JP2004314188A

JP2004314188A - Surface coated cemented carbide cutting tool having hard coated layer exhibiting excellent chipping resistance under heavy cutting processing conditions

Info

Publication number: JP2004314188A
Application number: JP2003107363A
Authority: JP
Inventors: Kazuki Okada; 一樹岡田; Shinsuke Sakamoto; 信介坂本
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2003-04-11
Filing date: 2003-04-11
Publication date: 2004-11-11

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cemented carbide cutting tool having a hard coated layer exhibiting excellent chipping resistance under heavy cutting processing conditions. <P>SOLUTION: In the surface coated cemented carbide cutting tool, the hard coated layer with an average layer thickness of 1 to 15 μm satisfying (a) to (d) is physically deposited on a surface of a cemented carbide body. (a) The hard covering layer has a two-phase structure in which Co is dispersed and distributed into a base of composite nitride of Al and Ti. (b) The base of composite nitride of Al and Ti satisfies a composition formula: (Al<SB>1-X</SB>Ti<SB>X</SB>)N (where X is 0.35-0.60 by atomic ratio). (c) The layer has a Co component concentration distribution variation structure in which the Co highest ratio dispersion point and a Co absence point alternatively and repeatedly exist at predetermined intervals along the thickness direction and the dispersion ratio of Co is continuously increased and decreased from the Co highest ratio dispersion point to the Co absence point and from the Co absence point to the Co highest ratio dispersion point. (d) The interval between the adjoining Co highest ratio dispersion point and Co absence point is 0.01 to 0.1 μm, and the Co dispersion ratio at the Co highest ratio dispersion point is 1 to 10 at.% as the ratio occupied in the total amount with the base. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層が高靭性を有し、かつ高温硬さと耐熱性にもすぐれ、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：（Ａｌ_１−ＸＴｉ_Ｘ）Ｎ（ただし、原子比で、Ｘは０．３５〜０．６０を示す）を満足するＡｌとＴｉの複合窒化物［以下、（Ａｌ，Ｔｉ）Ｎで示す］層からなる硬質被覆層を１〜１５μｍ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、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ている（例えば参考文献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合金ターゲット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（例えば参考文献１参照）。
【０００５】
【参考文献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、これを通常の切削加工条件で用いた場合には問題はないが、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、特に硬質被覆層の靭性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）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、両側に、いずれもカソード電極（蒸発源）として、所定の組成を有するＡｌ−Ｔｉ合金ターゲットを対向配置すると共に、いずれか一方側の前記Ａｌ−Ｔｉ合金ターゲットに金属Ｃｏターゲットを並設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に中心軸から半径方向に所定位置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、前記両側のＡｌ−Ｔｉ合金ターゲットからＡｌおよびＴｉ成分、さらに一方側の前記Ａｌ−Ｔｉ合金ターゲットに並設した前記金属ＣｏターゲットからＣｏ成分をそれぞれ雰囲気中にイオン化放出すると、ＡｌおよびＴｉ成分は反応雰囲気の窒素と反応して窒化物を形成するが、Ｃｏは雰囲気窒素とは反応しないままの状態を保持するので、前記超硬基体の表面には、（Ａｌ，Ｔｉ）Ｎの素地にＣｏが分散分布してなる２相組織［以下、（Ａｌ，Ｔｉ）Ｎ−Ｃｏで示す］層が形成されるようになり、この結果の（Ａｌ，Ｔｉ）Ｎ−Ｃｏ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金属Ｃｏターゲットを並設していないＡｌ−Ｔｉ合金ターゲットのカソード電極（蒸発源）に最も接近した時点で、Ｃｏが存在せず、（Ａｌ，Ｔｉ）Ｎだけからなる素地が形成され、また前記超硬基体が上記の他方側のＡｌ−Ｔｉ合金ターゲットおよび金属Ｃｏターゲットのカソード電極に最も接近した時点で、（Ａｌ，Ｔｉ）Ｎの素地にＣｏ最高割合分散点が存在するようになり、さらに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Ｃｏ不存在点と前記Ｃｏ最高割合分散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Ｃｏ最高割合分散点から前記Ｃｏ不存在点、前記Ｃｏ不存在点から前記Ｃｏ最高割合分散点へＣｏの分散割合が連続的に増減するＣｏ成分濃度分布変化構造をもつようになること。
【０００８】
（ｂ）上記（ａ）のＣｏ成分濃度分布変化構造を有する（Ａｌ，Ｔｉ）Ｎ−Ｃｏ層において、対向配置のカソード電極（蒸発源）であるＡｌ−Ｔｉ合金ターゲットにおけるＴｉ含有量を上記の従来Ａｌ−Ｔｉ合金ターゲットのＴｉ含有量に相当するものとし、かつ上記の通り前記金属Ｃｏターゲットをいずれか一方側の前記Ａｌ−Ｔｉ合金ターゲットに並設すると共に、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、
上記素地を、組成式：（Ｔｉ_１−ＸＡｌ_Ｘ）Ｎ（ただし、原子比で、Ｘは０．３５〜０．６０を示す）、
を満足し、さらに前記Ｃｏ最高割合分散点のＣｏの分散割合を、素地との合量に占める割合で１〜１０原子％とし、
かつ隣り合う上記Ｃｏ最高割合分散点とＣｏ不存在点の厚さ方向の間隔を０．０１〜０．１μｍとすると、
上記のＣｏ不存在点では、上記の従来（Ａｌ，Ｔｉ）Ｎ層と同等のＡｌ含有割合となることから、前記従来（Ａｌ，Ｔｉ）Ｎ層と同等のすぐれた高温硬さと耐熱性（高温特性）を示し、一方上記のＣｏ最高割合分散点では、高分散割合のＣｏ成分によって一段と高い靭性が確保され、かつこれらＣｏ最高割合分散点とＣｏ不存在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特性を保持した状態で一段と高い靭性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（Ａｌ，Ｔｉ）Ｎ−Ｃｏ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、特に高い機械的衝撃を伴うので高靭性が要求される、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、
（ａ）上記（Ａｌ，Ｔｉ）Ｎ−Ｃｏからなり、
（ｂ）上記（Ａｌ，Ｔｉ）Ｎの素地が、組成式：（Ａｌ_１−ＸＴｉ_Ｘ）Ｎ（ただし、原子比で、Ｘは０．３５〜０．６０を示す）、を満足し、
（ｃ）厚さ方向にそって、Ｃｏ最高割合分散点とＣｏ不存在点とが所定間隔をおいて交互に繰り返し存在し、さらに前記Ｃｏ最高割合分散点から前記Ｃｏ不存在点、前記Ｃｏ不存在点から前記Ｃｏ最高割合分散点へＣｏの分散割合が連続的に増減するＣｏ成分濃度分布変化構造を有し、
（ｄ）かつ隣り合う上記Ｃｏ最高割合分散点とＣｏ不存在点の間隔が、０．０１〜０．１μｍにして、前記Ｃｏ最高割合分散点におけるＣｏ分散割合が素地との合量に占める割合で１〜１０原子％である、
上記（ａ）〜（ｄ）を満足する硬質被覆層を１〜１５μｍの平均層厚で物理蒸着してなる、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）素地の組成
素地の（Ａｌ，Ｔｉ）ＮにおけるＡｌ成分は、高温硬さおよび耐熱性（高温特性）を向上させ、同Ｔｉ成分は強度を向上させる目的で含有するものであり、したがって、Ｔｉの割合を示すＸ値がＡｌとの合量に占める割合（原子比）で０．３５未満では、素地に所望の強度を確保することができず、一方同Ｘ値が同０．６０を越えると、前記高温特性が急激に低下するようになり、いずれの場合も素地にすぐれた高温特性と強度の両方を具備させることができなくなることから、素地を構成する（Ａｌ，Ｔｉ）ＮにおけるＴｉの割合を示すＸ値を０．３５〜０．６０と定めた。
【００１１】
（ｂ）Ｃｏ最高割合分散点におけるＣｏの分散割合
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加工条件では、硬質被覆層により一段と高い靭性が要求されることから、素地にＣｏ最高割合分散点を層厚方向に沿って周期的に存在させることにより、靭性の一段の向上を図ったものであり、したがって、Ｃｏの分散割合が素地の（Ａｌ，Ｔｉ）Ｎとの合量に占める割合で１原子％未満では所望の靭性向上効果が得られず、一方、同分散割合が同１０原子％を超えると、硬質被覆層全体の高温特性が急激に低下し、摩耗進行が著しく促進されるようになることから、その分布割合を１〜１０原子％と定めた。
【００１２】
（ｃ）Ｃｏ最高割合分散点とＣｏ不存在点間の間隔
その間隔が０．０１μｍ未満ではそれぞれの点を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靭性、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Ｃｏ最高割合分散点であれば高温特性不足、Ｃｏ不存在点であれば靭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。
【００１３】
（ｄ）硬質被覆層の平均層厚
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、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。
【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、Ｃｒ_３Ｃ_２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、Ｍｏ_２Ｃ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に、中心軸から半径方向に所定位置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Ａｌ−Ｔｉ合金ターゲットおよび金属Ｃｏターゲット、同他方側のカソード電極（蒸発源）として、前記Ａｌ−Ｔｉ合金ターゲットと同じ成分組成をもったＡｌ−Ｔｉ合金ターゲット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Ｔｉターゲットも装着し、まず、装置内を排気して０．５Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、前記回転テーブル上で自転しながら回転する超硬基体に−１０００Ｖの直流バイアス電圧を印加し、カソード電極の前記金属Ｔｉターゲットとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＴｉボンバート洗浄し、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、前記両側のＡｌ−Ｔｉ合金ターゲットのカソード電極とアノード電極との間には１５０Ａの電流、そして前記金属Ｃｏターゲットとアノード電極との間にはＣｏ最高割合分散点のＣｏ割合に応じて５０〜８０Ａの範囲内の所定の電流を流してアーク放電を発生させ、もって前記超硬基体の表面に、表３，４に示される目標組成の素地に、層厚方向に沿ってＣｏ最高割合分散点とＣｏ不存在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Ｃｏ最高割合分散点から前記Ｃｏ不存在点、前記Ｃｏ不存在点から前記Ｃｏ最高割合分散点へ、Ｃｏの分散割合が連続的に増減するＣｏ成分濃度分布変化構造を有し、かつ同じく表３，４に示される目標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）として種々の成分組成をもったＡｌ−Ｔｉ合金ターゲットを装着し、さらにボンバート洗浄用金属Ｔｉターゲットも装着し、まず、装置内を排気して０．５Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、前記超硬基体に−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Ｔｉターゲットとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＴｉボンバート洗浄し、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Ａｌ−Ｔｉ合金ターゲットとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって前記超硬基体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、かつ層中にＣｏの分散分布がなく、実質的に（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）１〜１６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：１６０ｍ／ｍｉｎ．、
切り込み：５ｍｍ、
送り：０．２ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件（通常の切り込み量は１．５ｍｍ）での合金鋼の乾式連続高切り込み切削加工試験、
被削材：ＪＩＳ・Ｓ５０Ｃの長さ方向等間隔４本縦溝入り丸棒、
切削速度：１６０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．６ｍｍ／ｒｅｖ．、
切削時間：１０分、
の条件（通常の送り量は０．２ｍｍ／ｒｅｖ．）での炭素鋼の乾式断続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：１６０ｍ／ｍｉｎ．、
切り込み：５ｍｍ、
送り：０．２ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件（通常の切り込み量は１．５ｍｍ）での鋳鉄の乾式断続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Ｃｒ_３Ｃ_２粉末、同１．５μｍのＶＣ粉末、同１．０μｍの（Ｔｉ，Ｗ）Ｃ粉末、および同１．８μｍのＣｏ粉末を用意し、これら原料粉末をそれぞれ表７に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、１００ＭＰａの圧力で所定形状の各種の圧粉体にプレス成形し、これらの圧粉体を、６Ｐａの真空雰囲気中、７℃／分の昇温速度で１３７０〜１４７０℃の範囲内の所定の温度に昇温し、この温度に１時間保持後、炉冷の条件で焼結して、直径が８ｍｍ、１３ｍｍ、および２６ｍｍの３種の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】
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、表８に示される目標組成の素地に、層厚方向に沿ってＣｏ最高割合分散点とＣｏ不存在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Ｃｏ最高割合分散点から前記Ｃｏ不存在点、前記Ｃｏ不存在点から前記Ｃｏ最高割合分散点へ、Ｃｏの分散割合が連続的に増減するＣｏ成分濃度分布変化構造を有し、さらに同じく表８に示される目標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、かつ層中にＣｏの分散分布がなく、実質的に（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：７０ｍ／ｍｉｎ．、
軸方向切り込み：１０ｍｍ、
径方向切り込み：２．７ｍｍ、
テーブル送り：４２０ｍｍ／分、
の条件（通常の軸方向切り込み量は６ｍｍ、径方向切り込み量は０．９ｍｍ）での工具鋼の乾式高切り込み側面切削加工試験、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：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ５０Ｃの板材、
切削速度：１００ｍ／ｍｉｎ．、
軸方向切り込み：１５ｍｍ、
径方向切り込み：１．５ｍｍ、
テーブル送り：１２８０ｍｍ／分、
の条件（通常のテーブル送りは４００ｍｍ／分）での炭素鋼の乾式高送り側面切削加工試験、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：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＵＳ３１６の板材、
切削速度：５０ｍ／ｍｉｎ．、
軸方向切り込み：３０ｍｍ、
径方向切り込み：７ｍｍ、
テーブル送り：１２０ｍｍ／分、
の条件（通常の軸方向切り込み量は２０ｍｍ、径方向切り込み量は３ｍｍ）でのステンレス鋼の湿式高切り込み側面切削加工試験（水溶性切削油使用）をそれぞれ行い、いずれの側面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】
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、表１０に示される目標組成の素地に、層厚方向に沿ってＣｏ最高割合分散点とＣｏ不存在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Ｃｏ最高割合分散点から前記Ｃｏ不存在点、前記Ｃｏ不存在点から前記Ｃｏ最高割合分散点へ、Ｃｏの分散割合が連続的に増減するＣｏ成分濃度分布変化構造を有し、さらに同じく表１０に示される目標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、かつ層中にＣｏの分散分布がなく、実質的に（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・ＳＣＭ４４０の板材、
切削速度：６０ｍ／ｍｉｎ．、
送り：０．２５ｍｍ／ｒｅｖ、
穴深さ：１０ｍｍ
の条件（通常の送り量は０．０８ｍｍ／ｒｅｖ、）での合金鋼の湿式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：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ４５Ｃの板材、
切削速度：８０ｍ／ｍｉｎ．、
送り：０．４ｍｍ／ｒｅｖ、
穴深さ：２０ｍｍ
の条件（通常の送り量は０．１２ｍｍ／ｒｅｖ、）での炭素鋼の湿式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：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＦＣＤ７００の板材、
切削速度：７５ｍ／ｍｉｎ．、
送り：０．６ｍｍ／ｒｅｖ、
穴深さ：４０ｍｍ
の条件（通常の送り量は０．２ｍｍ／ｒｅｖ、）でのダクタイル鋳鉄の湿式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における素地の組成およびＣｏ最高割合分散点のＣｏ分散割合、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の硬質被覆層の組成について、厚さ方向に沿ってＴｉおよびＡｌの含有割合、さらにＣｏ分散割合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、目標値と実質的に同じ組成の素地に、Ｃｏ最高割合分散点とＣｏ不存在点とが目標値と実質的に同じ間隔で交互に繰り返し存在し、かつ前記Ｃｏ最高割合分散点から前記Ｃｏ不存在点、前記Ｃｏ不存在点から前記Ｃｏ最高割合分散点へ、Ｃｏの分散割合が連続的に増減するＣｏ成分濃度分布変化構造を有することが確認され、また硬質被覆層の平均層厚も目標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、目標組成と実質的に同じ組成および目標層厚と実質的に同じ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、層厚方向に沿ってＣｏ最高割合分散点とＣｏ不存在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Ｃｏ最高割合分散点から前記Ｃｏ不存在点、前記Ｃｏ不存在点から前記Ｃｏ最高割合分散点へ、Ｃｏの分散割合が連続的に増減するＣｏ成分濃度分布変化構造を有する本発明被覆超硬工具は、硬質被覆層が前記Ｃｏ最高割合分散点によって高靭性、前記Ｃｏ不存在点によってすぐれた高温硬さと耐熱性のいずれの特性をも具備するようになることから、いずれも各種の鋼や鋳鉄などの切削加工を、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も、硬質被覆層が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のに対して、硬質被覆層が（Ａｌ，Ｔｉ）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熱性を有するものの、靭性に劣るものであるために、重切削条件での加工では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、通常の条件での切削加工は勿論のこと、特に各種の鋼や鋳鉄などの切削加工を、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]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a hard coating layer having high toughness, and excellent in high-temperature hardness and heat resistance. Therefore, in particular, cutting of various kinds of steel and cast iron can be performed at high cutting depth and high feed 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) in which a hard coating layer exhibits excellent chipping resistance when performed under heavy cutting conditions.
[0002]
[Prior art]
In general, coated carbide tools are used for throw-away inserts, drilling, etc., which are removably attached to the tip of a cutting tool for turning or planing of various materials such as steel and cast iron. Drills and miniature drills, as well as solid-type end mills used for face milling, grooving, shoulder processing, etc., in which the cutting edge takes an intermittent cutting form, and the solid-type by detachably attaching the throw-away tip There is known a throw-away end mill tool for performing a cutting process in the same manner as the end mill.
[0003]
Further, as a coated cemented 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, these are collectively referred to as a cemented carbide substrate) ), A composite nitride of Al and Ti satisfying the composition formula: (Al _1-X Ti _X ) N (where X represents 0.35 to 0.60 in atomic ratio) [hereinafter, ( Al, Ti) N], a coated hard carbide layer formed by physical vapor deposition of a hard coating layer having an average thickness of 1 to 15 μm has been proposed, and is used for continuous cutting and intermittent cutting of various steels and cast irons. (For example, see Reference Document 1).
[0004]
Furthermore, the above-mentioned coated carbide tool is charged with the above-mentioned carbide substrate in an arc ion plating apparatus, which is a kind of physical vapor deposition apparatus shown schematically in FIG. 2, for example, and the inside of the apparatus is heated by a heater. For example, an arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) on which an Al-Ti alloy target having a predetermined composition is set, for example, under a condition of a current of 90 A while being heated to a temperature of 500 ° C. At the same time, a nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of, for example, 2 Pa. On the other hand, the surface of the cemented carbide substrate is applied to the cemented carbide substrate under the condition that a bias voltage of, for example, -100 V is applied. In addition, it is also known that it is manufactured by evaporating a hard coating layer composed of the above (Al, Ti) N layer (for example, see Reference Document 1).
[0005]
[Reference 1]
Patent No. 2644710 [0006]
[Problems to be solved by the invention]
In recent years, the performance of cutting equipment has been remarkably improved.On the other hand, there is a strong demand for labor saving, energy saving, and lower cost for cutting, and with this, cutting has been performed under heavy cutting conditions such as high cutting depth and high feed. Although there is no problem in the conventional coated carbide tool described above when using it under normal cutting conditions, there is no problem with cutting, but high cutting depth and high feed with high mechanical impact Under the heavy cutting conditions described above, chipping (micro cracking) is liable to occur particularly due to insufficient toughness of the hard coating layer, and at present, the service life is reached in a relatively short time.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed the above-mentioned conventional coated carbide tool in order to develop a coated carbide tool in which the hard coating layer exhibits excellent chipping resistance especially under heavy cutting conditions. As a result of conducting research, focusing on the constituent hard coating layer,
(A) For example, an arc ion plating apparatus having a structure shown in a schematic plan view in FIG. 1A and a schematic front view in FIG. On both sides of the rotary table, Al-Ti alloy targets each having a predetermined composition are opposed to each other as cathode electrodes (evaporation sources), and a metal Co target is placed on one of the Al-Ti alloy targets. A plurality of carbide substrates are mounted in a ring shape along the outer peripheral portion at a position radially away from the central axis at a predetermined position on the turntable of the device by using an arc ion plating apparatus in which In this state, the rotary table is rotated while the atmosphere in the apparatus is set to a nitrogen atmosphere, and the carbide substrate itself is also used for the purpose of making the thickness of the hard coating layer formed by vapor deposition uniform. In the process, an arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides, and Al and Ti components from the Al-Ti alloy targets on both sides, and the Al-Ti alloy on one side. When the Co component is ionized and released into the atmosphere from the metal Co target arranged in parallel with the target, the Al and Ti components react with nitrogen in the reaction atmosphere to form a nitride, but Co remains unreacted with the atmosphere nitrogen. Is maintained on the surface of the cemented carbide substrate, and a two-phase structure [hereinafter, indicated by (Al, Ti) N-Co] layer in which Co is dispersed and distributed on the base material of (Al, Ti) N Are formed, and in the (Al, Ti) N—Co layer as a result, the super-hard substrate arranged in a ring shape on the turntable is made of the metal Co target on one side. At the point of closest approach to the cathode electrode (evaporation source) of an Al—Ti alloy target with no juxtaposition, a substrate consisting of only (Al, Ti) N without Co was formed, and When the substrate comes closest to the cathode electrode of the Al-Ti alloy target and the metal Co target on the other side, a Co highest ratio dispersion point exists in the (Al, Ti) N substrate, and the rotation The rotation of the table causes the Co non-existence points and the Co maximum ratio dispersion points to alternately appear at predetermined intervals along the layer thickness direction in the layer, and the Co non-existence points from the Co maximum ratio dispersion points to the Co non-existence points. A Co component concentration distribution change structure in which the Co dispersion ratio continuously increases and decreases from the Co non-existing point to the Co highest ratio dispersion point.
[0008]
(B) In the (Al, Ti) N—Co layer having the Co component concentration distribution changing structure of (a), the Ti content in the Al—Ti alloy target, which is the cathode electrode (evaporation source) disposed opposite to the above, is set to the above value. Conventionally, the metal Co target is assumed to correspond to the Ti content of the Al-Ti alloy target, and as described above, the metal Co target is juxtaposed with the Al-Ti alloy target on one side, and a super-hard substrate is mounted. By controlling the rotation speed of the turntable,
A composition formula: (Ti _1-X Al _X ) N (where X represents 0.35 to 0.60 in atomic ratio),
Is satisfied, and the Co dispersion ratio at the Co highest ratio dispersion point is set to 1 to 10 atomic% as a ratio to the total amount with the base material,
And when the interval in the thickness direction between the adjacent Co highest ratio dispersion point and the Co non-existing point is 0.01 to 0.1 μm,
At the above-mentioned Co-free point, since the Al content ratio is the same as that of the conventional (Al, Ti) N layer, excellent high-temperature hardness and heat resistance (high temperature) equivalent to the conventional (Al, Ti) N layer are obtained. On the other hand, at the above-mentioned Co highest proportion dispersion point, the toughness was further secured by the high dispersion proportion of the Co component, and the interval between these Co highest proportion dispersion point and the Co non-existence point was extremely small. The coated carbide tool made of the (Al, Ti) N-Co layer having such a structure in which the hard coating layer has such a high toughness while maintaining excellent high-temperature properties as the properties of the entire layer, Even when cutting various kinds of steel or cast iron under heavy cutting conditions such as high depth of cut and high feed, where high toughness is required especially with high mechanical impact, the hard coating layer has excellent resistance. Chippin To become able to exert sex.
The research results shown in (a) and (b) above were obtained.
[0009]
The present invention has been made based on the above-described research results, and has the following features:
(A) consisting of the above (Al, Ti) N-Co,
(B) the base material of (Al, Ti) N satisfies a composition formula: (Al _1−X Ti _X ) N (where X represents 0.35 to 0.60 in atomic ratio);
(C) Co maximum proportion dispersion points and Co non-existence points alternately and repeatedly exist at predetermined intervals along the thickness direction, and further, from the Co maximum proportion dispersion points, the Co non-existence points and the Co non-existence points. A Co component concentration distribution change structure in which the Co dispersion ratio continuously increases and decreases from the existence point to the Co highest ratio dispersion point,
(D) The distance between the adjacent Co maximum ratio dispersion point and the Co non-existence point is 0.01 to 0.1 μm, and the ratio of the Co dispersion ratio at the Co maximum ratio dispersion point to the total amount with the substrate Is 1 to 10 atomic%,
Hard coated layer satisfying the above conditions (a) to (d) is physically deposited with an average layer thickness of 1 to 15 μm, and the coated hard carbide tool exhibits excellent chipping resistance under heavy cutting conditions. It is characterized by the following.
[0010]
Next, the reason why the configuration of the hard coating layer constituting the coated carbide tool of the present invention is limited as described above will be described.
(A) Composition of the base The Al component in (Al, Ti) N of the base improves high-temperature hardness and heat resistance (high-temperature characteristics), and the Ti component is included for the purpose of improving strength. If the X value indicating the ratio of Ti and Ti in the ratio (atomic ratio) to the total amount with Al is less than 0.35, the desired strength cannot be secured in the base material, while the X value is 0.60. , The high-temperature characteristics rapidly decrease, and in any case, it is impossible to provide both the high-temperature characteristics and strength excellent in the base material, so that the base material (Al, Ti) N The X value indicating the ratio of Ti in was determined to be 0.35 to 0.60.
[0011]
(B) Co highest proportion Co dispersion ratio at high dispersion point Under heavy cutting conditions such as high cutting and high feed with high mechanical impact, the hard coating layer requires higher toughness. The toughness is further improved by causing the ratio dispersion points to exist periodically along the layer thickness direction. Therefore, the dispersion ratio of Co is reduced by the total amount with the base material (Al, Ti) N. If the proportion occupies less than 1 at%, the desired effect of improving toughness cannot be obtained. On the other hand, if the dispersion proportion exceeds 10 at%, the high-temperature characteristics of the entire hard coating layer rapidly decrease, and the progress of wear is remarkably accelerated. Therefore, the distribution ratio is determined to be 1 to 10 atomic%.
[0012]
(C) The distance between the Co highest-dispersion point and the point where Co is absent If the distance is less than 0.01 μm, it is difficult to form each point clearly, and as a result, the desired high toughness and high-temperature characteristics for the layer are obtained. When the distance exceeds 0.1 μm, the disadvantages of the respective points, that is, the high temperature characteristic is insufficient at the point of the highest proportion of Co dispersion and the toughness is insufficient at the point of the absence of Co. Locally, the chipping is likely to occur on the cutting edge and the abrasion progress is promoted. Therefore, the interval is set to 0.01 to 0.1 μm.
[0013]
(D) Average layer thickness of the hard coating layer If the layer thickness is less than 1 μm, the desired wear resistance cannot be secured, while if the average layer thickness exceeds 15 μm, chipping is likely to occur. The average layer thickness was determined to be 1 to 15 μm.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the coated cemented 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 each having an average particle diameter of 1 to 3 μm were prepared. The mixture was wet-mixed for 72 hours in a ball mill, dried and pressed into a green compact at a pressure of 100 MPa, and the green compact was heated to 1400 ° C. for 1 hour in a vacuum of 6 Pa. Sintering is performed under the conditions of holding, and after sintering, the cutting edge portion is subjected to honing processing of R: 0.03, and a carbide substrate A1 to A10 made of a WC-based cemented carbide having a chip shape of ISO standard CNMG120408. Was formed.
[0015]
Further, as raw material powder, TiCN (TiC / TiN = 50/50 by weight) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder each having an average particle diameter of 0.5 to 2 μm , Co powder, and Ni powder were prepared, and these raw material powders were blended in the composition shown in Table 2, wet-mixed in a ball mill for 24 hours, dried, and then pressed into a green 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 an ISO standard CNMG120408. Carbide bases B1 to B6 made of TiCN-based cermet having the chip shape described above were formed.
[0016]
Next, each of the above-mentioned super-hard substrates A1 to A10 and B1 to B6 was ultrasonically cleaned in acetone and dried, and then placed on a rotary table in an arc ion plating apparatus shown in FIG. Are mounted along the outer peripheral portion at a position radially away from the target, and as one cathode electrode (evaporation source), an Al—Ti alloy target and a metal Co target having various component compositions, As a cathode electrode (evaporation source), an Al-Ti alloy target having the same component composition as the Al-Ti alloy target was disposed opposite to the rotary table, and a metal Ti target for bombarding was also mounted. While the inside of the apparatus was evacuated and maintained at a vacuum of 0.5 Pa or less, the inside of the apparatus was heated to 500 ° C. with a heater, and then rotated on the rotary table. A DC bias voltage of -1000 V is applied to the rotating super-hard substrate, and a current of 100 A is caused to flow between the metal Ti target of the cathode electrode and the anode electrode to generate an arc discharge. After bombarding, nitrogen gas was introduced as a reaction gas into the apparatus to obtain a reaction atmosphere of 2 Pa, and a DC bias voltage of -100 V was applied to the super-hard substrate rotating while rotating on the rotary table. A current of 150 A is applied between the cathode electrode and the anode electrode of the Al-Ti alloy target on both sides, and 50 to 80 A is applied between the metal Co target and the anode electrode, depending on the Co ratio of the Co highest ratio dispersion point. An arc discharge is generated by passing a predetermined current within the range, and the target set shown in Tables 3 and 4 is applied to the surface of the cemented carbide substrate. In the base material, Co maximum ratio dispersion points and Co non-existence points are alternately and repeatedly present at target intervals shown in Tables 3 and 4 in the layer thickness direction, and the Co maximum ratio dispersion point is determined from the Co maximum ratio dispersion point. From the existence point, the Co non-existence point to the Co highest ratio dispersion point, a Co component concentration distribution change structure in which the dispersion ratio of Co continuously increases and decreases, and the target layer thickness also shown in Tables 3 and 4 By depositing a hard coating layer, throw-away tips 1 to 16 made of the surface-coated cemented carbide of the present invention (hereinafter, referred to as the coated carbide tips of the present invention) as the coated carbide tools of the present invention were produced.
[0017]
For the purpose of comparison, these super-hard substrates A1 to A10 and B1 to B6 were ultrasonically cleaned in acetone, dried, and charged into a usual arc ion plating apparatus shown in FIG. An Al-Ti alloy target having various component compositions is mounted as a cathode electrode (evaporation source), and a metal Ti target for bombardment cleaning is further mounted. First, the inside of the apparatus is evacuated to a vacuum of 0.5 Pa or less. After the inside of the apparatus was heated to 500 ° C. with the heater while holding, a DC bias voltage of −1000 V was applied to the carbide substrate, and a current of 100 A was passed between the metal Ti target of the cathode electrode and the anode electrode. Arc discharge was generated, and the surface of the cemented carbide substrate was cleaned by Ti bombardment. Then, nitrogen gas was introduced into the apparatus as a reaction gas to obtain a reaction atmosphere of 2 Pa. At the same time, a direct current bias voltage of -100 V is applied to the super hard substrate, and a current of 100 A is caused to flow between the Al-Ti alloy target of the cathode electrode and the anode electrode to generate an arc discharge. Each of the hard substrates A1 to A10 and B1 to B6 has a target composition and a target layer thickness shown in Tables 5 and 6 and has no Co distribution distribution in the layers, and substantially (Al, Ti ) By depositing a hard coating layer consisting of an N layer, throw-away tips made of conventional surface-coated cemented carbide (hereinafter referred to as conventional coated carbide tips) 1 to 16 as conventional coated cemented carbide tools were produced, respectively.
[0018]
Next, with respect to the above-mentioned coated carbide tips 1 to 16 of the present invention and conventional coated carbide tips 1 to 16, in a state where they were screwed to the tip of a tool steel tool with a fixing jig,
Work material: JIS SCM440 round bar,
Cutting speed: 160 m / min. ,
Cut: 5mm,
Feed: 0.2 mm / rev. ,
Cutting time: 8 minutes,
Dry continuous high-cut cutting test of alloy steel under the conditions (normal cut depth is 1.5 mm),
Work material: JIS S50C lengthwise round bar with four equally spaced longitudinal grooves,
Cutting speed: 160 m / min. ,
Cut: 1.5 mm,
Feed: 0.6 mm / rev. ,
Cutting time: 10 minutes,
(Normal feed rate is 0.2 mm / rev.) Dry intermittent high feed cutting test of carbon steel.
Work material: Round bar with four vertical grooves at equal intervals in the length direction of JIS / FC300
Cutting speed: 160 m / min. ,
Cut: 5mm,
Feed: 0.2 mm / rev. ,
Cutting time: 8 minutes,
(Normal cut depth is 1.5 mm), a dry intermittent high-cut cutting test was performed on cast iron, and the flank wear width of the cutting edge was measured in each cutting test. The measurement results are shown in Tables 3 to 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, and 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 powder, and 1.8 μm Co powder were prepared. Each was blended in the composition shown in Table 7, further added wax, mixed in a ball mill in acetone for 24 hours, dried under reduced pressure, and then pressed into various compacts of a predetermined shape at a pressure of 100 MPa. The green compact is heated in a vacuum atmosphere of 6 Pa at a heating rate of 7 ° C./min to a predetermined temperature in the range of 1370 to 1470 ° C., and is kept at this temperature for 1 hour, and then fired under furnace cooling conditions. In combination, diameters of 8 mm, 13 mm, and 2 mm mm, three types of round bar sintered bodies for forming a cemented carbide substrate are formed, and the above three types of round bar sintered bodies are subjected to grinding processing in a combination shown in Table 7 to obtain a diameter of a cutting edge portion. × Carbide substrate (end mill) C-1 having dimensions of 6 mm × 13 mm, 10 mm × 22 mm, and 20 mm × 45 mm, respectively, and having a four-flute square shape with a twist angle of 30 °. C-8 were each produced.
[0026]
Then, these super-hard substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone, dried, and charged into an arc ion plating apparatus also shown in FIG. Under the same conditions as in Example 1, on the base material having the target composition shown in Table 8, Co maximum proportion dispersion points and Co non-existence points are alternately and repeatedly present at the target intervals shown in Table 8 along the layer thickness direction. And, from the Co highest ratio dispersion point to the Co non-existence point, from the Co non-existence point to the Co highest ratio dispersion point, a Co component concentration distribution change structure in which the Co dispersion ratio continuously increases and decreases, Further, by depositing a hard coating layer having a target layer thickness shown in Table 8, an end mill made of the surface-coated cemented carbide of the present invention as a coated carbide tool of the present invention (hereinafter, referred to as the coated carbide end mill of the present invention) 1 ~ 8 each made It was.
[0027]
For the purpose of comparison, the above-mentioned ultra-hard substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and then a normal arc ion plating apparatus also shown in FIG. Under the same conditions as in Example 1 above, having the target composition and the target layer thickness shown in Table 9, and having no Co distribution in the layer, and substantially (Al, Ti) N By depositing a hard coating layer composed of layers, end mills made of conventional surface-coated cemented carbide (hereinafter referred to as conventional coated carbide end mills) 1 to 8 as conventional coated cemented carbide tools were manufactured, respectively.
[0028]
Next, among the coated carbide end mills 1 to 8 of the present invention and the conventional coated carbide end mills 1 to 8, of the coated carbide end mills 1 to 3 and the coated carbide end mills 1 to 3 of the present invention,
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm, JIS SKD61 plate,
Cutting speed: 70 m / min. ,
Axial cut: 10 mm
Radial cut: 2.7mm,
Table feed: 420 mm / min,
(Normal axial depth of cut 6 mm, radial depth of cut 0.9 mm) dry high-cut side cutting test of tool steel, coated carbide end mills 4 to 6 of the present invention and conventional coated carbide end mill 4 About ~ 6
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS S50C plate,
Cutting speed: 100 m / min. ,
Axial cut: 15 mm
Radial cut: 1.5mm,
Table feed: 1280 mm / min,
(Normal table feed is 400 mm / min), dry high feed side cutting test of carbon steel, coated carbide end mills 7, 8 of the present invention and conventional coated carbide end mills 7, 8
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS SUS316 plate,
Cutting speed: 50 m / min. ,
Axial cut: 30 mm
Radial cut: 7mm,
Table feed: 120 mm / min,
(A normal axial depth of cut is 20 mm, a radial depth of cut is 3 mm), a stainless steel wet high-cut side cutting test (using water-soluble cutting oil) was performed. The cutting length was measured until the flank wear width of the outer peripheral blade of the blade portion reached 0.1 mm, which is a standard for the service life. 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 were 8 mm (for forming the super-hard substrates C-1 to C-3), 13 mm (for forming the super-hard substrates C-4 to C-6), and 26 mm (for the super-hard substrates C-). 7, for forming C-8), the diameter x length of the groove forming portion was 4 mm x 13 mm (by grinding) from the three types of round rod sintered bodies by grinding. Carbide substrates D-1 to D-3), 8 mm x 22 mm (carbide substrates D-4 to D-6), and 16 mm x 45 mm (carbide substrates D-7, D-8), Carbide substrates (drills) D-1 to D-8 each having a two-blade shape with a twist angle of 30 degrees were manufactured.
[0033]
Next, the cutting blades of the super hard substrates (drills) D-1 to D-8 are honed, ultrasonically cleaned in acetone, and dried, and then the arc ion plating apparatus shown in FIG. Under the same conditions as in Example 1 described above, a Co maximum proportion dispersion point and a Co non-existence point are alternately shown in Table 10 along the layer thickness direction on a substrate having the target composition shown in Table 10. A Co component concentration which is repeatedly present at the indicated target interval and in which the Co dispersion ratio continuously increases and decreases from the Co highest ratio dispersion point to the Co non-existence point and from the Co non-existence point to the Co highest ratio dispersion point. By drilling a hard coating layer having a distribution changing structure and a target layer thickness also shown in Table 10, a drill made of the surface-coated cemented carbide of the present invention as a coated carbide tool of the present invention (hereinafter referred to as coating of the present invention) Carbide drill) 8 were prepared, respectively.
[0034]
Also, 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, and are also shown in FIG. It was charged into a normal arc ion plating apparatus, and had the target composition and the target layer thickness shown in Table 11 under the same conditions as in Example 1 described above, and there was substantially no Co dispersion distribution in the layer. By depositing a hard coating layer composed of an (Al, Ti) N layer on the surface, drills made of conventional surface-coated cemented carbide (hereinafter referred to as conventional coated carbide drills) 1 to 8 as conventional coated carbide tools are respectively provided. Manufactured.
[0035]
Next, of the coated carbide drills 1 to 8 of the present invention and the coated carbide drills 1 to 8 of the related art, the coated carbide drills 1 to 3 of the present invention and the covered carbide drills 1 to 3 of the present invention are:
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS SCM440 plate,
Cutting speed: 60 m / min. ,
Feed: 0.25 mm / rev,
Hole depth: 10mm
(The normal feed rate is 0.08 mm / rev), the wet-type high-feed drilling cutting test of the alloy steel, the coated carbide drills 4 to 6 of the present invention and the conventionally coated carbide drills 4 to 6 are:
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS S45C plate,
Cutting speed: 80 m / min. ,
Feed: 0.4 mm / rev,
Hole depth: 20mm
(Normal feed rate is 0.12 mm / rev), wet high feed drilling test of carbon steel, coated carbide drills 7 and 8 according to the present invention and conventional coated carbide drills 7 and 8
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS FCD700 plate,
Cutting speed: 75 m / min. ,
Feed: 0.6 mm / rev,
Hole depth: 40mm
Under the conditions (normal feed rate is 0.2 mm / rev), a high-feed drilling cutting test of ductile cast iron, and the tip cutting edge is used in any wet drilling cutting test (using water-soluble cutting oil). The number of holes drilled until the flank wear width of the surface reached 0.3 mm was measured. The measurement results are shown in Tables 10 and 11, respectively.
[0036]
[Table 10]

[0037]
[Table 11]

[0038]
The resulting coated carbide tips 1 to 16, the coated carbide end mills 1 to 8 as the resulting coated carbide tools of the present invention, and the hard coating layers constituting the coated carbide drills 1 to 8 of the present invention. The composition of the base material and the Co dispersion ratio of the Co maximum dispersion point, and the conventional coated carbide tips 1-16, the conventional coated carbide end mills 1-8, and the conventional coated carbide drills 1-8 as the conventionally coated carbide tools. For the composition of the hard coating layer, the content ratios of Ti and Al and the Co dispersion ratio along the thickness direction were measured using an Auger spectroscopic analyzer. And a Co-maximum dispersion point and a Co-absence point are alternately and repeatedly present at substantially the same interval as the target value, and the Co-absence point is determined from the Co-maximum dispersion point. From the Co non-existing point to the Co highest percentage dispersion point, it has been confirmed that the Co component distribution ratio has a structure in which the dispersion ratio of Co continuously increases and decreases, and the average layer thickness of the hard coating layer is also the target layer thickness. The values were substantially the same. On the other hand, it was confirmed that the hard coating layer of the conventional coated carbide tool exhibited substantially the same composition as the target composition and the same average layer thickness as the target layer thickness.
[0039]
【The invention's effect】
From the results shown in Tables 3 to 11, it can be seen that, in the hard coating layer, Co maximum ratio dispersion points and Co non-existence points are alternately present at predetermined intervals along the layer thickness direction, and the Co maximum ratio dispersion From the point to the Co absent point, from the Co absent point to the Co highest percentage dispersion point, the coated carbide tool of the present invention having a Co component concentration distribution change structure in which the Co dispersion ratio continuously increases and decreases, Since the layer has both high toughness due to the Co highest percentage dispersion point and excellent high-temperature hardness and heat resistance due to the Co-free point, all of the cutting work of various steels and cast irons The hard coating layer shows excellent chipping resistance and shows excellent wear resistance over a long period of time even under heavy cutting conditions such as high cutting and high feed with high mechanical impact. Against, hard In a conventional coated carbide tool in which the covering layer is made of an (Al, Ti) N layer, the hard covering layer has excellent high-temperature hardness and heat resistance, but is inferior in toughness. It is clear that chipping occurs at the cutting edge in the processing, and this causes a short service life in a relatively short time.
As described above, the coated carbide tool of the present invention can be used not only for cutting under normal conditions, but also for cutting various kinds of steel and cast iron, etc., with high cutting and high feed accompanied by high mechanical impact. Even under heavy cutting conditions, it exhibits excellent chipping resistance and exhibits excellent wear resistance over a long period of time. It can be satisfied enough.
[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 conventional arc ion plating apparatus used for forming a hard coating layer constituting a conventional coated carbide tool.

Claims

On the surface of a tungsten carbide-based cemented carbide substrate or titanium carbonitride-based cermet substrate,
(A) having a two-phase structure in which Co is dispersed and distributed in a composite nitride base material of Al and Ti;
(B) The base of the composite nitride of Al and Ti satisfies the composition formula: (Al _1−X Ti _X ) N (where X represents 0.35 to 0.60 in atomic ratio). ,
(C) Co maximum proportion dispersion points and Co non-existence points alternately and repeatedly exist at predetermined intervals along the thickness direction, and further, from the Co maximum proportion dispersion points, the Co non-existence points and the Co non-existence points. A Co component concentration distribution change structure in which the Co dispersion ratio continuously increases and decreases from the existence point to the Co highest ratio dispersion point,
(D) The distance between the adjacent Co maximum ratio dispersion point and the Co non-existence point is 0.01 to 0.1 μm, and the ratio of the Co dispersion ratio at the Co maximum ratio dispersion point to the total amount with the substrate Is 1 to 10 atomic%,
A hard coating layer satisfying the above conditions (a) to (d) is physically vapor-deposited at an average layer thickness of 1 to 15 μm, and the hard coating layer exhibits excellent chipping resistance under heavy cutting conditions. Alloy cutting tool.