JP2004042170A

JP2004042170A - Surface-coated cemented carbide cutting tool having hard coating layer for exhibiting superior chipping resistance under high speed double cutting condition

Info

Publication number: JP2004042170A
Application number: JP2002201280A
Authority: JP
Inventors: Koichi Maeda; 前田　浩一; Akihiro Kondou; 近藤　暁裕; Yusuke Tanaka; 田中　裕介
Original assignee: Mitsubishi Materials Corp; Mitsubishi Materials Kobe Tools Corp
Current assignee: Mitsubishi Materials Corp; Mitsubishi Materials Kobe Tools Corp
Priority date: 2002-07-10
Filing date: 2002-07-10
Publication date: 2004-02-12
Anticipated expiration: 2022-07-10
Also published as: JP4007102B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cemented carbide cutting tool having a hard coating layer for exhibiting superior chipping resistance under a high speed double cutting condition. <P>SOLUTION: The hard coating layer in the surface-coated cemented carbide cutting tool is formed by physically depositing the hard covering layer composed of a composite nitride layer of Ti, Al and Ta in the whole average layer thickness of 1 to 15 μm on a surface of a tungsten carbide group cemented carbide base body or a titanium carbonitride cermet base body, and is composed of a hard coating layer having a component concentration distribution structure for allowing an Al maximum including point and an Al minimum including point to alternately repeatedly exist at a prescribed interval in the layer thickness direction, and allowing the Al content to continuously change to the Al minimum including point from the Al maximum including point and to the Al maximum including point from the Al minimum including point. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層が高強度を有し、かつ高温硬さと耐熱性にもすぐれ、したがって特に各種の鋼や鋳鉄などの高速切削加工を、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−（Ｘ＋Ｚ）}Ａｌ_ＸＴａ_Ｚ）Ｎ（ただし、原子比で、Ｘは０．４５〜０．６０、Ｔａ：０．０５〜０．２０を示す）を満足するＴｉとＡｌとＴａの複合窒化物［以下、（Ｔｉ，Ａｌ，Ｔａ）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、前記硬質被覆層を構成する（Ｔｉ，Ａｌ，Ｔａ）Ｎ層が、Ａｌによる高温硬さと耐熱性、Ｔｉによる強度を有し、さらにＴａによる一段の高温硬さを具備することと相俟って、かかる被覆超硬工具を各種の鋼や鋳鉄などの連続切削や断続切削加工を高速切削条件で行なった場合にすぐれた切削性能を発揮することも知られている。
【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−Ａｌ−Ｔａ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，Ａｌ，Ｔａ）Ｎ層からなる硬質被覆層を蒸着することにより製造されることも知られている。
【０００５】
【発明が解決しようとする課題】
近年の切削加工装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求は強く、これに伴い、切削加工は高速化の傾向を強め、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を余儀なくされる傾向にあるが、上記の従来被覆超硬工具においては、これを高速切削加工条件で用いた場合には問題はないが、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を高速で行なった場合には、特に硬質被覆層の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。
【０００６】
【課題を解決するための手段】
そこで、本発明者等は、上述のような観点から、特に高速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，Ａｌ，Ｔａ）Ｎ層は、層厚全体に亘って実質的に均一な組成を有し、したがって均質な高温硬さと耐熱性、さらに強度を有するが、例えば図１（ａ）に概略平面図で、同（ｂ）に概略正面図で示される構造のアークイオンプレーティング装置、すなわち装置中央部に超硬基体装着用回転テーブルを設け、前記回転テーブルを挟んで、一方側にＡｌ最高含有点形成用Ｔｉ−Ａｌ−Ｔａ合金、他方側にＡｌ最低含有点形成用Ｔｉ−Ａｌ−Ｔａ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の中心軸から半径方向に所定距離離れた位置に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，Ａｌ，Ｔａ）Ｎ層を形成すると、この結果の（Ｔｉ，Ａｌ，Ｔａ）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−Ａｌ−Ｔａ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Ａｌ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Ｔｉ−Ａｌ−Ｔａ合金のカソード電極に最も接近した時点で層中にＡｌ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Ａｌ最高含有点とＡｌ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Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ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，Ａｌ，Ｔａ）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−Ａｌ−Ｔａ合金におけるＡｌおよびＴａ含有量を上記の従来（Ｔｉ，Ａｌ，Ｔａ）Ｎ層形成用Ｔｉ−Ａｌ−Ｔａ合金のＡｌおよびＴａ含有量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−Ａｌ−Ｔａ合金におけるＡｌ含有量を上記の従来Ｔｉ−Ａｌ−Ｔａ合金のＡｌ含有量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Ａｌ最高含有点が、組成式：（Ｔｉ_{１−（Ｘ＋Ｚ）}Ａｌ_ＸＴａ_Ｚ）Ｎ（ただし、原子比で、Ｘは０．４５〜０．６０、Ｚ：０．０５〜０．２０を示す）、
上記Ａｌ最低含有点が、組成式：（Ｔｉ_{１−（Ｘ＋Ｚ）}Ａｌ_ＸＴａ_Ｚ）Ｎ（ただし、原子比で、Ｘは０．１０〜０．２５、Ｚ：０．０５〜０．２０を示す）、
を満足し、かつ隣り合う上記Ａｌ最高含有点とＡｌ最低含有点の厚さ方向の間隔を０．０１〜０．１μｍとすると、
上記Ａｌ最高含有点部分では、上記の従来（Ｔｉ，Ａｌ，Ｔａ）Ｎ層のもつ高温硬さと耐熱性に相当する高温硬さと耐熱性を示し、一方上記Ａｌ最低含有点部分では、前記Ａｌ最高含有点部分に比してＡｌ含有量が低く、相対的にＴｉ含有量の高いものとなるので、一段と高い強度が確保され、かつこれらＡｌ最高含有点とＡｌ最低含有点の間隔をきわめて小さくしたことから、層全体の特性として高温硬さと耐熱性を保持した状態で一段とすぐれた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，Ａｌ，Ｔａ）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、高速で、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。
【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，Ａｌ，Ｔａ）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、Ａｌ最高含有点とＡｌ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Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ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Ａｌ最高含有点が、組成式：（Ｔｉ_{１−（Ｘ＋Ｚ）}Ａｌ_ＸＴａ_Ｚ）Ｎ（ただし、原子比で、Ｘは０．４５〜０．６０、Ｚ：０．０５〜０．２０を示す）、上記Ａｌ最低含有点が、組成式：（Ｔｉ_{１−（Ｘ＋Ｚ）}Ａｌ_ＸＴａ_Ｚ）Ｎ（ただし、原子比で、Ｘは０．１０〜０．２５、Ｚ：０．０５〜０．２０を示す）、
を満足し、かつ隣り合う上記Ａｌ最高含有点とＡｌ最低含有点の間隔が、０．０１〜０．１μｍである、
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。
【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）Ａｌ最高含有点の組成
Ａｌ最高含有点の（Ｔｉ，Ａｌ，Ｔａ）ＮにおけるＴｉ成分は強度を向上させ、同Ａｌ成分は高温硬さおよび耐熱性を向上させ、さらに同Ｔａ成分は一段と高温硬さを向上させる作用があり、したがってＡｌおよびＴａ成分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、高熱発生を伴う高速切削に適合したものになるが、Ａｌの含有割合を示すＸ値がＴｉとＴａの合量に占める割合（原子比）で０．６０を越えても、またＴａの含有割合を示すＺ値が同０．２０を越えても、高強度を有するＡｌ最低含有点が隣接して存在しても層自体の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Ｘ値が同０．４５未満でも、また同Ｚ値が０．０５未満でも高温硬さおよび耐熱性に所望の向上効果が得られないことから、Ｘ値を０．４５〜０．６０、Ｚ値を０．０５〜０．２０と定めた。
【００１０】
（ｂ）Ａｌ最低含有点の組成
上記の通りＡｌ最高含有点は相対的にすぐれた高温硬さおよび耐熱性を有するが、反面相対的に強度が不十分であるため、このＡｌ最高含有点の強度不足を補う目的で、Ｔｉ含有割合が高く、一方Ａｌ含有量が低く、これによって高強度を有するようになるＡｌ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Ａｌの割合を示すＸ値がＴｉおよびＴａ成分との合量に占める割合（原子比）で０．２５を越えると、所望のすぐれた強度を確保することができず、この結果チッピングが発生しやすくなり、一方同Ｘ値が０．１０未満になると、Ａｌ最低含有点に所定の高温硬さおよび耐熱性を確保することができず、摩耗促進の原因となることから、Ａｌ最低含有点でのＡｌの割合を示すＸ値を０．１０〜０．２５と定めた。
Ａｌ最低含有点におけるＴａ成分も、上記の通りＡｌ成分との共存で高温硬さを向上させ、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未満では所望の高温硬さ向上効果が得られず、一方Ｚ値が０．２０を越えるとＡｌ最低含有点での強度に低下傾向が現れるようになり、チッピング発生の原因となることから、Ｚ値を０．０５〜０．２０と定めた。
【００１１】
（ｃ）Ａｌ最高含有点とＡｌ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硬さおよび耐熱性、さらに高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を越えるとそれぞれの点がもつ欠点、すなわちＡｌ最高含有点であれば強度不足、Ａｌ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。
【００１２】
（ｄ）硬質被覆層の全体平均層厚
その層厚が１μｍ未満では、所望の耐摩耗性を確保することができず、一方その平均層厚が１５μｍを越えると、チッピングが発生し易くなることから、その平均層厚を１〜１５μｍと定めた。
【００１３】
【発明の実施の形態】
つぎに、この発明の被覆超硬工具を実施例により具体的に説明する。
（実施例１）
原料粉末として、いずれも１〜３μｍの平均粒径を有するＷＣ粉末、ＴｉＣ粉末、ＶＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃｒ_３Ｃ_２粉末、およびＣｏ粉末を用意し、これら原料粉末を、表１に示される配合組成に配合し、ボールミルで７２時間湿式混合し、乾燥した後、１００ＭＰａ　の圧力で圧粉体にプレス成形し、この圧粉体を６Ｐａの真空中、温度：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。
【００１４】
また、原料粉末として、いずれも０．５〜２μｍの平均粒径を有するＴｉＣＮ（重量比でＴｉＣ／ＴｉＮ＝５０／５０）粉末、Ｍｏ_２Ｃ粉末、ＺｒＣ粉末、ＮｂＣ粉末、ＴａＣ粉末、ＷＣ粉末、Ｃｏ粉末、およびＮｉ粉末を用意し、これら原料粉末を、表２に示される配合組成に配合し、ボールミルで２４時間湿式混合し、乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を２ｋＰａの窒素雰囲気中、温度：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。
【００１５】
ついで、上記の超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６のそれぞれを、アセトン中で超音波洗浄し、乾燥した状態で、図１に示されるアークイオンプレーティング装置内の回転テーブル上の中心軸から半径方向に所定距離離れた位置にテーブル外周部にそって装着し、一方側のカソード電極（蒸発源）として、種々の成分組成をもったＡｌ最高含有点形成用Ｔｉ−Ａｌ−Ｔａ合金、他方側のカソード電極（蒸発源）としてＡｌ最低含有点形成用Ｔｉ−Ａｌ−Ｔａ合金を前記回転テーブルを挟んで対向配置し、またボンバート洗浄用金属Ｔｉも装着し、まず、装置内を排気して０．５Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、前記回転テーブル上で自転しながら回転する超硬基体に−１０００Ｖの直流バイアス電圧を印加し、かつカソード電極の前記金属Ｔｉとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＴｉボンバート洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して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、かつそれぞれのカソード電極（前記Ａｌ最高含有点形成用Ｔｉ−Ａｌ−Ｔａ合金およびＡｌ最低含有点形成用Ｔｉ−Ａｌ−Ｔａ合金）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Ａｌ最高含有点とＡｌ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Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ含有量が連続的に変化する成分濃度分布構造を有し、かつ同じく表３，４に示される目標全体層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製スローアウエイチップ（以下、本発明被覆超硬チップと云う）１〜１６をそれぞれ製造した。
【００１６】
また、比較の目的で、これら超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６を、アセトン中で超音波洗浄し、乾燥した状態で、それぞれ図２に示される通常のアークイオンプレーティング装置に装入し、カソード電極（蒸発源）として種々の成分組成をもったＴｉ−Ａｌ−Ｔａ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−１０００Ｖの直流バイアス電圧を印加し、カソード電極の前記金属Ｔｉとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって超硬基体表面をＴｉボンバート洗浄し、ついで装置内に反応ガスとして窒素ガスを導入して２Ｐａの反応雰囲気とすると共に、前記超硬基体に印加するバイアス電圧を−１００Ｖに下げて、前記カソード電極とアノード電極との間にアーク放電を発生させ、もって前記超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６のそれぞれの表面に、表５，６に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ａｌ，Ｔａ）Ｎ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製スローアウエイチップ（以下、従来被覆超硬チップと云う）１〜１６をそれぞれ製造した。
【００１７】
つぎに、上記本発明被覆超硬チップ１〜１６および従来被覆超硬チップ１〜１６について、これを工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、
被削材：ＪＩＳ・ＳＣＭ４４０の丸棒、
切削速度：３００ｍ／ｍｉｎ．、
切り込み：４ｍｍ、
送り：０．３０ｍｍ／ｒｅｖ．、
切削時間：１０分、
の条件での合金鋼の乾式連続高速高切り込み切削加工試験、
被削材：ＪＩＳ・ＳＮＣＭ４３９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：０．６０ｍｍ／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・Ｓ４５Ｃの丸棒、
切削速度：３２０ｍ／ｍｉｎ．、
切り込み：３．５ｍｍ、
送り：０．４０ｍｍ／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７に示した。
【００１８】
【表１】

【００１９】
【表２】

【００２０】
【表３】

【００２１】
【表４】

【００２２】
【表５】

【００２３】
【表６】

【００２４】
【表７】

【００２５】
（実施例２）
原料粉末として、平均粒径：５．５μｍを有する中粗粒ＷＣ粉末、同０．８μｍの微粒ＷＣ粉末、同１．３μｍのＴａＣ粉末、同１．２μｍのＮｂＣ粉末、同１．２μｍのＺｒＣ粉末、同２．３μｍのＣｒ_３Ｃ_２粉末、同１．５μｍのＶＣ粉末、同１．０μｍの（Ｔｉ，Ｗ）Ｃ粉末、および同１．８μｍのＣｏ粉末を用意し、これら原料粉末をそれぞれ表８に示される配合組成に配合し、さらにワックスを加えてアセトン中で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８に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法を有し、かついずれもねじれ角：３０度の４枚刃スクエア形状をもった超硬基体（エンドミル）Ｃ−１〜Ｃ−８をそれぞれ製造した。
【００２６】
ついで、これらの超硬基体（エンドミル）Ｃ−１〜Ｃ−８を、アセトン中で超音波洗浄し、乾燥した状態で、同じく図１に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、層厚方向に沿って表９に示される目標組成のＡｌ最高含有点とＡｌ最低含有点とが交互に同じく表９に示される目標間隔で繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ含有量が連続的に変化する成分濃度分布構造を有し、かつ同じく表９に示される目標全体層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製エンドミル（以下、本発明被覆超硬エンドミルと云う）１〜８をそれぞれ製造した。
【００２７】
また、比較の目的で、上記の超硬基体（エンドミル）Ｃ−１〜Ｃ−８を、アセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示される通常のアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、表１０に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のない（Ｔｉ，Ａｌ，Ｔａ）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・Ｓ５５Ｃの板材、
切削速度：１８０ｍ／ｍｉｎ．、
溝深さ（切り込み）：３．５ｍｍ、
テーブル送り：４５０ｍｍ／分、
の条件での炭素鋼の乾式高速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・ＦＣ２５０の板材、
切削速度：１５０ｍ／ｍｉｎ．、
溝深さ（切り込み）：５．５ｍｍ、
テーブル送り：　４００ｍｍ／分、
の条件での鋳鉄の乾式高速高切り込み溝切削加工試験、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・ＳＣＭ４４０の板材、
切削速度：１５０ｍ／ｍｉｎ．、
溝深さ（切り込み）：７．５ｍｍ、
テーブル送り：３５０ｍｍ／分、
の条件での合金鋼の乾式高速高送り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９、１０にそれぞれ示した。
【００２９】
【表８】

【００３０】
【表９】

【００３１】
【表１０】

【００３２】
（実施例３）
上記の実施例２で製造した直径が８ｍｍ（超硬基体Ｃ−１〜Ｃ−３形成用）、１３ｍｍ（超硬基体Ｃ−４〜Ｃ−６形成用）、および２６ｍｍ（超硬基体Ｃ−７、Ｃ−８形成用）の３種の丸棒焼結体を用い、この３種の丸棒焼結体から、研削加工にて、溝形成部の直径×長さがそれぞれ４ｍｍ×１３ｍｍ（超硬基体Ｄ−１〜Ｄ−３）、８ｍｍ×２２ｍｍ（超硬基体Ｄ−４〜Ｄ−６）、および１６ｍｍ×４５ｍｍ（超硬基体Ｄ−７、Ｄ−８）の寸法を有し、かついずれもねじれ角：３０度の２枚刃形状をもった超硬基体（ドリル）Ｄ−１〜Ｄ−８をそれぞれ製造した。
【００３３】
ついで、これらの超硬基体（ドリル）Ｄ−１〜Ｄ−８の切刃に、ホーニングを施し、アセトン中で超音波洗浄し、乾燥した状態で、同じく図１に示されるアークイオンプレーティング装置に装入し、上記実施例１と同一の条件で、層厚方向に沿って表１１に示される目標組成のＡｌ最高含有点とＡｌ最低含有点とが交互に同じく表１１に示される目標間隔で繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ含有量が連続的に変化する成分濃度分布構造を有し、かつ同じく表１１に示される目標全体層厚の硬質被覆層を蒸着することにより、本発明被覆超硬工具としての本発明表面被覆超硬合金製ドリル（以下、本発明被覆超硬ドリルと云う）１〜８をそれぞれ製造した。
【００３４】
また、比較の目的で、上記の超硬基体（ドリル）Ｄ−１〜Ｄ−８の切刃に、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１２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，Ａｌ，Ｔａ）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・ＳＳ４００の板材、
切削速度：１５０ｍ／ｍｉｎ．、
送り：０．３０ｍｍ／ｒｅｖ、
穴深さ：８ｍｍ
の条件での構造用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・Ｓ５０Ｃの板材、
切削速度：１８０ｍ／ｍｉｎ．、
送り：０．３５ｍｍ／ｒｅｖ、
穴深さ：１６ｍｍ
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・ＳＣＭ４４０の板材、
切削速度：１２０ｍ／ｍｉｎ．、
送り：０．４０ｍｍ／ｒｅｖ、
穴深さ：３２ｍｍ
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１１、１２にそれぞれ示した。
【００３６】
【表１１】

【００３７】
【表１２】

【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の硬質被覆層について、厚さ方向に沿ってオージェ分光分析装置を用いてＴｉ、Ａｌ、およびＴａの含有量を測定した。これらの測定結果から、上記の本発明被覆超硬工具の硬質被覆層では、厚さ方向に沿って目標組成と実質的に同じ組成を有するＡｌ最高含有点とＡｌ最低含有点とが目標間隔と実質的に同じ間隔で交互に存在し、かつ硬質被覆層の全体平均層厚も目標全体層厚と実質的に同じ値を示し、さらに前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ含有量が連続的に変化する成分濃度分布構造をもつことも確認された。一方上記の従来被覆超硬工具の硬質被覆層においては、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全体層厚と実質的に同じ全体平均層厚を示すことが確認された。
【００３９】
【発明の効果】
表３〜１２に示される結果から、硬質被覆層が層厚方向に、一段と高い強度を有するＡｌ最低含有点と相対的にすぐれた高温硬さと耐熱性を有するＡｌ最高含有点とが交互に所定間隔をおいて繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ａｌ最低含有点、前記Ａｌ最低含有点から前記Ａｌ最高含有点へＡｌ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、高速で、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，Ａｌ，Ｔａ）Ｎ層からなる従来被覆超硬工具においては、前記硬質被覆層が高温硬さと耐熱性を有するものの、強度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、高速で、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、すぐれた耐チッピング性を発揮し、長期に亘ってすぐれた耐摩耗性を示すものであるから、切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。
【図面の簡単な説明】
【図１】この発明の被覆超硬工具を構成する硬質被覆層を形成するのに用いたアークイオンプレーティング装置を示し、（ａ）は概略平面図、（ｂ）は概略正面図である。
【図２】従来被覆超硬工具を構成する硬質被覆層を形成するのに用いた通常のアークイオンプレーティング装置の概略説明図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a high-strength hard coating layer and excellent high-temperature hardness and heat resistance. Therefore, high-speed cutting of various types of steel and cast iron can be performed particularly at high cutting and high feed rates with high mechanical impact. The present invention also relates to a cutting tool made of a surface-coated cemented carbide (hereinafter referred to as a coated cemented carbide tool) in which a hard coating layer exhibits excellent chipping resistance even when the cutting is performed under heavy cutting conditions.
[0002]
[Prior art]
In general, coated carbide tools are used for throw-away inserts, drilling, etc., which are removably attached to the tip of a cutting tool for turning or planing of various materials such as steel and cast iron. There are solid type end mills used for drilling and miniature drills, as well as for face milling, grooving, shoulder processing, etc., and the cutting is performed in the same manner as the solid type end mill by detachably attaching the throw-away tip. A throw-away end mill tool and the like are known.
[0003]
Further, as a coated cemented carbide tool, a substrate made of tungsten carbide (hereinafter, referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter, referred to as TiCN) -based cermet (hereinafter, these are collectively referred to as a cemented carbide substrate) surface, composition _{_{formula): (Ti 1- (X +}} Z) Al X Ta Z) N ( provided that an atomic ratio, X is 0.45 to 0.60, Ta: shows the 0.05-0.20) Coated hard tool obtained by physical vapor deposition of a hard coating layer composed of a composite nitride of Ti, Al and Ta [hereinafter, referred to as (Ti, Al, Ta) N] with an average layer thickness of 1 to 15 μm. And that the (Ti, Al, Ta) N layer constituting the hard coating layer has high-temperature hardness and heat resistance due to Al, strength due to Ti, and further has a higher temperature hardness due to Ta. Together, such coated carbide tools can be used in various types of steel and cast iron. It is also known to exhibit what continuous cutting and cutting performance of intermittent cutting with superior case of performing high-speed cutting conditions.
[0004]
Furthermore, the above-mentioned coated carbide tool is charged with the above-mentioned carbide substrate in an arc ion plating apparatus, which is a kind of physical vapor deposition apparatus shown schematically in FIG. 2, for example, and the inside of the apparatus is heated by a heater. For example, an arc discharge is generated between an anode electrode and a cathode electrode (evaporation source) on which a Ti-Al-Ta alloy having a predetermined composition is set, for example, at a current of 90 A while being heated to a temperature of 500 ° C. At the same time, a nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of, for example, 2 Pa. On the other hand, the surface of the cemented carbide substrate is applied to the cemented carbide substrate under the condition that a bias voltage of, for example, -100 V is applied. In addition, it is also known that it is manufactured by depositing a hard coating layer composed of the (Ti, Al, Ta) N layer.
[0005]
[Problems to be solved by the invention]
In recent years, the performance of cutting equipment has been remarkably improved, but on the other hand, there has been a strong demand for labor-saving and energy-saving cutting, as well as low cost. There is a tendency for cutting under heavy cutting conditions such as high feed, but in the above-mentioned conventional coated carbide tools, there is no problem if this is used under high-speed cutting conditions, but high mechanical When heavy cutting such as high cutting and high feed with impact is performed at high speed, chipping (small cracks) tends to occur especially due to insufficient strength of the hard coating layer, and the service life is shortened in a relatively short time is the current situation.
[0006]
[Means for Solving the Problems]
In view of the above, the present inventors have developed the above-described conventional coated carbide tool in order to develop a coated carbide tool in which the hard coating layer exhibits excellent chipping resistance especially in high-speed heavy cutting. As a result of conducting research, focusing on the constituent hard coating layer,
(A) The (Ti, Al, Ta) N layer constituting the conventional coated carbide tool formed by using the arc ion plating apparatus shown in FIG. 2 is substantially uniform over the entire layer thickness. And has a uniform high-temperature hardness, heat resistance, and strength. For example, arc ion plating having a structure shown in a schematic plan view in FIG. 1A and a schematic front view in FIG. An apparatus, that is, a rotary table for mounting a carbide substrate is provided at the center of the apparatus, and a Ti-Al-Ta alloy for forming the highest Al content point is provided on one side and a Ti for forming the lowest Al content point is provided on the other side with the rotary table interposed therebetween. Using an arc ion plating apparatus in which all of the Al-Ta alloys are arranged as a cathode electrode (evaporation source) and facing each other at a predetermined radial distance from the center axis on the rotary table of the apparatus. A plurality of carbide substrates are mounted in a ring shape along the outer periphery of the tool, and in this state, the rotating table is rotated with the atmosphere in the apparatus being a nitrogen atmosphere, and the thickness of the hard coating layer formed by vapor deposition is made uniform. For the purpose, an arc discharge is generated between the cathode electrode (evaporation source) and the anode electrode on both sides while rotating the cemented carbide substrate itself, and (Ti, Al, Ta) is formed on the surface of the cemented carbide substrate. When the N layer is formed, in the resulting (Ti, Al, Ta) N layer, the cemented carbide substrate arranged in a ring shape on the turntable is the above-described one side Ti—Al—Ta alloy cathode electrode. The highest Al content point is formed in the layer at the point of closest approach to the (evaporation source), and at the point of time when the cemented carbide substrate is closest to the cathode electrode of the Ti-Al-Ta alloy on the other side. Al minimum content point is formed The rotation of the turntable causes the Al maximum content point and the Al minimum content point to alternately and repeatedly appear at predetermined intervals in the layer along the layer thickness direction, and the Al maximum content point to the Al minimum content point, A component concentration distribution structure in which the Al content continuously changes from the lowest Al content point to the highest Al content point.
[0007]
(B) In the (Ti, Al, Ta) N layer having the repeated and continuously changing component concentration distribution structure of (a), Al and Ti in the Ti—Al—Ta alloy which is the cathode electrode (evaporation source) on one side of the opposed arrangement are provided. The Ta content is equivalent to the Al and Ta contents of the above-mentioned conventional Ti—Al—Ta alloy for forming a (Ti, Al, Ta) N layer, and the Ti—Al—Ta—electrode (evaporation source) on the other side is used. The Al content in the Al-Ta alloy is made relatively lower than the Al content in the above-mentioned conventional Ti-Al-Ta alloy, and the rotation speed of the turntable on which the carbide substrate is mounted is controlled. do it,
The Al highest content point, composition _{_{formula: (Ti 1- (X + Z}} ) Al X Ta Z) N ( provided that an atomic ratio, X is 0.45 to 0.60, Z: a 0.05-0.20 Show),
The Al minimum content point, composition _{_{formula: (Ti 1- (X + Z}} ) Al X Ta Z) N ( provided that an atomic ratio, X is 0.10 to 0.25, Z: a 0.05-0.20 Show),
And the distance between the adjacent Al maximum content point and Al minimum content point in the thickness direction is 0.01 to 0.1 μm,
The above-mentioned Al maximum content portion shows high-temperature hardness and heat resistance corresponding to the high-temperature hardness and heat resistance of the conventional (Ti, Al, Ta) N layer, while the above-mentioned Al minimum content portion shows the above-mentioned Al maximum content. Since the Al content is lower than the content point portion and the Ti content is relatively high, higher strength is secured, and the interval between the Al highest content point and the Al lowest content point is extremely small. As a result, the layer as a whole has higher strength while maintaining high-temperature hardness and heat resistance as a characteristic, and therefore, the hard coating layer is composed of the (Ti, Al, Ta) N layer having such a configuration. Carbide tools have excellent hard coating layer, especially when cutting various kinds of steel and cast iron at high speed and under heavy cutting conditions such as high cutting and high feed with high mechanical impact. Chipping resistant To become able to exert sex.
The research results shown in (a) and (b) above were obtained.
[0008]
The present invention has been made based on the above research results, and a hard coating layer composed of a (Ti, Al, Ta) N layer is physically formed on the surface of a super hard substrate with a total average layer thickness of 1 to 15 μm. In coated carbide tools made by evaporation,
The hard coating layer has an Al maximum content point and an Al minimum content point alternately and repeatedly provided at predetermined intervals along the layer thickness direction, and the Al maximum content point and the Al minimum content point, the Al Having a component concentration distribution structure in which the Al content continuously changes from the lowest content point to the highest Al content point,
Furthermore, the Al highest content point, composition _{_{formula: (Ti 1- (X + Z}} ) Al X Ta Z) N ( provided that an atomic ratio, X is 0.45 to 0.60, Z: from 0.05 to 0. 20), and the above-mentioned Al minimum content point is determined by a composition formula: (Ti _{1- (X + Z)} Al _X Ta _Z ) N (however, in atomic ratio, X is 0.10 to 0.25, Z: 0.05 ~ 0.20),
And the interval between the adjacent Al maximum content points and the Al minimum content points is 0.01 to 0.1 μm,
It is characterized by a coated carbide tool in which a hard coating layer exhibits excellent chipping resistance under high-speed heavy cutting conditions.
[0009]
Next, the reason why the configuration of the hard coating layer constituting the coated carbide tool of the present invention is limited as described above will be described.
(A) Composition of the highest Al content point The Ti component in (Ti, Al, Ta) N having the highest Al content improves the strength, and the Al component improves the high-temperature hardness and heat resistance. It has the effect of further improving the high-temperature hardness, and therefore, the higher the content ratio of the Al and Ta components, the higher the high-temperature hardness and heat resistance, and it is suitable for high-speed cutting with high heat generation. Even if the X value indicating the content ratio exceeds 0.60 in the ratio (atomic ratio) to the total amount of Ti and Ta, and the Z value indicating the Ta content ratio exceeds 0.20, high strength is obtained. , The strength of the layer itself is inevitably reduced, and as a result, chipping and the like are liable to occur. On the other hand, even when the X value is less than 0.45 or the Z value High temperature hardness and resistance even when the value is less than 0.05 Since not obtained the desired effect of improving sexual, the X value from 0.45 to 0.60, was defined as the Z value 0.05-0.20.
[0010]
(B) Composition of Al minimum content point As described above, the Al maximum content point has relatively excellent high-temperature hardness and heat resistance, but the strength is relatively insufficient. In order to compensate for the insufficient strength, the Al content is high, while the Al content is low, so that the Al minimum content point which has a high strength is alternately interposed in the thickness direction. When the X value indicating the ratio (atomic ratio) to the total amount of the Ti and Ta components exceeds 0.25, a desired excellent strength cannot be secured, and as a result, chipping is likely to occur, On the other hand, when the X value is less than 0.10, a predetermined high-temperature hardness and heat resistance cannot be secured at the Al minimum content point, which causes acceleration of wear. Set the X value indicating the ratio to 0. It was defined as 0 to 0.25.
The Ta component at the Al minimum content point is also contained for the purpose of improving high-temperature hardness in coexistence with the Al component as described above and adapting to high-speed cutting accompanied by high heat generation, and therefore, the Z value is less than 0.05. Does not provide the desired effect of increasing the high-temperature hardness, whereas if the Z value exceeds 0.20, the strength at the lowest Al content tends to decrease, causing chipping. Was determined to be 0.05 to 0.20.
[0011]
(C) The distance between the highest Al content point and the lowest Al content point If the distance is less than 0.01 μm, it is difficult to clearly form each point with the above composition, and as a result, the desired high temperature for the layer is obtained. Hardness and heat resistance, further high strength can not be ensured, and if the interval exceeds 0.1 μm, each point has a defect, that is, if the Al highest content point, the strength is insufficient, the Al lowest content point. If present, insufficient high-temperature hardness and heat resistance locally appear in the layer, which may cause chipping or accelerate the progress of wear. It was determined to be 1 μm.
[0012]
(D) Overall average layer thickness of the hard coating layer If the layer thickness is less than 1 μm, the desired wear resistance cannot be secured, while if the average layer thickness exceeds 15 μm, chipping is likely to occur. Therefore, the average layer thickness was determined to be 1 to 15 μm.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the coated cemented carbide tool of the present invention will be specifically described with reference to examples.
(Example 1)
As raw material powders, WC powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder each having an average particle diameter of 1 to 3 μm were prepared. The mixture was wet-mixed for 72 hours in a ball mill, dried and pressed into a green compact at a pressure of 100 MPa, and the green compact was heated to 1400 ° C. for 1 hour in a vacuum of 6 Pa. Sintering is performed under the conditions of holding, and after sintering, the cutting edge portion is subjected to honing processing of R: 0.03, and a carbide substrate A1 to A10 made of a WC-based cemented carbide having a chip shape of ISO standard CNMG120408. Was formed.
[0014]
Further, as raw material powder, TiCN (TiC / TiN = 50/50 by weight) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder each having an average particle diameter of 0.5 to 2 μm , Co powder, and Ni powder were prepared, and these raw material powders were blended in the composition shown in Table 2, wet-mixed in a ball mill for 24 hours, dried, and then pressed into a green compact at a pressure of 100 MPa. The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to obtain an ISO standard CNMG120408. Carbide bases B1 to B6 made of TiCN-based cermet having the chip shape described above were formed.
[0015]
Next, each of the above-mentioned super-hard substrates A1 to A10 and B1 to B6 was ultrasonically cleaned in acetone and dried, and then, from the center axis on the rotary table in the arc ion plating apparatus shown in FIG. Attached along the outer periphery of the table at a position separated by a predetermined distance in the radial direction, and as one cathode electrode (evaporation source), a Ti-Al-Ta alloy for forming the highest Al content point having various component compositions, As a cathode electrode (evaporation source) on the side, a Ti-Al-Ta alloy for forming the lowest content point of Al is disposed opposite to the rotating table, and a metal Ti for bombarding is also mounted. While maintaining the vacuum at 0.5 Pa or less, the inside of the apparatus is heated to 500 ° C. by a heater, and then a −1000 V DC via is applied to the super-hard substrate rotating while rotating on the rotary table. A voltage is applied, and an electric current of 100 A is caused to flow between the metal Ti of the cathode electrode and the anode electrode to generate an arc discharge. Thus, the surface of the cemented carbide substrate is cleaned by Ti bombardment. A gas was introduced to form a reaction atmosphere of 2 Pa, and a DC bias voltage of -100 V was applied to the super-hard substrate rotating while rotating on the rotary table, and each cathode electrode (for forming the Al highest content point). A current of 100 A is applied between the Ti-Al-Ta alloy and the Ti-Al-Ta alloy for forming the lowest Al content point) and the anode electrode to generate an arc discharge. Along the direction, the highest Al content points and lowest Al content points of the target compositions shown in Tables 3 and 4 are alternately present at the same target intervals shown in Tables 3 and 4. And having a component concentration distribution structure in which the Al content continuously changes from the Al maximum content point to the Al minimum content point, from the Al minimum content point to the Al maximum content point, and also shown in Tables 3 and 4. By depositing a hard coating layer having a target overall layer thickness to be obtained, the throw-away tips made of the surface-coated cemented carbide of the present invention (hereinafter referred to as the coated cemented carbide tips of the present invention) 1 to 16 as the coated carbide tools of the present invention. Each was manufactured.
[0016]
For the purpose of comparison, these super-hard substrates A1 to A10 and B1 to B6 were ultrasonically cleaned in acetone, dried, and charged into a usual arc ion plating apparatus shown in FIG. A Ti—Al—Ta alloy having various component compositions is mounted as a cathode electrode (evaporation source), and a metal Ti for bombarding is also mounted. First, the inside of the apparatus is evacuated to a vacuum of 0.5 Pa or less. After the inside of the apparatus was heated to 500 ° C. with a heater while holding, a DC bias voltage of −1000 V was applied to the superhard substrate, and a current of 100 A was passed between the metal Ti of the cathode electrode and the anode electrode. An arc discharge is generated, and the surface of the cemented carbide substrate is cleaned by Ti bombardment. Then, nitrogen gas is introduced into the apparatus as a reaction gas to make a reaction atmosphere of 2 Pa, and By lowering the bias voltage applied to the body to -100 V, an arc discharge is generated between the cathode electrode and the anode electrode, and thus, the surface of each of the cemented carbide substrates A1 to A10 and B1 to B6 is set in Table 5, 6 has a target composition and a target layer thickness shown in FIG. 6, and a hard coating layer composed of a (Ti, Al, Ta) N layer having substantially no composition change along the layer thickness direction. Conventional surface coated cemented carbide throwaway tips (hereinafter referred to as conventionally coated cemented carbide tips) 1 to 16 as cemented carbide tools were manufactured, respectively.
[0017]
Next, with respect to the above-mentioned coated carbide tips 1 to 16 of the present invention and conventional coated carbide tips 1 to 16, in a state where they were screwed to the tip of a tool steel tool with a fixing jig,
Work material: JIS SCM440 round bar,
Cutting speed: 300 m / min. ,
Cut: 4mm,
Feed: 0.30 mm / rev. ,
Cutting time: 10 minutes,
Dry continuous high-speed high-cut cutting test of alloy steel under the conditions
Work material: JIS SNCM439 Lengthwise equally spaced round bar with four longitudinal grooves,
Cutting speed: 250 m / min. ,
Cut: 2mm,
Feed: 0.60 mm / rev. ,
Cutting time: 5 minutes,
Intermittent high-speed high-feed cutting test of alloy steel under the conditions of
Work material: JIS S45C round bar,
Cutting speed: 320 m / min. ,
Cut: 3.5 mm,
Feed: 0.40 mm / rev. ,
Cutting time: 10 minutes,
A dry continuous high-speed high-cut cutting test of carbon steel was performed under the following conditions, and the flank wear width of the cutting edge was measured in each cutting test. Table 7 shows the measurement results.
[0018]
[Table 1]

[0019]
[Table 2]

[0020]
[Table 3]

[0021]
[Table 4]

[0022]
[Table 5]

[0023]
[Table 6]

[0024]
[Table 7]

[0025]
(Example 2)
As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, and ZrC of 1.2 μm Powder, 2.3 μm Cr ₃ C ₂ powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C powder, and 1.8 μm Co powder were prepared. Each was blended into the blending composition shown in Table 8, further added wax, mixed in a ball mill for 24 hours in acetone, dried under reduced pressure, and then pressed into various compacts of a predetermined shape at a pressure of 100 MPa. The green compact is heated in a vacuum atmosphere of 6 Pa at a heating rate of 7 ° C./min to a predetermined temperature in the range of 1370 to 1470 ° C., and is kept at this temperature for 1 hour, and then fired under furnace cooling conditions. In combination, diameters of 8 mm, 13 mm, and 2 mm mm, three types of round bar sintered bodies for forming a cemented carbide substrate are formed, and the above three types of round bar sintered bodies are subjected to grinding processing in a combination shown in Table 8 to obtain a diameter of a cutting edge portion. × Carbide substrate (end mill) C-1 having dimensions of 6 mm × 13 mm, 10 mm × 22 mm, and 20 mm × 45 mm, respectively, and having a four-flute square shape with a twist angle of 30 °. C-8 were each produced.
[0026]
Then, these super-hard substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone, dried, and charged into an arc ion plating apparatus also shown in FIG. Under the same conditions as in Example 1, the Al maximum content points and the Al minimum content points of the target compositions shown in Table 9 are alternately and repeatedly present at the target intervals shown in Table 9 along the layer thickness direction, and A target overall layer having a component concentration distribution structure in which the Al content continuously changes from the highest Al content point to the lowest Al content point, and the lowest Al content point to the highest Al content point; and also shown in Table 9 By depositing a thick hard coating layer, end mills 1-8 of the surface coated cemented carbide of the present invention (hereinafter referred to as coated carbide end mills of the present invention) as coated carbide tools of the present invention were manufactured.
[0027]
For the purpose of comparison, the above-mentioned ultra-hard substrates (end mills) C-1 to C-8 were ultrasonically cleaned in acetone and dried, and then a normal arc ion plating apparatus also shown in FIG. Under the same conditions as in Example 1 above, having the target composition and target layer thickness shown in Table 10, and having substantially no composition change along the layer thickness direction (Ti, Al, Ta). 3) End mills made of conventional surface-coated cemented carbide (hereinafter referred to as conventional coated carbide end mills) 1 to 8 as conventional coated cemented carbide tools were produced by depositing a hard coating layer composed of an N layer.
[0028]
Next, among the coated carbide end mills 1 to 8 of the present invention and the conventional coated carbide end mills 1 to 8, of the coated carbide end mills 1 to 3 and the coated carbide end mills 1 to 3 of the present invention,
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm, JIS S55C plate,
Cutting speed: 180 m / min. ,
Groove depth (cut): 3.5 mm,
Table feed: 450 mm / min,
Regarding the dry high-speed high-cut groove cutting test of carbon steel under the conditions described above, the coated carbide end mills 4 to 6 of the present invention and the conventionally coated carbide end mills 4 to 6,
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS FC250 plate,
Cutting speed: 150 m / min. ,
Groove depth (cut): 5.5 mm,
Table feed: 400 mm / min,
For the dry high-speed high-cut groove cutting test of cast iron under the following conditions, coated carbide end mills 7 and 8 of the present invention and conventional coated carbide end mills 7 and 8,
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS SCM440 plate,
Cutting speed: 150 m / min. ,
Groove depth (cut): 7.5 mm,
Table feed: 350 mm / 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 standard for the service life, in each dry cutting high speed high feed groove cutting test of alloy steel under the conditions of The cutting groove length up to was measured. The measurement results are shown in Tables 9 and 10, respectively.
[0029]
[Table 8]

[0030]
[Table 9]

[0031]
[Table 10]

[0032]
(Example 3)
The diameters produced in Example 2 were 8 mm (for forming the super-hard substrates C-1 to C-3), 13 mm (for forming the super-hard substrates C-4 to C-6), and 26 mm (for the super-hard substrates C-). 7, for forming C-8), the diameter x length of the groove forming portion was 4 mm x 13 mm (by grinding) from the three types of round rod sintered bodies by grinding. Carbide substrates D-1 to D-3), 8 mm x 22 mm (carbide substrates D-4 to D-6), and 16 mm x 45 mm (carbide substrates D-7, D-8), Carbide substrates (drills) D-1 to D-8 each having a two-blade shape with a twist angle of 30 degrees were manufactured.
[0033]
Next, the cutting blades of the super hard substrates (drills) D-1 to D-8 are honed, ultrasonically cleaned in acetone, and dried, and then the arc ion plating apparatus shown in FIG. Under the same conditions as in Example 1 described above, and the Al maximum content points and the Al minimum content points of the target compositions shown in Table 11 are alternately arranged along the layer thickness direction in the same manner as in Example 11. And a component concentration distribution structure in which the Al content continuously changes from the Al highest content point to the Al lowest content point, from the Al lowest content point to the Al highest content point, and By depositing a hard coating layer having a target total layer thickness shown in 11, a drill made of the surface-coated cemented carbide of the present invention as the coated carbide tool of the present invention (hereinafter referred to as the coated carbide drill of the present invention) 1 to 8 Was manufactured respectively.
[0034]
Also, for comparison purposes, the cutting edges of the above-mentioned carbide substrates (drills) D-1 to D-8 are honed, ultrasonically cleaned in acetone, and dried, and are also shown in FIG. It was charged in a normal arc ion plating apparatus, and had the target composition and the target layer thickness shown in Table 12 under the same conditions as in Example 1 above, and the composition change substantially along the layer thickness direction. By depositing a hard coating layer composed of a non-coated (Ti, Al, Ta) N layer, a drill made of a conventional surface-coated cemented carbide as a conventional coated carbide tool (hereinafter referred to as a conventional coated carbide drill) 1-8 Was manufactured respectively.
[0035]
Next, of the coated carbide drills 1 to 8 of the present invention and the coated carbide drills 1 to 8 of the related art, the coated carbide drills 1 to 3 of the present invention and the covered carbide drills 1 to 3 of the present invention are:
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm, JIS SS400 plate,
Cutting speed: 150 m / min. ,
Feed: 0.30 mm / rev,
Hole depth: 8mm
For the wet-type high-speed and high-feed drilling cutting test of structural steel under the conditions described above, the coated carbide drills 4 to 6 of the present invention and the conventionally coated carbide drills 4 to 6,
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS S50C plate,
Cutting speed: 180 m / min. ,
Feed: 0.35 mm / rev,
Hole depth: 16mm
For the wet-type high-speed and high-feed drilling cutting test of carbon steel under the conditions described below, the coated carbide drills 7 and 8 of the present invention and the conventionally coated
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS SCM440 plate,
Cutting speed: 120 m / min. ,
Feed: 0.40 mm / rev,
Hole depth: 32mm
Welding high-speed and high-feed drilling cutting tests of alloy steels under the conditions described above were performed, and in any of the wet-type high-speed drilling cutting tests (using water-soluble cutting oil), the flank wear width of the tip cutting edge surface was 0.3 mm. The number of drilling operations up to that point was measured. The measurement results are shown in Tables 11 and 12, respectively.
[0036]
[Table 11]

[0037]
[Table 12]

[0038]
The coated carbide tips 1-16, coated carbide end mills 1-8, coated drills 1-8, and coated carbide tools of the present invention as the coated carbide tools of the present invention obtained as a result. For the hard coating layers of the conventional coated carbide tips 1 to 16, the conventional coated carbide end mills 1 to 8, and the conventional coated carbide drills 1 to 8, Ti, along the thickness direction using an Auger spectrometer, The contents of Al and Ta were measured. From these measurement results, in the hard coating layer of the above-described coated carbide tool of the present invention, the Al maximum content point and the Al minimum content point having substantially the same composition as the target composition along the thickness direction are the target interval and The hard coating layers are present alternately at substantially the same intervals, and the overall average layer thickness of the hard coating layer also shows substantially the same value as the target overall layer thickness, and further, from the Al highest content point to the Al lowest content point and the Al lowest content. It was also confirmed that the composition had a component concentration distribution structure in which the Al content continuously changed from the content point to the Al maximum content point. On the other hand, in the hard coating layer of the conventional coated carbide tool, no change in composition is observed along the thickness direction, and the composition is substantially the same as the target composition and the overall average layer is substantially the same as the target total layer thickness. It was confirmed that the film showed a thickness.
[0039]
【The invention's effect】
From the results shown in Tables 3 to 12, the hard coating layer alternately determines, in the layer thickness direction, an Al lowest content point having higher strength and an Al highest content point having relatively excellent high-temperature hardness and heat resistance. The present invention has a component concentration distribution structure which is present repeatedly at intervals and in which the Al content continuously changes from the highest Al content point to the lowest Al content point and from the lowest Al content point to the highest Al content point. Coated carbide tools have a hard coating layer even when cutting various types of steel or cast iron at high speeds and under heavy cutting conditions such as high cutting and high feed with high mechanical impact. The conventional coated cemented carbide tool comprising a (Ti, Al, Ta) N layer in which the hard coating layer has substantially no composition change along the layer thickness direction, while exhibiting excellent chipping resistance. Hard coating layer has high temperature hardness Although a heat resistant, because it is inferior in strength, chipping occurs and this is apparent that lead to a relatively short time service life due.
As described above, the coated cemented carbide tool of the present invention can be used not only for cutting under normal conditions, but also for cutting various kinds of steel and cast iron, etc., at high speed, and with high cutting with high mechanical impact. Even when performed under heavy cutting conditions such as high feed and high cutting, it exhibits excellent chipping resistance and exhibits excellent wear resistance over a long period of time. It can sufficiently cope with cost reduction.
[Brief description of the drawings]
FIG. 1 shows an arc ion plating apparatus used for forming a hard coating layer constituting a coated carbide tool of the present invention, wherein (a) is a schematic plan view and (b) is a schematic front view.
FIG. 2 is a schematic explanatory view of a conventional arc ion plating apparatus used for forming a hard coating layer constituting a conventional coated carbide tool.

Claims

Surface coating formed by physical vapor deposition of a hard coating layer composed of a composite nitride layer of Ti, Al and Ta on the surface of a tungsten carbide-based cemented carbide substrate or a titanium carbonitride-based cermet substrate with a total average layer thickness of 1 to 15 μm In cemented carbide cutting tools,
The hard coating layer has an Al maximum content point and an Al minimum content point alternately and repeatedly provided at predetermined intervals along the layer thickness direction, and the Al maximum content point and the Al minimum content point, the Al Having a component concentration distribution structure in which the Al content continuously changes from the lowest content point to the highest Al content point,
Furthermore, the Al highest content point, composition _{_{formula: (Ti 1- (X + Z}} ) Al X Ta Z) N ( provided that an atomic ratio, X is 0.45 to 0.60, Z: from 0.05 to 0. 20), and the above-mentioned Al minimum content point is determined by a composition formula: (Ti _{1- (X + Z)} Al _X Ta _Z ) N (however, in atomic ratio, X is 0.10 to 0.25, Z: 0.05 ~ 0.20),
And the distance between the adjacent Al maximum content point and Al minimum content point is 0.01 to 0.1 μm,
Surface coated cemented carbide cutting tool with a hard coating layer that exhibits excellent chipping resistance under high-speed heavy cutting conditions.