JP2004188519A

JP2004188519A - Cutting tool made of surface coated cemented carbide, hard coating layer of which shows excellent wear resistance under high speed and heavy cutting condition

Info

Publication number: JP2004188519A
Application number: JP2002357595A
Authority: JP
Inventors: Makoto Nishida; 西田　　真; Tetsuhiko Honma; 哲彦本間; Akira Osada; 晃長田
Original assignee: Mitsubishi Materials Corp
Current assignee: Mitsubishi Materials Corp
Priority date: 2002-12-10
Filing date: 2002-12-10
Publication date: 2004-07-08
Anticipated expiration: 2022-12-10
Also published as: JP3900527B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool made of surface coated cemented carbide, the hard coating layer of which shows excellent wear resistance under high speed and heavy cutting condition. <P>SOLUTION: The cutting tool made of surface coated cemented carbide is manufactured by coating the surface of a cemented carbide base body with a hard coating layer by vapor deposition. The hard coating layer is composed of a compound carbonitride layer of Ti and Hf, and has the overall average layer thickness of 1 to 15 μm. In the hard coating layer, the maximum content point of Ti and carbon and the maximum content point of Hf and nitrogen alternately and repeatedly exist at the required intervals in the layer thickness direction, and the component concentration has such a distributive structure that the the content of Ti and Hf and the content of carbon and nitrogen continuously vary in the region between both maximum content points. The maximum content point of Ti and carbon satisfies the following relationship: Ti/(Ti+Hf)=0.8 to 0.98 and carbon/(carbon+nitrogen)=0.8 to 0.98 in atomic ratio, and the maximum content point of Hf and nitrogen satisfies the following relationship: Hf/(Hf+Ti)=0.8 to 0.98 and nitrogen/(nitrogen+carbon)=0.8 to 0.98 in atomic ratio, and the distance between two neighboring points is 0.01 to 0.2 μm. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、硬質被覆層が高硬度と高強度を兼ね備え、したがって各種の鋼や鋳鉄などの切削加工を、特に高速で、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、硬質被覆層がチッピング（微小欠け）などの発生なく、すぐれた耐摩耗性を発揮する表面被覆超硬合金製切削工具（以下、被覆超硬工具という）に関するものである。
【０００２】
【従来の技術】
一般に、被覆超硬工具には、各種の鋼や鋳鉄などの被削材の旋削加工や平削り加工にバイトの先端部に着脱自在に取り付けて用いられるスローアウエイチップ、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、原子比で、
Ｔｉ／（Ｔｉ＋Ｈｆ）：０．４０〜０．６０、
炭素／（炭素＋窒素）：０．４０〜０．６０、
を満足するＴｉとＨｆの複合炭窒化物［以下、（Ｔｉ，Ｈｆ）ＣＮで示す］層からなる硬質被覆層を１〜１５μｍの平均層厚で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（例えば特許文献１参照）。
【０００４】
さらに、上記の被覆超硬工具が、例えば図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黒鉛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、
反応ガス組成；容量％で、
ＴｉＣｌ_４：０．５〜１．５％、
ＨｆＣｌ_４：１〜２％、
ＣＨ_４：５〜１２％、
Ｎ_２：２０〜４０％、
Ｈ_２：残り、
反応雰囲気温度：９５０〜１０５０℃、
反応雰囲気圧力：５〜５０ｋＰａ、
の条件で（Ｔｉ，Ｈｆ）ＣＮ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（例えば特許文献２参照）。
【０００５】
【特許文献１】
特開昭５５−５８３６４号公報
【特許文献２】
特開平７−１１４５９号公報
【０００６】
【発明が解決しようとする課題】
近年の切削加工装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求も強く、これに伴い、切削加工は高速化の傾向を深め、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が強く求められる傾向にあるが、上記の従来被覆超硬工具においては、これを通常の切削加工条件で用いた場合には問題はないが、特に切削加工を高速で、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は、硬質被覆層の強度および硬さ不足が原因で、硬質被覆層の摩耗進行が一段と促進し、かつチッピングも発生し易くなることから、比較的短時間で使用寿命に至るのが現状である。
【０００７】
【課題を解決するための手段】
そこで、本発明者等は、上述のような観点から、特に高速重切削加工条件で硬質被覆層がすぐれた耐摩耗性を発揮する被覆超硬工具を開発すべく、上記の従来被覆超硬工具を構成する硬質被覆層に着目し、研究を行った結果、
（ａ）上記の図１，２に示される化学蒸着図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，Ｈｆ）ＣＮ層は、厚さ全体に亘って実質的に均一な組成を有し、したがって均質な硬さと強度を有するが、（Ｔｉ，Ｈｆ）ＣＮ層を形成するに際して、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、前記（Ｔｉ，Ｈｆ）ＣＮ層からなる硬質被覆層に層厚方向にそってＴｉおよび炭素の最高含有点とＨｆおよび窒素の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Ｔｉおよび炭素の最高含有点並びにＨｆおよび窒素の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Ｔｉと炭素およびＨｆと窒素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および硬質被覆層の全体層厚を、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Ｈ_２ガス、ＣＨ_４ガス、Ｎ_２ガス、およびＨＣｌガスの流量、さらにＴｉＣｌ_４ガスおよびＨｆＣｌ_４ガスの流量をそれぞれの原料流量自動制御装置にて制御しながら、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、Ｔｉおよび炭素の最高含有点とＨｆおよび窒素の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Ｔｉおよび炭素の最高含有点から前記Ｈｆおよび窒素の最高含有点、前記Ｈｆおよび窒素の最高含有点から前記Ｔｉおよび炭素の最高含有点へＴｉと炭素およびＨｆと窒素の含有量が連続的に変化する成分濃度分布構造をもつた（Ｔｉ，Ｈｆ）ＣＮ層からなる硬質被覆層が形成されるようになること。
【０００８】
（ｂ）上記（ａ）の繰り返し連続変化成分濃度分布構造の（Ｔｉ，Ｈｆ）ＣＮ層において、
上記Ｔｉおよび炭素の最高含有点におけるＴｉとＨｆおよび炭素と窒素の相互含有割合を示すＴｉ／（Ｔｉ＋Ｈｆ）および炭素／（炭素＋窒素）を、それぞれ原子比で、
Ｔｉ／（Ｔｉ＋Ｈｆ）：０．８０〜０．９８、
炭素／（炭素＋窒素）：０．８０〜０．９８、
上記Ｈｆおよび窒素の最高含有点におけるＨｆとＴｉおよび窒素と炭素の相互含有割合を示すＨｆ／（Ｈｆ＋Ｔｉ）および窒素／（窒素＋炭素）を、それぞれ原子比で、
Ｈｆ／（Ｈｆ＋Ｔｉ）：０．８０〜０．９８、
窒素／（窒素＋炭素）：０．８０〜０．９８、
とし、かつ隣り合う上記Ｔｉおよび炭素の最高含有点と上記Ｈｆおよび窒素の最高含有点の厚さ方向の間隔を０．０１〜０．２μｍとすると、
上記Ｔｉおよび炭素の最高含有点部分では、Ｔｉおよび炭素が主体を占め、これら両成分の作用によってきわめて高い硬さを示し、一方上記Ｈｆおよび窒素の最高含有点部分では、Ｈｆおよび窒素が主体を占め、これら両成分の作用によって高い強度を示すようになり、かつこれらＴｉおよび炭素の最高含有点と上記Ｈｆおよび窒素の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硬度と高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，Ｈｆ）ＣＮ層からなる被覆超硬工具は、各種の鋼や鋳鉄などの切削加工を、特に高い機械的衝撃を伴う高速重切削条件で行なった場合にも、硬質被覆層にチッピングの発生なく、すぐれた耐摩耗性を発揮するようになること。
以上（ａ）および（ｂ）に示される研究結果を得たのである。
【０００９】
この発明は、上記の研究結果に基づいてなされたものであって、超硬基体の表面に、（Ｔｉ，Ｈｆ）ＣＮ層からなる硬質被覆層を１〜１５μｍ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、Ｔｉおよび炭素の最高含有点とＨｆおよび窒素の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Ｔｉおよび炭素の最高含有点から前記Ｈｆおよび窒素の最高含有点、前記Ｈｆおよび窒素の最高含有点から前記Ｔｉおよび炭素の最高含有点へＴｉとＨｆおよび炭素と窒素の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Ｔｉおよび炭素の最高含有点におけるＴｉとＨｆおよび炭素と窒素の相互含有割合を示すＴｉ／（Ｔｉ＋Ｈｆ）および炭素／（炭素＋窒素）が、それぞれ原子比で、
Ｔｉ／（Ｔｉ＋Ｈｆ）：０．８０〜０．９８、
炭素／（炭素＋窒素）：０．８０〜０．９８、
上記Ｈｆおよび窒素の最高含有点におけるＨｆとＴｉおよび窒素と炭素の相互含有割合を示すＨｆ／（Ｈｆ＋Ｔｉ）および窒素／（窒素＋炭素）が、それぞれ原子比で、
Ｈｆ／（Ｈｆ＋Ｔｉ）：０．８０〜０．９８、
窒素／（窒素＋炭素）：０．８０〜０．９８、
を満足し、かつ隣り合う上記Ｔｉおよび炭素の最高含有点と上記Ｈｆおよび窒素の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摩耗性を発揮する被覆超硬工具に特徴を有するものである。
【００１０】
つぎに、この発明の被覆超硬工具において、これを構成する硬質被覆層の構成を上記の通りに限定した理由を説明する。
（ａ）Ｔｉおよび炭素の最高含有点
上記の通り硬質被覆層である（Ｔｉ，Ｈｆ）ＣＮ層の厚さ方向に沿ってＴｉおよび炭素成分の相対的に高い部分を繰り返し形成して層自体の硬さを向上させ、同じくＨｆよび窒素成分の相対的に高い部分を繰り返し形成して層自体の強度を向上させるものであり、したがってＴｉおよび炭素の最高含有点では硬さが著しく向上したものになるので、すぐれた耐摩耗性を発揮するようになるが、この場合ＴｉとＨｆおよび炭素と窒素の相互含有割合を示すＴｉ／（Ｔｉ＋Ｈｆ）および炭素／（炭素＋窒素）がいずれも原子比で（以下、同じ）０．９８を越えると、実質的にＴｉと炭素で構成されることになることから、強度低下は避けられず、高強度を有するＨｆと窒素の最高含有点が隣接して存在しても、高い機械的衝撃を伴なう高速重切削ではチッピングが発生し易くなり、一方同値が０．８０未満になると硬さが急激に低下し、層自体の摩耗が促進するようになることから、Ｔｉ／（Ｔｉ＋Ｈｆ）および炭素／（炭素＋窒素）の値をいずれも０．８０〜０．９８と定めた。
【００１１】
（ｂ）Ｈｆおよび窒素の最高含有点
上記の通りＴｉおよび炭素の最高含有点は相対的にすぐれた硬さを有するが、反面相対的に強度が不十分であるため、このＴｉおよび炭素の最高含有点の強度不足を補う目的で、高強度を有するＨｆおよび窒素の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、ＨｆとＴｉおよび窒素と炭素の相互含有割合を示すＨｆ／（Ｈｆ＋Ｔｉ）および窒素／（窒素＋炭素）が、それぞれ０．９８を越えると、実質的にＨｆと窒素で構成されるようになることから、Ｈｆおよび窒素の最高含有点に所定の硬さを確保することができず、これが摩耗促進の原因となり、一方同値がいずれも０．８０未満になると、急激な強度低下が起り、この結果チッピングが発生し易くなることから、Ｈｆ／（Ｈｆ＋Ｔｉ）および窒素／（窒素＋炭素）の値をいずれも０．８０〜０．９８と定めた。
【００１２】
（ｃ）Ｔｉおよび炭素の最高含有点とＨｆおよび窒素の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硬度と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Ｔｉおよび炭素の最高含有点であれば強度不足、Ｈｆおよび窒素の最高含有点であれば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０．０１〜０．２μｍと定めた。
【００１３】
（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。
【００１４】
【発明の実施の形態】
つぎに、この発明の被覆超硬工具を実施例により具体的に説明する。
原料粉末として、平均粒径：６．５μｍを有する粗粒ＷＣ粉末、同３．５μｍを有する中粒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１．０μｍの（Ｔｉ，Ｗ）ＣＮ（質量比で、ＴｉＣ／ＴｉＮ／ＷＣ＝２４／２０／５６）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１に示される配合組成に配合し、ボールミルで７２時間混合し、減圧乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を、表面部にＣｏ富化層を形成するものについては１３．３Ｐａ、そして全体に亘って均一組織を有するものについては６．７Ｐａの真空中、温度：１４３０℃に１時間保持の条件で焼結し、焼結後、切刃部分にＲ：０．０８のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１６０６１２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。なお、超硬基体Ａ−１、Ａ−３、Ａ−４、Ａ−６、Ａ−７、およびＡ−９の表面部にＣｏ富化層の形成が見られた。
【００１５】
また、原料粉末として、いずれも０．５〜２μｍの平均粒径を有するＨｆＣＮ（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：０．１０のホーニング加工を施してＩＳＯ規格・ＣＮＭＧ１６０６１２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。
【００１６】
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、ＴｉＣｌ_４：４．２％、Ｎ_２：３０％、Ｈ_２：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２０分間保持して前記超硬基体表面に、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Ｔｉおよび炭素の最高含有点の目標Ｔｉ／（Ｔｉ＋Ｈｆ）および炭素／（炭素＋窒素）、さらにＨｆおよび窒素の最高含有点の目標Ｈｆ／（Ｈｆ＋Ｔｉ）および窒素／（窒素＋炭素）に対応する反応ガス組成、前記Ｔｉおよび炭素の最高含有点とＨｆおよび窒素の最高含有点間のＴｉとＨｆおよび炭素と窒素の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蔵の原料ガス流量自動制御装置を通して、原料ガスであるＨ_２ガス、Ｎ_２ガス、ＣＨ_４ガス、ＨｆＣｌ_４ガス、およびＴｉＣｌ_４ガス（この場合、前記ＴｉＣｌ_４ガスは図示の通り流量制御されたＨ_２ガスをキャリアガスとしてＴｉＣｌ_４ガス気化器に送り、ここで液体から気化されたＴｉＣｌ_４と共に原料ガス流量自動制御装置に送られ、また前記ＨｆＣｌ_４ガスは、ＨｆＣｌ_４発生器で金属Ｈｆと流量制御されたＨＣｌガスを反応させることにより形成される）を、それぞれのガス流量を自動制御しながら、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７ｋＰａ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Ｔｉ／（Ｔｉ＋Ｈｆ）および炭素／（炭素＋窒素）のＴｉおよび炭素の最高含有点と、目標Ｈｆ／（Ｈｆ＋Ｔｉ）および窒素／（窒素＋炭素）のＨｆおよび窒素の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Ｔｉおよび炭素の最高含有点から前記Ｈｆおよび窒素の最高含有点、前記Ｈｆおよび窒素の最高含有点から前記Ｔｉおよび炭素の最高含有点へＴｉとＨｆおよび炭素と窒素の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。
【００１７】
また、比較の目的で、上記の超硬基体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、上記したＴｉＮ層形成条件と同じ条件で下地密着層として０．３μｍの平均層厚を有するＴｉＮ層を形成し、ついで反応雰囲気温度を１０２０℃に加熱した後、それぞれ表６，７に示される目標Ｔｉ／（Ｔｉ＋Ｈｆ）および目標炭素／（炭素＋窒素）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７ｋＰａ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（Ｔｉ，Ｈｆ）ＣＮ層からなる硬質被覆層を蒸着することにより、従来被覆超硬工具としての従来表面被覆超硬合金製スローアウエイチップ（以下、従来被覆超硬チップと云う）１〜１６をそれぞれ製造した。
【００１８】
つぎに、上記本発明被覆超硬チップ１〜１６および従来被覆超硬チップ１〜１６について、これを工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、
被削材：ＪＩＳ・ＳＣＭ４１５の丸棒、
切削速度：４００ｍ／ｍｉｎ．、
切り込み：５．５ｍｍ、
送り：０．２５ｍｍ／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・Ｓ２５Ｃの長さ方向等間隔４本縦溝入り丸棒、
切削速度：３８０ｍ／ｍｉｎ．、
切り込み：２．０ｍｍ、
送り：０．５０ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での炭素鋼の乾式断続高速高送り切削加工試験、さらに、
被削材：ＪＩＳ・ＦＣ３００の長さ方向等間隔４本縦溝入り丸棒、
切削速度：４５０ｍ／ｍｉｎ．、
切り込み：５．０ｍｍ、
送り：０．３０ｍｍ／ｒｅｖ．、
切削時間：５分、
の条件での鋳鉄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４〜７に示した。
【００１９】
【表１】

【００２０】
【表２】

【００２１】
【表３】

【００２２】
【表４】

【００２３】
【表５】

【００２４】
【表６】

【００２５】
【表７】

【００２６】
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Ｔｉ、Ｈｆ、炭素、および窒素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Ｔｉ／（Ｔｉ＋Ｈｆ）および炭素／（炭素＋窒素）値、さらにＨｆ／（Ｈｆ＋Ｔｉ）および窒素／（窒素＋炭素）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、Ｔｉおよび炭素の最高含有点と、Ｈｆおよび窒素の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Ｔｉおよび炭素の最高含有点からＨｆおよび窒素の最高含有点、前記Ｈｆおよび窒素の最高含有点からＴｉおよび炭素の最高含有点へＴｉとＨｆおよび炭素と窒素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すことが確認された。
【００２７】
【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硬度を有するＴｉおよび炭素の最高含有点と相対的に高強度を有するＨｆおよび窒素の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Ｔｉおよび炭素の最高含有点から前記Ｈｆおよび窒素の最高含有点、前記Ｈｆおよび窒素の最高含有点から前記Ｔｉおよび炭素の最高含有点へＴｉとＨｆおよび炭素と窒素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摩耗性および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従来被覆超硬チップ１〜１６においては、特に高い機械的衝撃を伴う高速重切削条件では強度不足が原因でチッピングが発生し、硬さ不足と相俟って、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、すぐれた耐摩耗性と耐チッピング性を発揮し、長期に亘ってすぐれた切削性能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られている化学蒸着装置を例示する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の概略チャート図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a hard coating layer having both high hardness and high strength, and therefore, can cut various kinds of steel and cast iron at a high speed, especially under heavy cutting conditions such as high cutting and high feed with high mechanical impact. The present invention 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 wear resistance without occurrence of chipping (minute chipping) when performed.
[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, and the like, and the cutting method 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, collectively referred to as a cemented carbide substrate) ) On the surface, in atomic ratio,
Ti / (Ti + Hf): 0.40 to 0.60,
Carbon / (carbon + nitrogen): 0.40 to 0.60,
A coated carbide tool formed by depositing a hard coating layer composed of a composite carbonitride of Ti and Hf [hereinafter, referred to as (Ti, Hf) CN] with an average layer thickness of 1 to 15 μm, It is also known that when used in continuous cutting or intermittent cutting of various types of steel or cast iron, excellent cutting performance is exhibited (for example, see Patent Document 1).
[0004]
Further, as shown in the schematic vertical sectional view of FIG. 1, for example, the above coated carbide tool is provided with a reaction gas blowing pipe made of stainless steel at the center thereof, and the reaction gas blowing pipe is provided with a reaction gas blowing pipe shown in FIG. Graphite carbide substrate support pallets exemplified in a schematic perspective view in a) and a schematic plan view in b) are skewered, stacked and fitted, and heated by a heater via a stainless steel cover. Using a chemical vapor deposition apparatus having a structure as shown in the figure, the cemented carbide substrate is mounted on the chemical vapor deposition apparatus in a state where it is placed as shown in a number of reaction gas passage holes formed on the bottom surface of the cemented carbide support pallet. Enter
Reaction gas composition; in volume%
TiCl _4: 0.5~1.5%,
HfCl _4: 1~2%,
CH _4: 5~12%,
N _2: 20~40%,
H ₂ : remaining,
Reaction atmosphere temperature: 950-1050 ° C,
Reaction atmosphere pressure: 5 to 50 kPa,
It is also known to manufacture by forming a hard coating layer made of (Ti, Hf) CN under the following conditions (for example, see Patent Document 2).
[0005]
[Patent Document 1]
JP-A-55-58364 [Patent Document 2]
JP-A-7-11459
[Problems to be solved by the invention]
In recent years, the performance of cutting equipment has been remarkably improved, and on the other hand, there is a strong demand for labor-saving and energy-saving cutting, as well as low cost. There is a tendency to strongly demand 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 normal cutting conditions, but especially cutting When processing is performed at high speed and under heavy cutting conditions such as high cutting and high feed with high mechanical impact, wear of the hard coating layer further increases due to insufficient strength and hardness of the hard coating layer. At the present, the use life is shortened in a relatively short time since the acceleration is promoted and the chipping easily occurs.
[0007]
[Means for Solving the Problems]
In view of the above, the present inventors have developed the above-mentioned conventional coated cemented carbide tool in order to develop a coated cemented carbide tool in which the hard coating layer exhibits excellent wear resistance particularly under high-speed heavy cutting conditions. Focusing on the hard coating layer that constitutes
(A) The (Ti, Hf) CN layer constituting the conventional coated carbide tool formed by using the chemical vapor deposition apparatus shown in FIGS. 1 and 2 is substantially uniform throughout its thickness. Although having a composition and thus a uniform hardness and strength, in forming the (Ti, Hf) CN layer, for example, a reaction gas composition automatic control system shown in FIG. In the flow rate central control unit, the highest content points of Ti and carbon and the highest content points of Hf and nitrogen are alternately arranged at predetermined intervals along the thickness direction of the hard coating layer composed of the (Ti, Hf) CN layer. For the purpose of repeated formation, a reaction gas composition corresponding to the highest content point of Ti and carbon and the highest content point of Hf and nitrogen, and a reaction gas corresponding to continuous change of Ti and carbon and Hf and nitrogen between the two points. Formed, further wherein the entire layer thickness of the spacing and the hard coating layer between the two points, and inputs based on historical data, according to a control signal from the reaction gas composition and flow rates central controller, H from the raw material gas cylinder While controlling the flow rates of the ₂ gas, the CH ₄ gas, the N ₂ gas, and the HCl gas, and the flow rates of the TiCl ₄ gas and the HfCl ₄ gas with the respective raw material flow automatic controllers, the reaction gas blowout pipe of the chemical vapor deposition apparatus is used. When introduced, the highest content points of Ti and carbon and the highest content points of Hf and nitrogen are alternately and repeatedly present at predetermined intervals along the layer thickness direction, and the highest content points of Ti and carbon are changed from the highest content points of Ti and carbon to Hf And the highest point of nitrogen, from the highest point of Hf and nitrogen to the highest point of Ti and carbon, containing Ti and carbon and Hf and nitrogen A hard coating layer composed of a (Ti, Hf) CN layer having a component concentration distribution structure in which the amount continuously changes is formed.
[0008]
(B) In the (Ti, Hf) CN layer having the concentration distribution structure of the continuously changing component of the above (a),
Ti / (Ti + Hf) and carbon / (carbon + nitrogen) indicating the mutual content ratio of Ti and Hf and carbon and nitrogen at the highest content points of Ti and carbon, respectively, are represented by atomic ratios,
Ti / (Ti + Hf): 0.80 to 0.98,
Carbon / (carbon + nitrogen): 0.80 to 0.98,
Hf / (Hf + Ti) and nitrogen / (nitrogen + carbon), which indicate the mutual content of Hf and Ti and nitrogen and carbon at the highest content points of Hf and nitrogen, respectively, are represented by atomic ratios,
Hf / (Hf + Ti): 0.80 to 0.98,
Nitrogen / (nitrogen + carbon): 0.80 to 0.98,
And the distance between the highest content point of adjacent Ti and carbon and the highest content point of Hf and nitrogen in the thickness direction is 0.01 to 0.2 μm,
In the highest Ti and carbon content points, Ti and carbon occupy the main part, and due to the action of these two components, extremely high hardness is exhibited. On the other hand, in the Hf and nitrogen highest content parts, Hf and nitrogen predominate. Occupied by these two components, and exhibited a high strength by the action of these two components, and the interval between the highest content point of Ti and carbon and the highest content point of Hf and nitrogen was extremely small. Therefore, the coated carbide tool composed of the (Ti, Hf) CN layer having the configuration in which the hard coating layer is formed can be used for cutting various kinds of steel, cast iron, etc., in particular, with high mechanical impact. Even when the cutting is performed under high-speed heavy cutting conditions, the hard coating layer exhibits excellent wear resistance without chipping.
The research results shown in (a) and (b) above were obtained.
[0009]
The present invention has been made based on the results of the above-mentioned research, and comprises depositing a hard coating layer composed of a (Ti, Hf) CN layer on the surface of a super-hard substrate with a total average layer thickness of 1 to 15 μm. Coated carbide tools,
In the hard coating layer, the highest content points of Ti and carbon and the highest content points of Hf and nitrogen are alternately present at predetermined intervals along the layer thickness direction, and the highest content points of the Ti and carbon are present. From the maximum content point of Hf and nitrogen, and the maximum content point of Hf and nitrogen to the maximum content point of Ti and carbon. And
Furthermore, Ti / (Ti + Hf) and carbon / (carbon + nitrogen), which indicate the mutual content of Ti and Hf and carbon and nitrogen at the highest content points of Ti and carbon, respectively, are represented by atomic ratios,
Ti / (Ti + Hf): 0.80 to 0.98,
Carbon / (carbon + nitrogen): 0.80 to 0.98,
Hf / (Hf + Ti) and nitrogen / (nitrogen + carbon) indicating the mutual content ratio of Hf and Ti and nitrogen and carbon at the highest content points of Hf and nitrogen are represented by atomic ratios,
Hf / (Hf + Ti): 0.80 to 0.98,
Nitrogen / (nitrogen + carbon): 0.80 to 0.98,
And the interval between the adjacent highest content points of Ti and carbon and the highest content points of Hf and nitrogen is 0.01 to 0.2 μm,
The present invention is characterized by a coated carbide tool in which a hard coating layer exhibits excellent wear resistance under high-speed heavy cutting conditions.
[0010]
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) The highest content point of Ti and carbon As described above, a relatively high portion of Ti and carbon components is repeatedly formed along the thickness direction of the (Ti, Hf) CN layer which is a hard coating layer to form the layer itself. This is to improve the hardness, and also to repeatedly form relatively high portions of Hf and nitrogen components to improve the strength of the layer itself. Therefore, at the highest content point of Ti and carbon, the hardness is remarkably improved. Therefore, excellent wear resistance is exhibited. In this case, Ti / (Ti + Hf) and carbon / (carbon + nitrogen), which indicate the mutual content of Ti and Hf and carbon and nitrogen, are expressed in atomic ratios. If it exceeds 0.98 (hereinafter the same), since it is substantially composed of Ti and carbon, a decrease in strength is inevitable, and the highest content points of Hf and nitrogen having high strength are adjacent to each other. Even if it exists, In high-speed heavy cutting with high mechanical impact, chipping is liable to occur. On the other hand, when the value is less than 0.80, the hardness decreases rapidly and the wear of the layer itself is accelerated. Both the values of / (Ti + Hf) and carbon / (carbon + nitrogen) were determined to be 0.80 to 0.98.
[0011]
(B) Maximum content of Hf and nitrogen As described above, the maximum content of Ti and carbon has relatively excellent hardness, but on the other hand, the strength is relatively insufficient. In order to compensate for the insufficient strength of the content points, the highest content points of Hf and nitrogen having high strength are alternately interposed in the thickness direction. However, when Hf / (Hf + Ti) and nitrogen / (nitrogen + carbon), which indicate the mutual content ratio of Hf and Ti and nitrogen and carbon, respectively exceed 0.98, they become substantially composed of Hf and nitrogen. Therefore, a predetermined hardness cannot be secured at the highest content point of Hf and nitrogen, which causes acceleration of abrasion. On the other hand, when both values are less than 0.80, a sharp decrease in strength occurs, As a result, chipping is likely to occur. Therefore, the values of Hf / (Hf + Ti) and nitrogen / (nitrogen + carbon) were both set to 0.80 to 0.98.
[0012]
(C) The distance between the highest content point of Ti and carbon and the highest content point of Hf and nitrogen 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 layer In addition, it is not possible to secure the desired excellent high hardness and high strength, and if the interval exceeds 0.2 μm, the disadvantage of each point, that is, if the maximum content point of Ti and carbon, the strength is insufficient, Hf In the case of the highest nitrogen content, insufficient hardness appears locally in the layer, which causes chipping to occur easily and promotes abrasion progress. ０．２0.2 μm.
[0013]
(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.
[0014]
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.
As raw material powders, coarse WC powder having an average particle size of 6.5 μm, medium WC powder having an average particle size of 3.5 μm, fine WC powder having an average particle size of 0.8 μm, TaC powder having an average particle size of 1.3 μm, and 1.2 μm NbC powder, 1.2 μm ZrC powder, 2.3 μm Cr ₃ C ₂ powder, 1.0 μm (Ti, W) CN (TiC / TiN / WC = 24/20/56 by mass ratio) ) Powder and Co powder of 1.8 μm were prepared, and each of these raw material powders was blended to the composition shown in Table 1, mixed with a ball mill for 72 hours, dried under reduced pressure, and then compacted at a pressure of 100 MPa. This compact is press-formed in a vacuum of 13.3 Pa for those forming a Co-enriched layer on the surface and 6.7 Pa for those having a uniform structure over the entire surface at a temperature of 1430. At 1 ° C for 1 hour After sintering, after sintering, the cutting edge portion was subjected to a honing process of R: 0.08 to form cemented carbide substrates A1 to A10 made of a WC-based cemented carbide having a tip shape of ISO standard CNMG160612. Note that formation of a Co-enriched layer was observed on the surface portions of the carbide substrates A-1, A-3, A-4, A-6, A-7, and A-9.
[0015]
Further, as raw material powders, HfCN (TiC / TiN = 50/50 by weight) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder all 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 2 kPa nitrogen atmosphere at a temperature of 1500 ° C. for 1 hour, and after sintering, the cutting edge portion was subjected to honing processing with an R of 0.10 to conform to ISO standard CNMG160612. Carbide bases B1 to B6 made of TiCN-based cermet having the chip shape described above were formed.
[0016]
Next, each of the above-mentioned super-hard substrates A1 to A10 and B1 to B6 is subjected to ultrasonic cleaning in acetone, dried, and then placed in a chemical vapor deposition apparatus shown in FIG. It was loaded while being placed in the positioning holes of the substrate supporting pallet. First, when the inside of the apparatus was heated to 900 ° C. with a heater, TiCl ₄ : 4.2%, N ₂ : 30%, and H ₂ : remainder. A reaction gas having a composition is introduced through a reaction gas blow-out tube, the reaction atmosphere pressure in the apparatus is set to 30 kPa, and the state is maintained for 20 minutes. After forming a thick titanium nitride (TiN) layer and then heating the atmosphere in the apparatus to 1020 ° C. with a heater, the reaction gas composition of the reaction gas composition automatic control system shown in FIG. According to the data of the past performance, the target Ti / (Ti + Hf) and carbon / (carbon + nitrogen) and the maximum content of Hf and nitrogen of the highest content of Ti and carbon shown in Table 3 Reaction gas composition corresponding to the target point Hf / (Hf + Ti) and nitrogen / (nitrogen + carbon), the content of Ti and Hf and the content of carbon and nitrogen between the highest content point of Ti and carbon and the highest content point of Hf and nitrogen The reaction gas composition corresponding to the continuous change of the amount, the target interval between the two points and the target total layer thickness of the hard coating layer shown in Tables 4 and 6 are input, and the reaction gas composition and the flow rate from the central controller are controlled. through the raw material gas flow automatic control of the control valve built to operate in accordance with the signal, _{H 2} gas as a source gas, _{N 2} gas, CH ₄ gas, HfCl ₄ moth , And TiCl ₄ gas (in this case, the TiCl ₄ gas is TiCl ₄ feed to the gas vaporizer as flow controlled _{H 2} gas shown as a carrier gas, the raw material gas flow rate automatic here with TiCl ₄ which has been vaporized from the liquid The HfCl ₄ gas is sent to a controller, and the HfCl ₄ gas is formed by reacting a metal Hf with a flow-controlled HCl gas in a HfCl ₄ generator. (The reaction atmosphere pressure in the apparatus is always kept at 7 kPa) through the reaction gas blow-out pipe of the chemical vapor deposition apparatus of (1). And the maximum content of Ti and carbon in the target Ti / (Ti + Hf) and carbon / (carbon + nitrogen), and the target Hf / (Hf + Ti) and nitrogen / (nitrogen + And the highest content points of Hf and nitrogen alternately and repeatedly at the target intervals shown in Tables 3 and 4, and from the highest content points of Ti and carbon, the highest content points of Hf and nitrogen; And the component concentration distribution structure in which the contents of Ti and Hf and the contents of carbon and nitrogen continuously change from the highest content point of nitrogen to the highest content point of Ti and carbon, respectively, and are also shown in Tables 3 and 4. By depositing a hard coating layer having the target overall layer thickness, the surface coated cemented carbide throw-away tips (hereinafter, referred to as the coated cemented carbide tips of the present invention) 1 to 16 as the coated cemented carbide tools of the present invention, respectively. Manufactured.
[0017]
For the purpose of comparison, the above-mentioned super-hard substrates A1 to A10 and B1 to B6 were ultrasonically cleaned in acetone, dried, and then loaded into a normal chemical vapor deposition apparatus also shown in FIGS. Then, a TiN layer having an average layer thickness of 0.3 μm was formed as a base adhesion layer under the same conditions as the above-described TiN layer formation conditions, and then the reaction atmosphere temperature was heated to 1020 ° C., and shown in Tables 6 and 7, respectively. A reaction gas having a composition corresponding to the target Ti / (Ti + Hf) and the target carbon / (carbon + nitrogen) is introduced from a reaction gas blow-out tube, and under the condition that the reaction atmosphere pressure is kept constant at 7 kPa, the cemented carbide substrates A1 to On each surface of A10 and B1 to B6, a (Ti, Hf) CN layer having the target composition and the target layer thickness shown in Tables 6 and 7 and having substantially no composition change along the layer thickness direction. Become By depositing the quality coating layer, conventional coating conventional surface-coated cemented carbide indexable as cemented carbide (hereinafter, conventional coating called carbide inserts) were 1-16 were prepared, respectively.
[0018]
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 SCM415 round bar,
Cutting speed: 400 m / min. ,
Cut: 5.5 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 5 minutes,
Dry continuous high-speed high-cut cutting test of alloy steel under the following conditions:
Work material: JIS S25C lengthwise round bar with four equally spaced longitudinal grooves,
Cutting speed: 380 m / min. ,
Notch: 2.0 mm,
Feed: 0.50 mm / rev. ,
Cutting time: 5 minutes,
Intermittent high-speed high-feed cutting test of carbon steel under the conditions of
Work material: Round bar with four vertical grooves at equal intervals in the length direction of JIS / FC300
Cutting speed: 450 m / min. ,
Cut: 5.0 mm,
Feed: 0.30 mm / rev. ,
Cutting time: 5 minutes,
A dry intermittent high-speed, high-cut cutting test was performed on cast iron under the following conditions, and the flank wear width of the cutting edge was measured in each cutting test. The measurement results are shown in Tables 4 to 7.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
[Table 3]

[0022]
[Table 4]

[0023]
[Table 5]

[0024]
[Table 6]

[0025]
[Table 7]

[0026]
Regarding the hard coating layers constituting the coated carbide tips 1 to 16 of the present invention and the conventional coated carbide tips 1 to 16 obtained as described above, the contents of Ti, Hf, carbon and nitrogen were determined along the thickness direction by Auger. The measurement was performed using a spectrophotometer, and the Ti / (Ti + Hf) and carbon / (carbon + nitrogen) values, and further, the Hf / (Hf + Ti) and nitrogen / (nitrogen + carbon) values at each measurement point were calculated from the measurement results. However, in the hard coating layers of the coated superhard tips 1 to 16 of the present invention, the highest content points of Ti and carbon and the highest content points of Hf and nitrogen are alternately repeated at substantially the same composition and interval as the target values, respectively. From the highest point of Ti and carbon to the highest point of Hf and nitrogen, from the highest point of Hf and nitrogen to the highest point of Ti and carbon It is confirmed that the content of nitrogen has a continuously changing component concentration distribution structure, also showing the overall mean layer thickness even entire target layer thickness substantially the same value of the hard layer. On the other hand, in the hard coating layers of the conventional coated carbide tips 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 is substantially the same as the target total layer thickness. It was confirmed that the film showed a thickness.
[0027]
【The invention's effect】
From the results shown in Tables 3 to 7, the hard coating layer has, in the layer thickness direction, the highest content points of Ti and carbon having relatively high hardness and the highest content point of Hf and nitrogen having relatively high strength. Are present alternately at predetermined intervals, and from the highest content point of Ti and carbon to the highest content point of Hf and nitrogen, from the highest content point of Hf and nitrogen to the highest content point of Ti and carbon. The coated carbide tips 1 to 16 of the present invention having a component concentration distribution structure in which the contents of Ti and Hf and the contents of carbon and nitrogen continuously change, all of which can cut various kinds of steel and cast iron at high speed, and The hard coating layer exhibits excellent wear and chipping resistance even under heavy cutting conditions such as high cutting and high feed with high mechanical impact, whereas the hard coating layer has a large thickness. Along the direction In conventional coated carbide tips 1 to 16 having substantially no composition change, chipping occurs due to lack of strength, especially in high-speed heavy cutting conditions accompanied by high mechanical impact, and this is combined with insufficient hardness. It is clear that the service life can be reached in an extremely short time.
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 depth accompanied by high mechanical impact. Even when performed under heavy cutting conditions such as high feed and high feed, it exhibits excellent wear resistance and chipping resistance, and exhibits excellent cutting performance over a long period of time. Therefore, it is possible to satisfactorily respond to cost reduction and cost reduction.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view illustrating a chemical vapor deposition apparatus used for forming a hard coating layer constituting a coated carbide tool.
FIGS. 2A and 2B show a super hard substrate supporting pallet as a structural member of the chemical vapor deposition apparatus, wherein FIG. 2A is a schematic perspective view and FIG.
FIG. 3 is a schematic chart of 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 surface-coated cemented carbide obtained by depositing a hard coating layer composed of a composite carbonitride layer of Ti and Hf on the surface of a tungsten carbide-based cemented carbide substrate or a titanium carbonitride-based cermet substrate with an overall average thickness of 1 to 15 μm. In cutting tools made of alloy,
In the hard coating layer, the highest content points of Ti and carbon and the highest content points of Hf and nitrogen are alternately present at predetermined intervals along the layer thickness direction, and the highest content points of the Ti and carbon are present. From the maximum content point of Hf and nitrogen, and the maximum content point of Hf and nitrogen to the maximum content point of Ti and carbon. And
Furthermore, Ti / (Ti + Hf) and carbon / (carbon + nitrogen), which indicate the mutual content of Ti and Hf and carbon and nitrogen at the highest content points of Ti and carbon, respectively, are represented by atomic ratios,
Ti / (Ti + Hf): 0.80 to 0.98,
Carbon / (carbon + nitrogen): 0.80 to 0.98,
Hf / (Hf + Ti) and nitrogen / (nitrogen + carbon) indicating the mutual content ratio of Hf and Ti and nitrogen and carbon at the highest content points of Hf and nitrogen are represented by atomic ratios,
Hf / (Hf + Ti): 0.80 to 0.98,
Nitrogen / (nitrogen + carbon): 0.80 to 0.98,
And the interval between the adjacent highest content points of Ti and carbon and the highest content points of Hf and nitrogen is 0.01 to 0.2 μm;
Surface coated cemented carbide cutting tool with a hard coating layer that exhibits excellent wear resistance under high speed heavy cutting conditions.