JP4375527B2

JP4375527B2 - Cutting tool made of surface-coated cemented carbide that exhibits excellent chipping resistance under high-speed heavy cutting conditions.

Info

Publication number: JP4375527B2
Application number: JP2003139712A
Authority: JP
Inventors: 浩一前田; 裕介田中
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2003-05-19
Filing date: 2003-05-19
Publication date: 2009-12-02
Anticipated expiration: 2023-05-19
Also published as: JP2004338058A

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強度を有し、かつ高温硬さと耐熱性、さらに耐熱塑性変形性にもすぐれ、したがって特に各種の鋼や鋳鉄などの高い発熱を伴なう高速切削加工を、高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング性を発揮する表面被覆超硬合金製切削工具（以下、被覆超硬工具という）に関するものである。
【０００２】
【従来の技術】
一般に、被覆超硬工具には、各種の鋼や鋳鉄などの被削材の旋削加工や平削り加工にバイトの先端部に着脱自在に取り付けて用いられるスローアウエイチップ、穴あけ切削加工などに用いられるドリルやミニチュアドリル、さらに面削加工や溝加工、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：（Ｔｉ_1- _ＡＳｉ_Ａ）Ｎ（ただし、原子比で、Ａは０．４５〜０．６０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］層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提案され、かかる被覆超硬工具が、硬質被覆層を構成する前記（Ｔｉ，Ｓｉ）Ｎ層がＳｉによるすぐれた高温硬さおよび耐熱性、さらにＴｉによるすぐれた高温強度を有することから、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知られている（例えば特許文献１参照）。
【０００４】
さらに、上記の被覆超硬工具が、例えば図２に概略説明図で示される物理蒸着装置の１種であるアークイオンプレーティング装置に上記の超硬基体を装入し、ヒータで装置内を、例えば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：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−２００Ｖ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、上記（Ｔｉ，Ｓｉ）Ｎ層からなる硬質被覆層を蒸着することにより製造されることも知られている。
【０００５】
【特許文献１】
特開平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は強く、これに伴い、切削速度は高速化し、かつ高切り込みや高送りなどの重切削条件での切削加工が強く求められる傾向にあるが、上記の従来被覆超硬工具においては、これを通常の切削加工条件で用いた場合には問題はないが、高い発熱を伴なう高速切削加工を機械的衝撃の高い高切り込みや高送りなどの重切削条件で行なった場合には、特に硬質被覆層の高温強度不足が原因でチッピング（微小割れ）が発生し易く、比較的短時間で使用寿命に至るのが現状である。
【０００７】
【課題を解決するための手段】
そこで、本発明者等は、上述のような観点から、特に高速重切削加工で硬質被覆層がすぐれた耐チッピング性を発揮する被覆超硬工具を開発すべく、上記の従来被覆超硬工具を構成する硬質被覆層に着目し、研究を行った結果、
（ａ）上記の図２に示されるアークイオンプレーティング装置を用いて形成された従来被覆超硬工具を構成する（Ｔｉ，Ｓｉ）Ｎ層は、厚さ全体に亘って実質的に均一な組成を有し、したがって均質な性質を有するが、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（Ｔｉ，Ｓｉ）Ｎ層の形成にカソード電極（蒸発源）として用いられたＴｉ−Ｓｉ合金に、さらにＹ成分を合金成分として含有させてなるＴｉ−Ｓｉ−Ｙ合金を配置し、他方側には前記Ｔｉ−Ｓｉ−Ｙ合金に比して相対的にＳｉ含有割合の低いＴｉ−Ｓｉ−Ｙ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上に、中心軸から半径方向に所定距離離れた位置に外周部に沿って複数の超硬基体をリング状に装着し、この状態で装置内雰囲気を窒素雰囲気として前記回転テーブルを回転させると共に、蒸着形成される硬質被覆層の層厚均一化を図る目的で超硬基体自体も自転させながら、前記の両側のカソード電極（蒸発源）とアノード電極との間にアーク放電を発生させて、前記超硬基体の表面に（Ｔｉ，Ｓｉ，Ｙ）Ｎ層を形成すると、この結果の（Ｔｉ，Ｓｉ，Ｙ）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Ｔｉ−Ｓｉ−Ｙ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含有割合の低いＴｉ−Ｓｉ−Ｙ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厚さ方向にそって前記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Ｓｉ含有割合が連続的に変化する成分濃度分布構造をもつようになること。
【０００８】
（ｂ）上記（ａ）の繰り返し連続変化成分濃度分布構造の（Ｔｉ，Ｓｉ，Ｙ）Ｎ層において、対向配置の一方側のカソード電極（蒸発源）であるＴｉ−Ｓｉ−Ｙ合金におけるＳｉ含有割合を上記の従来（Ｔｉ，Ｓｉ）Ｎ層形成用Ｔｉ−Ｓｉ合金のＳｉ含有割合に相当するものとし、同他方側のカソード電極（蒸発源）であるＴｉ−Ｓｉ−Ｙ合金におけるＳｉ含有割合を上記の従来Ｔｉ−Ｓｉ合金のＳｉ含有割合に比して相対的に低いものとすると共に、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：（Ｔｉ_1-( _Ａ ₊ _Ｚ ₎Ｓｉ_ＡＹ_Ｚ）Ｎ（ただし、原子比で、Ａは０．４５〜０．６０、Ｚ：０．０３〜０．１０を示す）、
上記Ｓｉ最低含有点が、組成式：（Ｔｉ_1-( _Ｂ ₊ _Ｚ ₎Ｓｉ_ＢＹ_Ｚ）Ｎ（ただし、原子比で、Ｂは０．０３〜０．２５、Ｚ：０．０３〜０．１０を示す）、
を満足し、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、上記の従来（Ｔｉ，Ｓｉ）Ｎ層の具備する高温硬さおよび耐熱性に相当するすぐれた高温硬さおよび耐熱性を有し、かつＹ成分含有によって耐熱塑性変形性も向上し、さらにＴｉ成分による高温強度も具備し、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含有割合が低く、相対的にＴｉ含有割合の高いものとなるので、一段と高い高温強度を有するようになり、しかもこれら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硬さと耐熱性、および耐熱塑性変形性を保持した状態で、さらに一段とすぐれた高温強度を具備するようになり、したがって、硬質被覆層がかかる構成の（Ｔｉ，Ｓｉ，Ｙ）Ｎ層からなる被覆超硬工具は、特に各種の鋼や鋳鉄などの切削加工を、高い発熱を伴なう速い切削速度で、かつ高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング性を発揮するようになること。
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，Ｙ）Ｎ層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して、上記硬質被覆層を、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Ｓｉ含有割合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Ｓｉ最高含有点が、
組成式：（Ｔｉ_1-( _Ａ ₊ _Ｚ ₎Ｓｉ_ＡＹ_Ｚ）Ｎ（ただし、原子比で、Ａは０．４５〜０．６０、Ｚ：０．０３〜０．１０を示す）、
上記Ｓｉ最低含有点が、
組成式：（Ｔｉ_1-( _Ｂ ₊ _Ｚ ₎Ｓｉ_ＢＹ_Ｚ）Ｎ（ただし、原子比で、Ｂは０．０３〜０．２５、Ｚ：０．０３〜０．１０を示す）、
を満足し、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、
硬質被覆層で構成してなる、高速重切削条件で硬質被覆層がすぐれた耐チッピング性を発揮する被覆超硬工具に特徴を有するものである。
【００１０】
つぎに、この発明の被覆超硬工具において、これを構成する硬質被覆層の構成を上記の通りに限定した理由を説明する。
（ａ）Ｓｉ最高含有点の組成
Ｓｉ最高含有点の（Ｔｉ，Ｓｉ，Ｙ）Ｎにおいて、Ｔｉ成分は高温強度を向上させ、同Ｓｉは高温硬さと耐熱性、さらにＹ成分は耐熱塑性変形性を向上させる作用があり、したがってＳｉの含有割合が高くなればなるほど高温硬さおよび耐熱性は向上したものになり、高熱発生を伴う高速切削に適応したものになるが、Ｓｉの含有割合を示すＡ値がＴｉとＹの合量に占める割合（原子比）で０．６０を越えると、相対的にＴｉ成分の含有割合が少なくなり過ぎて、すぐれた高温強度を有するＳｉ最低含有点が隣接して存在しても層自体の高温強度の低下は避けられず、この結果チッピングなどが発生し易くなり、一方同Ａ値が同０．４５未満になると、所定のすぐれた高温硬さと耐熱性を確保することが困難になり、摩耗が急速に進行するようになることから、Ａ値を０．４５〜０．６０と定めた。
さらに、Ｙ成分には上記の通り耐熱塑性変形性を向上させる作用があるが、Ｙの含有割合を示すＺ値がＳｉとＴｉの合量に占める割合（原子比）で０．０５未満では所望の耐熱塑性変形性向上効果が得られず、さらに同Ｚ値が０．１５を超えると、高温強度が低下するようになることから、Ｚ値を０．０３〜０．１０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Ｓｉ成分の高含有によりすぐれた高温硬さと耐熱性を有するが、反面高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件での高速切削加工では高温強度不足が避けられず、このＳｉ最高含有点の高温強度不足を補う目的で、Ｔｉ含有割合が相対的に高く、一方Ｓｉ含有割合が低く、これによって一段とすぐれた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り、したがってＳｉの割合を示すＢ値がＴｉおよびＹ成分との合量に占める割合（原子比）で０．２５を越えると、相対的にＴｉの含有割合が少なくなり過ぎて、所望のすぐれた高温強度を確保することができず、一方同Ｂ値が０．０３未満になると、所定の高温硬さおよび耐熱性の確保が困難になり、これが原因で高温硬さおよび耐熱性のすぐれたＳｉ最高含有点が隣接して存在しても層自体の摩耗進行が促進するようになることから、Ｓｉ最低含有点でのＳｉの含有割合を示すＢ値を０．０３〜０．２５と定めた。
さらに、Ｓｉ最低含有点におけるＹ成分も、上記の通り耐熱塑性変形性を向上させ、もって高熱発生を伴う高速切削に適応させる目的で含有するものであり、したがってＺ値が０．０５未満では所望の耐熱塑性変形性向上効果が得られず、一方Ｚ値が０．１５を越えると高温強度が低下するようになって、切刃部にチッピングが発生し易くなることから、Ｚ値を０．０３〜０．１０と定めた。
【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Ｓｉ最高含有点によるすぐれた高温硬さと耐熱性と、Ｓｉ最低含有点による一段とすぐれた高温強度を確保することができなくなり、またその間隔が０．１μmを越えると重切削条件での高速切削加工で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、これが原因でチッピングが発生し易くなったり、摩耗進行が促進されるようになることから、その間隔を０．０１〜０．１μmと定めた。
【００１３】
（ｄ）硬質被覆層の平均層厚
その層厚が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、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、ＶＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃｒ₃Ｃ₂粉末、およびＣｏ粉末を用意し、これら原料粉末を、表１に示される配合組成に配合し、ボールミルで４８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：１４２０℃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・ＣＮＭＧ１２０４１２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（重量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ₂Ｃ粉末、ＺｒＣ粉末、ＮｂＣ粉末、ＴａＣ粉末、ＷＣ粉末、Ｃｏ粉末、およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで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２ｋＰａの窒素雰囲気中、温度：１５２０℃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・ＣＮＭＧ１２０４１２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、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、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最高含有点形成用Ｔｉ−Ｓｉ−Ｙ合金、他方側のカソード電極（蒸発源）としてＳｉ最低含有点形成用Ｔｉ−Ｓｉ−Ｙ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、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−３０Ｖ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Ｓｉ最高含有点形成用Ｔｉ−Ｓｉ−Ｙ合金およびＳｉ最低含有点形成用Ｔｉ−Ｓｉ−Ｙ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Ｓｉ最高含有点とＳｉ最低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Ｓｉ含有割合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合金を装着し、またボンバード洗浄用金属Ｔｉも装置し、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９０Ａ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−２００Ｖ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、かつ厚さ方向に沿って実質的に組成変化のない（Ｔｉ，Ｓｉ）Ｎ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製スローアウエイチップ（以下、従来被覆超硬チップと云う）１〜１６をそれぞれ製造した。
【００１８】
つぎに、上記本発明被覆超硬チップ１〜１６および従来被覆超硬チップ１〜１６について、これを工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、
被削材：ＪＩＳ・Ｓ５０Ｃの丸棒、
切削速度：３００ｍ／ｍｉｎ．、
切り込み：４．５ｍｍ、
送り：０．２５ｍｍ／ｒｅｖ．、
切削時間：１０分、
の条件での炭素鋼の乾式連続高速高切り込み切削加工試験、
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：２８０ｍ／ｍｉｎ．、
切り込み：２ｍｍ、
送り：０．４ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での合金鋼の乾式断続高速高送り切削加工試験、さらに、
被削材：ＪＩＳ・ＦＣ３００の丸棒、
切削速度：３２０ｍ／ｍｉｎ．、
切り込み：４ｍｍ、
送り：０．３ｍｍ／ｒｅｖ．、
切削時間：１０分、
の条件での鋳鉄の乾式連続高速高切り込み切削加工試験を行い、いずれの切削加工試験でも切刃の逃げ面摩耗幅を測定した。この測定結果を表６に示した。
【００１９】
【表１】

【００２０】
【表２】

【００２１】
【表３】

【００２２】
【表４】

【００２３】
【表５】

【００２４】
【表６】

【００２５】
（実施例２）
原料粉末として、平均粒径：５．５μｍを有する中粗粒ＷＣ粉末、同０．８μｍの微粒ＷＣ粉末、同１．３μｍのＴａＣ粉末、同１．２μｍのＮｂＣ粉末、同１．２μｍのＺｒＣ粉末、同２．３μｍのＣｒ₃Ｃ₂粉末、同１．５μｍのＶＣ粉末、同１．０μｍの（Ｔｉ，Ｗ）Ｃ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５０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６枚刃スクエア形状をもった超硬基体（エンドミル）Ｃ−１〜Ｃ−８をそれぞれ製造した。
【００２６】
ついで、これらの超硬基体（エンドミル）Ｃ−１〜Ｃ−８を、アセトン中で超音波洗浄し、乾燥した状態で、同じく図１に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、層厚方向に沿って表８に示される目標組成のＳｉ最高含有点とＳｉ最低含有点とが交互に同じく表８に示される目標間隔で繰り返し存在し、かつ前記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Ｓｉ含有割合が連続的に変化する成分濃度分布構造を有し、かつ同じく表８に示される目標層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製エンドミル（以下、本発明被覆超硬エンドミルと云う）１〜８をそれぞれ製造した。
【００２７】
また、比較の目的で、上記の超硬基体（エンドミル）Ｃ−１〜Ｃ−８を、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表９に示される目標組成および目標層厚を有し、かつ厚さ方向に沿って実質的に組成変化のない（Ｔｉ，Ｓｉ）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・ＳＫＤ１１の板材、
切削速度：２５０ｍ／ｍｉｎ．、
軸方向切り込み：５ｍｍ、
径方向切り込み：０．６ｍｍ、
テーブル送り：４５００ｍｍ／分、
の条件での工具鋼の乾式高速高切り込み側面切削加工試験、本発明被覆超硬エンドミル４〜６および従来被覆超硬エンドミル４〜６については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ４５Ｃの板材、
切削速度：３００ｍ／ｍｉｎ．、
軸方向切り込み：１０ｍｍ、
径方向切り込み：０．８ｍｍ、
テーブル送り：５０００ｍｍ／分、
の条件での炭素鋼の乾式高速高切り込み側面切削加工試験、本発明被覆超硬エンドミル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・ＳＮＣＭ４３９の板材、
切削速度：２８０ｍ／ｍｉｎ．、
軸方向切り込み：１５ｍｍ、
径方向切り込み：０．５ｍｍ、
テーブル送り：３２００ｍｍ／分、
の条件での合金鋼の乾式高速高送り側面切削加工試験をそれぞれ行い、いずれの乾式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に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、層厚方向に沿って表１０に示される目標組成のＳｉ最高含有点とＳｉ最低含有点とが交互に同じく表１０に示される目標間隔で繰り返し存在し、かつ前記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Ｓｉ含有割合が連続的に変化する成分濃度分布構造を有し、かつ同じく表１０に示される目標層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製ドリル（以下、本発明被覆超硬ドリルと云う）１〜８をそれぞれ製造した。
【００３４】
また、比較の目的で、上記の超硬基体（ドリル）Ｄ−１〜Ｄ−８の切刃に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表１１に示される目標組成および目標層厚を有し、かつ厚さ方向に沿って実質的に組成変化のない（Ｔｉ，Ｓｉ）Ｎ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製ドリル（以下、従来被覆超硬ドリルと云う）１〜８をそれぞれ製造した。
【００３５】
つぎに、上記本発明被覆超硬ドリル１〜８および従来被覆超硬ドリル１〜８のうち、本発明被覆超硬ドリル１〜３および従来被覆超硬ドリル１〜３については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＦＣ３００の板材、
切削速度：１８０ｍ／ｍｉｎ．、
送り：０．１６ｍｍ／ｒｅｖ、
穴深さ：８ｍｍ
の条件での鋳鉄の湿式高速高送り穴あけ切削加工試験、本発明被覆超硬ドリル４〜６および従来被覆超硬ドリル４〜６については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ４５Ｃの板材、
切削速度：１５０ｍ／ｍｉｎ．、
送り：０．２１ｍｍ／ｒｅｖ、
穴深さ：１５ｍｍ
の条件での炭素鋼の湿式高速高送り穴あけ切削加工試験、本発明被覆超硬ドリル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・ＳＣＭ４３５の板材、
切削速度：１５０ｍ／ｍｉｎ．、
送り：０．２５ｍｍ／ｒｅｖ、
穴深さ：２５ｍｍ
の条件での合金鋼の湿式高速高送り穴あけ切削加工試験、をそれぞれ行い、いずれの湿式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、並びに従来被覆超硬工具としての従来被覆超硬チップ１〜１６、従来被覆超硬エンドミル１〜８、および従来被覆超硬ドリル１〜８を構成する硬質被覆層について、厚さ方向に沿ってＴｉ、Ｓｉ、およびＹの含有割合をオージェ分光分析装置を用いて測定したところ、前記本発明被覆超硬工具の硬質被覆層では、Ｓｉ最高含有点とＳｉ最低含有点とがそれぞれ目標値と実質的に同じ組成および間隔で交互に繰り返し存在し、かつ前記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することが確認され、さらに硬質被覆層の平均層厚も目標層厚と実質的に同じ値を示した。一方、前記従来被覆超硬工具の硬質被覆層では、目標組成と実質的に同じ組成および目標層厚と実質的に同じ平均層厚を示すものの、厚さ方向に沿った組成変化は見られず、層全体に亘って均質な組成を示すものであった。
【００３９】
【発明の効果】
表３〜１１に示される結果から、硬質被覆層が層全体に亘ってすぐれた耐熱塑性変形性を具備した状態で、厚さ方向にすぐれた高温硬さと耐熱性を有するＳｉ最高含有点と一段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Ｓｉ含有割合が連続的に変化する成分濃度分布構造を有する本発明被覆超硬工具は、いずれも各種の鋼や鋳鉄などの高速切削加工を、高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング性を発揮するのに対して、硬質被覆層が厚さ方向に沿って実質的に組成変化のない（Ｔｉ，Ｓｉ）Ｎ層からなる従来被覆超硬工具においては、重切削条件での高速切削加工では前記硬質被覆層の高温強度不足が原因で、チッピングが発生し、これが原因で比較的短時間で使用寿命に至ることが明らかである。
上述のように、この発明の被覆超硬工具は、通常の条件での切削加工は勿論のこと、特に各種の鋼や鋳鉄などの高速切削加工を、高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、すぐれた耐チッピング性を発揮し、長期に亘ってすぐれた耐摩耗性を示すものであるから、切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。
【図面の簡単な説明】
【図１】この発明の被覆超硬工具を構成する硬質被覆層を形成するのに用いたアークイオンプレーティング装置を示し、（ａ）は概略平面図、（ｂ）は概略正面図である。
【図２】従来被覆超硬工具を構成する硬質被覆層を形成するのに用いた通常のアークイオンプレーティング装置の概略説明図である。[0001]
BACKGROUND OF THE INVENTION
This invention has a high temperature strength with a hard coating layer that is further superior, high temperature hardness and heat resistance, and also excellent heat resistance plastic deformation, and therefore high speed cutting with high heat generation especially for various steels and cast irons. A surface-coated cemented carbide cutting tool that exhibits excellent chipping resistance even when heavy cutting conditions such as high cutting and high feed with high mechanical impact are performed (hereinafter referred to as coating) This is related to carbide tools.
[0002]
[Prior art]
In general, coated carbide tools are used for throwaway inserts that are detachably attached to the tip of a cutting tool for drilling and cutting of various materials such as steel and cast iron, and for flat cutting. There are drills, miniature drills, solid type end mills used for chamfering, grooving, shoulder processing, etc. Also, the throwaway tip is detachably attached and cutting is performed in the same way as the solid type end mill Throwaway end mill tools are known.
[0003]
Further, as a coated carbide tool, a substrate made of tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet (hereinafter collectively referred to as a cemented carbide substrate). On the surface)
Composition formula: (Ti _1- _A Si _A ) N (however, in atomic ratio, A represents 0.45 to 0.60),
Coated carbide tool formed by physical vapor deposition of hard coating layer composed of Ti and Si composite nitride (hereinafter referred to as (Ti, Si) N) layer satisfying the requirements with an average layer thickness of 0.5 to 15 μm In such a coated carbide tool, the (Ti, Si) N layer constituting the hard coating layer has excellent high-temperature hardness and heat resistance due to Si, and excellent high-temperature strength due to Ti. It is also known that it is used for continuous cutting and intermittent cutting processing of cast iron and cast iron (for example, see 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, in the state heated to a temperature of 400 ° C., an arc discharge is generated between the anode electrode and the cathode electrode (evaporation source) in which a Ti—Si alloy having a predetermined composition is set, for example, at a current of 90 A, At the same time, nitrogen gas is introduced into the apparatus as a reaction gas to give a reaction atmosphere of, for example, 2 Pa. On the other hand, the carbide substrate is applied with a bias voltage of, for example, -200 V on the surface of the carbide substrate. It is also known that it is produced by vapor-depositing a hard coating layer composed of a (Ti, Si) N layer.
[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 has been a strong demand for labor saving and energy saving and further cost reduction for cutting work. With this, cutting speed has been increased, and high cutting depth and high feed are required. Although there is a tendency to strongly demand cutting under heavy cutting conditions, the above conventional coated carbide tool has no problem when used under normal cutting conditions, but involves high heat generation. When high-speed cutting is performed under heavy cutting conditions such as high cutting and high feed with high mechanical impact, chipping (microcracks) is likely to occur due to insufficient high-temperature strength of the hard coating layer, and it is relatively short. The current situation is that the service life is reached in time.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed the above-mentioned conventional coated carbide tool in order to develop a coated carbide tool that exhibits excellent chipping resistance with a hard coating layer particularly in high-speed heavy cutting. As a result of conducting research with a focus on the hard coating layer,
(A) The (Ti, Si) N layer constituting the conventional coated carbide tool formed by using the arc ion plating apparatus shown in FIG. 2 has a substantially uniform composition over the entire thickness. Therefore, 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. A rotation table for mounting the substrate is provided, and the Y-component is further added to the Ti-Si alloy used as the cathode electrode (evaporation source) for forming the conventional (Ti, Si) N layer on one side with the rotation table interposed therebetween. A Ti—Si—Y alloy containing Nb as an alloy component is disposed, and a Ti—Si—Y alloy having a relatively low Si content as compared with the Ti—Si—Y alloy is disposed on the other side. As cathode electrode (evaporation source) Using an arc ion plating apparatus disposed opposite to each other, a plurality of cemented carbide substrates are mounted in a ring shape along the outer periphery at a position spaced apart from the central axis in a radial direction on the rotary table of the apparatus. In this state, the atmosphere inside the apparatus is changed to a nitrogen atmosphere, the rotating table is rotated, and the carbide substrate itself is rotated for the purpose of uniforming the thickness of the hard coating layer formed by vapor deposition. When a (Ti, Si, Y) N layer is formed on the surface of the cemented carbide substrate by generating an arc discharge between the source and the anode electrode, in the resulting (Ti, Si, Y) N layer, When the cemented carbide substrate arranged in a ring shape on the rotary table is closest to the cathode electrode (evaporation source) of the Ti-Si-Y alloy on one side, the highest Si content point is formed in the layer. , Ma When the cemented carbide substrate is closest to the cathode electrode of the Ti-Si-Y alloy having a relatively low Si content on the other side, the lowest Si content point is formed in the layer, In the layer, the Si highest content point and the Si lowest content point alternately appear at predetermined intervals along the thickness direction, and the Si highest content point to the Si lowest content point and the Si lowest content point to the Si To have a component concentration distribution structure in which the Si content rate continuously changes to the highest content point.
[0008]
(B) In the (Ti, Si, Y) N layer having the repeated continuous change component concentration distribution structure of (a) above, Si content in the Ti—Si—Y alloy which is the cathode electrode (evaporation source) on one side facing each other The ratio corresponds to the Si content of the conventional Ti—Si alloy for forming a (Ti, Si) N layer, and the Si content in the Ti—Si—Y alloy which is the cathode electrode (evaporation source) on the other side. Is relatively low compared to the Si content of the conventional Ti-Si alloy, and the rotational speed of the rotary table on which the carbide substrate is mounted is controlled,
The highest Si content point is the composition formula: (Ti _{1- (} _A ₊ _Z ₎ Si _A _YZ ) N (however, in atomic ratio, A represents 0.45 to 0.60, Z represents 0.03 to 0.10),
The minimum Si content point is the composition formula: (Ti _{1- (} _B ₊ _Z ₎ Si _B Y _Z ) N (however, in atomic ratio, B represents 0.03 to 0.25, Z represents 0.03 to 0.10),
And the interval 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,
The highest Si content point has excellent high-temperature hardness and heat resistance corresponding to the high-temperature hardness and heat resistance of the conventional (Ti, Si) N layer, and heat-resistant plastic deformation due to the Y component. In addition, the Si minimum content point portion has a lower Si content rate than the Si highest content point portion, and a relatively high Ti content rate. As a result, it has a much higher high-temperature strength, and the distance between the highest Si content point and the lowest Si content point has been made extremely small, so that it has excellent high-temperature hardness, heat resistance, and heat-resistant plastic deformation. Coated carbide tool comprising a (Ti, Si, Y) N layer having a structure with a hard coating layer, which has a further excellent high-temperature strength while maintaining its properties. Especially when cutting various steels and cast irons at high cutting speed with high heat generation and heavy cutting conditions such as high cutting and high feed with high mechanical impact. The layer should have excellent chipping resistance.
The research results shown in (a) and (b) above were obtained.
[0009]
The present invention has been made based on the above research results, and a hard coating layer composed of a (Ti, Si, Y) N layer is formed on the surface of a cemented carbide substrate with an average layer thickness of 0.5 to 15 μm. In the coated carbide tool formed by physical vapor deposition, the hard coating layer is repeatedly present along the layer thickness direction with the Si highest content point and the Si lowest content point alternately present at predetermined intervals, and the Si From the highest content point to the Si lowest content point, having a component concentration distribution structure in which the Si content rate continuously changes from the Si lowest content point to the Si highest content point,
Furthermore, the Si maximum content point is
Composition formula: (Ti _{1- (} _A ₊ _Z ₎ Si _A _YZ ) N (however, in atomic ratio, A represents 0.45 to 0.60, Z represents 0.03 to 0.10),
The Si minimum content point is
Composition formula: (Ti _{1- (} _B ₊ _Z ₎ Si _B Y _Z ) N (however, in atomic ratio, B represents 0.03 to 0.25, Z represents 0.03 to 0.10),
And the distance between adjacent Si highest content point and Si lowest content point is 0.01 to 0.1 μm.
It is characterized by a coated carbide tool that is composed of a hard coating layer and exhibits excellent chipping resistance under high-speed heavy cutting conditions.
[0010]
Next, in the coated carbide tool of the present invention, the reason why the structure of the hard coating layer constituting the tool is limited as described above will be described.
(A) Composition of the highest Si content point In (Ti, Si, Y) N with the highest Si content point, the Ti component improves high temperature strength, the Si is high temperature hardness and heat resistance, and the Y component is heat plastic deformation resistance. Therefore, the higher the Si content, the higher the high-temperature hardness and heat resistance, and it is suitable for high-speed cutting with high heat generation. When the A value exceeds 0.60 in the ratio (atomic ratio) to the total amount of Ti and Y, the content ratio of the Ti component becomes relatively small, and the Si minimum content point having excellent high-temperature strength is adjacent. Even if it exists, a decrease in the high-temperature strength of the layer itself is unavoidable, and as a result, chipping or the like tends to occur. On the other hand, when the A value is less than 0.45, a predetermined excellent high-temperature hardness and heat resistance Difficult to secure , Since it becomes wear progresses rapidly, it was defined as 0.45 to 0.60 the A value.
Furthermore, the Y component has the effect of improving the heat-resistant plastic deformation as described above, but it is desirable if the Z value indicating the Y content is less than 0.05 in terms of the ratio (atomic ratio) to the total amount of Si and Ti. Thus, when the Z value exceeds 0.15, the high-temperature strength decreases. Therefore, the Z value is determined to be 0.03 to 0.10.
[0011]
(B) Composition of the lowest Si content point As described above, the highest Si content point has excellent high-temperature hardness and heat resistance due to the high Si content, but on the other hand, heavy cutting such as high cutting and high feed with high mechanical impact. In high-speed cutting under conditions, insufficient high-temperature strength is inevitable, and in order to make up for the lack of high-temperature strength at this Si highest content point, the Ti content rate is relatively high, while the Si content rate is low, which further improves Si minimum content points that have high-temperature strength are alternately interposed in the thickness direction, and therefore, the B value indicating the ratio of Si is 0 in the ratio (atomic ratio) to the total amount of Ti and Y components. If it exceeds .25, the content ratio of Ti becomes relatively small, and the desired excellent high-temperature strength cannot be ensured. On the other hand, if the B value is less than 0.03, a predetermined high-temperature hardness is obtained. And heat resistance It becomes difficult to ensure, and this causes the wear progress of the layer itself to be promoted even if there is an adjacent Si highest content point with excellent high-temperature hardness and heat resistance. B value which shows the content rate of Si was defined as 0.03-0.25.
Furthermore, the Y component at the Si minimum content point is also included for the purpose of improving the heat-resistant plastic deformability and adapting to high-speed cutting with high heat generation as described above. Therefore, if the Z value is less than 0.05, it is desirable. On the other hand, if the Z value exceeds 0.15, the high-temperature strength decreases, and chipping tends to occur at the cutting edge portion. It was set as 03-0.10.
[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. Excellent high-temperature hardness and heat resistance, as well as excellent high-temperature strength due to the lowest Si content point can no longer be secured, and if the spacing exceeds 0.1 μm, each point will be in high-speed cutting under heavy cutting conditions. Disadvantages, i.e., the highest Si content point, insufficient high-temperature strength, and the lowest Si content point, local high-temperature hardness and insufficient heat resistance appear locally in the layer, which is likely to cause chipping and wear. Since the progress is promoted, the interval is set to 0.01 to 0.1 μm.
[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 tends to occur. Therefore, the average layer thickness was determined to be 0.5 to 15 μm.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated carbide tool of the present invention will be specifically described with reference to examples.
Example 1
As raw material powders, WC powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder, all having an average particle diameter of 1 to 3 μm, were prepared. The mixture is blended for 48 hours by a ball mill, dried and then pressed into a green compact at a pressure of 100 MPa, and this green compact is vacuumed at 6 Pa at a temperature of 1420 ° C. for 1 hour. Sintered under the holding conditions, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03, and a cemented carbide substrate A-1 made of WC-based cemented carbide having a chip shape of ISO standard / CNMG120212 ~ A-10 was formed.
[0015]
In addition, as raw material powders, all are TiCN (weight ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder were prepared, and these raw material powders were blended in the blending composition shown in Table 2, wet mixed by a ball mill for 72 hours, dried, and then pressed into a compact at a pressure of 100 MPa. The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1520 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03, and ISO standard / CNMG120212. TiCN-based cermet carbide substrates B-1 to B-6 having the following chip shape 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. A plurality of cemented carbide substrates are mounted in a ring shape along the outer periphery at a predetermined distance in the radial direction from the central axis on the rotary table, and various component compositions are used as a cathode electrode (evaporation source) on one side. A Ti-Si-Y alloy for forming the highest Si content point with a Ti-Si-Y alloy for forming the lowest Si content point as a cathode electrode (evaporation source) on the other side, with the rotary table interposed therebetween, and The metal Ti for bombard cleaning is also mounted. First, the inside of the apparatus is evacuated and kept at a vacuum of 0.5 Pa or less, the inside of the apparatus is heated to 500 ° C. with a heater, and then rotates while rotating on the rotary table. Carbide substrate A DC bias voltage of 1000 V was applied and a current of 100 A was passed between the metal Ti and the anode electrode of the cathode electrode to generate an arc discharge, thereby cleaning the surface of the carbide substrate with Ti bombardment, and then in the apparatus. Nitrogen gas was introduced as a reaction gas to give a reaction atmosphere of 3 Pa, a DC bias voltage of −30 V was applied to the carbide substrate rotating while rotating on the rotary table, and each cathode electrode (the Si maximum) The content of Ti-Si-Y alloy for content point formation and Ti-Si-Y alloy for Si content minimum point formation) and an anode electrode are used to generate an arc discharge, and thereby the surface of the cemented carbide substrate. Further, along the thickness direction, the highest Si content point and the lowest Si content point of the target composition shown in Tables 3 and 4 are alternately changed at the target intervals shown in Tables 3 and 4. It has a component concentration distribution structure that repeatedly exists and the Si content ratio continuously changes 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, and also in Table 3. , 4 to deposit a hard coating layer having a target layer thickness, the surface coated cemented carbide throwaway tip (hereinafter referred to as the present coated carbide tip) 1 as the coated carbide tool of the present invention 1 ~ 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. Inserted into an ion plating apparatus, mounted with Ti-Si alloys having various component compositions as a cathode electrode (evaporation source), and also mounted a metal Ti for bombard cleaning. The apparatus was heated to 400 ° C. with a heater while maintaining a vacuum of .5 Pa or less, and then a DC bias voltage of −1000 V was applied to the cemented carbide substrate, and between the metal Ti of the cathode electrode and the anode electrode. Then, a 90 A current is passed to generate arc discharge, and the surface of the carbide substrate is cleaned with Ti bombardment, and then nitrogen gas is introduced into the apparatus as a reaction gas to obtain a reaction atmosphere of 2 Pa. The bias voltage applied to the hard substrate is lowered to −200 V, and arc discharge is generated between the cathode electrode and the anode electrode, thereby the carbide substrates A-1 to A-10 and B-1 to B-6. A hard coating layer composed of a (Ti, Si) N layer having a target composition and a target layer thickness shown in Table 5 and having substantially no composition change along the thickness direction is deposited on each surface of Thus, conventional surface-coated cemented carbide throwaway tips (hereinafter referred to as conventional coated carbide tips) 1 to 16 as conventional coated carbide tools were produced, respectively.
[0018]
Next, with the present invention coated carbide tips 1-16 and conventional coated carbide tips 1-16, in a state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / S50C round bar,
Cutting speed: 300 m / min. ,
Cutting depth: 4.5mm,
Feed: 0.25 mm / rev. ,
Cutting time: 10 minutes,
Dry continuous high-speed high-cut cutting test of carbon steel under the conditions of
Work material: JIS · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 280 m / min. ,
Cutting depth: 2mm,
Feed: 0.4 mm / rev. ,
Cutting time: 5 minutes
Dry interrupted high-speed high-feed cutting test of alloy steel under the conditions of
Work material: JIS / FC300 round bar,
Cutting speed: 320 m / min. ,
Incision: 4mm,
Feed: 0.3 mm / rev. ,
Cutting time: 10 minutes,
The dry continuous high-speed, high-cut cutting test of cast iron was performed under the conditions described above, and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in 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 Prepare a 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. Each was blended in the blending composition shown in Table 7, further added with wax, mixed in ball mill in acetone for 50 hours, dried under reduced pressure, and then pressed into various compacts of a predetermined shape at a pressure of 100 MPa. The green compact is heated 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, held at this temperature for 1 hour, and then fired under furnace cooling conditions. Finally, the diameters are 8mm, 13mm, and 26 3 types of sintered carbide rod forming bodies for forming a carbide substrate of m, and further, the diameter of the cutting edge portion by the combination shown in Table 7 by grinding from the above three types of sintered rods. × Carbide substrates (end mills) C-1 to C-8 having a 6-blade square shape with lengths 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 Were manufactured respectively.
[0026]
Then, these carbide substrates (end mills) C-1 to C-8 were ultrasonically washed in acetone and dried, and then charged into the arc ion plating apparatus shown in FIG. Under the same conditions as in Example 1, the Si highest content point and the Si lowest content point of the target composition shown in Table 8 along the layer thickness direction alternately and repeatedly exist at the target interval shown in Table 8, and A target layer thickness having a component concentration distribution structure in which the Si content continuously changes 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, and also shown in Table 8 The hard coating layer of the present invention was used to produce end mills made of the surface coated cemented carbide alloy (hereinafter referred to as the present coated carbide end mill) 1 to 8 as the coated carbide tool of the present invention.
[0027]
For the purpose of comparison, the above-mentioned carbide substrates (end mills) C-1 to C-8 are ultrasonically cleaned in acetone and dried, and the ordinary arc ion plating apparatus shown in FIG. 2 is also used. (Ti, Si) N having the target composition and target layer thickness shown in Table 9 and substantially no composition change along the thickness direction under the same conditions as in Example 1 above. By vapor-depositing a hard coating layer consisting of layers, conventional surface-coated cemented carbide end mills (hereinafter referred to as conventional coated carbide end mills) 1 to 8 as conventional coated carbide tools were produced, respectively.
[0028]
Next, of the present invention coated carbide end mills 1-8 and conventional coated carbide end mills 1-8, the present invention coated carbide end mills 1-3 and conventional coated carbide end mills 1-3 are as follows:
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SKD11 plate material,
Cutting speed: 250 m / min. ,
Axial cut: 5mm,
Radial incision: 0.6mm,
Table feed: 4500 mm / min,
With respect to the tool steel dry high-speed high-cut side cutting test, the coated carbide end mills 4 to 6 and the conventional coated carbide end mills 4 to 6 of the present invention,
Work material: Plane dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / S45C plate,
Cutting speed: 300 m / min. ,
Axial cut: 10 mm
Radial notch: 0.8mm,
Table feed: 5000 mm / min,
With respect to the dry high-speed high-cut side cutting test of carbon steel under the conditions of the present invention, the coated carbide end mills 7 and 8 of the present invention and the conventional coated carbide end mills 7 and 8 are as follows:
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SNCM439 plate material,
Cutting speed: 280 m / min. ,
Axial cut: 15mm,
Radial notch: 0.5mm,
Table feed: 3200 mm / min,
In each dry side cutting test, the flank wear width of the outer peripheral edge of the cutting edge is set to 0.1 mm, which is a guide for the service life. The cutting length was measured. The measurement results are shown in Tables 8 and 9, respectively.
[0029]
[Table 7]

[0030]
[Table 8]

[0031]
[Table 9]

[0032]
(Example 3)
The diameters produced in Example 2 above were 8 mm (for forming carbide substrates C-1 to C-3), 13 mm (for forming carbide substrates C-4 to C-6), and 26 mm (for carbide substrates C-). 7, for C-8 formation), from these three types of round bar sintered bodies, the diameter x length of the groove forming portion is 4 mm x 13 mm (by grinding), respectively. Carbide substrates D-1 to D-3), 8 mm × 22 mm (Carbide substrates D-4 to D-6), and 16 mm × 45 mm (Carbide substrates D-7 and D-8), and all Carbide substrates (drills) D-1 to D-8 having a two-blade shape with a twist angle of 30 degrees were produced.
[0033]
Next, the cutting edges of these carbide substrates (drills) D-1 to D-8 are subjected to honing, ultrasonically cleaned in acetone and dried, and the arc ion plating apparatus shown in FIG. 1 is also used. In the same conditions as in Example 1 above, the target spacing shown in Table 10 in which the Si highest content point and the Si lowest content point of the target composition shown in Table 10 are alternately shown along the layer thickness direction. And a component concentration distribution structure in which the Si content ratio continuously changes 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. By depositing a hard coating layer having a target layer thickness shown in FIG. 10, drills made of the surface coated cemented carbide of the present invention (hereinafter referred to as the present coated carbide drill) 1 to 8 as the coated carbide tool of the present invention. Each was manufactured.
[0034]
For comparison purposes, the cutting edges of the above-mentioned carbide substrates (drills) D-1 to D-8 are honed, ultrasonically cleaned in acetone, and dried, as shown in FIG. The sample was charged into a normal arc ion plating apparatus, had the target composition and target layer thickness shown in Table 11 under the same conditions as in Example 1, and substantially changed in composition along the thickness direction. By vapor-depositing a hard coating layer consisting of no (Ti, Si) N layer, conventional surface-coated cemented carbide drills (hereinafter referred to as conventional coated carbide drills) 1 to 8 as conventional coated carbide tools are respectively provided. Manufactured.
[0035]
Next, of the present invention coated carbide drills 1-8 and conventional coated carbide drills 1-8, the present invention coated carbide drills 1-3 and conventional coated carbide drills 1-3,
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS / FC300 plate material,
Cutting speed: 180 m / min. ,
Feed: 0.16mm / rev,
Hole depth: 8mm
For the cast iron wet high-speed high-feed drilling test under the conditions of the present invention, the present invention coated carbide drills 4-6 and conventional coated carbide drills 4-6,
Work material: Plane dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / S45C plate,
Cutting speed: 150 m / min. ,
Feed: 0.21mm / rev,
Hole depth: 15mm
With respect to the carbon steel wet high-speed high-feed drilling test, the coated carbide drills 7 and 8 of the present invention and the conventional coated carbide drills 7 and 8,
Work material: Plane dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SCM435 plate material,
Cutting speed: 150 m / min. ,
Feed: 0.25mm / rev,
Hole depth: 25mm
Wet high-speed high-feed drilling test of alloy steel under the above conditions, respectively, and in any wet high-speed drilling test (using water-soluble cutting oil), the flank wear width of the cutting edge surface is 0.3 mm The number of drilling processes was measured. The measurement results are shown in Tables 10 and 11, respectively.
[0036]
[Table 10]

[0037]
[Table 11]

[0038]
As a result, the coated carbide tips 1 to 16 of the present invention, the coated carbide end mills 1 to 8 of the present invention, the coated carbide drills 1 to 8 of the present invention, and the conventionally coated carbide tools of the present invention. Conventionally coated carbide tips 1 to 16, conventional coated carbide end mills 1 to 8, and conventional coated carbide drills 1 to 8 are coated with Ti, Si, and Y along the thickness direction. When the content ratio was measured using an Auger spectroscopic analyzer, in the hard coating layer of the coated carbide tool of the present invention, the Si maximum content point and the Si minimum content point were respectively substantially the same composition and interval as the target values. It has a component concentration distribution structure that repeats alternately and the content ratio of Si continuously changes from the highest Si content point to the lowest Si content point and from the lowest Si content point to the highest Si content point. Rukoto is confirmed, further the average layer thickness of the hard layer shown the target layer thickness substantially the same value. On the other hand, the hard coating layer of the conventional coated carbide tool shows a composition substantially the same as the target composition and an average layer thickness substantially the same as the target layer thickness, but there is no composition change along the thickness direction. The composition showed a homogeneous composition throughout the entire layer.
[0039]
【The invention's effect】
From the results shown in Tables 3 to 11, in the state in which the hard coating layer has excellent heat plastic deformation throughout the entire layer, the highest Si content point having excellent high temperature hardness and heat resistance in the thickness direction and further Si lowest content points having excellent high-temperature strength are alternately present at predetermined intervals, and Si content from the Si highest content point to the Si lowest content point, from the Si lowest content point to the Si highest content point The coated carbide tool of the present invention having a component concentration distribution structure in which the ratio continuously changes is used for high-speed cutting such as various steels and cast iron, and heavy cutting such as high cutting and high feed with high mechanical impact. Even when performed under the conditions, the hard coating layer exhibits excellent chipping resistance, whereas the hard coating layer is formed from a (Ti, Si) N layer having substantially no composition change along the thickness direction. Conventional coated carbide In ingredients, due to the high temperature insufficient strength of the hard coating layer is a fast cutting of heavy cutting conditions, chipping occurs and this is apparent that lead to a relatively short time service life due.
As described above, the coated carbide tool according to the present invention can be used not only for cutting under normal conditions, but also for high-speed cutting such as various types of steel and cast iron, with high cutting and high feed with high mechanical impact. Even when performed under heavy cutting conditions such as the above, it exhibits excellent chipping resistance and excellent wear resistance over a long period of time. It is possible to cope with the above sufficiently.
[Brief description of the drawings]
FIG. 1 shows an arc ion plating apparatus used for forming a hard coating layer constituting a coated carbide tool of the present invention, wherein (a) is a schematic plan view and (b) is a schematic front view.
FIG. 2 is a schematic explanatory view of a normal arc ion plating apparatus used to form a hard coating layer constituting a conventional coated carbide tool.

Claims

Physical vapor deposition of a hard coating layer composed of a composite nitride layer of Ti, Si and Y (yttrium) on the surface of a tungsten carbide base cemented carbide substrate or a titanium carbonitride cermet substrate with an overall average layer thickness of 0.5 to 15 μm A surface-coated cemented carbide cutting tool made of
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 Si content ratio continuously changes from the lowest content point to the Si highest content point,
Furthermore, the Si highest content point is the composition formula: (Ti _{1- (} _A ₊ _Z ₎ Si _A _YZ ) N (however, in atomic ratio, A represents 0.45 to 0.60, Z represents 0.03 to 0.10),
The minimum Si content point is the composition formula: (Ti _{1- (} _B ₊ _Z ₎ Si _B Y _Z ) N (however, in atomic ratio, B represents 0.03 to 0.25, Z represents 0.03 to 0.10),
And the distance between adjacent Si highest content point and Si lowest content point is 0.01 to 0.1 μm.
A surface-coated cemented carbide cutting tool that exhibits excellent chipping resistance under high-speed heavy cutting conditions characterized by comprising a hard coating layer.