JP2004009162A - Cutting tool made of surface coated cemented carbide exerting excellent wear resistance of hard coat layer in high speed cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool made of surface coated cemented carbide exerting excellent wear resistance of a hard coat layer in high speed cutting. <P>SOLUTION: This cutting tool is constituted of a hard covering layer of 1∼15μm made of composite nitride of Al, Ti and Zr on which a Ti lowest containing point (point A hereinafter) and a Ti highest containing point (point B hereinafter) are alternately repeatedly exist with a specified interval, Ti content from the point B to the point A and from the point A to the point B has a continuously changing component concentration distributing structure and that the point B satisfies a composition formula: (Al<SB>1-(X+Y)</SB>Ti<SB>X</SB>Zr<SB>Y</SB>)N(but, in an atomic ratio, X shows 0.35∼0.60, Y shows 0.01∼0.15) and the point A satisfies a composition formula: (A1<SB>1-(X+Y)</SB>Ti<SB>X</SB>Zr<SB>Y</SB>)N(but, in an atomic ratio, X shows 0.05∼0.30 and Y shows 0.01∼0.15) respectively and that the interval between the adjacent points B and A is 0.01∼0.1μm. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層が一段とすぐれた高温硬さおよび耐熱性を有し、したがって特に各種の鋼や鋳鉄などの高熱発生を伴う高速切削加工で、すぐれた耐摩耗性を発揮する表面被覆超硬合金製切削工具（以下、被覆超硬工具という）に関するものである。
【０００２】
【従来の技術】
一般に、被覆超硬工具には、各種の鋼や鋳鉄などの被削材の旋削加工や平削り加工にバイトの先端部に着脱自在に取り付けて用いられるスローアウエイチップ、前記被削材の穴あけ切削加工などに用いられるドリルやミニチュアドリル、さらに前記被削材の面削加工や溝加工、肩加工などに用いられるソリッドタイプのエンドミルなどがあり、また前記スローアウエイチップを着脱自在に取り付けて前記ソリッドタイプのエンドミルと同様に切削加工を行うスローアウエイエンドミル工具などが知られている。
【０００３】
また、被覆超硬工具として、炭化タングステン（以下、ＷＣで示す）基超硬合金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−（Ｘ＋Ｙ）}Ｔｉ_ＸＺｒ_Ｙ）Ｎ（ただし、原子比で、Ｘは０．３５〜０．６０、Ｙ：０．０１〜０．１５を示す）を満足するＡｌとＴｉとＺｒの複合窒化物［以下、（Ａｌ，Ｔｉ，Ｚｒ）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知られており、これが各種の鋼や鋳鉄などの連続切削や断続切削加工に用いられることも良く知られるところである。
【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４００℃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−Ｚｒ合金がセットされたカソード電極（蒸発源）との間に、例えば電流：９０Ａの条件でアーク放電を発生させ、同時に装置内に反応ガスとして窒素ガスを導入して、例えば２Ｐａの反応雰囲気とし、一方上記超硬基体には、例えば−１００Ｖのバイアス電圧を印加した条件で、前記超硬合金基体の表面に、上記（Ａｌ，Ｔｉ，Ｚｒ）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】
【発明が解決しようとする課題】
近年の切削加工装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求は強く、これに伴い、切削加工は高速化の傾向にあるが、上記の従来被覆超硬工具においては、これを通常の切削加工条件で用いた場合には問題はないが、これを高い発熱を伴う高速切削条件で用いた場合には、硬質被覆層が高強度と高靭性を具備するものの、高温硬さおよび耐熱性が不十分であるため、硬質被覆層の摩耗進行が促進され、比較的短時間で使用寿命に至るのが現状である。
【０００６】
【課題を解決するための手段】
そこで、本発明者等は、上述のような観点から、特に高速切削加工ですぐれた耐摩耗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（Ａｌ，Ｔｉ，Ｚｒ）Ｎ層は、層厚全体に亘って均質な高温硬さと耐熱性、強度と靭性、さらに高温強度を有するが、例えば図１（ａ）に概略平面図で、同（ｂ）に概略正面図で示される構造のアークイオンプレーティング装置、すなわち装置中央部に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、一方側に上記の従来（Ａｌ，Ｔｉ，Ｚｒ）Ｎ層の形成にカソード電極（蒸発源）として用いられたＡｌ−Ｔｉ−Ｚｒ合金に相当する相対的にＴｉ含有量の高いＡｌ−Ｔｉ−Ｚｒ合金、他方側に相対的にＴｉ含有量の低いＡｌ−Ｔｉ−Ｚｒ合金をいずれもカソード電極（蒸発源）として対向配置したアークイオンプレーティング装置を用い、この装置の前記回転テーブルの外周部に沿って複数の超硬基体をリング状に装着し、この状態で装置内雰囲気を窒素雰囲気として前記回転テーブルを回転させると共に、蒸着形成される硬質被覆層の層厚均一化を図る目的で超硬基体自体も自転させながら、前記の両側のカソード電極（蒸発源）とアノード電極との間にアーク放電を発生させて、前記超硬基体の表面に（Ａｌ，Ｔｉ，Ｚｒ）Ｎ層を形成すると、この結果の（Ａｌ，Ｔｉ，Ｚｒ）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Ｔｉ含有量の高いＡｌ−Ｔｉ−Ｚｒ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Ｔｉ最高含有点が形成され、また前記超硬基体が上記の他方側の相対的にＴｉ含有量の低いＡｌ−Ｔｉ−Ｚｒ合金のカソード電極に最も接近した時点で層中にＴｉ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厚さ方向にそって前記Ｔｉ最高含有点とＴｉ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Ｔｉ最高含有点から前記Ｔｉ最低含有点、前記Ｔｉ最低含有点から前記Ｔｉ最高含有点へＴｉ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。
【０００７】
（ｂ）上記（ａ）の繰り返し連続変化成分濃度分布構造の（Ａｌ，Ｔｉ，Ｚｒ）Ｎ層において、例えば対向配置のカソード電極（蒸発源）のそれぞれの組成を調製すると共に、超硬基体が装着されている回転テーブルの回転速度を制御して、
上記Ｔｉ最高含有点が、組成式：（Ａｌ_{１−（Ｘ＋Ｙ）}Ｔｉ_ＸＺｒ_Ｙ）Ｎ（ただし、原子比で、Ｘは０．３５〜０．６０、Ｙ：０．０１〜０．１５を示す）、
上記Ｔｉ最低含有点が、組成式：（Ａｌ_{１−（Ｘ＋Ｙ）}Ｔｉ_ＸＺｒ_Ｙ）Ｎ（ただし、原子比で、Ｘは０．０５〜０．３０、Ｙ：０．０１〜０．１５を示す）、
をそれぞれ満足し、かつ隣り合う上記Ｔｉ最高含有点とＴｉ最低含有点の厚さ方向の間隔を０．０１〜０．１μｍとすると、
上記Ｔｉ最低含有点部分では、上記の従来（Ａｌ，Ｔｉ，Ｚｒ）Ｎ層に比してＡｌ含有量が相対的に高くなることから、より一段とすぐれた高温硬さと耐熱性を示し、一方上記Ｔｉ最高含有点部分は、前記従来（Ａｌ，Ｔｉ，Ｚｒ）Ｎ層と同等の組成、すなわち前記Ｔｉ最低含有点部分に比して相対的にＡｌ含有量が低く、Ｔｉ含有量の高い組成をもつので、高強度と高靭性を保持し、かつこれらＴｉ最高含有点とＴｉ最低含有点の間隔をきわめて小さくしたことから、層全体の特性として高強度と高靭性を保持し、かつＺｒによる高温強度も保持した状態ですぐれた高温硬さと耐熱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、Ｚｒ）Ｎ層からなる被覆超硬工具は、高い発熱を伴う鋼や鋳鉄などの高速切削加工ですぐれた耐摩耗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。
【０００８】
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、（Ａｌ，Ｔｉ，Ｚｒ）Ｎからなる硬質被覆層を１〜１５μｍ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、厚さ方向にそって、Ｔｉ最高含有点とＴｉ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Ｔｉ最高含有点から前記Ｔｉ最低含有点、前記Ｔｉ最低含有点から前記Ｔｉ最高含有点へＴｉ含有量が連続的に変化する成分濃度分布構造を有し、
さらに、上記Ｔｉ最高含有点が、組成式：（Ａｌ_{１−（Ｘ＋Ｙ）}Ｔｉ_ＸＺｒ_Ｙ）Ｎ（ただし、原子比で、Ｘは０．３５〜０．６０、Ｙ：０．０１〜０．１５を示す）、
上記Ｔｉ最低含有点が、組成式：（Ａｌ_{１−（Ｘ＋Ｙ）}Ｔｉ_ＸＺｒ_Ｙ）Ｎ（ただし、原子比で、Ｘは０．０５〜０．３０、Ｙ：０．０１〜０．１５を示す）、
をそれぞれ満足し、かつ隣り合う上記Ｔｉ最高含有点とＴｉ最低含有点の間隔が、０．０１〜０．１μｍである、
高速切削加工で硬質被覆層がすぐれた耐摩耗性を発揮する被覆超硬工具に特徴を有するものである。
【０００９】
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）Ｔｉ最低含有点の組成
Ｔｉ最低含有点の（Ａｌ，Ｔｉ，Ｚｒ）ＮにおけるＡｌ成分は高温硬さおよび耐熱性を向上させ、一方同Ｔｉ成分は、強度および靭性を向上させ、さらに同Ｚｒ成分は層の高温強度を一段と向上させる作用があるので、前記Ｔｉ最低含有点では相対的にＴｉ含有量を低くし、Ａｌ含有量を高くして、高熱発生を伴う高速切削に適応するすぐれた高温硬さと耐熱性を具備するようにしたものであるが、Ｔｉの割合を示すＸ値がＡｌとＺｒの合量に占める割合（原子比）で０．０５未満になると、相対的にＡｌの割合が多くなり過ぎて、高強度および高靭性を有するＴｉ最高含有点が隣接して存在しても層自体の強度および靭性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Ｔｉの割合を示すＸ値が同０．３０を越えると、相対的にＡｌの割合が少なくなり過ぎて、高速切削に要求されるすぐれた高温硬さおよび耐熱性を確保することができなくなるものであり、またＺｒの割合を示すＹ値がＡｌとＴｉの合量に占める割合（原子比）で０．０１未満では所望の高温強度を確保することができず、この結果チッピングが発生し易くなり、一方同Ｙ値が０．１５を超えても、所望の高温強度を確保することが困難になることから、Ｘ値を０．０５〜０．３０、Ｙ値を０．０１〜０．１５とそれぞれ定めた。
【００１０】
（ｂ）Ｔｉ最高含有点の組成
上記の通りＴｉ最低含有点は高温硬さおよび耐熱性のすぐれたものであるが、反面強度および靭性の劣るものであるため、このＴｉ最低含有点の強度および靭性不足を補う目的で、上記の従来（Ａｌ，Ｔｉ，Ｚｒ）Ｎ層と同等の組成、すなわち相対的にＴｉ含有割合が高く、一方Ａｌ含有量が低く、これによって高強度および高靭性を有するようになるＴｉ最高含有点を厚さ方向に交互に介在させるものであり、したがってＴｉの割合を示すＸ値がＡｌおよびＺｒ成分との合量に占める割合（原子比）で０．３５未満では、所望のすぐれた強度および靭性を確保することができず、一方同Ｘ値が０．６０を越えると、Ａｌに対するＴｉの割合が多くなり過ぎて、Ｔｉ最高含有点に所望の高温硬さおよび耐熱性を具備せしめることができなくなることから、Ｔｉ最高含有点でのＴｉの割合を示すＸ値を０．３５〜０．６０と定めた。
また、Ｔｉ最高含有点におけるＺｒ成分は、上記の通り高温強度を向上させ、もって耐チッピング性の向上に寄与する作用をもつものであり、したがってＹ値が０．０１未満では所望の高温強度向上効果が得られず、一方Ｙ値が０．１５を超えても、所望の高温強度を確保することが困難になることから、Ｙ値を０．０１〜０．１５と定めた。
【００１１】
（ｃ）Ｔｉ最低含有点とＴｉ最高含有点間の間隔
その間隔が０．０１μｍ未満ではそれぞれの点を上記の組成で明確に形成することが困難であり、この結果層に所望のすぐれた高温硬さと耐熱性、さらに高強度と高靭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Ｔｉ最低含有点であれば強度および靭性不足、Ｔｉ最高含有点であれば高温硬さと耐熱性不足が層内に局部的に現れ、これが原因で切刃にチッピングが発生し易くなったり、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。
【００１２】
（ｄ）硬質被覆層の全体平均層厚
その層厚が１μｍ未満では、所望の耐摩耗性を確保することができず、一方その平均層厚が１５μｍを越えると、切刃にチッピングが発生し易くなることから、その平均層厚を１〜１５μｍと定めた。
【００１３】
【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：１４１０℃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。
【００１４】
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：１５１０℃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。
【００１５】
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Ｔｉ最低含有点形成用Ａｌ−Ｔｉ−Ｚｒ合金、他方側のカソード電極（蒸発源）として、種々の成分組成をもったＴｉ最高含有点形成用Ａｌ−Ｔｉ−Ｚｒ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Ｔｉ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、かつカソード電極の前記金属Ｔｉとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面を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３Ｐａの反応雰囲気とすると共に、前記回転テーブル上で自転しながら回転する超硬基体に−５０Ｖの直流バイアス電圧を印加し、かつそれぞれのカソード電極（前記Ｔｉ最低含有点形成用Ａｌ−Ｔｉ−Ｚｒ合金およびＴｉ最高含有点形成用Ａｌ−Ｔｉ−Ｚｒ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の表面に、厚さ方向に沿って表３，４に示される目標組成のＴｉ最低含有点とＴｉ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Ｔｉ最高含有点から前記Ｔｉ最低含有点、前記Ｔｉ最低含有点から前記Ｔｉ最高含有点へＴｉ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。
【００１６】
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−Ｚｒ合金を装着し、またボンバート洗浄用金属Ｔｉ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４００℃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、かつカソード電極の前記金属Ｔｉとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面を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、前記超硬基体に印加するバイアス電圧を−１００Ｖに下げて、前記カソード電極とアノード電極との間にアーク放電を発生させ、もって前記超硬基体Ａ１〜Ａ１０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（Ａｌ，Ｔｉ，Ｚｒ）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。
【００１７】
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・Ｓ１０Ｃの丸棒、
切削速度：３７０ｍ／ｍｉｎ．、
切り込み：１．１ｍｍ、
送り：０．２２ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での炭素鋼の乾式高速連続旋削加工試験、
被削材：ＪＩＳ・ＳＣＭ４４０の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３２０ｍ／ｍｉｎ．、
切り込み：２．５ｍｍ、
送り：０．２５ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での合金鋼の乾式高速断続旋削加工試験、さらに、
被削材：ＪＩＳ・ＦＣ２５０の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３５０ｍ／ｍｉｎ．、
切り込み：３ｍｍ、
送り：０．２５ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での鋳鉄の乾式高速断続旋削加工試験を行い、いずれの旋削加工試験でも切刃の逃げ面摩耗幅を測定した。この測定結果を表７に示した。
【００１８】
【表１】

【００１９】
【表２】

【００２０】
【表３】

【００２１】
【表４】

【００２２】
【表５】

【００２３】
【表６】

【００２４】
【表７】

【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８に示される配合組成に配合し、さらにワックスを加えてアセトン中で４８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８に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法、並びにいずれもねじれ角：３０度の４枚刃スクエア形状をもった超硬基体（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の表面をアセトン中で超音波洗浄し、乾燥した状態で、同じく図１に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、厚さ方向に沿って表９に示される目標組成のＴｉ最低含有点とＴｉ最高含有点とが交互に同じく表９に示される目標間隔で繰り返し存在し、かつ前記Ｔｉ最高含有点から前記Ｔｉ最低含有点、前記Ｔｉ最低含有点から前記Ｔｉ最高含有点へＴｉ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９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の表面をアセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表１０に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ，Ｚｒ）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・Ｓ２０Ｃの板材、
切削速度：２８５ｍ／ｍｉｎ．、
軸方向切り込み：５ｍｍ、
径方向切り込み：０．２ｍｍ、
テーブル送り：２００ｍｍ／分、
の条件での炭素鋼の湿式高速側面切削加工試験、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・ＳＣＭ４４０の板材、
切削速度：２７０ｍ／ｍｉｎ．、
軸方向切り込み：７．５ｍｍ、
径方向切り込み：０．３ｍｍ、
テーブル送り：２２０ｍｍ／分、
の条件での合金鋼の湿式高速側面切削加工試験、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・ＦＣ２５０の板材、
切削速度：３０５ｍ／ｍｉｎ．、
軸方向切り込み：１５ｍｍ、
径方向切り込み：０．４ｍｍ、
テーブル送り：１１０ｍｍ／分、
の条件での鋳鉄の湿式高速側面切削加工試験をそれぞれ行い、いずれの側面切削加工試験（いずれの試験も水溶性切削油使用）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９、１０にそれぞれ示した。
【００２９】
【表８】

【００３０】
【表９】

【００３１】
【表１０】

【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１１に示される目標組成のＴｉ最低含有点とＴｉ最高含有点とが交互に同じく表１１に示される目標間隔で繰り返し存在し、かつ前記Ｔｉ最高含有点から前記Ｔｉ最低含有点、前記Ｔｉ最低含有点から前記Ｔｉ最高含有点へＴｉ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１１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の表面に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表１２に示される目標組成および目標層厚を有し、かつ厚さ方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ，Ｚｒ）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×２５０厚さ：５０ｍｍのＪＩＳ・Ｓ２０Ｃの板材、
切削速度：１８０ｍ／ｍｉｎ．、
送り：０．２ｍｍ／ｒｅｖ、
穴深さ：１０ｍｍ
の条件での炭素鋼の湿式高速穴あけ切削加工試験、本発明被覆超硬ドリル４〜６および従来被覆超硬ドリル４〜６については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＣＭ４４０の板材、
切削速度：１８５ｍ／ｍｉｎ．、
送り：０．２１ｍｍ／ｒｅｖ、
穴深さ：１５ｍｍ
の条件での合金鋼の湿式高速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・ＦＣ２５０の板材、
切削速度：２２５ｍ／ｍｉｎ．、
送り：０．２５ｍｍ／ｒｅｖ、
穴深さ：３０ｍｍ
の条件での鋳鉄の湿式高速穴あけ切削加工試験、をそれぞれ行い、いずれの湿式高速穴あけ切削加工試験（水溶性切削油使用）でも先端切刃面の逃げ面摩耗幅が０．３ｍｍに至るまでの穴あけ加工数を測定した。この測定結果を表１１、１２にそれぞれ示した。
【００３６】
【表１１】

【００３７】
【表１２】

【００３８】
なお、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Ｔｉ最低含有点とＴｉ最高含有点の組成、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をオージェ分光分析装置を用いて測定したところ、それぞれ目標組成と実質的に同じ組成を示した。
また、これらの本発明被覆超硬工具の硬質被覆層におけるＴｉ最低含有点とＴｉ最高含有点間の間隔、およびこれの全体層厚、並びに従来被覆超硬工具の硬質被覆層の厚さを、走査型電子顕微鏡を用いて断面測定したところ、いずれも目標値と実質的に同じ値を示した。
【００３９】
【発明の効果】
表３〜１２に示される結果から、硬質被覆層が層厚方向にＴｉ最低含有点とＴｉ最高含有点とが交互に所定間隔をおいて繰り返し存在し、かつ前記Ｔｉ最高含有点から前記Ｔｉ最低含有点、前記Ｔｉ最低含有点から前記Ｔｉ最高含有点へＴｉ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、いずれも鋼や鋳鉄の切削加工を高い発熱を伴う高速で行っても、すぐれた耐摩耗性を発揮するのに対して、硬質被覆層が厚さ方向に沿って実質的に組成変化のない（Ａｌ，Ｔｉ，Ｚｒ）Ｎ層からなる従来被覆超硬工具においては、高温を伴う高速切削加工では前記層の高温硬さおよび耐熱性不足が原因で切刃の摩耗進行が速く、比較的短時間で使用寿命に至ることが明らかである。
上述のように、この発明の被覆超硬工具は、特に各種の鋼や鋳鉄などの高速切削加工でもすぐれた耐摩耗性を発揮し、長期に亘ってすぐれた切削性能を示すものであるから、切削加工装置の高性能化、並びに切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。
【図面の簡単な説明】
【図１】この発明の被覆超硬工具を構成する硬質被覆層を形成するのに用いたアークイオンプレーティング装置を示し、（ａ）は概略平面図、（ｂ）は概略正面図である。
【図２】従来被覆超硬工具を構成する硬質被覆層を形成するのに用いた通常のアークイオンプレーティング装置の概略説明図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface coating super hard coating layer having excellent high-temperature hardness and heat resistance, and thus exhibiting excellent wear resistance, especially in high-speed cutting work involving high heat generation of various steels and cast irons. The present invention relates to a hard alloy cutting tool (hereinafter, referred to as a coated carbide tool).
[0002]
[Prior art]
In general, coated carbide tools include throw-away inserts, which are detachably attached to the tip of a cutting tool for turning or planing of various materials such as steel or cast iron, and drilling of the material. Drills and miniature drills used for processing and the like, there are solid type end mills and the like used for face machining and grooving, shoulder machining and the like of the work material, and the solid is provided by detachably attaching the throw-away tip. 2. Description of the Related Art A throw-away end mill tool or the like that performs a cutting process like a type end mill is known.
[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) surface, composition _{formula): (Al 1- (X +} Y) Ti X Zr Y) N ( provided that an atomic ratio, X is from 0.35 to 0.60, Y: shows the 0.01 to 0.15) Coated hard tool formed by physical vapor deposition of a hard coating layer composed of a composite nitride of Al, Ti and Zr [hereinafter, referred to as (Al, Ti, Zr) N] with an average thickness of 1 to 15 μm. It is also well known that this is used for continuous cutting and intermittent cutting of various steels and cast irons.
[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 an anode electrode and a cathode electrode (evaporation source) on which an Al-Ti-Zr alloy having a predetermined composition is set, for example, at a current of 90 A while being heated to a temperature of 400 ° 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. It is also known that a hard coating layer composed of the above (Al, Ti, Zr) N layer is formed by vapor deposition.
[0005]
[Problems to be solved by the invention]
In recent years, the performance of cutting equipment has been remarkably improved, and on the other hand, there has been a strong demand for labor saving, energy saving, and further cost reduction for cutting work. In coated carbide tools, there is no problem when used under normal cutting conditions, but when used under high-speed cutting conditions with high heat generation, the hard coating layer has high strength and high toughness. However, since the high-temperature hardness and the heat resistance are insufficient, the progress of abrasion of the hard coating layer is promoted, and the service life is relatively short in the present situation.
[0006]
[Means for Solving the Problems]
In view of the above, the present inventors have developed a hard coating layer constituting the above-mentioned conventional coated carbide tool in order to develop a coated carbide tool exhibiting excellent wear resistance particularly in high-speed cutting. As a result of conducting research with a focus on
(A) The (Al, Ti, Zr) N layer constituting the conventional coated carbide tool formed using the arc ion plating apparatus shown in FIG. , Heat resistance, strength and toughness, and high-temperature strength. 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. Is provided with a rotary table for mounting a cemented carbide substrate, and on one side of the rotary table, Al-Ti- used as a cathode electrode (evaporation source) for forming the above-mentioned conventional (Al, Ti, Zr) N layer. An Al—Ti—Zr alloy having a relatively high Ti content corresponding to the Zr alloy and an Al—Ti—Zr alloy having a relatively low Ti content on the other side are both arranged as cathode electrodes (evaporation sources). Arc ion pump A plurality of super-hard substrates are mounted in a ring shape along the outer periphery of the turntable of the device using a printing device, and in this state, the turntable is rotated while the atmosphere in the device is set to a nitrogen atmosphere, and vapor deposition is performed. In order to make the thickness of the hard coating layer uniform, an arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides while rotating the cemented carbide substrate itself, thereby forming the cemented carbide substrate. When the (Al, Ti, Zr) N layer is formed on the surface of the substrate, in the resulting (Al, Ti, Zr) N layer, the cemented carbide substrate arranged in a ring shape on the turntable has the above-mentioned one side. At the point closest to the cathode electrode (evaporation source) of an Al—Ti—Zr alloy having a relatively high Ti content, the highest Ti content point is formed in the layer. Relatively Ti At the point closest to the low-weight Al-Ti-Zr alloy cathode electrode, the lowest Ti content point is formed in the layer, and the rotation of the rotary table causes the highest Ti content in the layer along the thickness direction. A point and a Ti minimum content point alternately and repeatedly appear at predetermined intervals, and a component in which the Ti content continuously changes from the Ti maximum content point to the Ti minimum content point and from the Ti minimum content point to the Ti maximum content point. To have a concentration distribution structure.
[0007]
(B) In the (Al, Ti, Zr) N layer having the repeated and continuously changing component concentration distribution structure of the above (a), for example, the respective compositions of the cathode electrodes (evaporation sources) arranged opposite to each other are prepared, and the super-hard substrate is formed. By controlling the rotation speed of the mounted rotary table,
The Ti maximum content point, the composition _{formula: (Al 1- (X + Y} ) Ti X Zr Y) N ( provided that an atomic ratio, X is from 0.35 to 0.60, Y: a 0.01 to 0.15 Show),
The Ti minimum content point, the composition _{formula: (Al 1- (X + Y} ) Ti X Zr Y) N ( provided that an atomic ratio, X is 0.05 to 0.30, Y: a 0.01 to 0.15 Show),
And the distance between the adjacent Ti maximum content point and the minimum Ti content point in the thickness direction is 0.01 to 0.1 μm.
Since the Al content is relatively higher in the above-mentioned Ti minimum content point portion than in the above-mentioned conventional (Al, Ti, Zr) N layer, it shows more excellent high-temperature hardness and heat resistance. The Ti highest content portion has a composition equivalent to that of the conventional (Al, Ti, Zr) N layer, that is, a composition having a relatively low Al content and a high Ti content compared to the lowest Ti content portion. Therefore, the high strength and high toughness are maintained, and the interval between the highest Ti content point and the lowest Ti content point is extremely small. The coated carbide tool made of the (Al, Ti, Zr) N layer having such a structure that the hard coating layer is formed is accompanied by high heat generation, while having excellent high-temperature hardness and heat resistance while maintaining strength. High-speed cutting of steel and cast iron It is like to exhibit wear resistance excellent in working.
The research results shown in (a) and (b) above were obtained.
[0008]
The present invention has been made based on the above research results, and a physical vapor deposition of a hard coating layer made of (Al, Ti, Zr) N with a total average layer thickness of 1 to 15 μm on the surface of a super hard substrate. In coated carbide tools,
In the hard coating layer, the highest Ti content point and the lowest Ti content point alternately and repeatedly exist at predetermined intervals along the thickness direction, and the lowest Ti content point and the lowest Ti content point from the highest Ti content point. Having a component concentration distribution structure in which the Ti content continuously changes from the lowest content point to the highest Ti content point,
Furthermore, the Ti maximum content point, the composition _{formula: (Al 1- (X + Y} ) Ti X Zr Y) N ( provided that an atomic ratio, X is 0.35~0.60, Y: 0.01~0. 15),
The Ti minimum content point, the composition _{formula: (Al 1- (X + Y} ) Ti X Zr Y) N ( provided that an atomic ratio, X is 0.05 to 0.30, Y: a 0.01 to 0.15 Show),
Respectively, and the interval between adjacent Ti maximum content point and Ti minimum content point is 0.01 to 0.1 μm,
The present invention is characterized by a coated carbide tool in which a hard coating layer exhibits excellent wear resistance by high-speed cutting.
[0009]
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 lowest Ti content point The Al component in the (Ti, Zr) N with the lowest Ti content improves high-temperature hardness and heat resistance, while the same Ti component improves strength and toughness, Since the Zr component has the effect of further improving the high-temperature strength of the layer, the Ti content is relatively reduced and the Al content is increased at the lowest content point of the Ti to adapt to high-speed cutting with high heat generation. It has excellent high-temperature hardness and heat resistance, but when the X value indicating the ratio of Ti is less than 0.05 in the ratio (atomic ratio) to the total amount of Al and Zr, the relative value is relatively small. Even if the Al content is too large and the highest Ti content point having high strength and high toughness exists adjacently, a decrease in the strength and toughness of the layer itself is unavoidable, and as a result, chipping and the like are likely to occur. , On the other hand, indicates the proportion of Ti If the value exceeds 0.30, the ratio of Al becomes relatively too small, and it becomes impossible to secure excellent high-temperature hardness and heat resistance required for high-speed cutting. If the Y value indicating the ratio is less than 0.01 in the ratio (atomic ratio) to the total amount of Al and Ti, desired high-temperature strength cannot be secured, and as a result, chipping is likely to occur, while the same Y value Exceeds 0.15, it becomes difficult to secure the desired high-temperature strength. Therefore, the X value is set to 0.05 to 0.30 and the Y value is set to 0.01 to 0.15.
[0010]
(B) Composition of the highest content point of Ti As described above, the lowest content point of Ti is excellent in high-temperature hardness and heat resistance, but is inferior in strength and toughness. For the purpose of compensating for the lack of toughness, the composition is equivalent to that of the above-mentioned conventional (Al, Ti, Zr) N layer, that is, the Ti content is relatively high, while the Al content is low, so that it has high strength and high toughness. Thus, the maximum Ti content point is alternately interposed in the thickness direction. Therefore, if the X value indicating the ratio of Ti is less than 0.35 in the ratio (atomic ratio) to the total amount of the Al and Zr components, When the excellent X value exceeds 0.60, the ratio of Ti to Al becomes too large and the desired high-temperature hardness and the desired With heat resistance Since it becomes impossible to allowed to, it was defined as 0.35 to 0.60 the X value indicating the proportion of Ti in Ti up containing point.
Further, the Zr component at the highest Ti content point has the effect of improving the high-temperature strength as described above and thus contributing to the improvement of chipping resistance. Therefore, when the Y value is less than 0.01, the desired high-temperature strength improvement is achieved. The effect is not obtained. On the other hand, if the Y value exceeds 0.15, it becomes difficult to secure a desired high-temperature strength. Therefore, the Y value is set to 0.01 to 0.15.
[0011]
(C) Spacing between the lowest Ti content point and the highest Ti content point If the spacing is less than 0.01 μm, it is difficult to clearly form each point with the above composition, and as a result, the desired high temperature for the layer is obtained. Hardness and heat resistance, as well as high strength and high toughness, cannot be ensured. If the interval exceeds 0.1 μm, the disadvantages of each point, that is, if the minimum content of Ti, the strength and toughness are insufficient. At the highest content point, high-temperature hardness and insufficient heat resistance appear locally in the layer, which causes chipping to occur easily on the cutting edge and promotes abrasion progress, so the interval is set to It was determined as 0.01 to 0.1 μm.
[0012]
(D) If the average thickness of the hard coating layer is less than 1 μm, the desired wear resistance cannot be ensured. On the other hand, if the average thickness exceeds 15 μm, chipping occurs on the cutting edge. The average layer thickness was determined to be 1 to 15 μm because it was easier.
[0013]
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. And wet-mixed in a ball mill for 72 hours, dried, and pressed into a green compact at a pressure of 100 MPa, and the green compact was heated at 1410 ° 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.
[0014]
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 1510 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to conform to ISO standard CNMG120408. Carbide bases B1 to B6 made of TiCN-based cermet having the chip shape described above were formed.
[0015]
Then, each of the above-mentioned super-hard substrates A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, and is placed on a rotary table in an arc ion plating apparatus shown in FIG. Attached along, as one side cathode electrode (evaporation source), an Al-Ti-Zr alloy for forming the lowest Ti content point having various component compositions, and as the other side cathode electrode (evaporation source), various components An Al-Ti-Zr alloy for forming the highest Ti content point having a composition is disposed to face the rotary table, and metal Ti for bombarding is also mounted. After heating the inside of the apparatus to 500 ° C. with a heater, a DC bias voltage of −1000 V was applied to the carbide substrate rotating while rotating on the rotary table, and An arc discharge is generated by passing a current of 100 A between the metal Ti of the electrode and the anode electrode, and the surface of the super-hard substrate is cleaned by Ti bombardment. Then, nitrogen gas is introduced into the apparatus as a reaction gas by 3 Pa. While applying a reaction atmosphere, a DC bias voltage of -50 V is applied to the superhard substrate rotating while rotating on the rotary table, and the respective cathode electrodes (the Al-Ti-Zr alloy for forming the Ti minimum content point and the A current of 150 A was applied between the Al-Ti-Zr alloy for forming the highest Ti content point and the anode electrode to generate an arc discharge, and thus, on the surface of the cemented carbide substrate, along the thickness direction, as shown in Table 3, The Ti minimum content point and the Ti maximum content point of the target composition shown in No. 4 are alternately and repeatedly present at the target intervals shown in Tables 3 and 4; It has a component concentration distribution structure in which the Ti content continuously changes from the lowest Ti content point to the lowest Ti content point and from the lowest Ti content point, and has a target total layer thickness hard as shown in Tables 3 and 4. By depositing the coating layer, throw-away tips (hereinafter, referred to as the coated carbide tips of the present invention) 1-16 made of the surface-coated cemented carbide of the present invention as the coated carbide tools of the present invention were produced, respectively.
[0016]
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—Zr alloy having various component compositions is mounted as a cathode electrode (evaporation source), and metal Ti for bombarding is also 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 400 ° C. with the heater while holding, a DC bias voltage of −1000 V was applied to the superhard substrate, and a current of 100 A was passed between the metal Ti 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 form a reaction atmosphere of 2 Pa. By lowering the bias voltage applied to the hard substrate to -100 V, an arc discharge was generated between the cathode electrode and the anode electrode, and the surface of each of the super hard substrates A1 to A10 and B1 to B6 was added to Table 5 By depositing a hard coating layer composed of an (Al, Ti, Zr) N layer having a target composition and a target layer thickness shown in FIGS. Conventional surface coated cemented carbide throwaway tips (hereinafter referred to as conventional coated cemented carbide tips) 1 to 16 as coated cemented carbide tools were manufactured, respectively.
[0017]
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 S10C round bar,
Cutting speed: 370 m / min. ,
Cut: 1.1 mm,
Feed: 0.22 mm / rev. ,
Cutting time: 5 minutes,
Dry high-speed continuous turning test of carbon steel under the conditions of
Work material: JIS SCM440 4 rods with longitudinal grooves at regular intervals in the longitudinal direction,
Cutting speed: 320 m / min. ,
Cut: 2.5mm,
Feed: 0.25 mm / rev. ,
Cutting time: 5 minutes,
High-speed intermittent turning test of alloy steel under the following conditions,
Work material: Round bar with four vertical grooves at equal intervals in the length direction of JIS FC250
Cutting speed: 350 m / min. ,
Cut: 3mm,
Feed: 0.25 mm / rev. ,
Cutting time: 8 minutes,
A dry high-speed intermittent turning test of cast iron was performed under the conditions described in (1), and the flank wear width of the cutting edge was measured in each of the turning tests. Table 7 shows the measurement results.
[0018]
[Table 1]

[0019]
[Table 2]

[0020]
[Table 3]

[0021]
[Table 4]

[0022]
[Table 5]

[0023]
[Table 6]

[0024]
[Table 7]

[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 to the composition shown in Table 8, further added wax, mixed in a ball mill for 48 hours in acetone, 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 8 to obtain a diameter of a cutting edge portion. × Carbide substrates (end mills) C-1 to C-8 each having dimensions of 6 mm × 13 mm, 10 mm × 22 mm, and 20 mm × 45 mm, and a four-flute square shape with a twist angle of 30 °. Was manufactured respectively.
[0026]
Then, the surfaces of 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, the minimum Ti content points and the maximum Ti content points of the target compositions shown in Table 9 alternately exist along the thickness direction at the same target intervals as shown in Table 9; It has a component concentration distribution structure in which the Ti content continuously changes from the highest Ti content point to the lowest Ti content point, and from the lowest Ti content point to the highest Ti content point. By depositing a hard coating layer having a layer thickness, end mills 1 to 8 made of the surface coated cemented carbide of the present invention (hereinafter referred to as the coated carbide end mill of the present invention) as the coated carbide tool of the present invention were manufactured.
[0027]
For the purpose of comparison, the surfaces of the above-mentioned super-hard substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone, dried, and then dried in the usual arc ion plating shown in FIG. It was charged into the apparatus, and had the target composition and target layer thickness shown in Table 10 under the same conditions as in Example 1 described above, and had substantially no composition change along the layer thickness direction (Al, Ti, Zr) 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 produced by depositing a hard coating layer composed of an N layer.
[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 S20C plate,
Cutting speed: 285 m / min. ,
Axial cut: 5mm
Radial cut: 0.2mm,
Table feed: 200 mm / min,
For the wet high-speed side cutting test of carbon steel under the following conditions, the coated carbide end mills 4 to 6 of the present invention and the conventionally coated carbide end mills 4 to 6,
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS SCM440 plate,
Cutting speed: 270 m / min. ,
Axial cut: 7.5 mm
Radial cut: 0.3mm,
Table feed: 220 mm / min,
For the wet high-speed side cutting test of the alloy 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: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS FC250 plate,
Cutting speed: 305 m / min. ,
Axial cut: 15 mm
Radial cut: 0.4mm
Table feed: 110 mm / min,
Wet high-speed side cutting test of cast iron under the following conditions, and the flank wear width of the outer cutting edge of the cutting edge is the guideline of service life in any side cutting test (both tests use water-soluble cutting oil). The cutting length up to 0.1 mm was measured. The measurement results are shown in Tables 9 and 10, respectively.
[0029]
[Table 8]

[0030]
[Table 9]

[0031]
[Table 10]

[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), dimensions of 8 mm x 22 mm (carbide substrates D-4 to D-6), and 16 mm x 45 mm (carbide substrates D-7 and D-8), and any of them 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, and the Ti minimum content point and the Ti maximum content point of the target composition shown in Table 11 are alternately arranged along the layer thickness direction in the same manner as in Example 11. And a component concentration distribution structure in which the Ti content continuously changes from the highest Ti content to the lowest Ti content, from the lowest Ti content to the highest Ti content, and By depositing a hard coating layer having a target total layer thickness shown in 11, a drill made of the surface-coated cemented carbide of the present invention as the coated carbide tool of the present invention (hereinafter referred to as the coated carbide drill of the present invention) 1 to 8 Was manufactured respectively.
[0034]
Also, for the purpose of comparison, the surface of the above-mentioned carbide substrate (drill) D-1 to D-8 is honed, ultrasonically washed in acetone, and dried, and is then shown in FIG. Under the same conditions as in Example 1 above, having the target composition and target layer thickness shown in Table 12, and having substantially no composition change along the thickness direction. By depositing a hard coating layer composed of an (Al, Ti, Zr) N layer, conventional surface-coated carbide alloy drills (hereinafter referred to as conventional coated carbide drills) 1 to 8 as conventional coated carbide tools are obtained. Each was 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 Thickness: 50 mm JIS S20C plate,
Cutting speed: 180 m / min. ,
Feed: 0.2 mm / rev,
Hole depth: 10mm
For the wet-type high-speed drilling test of carbon steel under the following conditions, the coated carbide drills 4 to 6 of the present invention and the conventionally coated carbide drills 4 to 6,
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS SCM440 plate,
Cutting speed: 185 m / min. ,
Feed: 0.21 mm / rev,
Hole depth: 15mm
For the wet high-speed drilling test of the alloy steel under the conditions described below, the coated carbide drills 7 and 8 of the present invention and the conventionally coated carbide drills 7 and 8 are as follows.
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS FC250 plate,
Cutting speed: 225 m / min. ,
Feed: 0.25 mm / rev,
Hole depth: 30mm
Welding high-speed drilling cutting test of cast iron under the conditions described above, and in all wet high-speed drilling cutting tests (using water-soluble cutting oil), the flank wear width of the tip cutting edge surface reaches 0.3 mm. The number of drilling operations was measured. The measurement results are shown in Tables 11 and 12, respectively.
[0036]
[Table 11]

[0037]
[Table 12]

[0038]
The hard coatings constituting the coated carbide tips 1-16, coated carbide end mills 1-8, and coated drills 1-8 of the present invention as the coated carbide tools of the present invention obtained as a result. Composition of the lowest Ti content point and the highest Ti content point in the layer, and the conventional coated carbide tips 1-16, conventional coated carbide end mills 1-8, and conventional coated carbide drills 1-8 as conventional coated carbide tools. When the composition of the hard coating layer was measured using an Auger spectroscopic analyzer, each composition showed substantially the same composition as the target composition.
Further, the interval between the lowest point of Ti and the highest point of Ti in the hard coating layer of the coated carbide tool of the present invention, and the total layer thickness thereof, and the thickness of the hard coating layer of the conventional coated carbide tool, When the cross section was measured using a scanning electron microscope, all the values showed substantially the same value as the target value.
[0039]
【The invention's effect】
From the results shown in Tables 3 to 12, it can be seen from the results shown in the hard coating layer that the lowest Ti content point and the highest Ti content point are alternately present at predetermined intervals in the layer thickness direction, and the lowest Ti content point and the lowest Ti content point from the highest Ti content point. Content point, the coated carbide tool of the present invention having a component concentration distribution structure in which the Ti content continuously changes from the lowest Ti content point to the highest Ti content point, all of which generate high heat when cutting steel or cast iron. The conventional coating consisting of an (Al, Ti, Zr) N layer in which the hard coating layer has substantially no composition change along the thickness direction, while exhibiting excellent wear resistance even at high speed. In a carbide tool, it is clear that in high-speed cutting at high temperatures, wear of the cutting edge progresses rapidly due to lack of high-temperature hardness and heat resistance of the layer, resulting in a relatively short service life.
As described above, the coated cemented carbide tool of the present invention exhibits excellent wear resistance especially in high-speed cutting of various steels and cast irons, and exhibits excellent cutting performance over a long period of time. The present invention can sufficiently satisfy the high performance of the cutting device, the labor saving and energy saving of the cutting process, and the cost reduction.
[Brief description of the drawings]
FIG. 1 shows an arc ion plating apparatus used for forming a hard coating layer constituting a coated carbide tool of the present invention, wherein (a) is a schematic plan view and (b) is a schematic front view.
FIG. 2 is a schematic explanatory view of a conventional arc ion plating apparatus used for forming a hard coating layer constituting a conventional coated carbide tool.

Claims (1)

炭化タングステン基超硬合金基体または炭窒化チタン系サーメット基体の表面に、ＡｌとＴｉとＺｒの複合窒化物からなる硬質被覆層を１〜１５μｍの全体平均層厚で物理蒸着してなる表面被覆超硬合金製切削工具において、
上記硬質被覆層が、厚さ方向にそって、Ｔｉ最高含有点とＴｉ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Ｔｉ最高含有点から前記Ｔｉ最低含有点、前記Ｔｉ最低含有点から前記Ｔｉ最高含有点へＴｉ含有量が連続的に変化する成分濃度分布構造を有し、
さらに、上記Ｔｉ最高含有点が、組成式：（Ａｌ_{１−（Ｘ＋Ｙ）}Ｔｉ_ＸＺｒ_Ｙ）Ｎ（ただし、原子比で、Ｘは０．３５〜０．６０、Ｙ：０．０１〜０．１５を示す）、
上記Ｔｉ最低含有点が、組成式：（Ａｌ_{１−（Ｘ＋Ｙ）}Ｔｉ_ＸＺｒ_Ｙ）Ｎ（ただし、原子比で、Ｘは０．０５〜０．３０、Ｙ：０．０１〜０．１５を示す）、
をそれぞれ満足し、かつ隣り合う上記Ｔｉ最高含有点とＴｉ最低含有点の間隔が、０．０１〜０．１μｍであること、
を特徴とする高速切削加工で硬質被覆層がすぐれた耐摩耗性を発揮する表面被覆超硬合金製切削工具。Surface coating super-hardness formed by physical vapor deposition of a hard coating layer composed of a composite nitride of Al, Ti and Zr on the surface of a tungsten carbide-based cemented carbide substrate or a titanium carbonitride-based cermet substrate with a total average layer thickness of 1 to 15 µm. For hard alloy cutting tools,
In the hard coating layer, the highest Ti content point and the lowest Ti content point alternately and repeatedly exist at predetermined intervals along the thickness direction, and the lowest Ti content point and the lowest Ti content point from the highest Ti content point. Having a component concentration distribution structure in which the Ti content continuously changes from the lowest content point to the highest Ti content point,
Furthermore, the Ti maximum content point, the composition _{formula: (Al 1- (X + Y} ) Ti X Zr Y) N ( provided that an atomic ratio, X is 0.35~0.60, Y: 0.01~0. 15),
The Ti minimum content point, the composition _{formula: (Al 1- (X + Y} ) Ti X Zr Y) N ( provided that an atomic ratio, X is 0.05 to 0.30, Y: a 0.01 to 0.15 Show),
Respectively, and the interval between adjacent Ti maximum content point and Ti minimum content point is 0.01 to 0.1 μm,
Surface coated cemented carbide cutting tool with a hard coating layer that exhibits excellent wear resistance during high-speed cutting.

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