【０００１】
【発明が属する技術分野】
本発明は、金型、機械部品等の切削加工に使用される粗加工用エンドミルの表面被覆材として有用な硬質皮膜を被覆することにより、優れた耐摩耗性を発揮する被覆粗加工用エンドミルに関する。
【０００２】
【従来の技術】
金型や機械構造部品等の粗切削加工に使用される粗加工用エンドミルとして、外周刃先部に連続して波状に形成された波状切刃を有するエンドミルや、切屑を分断するためニックが設けられた粗加工用エンドミルが使用されている。この波状及びニックを設けたエンドミルは、波状／ニックのないエンドミルと比べ、切削加工時の切削応力が分散されるため、工具径に対する切込み量を大きくとることができ、荒削り加工に適する。このように粗加工用エンドミルは、通常の波状切刃を有しないエンドミルによる切削加工よりも大きな衝撃力が刃先に加わると同時に、単位時間あたりの切屑排出量が多くなり、切屑が排出される波状切刃近傍の逃げ面側及びすくい面側は極めて高温にさらされる。そこで、粗加工用エンドミルの波状切刃近傍の工具摩耗を抑制するために、皮膜硬度並びに耐高温酸化特性の改善がなされた（ＴｉＡｌ）Ｎ皮膜を被覆した粗加工用エンドミルが用いられている。しかしながら、近年の切削加工の分野では、粗切削加工の長寿命化並びにコスト低減のため、高能率化を目的とした高速加工及び被加工物の高硬度化等が求められており、（ＴｉＡｌ）Ｎ皮膜を被覆した粗加工用エンドミルでは、これらの要求に対して満足される切削寿命は得られてはいない。そこで、（ＴｉＡｌ）Ｎ皮膜よりも、耐高温酸化特性に優れた硬質皮膜材として、ＡｌＣｒ系皮膜が下記に示す特許文献１から３に開示されている。
【特許文献１】特許第３０２７５０２号公報（第６頁、図１）
【特許文献２】特許第３０３９３８１号公報（第４頁、図１）
【特許文献３】特開平２００２−１６０１２９号公報（第３頁、図１）
【０００３】
特許文献１は金属成分としてＡｌＣｒとＣ、Ｎ、Ｏの１種より選択されるＡｌＣｒ系硬質膜において、高硬度を有する非晶質膜に関する事例が開示されている。しかしこの非晶質膜の硬度は最大でもヌープ硬さ２１ＧＰａ程度であり、粗加工用エンドミルとして、耐摩耗効果は改善されず、密着性に関しても十分ではない。特許文献２及び特許文献３に開示されている硬質皮膜はＡｌＣｒの窒化物であり、約１０００℃の耐高温酸化特性を有しているが、１０００℃以上の耐酸化特性の検討は行われていない。また硬度はビッカ−ス硬さ２１ＧＰａ程度で硬度の改善が不十分であり耐摩耗性に乏しい。
【０００４】
【発明が解決しようとする課題】
本願発明は、上記の問題点を改善し、（ＡｌＣｒ）Ｎ系皮膜の欠点である硬度を高めることにより耐摩耗性を著しく改善し、その結果優れた工具寿命を発揮する被覆粗加工用エンドミルを提供することを目的とする。
【０００５】
【課題を解決するために手段】
本発明は、被覆粗加工用エンドミルにおいて、該被覆はアーク放電式イオンプレーティング法により被覆された硬質皮膜であり、該硬質皮膜は、（ＡｌｘＣｒ１−ｘ−ｙＳｉｙ）（Ｎ１−α−β−γＢαＣβＯγ）、但し、ｘ、ｙ、α、β、γは夫々原子比率を示し、０．４５＜ｘ＜０．８５、０≦ｙ＜０．３５、０．５０≦ｘ＋ｙ＜１．０、０≦α＜０．１５、０≦β＜０．６５、０＜γ＜０．６５、０＜α＋β＋γ≦１．０で示される少なくとも１層以上からなり、θ−２θ法によるＸ線回折において測定される岩塩構造型の（２００）面に回折強度を有し、その回折ピークの２θの半価幅が、０．５度以上、２．０度以下であり、Ｘ線光電子分光分析における５２５ｅＶから５３５ｅＶの範囲に、少なくともＡｌ、Ｃｒ及び／又はＳｉと酸素との結合エネルギーを有し、該粗加工用エンドミルの被覆基体は粉末高速度鋼からなり、ＶとＣｏの和が重量％で１０≦（Ｖ＋Ｃｏ）≦２０、Ｃｒが重量％で２≦Ｃｒ≦６であることを特徴とする被覆粗加工用エンドミルである。上記構成を採用することにより、基体と硬質皮膜との密着性に特に優れ、高硬度化することが可能となり、その結果、優れた耐摩耗性を発揮する本発明の被覆粗加工用エンドミルを完成させた。
【０００６】
本発明硬質皮膜は、θ−２θ法によるＸ線回折で測定される岩塩構造型の（１１１）面の回折強度をＩ（１１１）、（２００）面の回折強度をＩ（２００）とした時、０．３＜Ｉ（２００）／Ｉ（１１１）＜１２である場合、硬質皮膜内に残留する圧縮応力が低減され、基体との密着性に優れるとともに、皮膜硬度並びに耐酸化性改善への寄与が大きい。また、ナノインデンテーションによる硬度測定法により接触深さと最大荷重時の最大変位量が求められる（Ｗ． Ｃ． Ｏｌｉｖｅｒ ａｎｄ Ｇ． Ｍ． Ｐｈａｒｒ： Ｊ． Ｍａｔｅｒ． Ｒｅｓ．， Ｖｏｌ．７， Ｎｏ．６，Ｊｕｎｅ、１９９２、１５６４−１５８３）。この数値を用いて、
Ｅ＝１００−｛（接触深さ）／（最大荷重時の最大変位量）｝
の数式で、弾性回復率Ｅを定義し、２８％≦Ｅ≦４０％とすることにより、耐摩耗性と密着性のバランスが最適となる。更に、該硬質皮膜の最表面から深さ方向に５００ｎｍ以内の深さ領域で酸素濃度が最大となる場合、耐高温酸化特性並びに耐摩耗特性改善に極めて有効である。また、本願発明の硬質皮膜は、硬質皮膜表面の凸部を機械的処理により平滑にすると、表面の摩擦係数が低減し、これによって切屑排出性が改善される。本発明の被覆粗加工用エンドミルは、波状切刃を有した被覆粗加工用エンドミルで有ることが望ましく、該被覆基体は粉末法により作成された高速度鋼、且つ基体の硬さがＨＲＣ６４以上、ＨＲＣ７１未満であることが特に好ましい。
【０００７】
【発明の実施の形態】
本発明の硬質皮膜を構成する金属元素の組成は、（ＡｌｘＣｒ１−ｘ−ｙＳｉｙ）において、ｘが０．４５＜ｘ＜０．８５、ｙが０≦ｙ＜０．３５、０．５０≦ｘ＋ｙ＜１．０を満足する必要がある。ｘの値が０．４５以下、またｘ＋ｙの値が０．５未満の場合では、皮膜硬度並びに耐高温酸化特性の改善効果が十分ではなく、ｘの値が０．８５以上またはｘ＋ｙの値が１の場合、皮膜硬度の著しい低下を招き耐摩耗性に劣る。またｙの値が０．３５以上では、硬質皮膜内に残留する圧縮応力が過大になり、被覆直後に自己破壊を誘発するなどの基体への密着強度を著しく低下させる場合がある。非金属元素の組成は、（Ｎ１−α−β−γＢαＣβＯγ）において、αは０．１５以上では皮膜が脆化し、好ましいαの上限値は０．０７である。硼素の添加は被加工物との耐溶着性と高温環境下での摩擦係数を低減し、潤滑性を向上させる効果がある。βは０．６５以上で皮膜が著しく脆化する。炭素の含有量の上限値は、炭素を含有する層厚に依存する。炭素を含有する層厚が０．５μｍ未満であれば、βの上限値は０．５である。炭素の添加は硬質皮膜の硬度を高めると同時に、摩擦係数を低減し、潤滑性を向上させる効果がある。γは０を超えて大きく、０．６５未満にすることが必要である。γが０の場合、耐高温酸化特性並びに皮膜硬度が充分ではなく耐摩耗性に乏しい。０．６５以上でも皮膜硬度が低下する。好ましいγの値は、酸素を含有する層厚に依存するが、０．５μｍ未満であれば、γの上限値は０．３である。酸素の添加は、硬質皮膜内に残留する圧縮応力を低減し、基体と皮膜との密着性を向上させる作用に加え、皮膜が緻密化することによる高硬度化と酸素の拡散経路である基体と垂直方向の結晶粒界を減少させることより、耐高温酸化性の改善に効果的である。更に、金属元素のＡｌ、Ｃｒ、Ｓｉに対する非金属元素のＮ、Ｂ、Ｃ、Ｏの比は、化学量論的に（Ｎ、Ｂ、Ｃ、Ｏ）／（Ａｌ、Ｃｒ、Ｓｉ）＞１．０がより好ましい。
【０００８】
本発明の硬質皮膜はθ−２θ法によるＸ線回折において測定される岩塩構造型の（２００）面に回折強度を有し、その回折ピークの２θの半価幅が、０．５度以上、２．０度以下とした。その理由は、０．５未満の場合は結晶粒が粗大化し、皮膜硬度並びに高温酸化特性が充分ではなく、耐摩耗性に乏しく、２．０を超えると皮膜が脆化し、基体密着強度を著しく劣化させるためである。
【０００９】
硬質皮膜はＸ線光電子分光分析にて、５２５ｅＶから５３５ｅＶの範囲に少なくともＡｌ、Ｃｒ及び／又はＳｉと酸素との結合エネルギーを有することが必要である。これは、これら金属元素が酸素との結合を有することにより、皮膜が緻密化し高硬度化され、さらに酸化雰囲気において酸素の拡散経路となる基体に対して垂直方向の結晶粒界が減少し、酸素の内向拡散を抑制する機能を有することによるものである。本発明皮膜の特徴である、Ｃｒ、Ａｌ及び／又はＳｉと酸素との結合状態を形成するには、最適な被覆条件と一定以上の酸素を硬質皮膜内に含有させることが必要である。
【００１０】
被覆粗加工用エンドミルの被覆基体は、粉末高速度鋼からなり、ＶとＣｏの和が重量％で１０≦（Ｖ＋Ｃｏ）≦２０、Ｃｒが重量％で２≦Ｃｒ≦６である。（Ｖ＋Ｃｏ）の値が重量％で２０を超える場合、切れ刃のチッピングが増加する傾向にあり、（Ｖ＋Ｃｏ）の値が重量％で１０未満の場合、耐摩耗性が十分ではない。また、（Ｖ＋Ｃｏ）が上記範囲内を満足してしてもＣｒ含有量が重量％で２未満となる場合、耐摩耗性が十分ではなく、重量％が６を超える場合、切刃のチッピングが増加する傾向にある。これらの構成により、被覆粗加工用エンドミルによる粗切削加工の高能率並びに長寿命化を達成することが可能となる。
【００１１】
被覆粗加工用エンドミルにおいて、該硬質皮膜のθ−２θ法によるＸ線回折で測定される岩塩構造型の（１１１）面の回折強度をＩ（１１１）、（２００）面の回折強度をＩ（２００）とした時、０．３＜Ｉ（２００）／Ｉ（１１１）＜１２とすることが好ましい。皮膜の密着性は残留圧縮応力に強く依存し、この残留圧縮応力は被覆条件であるイオンエネルギーに強く依存している。即ち、イオンエネルギーが低い条件下では皮膜の残留圧縮応力は低い結果となる。逆に、イオンエネルギーが高い条件下では皮膜の残留圧縮応力は高い結果となる。ここで、イオンエネルギーを決定する要素は、具体的には被覆条件であるバイアス電圧、反応ガス圧力であり、これによって制御することができる。本発明は、残留圧縮応力が高い場合、Ｘ線回折において皮膜は（１１１）面に強く配向する傾向を示し、皮膜の硬度も、この高い残留圧縮応力の影響を受けて高硬度とする事が可能となる。一方、皮膜の密着性に着目すると、硬質皮膜内の残留圧縮応力を高くすると、皮膜の高硬度化を達成できるが、基体と皮膜界面近傍において、せん断応力が増大する方向に作用するため、密着性を損なうこととなり、好ましくない。従って、基体と皮膜との密着性及び皮膜硬度とのバランスを最適に制御することが重要となる。本発明では、０．３＜Ｉ（２００）／Ｉ（１１１）＜１２とすることにより、両者のバランスを最適に制御することを可能にした。
【００１２】
ナノインデンテーション硬度測定法によるＥは、２８％≦Ｅ≦４０％であり、皮膜の被覆条件であるバイアス電圧、反応ガス圧やその分圧比、成膜時の基体温度を最適に制御することにより達成でき好ましい。Ｅが４０％を超える場合、硬質皮膜内に残留圧縮応力が高くなり過ぎて靭性に乏しくなり密着性を劣化させる場合がある。２８％未満となる場合は強度不足による異常摩耗等により耐摩耗性が十分でない場合が確認された。さらに好ましいＥの値は３０％〜３５％である。
【００１３】
更に、該硬質皮膜の最表面から深さ方向に５００ｎｍ以内の深さ領域で酸素濃度が最大となる場合、特に切削寿命に優れ好ましい。切削過程における硬質皮膜の酸化は硬質皮膜最表面からの酸素の拡散が支配的である。従って、硬質皮膜表面を酸素リッチにすることにより、結晶を緻密化し酸素の拡散経路となる基体と垂直方向成分の結晶粒界を減少させることができ、より耐高温酸化特性に優れ切削寿命が向上する。また、硬質皮膜最表面を酸素リッチにすることにより、切り屑流れを助長する効果も確認され、潤滑特性を改善することも可能となり好ましい。
【００１４】
本発明の皮膜を被覆し、被覆基体表面の研磨面や研削面に沿った硬質皮膜表面の凸部や、被覆中に発生したマクロ粒子等の付着により凸部が形成される場合があるため、その凸部を機械的処理により平滑にすることにより、切屑除去効果に更に優れ望ましい。更に、被覆後に切刃エッジに機械的処理を施すことにより、なじみ効果も確認され、耐欠損、耐チッピング特性を改善することができ、より好ましい被覆粗加工用エンドミルを得ることができる。
【００１５】
被覆粗加工用エンドミルは、波状切刃を有した被覆粗加工用エンドミルであり、また該被覆基体は粉末法により作成された高速度鋼からなり、且つ基体の硬さがＨＲＣ６４以上、ＨＲＣ７１未満であることが更に望ましい。波状切刃を採用することにより、切削抵抗による発熱と本発明皮膜の耐熱温度とのバランスが最適となり、更に工具寿命を延長することが可能となる。そのときの被覆基体としては、粉末高速度鋼を使用することにより、過酷な粗加工においても、耐摩耗性に優れ、工具折損、切刃チッピングを抑制することが可能であり好ましい。母材がＨＲＣ６４未満となる場合、過酷な切削環境下において波状切刃の山部が逃げ面側へ塑性変形を伴った摩耗進行も確認され、刃先強度が十分ではなく好ましくない。また、ＨＲＣ７１以上の場合は、波状切刃の山部がチッピングや欠けを生じる場合があり、好ましくない。
【００１６】
本発明である該硬質皮膜は、アークイオンプレーティング法による被覆により、基体との密着性に特に優れ、緻密で耐高温酸化特性、高硬度を有する極めて長寿命を有する被覆粗加工用エンドミルが得られる。
【００１７】
該硬質皮膜の結晶粒のアスペクト比について、本発明の皮膜破断面の膜厚Ｔについて、膜厚Ｔの２５％から５０％の厚みであるＴ１に相当する上下膜厚方向の上端位置と下端位置とを求める。この時、上端位置と下端位置は、Ｔ／２に相当する基準位置より上下膜厚方向に略均等となる様に割り振る。各上下端位置における水平方向の上端側粒径Ｋと下端側粒径Ｌを求める。そこで、アスペクト比をＴ１／（（Ｋ＋Ｌ）／２）とすると、柱状結晶構造からなる該硬質皮膜の結晶粒のアスペクト比が、０．２から１２である。アスペクト比が１２を超えて大きくなると、結晶粒が膜厚方向に細長くなり、皮膜の靭性が低下し好ましくない。０．２未満では粒状結晶が増加する傾向となり、皮膜硬度が低下し好ましくない。更に、該硬質皮膜の残留圧縮応力が、０．５ＧＰａ以上、４．０ＧＰａ以下であることが、硬質皮膜に靭性を持たせ、皮膜硬度と基体密着性とのバランスに適した範囲となり、性能の改善に効果的である。
【００１８】
更に、本発明の硬質皮膜において金属成分の１０原子％未満を周期律表の４ａ、５ａ、６ａ族の金属成分の少なくとも１種以上で置き換えた場合、また本発明に関わる硬質皮膜を１層以上含有する複層構造においても、本発明である被覆粗加工用エンドミルの特性を補完することが可能となり好ましく、また、基体との密着性を更に改善する目的等で、最下層にＴｉＮ系皮膜、（ＴｉＡｌ）Ｎ系皮膜等を用いることも本発明の技術的範囲に含まれるものである。以下、実施例に基づき、本発明を具体的に説明する。
【００１９】
【実施例】
（実施例１）
成膜には酸素を３２００ｐｐｍ含有した粉末法により作成した合金ターゲットを用いた。硬質皮膜内への炭素、酸素、硼素の添加には、反応ガスであるＮ２ガス、ＣＨ４ガス、Ｃ２Ｈ２ガス、Ａｒガス、Ｏ２ガス、Ｂ３Ｎ３Ｈ６ガスから目的の皮膜が得られるものを１種以上、もしくはその組合せによるガスを選択し、真空装置内へ導入した。各反応ガスを真空装置内に導入後、全圧を１２Ｐａ、負バイアス電圧を−１６０Ｖ／正バイアス電圧を＋４０Ｖのパルスバイアス電圧を用い、そのときの周波数を２０ｋＨｚ、振幅をマイナス側に８０％で行った。被覆温度は４５０℃、膜厚を約３．５μｍとし、（Ａｌ０．６５Ｃｒ０．３５）（Ｎ０．８０Ｃ０．０８Ｏ０．１０Ｂ０．０２）からなる硬質皮膜を被覆し、本発明例１とした。被覆条件は上記被覆条件に限定されるものではない。皮膜組成は、電子プローブＸ線マイクロアナリシス及びオージェ電子分光法により決定した。硬質皮膜内の酸素との結合状態を解析するためのＸ線光電子分光分析は、ＰＨＩ社製１６００Ｓ型Ｘ線光電子分光分析装置を用い、Ｘ線源はＭｇＫαを用い４００Ｗとし、分析領域を直径０．４ｍｍの円内部を分析した。十分に脱脂洗浄した後、真空装置内で５分間Ａｒイオンガンを用いて表面をエッチングした後、ワイドスペクトルを測定し、更に３０秒間エッチングした後、ナロースペクトルを測定した。ＡｒイオンガンによるエッチングレートはＳｉＯ２換算で１．９ｎｍ／分であった。本発明例１のＸ線光電子分光分析結果を図１に示す。図１は結合エネルギーが５３０ｅＶ近傍のナロースペクトル示し、Ｃｒ−Ｏ及びＡｌ−Ｏの結合の存在を示す。図２はＣｒ−Ｎ及びＣｒ−Ｏの結合の存在を示す。図３はＡｌ−Ｎ及びＡｌ−Ｏの結合の存在を示す。図４は、本発明例１のθ−２θ法によるＸ線回折結果を示す。
【００２０】
（実施例２）
実施例１と同様に、（ＡｌｘＣｒ１−ｘ−ｙＳｉｙ）（Ｎ０．９５Ｏ０．０５）を成膜し、比較例２、ｘ＝０．２０、ｙ＝０、比較例３、ｘ＝０．３０、ｙ＝０、本発明例４、ｘ＝０．５０、ｙ＝０、本発明例５、ｘ＝０．６０、ｙ＝０、本発明例６、ｘ＝０．７０、ｙ＝０、本発明例７、ｘ＝０．８０、ｙ＝０及び（ＡｌｘＣｒ１−ｘ）Ｎ系の比較例８、ｘ＝９０、ｙ＝０、従来例９、ｘ＝０．２０、従来例１０、ｘ＝０．５０、従来例１１、ｘ＝０．７０、を製作し、ナノインデンテーション法による押込硬さを測定した。試験機は微小押込み硬さ試験機を用い、圧子はダイヤモンド製の対稜角１１５度の三角錐圧子を用い、最大荷重を４９ｍＮ、荷重負荷ステップ４．９ｍＮ／ｓｅｃ、最大荷重時の保持時間は１秒とした。測定試料は、硬質皮膜断面を５度で傾斜させ、鏡面加工したものを用い、膜厚が２〜３μｍになる位置において、１０点測定しその平均値を求めた。本発明例４〜７のＸ線光電子分光分析結果から５２５ｅＶから５３５ｅＶの範囲に、Ａｌ、Ｃｒ及び／又はＳｉと酸素との結合エネルギーが存在することを確認した。図５より、本発明例４〜７、Ａｌ添加量、４５〜８５原子％の範囲で、酸素を含有しない従来例より著しい硬化が確認された。本発明の硬質皮膜は、酸素を含有し、且つ金属元素と酸素の結合を形成する事により、高硬度となり、４０ＧＰａ以上の硬度を得ることが出来る。これによって密着性並びに耐摩耗性に優れた被覆粗加工用エンドミルが得られる。
【００２１】
（実施例３）
粉末高速度鋼を基体に用い、表１に示す皮膜組成の、本発明例１２〜２２、比較例２３〜３０及び従来例１０を製作した。被覆条件は実施例１に準ずる。表１に皮膜の組成等を示す。
【００２２】
【表１】
【００２３】
表１の試料を用いて、大気中１１００℃の酸化条件で処理した皮膜の酸化層の厚さ、実施例２同様に微小押込み硬さ、薄板の変形量より算出した残留圧縮応力、弾性回復率を測定した。表１より、酸化層厚さは、本発明例１２〜２２は、殆ど酸化進行が無く、耐高温酸化特性に優れていることが確認された。従来例１０は酸化進行が著しく、硬質皮膜は殆ど酸化物となり、酸素の内向拡散が激しく、酸化層は基体まで到達していた。押込み硬さも炭素、硼素を含有させることにより、更に高硬度となる。残留圧縮応力は、本発明例１２〜２２は低く、更に、図６に示す、本発明例１２及び従来例１０の荷重変位曲線より、本発明例１２は、最大荷重時における最大変位量が大きいにもかかわらず、塑性変形量が小さい。すなわち、同一応力が硬質皮膜に作用した際、弾性回復する割合が大きく、被覆基体の塑性変形に追従し易く、また塑性変形し難いことを示すものである。この荷重変位曲線より弾性回復率Ｅを求めた。Ｅが大きい程、弾性回復特性に優れる。表１より、本発明例１２〜２２は弾性回復特性に優れ、硬質皮膜の剥離やクラックの低減が可能となり、密着性に優れた硬質皮膜を得ることができる。これは、皮膜硬度差よりも大きな効果がある。
【００２４】
次に、表１の本発明例及び比較例を用いて圧痕試験による皮膜剥離状況を併記する。測定はロックウェル硬度計により１４７０Ｎの荷重で圧痕を形成し、光学顕微鏡により圧痕周辺部の剥離状況を観察した。本発明例１２〜２２は剥離が無く、優れた密着性を示した。これは本発明例が適正なＥ値の範囲内にあるためである。比較例２３〜３０、従来例１０は被覆基体の塑性変形に追従することができず、圧痕周辺部に膜剥離が発生した。
【００２５】
（実施例４）
表１に示す本発明例１２から２２、比較例２３から３０及び従来例１０の硬質皮膜を外径１２ｍｍ、４枚刃、高速度鋼製被覆粗加工用エンドミルに被覆した。被覆条件は実施例１に準ずる。表１に示す本発明例１２から２２、比較例２３から３０及び従来例１０の被覆被覆粗加工用エンドミルを用いて、下記条件の切削試験を行い切削不能に至るまでの切削長を表１に併記する。
（切削条件）
切削方法：側面粗加工
被削材：ＳＣＭ４４０（硬さＨＲＣ３１）
切り込み：Ｒｄ６ｍｍ、Ａｄ１２ｍｍ
切削速度：６５ｍ／ｍｉｎ
送り：０．０７ｍｍ／刃
切削油：無し（乾式エアーブロー）
【００２６】
表１より、本発明例１２から２２の高速度鋼を基体とした被覆粗加工用エンドミルは、従来例１０と比較して切削不能に至るまでの切削長が長く、耐摩耗性に優れている。本発明例１３は本発明皮膜被覆後にダイヤモンド粒子を含有した粒子を工具すくい面に投射することにより、硬質皮膜表面を平滑にしたが、本発明例１２と比較しても、より切削寿命が延長している。本発明例２１は硬質皮膜最表面の酸素濃度が高く、硬質皮膜内部が硬質皮膜最表面に比べ、低い場合の発明例を示すが、極めて寿命が長い。比較例２３は被覆条件をバイアス電圧−２５Ｖで被覆した硬質皮膜のＸ線回折による（２００）面の半価幅が０．４となり、本発明例に比べて切削寿命が短い。比較例２４はターゲットに含有する酸素濃度が１２００ｐｐｍからなるターゲットを使用した場合を示すが、Ｘ線光電子分光分析により酸化物としての結合状態が確認されず、本発明例に比べて切削寿命が短い。比較例２５は高速度鋼母材中の（Ｖ＋Ｃｏ）が２１．２重量％の場合の比較例であるが本発明例に比較して、寿命が短い。比較例２６は高速度鋼母材中のＣｒが１．８重量％の場合の比較例であるが本発明例に比較して、寿命が短い。比較例２７は、本発明例１２と同一皮膜であるが溶解法により作成した高速度鋼基体の場合の比較例を示すが、耐摩耗性が十分ではなく、粉末法により作成した本発明例に比べ工具寿命が短い。比較例２８はＡｌ含有量が９０原子％の場合であり、切削寿命が短く耐摩耗性に劣る。比較例２９は酸素含有量が７７原子％の場合であるが、耐摩耗性が十分ではない。比較例３０はＡｌ含有量が４３原子％の場合であるが耐摩耗性が十分ではない。
【００２７】
【発明の効果】
本願発明の被覆粗加工用エンドミルを適用することにより、過酷な切削加工に用いても十分な耐摩耗性を有し、基体表面とその直上の硬質皮膜との密着性改善を図り、更に高硬度で耐高温酸化特性に優れた被覆粗加工用エンドミルを得ることが出来た。
【図面の簡単な説明】
【図１】図１は、本発明例のＣｒ−Ｏ及びＡｌ−Ｏの結合エネルギーを示す。
【図２】図２は、本発明例のＣｒ−Ｎ及びＣｒ−Ｏの結合エネルギーを示す。
【図３】図３は、本発明例のＡｌ−Ｎ及びＡｌ−Ｏの結合エネルギーを示す。
【図４】図４は、本発明例のＸ線回折結果を示す。
【図５】図５は、本発明例と従来例のＡｌ添加量と皮膜硬度の関係を示す。
【図６】図６は、本発明例１２及び従来例１０の荷重変位曲線を示す。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a coated rough processing end mill that exhibits excellent wear resistance by coating a hard coating useful as a surface coating material of a rough processing end mill used for cutting of dies, machine parts, and the like. .
[0002]
[Prior art]
As an end mill for rough machining used for rough cutting of molds and mechanical structural parts, an end mill with a wavy cutting edge continuously formed in a wavy shape at the outer peripheral edge and a nick for separating chips are provided. End mills for rough machining are used. The end mill provided with the wavy shape and the nick has a larger cutting depth with respect to the tool diameter because the cutting stress at the time of the cutting process is dispersed than the end mill without the wavy shape / nick, and is suitable for rough cutting. In this way, the end mill for rough machining applies a greater impact force to the cutting edge than cutting by an end mill without a normal wavy cutting edge, and at the same time, the amount of chips discharged per unit time increases, and the wavy The flank side and rake side near the cutting edge are exposed to extremely high temperatures. Therefore, in order to suppress tool wear near the wavy cutting edge of the rough machining end mill, a rough machining end mill coated with a (TiAl) N film having improved film hardness and high-temperature oxidation resistance is used. However, in the field of cutting in recent years, in order to prolong the service life and reduce the cost of rough cutting, high-speed processing and high hardness of a workpiece are required for high efficiency. A rough cutting end mill coated with an N film does not provide a cutting life that satisfies these requirements. Therefore, AlCr-based coatings are disclosed in Patent Documents 1 to 3 shown below as hard coating materials having better high-temperature oxidation resistance than (TiAl) N coatings.
[Patent Document 1] Japanese Patent No. 3027502 (page 6, FIG. 1)
[Patent Document 2] Japanese Patent No. 3039381 (page 4, FIG. 1)
[Patent Document 3] JP-A-2002-160129 (page 3, FIG. 1)
[0003]
Patent Literature 1 discloses an AlCr-based hard film selected from AlCr and one of C, N, and O as a metal component, and an example relating to an amorphous film having high hardness. However, the hardness of the amorphous film is at most about 21 GPa Knoop hardness, and the wear resistance is not improved as an end mill for rough working, and the adhesion is not sufficient. The hard coatings disclosed in Patent Literature 2 and Patent Literature 3 are nitrides of AlCr and have a high-temperature oxidation resistance of about 1000 ° C, but the oxidation resistance at a temperature of 1000 ° C or higher has been studied. Absent. The hardness is about 21 GPa Vickers hardness, the hardness is not sufficiently improved, and the wear resistance is poor.
[0004]
[Problems to be solved by the invention]
The present invention is directed to an end mill for coating rough machining which solves the above problems and significantly improves wear resistance by increasing hardness, which is a drawback of (AlCr) N-based coatings, resulting in excellent tool life. The purpose is to provide.
[0005]
[Means for solving the problem]
The present invention relates to an end mill for coating rough processing, wherein the coating is a hard coating coated by an arc discharge ion plating method, and the hard coating is formed of (Al x Cr 1-xy Si y ) (N 1 -α-β-γ B α C β O γ), where, x, y, α, β , γ represents a respective atomic ratio, 0.45 <x <0.85,0 ≦ y <0.35, At least one layer represented by 0.50 ≦ x + y <1.0, 0 ≦ α <0.15, 0 ≦ β <0.65, 0 <γ <0.65, 0 <α + β + γ ≦ 1.0 Has a diffraction intensity on the (200) plane of the rock salt structure type measured by X-ray diffraction by the θ-2θ method, and the half value width of 2θ of the diffraction peak is 0.5 ° or more and 2.0 ° or less. In the range of 525 eV to 535 eV in X-ray photoelectron spectroscopy, at least Al, Cr and / or Si The coating substrate of the roughing end mill is made of powdered high-speed steel, and the sum of V and Co is 10 ≦ (V + Co) ≦ 20 by weight% and 2 ≦ Cr by Cr weight%. <6 is an end mill for rough coating. By adopting the above configuration, the adhesion between the substrate and the hard coating is particularly excellent, and the hardness can be increased. As a result, the end mill for rough coating of the present invention which exhibits excellent wear resistance is completed. I let it.
[0006]
In the hard coating of the present invention, when the diffraction intensity of the (111) plane of the rock salt structure type measured by X-ray diffraction by the θ-2θ method is I (111), and the diffraction intensity of the (200) plane is I (200). , 0.3 <I (200) / I (111) <12, the compressive stress remaining in the hard coating is reduced, the adhesion to the substrate is excellent, and the hardness of the coating and the improvement of the oxidation resistance are improved. Large contribution. The contact depth and the maximum displacement at the time of the maximum load are determined by a hardness measurement method using nanoindentation (WC Oliver and GM Phar: J. Mater. Res., Vol. 7, No. 6). , June, 1992, 1564-1584). Using this number,
E = 100-{(contact depth) / (maximum displacement at maximum load)}
The elastic recovery ratio E is defined by the following formula, and by setting 28% ≦ E ≦ 40%, the balance between wear resistance and adhesion is optimized. Furthermore, when the oxygen concentration is maximum in a depth region within 500 nm in the depth direction from the outermost surface of the hard coating, it is extremely effective for improving high-temperature oxidation resistance and wear resistance. Further, in the hard coating of the present invention, when the projections on the surface of the hard coating are smoothed by mechanical treatment, the coefficient of friction of the surface is reduced, thereby improving the chip dischargeability. The coated roughing end mill of the present invention is desirably a coated roughing end mill having a wavy cutting edge, the coated substrate is a high-speed steel prepared by a powder method, and the substrate has a hardness of HRC64 or more, It is particularly preferred that it is less than HRC71.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
The composition of the metal elements constituting the hard coating of the present invention, (Al x Cr 1-x -y Si y) in, x is from 0.45 <x <0.85, y is 0 ≦ y <0.35, It is necessary to satisfy 0.50 ≦ x + y <1.0. When the value of x is 0.45 or less and the value of x + y is less than 0.5, the effect of improving the film hardness and the high-temperature oxidation resistance is not sufficient, and the value of x is 0.85 or more or the value of x + y In the case of 1, the hardness of the film is remarkably reduced and the wear resistance is poor. When the value of y is 0.35 or more, the compressive stress remaining in the hard coating becomes excessive, and the adhesion strength to the substrate may be significantly reduced, such as inducing self-destruction immediately after coating. As for the composition of the nonmetal element, in (N1- [ alpha]-[beta]-[gamma] B [ alpha] C [ beta] O [ gamma] ), when [alpha] is 0.15 or more, the coating becomes brittle, and the preferable upper limit of [alpha] is 0.07. The addition of boron has the effect of reducing the welding resistance to the workpiece and the coefficient of friction in a high-temperature environment, and improving the lubricity. When β is 0.65 or more, the film becomes extremely brittle. The upper limit of the carbon content depends on the thickness of the layer containing carbon. If the thickness of the layer containing carbon is less than 0.5 μm, the upper limit of β is 0.5. The addition of carbon has the effect of increasing the hardness of the hard coating, reducing the coefficient of friction, and improving lubricity. γ is larger than 0 and must be less than 0.65. When γ is 0, the high-temperature oxidation resistance and the film hardness are insufficient and the wear resistance is poor. Even with 0.65 or more, the film hardness decreases. The preferred value of γ depends on the thickness of the layer containing oxygen, but if it is less than 0.5 μm, the upper limit of γ is 0.3. The addition of oxygen reduces the compressive stress remaining in the hard coating and improves the adhesion between the base and the coating. The reduction of the vertical grain boundaries is effective in improving the high-temperature oxidation resistance. Further, the ratio of N, B, C, O of the non-metallic element to Al, Cr, Si of the metal element is stoichiometrically ((N, B, C, O) / (Al, Cr, Si)> 1). .0 is more preferred.
[0008]
The hard coating of the present invention has a diffraction intensity on the (200) plane of the rock salt structure type measured by X-ray diffraction by the θ-2θ method, and the half width of 2θ of the diffraction peak is 0.5 ° or more, 2.0 degrees or less. The reason is that if it is less than 0.5, the crystal grains become coarse, the film hardness and high-temperature oxidation characteristics are not sufficient, and the abrasion resistance is poor, and if it exceeds 2.0, the film becomes brittle and the substrate adhesion strength is remarkably increased. This is for deteriorating.
[0009]
The hard coating needs to have at least the binding energy between Al, Cr and / or Si and oxygen in the range of 525 eV to 535 eV by X-ray photoelectron spectroscopy analysis. This is because these metal elements have a bond with oxygen, so that the film becomes denser and harder, and furthermore, in an oxidizing atmosphere, crystal grain boundaries in a direction perpendicular to a substrate serving as a diffusion path of oxygen are reduced, and oxygen is reduced. This has the function of suppressing the inward diffusion of the In order to form the bonding state of Cr, Al and / or Si and oxygen, which are the characteristics of the coating of the present invention, it is necessary to contain optimal coating conditions and a certain amount or more of oxygen in the hard coating.
[0010]
The coated substrate of the coating roughing end mill is made of powdered high-speed steel, and the sum of V and Co is 10 ≦ (V + Co) ≦ 20 in weight%, and 2 ≦ Cr ≦ 6 in weight% of Cr. When the value of (V + Co) exceeds 20 in weight%, chipping of the cutting edge tends to increase, and when the value of (V + Co) is less than 10 in weight%, the wear resistance is not sufficient. In addition, even if (V + Co) satisfies the above range, if the Cr content is less than 2 in weight%, the wear resistance is not sufficient, and if the weight% exceeds 6, chipping of the cutting edge is reduced. It tends to increase. With these configurations, it is possible to achieve high efficiency and long life of rough cutting by the end mill for coating rough processing.
[0011]
In the end mill for rough coating, the diffraction intensity of the (111) plane of the rock salt structure type measured by X-ray diffraction by the θ-2θ method of the hard coating is I (111), and the diffraction intensity of the (200) plane is I ( 200), it is preferable that 0.3 <I (200) / I (111) <12. The adhesion of the film strongly depends on the residual compressive stress, and the residual compressive stress strongly depends on the ion energy which is a coating condition. That is, under the condition that the ion energy is low, the result is that the residual compressive stress of the film is low. Conversely, under conditions of high ion energy, the residual compressive stress of the coating is high. Here, the factors that determine the ion energy are specifically the bias voltage and the reaction gas pressure, which are the coating conditions, and can be controlled by this. According to the present invention, when the residual compressive stress is high, the coating tends to be strongly oriented to the (111) plane in X-ray diffraction, and the hardness of the coating can be made high due to the influence of the high residual compressive stress. It becomes possible. On the other hand, focusing on the adhesion of the coating, if the residual compressive stress in the hard coating is increased, the hardness of the coating can be increased. However, since the shear stress acts in the direction near the interface between the base and the coating, the adhesion increases. It is not preferable because the property is impaired. Therefore, it is important to optimally control the balance between the adhesion between the substrate and the coating and the hardness of the coating. In the present invention, by setting 0.3 <I (200) / I (111) <12, it is possible to optimally control the balance between the two.
[0012]
E according to the nanoindentation hardness measurement method is 28% ≦ E ≦ 40%. By optimally controlling the bias voltage, the reaction gas pressure and its partial pressure ratio, and the substrate temperature during film formation, which are the coating conditions of the film. Achievable and preferred. If E exceeds 40%, the residual compressive stress in the hard coating may be too high, resulting in poor toughness and poor adhesion. When it is less than 28%, it was confirmed that the wear resistance was not sufficient due to abnormal wear due to insufficient strength. A more preferred value of E is 30% to 35%.
[0013]
Furthermore, when the oxygen concentration becomes maximum in a depth region within 500 nm in the depth direction from the outermost surface of the hard coating, the cutting life is particularly excellent, which is preferable. Oxidation of the hard coating in the cutting process is dominated by diffusion of oxygen from the outermost surface of the hard coating. Therefore, by making the surface of the hard coating oxygen-rich, it is possible to densify the crystal and reduce the crystal grain boundary of the component in the vertical direction with respect to the substrate serving as a diffusion path of oxygen, thereby improving the high-temperature oxidation resistance and improving the cutting life. I do. Further, by making the outermost surface of the hard coating oxygen-rich, an effect of promoting the flow of chips is also confirmed, and lubrication characteristics can be improved, which is preferable.
[0014]
Coating the coating of the present invention, the convex portion of the hard coating surface along the polished surface or the ground surface of the coated substrate surface, since convex portions may be formed by adhesion of macroparticles and the like generated during coating, By smoothing the projections by mechanical treatment, it is desirable to further improve the chip removal effect. Further, by applying a mechanical treatment to the cutting edge after coating, a break-in effect is also confirmed, the chipping resistance and chipping resistance can be improved, and a more preferable end mill for coating roughing can be obtained.
[0015]
The coating roughing end mill is a coating roughing end mill having a wavy cutting edge, and the coated substrate is made of a high-speed steel prepared by a powder method, and has a substrate hardness of HRC64 or more and less than HRC71. It is even more desirable. By employing the corrugated cutting edge, the balance between the heat generated by the cutting resistance and the heat resistant temperature of the coating of the present invention is optimized, and the tool life can be further extended. The use of powdered high-speed steel as the coated substrate at this time is preferable because it is excellent in wear resistance even in severe roughing, and can suppress tool breakage and chipping of the cutting edge. When the base material is less than HRC64, the abrasion progression accompanied by plastic deformation of the peak of the wavy cutting edge toward the flank surface under severe cutting environment is also confirmed, and the cutting edge strength is not sufficient, which is not preferable. In the case of HRC71 or more, the peak of the wavy cutting edge may cause chipping or chipping, which is not preferable.
[0016]
The hard coating of the present invention is coated with an arc ion plating method to obtain an end mill for coating rough processing which has particularly excellent adhesion to a substrate, is dense, has high-temperature oxidation resistance and high hardness and has an extremely long life. Can be
[0017]
Regarding the aspect ratio of the crystal grains of the hard coating, the upper and lower positions in the upper and lower film thickness directions corresponding to T1, which is 25% to 50% of the film thickness T of the film fracture surface of the present invention. And ask. At this time, the upper end position and the lower end position are allocated so as to be substantially equal in the upper and lower film thickness directions from the reference position corresponding to T / 2. The upper-side particle diameter K and the lower-side particle diameter L in the horizontal direction at each upper and lower end position are obtained. Therefore, assuming that the aspect ratio is T1 / ((K + L) / 2), the aspect ratio of the crystal grains of the hard coating having a columnar crystal structure is 0.2 to 12. If the aspect ratio exceeds 12 and becomes large, the crystal grains become elongated in the film thickness direction, and the toughness of the film decreases, which is not preferable. If it is less than 0.2, the number of granular crystals tends to increase, and the hardness of the film is undesirably reduced. Further, when the residual compressive stress of the hard film is 0.5 GPa or more and 4.0 GPa or less, the hard film has toughness, and is in a range suitable for a balance between the film hardness and the substrate adhesion. It is effective for improvement.
[0018]
Further, when less than 10 atomic% of the metal component in the hard coating of the present invention is replaced by at least one of the metal components belonging to groups 4a, 5a and 6a of the periodic table, one or more hard coatings according to the present invention are used. In the multilayer structure containing, it is possible to supplement the characteristics of the end mill for coating rough processing of the present invention, and it is preferable. Use of a (TiAl) N-based coating or the like is also included in the technical scope of the present invention. Hereinafter, the present invention will be specifically described based on examples.
[0019]
【Example】
(Example 1)
For the film formation, an alloy target prepared by a powder method containing 3200 ppm of oxygen was used. Carbon into the hard film, oxygen, the addition of boron, N 2 gas is a reaction gas, CH 4 gas, C 2 H 2 gas, Ar gas, O 2 gas, a B 3 N 3 H 6 gas purpose of One or more gases from which a film was obtained or a combination thereof were selected and introduced into a vacuum apparatus. After introducing each reaction gas into the vacuum device, a pulse pressure of 12 Pa, a negative bias voltage of -160 V / a positive bias voltage of +40 V was used, the frequency at that time was 20 kHz, and the amplitude was 80% on the negative side. went. The coating temperature was 450 ° C., the film thickness was about 3.5 μm, and a hard coating made of (Al 0.65 Cr 0.35 ) (N 0.80 C 0.08 O 0.10 B 0.02 ) was coated. Inventive Example 1. The coating conditions are not limited to the above-mentioned coating conditions. The coating composition was determined by electron probe X-ray microanalysis and Auger electron spectroscopy. The X-ray photoelectron spectroscopy for analyzing the bonding state with oxygen in the hard film was performed using a PHI 1600S type X-ray photoelectron spectrometer, the X-ray source was 400 W using MgKα, and the analysis area was 0 mm in diameter. The inside of the .4 mm circle was analyzed. After sufficient degreasing and washing, the surface was etched using an Ar ion gun for 5 minutes in a vacuum apparatus, a wide spectrum was measured, and after further etching for 30 seconds, a narrow spectrum was measured. The etching rate by the Ar ion gun was 1.9 nm / min in terms of SiO2. FIG. 1 shows the results of X-ray photoelectron spectroscopy analysis of Example 1 of the present invention. FIG. 1 shows a narrow spectrum in which the binding energy is around 530 eV, and shows the presence of Cr—O and Al—O bonds. FIG. 2 shows the presence of Cr-N and Cr-O bonds. FIG. 3 shows the presence of Al—N and Al—O bonds. FIG. 4 shows an X-ray diffraction result of the present invention example 1 by the θ-2θ method.
[0020]
(Example 2)
In the same manner as in Example 1, (Al x Cr 1-xy Si y ) (N 0.95 O 0.05 ) was formed, and Comparative Example 2, x = 0.20, y = 0, Comparative Example 3, x = 0.30, y = 0, present invention example 4, x = 0.50, y = 0, present invention example 5, x = 0.60, y = 0, present invention example 6, x = 0 .70, y = 0, present invention example 7, x = 0.80, y = 0 and (AlxCr1-x) N-based comparative example 8, x = 90, y = 0, conventional example 9, x = 0. 20, Conventional Example 10, x = 0.50 and Conventional Example 11, x = 0.70, and the indentation hardness by the nanoindentation method was measured. The tester used was a micro indentation hardness tester, and the indenter used was a triangular pyramid indenter made of diamond with a 115 ° confronting angle. The maximum load was 49 mN, the load step was 4.9 mN / sec, and the holding time at the maximum load was 1 Seconds. As the measurement sample, a hard film having a cross section inclined at 5 degrees and mirror-finished was used. At a position where the film thickness became 2 to 3 μm, 10 points were measured, and the average value was obtained. From the results of the X-ray photoelectron spectroscopy analysis of the inventive examples 4 to 7, it was confirmed that the binding energy between Al, Cr and / or Si and oxygen was present in the range of 525 eV to 535 eV. From FIG. 5, it was confirmed that in Examples 4 to 7 of the present invention and in the range of the addition amount of Al of 45 to 85 atomic%, remarkable hardening was observed as compared with the conventional example containing no oxygen. The hard coating of the present invention contains oxygen and forms a bond between a metal element and oxygen, thereby achieving a high hardness and a hardness of 40 GPa or more. As a result, an end mill for coating roughing having excellent adhesion and wear resistance can be obtained.
[0021]
(Example 3)
Inventive Examples 12 to 22, Comparative Examples 23 to 30, and Conventional Example 10 having the coating compositions shown in Table 1 were manufactured using powdered high-speed steel as the substrate. The coating conditions are the same as in Example 1. Table 1 shows the composition of the film and the like.
[0022]
[Table 1]
[0023]
Using the samples shown in Table 1, the thickness of the oxide layer of the film treated under the oxidation conditions of 1100 ° C. in the air, the microindentation hardness, the residual compressive stress calculated from the deformation of the thin plate as in Example 2, and the elastic recovery rate Was measured. From Table 1, it was confirmed that the oxidation layer thicknesses of Examples 12 to 22 of the present invention hardly proceeded with oxidation and were excellent in high-temperature oxidation resistance. In Conventional Example 10, the oxidation progressed remarkably, the hard film almost became an oxide, the inward diffusion of oxygen was intense, and the oxide layer reached the substrate. The indentation hardness is further increased by containing carbon and boron. Residual compressive stress is low in Examples 12 to 22 of the present invention. Further, from the load displacement curves of Examples 12 and 10 of the present invention shown in FIG. Nevertheless, the amount of plastic deformation is small. That is, when the same stress acts on the hard coating, the elastic recovery rate is large, indicating that it is easy to follow the plastic deformation of the coated substrate, and it is difficult to perform the plastic deformation. The elastic recovery rate E was determined from the load displacement curve. The larger the E, the better the elastic recovery characteristics. From Table 1, it can be seen that Examples 12 to 22 of the present invention are excellent in elastic recovery characteristics, enable peeling of the hard film and reduce cracks, and can provide a hard film having excellent adhesion. This has a greater effect than the film hardness difference.
[0024]
Next, the peeling state of the film by the indentation test will be described together with the present invention examples and comparative examples in Table 1. In the measurement, an indent was formed with a load of 1470 N using a Rockwell hardness tester, and the peeling state around the indent was observed using an optical microscope. Inventive Examples 12 to 22 showed no peeling and exhibited excellent adhesion. This is because the example of the present invention is within the range of an appropriate E value. Comparative Examples 23 to 30 and Conventional Example 10 could not follow the plastic deformation of the coated substrate, and film peeling occurred around the indentation.
[0025]
(Example 4)
The hard coatings of Inventive Examples 12 to 22, Comparative Examples 23 to 30, and Conventional Example 10 shown in Table 1 were coated on a 12 mm outer diameter, 4-flute, high-speed steel coating roughing end mill. The coating conditions are the same as in Example 1. Using the end mills for rough coating of Examples 12 to 22, Comparative Examples 23 to 30, and Conventional Example 10 shown in Table 1, cutting tests were performed under the following conditions, and cutting lengths until cutting was impossible are shown in Table 1. I will write it together.
(Cutting conditions)
Cutting method: Side roughing Work material: SCM440 (hardness HRC31)
Cut: Rd6mm, Ad12mm
Cutting speed: 65m / min
Feed: 0.07 mm / blade Cutting oil: none (dry air blow)
[0026]
As shown in Table 1, the coated roughing end mills based on the high-speed steels of Examples 12 to 22 of the present invention have a longer cutting length until they cannot be cut as compared with Conventional Example 10, and are excellent in wear resistance. . In Invention Example 13, the hard coating surface was smoothed by projecting particles containing diamond particles onto the tool rake surface after coating the invention film, but the cutting life was longer than that of Invention Example 12. are doing. Invention Example 21 shows an invention example in which the oxygen concentration on the outermost surface of the hard film is high and the inside of the hard film is lower than the outermost surface of the hard film, but the life is extremely long. In Comparative Example 23, the half-value width of the (200) plane obtained by X-ray diffraction of the hard film coated with a bias voltage of −25 V under the coating condition was 0.4, and the cutting life was shorter than that of the present invention. Comparative Example 24 shows the case where a target having an oxygen concentration of 1200 ppm contained in the target was used. However, the bonding state as an oxide was not confirmed by X-ray photoelectron spectroscopy, and the cutting life was shorter than that of the present invention. . Comparative Example 25 is a comparative example in which (V + Co) in the high-speed steel base material is 21.2% by weight, but has a shorter life than the inventive example. Comparative Example 26 is a comparative example in which Cr in the high-speed steel base material is 1.8% by weight, but has a shorter life than the inventive example. Comparative Example 27 shows a comparative example in which a high-speed steel substrate produced by the melting method was the same film as that of Example 12 of the present invention. Tool life is shorter. Comparative Example 28 was a case where the Al content was 90 atomic%, and the cutting life was short and the wear resistance was poor. Comparative Example 29 is a case where the oxygen content is 77 atomic%, but the abrasion resistance is not sufficient. In Comparative Example 30, the Al content was 43 atomic%, but the abrasion resistance was not sufficient.
[0027]
【The invention's effect】
By applying the end mill for coating rough processing of the present invention, it has sufficient abrasion resistance even when used for severe cutting, improves the adhesion between the substrate surface and the hard coating immediately thereon, and further increases the hardness. As a result, an end mill for coating roughing having excellent high-temperature oxidation resistance was obtained.
[Brief description of the drawings]
FIG. 1 shows the binding energies of Cr—O and Al—O according to the present invention.
FIG. 2 shows the binding energies of Cr—N and Cr—O of the present invention.
FIG. 3 shows binding energies of Al—N and Al—O of the present invention.
FIG. 4 shows an X-ray diffraction result of an example of the present invention.
FIG. 5 shows the relationship between the amount of Al added and the film hardness of the present invention and the conventional example.
FIG. 6 shows load displacement curves of Example 12 of the present invention and Conventional Example 10.
