JP3962910B2

JP3962910B2 - Surface coated cemented carbide cutting tool with excellent chipping resistance due to hard coating layer in heavy cutting

Info

Publication number: JP3962910B2
Application number: JP2002106101A
Authority: JP
Inventors: 秀充高岡; 恵滋中村; 安彦田代
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2002-04-09
Filing date: 2002-04-09
Publication date: 2007-08-22
Anticipated expiration: 2022-04-09
Also published as: JP2003300104A

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層が高強度と高靭性、さらに高い高温硬さを有し、したがって特に各種の鋼や鋳鉄などの切削加工を、高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合に、硬質被覆層がすぐれた耐チッピング性を発揮する表面被覆超硬合金製切削工具（以下、被覆超硬工具という）に関するものである。
【０００２】
【従来の技術】
一般に、被覆超硬工具には、各種の鋼や鋳鉄などの被削材の旋削加工や平削り加工にバイトの先端部に着脱自在に取り付けて用いられるスローアウエイチップ、穴あけ切削加工などに用いられるドリルやミニチュアドリル、さらに面削加工や溝加工、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-XＺｒ_X）Ｎ（ただし、原子比で、Ｘは０．０５〜０．３５を示す）を満足するＴｉとＺｒの複合窒化物［以下、（Ｔｉ，Ｚｒ）Ｎで示す］層からなる硬質被覆層を１〜１５μｍの平均層厚で物理蒸着してなる被覆超硬工具が提案され、各種の鋼や鋳鉄などの連続切削や断続切削加工に用いられている。
【０００４】
さらに、上記の被覆超硬工具が、例えば図２に概略説明図で示される物理蒸着装置の１種であるアークイオンプレーティング装置に上記の超硬基体を装入し、ヒータで装置内を、例えば５００℃の温度に加熱した状態で、アノード電極と所定組成を有するＴｉ−Ｚｒ合金がセットされたカソード電極（蒸発源）との間に、例えば電流：９０Ａの条件でアーク放電を発生させ、同時に装置内に反応ガスとして窒素ガスを導入して、例えば２Ｐａの反応雰囲気とし、一方上記超硬基体には、例えば−１００Ｖのバイアス電圧を印加した条件で、前記超硬合金基体の表面に、上記（Ｔｉ，Ｚｒ）Ｎ層からなる硬質被覆層を蒸着することにより製造されることも知られている。
【０００５】
【発明が解決しようとする課題】
近年の切削加工装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求は強く、これに伴い、加工能率向上の面から、切削加工は高切り込みや高送りなどの重切削条件で行なわれる傾向にあるが、上記の従来被覆超硬工具においては、これを通常の切削加工条件で用いた場合には問題はないが、切削加工を高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合には、特に硬質被覆層の強度および靭性不足が原因でチッピング（微小割れ）が発生し易くなり、比較的短時間で使用寿命に至るのが現状である。
【０００６】
【課題を解決するための手段】
そこで、本発明者等は、上述のような観点から、特に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，Ｚｒ）Ｎ層は、層厚全体に亘って実質的に均一な組成を有し、したがって均質な強度と靭性、さらに高温硬さを有するが、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Ｚｒ成分を含有したＴｉ−Ｚｒ合金、他方側に金属Ｔｉをいずれもカソード電極（蒸発源）として対向配置したアークイオンプレーティング装置を用い、この装置の前記回転テーブルの外周部に沿って複数の超硬基体をリング状に装着し、この状態で装置内雰囲気を窒素雰囲気として前記回転テーブルを回転させると共に、蒸着形成される硬質被覆層の層厚均一化を図る目的で超硬基体自体も自転させながら、前記の両側のカソード電極（蒸発源）とアノード電極との間にアーク放電を発生させて、前記超硬基体の表面に（Ｔｉ，Ｚｒ）Ｎ層を形成すると、この結果の（Ｔｉ，Ｚｒ）Ｎ層においては、回転テーブル上にリング状に配置された前記超硬基体が上記の一方側のＴｉ−Ｚｒ合金のカソード電極（蒸発源）に最も接近した時点で層中にＺｒ成分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金属Ｔｉのカソード電極に最も接近した時点で層中にＴｉＮ点（Ｚｒ成分不含有点）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Ｚｒ成分最高含有点とＺｒ成分不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Ｚｒ成分最高含有点から前記Ｚｒ成分不含有点、前記Ｚｒ最低含有点から前記Ｚｒ成分不含有点へＺｒ成分含有量が連続的に変化する成分濃度分布構造をもつようになること。
【０００７】
（ｂ）上記（ａ）の繰り返し連続変化成分濃度分布構造の（Ｔｉ，Ｚｒ）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−Ｚｒ合金におけるＺｒ成分含有量を上記の従来Ｔｉ−Ｚｒ合金のＺｒ成分含有量に相当するものとする共に、超硬基体が装着されている回転テーブルの回転速度を制御して、
上記Ｚｒ成分最高含有点が、組成式：（Ｔｉ_1-XＺｒ_X）Ｎ（ただし、原子比で、Ｘは０．０５〜０．３５を示す）、
を満足し、かつ隣り合う上記Ｚｒ成分最高含有点とＺｒ成分不含有点の厚さ方向の間隔を０．０１〜０．１μmとすると、
上記Ｚｒ成分最高含有点部分では、上記の従来（Ｔｉ，Ｚｒ）Ｎ層のもつ強度と靭性、さらに高温硬さに相当するすぐれた性質を示し、一方上記Ｚｒ成分不含有点部分では、実質的にＴｉＮ点を中心にしてＺｒ成分含有量の著しく低いものとなるので、ＴｉＮのもつ高強度と高靭性が確保され、かつこれらＺｒ成分最高含有点とＺｒ成分不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を保持した状態で一段とすぐれた強度と靭性を具備するようになり、したがって、硬質被覆層がかかる構成の（Ｔｉ，Ｚｒ）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。
【０００８】
この発明は、上記の研究結果に基づいてなされたものであって、超硬基体の表面に、（Ｔｉ，Ｚｒ）Ｎ層からなる硬質被覆層を１〜１５μｍの全体平均層厚で物理蒸着してなる被覆超硬工具において、
上記硬質被覆層が、層厚方向にそって、Ｚｒ成分最高含有点（Ｔｉ成分最低含有点）とＺｒ成分不含有点（ＴｉＮ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Ｚｒ成分最高含有点から前記Ｚｒ成分不含有点、前記Ｚｒ成分不含有点から前記Ｚｒ成分最高含有点へＺｒ成分含有量が連続的に変化する成分濃度分布構造を有し、
さらに、上記Ｚｒ成分最高含有点が、組成式：（Ｔｉ_1-XＺｒ_X）Ｎ（ただし、原子比で、Ｘは０．０５〜０．３５を示す）、
を満足し、かつ隣り合う上記Ｚｒ成分最高含有点とＺｒ成分不含有点の間隔が、０．０１〜０．１μmである、
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に特徴を有するものである。
【０００９】
つぎに、この発明の被覆超硬工具において、これを構成する硬質被覆層の構成を上記の通りに限定した理由を説明する。
（ａ）Ｚｒ成分最高含有点の組成
（Ｔｉ，Ｚｒ）Ｎ層におけるＺｒ成分は、高強度および高靭性を有するＴｉＮ層の高温硬さを向上させる目的で含有するものであり、したがってＺｒ成分の含有割合が高くなればなるほど高温硬さは高いものとなるが、Ｚｒの割合を示すＸ値がＴｉとの合量に占める割合（原子比）で０．３５を越えて高くなると、高強度および高靭性を有するＴｉＮ点が隣接して存在しても層自体の強度および靭性の低下は避けられず、この結果チッピングなどが発生し易くなり、一方同Ｘ値が同０．０５未満では前記高温硬さにに所望の向上効果が得られないことから、その割合を０．０５〜０．３５と定めた。
【００１０】
（ｂ）Ｚｒ成分最高含有点とＺｒ成分不含有点間の間隔
その間隔が０．０１μm未満ではそれぞれの点を上記の組成で明確に形成することが困難であり、この結果層に所望の高強度および高靭性、さらに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Ｚｒ成分最高含有点であれば強度および靭性不足、Ｚｒ不含有点であれば高温硬さ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。
【００１１】
（ｄ）硬質被覆層の全体平均層厚
その層厚が１μｍ未満では、所望の耐摩耗性を確保することができず、一方その平均層厚が１５μｍを越えると、チッピングが発生し易くなることから、その平均層厚を１〜１５μｍと定めた。
【００１２】
【発明の実施の形態】
つぎに、この発明の被覆超硬工具を実施例により具体的に説明する。
（実施例１）
原料粉末として、いずれも１〜３μｍの平均粒径を有するＷＣ粉末、ＴｉＣ粉末、ＶＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃｒ₃Ｃ₂粉末、およびＣｏ粉末を用意し、これら原料粉末を、表１に示される配合組成に配合し、ボールミルで７２時間湿式混合し、乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を６Ｐａの真空中、温度：１４００℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０３のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１２０４０８のチップ形状をもったＷＣ基超硬合金製の超硬基体Ａ１〜Ａ１０を形成した。
【００１３】
また、原料粉末として、いずれも０．５〜２μｍの平均粒径を有するＴｉＣＮ（重量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ₂Ｃ粉末、ＺｒＣ粉末、ＮｂＣ粉末、ＴａＣ粉末、ＷＣ粉末、Ｃｏ粉末、およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで２４時間湿式混合し、乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を２ｋＰａの窒素雰囲気中、温度：１５００℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０３のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１２０４０８のチップ形状をもったＴｉＣＮ系サーメット製の超硬基体Ｂ１〜Ｂ６を形成した。
【００１４】
ついで、上記の超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６のそれぞれを、アセトン中で超音波洗浄し、乾燥した状態で、図１に示されるアークイオンプレーティング装置内の回転テーブル上に外周部にそって装着し、一方側のカソード電極（蒸発源）として、種々の成分組成をもったＺｒ成分最高含有点形成用Ｔｉ−Ｚｒ合金、他方側のカソード電極（蒸発源）としてＺｒ成分不含有点形成用金属Ｔｉを前記回転テーブルを挟んで対向配置し、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、他方側のカソード電極である前記金属Ｔｉとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＴｉボンバート洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して４Ｐａ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て、それぞれのカソード電極(前記Ｚｒ成分最高含有点形成用Ｔｉ−Ｚｒ合金およびＺｒ成分不含有点形成用金属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Ｚｒ成分最高含有点とＺｒ成分不含有点（ＴｉＮ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Ｚｒ成分最高含有点から前記Ｚｒ成分不含有点、前記Ｚｒ成分不含有点から前記Ｚｒ成分最高含有点へＺｒ成分含有量が連続的に変化する成分濃度分布構造を有し、かつ同じく表３，４に示される目標全体層厚の硬質被覆層を蒸着することにより、図３（ａ）に概略斜視図で、同（ｂ）に概略縦断面図で示される形状を有する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。
【００１５】
また、比較の目的で、これら超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６を、アセトン中で超音波洗浄し、乾燥した状態で、それぞれ図２に示される通常のアークイオンプレーティング装置に装入し、カソード電極（蒸発源）として種々の成分組成をもったＴｉ−Ｚｒ合金を装着し、またボンバート洗浄用金属Ｔｉも装着し、まず、装置内を排気して０．５Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、前記超硬基体に−８００Ｖの直流バイアス電圧を印加し、カソード電極の前記金属Ｔｉとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＴｉボンバート洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して４Ｐａの反応雰囲気とすると共に、前記超硬基体に印加するバイアス電圧を−１００Ｖに下げて、前記カソード電極とアノード電極との間にアーク放電を発生させ、もって前記超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６のそれぞれの表面に、表５，６に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ｚｒ）Ｎ層からなる硬質被覆層を蒸着することにより、同じく図３に示される形状の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。
【００１６】
つぎに、上記本発明被覆超硬チップ１〜１６および従来被覆超硬チップ１〜１６について、これを工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、
被削材：ＪＩＳ・ＳＣＭ４４０の丸棒、
切削速度：１６０ｍ／ｍｉｎ．、
切り込み：６．０ｍｍ、
送り：０．１８ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での合金鋼の乾式連続高切り込み切削加工試験、
被削材：ＪＩＳ・Ｓ４５Ｃの長さ方向等間隔４本縦溝入り丸棒、
切削速度：１６０ｍ／ｍｉｎ．、
切り込み：１．２ｍｍ、
送り：０．６５ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での炭素鋼の乾式断続高送り切削加工試験、さらに、
被削材：ＪＩＳ・ＦＣ３００の丸棒、
切削速度：２００ｍ／ｍｉｎ．、
切り込み：６．０ｍｍ、
送り：０．１８ｍｍ／ｒｅｖ．、
切削時間：８分、
の条件での鋳鉄の乾式連続高切り込み切削加工試験を行い、いずれの切削加工試験でも切刃の逃げ面摩耗幅を測定した。この測定結果を表３〜６に示した。
【００１７】
【表１】

【００１８】
【表２】

【００１９】
【表３】

【００２０】
【表４】

【００２１】
【表５】

【００２２】
【表６】

【００２３】
（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２４時間ボールミル混合し、減圧乾燥した後、１００ＭＰａの圧力で所定形状の各種の圧粉体にプレス成形し、これらの圧粉体を、６Ｐａの真空雰囲気中、７℃／分の昇温速度で１３７０〜１４７０℃の範囲内の所定の温度に昇温し、この温度に１時間保持後、炉冷の条件で焼結して、直径が８ｍｍ、１３ｍｍ、および２６ｍｍの３種の超硬基体形成用丸棒焼結体を形成し、さらに前記の３種の丸棒焼結体から、研削加工にて、表７に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法をもった超硬基体（エンドミル）Ｃ−１〜Ｃ−８をそれぞれ製造した。
【００２４】
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Ｚｒ成分最高含有点とＺｒ成分不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Ｚｒ成分最高含有点から前記Ｚｒ成分不含有点、前記Ｚｒ成分不含有点から前記Ｚｒ成分最高含有点へＺｒ成分含有量が連続的に変化する成分濃度分布構造を有し、かつ同じく表８に示される目標全体層厚の硬質被覆層を蒸着することにより、図４（ａ）に概略正面図で、同（ｂ）に切刃部の概略横断面図で示される形状を有する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。
【００２５】
また、比較の目的で、上記の超硬基体（エンドミル）Ｃ−１〜Ｃ−８を、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表９に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ｚｒ）Ｎ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製エンドミル（以下、従来被覆超硬エンドミルと云う）１〜８をそれぞれ製造した。
【００２６】
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：４０ｍ／ｍｉｎ．、
溝深さ（切り込み）：５ｍｍ、
テーブル送り：１５０ｍｍ／分、
の条件での工具鋼の乾式高切り込み溝切削加工試験、本発明被覆超硬エンドミル４〜６および従来被覆超硬エンドミル４〜６については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＵＳ３０４の板材、
切削速度：８０ｍ／ｍｉｎ．、
溝深さ（切り込み）：５ｍｍ、
テーブル送り：４００ｍｍ／分、
の条件でのステンレス鋼の乾式高送り溝切削加工試験、本発明被覆超硬エンドミル７，８および従来被覆超硬エンドミル７，８については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＮＣＭ４３９の板材、
切削速度：１００ｍ／ｍｉｎ．、
溝深さ（切り込み）：２０ｍｍ、
テーブル送り：４００ｍｍ／分、
の条件での合金鋼の乾式高切り込み溝切削加工試験をそれぞれ行い、いずれの溝切削加工試験でも切刃部の外周刃の逃げ面摩耗幅が使用寿命の目安とされる０．１ｍｍに至るまでの切削溝長を測定した。この測定結果を表８、９にそれぞれ示した。
【００２７】
【表７】

【００２８】
【表８】

【００２９】
【表９】

【００３０】
（実施例３）
上記の実施例２で製造した直径が８ｍｍ（超硬基体Ｃ−１〜Ｃ−３形成用）、１３ｍｍ（超硬基体Ｃ−４〜Ｃ−６形成用）、および２６ｍｍ（超硬基体Ｃ−７、Ｃ−８形成用）の３種の丸棒焼結体を用い、この３種の丸棒焼結体から、研削加工にて、溝形成部の直径×長さがそれぞれ４ｍｍ×１３ｍｍ（超硬基体Ｄ−１〜Ｄ−３）、８ｍｍ×２２ｍｍ（超硬基体Ｄ−４〜Ｄ−６）、および１６ｍｍ×４５ｍｍ（超硬基体Ｄ−７、Ｄ−８）の寸法をもった超硬基体（ドリル）Ｄ−１〜Ｄ−８をそれぞれ製造した。
【００３１】
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Ｚｒ成分最高含有点とＺｒ成分不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Ｚｒ成分最高含有点から前記Ｚｒ成分不含有点、前記Ｚｒ成分不含有点から前記Ｚｒ成分最高含有点へＺｒ成分含有量が連続的に変化する成分濃度分布構造を有し、かつ同じく表１０に示される目標全体層厚の硬質被覆層を蒸着することにより、図５（ａ）に概略正面図で、同（ｂ）に溝形成部の概略横断面図で示される形状を有する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。
【００３２】
また、比較の目的で、上記の超硬基体（ドリル）Ｄ−１〜Ｄ−８の切刃に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表１１に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ｚｒ）Ｎ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製ドリル（以下、従来被覆超硬ドリルと云う）１〜８をそれぞれ製造した。
【００３３】
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・ＳＫＤ６１の板材、
切削速度：２５ｍ／ｍｉｎ．、
送り：０．２５ｍｍ／ｒｅｖ、
穴深さ：１０ｍｍ、
の条件での工具鋼の湿式高送り穴あけ切削加工試験、本発明被覆超硬ドリル４〜６および従来被覆超硬ドリル４〜６については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＦＣＤ４００の板材、
切削速度：４５ｍ／ｍｉｎ．、
送り：０．５ｍｍ／ｒｅｖ、
穴深さ：１５ｍｍ、
の条件でのダクタイル鋳鉄の湿式高送り穴あけ切削加工試験、本発明被覆超硬ドリル７，８および従来被覆超硬ドリル７，８については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＦＣ３００の板材、
切削速度：８０ｍ／ｍｉｎ．、
送り：０．８ｍｍ／ｒｅｖ、
穴深さ：３０ｍｍ、
の条件での鋳鉄の湿式高送り穴あけ切削加工試験、をそれぞれ行い、いずれの湿式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。
【００３４】
【表１０】

【００３５】
【表１１】

【００３６】
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Ｚｒ成分最高含有点とＺｒ成分不含有点の組成、並びに従来被覆超硬工具としての従来被覆超硬チップ１〜１６、従来被覆超硬エンドミル１〜８、および従来被覆超硬ドリル１〜８の硬質被覆層の組成をオージェ電子分光分析装置を用いて測定したところ、それぞれ目標組成と実質的に同じ組成を示した。
また、これらの本発明被覆超硬工具の硬質被覆層におけるＺｒ成分最高含有点とＺｒ成分不含有点間の間隔、およびこれの全体層厚、並びに従来被覆超硬工具の硬質被覆層の厚さを、走査型電子顕微鏡を用いて断面測定したところ、いずれも目標値と実質的に同じ値を示した。
【００３７】
【発明の効果】
表３〜１１に示される結果から、硬質被覆層が層厚方向に、すぐれた高温硬さを有するＺｒ成分最高含有点と高強度と高靭性を有するＺｒ成分不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Ｚｒ成分最高含有点から前記Ｚｒ成分不含有点、前記Ｚｒ成分不含有点から前記Ｚｒ成分最高含有点へＺｒ成分含有量が連続的に変化する成分濃度分布構造を有する本発明被覆超硬工具は、いずれも各種の鋼や鋳鉄などの切削加工を、高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、硬質被覆層がすぐれた耐チッピング性を発揮するのに対して、硬質被覆層が層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ｚｒ）Ｎ層からなる従来被覆超硬工具においては、前記硬質被覆層がすぐれた高温硬さを有するものの、強度および靭性に劣るものであるために、チッピングが発生し、これが原因で比較的短時間で使用寿命に至ることが明らかである。
上述のように、この発明の被覆超硬工具は、通常の条件での切削加工は勿論のこと、特に各種の鋼や鋳鉄などの切削加工を、高い機械的衝撃を伴う高切り込みや高送りなどの重切削条件で行なった場合にも、すぐれた耐チッピング性を発揮し、長期に亘ってすぐれた耐摩耗性を示すものであるから、切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。
【図面の簡単な説明】
【図１】この発明の被覆超硬工具を構成する硬質被覆層を形成するのに用いたアークイオンプレーティング装置を示し、（ａ）は概略平面図、（ｂ）は概略正面図である。
【図２】従来被覆超硬工具を構成する硬質被覆層を形成するのに用いた通常のアークイオンプレーティング装置の概略説明図である。
【図３】（ａ）は被覆超硬チップの概略斜視図、（ｂ）は被覆超硬チップの概略縦断面図である。
【図４】（ａ）は被覆超硬エンドミル概略正面図、（ｂ）は同切刃部の概略横断面図である。
【図５】（ａ）は被覆超硬ドリルの概略正面図、（ｂ）は同溝形成部の概略横断面図である。[0001]
BACKGROUND OF THE INVENTION
In the present invention, the hard coating layer has high strength and high toughness, and high high temperature hardness. Therefore, cutting of various types of steel and cast iron is particularly important for heavy cutting such as high cutting and high feed with high mechanical impact. The present invention relates to a surface-coated cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide tool) that exhibits excellent chipping resistance when a hard coating layer is used under cutting conditions.
[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). ) And a composite nitride of Ti and Zr satisfying the composition formula: (Ti _1-X Zr _X ) N (wherein X is 0.05 to 0.35 in atomic ratio) [hereinafter, ( Coated carbide tools formed by physical vapor deposition of a hard coating layer composed of a layer represented by Ti, Zr) N] with an average layer thickness of 1 to 15 μm have been proposed for continuous cutting and intermittent cutting of various steels and cast irons. It is used.
[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 a state heated to a temperature of 500 ° C., an arc discharge is generated between the anode electrode and a cathode electrode (evaporation source) in which a Ti—Zr alloy having a predetermined composition is set, for example, under 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, while the cemented carbide substrate is applied to the surface of the cemented carbide substrate with a bias voltage of, for example, −100 V applied. It is also known that it is produced by vapor-depositing a hard coating layer composed of the (Ti, Zr) N layer.
[0005]
[Problems to be solved by the invention]
In recent years, there has been a remarkable increase in the performance of cutting devices. On the other hand, there are strong demands for labor saving, energy saving, and cost reduction for cutting. Although there is a tendency to be performed under heavy cutting conditions such as feeding, there is no problem in using the above conventional coated carbide tools under normal cutting conditions, but the cutting work has a high mechanical impact. When performed under heavy cutting conditions such as high cutting and high feed, chipping (microcracking) is likely to occur, especially due to insufficient strength and toughness of the hard coating layer, resulting in a shorter service life. is the current situation.
[0006]
[Means for Solving the Problems]
In view of the above, the present inventors configured 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 heavy cutting. As a result of conducting research, focusing on the hard coating layer
(A) The (Ti, Zr) N layer constituting the conventional coated carbide tool formed using the arc ion plating apparatus shown in FIG. 2 has a substantially uniform composition throughout the layer thickness. Arc ion plating apparatus having a structure shown in FIG. 1 (a) in a schematic plan view and in FIG. 1 (b) in a schematic front view. That is, a rotating table for mounting a carbide substrate is provided in the center of the apparatus, and a Ti—Zr alloy containing a Zr component on one side and metal Ti on the other side as a cathode electrode (evaporation source) with the rotating table interposed therebetween. Using an arc ion plating apparatus arranged opposite to each other, a plurality of carbide substrates are mounted in a ring shape along the outer periphery of the rotary table of the apparatus, and in this state, the atmosphere in the apparatus is changed to a nitrogen atmosphere. Arc discharge between the cathode electrode (evaporation source) and the anode electrode on both sides while rotating the table and rotating the carbide substrate itself for the purpose of uniforming the thickness of the hard coating layer to be deposited. To form a (Ti, Zr) N layer on the surface of the cemented carbide substrate, the resulting (Ti, Zr) N layer has a ring-shaped arrangement on the rotating table. Is the point closest to the cathode electrode (evaporation source) of the Ti-Zr alloy on one side, the highest content point of Zr component is formed in the layer, and the carbide substrate is the cathode of the metal Ti on the other side. TiN points (Zr component-free points) are formed in the layer at the point closest to the electrode, and the Zr component highest content point and Zr component-free in the layer thickness direction in the layer by the rotation of the rotary table. The dots are evenly spaced And a component concentration distribution structure in which the Zr component content continuously changes from the Zr component highest content point to the Zr component non-contained point and from the Zr lowest content point to the Zr component non-contained point. To be like that.
[0007]
(B) In the (Ti, Zr) N layer of the repeated continuous change component concentration distribution structure of (a) above, the Zr component content in the Ti—Zr alloy which is the cathode electrode (evaporation source) on one side of the opposing arrangement is described above. The conventional Ti-Zr alloy is equivalent to the Zr component content of the conventional Ti-Zr alloy, and the rotational speed of the rotary table on which the carbide substrate is mounted is controlled,
The highest Zr component content point is the composition formula: (Ti _1-X Zr _X ) N (wherein X is 0.05 to 0.35 in atomic ratio),
And the distance in the thickness direction between the adjacent Zr component highest content point and the Zr component non-contained point adjacent to each other is 0.01 to 0.1 μm,
The above Zr component highest content point portion shows the strength and toughness of the conventional (Ti, Zr) N layer, and excellent properties corresponding to high temperature hardness, while the Zr component non-content point portion is substantially Since the Zr component content is remarkably low centering on the TiN point, the high strength and high toughness of TiN are ensured, and the distance between the highest Zr component content point and the Zr component non-contained point is extremely small. Therefore, the coating layer is composed of a (Ti, Zr) N layer having such a structure that the hard coating layer is provided with excellent strength and toughness while maintaining excellent high-temperature hardness as a characteristic of the entire layer. Carbide tools have excellent chipping resistance, especially when cutting various steels and cast irons under heavy cutting conditions such as high cutting with high mechanical impact and high feed. To become able to volatilization.
The research results shown in (a) and (b) above were obtained.
[0008]
The present invention has been made based on the above research results. A hard coating layer made of a (Ti, Zr) N layer is physically vapor-deposited on the surface of a cemented carbide substrate with an overall average layer thickness of 1 to 15 μm. In the coated carbide tool
In the hard coating layer, Zr component highest content point (Ti component lowest content point) and Zr component non-content point (TiN point) are alternately present at predetermined intervals along the layer thickness direction, and A component concentration distribution structure in which the Zr component content continuously changes from the Zr component highest content point to the Zr component non-content point, from the Zr component non-content point to the Zr component highest content point,
Further, the highest Zr component content point is the composition formula: (Ti _1-X Zr _X ) N (wherein X is 0.05 to 0.35 in atomic ratio),
And the interval between the adjacent Zr component highest content point and the Zr component non-contained point adjacent to each other is 0.01 to 0.1 μm.
It is characterized by a coated cemented carbide tool that exhibits excellent chipping resistance in a hard coating layer in heavy cutting.
[0009]
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 Zr component highest content point (Ti, Zr) The Zr component in the N layer is contained for the purpose of improving the high temperature hardness of the TiN layer having high strength and high toughness. The higher the content ratio, the higher the high-temperature hardness. However, when the X value indicating the ratio of Zr is higher than 0.35 in terms of the total amount with Ti (atomic ratio), high strength and Even if TiN points having high toughness are present adjacently, a decrease in the strength and toughness of the layer itself is unavoidable, and as a result, chipping and the like are likely to occur. Since the desired improvement effect in hardness cannot be obtained, the ratio was determined to be 0.05 to 0.35.
[0010]
(B) Interval between Zr component highest content point and Zr component non-content point If the distance is less than 0.01 μm, it is difficult to clearly form each point with the above composition. Strength and high toughness, and high temperature hardness cannot be ensured, and if the distance exceeds 0.1 μm, the disadvantages of each point, that is, if the Zr component is the highest content point, insufficient strength and toughness, If it is a content point, insufficient high-temperature hardness appears locally in the layer, which makes it easy for chipping to occur and promotes the progress of wear. It was set to 1 μm.
[0011]
(D) Overall average layer thickness of hard coating layer If the layer thickness is less than 1 μm, 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 1 to 15 μm.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated carbide tool of the present invention will be specifically described with reference to examples.
Example 1
As raw material powders, WC powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder, all having an average particle diameter of 1 to 3 μm, were prepared. And then wet-mixed with a ball mill for 72 hours, dried, and press-molded into a green compact at a pressure of 100 MPa. The green compact was vacuumed at 6 Pa at a temperature of 1400 ° C. for 1 hour. Sintered under the holding conditions, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03, and the carbide bases A1 to A10 made of WC-based cemented carbide having ISO / CNMG120408 chip shape Formed.
[0013]
In addition, as raw material powders, all are TiCN (weight ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder having an average particle diameter of 0.5 to 2 μm. Co powder and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed into a compact at a pressure of 100 MPa. The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to obtain ISO standard / CNMG120408. TiCN-based cermet carbide substrates B1 to B6 having the following chip shape were formed.
[0014]
Next, each of the above-mentioned carbide substrates A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, on the rotary table in the arc ion plating apparatus shown in FIG. Therefore, as one cathode electrode (evaporation source), a Zr component highest content point forming Ti-Zr alloy having various component compositions, and as the other cathode electrode (evaporation source) no Zr component-containing point The forming metal Ti is disposed opposite to the rotary table, and first, the interior of the apparatus is heated to 500 ° C. with a heater while evacuating the apparatus and maintaining a vacuum of 0.5 Pa or less. A DC bias voltage of −1000 V is applied to a carbide substrate that rotates while rotating, and a current of 100 A flows between the metal Ti, which is the cathode electrode on the other side, and the anode electrode. An arc discharge is generated, and the surface of the carbide substrate is cleaned by Ti bombardment. Then, nitrogen gas is introduced into the apparatus as a reaction gas to form a 4 Pa reaction atmosphere, and the carbide rotating while rotating on the rotary table. A DC bias voltage of −100 V was applied to the substrate, and 100 A of each cathode electrode (the Zr component highest-containing point forming Ti—Zr alloy and the Zr component-free point forming metal Ti) and an anode electrode An arc discharge is generated by passing an electric current, so that the Zr component highest content point and Zr component non-contained point (TiN point) of the target composition shown in Tables 3 and 4 along the layer thickness direction on the surface of the cemented carbide substrate. Are alternately present at the target intervals shown in Tables 3 and 4, and the Zr component non-contained point from the Zr component highest content point, and the Zr component free point from the Zr component non-contained point. By depositing a hard coating layer having a component concentration distribution structure in which the Zr component content continuously changes to the highest content point and also having the target overall layer thickness shown in Tables 3 and 4, FIG. ) Is a schematic perspective view of the present invention, and the surface coated cemented carbide throwaway tip of the present invention as a coated carbide tool of the present invention having the shape shown in FIG. 1 to 16 were produced.
[0015]
Further, for the purpose of comparison, these carbide substrates A1 to A10 and B1 to B6 are ultrasonically cleaned in acetone and dried, and then loaded into a normal arc ion plating apparatus shown in FIG. In addition, Ti-Zr alloys with various component compositions are mounted as cathode electrodes (evaporation sources), and 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. However, after heating the inside of the apparatus to 500 ° C. with a heater, a DC bias voltage of −800 V was applied to the cemented carbide substrate, and a current of 100 A was passed between the metal Ti of the cathode electrode and the anode electrode to cause arc discharge. Thus, the surface of the carbide substrate is cleaned by Ti bombardment, and then nitrogen gas is introduced into the apparatus as a reaction gas to form a 4 Pa reaction atmosphere, and the carbide substrate is marked. The bias voltage is reduced to −100 V to generate an arc discharge between the cathode electrode and the anode electrode, and the surfaces of the carbide substrates A1 to A10 and B1 to B6 are shown in Tables 5 and 6, respectively. The shape shown in FIG. 3 is also obtained by depositing a hard coating layer composed of a (Ti, Zr) N layer having a target composition and a target layer thickness and having substantially no composition change along the layer thickness direction. Conventional surface-coated cemented carbide throwaway tips (hereinafter referred to as conventional coated carbide tips) 1 to 16 as conventional coated carbide tools were manufactured.
[0016]
Next, with the present invention coated carbide tips 1-16 and conventional coated carbide tips 1-16, in a state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SCM440 round bar,
Cutting speed: 160 m / min. ,
Cutting depth: 6.0 mm,
Feed: 0.18 mm / rev. ,
Cutting time: 8 minutes
Dry continuous high-cut cutting test of alloy steel under the conditions of
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 160 m / min. ,
Cutting depth: 1.2mm,
Feed: 0.65 mm / rev. ,
Cutting time: 8 minutes
Carbon steel dry intermittent high feed cutting test under the conditions of
Work material: JIS / FC300 round bar,
Cutting speed: 200 m / min. ,
Cutting depth: 6.0 mm,
Feed: 0.18 mm / rev. ,
Cutting time: 8 minutes
The dry continuous 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 Tables 3-6.
[0017]
[Table 1]

[0018]
[Table 2]

[0019]
[Table 3]

[0020]
[Table 4]

[0021]
[Table 5]

[0022]
[Table 6]

[0023]
(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, ball milled in acetone for 24 hours, dried under reduced pressure, 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. X Carbide substrates (end mills) C-1 to C-8 having lengths of 6 mm x 13 mm, 10 mm x 22 mm, and 20 mm x 45 mm, respectively, were produced.
[0024]
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 Zr component highest content point and the Zr component non-contained 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 having a component concentration distribution structure in which the Zr component content continuously changes from the Zr component highest content point to the Zr component non-content point, from the Zr component non-content point to the Zr component highest content point, and By depositing a hard coating layer having a target overall layer thickness shown in FIG. 8, the present invention has a shape shown in a schematic front view in FIG. 4 (a) and in a schematic cross-sectional view of the cutting edge portion in FIG. 4 (b). Surface-coated carbide of the present invention as a coated carbide tool Gold end mill (hereinafter, the present invention refers to the coating end mills) 1-8 were prepared, respectively.
[0025]
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, Zr) N having the target composition and target layer thickness shown in Table 9 and substantially no composition change along the layer thickness direction under the same conditions as in Example 1 above. By vapor-depositing a hard coating layer consisting of layers, conventional surface-coated cemented carbide end mills (hereinafter referred to as conventional coated carbide end mills) 1 to 8 as conventional coated carbide tools were produced, respectively.
[0026]
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: 40 m / min. ,
Groove depth (cut): 5 mm,
Table feed: 150 mm / min,
With respect to the tool steel dry type high cutting groove cutting test under the conditions of the present invention, the coated carbide end mills 4-6 of the present invention and the conventional coated carbide end mills 4-6,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 80 m / min. ,
Groove depth (cut): 5 mm,
Table feed: 400mm / min,
With respect to the dry high feed grooving test of stainless steel under the following conditions, the coated carbide end mills 7 and 8 of the present invention and the conventional coated carbide end mills 7 and 8:
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SNCM439 plate material,
Cutting speed: 100 m / min. ,
Groove depth (cut): 20 mm,
Table feed: 400mm / min,
In each of the groove cutting tests, the flank wear width of the outer peripheral edge of the cutting edge reaches 0.1 mm, which is a guide for the service life. The cutting groove length of was measured. The measurement results are shown in Tables 8 and 9, respectively.
[0027]
[Table 7]

[0028]
[Table 8]

[0029]
[Table 9]

[0030]
(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, D-8) Hard substrates (drills) D-1 to D-8 were produced, respectively.
[0031]
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 Zr component highest content point and the Zr component non-content point of the target composition shown in Table 10 along the layer thickness direction are also shown in Table 10 alternately. Component concentration distribution structure that repeatedly exists at a target interval, and in which the Zr component content continuously changes from the highest Zr component content point to the non-Zr component content point and from the Zr component non-content point to the highest Zr component content point And a hard coating layer having a target overall layer thickness also shown in Table 10 is vapor-deposited, and FIG. 5 (a) is a schematic front view, and FIG. 5 (b) is a schematic cross-sectional view of a groove forming portion. The invention coated carbide with the shape shown The present invention surface coating cemented carbide drill as (hereinafter, the present invention refers to the coating carbide drills) 1-8 were prepared, respectively.
[0032]
For comparison purposes, the cutting edges of the above-mentioned carbide substrates (drills) D-1 to D-8 are honed, ultrasonically cleaned in acetone, and dried, as shown in FIG. The sample was charged into a normal arc ion plating apparatus, had the target composition and target layer thickness shown in Table 11 under the same conditions as in Example 1, and substantially changed in composition along the layer thickness direction. By vapor-depositing a hard coating layer comprising no (Ti, Zr) 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.
[0033]
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 × 250 mm, thickness: 50 mm JIS / SKD61 plate material,
Cutting speed: 25 m / min. ,
Feed: 0.25mm / rev,
Hole depth: 10mm,
For the wet high feed drilling test of tool steel under the conditions of the present invention, the coated carbide drills 4-6 of the present invention and the conventional coated carbide drills 4-6,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / FCD400 plate material,
Cutting speed: 45 m / min. ,
Feed: 0.5mm / rev,
Hole depth: 15mm,
For the wet high feed drilling test of ductile cast iron under the conditions of the present invention, the coated carbide drills 7 and 8 of the present invention and the conventional coated carbide drills 7 and 8,
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS / FC300 plate material,
Cutting speed: 80 m / min. ,
Feed: 0.8mm / rev,
Hole depth: 30mm,
Each of the wet high-feed drilling tests of cast iron under the above conditions was conducted, and the flank wear width of the tip cutting edge surface reached 0.3 mm in any wet high-speed drilling test (using water-soluble cutting oil). The number of holes drilled was measured. The measurement results are shown in Tables 10 and 11, respectively.
[0034]
[Table 10]

[0035]
[Table 11]

[0036]
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 Zr component highest content point and Zr component non-content point, as well as conventional coated carbide tips 1-16, conventional coated carbide end mills 1-8, and conventional coated carbide drills 1-8 as conventional coated carbide tools When the composition of the hard coating layer was measured using an Auger electron spectroscopy analyzer, the composition was substantially the same as the target composition.
Further, the distance between the highest Zr component-containing point and the Zr component-free point in the hard coating layer of these coated carbide tools of the present invention, and the overall layer thickness thereof, and the thickness of the hard coating layer of the conventional coated carbide tool When the cross section was measured using a scanning electron microscope, all showed substantially the same value as the target value.
[0037]
【The invention's effect】
From the results shown in Tables 3 to 11, the hard coating layer has a Zr component highest content point having excellent high temperature hardness and a Zr component non-content point having high strength and high toughness alternately in the layer thickness direction at predetermined intervals. Component concentration distribution structure in which the Zr component content continuously changes from the highest Zr component content point to the Zr component non-contained point and the Zr component non-content point to the highest Zr component content point The coated carbide tool of the present invention has a hard coating layer even when cutting various steels and cast iron under heavy cutting conditions such as high cutting with high mechanical impact and high feed. In the conventional coated carbide tool having a (Ti, Zr) N layer in which the hard coating layer has substantially no composition change along the layer thickness direction while exhibiting excellent chipping resistance, High temperature hardness with excellent layer That although, because of inferior strength and toughness, chipping occurs and this is apparent that lead to a relatively short time service life due.
As described above, the coated carbide tool of the present invention can be used not only for cutting under normal conditions, but also for cutting various steels and cast irons. Even under heavy cutting conditions, it exhibits excellent chipping resistance and excellent wear resistance over a long period of time. It can respond satisfactorily.
[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.
FIG. 3A is a schematic perspective view of a coated carbide chip, and FIG. 3B is a schematic longitudinal sectional view of the coated carbide chip.
4A is a schematic front view of a coated carbide end mill, and FIG. 4B is a schematic cross-sectional view of the cutting edge portion.
5A is a schematic front view of a coated carbide drill, and FIG. 5B is a schematic cross-sectional view of the groove forming portion.

Claims

Surface-coated carbide formed by physical vapor deposition of a hard coating layer composed of a composite nitride layer of Ti and Zr on the surface of a tungsten carbide base cemented carbide substrate or a titanium carbonitride-based cermet substrate with an overall average layer thickness of 1 to 15 μm. In the alloy cutting tool, the hard coating layer has a Zr component highest content point (Ti component lowest content point) and a Zr component non-content point (TiN point) alternately at predetermined intervals along the layer thickness direction. It has a component concentration distribution structure that repeatedly exists and the Zr component content continuously changes from the Zr component highest content point to the Zr component non-contained point and from the Zr component non-content point to the Zr component highest content point. ,
Further, the highest Zr component content point is the composition formula: (Ti _1-X Zr _X ) N (wherein X is 0.05 to 0.35 in atomic ratio),
And the interval between the adjacent Zr component highest content point and the Zr component non-contained point adjacent to each other is 0.01 to 0.1 μm,
A surface-coated cemented carbide cutting tool that exhibits excellent chipping resistance with a hard coating layer that is characterized by heavy cutting.