JP2005028474A - Cutting tool made of surface coated cemented carbide with hard coating layer exhibiting excellent wear resistance in high-speed cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool made of surface coated cemented carbide with a hard coating layer exhibiting excellent wear resistance in high-speed cutting. <P>SOLUTION: The hard coating layer of the cutting tool made of the surface coated cemented carbide formed by physical vapor deposition of the hard coating layer in the average layer thickness of 0.5-15 μm on the surface of a carbide substrate, comprises a compound nitride of Ti, Si and B (boron) having a component concentration distribution structure wherein Si maximum content points and Si minimum content points exist in alternate repetition at prescribed spaces along a layer thickness direction and the content rates of Ti and Si continuously change between both points, and the Si maximum content point satisfies a composition formula: [Ti<SB>1-(X+Z)</SB>Si<SB>X</SB>B<SB>Z</SB>]N, wherein X is 0.50-0.70 and Z is 0.01-0.10 at the atomic ratio, while the Si minimum content point satisfies a composition formula: [Ti<SB>1-(Y+Z)</SB>Si<SB>Y</SB>B<SB>Z</SB>]N, wherein Y is 0.03-0.30 and Z is 0.01-0.10 at the atomic ratio, and further the spacing of the adjacent Si maximum content points and Si minimum content points is 0.01-0.1 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層がすぐれた高温硬さと耐熱性を有し、かつすぐれた高温強度も具備し、したがって各種の鋼や鋳鉄などの高熱発生を伴なう高速切削加工で、一段と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超硬基体の表面に、
組成式：［Ｔｉ_{１− Ａ} Ｓｉ_Ａ ］Ｎ（ただし、原子比で、Ａは０．０１〜０．４５を示す）、
を満足するＴｉとＳｉの複合窒化物［以下、（Ｔｉ，Ｓｉ）Ｎで示す］からなる硬質被覆層を０．５〜１５μｍ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、この被覆超硬工具は、硬質被覆層である前記（Ｔｉ、Ｓｉ）Ｎ層がＴｉ成分による高温強度とＳｉ成分による高温硬さおよび耐熱性を具備することから、各種の鋼や鋳鉄などの連続切削や断続切削加工に用いられることも良く知られるところである（例えば、特許文献１参照）。
【０００４】
さらに、上記の被覆超硬工具が、例えば図２に概略説明図で示される物理蒸着装置の１種であるアークイオンプレーティング装置に上記の超硬基体を装入し、ヒータで装置内を、例えば５００℃の温度に加熱した状態で、アノード電極と各種の組成をもったＴｉ−Ｓｉ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：１００Ａの条件でアーク放電を発生させ、同時に装置内に反応ガスとして窒素ガスの混合ガスを導入して、例えば２．５Ｐａ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、前記超硬基体の表面に、（Ｔｉ，Ｓｉ）Ｎ層からなる硬質被覆層を０．５〜１５μｍの平均層厚で蒸着することにより製造されることも知られている。
【０００５】
【特許文献１】
特開平８−１１８１０６号公報
【０００６】
【発明が解決しようとする課題】
近年の切削加工装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求も強く、これに伴い、切削加工は高速化の傾向にあるが、上記の硬質被覆層が（Ｔｉ，Ｓｉ）Ｎ層からなる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なう高速切削条件で用いた場合には、硬質被覆層の高温硬さおよび耐熱性不足が原因で摩耗進行が一段と促進し、比較的短時間で使用寿命に至るのが現状である。
【０００７】
【課題を解決するための手段】
そこで、本発明者等は、上述のような観点から、特に高速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の硬質被覆層を構成する（Ｔｉ，Ｓｉ）Ｎ層は、層厚全体に亘って均質な高温強度と、高温硬さおよび耐熱性を有するが、例えば図１（ａ）に概略平面図で、同（ｂ）に概略正面図で示される構造のアークイオンプレーティング装置、すなわち装置中央部に超硬基体装着用回転テーブルを設け、前記回転テーブルを挟んで、一方側にＳｉ含有量が上記の従来（Ｔｉ，Ｓｉ）Ｎ層の形成にカソード電極（蒸発源）として用いられているＴｉ−Ｓｉ合金のＳｉ含有量の低い側に相当するＳｉ含有量のＴｉ−Ｓｉ−Ｂ合金、他方側に相対的にＳｉ含有量の高いＴｉ−Ｓｉ−Ｂ合金をそれぞれカソード電極（蒸発源）として対向配置した装置を用い、この装置の前記回転テーブル上に、前記回転テーブルの中心軸から半径方向に所定距離離れた位置に外周部に沿って複数の超硬基体をリング状に装着し、この状態で装置内の反応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、前記の相対的にＳｉ含有量の低いＴｉ−Ｓｉ−Ｂ合金および相対的にＳｉ含有量の高いＴｉ−Ｓｉ−Ｂ合金のカソード電極とアノード電極との間にアーク放電を発生させて、前記超硬基体の表面にＴｉとＳｉとＢの複合窒化物［以下、（Ｔｉ，Ｓｉ，Ｂ）Ｎで示す］層を形成すると、この結果の（Ｔｉ，Ｓｉ，Ｂ）Ｎ層においては、回転テーブル上にリング状に配置された前記超硬基体が上記の一方側の相対的にＳｉ含有量の高いＴｉ−Ｓｉ−Ｂ合金のカソード電極に最も接近した時点で層中にＳｉ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Ｓｉ含有量の低いＴｉ−Ｓｉ−Ｂ合金のカソード電極に最も接近した時点で層中にＳｉ最低含有点が形成され、上記回転テーブルの回転によって層中には層厚方向にそって前記Ｓｉ最高含有点とＳｉ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Ｓｉ最高含有点から前記Ｓｉ最低含有点、前記Ｓｉ最低含有点から前記Ｓｉ最高含有点へＴｉおよびＳｉの含有割合がそれぞれ連続的に変化する成分濃度分布構造をもつようになること。
【０００８】
（ｂ）上記（ａ）の繰り返し連続変化成分濃度分布構造の（Ｔｉ，Ｓｉ，Ｂ）Ｎ層において、例えば対向配置の上記Ｓｉ最高含有点形成用Ｔｉ−Ｓｉ−Ｂ合金およびＳｉ最低含有点形成用Ｔｉ−Ｓｉ−Ｂ合金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Ｓｉ最高含有点が、組成式：［Ｓｉ_{１− （Ｘ＋Ｚ）}Ｔｉ_Ｘ Ｂ_Ｚ ］Ｎ（ただし、原子比で、Ｘは０．５０〜０．７０、Ｚは０．０１〜０．１０を示す）、上記Ｓｉ最低含有点が、組成式：［Ｔｉ_{１− （ Ｙ ＋Ｚ）}Ｓｉ_Ｙ Ｂ_Ｚ ］Ｎ（ただし、原子比で、Ｙは０．０３〜０．３０、Ｚは０．０１〜０．１０を示す）、
をそれぞれ満足し、かつ隣り合う上記Ｓｉ最高含有点とＳｉ最低含有点の厚さ方向の間隔を０．０１〜０．１μｍとすると、
上記Ｓｉ最高含有点部分では、（Ｔｉ，Ｓｉ，Ｂ）Ｎ層におけるＳｉ含有量が相対的に高く、Ｔｉ含有量が低くなることから、より一段と高い高温硬さおよび耐熱性を示し、一方上記Ｓｉ最低含有点部分では、前記Ｓｉ最高含有点部分に比してＳｉ含有量が低く、Ｔｉ含有量の高いものとなるので、相対的に高い高温強度、すなわち上記従来（Ｔｉ，Ｓｉ）Ｎ層のもつ高温強度と同等の高温強度が確保され、これらＳｉ最高含有点とＳｉ最低含有点の間隔をきわめて小さくしたことから、層全体の特性としてすぐれた高温強度と、一段とすぐれた高温硬さおよび耐熱性を具備し、かつＢの作用で層自体の高温耐酸化性が一段と向上するようになり、したがって、硬質被覆層がかかる構成の（Ｔｉ，Ｓｉ，Ｂ）Ｎ層からなる被覆超硬工具は、各種の鋼や鋳鉄などの高熱を発生し、切刃部が高温酸化雰囲気に曝される高速切削加工でもすぐれた耐摩耗性を長期に亘って発揮するようになること。
以上（ａ）および（ｂ）に示される研究結果を得たのである。
【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、（Ｔｉ，Ｓｉ，Ｂ）Ｎからなる硬質被覆層を０．５〜１５μｍの平均層厚で物理蒸着してなる被覆超硬工具において、
上記硬質被覆層が、層厚方向にそって、Ｓｉ最高含有点とＳｉ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Ｓｉ最高含有点から前記Ｓｉ最低含有点、前記Ｓｉ最低含有点から前記Ｓｉ最高含有点へＴｉおよびＳｉ成分の含有割合がそれぞれ連続的に変化する成分濃度分布構造を有し、
さらに、上記Ｓｉ最高含有点が、組成式：［Ｔｉ_{１− （Ｘ＋Ｚ）} Ｓｉ_Ｘ Ｂ_Ｚ ］Ｎ（ただし、原子比で、Ｘは０．５０〜０．７０、Ｚは０．０１〜０．１０を示す）、
上記Ｓｉ最低含有点が、組成式：組成式：［Ｔｉ_{１− （ Ｙ ＋Ｚ）} Ｓｉ_Ｙ Ｂ_Ｚ ］（ただし、原子比で、Ｙは０．０３〜０．３０、Ｚは０．０１〜０．１０を示す）、
をそれぞれ満足し、かつ隣り合う上記Ｓｉ最高含有点とＳｉ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。
【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）Ｓｉ最高含有点の組成
Ｓｉ最高含有点の（Ｔｉ，Ｓｉ，Ｂ）ＮにおけるＴｉ成分は、高温強度を向上させ、同Ｓｉ成分は、高温硬さおよび耐熱性を向上させ、さらに同Ｂ成分は高温耐酸化性を向上させる作用があり、したがってＳｉおよびＢ成分の含有割合が高くなればなるほど高温硬さと耐熱性、さらに高温耐酸化性が向上したものになり、高熱発生を伴う高速切削に適合したものになるが、Ｓｉ成分の含有割合を示すＸ値がＴｉとＢ成分との合量に占める割合（原子比、以下同じ）で０．５０未満では、所望のすぐれた高温硬さと耐熱性を確保することができず、この結果高速切削時に十分な耐摩耗性向上効果が得られず、一方同Ｘ値が０．７０を越えると、隣接して高温強度のすぐれたＳｉ最低含有点が存在しても、Ｓｉ最高含有点が破壊の起点となってチッピングが発生し易くなることから、前記Ｘ値を０．５０〜０．７０と定めた。
また、Ｂ成分には、上記の通り高温耐酸化性を向上させ、高速切削時の高温酸化雰囲気での酸化による摩耗を抑制する作用があるが、Ｂの含有割合を示すＺ値がＴｉおよびＳｉ成分との合量に占める割合で０．０１未満では所望の高温耐酸化性向上効果が得られず、一方前記Ｚ値が０．１０を越えると高温強度が急激に低下し、切刃部にチッピングが発生し易くなることから、前記Ｚ値を０．０１〜０．１０と定めた。
【００１１】
（ｂ）Ｓｉ最低含有点の組成
上記の通りＳｉ最高含有点はすぐれた高温硬さおよび耐熱性を有するが、十分な高温強度を具備するものでないため、このＳｉ最高含有点の高温強度不足を補う目的で、Ｔｉ成分の含有割合が相対的に高く、これによって高い高温強度を有するようになるＳｉ最低含有点を厚さ方向に交互に介在させるものであるが、Ｓｉの含有割合を示すＹ値がＴｉとＢ成分との合量に占める割合で０．０３未満では、所望の高温硬さおよび耐熱性を確保することができず、Ｓｉ最高含有点が隣接して存在してもＳｉ最低含有点の摩耗が優先して進行するようになり、一方前記Ｙ値が０．３０を越えると、Ｓｉ最低含有点での高温強度が急激に低下し、チッピングが発生し易くなることから、その割合を０．０３〜０．３０と定めた。さらに、Ｓｉ最低含有点におけるＢ成分の含有割合を示すＺ値も上記のＳｉ最高含有点における理由と同じ理由で０．０１〜０．１０と定めたものである。
【００１２】
（ｃ）Ｓｉ最高含有点とＳｉ最低含有点間の間隔
その間隔が０．０１μｍ未満ではそれぞれの点を上記の組成で明確に形成することが困難であり、この結果層に所望のすぐれた高温強度と高温硬さ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Ｓｉ最高含有点であれば高温強度不足、Ｓｉ最低含有点であれば高温硬さおよび耐熱性不足が層内に局部的に現れ、これが原因で切刃部にチッピングが発生し易くなったり、摩耗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０．５μｍ未満では、所望の耐摩耗性を確保することができず、一方その平均層厚が１５μｍを越えると、切刃部にチッピングが発生し易くなることから、その平均層厚を０．５〜１５μｍ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、ＴａＣ粉末、ＶＣ粉末、ＮｂＣ粉末、Ｃｒ_３ Ｃ_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Ａ−１〜Ａ−１０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（質量比で、ＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ_２ Ｃ粉末、ＺｒＣ粉末、ＴａＣ粉末、ＮｂＣ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Ｂ−１〜Ｂ−６を形成した。
【００１６】
ついで、上記の超硬基体Ａ−１〜Ａ−１０およびＢ−１〜Ｂ−６のそれぞれを、アセトン中で超音波洗浄し、乾燥した状態で、図１に示されるアークイオンプレーティング装置内の回転テーブル上に、前記回転テーブルの中心軸から半径方向に所定距離離れた位置に外周部に沿って装着し、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Ｓｉ最低含有点形成用Ｔｉ−Ｓｉ−Ｂ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Ｓｉ最高含有点形成用Ｔｉ−Ｓｉ−Ｂ合金を前記回転テーブルを挟んで対向配置し、またカソード電極（蒸発源）としてボンバード洗浄用金属Ｔｉも装着し、まず装置内を排気して０．５Ｐａ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て、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ボンバード洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して２Ｐａの反応雰囲気とすると共に、前記回転テーブル上で自転しながら回転する超硬基体に−１００Ｖの直流バイアス電圧を印加し、かつ前記Ｓｉ最低含有点形成用Ｔｉ−Ｓｉ−Ｂ合金および前記Ｓｉ最高含有点形成用Ｔｉ−Ｓｉ−Ｂ合金のそれぞれのカソード電極とアノード電極との間には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の表面に、層厚方向に沿って表３，４に示される目標組成のＳｉ最低含有点とＳｉ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Ｓｉ最高含有点から前記Ｓｉ最低含有点、前記Ｓｉ最低含有点から前記Ｓｉ最高含有点へＴｉおよびＳｉの含有割合がそれぞれ連続的に変化する成分濃度分布構造を有し、かつ同じく表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Ａ−１〜Ａ−１０およびＢ−１〜Ｂ−６を、アセトン中で超音波洗浄し、乾燥した状態で、それぞれ図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Ｔｉ−Ｓｉ合金およびＴｉ−Ｓｉ−Ｂ合金をそれぞれ装着し、またボンバード洗浄用金属Ｔｉも装着し、まず、装置内を排気して０．５Ｐａ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、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ボンバード洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して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Ａ−１〜Ａ−１０およびＢ−１〜Ｂ−６のそれぞれの表面に、表５に示される目標組成および目標層厚を有し、かついずれも厚さ方向に沿って実質的に組成変化のない（Ｔｉ，Ｓｉ）Ｎ層または（Ｔｉ，Ｓｉ，Ｂ）Ｎ層からなる硬質被覆層を蒸着することにより、比較被覆超硬工具としての比較表面被覆超硬合金製スローアウエイチップ（以下、比較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および比較被覆超硬チップ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・ＳＮＣＭ４２０の丸棒、
切削速度：３２０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．４ｍｍ／ｒｅｖ．、
切削時間：１０分、
の条件での合金鋼の乾式連続高速切削加工試験（通常の切削速度は２５０ｍ／ｍｉｎ．）、
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：２５０ｍ／ｍｉｎ．、
切り込み：２ｍｍ、
送り：０．３ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での炭素鋼の乾式断続高速切削加工試験（通常の切削速度は２００ｍ／ｍｉｎ．）、さらに、
被削材：ＪＩＳ・ＦＣ２５０の丸棒、
切削速度：３５０ｍ／ｍｉｎ．、
切り込み：２ｍｍ、
送り：０．５ｍｍ／ｒｅｖ．、
切削時間：１０分、
の条件での鋳鉄の乾式連続高速切削加工試験（通常の切削速度は２３０ｍ／ｍｉｎ．）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［質量比で、ＴｉＣ／ＷＣ＝５０／５０］粉末、および同１．８μｍのＣｏ粉末を用意し、これら原料粉末をそれぞれ表７に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、１００ＭＰａの圧力で所定形状の各種の圧粉体にプレス成形し、これらの圧粉体を、６Ｐａの真空雰囲気中、７℃／分の昇温速度で１３７０〜１４７０℃の範囲内の所定の温度に昇温し、この温度に１時間保持後、炉冷の条件で焼結して、直径が８ｍｍ、１３ｍｍ、および２６ｍｍの３種の超硬基体形成用丸棒焼結体を形成し、さらに前記の３種の丸棒焼結体から、研削加工にて、表７に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法、並びにいずれもねじれ角３０度の４枚刃スクエアの形状をもったＷＣ基超硬合金製の超硬基体（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、層厚方向に沿って表８に示される目標組成のＳｉ最低含有点とＳｉ最高含有点とが交互に同じく表８に示される目標間隔で繰り返し存在し、かつ前記Ｓｉ最高含有点から前記Ｓｉ最低含有点、前記Ｓｉ最低含有点から前記Ｓｉ最高含有点へＴｉおよびＳｉの含有割合がそれぞれ連続的に変化する成分濃度分布構造を有し、かつ同じく表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に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表９に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ｓｉ）Ｎ層または（Ｔｉ，Ｓｉ，Ｂ）Ｎ層からなる硬質被覆層を蒸着することにより、比較被覆超硬工具としての比較表面被覆超硬合金製エンドミル（以下、比較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および比較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および比較被覆超硬エンドミル１〜３については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・Ｓ４５Ｃの板材、
切削速度：２８０ｍ／ｍｉｎ．、
軸方向切り込み：４ｍｍ、
径方向切り込み：０．５ｍｍ、
テーブル送り：１０００ｍｍ／分、
の条件での炭素鋼の乾式高速側面切削加工試験（通常の切削速度は１００ｍ／ｍｉｎ．）、本発明被覆超硬エンドミル４〜６および比較被覆超硬エンドミル４〜６については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・ＳＣＭ４４０の板材、
切削速度：２４０ｍ／ｍｉｎ．、
軸方向切り込み：８ｍｍ、
径方向切り込み：０．８ｍｍ、
テーブル送り：９００ｍｍ／分、
の条件での合金鋼の乾式高速側面切削加工試験（通常の切削速度は１００ｍ／ｍｉｎ．）、本発明被覆超硬エンドミル７，８および比較被覆超硬エンドミル７，８については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・ＳＫＤ６１の板材、
切削速度：２００ｍ／ｍｉｎ．、
軸方向切り込み：１６ｍｍ、
径方向切り込み：１ｍｍ、
テーブル送り：３５０ｍｍ／分、
の条件での工具鋼の乾式高速側面切削加工試験（通常の切削速度は６０ｍ／ｍｉｎ．）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、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、層厚方向に沿って表１０に示される目標組成のＳｉ最低含有点とＳｉ最高含有点とが交互に同じく表１０に示される目標間隔で繰り返し存在し、かつ前記Ｓｉ最高含有点から前記Ｓｉ最低含有点、前記Ｓｉ最低含有点から前記Ｓｉ最高含有点へＴｉおよびＳｉの含有割合がそれぞれ連続的に変化する成分濃度分布構造を有し、かつ同じく表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のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表１１に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ｓｉ）Ｎ層または（Ｔｉ，Ｓｉ，Ｂ）Ｎ層からなる硬質被覆層を蒸着することにより、比較被覆超硬工具としての比較表面被覆超硬合金製ドリル（以下、比較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および比較被覆超硬ドリル１〜８のうち、本発明被覆超硬ドリル１〜３および比較被覆超硬ドリル１〜３については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・ＳＣＭ４２０の板材、
切削速度：１５０ｍ／ｍｉｎ．、
送り：０．１１ｍｍ／ｒｅｖ．、
穴深さ：６ｍｍ．、
の条件での合金鋼の湿式高速穴あけ切削加工試験（通常の切削速度は６０ｍ／ｍｉｎ．）、本発明被覆超硬ドリル４〜６および比較被覆超硬ドリル４〜６については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・ＦＣ２００の板材、
切削速度：１８０ｍ／ｍｉｎ．、
送り：０．２１ｍｍ／ｒｅｖ．、
穴深さ：１５ｍｍ．、
の条件での鋳鉄の湿式高速穴あけ切削加工試験（通常の切削速度は８０ｍ／ｍｉｎ．）、本発明被覆超硬ドリル７，８および比較被覆超硬ドリル７，８については、
被削材−平面：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍの寸法をもったＪＩＳ・Ｓ４８Ｃの板材、
切削速度：１４０ｍ／ｍｉｎ．、
送り：０．２５ｍｍ／ｒｅｖ．、
穴深さ：３０ｍｍ．、
の条件での炭素鋼の湿式高速穴あけ切削加工試験（通常の切削速度は６０ｍ／ｍｉｎ．）、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Ｓｉ最低含有点とＳｉ最高含有点の組成、並びに比較被覆超硬工具としての比較被覆超硬チップ１〜１６、比較被覆超硬エンドミル１〜８、および比較被覆超硬ドリル１〜８の硬質被覆層の組成について、厚さ方向に沿ってＴｉ、Ｓｉ、およびＢ成分の含有量をオージェ分光分析装置を用いて測定したところ、本発明被覆超硬工具の硬質被覆層では、Ｓｉ最低含有点とＳｉ最高含有点とがそれぞれ目標値と実質的に同じ組成および間隔で交互に繰り返し存在し、かつ前記Ｓｉ最低含有点から前記Ｓｉ最高含有点、前記Ｓｉ最高含有点から前記Ｓｉ最低含有点へＴｉおよびＳｉ成分の含有割合がそれぞれ連続的に変化する成分濃度分布構造を有することが確認され、また硬質被覆層の平均層厚（５ヶ所の平均値）も目標層厚と実質的に同じ値を示した。
一方前記比較被覆超硬工具の硬質被覆層では厚さ方向に沿って組成変化が見られず、かつ目標組成と実質的に同じ組成および目標層厚と実質的に同じ平均層厚（５ヶ所の平均値）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、厚さ方向に、きわめてすぐれた高温硬さと耐熱性を有するＳｉ最高含有点とすぐれた高温強度を有するＳｉ最低含有点とが交互に所定間隔をおいて繰り返し存在し、かつ前記Ｓｉ最低含有点から前記Ｓｉ最高含有点、前記Ｓｉ最高含有点から前記Ｓｉ最低含有点へＴｉおよびＳｉの含有割合がそれぞれ連続的に変化する成分濃度分布構造を有し、この成分濃度分布構造によって層全体に亘ってきわめてすぐれた高温硬さおよび耐熱性と、すぐれた高温強度を有するようになり、さらにＢによりすぐれた高温耐酸化性も具備する硬質被覆層を形成してなる本発明被覆超硬工具は、いずれも各種の鋼や鋳鉄の高熱発生を伴なう高速切削加工で、すぐれた耐摩耗性を発揮するのに対して、硬質被覆層がいずれも厚さ方向に沿って実質的に組成変化のない（Ｔｉ，Ｓｉ）Ｎ層または（Ｔｉ，Ｓｉ，Ｂ）Ｎ層からなる比較被覆超硬工具においては、高熱発生を伴なう高速切削加工では、前記硬質被覆層の高温硬さおよび耐熱性不足が原因で、いずれも摩耗進行が速く、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、通常の条件での鋼や鋳鉄などの切削加工は勿論のこと、特に高熱発生を伴なう高速切削加工でも、すぐれた耐摩耗性を示し、長期に亘ってすぐれた切削性能を発揮するものであるから、切削加工装置の高性能化、並びに切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。
【図面の簡単な説明】
【図１】この発明の被覆超硬工具を構成する硬質被覆層の形成に用いたアークイオンプレーティング装置を示し、（ａ）は概略平面図、（ｂ）は概略正面図である。
【図２】通常のアークイオンプレーティング装置の概略説明図である。[0001]
BACKGROUND OF THE INVENTION
The present invention has excellent high-temperature hardness and heat resistance with a hard coating layer, and also has excellent high-temperature strength. Therefore, it is superior in high-speed cutting with high heat generation such as various steels and cast iron. The present invention relates to a surface-coated cemented carbide cutting tool that exhibits wear resistance (hereinafter referred to as a coated carbide tool).
[0002]
[Prior art]
In general, coated carbide tools include a throw-away tip that is attached to the tip of a cutting tool for turning and planing of various steels and cast irons, and drilling of the work material. There are drills and miniature drills used for processing, etc., and solid type end mills used for chamfering, grooving, shoulder processing, etc. of the work material. A slow-away end mill tool that performs cutting work in the same manner as a type end mill is known.
[0003]
In addition, as a coated carbide tool, on the surface of a carbide substrate made of tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet,
Composition formula: [Ti _{1 -A} Si _A ] N (however, in atomic ratio, A represents 0.01 to 0.45),
There is known a coated carbide tool formed by physical vapor deposition of a hard coating layer made of a composite nitride of Ti and Si satisfying the following [hereinafter referred to as (Ti, Si) N] with an average layer thickness of 0.5 to 15 μm. In this coated carbide tool, the (Ti, Si) N layer, which is a hard coating layer, has high-temperature strength due to the Ti component and high-temperature hardness and heat resistance due to the Si component. It is also well known that it is used for continuous cutting and intermittent cutting such as (see, for example, Patent Document 1).
[0004]
Furthermore, the above-mentioned coated carbide tool is, for example, the above-mentioned carbide substrate is inserted into an arc ion plating apparatus which is one type of physical vapor deposition apparatus schematically shown in FIG. For example, an arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) on which a Ti—Si alloy having various compositions is set, for example, at a current of 100 A, while being heated to a temperature of 500 ° C. At the same time, a mixed gas of nitrogen gas is introduced into the apparatus as a reaction gas to obtain a reaction atmosphere of, for example, 2.5 Pa. On the other hand, the carbide substrate is subjected to, for example, a bias voltage of −100 V, for example. It is also known that a hard coating layer composed of a (Ti, Si) N layer is deposited on the surface of a hard substrate with an average layer thickness of 0.5 to 15 μm.
[0005]
[Patent Document 1]
JP-A-8-118106 [0006]
[Problems to be solved by the invention]
In recent years, the performance of cutting machines has been remarkable. On the other hand, there are strong demands for labor saving, energy saving and cost reduction for cutting, and with this, cutting tends to increase in speed. In a conventional coated carbide tool whose coating layer is a (Ti, Si) N layer, there is no problem when this is used under normal cutting conditions, but this is not possible under high-speed cutting conditions with high heat generation. When used, the progress of wear is further accelerated due to the high temperature hardness and insufficient heat resistance of the hard coating layer, and the service life is reached in a relatively short time.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors configured the above conventional coated carbide tool in order to develop a coated carbide tool exhibiting excellent wear resistance with a hard coating layer particularly in high-speed cutting. As a result of conducting research with a focus on the hard coating layer,
(A) The (Ti, Si) N layer constituting the hard coating layer of the conventional coated carbide tool formed using the arc ion plating apparatus shown in FIG. 2 is homogeneous over the entire layer thickness. Although it has high-temperature strength, high-temperature hardness and heat resistance, 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. Ti-- which is provided as a cathode electrode (evaporation source) for forming the above-described conventional (Ti, Si) N layer on one side with a turntable for mounting a carbide substrate and sandwiching the turntable. Ti-Si-B alloy with Si content corresponding to the low Si content side of the Si alloy and Ti-Si-B alloy with relatively high Si content facing the other side as cathode electrodes (evaporation sources), respectively Using the arranged device, A plurality of cemented carbide substrates are mounted in a ring shape along the outer peripheral portion at a position spaced apart from the central axis of the rotary table by a predetermined distance in the radial direction on the rotary table of the apparatus, and in this state, the reaction atmosphere in the apparatus While rotating the rotary table in a nitrogen atmosphere and rotating the carbide substrate itself for the purpose of uniforming the thickness of the hard coating layer to be deposited, the Ti-Si having a relatively low Si content is used. An arc discharge is generated between a cathode electrode and an anode electrode of a Ti-Si-B alloy having a relatively high Si content and a composite nitriding of Ti, Si and B on the surface of the cemented carbide substrate. When a product [hereinafter referred to as (Ti, Si, B) N] layer is formed, in the resulting (Ti, Si, B) N layer, the carbide substrate arranged in a ring shape on the rotary table is Above one side relative When the closest to the cathode electrode of the Ti-Si-B alloy having a high Si content, the highest Si content point is formed in the layer, and the carbide substrate has a relatively low Si content on the other side. At the point closest to the cathode electrode of the Ti—Si—B alloy, the lowest Si content point is formed in the layer, and by the rotation of the rotary table, the highest Si content point and the lowest Si point are formed in the layer along the layer thickness direction. Components in which content points repeatedly appear alternately at predetermined intervals, and the content ratios of Ti and Si continuously change from the Si maximum content point to the Si minimum content point and from the Si minimum content point to the Si maximum content point, respectively. Have a concentration distribution structure.
[0008]
(B) In the (Ti, Si, B) N layer having the repeated continuous change component concentration distribution structure of (a) above, for example, the Ti-Si-B alloy for forming the Si highest content point and the Si lowest content point formation of the opposing arrangement While preparing each composition of Ti-Si-B alloy for use, and controlling the rotational speed of the rotary table on which the carbide substrate is mounted,
The Si highest content point is the composition formula: [Si _{1− (X + Z)} Ti _X B _Z ] N (wherein X is 0.50 to 0.70 and Z is 0.01 to 0.10 in atomic ratio), and the Si minimum content point is the composition formula: [Ti _{1− ( Y + Z) Si Y B Z]} N ( provided that an atomic ratio, Y is 0.03 to 0.30, Z represents a 0.01-0.10)
And the distance in the thickness direction of the adjacent Si highest content point and Si lowest content point adjacent to each other is 0.01 to 0.1 μm,
In the Si highest content point portion, since the Si content in the (Ti, Si, B) N layer is relatively high and the Ti content is low, higher temperature hardness and heat resistance are exhibited, The Si lowest content point portion has a lower Si content and a higher Ti content than the Si highest content point portion, so that it has a relatively high high temperature strength, that is, the conventional (Ti, Si) N layer. The high temperature strength equivalent to the high temperature strength of is secured, and the interval between the Si highest content point and the Si lowest content point is made extremely small. Therefore, the high temperature strength that is superior as the characteristics of the entire layer, and the excellent high temperature hardness and A coated carbide tool comprising a (Ti, Si, B) N layer having a heat resistance, and the high-temperature oxidation resistance of the layer itself is further improved by the action of B, and thus a hard coating layer is applied. Each Of high heat, such as steel or cast iron occurs, be like cutting edge exerts a long term wear resistance excellent in high-speed cutting machining is exposed to high-temperature oxidizing atmosphere.
The research results shown in (a) and (b) above were obtained.
[0009]
The present invention has been made based on the above research results. A hard coating layer made of (Ti, Si, B) N is physically applied to the surface of a cemented carbide substrate with an average layer thickness of 0.5 to 15 μm. In coated carbide tools formed by vapor deposition,
In the hard coating layer, the Si highest content point and the Si lowest content point are alternately present at predetermined intervals along the layer thickness direction, and from the Si highest content point, the Si lowest content point, the Si A component concentration distribution structure in which the content ratios of Ti and Si components continuously change from the lowest content point to the Si highest content point, respectively,
Furthermore, the Si maximum content point is the composition formula: [Ti _{1− (X + Z)} Si _X B _Z] N (provided that an atomic ratio, X is 0.50 to 0.70, Z represents a 0.01-0.10)
The Si minimum content point, composition formula: _{formula: [Ti 1- (Y + Z} ) Si Y B Z] ( however, in atomic ratio, Y is 0.03 to 0.30, Z is from 0.01 to 0 .10),
And the interval between the adjacent Si highest content point and Si lowest content point adjacent to each other is 0.01 to 0.1 μm.
It is characterized by a coated carbide tool that exhibits excellent wear resistance with a hard coating layer in high-speed cutting.
[0010]
Next, in the coated carbide tool of the present invention, the reason why the structure of the hard coating layer constituting the tool is limited as described above will be described.
(A) Composition of Si highest content point The Ti component in (Ti, Si, B) N having the highest Si content point improves the high temperature strength, and the Si component improves the high temperature hardness and heat resistance. The B component has the effect of improving the high temperature oxidation resistance. Therefore, the higher the content ratio of Si and B components, the higher the high temperature hardness and heat resistance, and the higher the high temperature oxidation resistance. Although it is suitable for cutting, if the X value indicating the Si component content ratio is less than 0.50 in terms of the total amount of Ti and B components (atomic ratio, the same shall apply hereinafter), the desired excellent high-temperature hardness As a result, a sufficient wear resistance improvement effect cannot be obtained during high-speed cutting. On the other hand, if the X value exceeds 0.70, the Si minimum with excellent high-temperature strength is adjacent. Even if there is a content point, the highest Si content Points are determined from chipping become starting points of fracture is likely to occur, the X value as 0.50 to 0.70.
In addition, the B component has an effect of improving high-temperature oxidation resistance as described above and suppressing wear due to oxidation in a high-temperature oxidizing atmosphere during high-speed cutting, but the Z value indicating the content ratio of B is Ti and Si. If the ratio to the total amount with the component is less than 0.01, the desired high-temperature oxidation resistance improvement effect cannot be obtained. On the other hand, if the Z value exceeds 0.10, the high-temperature strength decreases rapidly, Since the chipping is likely to occur, the Z value is set to 0.01 to 0.10.
[0011]
(B) Composition of the lowest Si content point As mentioned above, the highest Si content point has excellent high-temperature hardness and heat resistance, but does not have sufficient high-temperature strength. For the purpose of supplementing, the content ratio of the Ti component is relatively high, and thereby the Si minimum content point that has a high high-temperature strength is alternately interposed in the thickness direction. If the value is less than 0.03 as a proportion of the total amount of Ti and B components, the desired high-temperature hardness and heat resistance cannot be ensured, and even if the Si highest content point exists adjacently, the Si minimum On the other hand, the wear of the content point proceeds preferentially. On the other hand, if the Y value exceeds 0.30, the high temperature strength at the Si minimum content point rapidly decreases and chipping is likely to occur. The ratio is fixed as 0.03 to 0.30 It was. Furthermore, Z value which shows the content rate of B component in Si minimum content point is also defined as 0.01-0.10 for the same reason as said Si maximum content point.
[0012]
(C) Interval between the highest Si content point and the lowest Si content point If the distance is less than 0.01 μm, it is difficult to clearly form each point with the above composition. As a result, the layer has a desired excellent high temperature. Strength and high temperature hardness cannot be ensured, and if the distance exceeds 0.1 μm, each point has a defect, that is, if the Si maximum content point is insufficient, the high temperature strength is insufficient, if the Si minimum content point is high temperature Insufficient hardness and heat resistance appear locally in the layer, which makes it easier for chipping to occur at the cutting edge and promotes wear. 1 μm was determined.
[0013]
(D) Average layer thickness of hard coating layer If the layer thickness is less than 0.5 μm, the desired wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 15 μm, chipping occurs at the cutting edge. Since it becomes easy to generate | occur | produce, the average layer thickness was set to 0.5-15 micrometers.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated carbide tool of the present invention will be specifically described with reference to examples.
(Example 1)
As raw material powders, WC powder, TiC powder, TaC powder, VC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder all having an average particle diameter of 1 to 3 μm were prepared. And then wet-mixed with a ball mill for 72 hours, dried, and press-molded into a green compact at a pressure of 100 MPa. The green compact was vacuumed at 6 Pa at a temperature of 1400 ° C. for 1 hour. Sintered under holding conditions, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03, and a cemented carbide substrate A-1 made of WC-based cemented carbide having a chip shape of ISO standard / CNMG120408 ~ A-10 was formed.
[0015]
In addition, as raw material powders, all TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, TaC powder, NbC powder, WC having an average particle diameter of 0.5 to 2 μm Prepare powder, Co powder, and Ni powder, mix these raw material powders into the composition shown in Table 2, wet mix for 24 hours with a ball mill, dry, and press-mold into green compact at 100 MPa pressure The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to meet ISO standards / TiCN-based cermet carbide substrates B-1 to B-6 having a chip shape of CNMG120408 were formed.
[0016]
Next, each of the above-mentioned carbide substrates A-1 to A-10 and B-1 to B-6 was ultrasonically cleaned in acetone and dried, and then in the arc ion plating apparatus shown in FIG. Is mounted along the outer peripheral portion at a predetermined distance in the radial direction from the central axis of the rotary table, and a Si minimum having various component compositions as a cathode electrode (evaporation source) on one side Ti-Si-B alloy for content point formation and Ti-Si-B alloy for Si highest content point formation having various composition as opposed cathode electrode (evaporation source) on opposite sides of the rotary table Also, a bombard cleaning metal Ti is mounted as a cathode electrode (evaporation source), and the apparatus is first heated to 500 ° C. with a heater while evacuating the apparatus and maintaining a vacuum of 0.5 Pa or less. rotation A DC bias voltage of −1000 V is applied to a carbide substrate that rotates while rotating on a table, and a current of 100 A is passed between the metal Ti and the anode electrode of the cathode electrode to generate an arc discharge. The surface of the hard substrate is cleaned with Ti bombardment, and then nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 2 Pa. A DC bias voltage of −100 V is applied to the carbide substrate that rotates while rotating on the rotary table. And a current of 100 A is passed between the cathode electrode and the anode electrode of the Ti-Si-B alloy for forming the lowest Si content point and the Ti-Si-B alloy for forming the highest Si content point. Arc discharge is generated, and the lowest Si content point and the highest Si content of the target composition shown in Tables 3 and 4 along the layer thickness direction are formed on the surface of the cemented carbide substrate. Ti and Si are alternately present at the target intervals shown in Tables 3 and 4 alternately and from the Si highest content point to the Si lowest content point, and from the Si lowest content point to the Si highest content point. The surface coating of the present invention as a coated carbide tool of the present invention is formed by depositing a hard coating layer having a component concentration distribution structure in which the ratio continuously changes and also having a target layer thickness shown in Tables 3 and 4 Cemented carbide alloy throwaway tips (hereinafter referred to as the present invention coated carbide tips) 1 to 16 were produced, respectively.
[0017]
For comparison purposes, these carbide substrates A-1 to A-10 and B-1 to B-6 were ultrasonically cleaned in acetone and dried, and each of the ordinary arcs shown in FIG. First, the Ti-Si alloy and Ti-Si-B alloy having various component compositions were mounted as cathode electrodes (evaporation sources), respectively, and a bombard cleaning metal Ti was also mounted. The inside of the apparatus was heated to 500 ° C. with a heater while the inside of the apparatus was evacuated and kept at a vacuum of 0.5 Pa or less, and then a −1000 V DC bias voltage was applied to the cemented carbide substrate, and the cathode electrode An arc discharge is generated by passing a current of 100 A between the metal Ti and the anode electrode, thereby cleaning the surface of the carbide substrate with Ti bombardment, and then introducing nitrogen gas as a reaction gas into the apparatus. and a bias voltage applied to the cemented carbide substrate is lowered to −100 V to generate an arc discharge between the cathode electrode and the anode electrode, whereby the cemented carbide substrates A-1 to A -10 and B-1 to B-6 have the target composition and target layer thickness shown in Table 5 on the respective surfaces, and both have substantially no composition change along the thickness direction (Ti, By depositing a hard coating layer comprising a Si) N layer or a (Ti, Si, B) N layer, a comparative surface-coated cemented carbide throwaway tip (hereinafter referred to as a comparative coated carbide tip) as a comparative coated carbide tool. 1 to 16 were produced.
[0018]
Next, with the present invention coated carbide chips 1-16 and comparative coated carbide chips 1-16, in a state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SNCM420 round bar,
Cutting speed: 320 m / min. ,
Incision: 1.5mm,
Feed: 0.4 mm / rev. ,
Cutting time: 10 minutes,
Dry continuous high speed cutting test of alloy steel under the conditions of (normal cutting speed is 250 m / min.),
Work material: JIS / S50C lengthwise equal 4 round grooved round bars,
Cutting speed: 250 m / min. ,
Cutting depth: 2mm,
Feed: 0.3 mm / rev. ,
Cutting time: 5 minutes
Carbon steel under the conditions of dry intermittent high speed cutting test (normal cutting speed is 200 m / min.),
Work material: JIS / FC250 round bar,
Cutting speed: 350 m / min. ,
Cutting depth: 2mm,
Feed: 0.5 mm / rev. ,
Cutting time: 10 minutes,
The dry continuous high-speed cutting test of cast iron under the conditions (normal cutting speed is 230 m / min.) Was performed, and the flank wear width of the cutting edge was measured in any turning test. The measurement results are shown in Table 6.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
[Table 3]

[0022]
[Table 4]

[0023]
[Table 5]

[0024]
[Table 6]

[0025]
(Example 2)
As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, ZrC of 1.2 μm Powder, 2.3 μm Cr ₃ C ₂ powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C [by mass ratio, TiC / WC = 50/50] powder, and 1 Prepare 8 .mu.m Co powder, mix these raw material powders with the composition shown in Table 7, add wax, ball mill in acetone for 24 hours, dry under reduced pressure, and then press at a pressure of 100 MPa. The green compacts were press-molded, and these green compacts were heated to a predetermined temperature in the range of 1370 to 1470 ° C. at a rate of temperature increase of 7 ° C./min in a 6 Pa vacuum atmosphere. After holding at temperature for 1 hour, sintering under furnace cooling conditions Then, three kinds of sintered carbide rod forming bodies for forming a carbide substrate having diameters of 8 mm, 13 mm, and 26 mm were formed, and further, the three kinds of sintered rods for round bar were ground and shown in Table 7. WC-based carbide with a 4-blade square shape with a diameter x length of 6 mm x 13 mm, 10 mm x 22 mm, and 20 mm x 45 mm, respectively, and a twist angle of 30 degrees. Alloy carbide substrates (end mills) C-1 to C-8 were produced.
[0026]
Then, the surfaces of these carbide substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and then charged into the arc ion plating apparatus shown in FIG. Under the same conditions as in Example 1, the Si minimum content point and the Si maximum content point of the target composition shown in Table 8 along the layer thickness direction are alternately present at the target interval shown in Table 8 alternately, and It has a component concentration distribution structure in which the content ratios of Ti and Si continuously change from the Si highest content point to the Si lowest content point, and from the Si lowest content point to the Si highest content point, respectively. By vapor-depositing a hard coating layer having the target layer thickness shown, end mills made of the surface coated cemented carbide of the present invention (hereinafter referred to as the present coated carbide end mill) 1 to 8 as the coated carbide tool of the present invention are produced. Shi .
[0027]
For the purpose of comparison, the surfaces of the above-mentioned carbide substrates (end mills) C-1 to C-8 are ultrasonically cleaned in acetone and dried, and the arc ion plating apparatus shown in FIG. (Ti, Si) N layer that is charged and has the target composition and target layer thickness shown in Table 9 under the same conditions as in Example 1 and substantially no composition change along the layer thickness direction. Alternatively, a comparative surface-coated cemented carbide end mill (hereinafter referred to as a comparative coated carbide end mill) 1 to 8 as a comparative coated carbide tool is deposited by vapor-depositing a hard coating layer composed of a (Ti, Si, B) N layer. Were manufactured respectively.
[0028]
Next, of the present invention coated carbide end mills 1-8 and comparative coated carbide end mills 1-8, the present invention coated carbide end mills 1-3 and comparative coated carbide end mills 1-3 are as follows:
Work material-plane: 100 mm x 250 mm, thickness: 50 mm JIS S45C plate material,
Cutting speed: 280 m / min. ,
Axial cut: 4 mm
Radial notch: 0.5mm,
Table feed: 1000 mm / min,
The dry high-speed side cutting test of carbon steel under the conditions (normal cutting speed is 100 m / min.), The coated carbide end mills 4 to 6 of the present invention and the comparative coated carbide end mills 4 to 6
Work material-Plane: 100 mm × 250 mm, thickness: 50 mm, JIS / SCM440 plate,
Cutting speed: 240 m / min. ,
Axial cut: 8mm,
Radial notch: 0.8mm,
Table feed: 900 mm / min,
With respect to the dry high-speed side cutting test of the alloy steel under the conditions (normal cutting speed is 100 m / min.), The coated carbide end mills 7 and 8 of the present invention and the comparative coated carbide end mills 7 and 8 are as follows:
Work material-Plane: 100 mm x 250 mm, JIS SKD61 plate material with thickness: 50 mm,
Cutting speed: 200 m / min. ,
Axial cut: 16mm,
Radial notch: 1mm,
Table feed: 350 mm / min,
The dry high-speed side cutting test of the tool steel under the above conditions (normal cutting speed is 60 m / min.) Is performed, and the flank wear width of the outer peripheral edge of the cutting edge is the service life in any side cutting test. The cutting length up to 0.1 mm, which is a standard, was measured. The measurement results are shown in Tables 8 and 9, respectively.
[0029]
[Table 7]

[0030]
[Table 8]

[0031]
[Table 9]

[0032]
(Example 3)
The diameters produced in Example 2 above were 8 mm (for forming carbide substrates C-1 to C-3), 13 mm (for forming carbide substrates C-4 to C-6), and 26 mm (for carbide substrates C-). 7, for C-8 formation), from these three types of round bar sintered bodies, the diameter x length of the groove forming portion is 4 mm x 13 mm (by grinding), respectively. Carbide substrates D-1 to D-3), 8 mm × 22 mm (Carbide substrates D-4 to D-6), and 16 mm × 45 mm (Carbide substrates D-7 and D-8), and all Carbide substrates (drills) D-1 to D-8 having a two-blade shape with a twist angle of 30 degrees were manufactured.
[0033]
Next, the cutting edges of these carbide substrates (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone and dried, and then mounted on the arc ion plating apparatus of FIG. Then, under the same conditions as in Example 1 above, the lowest Si content point and the highest Si content point of the target composition shown in Table 10 along the layer thickness direction are alternately repeated at the target interval shown in Table 10 as well. And a component concentration distribution structure in which the content ratio of Ti and Si continuously changes from the Si highest content point to the Si lowest content point, from the Si lowest content point to the Si highest content point, and Similarly, by depositing a hard coating layer having a target layer thickness shown in Table 10, a drill made of the surface coated cemented carbide of the present invention (hereinafter referred to as the present coated carbide drill) 1 to 1 as the coated carbide tool of the present invention. 8 each And elephants.
[0034]
For comparison purposes, the cutting edges of the above-mentioned carbide substrates (drills) D-1 to D-8 are honed, ultrasonically cleaned in acetone, and dried, and the arc ions shown in FIG. In the plating apparatus, under the same conditions as in Example 1, the target composition and the target layer thickness shown in Table 11 are obtained, and there is substantially no composition change along the layer thickness direction (Ti, By vapor-depositing a hard coating layer comprising a Si) N layer or a (Ti, Si, B) N layer, a comparative surface-coated cemented carbide drill as a comparative coated carbide tool (hereinafter referred to as a comparative coated carbide drill). ) 1-8 were produced respectively.
[0035]
Next, of the present invention coated carbide drills 1-8 and comparative coated carbide drills 1-8, for the present invention coated carbide drills 1-3 and comparative coated carbide drills 1-3,
Work material-Plane: 100 mm x 250 mm, JIS SCM420 plate material with thickness: 50 mm,
Cutting speed: 150 m / min. ,
Feed: 0.11 mm / rev. ,
Hole depth: 6 mm. ,
About the wet high-speed drilling test of alloy steel under the conditions of (normal cutting speed is 60 m / min.), The present invention coated carbide drills 4-6 and comparative coated carbide drills 4-6,
Work material-Plane: 100 mm x 250 mm, thickness: 50 mm plate material of JIS / FC200,
Cutting speed: 180 m / min. ,
Feed: 0.21 mm / rev. ,
Hole depth: 15 mm. ,
With regard to the cast iron wet high speed drilling cutting test under the conditions (normal cutting speed is 80 m / min.), The present invention coated carbide drills 7 and 8 and the comparative coated carbide drills 7 and 8,
Work material-Plane: 100 mm x 250 mm, thickness: 50 mm JIS / S48C plate material,
Cutting speed: 140 m / min. ,
Feed: 0.25 mm / rev. ,
Hole depth: 30 mm. ,
Each of the wet high-speed drilling tests (normal cutting speed is 60 m / min.) Of carbon steel under the above conditions is performed, and any wet high-speed drilling test (using water-soluble cutting oil) The number of drilling processes until the flank wear width reached 0.3 mm was measured. The measurement results are shown in Tables 10 and 11, respectively.
[0036]
[Table 10]

[0037]
[Table 11]

[0038]
In the hard coating layer which comprises this invention coated carbide tips 1-16, this invention coated carbide end mills 1-8, and this invention coated carbide drills 1-8 as this invention coated carbide tool obtained as a result. Composition of lowest Si content point and highest Si content point, and comparative coated carbide tips 1-16 as comparative coated carbide tools, comparative coated carbide end mills 1-8, and hard coating of comparative coated carbide drills 1-8 Regarding the composition of the layer, the contents of Ti, Si, and B components were measured along the thickness direction using an Auger spectroscopic analyzer. In the hard coating layer of the coated carbide tool of the present invention, The Si highest content point alternately and repeatedly exists at substantially the same composition and interval as the target value, and from the Si lowest content point to the Si highest content point and from the Si highest content point to the Si lowest content point It has been confirmed that each of the i and Si component content ratios has a component concentration distribution structure that changes continuously, and the average thickness (average value of five locations) of the hard coating layer is substantially the same as the target layer thickness. showed that.
On the other hand, in the hard coating layer of the comparative coated carbide tool, no composition change is observed along the thickness direction, and the composition is substantially the same as the target composition and the average layer thickness is substantially the same as the target layer thickness (at five locations). (Average value) was confirmed.
[0039]
【The invention's effect】
From the results shown in Tables 3 to 11, in the thickness direction, the highest Si content point having excellent high temperature hardness and heat resistance and the lowest Si content point having excellent high temperature strength were alternately repeated at predetermined intervals. And having a component concentration distribution structure in which the content ratios of Ti and Si continuously change from the Si lowest content point to the Si highest content point, and from the Si highest content point to the Si lowest content point, respectively. The component concentration distribution structure forms a hard coating layer that has excellent high-temperature hardness and heat resistance and excellent high-temperature strength throughout the entire layer, and B also has excellent high-temperature oxidation resistance. The coated carbide tool of the present invention is excellent in wear resistance in high-speed cutting with high heat generation of various steels and cast irons, whereas the hard coating layer is thick. In a comparative coated carbide tool composed of a (Ti, Si) N layer or a (Ti, Si, B) N layer having substantially no composition change along the direction, in high-speed cutting with high heat generation, It is clear that due to the high temperature hardness and insufficient heat resistance of the hard coating layer, both wear progresses quickly and reaches the service life in a relatively short time.
As described above, the coated carbide tool of the present invention exhibits excellent wear resistance not only in cutting of steel and cast iron under normal conditions, but particularly in high-speed cutting with high heat generation. Since it exhibits excellent cutting performance over a long period of time, it can sufficiently satisfy the high performance of the cutting device, the labor saving and energy saving of the cutting work, 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 diagram of a normal arc ion plating apparatus.

Claims (1)

炭化タングステン基超硬合金または炭窒化チタン系サーメットからなる超硬基体の表面に、ＴｉとＳｉとＢ（ボロン）の複合窒化物からなる硬質被覆層を０．５〜１５μｍの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して、
上記硬質被覆層が、層厚方向にそって、Ｓｉ最高含有点とＳｉ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Ｓｉ最高含有点から前記Ｓｉ最低含有点、前記Ｓｉ最低含有点から前記Ｓｉ最高含有点へＴｉおよびＳｉの含有割合がそれぞれ連続的に変化する成分濃度分布構造を有し、
さらに、上記Ｓｉ最高含有点が、組成式：［Ｔｉ_{１− （Ｘ＋Ｚ）} Ｓｉ_Ｘ Ｂ_Ｚ ］Ｎ（ただし、原子比で、Ｘは０．５０〜０．７０、Ｚは０．０１〜０．１０を示す）、
上記Ｓｉ最低含有点が、組成式：［Ｔｉ_{１− （ Ｙ ＋Ｚ）} Ｓｉ_Ｙ Ｂ_Ｚ ］Ｎ（ただし、原子比で、Ｙは０．０３〜０．３０、Ｚは０．０１〜０．１０を示す）、
をそれぞれ満足し、かつ隣り合う上記Ｓｉ最高含有点とＳｉ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。A hard coating layer made of a composite nitride of Ti, Si, and B (boron) is physically applied with an average layer thickness of 0.5 to 15 μm on the surface of a cemented carbide substrate made of tungsten carbide base cemented carbide or titanium carbonitride cermet. A surface-coated cemented carbide cutting tool made by vapor deposition,
In the hard coating layer, the Si highest content point and the Si lowest content point are alternately present at predetermined intervals along the layer thickness direction, and from the Si highest content point, the Si lowest content point, the Si A component concentration distribution structure in which the content ratios of Ti and Si continuously change from the lowest content point to the Si highest content point, respectively,
Furthermore, the Si maximum content point is the composition formula: [Ti _{1− (X + Z)} Si _X B _Z] N (provided that an atomic ratio, X is 0.50 to 0.70, Z represents a 0.01-0.10)
The Si minimum content point, composition _{formula: [Ti 1- (Y + Z} ) Si Y B Z] N ( provided that an atomic ratio, Y is 0.03 to 0.30, Z is 0.01-0.10 ),
And the interval between the Si highest content point and the Si lowest content point adjacent to each other is 0.01 to 0.1 μm,
A surface-coated cemented carbide cutting tool that exhibits excellent wear resistance with a hard coating layer in high-speed cutting.

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