JP3814051B2

JP3814051B2 - Coated hard alloy tool

Info

Publication number: JP3814051B2
Application number: JP14884997A
Authority: JP
Inventors: 秀樹森口; 明彦池ケ谷
Original assignee: Sumitomo Electric Hardmetal Corp
Current assignee: Sumitomo Electric Hardmetal Corp
Priority date: 1996-06-12
Filing date: 1997-06-06
Publication date: 2006-08-23
Anticipated expiration: 2017-06-06
Also published as: JPH1071507A

Description

【０００１】
【発明の属する技術分野】
本発明は、被覆硬質合金工具に関し、特に、硬質合金基材への被覆膜の膜厚を増大するとともに、被覆処理後の切れ刃稜線部の形状を特定する表面処理を施すことにより、耐欠損性を損なうことなく耐摩耗性を向上する技術に関するものである。
【０００２】
【従来の技術】
従来、金属材料を切削する工具の材質としては、超硬合金（ＷＣ−Ｃｏ合金もしくはＷＣ−Ｃｏ合金にＴｉやＴａ，Ｎｂの炭窒化物を添加した合金）が用いられてきた。ところが近年は、切削条件が高速化してきた結果、超硬合金やサーメットからなる基材、あるいはアルミナ系や窒化珪素系のセラミックスからなる基材の表面に、ＣＶＤ(Chemical Vapor Deposition) 法やＰＶＤ(Physical Vapor Deposition) 法によって種々の材料の被覆膜を３〜１５μｍの厚さに被覆した硬質合金工具の使用が増大している。その被覆膜の材質としては、元素周期律表ＩＶａ，Ｖａ，ＶＩａ族金属およびＡｌなどの、炭化物，窒化物，炭窒化物，炭酸化物，ホウ窒化物，または酸化物、もしくはこれらの固溶体が用いられている。また、ダイヤモンドあるいはダイヤモンド状炭素からなる被覆膜も用いられている。
【０００３】
これらの被覆硬質合金工具は、硬質合金基材をホーニング，チャンファリング，またはそれらの複合処理により面取り加工することによって刃先形状を形成し、それによって、破壊しやすい硬質合金の耐欠損性を補った上で、被膜処理を行なっている。また、耐摩耗性の向上には、被覆膜を多層化する公知の技術が存在する。
【０００４】
また、特公平５−９２０１号公報には、硬質合金基材表面への被覆処理後の表面処理によって、切れ刃稜線部の被覆膜の一部を除去することによって、刃先強度を改善し、耐摩耗性の向上を図る技術が開示されている。
【０００５】
【発明が解決しようとする課題】
しかしながら、上記各従来の被覆硬質合金工具では、硬質合金基材の刃先処理量を大きくすると、耐欠損性は改善されるものの耐摩耗性が低下し、刃先処理量を小さくすると、耐摩耗性は向上するものの耐欠損性が低下するという相反する現象による問題点を十分に回避することはできていなかった。また、特公平５−９２０１号公報に記載の技術においても、被覆膜の除去の度合によって、必ずしも耐欠損性および耐摩耗性の双方の向上を図ることができない場合があるという問題があった。
【０００６】
本発明は、被覆硬質合金工具の刃先において、硬質合金基材の形状および被覆層の形状の双方を最適化することによって、耐欠損性を損なうことなく耐摩耗性を改善した、長寿命の被覆硬質合金工具を提供することを目的とする。
【０００７】
また、本発明は、耐欠損性および耐摩耗性の双方を改善した、長寿命の被覆硬質合金工具を提供することを目的とする。
【０００８】
【課題を解決するための手段】
上記目的を達成する本発明の被覆硬質合金工具は、逃げ面とすくい面とのつなぎ部をなす切れ刃稜線部に刃先処理部を有する硬質合金基材と、該硬質合金基材の表面に被覆された被覆膜とを備え、前記被覆膜の表面の切れ刃稜線部に表面処理部を有している。この被覆硬質合金工具の特徴は、硬質合金基材の表面において逃げ面と刃先処理部との境界部に形成される凸曲面の曲率半径をＲｓ１、前記被覆膜の表面において逃げ面と表面処理部との境界部に形成される凸曲面の曲率半径をＲｃ１、表面処理部以外の領域の被覆膜の平均膜厚をｄとしたとき、Ｒｃ１／（Ｒｓ１＋ｄ）＜１．０となるように被覆膜を形成したことにある。
【０００９】
この構造によれば、Ｒｃ１／（Ｒｓ１＋ｄ）＜１．０となるように被覆膜が形成されていることにより、耐欠損性を損なうことなく、耐摩耗性の向上を図ることができる。
【００１０】
本発明者らが硬質合金基材および被覆層の双方の刃先の曲率半径の関係に着目して、上記本発明の構造を見出した経緯は、次のとおりである。
【００１１】
被覆硬質合金工具の耐欠損性は、被覆母材である硬質合金基材の材質によって決まる靱性、および被覆前の硬質合金基材の刃先処理形状によって支配されることはすでに知られている。通常、硬質合金基材の刃先形状は、アルミナやＺｒ０₂ などの酸化物を被覆した場合、切れ刃稜線をなす角部において被覆膜厚が極大化しやすくなる。そのため、逃げ面と表面処理された切れ刃部との境界における被覆膜表面の曲率半径をＲｃ１，それに対応する硬質合金基材表面の曲率半径をＲｓ１，および表面処理部以外の領域の被覆膜の平均膜厚をｄとしたときに、これらがＲｃ１＞Ｒｓ１＋ｄをみたす関係になっていることが多い。ただし、アルミナ膜のコーティング時に原料ガスとしてＨ₂ Ｓを用いて、角部での膜厚の極大化を抑制する技術を用いれば、硬質合金基材の刃先上にＲｃ１＝Ｒｓ１＋ｄの関係をみたすほぼ均一な膜厚の被覆膜を形成することが可能である。
【００１２】
曲率半径Ｒｃ１の大小が工具としての切れ味を決定付けるため、被覆処理を施さない場合に比較して、被覆処理を施した後の工具の切れ味は若干低下し、耐摩耗性も同時に劣化する。この傾向は、被覆膜の膜厚が増大するほど大きくなり、被覆膜厚が１５μｍ以上において特に著しいことが判明した。
【００１３】
そこで、靱性を維持したまま耐摩耗性を向上させるために、硬質合金基材の逃げ面と刃先処理された切れ刃部との境界における曲率半径Ｒｓ１を従来の工具よりも大きくするとともに、従来よりも被覆膜厚が大きくなるように被覆処理を行なって、その後に被覆膜の表面処理を行なうことを試みた。
【００１４】
その際において、Ｒｃ１を小さくし、Ｒｃ１＜Ｒｓ１＋ｄの関係を満たすような刃先形状になるように刃先処理を施すことにより、耐欠損性を損なうことなく、耐摩耗性の向上を図ることができることを発見したものである。
【００１５】
本発明の被覆硬質合金工具は、上記構造において、硬質合金基材の表面においてすくい面と刃先処理部との境界部に形成される凸曲面の曲率半径をＲｓ２、前記被覆膜の表面においてすくい面と表面処理部との境界部に形成される凸曲面の曲率半径をＲｃ２としたときに、さらにＲｃ２／（Ｒｓ２＋ｄ）＞１．０となるように被覆膜が形成されていることが好ましい。このように、Ｒｃ１／（Ｒｓ１＋ｄ）＜１．０およびＲｃ２／（Ｒｓ２＋ｄ）＞１．０の両方の関係を満たすことにより、耐欠損性および耐摩耗性の双方を向上することができる。
【００１６】
また、耐欠損性および耐摩耗性の向上の効果を一層発揮させるためには、Ｒｃ１／（Ｒｓ１＋ｄ）が０．２以上０．８以下になるように、また、Ｒｃ２／（Ｒｓ２＋ｄ）が２．０以上５．０以下になるように形成することが好ましい。
【００１７】
【発明の実施の形態】
以下、本発明の実施の形態について、図面に基づいて説明する。
【００１８】
まず、図１を参照して、逃げ面４とすくい面６とのつなぎ部をなす切れ刃稜線部３を刃先処理した硬質合金基材１表面に被覆膜２を被覆処理した後、さらに表面処理を施して、被覆膜２の表面の切れ刃稜線部３に表面処理部を形成することにより、図１に示す断面形状を有する被覆硬質合金工具が形成される。
【００１９】
このようにして形成された、図１に示す被覆硬質合金工具においては、硬質合金基材１表面において逃げ面４と刃先処理部との境界部に形成される凸曲面の曲率半径をＲｓ１、被覆膜２の表面において逃げ面４と表面処理部との境界部に形成される凸曲面の曲率半径をＲｃ１、表面処理部以外の領域の被覆膜２の平均膜厚をｄとしたとき、Ｒｃ１／（Ｒｓ１＋ｄ）＜１．０およびＲｃ２／（Ｒｓ２＋ｄ）＞１．０の関係を満たすように、硬質合金基材１の刃先処理部および被覆膜２表面の表面処理部が形成されている。
【００２０】
このように、Ｒｃ１／（Ｒｓ１＋ｄ）＜１．０およびＲｃ２／（Ｒｓ２＋ｄ）＞１．０の両方の関係を満たすことによって、耐欠損性および耐摩耗性の双方を向上することができる。また、少なくともＲｃ１／（Ｒｓ１＋ｄ）＜１．０のみの関係を満たすことによっても、耐欠損性を損なうことなく、耐摩耗性を向上することができる。
【００２１】
これらの不等式によって表わされる関係は、図２に示されたスローアウエイチップ７の切れ刃３のノーズＲ部８の切れ刃のすべてにわたって成り立つように形成されていることが好ましいが、その一部において成り立つ場合であっても、ある程度の効果が発揮される。
【００２２】
なお、曲率半径Ｒｃ１の値は、次のようにして測定される。まず、被覆膜２を表面処理した被覆硬質合金工具を切れ刃に対して垂直な断面で切断後、その切断面を樹脂に埋め込む。これに平面研削と鏡面研摩を施した後、エッチングし、その後さらに、必要に応じて金蒸着を行なう。次に、そのようにして形成された試料の切れ刃稜線部付近を、光学顕微鏡によって、１５００倍の倍率で撮影する。次に、撮影された写真を画像処理装置に取り込み、その画像上で、逃げ面側の被覆膜の未処理部と表面処理部との境界部を起点（Ｏ点）とし、このＯ点から被覆膜の表面上をすくい面側へ５μｍ離れた点（Ａ点）、および、Ｏ点から被覆膜の表面上を逃げ面側へ５μｍ離れた点（Ｂ点）を決定する。このようにして決定したＯ点，Ａ点およびＢ点の（ｘ，ｙ）座標をもとに、これらの３点を通る円の半径を計算することにより、曲率半径Ｒｃ１の値が求められる。曲率半径Ｒｃ２，Ｒｓ１，Ｒｓ２についても、同様の方法によって求められる。
【００２３】
被覆膜２の表面処理の方法としては、ダイヤモンドやＳｉＣなどの硬質物質を含有したブラシや弾性砥石などによる処理方法が適しているが、これらの方法に限定されるものではない。ブラシや砥石の回転スピード，硬さ，工具のすくい面に対する処理角度など、あるいは砥石の加圧力，切削油の有無などによって、表面処理後の刃先形状が左右される。そのため、所望の刃先形状を得るためには、これらの条件を適正に設定することが必要となる。
【００２４】
硬質合金基材１の材質としては、超硬合金のほか、サーメットやセラミック（たとえば窒化珪素や繊維強化セラミック（ＦＲＣ））を用いることができ、これらの材料が傾斜(gradient)組成を有していてもよい。傾斜組成材料としては、表面に強靱層やセラミック層を有するタイプのものが利用できる。被覆層２を構成する材料としては、元素の周期律表のＩＶａ，Ｖａ，ＶＩａ族金属（すなわちＴｉ，Ｚｒ，Ｈｆ；Ｖ，Ｎｂ，Ｔａ；Ｃｒ，Ｍｏ，Ｗ）またはＡｌ等の、炭化物，窒化物，炭窒化物，炭酸化物，ホウ窒化物または酸化物、あるいはそれらの固溶体があげられる。また、被覆層２の材質として、ダイヤモンドやダイヤモンド状炭素等も用いられる。被覆層２は、ＣＶＤ法やＰＶＤ法等により形成される。
【００２５】
本実施例の被覆硬質合金工具においては、硬質合金基材の被覆膜の平均膜厚が１５μｍ以上であり、かつ、表面処理によって薄膜化された切れ刃稜線部での膜厚をｄｘとしたとき、ｄｘ／ｄが０．２以上０．８以下になるように形成されている。
【００２６】
被覆膜２の厚さが一定の従来の場合において、その厚さが１５μｍを超えると、被覆膜２の表面のＲｃ１が増大して切れ味が低下する。それに対し、刃先処理を施していない領域である逃げ面４における被覆膜２の平均膜厚をｄ、表面処理により薄膜化された切れ刃稜線部３での最も薄い部分での膜厚をｄｘとしたときの、ｄｘ／ｄが０．２〜０．８の範囲に入るように形成することにより、従来実用化されていなかった、被覆膜２の薄膜化されていない部分の厚さが１５μｍ以上の工具の切れ味を向上させることができるとともに、耐摩耗性が改善される。その結果、被覆膜２の膜厚が２０μｍ〜５０μｍの被覆硬質合金工具の実用化を図ることができる。
【００２７】
ここで、ｄｘ／ｄの値を０．２以上に設定したのは、この値が０．２未満であると被覆膜２の摩耗による硬質合金基材１が露出するまでの時間が極端に短くなって耐摩耗性が低下し、０．８を越える値に設定したとしても耐欠損性の大幅な向上が認められないためである。
【００２８】
また、硬質合金基材１の２つの曲率半径の比Ｒｓ２／Ｒｓ１が、０．７以上１．３以下になるように形成されることが好ましい。このように、Ｒｓ２／Ｒｓ１を０．７〜１．３の範囲に形成すると、硬質合金基材１の切れ刃稜線部３に働く切削抵抗の応力集中が緩和される。このような刃先手法としては、遠心バレルや振動バレルなどによる研摩法が好ましい。これらの刃先処理法は、硬質合金基材１の表面性状を平滑（Ｒｍａｘ０．３μｍ以下）にする工業的手段として有効である。ここでＲｓ２／Ｒｓ１の比が０．７未満では耐摩耗性が低下し、１．３を越えると耐欠損性が低下する。
【００２９】
また、被覆膜２表面の２つの曲率半径の比Ｒｃ２／Ｒｃ１が、２．０以上５０以下になるように形成されることが好ましい。このように、Ｒｃ２／Ｒｃ１が２．０〜５０の範囲になるように形成すると、耐摩耗性と耐欠損性とのバランスが非常によくなる。Ｒｃ２／Ｒｃ１が２．０未満では耐摩耗性が劣化し、５０を越えると耐欠損性が低下する。
【００３０】
被覆膜２の表面における刃先処理部は、図１に示すように、そのすくい面側の幅をａ、逃げ面側の幅をｂとしたとき、これらの比ａ／ｂが１．５以上４．０以下になるように形成されることが好ましい。ａ／ｂの比が１．５未満になると、耐摩耗性の改善効果が小さく、４．０を越えると耐欠損性が低下する。
【００３１】
被覆膜２は、好ましくは、少なくとも酸化物セラミック層を含む多層構造を有し、該酸化物セラミック層の少なくとも１層の厚みの一部が、切れ刃稜線部全領域に渡って残存するように表面処理が施されていることが好ましい。たとえば、図６（ａ）に示すように、４層からなる被覆層２のうちの１層のみが酸化物セラミック層２ａからなる被覆硬質合金の場合、被覆膜２の刃先処理を施した後において、酸化物セラミック層２ａが図６（ｂ）に示すようにその厚みの一部が刃先処理部全域に残存していれば、良好な耐摩耗性を発揮するが、酸化物セラミック層２ａが、図６（ｃ）に示すように刃先処理部の一部においてでも取り除かれていると、耐摩耗性が劣化することがある。
【００３２】
より具体的には、高速高能率切削時の切削温度の上昇による図３に示す位置のクレータ摩耗９の発生が、酸化物セラミック層２ａが切れ刃稜線部３に存在していることによって大幅に抑制される。特に、上述の比ａ／ｂが１．５〜４の範囲にあるときには、表面処理によってすくい面６側の被覆膜の除去量が大きくなり、クレータ摩耗９の発生しやすい領域と切屑１０の接触面とが重なるため、酸化物セラミック層を残存させてクレータ摩耗９を低減することが極めて有効である。
【００３３】
本実施の形態の被覆硬質合金工具は、被覆膜２の表面処理部の少なくとも一部における増加表面積比率が０．１％以上１．３％以下になるように設定されている。表面処理後の切れ刃稜線部３における増加表面積比率を０．１〜１．３％とすることにより、耐欠損性および耐摩耗性の双方を向上することに加えて、被覆膜の耐剥離性を向上させることができる。被覆膜２の耐剥離性は、表面処理後の表面が鏡面に近いほど向上するが、増加表面積比率が０．１未満になるように処理することは工業的に難しく、また、増加表面積比率が１．３を越えると耐剥離性の大幅な向上を得ることができない。被覆膜２の耐剥離性の向上により、刃先処理部における硬質合金基材表面が切削中に露出する度合いが抑制されるため、被削材の刃先処理部への溶着現象も抑制され、その結果として工具の耐欠損性をさらに向上することができる。
【００３４】
ここで増加表面積比率とは、図４（ａ）に示すように測定視野面積をＳｍ、測定部の表面積をＳａとしたときに、（Ｓａ／Ｓｍ−１）×１００％という数式により定量化される数値である。すなわち、測定視野面積領域内を全くの鏡面とした場合の表面積に対して、測定視野面積領域の表面凹凸面積の増加率を表わしたものである。この数値で表面積を定量化した理由は、Ｒｍａｘ、Ｒａなどの従来の粗さ指標が高さ方向の面粗さ性状しか表現できなかったのに対して、この数値では水平方向の面粗さをも含めた３次元の面粗さに関する情報を定量化できるからである。
【００３５】
測定部の表面積Ｓａは、図４（ｂ）に黒点で示す位置の座標を、矢印Ｍ方向にサンプリングして求めた上で、測定部の表面上のサンプリング点ｘ11，ｘ12，ｘ21, ……を頂点とした三角形の面積ｓ11，ｓ12，……の和として計算される。
【００３６】
【実施例】
以下、本発明の効果を検証した実施例を示す。
【００３７】
実施例１
型番ＳＮＭＧ１２０４０８形状のＩＳＯ−Ｐ２０級スローアウエイチップの切れ刃稜線部でのＲｓ１が６０μｍ、Ｒｓ２が９０μｍとなるように刃先処理し、下層から順に０．５μｍＴｉＮ／７μｍＴｉＣＮ／２μｍＡｌ₂ Ｏ₃ ／０．５μｍＴｉＮの４層からなるセラミック被膜（ｄ＝１０μｍ）を約１０００℃の温度でＣＶＤ法によってコーティングした。なお、アルミナ膜被覆時にはＨ₂ Ｓガスを原料として用い、エッジ部でのアルミナ膜の極大化を防いでおり、平坦部とエッジ部とで膜厚の差がほとんどない被覆膜を得ることができた。
【００３８】
次に、この被覆スローアウエイチップを♯４００のダイヤモンド砥粒を付着させたナイロン製ブラシでスローアウエイチップに対するすくい角を変化させて、表１に示すようにＲｃ１およびＲｃ２の異なるスローアウエイチップを用意した。次に、これらの試料を用いて、図５に横断面を示すように、外周に４つの溝１２を設けた高炭素鋼ＳＣＭ４３５材からなる被削材１１を次の条件で断続切削し、各試料の耐欠損性を評価するとともに、低炭素鋼ＳＣＭ４１５材からなる丸棒の被削材を用いて、次の条件で耐摩耗性を評価した。
【００３９】
耐欠損性テスト１
切削速度１００ｍ／ｍｉｎ
送り０．２〜０．４ｍｍ／ｒｅｖ
切り込み２ｍｍ
切削油なし
使用ホルダＰＳＵＮＲ２５２５−４３
寿命時間は、切削開始から欠け発生時点までの時間とし、各試料における４コーナーの平均寿命時間を当該試料の寿命時間とした。
【００４０】
耐摩耗性テスト１
切削速度３００ｍ／ｍｉｎ
送り０．３ｍｍ／ｒｅｖ
切り込み１．５ｍｍ
切削時間３０分
切削油あり
その結果を下記の表１に示している。
【００４１】
【表１】

【００４２】
表１の結果からわかるように、表面処理を施していない比較品１−１および表面処理を施したものの本発明の範囲に入らない比較品１−２に比べて、Ｒｃ１をＲｓ１＋ｄよりも小さくした発明品１−１〜１−６は、耐欠損性を損なうことなく、耐摩耗性が向上していることがわかる。中でも、Ｒｃ１／（Ｒｓ＋ｄ）が０．２〜０．８の範囲内にある発明品１−３〜１−５は、特に優れた耐摩耗性を示している。
【００４３】
実施例２
ＩＳＯ−Ｐ２０級のサーメット系スローアウエイチップを基材とし、その表面に厚さｄ＝１０〜２２μｍの被覆膜を被覆処理した試料を形成し、この試料に、実施例１と同一のダイヤモンドブラシを用いて、Ｒｃ２，Ｒｓ２，Ｒｃ１，Ｒｓ１の値が異なる比較品２−１，発明品２−１〜２−７を用意した。そのテスト結果を下記の表に示す。
【００４４】
【表２】

【００４５】
表２に示す結果からわかるように、本発明の範囲から外れる比較品２−１に比べて、発明品２−１〜２−７は優れた耐欠損性および耐摩耗性を示した。中でも、Ｒｃ２／（Ｒｓ２＋ｄ）を１．０よりも大きくした発明品２−２〜２−７は、特に優れた切削特性を示し、とりわけ、Ｒｃ２／（Ｒｓ２＋ｄ）が２．０〜５．０の範囲内にある発明品２−４〜２−６が優れた切削性能を発揮した。
【００４６】
実施例３
実施例１で用意した比較品１−１と同じＲｓ１（＝６０μｍ），Ｒｓ２（＝９０μｍ）の硬質合金基材に、下記の表３に示す中間層のＴｉＣＮ膜の膜厚のみが実施例１と異なり、その他は実施例１と同一の被覆膜をコーティングし、実施例１と同様にダイヤモンドブラシで表面処理し、Ｒｃ１，Ｒｃ２を発明品１−４と同一の４０μｍ，９０μｍとした発明品３−１〜３−４に対し、実施例１と同様の耐摩耗性テストを行なった。その結果を表４に示す。
【００４７】
【表３】

【００４８】
【表４】

【００４９】
表４の結果から、被覆膜の膜厚ｄが１５μｍよりも厚い発明品３−２〜３−４における切削性能向上の度合が特に大きいことがわかる。
【００５０】
次に、発明品３−３（Ｒｓ１＝６０μｍ，Ｒｓ２＝９０μｍ，ｄ＝２２μｍ）を用いて、ブラシのスローアウエイチップに対するすくい角を−１０°にし、表面処理時間を変えることによって切れ刃稜線部での膜厚が異なる発明品４−１〜４−６を用意した。また、全く表面処理を施さない試料を比較品４−２とした。さらに、ブラシのスローアウエイチップに対するすくい角を３０°に設定して表面処理を施した、本発明の範囲から外れる比較品４−１を用意した。なお、このようにして得られた発明品４−１〜４−６のＲｃ１はそれぞれ４０μｍ，４２μｍ，４５μｍ，４７μｍ，４８μｍおよび５０μｍであって、いずれも４０〜５０μｍの範囲内のものであり、比較品４−１のＲｃ１は１００μｍのものを用意した。また、発明品４−１〜４−６のＲｃ２はそれぞれ７０μｍ，７５μｍ，８０μｍ，８３μｍ，８６μｍおよび９０μｍであって、いずれも７０〜９０μｍの範囲内のものであり、比較品４−１のＲｃ２は９０μｍであった。
【００５１】
これらの比較品および発明品についての切削テスト結果を下記の表５に示す。
【００５２】
【表５】

【００５３】
表５に示すテスト結果からわかるように、比較品４−２の表面処理を施さない試料が耐欠損性テストにおいて初期チッピングを発生したのに対して、発明品４−１〜４−６は大幅に切削可能時間が延びている。また、耐摩耗性テストの結果から、発明品４−６を除いて、耐摩耗性が向上していることがわかる。以上の結果を総合すると、ｄｘ／ｄ＝０．２〜０．８の範囲にある発明品４−２〜４−５の切削性能が特に優れていることがわかる。中でも、ｄｘ／ｄ＝０．２〜０．６の範囲にある発明品４−３〜４−５は、特に優れた耐欠損性を示している。
【００５４】
実施例４
型番ＳＮＭＧ１２０４０８形状のＩＳＯ−Ｋ１０級基材の切れ刃稜線部でのＲｓ１が３０μｍ、Ｒｓ２が３０μｍとなるように表面処理を施したスローアウエイチップに、実施例１と同様のセラミック膜（ｄ＝１０μｍ）を被覆後、表面処理を施し、Ｒｃ１，Ｒｃ２の異なる比較品５−１，５−２、発明品５−１〜５−５を用意した。これらのスローアウエイチップを用いて、ＦＣＤ４５０製被削材１１を次の条件で切削し、各試料の耐欠損性を評価するとともに、ＦＣＤ７００製被削材１１を用いて次の条件で耐摩耗性を評価した。なお、これたのテストにおいてダクタイル鋳鉄を使用したのは、Ｋ１０級基材を採用したためである。
【００５５】
耐欠損性テスト２
切削速度１５０ｍ／ｍｉｎ
送り０．２〜０．４ｍｍ／ｒｅｖ
切り込み２ｍｍ
切削油あり
寿命時間は、切削開始から欠け発生時点までの時間とし、各試料における４コーナーの平均寿命時間を当該試料の寿命時間とした。
【００５６】
耐摩耗性テスト２
切削速度２００ｍ／ｍｉｎ
送り０．３ｍｍ／ｒｅｖ
切り込み１．５ｍｍ
切削時間１０分
切削油あり
これらの切削テストの結果を下記の表６に示す。
【００５７】
【表６】

【００５８】
表６に示す結果からわかるように、発明品５−１〜５−５は、比較品５−１および５−２と比較して、耐欠損性および耐摩耗性ともに優れ、中でもＲｃ２／Ｒｃ１が２．０〜５０の範囲にある発明品５−２〜５−４は、特に優れた切削性能を示すことがわかる。
【００５９】
実施例５
実施例３で用意した発明品３−２と同一基材、同一被覆層を有する、表面処理を施していない比較品６−１（Ｒｓ１＝６０μｍ，Ｒｓ２＝９０μｍ，ｄ＝１６μｍ）を、♯４００のＳｉＣ砥粒の付着した弾性砥石を用いて、回転数、硬さ、加圧力を選んで、下記の表７に示す比較品６−２、発明品６−１〜６−５を用意した。実施例１と同じ切削テストを行ない、その結果を下記の表７に示す。
【００６０】
【表７】

【００６１】
表７の結果からわかるように、発明品６−１〜６−５は、比較品６−１および６−２に比べて優れた切削性能を示している。中でもａ／ｂが１．５〜４．０の範囲にある発明品６−２〜６−４は、特に優れた切削性能を示している。
【００６２】
実施例６
実施例５で用意した発明品６−１〜６−５と評価品６−１とを、切削温度の上昇しやすい高炭素鋼ＳＣＭ４３５からなる丸棒の被削材を用いて、下記条件で切削テストを行なった。
【００６３】
耐摩耗テスト３
切削速度１８０ｍ／ｍｉｎ
送り０．３ｍｍ／ｒｅｖ
切り込み１．５ｍｍ
切削時間１０分
切削油なし
この試験の結果、下記の表８に示すように、比較品６−１は摩耗量は大きいものの、１０分間切削できたのに対し、発明品６−３〜６−５は切削途中で火花が発生し、切削を継続することが不能となった。その原因は、被覆後の表面処理によって切れ刃稜線部のアルミナ膜が除去されたためと推定される。
【００６４】
そこで、被覆膜を下層から順に０．５μｍＴｉＮ／２μｍＡｌ₂ Ｏ₃ ／１３μｍＴｉＣＮ／０．５μｍＴｉＮの４層（総膜厚ｄ＝１６μｍ）とし、アルミナ膜を下層に被覆して表面処理後のアルミナ膜が切れ刃稜線部に残る構造とした被覆膜を、発明品６−１〜６−５と同一組成、同一Ｒｓ１、Ｒｓ２（Ｒｓ１＝６０μｍ，Ｒｓ２＝９０μｍ）の基材へコーティングし、発明品６−４と同一のＲｃ１、Ｒｃ２、ａ、ｂ（Ｒｃ１＝４５μｍ，Ｒｃ２＝１２０μｍ，ａ＝０．２６ｍｍ，ｂ＝０．０７ｍｍ）となるように表面処理を施した発明品７−１を用意した。そして、上記の耐摩耗性テスト３を行なった結果、下記の表８に示す優れた耐摩耗性を示すことがわかった。
【００６５】
【表８】

【００６６】
表８に示す結果から、本発明の表面処理の際、表面処理後も切れ刃稜線部に酸化物被膜の残存する被膜構造を持つスローアウエイチップが、切削温度の上昇しやすい高炭素鋼の高速切削において特に優れた切削性能を示すことがわかる。
【００６７】
実施例７
♯８００および１２００のＳｉＣ砥粒の付着した弾性砥石を用いて、表面処理を行っていない比較品１−１を表面処理した発明品８−１〜８−５を用意した。なお、これらのスローアウエイチップのＲｓ１，Ｒｓ２，Ｒｃ１，Ｒｃ２，ａ，ｂ，ｄは、それぞれ６０μｍ，９０μｍ，４０μｍ，９０μｍ，０．１５ｍｍ，０．０８ｍｍ，１０μｍであり、発明品１−４とほぼ同一である。次に、実施例１で用いた発明品１−４（切れ刃稜線部の増加表面積比率１．５％）の試料と発明品８−１〜８−５の（増加表面積比率０．２〜１．３％）および比較品１−１（増加表面積比率２．４％）の試料を比較する。増加表面積比率の測定は、株式会社エリオニクス(Elionix) 製ＥＲＡ８０００型測定器を用い、測定倍率は、硬質合金基材の表面のうねりを排除して微細な凹凸を測定するため５０００倍とし、測定視野内の水平方向および垂直方向のサンプリング数をそれぞれ２８０点および２１０点とした。
【００６８】
これらのスローアウエイチップを用いて、溶着の発生しやすい金型鋼ＳＫＤ６１からなる、図５に示す横断面形状を有する被削材１１を次の条件で断続切削し、各試料の耐剥離性を評価した。
【００６９】
耐剥離テスト１
切削速度１００ｍ／ｍｉｎ
送り０．１５ｍｍ／ｒｅｖ
切り込み１．５ｍｍ
切削油なし
このテストにおいては、切削開始から、試料の刃先に被削材が溶着して被膜剥離が発生するまでを寿命時間とした。そのテスト結果を下記の表９に示す。
【００７０】
【表９】

【００７１】
表９に示すテスト結果から、増加表面積比率が０．１〜１．３％の範囲にあるスローアウエイチップは、耐剥離性能が優れていることがわかる。中でも、増加表面積比率が０．２〜１．０％の範囲にある発明品８−１，８−２，８−４，８−５は、特に優れた耐剥離性を示している。
【００７２】
以上開示された本発明の実施の形態および実施例は、すべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は、上述の説明では、特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更を含むことが意図される。
【図面の簡単な説明】
【図１】本発明の被覆硬質合金工具の刃先稜線部における、硬質合金基材の刃先処理部の形態と、被覆膜の表面処理部の形態とを示す断面図である。
【図２】本発明の効果を検証するために用いたスローアウエイチップの形態を示す斜視図である。
【図３】切削テストの際に、切り屑とスローアウエイチップのすくい面との接触面に発生するクレータ摩耗を説明するための図である。
【図４】（ａ）は増加表面積比率の定義を説明するためのの模式的斜視図、（ｂ）はサンプリングによって測定部の表面積を求める手法を説明するための図である。
【図５】耐欠損性テストにおける断続切削に用いられる被削材の横断面形状を示す断面図である。
【図６】（ａ）は、４層の被覆膜を被覆した被覆硬質合金工具の、被覆膜を表面処理する前の状態の断面図、（ｂ）は、被覆膜を表面処理した後に酸化物セラミック層が切れ刃稜線部全域に残存した状態の断面図、（ｃ）は、被覆膜を表面処理した後に、刃先稜線部の一部において酸化物セラミック層が除去された状態の断面図である。
【符号の説明】
１硬質合金基材
２被覆膜
３切れ刃稜線部
４逃げ面
６すくい面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coated hard alloy tool, and in particular, by increasing the film thickness of the coating film on the hard alloy substrate and applying a surface treatment that identifies the shape of the edge portion of the cutting edge after the coating process, The present invention relates to a technique for improving wear resistance without impairing chipping properties.
[0002]
[Prior art]
Conventionally, cemented carbide (WC-Co alloy or alloy obtained by adding a carbonitride of Ti, Ta, or Nb to a WC-Co alloy) has been used as a material for a tool for cutting a metal material. However, in recent years, as a result of the speeding up of cutting conditions, a CVD (Chemical Vapor Deposition) method or PVD (PVD) is applied to the surface of a substrate made of cemented carbide or cermet, or a substrate made of alumina or silicon nitride ceramics. The use of hard alloy tools in which coating films of various materials are coated to a thickness of 3 to 15 μm by the Physical Vapor Deposition method is increasing. Examples of the material of the coating film include carbides, nitrides, carbonitrides, carbonates, boronitrides, oxides, or solid solutions thereof such as group IVa, Va, VIa group metals and Al. It is used. A coating film made of diamond or diamond-like carbon is also used.
[0003]
These coated hard alloy tools formed a cutting edge shape by chamfering a hard alloy base material by honing, chamfering, or a combination thereof, thereby supplementing the fracture resistance of hard alloys that are prone to breakage. The coating process is performed above. In addition, there is a known technique for multilayering the coating film in order to improve the wear resistance.
[0004]
Moreover, in Japanese Patent Publication No. 5-9201, the surface strength after the coating treatment on the surface of the hard alloy base material is improved by removing a part of the coating film of the cutting edge ridge line portion, A technique for improving wear resistance is disclosed.
[0005]
[Problems to be solved by the invention]
However, in each of the above-mentioned conventional coated hard alloy tools, increasing the cutting edge processing amount of the hard alloy base material improves the chipping resistance, but the wear resistance is reduced, and reducing the cutting edge processing amount reduces the wear resistance. However, it has not been possible to sufficiently avoid the problem due to the conflicting phenomenon that the fracture resistance is reduced although it is improved. Further, the technique described in Japanese Patent Publication No. 5-9201 also has a problem in that it is not always possible to improve both the fracture resistance and the wear resistance depending on the degree of removal of the coating film. .
[0006]
The present invention provides a long-life coating that has improved wear resistance without impairing fracture resistance by optimizing both the shape of the hard alloy substrate and the shape of the coating layer at the cutting edge of the coated hard alloy tool. An object is to provide a hard alloy tool.
[0007]
Another object of the present invention is to provide a long-life coated hard alloy tool which has improved both fracture resistance and wear resistance.
[0008]
[Means for Solving the Problems]
The coated hard alloy tool of the present invention that achieves the above object comprises a hard alloy base material having a cutting edge ridge line part that forms a connecting part between a flank face and a rake face, and a surface of the hard alloy base material. And a surface treatment portion at the cutting edge ridge portion on the surface of the coating film. The feature of this coated hard alloy tool is that the radius of curvature of the convex curved surface formed at the boundary between the flank and the blade edge processing portion on the surface of the hard alloy substrate is Rs1, and the flank and surface treatment on the surface of the coating film. Rc1 / (Rs1 + d) <1.0, where Rc1 is the radius of curvature of the convex curved surface formed at the boundary with the part, and d is the average film thickness of the coating film in the region other than the surface treatment part. The coating film is formed.
[0009]
According to this structure, since the coating film is formed so that Rc1 / (Rs1 + d) <1.0, the wear resistance can be improved without impairing the fracture resistance.
[0010]
The inventors have found the structure of the present invention by paying attention to the relationship between the curvature radii of the cutting edges of both the hard alloy substrate and the coating layer, as follows.
[0011]
It is already known that the chipping resistance of a coated hard alloy tool is governed by the toughness determined by the material of the hard alloy substrate that is the coated base material and the cutting edge processing shape of the hard alloy substrate before coating. Usually, the edge shape of a hard alloy substrate is alumina or Zr0. ₂ When oxides such as these are coated, the coating film thickness tends to be maximized at the corners forming the cutting edge ridgeline. Therefore, the radius of curvature of the surface of the coating film at the boundary between the flank and the surface-treated cutting edge portion is Rc1, the corresponding radius of curvature of the hard alloy substrate surface is Rs1, and the region other than the surface-treated portion is coated. In many cases, when the average film thickness is d, these satisfy the relationship Rc1> Rs1 + d. However, when coating the alumina film, the source gas is H ₂ If a technique for suppressing the maximization of the film thickness at the corner using S is used, a coating film having a substantially uniform film thickness satisfying the relationship of Rc1 = Rs1 + d is formed on the cutting edge of the hard alloy substrate. Is possible.
[0012]
Since the size of the curvature radius Rc1 determines the sharpness of the tool, the sharpness of the tool after the coating treatment is slightly lowered and the wear resistance is simultaneously deteriorated as compared with the case where the coating treatment is not performed. This tendency increases as the coating film thickness increases, and it has been found that this tendency is particularly remarkable when the coating film thickness is 15 μm or more.
[0013]
Therefore, in order to improve wear resistance while maintaining toughness, the radius of curvature Rs1 at the boundary between the flank face of the hard alloy substrate and the cutting edge processed by the cutting edge is made larger than that of the conventional tool, and conventionally. In addition, the coating treatment was performed so that the coating film thickness was increased, and then the surface treatment of the coating film was tried.
[0014]
In that case, the wear resistance can be improved without impairing the fracture resistance by reducing the Rc1 and performing the cutting edge processing so that the cutting edge shape satisfies the relationship of Rc1 <Rs1 + d. It has been discovered.
[0015]
The coated hard alloy tool of the present invention has the above-described structure, the radius of curvature of the convex curved surface formed at the boundary between the rake face and the blade edge processing portion on the surface of the hard alloy substrate is Rs2, and the surface of the coating film is raked. The coating film is preferably formed so that Rc2 / (Rs2 + d)> 1.0 when the radius of curvature of the convex curved surface formed at the boundary between the surface and the surface treatment portion is Rc2. . Thus, by satisfying both the relations of Rc1 / (Rs1 + d) <1.0 and Rc2 / (Rs2 + d)> 1.0, both the fracture resistance and the wear resistance can be improved.
[0016]
In order to further enhance the effect of improving the fracture resistance and wear resistance, Rc1 / (Rs1 + d) is set to 0.2 or more and 0.8 or less, and Rc2 / (Rs2 + d) is set to 2. It is preferable to form so that it may be 0 or more and 5.0 or less.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
First, referring to FIG. 1, after coating the coating film 2 on the surface of the hard alloy substrate 1 obtained by subjecting the cutting edge ridge portion 3 forming the connecting portion between the flank 4 and the rake face 6 to the edge, By performing the treatment and forming a surface treatment portion on the cutting edge ridge portion 3 on the surface of the coating film 2, a coated hard alloy tool having a cross-sectional shape shown in FIG. 1 is formed.
[0019]
In the coated hard alloy tool shown in FIG. 1 formed in this way, the radius of curvature of the convex curved surface formed at the boundary between the flank 4 and the blade edge processing portion on the surface of the hard alloy substrate 1 is Rs1, When the curvature radius of the convex curved surface formed at the boundary between the flank 4 and the surface treatment portion on the surface of the covering film 2 is Rc1, and the average film thickness of the coating film 2 in the region other than the surface treatment portion is d, The cutting edge processing portion of the hard alloy substrate 1 and the surface processing portion of the surface of the coating film 2 are formed so as to satisfy the relationship of Rc1 / (Rs1 + d) <1.0 and Rc2 / (Rs2 + d)> 1.0. .
[0020]
Thus, by satisfying both the relations of Rc1 / (Rs1 + d) <1.0 and Rc2 / (Rs2 + d)> 1.0, both the fracture resistance and the wear resistance can be improved. Further, by satisfying at least the relationship of Rc1 / (Rs1 + d) <1.0, the wear resistance can be improved without impairing the fracture resistance.
[0021]
The relationship represented by these inequalities is preferably formed so as to hold over all the cutting edges of the nose R portion 8 of the cutting edge 3 of the throwaway tip 7 shown in FIG. Even if it is true, a certain degree of effect is exhibited.
[0022]
The value of the radius of curvature Rc1 is measured as follows. First, the coated hard alloy tool whose surface is coated with the coating film 2 is cut in a cross section perpendicular to the cutting edge, and then the cut surface is embedded in the resin. This is subjected to surface grinding and mirror polishing, then etched, and then further gold deposition is performed as necessary. Next, the vicinity of the cutting edge ridge line portion of the sample thus formed is photographed with an optical microscope at a magnification of 1500 times. Next, the photographed photograph is taken into the image processing apparatus, and the boundary between the untreated portion of the coating film on the flank side and the surface treated portion is set as the starting point (point O) on the image, and from this point O A point (point A) that is 5 μm away from the surface of the coating film toward the rake face side and a point (point B) that is 5 μm away from the point O on the surface of the coating film toward the flank side are determined. Based on the (x, y) coordinates of the points O, A and B determined in this way, the radius of the circle passing through these three points is calculated to obtain the value of the curvature radius Rc1. The curvature radii Rc2, Rs1, and Rs2 are also obtained by the same method.
[0023]
As a surface treatment method of the coating film 2, a treatment method using a brush or an elastic grindstone containing a hard substance such as diamond or SiC is suitable, but is not limited to these methods. The cutting edge shape after the surface treatment depends on the rotational speed and hardness of the brush and grindstone, the processing angle with respect to the rake face of the tool, the pressing force of the grindstone, and the presence or absence of cutting oil. Therefore, in order to obtain a desired cutting edge shape, it is necessary to set these conditions appropriately.
[0024]
As the material of the hard alloy substrate 1, cermet and ceramic (for example, silicon nitride and fiber reinforced ceramic (FRC)) can be used in addition to cemented carbide, and these materials have a gradient composition. May be. As the gradient composition material, a material having a tough layer or a ceramic layer on the surface can be used. The material constituting the coating layer 2 includes carbides such as IVa, Va, and VIa group metals (ie, Ti, Zr, Hf; V, Nb, Ta; Cr, Mo, W) or Al in the periodic table of elements, Examples thereof include nitrides, carbonitrides, carbonates, boronitrides or oxides, or solid solutions thereof. Further, diamond, diamond-like carbon, or the like is also used as the material for the coating layer 2. The covering layer 2 is formed by a CVD method, a PVD method, or the like.
[0025]
In the coated hard alloy tool of this example, the average film thickness of the coating film of the hard alloy base material is 15 μm or more, and the film thickness at the cutting edge ridge line portion thinned by the surface treatment is dx. In some cases, dx / d is 0.2 or more and 0.8 or less.
[0026]
In the conventional case where the thickness of the coating film 2 is constant, when the thickness exceeds 15 μm, Rc1 on the surface of the coating film 2 increases and sharpness decreases. On the other hand, the average film thickness of the coating film 2 on the flank 4 which is a region not subjected to the blade edge treatment is d, and the film thickness at the thinnest portion of the cutting edge ridge line portion 3 thinned by the surface treatment is dx. By forming so that dx / d falls within the range of 0.2 to 0.8, the thickness of the portion of the coating film 2 that has not been put into practical use and has not been made thin can be reduced. The sharpness of a tool of 15 μm or more can be improved and the wear resistance is improved. As a result, the coated hard alloy tool having a coating film 2 with a thickness of 20 μm to 50 μm can be put into practical use.
[0027]
Here, the value of dx / d is set to 0.2 or more. If this value is less than 0.2, the time until the hard alloy substrate 1 is exposed due to wear of the coating film 2 is extremely large. This is because the wear resistance is reduced due to shortening, and even if the value is set to a value exceeding 0.8, no significant improvement in fracture resistance is observed.
[0028]
Moreover, it is preferable to form so that ratio Rs2 / Rs1 of two curvature radii of the hard alloy base material 1 may be 0.7 or more and 1.3 or less. Thus, when Rs2 / Rs1 is formed in the range of 0.7 to 1.3, the stress concentration of the cutting resistance acting on the cutting edge ridge line portion 3 of the hard alloy base material 1 is relaxed. As such a blade edge method, a polishing method using a centrifugal barrel or a vibration barrel is preferable. These blade edge treatment methods are effective as industrial means for smoothening the surface properties of the hard alloy substrate 1 (Rmax 0.3 μm or less). Here, if the ratio of Rs2 / Rs1 is less than 0.7, the wear resistance is lowered, and if it exceeds 1.3, the fracture resistance is lowered.
[0029]
Moreover, it is preferable that the ratio Rc2 / Rc1 of the two curvature radii on the surface of the coating film 2 is 2.0 or more and 50 or less. Thus, if it forms so that Rc2 / Rc1 may be in the range of 2.0-50, the balance of abrasion resistance and chipping resistance becomes very good. When Rc2 / Rc1 is less than 2.0, the wear resistance deteriorates, and when it exceeds 50, the fracture resistance decreases.
[0030]
As shown in FIG. 1, the cutting edge processing portion on the surface of the coating film 2 has a ratio a / b of 1.5 or more when the rake face width is a and the flank face width is b. It is preferably formed so as to be 4.0 or less. When the ratio of a / b is less than 1.5, the effect of improving the wear resistance is small, and when it exceeds 4.0, the fracture resistance is lowered.
[0031]
The coating film 2 preferably has a multilayer structure including at least an oxide ceramic layer, and a part of the thickness of at least one layer of the oxide ceramic layer remains over the entire cutting edge ridge line region. It is preferable that the surface treatment is performed. For example, as shown in FIG. 6A, in the case where only one of the four coating layers 2 is a coated hard alloy composed of an oxide ceramic layer 2a, the blade edge treatment of the coating film 2 is performed. In FIG. 6B, the oxide ceramic layer 2a exhibits good wear resistance if a part of its thickness remains in the entire cutting edge processing portion as shown in FIG. As shown in FIG. 6C, if even a part of the blade edge processing portion is removed, the wear resistance may be deteriorated.
[0032]
More specifically, the occurrence of crater wear 9 at the position shown in FIG. 3 due to an increase in the cutting temperature during high-speed and high-efficiency cutting is greatly caused by the presence of the oxide ceramic layer 2a in the cutting edge ridge 3. It is suppressed. In particular, when the above-mentioned ratio a / b is in the range of 1.5 to 4, the removal amount of the coating film on the rake face 6 side is increased by the surface treatment, and the region where the crater wear 9 is likely to occur and the chip 10 Since the contact surface overlaps, it is extremely effective to reduce the crater wear 9 by leaving the oxide ceramic layer.
[0033]
The coated hard alloy tool of the present embodiment is set such that the increased surface area ratio in at least a part of the surface treatment portion of the coating film 2 is 0.1% or more and 1.3% or less. In addition to improving both fracture resistance and wear resistance by setting the increased surface area ratio in the cutting edge ridge line part 3 after the surface treatment to be 0.1 to 1.3%, peeling resistance of the coating film Can be improved. The peel resistance of the coating film 2 is improved as the surface after the surface treatment is closer to a mirror surface, but it is industrially difficult to treat the increased surface area ratio to be less than 0.1, and the increased surface area ratio. If the ratio exceeds 1.3, the peel resistance cannot be significantly improved. By improving the peel resistance of the coating film 2, the degree of exposure of the hard alloy substrate surface in the cutting edge processing portion during cutting is suppressed, so that the welding phenomenon of the work material to the cutting edge processing portion is also suppressed, As a result, the fracture resistance of the tool can be further improved.
[0034]
Here, the increased surface area ratio is quantified by a formula of (Sa / Sm−1) × 100%, where Sm is the measurement visual field area and Sa is the surface area of the measurement part as shown in FIG. It is a numerical value. That is, it represents the rate of increase of the surface irregularity area of the measurement visual field area region with respect to the surface area when the measurement visual field area region is a complete mirror surface. The reason for quantifying the surface area with this value is that the conventional roughness index such as Rmax and Ra can only express the surface roughness property in the height direction, whereas in this value the surface roughness in the horizontal direction is expressed. This is because the information about the three-dimensional surface roughness including the above can be quantified.
[0035]
The surface area Sa of the measuring part is obtained by sampling the coordinates of the positions indicated by black dots in FIG. 4B in the direction of the arrow M, and then sampling points x11, x12, x21,... On the surface of the measuring part. It is calculated as the sum of the areas s11, s12,.
[0036]
【Example】
Examples in which the effects of the present invention are verified will be described below.
[0037]
Example 1
The blade tip is processed so that Rs1 is 60 μm and Rs2 is 90 μm at the edge of the edge of the ISO-P20 class throwaway tip of model number SNMG120408, and 0.5 μmTiN / 7 μmTiCN / 2 μmAl in order from the bottom. ₂ O _Three A ceramic film (d = 10 μm) consisting of four layers of /0.5 μm TiN was coated by a CVD method at a temperature of about 1000 ° C. When the alumina film is coated, H ₂ S gas was used as a raw material to prevent the alumina film from being maximized at the edge portion, and a coating film having almost no difference in film thickness between the flat portion and the edge portion could be obtained.
[0038]
Next, the rake angle with respect to the throwaway tip is changed with a nylon brush to which diamond abrasive grains of # 400 are attached to this coated throwaway tip to prepare throwaway tips having different Rc1 and Rc2 as shown in Table 1. did. Next, using these samples, as shown in a cross section in FIG. 5, the work material 11 made of a high carbon steel SCM435 material provided with four grooves 12 on the outer periphery is intermittently cut under the following conditions. While evaluating the fracture resistance of the sample, the wear resistance was evaluated under the following conditions using a round bar work material made of low carbon steel SCM415.
[0039]
Fracture resistance test 1
Cutting speed 100m / min
Feed 0.2-0.4mm / rev
Notch 2mm
Cutting oil None
Holder used PSUNR2525-43
The life time was defined as the time from the start of cutting to the occurrence of chipping, and the average life time at the four corners of each sample was defined as the life time of the sample.
[0040]
Abrasion resistance test 1
Cutting speed 300m / min
Feed 0.3mm / rev
Notch 1.5mm
Cutting time 30 minutes
Cutting oil Yes
The results are shown in Table 1 below.
[0041]
[Table 1]

[0042]
As can be seen from the results in Table 1, Rc1 was made smaller than Rs1 + d compared to Comparative Product 1-1 that was not surface-treated and Comparative Product 1-2 that was surface-treated but did not fall within the scope of the present invention. It can be seen that the inventive products 1-1 to 1-6 have improved wear resistance without impairing fracture resistance. Among them, invention products 1-3 to 1-5 in which Rc1 / (Rs + d) is in the range of 0.2 to 0.8 show particularly excellent wear resistance.
[0043]
Example 2
An ISO-P20 grade cermet-type throwaway tip is used as a base material, and a surface of which is coated with a coating film having a thickness d = 10 to 22 μm is formed. The same diamond brush as in Example 1 is formed on this sample. Comparative products 2-1 and inventive products 2-1 to 2-7 having different values of Rc2, Rs2, Rc1, and Rs1 were prepared. The test results are shown in the table below.
[0044]
[Table 2]

[0045]
As can be seen from the results shown in Table 2, the inventive products 2-1 to 2-7 exhibited excellent fracture resistance and wear resistance as compared with the comparative product 2-1, which is out of the scope of the present invention. Among them, invention products 2-2 to 2-7 in which Rc2 / (Rs2 + d) is larger than 1.0 show particularly excellent cutting characteristics, and in particular, Rc2 / (Rs2 + d) is 2.0 to 5.0. Invention products 2-4 to 2-6 in the range exhibited excellent cutting performance.
[0046]
Example 3
Only the film thickness of the TiCN film of the intermediate layer shown in Table 3 below is applied to the same hard alloy substrate of Rs1 (= 60 μm) and Rs2 (= 90 μm) as the comparative product 1-1 prepared in Example 1. Otherwise, the same coating film as in Example 1 was coated, and surface treatment was performed with a diamond brush in the same manner as in Example 1 so that Rc1 and Rc2 were 40 μm and 90 μm as in Invention 1-4. The same abrasion resistance test as in Example 1 was performed on 3-1 to 3-4. The results are shown in Table 4.
[0047]
[Table 3]

[0048]
[Table 4]

[0049]
From the results in Table 4, it can be seen that the degree of improvement in cutting performance is particularly large in invention products 3-2 to 3-4 in which the film thickness d of the coating film is thicker than 15 μm.
[0050]
Next, by using the inventive product 3-3 (Rs1 = 60 μm, Rs2 = 90 μm, d = 22 μm), the rake angle of the brush with respect to the throwaway tip is set to −10 °, and the surface treatment time is changed to change the cutting edge ridge line part Inventive products 4-1 to 4-6 having different film thicknesses were prepared. A sample that was not subjected to any surface treatment was designated as Comparative product 4-2. Further, a comparative product 4-1 was prepared, which was subjected to surface treatment with the rake angle of the brush with respect to the throwaway tip set to 30 °, and deviated from the scope of the present invention. In addition, Rc1 of the inventive products 4-1 to 4-6 obtained in this way is 40 μm, 42 μm, 45 μm, 47 μm, 48 μm and 50 μm, respectively, all within the range of 40 to 50 μm, A comparative product 4-1 having an Rc1 of 100 μm was prepared. In addition, Rc2 of the inventive products 4-1 to 4-6 is 70 μm, 75 μm, 80 μm, 83 μm, 86 μm and 90 μm, respectively, all within the range of 70 to 90 μm, and Rc2 of the comparative product 4-1 Was 90 μm.
[0051]
The cutting test results for these comparative products and invention products are shown in Table 5 below.
[0052]
[Table 5]

[0053]
As can be seen from the test results shown in Table 5, the samples of the comparative product 4-2 that had not been subjected to the surface treatment generated initial chipping in the fracture resistance test, whereas the inventive products 4-1 to 4-6 were significantly different. The cutting time is prolonged. Moreover, it can be seen from the results of the abrasion resistance test that the abrasion resistance is improved except for the inventive product 4-6. When the above result is put together, it turns out that the cutting performance of the invention products 4-2 to 4-5 in the range of dx / d = 0.2 to 0.8 is particularly excellent. Among them, invention products 4-3 to 4-5 in the range of dx / d = 0.2 to 0.6 show particularly excellent fracture resistance.
[0054]
Example 4
Model No. SNMG120408 shaped ISO-K10 grade base material with a ceramic film similar to that of Example 1 (d = 10 μm) on a slow-away tip subjected to surface treatment so that Rs1 is 30 μm and Rs2 is 30 μm at the edge of the cutting edge ) Were subjected to surface treatment to prepare comparative products 5-1, 5-2 having different Rc1 and Rc2, and invention products 5-1 to 5-5. Using these throwaway tips, the FCD450 work material 11 is cut under the following conditions to evaluate the fracture resistance of each sample, and the FCD700 work material 11 is used for wear resistance under the following conditions. Evaluated. The reason why ductile cast iron was used in these tests was that a K10 grade base material was used.
[0055]
Fracture resistance test 2
Cutting speed 150m / min
Feed 0.2-0.4mm / rev
Notch 2mm
Cutting oil Yes
The life time was defined as the time from the start of cutting to the occurrence of chipping, and the average life time at the four corners of each sample was defined as the life time of the sample.
[0056]
Abrasion resistance test 2
Cutting speed 200m / min
Feed 0.3mm / rev
Notch 1.5mm
Cutting time 10 minutes
Cutting oil Yes
The results of these cutting tests are shown in Table 6 below.
[0057]
[Table 6]

[0058]
As can be seen from the results shown in Table 6, the inventive products 5-1 to 5-5 are superior in both fracture resistance and wear resistance compared to the comparative products 5-1 and 5-2, and in particular, Rc2 / Rc1 is It turns out that the invention products 5-2 to 5-4 in the range of 2.0 to 50 show particularly excellent cutting performance.
[0059]
Example 5
A comparative product 6-1 (Rs1 = 60 μm, Rs2 = 90 μm, d = 16 μm) having the same base material and the same coating layer as the inventive product 3-2 prepared in Example 3 and not subjected to surface treatment was treated with # 400. Comparative products 6-2 and invention products 6-1 to 6-5 shown in Table 7 below were prepared using an elastic grindstone to which SiC abrasive grains were adhered, and selecting the number of rotations, hardness, and pressure. The same cutting test as in Example 1 was performed, and the results are shown in Table 7 below.
[0060]
[Table 7]

[0061]
As can be seen from the results in Table 7, invention products 6-1 to 6-5 show superior cutting performance compared to comparative products 6-1 and 6-2. Among them, invention products 6-2 to 6-4 having a / b in the range of 1.5 to 4.0 show particularly excellent cutting performance.
[0062]
Example 6
The inventive products 6-1 to 6-5 and the evaluation product 6-1 prepared in Example 5 were cut under the following conditions using a round bar work material made of high-carbon steel SCM435 that easily increases the cutting temperature. Tested.
[0063]
Abrasion test 3
Cutting speed 180m / min
Feed 0.3mm / rev
Notch 1.5mm
Cutting time 10 minutes
Cutting oil None
As a result of this test, as shown in Table 8 below, the comparative product 6-1 was able to cut for 10 minutes although the wear amount was large, whereas the inventive products 6-3 to 6-5 had a spark in the middle of cutting. Occurred, making it impossible to continue cutting. This is presumably because the alumina film on the cutting edge ridge was removed by the surface treatment after coating.
[0064]
Therefore, the coating film is 0.5 μm TiN / 2 μm Al in order from the lower layer. ₂ O _Three /13μmTiCN/0.5μmTiN 4 layers (total film thickness d = 16μm), and coated film with a structure in which the alumina film is coated on the lower layer and the surface-treated alumina film remains on the edge of the cutting edge. 6-1 to 6-5 having the same composition and the same Rs1, Rs2 (Rs1 = 60 μm, Rs2 = 90 μm) coated on the base material, and Rc1, Rc2, a, b (Rc1 = 45 μm) identical to the inventive product 6-4 , Rc2 = 120 μm, a = 0.26 mm, b = 0.07 mm), an invention product 7-1 was prepared, which was surface-treated. And as a result of performing said abrasion resistance test 3, it turned out that the outstanding abrasion resistance shown in following Table 8 is shown.
[0065]
[Table 8]

[0066]
From the results shown in Table 8, in the surface treatment of the present invention, the throwaway tip having a coating structure in which the oxide coating remains on the edge of the cutting edge even after the surface treatment is a high-speed high carbon steel that tends to increase the cutting temperature. It can be seen that the cutting performance is particularly excellent in cutting.
[0067]
Example 7
Invention products 8-1 to 8-5 were prepared by surface-treating comparative product 1-1 on which surface treatment was not performed using an elastic grindstone to which # 800 and 1200 SiC abrasive grains adhered. Note that Rs1, Rs2, Rc1, Rc2, a, b, and d of these throwaway tips are 60 μm, 90 μm, 40 μm, 90 μm, 0.15 mm, 0.08 mm, and 10 μm, respectively. Almost identical. Next, the sample of Invention 1-4 (Increase surface area ratio of cutting edge ridge line portion 1.5%) used in Example 1 and (Increase surface area ratio 0.2-1 of Invention products 8-1 to 8-5) .3%) and Comparative Sample 1-1 (increased surface area ratio 2.4%). Measurement of the increased surface area ratio was performed using an ERA8000 type measuring instrument manufactured by Elionix Co., Ltd., and the measurement magnification was set to 5000 times in order to measure fine irregularities by eliminating the undulations on the surface of the hard alloy substrate. The number of samplings in the horizontal direction and the vertical direction was 280 points and 210 points, respectively.
[0068]
Using these throwaway tips, the workpiece 11 having a cross-sectional shape shown in FIG. 5 made of mold steel SKD61, which is easily welded, is intermittently cut under the following conditions, and the peel resistance of each sample is evaluated. did.
[0069]
Peel resistance test 1
Cutting speed 100m / min
Feed 0.15mm / rev
Notch 1.5mm
Cutting oil None
In this test, the life time was defined as the time from the start of cutting until the work material was welded to the cutting edge of the sample and the film peeling occurred. The test results are shown in Table 9 below.
[0070]
[Table 9]

[0071]
From the test results shown in Table 9, it can be seen that the throwaway tip having an increased surface area ratio in the range of 0.1 to 1.3% has excellent peeling resistance. Among them, Invention Products 8-1, 8-2, 8-4, and 8-5 having an increased surface area ratio in the range of 0.2 to 1.0% exhibit particularly excellent peeling resistance.
[0072]
The embodiments and examples of the present invention disclosed above should be considered as illustrative in all points and not restrictive. In the above description, the scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view showing a form of a cutting edge processing part of a hard alloy substrate and a form of a surface processing part of a coating film in a cutting edge ridge line part of a coated hard alloy tool of the present invention.
FIG. 2 is a perspective view showing a form of a throwaway tip used for verifying the effect of the present invention.
FIG. 3 is a view for explaining crater wear occurring on a contact surface between chips and a rake surface of a throwaway tip during a cutting test.
FIG. 4A is a schematic perspective view for explaining the definition of an increased surface area ratio, and FIG. 4B is a view for explaining a method for obtaining a surface area of a measurement unit by sampling.
FIG. 5 is a cross-sectional view showing a cross-sectional shape of a work material used for intermittent cutting in a fracture resistance test.
FIG. 6A is a cross-sectional view of a coated hard alloy tool coated with a four-layer coating film before the coating film is surface-treated, and FIG. 6B is a surface treatment of the coating film. A cross-sectional view of the state in which the oxide ceramic layer remains in the entire cutting edge ridge line portion later, (c) is a state in which the oxide ceramic layer is removed in a part of the edge ridge line portion after the surface treatment of the coating film It is sectional drawing.
[Explanation of symbols]
1 Hard alloy substrate
2 Coating film
3 Cutting edge ridge
4 flank
6 Rake face

Claims

A hard alloy substrate having a cutting edge processing portion at a cutting edge ridge line portion connecting the flank and the rake surface, and a coating film coated on the surface of the hard alloy substrate, A coated hard alloy tool having a surface treatment portion at the cutting edge ridge line portion of the surface, wherein the curvature radius of the convex curved surface formed at the boundary portion between the flank and the blade edge treatment portion on the surface of the hard alloy substrate is Rs1, When the curvature radius of the convex curved surface formed at the boundary between the flank and the surface treatment portion on the surface of the coating film is Rc1, and the average film thickness of the coating film in the region other than the surface treatment portion is d, A coated hard alloy tool, wherein a coating film is formed so that Rc1 / (Rs1 + d) <1.0.

Rs2 is the radius of curvature of the convex curved surface formed at the boundary between the rake face and the blade edge processing portion on the surface of the hard alloy base material, and is formed at the boundary between the rake surface and the surface treatment portion on the surface of the coating film. The coated hard alloy tool according to claim 1, wherein a coating film is further formed so that Rc2 / (Rs2 + d)> 1.0 when the radius of curvature of the convex curved surface is Rc2.

The coated hard alloy tool according to claim 1, wherein Rc1 / (Rs1 + d) is formed to be 0.2 or more and 0.8 or less.

The coated hard alloy tool according to claim 2, wherein Rc2 / (Rs2 + d) is formed to be 2.0 or more and 5.0 or less.

When the film thickness of the thinnest portion of the coating film of the hard alloy substrate is 15 μm or more and the film thickness at the cutting edge ridge line portion thinned by the surface treatment is dx / d is 0. The coated hard alloy tool according to claim 1, wherein the hard alloy tool is formed so as to be 2 or more and 0.8 or less.

Rs2 / Rs1 is set to 0.7 or more and 1.3 or less when the curvature radius of the convex curved surface formed at the boundary portion between the rake face and the blade edge processing portion on the surface of the hard alloy substrate is Rs2. The coated hard alloy tool according to claim 1 formed.

When the radius of curvature of the convex curved surface formed at the boundary between the rake face and the surface treatment portion on the surface of the coating film is Rc2, Rc2 / Rc1 is formed to be 2.0 or more and 50 or less. The coated hard alloy tool according to claim 1.

When the width on the rake face side of the cutting edge processing portion on the surface of the coating film is a and the width on the flank face is b, the ratio a / b is 1.5 to 4.0. The coated hard alloy tool according to claim 1.

The coating film has a multilayer structure, at least one of which is made of an oxide ceramic layer, and a portion of the thickness of at least one layer of the oxide ceramic layer remains over the entire region of the cutting edge ridge. The coated hard alloy tool according to claim 1, wherein a surface treatment is performed on the coated hard alloy tool.

The coated hard alloy tool according to claim 1, wherein an increased surface area ratio in at least a part of a surface treatment portion on the surface of the coating film is 0.1% or more and 1.3% or less.