JP4048364B2

JP4048364B2 - Surface coated cemented carbide cutting tool with excellent chipping resistance with hard coating layer under high speed heavy cutting conditions

Info

Publication number: JP4048364B2
Application number: JP2002220570A
Authority: JP
Inventors: 稔晃植田; 拓也早樋; 高歳大鹿
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2002-07-30
Filing date: 2002-07-30
Publication date: 2008-02-20
Anticipated expiration: 2022-07-30
Also published as: JP2004058217A

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、ＡｌとＴｉの相互含有割合を示すＡｌ／（Ａｌ＋Ｔｉ）が原子比で０．７４〜０．９８を満足するＡｌとＴｉの複合酸化物［以下、Ａｌ−Ｔｉ酸化物で示す］層からなる硬質被覆層を５〜２０μｍの平均層厚で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Ａｌ−Ｔｉ酸化物層が、Ａｌによる高温硬さおよび耐熱性と、Ｔｉによる靭性を具備することから、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１に概略縦断面図で示される通り、中央部にステンレス鋼製の反応ガス吹き出し管が立設され、前記反応ガス吹き出し管には、図２（ａ）に概略斜視図で、同（ｂ）に概略平面図で例示されるステンレス製の超硬基体支持パレットが串刺し積層嵌着され、かつこれらがステンレス鋼製のカバーを介してヒーターで加熱される構造を有する化学蒸着装置を用い、超硬基体を前記超硬基体支持パレットの底面に形成された多数の反応ガス通過穴位置に図示される通りに載置した状態で前記化学蒸着装置に装入し、ヒーターで装置内を、例えば８５０〜１１００℃の範囲内の所定の温度に加熱した後、反応ガスとして、容量％で（以下、反応ガスの％は容量％を示す）、
ＡｌＣｌ₃：０．５〜１０％、
ＴｉＣｌ₄：０．５〜３０％、
ＣＯ₂：０．５〜１０％、
ＨＣｌ：０．１〜１０％、
Ｈ₂：残り、
からなる組成を有する反応ガスを用い、この反応ガスを予め真空排気された装置内に前記反応ガス吹き出し管を通して導入し、装置内の反応ガス圧力を、３〜３０ＫＰａの範囲内の所定の圧力に所定時間保持することによりＡｌとＴｉの相互含有割合を示すＡｌ／（Ａｌ＋Ｔｉ）が層厚方向に一定のＡｌ−Ｔｉ酸化物層からなる硬質被覆層を形成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、特に層厚方向に一定の組成を有するＡｌ−Ｔｉ酸化物層からなる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）上記の化学蒸着装置を用いて形成された従来被覆超硬工具を構成するＡｌ−Ｔｉ酸化物層からなる硬質被覆層は、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、上記の従来硬質被覆層を構成するＡｌ−Ｔｉ酸化物に代って、硬質被覆層をＡｌとＴｉの複合酸化物［以下、Ａｌ−Ｔｉ酸化物で示す］で構成すると共に、例えば図３に反応ガス組成自動制御システムが概略チャート図で示される通り、反応ガス組成および流量中央制御装置に、Ａｌ−Ｔｉ酸化物からなる硬質被覆層に層厚方向にそってＡｌ最高含有点とＴｉ最高含有点とを所定間隔をおいて交互に繰り返し形成させる目的で、前記Ａｌ最高含有点およびＴｉ最高含有点に対応した反応ガス組成、並びに前記両点間のＡｌおよびＴｉの連続変化に対応した反応ガス組成、さらに前記両点間の間隔を、過去の実績データに基づいてインプットし、この反応ガス組成および流量中央制御装置からの制御信号にしたがって、原料ガスボンベからのＨ₂ガス、ＣＯ₂ガス、およびＨＣｌガスの流量、ＡｌＣｌ₃およびＴｉＣｌ₄の流量をそれぞれの原料ガス流量自動制御装置にて制御した状態で、化学蒸着装置の反応ガス吹き出し管に導入すると、層厚方向にそって、Ａｌ最高含有点とＴｉ最高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Ｔｉ最高含有点、前記Ｔｉ最高含有点から前記Ａｌ最低含有点へＡｌおよびＴｉ含有量が連続的に変化する成分濃度分布構造をもつたＡｌ−Ｔｉ酸化物層からなる硬質被覆層が形成されるようになること。
【０００７】
（ｂ）上記（ａ）の繰り返し連続変化成分濃度分布構造のＡｌ−Ｔｉ酸化物層において、
上記Ａｌ最高含有点におけるＡｌとＴｉの相互含有割合を示すＡｌ／（Ａｌ＋Ｔｉ）が原子比で０．７０〜０．９５、
上記Ｔｉ最高含有点におけるＴｉとＡｌの相互含有割合を示すＴｉ／（Ｔｉ＋Ａｌ）が原子比で０．７０〜０．０．９５、
を満足し、かつ隣り合う上記Ａｌ最高含有点とＴｉ最高含有点の厚さ方向の間隔を０．０１〜０．２μmとすると、
上記Ａｌ最高含有点部分では、上記の従来Ａｌ−Ｔｉ酸化物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Ｔｉ最高含有点部分では、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Ｔｉ最高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Ａｌ−Ｔｉ酸化物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、化学蒸着装置を用い、反応ガス組成および流量中央制御装置からの制御信号にしたがって、個々の原料ガスを、流量を自動制御しながら反応ガス吹き出し管に導入して、Ａｌ−Ｔｉ酸化物層からなる硬質被覆層を５〜２５μｍの全体平均層厚で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Ｔｉ最高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Ｔｉ最高含有点、前記Ｔｉ最高含有点から前記Ａｌ最高含有点へＡｌおよびＴｉ含有量が連続的に変化する成分濃度分布構造を有し、
さらに、上記Ａｌ最高含有点におけるＡｌとＴｉの相互含有割合を示すＡｌ／（Ａｌ＋Ｔｉ）が原子比で０．７０〜０．９５、
上記Ｔｉ最高含有点におけるＴｉとＡｌの相互含有割合を示すＴｉ／（Ｔｉ＋Ａｌ）が原子比で０．７０〜０．０．９５、
を満足し、かつ隣り合う上記Ａｌ最高含有点とＴｉ最高含有点の間隔が、０．０１〜０．２μm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Ａｌ−Ｔｉ酸化物層における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る作用があり、したがってＡｌ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成分のＴｉ成分との相互含有割合を示すＡｌ／（Ａｌ＋Ｔｉ）が原子比で０．９５を越えると、高強度を有するＴｉ最高含有点が隣接して存在しても層自体の強度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、一方同値が０．７０未満になると高温硬さおよび耐熱性が急激に低下し、摩耗促進の原因となることから、Ａｌ成分のＴｉ成分との相互含有割合を示すＡｌ／（Ａｌ＋Ｔｉ）を原子比で０．７０〜０．９５と定めた。
【００１０】
（ｂ）Ｔｉ最高含有点の組成
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Ｔｉ最高含有点を厚さ方向に交互に介在させるものである。しかし、Ｔｉ成分のＡｌ成分との相互含有割合を示すＴｉ／（Ｔｉ＋Ａｌ）が原子比で０．９５を越えると、Ｔｉ最高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、これが摩耗促進の原因となり、一方同値が０．７０未満になると、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易くなることから、Ｔｉ成分のＡｌ成分との相互含有割合を示すＴｉ／（Ｔｉ＋Ａｌ）を原子比で０．７０〜０．９５と定めた。
【００１１】
（ｃ）Ａｌ最高含有点とＴｉ最高含有点間の間隔
その間隔が０．０１μm未満ではそれぞれの点を上記の組成で明確に形成することが困難であり、この結果層に所望のすぐれた高温硬さおよび耐熱性、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０．２μm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、Ｔｉ最高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０．０１〜０．２μmと定めた。
【００１２】
（ｄ）硬質被覆層の全体平均層厚
その層厚が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２５μｍ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５〜２５μｍ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。
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。
【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、Ｍｏ₂Ｃ粉末、ＴｉＣ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】
つぎに、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、乾燥した後、図１に示される化学蒸着装置内に、第２図に示される超硬基体支持パレットの位置決め穴に載置した状態で装入し、まず、装置内をヒーターで９００℃に加熱したところで、ＴｉＣｌ₄：４．２％、Ｎ₂：３０％、Ｈ₂：残りからなる組成を有する反応ガスを反応ガス吹き出し管を通して導入して、装置内の反応雰囲気圧力を３０ｋＰａとし、この状態で３０分間保持して下地密着層として０．３μmの平均層厚をもった窒化チタン（ＴｉＮ）層を形成し、ついで、同じく装置内の雰囲気温度をヒーターにて加熱して１０２０℃とした後、図３に示される反応ガス組成自動制御システムの反応ガス組成および流量中央制御装置に過去の実績にデータにしたがって表３に示されるＡｌ最高含有点およびＴｉ最高含有点の目標Ａｌ／（Ａｌ＋Ｔｉ）および目標Ｔｉ／（Ｔｉ＋Ａｌ）と反応ガス組成の関係、前記Ａｌ最高含有点とＴｉ最高含有点間のＡｌとＴｉ含有量の連続変化に対応する反応ガス組成、さらに表４，６に示される前記両点間の目標間隔および硬質被覆層の目標全体層厚をインプットし、この反応ガス組成および流量中央制御装置からの信号にしたがって作動するコントロールバルブ内臓の原料ガス流量自動制御装置を通して、原料ガスであるＨ₂ガス、ＣＯ₂ガス、ＨＣｌガス、ＡｌＣｌ₃ガス、およびＴｉＣｌ₄ガス（この場合、ＡｌＣｌ₃ガスはＡｌＣｌ₃ガス発生器で金属ＡｌとＨＣｌガスを反応させることにより形成され、また、ＴｉＣｌ₄ガスは、図示の通り流量制御されたＨ₂ガスをキャリアガスとしてＴｉＣｌ₄ガス発生器に送り、ここで液体から気化されたＴｉＣｌ₄ガスと共に原料ガス流量自動制御装置に送られる）を、それぞれのガス流量を制御しながら、図１の化学蒸着装置の反応ガス吹き出し管から装置内に導入し（装置内の反応雰囲気圧力は常に１０ｋＰａに保持される）、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Ｔｉ最高含有点とが交互に同じく表３，４に示される目標間隔で繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ｔｉ最高含有点、前記Ｔｉ最高含有点から前記Ａｌ最高含有点へＡｌおよびＴｉ含有量がそれぞれ連続的に変化する成分濃度分布構造を有し、かつ同じく表３，４に示される目標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、乾燥した後、同じくそれぞれ図１，２に示される通常の化学蒸着装置に装入し、反応雰囲気温度を１０２０℃に加熱した後、それぞれ表６，７に示される従来硬質被覆層のもつ組成に相当する目標Ａｌ／（Ａｌ＋Ｚｒ）に対応した組成の反応ガスを反応ガス吹き出し管から導入し、反応雰囲気圧力を１０ｋＰａに一定とした条件で、前記超硬基体Ａ１〜Ａ１０およびＢ１〜Ｂ６のそれぞれの表面に、表６，７に示される目標組成および目標層厚を有し、かつ層厚方向に沿って実質的に組成変化のないＡｌ−Ｚｒ酸化物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：３５０ｍ／ｍｉｎ．、
切り込み：８ｍｍ、
送り：０．２ｍｍ／ｒｅｖ．、
切削時間：５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・ＦＣ３００の長さ方向等間隔４本縦溝入り丸棒、
切削速度：３５０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．６５ｍｍ／ｒｅｖ．、
切削時間：３分、
の条件での鋳鉄の乾式断続高速高送り切削加工試験、さらに、
被削材：ＪＩＳ・Ｓ４５Ｃの長さ方向等間隔４本縦溝入り丸棒、
切削速度：３５０ｍ／ｍｉｎ．、
切り込み：８ｍｍ、
送り：０．２ｍｍ／ｒｅｖ．、
切削時間：３分、
の条件での炭素鋼の乾式断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】
この結果得られた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を構成する硬質被覆層について、厚さ方向に沿ってＡｌおよびＴｉの含有量をオージェ分光分析装置を用いて測定し、この測定結果から各測定点におけるＡｌ／（Ａｌ＋Ｔｉ）値、さらにＴｉ／（Ｔｉ＋Ａｌ）値を算出したところ、本発明被覆超硬チップ１〜１６の硬質被覆層では、Ａｌ最高含有点と、Ｔｉ最高含有点とがそれぞれ目標値と実質的に同じ組成および間隔で交互に繰り返し存在し、かつＡｌ最高含有点からＴｉ最高含有点、前記Ｔｉ最高含有点からＡｌ最高含有点へＡｌとＴｉの含有量が連続的に変化する成分濃度分布構造を有することが確認され、また、硬質被覆層の全体平均層厚も目標全体層厚と実質的に同じ値を示した。一方前記従来被覆超硬チップ１〜１６の硬質被覆層では厚さ方向に沿って組成変化が見られず、かつ目標組成と実質的に同じ組成および目標全体層厚と実質的に同じ全体平均層厚を示した。
【００２６】
【発明の効果】
表３〜７に示される結果から、硬質被覆層が層厚方向に、相対的にすぐれた高温硬さと耐熱性を有するＡｌ最高含有点と相対的に高強度を有するＴｉ最高含有点とが交互に所定間隔をおいて繰り返し存在し、かつ前記Ａｌ最高含有点から前記Ｔｉ最高含有点、前記Ｔｉ最高含有点から前記Ａｌ最高含有点へＡｌおよびＴｉ含有量が連続的に変化する成分濃度分布構造を有する本発明被覆超硬チップ１〜１６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Ａｌ−Ｚｒ酸化物層からなる従来被覆超硬チップ１〜１６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】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化学蒸着装置を示す概略縦断面図である。
【図２】化学蒸着装置の構造部材である超硬基体支持パレットを示し、（ａ）が概略斜視図、（ｂ）が概略平面図である。
【図３】この発明の被覆超硬工具を構成する硬質被覆層の形成に用いられる反応ガス組成自動制御システムである。[0001]
BACKGROUND OF THE INVENTION
In the present invention, the hard coating layer has high strength and is excellent in high-temperature hardness and heat resistance, and therefore, high-speed cutting such as various steels and cast irons, especially high cutting with high mechanical impact, high feed, etc. The present invention also relates to a surface-coated cemented carbide cutting tool (hereinafter referred to as a coated cemented carbide tool) that exhibits excellent chipping resistance even when performed under heavy 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). ) Al / (Al + Ti) indicating the mutual content ratio of Al and Ti on the surface of Al / Ti composite oxide satisfying an atomic ratio of 0.74 to 0.98 [hereinafter referred to as Al-Ti oxide. A coated carbide tool formed by vapor-depositing a hard coating layer composed of a layer with an average layer thickness of 5 to 20 μm is proposed, and the Al—Ti oxide layer constituting the hard coating layer has high-temperature hardness and heat resistance due to Al. It is also known that this coated carbide tool exhibits excellent cutting performance when performing continuous cutting and intermittent cutting of various steels and cast irons under high-speed cutting conditions. It has been.
[0004]
Furthermore, as shown in the schematic longitudinal sectional view of FIG. 1, for example, the coated carbide tool has a stainless steel reaction gas blowing pipe standing at the center thereof. A stainless steel substrate support pallet illustrated in a schematic perspective view in (a) and a schematic plan view in (b) is skewered and laminated, and these are heated by a heater through a stainless steel cover. A chemical vapor deposition apparatus having a structure is used, and the cemented carbide substrate is mounted on the chemical vapor deposition apparatus in a state where the carbide substrate is placed as illustrated in a number of reaction gas passage hole positions formed on the bottom surface of the carbide substrate support pallet. And after heating the inside of the apparatus with a heater to a predetermined temperature within a range of 850 to 1100 ° C., for example, as a reaction gas, in volume% (hereinafter,% of the reaction gas indicates volume%),
AlCl ₃ : 0.5 to 10%,
TiCl _4: 0.5~30%,
CO _2: 0.5~10%,
HCl: 0.1-10%
H ₂ : Remaining
The reaction gas is introduced into the apparatus that has been evacuated in advance through the reaction gas blowing pipe, and the reaction gas pressure in the apparatus is set to a predetermined pressure in the range of 3 to 30 KPa. It is also known that Al / (Al + Ti) showing the mutual content ratio of Al and Ti by holding for a predetermined time is produced by forming a hard coating layer composed of a constant Al-Ti oxide layer in the layer thickness direction. ing.
[0005]
[Problems to be solved by the invention]
In recent years, there has been a remarkable increase in the performance of cutting equipment, while there has been a strong demand for labor saving and energy saving and further cost reduction for cutting work. Although there is a tendency to be forced to cut under heavy cutting conditions such as high feed, there is no problem with the above-mentioned conventional coated carbide tools when used under high-speed cutting conditions. When heavy cutting such as high cutting with impact and high feed is performed at high speed, chipping (due to insufficient strength of the hard coating layer made of an Al-Ti oxide layer having a constant composition in the layer thickness direction) At present, microcracks are likely to occur and the service life is reached in a relatively short time.
[0006]
[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 hard coating layer composed of the Al-Ti oxide layer constituting the conventional coated carbide tool formed by using the chemical vapor deposition apparatus has a substantially uniform composition throughout the entire layer thickness. Therefore, it has uniform high temperature hardness and heat resistance, and further strength, but instead of the Al-Ti oxide constituting the conventional hard coating layer, the hard coating layer is made of a composite oxide of Al and Ti [hereinafter referred to as Al As shown in FIG. 3, for example, the reaction gas composition automatic control system is shown in a schematic chart diagram, and the reaction gas composition and flow rate central control unit is provided with a hard coating made of Al—Ti oxide. Reaction gas composition corresponding to the Al highest content point and Ti highest content point for the purpose of alternately and repeatedly forming the Al highest content point and the Ti highest content point at a predetermined interval along the layer thickness direction in the layer, and Both points The reaction gas composition corresponding to the continuous change of Al and Ti, and the interval between the two points are input based on the past actual data, and the raw material according to the control signal from the reaction gas composition and the flow rate central controller The H ₂ gas, CO ₂ gas, and HCl gas flow rates from the gas cylinders, and the flow rates of AlCl ₃ and TiCl ₄ are controlled by the respective raw material gas flow rate automatic control devices and introduced into the reaction gas blowing pipe of the chemical vapor deposition system. Then, along the layer thickness direction, the highest Al content point and the highest Ti content point are alternately present at predetermined intervals, and from the highest Al content point, the highest Ti content point, from the highest Ti content point A hard coating layer composed of an Al-Ti oxide layer having a component concentration distribution structure in which the Al and Ti contents continuously change to the Al minimum content point is formed. To become.
[0007]
(B) In the Al—Ti oxide layer having the repeated continuous change component concentration distribution structure of (a) above,
Al / (Al + Ti) indicating the mutual content ratio of Al and Ti at the Al highest content point is 0.70 to 0.95 in atomic ratio,
Ti / (Ti + Al) indicating the mutual content ratio of Ti and Al at the Ti highest content point is 0.70 to 0.0.95 in atomic ratio,
And the interval in the thickness direction of the adjacent Al highest content point and Ti highest content point adjacent to each other is 0.01 to 0.2 μm,
The Al highest content point portion shows high temperature hardness and heat resistance corresponding to the high temperature hardness and heat resistance of the conventional Al-Ti oxide layer, while the Ti highest content point portion has the Al highest content point portion. Since the Al content is lower than that of the Ti, and the Ti content is relatively high, a much higher strength is ensured, and the interval between the Al highest content point and the Ti highest content point is extremely small. The coated carbide tool composed of an Al-Ti oxide layer having such a structure that the hard coating layer is provided has excellent strength while maintaining high temperature hardness and heat resistance as characteristics of the entire layer. Even when cutting various types of steel and cast iron at high speeds and under heavy cutting conditions such as high cutting and high feed with high mechanical impact, the hard coating layer exhibits excellent chipping resistance. To become so.
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 uses a chemical vapor deposition device on the surface of a cemented carbide substrate, and in accordance with a reaction gas composition and a control signal from a flow rate central control device, In a coated cemented carbide tool in which a hard coating layer made of an Al-Ti oxide layer is vapor-deposited with an overall average layer thickness of 5 to 25 μm, while automatically controlling the flow rate ,
In the hard coating layer, the highest Al content point and the highest Ti content point are repeatedly present at predetermined intervals along the layer thickness direction, and the highest Ti content point, the highest Ti content point, and the highest Ti content point A component concentration distribution structure in which the Al and Ti contents continuously change from the highest content point to the Al highest content point,
Furthermore, Al / (Al + Ti) indicating the mutual content ratio of Al and Ti at the Al highest content point is 0.70 to 0.95 in atomic ratio,
Ti / (Ti + Al) indicating the mutual content ratio of Ti and Al at the Ti highest content point is 0.70 to 0.0.95 in atomic ratio,
And the interval between the adjacent Al highest content point and the Ti highest content point adjacent to each other is 0.01 to 0.2 μm.
This is characterized by a coated carbide tool that exhibits excellent chipping resistance under high-speed heavy cutting conditions.
[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 Al highest content point The Ti component in the Al-Ti oxide layer having the highest Al content point improves the strength, and the Al component has the effect of improving the high-temperature hardness and heat resistance. The higher the content ratio, the higher the high-temperature hardness and heat resistance, and it is suitable for high-speed cutting with high heat generation, but Al / (Al + Ti) indicating the mutual content ratio with the Ti component of the Al component is an atom. When the ratio exceeds 0.95, even if the highest Ti content point having high strength is present adjacently, a decrease in the strength of the layer itself is unavoidable, and as a result, chipping or the like tends to occur, while the equivalent value is 0. When it is less than .70, the high-temperature hardness and heat resistance are drastically reduced, and this causes acceleration of wear. Therefore, Al / (Al + Ti) indicating the mutual content ratio of the Al component with the Ti component is 0.70 in atomic ratio. ~ 0.9 It was defined as.
[0010]
(B) Composition of the highest Ti content point As described above, the highest Al content point has relatively high high-temperature hardness and heat resistance, but on the other hand, the strength is relatively insufficient. In order to make up for the lack of strength, the Ti content ratio is high, while the Al content is low, thereby causing the highest Ti content point having high strength to intervene alternately in the thickness direction. However, if Ti / (Ti + Al) indicating the mutual content ratio of the Ti component with the Al component exceeds 0.95 by atomic ratio, the predetermined high-temperature hardness and heat resistance cannot be secured at the highest Ti content point. This is a cause of accelerated wear. On the other hand, if the same value is less than 0.70, the desired excellent strength cannot be ensured, and as a result, chipping is likely to occur. Ti / (Ti + Al) indicating the content ratio was determined to be 0.70 to 0.95 in atomic ratio.
[0011]
(C) Interval between the highest Al content point and the highest Ti content point If the distance is less than 0.01 μm, it is difficult to clearly form each point with the above composition. Hardness, heat resistance, and high strength cannot be ensured. Also, if the distance exceeds 0.2 μm, each point has defects, that is, if Al is the highest content point, insufficient strength, Ti highest content point If so, high-temperature hardness and insufficient heat resistance appear locally in the layer, which may cause chipping easily and promote the progress of wear. 2 μm was determined.
[0012]
(D) Overall average layer thickness of hard coating layer If the layer thickness is less than 5 μm, the desired wear resistance cannot be ensured. On the other hand, if the average layer thickness exceeds 25 μm, chipping tends to occur. Therefore, the average layer thickness was determined to be 5 to 25 μm.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated carbide tool of the present invention will be specifically described with reference to examples.
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.
[0014]
In addition, as raw material powders, TiCN (TiC / TiN = 50/50 by weight ratio) powder, Mo ₂ C powder, TiC powder, NbC powder, TaC powder, WC powder, all 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.
[0015]
Next, each of the above-mentioned carbide substrates A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, and then the carbide shown in FIG. 2 is placed in the chemical vapor deposition apparatus shown in FIG. First, when the inside of the apparatus was heated to 900 ° C. with a heater, it was loaded with TiCl ₄ : 4.2%, N ₂ : 30%, H ₂ : remaining. A reactive gas having a composition is introduced through a reactive gas blowing tube, the reaction atmosphere pressure in the apparatus is set to 30 kPa, and this state is maintained for 30 minutes, and the titanium nitride having an average layer thickness of 0.3 μm as a base adhesion layer ( TiN) layer is formed, and the atmospheric temperature in the apparatus is then heated to 1020 ° C. with a heater, and then the reaction gas composition and flow rate central control apparatus of the reaction gas composition automatic control system shown in FIG. The target Al / (Al + Ti) and target Ti / (Ti + Al) of the highest Al content point and the highest Ti content point shown in Table 3 according to the data of the actual results and the relationship between the target Ti / (Ti + Al) and reaction gas composition, the highest Al content point and the highest Ti content The reaction gas composition corresponding to the continuous change in the Al and Ti contents between points, and the target distance between the two points shown in Tables 4 and 6 and the target total layer thickness of the hard coating layer were input. The raw material gas H ₂ gas, CO ₂ gas, HCl gas, AlCl ₃ gas, and TiCl ₄ gas (in this case) through the automatic control device for the raw material gas flow rate built in the control valve that operates according to the signal from the central flow rate controller The AlCl ₃ gas is formed by reacting metal Al and HCl gas with an AlCl ₃ gas generator, and the TiCl ₄ gas is shown in FIG. The H ₂ gas whose flow rate is controlled as follows is sent to the TiCl ₄ gas generator as a carrier gas, where it is sent to the raw material gas flow automatic control device together with the TiCl ₄ gas vaporized from the liquid). However, it was introduced into the apparatus from the reaction gas blowing tube of the chemical vapor deposition apparatus of FIG. 1 (the reaction atmosphere pressure in the apparatus is always maintained at 10 kPa), and thus along the layer thickness direction on the surface of the cemented carbide substrate. The Al highest content point and the Ti highest content point of the target composition shown in Tables 3 and 4 are alternately repeated at the target intervals shown in Tables 3 and 4, and the highest Ti content from the Al highest content point. Point, having a component concentration distribution structure in which the content of Al and Ti continuously changes from the highest Ti content point to the highest Al content point, and the target total layer thickness shown in Tables 3 and 4 as well. By depositing the quality coating layer, the present invention coated carbide tool as the present invention the surface coating cemented carbide indexable (hereinafter, the present invention refers to the coating hard tip) 1 to 16 were prepared, respectively.
[0016]
For comparison purposes, these carbide substrates A1 to A10 and B1 to B6 were ultrasonically cleaned in acetone and dried, and then charged into the normal chemical vapor deposition apparatus shown in FIGS. After the reaction atmosphere temperature is heated to 1020 ° C., a reaction gas having a composition corresponding to the target Al / (Al + Zr) corresponding to the composition of the conventional hard coating layer shown in Tables 6 and 7 is introduced from the reaction gas blowing pipe. Then, under the condition that the reaction atmosphere pressure is constant at 10 kPa, each of the surfaces of the cemented carbide substrates A1 to A10 and B1 to B6 has the target composition and the target layer thickness shown in Tables 6 and 7, and By depositing a hard coating layer composed of an Al-Zr oxide layer having substantially no composition change along the thickness direction, a conventional surface-coated cemented carbide throwaway tip ( Under conventional coating referred to as hard tip) 1-16 were prepared, respectively.
[0017]
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: 350 m / min. ,
Cutting depth: 8mm,
Feed: 0.2 mm / rev. ,
Cutting time: 5 minutes
Dry-type continuous high-speed high-cut cutting test of alloy steel under the conditions of
Work material: JIS / FC300 lengthwise equidistant 4 bars with vertical grooves,
Cutting speed: 350 m / min. ,
Incision: 1.5mm,
Feed: 0.65 mm / rev. ,
Cutting time: 3 minutes
Cast iron dry intermittent high-speed high-feed cutting test under the conditions of
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 350 m / min. ,
Cutting depth: 8mm,
Feed: 0.2 mm / rev. ,
Cutting time: 3 minutes
Carbon steel was subjected to a dry intermittent high-speed high-cut cutting test 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 7.
[0018]
[Table 1]

[0019]
[Table 2]

[0020]
[Table 3]

[0021]
[Table 4]

[0022]
[Table 5]

[0023]
[Table 6]

[0024]
[Table 7]

[0025]
For the hard coating layers constituting the coated carbide chips 1 to 16 of the present invention and the conventional coated carbide chips 1 to 16 obtained as a result, the content of Al and Ti was measured along the thickness direction using an Auger spectrometer. The Al / (Al + Ti) value at each measurement point and further the Ti / (Ti + Al) value were calculated from the measurement results. In the hard coating layers of the coated carbide tips 1 to 16 of the present invention, the highest Al content point And the highest Ti content point alternately and repeatedly with substantially the same composition and interval as the target value, and the highest Al content point to the highest Ti content point, the highest Ti content point to the highest Al content point Al and It was confirmed that the Ti content had a component concentration distribution structure in which the content varied continuously, and the overall average layer thickness of the hard coating layer showed substantially the same value as the target overall layer thickness. On the other hand, in the hard coating layers of the conventional coated carbide chips 1 to 16, no composition change is observed along the thickness direction, and the composition is substantially the same as the target composition and the overall average layer thickness is substantially the same as the target overall layer thickness. Thickness indicated.
[0026]
【The invention's effect】
From the results shown in Tables 3 to 7, the Al highest content point having relatively high temperature hardness and heat resistance and the highest Ti content point having relatively high strength alternate in the layer thickness direction of the hard coating layer. And a concentration distribution structure in which the content of Al and Ti continuously changes from the highest Al content point to the highest Ti content point and from the highest Ti content point to the highest Al content point. The coated carbide chips 1 to 16 of the present invention having the above are all subjected to cutting of various steels and cast irons at high speed and under heavy cutting conditions such as high cutting and high feed with high mechanical impact In addition, the hard coating layer exhibits excellent chipping resistance, whereas the hard coating layer is made of an Al—Zr oxide layer having substantially no composition change along the layer thickness direction. 1-16, before Although the hard coating layer has high-temperature hardness and heat resistance, 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 carbide tool of the present invention is capable of cutting various steels and cast irons as well as cutting under normal conditions at high speed and with high mechanical impact. Even under heavy cutting conditions such as high feed and high feed, it exhibits excellent chipping resistance and excellent wear resistance over a long period of time. It can cope with cost reduction sufficiently satisfactorily.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing a chemical vapor deposition apparatus used for forming a hard coating layer constituting a coated carbide tool.
2A and 2B show a cemented carbide substrate support pallet that is a structural member of a chemical vapor deposition apparatus, in which FIG. 2A is a schematic perspective view, and FIG. 2B is a schematic plan view.
FIG. 3 is a reaction gas composition automatic control system used for forming a hard coating layer constituting the coated carbide tool of the present invention.

Claims

A chemical vapor deposition device is used on the surface of a tungsten carbide base cemented carbide substrate or titanium carbonitride cermet substrate, and the flow rate of each source gas is automatically controlled according to the reaction gas composition and the control signal from the flow rate central control unit. While introducing into the reaction gas blowing tube, a hard coating layer composed of a composite oxide layer of Al and Ti is a surface-coated cemented carbide cutting tool formed by chemical vapor deposition with an overall average layer thickness of 5 to 25 μm,
In the hard coating layer, the Al highest content point and the Ti highest content point are alternately present at predetermined intervals along the layer thickness direction, and the Ti highest content point, Ti A component concentration distribution structure in which the Al and Ti contents continuously change from the highest content point to the Al highest content point,
Furthermore, Al / (Al + Ti) indicating the mutual content ratio of Al and Ti at the Al highest content point is 0.70 to 0.95 in atomic ratio,
Ti / (Ti + Al) indicating the mutual content ratio of Ti and Al at the Ti highest content point is 0.70 to 0.0.95 in atomic ratio,
The distance between the Al highest content point and the Ti highest content point adjacent to each other is 0.01 to 0.2 μm,
A surface-coated cemented carbide cutting tool that exhibits excellent chipping resistance under high-speed heavy cutting conditions.