JP3618183B2 - Cemented carbide end mill for cutting hard materials - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、焼入れした金型用工具鋼の様な高硬度材を切削する際に用いる超硬合金エンドミルに関し、殊に組成および保磁力を特定した超硬合金を工具素材として用いると共に、その表面に適切な皮膜を被覆することによって、優れた耐摩耗性を発揮することのできる超硬合金エンドミルに関するものである。
【０００２】
【従来の技術】
金型用工具鋼の様な高硬度材を切削加工する際には、従来では焼入れ前に切削加工にて粗加工を行い、焼入れ後に放電加工、研削加工または切削加工によって仕上げ加工を行っていた。ところが近年では、工程の短縮を図ることを目的として、焼入れ後の金型材を切削加工だけで粗加工と仕上げ加工して金型製品とすることのできる様なエンドミルに対する要望が強くなっている。
【０００３】
こうした技術として、例えば特開平５−５７５１９号には、焼入れ後の高硬度材を切削するのに適する様に、切刃の切れ味を損なうことなく且つチッピングも十分に防止できる切刃形状の高硬度材切削用超硬合金製エンドミルが提案されている。またこうした切削工具の素材としてはＷＣ−Ｃｏ系超硬合金が汎用されているが、この超硬合金のＷＣ粒径の適切化や、Ｃｒ，Ｖ，Ｔａ等の元素を炭化物の形態で添加することによって、硬さや靭性等を改善できることも知られている（例えば、特公昭６２−５６９４４号）。
【０００４】
一方、高速度鋼や超硬合金等の工具母材表面に硬質皮膜を形成して、工具の耐摩耗性を向上する技術も各種提案されている。こうした硬質皮膜として、（Ａｌｘ Ｔｉ１−ｘ ）（Ｎｙ Ｃ１−ｙ ）（但し、０．５６≦ｘ≦０．７５，０．６≦ｙ≦１．０）で示される窒化物または炭窒化物（特開平２−１９４１５９号）、Ｔｉ（Ｃｘ Ｎ１−ｘ ）（但し、０．１≦ｘ≦０．６）で示される炭窒化物（特開平１−４２５７０号）、（Ａｌｘ Ｔｉ１−ｘ−ｙ Ｓｉｙ ）（Ｎｚ Ｃ１−ｚ ）（但し、０．０５≦ｘ≦０．７５，０．０１≦ｙ≦０．１，０．６≦ｚ≦１．０）で示される窒化物または炭窒化物（特開平７−３１０１７４号）、（Ａｌｘ Ｔｉ１−ｘ−ｙ Ｓｉｙ ）（Ｂｚ Ｎ１−ｚ ）（但し、０．０５≦ｘ≦０．７５，０．０１≦ｙ≦０．１，０．０１≦ｚ≦０．１２）で示される硼窒化物（特開平７−３１０１７１号）等、様々なものが知られている。
【０００５】
【発明が解決しようとする課題】
しかしながら、これまでに提案されている高硬度材切削用エンドミルでは、近年要求されている高い性能が発揮されているとは言えない。例えば前記特開平５−５７５１９号に開示された高硬度材切削用超硬合金製エンドミルでは、切刃形状の工夫だけしかされていないので、チッピング発生の抑制や耐摩耗性の点で十分とは言えなかった。
【０００６】
また超硬合金では、硬さを高くすると靭性が低下することが知られており、エンドミル等の切削工具として用いる場合において要求される種々の特性には相反するものが多く、これらの特性が直接的に工具寿命に結びつかないことが経験上知られている。更に、切削工具に要求される材料特性は工具の種類や被削材等によって異なる為に、夫々の場合に応じて最適な材料設計を行うことが重要である。
【０００７】
一方、前記した各種の硬質皮膜を工具母材表面に形成することは、切削工具の耐摩耗性を向上する上で有効であることは知られているが、こうした効果は各々の皮膜に対応した工具母材を使用することによって初めて発揮されるものであり、こうした点を考慮しなければ切削工具としての特性が十分に発揮されないことがある。
【０００８】
本発明は、こうした状況の下でなされたものであって、その目的は、最適な工具母材を明確にすることによって、焼入れした金型用工具鋼等の高硬度材を切削する場合に、チッピングの発生を抑制し且つ優れた耐摩耗性を発揮することのできる高硬度材切削用超硬合金エンドミル性を提供することにある。
【０００９】
【課題を解決するための手段】
上記目的を達成した本発明の高硬度材切削用超硬合金エンドミルとは、Ｃｏを主体とする結合相を６〜９重量％含む他、Ｖ：０．１〜０．９重量％，Ｃｒ：０．１〜１．５重量％，Ｔａ：０．１〜１．８重量％，Ｎｂ：０．１〜１．８重量％よりなる群から選択される１種以上を、炭化物、窒化物または炭窒化物の形態で含み、残部がＷＣおよび不可避不純物からなり、且つ保磁力が下記（１）式の関係を満足する超硬合金を工具母材とし、
［保磁力（Ｏｅ）］＞３９０−１０×［Ｃｏ含有量（重量％）］…（１）
この工具母材の少なくとも刃先表面に、周期律表の４ａ族元素，ＡｌまたはＳｉの窒化物、炭窒化物、硼化物、硼窒化物のいずれか、またはこれらの２種以上の複合化合物からなる皮膜若しくは複合皮膜を被覆した点に要旨を有するものである。
【００１０】
上記本発明の超硬合金エンドミルにおいては、エンドミルの切刃稜線の少なくとも先端部付近の軸直交断面に現れるすくい角が−３０〜０°であることが好ましい。
【００１１】
また本発明の超硬合金エンドミルにおいて、工具母材表面に被覆される皮膜としては、具体的には、下記に列挙するものが好ましい。即ち、下記に硬質皮膜は、上記工具母材表面に形成する皮膜とし相応しいものであり、こうした構成を採用することによって、工具母材と硬質皮膜との相乗効果によってエンドミルの耐摩耗性が一段と優れたものとなるのである。
【００１２】
（ａ）（Ａｌｘ Ｔｉ１−ｘ ）（Ｎｙ Ｃ１−ｙ ）
（但し、０．５６≦ｘ≦０．７５，０．６≦ｙ≦１．０）
で示される窒化物または炭窒化物。
（ｂ）Ｔｉ（Ｃｘ Ｎ１−ｘ ）（但し、０．１≦ｘ≦０．６）
で示される炭窒化物。
（ｃ）（Ａｌｘ Ｔｉ１−ｘ−ｙ Ｓｉｙ ）（Ｎｚ Ｃ１−ｚ ）
（但し、０．０５≦ｘ≦０．７５ ，０．０１≦ｙ≦０．１，０．６≦ｚ≦１．０）
で示される窒化物または炭窒化物。
（ｄ）（Ａｌｘ Ｔｉ１−ｘ−ｙ Ｓｉｙ ）（Ｂｚ Ｎ１−ｚ ）
（但し、０．０５≦ｘ≦０．７５，０．０１≦ｙ≦０．１，０．０１≦ｚ≦０．１２）
で示される硼窒化物。
【００１３】
【発明の実施の形態】
本発明者らは、超硬合金エンドミルの耐摩耗性を向上させるべく、特にエンドミルを構成する工具母材に着目し、高硬度材切削用超硬合金エンドミルとして最適な工具母材の実現を目指して様々な検討を行った。
【００１４】
工具母材を硬くすれば耐摩耗性を向上させることができることが予想されるが、その為にＣｏ含有量を低下させると工具母材は硬くなるが、チッピングが発生し易くなり、却って工具寿命が低下するということが多い。また超硬合金の靭性を評価する基準として、抗折力や破壊靭性値（ＫＩＣ）が用いられているが、エンドミル等の工具として用いる場合に発生するチッピングは、これらとは直接的な関係がないことが経験的に知られており、チッピングの発生を支配する材料のパラメーターについては的確に把握されているとは言えない。
【００１５】
そこで本発明者らは、種々の超硬合金を工具材料にしてエンドミルを作成し、高硬度材の切削を試み、その性能について調査した。その結果について、材料のパラメーターとして保磁力を選び、この保磁力とエンドミルの性能との関係について整理したところ、保磁力とＣｏ含有量が特定の関係を満足する場合には、エンドミルのチッピングが抑制され得ることを見出した。即ち、工具母材の保磁力が前記（１）式の関係を満足する場合には、エンドミルのチッピングが抑制されて優れた特性が発揮されたのである。
【００１６】
但し、前記（１）式の関係を満足するだけで、本発明の目的が達成されるものではなく、超硬合金の組成を適切に調節する必要がある。次に、本発明において工具母材として用いる超硬合金の組成を規定した理由について説明する。
【００１７】
本発明で工具母材として用いる超硬合金は、Ｃｏを主体とする結合相を６〜９重量％含む必要がある。結合相が６重量％未満では硬質相を結合させる力が不足して超硬合金にチッピングや欠けが発生し易くなり、９重量％を超えると十分な耐摩耗性が得られない。尚「Ｃｏを主体とする」とは、結合相を構成する元素が主にＣｏであることを意味し、後述の炭化物等の形態で添加される元素やＷを固溶していても良いことは勿論である。要するに、本発明においては、Ｃｏ等の結合相となる元素の総量が６〜９重量％であれば上記効果が発揮されるのである。
【００１８】
また上記超硬合金は、Ｖ：０．１〜０．９重量％，Ｃｒ：０．１〜１．５重量％，Ｔａ：０．１〜１．８重量％，Ｎｂ：０．１〜１．８重量％よりなる群から選択される１種以上を含む必要がある。これらの元素は、炭化物、窒化物または炭窒化物等の形態で添加されるが、その添加量が０．１重量％未満ではその効果が十分に発揮されず、また上記した上限を超えると却ってチッピング発生の原因となる。
【００１９】
本発明は工具母材の耐摩耗性の向上およびチッピングの抑制に主眼を置いたものであるが、工具母材表面に周期律表の４ａ族元素，ＡｌまたはＳｉの窒化物、炭窒化物、硼化物、硼窒化物のいずれか、またはこれらの２種以上の複合化合物からなる皮膜若しくは複合皮膜を被覆することも必要である。即ち、これらの皮膜を被覆しなければ、切削時に早期に工具母材表面に大きな摩耗やチッピングが発生し、上記した工具母材の改善効果が十分に発揮されなくなる。
【００２０】
こうした皮膜として、上記した様に、（Ａｌｘ Ｔｉ１−ｘ ）（Ｎｙ Ｃ１−ｙ ）（但し、０．５６≦ｘ≦０．７５，０．６≦ｙ≦１．０）で示される窒化物または炭窒化物、Ｔｉ（Ｃｘ Ｎ１−ｘ ）（但し、０．１≦ｘ≦０．６）で示される炭窒化物、（Ａｌｘ Ｔｉ１−ｘ−ｙ Ｓｉｙ ）（Ｎｚ Ｃ１−ｚ ）（但し、０．０５≦ｘ≦０．７５，０．０１≦ｙ≦０．１，０．６≦ｚ≦１．０）で示される窒化物または炭窒化物、（Ａｌｘ Ｔｉ１−ｘ−ｙ Ｓｉｙ ）（Ｂｚ Ｎ１−ｚ ）（但し、０．０５≦ｘ≦０．７５，０．０１≦ｙ≦０．１，０．０１≦ｚ≦０．１２）で示される硼窒化物、等の各皮膜が好ましい。
【００２１】
ところで形状面からチッピングを抑制するという観点から、スクエアエンドミル等では、外周刃切刃の軸直交断面に現れるすくい角を刃長全体に亘り−３０〜０°にしたり、底刃にいわゆる面取りをすることが好ましい。ここで面取りとは、エンドミルの切刃稜線の少なくとも先端部近傍のすくい角を−３０〜０°にした場合を例示したものである。一方、ボールエンドミルや外周刃と底刃の連続部にＲ刃を持つエンドミルのＲ刃についても同様であり、エンドミルの切刃稜線の少なくとも先端部付近の軸直交断面に現れるすくい角を−３０〜０°にすることが好ましい。
【００２２】
尚本発明で工具母材として用いる超硬合金は、保磁力とＣｏ含有量が特定の関係を満足するものであり、保磁力は成分組成と直接的に関係するものではないが、この保磁力を調整するに当たっては、ＷＣの粒度分布、合金炭素量、焼結条件を合金系に応じて選定する、等の手段を採用することができる。
【００２３】
次に本発明の実施例を示すが、本発明はもとより下記実施例によって制限を受けるものではなく、前後記の趣旨に適合し得る範囲で適当に変更を加えて実施することも勿論可能であり、それらはいずれも本発明の技術的範囲に含まれる。
【００２４】
【実施例】
実施例１
原料粉末として、平均粒径：０．４〜０．７μｍのＷＣ、平均粒径：１．３μｍのＣｏ、平均粒径：１．３μｍのＣｒ３ Ｃ２ 、平均粒径：１．３μｍのＶＣ、平均粒径：１．０μｍのＴａＣ等を用い、これら原料粉末を下記表１のＡ〜Ｊの組成となる様に配合した。
【００２５】
配合した原料粉末を、アトライタを用いて有機溶媒中で８時間混合し、パラフィンを加えた後乾燥し、１００ＭＰａで圧粉成形した後、脱ロウ・予備焼結した。この予備焼結品を、エンドミルにする為の素材形状に研削加工し、１４００℃で１時間真空焼結した後、Ａｒ雰囲気下で１００ＭＰａ、１３５０℃で１時間熱間静水圧加圧処理（ＨＩＰ処理）を施してエンドミル素材とした。
【００２６】
【表１】
上記エンドミル素材を、直径：１０ｍｍ、ねじれ角：４５°、心厚：８．５ｍｍ、刃数：６枚、外周２番角：６°、外周すくい角：−１３°、等を諸元とするスクエアエンドミル、または直径：１０ｍｍ、先端部Ｒ刃のＲ：５ｍｍ、ねじれ角：３０°、心厚：７．０ｍｍ、刃数：２枚、外周２番角：１０°、外周すくい角：６°、Ｒ刃２番角：６°、Ｒ刃すくい角：−５°、等を諸元とするボールエンドミル母材に研削加工し、刃部表面に下記表２および表３に示す組成の皮膜を被覆し、スクエアエンドミルに関しては下記切削条件ａで、ボールエンドミルに関しては下記切削条件ｂで切削試験を行った。
【００２８】
（切削条件ａ）
切削方法 ：側面切削ダウンカット
被削材 ：ＳＫＤ１１（硬さＨＲＣ６０）
切込み ：Ｒｄ ０．５ｍｍ×Ａｄ １０ｍｍ
回転数 ：６５０ｒｐｍ
送り速度 ：１２０ｍｍ／ｍｉｎ
切削油 ：乾式
切削長 ：２０ｍ
（切削条件ｂ）
切削方法 ：ダウンカット
被削材 ：ＳＫＤ１１（硬さＨＲＣ６０）
切込み ：Ａｄ ５ｍｍ×ピックフィード０．２ｍｍ
回転数 ：５６００ｒｐｍ
送り速度 ：１１２０ｍｍ／ｍｉｎ
切削油 ：乾式
切削長 ：２５ｍ
【００２９】
【表２】
【表３】
切削試験結果を、スクエアエンドミルに関しては表２に、ボールエンドミルに関しては表３に夫々示すが、これらの結果から次の様に考察できる。
まずＮｏ．１，２，５〜７、１３，１５および１６のものは、Ｃｏ含有量が本発明で規定する範囲を外れるものであり、このうちＣｏ含有量が６重量％未満のもの（Ｎｏ．１，２，１３）では比較的短い切削長において欠けが発生して寿命となっており、一方Ｃｏ含有量が９重量％を超えるもの（Ｎｏ．５，６，７，１６）では摩耗幅が大きく寿命となっている。
またＮｏ．３，４，１４および１５のものは、保磁力が本発明で規定する範囲を外れるものであり、いずれも比較的短い切削長においてチッピングが発生し、寿命に至っている。
【００３２】
これらに対し、本発明で規定する要件をす満足するＮｏ．８〜１２，１７〜２０のものでは、いずれもチッピングを起こさず、摩耗幅も小さくなっていることが分かる。
【００３３】
図１は、上記した切削試験結果に基づいて、Ｃｏ含有量と保磁力がチッピングの発生に及ぼす影響について示したグラフである。この結果から明らかな様に、工具母材のＣｏ含有量が６〜９重量％で且つ保磁力が前記（１）式の関係を満足するものでは、チッピングや欠けが発生することなく、摩耗量が少なくなっていることが分かる。
【００３４】
【発明の効果】
本発明は以上のように構成されており、焼入れした金型用工具鋼等の高硬度材を切削する場合に、チッピング等の発生を抑制し且つ優れた耐摩耗性を発揮することのできる高硬度材切削用超硬合金エンドミルが実現できた。
【図面の簡単な説明】
【図１】Ｃｏ含有量と保磁力がチッピングの発生や摩耗に及ぼす影響について示したグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cemented carbide end mill used when cutting a hardened material such as a hardened tool steel, and in particular, a cemented carbide having a specified composition and coercive force is used as a tool material and its surface. The present invention relates to a cemented carbide end mill capable of exhibiting excellent wear resistance by coating with a suitable film.
[0002]
[Prior art]
When cutting high-hardness materials such as tool steel for molds, conventionally, roughing is performed by cutting before quenching, and finishing is performed by electrical discharge machining, grinding, or cutting after quenching. . However, in recent years, for the purpose of shortening the process, there has been a strong demand for an end mill that can form a die product by roughing and finishing the die material after quenching only by cutting.
[0003]
As such a technique, for example, in Japanese Patent Laid-Open No. 5-57519, a cutting edge-shaped high hardness capable of sufficiently preventing chipping without impairing the sharpness of the cutting edge so as to be suitable for cutting a hardened material after quenching. A cemented carbide end mill for material cutting has been proposed. In addition, WC-Co based cemented carbide is widely used as a material for such cutting tools, and the WC grain size of the cemented carbide is optimized, and elements such as Cr, V, and Ta are added in the form of carbides. It is also known that the hardness and toughness can be improved (for example, Japanese Examined Patent Publication No. 62-56944).
[0004]
On the other hand, various techniques for improving the wear resistance of a tool by forming a hard film on the surface of a tool base material such as high speed steel or cemented carbide have been proposed. As such a hard film, a nitride represented by (Al x Ti 1-x ) (N y C 1-y ) (where 0.56 ≦ x ≦ 0.75, 0.6 ≦ y ≦ 1.0) or Carbonitrides (JP-A-1-42570) represented by carbonitrides (JP-A-2-194159), Ti (C x N 1-x ) (where 0.1 ≦ x ≦ 0.6), ( Al x Ti 1-xy Si y ) (N z C 1-z ) (where 0.05 ≦ x ≦ 0.75, 0.01 ≦ y ≦ 0.1, 0.6 ≦ z ≦ 1. 0) nitrides or carbonitrides (Japanese Patent Laid-Open No. 7-310174), (Al x Ti 1-xy Si y ) (B z N 1-z ) (where 0.05 ≦ x ≦ 0) .75, 0.01 ≦ y ≦ 0.1, 0.01 ≦ z ≦ 0.12), and the like, etc. (Japanese Patent Laid-Open No. 7-310171) are known.
[0005]
[Problems to be solved by the invention]
However, it cannot be said that the high performance required in recent years has been exhibited in the end mills for cutting hard materials proposed so far. For example, in the cemented carbide end mill for cutting high hardness materials disclosed in JP-A-5-57519, only the cutting edge shape is devised, so that it is sufficient in terms of suppression of chipping and wear resistance. I could not say.
[0006]
In addition, it is known that cemented carbide lowers toughness when the hardness is increased, and there are many conflicting properties required when used as a cutting tool such as an end mill. It is known from experience that it does not lead to tool life. Furthermore, since the material characteristics required for the cutting tool differ depending on the type of tool, work material, etc., it is important to perform an optimum material design according to each case.
[0007]
On the other hand, it is known that forming the various hard coatings on the surface of the tool base material is effective in improving the wear resistance of the cutting tool, but such an effect corresponds to each coating. It is exhibited for the first time by using a tool base material, and the characteristics as a cutting tool may not be sufficiently exhibited unless these points are taken into consideration.
[0008]
The present invention has been made under such circumstances, and its purpose is to clarify the optimum tool base material, and to cut a hard material such as a hardened tool steel, etc. An object of the present invention is to provide a cemented carbide end mill property for cutting a hard material capable of suppressing occurrence of chipping and exhibiting excellent wear resistance.
[0009]
[Means for Solving the Problems]
The cemented carbide end mill for cutting high-hardness material according to the present invention that achieves the above object includes 6 to 9% by weight of a binder phase mainly composed of Co, V: 0.1 to 0.9% by weight, Cr: At least one selected from the group consisting of 0.1 to 1.5 wt%, Ta: 0.1 to 1.8 wt%, Nb: 0.1 to 1.8 wt%, carbide, nitride or A cemented carbide containing in the form of carbonitride, the balance being composed of WC and inevitable impurities, and coercive force satisfying the relationship of the following formula (1) is used as a tool base material,
[Coercivity (Oe)]> 390-10 × [Co content (% by weight)] (1)
At least the surface of the cutting edge of the tool base material is composed of any of the group 4a elements of the periodic table, Al or Si nitride, carbonitride, boride, boronitride, or a composite compound of two or more of these. It has a gist in that it is coated with a film or a composite film.
[0010]
In the cemented carbide end mill of the present invention, it is preferable that the rake angle appearing in the axial orthogonal cross section at least near the tip of the cutting edge ridge line of the end mill is −30 to 0 °.
[0011]
Further, in the cemented carbide end mill of the present invention, as the film to be coated on the tool base material surface, specifically, those listed below are preferable. In other words, the hard film described below is suitable as a film to be formed on the surface of the tool base material. By adopting such a configuration, the wear resistance of the end mill is further improved by the synergistic effect of the tool base material and the hard film. It will be a thing.
[0012]
(A) (Al x Ti 1 -x) (N y C 1-y)
(However, 0.56 ≦ x ≦ 0.75, 0.6 ≦ y ≦ 1.0)
Nitride or carbonitride represented by
(B) Ti (C x N 1-x ) (where 0.1 ≦ x ≦ 0.6)
Carbonitride shown in
(C) (Al x Ti 1 -x-y Si y) (N z C 1-z)
(However, 0.05 ≦ x ≦ 0.75, 0.01 ≦ y ≦ 0.1, 0.6 ≦ z ≦ 1.0)
Nitride or carbonitride represented by
(D) (Al x Ti 1 -x-y Si y) (B z N 1-z)
(However, 0.05 ≦ x ≦ 0.75, 0.01 ≦ y ≦ 0.1, 0.01 ≦ z ≦ 0.12)
Boronide shown by
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In order to improve the wear resistance of the cemented carbide end mill, the present inventors focused on the tool base material that constitutes the end mill, and aimed to realize an optimum tool base material as a cemented carbide end mill for cutting hard materials. Various studies were conducted.
[0014]
It is expected that the wear resistance can be improved if the tool base material is hardened. However, if the Co content is reduced, the tool base material will be hardened, but chipping is likely to occur. Often decreases. In addition, bending strength and fracture toughness value (K IC ) are used as criteria for evaluating the toughness of cemented carbide, but chipping that occurs when used as a tool such as an end mill is directly related to these. It has been empirically known that there is no material, and it cannot be said that the parameters of the material governing the occurrence of chipping are accurately grasped.
[0015]
Therefore, the inventors made end mills using various cemented carbides as tool materials, tried cutting high-hardness materials, and investigated their performance. As a result, the coercive force was selected as a material parameter, and the relationship between the coercive force and the performance of the end mill was arranged. When the coercive force and the Co content satisfy a specific relationship, chipping of the end mill was suppressed. Found that could be. That is, when the coercive force of the tool base material satisfies the relationship of the above formula (1), the end mill chipping is suppressed and excellent characteristics are exhibited.
[0016]
However, the object of the present invention is not achieved only by satisfying the relationship of the formula (1), and it is necessary to appropriately adjust the composition of the cemented carbide. Next, the reason for defining the composition of the cemented carbide used as the tool base material in the present invention will be described.
[0017]
The cemented carbide used as the tool base material in the present invention needs to contain 6 to 9% by weight of a binder phase mainly composed of Co. If the binder phase is less than 6% by weight, the strength for binding the hard phase is insufficient, and chipping and chipping are likely to occur in the cemented carbide, and if it exceeds 9% by weight, sufficient wear resistance cannot be obtained. The phrase “consisting mainly of Co” means that the element constituting the binder phase is mainly Co, and the element added in the form of carbide or the like to be described later or W may be dissolved. Of course. In short, in the present invention, the above effect is exhibited when the total amount of elements such as Co, which becomes a binder phase, is 6 to 9% by weight.
[0018]
The cemented carbide is composed of V: 0.1 to 0.9% by weight, Cr: 0.1 to 1.5% by weight, Ta: 0.1 to 1.8% by weight, Nb: 0.1 to 1%. It is necessary to include at least one selected from the group consisting of .8% by weight. These elements are added in the form of carbides, nitrides, carbonitrides, etc., but if the addition amount is less than 0.1% by weight, the effect is not sufficiently exhibited, and if the above upper limit is exceeded, Causes chipping.
[0019]
The present invention focuses on improving the wear resistance of the tool base material and suppressing chipping, but on the surface of the tool base material, Group 4a element of the periodic table, Al or Si nitride, carbonitride, It is also necessary to coat a film or composite film made of either boride, boronitride, or a composite compound of two or more of these. That is, if these coatings are not coated, large wear or chipping occurs on the surface of the tool base material at an early stage during cutting, and the above-described effect of improving the tool base material is not sufficiently exhibited.
[0020]
As described above, as described above, (Al x Ti 1-x ) (N y C 1-y ) (where 0.56 ≦ x ≦ 0.75, 0.6 ≦ y ≦ 1.0) Nitride or carbonitride, carbonitride represented by Ti (C x N 1-x ) (where 0.1 ≦ x ≦ 0.6), (Al x Ti 1-xy Si y ) ( N z C 1-z ) (provided that 0.05 ≦ x ≦ 0.75, 0.01 ≦ y ≦ 0.1, 0.6 ≦ z ≦ 1.0), (Al x Ti 1-xy Si y ) (B z N 1-z ) (However, 0.05 ≦ x ≦ 0.75, 0.01 ≦ y ≦ 0.1, 0.01 ≦ z ≦ 0 Each film such as boronitride represented by .12) is preferable.
[0021]
By the way, from the viewpoint of suppressing chipping from the shape surface, in a square end mill or the like, the rake angle appearing in the axial orthogonal cross section of the outer peripheral cutting edge is set to −30 to 0 ° over the entire blade length, or the bottom edge is chamfered. It is preferable. Here, chamfering exemplifies a case where the rake angle in the vicinity of at least the tip of the cutting edge ridge line of the end mill is set to −30 to 0 °. On the other hand, the same applies to a ball end mill or an end mill R-blade having an R-blade at the continuous portion of the outer peripheral blade and the bottom blade. It is preferable to make it 0 °.
[0022]
In the cemented carbide used as the tool base material in the present invention, the coercive force and the Co content satisfy a specific relationship, and the coercive force is not directly related to the component composition. In adjusting the above, it is possible to adopt means such as selecting the particle size distribution of WC, the amount of alloy carbon, and the sintering conditions according to the alloy system.
[0023]
Next, examples of the present invention will be shown. However, the present invention is not limited by the following examples as a matter of course, and it is needless to say that the present invention can be implemented with appropriate modifications within a range that can meet the gist of the preceding and following descriptions. These are all included in the technical scope of the present invention.
[0024]
【Example】
Example 1
As a raw material powder, WC having an average particle size of 0.4 to 0.7 μm, Co having an average particle size of 1.3 μm, Cr 3 C 2 having an average particle size of 1.3 μm, and VC having an average particle size of 1.3 μm These raw material powders were blended so as to have the compositions of A to J in Table 1 below, using TaC or the like having an average particle diameter of 1.0 μm.
[0025]
The blended raw material powder was mixed in an organic solvent for 8 hours using an attritor, dried after adding paraffin, compacted at 100 MPa, dewaxed and pre-sintered. This pre-sintered product is ground into an end mill material shape, vacuum sintered at 1400 ° C. for 1 hour, and then subjected to hot isostatic pressing (HIP) at 100 MPa and 1350 ° C. for 1 hour in an Ar atmosphere. To give an end mill material.
[0026]
[Table 1]
The above-mentioned end mill material has various dimensions such as diameter: 10 mm, twist angle: 45 °, core thickness: 8.5 mm, number of blades: 6, outer peripheral second angle: 6 °, outer peripheral rake angle: −13 °, etc. Square end mill, or diameter: 10 mm, tip R radius R: 5 mm, helix angle: 30 °, core thickness: 7.0 mm, number of blades: 2 outer peripheral angle: 10 °, outer rake angle: 6 ° R edge No. 2 angle: 6 °, R edge rake angle: -5 °, etc., are ground to a ball end mill base material, and a coating film having the composition shown in Table 2 and Table 3 below is applied to the blade surface. The cutting test was carried out under the following cutting condition a for the square end mill and under the following cutting condition b for the ball end mill.
[0028]
(Cutting conditions a)
Cutting method: Side cut down cut work material: SKD11 (hardness HRC60)
Cutting depth: R d 0.5 mm × A d 10 mm
Rotation speed: 650rpm
Feeding speed: 120mm / min
Cutting oil: Dry cutting length: 20m
(Cutting condition b)
Cutting method: Down-cut work material: SKD11 (hardness HRC60)
Cut: A d 5mm × pick-feed 0.2mm
Rotation speed: 5600rpm
Feeding speed: 1120mm / min
Cutting oil: Dry cutting length: 25m
[0029]
[Table 2]
[Table 3]
The results of the cutting test are shown in Table 2 for the square end mill and in Table 3 for the ball end mill, and these results can be considered as follows.
First, no. 1, 2, 5-7, 13, 15 and 16 are those whose Co content is outside the range defined in the present invention, among which the Co content is less than 6% by weight (No. 1, 2 and 13), chipping occurs at a relatively short cutting length, resulting in a life, while those having a Co content exceeding 9% by weight (No. 5, 6, 7, 16) have a large wear width and a long life. It has become.
No. Those of 3, 4, 14 and 15 have a coercive force outside the range defined in the present invention, and all of them have chipping at a relatively short cutting length and have reached the end of their service life.
[0032]
On the other hand, No. satisfying the requirements defined in the present invention. It can be seen that 8-12 and 17-20 do not cause chipping and wear width is small.
[0033]
FIG. 1 is a graph showing the influence of the Co content and coercive force on the occurrence of chipping based on the above-described cutting test results. As is apparent from this result, when the Co content of the tool base material is 6 to 9% by weight and the coercive force satisfies the relationship of the above formula (1), the amount of wear does not occur without chipping or chipping. It can be seen that is decreasing.
[0034]
【The invention's effect】
The present invention is configured as described above, and is capable of suppressing the occurrence of chipping and exhibiting excellent wear resistance when cutting a hard material such as a hardened tool steel. A cemented carbide end mill for cutting hard materials has been realized.
[Brief description of the drawings]
FIG. 1 is a graph showing the effects of Co content and coercivity on the occurrence of chipping and wear.
Claims (6)
［保磁力（Ｏｅ）］＞３９０−１０×［Ｃｏ含有量（重量％）］…（１）
この工具母材の少なくとも刃先表面に、周期律表の４ａ族元素，ＡｌまたはＳｉの窒化物、炭窒化物、硼化物、硼窒化物のいずれか、またはこれらの２種以上の複合化合物からなる皮膜若しくは複合皮膜を被覆したものであることを特徴とする高硬度材切削用超硬合金エンドミル。It is a cemented carbide end mill for cutting high-hardness materials, including 6 to 9% by weight of a binder phase mainly composed of Co, V: 0.1 to 0.9% by weight, Cr: 0.1 to 1.5 At least one selected from the group consisting of wt%, Ta: 0.1-1.8 wt%, Nb: 0.1-1.8 wt%, carbide, nitride, carbonitride, composite carbide or A cemented carbide containing a composite carbonitride, the balance being WC and inevitable impurities, and a coercive force satisfying the relationship of the following formula (1) is used as a tool base material:
[Coercivity (Oe)]> 390-10 × [Co content (% by weight)] (1)
At least the surface of the cutting edge of the tool base material is composed of any of the group 4a elements of the periodic table, Al or Si nitride, carbonitride, boride, boronitride, or a composite compound of two or more of these. A cemented carbide end mill for cutting high-hardness materials, characterized by being coated with a film or a composite film.
（Ａｌｘ Ｔｉ１−ｘ ）（Ｎｙ Ｃ１−ｙ ）（但し、０．５６≦ｘ≦０．７５，０．６≦ｙ≦１．０）
で示される窒化物または炭窒化物である請求項１または２に記載の高硬度材切削用超硬合金エンドミル。The coating on the tool base material surface
(Al x Ti 1-x ) (N y C 1-y ) (however, 0.56 ≦ x ≦ 0.75, 0.6 ≦ y ≦ 1.0)
The cemented carbide end mill for cutting a hard material according to claim 1 or 2, wherein the carbide or carbonitride is represented by the following formula.
Ｔｉ（Ｃｘ Ｎ１−ｘ ）（但し、０．１≦ｘ≦０．６）
で示される炭窒化物である請求項１または２に記載の高硬度材切削用超硬合金エンドミル。The coating on the tool base material surface
Ti (C x N 1-x ) (however, 0.1 ≦ x ≦ 0.6)
The cemented carbide end mill for high-hardness material cutting according to claim 1 or 2, wherein the carbide is a carbonitride represented by the following formula.
（Ａｌｘ Ｔｉ１−ｘ−ｙ Ｓｉｙ ）（Ｎｚ Ｃ１−ｚ）（但し、０．０５≦ｘ≦０．７５，０．０１≦ｙ≦０．１，０．６≦ｚ≦１．０）
で示される窒化物または炭窒化物である請求項１または２に記載の高硬度材切削用超硬合金エンドミル。The coating on the tool base material surface
(Al x Ti 1-xy Si y ) (N z C 1-z ) (However, 0.05 ≦ x ≦ 0.75, 0.01 ≦ y ≦ 0.1, 0.6 ≦ z ≦ 1 .0)
The cemented carbide end mill for cutting a hard material according to claim 1 or 2, wherein the carbide or carbonitride is represented by the following formula.
（Ａｌｘ Ｔｉ１−ｘ−ｙ Ｓｉｙ ）（Ｂｚ Ｎ１−ｚ）（但し、０．０５≦ｘ≦０．７５，０．０１≦ｙ≦０．１，０．０１≦ｚ≦０．１２）
で示される硼窒化物である請求項１または２に記載の高硬度材切削用超硬合金エンドミル。The coating on the tool base material surface
(Al x Ti 1-xy Si y ) (B z N 1-z ) (However, 0.05 ≦ x ≦ 0.75, 0.01 ≦ y ≦ 0.1, 0.01 ≦ z ≦ 0 .12)
The cemented carbide end mill for cutting a high-hardness material according to claim 1 or 2, which is a boronitride represented by the following formula.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29416796A JP3618183B2 (en) | 1996-11-06 | 1996-11-06 | Cemented carbide end mill for cutting hard materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29416796A JP3618183B2 (en) | 1996-11-06 | 1996-11-06 | Cemented carbide end mill for cutting hard materials |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10138032A JPH10138032A (en) | 1998-05-26 |
| JP3618183B2 true JP3618183B2 (en) | 2005-02-09 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29416796A Expired - Lifetime JP3618183B2 (en) | 1996-11-06 | 1996-11-06 | Cemented carbide end mill for cutting hard materials |
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| Country | Link |
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| JP (1) | JP3618183B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE519005C2 (en) * | 1999-03-26 | 2002-12-17 | Sandvik Ab | Coated cemented carbide inserts |
| SE530517C2 (en) * | 2006-08-28 | 2008-06-24 | Sandvik Intellectual Property | Coated cemented carbide inserts, ways to manufacture them and their use for milling hard Fe-based alloys> 45 HRC |
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1996
- 1996-11-06 JP JP29416796A patent/JP3618183B2/en not_active Expired - Lifetime
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| Publication number | Publication date |
|---|---|
| JPH10138032A (en) | 1998-05-26 |
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