JP3847117B2

JP3847117B2 - Surface-coated cemented carbide end mill or drill with excellent wear-resistant coating and excellent heat dissipation

Info

Publication number: JP3847117B2
Application number: JP2001234332A
Authority: JP
Inventors: 和則佐藤; 裕介田中; 夏樹一宮; 暁裕近藤
Original assignee: 三菱マテリアル神戸ツールズ株式会社
Priority date: 2001-08-02
Filing date: 2001-08-02
Publication date: 2006-11-15
Anticipated expiration: 2021-08-02
Also published as: JP2003039211A

Description

【０００１】
【発明の属する技術分野】
この発明は、特に高熱発生を伴なう鋼などの高速切削で、耐摩耗被覆層がすぐれた放熱性を発揮して、過熱による摩耗進行を抑制し、もって一段の使用寿命の延命化を可能ならしる表面被覆超硬合金製エンドミルおよびドリル（以下、被覆超硬エンドミルまたは被覆超硬ドリルと云う）に関するものである。
【０００２】
【従来の技術】
切削工具として、各種の鋼や鋳鉄などの被削材の穴あけ切削加工などに用いられる被覆超硬ドリルや被覆超硬ミニチュアドリル、さらに前記被削材の面削加工や溝加工、肩加工などに用いられるソリッドタイプの被覆超硬エンドミルが知られている。
【０００３】
また、炭化タングステン（以下、ＷＣで示す）基超硬合金からなるエンドミル基体またはドリル基体の表面に、図１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を用い、ヒータで装置内を例えば７００℃の温度に加熱した状態で、アノード電極と、下地強靭層形成には金属Ｔｉ、下側硬質層形成には所定組成を有するＴｉ−Ａｌ合金、さらに上側硬質層形成には金属Ａｌがセットされたカソード電極（蒸発源）との間にアーク放電を発生させ、同時に装置内に反応ガスとしてメタンガスおよび／または窒素ガス、あるいは酸素を導入し、一方前記アノード電極およびカソード電極と所定間隔をもって対向配置されたエンドミル基体またはドリル基体には、例えば−１２０Ｖのバイアス電圧を印加した条件で、
（ａ）Ｔｉの炭化物層、窒化物層、および炭窒化物層（以下、それぞれＴｉＣ層、ＴｉＮ層、およびＴｉＣＮ層で示す）のうちの１種の単層または２種以上の複層からなり、かつ０．１〜１０μｍの平均層厚を有する下地強靭層、
（ｂ）組成式：（Ｔｉ_1-XＡｌ_X）Ｎおよび同（Ｔｉ_{1 -X} Ａｌ_X ）Ｃ_1- _ｍＮ_ｍ（ただし、原子比で、厚さ方向中央部のオージェ分光分析装置による測定で、Ｘは０．３〜０．７、ｍは０．５〜０．９９を示す）を有するＴｉとＡｌの複合窒化物層［以下、（Ｔｉ，Ａｌ）Ｎで示す］およびＴｉとＡｌの複合炭窒化物層［以下、（Ｔｉ，Ａｌ）ＣＮで示す］のうちのいずれかの単層、または両方の複層からなり、かつ０．１〜１５μｍの平均層厚を有する下側硬質層、
（ｃ）酸化アルミニウム（以下、Ａｌ₂Ｏ₃で示す）層からなり、かつ０．５〜１５μｍの平均層厚を有する上側硬質層、
以上（ａ）〜（ｃ）で構成された耐摩耗被覆層を形成することにより被覆超硬エンドミルまたは被覆超硬ドリルを製造する試みがなされている。
【０００４】
【発明が解決しようとする課題】
一方、近年の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、切削加工は切削機械の高性能化とも相俟って高速化の傾向にあるが、上記の従来被覆超硬エンドミルまたは被覆超硬ドリルにおいては、これを鋼や鋳鉄などの通常の条件での切削加工に用いた場合には問題はないが、これを高速切削条件で用いると、切削加工時に発生する高熱によって、特に耐摩耗被覆層の温度が上昇し、この結果耐摩耗被覆層の摩耗は一段と促進されるようになることから、比較的短時間で使用寿命に至るのが現状である。
【０００５】
【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、上記の従来被覆超硬エンドミルまたは被覆超硬ドリルに着目し、特に高速切削時における耐摩耗被覆層の温度上昇を抑制すべく研究を行った結果、
上記の従来被覆超硬エンドミルまたは被覆超硬ドリルの耐摩耗被覆層の表面層として、同じくアークイオンプレーティング装置を用い、カソード電極（蒸発源）として金属Ａｌを用い、反応ガスとして窒素ガスを導入して窒化アルミニウム（以下、ＡｌＮで示す）層を形成すると、この結果の耐摩耗被覆層においては、前記ＡｌＮ層がすぐれた熱伝導性および熱的安定性を発揮するようになって、耐摩耗被覆層の放熱性が一段と向上し、高速切削時に発生する高熱に曝されても耐摩耗被覆層自体の過熱は著しく抑制され、かつ前記下地強靭層、下側硬質層、および上側硬質層によって耐摩耗被覆層はすぐれた靭性と高温硬さ、さらにすぐれた耐熱性も併せ持つようになることから、この耐摩耗被覆層を形成してなる被覆超硬エンドミルまたは被覆超硬ドリルは、これを特に鋼や鋳鉄などの高熱発生を伴なう高速切削加工に用いても、耐摩耗被覆層はすぐれた放熱性を発揮し、これ自体の過熱による摩耗進行が抑制され、一段とすぐれた耐摩耗性を発揮するようになる、という研究結果を得たのである。
【０００６】
この発明は、上記の研究結果にもとづいてなされたものであって、アークイオンプレーティング装置にて、ＷＣ基超硬合金で構成されたエンドミル基体またはドリル基体の表面に、
（ａ）カソード電極（蒸発源）として金属Ｔｉを用い、反応ガスとしてメタンガス、窒素ガス、またはメタンガスと窒素ガスを導入して形成された、ＴｉＣ層、ＴｉＮ層、およびＴｉＣＮ層のうちの１種の単層または２種以上の複層からなり、かつ０．１〜１０μｍの平均層厚を有する下地強靭層、
（ｂ）カソード電極（蒸発源）としてＴｉ−Ａｌ合金を用い、反応ガスとして窒素ガス、またはメタンガスと窒素ガスを導入して形成された、組成式：（Ｔｉ_1-X Ａｌ_X ）Ｎおよび同（Ｔｉ_1-X Ａｌ_X ）Ｃ_1- _ｍＮ_ｍで表わした場合、厚さ方向中央部のオージェ分光分析装置による測定で、原子比で、Ｘ：０．３０〜０．７０、ｍ：０．５〜０．９９を満足する（Ｔｉ，Ａｌ）Ｎ層および（Ｔｉ，Ａｌ）ＣＮ層のうちのいずれか、または両方からなり、かつ０．５〜１５μｍの平均層厚を有する下側硬質層、
（ｃ）カソード電極（蒸発源）として金属Ａｌを用い、反応ガスとして酸素を導入して形成されたＡｌ₂Ｏ₃層からなり、かつ０．５〜１５μｍの平均層厚を有する上側硬質層、
（ｄ）カソード電極（蒸発源）として金属Ａｌを用い、反応ガスとして窒素ガスを導入して形成されたＡｌＮ層からなり、かつ０．５〜１５μｍの平均層厚を有する表面放熱層、
以上（ａ）〜（ｄ）で構成した耐摩耗被覆層を形成してなる、耐摩耗被覆層がすぐれた放熱性を発揮する被覆超硬エンドミルまたは被覆超硬ドリルに特徴を有するものである。
【０００７】
つぎに、この発明の被覆超硬エンドミルまたは被覆超硬ドリルにおいて、これの耐摩耗被覆層を構成する下地強靭層、下側硬質層、上側硬質層、および表面放熱層について説明する。
（ａ）下地強靭層
下地強靭層には、耐摩耗被覆層にすぐれた靭性と強度を付与する作用があるが、その平均層厚が０．１μｍ未満では、前記作用に所望の効果が得られず、一方その平均層厚が１０μｍを越えると、切削時に発生する高熱によって熱塑性変形を起し、切刃に偏摩耗が発生し、これが原因で摩耗進行が急激に促進されるようになることから、その平均層厚を０．１〜１０μｍと定めた。
【０００８】
（ｂ）下側硬質層
下側硬質層を構成する（Ｔｉ，Ａｌ）Ｎ層および（Ｔｉ，Ａｌ）ＣＮ層には、耐摩耗被覆層に硬さと靭性を付与せしめ、もってチッピングの発生なく、すぐれた耐摩耗性を上側硬質層との共存において発揮する作用がある。すなわち前記下側硬質層におけるＡｌは高靭性を有するＴｉＮに対して硬さを高め、もって耐摩耗性を向上させるために固溶するものであり、したがって組成式：（Ｔｉ_1-X Ａｌ_X ）Ｎおよび同（Ｔｉ_1-X Ａｌ_X ）Ｃ_1- _ｍＮ_ｍのＸ値が０．３未満では所望の硬さ向上効果が得られず、一方その値が０．７を越えると、耐摩耗被覆層にチッピングが発生し易くなると云う理由によりＸ値を０．３〜０．７（原子比）と定めたものであり、また、（Ｔｉ，Ａｌ）ＣＮ層におけるＣ成分には、さらに硬さを向上させる作用があるので、（Ｔｉ，Ａｌ）ＣＮ層は上記（Ｔｉ，Ａｌ）Ｎ層に比して相対的に高い硬さをもつが、この場合Ｃ成分の割合が０．０１未満、すなわちｍ値が０．９９を越えると所定の硬さ向上効果が得られず、一方Ｃ成分の割合が０．５を越える、すなわちｍ値が０．５未満になると靭性が急激に低下するようになることから、ｍ値を０．５〜０．９９と定めたのである。
また、この場合その平均層厚が０．５μｍ未満では所望のすぐれた耐摩耗性を確保することができず、一方その層厚が１５μｍを越えると、耐摩耗被覆層にチッピングが発生し易くなることから、その平均層厚を０．５〜１５μｍと定めた。
【０００９】
（ｃ）上側硬質層
上側硬質層を構成するＡｌ₂Ｏ₃層は、すぐれた高温硬さと耐熱性を有し、上記の下側硬質層と共存した状態で耐摩耗被覆層の耐摩耗性を一段と向上させる作用があるが、その平均層厚が０．５μｍでは所望のすぐれた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、耐摩耗被覆層にチッピングが発生し易くなることから、その平均層厚を０．５〜１５μｍと定めた。
【００１０】
（ｄ）表面放熱層
表面放熱層には、上記の通り耐摩耗被覆層にすぐれた熱伝導性と熱的安定性を付与せしめ、もって放熱性の一段の向上をもたらす作用があるが、その平均層厚が０．５μｍ未満では前記作用に所望の向上効果が得られず、一方その平均層厚が１５μｍを越えると切刃部に偏摩耗が発生し易くなり、これが摩耗進行を促進するようになることから、その平均層厚を０．５〜１５μｍと定めた。
【００１１】
さらに、上記耐摩耗被覆層の上に、最表面層として、必要に応じてＴｉＮ層を０．１〜２μｍの平均層厚で形成してもよく、これはＴｉＮ層が黄金色の色調を有し、この色調によって被覆超硬エンドミルおよびドリルの使用前と使用後の識別が容易になるという理由からで、この場合その層厚が０．１μｍ未満では前記色調の付与が不十分であり、一方前記色調の付与は２μｍまでの平均層厚で十分である。
【００１２】
【発明の実施の形態】
ついで、この発明の被覆超硬エンドミルまたは被覆超硬ドリル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、平均粒径：５．５μｍを有する中粗粒ＷＣ粉末、同０．８μｍの微粒ＷＣ粉末、同１．３μｍのＴａＣ粉末、同１．２μｍのＮｂＣ粉末、同１．２μｍのＺｒＣ粉末、同２．３μｍのＣｒ₃Ｃ₂粉末、同１．５μｍのＶＣ粉末、同１．０μｍの（Ｔｉ，Ｗ）Ｃ粉末、および同１．８μｍのＣｏ粉末を用意し、これら原料粉末をそれぞれ表１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１に示される組合せで、切刃部の直径×長さがそれぞれ６ｍｍ×１３ｍｍ、１０ｍｍ×２２ｍｍ、および２０ｍｍ×４５ｍｍの寸法をもったエンドミル基体ａ〜ｇをそれぞれ製造した。
【００１３】
ついで、これらのエンドミル基体ａ〜ｇの表面を、アセトン中で超音波洗浄し、乾燥した状態で、図１に例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、一方カソード電極（蒸発源）として、金属Ｔｉ（下地強靭層形成用）、種々の成分組成をもったＴｉ−Ａｌ合金（下側硬質層形成用）、さらに金属Ａｌ（上側硬質層形成用）をそれぞれ装着し、
装置内を排気して１．３×１０^-3Ｐａ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、Ａｒガスを装置内に導入して２．５ＰａのＡｒ雰囲気とし、この状態でエンドミル基体に−８００Ｖの電圧を印加して前記基体表面をＡｒガスボンバート洗浄し、
ついで装置内を１．３×１０^-3Ｐａの真空に保持しながら、ヒーターで装置内を６００〜７００℃の範囲内の所定の温度に加熱した状態で、装置内に反応ガスとしてメタンガス、窒素ガス、またはメタンガスと窒素ガスを導入して２．８Ｐａの反応雰囲気とすると共に、前記基体に印加するバイアス電圧を−１５０Ｖに下げて、前記カソード電極（金属Ｔｉ）とアノード電極との間にアーク放電を発生させ、もって前記基体のそれぞれの表面に、表２に示される目標組成および目標層厚の下地強靭層を形成し、
カソード電極（蒸発源）としてＴｉ−Ａｌ合金を用い、アノード電極との間にアーク放電を発生させ、装置内に反応ガスとして窒素ガス、またはメタンガスと窒素ガスを導入する以外は前記下地強靭層形成条件と同一の条件で、前記下地強靭層の表面に、同じく表２に示される目標組成および目標層厚の（Ｔｉ，Ａｌ）Ｎ層および（Ｔｉ，Ａｌ）ＣＮ層のうちのいずれか、または両方からなる下側硬質層を形成し、
さらにカソード電極（蒸発源）として金属Ａｌを用い、アノード電極との間にアーク放電を発生させ、装置内に反応ガスとして酸素を導入して１．３Ｐａの反応雰囲気とすると共に、前記基体に印加するパルスバイアス電圧を−３００Ｖとする以外は前記下地強靭層形成条件と同一の条件で、前記下側硬質層の表面に、同じく表２に示される目標層厚のＡｌ₂Ｏ₃層からなる上側硬質層を形成することにより、耐摩耗被覆層が以上の下地強靭層、下側硬質層、および上側硬質層からなり、かつ図２（ａ）に概略正面図で、同（ｂ）に切刃部の概略横断面図で示される形状を有する比較被覆超硬エンドミル１〜７をそれぞれ製造した。
【００１４】
さらに、上記の比較被覆超硬エンドミル１〜７の表面に、同じく図１のアークイオンプレーティング装置にて、カソード電極（蒸発源）として、金属Ａｌを装着し、装置内を排気して１．３×１０^-3Ｐａの真空に保持しながら、ヒーターで装置内を６００〜７００℃の範囲内の所定の温度に加熱した状態で、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、装置内に反応ガスとして、窒素ガスを導入して３Ｐａの反応雰囲気とし、かつ基体に印加するパルスバイアス電圧を−２８０Ｖとすることにより、表３に示される目標層厚の表面放熱層を耐摩耗被覆層の構成層として蒸着形成することにより同じく図２に示される形状をもった本発明被覆超硬エンドミル１〜７をそれぞれ製造した。
【００１５】
また、この結果得られた各種の被覆超硬エンドミルについて、これの耐摩耗被覆層の構成層の組成および層厚を、オージェ分光分析装置および走査型電子顕微鏡を用いて測定したところ、表２，３の目標組成および目標層厚と実質的に同じ組成および平均層厚（任意５ヶ所測定の平均値との比較）を示した。
【００１６】
つぎに、上記本発明被覆超硬エンドミル１〜７および比較被覆超硬エンドミル１〜７のうち、本発明被覆超硬エンドミル１〜３および比較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・ＳＣＭ４４０の板材、
切削速度：１６０ｍ／ｍｉｎ．、
溝深さ（切り込み）：３ｍｍ、
テーブル送り：５２０ｍｍ／分、
の条件での合金鋼の乾式高速溝加工試験、本発明被覆超硬エンドミル４，５および比較被覆超硬エンドミル４，５については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＫＤ６１（硬さＨＲＣ５０）の板材、
切削速度：７５ｍ／ｍｉｎ．、
溝深さ（切り込み）：５ｍｍ、
テーブル送り：１５０ｍｍ／分、
の条件での合金鋼の乾式高速溝加工試験、本発明被覆超硬エンドミル６，７および比較被覆超硬エンドミル６，７については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＦＣ３００の板材、
切削速度：１６０ｍ／ｍｉｎ．、
溝深さ（切り込み）：８ｍｍ、
テーブル送り：３００ｍｍ／分、
の条件での鋳鉄の乾式高速溝加工試験をそれぞれ行い、いずれの高速溝加工試験でも外周刃の逃げ面摩耗量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２，３にそれぞれ示した。
【００１７】
【表１】

【００１８】
【表２】

【００１９】
【表３】

【００２０】
（実施例２）
上記の実施例１で製造した直径が８ｍｍ（エンドミル基体ｂ，ｃ形成用）、１３ｍｍ（エンドミル基体ｄ，ｅ形成用）、および２６ｍｍ（エンドミル基体ｇ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（ドリル基体ｂ′，ｃ′）、８ｍｍ×２２ｍｍ（ドリル基体ｄ′，ｅ′）、および１６ｍｍ×４５ｍｍ（ドリル基体ｇ′）の寸法をもったドリル基体ｂ′〜ｅ′およびｇ′をそれぞれ製造した。
【００２１】
ついで、これらのドリル基体ｂ′〜ｅ′およびｇ′の表面に、アセトン中で超音波洗浄し、乾燥した状態で、同じく図１に例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と同じ条件で、表４に示される目標組成および目標層厚の下地強靭層、下側硬質層、および上側硬質層からなる耐摩耗被覆層を蒸着形成することにより、図３（ａ）に概略正面図で、同（ｂ）に溝形成部の概略横断面図で示される形状を有する比較被覆超硬ドリル１〜５をそれぞれ製造した。
【００２２】
さらに、上記の比較被覆超硬ドリル１〜５の表面に、同じくアークイオンプレーティング装置にて、上記実施例１と同一の条件で、表５に示される目標層厚の表面放熱層を耐摩耗被覆層の構成層として蒸着形成することにより、同じく図３に示される形状をもった本発明被覆超硬ドリル１〜５をそれぞれ製造した。
【００２３】
さらに、この結果得られた各種の被覆超硬ドリルについて、同じくこれの耐摩耗被覆層の構成層の組成および層厚を、オージェ分光分析装置および走査型電子顕微鏡を用いて測定したところ、表４，５の目標組成および目標層厚と実質的に同じ組成および平均層厚（任意５ヶ所測定の平均値との比較）を示した。
【００２４】
つぎに、上記本発明被覆超硬ドリル１〜５および比較被覆超硬ドリル１〜５のうち、本発明被覆超硬ドリル１，２および比較被覆超硬ドリル１，２については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ４５Ｃの板材、
回転速度：８２００ｍｉｎ^−１、
送り：１１５０ｍｍ／分、
の条件での炭素鋼の湿式高速穴あけ加工試験、本発明被覆超硬ドリル３，４および比較被覆超硬ドリル３，４については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＳＮＣＭ４３９の板材、
回転速度：４０００ｍｉｎ^−１、
送り：７２０ｍｍ／分、
の条件での合金鋼の湿式高速穴あけ加工試験、本発明被覆超硬ドリル５および比較被覆超硬ドリル５については、
被削材：平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・ＦＣ２５０の板材、
回転速度：１８００ｍｉｎ^−１、
送り：４８０ｍｍ／分、
の条件での鋳鉄の湿式高速穴あけ加工試験、
をそれぞれ行い、いずれの湿式（水溶性切削油使用）高速穴あけ加工試験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４，５にそれぞれ示した。
【００２５】
【表４】

【００２６】
【表５】

【００２７】
【発明の効果】
表２〜５に示される結果から、本発明被覆超硬エンドミル１〜７または本発明被覆超硬ドリル１〜５は、いずれも各種鋼の切削加工を高い発熱を伴う高速で行っても、表面放熱層の発揮するすぐれた熱伝導性および熱的安定性によって耐摩耗被覆層はすぐれた放熱性を発揮し、耐摩耗被覆層自体が過熱されることがなくなることから、同じく構成層である下地強靭層、下側硬質層、および上側硬質層の作用と相俟って、切刃に欠けやチッピングなどの発生なく、すぐれた耐摩耗性を発揮するのに対して、耐摩耗被覆層の構成層として前記表面放熱層の形成がない比較被覆超硬エンドミル１〜７および比較被覆超硬ドリル１〜５においては、いずれも高速切削時に発生する高熱によって耐摩耗被覆層自体の温度が上昇し、このため摩耗進行が著しく促進し、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エンドミルまたは被覆超硬ドリルは、各種の鋼や鋳鉄などの通常の条件での切削加工は勿論のこと、特に高速切削加工においてもすぐれた耐摩耗性を発揮するものであるから、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】アークイオンプレーティング装置の概略説明図である。
【図２】（ａ）は被覆超硬エンドミルの概略正面図、（ｂ）は同切刃部の概略横断面図である。
【図３】（ａ）は被覆超硬ドリルの概略正面図、（ｂ）は同溝形成部の概略横断面図である。[0001]
BACKGROUND OF THE INVENTION
This invention is particularly effective for high-speed cutting of steel with high heat generation, and the wear-resistant coating layer exhibits excellent heat dissipation, which suppresses the progress of wear due to overheating, thereby extending the life of the product by one step. The present invention relates to a surface-coated cemented carbide end mill and drill (hereinafter referred to as a coated carbide end mill or a coated carbide drill).
[0002]
[Prior art]
For cutting tools, such as coated carbide drills or coated carbide miniature drills used for drilling and cutting of various steel and cast iron materials, as well as face machining, grooving, shoulder processing, etc. Solid type coated carbide end mills used are known.
[0003]
Further, an arc ion plating apparatus, which is a kind of physical vapor deposition apparatus shown schematically in FIG. 1, is used on the surface of an end mill base or drill base made of a tungsten carbide (hereinafter referred to as WC) base cemented carbide . In the state where the inside of the apparatus is heated to a temperature of, for example, 700 ° C. by a heater, the Ti, Al alloy having a predetermined composition for forming the anode electrode, the base tough layer, the lower hard layer, and the upper hard layer For the formation, an arc discharge is generated between the cathode electrode (evaporation source) on which metal Al is set, and at the same time, methane gas and / or nitrogen gas or oxygen is introduced into the apparatus as a reaction gas, while the anode electrode and For example, an end mill base or a drill base opposed to the cathode electrode with a predetermined interval is applied with a bias voltage of −120 V, for example. In,
(A) It consists of one single layer or two or more multilayers of Ti carbide layer, nitride layer, and carbonitride layer (hereinafter referred to as TiC layer, TiN layer, and TiCN layer, respectively). And an underlying tough layer having an average layer thickness of 0.1 to 10 μm,
(B) Composition formula: (Ti _1-X Al _X ) N and (Ti _{1 -X)} Al _X ) C _1- _m N _m (However, in atomic ratio, X is 0.3 to 0.7 and m is 0.5 to 0.99 as measured by an Auger spectrometer at the center in the thickness direction) One of a Ti and Al composite nitride layer [hereinafter referred to as (Ti, Al) N] and a Ti and Al composite carbonitride layer [hereinafter referred to as (Ti, Al) CN] A lower hard layer consisting of a single layer, or a multilayer of both, and having an average layer thickness of 0.1 to 15 μm,
(C) an upper hard layer comprising an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer and having an average layer thickness of 0.5 to 15 μm;
Attempts have been made to produce a coated carbide end mill or a coated carbide drill by forming the wear-resistant coating layer composed of (a) to (c) above .
[0004]
[Problems to be solved by the invention]
On the other hand, there is a strong demand for labor-saving and energy-saving and cost reduction for cutting in recent years. Along with this, cutting tends to increase speed in combination with higher performance of cutting machines. In conventional coated carbide end mills or coated carbide drills, there is no problem if this is used for cutting under normal conditions such as steel or cast iron. Due to the high heat generated, the temperature of the wear-resistant coating layer in particular increases, and as a result, the wear of the wear-resistant coating layer is further accelerated, so that the service life is reached in a relatively short time.
[0005]
[Means for Solving the Problems]
In view of the above, the present inventors focused on the above-mentioned conventional coated carbide end mill or coated carbide drill, and conducted research to suppress the temperature rise of the wear-resistant coating layer particularly during high-speed cutting. As a result,
Similarly, the arc ion plating device is used as the surface layer of the wear-resistant coating layer of the above conventional coated carbide end mill or coated carbide drill, metal Al is used as the cathode electrode (evaporation source), and nitrogen gas is introduced as the reaction gas. Then, when an aluminum nitride (hereinafter referred to as AlN) layer is formed, in the resulting wear resistant coating layer, the AlN layer exhibits excellent thermal conductivity and thermal stability, resulting in wear resistance. The heat dissipation of the coating layer is further improved, and even if it is exposed to high heat generated during high-speed cutting, overheating of the wear resistant coating layer itself is remarkably suppressed, and the base tough layer, the lower hard layer, and the upper hard layer are resistant to heat. the wear coating layer excellent toughness and high-temperature hardness, further excellent since it becomes also combine heat resistance, coating carbide end mill or obtained by forming the wear-resistant coating layer Covering carbide drill, even with this in particular accompanying high speed cutting a high heat generation, such as steel or cast iron, exhibit the excellent heat dissipation wear-resistant coating layer, which wear progresses due to overheating of itself suppression As a result, they have obtained research results that they will exhibit even better wear resistance.
[0006]
The present invention has been made based on the above research results. In an arc ion plating apparatus, the surface of an end mill base or a drill base made of a WC-based cemented carbide is used.
(A) One of a TiC layer, a TiN layer, and a TiCN layer formed by using metal Ti as a cathode electrode (evaporation source) and introducing methane gas, nitrogen gas, or methane gas and nitrogen gas as a reaction gas An underlayer tough layer having an average layer thickness of 0.1 to 10 μm, comprising a single layer or a multilayer of two or more of
(B) A composition formula: (Ti _1-X) formed by using a Ti—Al alloy as a cathode electrode (evaporation source) and introducing nitrogen gas or methane gas and nitrogen gas as a reaction gas. Al _X ) N and the same (Ti _1-X Al _X ) When expressed by C _1- _m N _m , X: 0.30 to 0.70, m: 0.5 to 0.99 in terms of atomic ratio, as measured by an Auger spectrometer at the center in the thickness direction. A lower hard layer consisting of either or both of a satisfactory (Ti, Al) N layer and (Ti, Al) CN layer and having an average layer thickness of 0.5 to 15 μm;
(C) an upper hard layer comprising an Al ₂ O ₃ layer formed by using metal Al as a cathode electrode (evaporation source) and introducing oxygen as a reaction gas, and having an average layer thickness of 0.5 to 15 μm;
(D) a surface heat radiation layer comprising an AlN layer formed by using metal Al as a cathode electrode (evaporation source) and introducing nitrogen gas as a reaction gas, and having an average layer thickness of 0.5 to 15 μm;
The coated carbide end mill or the coated carbide drill, which is formed by the wear-resistant coating layer configured as described above in (a) to (d) and exhibits excellent heat dissipation, is characterized by the wear-resistant coating layer.
[0007]
Next, in the coated carbide end mill or the coated carbide drill of the present invention, the base tough layer, the lower hard layer, the upper hard layer, and the surface heat radiation layer constituting the wear resistant coating layer will be described.
(A) Base tough layer The base tough layer has an effect of imparting excellent toughness and strength to the wear-resistant coating layer. However, if the average layer thickness is less than 0.1 μm, the desired effect can be obtained. On the other hand, if the average layer thickness exceeds 10 μm, thermoplastic deformation occurs due to high heat generated during cutting, and uneven wear occurs in the cutting edge, which causes the wear progress to be accelerated rapidly. The average layer thickness was determined to be 0.1 to 10 μm.
[0008]
(B) Lower hard layer The (Ti, Al) N layer and (Ti, Al) CN layer constituting the lower hard layer impart hardness and toughness to the wear-resistant coating layer, so that no chipping occurs. It has the effect of exhibiting excellent wear resistance in coexistence with the upper hard layer. That is, Al in the lower hard layer is a solid solution for increasing the hardness and improving the wear resistance with respect to TiN having high toughness, and therefore the composition formula: (Ti _1-X Al _X ) N and the same (Ti _1-X Al _X ) If the X value of C _1- _m N _m is less than 0.3, the desired hardness improvement effect cannot be obtained. On the other hand, if the value exceeds 0.7, chipping is likely to occur in the wear-resistant coating layer. The X value is determined to be 0.3 to 0.7 (atomic ratio) for the reason, and the C component in the (Ti, Al) CN layer has the effect of further improving the hardness. The Ti, Al) CN layer has a relatively high hardness compared to the (Ti, Al) N layer, but in this case, the proportion of the C component is less than 0.01, that is, the m value exceeds 0.99. On the other hand, if the ratio of the C component exceeds 0.5, that is, if the m value is less than 0.5, the toughness will suddenly decrease, the m value is reduced to 0. .5 to 0.99.
Further, in this case, if the average layer thickness is less than 0.5 μm, the desired excellent wear resistance cannot be ensured. On the other hand, if the layer thickness exceeds 15 μm, chipping tends to occur in the wear-resistant coating layer. Therefore, the average layer thickness was determined to be 0.5 to 15 μm.
[0009]
(C) Upper hard layer The Al ₂ O ₃ layer constituting the upper hard layer has excellent high-temperature hardness and heat resistance, and the wear resistance of the wear-resistant coating layer in the state of coexisting with the lower hard layer. Although there is an effect of further improving, if the average layer thickness is 0.5 μm, the desired excellent wear resistance cannot be secured, while if the average layer thickness exceeds 15 μm, the wear-resistant coating layer is chipped. Since it becomes easy to generate | occur | produce, the average layer thickness was set to 0.5-15 micrometers.
[0010]
(D) Surface heat dissipation layer The surface heat dissipation layer has the effect of imparting excellent thermal conductivity and thermal stability to the wear-resistant coating layer as described above, thereby providing a further improvement in heat dissipation. If the layer thickness is less than 0.5 μm, a desired improvement effect cannot be obtained in the above-mentioned action. On the other hand, if the average layer thickness exceeds 15 μm, uneven wear tends to occur at the cutting edge, which promotes the progress of wear. Therefore, the average layer thickness was set to 0.5 to 15 μm.
[0011]
Furthermore, a TiN layer having an average layer thickness of 0.1 to 2 μm may be formed on the wear-resistant coating layer as an outermost surface layer, if necessary, and the TiN layer has a golden color tone. In this case, the color tone is insufficient if the layer thickness is less than 0.1 μm, because the color tone facilitates the discrimination before and after using the coated carbide end mill and drill. For the color tone, an average layer thickness of up to 2 μm is sufficient.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, the coated carbide end mill or the coated carbide drill of the present invention will be described in detail with reference to examples.
Example 1
As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, ZrC of 1.2 μm Prepare a powder, 2.3 μm Cr ₃ C ₂ powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C powder, and 1.8 μm Co powder. Each compounded in the composition shown in Table 1, added with wax, ball mill mixed in acetone for 24 hours, dried under reduced pressure, then pressed into various compacts of a predetermined shape at a pressure of 100 MPa. The green compact is heated to a predetermined temperature in the range of 1370 to 1470 ° C. at a rate of temperature increase of 7 ° C./min in a 6 Pa vacuum atmosphere, held at this temperature for 1 hour, and then fired under furnace cooling conditions. Finally, the diameters are 8mm, 13mm, and 26 m of three types of substrate-forming round bar sintered bodies of m, and further from the above-mentioned three types of round bar sintered bodies by grinding, in the combinations shown in Table 1, the diameter of the cutting edge portion x length End mill substrates a to g having dimensions of 6 mm × 13 mm, 10 mm × 22 mm, and 20 mm × 45 mm, respectively, were manufactured.
[0013]
Next, the surfaces of these end mill substrates a to g are ultrasonically cleaned in acetone and dried, and then charged into a normal arc ion plating apparatus illustrated in FIG. ) As metal Ti (for forming the base tough layer), Ti-Al alloys having various component compositions (for forming the lower hard layer), and further mounting metal Al (for forming the upper hard layer),
While the inside of the apparatus was evacuated and kept at a vacuum of 1.3 × 10 ⁻³ Pa, the inside of the apparatus was heated to 500 ° C. with a heater, and then Ar gas was introduced into the apparatus to form an Ar atmosphere of 2.5 Pa. In this state, a voltage of −800 V was applied to the end mill substrate to clean the surface of the substrate with Ar gas bombardment,
Then, while maintaining the inside of the apparatus at a vacuum of 1.3 × 10 ⁻³ Pa, the apparatus is heated to a predetermined temperature within a range of 600 to 700 ° C. with a heater, and methane gas and nitrogen are used as reaction gases in the apparatus. Gas or methane gas and nitrogen gas are introduced to form a reaction atmosphere of 2.8 Pa, and the bias voltage applied to the substrate is lowered to −150 V, and an arc is formed between the cathode electrode (metal Ti) and the anode electrode. An electric discharge is generated, and thereby a base tough layer having a target composition and a target layer thickness shown in Table 2 is formed on each surface of the substrate,
Ti—Al alloy is used as the cathode electrode (evaporation source), arc discharge is generated between the anode electrode and nitrogen gas or methane gas and nitrogen gas are introduced into the apparatus as reactive gas, and the above-mentioned tough layer is formed. On the surface of the base tough layer under the same conditions as those described above, either the (Ti, Al) N layer and the (Ti, Al) CN layer having the target composition and target layer thickness also shown in Table 2, or Form a lower hard layer consisting of both,
Further, metal Al is used as a cathode electrode (evaporation source), arc discharge is generated between the anode electrode and oxygen as a reaction gas is introduced into the apparatus to create a reaction atmosphere of 1.3 Pa and applied to the substrate. Except that the pulse bias voltage to be -300 V is the same as that of the base tough layer, and the upper hard layer is formed of an Al ₂ O ₃ layer having the target layer thickness shown in Table 2 on the surface of the lower hard layer. By forming the hard layer, the wear-resistant coating layer is composed of the above-mentioned base tough layer, lower hard layer, and upper hard layer, and FIG. 2 (a) is a schematic front view and FIG. Comparative coated carbide end mills 1 to 7 having the shapes shown in the schematic cross-sectional views of the parts were produced.
[0014]
Further, on the surfaces of the comparative coated carbide end mills 1 to 7, metal arc was attached as a cathode electrode (evaporation source) using the arc ion plating apparatus of FIG. While maintaining a vacuum of 3 × 10 ⁻³ Pa, an arc discharge is generated between the cathode electrode and the anode electrode while the apparatus is heated to a predetermined temperature within a range of 600 to 700 ° C. with a heater. The surface heat radiation layer having the target layer thickness shown in Table 3 can be resisted by introducing nitrogen gas as a reaction gas into the apparatus to make a reaction atmosphere of 3 Pa and setting the pulse bias voltage applied to the substrate to −280 V. The coated carbide end mills 1 to 7 of the present invention each having the shape shown in FIG. 2 were produced by vapor deposition as a constituent layer of the wear coating layer.
[0015]
Further, for the various coated carbide end mills obtained as a result, the composition and layer thickness of the wear-resistant coating layer were measured using an Auger spectroscopic analyzer and a scanning electron microscope. The target composition and target layer thickness of 3 were substantially the same as the target composition and target layer thickness, and an average layer thickness (comparison with an average value measured at five arbitrary positions) was shown.
[0016]
Next, of the present invention coated carbide end mills 1-7 and comparative coated carbide end mills 1-7, the present invention coated carbide end mills 1-3 and comparative coated carbide end mills 1-3 are as follows:
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SCM440 plate material,
Cutting speed: 160 m / min. ,
Groove depth (cut): 3 mm,
Table feed: 520 mm / min,
For the dry high-speed grooving test of alloy steel under the conditions of the present invention, the coated carbide end mills 4 and 5 and the comparative coated carbide end mills 4 and 5 of the present invention,
Work material: Plane size: 100 mm × 250 mm, thickness: 50 mm JIS / SKD61 (hardness HRC50) plate material,
Cutting speed: 75 m / min. ,
Groove depth (cut): 5 mm,
Table feed: 150 mm / min,
For the dry high speed grooving test of alloy steel under the conditions of the present invention, the coated carbide end mills 6 and 7 and the comparative coated carbide end mills 6 and 7 of the present invention,
Work material: Plane dimensions: 100 mm x 250 mm, thickness: 50 mm JIS / FC300 plate material,
Cutting speed: 160 m / min. ,
Groove depth (cut): 8 mm,
Table feed: 300mm / min,
In each high-speed grooving test, the cutting groove length was measured until the flank wear amount of the outer peripheral blade reached 0.1 mm, which is a guide for the service life. . The measurement results are shown in Tables 2 and 3, respectively.
[0017]
[Table 1]

[0018]
[Table 2]

[0019]
[Table 3]

[0020]
(Example 2)
Three types of round bar sintered bodies having diameters of 8 mm (for forming end mill bases b and c), 13 mm (for forming end mill bases d and e), and 26 mm (for forming end mill bases g) manufactured in Example 1 above. From these three types of round bar sintered bodies, the diameter x length of the groove forming portion is 4 mm × 13 mm (drill base b ′, c ′) and 8 mm × 22 mm (drill base d ′) by grinding. , E '), and drill bases b'-e' and g 'having dimensions of 16 mm x 45 mm (drill base g'), respectively.
[0021]
Next, the surfaces of these drill bases b ′ to e ′ and g ′ are ultrasonically cleaned in acetone and dried, and then charged into a normal arc ion plating apparatus also illustrated in FIG. Under the same conditions as in Example 1 above, the wear-resistant coating layer composed of the base tough layer, the lower hard layer, and the upper hard layer having the target composition and target layer thickness shown in Table 4 is formed by vapor deposition. Comparative coated carbide drills 1 to 5 having the shape shown in the schematic front view in a) and in the schematic cross-sectional view of the groove forming part in (b) were manufactured, respectively.
[0022]
Furthermore, on the surfaces of the comparative coated carbide drills 1 to 5, the surface heat radiation layer having the target layer thickness shown in Table 5 was subjected to wear resistance using the same arc ion plating apparatus under the same conditions as in Example 1. The coated carbide drills 1 to 5 of the present invention each having the shape shown in FIG. 3 were produced by vapor deposition as a constituent layer of the coating layer.
[0023]
Further, for the various coated carbide drills obtained as a result, the composition and layer thickness of the wear-resistant coating layer were measured using an Auger spectroscopic analyzer and a scanning electron microscope. , 5 showed a composition and average layer thickness substantially the same as the target composition and target layer thickness (comparison with the average value measured at five arbitrary points).
[0024]
Next, of the present invention coated carbide drills 1 to 5 and the comparative coated carbide drills 1 to 5, the present invention coated carbide drills 1 and 2 and the comparative coated carbide drills 1 and 2,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / S45C plate,
Rotational speed: 8200 min ⁻¹ ,
Feed: 1150mm / min,
For the wet high speed drilling test of carbon steel under the conditions of the present invention, the present invention coated carbide drills 3 and 4 and the comparative coated carbide drills 3 and 4,
Work material: Plane size: 100 mm × 250 mm, thickness: 50 mm JIS / SNCM439 plate material,
Rotational speed: 4000 min ⁻¹ ,
Feed: 720mm / min,
About the wet high speed drilling test of alloy steel under the conditions of the present invention, the coated carbide drill 5 of the present invention and the comparative coated carbide drill 5,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / FC250 plate material,
Rotational speed: 1800 min ⁻¹ ,
Feed: 480mm / min,
Wet high-speed drilling test of cast iron under the conditions of
In each wet (using water-soluble cutting oil) high-speed drilling test, the number of drilling processes until the flank wear width of the cutting edge surface reached 0.3 mm was measured. The measurement results are shown in Tables 4 and 5, respectively.
[0025]
[Table 4]

[0026]
[Table 5]

[0027]
【The invention's effect】
From the results shown in Tables 2 to 5, the coated carbide end mills 1 to 7 or the coated carbide drills 1 to 5 of the present invention can be used even when cutting various steels at high speed with high heat generation. The wear resistant coating layer exhibits excellent heat dissipation due to the excellent thermal conductivity and thermal stability exhibited by the heat dissipation layer, and the wear resistant coating layer itself is not overheated. Combined with the action of the tough layer, lower hard layer, and upper hard layer, the cutting edge exhibits excellent wear resistance without chipping or chipping. In the comparative coated carbide end mills 1 to 7 and comparative coated carbide drills 1 to 5 in which the surface heat radiation layer is not formed as a layer, the temperature of the wear-resistant coating layer itself is increased by high heat generated during high-speed cutting, For this reason, wear progress is significant. Ku promoted, it is apparent that lead to a relatively short time service life.
As described above, the coated carbide end mill or the coated carbide drill of the present invention has excellent wear resistance not only in cutting processing under normal conditions such as various steels and cast iron, but also in high-speed cutting processing. Because it demonstrates it, it can fully satisfy the labor saving and energy saving of cutting, and further cost reduction.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of an arc ion plating apparatus.
2A is a schematic front view of a coated carbide end mill, and FIG. 2B is a schematic cross-sectional view of the cutting edge portion.
3A is a schematic front view of a coated carbide drill, and FIG. 3B is a schematic cross-sectional view of the groove forming portion.

Claims

In the arc ion plating device, on the surface of the end mill base composed of tungsten carbide base cemented carbide,
(A) Ti carbide layer, nitride layer, and carbonitride layer formed using metal Ti as a cathode electrode (evaporation source) and introducing methane gas, nitrogen gas, or methane gas and nitrogen gas as a reaction gas An underlayer tough layer having an average layer thickness of 0.1 to 10 μm,
(B) A composition formula: (Ti _1-X) formed by using a Ti—Al alloy as a cathode electrode (evaporation source) and introducing nitrogen gas or methane gas and nitrogen gas as a reaction gas. Al _X ) N and the same (Ti _1-X Al _X ) When expressed in C _{_1-m} N _m, as measured by Auger spectroscopy apparatus in the thickness direction central portion, in atomic ratio, X is from 0.30 to 0.70, m is a 0.5 to 0.99 A lower hard layer comprising any one or both of a satisfactory Ti and Al composite nitride layer and a Ti and Al composite carbonitride layer, and having an average layer thickness of 0.5 to 15 μm;
(C) an upper hard layer comprising an aluminum oxide layer formed by using metal Al as a cathode electrode (evaporation source) and introducing oxygen as a reaction gas, and having an average layer thickness of 0.5 to 15 μm;
(D) a surface heat radiation layer comprising an aluminum nitride layer formed by using metal Al as a cathode electrode (evaporation source) and introducing nitrogen gas as a reaction gas, and having an average layer thickness of 0.5 to 15 μm;
An end mill made of a surface-coated cemented carbide alloy, which is formed by the above-described wear-resistant coating layer (a) to (d) and exhibits excellent heat dissipation.

In the arc ion plating device, on the surface of the drill base made of tungsten carbide based cemented carbide,
(A) Ti carbide layer, nitride layer, and carbonitride layer formed using metal Ti as a cathode electrode (evaporation source) and introducing methane gas, nitrogen gas, or methane gas and nitrogen gas as a reaction gas An underlayer tough layer having an average layer thickness of 0.1 to 10 μm,
(B) A composition formula: (Ti _1-X) formed by using a Ti—Al alloy as a cathode electrode (evaporation source) and introducing nitrogen gas or methane gas and nitrogen gas as a reaction gas. Al _X ) N and the same (Ti _1-X Al _X ) When expressed in C _{_1-m} N _m, as measured by Auger spectroscopy apparatus in the thickness direction central portion, in atomic ratio, X is from 0.30 to 0.70, m is a 0.5 to 0.99 A lower hard layer comprising any one or both of a satisfactory Ti and Al composite nitride layer and a Ti and Al composite carbonitride layer, and having an average layer thickness of 0.5 to 15 μm;
(C) an upper hard layer comprising an aluminum oxide layer formed by using metal Al as a cathode electrode (evaporation source) and introducing oxygen as a reaction gas, and having an average layer thickness of 0.5 to 15 μm;
(D) a surface heat radiation layer comprising an aluminum nitride layer formed by using metal Al as a cathode electrode (evaporation source) and introducing nitrogen gas as a reaction gas, and having an average layer thickness of 0.5 to 15 μm;
A surface-coated cemented carbide drill, which is formed by the above-described wear-resistant coating layer (a) to (d) and exhibits excellent heat dissipation.