JP6102571B2 - Surface coated cutting tool - Google Patents
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Description
本発明は、炭素鋼等の切削加工において、硬質被覆層がすぐれた耐チッピング性、耐摩耗性を発揮する表面被覆切削工具（以下、被覆工具という）に関するものである。 The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent chipping resistance and abrasion resistance in a cutting process of carbon steel or the like.
一般に、被覆工具には、各種の鋼や鋳鉄などの被削材の旋削加工や平削り加工にバイトの先端部に着脱自在に取り付けて用いられるインサート、前記被削材の穴あけ切削加工などに用いられるドリル、さらに前記被削材の面削加工や溝加工、肩加工などに用いられるソリッドタイプのエンドミルなどがあり、また前記インサートを着脱自在に取り付けて前記ソリッドタイプのエンドミルと同様に切削加工を行うインサート式エンドミル工具などが知られている。 In general, for coated tools, inserts that are used to attach and detachably attach to the tip of a cutting tool for turning and planing of various steels and cast irons, and drilling of the work material. Drills, solid type end mills used for chamfering, grooving, shoulder processing, etc. of the work material, etc. In addition, the insert can be detachably attached to perform cutting as in the solid type end mill. Insert type end mill tools to perform are known.
例えば、特許文献１に示すように、工具基体とその表面に形成された硬質被膜とを具え、逃げ面およびすくい面を有する被覆切削工具であって、刃先稜線から逃げ面方向に０．２０ｍｍ以内の領域α１と、実質的に切削に関与する範囲のうち領域α１に隣接して逃げ面方向に領域α１の０．５倍以上の範囲を有する領域α２と、刃先稜線からすくい面方向に０．５０ｍｍ以内の領域β１と、実質的に切削に関与する範囲のうち領域β１に隣接してすくい面方向に領域β１の０．５倍以上の範囲を有する領域β２とを有し、前記領域α１およびβ１の範囲で前記硬質被膜は以下の（ａ）、（ｂ）の構造を有する層を含み、前記領域α２およびβ２の範囲で前記硬質被膜は以下の（ｃ）、（ｄ）の構造を有する層を含むことを特徴とする被覆工具が知られている。
（ａ）結晶粒の成長方向が、工具基体表面に対して実質的に垂直方向で、結晶粒の粒界の２等分線に対して±２°以内の角度を有する。
（ｂ）結晶粒のアスペクト比が５以上である。
（ｃ）結晶粒の成長方向が、結晶粒の粒界の２等分線に対して±２°超〜±４０°以内の角度を有する。
（ｄ）結晶粒のアスペクト比が５以上である。
For example, as shown in Patent Document 1, a coated cutting tool having a tool base and a hard coating formed on the surface thereof and having a flank face and a rake face, and within 0.20 mm in the flank direction from the edge of the blade edge Of the region α1, a region α2 having a range of 0.5 times or more of the region α1 in the flank direction adjacent to the region α1 in a range substantially involved in cutting, and 0. A region β1 within 50 mm, and a region β2 having a range of 0.5 times or more of the region β1 in the rake face direction adjacent to the region β1 in a range substantially involved in cutting, and the region α1 and In the range of β1, the hard coating includes layers having the following structures (a) and (b), and in the range of the regions α2 and β2, the hard coating has the following structures (c) and (d). Coating tools characterized by containing layers are known There.
(A) The growth direction of the crystal grains is substantially perpendicular to the surface of the tool base and has an angle within ± 2 ° with respect to the bisector of the grain boundary of the crystal grains.
(B) The aspect ratio of the crystal grains is 5 or more.
(C) The growth direction of the crystal grains has an angle of more than ± 2 ° to within ± 40 ° with respect to the bisector of the grain boundary of the crystal grains.
(D) The aspect ratio of the crystal grains is 5 or more.
また、被覆工具においては、その切削性能、特に、耐チッピング性、耐摩耗性等の改善を図るべく、硬質被覆層の組織構造について種々の提案がなされている。 In the coated tool, various proposals have been made for the structure of the hard coating layer in order to improve the cutting performance, particularly the chipping resistance and wear resistance.
例えば、特許文献２には、アークイオンプレーティング法によって成膜されたＣおよび／またはＦを合計で３〜２１ａｔ％含有するＣｒＮ膜であって該ＣｒＮ膜においてＸ線回折強度比（２００）／（１１１）が０．２以上である場合に、より確実にＣｒＮ膜の硬度が高くなることが開示されている。 For example, Patent Document 2 discloses a CrN film containing 3 to 21 at% in total of C and / or F formed by an arc ion plating method, and the X-ray diffraction intensity ratio (200) / It is disclosed that the hardness of the CrN film is more reliably increased when (111) is 0.2 or more.
また、特許文献３には、耐摩耗性と靭性とを両立させるとともに、基材との密着性にもすぐれた被膜を備えた被覆工具として、基材上に形成された被膜は、第１被膜層を含み、該第１被膜層は、微細組織領域と粗大組織領域とを含み、該微細組織領域は、それを構成する化合物の平均結晶粒径が１０〜２００ｎｍであり、かつ該第１被膜層の表面側から該第１被膜層の全体の厚みに対して５０％以上の厚みとなる範囲を占めて存在し、かつ−４ＧＰａ以上−２ＧＰａ以下の範囲の応力である平均圧縮応力を有し、該第１被膜層は、その厚み方向に応力分布を有しており、その応力分布において２つ以上の極大値または極小値を持ち、それらの極大値または極小値は厚み方向表面側に位置するものほど高い圧縮応力を有する被覆工具が記載されている。 Patent Document 3 discloses a coating film formed on a base material as a coating tool having a coating film that achieves both wear resistance and toughness and also has excellent adhesion to the base material. The first coating layer includes a fine structure region and a coarse structure region, and the fine structure region has an average crystal grain size of a compound constituting the first coating layer of 10 to 200 nm, and the first coating layer. It occupies a range that is 50% or more of the total thickness of the first coating layer from the surface side of the layer, and has an average compressive stress that is a stress in the range of −4 GPa to −2 GPa. The first coating layer has a stress distribution in the thickness direction, and has two or more maximum values or minimum values in the stress distribution, and these maximum values or minimum values are located on the surface side in the thickness direction. A coated tool with a higher compressive stress is described. There.
そして、従来被覆工具の硬質被覆層として汎用されているＡｌ−Ｃｒ複合窒化物層は、例えば、図１に示すように、物理蒸着装置の１種であるアークイオンプレーティング装置に工具基体を装入し、工具基体に、例えば、−１００Ｖのバイアス電圧を印加しながら、ヒータで工具基体を５００℃程度の温度に加熱した状態で、装置内に反応ガスとして窒素ガスおよび／またはＣＨ４ガスを導入し、アノード電極とＡｌ―Ｃｒ合金がセットされたカソード電極との間に、所定の電流条件でアーク放電を発生させ、同時に反応雰囲気を所定のガス圧に維持することにより工具基体表面に、ＡｌとＣｒの複合窒化物層を蒸着形成することにより製造できることも知られている。 An Al—Cr composite nitride layer that has been widely used as a hard coating layer of a conventional coated tool, for example, has a tool base mounted on an arc ion plating apparatus, which is a kind of physical vapor deposition apparatus, as shown in FIG. For example, while applying a bias voltage of −100 V to the tool base, the tool base is heated to a temperature of about 500 ° C. with a heater, and nitrogen gas and / or CH 4 gas is used as a reaction gas in the apparatus. Introduced and generated an arc discharge under a predetermined current condition between the anode electrode and the cathode electrode in which the Al-Cr alloy is set, and at the same time maintaining the reaction atmosphere at a predetermined gas pressure on the tool substrate surface, It is also known that a composite nitride layer of Al and Cr can be manufactured by vapor deposition.
近年の切削加工装置の高性能化はめざましく、一方で切削加工に対する省力化および省エネ化、さらに低コスト化の要求は強く、これに伴い、切削加工は一段と厳しい切削条件下で行われるようになってきている。
従来被覆工具においては、ある程度の耐チッピング性、耐欠損性、耐摩耗性の改善は図り得るものの、これを炭素鋼などの一段と厳しい切削加工に用いた場合には、チッピングが発生しやすく、あるいは、摩耗損耗が大きくなり、これを原因として、比較的短時間で使用寿命に至るのが現状である。
In recent years, the performance of cutting devices has been dramatically improved, while on the other hand, there has been a strong demand for labor saving, energy saving, and cost reduction for cutting, and as a result, cutting has been performed under more severe cutting conditions. It is coming.
In conventional coated tools, chipping resistance, fracture resistance, and wear resistance can be improved to some extent, but when this is used for more severe cutting such as carbon steel, chipping is likely to occur, or As a result, the wear and wear increase, and due to this, the service life is reached in a relatively short time.
そこで、本発明が解決しようとする技術的課題、すなわち、本発明の目的は、炭素鋼などを切削する場合においても、耐チッピング性、耐欠損性、耐摩耗性にすぐれ、長期の使用に亘ってすぐれた切削性能を発揮する被覆工具を提供することにある。 Therefore, the technical problem to be solved by the present invention, that is, the object of the present invention, is excellent in chipping resistance, chipping resistance, and wear resistance even when cutting carbon steel and the like, and is used over a long period of use. It is to provide a coated tool that exhibits excellent cutting performance.
本発明者らは、炭素鋼などの切削加工において、耐チッピング性とともに耐摩耗性にもすぐれ、長期の使用に亘ってすぐれた切削性能を発揮する被覆工具を提供すべく、硬質被覆層の結晶組織構造について鋭意研究を行った結果、以下の知見を得た。 In order to provide a coated tool that has excellent chipping resistance as well as wear resistance in cutting work such as carbon steel and that exhibits excellent cutting performance over a long period of use, the present inventors have developed a crystal of a hard coating layer. As a result of earnest research on the tissue structure, the following findings were obtained.
従来、被覆工具を作製するにあたり、硬質被覆層の形成手段としては、ＣＶＤ法、ＰＶＤ法等が一般的に採用されており、そして、例えば、ＣＶＤ法の一種であるＭＴ−ＣＶＤ法によりＴｉＮ、ＴｉＣＮ、ＴｉＣなどからなる硬質被覆層を成膜する際には、特許文献１として示したように、工具基体表面に平面研磨、刃先ホーニング処理を施し、装置内に装入し、装置内を所定温度（１０５０〜１２００Ｋ程度）に加熱した状態で、反応ガスとしてＴｉＣｌ４ガスとＮ２ガス、ＣＨ４ガスなどを導入し、同時にマイクロ波や熱フィラメントなどで反応ガスを励起させて、プラズマ放電を発生させ所定圧の反応雰囲気中で蒸着することによって硬質被覆層を成膜していた。 Conventionally, in producing a coated tool, a CVD method, a PVD method or the like is generally employed as a means for forming a hard coating layer, and, for example, TiN, a MT-CVD method which is a kind of CVD method, When depositing a hard coating layer made of TiCN, TiC, etc., as shown in Patent Document 1, the surface of the tool base is subjected to surface polishing and blade edge honing treatment, inserted into the apparatus, and the inside of the apparatus is predetermined. While heated to a temperature (about 1050 to 1200 K), TiCl 4 gas, N 2 gas, CH 4 gas and the like are introduced as reaction gases, and at the same time, the reaction gas is excited by a microwave, a hot filament, etc. A hard coating layer was formed by vapor deposition in a reaction atmosphere at a predetermined pressure.
本発明者らは、従来から汎用されているアークイオンプレーティング（以下、ＡＩＰという）法によるＴｉ化合物からなる硬質被覆層の成膜に際し、工具基体とターゲット間に磁場をかけ、硬質被覆層の組織構造に及ぼす磁場の影響を調査検討したところ、
（１）ＡＩＰ法による硬質被覆層の成膜を所定強度の磁場中で行うことによって、硬質被覆層を構成する結晶粒の粒径、形成領域およびその分布を調整することができること、
（２）そして、逃げ面上の刃先から１００μｍ離れた位置までの範囲において、硬質被覆層は、粒径０．１５μｍ以下の結晶粒と粒径１．０μｍ以下の結晶粒の占める結晶粒径長割合がそれぞれ２０〜７０％、９５％以上となるように調整すること、すなわち、逃げ面上の結晶粒の粒径分布を調整することにより、切削時に刃先の部位ごとに要求される硬度を満足させることができ、結果として工具寿命の長寿命化が可能になること、
（３）さらに、逃げ面上の刃先から１００μｍ離れた位置までの範囲において、硬質被覆層と工具基体との界面における粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合を所定の値以下にすることにより、硬質被覆層の耐剥離性が向上させることができ、工具寿命の一層の長寿命化が可能になること、
という新規な知見を得た。
The inventors of the present invention applied a magnetic field between a tool base and a target when forming a hard coating layer made of a Ti compound by a conventionally used arc ion plating (hereinafter referred to as AIP) method. After investigating the effects of magnetic fields on the tissue structure,
(1) By performing film formation of the hard coating layer by the AIP method in a magnetic field of a predetermined strength, the grain size, formation region and distribution of the crystal grains constituting the hard coating layer can be adjusted,
(2) In the range from the cutting edge on the flank to a position 100 μm away, the hard coating layer has a crystal grain size length occupied by crystal grains having a grain size of 0.15 μm or less and crystal grains having a grain size of 1.0 μm or less. By adjusting the ratio to 20 to 70% and 95% or more respectively, that is, by adjusting the grain size distribution of the crystal grains on the flank, the hardness required for each part of the cutting edge during cutting is satisfied. The tool life can be extended as a result,
(3) Further, in a range from the cutting edge on the flank to a position 100 μm away, a crystal grain length ratio occupied by crystal grains having a grain size of 0.15 μm or less at the interface between the hard coating layer and the tool base is a predetermined value. By making the following, it is possible to improve the peel resistance of the hard coating layer, it is possible to further extend the tool life,
I got the new knowledge.
本発明は、前述の知見に基づいてなされたものであって、
「（１） 炭化タングステン基超硬合金で構成された工具基体の表面に、平均層厚が２〜１０μｍの硬質被覆層を蒸着形成した表面被覆切削工具において、
（ａ）前記硬質被覆層は、ＡｌとＣｒの合量に占めるＣｒの含有割合が０．２〜０．５（但し、原子比）であるＡｌとＣｒの複合窒化物層を有し、
（ｂ）前記複合窒化物層は、逃げ面上の刃先から１００μｍ離れた位置までの範囲において、粒径０．１５μｍ以下の結晶粒と粒径１．０μｍ以下の結晶粒の占める結晶粒径長割合がそれぞれ２０〜７０％、９５％以上であり、
（ｃ）前記逃げ面上の刃先から１００μｍ離れた位置までの範囲の工具基体と複合窒化物層の界面において、粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合が２０％以下である、
ことを特徴とする表面被覆切削工具。
（２） 前記逃げ面上の刃先から１００〜２００μｍ離れた位置までの範囲の工具基体と複合窒化物層の界面において、粒径０．１５μｍ以下の結晶粒と粒径１．０μｍ以下の結晶粒の占める結晶粒径長割合がそれぞれ２０％以下、９５％以上である、
ことを特徴とする（１）に記載の表面被覆切削工具。
（３） 前記表面被覆切削工具の刃先角度をα度とし、該α度の角度範囲内の切れ刃先端部のコーナー部の硬質被覆層中に形成されている連続クラックの占有角度をβ度とした場合、クラック占有率β／αが０．３〜１．０であることを特徴とする（１）または（２）に記載の表面被覆切削工具。」
に特徴を有するものである。
The present invention has been made based on the above-mentioned findings,
“(1) In a surface-coated cutting tool in which a hard coating layer having an average layer thickness of 2 to 10 μm is vapor-deposited on the surface of a tool base composed of a tungsten carbide-based cemented carbide,
(A) The hard coating layer has a composite nitride layer of Al and Cr in which the content ratio of Cr in the total amount of Al and Cr is 0.2 to 0.5 (however, the atomic ratio);
(B) The composite nitride layer has a crystal grain size length occupied by crystal grains having a grain size of 0.15 μm or less and crystal grains having a grain size of 1.0 μm or less in a range from the cutting edge on the flank to a position away from 100 μm. The proportions are 20 to 70% and 95% or more, respectively.
(C) At the interface between the tool base and the composite nitride layer in a range of 100 μm away from the cutting edge on the flank, the crystal grain size length ratio occupied by crystal grains having a grain size of 0.15 μm or less is 20% or less. is there,
A surface-coated cutting tool characterized by that.
(2) Crystal grains having a grain size of 0.15 μm or less and crystal grains having a grain size of 1.0 μm or less at the interface between the tool base and the composite nitride layer in a range of 100 to 200 μm away from the cutting edge on the flank. The crystal grain length ratio occupied by is 20% or less and 95% or more, respectively.
The surface-coated cutting tool according to (1), wherein
(3) The cutting edge angle of the surface-coated cutting tool is α degrees, and the occupation angle of continuous cracks formed in the hard coating layer at the corner portion of the cutting edge tip within the angle range of α degrees is β degrees. The surface-coated cutting tool according to (1) or (2), wherein the crack occupancy ratio β / α is 0.3 to 1.0. "
It has the characteristics.
つぎに、本発明の被覆工具について詳細に説明する。
（ａ）硬質被覆層の組成および平均層厚：
本発明の硬質被覆層は、ＡｌとＣｒの複合窒化物層（（Ａｌ，Ｃｒ）Ｎ層）を有する。
前記（Ａｌ，Ｃｒ）Ｎ層は、Ａｌ成分が高温硬さと耐熱性を向上させ、Ｃｒ成分が高温強度を向上させ、さらにＣｒとＡｌの共存含有によって高温耐酸化性が向上することから、高温硬さ、耐熱性、高温強度及び高温耐酸化性にすぐれた硬質被覆層として既によく知られている。
本発明の（Ａｌ，Ｃｒ）Ｎ層は、Ａｌとの合量に占めるＣｒの含有割合（原子比、以下同じ）が０．２未満では、切削加工時の高温強度を確保することが困難となり、一方、Ａｌとの合量に占めるＣｒの含有割合（原子比）が０．５を越えると、相対的にＡｌの含有割合が少なくなり、高温硬さの低下、耐熱性の低下を招き、その結果、偏摩耗の発生、熱塑性変形の発生等により耐摩耗性が劣化するようになることから、Ａｌとの合量に占めるＣｒの含有割合（原子比）は、０．２〜０．５であることが必要である。
Next, the coated tool of the present invention will be described in detail.
(A) Composition and average layer thickness of the hard coating layer:
The hard coating layer of the present invention has a composite nitride layer ((Al, Cr) N layer) of Al and Cr.
In the (Al, Cr) N layer, the Al component improves high-temperature hardness and heat resistance, the Cr component improves high-temperature strength, and the high-temperature oxidation resistance is improved by coexistence of Cr and Al. It is already well known as a hard coating layer having excellent hardness, heat resistance, high temperature strength and high temperature oxidation resistance.
In the (Al, Cr) N layer of the present invention, if the Cr content ratio (atomic ratio, the same applies hereinafter) in the total amount with Al is less than 0.2, it is difficult to ensure high temperature strength during cutting. On the other hand, when the Cr content ratio (atomic ratio) in the total amount with Al exceeds 0.5, the Al content ratio is relatively reduced, resulting in a decrease in high-temperature hardness and a decrease in heat resistance. As a result, wear resistance deteriorates due to the occurrence of uneven wear, the occurrence of thermoplastic deformation, etc., so the Cr content (atomic ratio) in the total amount with Al is 0.2 to 0.5. It is necessary to be.
また、（Ａｌ，Ｃｒ）Ｎ層を有する硬質被覆層の平均層厚は、２μｍ未満では、すぐれた耐摩耗性を長期に亘って発揮することができず、工具寿命短命の原因となり、一方、その平均層厚が１０μｍを越えると、刃先部にチッピングが発生し易くなることから、その平均層厚は２〜１０μｍとすることが必要である。
なお、本発明では平均層厚の測定は、以下のような方法で行った。
まず、工具基体刃先から逃げ面側の断面を切り出し、その断面をＳＥＭで観察する。次いで、工具基体と硬質被覆層の界面から硬質被覆層表面までの距離を任意の５箇所で測定し、その平均値を平均層厚とした。
In addition, if the average thickness of the hard coating layer having an (Al, Cr) N layer is less than 2 μm, excellent wear resistance cannot be exhibited over a long period of time, causing a short tool life, When the average layer thickness exceeds 10 μm, chipping is likely to occur at the blade edge portion, so the average layer thickness needs to be 2 to 10 μm.
In the present invention, the average layer thickness was measured by the following method.
First, a section on the flank side is cut out from the tool base blade edge, and the section is observed with an SEM. Subsequently, the distance from the interface of a tool base | substrate and a hard coating layer to the hard coating layer surface was measured in arbitrary 5 places, and the average value was made into average layer thickness.
（ｂ）（Ａｌ，Ｃｒ）Ｎ層の層構造：
本発明では、逃げ面上の刃先から１００μｍ離れた位置までの範囲においては、（Ａｌ，Ｃｒ）Ｎ層は粒径０．１５μｍ以下、１μｍ以下の結晶粒の結晶粒径長割合が、それぞれ、２０〜７０％、９５％以上とする。
また、逃げ面上の刃先から１００μｍ離れた位置までの範囲における工具基体と硬質被覆層の界面においては、粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合を２０％以下とする。
(B) Layer structure of the (Al, Cr) N layer:
In the present invention, in the range from the cutting edge on the flank to a position 100 μm away, the (Al, Cr) N layer has a crystal grain length ratio of crystal grains having a grain size of 0.15 μm or less and 1 μm or less, respectively. 20 to 70%, 95% or more.
In addition, at the interface between the tool base and the hard coating layer in a range from the cutting edge on the flank to a position 100 μm away, the crystal grain length ratio occupied by crystal grains having a grain size of 0.15 μm or less is set to 20% or less.
なお、本発明でいう「刃先」とは、図３に示すように、「切れ刃先端のコーナー部の円錐形状となっている部分を除いた、直線状切れ刃の最も先端に近い部分」であると定義する。
また、ここで「粒径が０．１５μｍ以下の結晶粒が占める結晶粒径長割合」とは、複数の結晶粒の粒径を測定し、その全測定結晶粒径長の和に対する粒径０．１５μｍ以下の結晶粒径長の和の割合を示し、同様に、「粒径が１μｍ以下の結晶粒が占める結晶粒径長割合」とは、複数の結晶粒の粒径を測定し、その全測定結晶粒径長の和に対する粒径１μｍ以下の結晶粒径長の和の割合を示す。
In addition, as shown in FIG. 3, the “blade edge” in the present invention is “the portion closest to the tip of the linear cutting blade excluding the conical portion of the corner portion at the tip of the cutting blade”. Define that there is.
In addition, “the ratio of the crystal grain length occupied by crystal grains having a grain size of 0.15 μm or less” means that the grain size of a plurality of crystal grains is measured and the grain size is 0 with respect to the sum of all the measured crystal grain lengths. The ratio of the sum of crystal grain lengths of .15 μm or less is indicated, and similarly, “the ratio of crystal grain length occupied by crystal grains having a grain size of 1 μm or less” is the measurement of the grain size of a plurality of crystal grains. The ratio of the sum of crystal grain lengths with a grain size of 1 μm or less to the sum of all measured crystal grain lengths is shown.
本発明の（Ａｌ，Ｃｒ）Ｎ層の層構造について、以下に、詳細に説明する。
本発明では、逃げ面上の刃先近傍、すなわち、刃先から１００μｍ離れた位置までの範囲においては、（Ａｌ，Ｃｒ）Ｎ層は、粒径０．１５μｍ以下の結晶粒の結晶粒径長割合が２０〜７０％であり、粒径１μｍ以下の結晶粒の結晶粒径長割合が９５％以上となるように、結晶粒の粒径分布を調整する。その理由は、粒径０．１５μｍ以下の結晶粒の結晶粒径長割合が組織中の２０％未満、または、粒径１μｍ以下の結晶粒の結晶粒径長割合が９５％未満になると、硬質被覆層中の平均結晶粒径が相対的に大きくなることを意味している。硬質被覆層の内部の残留応力が小さい場合に、結晶粒毎に蓄えられる応力（すなわち、エネルギー）が小さいため、粒界が少なく、すなわち結晶粒径が大きくなる。硬質被覆層中に形成される圧縮応力の値が小さくなるため、硬質被覆層の耐摩耗性が低下する。一方、粒径０．１５μｍ以下の結晶粒の結晶粒径長割合が組織中の７０％を超えると、硬質被覆層中の平均結晶粒径が相対的に小さくなることを意味している。硬質被覆層の内部の残留応力が大きい場合に、結晶粒毎に蓄えられる応力（すなわち、エネルギー）が大きいため、それらエネルギーを解放するために粒界部を多く形成し、すなわち結晶粒径が小さくなる。硬質被覆層中に形成される圧縮応力の値が大きくなりすぎて、切削加工時にチッピングを発生しやすくなる。
そのため、逃げ面上の刃先近傍は、粒径０．１５μｍ以下の結晶粒の結晶粒径長割合を２０〜７０％、粒径１．０μｍ以下の結晶粒の結晶粒径長割合を９５％以上とすることが必要である。
The layer structure of the (Al, Cr) N layer of the present invention will be described in detail below.
In the present invention, in the vicinity of the cutting edge on the flank, that is, up to a position 100 μm away from the cutting edge, the (Al, Cr) N layer has a crystal grain length ratio of crystal grains having a grain size of 0.15 μm or less. The grain size distribution of the crystal grains is adjusted so that the crystal grain length ratio of the crystal grains with a grain size of 1 μm or less is 95% or more. The reason is that when the crystal grain length ratio of crystal grains having a grain size of 0.15 μm or less is less than 20% in the structure, or the crystal grain length ratio of crystal grains having a grain size of 1 μm or less is less than 95%, This means that the average crystal grain size in the coating layer becomes relatively large. When the residual stress inside the hard coating layer is small, the stress (that is, energy) stored for each crystal grain is small, so there are few grain boundaries, that is, the crystal grain size is large. Since the value of the compressive stress formed in the hard coating layer is reduced, the wear resistance of the hard coating layer is lowered. On the other hand, if the crystal grain length ratio of crystal grains having a grain size of 0.15 μm or less exceeds 70% in the structure, it means that the average crystal grain size in the hard coating layer becomes relatively small. When the residual stress inside the hard coating layer is large, the stress (that is, energy) stored for each crystal grain is large. Therefore, many grain boundaries are formed to release the energy, that is, the crystal grain size is small. Become. The value of the compressive stress formed in the hard coating layer becomes too large, and chipping is likely to occur during cutting.
Therefore, in the vicinity of the cutting edge on the flank, the crystal grain length ratio of crystal grains having a grain size of 0.15 μm or less is 20 to 70%, and the crystal grain length ratio of crystal grains having a grain size of 1.0 μm or less is 95% or more. Is necessary.
また、逃げ面上の刃先近傍、すなわち、刃先から１００μｍ離れた位置までの範囲の工具基体と硬質被覆層の界面においては、粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合を２０％以下とすることが必要である。
ここで、工具基体と硬質被覆層の界面における硬質被覆層の結晶粒は、硬質被覆層内における工具基体と硬質被覆層の界面から厚さ０．５μｍの領域にて形成されている結晶粒を意味する。
本発明で、逃げ面上の刃先近傍の工具基体と硬質被覆層の界面における０．１５μｍ以下の結晶粒の占める結晶粒径長割合を前述のとおり定めた理由は、刃先に被覆された硬質被覆層と工具基体との十分な耐剥離性を確保すると同時に、チッピングの発生を抑制するためでる。すなわち、粒径０．１５μｍ以下の結晶粒の結晶粒径長割合が２０％を超える場合には、硬質被覆層中の圧縮残留応力が大きくなり、炭素鋼等の切削加工においてチッピングを発生し易くなるため好ましくない。
さらに、逃げ面上の刃先からの距離が１００〜２００μｍ離れた位置での工具基体と硬質被覆層においては、粒径０．１５μｍ以下の結晶粒の結晶粒径長割合が２０％以下、かつ、粒径１μｍ以下の結晶粒の結晶粒径長割合が９５％以上とすることが必要である。その理由は、粒径０．１５μｍ以下の結晶粒の結晶粒径長割合が組織中の２０％を超える場合には、切削加工時に刃先にてクラックが発生した場合、硬質被覆層中に結晶粒界が占める割合が多く、亀裂が結晶粒界に沿って進展するため、チッピングが生じやすくなる。また、粒径１μｍ以下の結晶粒の結晶粒径長割合が９５％未満である場合には、硬質被覆層中の残留応力値が小さいため、硬質被覆層の耐摩耗性が低下しやすくなる。
Further, in the vicinity of the cutting edge on the flank, that is, at the interface between the tool base and the hard coating layer in a range up to a position 100 μm away from the cutting edge, the crystal grain size length ratio occupied by crystal grains having a grain size of 0.15 μm or less is 20 % Or less is required.
Here, the crystal grains of the hard coating layer at the interface between the tool base and the hard coating layer are the crystal grains formed in the region of 0.5 μm thickness from the interface between the tool base and the hard coating layer in the hard coating layer. means.
In the present invention, the reason why the crystal grain length ratio of the crystal grains of 0.15 μm or less at the interface between the tool base near the cutting edge on the flank and the hard coating layer is determined as described above is that the hard coating coated on the cutting edge This is because sufficient peeling resistance between the layer and the tool substrate is ensured, and at the same time, the occurrence of chipping is suppressed. That is, when the crystal grain size length ratio of crystal grains having a grain size of 0.15 μm or less exceeds 20%, the compressive residual stress in the hard coating layer increases, and chipping is likely to occur in the cutting of carbon steel or the like. Therefore, it is not preferable.
Further, in the tool base and the hard coating layer at a position 100 to 200 μm away from the cutting edge on the flank, the crystal grain length ratio of crystal grains having a grain size of 0.15 μm or less is 20% or less, and It is necessary that the crystal grain length ratio of crystal grains having a grain size of 1 μm or less is 95% or more. The reason is that when the crystal grain length ratio of crystal grains having a grain size of 0.15 μm or less exceeds 20% in the structure, if cracks occur at the cutting edge during cutting, the crystal grains in the hard coating layer Since the boundary occupies a large proportion and cracks propagate along the grain boundaries, chipping is likely to occur. Further, when the crystal grain length ratio of the crystal grains having a grain size of 1 μm or less is less than 95%, the residual stress value in the hard coating layer is small, so that the wear resistance of the hard coating layer is likely to be lowered.
なお、本発明では、逃げ面上の硬質被覆層の結晶粒の粒径の測定は、以下のように行った。
工具基体刃先から逃げ面側の断面を切り出し、その断面をＳＥＭで観察する。「硬質被覆層表面から深さ０．５μｍの領域（水平断面）」に形成されている結晶粒、「硬質被覆層内における工具基体と硬質被覆層の界面から厚さ０．５μｍの領域（水平断面）」に形成されている結晶粒および「硬質被覆層表面と工具基体表面の中間の領域（水平断面）」に存在している結晶粒について、工具基体表面と平行に直線を引き、結晶粒界間の距離を粒径と定義する。
なお、工具基体表面と平行に直線を引く位置は、各結晶粒において最長の粒径となる位置とする。それぞれの領域において、図３に模式的に示したように、「逃げ面上の刃先から２５μｍ離れた位置」および「逃げ面上で刃先から７５μｍ離れた位置」および「刃先から１２５μｍ離れた位置」および「逃げ面上で刃先から１７５μｍ離れた位置」の４箇所に対して、それぞれ３箇所、全１２箇所において幅１０μｍの範囲内に存在する結晶粒の粒径を測定した。
In the present invention, the crystal grain size of the hard coating layer on the flank face was measured as follows.
A section on the flank side is cut out from the tool base blade edge, and the section is observed with an SEM. Crystal grains formed in “region of 0.5 μm depth from the surface of the hard coating layer (horizontal section)”, “region of 0.5 μm thickness from the interface between the tool substrate and the hard coating layer in the hard coating layer (horizontal section) For the crystal grains formed in the “cross section)” and the crystal grains existing in the “intermediate region between the hard coating layer surface and the tool base surface (horizontal cross section)”, a straight line is drawn parallel to the tool base surface, and the crystal grains The distance between the boundaries is defined as the particle size.
The position where a straight line is drawn parallel to the surface of the tool base is the position where the longest grain size is obtained in each crystal grain. In each region, as schematically shown in FIG. 3, “a position 25 μm away from the cutting edge on the flank” and “a position 75 μm away from the cutting edge on the flank” and “a position 125 μm away from the cutting edge”. And the grain size of the crystal grains existing in the range of 10 μm in width at 3 locations and 12 locations in total at 4 locations “positions 175 μm away from the cutting edge on the flank” was measured.
幅１０μｍの範囲内に存在する粒径を測定するにあたり、各測定箇所を中心に刃先側５μｍ、刃先と逆側５μｍの測定データを用いた。 In measuring the particle diameter existing within a range of 10 μm in width, measurement data of 5 μm on the blade edge side and 5 μm on the opposite side to the blade edge were used around each measurement point.
また、逃げ面上の刃先から１００μｍ離れた位置までの範囲での「粒径が０．１５μｍ以下の結晶粒が占める結晶粒径長割合」および「粒径が１．０μｍ以下の結晶粒が占める結晶粒径長割合」の測定方法は前記粒径を測定した、逃げ面上の刃先から２５μｍ離れた位置および逃げ面上の刃先から７５μｍ離れた位置にて、界面２箇所、表面２箇所および中間領域２箇所にて測定した結晶粒の粒径の全測定データを用いる。測定した全結晶粒の粒径の和に対する、粒径が０．１５μｍ以下の結晶粒の粒径の和および粒径が１．０μｍ以下の結晶粒の粒径の和をそれぞれの結晶粒が占める結晶粒径長割合と定義した。 Further, “the ratio of the crystal grain length occupied by crystal grains having a grain size of 0.15 μm or less” and “crystal grains having a grain size of 1.0 μm or less” in the range from the cutting edge on the flank to a position 100 μm away The crystal grain length ratio is measured by measuring the grain size, at a position 25 μm away from the cutting edge on the flank face and a position 75 μm away from the cutting edge on the flank face, two interfaces, two surfaces, and an intermediate All measured data of the grain size of the crystal grains measured at two locations in the region is used. Each crystal grain occupies the sum of the grain diameters of the crystal grains having a grain size of 0.15 μm or less and the sum of the grain diameters of the crystal grains having a grain size of 1.0 μm or less with respect to the sum of the measured grain sizes of all the crystal grains. It was defined as the crystal grain length ratio.
また、逃げ面上の刃先から１００μｍ離れた位置までの範囲での工具基体と硬質被覆層の界面において、「粒径が０．１５μｍ以下の結晶粒が占める結晶粒径長割合」の測定方法は、前記粒径を測定した、逃げ面上の刃先から２５μｍ離れた位置および逃げ面上の刃先から７５μｍ離れた位置にて界面２箇所の全測定データを用いる。測定した全結晶粒径の和に対する、粒径が０．１５μｍ以下の結晶粒の粒径の和を逃げ面上の刃先から１００μｍ離れた位置までの範囲での工具基体と硬質被覆層の界面における「粒径０．１５μｍ以下の結晶粒が占める結晶粒径長割合」と定義した。
また、逃げ面上の刃先から１００〜２００μｍ離れた位置の範囲での「粒径が０．１５μｍ以下の結晶粒が占める結晶粒径長割合」および「粒径が１．０μｍ以下の結晶粒が占める結晶粒径長割合」の測定方法は前記粒径を測定した、逃げ面上の刃先から１２５μｍ離れた位置および逃げ面上の刃先から１７５μｍ離れた位置にて、界面２箇所、表面２箇所および中間領域２箇所にて測定した結晶粒の粒径の全測定データを用いる。測定した全結晶粒の粒径の和に対する、粒径が０．１５μｍ以下の結晶粒の粒径の和および粒径が１．０μｍ以下の結晶粒の粒径の和をそれぞれの結晶粒が占める結晶粒径長割合と定義した。
In addition, the measurement method of “the crystal grain length ratio occupied by crystal grains having a grain size of 0.15 μm or less” at the interface between the tool base and the hard coating layer in a range from the cutting edge on the flank to a position 100 μm away is: The measurement data of the two interfaces are used at a position 25 μm away from the cutting edge on the flank and 75 μm away from the cutting edge on the flank. At the interface between the tool base and the hard coating layer in the range of the sum of the grain sizes of the grains having a grain size of 0.15 μm or less to the position of 100 μm away from the cutting edge on the flank with respect to the sum of all the measured grain sizes It was defined as “the ratio of the crystal grain size length occupied by crystal grains having a grain size of 0.15 μm or less”.
Further, in the range of the position 100 to 200 μm away from the cutting edge on the flank, “the ratio of the crystal grain length occupied by the crystal grains having a grain size of 0.15 μm or less” and “the crystal grains having a grain size of 1.0 μm or less The measurement method of the “occupying crystal grain length ratio” is the measurement of the grain size, at a position 125 μm away from the cutting edge on the flank and at a position 175 μm away from the cutting edge on the flank, two interfaces, two surfaces, and All measured data of the grain size of the crystal grains measured at two locations in the intermediate region is used. Each crystal grain occupies the sum of the grain diameters of the crystal grains having a grain size of 0.15 μm or less and the sum of the grain diameters of the crystal grains having a grain size of 1.0 μm or less with respect to the sum of the measured grain sizes of all the crystal grains. It was defined as the crystal grain length ratio.
本発明では、さらに、図４に示すように、被覆工具の刃先角度をα度とし該α度の角度範囲内の切れ刃先端のコーナー部の硬質被覆層中に形成されている連続クラックの占有角度をβ度とした場合に、クラック占有率β／αを０．３〜１．０とすることが好ましい。さらには、クラック占有率β／αを０．３〜０．９とすることがより好ましい。
その理由は、次のとおりである。
Further, in the present invention, as shown in FIG. 4, the edge angle of the coated tool is α degrees, and the occupation of the continuous cracks formed in the hard coating layer at the corner portion of the cutting edge within the angle range of the α degrees. When the angle is β degrees, the crack occupancy β / α is preferably 0.3 to 1.0. Furthermore, it is more preferable that the crack occupation ratio β / α is 0.3 to 0.9.
The reason is as follows.
工具基体表面に、ＡＩＰ装置を用いて硬質被覆層を形成する場合、層中には圧縮残留応力が蓄積され、特に、結晶粒径の大きな層にあっては、結晶粒界に圧縮残留応力が集中し、亀裂の起点となりやすい。
しかし、本発明によれば、切れ刃先端のコーナー部の硬質被覆層中に予めクラックが形成されていることから、残留応力の集中が低減される。その結果、特に、切削開始初期に生じがちな結晶粒界に圧縮残留応力が集中することが回避され、チッピング発生等による切削性能の低下を抑制できる。
ただし、β／αが０．３未満である場合には、期待した圧縮残留応力の集中抑制効果が得られないため、β／αは０．３以上と定めた。一方、圧縮残留応力の集中抑制効果の観点からは、β／αの値に上限を設ける必要はない（即ち、β／αは、０．３〜１．０）が、β／αの値が１．０に近づくほど、硬質被覆層と工具基体界面での界面剥離が発生しやすくなる。そのため、切削工具として必要な耐剥離性を確保する点で、β／αの値は０．３〜０．９とすることがより好ましい。
When a hard coating layer is formed on the surface of a tool substrate using an AIP apparatus, compressive residual stress is accumulated in the layer. In particular, in a layer having a large crystal grain size, compressive residual stress is present at the crystal grain boundary. It tends to concentrate and become the starting point of cracks.
However, according to the present invention, since cracks are formed in advance in the hard coating layer at the corner portion at the tip of the cutting edge, the concentration of residual stress is reduced. As a result, it is possible to avoid compressive residual stress from concentrating on the grain boundaries that tend to occur particularly at the beginning of cutting, and to suppress a reduction in cutting performance due to chipping and the like.
However, when β / α is less than 0.3, the expected effect of suppressing the concentration of compressive residual stress cannot be obtained, so β / α is set to 0.3 or more. On the other hand, from the viewpoint of the effect of suppressing the concentration of compressive residual stress, there is no need to provide an upper limit to the value of β / α (that is, β / α is 0.3 to 1.0), but the value of β / α is As the value approaches 1.0, interfacial peeling at the interface between the hard coating layer and the tool substrate tends to occur. Therefore, it is more preferable that the value of β / α is 0.3 to 0.9 in terms of securing the peel resistance necessary as a cutting tool.
ここで、クラック占有率とは、本発明で、以下のように定義する。
図４に示すように、逃げ面上の刃先Ａを通る逃げ面の垂線と、すくい面上の刃先Ｂを通るすくい面の垂線との交点を中心Ｏとした時、Ａ−Ｏ−Ｂのなす角度を刃先角度α（度）という。
Here, the crack occupation ratio is defined as follows in the present invention.
As shown in FIG. 4, when the intersection of the perpendicular of the flank passing through the cutting edge A on the flank and the perpendicular of the rake face passing through the cutting edge B on the rake face is the center O, the line A-O-B is formed. The angle is called the blade edge angle α (degrees).
また、切れ刃先端のコーナー部の硬質被覆層中に形成されている連続クラックについては、前記中心Ｏから、連続する一つのクラックの端部Ｃ，Ｄに接する線を引いた時、Ｃ−Ｏ−Ｄのなす角度を連続クラックの占有角度β（度）とする。ただし、Ｏ―ＡまたはＯ−Ｂの延長線上をクラックが横切る場合は、延長線とクラックの交点をそれぞれＣ、Ｄとする。切れ刃先端のコーナー部の硬質被覆層中に複数のクラックが存在する場合、最大の占有角度を示す連続クラックを用いるものとする。
そして、（連続クラックの占有角度β）／（刃先角度α）の値を、クラック占有率であると定義する。図４（ｂ）に、刃先角度α内における最大の角度βを示すクラックをクラックの端部Ｃ、Ｄとして示す。
なお、本発明被覆工具の硬質被覆層は、（Ａｌ，Ｃｒ）Ｎ層からなり、逃げ面上において所定の粒径分布を有する組織とする。そして、逃げ面上の刃先から１００μｍ離れた位置までの界面においては、粒径が０．１５μｍ以下の結晶粒が占める結晶粒径長割合を２０〜７０％、１．０μｍ以下の結晶粒が占める結晶粒径長割合を９５％以上と定めることにより、クラック占有率β／αを再現性よく、０．３〜１．０とすることが出来る。
この粒径分布とクラック占有率の関係も本発明に関する研究過程で知得した新規な知見である。
Further, for continuous cracks formed in the hard coating layer at the corner portion at the tip of the cutting edge, when a line in contact with the end portions C and D of one continuous crack is drawn from the center O, C—O The angle formed by -D is defined as the occupied angle β (degrees) of the continuous crack. However, when a crack crosses the extension line of OA or OB, the intersections of the extension line and the crack are C and D, respectively. When there are a plurality of cracks in the hard coating layer at the corner portion at the tip of the cutting edge, a continuous crack showing the maximum occupation angle is used.
The value of (occupation angle β of continuous crack) / (blade edge angle α) is defined as the crack occupancy rate. In FIG. 4B, cracks indicating the maximum angle β within the blade edge angle α are shown as crack ends C and D. FIG.
The hard coating layer of the coated tool of the present invention is made of an (Al, Cr) N layer and has a structure having a predetermined particle size distribution on the flank. And, at the interface from the cutting edge on the flank face to a position 100 μm away, the crystal grain size ratio of 20 to 70% and the crystal grain of 1.0 μm or less occupy the crystal grain length ratio occupied by the crystal grain of 0.15 μm or less. By determining the crystal grain length ratio to be 95% or more, the crack occupancy ratio β / α can be set to 0.3 to 1.0 with good reproducibility.
The relationship between the particle size distribution and the crack occupancy rate is also a new finding obtained during the research process relating to the present invention.
（ｃ）硬質被覆層の蒸着形成方法
本発明の硬質被覆層は、図２（ａ）、（ｂ）に示すようなＡＩＰ装置を用い、工具基体の温度を３７０〜４５０℃に維持しつつ、工具基体をＡＩＰ装置内で自公転させ、ターゲット表面中心とターゲットに最近接した工具基体間に所定の磁場（積算磁力が４５〜１００ｍＴ×ｍｍ）を印加しながら蒸着することによって、形成することができる。
(C) Method for forming vapor deposition of hard coating layer The hard coating layer of the present invention uses an AIP apparatus as shown in FIGS. 2 (a) and 2 (b), while maintaining the temperature of the tool base at 370 to 450 ° C. It can be formed by revolving the tool base in the AIP apparatus and depositing it while applying a predetermined magnetic field (integrated magnetic force of 45 to 100 mT × mm) between the center of the target surface and the tool base closest to the target. it can.
例えば、ＡＩＰ装置の一方には基体洗浄用のＴｉ電極からなるカソード電極、他方には７０ａｔ％Ａｌ−３０ａｔ％Ｃｒ合金からなるターゲット（以下、Ａｌ−Ｃｒ合金ターゲット）（カソード電極）を設ける。
まず、炭化タングステン（ＷＣ）基超硬合金からなる工具基体をアセトン中で超音波洗浄・乾燥し、ＡＩＰ装置内の回転テーブル上に装着し、真空中で基体洗浄用のＴｉ電極とアノード電極との間に１００Ａのアーク放電を発生させて、工具基体に−１０００Ｖのバイアス電圧を印加しつつ工具基体表面をボンバード洗浄する。
ついで、Ａｌ−Ｃｒ合金ターゲットの表面中心からターゲットに最近接した工具基体までの積算磁力が４５〜１００ｍＴ×ｍｍなる磁場を印加する。
そして、装置内に反応ガスとして窒素ガスを導入し９．３Ｐａの雰囲気圧力とし、工具基体の温度を３７０〜４５０℃に維持し、工具基体に−５０Ｖのバイアス電圧を印加しつつ、Ａｌ−Ｃｒ合金ターゲット（カソード電極）とアノード電極との間に１００Ａのアーク放電を発生させ、工具基体がターゲットに最接近した際に、逃げ面の一部または全部とターゲット面が水平となるように工具基体を支持して自公転させつつ蒸着することによって、本発明の層構造を有する（Ａｌ，Ｃｒ）Ｎ層からなる硬質被覆層を蒸着形成することができる。
For example, one of the AIP apparatuses is provided with a cathode electrode made of a substrate cleaning Ti electrode, and the other with a target made of a 70 at% Al-30 at% Cr alloy (hereinafter referred to as an Al-Cr alloy target) (cathode electrode).
First, a tool base made of tungsten carbide (WC) based cemented carbide is ultrasonically cleaned and dried in acetone, mounted on a rotary table in an AIP apparatus, and a Ti electrode and an anode electrode for cleaning the base in vacuum During this, an arc discharge of 100 A is generated, and the tool base surface is bombarded while applying a bias voltage of -1000 V to the tool base.
Next, a magnetic field having an integrated magnetic force of 45 to 100 mT × mm from the center of the surface of the Al—Cr alloy target to the tool base closest to the target is applied.
Then, nitrogen gas is introduced into the apparatus as a reaction gas to set the atmospheric pressure to 9.3 Pa, the temperature of the tool base is maintained at 370 to 450 ° C., and a bias voltage of −50 V is applied to the tool base while Al—Cr is applied. 100A arc discharge is generated between the alloy target (cathode electrode) and the anode electrode, and when the tool base is closest to the target, the tool base is such that part or all of the flank and the target face are horizontal. By vapor deposition while supporting and revolving, a hard coating layer composed of an (Al, Cr) N layer having the layer structure of the present invention can be formed by vapor deposition.
なお、前記Ａｌ−Ｃｒ合金ターゲットと工具基体間での磁場の印加は、例えば、カソード周辺に磁場発生源である電磁コイルまたは永久磁石を設置する、あるいは、ＡＩＰ装置のチャンバーの内部、中心部に永久磁石を配置する等、任意の手段で磁場を形成することができる。
ここで本発明における積算磁力は、以下の算出方法により算出する。
磁束計にて、Ａｌ−Ｃｒ合金ターゲット中心から工具基体の位置までの直線上を１０ｍｍ間隔で磁束密度を測定する。磁束密度は単位ｍＴ（ミリテスラ）で表し、ターゲット表面から工具基体の位置までの距離は単位ｍｍ（ミリメートル）で表す。さらに、ターゲット表面から工具基体の位置までの距離を横軸とし、磁束密度を縦軸のグラフで表現した場合、面積に相当する値を積算磁力（ｍＴ×ｍｍ）と定義する。
ここで工具基体の位置は、Ａｌ−Ｃｒ合金ターゲットに最近接する位置とする。なお、磁束密度の測定は磁場を形成している状態であれば、放電中でなくても良く、例えば大気圧下にて放電させていない状態で測定しても良い。
また、本発明の必須構成要件の定義に特に関係するわけではないが、本発明において結晶粒のアスペクト比は１以上６以下である。ここでアスペクト比は、結晶粒の水平断面で最も長い直径（長辺）とそれに垂直な直径（短辺）の長さの比を、長辺を分子、短辺を分母として算出するものとする。
The magnetic field is applied between the Al—Cr alloy target and the tool base by, for example, installing an electromagnetic coil or permanent magnet as a magnetic field generation source around the cathode, or in the center of the chamber of the AIP apparatus. The magnetic field can be formed by any means such as disposing a permanent magnet.
Here, the integrated magnetic force in the present invention is calculated by the following calculation method.
With a magnetometer, the magnetic flux density is measured at intervals of 10 mm on a straight line from the center of the Al—Cr alloy target to the position of the tool base. The magnetic flux density is expressed in units of mT (millitesla), and the distance from the target surface to the position of the tool base is expressed in units of mm (millimeters). Furthermore, when the distance from the target surface to the position of the tool base is the horizontal axis and the magnetic flux density is represented by a graph of the vertical axis, a value corresponding to the area is defined as an integrated magnetic force (mT × mm).
Here, the position of the tool base is the position closest to the Al—Cr alloy target. Note that the magnetic flux density may be measured in a state where a magnetic field is formed, not in a discharge, for example, in a state where the magnetic field is not discharged under atmospheric pressure.
Further, although not particularly related to the definition of the essential constituent elements of the present invention, the aspect ratio of the crystal grains in the present invention is 1 or more and 6 or less. Here, the aspect ratio is calculated by calculating the ratio of the longest diameter (long side) to the perpendicular diameter (short side) in the horizontal section of the crystal grain, with the long side as the numerator and the short side as the denominator. .
本発明の被覆工具は、（Ａｌ，Ｃｒ）Ｎ層からなる硬質被覆層を備え、しかも、硬質被覆層がＡｌとＣｒの合量に占めるＣｒの含有割合が所定の値を有するＡｌとＣｒの複合窒化物層を有し、複合窒化物層が、逃げ面上の刃先から１００μｍ離れた位置までの範囲において、粒径０．１５μｍ以下の結晶粒と粒径１．０μｍ以下の結晶粒の占める結晶粒径長割合がそれぞれ所定の値である粒径分布を有し、逃げ面上の刃先から１００μｍ離れた位置までの範囲の工具基体と複合窒化物層の界面において、粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合が所定値以下であるという、本発明に特有な構成を有していることによって、炭素鋼等の切削加工において、すぐれた耐チッピング性、耐摩耗性を発揮し、長期の使用に亘ってすぐれた切削性能を発揮するものであり、その効果は絶大である。 The coated tool of the present invention includes a hard coating layer composed of an (Al, Cr) N layer, and the content ratio of Cr occupying the total amount of Al and Cr in the hard coating layer has a predetermined value. It has a composite nitride layer, and the composite nitride layer is occupied by crystal grains having a grain size of 0.15 μm or less and crystal grains having a grain size of 1.0 μm or less in a range from the cutting edge on the flank to a position 100 μm away. The grain size distribution has a grain size distribution in which the crystal grain length ratio is a predetermined value, and the grain size is 0.15 μm or less at the interface between the tool base and the composite nitride layer in a range of 100 μm away from the cutting edge on the flank. By having a structure unique to the present invention in which the ratio of the crystal grain length occupied by the crystal grains is less than or equal to a predetermined value, excellent chipping resistance and wear resistance can be obtained in cutting of carbon steel and the like. Demonstrates excellent cutting over long-term use It shows cutting performance and its effect is enormous.
つぎに、本発明の被覆工具を実施例により具体的に説明する。 Next, the coated tool of the present invention will be specifically described with reference to examples.
原料粉末として、平均粒径：５．５μｍを有する中粗粒ＷＣ粉末、同０．８μｍの微粒ＷＣ粉末、同１．３μｍのＴａＣ粉末、同１．２μｍのＮｂＣ粉末、同１．２μｍのＺｒＣ粉末、同２．３μｍのＣｒ３Ｃ２粉末、同１．５μｍのＶＣ粉末、同１．０μｍの（Ｔｉ，Ｗ）Ｃ［質量比で、ＴｉＣ／ＷＣ＝５０／５０］粉末、および同１．８μｍのＣｏ粉末を用意し、これら原料粉末をそれぞれ表１に示される配合組成に配合し、さらにワックスを加えてアセトン中で２４時間ボールミル混合し、減圧乾燥した後、１００ＭＰａの圧力で所定形状の各種の圧粉体に押出しプレス成形し、これらの圧粉体を、６Ｐａの真空雰囲気中、７℃／分の昇温速度で１３７０〜１４７０℃の範囲内の所定の温度に昇温し、この温度に１時間保持後、炉冷の条件で焼結して、直径が１０ｍｍの工具基体形成用丸棒焼結体を形成し、さらに前記丸棒焼結体から、研削加工にて、切刃部の直径×長さが６ｍｍ×１３ｍｍの寸法で、ねじれ角３０度の２枚刃ボール形状をもったＷＣ基超硬合金製の工具基体（エンドミル）１〜３および切刃部の直径×長さが１０ｍｍ×２２ｍｍの寸法で２枚刃スクエア形状をもったＷＣ基超硬合金製の工具基体（エンドミル）４〜５をそれぞれ製造した。 As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, ZrC of 1.2 μm Powder, 2.3 μm Cr 3 C 2 powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C [by mass ratio, TiC / WC = 50/50] powder, and 1 .8 μm Co powder was prepared, each of these raw material powders was blended in the blending composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and then pressed into a predetermined shape at a pressure of 100 MPa. Extruded and pressed into various types of green compacts, and these green compacts were heated to a predetermined temperature in the range of 1370 to 1470 ° C. at a temperature increase rate of 7 ° C./min in a 6 Pa vacuum atmosphere. Conditions for furnace cooling after holding at this temperature for 1 hour Sintered to form a round tool sintered body for forming a tool base having a diameter of 10 mm, and further, from the round bar sintered body, the diameter x length of the cutting edge portion is 6 mm x 13 mm by grinding. The WC-base cemented carbide tool base (end mill) 1 to 3 having a two-blade ball shape with a twist angle of 30 degrees, and a two-blade square with a diameter × length of 10 mm × 22 mm of the cutting edge portion. Tool bases (end mills) 4 to 5 made of a WC-base cemented carbide having a shape were produced.
（ａ）前記工具基体１〜５のそれぞれを、アセトン中で超音波洗浄し、乾燥した状態で、図２に示すＡＩＰ装置の回転テーブル上の中心軸から半径方向に所定距離離れた位置に外周部にそって装着し、ＡＩＰ装置の一方にボンバード洗浄用のＴｉカソード電極を、他方側に７０ａｔ％Ａｌ−３０ａｔ％Ｃｒ合金（以下、Ａｌ−Ｃｒ合金）からなるターゲット（カソード電極）を配置する。
（ｂ）まず、装置内を排気して真空に保持しながら、ヒータで工具基体を５００℃に加熱した後、前記回転テーブル上で自転しながら回転する工具基体に−１０００Ｖの直流バイアス電圧を印加し、かつ、Ｔｉカソード電極とアノード電極との間に１００Ａの電流を流してアーク放電を発生させることによって、工具基体表面をボンバード洗浄する。
（ｃ）ついで、前記Ａｌ−Ｃｒ合金ターゲットの表面中心から工具基体までの積算磁力が４５〜１００ｍＴ×ｍｍの範囲内となるように種々の磁場を印加する。
ここで積算磁力の算出方法を以下に記述する。磁束計にて、Ａｌ−Ｃｒ合金ターゲット中心から工具基体の位置までの直線上を１０ｍｍ間隔で磁束密度を測定する。磁束密度は単位ｍＴ（ミリテスラ）で表し、ターゲット表面から工具基体の位置までの距離は単位ｍｍ（ミリメートル）で表す。さらに、ターゲット表面から工具基体の位置までの距離を横軸とし、磁束密度を縦軸のグラフで表現した場合、面積に相当する値を積算磁力（ｍＴ×ｍｍ）と定義する。ここで工具基体の位置は、Ａｌ−Ｃｒ合金ターゲットに最近接する位置とする。なお、磁束密度の測定は、磁場を形成している状態で大気圧下にて事前に放電させていない状態で測定した。
（ｄ）ついで、装置内に反応ガスとして窒素ガスを導入して９．３Ｐａの反応雰囲気とすると共に、前記回転テーブル上で自転しながら回転する工具基体の温度を３７０〜４５０℃の範囲内に維持するとともに−５０Ｖの直流バイアス電圧を印加し、かつ前記Ａｌ−Ｃｒ合金ターゲットとアノード電極との間に１００Ａの電流を流してアーク放電を発生させ、もって前記工具基体の表面に、表２に示される組成および目標平均層厚の（Ａｌ，Ｃｒ）Ｎ層からなる硬質被覆層を蒸着形成することにより、本発明被覆工具としての表面被覆エンドミル１〜５（以下、本発明１〜５という）をそれぞれ製造した。
なお、図２に示すＡＩＰ装置では、工具基体がＡｌ−Ｃｒ合金ターゲットに最接近する際に、逃げ面の一部または全部とＡｌ−Ｃｒ合金ターゲット面が水平となるように装着支持されている。
(A) Each of the tool bases 1 to 5 is ultrasonically cleaned in acetone and dried, and the outer periphery is positioned at a predetermined distance in the radial direction from the central axis on the rotary table of the AIP apparatus shown in FIG. The Ti cathode electrode for bombard cleaning is disposed on one side of the AIP apparatus, and the target (cathode electrode) made of 70 at% Al-30 at% Cr alloy (hereinafter referred to as Al—Cr alloy) is disposed on the other side. .
(B) First, the tool base is heated to 500 ° C. with a heater while the inside of the apparatus is evacuated and kept in vacuum, and then a DC bias voltage of −1000 V is applied to the tool base that rotates while rotating on the rotary table. In addition, the surface of the tool base is bombarded by passing an electric current of 100 A between the Ti cathode electrode and the anode electrode to generate arc discharge.
(C) Next, various magnetic fields are applied so that the integrated magnetic force from the center of the surface of the Al—Cr alloy target to the tool base is in the range of 45 to 100 mT × mm.
Here, a method of calculating the integrated magnetic force will be described below. With a magnetometer, the magnetic flux density is measured at intervals of 10 mm on a straight line from the center of the Al—Cr alloy target to the position of the tool base. The magnetic flux density is expressed in units of mT (millitesla), and the distance from the target surface to the position of the tool base is expressed in units of mm (millimeters). Furthermore, when the distance from the target surface to the position of the tool base is the horizontal axis and the magnetic flux density is represented by a graph of the vertical axis, a value corresponding to the area is defined as an integrated magnetic force (mT × mm). Here, the position of the tool base is the position closest to the Al—Cr alloy target. The magnetic flux density was measured in a state in which a magnetic field was formed and not discharged in advance under atmospheric pressure.
(D) Next, nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 9.3 Pa, and the temperature of the tool base rotating while rotating on the rotary table is within a range of 370 to 450 ° C. And a DC bias voltage of −50 V is applied, and a current of 100 A is passed between the Al—Cr alloy target and the anode electrode to generate an arc discharge. Surface coating end mills 1 to 5 (hereinafter referred to as the present invention 1 to 5) as the present invention coated tools by vapor-depositing and forming a hard coating layer composed of an (Al, Cr) N layer having the composition and target average layer thickness shown. Were manufactured respectively.
In the AIP apparatus shown in FIG. 2, when the tool base is closest to the Al—Cr alloy target, it is mounted and supported so that a part or all of the flank and the Al—Cr alloy target surface are horizontal. .
比較例１：
比較の目的で、実施例１における（ｃ）の条件を変更し（即ち、Ａｌ−Ｃｒ合金ターゲットの表面中心から工具基体までの積算磁力を４５〜１００ｍＴ×ｍｍの範囲外）、また、（ｄ）の条件を変更し（即ち、工具基体が３７０℃未満、あるいは４５０℃を超える温度に維持し）て、その他は実施例１と同一の条件で、比較例被覆工具としての表面被覆エンドミル１〜５（以下、比較例１〜５という）をそれぞれ製造した。
さらに、Ａｌ−Ｃｒ合金ターゲットの組成を変えることによって、実施例１から被覆層中のＡｌとＣｒの合量に占めるＣｒの含有割合が０．２〜０．５（但し、原子比）の範囲外、または、蒸着時間を変えることによって硬質被覆層の平均層厚が２〜１０μｍの範囲外の表面被覆エンドミル６〜１０（以下、比較例６〜１０という）をそれぞれ製造した。
Comparative Example 1:
For the purpose of comparison, the condition of (c) in Example 1 was changed (that is, the integrated magnetic force from the center of the surface of the Al—Cr alloy target to the tool substrate was outside the range of 45 to 100 mT × mm), and (d The surface-coated end mills 1 to 1 as the comparative coated tools were used under the same conditions as in Example 1 except that the tool substrate was maintained at a temperature lower than 370 ° C. or higher than 450 ° C. 5 (hereinafter referred to as Comparative Examples 1 to 5) were produced.
Further, by changing the composition of the Al—Cr alloy target, the Cr content in the total amount of Al and Cr in the coating layer from Example 1 is in the range of 0.2 to 0.5 (however, the atomic ratio). Surface-coated end mills 6 to 10 (hereinafter referred to as Comparative Examples 6 to 10) having an average thickness of the hard coating layer outside the range of 2 to 10 μm were produced by changing the deposition time or the deposition time.
前述のようにして作製した本発明１〜５について、逃げ面上の刃先から１００μｍ離れた位置までの範囲において、縦断面の硬質被覆層の平均層厚、粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合、粒径１．０μｍ以下の結晶粒の占める結晶粒径長割合を算出した。その結果、それぞれ２０〜７０％、９５％以上であることを確認した。
また、刃先から１００μｍ離れた位置までの範囲における工具基体と硬質被覆層の界面における粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合を測定したところ、２０％以下であることも確認した。
About this invention 1-5 produced as mentioned above, in the range from the blade edge on the flank to the position 100 μm away, the average layer thickness of the hard coating layer in the longitudinal section, the crystal grain size of 0.15 μm or less The crystal grain length ratio, and the crystal grain length ratio occupied by crystal grains having a grain size of 1.0 μm or less were calculated. As a result, it was confirmed that they were 20 to 70% and 95% or more, respectively.
Further, when the ratio of the crystal grain size length occupied by the crystal grains having a grain size of 0.15 μm or less at the interface between the tool base and the hard coating layer in the range up to 100 μm away from the blade edge was measured, it was confirmed that it was 20% or less. did.
一方、比較例１〜１０について、本発明と同様な観察、測定を行ったところ、被覆層の平均層厚が２〜１０μｍの範囲外の表面被覆エンドミル（比較例９，１０）以外では、前述の結晶粒径長割合が本発明で規定した範囲外、あるいは、工具基体と硬質被覆層の界面における粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合を測定したところ、２０％を超えていた。
表２、表３に、前述の測定・算出したそれぞれの値を示す。
On the other hand, when Comparative Examples 1 to 10 were observed and measured in the same manner as in the present invention, except for the surface-coated end mill (Comparative Examples 9 and 10) where the average layer thickness of the coating layer was outside the range of 2 to 10 μm. The crystal grain length ratio is outside the range specified in the present invention, or the crystal grain length ratio occupied by crystal grains having a grain size of 0.15 μm or less at the interface between the tool base and the hard coating layer is 20%. It was over.
Tables 2 and 3 show the values measured and calculated as described above.
なお、前記平均層厚の測定法、粒径の測定法、結晶粒径長割合の測定法をより具体的にいえば、以下のとおりである。 More specifically, the measurement method of the average layer thickness, the measurement method of the particle size, and the measurement method of the crystal grain size length ratio are as follows.
被覆工具の切れ刃先端のコーナー部を含み、逃げ面の断面を研磨加工した後、その断面を走査型電子顕微鏡（Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｙ：ＳＥＭ）で観察する。
工具基体と硬質被覆層の界面から硬質被覆層表面までの距離を５箇所で測定し、その平均値を平均層厚とした。なお、測定する箇所は、逃げ面上刃先から、逃げ面上にて刃先から１００μｍ離れた位置までの間の任意の５箇所とする。
After polishing the cross section of the flank, including the corner portion of the cutting edge of the coated tool, the cross section is observed with a scanning electron microscope (SEM).
The distance from the interface between the tool base and the hard coating layer to the surface of the hard coating layer was measured at five locations, and the average value was taken as the average layer thickness. In addition, the location to measure shall be arbitrary 5 places from the flank upper blade edge to the position 100 micrometers away from the blade edge on the flank.
硬質被覆層表面から深さ０．５μｍの領域に形成されている結晶粒、硬質被覆層内における工具基体と硬質被覆層の界面から厚さ０．５μｍの領域に形成されている結晶粒および硬質被覆層表面と工具基体表面の中間の領域に存在する結晶粒に対して、工具基体表面と平行に直線を引き、結晶粒界間の距離を粒径と定義する。それぞれの領域において、逃げ面上にて刃先から２５μｍ離れた位置および刃先から７５μｍ離れた位置および逃げ面上にて刃先から１２５μｍ離れた位置および刃先から１７５μｍ離れた位置の４箇所、計１２箇所において幅１０μｍの範囲内に存在する結晶の平均結晶粒径を測定する。幅１０μｍの粒径を測定するにあたり、各測定箇所を中心に刃先側５μｍ、刃先と逆側５μｍの測定データを用いた。 Crystal grains formed in a region having a depth of 0.5 μm from the surface of the hard coating layer, crystal grains formed in a region having a thickness of 0.5 μm from the interface between the tool base and the hard coating layer in the hard coating layer, and hard A straight line is drawn in parallel to the tool substrate surface with respect to the crystal grains existing in the intermediate region between the coating layer surface and the tool substrate surface, and the distance between the crystal grain boundaries is defined as the particle size. In each region, at a total of 12 locations on the flank face, a position 25 μm away from the cutting edge, a position 75 μm away from the cutting edge, a position 125 μm away from the cutting edge on the flank face, and a position 175 μm away from the cutting edge. The average crystal grain size of crystals existing within a width of 10 μm is measured. In measuring a particle diameter of 10 μm in width, measurement data of 5 μm on the blade edge side and 5 μm on the opposite side to the blade edge were used centering on each measurement point.
また、刃先から１００μｍ離れた位置までの範囲における粒径０．１５μｍ以下の結晶粒が占める結晶粒径長割合および粒径１μｍ以下結晶粒が占める結晶粒径長割合の測定方法は、前記粒径を測定した逃げ面上にて刃先から２５μｍ離れた位置および刃先から７５μｍ離れた位置の界面２箇所、表面２箇所および中間領域２箇所で測定した結晶粒径の全測定データを用いる。測定した全結晶粒径の和に対する、粒径が０．１５μｍ以下および１μｍ以下の結晶粒径の和を「刃先から１００μｍ離れた位置までの範囲における粒径０．１５μｍ以下の結晶粒が占める結晶粒径長割合」および「刃先から１００μｍ離れた位置までの範囲における粒径１μｍ以下の結晶粒が占める結晶粒径長割合」とした。
また、刃先から１００μｍ離れた位置までの範囲における界面で粒径が０．１５μｍ以下の結晶粒が占める結晶粒径長割合の測定方法は、前記粒径を測定した界面２箇所の全測定データを用いる。測定した全結晶粒径の和に対する、粒径が０．１５μｍ以下の結晶粒径の和を「刃先から１００μｍ離れた位置の範囲における界面の粒径０．１５μｍ以下の結晶粒が占める結晶粒径長割合」とした。
また、刃先から１００〜２００μｍ離れた位置の範囲における粒径０．１５μｍ以下の結晶粒が占める結晶粒径長割合および粒径１μｍ以下結晶粒が占める結晶粒径長割合の測定方法は、前記粒径を測定した逃げ面上にて刃先から１２５μｍ離れた位置および刃先から１７５μｍ離れた位置の界面２箇所、表面２箇所および中間領域２箇所で測定した結晶粒径の全測定データを用いる。測定した全結晶粒径の和に対する、粒径が０．１５μｍ以下および１μｍ以下の結晶粒径の和を「刃先から１００〜２００μｍ離れた位置までの範囲における粒径０．１５μｍ以下の結晶粒が占める結晶粒径長割合」および「刃先から１００〜２００μｍ離れた位置までの範囲における粒径１μｍ以下の結晶粒が占める結晶粒径長割合」とした。
Further, the method for measuring the crystal grain length ratio of the crystal grains having a grain size of 0.15 μm or less and the crystal grain length ratio of the crystal grains having a grain size of 1 μm or less in the range up to a position away from the blade edge by 100 μm is the above-mentioned grain size All measured data of the crystal grain size measured at two interfaces, two surfaces, and two intermediate regions at a position 25 μm away from the cutting edge and a position 75 μm away from the cutting edge on the flank face where the measurement was taken. The sum of the crystal grain sizes with a grain size of 0.15 μm or less and 1 μm or less with respect to the sum of the total crystal grain sizes measured is “a crystal occupied by crystal grains having a grain size of 0.15 μm or less in a range up to a position 100 μm away from the blade edge The grain size length ratio ”and“ the crystal grain length ratio occupied by crystal grains having a grain size of 1 μm or less in a range from the cutting edge to a position 100 μm away ”.
Moreover, the measuring method of the crystal grain length ratio occupied by the crystal grains having a grain size of 0.15 μm or less at the interface in the range up to a position 100 μm away from the cutting edge is obtained by measuring all the measurement data at the two interfaces where the grain size was measured. Use. The sum of the crystal grain sizes with a grain size of 0.15 μm or less relative to the sum of the total crystal grain sizes measured is “the crystal grain size occupied by crystal grains with an interface grain size of 0.15 μm or less in the range of a position 100 μm away from the cutting edge. "Long ratio".
In addition, the method for measuring the crystal grain size length ratio occupied by crystal grains having a grain size of 0.15 μm or less and the crystal grain size length ratio occupied by crystal grains having a grain size of 1 μm or less in the range of a position 100 to 200 μm away from the cutting edge includes the above-mentioned grains All measured data of the crystal grain size measured at two interfaces, two surfaces and two intermediate regions at a position 125 μm away from the blade edge and a position 175 μm away from the blade edge on the flank whose diameter was measured is used. The sum of the crystal grain sizes of 0.15 μm or less and 1 μm or less with respect to the sum of the measured total crystal grain sizes is expressed as “crystal grains having a particle size of 0.15 μm or less in a range from 100 to 200 μm away from the blade edge. “Crystal grain size length ratio” and “Crystal grain size length ratio occupied by crystal grains having a grain size of 1 μm or less in the range from 100 to 200 μm away from the blade edge”.
さらに、本発明１〜５および比較例１〜１０の刃先角度αを測定するとともに、切れ刃先端のコーナー部の硬質被覆層の中の連続クラックの占有角度βを測定し、クラック占有率β／αの値を算出した。
表２、表３に、これらの値を示す。
なお、前記刃先角度α、連続クラックの占有角度βの測定法をより具体的にいえば、以下のとおりである。
結晶粒径を測定するために観察したＳＥＭ像のうち、切れ刃先端部の断面ＳＥＭ像を用いる。測定条件は、観察倍率：１００００倍、加速電圧：３ｋＶの条件を使用した。本発明２の切れ刃先端部の断面ＳＥＭ像（ａ）及び模式図（ｂ）を図４に示す。図４（ｂ）を用いて説明する。逃げ面上の刃先をＡ、すくい面上の刃先をＢとする。Ａを通る逃げ面の垂線、Ｂを通るすくい面の垂線を引き、双方の垂線の交点を中心Ｏとする。刃先角度α（度）はＡ−Ｏ−Ｂのなす角度とする。
また、切れ刃先端のコーナー部の硬質被覆層中に形成されている連続クラックについて、前記中心Ｏから該クラックを投影させた場合、Ａを通る逃げ面の垂線に最も近い箇所をＣとし、Ｂを通るすくい面の垂線に最も近い箇所をＤとする。連続クラックの占有角度β（度）はＣ−Ｏ−Ｄのなす角度とする。なお、切れ刃先端のコーナー部の硬質被覆層中に複数のクラックが存在する場合、最大値を示す連続クラックにて算出した値を連続クラックの占有角度βと定義する。
そして、（連続クラックの占有角度β）／（刃先角度α）の値を、クラック占有率であると定義する。
Furthermore, while measuring the blade edge angle α of the present invention 1-5 and Comparative Examples 1-10, the occupation angle β of the continuous crack in the hard coating layer at the corner portion at the tip of the cutting edge was measured, and the crack occupation ratio β / The value of α was calculated.
Tables 2 and 3 show these values.
More specifically, the measurement method of the edge angle α and the occupying angle β of the continuous crack is as follows.
Of the SEM images observed for measuring the crystal grain size, a cross-sectional SEM image of the tip of the cutting edge is used. The measurement conditions used were an observation magnification of 10,000 times and an acceleration voltage of 3 kV. FIG. 4 shows a cross-sectional SEM image (a) and a schematic diagram (b) of the cutting edge tip of the present invention 2. This will be described with reference to FIG. The cutting edge on the flank is A, and the cutting edge on the rake face is B. The perpendicular of the flank passing through A and the perpendicular of the rake face passing through B are drawn, and the intersection of both perpendiculars is set as the center O. The blade edge angle α (degrees) is an angle formed by AOB.
Further, regarding the continuous crack formed in the hard coating layer at the corner portion at the tip of the cutting edge, when the crack is projected from the center O, the point closest to the perpendicular of the flank passing through A is defined as C, and B Let D be the point closest to the normal of the rake face passing through. The occupying angle β (degrees) of continuous cracks is an angle formed by C-O-D. When there are a plurality of cracks in the hard coating layer at the corner portion at the tip of the cutting edge, the value calculated by the continuous crack showing the maximum value is defined as the occupation angle β of the continuous crack.
The value of (occupation angle β of continuous crack) / (blade edge angle α) is defined as the crack occupancy rate.
つぎに、前述した本発明１〜５および比較例１〜１０のエンドミルのうち、本発明１〜３および比較例１〜３、６〜８については、
被削材−平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ５５Ｃの板材、
回転速度： １５０００ ｍｉｎ．−１、
横方向切り込み： ２．０ ｍｍ、
縦方向切り込み： ０．３ ｍｍ、
送り速度（１刃当り）： ０．０６ ｍｍ／ｔｏｏｔｈ、
切削長：３４０ｍ、
の条件（切削条件Ａという）での炭素鋼の溝切削加工試験を実施し、
また、本発明４，５および比較例４，５，９，１０については、
被削材−平面寸法：１００ｍｍ×２５０ｍｍ、厚さ：５０ｍｍのＪＩＳ・Ｓ５５Ｃの板材、
回転速度： ３０００ ｍｉｎ．−１、
横方向切り込み： １０ ｍｍ、
縦方向切り込み： １ ｍｍ、
送り速度（１刃当り）： ０．０７ ｍｍ／ｔｏｏｔｈ、
切削長：９０ｍ、
の条件（切削条件Ｂという）の炭素鋼の溝切削加工試験を実施し、
いずれの溝切削加工試験でも切刃の逃げ面摩耗幅を測定した。
この測定結果を表４に示した。
Next, among the above-described end mills of the present inventions 1 to 5 and comparative examples 1 to 10, the present inventions 1 to 3 and comparative examples 1 to 3 and 6 to 8 are
Work material-Plane size: 100 mm x 250 mm, thickness: 50 mm JIS / S55C plate material,
Rotational speed: 15000 min. -1 ,
Lateral cut: 2.0 mm,
Longitudinal cut: 0.3 mm,
Feed rate (per blade): 0.06 mm / tooth,
Cutting length: 340m,
Conducted a groove cutting test of carbon steel under the conditions (cutting condition A),
Moreover, about this invention 4, 5 and comparative examples 4, 5, 9, and 10,
Work material-Plane size: 100 mm x 250 mm, thickness: 50 mm JIS / S55C plate material,
Rotational speed: 3000 min. -1 ,
Lateral cut: 10 mm,
Longitudinal cut: 1 mm,
Feed rate (per tooth): 0.07 mm / tooth,
Cutting length: 90m,
Conducted a groove cutting test of carbon steel under the conditions (referred to as cutting condition B),
In any groove cutting test, the flank wear width of the cutting edge was measured.
The measurement results are shown in Table 4.
原料粉末として、いずれも１〜３μｍの平均粒径を有するＷＣ粉末、ＴｉＣ粉末、ＺｒＣ粉末、ＶＣ粉末、ＴａＣ粉末、ＮｂＣ粉末、Ｃｒ３Ｃ２粉末、ＴｉＮ粉末、ＴａＮ粉末、およびＣｏ粉末を用意し、これら原料粉末を、表５に示される配合組成に配合し、ボールミルで７２時間湿式混合し、乾燥した後、１００ＭＰａの圧力で圧粉体にプレス成形し、この圧粉体を６Ｐａの真空中、温度：１４００℃に１時間保持の条件で焼結し、焼結後、刃先部分にＲ：０．０３のホーニング加工を施し、さらに仕上げ研磨を施すことにより、ＩＳＯ規格・ＳＮＧＡ１２０４０８のインサート形状をもったＷＣ基超硬合金製の工具基体６〜１０を形成した。 WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr 3 C 2 powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 5, wet mixed by a ball mill for 72 hours, dried, and then pressed into a green compact at a pressure of 100 MPa. The green compact was vacuumed at 6 Pa. Medium temperature: Sintered at 1400 ° C for 1 hour. After sintering, insert edge shape of ISO standard, SNGA120408 by applying honing of R: 0.03 to the cutting edge and further polishing. Tool bases 6 to 10 made of WC-base cemented carbide having
ついで、これらの工具基体（インサート）６〜１０の表面をアセトン中で超音波洗浄し、乾燥した状態で、同じく図２に示すＡＩＰ装置に装入し、前記実施例１と同一の条件で、表６に示される組成および目標平均層厚の（Ａｌ，Ｃｒ）Ｎ層からなる硬質被覆層を形成することにより、本発明被覆工具としての本発明被覆超硬インサート（以下、本発明６〜１０という）をそれぞれ製造した。 Next, the surfaces of these tool bases (inserts) 6 to 10 are ultrasonically cleaned in acetone and dried, and then inserted into the AIP apparatus shown in FIG. 2 under the same conditions as in Example 1. By forming a hard coating layer composed of an (Al, Cr) N layer having the composition and target average layer thickness shown in Table 6, the coated carbide insert of the present invention as the coated tool of the present invention (hereinafter referred to as the present invention 6 to 10). Each).
比較例２：
比較の目的で、前記の工具基体（インサート）６〜１０に対して、前述した比較例１と同一の条件で、表７に示される組成および目標平均層厚の（Ａｌ，Ｃｒ）Ｎ層からなる硬質被覆層を形成することにより、比較例被覆工具としての比較例被覆超硬インサート（以下、比較例１１〜２０という）をそれぞれ製造した。
Comparative Example 2:
For comparison purposes, the composition and target average layer thickness (Al, Cr) N layers shown in Table 7 were used for the above-mentioned tool bases (inserts) 6 to 10 under the same conditions as in Comparative Example 1 described above. Comparative example coated carbide inserts (hereinafter referred to as Comparative Examples 11 to 20) as comparative example coated tools were produced by forming the hard coating layer.
前述のように作製した本発明６〜１０について、逃げ面上の刃先から１００μｍ離れた位置までの範囲において、縦断面の硬質被覆層の平均層厚、粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合、粒径１．０μｍ以下の結晶粒の占める結晶粒径長割合を算出した。
また、刃先から１００μｍ離れた位置までの範囲における工具基体と硬質被覆層の界面における粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合を測定したところ、２０％以下であることも確認した。
About this invention 6-10 produced as mentioned above, the average layer thickness of the hard coating layer of a longitudinal section, and the grain of a particle size of 0.15 micrometer or less occupy in the range from the blade edge on a flank to the position of 100 micrometers away The crystal grain length ratio was calculated as the crystal grain length ratio occupied by crystal grains having a grain size of 1.0 μm or less.
Further, when the ratio of the crystal grain size length occupied by the crystal grains having a grain size of 0.15 μm or less at the interface between the tool base and the hard coating layer in the range up to 100 μm away from the blade edge was measured, it was confirmed that it was 20% or less. did.
一方、比較例１１〜２０について、本発明と同様な観察、測定を行ったところ、被覆層の平均層厚が２〜１０μｍの範囲外の表面被覆インサート（比較例１９，２０）以外では、前述の逃げ面上の刃先近傍の結晶粒の粒径分布（結晶粒径長割合）が本発明で規定した範囲外、あるいは、工具基体と硬質被覆層の界面における粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合を測定したところ、２０％を超えていることを確認した。
また、本発明６〜１０、比較例１１〜２０について、刃先角度α、連続クラックの占有角度β、クラック占有率β／αの値についても測定・算出した。
表６、表７に、前記で測定・算出したそれぞれの値を示す。
On the other hand, when Comparative Examples 11 to 20 were observed and measured in the same manner as in the present invention, except for the surface coating inserts (Comparative Examples 19 and 20) where the average layer thickness of the coating layer was outside the range of 2 to 10 μm. The crystal grain size distribution (crystal grain length ratio) in the vicinity of the cutting edge on the flank face is outside the range defined by the present invention, or the grain size is 0.15 μm or less at the interface between the tool base and the hard coating layer As a result, the ratio of the crystal grain length occupied by was confirmed to exceed 20%.
Further, for the present inventions 6 to 10 and Comparative Examples 11 to 20, the values of the blade edge angle α, the continuous crack occupying angle β, and the crack occupying ratio β / α were also measured and calculated.
Tables 6 and 7 show the values measured and calculated as described above.
なお、前記平均層厚の測定法、粒径の測定法、結晶粒径長割合の測定法は、実施例１と同じ方法を用いた。 The average layer thickness measurement method, the particle size measurement method, and the crystal grain size length ratio measurement method were the same as in Example 1.
つぎに、本発明６〜１０、比較例１１〜２０の被覆インサートを、いずれも工具鋼製バイトの先端部に固定治具にてネジ止めした状態で、
被削材：ＪＩＳ・ＳＣＭ４４０の丸棒、
切削速度：９０ｍ／ｍｉｎ．、
切り込み：１．５ｍｍ、
送り：０．３ｍｍ／ｒｅｖ．、
切削時間：３分、
の条件（切削条件Ｃという）での合金鋼（クロムモリブデン鋼）の乾式連続切削加工試験を実施し、切刃の逃げ面摩耗幅を測定した。
この測定結果を表８に示した。
Next, in the state where all of the coated inserts of the present invention 6 to 10 and Comparative Examples 11 to 20 are screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SCM440 round bar,
Cutting speed: 90 m / min. ,
Incision: 1.5mm,
Feed: 0.3 mm / rev. ,
Cutting time: 3 minutes
A dry continuous cutting test of alloy steel (chromium molybdenum steel) under the above conditions (referred to as cutting condition C) was performed, and the flank wear width of the cutting edge was measured.
The measurement results are shown in Table 8.
表４，８に示される結果から、本発明被覆工具は、所定の組成のＡｌとＣｒの複合窒化物層を有し、複合窒化物層が、逃げ面上の刃先から１００μｍ離れた位置までの範囲において、粒径０．１５μｍ以下の結晶粒と粒径１．０μｍ以下の結晶粒の占める結晶粒径長割合がそれぞれ所定の値である粒径分布を有し、逃げ面上の刃先から１００μｍ離れた位置までの範囲の工具基体と複合窒化物層の界面において、粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合が所定値以下であることから、さらには、クラック占有率が０．３〜１．０となっていることから、炭素鋼等の切削加工において、すぐれた耐チッピング性、耐摩耗性を発揮するものである。
これに対して、硬質被覆層の構造が本発明で規定する範囲を外れる比較例被覆工具では、チッピング発生あるいは耐摩耗性の低下によって、比較的短時間で使用寿命に至ることが明らかである。
From the results shown in Tables 4 and 8, the coated tool of the present invention has a composite nitride layer of Al and Cr having a predetermined composition, and the composite nitride layer reaches a position 100 μm away from the cutting edge on the flank. In the range, the crystal grain length ratio of the crystal grains having a grain size of 0.15 μm or less and the crystal grains having a grain size of 1.0 μm or less has a predetermined grain size distribution, and 100 μm from the cutting edge on the flank. At the interface between the tool base and the composite nitride layer in the range up to a distant position, the crystal grain size length ratio occupied by crystal grains having a grain size of 0.15 μm or less is a predetermined value or less. Since it is 0.3 to 1.0, it exhibits excellent chipping resistance and wear resistance in cutting of carbon steel and the like.
On the other hand, it is apparent that the comparative coated tool in which the structure of the hard coating layer is outside the range defined in the present invention reaches the service life in a relatively short time due to occurrence of chipping or a decrease in wear resistance.
前述のように、本発明の被覆工具は、炭素鋼等の切削加工に供した場合に長期に亘ってすぐれた切削性能を示すものであるから、切削加工装置の自動化並びに切削加工の省力化および省エネ化、さらに低コスト化に十分満足に対応できるものである。 As described above, the coated tool of the present invention exhibits excellent cutting performance over a long period when subjected to cutting of carbon steel or the like. It can cope with energy saving and cost reduction sufficiently satisfactorily.
Claims (3)
（ａ）前記硬質被覆層は、ＡｌとＣｒの合量に占めるＣｒの含有割合が０．２〜０．５（但し、原子比）であるＡｌとＣｒの複合窒化物層を有し、
（ｂ）前記複合窒化物層は、逃げ面上の刃先から１００μｍ離れた位置までの範囲において、粒径０．１５μｍ以下の結晶粒と粒径１μｍ以下の結晶粒の占める結晶粒径長割合がそれぞれ２０〜７０％、９５％以上であり、
（ｃ）前記逃げ面上の刃先から１００μｍ離れた位置までの範囲の工具基体と前記複合窒化物層の界面において、粒径０．１５μｍ以下の結晶粒の占める結晶粒径長割合が２０％以下である、
ことを特徴とする表面被覆切削工具。 In a surface-coated cutting tool in which a hard coating layer having an average layer thickness of 2 to 10 μm is vapor-deposited on the surface of a tool base composed of a tungsten carbide-based cemented carbide,
(A) The hard coating layer has a composite nitride layer of Al and Cr in which the content ratio of Cr in the total amount of Al and Cr is 0.2 to 0.5 (however, the atomic ratio);
(B) The composite nitride layer has a crystal grain length ratio of crystal grains having a grain size of 0.15 μm or less and crystal grains having a grain size of 1 μm or less in a range from the cutting edge on the flank to a position 100 μm away. 20-70%, 95% or more,
(C) at the interface of the tool substrate ranging from the cutting edge on the flank face to a position spaced 100μm and the composite nitride layer, crystal grains vector length ratio particle diameter 0.15μm below the crystal grains 20% or less Is,
A surface-coated cutting tool characterized by that.
ことを特徴とする請求項１に記載の表面被覆切削工具。 At the interface of the flank on the position to the tool substrate and the composite nitride layer ranging away 100~200μm from the cutting edge of the crystal grains occupying less particle size 0.15μm of crystal grains and grain size 1μm or less of the grain The length ratio is 20% or less and 95% or more, respectively.
The surface-coated cutting tool according to claim 1.
If the cutting edge angle of the surface-coated cutting tool as α degrees, and the occupation angle of the continuous crack the formed hard coating layer of the corner portion of the cutting edge tip in the angular range of the α degree and β degree The surface-coated cutting tool according to claim 1 or 2, wherein a crack occupation ratio β / α is 0.3 to 1.0.
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