JP2004042149A

JP2004042149A - Coated cutting tool

Info

Publication number: JP2004042149A
Application number: JP2002199526A
Authority: JP
Inventors: Takashi Ishikawa; 石川　剛史
Original assignee: Hitachi Tool Engineering Ltd
Current assignee: Moldino Tool Engineering Ltd
Priority date: 2002-07-09
Filing date: 2002-07-09
Publication date: 2004-02-12

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool having a coating film rich in abrasion resistance and lubricity by constituting the cutting tool with the coating film superior in hardness, particularly, high temperature hardness and superior in the lubricity by adding boron in one film without arranging a hard coating film and a lubricating coating film in two layers or a double layer. <P>SOLUTION: This coated cutting tool is characterized in that a base body is composed of a cemented carbide alloy or TiCN group cermet, and the base body is coated with at least a TiN, TiB, BN existing coating film composed of (Ti<SB>x</SB>B<SB>1-x</SB>)(N<SB>y</SB>O<SB>1-y</SB>), here, 0.90 ≤ X ≤ 0.99 and 0.90 ≤ y ≤ 1.0, and the coating film has 0.3 to 0.6 of a friction coefficient to steel in a cutting temperature area. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、ドリル、エンドミル、フライス加工用刃先交換型チップ、旋削用刃先交換型チップ等の切削工具に関し、特に、その表面に耐摩耗性と潤滑性に富む皮膜を備えた切削工具に関する。
【０００２】
【従来の技術】
切削工具の高能率化、高精度化の要求を満たすために、切削速度がより高速になってきており、刃先の温度は益々高温になる傾向にある。切削工具は、様々な形態の損傷を受けるが、その主なものは摩耗と欠損である。摩耗は、機械的な摩擦摩耗と、高温での酸化や被削材との間での拡散などによって生じる熱的摩耗とに大きく分けられる。いずれの摩耗の場合も、切削速度や送り速度が大きくなって工具の刃先温度が高くなるほど著しくなる。欠損は、刃先にかかる大きな切削抵抗や機械的、熱的な衝撃によって起こり、高速送り切削や断続切削で顕著に現われる。皮膜に要求される特性は一段と厳しくなる一方である。その皮膜としては、（ＴｉＡｌ）Ｎ、（ＴｉＳｉ）Ｎ、が挙げられる。これらの中でも、（ＴｉＳｉ）Ｎ、皮膜の高硬度を生かし、高速切削に対応し、硬質膜として切削工具等に応用されている。これら硬質膜を形成する方法としては、従来から、ＰＶＤ法又はＣＶＤ法に代表されるイオンプレーティング法、スパッター蒸着法、プラズマＣＶＤ法及びイオン注入法などの表面改質技術が検討されている。特に、イオンプレーティング法は、基体との密着性が優れる。
【０００３】
次に、潤滑性では、上記硬質被覆層の上にＣｒＮ、ＢＮ、ダイヤモンド状カーボン（以下、ＤＬＣと称する。）、黒鉛、フッ化黒鉛、ＭｏＳ_２の固体潤滑剤膜を０．１〜２μｍ被覆したものが実用化されている。例えば、特開平１０−１５８８６１号公報では、切削工具の表面での被削材の溶着を防ぐために、耐摩耗性皮膜として窒化チタン膜、ＴｉとＶとＮとを含有する皮膜を設け、上記皮膜が切削時の温度の影響により酸化バナジウム、融点が１０００℃以下の低融点酸化物、に変化し、切削中の摩擦熱で酸化物が軟化または溶融状態になり、溶着した被削材が容易に脱落し、溶着そのものを生じなくしている。
更に、特開２０００−１２９４２０号公報には、高温摺動部材用硬質膜として、ＴｉＮ膜の優れた耐摩耗性および低摩擦係数を生かしつつ、窒化チタンを主成分とし、Ａｌ、Ｃｒ、Ｚｒ及びＨｆから選ばれる少なくとも一つの元素を含有する窒化物であって、前記窒化物の結晶粒子の格子定数が０．４１４ｎｍから０．４２３ｎｍの範囲にある面心立方晶構造であることを特徴とする高温摺動部材用硬質膜、が提案されている。
【０００４】
【発明が解決しようとする課題】
切削工具の加工能率を一層向上させるために切削速度がより高速になることに加え、環境対策として、切削油剤削減のためのドライ（乾式）加工化が進みつつある。これらのことから、切削工具の刃先温度は益々高温になる傾向にあるので、今後用いられる工具の材料には高温における耐摩耗性が要求されるとともに、刃先での溶着欠損を防ぐための潤滑性が同時に求められるようになってきている。
【０００５】
【本発明の目的】
そのため、本願発明では、上述のような技術的な背景に鑑みてなされたものであり、従来のように硬質皮膜、潤滑性皮膜を２層又は複層設けるのではなく、１膜中に硼素を添加することより硬さ、特に高温硬さに優れ、潤滑性に優れた皮膜で構成することにより、上記耐摩耗性と潤滑性に富む皮膜を備えた切削工具を提供することを目的とする。
【０００６】
【課題を解決するための手段】
本発明は、基体が超硬合金又はＴｉＣＮ基サーメットからなり、該基体に（Ｔｉ_ｘＢ_１−ｘ）（Ｎ_ｙＯ_１−ｙ）、但し、０．９０≦Ｘ≦０．９９、０．９０≦ｙ≦１．０からなり、且つ、少なくともＴｉＮ、ＴｉＢ、ＢＮが存在する皮膜を被覆し、該皮膜は、鋼に対する摩擦係数が、切削温度域で０．３〜０．６で有ることを特徴とする被覆切削工具である。
【０００７】
【発明の実施の形態】
第１に、該皮膜は、（Ｔｉ_ｘＢ_１−ｘ）（Ｎ_ｙＯ_１−ｙ）、但し、０．９０≦Ｘ≦０．９９、０．９０≦ｙ≦１．０の組成からなり、Ｔｉ量を０．９０≦Ｘ≦０．９９、すなわちＢ量を０．０１〜０．１０の範囲とすることにより、適度な硬さと潤滑性の向上がはかれる。Ｂは、Ｔｉと化合物を形成し、非金属のＮ、Ｏとも化合物を形成し、ＴｉＢ、ＢＮ、ＢＯも形成し、硬さと潤滑性を高めることができる。又、Ｂ量が０．１０を越えると硬くなりすぎるため０．０１〜０．１０の範囲とした。
次に、Ｎ量を０．９０≦ｙ≦１．０の範囲としたのは、酸素量が０．１０を越えると他の低級酸化物が生成されやすく、例えばＴｉＮＯ等の生成される量が僅少で有れば皮膜に悪影響を及さないが、増えるに従い皮膜を脆化させるため、０．９０〜１．０の範囲とした。これらの範囲とすることにより、少なくともＴｉＮ、ＴｉＢ及びＢＮとＢＯとが存在し、皮膜自体の硬さが高く、特にＴｉＢを分散させることによりＨＶ２５００〜３０００程度の硬さとなり、ＴｉＮ（ＨＶ２０００〜２１００）に比べて向上させることができる。
【０００８】
図１、図２は、本発明例の（ＴｉＢ）（ＮＯ）皮膜を被覆した時の皮膜のＥＳＣＡ解析結果である。図１のＴｉとＮとの結合エネルギ回折ピークと、図２のＢとＮとの結合エネルギー回折ピークが確認され、皮膜はＴｉＮ相とＢＮ相を含むことが確認された。この場合、ＢＮ相はＴＥＭ観察結果によれば数ナノから数十ナノの大きさを有するナノ結晶であり、格子歪の発生に起因するＴｉＮ層の大幅な硬度上昇が確認された。耐クレータ摩耗性はＴｉＮに比べ著しく改善される結果であった。これはＢＮ相自体が優れた潤滑性を有していることに起因すると考えられる。
【０００９】
第２に、該皮膜の鋼に対する摩擦係数を、切削温度域で０．３〜０．６とした理由は、ボールオンディスク型の摩耗試験器において、主要なパラメータである垂直荷重、接触面積、摺動速度、試験時間があり、更に、試験温度の与える影響は非常に重要で、多くは摩擦による発熱であるが熱的に化学反応が活性化されることがある。本発明の皮膜は、切削工具として用いたときの切れ刃付近の温度に近似した温度域での摩擦の状況を確認した。
ＪＩＳ、ＳＫＤ６１材をボール材（静止相手材）とし、ディスクを超硬合金で製作し、そのディスク上に本発明皮膜を被覆した。測定は、接触面圧：２Ｎ、速度：１００ｍｍ／ｓｅｃ、温度：室温（２５℃）、４００℃、７００℃時で行い、その時の試験時間と摩擦係数の関係を図１に示す。尚、比較のため、従来例２として、本発明の実施例中に基体直上の層に用いた（ＴｉＡｌ）Ｎ膜を併記する。
図３より、本発明例１の摩擦係数は、室温においては、従来例２と大差く、０．８５〜０．９５の範囲で推移している。温度の上昇に伴い、本発明例１は試験温度４００℃では０．５５〜０．６で低下し、更に、７００℃では、０．４３〜０．４７と低下する。それに対し、従来例２では、０．７５〜０．８５の範囲で推移している。
上記のように、本発明皮膜は、切削時に上昇する切れ刃付近の温度、７００℃で摩擦係数が低くなり、切屑の擦り摩耗を低減し、スムーズな切屑排出を行うことができる。
【００１０】
第３に、該皮膜中のＢは、皮膜の最表面から深さ方向に５００ｎｍ未満の領域でＢ含有量が最大となる場合、更に優れた切削寿命が得られた。また、Ｂは、該皮膜の最表面から膜厚深さ方向に５００ｎｍ未満の領域でＢ含有量が最大となることが好ましい。５００ｎｍ未満の表面層側にＢ濃度が高い場合、切削過程において耐摩耗皮膜中の１部のＢがＢとＯの結合及び／又はＢとＮの結合となり、更に被加工物との摩擦が低減され好ましい。５００ｎｍより内部の硬質皮膜でＢの濃度が高くなる場合、靭性が損なわれる場合があり耐欠損性が十分ではない場合が確認されており好ましくない。
上記により、高速切削加工及び高硬度材切削加工などの過酷な切削環境下においても、皮膜剥離を生ずることなく、皮膜の耐酸化性及び皮膜硬さを改善しているため、切削寿命が極めて長く、切削速度の高速化が可能であり、従来技術の課題を解決するに至った。
【００１１】
次に、該皮膜は、Ｘ線回折における回折強度が（２００）面で最大ピークを示し、その（２００）面の回折線が２θの半価幅で１．０度以上である。図６にはＸ線回折パターンを示す。図６より、（２００）面に最強ピーク強度を示し、その（２００）面における回折ピークは２θの半価幅で１．０度以上の広がりが認められる。半価幅の測定には、Ｘ線回折における、Ｃｕ−Ｋα線の回折線を用い、入射角を５度に設定し、θ−２θ法で測定した。半価幅の測定には（２００）面の回折線のバックグラウンドに対するピーク高さの２分の１における回折線の幅をもって算出した。該皮膜は（２００）面に強く配向した場合が最も皮膜内の格子欠陥が少なく、高密度であり耐酸化性に優れるため、（２００）面に最大のピーク強度をもつことが好ましい。更に、その半価幅が１．０度以上の広がりを有する場合、高硬度化並びに耐酸化性改善が著しく、更に好ましい。
【００１２】
更に、該Ｔｉの１部を、金属のみの原子％で３０％未満をＴｉを除く周期律表の４ａ、５ａ、６ａ族及びＡｌ、Ｓｉ元素から選択される１種以上で置換しても良い。該皮膜の硬さを更に向上させるには、特に、Ｓｉ、Ｚｒ等の添加が有効であり、潤滑性を向上させるには、Ｃｒ、Ａｌの添加が有効である。
【００１３】
被覆方法として、物理蒸着法及び／又はプラズマ活性化化学蒸着法で被覆することが望ましく、耐摩耗皮膜内へのＢの添加方法としてはＢ含有気体を用いると耐摩耗皮膜内のＢ含有量を制御することが可能であり、更に、優れた切削特性を得ることが可能であり好ましい。物理蒸着における被覆処理においては被覆時のイオン化率が高く、高密度なプラズマを形成することが可能であり、被覆基体との密着性が優れる。また、プラズマ活性化化学蒸着法においても同様に高密度であるプラズマを形成することが可能であると同時に、Ｂ含有気体を真空容器内に導入してイオン化することが可能であるため、Ｂ濃度のコントロールが容易である。また、耐摩耗皮膜の被覆基体への密着性の改善及び又は切削寿命を延ばすために、被覆前後に、工具切刃を機械的処理によってなじませることにより、突発的なチッピングが抑制され、好ましい。また、被覆中に付着したドロップレット等の欠陥に関しても機械的処理により除去することも、異常摩耗の抑制に効果的であり好ましい。以下、本発明を実施例に基づいて説明する。
【００１４】
【実施例】
（実施例１）
アークイオンプレーティング装置を用い、金属成分の蒸発源である各種合金製ターゲット、ならびに反応ガスである窒素ガス、酸素ガス、硼素系ガスから目的の皮膜が得られるものを選択し、密着性付与皮膜においては、各種組成の金属ターゲットを用い、被覆基体温度４００℃、反応ガス圧力１．０Ｐａ、基体印可バイアス電圧１５０Ｖの条件下にて、被覆基体としてボールオンディスク型の摩耗試験機のディスクに本発明例１として、（Ｔｉ_０．９９Ｂ_０．０１）（Ｎ_０．９Ｏ_０．１）の皮膜を、厚さ５ミクロン成膜した。尚、比較のため、従来例２として、後述の、本発明の実施例中に基体直上の層に用いる（ＴｉＡｌ）Ｎ膜を５ミクロン成膜したものを用いた。
ＪＩＳ、ＳＫＤ６１材をボール材（静止相手材）とし、測定は、接触面圧：２Ｎ、速度：１００ｍｍ／ｓｅｃ、温度：室温（２５℃）、４００℃、７００℃時で行い、その時の試験時間と摩擦係数の関係を図１に示す。尚、比較のため、従来例２としても併記する。
図１より、本発明例１の摩擦係数は、室温においては、従来例２と大差く、０．８５〜０．９５の範囲で推移している。温度の上昇に伴い、本発明例１は試験温度４００℃では０．５５〜０．６で低下し、更に、７００℃では、０．４３〜０．４７と低下する。それに対し、従来例２では、０．７５〜０．８５の範囲で推移し、本発明例の皮膜は、切削に用いる温度域で低摩擦係数である。
【００１５】
（実施例１）
次に、超硬合金ＪＩＳ　Ｐ４０相当材種のスローアウェイインサート、工具型番：ＲＤＭＷ１６０４ＭＯＴＮ、丸駒インサートを用いて、基体直上に（ＴｉＡｌ）Ｎ層を２ミクロン被覆し、その上に（Ｔｉ_ｘＢ_１−ｘ）（Ｎ_ｙＯ_１−ｙ）を２ミクロン成膜し、本発明例３〜１６を製作した。尚、比較のため、上記（ＴｉＡｌ）Ｎ層のみのものも製作した。その組成等を表１に記載する。
【００１６】
【表１】

【００１７】
得られた被覆インサートを用い切削試験を行った。巾１００ｍｍ×長さ２５０ｍｍの面加工で、被削材はφ１０ｍｍのドリル穴を２０ｍｍ間隔に設けたＳＫＤ６１（ＨＲＣ４５）を、切削諸元、切り込み：１．０ｍｍ、切削速度：２００ｍ／ｍｉｎ、１刃当りの送り：１．５ｍｍ／刃、乾式切削で実施した。このドリル穴を一定間隔で配置したのは、特に、強断続切削とするためであり、皮膜は剥離し易い傾向を有する。欠損に至る切削長を表１に併記する。また、工具寿命は、皮膜に剥離が発生しない場合は、クレーター摩耗が寿命を支配するため、クレーター摩耗により工具が切削不能となった時の切削時間を寿命とした。１刃あたりの送りが１ｍｍを越えるようなフライス加工では切削温度が局部的に上昇し、クレーター摩耗が発生する傾向にある。
表１より明らかなように、本発明例３〜１１は著しい寿命改善が認められる。これらは比較例１４〜１７が全て、クレーター摩耗、皮膜剥離により短寿命であったことより、すくい面の潤滑性による耐クレーター摩耗性の改善によるところが大きい。また、本発明例１２は（１１１）配向の例であるが、本発明例４の（２００）配向に比して寿命までの切削時間がやや短くなった。本発明例１３は、半価幅が０．９度と、本発明例４の半価幅１．３度に比して、短くなったが、本発明例４では、ＳＥＭで皮膜の破面を観察すると、柱状に成長しており、耐摩耗性に優れる結果となった。
【００１８】
（実施例３）
実施例２の方法に基づき、表１記載の本発明例及び比較例の皮膜を旋削用超硬合金インサート、チップ形状：ＴＮＧＧ１１０３０２Ｒ、に被覆し、切削諸元、被削材として４つ溝付きのＳ５３Ｃを用い、切削速度：２００ｍ／分、切り込み：１ｍｍ、送り：０．１２ｍｍ／ｒｅｖ、水溶性切削油を用い湿式で行った。断続切削であり、皮膜は剥離し易い傾向を有し、剥離しない場合はいずれもクレーター摩耗の進行から発熱が大きくなり、逃げ面摩耗が増大する傾向にある。逃げ面摩耗値が０．１ｍｍになった時点を寿命と判定した。寿命までの切削時間を表２に記載する。
【００１９】
【表２】

【００２０】
表２の結果から明らかなように、本発明例１６〜２９では、ＴｉＮ、ＴｉＢに、第３のＣｒＮ等を加えたことにより、断続の高速旋削加工においても剥離、チッピング等を生せずに、長寿命であり、更には、本発明例２２のＶ、本発明例２６のＭｏでは、寿命に至る時間はやや短くなっている。また、本発明例２３のＺｒ、本発明例２５のＳｉ等では、長寿命が図れている。それに対し、比較例３２では、Ｃｒの添加量が多くなりすぎ、皮膜剥離は発生しないものの、寿命が短くなった。
【００２１】
【発明の効果】
以上の如く、本発明の多層硬質皮膜被覆工具は、従来の被覆工具に比べ耐クレータ摩耗性に優れ、乾式高速切削加工において格段に長い工具寿命が得られ、切削加工における生産性の向上、コスト低減、環境改善に極めて有効である。
【図面の簡単な説明】
【図１】図１は、本発明例のＥＳＣＡ解析結果で、ＴｉとＮとの結合エネルギ回折ピークを示す。
【図２】図２は、本発明例のＥＳＣＡ解析結果で、ＢとＮとの結合エネルギー回折ピークを示す。
【図３】図３は、ボールオンディスク型の摩耗試験機による、室温、４００℃、７００℃における距離−摩擦係数の推移を示す。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cutting tool such as a drill, an end mill, an exchangeable cutting edge for milling, and an exchangeable cutting edge for turning, and more particularly to a cutting tool provided with a coating having excellent wear resistance and lubricity on its surface.
[0002]
[Prior art]
In order to meet the demands for higher efficiency and higher precision of cutting tools, cutting speeds have become higher, and the temperature of the cutting edge tends to be higher and higher. Cutting tools are subject to various forms of damage, the main ones being wear and chipping. Wear can be broadly divided into mechanical friction wear and thermal wear caused by oxidation at high temperatures or diffusion between workpieces. In any case, the wear becomes more remarkable as the cutting speed or feed speed increases and the cutting edge temperature of the tool increases. The chipping occurs due to a large cutting force applied to the cutting edge or a mechanical or thermal shock, and is remarkably exhibited in high-speed feed cutting or intermittent cutting. The characteristics required for the film are becoming more severe. Examples of the coating include (TiAl) N and (TiSi) N. Among them, (TiSi) N and the high hardness of the film are utilized to cope with high-speed cutting and applied to cutting tools and the like as a hard film. As a method for forming these hard films, surface modification techniques such as an ion plating method represented by a PVD method or a CVD method, a sputter deposition method, a plasma CVD method, and an ion implantation method have been conventionally studied. In particular, the ion plating method has excellent adhesion to a substrate.
[0003]
Next, in the lubricity, CrN on the hard coating layer, BN, diamond-like carbon (hereinafter, referred to as DLC.), Graphite, graphite fluoride, the solid lubricant film of MoS ₂ 0.1-2 .mu.m coating Has been put to practical use. For example, in Japanese Patent Application Laid-Open No. 10-158861, in order to prevent welding of a work material on the surface of a cutting tool, a titanium nitride film and a film containing Ti, V and N are provided as a wear-resistant film. Changes to vanadium oxide, a low-melting oxide with a melting point of 1000 ° C or less due to the temperature during cutting, and the oxide becomes soft or molten due to frictional heat during cutting, and the welded work material is easily formed. It has come off and no welding has occurred.
Further, Japanese Patent Application Laid-Open No. 2000-129420 discloses that as a hard film for a high-temperature sliding member, titanium nitride is used as a main component while taking advantage of the excellent wear resistance and low friction coefficient of a TiN film, and Al, Cr, Zr and A nitride containing at least one element selected from Hf, wherein the nitride has a face-centered cubic structure in which the crystal grains have a lattice constant in a range of 0.414 nm to 0.423 nm. Hard films for high-temperature sliding members have been proposed.
[0004]
[Problems to be solved by the invention]
In addition to increasing the cutting speed in order to further improve the machining efficiency of the cutting tool, dry (dry) machining for reducing cutting oil is progressing as an environmental measure. From these facts, the cutting edge temperature of cutting tools tends to be higher and higher, so that the tool materials used in the future are required to have high wear resistance at high temperatures and lubricity to prevent welding defects at the cutting edges. Is also required at the same time.
[0005]
[Object of the present invention]
Therefore, the present invention has been made in view of the technical background as described above, and instead of providing two or more hard films and lubricating films as in the related art, boron is contained in one film. An object of the present invention is to provide a cutting tool provided with a film having excellent wear resistance and lubricity by being composed of a film having excellent hardness, particularly high-temperature hardness, and excellent lubricity.
[0006]
[Means for Solving the Problems]
The present invention, the substrate is made of cemented carbide or TiCN-based cermet, the base body _{_{_{(Ti x B 1-x)}}} (N y O 1-y), where, 0.90 ≦ X ≦ 0.99,0. 90 ≦ y ≦ 1.0 and at least a coating in which TiN, TiB and BN are present, wherein the coating has a friction coefficient against steel of 0.3 to 0.6 in a cutting temperature range. It is a coated cutting tool characterized by the following.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
First, it said coating _{_{_{is, (Ti x B 1-x}}} ) (N y O 1-y), provided that consists composition of 0.90 ≦ X ≦ 0.99,0.90 ≦ y ≦ 1.0 By setting the Ti amount to 0.90 ≦ X ≦ 0.99, that is, setting the B amount to the range of 0.01 to 0.10, moderate hardness and lubricity can be improved. B forms a compound with Ti, forms a compound with non-metallic N and O, also forms TiB, BN and BO, and can improve hardness and lubricity. On the other hand, if the B content exceeds 0.10, it becomes too hard, so that the B content is in the range of 0.01 to 0.10.
Next, the reason why the N amount is in the range of 0.90 ≦ y ≦ 1.0 is that when the oxygen amount exceeds 0.10, other lower oxides are easily generated. If the amount is small, it does not adversely affect the film, but the film is embrittled as the amount increases, so that the range is 0.90 to 1.0. Within these ranges, at least TiN, TiB, and BN and BO are present, and the hardness of the coating itself is high. In particular, by dispersing TiB, the hardness becomes about HV 2500 to 3000, and TiN (HV 2000 to 2100 ) Can be improved.
[0008]
1 and 2 show the results of ESCA analysis of the (TiB) (NO) film of the present invention when coated. The binding energy diffraction peak of Ti and N in FIG. 1 and the binding energy diffraction peak of B and N in FIG. 2 were confirmed, and it was confirmed that the film contained a TiN phase and a BN phase. In this case, the BN phase was a nanocrystal having a size of several nanometers to several tens of nanometers according to the TEM observation results, and a significant increase in the hardness of the TiN layer due to the occurrence of lattice strain was confirmed. As a result, the crater wear resistance was significantly improved as compared with TiN. This is considered to be due to the fact that the BN phase itself has excellent lubricity.
[0009]
Secondly, the reason for setting the coefficient of friction of the coating to steel in the cutting temperature range from 0.3 to 0.6 is that in a ball-on-disk type wear tester, the main parameters are vertical load, contact area, There are a sliding speed and a test time, and the influence of the test temperature is very important. In many cases, heat is generated by friction, but a chemical reaction may be activated thermally. When the film of the present invention was used as a cutting tool, the state of friction in a temperature range close to the temperature near the cutting edge was confirmed.
JIS, SKD61 material was used as a ball material (stationary mating material), a disk was made of a cemented carbide, and the disk was coated with the coating of the present invention. The measurement was performed at a contact surface pressure of 2 N, a speed of 100 mm / sec, a temperature of room temperature (25 ° C.), 400 ° C. and 700 ° C. The relationship between the test time and the friction coefficient at that time is shown in FIG. For comparison, a (TiAl) N film used for the layer immediately above the substrate in the example of the present invention is also shown as Conventional Example 2.
3, the coefficient of friction of Example 1 of the present invention is significantly different from that of Conventional Example 2 at room temperature, and is in the range of 0.85 to 0.95. As the temperature rises, Example 1 of the present invention decreases at a test temperature of 400 ° C from 0.55 to 0.6, and further decreases at 700 ° C from 0.43 to 0.47. On the other hand, in Conventional Example 2, the value is in the range of 0.75 to 0.85.
As described above, the coating of the present invention has a low coefficient of friction at 700 ° C., which is a temperature near the cutting edge, which rises during cutting, reduces abrasion of chips, and enables smooth chip discharge.
[0010]
Thirdly, when the B content in the coating is maximum in a region of less than 500 nm in the depth direction from the outermost surface of the coating, a more excellent cutting life was obtained. Further, it is preferable that the B content is maximum in a region of less than 500 nm from the outermost surface of the film in the thickness direction. When the B concentration is high on the side of the surface layer of less than 500 nm, a part of B in the wear-resistant coating becomes a bond of B and O and / or a bond of B and N in the cutting process, further reducing the friction with the workpiece. And preferred. When the concentration of B is higher than 500 nm in the inner hard coating, it has been confirmed that the toughness may be impaired and the fracture resistance may not be sufficient.
Due to the above, even under severe cutting environments such as high-speed cutting and cutting of hard materials, the coating has been improved in oxidation resistance and hardness without peeling off, resulting in extremely long cutting life. Thus, the cutting speed can be increased, and the problem of the prior art has been solved.
[0011]
Next, the film shows the maximum peak in X-ray diffraction intensity on the (200) plane, and the diffraction line on the (200) plane has a half width of 2θ of 1.0 ° or more. FIG. 6 shows an X-ray diffraction pattern. From FIG. 6, the strongest peak intensity is shown on the (200) plane, and the diffraction peak on the (200) plane shows a spread of 1.0 degree or more at a half width of 2θ. For the measurement of the half width, the diffraction angle of the Cu-Kα ray in the X-ray diffraction was used, the incident angle was set to 5 degrees, and the measurement was performed by the θ-2θ method. For the measurement of the half width, the width of the diffraction line at half the peak height of the diffraction line of the (200) plane with respect to the background was calculated. When the film is strongly oriented on the (200) plane, it has the least lattice defects in the film, has a high density and is excellent in oxidation resistance, and therefore preferably has the maximum peak intensity on the (200) plane. Further, it is more preferable that the half width has a spread of 1.0 degree or more, because the hardness and oxidation resistance are remarkably improved.
[0012]
Further, a part of the Ti may be replaced with one or more elements selected from the group 4a, 5a, 6a of the periodic table and the Al and Si elements excluding Ti and less than 30% by atomic% of metal alone. . In order to further improve the hardness of the film, it is particularly effective to add Si, Zr and the like, and to improve lubricity, it is effective to add Cr and Al.
[0013]
As a coating method, it is preferable to coat by a physical vapor deposition method and / or a plasma activated chemical vapor deposition method. As a method for adding B to the wear-resistant film, when a B-containing gas is used, the B content in the wear-resistant film is reduced. It is preferable because it can be controlled, and furthermore, excellent cutting characteristics can be obtained. In the coating process in physical vapor deposition, the ionization rate at the time of coating is high, high-density plasma can be formed, and the adhesion to the coated substrate is excellent. Also, in plasma-activated chemical vapor deposition, it is possible to form high-density plasma, and at the same time, it is possible to introduce a B-containing gas into a vacuum vessel and ionize it. Is easy to control. In addition, in order to improve the adhesion of the wear-resistant coating to the coated substrate and / or extend the cutting life, the tool cutting blade is adapted to the surface by mechanical treatment before and after coating, thereby suppressing sudden chipping, which is preferable. Further, it is also preferable to remove defects such as droplets adhered to the coating by mechanical treatment, because it is effective for suppressing abnormal wear. Hereinafter, the present invention will be described based on examples.
[0014]
【Example】
(Example 1)
Using an arc ion plating device, select a target made of various alloys that is a source of evaporation of metal components, and a target gas that can obtain the target film from nitrogen gas, oxygen gas, and boron-based gas that are reaction gases. In this test, a metal target of various compositions was used as a coated substrate on a disk of a ball-on-disk wear tester under the conditions of a coated substrate temperature of 400 ° C., a reaction gas pressure of 1.0 Pa, and a substrate applying bias voltage of 150 V. As Invention Example 1, a film of (Ti _0.99 B _0.01 ) (N _0.9 O _0.1 ) was formed to a thickness of 5 μm. For comparison, a conventional example 2 in which a (TiAl) N film used for a layer immediately above a substrate was formed to a thickness of 5 μm in an example of the present invention, which will be described later, was used.
JIS, SKD61 material is used as ball material (stationary mating material), the measurement is performed at contact surface pressure: 2N, speed: 100 mm / sec, temperature: room temperature (25 ° C), 400 ° C, 700 ° C, and test time at that time FIG. 1 shows the relationship between and the friction coefficient. For comparison, it is also described as Conventional Example 2.
As shown in FIG. 1, at room temperature, the coefficient of friction of Example 1 of the present invention is significantly different from that of Conventional Example 2, and is in the range of 0.85 to 0.95. As the temperature rises, Example 1 of the present invention decreases at a test temperature of 400 ° C from 0.55 to 0.6, and further decreases at 700 ° C from 0.43 to 0.47. On the other hand, in Conventional Example 2, the value changes in the range of 0.75 to 0.85, and the coating of the present invention has a low friction coefficient in the temperature range used for cutting.
[0015]
(Example 1)
Next, a (TiAl) N layer was coated on the base immediately above the substrate by 2 μm using a throw-away insert made of cemented carbide equivalent to JIS P40, a tool model number: RDMW1604MOTN, and a round piece insert, and (Ti _x B _{1) _{_{-x) (N y O 1-}}} y) and the 2 micron deposition was fabricated invention example 3-16. For comparison, a device having only the (TiAl) N layer was also manufactured. Table 1 shows the composition and the like.
[0016]
[Table 1]

[0017]
A cutting test was performed using the obtained coated insert. The surface is 100 mm wide x 250 mm long. The work material is SKD61 (HRC45) with φ10 mm drill holes at 20 mm intervals. Cutting specifications, depth of cut: 1.0 mm, cutting speed: 200 m / min, 1 blade Feed per unit: 1.5 mm / blade, dry cutting. The reason why the drill holes are arranged at regular intervals is, in particular, to perform heavy interrupted cutting, and the coating tends to peel off. Table 1 also shows the cutting length leading to chipping. The tool life is defined as the cutting time when the tool cannot be cut due to the crater wear because the crater wear governs the life when the coating does not peel off. In milling in which the feed per tooth exceeds 1 mm, the cutting temperature locally increases, and crater wear tends to occur.
As is clear from Table 1, Examples 3 to 11 of the present invention show remarkable life improvement. All of Comparative Examples 14 to 17 have a short life due to crater wear and film peeling, and this is largely due to improvement in crater wear resistance due to lubrication of the rake face. In addition, Example 12 of the present invention is an example of the (111) orientation, but the cutting time until the life is slightly shorter than that of the (200) orientation of Example 4 of the present invention. In the present invention example 13, the half width was 0.9 degrees, which was shorter than the half value width of 1.3 degrees of the present invention example 4, but in the present invention example 4, the fracture surface of the film was observed by SEM. When observed, it was found to be growing in a columnar shape and to have excellent wear resistance.
[0018]
(Example 3)
Based on the method of Example 2, the coatings of the present invention examples and comparative examples shown in Table 1 were coated on a cemented carbide insert for turning, a tip shape: TNGG110302R, and were provided with four grooves as cutting data and a work material. Using S53C, a cutting speed: 200 m / min, a cutting depth: 1 mm, a feed: 0.12 mm / rev, and a wet process using a water-soluble cutting oil. This is intermittent cutting, and the coating has a tendency to peel easily. In the case where the peeling does not occur, the heat generation increases due to the progress of crater wear, and the flank wear tends to increase. The point in time at which the flank wear value reached 0.1 mm was determined to be the life. Table 2 shows the cutting time until the life.
[0019]
[Table 2]

[0020]
As is clear from the results of Table 2, in Examples 16 to 29 of the present invention, the third CrN and the like were added to TiN and TiB, so that peeling, chipping, and the like did not occur even in intermittent high-speed turning. In addition, in the case of V of the present invention example 22 and the case of Mo of the present invention example 26, the time until the life is slightly shortened. In addition, Zr of Inventive Example 23, Si of Inventive Example 25, and the like have a long life. On the other hand, in Comparative Example 32, the added amount of Cr was too large, and no film peeling occurred, but the life was shortened.
[0021]
【The invention's effect】
As described above, the multilayer hard film-coated tool of the present invention is superior in crater wear resistance as compared with the conventional coated tool, provides a significantly longer tool life in dry high-speed cutting, improves productivity in cutting, and reduces costs. It is extremely effective for reduction and environmental improvement.
[Brief description of the drawings]
FIG. 1 shows a binding energy diffraction peak of Ti and N in an ESCA analysis result of an example of the present invention.
FIG. 2 shows a binding energy diffraction peak of B and N in an ESCA analysis result of the example of the present invention.
FIG. 3 shows the transition of the distance-friction coefficient at room temperature, 400 ° C., and 700 ° C. by a ball-on-disk type wear tester.

Claims

Substrate is a cemented carbide or a TiCN-based cermet, the base body _{_{_{(Ti x B 1-x)}}} (N y O 1-y), where, 0.90 ≦ X ≦ 0.99,0.90 ≦ y ≦ 1.0 and a coating in which at least TiN, TiB and BN are present, wherein the coating has a coefficient of friction against steel of 0.3 to 0.6 in a cutting temperature range. Coated cutting tool.

The coated cutting tool according to claim 1, wherein at least a BO phase is present in the coating.

3. The coated cutting tool according to claim 1, wherein the B content is maximum in a region of less than 500 nm in a depth direction from the outermost surface of the coating.

4. The coated cutting tool according to claim 1, wherein the film has a diffraction peak in X-ray diffraction at a (200) plane, and a diffraction line of the (200) plane has a half-value width of 2θ of 1.0. A coated cutting tool characterized in that it is at least degree.

5. The coated cutting tool according to claim 1, wherein a part of the Ti is selected from the group 4a, 5a, 6a of the periodic table and Al, Si elements excluding Ti by less than 30% by atomic% of metal alone. A coated cutting tool characterized by being replaced by at least one of the following.

The coated cutting tool according to any one of claims 1 to 5, wherein the coated cutting tool is a coating other than the coating, one or more of the periodic table 4a, 5a, 6a group, Al, Si as a metal element and a non-metallic element. A coated cutting tool provided with a film comprising at least one of C, N, and O.