JP2004255488A

JP2004255488A - Surface coated cutting tool and manufacturing method thereof

Info

Publication number: JP2004255488A
Application number: JP2003047006A
Authority: JP
Inventors: Takeshi Fukano; 剛深野
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2003-02-25
Filing date: 2003-02-25
Publication date: 2004-09-16
Anticipated expiration: 2023-02-25
Also published as: JP4084678B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coating cutting tool having excellent chipping resistance and fracture resistance. <P>SOLUTION: This surface coating cutting tool 1 has a base material 5, which is formed with a cutting surface 2 formed into a polygonal nearly-plane shape in the main surface thereof and formed with a flank 3 in side surfaces thereof and of which surface is formed with a cutting blade 4 in a corner part formed by the cutting surface 2 and the adjacent two flanks 3 crossing each other, and the surface of the base material 5 is coated with at least one layer of hard film 6. A part of the surface of the hard film 6 in a range including at least the cutting blade 4 is eliminated without generating a polishing scratch 20. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、鋼、鋳鉄等を切削加工する表面被覆切削工具およびその製造方法に関し、特に切刃強度を高めた表面被覆切削工具およびその製造方法に関する。
【０００２】
【従来の技術】
従来より、鋼、鋳鉄等を切削加工する際に、ＷＣ基超硬合金や、ＴｉＣＮ基サーメット等の母材に、Ｔｉの窒化物、炭化物、または炭窒化物や、Ａｌ_２Ｏ_３、またはＴｉとＡｌの固溶体の窒化物、炭化物、炭窒化物、または炭酸化物等の硬質膜を被覆した表面被覆切削工具（以下、被覆切削工具と呼ぶ）を用いられており、工具寿命の改善が行われている。
【０００３】
また、切削工具の切刃部にホーニング加工、または、チャンファ加工等の刃先処理を施すことによって刃先強度を高め、工具寿命を高める方法も行われている。
【０００４】
一方、特許文献１や特許文献２では、前記被覆切削工具の刃先処理部の硬質膜にラッピング等の機械研磨を施して切刃表面を除去して薄くしたり、または表面を平滑化することで、切刃における硬質膜の靭性、耐衝撃性を高めて工具寿命を向上させることが記載されている。
【０００５】
〔特許文献１〕
特開平２−２１８５２２
〔特許文献２〕
特開昭６４−１６３０２
【０００６】
【発明が解決しようとする課題】
しかしながら、特許文献１および特許文献２の機械研磨によって切刃の硬質膜を除去する方法では、研磨した切刃部分に研摩痕がのこってしまい、研磨痕に応力集中が生じて結果的に切刃の耐欠損性が不十分で工具寿命の延命効果に限界があった。
【０００７】
本発明は上記の問題を解決するものであって、その目的は、切刃の耐欠損性をより高めて、より工具寿命の長い表面被覆切削工具を提供することである。
【０００８】
【課題を解決するための手段】
本発明者は、上記の問題に対して検討した結果、硬質膜を被覆した切削工具の切刃を機械研磨することなく、すなわち、前記刃先処理部において、プラズマを用いたボンバード処理法にて研磨する方法のように研磨による研磨痕をなくすように除去することによって、局所的な応力集中を抑制して切刃強度を高め、耐欠損性が向上することを知見した。
【０００９】
すなわち、本発明の表面被覆切削工具は、母材の表面に、硬質膜を少なくとも１層被覆するとともに、すくい面と逃げ面の交差稜を切刃とする表面被覆切削工具において、前記硬質膜の少なくとも前記切刃部を含む領域に被覆された硬質膜の表面部分を研磨痕が残らないように除去したことを特徴とする表面被覆切削工具。
【００１０】
また、前記母材の主面がすくい面、側面が逃げ面をなすとともに、前記すくい面が多角形の略平板形状をなし、該すくい面と隣接する２つの逃げ面とが交わるコーナー部に切刃を形成してなることが望ましい。
【００１１】
さらに、前記硬質膜の除去量が前記切刃から前記すくい面および前記逃げ面の中央部に向かって暫減していることが望ましい。
【００１２】
また、前記切刃における硬質膜の膜厚が、前記切刃以外の部位における膜厚よりも薄くなっていることが望ましい。
【００１３】
さらに、前記硬質膜の除去された表面でＡｒ、Ｎ、Ｏ、ＴｉおよびＡｌのいずれかの濃度が前記硬質膜の内部よりも高くなっていることが望ましい。
【００１４】
請求項６に記載の表面被覆切削工具の製造方法は、母材のすくい面と逃げ面の交差稜に切刃を形成するとともに、表面に硬質膜を少なくとも１層被覆する表面被覆切削工具の製造方法において、前記硬質膜の少なくとも前記切刃部を含む領域の表面部分をイオンボンバード処理して除去することを特徴とする。
【００１５】
上記表面被覆切削工具の製造方法では、前記硬質膜の少なくとも前記切刃部を含む領域の表面部分にＡｒ、Ｎ、Ｏ、ＴｉおよびＡｌの群から選ばれるいずれか一種以上のイオンを照射して前記イオンボンバード処理してもよい。
【００１６】
【発明の実施の形態】
本発明の被覆切削工具についてその一例であるスローアウェイチップの概略斜視図である図１、図１のスローアウェイチップのコーナー部を拡大した概略斜視図である図３、図１における切刃部付近（Ａ部）の金属顕微鏡（×２５０）写真である図２（ａ）、図１のスローアウェイチップの切刃部付近の拡大断面模式図である図２（ｂ）を用いて説明する。
【００１７】
本発明の被覆切削工具は、母材５の表面に、硬質膜６を少なくとも１層被覆するとともに、すくい面２と逃げ面３の交差稜を切刃４とする表面被覆切削工具１において、硬質膜６の少なくとも切刃４を含む領域の表面部分を研磨痕７が残らないように除去したことを特徴とする表面被覆切削工具であり、図１の表面被覆切削工具は多角形状をなす主面（正方形）にすくい面２および着座面、側面に逃げ面３をそれぞれ有した略平板形状をなし、すくい面２と隣接する２つの逃げ面３とが交わるコーナーに切刃４を設けている。
【００１８】
また、図１の表面被覆切削工具１によれば、図２の断面模式図に示すように、母材５の表面に硬質膜６を少なくとも１層被覆しており、図２の表面被覆切削工具１では、３つの層からなる多層膜にて硬質膜６を形成している。
【００１９】
本発明の被覆切削工具１では、図３に示すように、少なくとも切刃４を含む領域における硬質膜６の表面部分を研磨痕７が残らないように除去することを大きな特徴とするものである。すなわち、切刃４を含む領域における硬質膜６の表面部分のみを除去することによって、切刃４を含む硬質膜６の除去部９における硬質膜６の残留応力を開放することができるため、切刃４の強度を高めることができ、被覆切削工具１の耐チッピング性および耐欠損性を向上させることができるとともに、図４（ａ）に示すような切刃４上の硬質膜６の表面を機械研磨加工にて除去する際に生じる研磨痕２０をなくすことによって、研磨痕２０に応力集中が生じてクラックが発生することがなくなり、被覆切削工具１の耐欠損性がより向上する。すなわち、機械研磨加工にて硬質膜６の表面を除去すると、耐チッピング性は向上するが、クラックの進展などによる欠損に対する耐性は向上しない。ここで本発明における研磨痕２０とは、図４（ａ）に示されるような金属顕微鏡にて観察できる筋状の傷のことを指す。
【００２０】
本発明において硬質膜６の研磨痕が残らないように硬質膜６を除去するには、例えば、イオンを照射して硬質膜６の表面をボンバード処理する方法が好適に採用でき、特に、ボンバード処理を行う方法としては、プラズマを用いて物理蒸着を行う装置内にてＡｒ，ＮおよびＯの群から選ばれるいずれか１種以上のガスを導入し、タングステンフィラメントを加熱することにより炉内をプラズマ状態とし、該プラズマ内に硬質膜６を被覆した工具を載置して、Ａｒ，ＮおよびＯの群から選ばれるいずれか１種以上のイオンを硬質膜６の表面にバイアス電圧をかけて衝突させる方法が、より確実に、かつ、より均一にボンバード処理ができるとともに、硬質膜６の除去量を制御できる点で望ましい。
【００２１】
また、アークイオンプレーティングなどでは、ターゲットにＴｉまたはＴｉＡｌを使用しアーク放電を発生させ、ＴｉイオンおよびまたはＡｌイオンを硬質膜６の表面にバイアス電圧をかけ衝突させる方法も望ましい。また、ターゲット材種には金属及びそれらの合金、例えばＴｉ、ＴｉＡｌ、ＴｉＣｒ、ＴｉＳｉ、Ｃｒ、Ｓｉ、Ａｌまたはそれらに微量な金属（例えばＹ，Ｚｒ，Ｍｇ，Ｃｒ，Ｓｉ，Ｔａ，Ｂ，Ｖ，Ｎｂのうちのいずれか一種の元素）を添加したものなどでも同様の効果が期待できる。
【００２２】
さらに、切刃４上の硬質膜６の表面におけるＡｒ、Ｔｉ、Ｎ、ＯおよびＡｌのいずれかの濃度が硬質膜６の内部と比較して高くなっていることにより、切削の際に被削材との反応による溶着が起こりにくくなり、チッピングおよび刃先の欠損を防ぐことができるため望ましい。
【００２３】
また、切刃４以外の部位での硬質膜６の膜厚ａと比較して、切刃４の硬質膜の膜厚ｂが薄くなっていることが望ましい。硬質膜６の膜厚を薄くすることにより耐欠損性を向上させることができるが、耐摩耗性が低下してしまう。よって、切刃４の硬質膜のみを薄くし、耐摩耗性に関与する逃げ面の膜厚を厚くしておくことで、耐摩耗性を保持したまま切刃４の耐欠損性を改善できる。
【００２４】
さらに、図４（ｂ）に示すように、硬質膜６の除去量が切刃４からすくい面２および逃げ面３の中央部に向かって暫減しており、硬質膜６の除去部と非除去部の境界２１を持たないことが、図４（ｂ）の機械研磨により硬質膜６を除去した従来の研磨方法を施したチップの断面模式図に示すように、硬質膜６を除去した部分と非除去の部分との境界２１の発生による段差や加工不良（図４（ａ））をなくすことができるため、境界２１での応力集中の発生による工具損傷を防ぐことができる点で望ましい。ここで、硬質膜６の除去量は、硬質膜６が単層の場合は硬質膜６の表面の一部のみ、硬質膜６が複層の場合は、最外層の厚み程度で硬質膜６が所望の厚みで残存するように制御するのがよい。
【００２５】
なお、本発明において、母材５としては、ＷＣを主体とし、Ｃｏ等の鉄族金属を主体とする結合相からなる超硬合金や、ＴｉＣまたはＴｉＣＮを主体とし、Ｃｏ、Ｎｉ等の鉄族金属を主体とする結合相からなるサーメット等が好適である。
【００２６】
上述した硬質膜６としては、化学蒸着法や、イオンプレーティング、スパッタリング法、蒸着等の物理蒸着法によって、母材表面にＴｉ等の４ａ、５ａ、６ａ族金属、ＳｉおよびＡｌの群から選ばれる少なくとも１種の窒化物、炭化物、炭窒化物、炭酸化物、炭窒酸化物、酸化物、酸窒化物の単層または二層以上の複層からなる高硬度で耐溶着性に優れるとともに耐欠損性の高い膜からなる。
【００２７】
また、図２（ｂ）に示すように、さらに、母材５の切刃４に砥石やブラシ等を用いてホーニングやチャンファ等の機械加工にて刃先処理を施すことで切刃強度を高め、切削性能を向上させることもできるが、本発明によれば、かかる母材５表面に生じた研磨痕は硬質膜６を成膜することによって埋めることができる。
【００２８】
一方、本発明の表面被覆切削工具を作成するには、まず所定形状に成形、焼成した母材５のコーナー部（切刃部４）にホーニングやチャンファ等の刃先処理を機械研磨加工によって施した後、母材５表面に上述した方法にて硬質膜６を成膜する。そして、硬質膜６の除去を、プラズマを用いて物理蒸着または化学蒸着を行う装置内にて前記硬質膜表面にイオンボンバード処理によって行い、硬質膜６の表面部分を研磨痕が残らないように除去することにより、本発明の表面被覆切削工具１を作成できる。
【００２９】
なお、ボンバード処理の具体的な条件としては、例えばイオンプレーティング、アークイオンプレーティング等のＰＶＤ炉内にて、Ａｒ、Ｎ_２、Ｏ_２ガスを用いて炉内をそれらの１種及び２種以上の雰囲気でタングステンフィラメントを加熱することにより炉内をプラズマ状態として、炉内圧力０．５Ｐａ〜１０Ｐａ、炉内温度２００〜９００℃、バイアス電圧−１００〜−１０００Ｖ、処理時間２ｍｉｎ〜２４０ｍｉｎの条件が好適である。また、アークイオンプレーティングにて、ターゲットにＴｉ、ＴｉＡｌを用いて、アーク放電電流１５０Ａにてアーク放電を発生させ、Ａｒガスを用いて炉内を炉内圧力０．５Ｐａ〜１０Ｐａ、炉内温度２００〜９００℃、バイアス電圧−１００〜−１０００Ｖ、処理時間２ｍｉｎ〜２４０ｍｉｎの条件が好適である。
【００３０】
ここで、上記ボンバードによる硬質膜６の除去方法では、ボンバード処理を行う際にプラズマが被処理物のエッジに集中しやすいため、エッジが中央部よりもプラズマによって除去されやすいために、容易に上述した硬質膜６の構成を作製することができる。
【００３１】
【実施例】
（実施例）
平均粒径１．５μｍの炭化タングステン（ＷＣ）粉末、平均粒径１．２μｍの金属コバルト（Ｃｏ）粉末および平均粒径２．０μｍの炭化タンタル（ＴａＣ）、炭化チタン（ＴｉＣ）、炭化ニオブ（ＮｂＣ）を添加、混合して、プレス成形によりスローアウェイチップ形状（ＣＮＭＡ１２０４１２）に成形した後、脱バインダ処理を施し、さらに、１０００℃を越えると３℃／分の速度で昇温して、０．０１Ｐａの真空中、１５００℃で１時間焼成して炭化タングステン基超硬合金基体を作製した。
【００３２】
得られた炭化タングステン基超硬合金基体の切刃部分をブラシ加工にて半径８０μｍのＲ面ホーニング加工を施した後、ＣＶＤ法により母材側よりＴｉＣＮ−Ａｌ_２Ｏ_３−ＴｉＮの膜構成からなる硬質膜を順次成膜した。
【００３３】
そして、アークイオンプレーティング装置内に上記スローアウェイチップを載置して、タングステンフィラメントを加熱し、バイアス電圧５００Ｖ、炉内温度５００℃、表１に示すガスを炉内圧３Ｐａで、表１に示す時間ボンバード処理を施し、硬質膜表面の除去を行った。（試料Ｎｏ．１〜３）
また、アークイオンプレーティング装置内に上記スローアウェイチップを載置して、バイアス電圧８００Ｖ、炉内温度５００℃、表１に示すガスを炉内圧３Ｐａで、アーク放電電流１５０Ａにてボンバード処理を施し、硬質膜表面の除去を行った。（試料Ｎｏ．４、５）
また、試料Ｎｏ．６は硬質膜の除去を行わず、試料Ｎｏ．７はボンバード処理ではなく、ブラシ加工によって切刃の硬質膜を除去した試料である。
【００３４】
上記方法にて作製した試料Ｎｏ．１〜７の切刃（コーナー部）表面について、切刃の研磨痕の有無を金属顕微鏡にて確認した。また、各試料の断面について金属顕微鏡観察を行い、切刃（コーナー部）での最も薄い膜厚およびすくい面中央での膜厚、および切刃の断面形状より、硬質膜の除去部と非除去部の境界の有無を観察した。結果は表１に示した。
【００３５】
さらに、試料Ｎｏ．１〜７の硬質膜の切刃部分の断面についてＡｒ、Ｏ、Ｎ、Ｔｉ、Ａｌの濃度分布をＥＰＭＡにて分析を行った結果、それぞれの試料について、表１に示される検出元素が硬質膜の内部よりも硬質膜を除去した部分の表面に特に多く検出された。
【００３６】
また試料Ｎｏ．１〜７にて下記の条件で切削試験を行い、耐欠損性および耐チッピング性の評価を行った。結果は表１に示した。
【００３７】
切削条件
耐欠損性試験
切削方法：旋削
被削材：ＳＣＭ４４０溝入れ
切削速度：１３０ｍ／ｍｉｎ
切り込み：２ｍｍ
送り：０．４ｍｍ／ｒｅｖ
切削状態：湿式
試料が損傷するまでの切削時間を測定。
【００３８】
耐チッピング性試験
切削方法：旋削
被削材：ＳＣＭ４４０溝入れ
切削速度：２００ｍ／ｍｉｎ
切り込み：２ｍｍ
送り：０．２５ｍｍ／ｒｅｖ
切削状態：乾式
耐チッピング性試験：試料をそれぞれ１０個ずつ試験し、５分間切削した後に刃先の状態をチェックし、１０個中何個にチッピングが発生したかを確認する。
【００３９】
【表１】

表１より、ボンバードで刃先処理を行った試料Ｎｏ．１〜５では、切削試験において、耐欠損性試験による工具寿命も長く、チッピングの発生もほとんど見られなかった。
【００４０】
一方、刃先処理を行わなかった試料Ｎｏ．６では、刃先のチッピングが発生し耐欠損性も悪かった。
【００４１】
また、刃先処理をブラシで行い、研磨痕が残っている試料Ｎｏ．７では、チッピングの発生はある程度抑えられていたが、耐欠損性においては十分な性能ではなかった。
【００４２】
【発明の効果】
以上詳述したように本発明の表面被覆切削工具によれば、硬質膜の少なくとも切刃部を含む領域に被覆された硬質膜の表面部分を研磨痕が残らないように除去することによって、刃先強度を高めて耐チッピング性を向上させるとともに、研磨痕に発生する応力集中をなくし、耐欠損性を向上させることができる。
【００４３】
また、本発明の表面被覆切削工具の製造方法によれば、少なくとも切刃部を含む領域の硬質膜の表面部分をイオンボンバード処理して除去することから、刃先強度を高めて耐チッピング性を容易に向上させることができるとともに、研磨痕に発生する応力集中をなくして耐欠損性を容易に向上させることができる。
【図面の簡単な説明】
【図１】本発明の表面被覆切削工具の概略斜視図である。
【図２】（ａ）本発明の表面被覆切削工具の図１におけるＡ部の金属顕微鏡写真（×２５０）である。
（ｂ）本発明の表面被覆切削工具の切刃付近における断面拡大模式図である。
【図３】本発明の被覆切削工具の図１におけるＡ部の拡大概略図である。
【図４】（ａ）本発明の範囲外の表面被覆切削工具の図１におけるＡ部の金属顕微鏡写真（×２５０）である。
（ｂ）本発明の範囲外の表面被覆切削工具の切刃付近における断面拡大模式図である。
【符号の説明】
１：表面被覆切削工具
２：すくい面
３：逃げ面
４：切刃
５：母材
６：硬質膜
９：硬質膜の除去部
２０：研磨痕
２１：境界
ａ：切刃以外の硬質膜の膜厚
ｂ：切刃の硬質膜の膜厚[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface-coated cutting tool for cutting steel, cast iron, and the like, and a method for manufacturing the same, and more particularly, to a surface-coated cutting tool with enhanced cutting edge strength and a method for manufacturing the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, when cutting steel, cast iron, or the like, a base material such as a WC-based cemented carbide or a TiCN-based cermet is added with a nitride, carbide, or carbonitride of Ti, Al ₂ O ₃ , or Ti. And a surface-coated cutting tool (hereinafter referred to as a coated cutting tool) coated with a hard film such as a solid solution nitride, carbide, carbonitride or carbonate of Al, and the tool life is improved. ing.
[0003]
Further, there is also a method in which the cutting edge portion of a cutting tool is subjected to a cutting edge treatment such as honing or chamfering to increase the cutting edge strength and extend the tool life.
[0004]
On the other hand, in Patent Literature 1 and Patent Literature 2, the hard film of the cutting edge processing section of the coated cutting tool is subjected to mechanical polishing such as lapping to remove the cutting blade surface to make it thinner or to smooth the surface. It describes that the toughness and impact resistance of the hard film at the cutting edge are increased to improve the tool life.
[0005]
[Patent Document 1]
JP-A-2-218522
[Patent Document 2]
JP-A-64-16302
[0006]
[Problems to be solved by the invention]
However, in the method of removing the hard film of the cutting edge by mechanical polishing disclosed in Patent Literature 1 and Patent Literature 2, polishing marks are left on the polished cutting blade portions, and stress concentration occurs in the polishing marks, resulting in the cutting edge. Was insufficient in fracture resistance, and there was a limit to the tool life extension effect.
[0007]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a surface-coated cutting tool having a longer tool life by further improving the chipping resistance of a cutting edge.
[0008]
[Means for Solving the Problems]
As a result of studying the above problem, the present inventor found that the cutting edge of the cutting tool coated with the hard film was not mechanically polished, that is, the cutting edge portion was polished by a bombardment method using plasma. It has been found that, by removing the polishing marks by polishing as in the method described above, the local stress concentration is suppressed, the cutting edge strength is increased, and the fracture resistance is improved.
[0009]
That is, the surface-coated cutting tool of the present invention is a surface-coated cutting tool that coats at least one layer of a hard film on the surface of a base material and that uses a crossing edge between a rake face and a flank as a cutting edge. A surface-coated cutting tool, wherein at least a surface portion of a hard film coated on a region including the cutting edge portion is removed so as not to leave polishing marks.
[0010]
Further, the main surface of the base material forms a rake face and the side faces form a flank face, and the rake face has a substantially flat plate shape of a polygon, and is cut at a corner where the rake face and two adjacent flank faces intersect. It is desirable to form a blade.
[0011]
Further, it is desirable that the removal amount of the hard film is reduced gradually from the cutting edge toward the center of the rake face and the flank.
[0012]
In addition, it is desirable that the thickness of the hard film at the cutting edge is smaller than the thickness at a portion other than the cutting edge.
[0013]
Further, it is preferable that the concentration of any of Ar, N, O, Ti, and Al on the surface from which the hard film has been removed is higher than that inside the hard film.
[0014]
A method of manufacturing a surface-coated cutting tool according to claim 6, wherein a cutting edge is formed at an intersection between a rake face and a flank of a base material and at least one hard film is coated on the surface. In the method, at least a surface portion of a region including the cutting edge portion of the hard film is removed by ion bombardment.
[0015]
In the method of manufacturing a surface-coated cutting tool, the hard film is irradiated with at least one ion selected from the group consisting of Ar, N, O, Ti, and Al on a surface portion of a region including at least the cutting edge portion. The ion bombardment treatment may be performed.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic perspective view of a throwaway tip as an example of the coated cutting tool of the present invention, FIG. 3 is an enlarged perspective view of a corner portion of the throwaway tip of FIG. This will be described with reference to FIG. 2A, which is a metallographic (× 250) photograph of (A), and FIG. 2B, which is an enlarged schematic cross-sectional view of the vicinity of the cutting edge of the throw-away tip of FIG.
[0017]
The coated cutting tool according to the present invention is characterized in that, in the surface-coated cutting tool 1 in which the surface of the base material 5 is coated with at least one hard film 6 and the intersection ridge between the rake face 2 and the flank 3 is a cutting edge 4, A surface-coated cutting tool in which at least a surface portion of a region including the cutting edge 4 of the film 6 is removed so that polishing marks 7 do not remain. The surface-coated cutting tool in FIG. 1 has a polygonal main surface. The rake face 2 has a substantially flat plate shape having a rake face 2, a seating face, and a flank 3 on its side face, and a cutting edge 4 is provided at a corner where the rake face 2 and two adjacent flank 3 intersect.
[0018]
Further, according to the surface-coated cutting tool 1 of FIG. 1, as shown in the schematic cross-sectional view of FIG. 2, at least one hard film 6 is coated on the surface of the base material 5. In No. 1, the hard film 6 is formed of a multilayer film composed of three layers.
[0019]
As shown in FIG. 3, the coated cutting tool 1 of the present invention is characterized in that at least the surface portion of the hard film 6 in a region including the cutting edge 4 is removed so that polishing marks 7 do not remain. . That is, by removing only the surface portion of the hard film 6 in the region including the cutting edge 4, the residual stress of the hard film 6 in the removed portion 9 of the hard film 6 including the cutting edge 4 can be released. The strength of the blade 4 can be increased, the chipping resistance and the chipping resistance of the coated cutting tool 1 can be improved, and the surface of the hard film 6 on the cutting blade 4 as shown in FIG. Eliminating the polishing marks 20 generated when removing by the mechanical polishing process eliminates the occurrence of cracks due to stress concentration in the polishing marks 20 and further improves the chipping resistance of the coated cutting tool 1. That is, when the surface of the hard film 6 is removed by mechanical polishing, the chipping resistance is improved, but the resistance to defects due to cracks and the like is not improved. Here, the polishing marks 20 in the present invention refer to streak-like scratches that can be observed with a metal microscope as shown in FIG.
[0020]
In the present invention, in order to remove the hard film 6 so that polishing marks of the hard film 6 do not remain, for example, a method of bombarding the surface of the hard film 6 by irradiating ions can be suitably used. Is performed by introducing at least one gas selected from the group consisting of Ar, N, and O into an apparatus for performing physical vapor deposition using plasma, and heating the tungsten filament to form a plasma in the furnace. In this state, a tool coated with the hard film 6 is placed in the plasma, and any one or more ions selected from the group consisting of Ar, N and O are applied to the surface of the hard film 6 by applying a bias voltage to the plasma. This method is desirable in that the bombarding process can be performed more reliably and more uniformly, and the removal amount of the hard film 6 can be controlled.
[0021]
Further, in arc ion plating or the like, it is also desirable to use a method in which Ti or TiAl is used as a target to generate an arc discharge, and a Ti voltage and / or an Al ion collide with the surface of the hard film 6 by applying a bias voltage. The target material includes metals and their alloys, for example, Ti, TiAl, TiCr, TiSi, Cr, Si, Al, or trace metals (for example, Y, Zr, Mg, Cr, Si, Ta, B, V). , Nb), the same effect can be expected.
[0022]
Further, since the concentration of any of Ar, Ti, N, O, and Al on the surface of the hard film 6 on the cutting edge 4 is higher than that inside the hard film 6, the surface of This is desirable because welding due to the reaction with the material is less likely to occur and chipping and chipping of the cutting edge can be prevented.
[0023]
Further, it is desirable that the thickness b of the hard film of the cutting edge 4 is smaller than the thickness a of the hard film 6 at a portion other than the cutting edge 4. Although the fracture resistance can be improved by reducing the thickness of the hard film 6, the wear resistance is reduced. Therefore, by making only the hard film of the cutting edge 4 thin and increasing the thickness of the flank surface related to the wear resistance, the chipping resistance of the cutting edge 4 can be improved while maintaining the wear resistance.
[0024]
Further, as shown in FIG. 4B, the removal amount of the hard film 6 is reduced from the cutting edge 4 to the center of the rake face 2 and the flank 3, so that the removal amount of the hard film 6 is As shown in FIG. 4 (b), a portion where the hard film 6 is removed is shown in a schematic cross-sectional view of a chip subjected to a conventional polishing method in which the hard film 6 is removed by mechanical polishing. Since a step and a processing defect (FIG. 4A) due to the generation of the boundary 21 between the portion and the non-removed portion can be eliminated, it is desirable in that the tool damage due to the occurrence of stress concentration at the boundary 21 can be prevented. Here, the removal amount of the hard film 6 is only a part of the surface of the hard film 6 when the hard film 6 is a single layer, and when the hard film 6 is a multilayer, the thickness of the hard film 6 is about the thickness of the outermost layer. It is preferable to control so as to remain at a desired thickness.
[0025]
In the present invention, as the base material 5, a cemented carbide mainly composed of a binder phase mainly composed of WC and an iron group metal such as Co, or an iron group mainly composed of TiC or TiCN and composed of Co or Ni Cermet or the like composed of a binder phase mainly composed of a metal is preferable.
[0026]
The hard film 6 is selected from the group consisting of 4a, 5a, 6a group metals such as Ti, Si and Al on the surface of the base material by a physical vapor deposition method such as a chemical vapor deposition method, an ion plating method, a sputtering method, and vapor deposition. It has high hardness, excellent welding resistance and high resistance consisting of a single layer or multiple layers of at least one kind of nitride, carbide, carbonitride, carbonate, carbonitride, oxide and oxynitride. It consists of a highly defective film.
[0027]
Further, as shown in FIG. 2B, the cutting edge 4 of the base material 5 is further subjected to a cutting edge treatment by machining such as honing or chamfer using a grindstone or a brush to increase the cutting edge strength. Although the cutting performance can be improved, according to the present invention, the polishing marks generated on the surface of the base material 5 can be filled by forming the hard film 6.
[0028]
On the other hand, in order to produce the surface-coated cutting tool of the present invention, first, a corner portion (cutting edge portion 4) of a base material 5 formed and fired into a predetermined shape was subjected to a cutting edge treatment such as honing or chamfering by mechanical polishing. Thereafter, the hard film 6 is formed on the surface of the base material 5 by the method described above. Then, the hard film 6 is removed by ion bombardment on the surface of the hard film in an apparatus for performing physical vapor deposition or chemical vapor deposition using plasma, and the surface of the hard film 6 is removed so that polishing marks do not remain. By doing so, the surface-coated cutting tool 1 of the present invention can be created.
[0029]
As specific conditions for the bombarding treatment, for example, in a PVD furnace such as ion plating and arc ion plating, one or two types of these are performed using Ar, N ₂ , and O ₂ gas in the furnace. By heating the tungsten filament in the above atmosphere, the inside of the furnace is turned into a plasma state, the furnace pressure is 0.5 Pa to 10 Pa, the furnace temperature is 200 to 900 ° C., the bias voltage is −100 to −1000 V, and the processing time is 2 min to 240 min. Is preferred. Further, in arc ion plating, an arc discharge was generated at an arc discharge current of 150 A using Ti and TiAl as targets, and a furnace pressure of 0.5 Pa to 10 Pa and a furnace temperature of Ar using Ar gas were used. The conditions are preferably 200 to 900 ° C., a bias voltage of −100 to −1000 V, and a processing time of 2 to 240 min.
[0030]
Here, in the method of removing the hard film 6 by the bombardment, the plasma is easily concentrated on the edge of the object to be processed when the bombardment process is performed. The structure of the hard film 6 can be manufactured.
[0031]
【Example】
(Example)
Tungsten carbide (WC) powder having an average particle size of 1.5 μm, metallic cobalt (Co) powder having an average particle size of 1.2 μm, tantalum carbide (TaC) having an average particle size of 2.0 μm, titanium carbide (TiC), niobium carbide ( NbC) was added, mixed, and formed into a throw-away chip shape (CNMA120412) by press molding, followed by binder removal treatment. When the temperature exceeded 1000 ° C., the temperature was raised at a rate of 3 ° C./min. It was fired at 1500 ° C. for 1 hour in a vacuum of 0.01 Pa to produce a tungsten carbide-based cemented carbide substrate.
[0032]
After the cutting edge portion of the obtained tungsten carbide-based cemented carbide substrate is subjected to R-face honing with a radius of 80 μm by brushing, the film configuration of TiCN—Al ₂ O ₃ —TiN is applied from the base material side by the CVD method. Hard films were sequentially formed.
[0033]
Then, the throw-away tip is placed in an arc ion plating apparatus, the tungsten filament is heated, and a bias voltage of 500 V, a furnace temperature of 500 ° C., and a gas shown in Table 1 at a furnace pressure of 3 Pa are shown in Table 1. The bombardment treatment was performed for a time to remove the hard film surface. (Sample Nos. 1 to 3)
Further, the throw-away tip was placed in an arc ion plating apparatus, and bombarding was performed at a bias voltage of 800 V, a furnace temperature of 500 ° C., a gas shown in Table 1 at a furnace pressure of 3 Pa, and an arc discharge current of 150 A. Then, the hard film surface was removed. (Sample Nos. 4, 5)
Further, the sample No. Sample No. 6 did not remove the hard film, and Reference numeral 7 denotes a sample from which the hard film of the cutting edge has been removed by brushing, not by bombarding.
[0034]
The sample No. prepared by the above method was used. With respect to the surfaces of the cutting blades (corner portions) 1 to 7, the presence or absence of polishing marks on the cutting blades was confirmed with a metallographic microscope. In addition, the cross section of each sample was observed with a metallographic microscope, and based on the thinnest film thickness at the cutting edge (corner portion), the film thickness at the center of the rake face, and the cross-sectional shape of the cutting edge, the hard film was removed and not removed. The presence or absence of the boundary of the part was observed. The results are shown in Table 1.
[0035]
Further, the sample No. As a result of analyzing the concentration distributions of Ar, O, N, Ti, and Al by EPMA for the cross sections of the cutting edges of the hard films 1 to 7, the detection elements shown in Table 1 were obtained for each sample. Was more frequently detected on the surface of the portion where the hard film was removed than on the inside.
[0036]
Sample No. A cutting test was performed on each of Nos. 1 to 7 under the following conditions to evaluate chipping resistance and chipping resistance. The results are shown in Table 1.
[0037]
Cutting conditions Fracture resistance test Cutting method: Turning work material: SCM440 Grooving Cutting speed: 130 m / min
Cut: 2mm
Feed: 0.4mm / rev
Cutting condition: Measure the cutting time until the wet sample is damaged.
[0038]
Chipping resistance test Cutting method: Turning work material: SCM440 Grooving Cutting speed: 200 m / min
Cut: 2mm
Feed: 0.25mm / rev
Cutting condition: Dry chipping resistance test: Ten samples were tested each, and after cutting for 5 minutes, the condition of the cutting edge was checked to confirm how many of the ten chips had chipping.
[0039]
[Table 1]

From Table 1, it can be seen that the sample no. In Nos. 1 to 5, in the cutting test, the tool life in the fracture resistance test was long, and almost no occurrence of chipping was observed.
[0040]
On the other hand, the sample No. In No. 6, chipping of the cutting edge occurred, and chipping resistance was poor.
[0041]
Further, the blade edge treatment was performed with a brush, and the sample No. In No. 7, although the occurrence of chipping was suppressed to some extent, the chipping resistance was not sufficient.
[0042]
【The invention's effect】
As described above in detail, according to the surface-coated cutting tool of the present invention, by removing the surface portion of the hard film coated on at least the region including the cutting edge portion of the hard film so that no polishing mark remains, the cutting edge It is possible to improve the chipping resistance by increasing the strength, to eliminate the stress concentration generated in the polishing marks, and to improve the chipping resistance.
[0043]
Further, according to the method of manufacturing a surface-coated cutting tool of the present invention, since the surface portion of the hard film in at least the region including the cutting edge portion is removed by ion bombardment, the cutting edge strength is increased and chipping resistance is easily increased. In addition, the stress concentration generated in the polishing marks can be eliminated, and the fracture resistance can be easily improved.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a surface-coated cutting tool of the present invention.
2 (a) is a metal micrograph (× 250) of a portion A in FIG. 1 of the surface-coated cutting tool of the present invention.
(B) It is a cross-sectional enlarged schematic diagram in the vicinity of the cutting edge of the surface-coated cutting tool of the present invention.
FIG. 3 is an enlarged schematic view of a portion A in FIG. 1 of the coated cutting tool of the present invention.
FIG. 4 (a) is a metal micrograph (× 250) of part A in FIG. 1 of a surface-coated cutting tool outside the scope of the present invention.
(B) It is a cross-sectional enlarged schematic diagram in the vicinity of the cutting edge of the surface-coated cutting tool outside the scope of the present invention.
[Explanation of symbols]
1: surface coated cutting tool 2: rake face 3: flank face 4: cutting edge 5: base material 6: hard film 9: removal portion 20 of hard film: polishing mark 21: boundary a: film of hard film other than cutting edge Thickness b: thickness of hard film of cutting edge

Claims

In a surface-coated cutting tool in which at least one hard film is coated on a surface of a base material and an intersection between a rake face and a flank is a cutting edge, a surface portion of at least the region including the cutting edge portion of the hard film. A surface-coated cutting tool characterized in that polishing marks are removed so as not to leave polishing marks.

The main surface of the base material is a rake face, the side faces form a flank face, the rake face has a substantially flat plate shape of a polygon, and a cutting edge is formed at a corner where the rake face and two adjacent flank faces intersect. The surface-coated cutting tool according to claim 1, wherein the cutting tool is formed.

3. The surface-coated cutting tool according to claim 1, wherein an amount of removal of the hard film decreases from the cutting edge toward a center of the rake face and the flank. 4.

The surface-coated cutting tool according to any one of claims 1 to 3, wherein the thickness of the hard film on the cutting edge is smaller than the thickness of a portion other than the cutting edge.

The concentration of any of Ar, N, O, Ti and Al on the surface from which the hard film has been removed is higher than that inside the hard film. Surface coated cutting tools.

In a method of manufacturing a surface-coated cutting tool in which a cutting edge is formed at an intersection of a rake face and a flank of a base material and at least one hard film is coated on a surface, a region including at least the cutting edge portion of the hard film. A method for producing a surface-coated cutting tool, characterized in that the surface portion of the cutting tool is removed by ion bombardment.

The ion bombarding is performed by irradiating at least one kind of ion selected from the group consisting of Ar, N, O, Ti and Al onto a surface portion of at least the region including the cutting edge portion of the hard film. A method for producing a surface-coated cutting tool according to claim 6.