbide drills (hereinafter referred to as conventional coated carbide drills) 1 to 8 as conventional coated carbide tools are respectively provided. 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: JIS / SKD61 plate material having a plane dimension of 100 mm × 250 mm and a thickness of 50 mm,
Cutting speed: 45 m / min. ,
Feed: 0.18mm / 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: JIS / FC400 plate material with a planar dimension of 100 mm × 250 mm and a thickness of 50 mm,
Cutting speed: 110 m / min. ,
Feed: 0.35mm / rev,
Hole depth: 16mm
For the ductile cast iron wet high-speed high-feed drilling test 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: JIS / FC300 plate material with a plane dimension of 100 mm × 250 mm and a thickness of 50 mm,
Cutting speed: 150 m / min. ,
Feed: 0.4mm / rev,
Hole depth: 32mm
We performed a high-speed, high-feed, high-feed drilling test of cast iron under the above conditions, and in any wet drilling test (using water-soluble cutting oil), the flank wear width of the tip cutting edge surface reached 0.3 mm The number of holes drilled was measured. The measurement results are shown in Tables 10 and 11, respectively.
[0036]
[Table 10]

[0037]
[Table 11]

[0038]
Hard coating layers constituting the present coated carbide tips 1-16, the present coated carbide end mills 1-8, and the present coated carbide drills 1-8 as the present coated carbide tool obtained as a result, In addition, the conventional coated carbide tips 1 to 16 as the conventional coated carbide tool, the conventional coated carbide end mills 1 to 8 and the hard coating layer constituting the conventional coated carbide drills 1 to 8 are Auger along the thickness direction. The contents of Ta and B were measured using a spectroscopic analyzer. From these measurement results, in the hard coating layer of the coated carbide tool of the present invention, the B highest content point and B lowest content point having substantially the same composition as the target composition along the thickness direction are substantially equal to the target interval. Are present alternately at the same intervals, and the overall average layer thickness of the hard coating layer also shows substantially the same value as the target overall layer thickness, and further, from the B highest content point to the B lowest content point, the B lowest content It was also confirmed that it has a component concentration distribution structure in which the B content continuously changes from the point to the B highest content point. On the other hand, in the hard coating layer of the conventional coated carbide tool, no composition change is observed along the thickness direction, and the composition is substantially the same as the target composition and the overall average layer thickness is substantially the same as the target overall layer thickness. It was confirmed that
[0039]
【The invention's effect】
From the results shown in Tables 3 to 11, the hard coating layer has a predetermined interval alternately between the highest B content point having excellent high temperature hardness and oxidation resistance and the lowest B content point having high strength in the layer thickness direction. And the present invention has a component concentration distribution structure in which the B content continuously changes from the highest B content point to the lowest B content point and from the lowest B content point to the highest B content point. All hard tools have excellent hard coating layers even when cutting various steels and cast irons at high speeds and under heavy cutting conditions such as high cutting and high feed with high mechanical impact. In a conventional coated carbide tool composed of a (Ta, B) N layer that exhibits a chipping resistance while the hard coating layer has substantially no composition change along the layer thickness direction, the hard coating layer includes Although it has excellent high temperature hardness and oxidation resistance, For degree is insufficient, chipping occurs in the cutting edge, which is clear may result in a relatively short time service life due.
As described above, the coated cemented carbide tool of the present invention, particularly when cutting various steels and cast irons, is performed at high speed and under heavy cutting conditions such as high cutting and high feed with high mechanical impact. In addition, it exhibits excellent chipping resistance and exhibits excellent wear resistance over a long period of time, so it can fully satisfy the labor saving and energy saving of cutting work, and further 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

Surface coating formed by physical vapor deposition of a hard coating layer made of a composite nitride layer of Ta and B on the surface of a tungsten carbide base cemented carbide substrate or a titanium carbonitride cermet substrate with an overall average layer thickness of 0.5 to 10 μm. In cemented carbide cutting tools,
In the hard coating layer, the B highest content point and the B lowest content point are alternately present at predetermined intervals along the layer thickness direction, and the B lowest content point, the B A component concentration distribution structure in which the B content continuously changes from the lowest content point to the B highest content point,
Furthermore, the B highest content point is
Composition formula: (Ta _1-X B _X ) N (wherein X is 0.40 to 0.60 in atomic ratio),
B minimum content point,
Composition formula: (Ta _1-Y B _Y ) N (however, in atomic ratio, Y represents 0.05 to 0.30),
And the interval between the B highest content point and the B lowest content point adjacent to each other is 0.01 to 0.1 μm,
A surface-coated cemented carbide cutting tool that exhibits excellent chipping resistance under high-speed heavy cutting conditions.