JP5831708B2 - Surface coated cutting tool - Google Patents
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- JP5831708B2 JP5831708B2 JP2012056662A JP2012056662A JP5831708B2 JP 5831708 B2 JP5831708 B2 JP 5831708B2 JP 2012056662 A JP2012056662 A JP 2012056662A JP 2012056662 A JP2012056662 A JP 2012056662A JP 5831708 B2 JP5831708 B2 JP 5831708B2
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- 238000005520 cutting process Methods 0.000 title claims description 99
- 239000013078 crystal Substances 0.000 claims description 174
- 239000011247 coating layer Substances 0.000 claims description 105
- 239000010410 layer Substances 0.000 claims description 46
- 229910052804 chromium Inorganic materials 0.000 claims description 25
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 claims description 5
- 239000002131 composite material Substances 0.000 claims description 4
- 150000004767 nitrides Chemical class 0.000 claims description 4
- 239000011651 chromium Substances 0.000 description 32
- 239000000843 powder Substances 0.000 description 22
- 230000000052 comparative effect Effects 0.000 description 20
- 238000005259 measurement Methods 0.000 description 14
- 239000000758 substrate Substances 0.000 description 13
- 229910000599 Cr alloy Inorganic materials 0.000 description 11
- QQHSIRTYSFLSRM-UHFFFAOYSA-N alumanylidynechromium Chemical compound [Al].[Cr] QQHSIRTYSFLSRM-UHFFFAOYSA-N 0.000 description 10
- 239000010935 stainless steel Substances 0.000 description 10
- 229910001220 stainless steel Inorganic materials 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 239000002245 particle Substances 0.000 description 9
- 239000011248 coating agent Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 6
- 238000010891 electric arc Methods 0.000 description 6
- 238000000691 measurement method Methods 0.000 description 6
- 238000007740 vapor deposition Methods 0.000 description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 229910001873 dinitrogen Inorganic materials 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000007733 ion plating Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000012495 reaction gas Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 238000005240 physical vapour deposition Methods 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910001018 Cast iron Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910001315 Tool steel Inorganic materials 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- VNTLIPZTSJSULJ-UHFFFAOYSA-N chromium molybdenum Chemical compound [Cr].[Mo] VNTLIPZTSJSULJ-UHFFFAOYSA-N 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
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- Drilling Tools (AREA)
- Cutting Tools, Boring Holders, And Turrets (AREA)
- Physical Vapour Deposition (AREA)
Description
この発明は、ステンレス鋼等の難削材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 wear resistance in a hard coating layer when cutting difficult-to-cut materials such as stainless steel.
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スローアウエイチップ、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、また前記スローアウエイチップ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スローアウエイエンドミル工具などが知られている。 In general, for coated tools, throwaway inserts that are detachably attached to the tip of the cutting tool for turning and planing of various steel and cast iron materials, drilling of the work material, etc. There are also drills used in the above, solid type end mills used for chamfering, grooving, shoulder processing, etc. of the work material. Slow-away end mill tools that perform cutting work are known.
例えば、特許文献１に示すように、被覆工具として、炭化タングステン（以下、ＷＣで示す）基超硬合金で構成された基体（以下、工具基体という）の表面に、ＡｌとＣｒの複合窒化物［以下、（Ａｌ，Ｃｒ）Ｎで示す］層からなる硬質被覆層を蒸着形成してなる被覆工具が知られており、かかる従来の被覆工具においては、硬質被覆層を構成する前記（Ａｌ，Ｃｒ）Ｎ層が、すぐれた高温硬さ、耐熱性、高温強度、高温耐酸化性等を有することから、すぐれた切削性能を発揮することが知られている。
そして、上記従来の被覆工具は、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上記の工具基体を装入し、ヒータで工具基体を５００℃の温度に加熱した状態で、アノード電極と所定組成のＡｌ−Ｃｒ合金がセットされたカソード電極との間に、電流：９０Ａの条件でアーク放電を発生させ、同時に装置内に反応ガスとして窒素ガスを導入して、２Ｐａの反応雰囲気とし、一方、上記工具基体には、−１００Ｖのバイアス電圧を印加した条件で、前記工具基体の表面に、上記（Ａｌ，Ｃｒ）Ｎ層を蒸着形成することにより製造し得ることも知られている。
For example, as shown in Patent Document 1, as a coated tool, a composite nitride of Al and Cr is formed on the surface of a base (hereinafter referred to as a tool base) made of tungsten carbide (hereinafter referred to as WC) based cemented carbide. A coating tool formed by vapor-depositing a hard coating layer composed of a layer [hereinafter referred to as (Al, Cr) N] is known. In such a conventional coating tool, the (Al, Cr) Since the Cr) N layer has excellent high-temperature hardness, heat resistance, high-temperature strength, high-temperature oxidation resistance, etc., it is known to exhibit excellent cutting performance.
In the conventional coated tool, for example, as shown in FIG. 1, the tool base is loaded into an arc ion plating apparatus which is a kind of physical vapor deposition apparatus, and the tool base is heated to 500 ° C. with a heater. In the heated state, arc discharge is generated under the condition of current: 90 A between the anode electrode and the cathode electrode on which an Al—Cr alloy having a predetermined composition is set, and at the same time, nitrogen gas is introduced into the apparatus as a reaction gas. Then, the reaction atmosphere is 2 Pa, while the (Al, Cr) N layer is formed on the surface of the tool base by vapor deposition under the condition that a bias voltage of −100 V is applied to the tool base. It is also known that it can.
ところで、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。
例えば、特許文献２には、すくい面での被覆層の欠損を抑制して耐欠損性を向上させ、また、逃げ面における耐摩耗性を向上させた被覆工具として、被覆層を柱状結晶で構成し、すくい面における被覆層厚は逃げ面での被覆層厚よりも薄く、被覆層表面側の上層領域の平均結晶幅が、被覆層基体側の下層領域の平均結晶幅よりも大きい２つの層領域にて構成し、すくい面での被覆層厚に対する上層領域の厚みの比率が、逃げ面での被覆層厚に対する上層領域の厚みの比率よりも小さく、すくい面での柱状結晶の平均結晶幅が逃げ面での柱状結晶の平均結晶幅より小さい被覆工具（エンドミル）が記載されている。
また、例えば、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優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。
By the way, in the coated tool, various proposals have been made for the structure of the hard coating layer in order to improve its cutting performance, particularly chipping resistance, wear resistance, and the like.
For example, Patent Document 2 discloses that the coating layer is made of columnar crystals as a coating tool that improves chipping resistance by suppressing chipping of the coating layer on the rake face, and improves wear resistance on the flank face. The coating layer thickness at the rake face is smaller than the coating layer thickness at the flank face, and the average crystal width of the upper layer region on the coating layer surface side is larger than the average crystal width of the lower layer region on the coating layer substrate side. The ratio of the thickness of the upper layer region to the coating layer thickness at the rake face is smaller than the ratio of the thickness of the upper layer region to the coating layer thickness at the flank face, and the average crystal width of the columnar crystals at the rake face Describes a coated tool (end mill) that is smaller than the average crystal width of the columnar crystals at the flank face.
Further, for example, Patent Document 3 discloses a coating tool formed on a substrate as a coating tool having a coating having both wear resistance and toughness and excellent adhesion to the substrate. One coating layer, 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 it of 10 to 200 nm, and An average compressive stress which is present in a range of 50% or more of the total thickness of the first coating layer from the surface side of one coating layer and is a stress in a 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 on the surface side in the thickness direction. Coated tools with higher compressive stress It is.
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。
上記従来の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、これをステンレス鋼等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.
The above conventional coated tools can improve chipping resistance, chipping resistance, and wear resistance to some extent, but if this is used for more severe cutting such as stainless steel, chipping is likely to occur. Or, wear and wear increase, and due to this, the service life is reached in a relatively short time.
そこで、本発明者等は、ステンレス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。 Therefore, the present inventors have provided a hard coating layer in order to provide a coated tool that has excellent chipping resistance as well as wear resistance in cutting processing of stainless steel and the like, and exhibits excellent cutting performance over a long period of use. As a result of earnest research on the crystal structure of the following, the following knowledge was 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、ＰＶＤ法の一種であるアークイオンプレーティング法（以下、ＡＩＰ法という）により（Ａｌ，Ｃｒ）Ｎ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、工具基体を装置内に装入し、所定のバイアス電圧を印加するとともに、装置内を所定温度に加熱した状態で、アノード電極と所定組成のＡｌ−Ｃｒ合金ターゲットとの間にアーク放電を発生させ、同時に装置内に反応ガスとして窒素ガスを導入し、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（図１参照）。 Conventionally, as a means for forming a hard coating layer, a CVD method, a PVD method, or the like is generally employed as a means for forming a coated tool. For example, an arc ion plating method (hereinafter referred to as a PVD method) When the hard coating layer made of (Al, Cr) N is formed by the AIP method), as shown in Patent Document 1, the tool base is inserted into the apparatus and a predetermined bias voltage is applied. At the same time, an arc discharge is generated between the anode electrode and the Al—Cr alloy target having a predetermined composition while the apparatus is heated to a predetermined temperature, and simultaneously nitrogen gas is introduced into the apparatus as a reaction gas, and a predetermined pressure is applied. A hard coating layer was formed by vapor deposition in the reaction atmosphere (see FIG. 1).
本発明者らは、上記従来のＡＩＰ法による（Ａｌ，Ｃｒ）Ｎ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、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、そして、硬質被覆層の切刃から１００μｍ以内の硬質被覆層を、所定の平均粒径を有する粒状結晶粒と微細結晶粒の混合組織として構成し、また、０．１５μｍ以下の結晶粒の結晶粒径長割合についても２０％以下とすることによって、さらに、切れ刃先端のコーナー部に形成される連続クラックのクラック占有率を０．３〜１．０に調整することによって、このような硬質被覆層を備えた被覆工具は、ステンレス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ことを見出したのである。 The inventors applied a magnetic field between the tool base and the target when forming the hard coating layer made of (Al, Cr) N by the conventional AIP method, and measured the influence of the magnetic field on the structure of the hard coating layer. As a result of investigation and investigation, it is possible to adjust the grain size, formation region, and distribution of crystal grains constituting the hard coating layer by performing the formation of the hard coating layer by the AIP method in a magnetic field having a predetermined strength. The hard coating layer within 100 μm from the cutting edge of the hard coating layer is configured as a mixed structure of granular crystal grains having a predetermined average grain size and fine crystal grains, and the crystal grain size of the crystal grains of 0.15 μm or less By setting the length ratio to 20% or less, and further adjusting the crack occupancy ratio of continuous cracks formed at the corner portion at the tip of the cutting edge to 0.3 to 1.0, It was found that a coated tool with a quality coating layer exhibits excellent chipping resistance and wear resistance in cutting of stainless steel and the like, and exhibits excellent cutting performance over a long period of use. .
この発明は、上記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の硬質被覆層が形成された被覆工具において、
（ａ）硬質被覆層は、ＡｌとＣｒの複合窒化物層からなり、かつ、該層においてＡｌとＣｒの合量に占めるＣｒの含有割合は０．２〜０．５（但し、原子比）であり、
（ｂ）上記被覆工具の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、硬質被覆層は平均粒径０．２〜１μｍの粒状結晶粒と平均粒径０．０８μｍ以下の微細結晶粒との混合組織を有し、また、粒径０．１μｍ未満の微細結晶粒の結晶粒径長割合は、上記混合組織中の１０〜５０％を占め、
（ｃ）上記被覆工具の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は２０％以下であることを特徴とする被覆工具。
（２） 上記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、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前記（１）に記載の被覆工具。」
に特徴を有するものである。
This invention has been made based on the above findings,
“(1) In a coated tool in which a hard coating layer having an average layer thickness of 2 to 10 μm is formed on the surface of a tool base composed of a tungsten carbide base cemented carbide,
(A) The hard coating layer is composed of a composite nitride layer of Al and Cr, and the content ratio of Cr in the total amount of Al and Cr in the layer is 0.2 to 0.5 (however, atomic ratio) And
(B) In the range from the cutting edge on the flank of the above coated tool to a position 100 μm away, the hard coating layer is composed of granular crystal grains having an average grain diameter of 0.2 to 1 μm and fine crystals having an average grain diameter of 0.08 μm or less. The crystal grain size ratio of fine crystal grains having a grain size of less than 0.1 μm occupies 10 to 50% of the above-mentioned mixed structure,
(C) At the interface between the tool base and the hard coating layer in the range from the cutting edge on the flank face of the coated tool to a position 100 μm away, the crystal grain size length ratio occupied by crystal grains having a grain size of 0.15 μm or less is 20 Coated tool characterized by being less than or equal to%.
(2) When the cutting edge angle of the coated 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 within the angle range of the α degrees is β degrees, The covering tool according to (1), wherein the crack occupation ratio β / α is 0.3 to 1.0. "
It has the characteristics.
つぎに、この発明の被覆工具について詳細に説明する。
（ａ）硬質被覆層の種別、平均層厚：
この発明の硬質被覆層は、ＡｌとＣｒの複合窒化物層（（Ａｌ，Ｃｒ）Ｎ層）からなる。
上記（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。
また、（Ａｌ，Ｃｒ）Ｎ層からな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方法は、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にて、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任意の５箇所で測定し、その平均値を平均層厚とした。
Next, the coated tool of the present invention will be described in detail.
(A) Type of hard coating layer, average layer thickness:
The hard coating layer of the present invention is composed of a composite nitride layer of Al and Cr ((Al, Cr) N layer).
In the (Al, Cr) N layer, the Al component improves the high temperature hardness and heat resistance, the Cr component improves the high temperature strength, and the high temperature oxidation resistance is improved by the 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.
In addition, if the average thickness of the hard coating layer made of the (Al, Cr) N layer is less than 2 μm, excellent wear resistance cannot be exhibited over a long period of time, resulting in 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 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. 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 any five locations, and the average value was taken as the average layer thickness.
（ｂ）（Ａｌ，Ｃｒ）Ｎ層からなる硬質被覆層の層構造：
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、硬質被覆層は平均粒径０．２〜１μｍの粒状結晶粒と平均粒径０．０８μｍ以下の微細結晶粒との混合組織から構成し、そして、粒径０．１μｍ未満の微細結晶粒の結晶粒径長割合は、上記混合組織中の１０〜５０％を占める。
また、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は２０％以下とする。
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「粒状結晶」とはアスペクト比が１以上６以下であり、かつ、粒径０．１μｍ以上の結晶粒を意味する。「微細結晶」とは、アスペクト比が１以上６以下であり、かつ、粒径０．１μｍ未満の結晶粒を意味する。アスペクト比は、結晶粒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。
また、ここで「粒径が０．１μｍ未満の微細結晶粒の結晶粒径長割合」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が０．１μｍ未満の結晶粒径長の和の割合を示し、また、「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す。
(B) Layer structure of hard coating layer composed of (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 hard coating layer is composed of granular crystal grains having an average grain diameter of 0.2 to 1 μm and fine crystal grains having an average grain diameter of 0.08 μm or less. The crystal grain length ratio of fine crystal grains composed of a mixed structure and having a particle diameter of less than 0.1 μm occupies 10 to 50% of the mixed structure.
In addition, at the interface between the tool base and the hard coating layer, 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.
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.
Further, the “granular crystal” herein means crystal grains having an aspect ratio of 1 or more and 6 or less and a grain size of 0.1 μm or more. “Fine crystals” means crystal grains having an aspect ratio of 1 or more and 6 or less and a grain size of less than 0.1 μm. The aspect ratio is calculated as the ratio of the length of the longest diameter (long side) to the diameter (short side) perpendicular to the crystal grain cross section, with the long side as the numerator and the short side as the denominator.
In addition, “the crystal grain size length ratio of fine crystal grains having a grain size of less than 0.1 μm” means that the grain size of a plurality of crystal grains is measured and the grain size relative to the sum of all the measured crystal grain lengths is The ratio of the sum of crystal grain lengths of less than 0.1 μm is indicated, and “the ratio of crystal grain length occupied by crystal grains having a grain size of 0.15 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 0.15 μm or less to the sum of all measured crystal grain lengths.
本発明の硬質被覆層の層構造について、以下に、詳細に説明する。
本発明では、逃げ面上の刃先から１００μｍ離れた位置までの範囲においては、硬質被覆層は、主として、平均粒径０．２〜１μｍの粒状結晶粒と平均粒径０．０８μｍ以下の微細結晶粒との混合組織として硬質被覆層を構成するが、粒径０．１μｍ未満の微細結晶粒の結晶粒径長割合が、混合組織中の１０％未満になると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し、一方、粒径０．１μｍ未満の微細結晶粒の結晶粒径長割合が混合組織中の５０％を超えると、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ことから、混合組織中に占める粒径０．１μｍ未満の微細結晶粒の結晶粒径長割合は、１０〜５０％とすることが必要である。
粒径０．１μｍ以上の粒状結晶粒の結晶粒径長割合は、５０〜９０％の割合で存在する必要がある。９０％を超える場合、圧縮応力の値が小さくなり硬さが小さくなりすぎて、硬質被覆層の耐摩耗性が低下し、一方、５０％未満である場合、圧縮応力の値が大きくなり硬さ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ことから、混合組織中に占める粒径０．１μｍ以上の粒状結晶粒の結晶粒径長割合は５０〜９０％とすることが必要である。
また、粒状結晶粒の平均粒径が１μｍを超える場合、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ため、粒状結晶粒の平均粒径の上限値を１μｍとすることが必要である。
The layer structure of the hard coating layer of the present invention will be described in detail below.
In the present invention, in the range from the cutting edge on the flank to a position 100 μm away, the hard coating layer is mainly composed of granular crystal grains having an average grain diameter of 0.2 to 1 μm and fine crystals having an average grain diameter of 0.08 μm or less. A hard coating layer is formed as a mixed structure with grains, but the compression formed in the hard coating layer when the crystal grain length ratio of fine crystal grains having a grain size of less than 0.1 μm is less than 10% in the mixed structure. Since the stress value becomes small, the wear resistance of the hard coating layer is lowered. On the other hand, if the crystal grain length ratio of fine crystal grains having a grain size of less than 0.1 μm exceeds 50% in the mixed structure, the hard coating layer Since the value of the compressive stress formed in the layer becomes too large and chipping is likely to occur at the time of cutting, the crystal grain size ratio of fine crystal grains having a grain size of less than 0.1 μm in the mixed structure is 10 to 50%.
The crystal grain length ratio of the granular crystal grains having a grain size of 0.1 μm or more needs to be present at a ratio of 50 to 90%. If it exceeds 90%, the compressive stress value becomes small and the hardness becomes too small, and the wear resistance of the hard coating layer decreases. On the other hand, if it is less than 50%, the compressive stress value becomes large and the hardness is low. Becomes too large and chipping is likely to occur at the time of cutting. Therefore, the crystal grain length ratio of the granular crystal grains having a grain size of 0.1 μm or more in the mixed structure needs to be 50 to 90%. is there.
In addition, when the average grain size of the granular crystal grains exceeds 1 μm, the value of the compressive stress formed in the hard coating layer is reduced, so that the wear resistance of the hard coating layer is reduced. It is necessary to set the upper limit of the diameter to 1 μm.
また、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は２０％以下であ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、０．１５μｍ以下の結晶粒の分布を上記のとおり定めたのは、刃先に被覆された硬質被覆層で十分な耐摩耗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あって、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、ステンレス鋼等の難削材の切削加工においてチッピングを発生しやすくなるという理由による。
なお、本発明では、逃げ面上の硬質被覆層の結晶粒径の測定、また、平均結晶粒径の算出は、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にて、観察する。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、及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結晶粒径となる位置とする。それぞれの領域において、逃げ面上刃先、及び逃げ面上にて刃先から５０μｍ離れた位置、及び刃先から１００μｍ離れた位置の３箇所、計９箇所にて幅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。ただし、逃げ面上の刃先の箇所においては、刃先から５μｍ離れた位置を中心として、刃先側５μｍ、刃先と逆側５μｍの幅１０μｍの範囲内で測定した。全９箇所の領域で、粒径が０．１μｍ以上の結晶粒の平均値を「粒状結晶粒の平均粒径」と定義する。また、粒径が０．１μｍ未満の結晶粒の平均値を「微細結晶粒の平均粒径」と定義する。
また、粒径が０．１μｍ未満の結晶粒が占める結晶粒径長割合の測定方法は、上記粒径を測定した界面３箇所、表面３箇所、及び中間領域３箇所にて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０．１μｍ未満の結晶粒径の和を「微細結晶粒が占める結晶粒径長割合」とした。
また、界面にて粒径が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、上記粒径を測定した界面３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「粒径０．１５μｍ以下の結晶粒が占める結晶粒径長割合」とした。
In addition, at the interface between the tool base and the hard coating layer, the crystal grain length ratio occupied by crystal grains having a grain size of 0.15 μm or less needs to be 20% or less.
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 distribution of the crystal grains of 0.15 μm or less was determined as described above in order to ensure sufficient wear resistance with the hard coating layer coated on the blade edge and to suppress the occurrence of chipping. If the crystal grain 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 performed in cutting difficult-to-cut materials such as stainless steel. It is because it becomes easy to generate.
In the present invention, the measurement of the crystal grain size of the hard coating layer on the flank and the calculation of the average crystal grain size were performed 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 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 A straight line is drawn in parallel with the tool base surface at the crystal grains present in the intermediate region between the hard coating layer surface and the tool base surface, and the distance between the crystal grain boundaries is defined as the grain size. The position where a straight line is drawn parallel to the surface of the tool base is the position where the longest crystal grain size is obtained in each crystal grain. In each region, the average of the flank upper cutting edge, and the crystal existing within a range of 10 μm in width at a total of nine positions, three positions on the flank face, 50 μm away from the cutting edge, and 100 μm away from the cutting edge. Measure crystal grain size. 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. However, at the position of the cutting edge on the flank, the measurement was performed within a range of 10 μm in width of 5 μm on the side of the cutting edge and 5 μm on the opposite side to the cutting edge, with a position 5 μm away from the cutting edge. The average value of crystal grains having a grain size of 0.1 μm or more in all nine regions is defined as “average grain diameter of granular crystal grains”. The average value of crystal grains having a grain size of less than 0.1 μm is defined as “average grain size of fine crystal grains”.
Moreover, the measuring method of the crystal grain size length ratio occupied by crystal grains having a grain size of less than 0.1 μm is the crystal grain size measured at the three interfaces, three surfaces, and three intermediate regions where the particle size was measured. All measured data of are used. The sum of crystal grain sizes with a grain size of less than 0.1 μm with respect to the sum of all measured crystal grain sizes was defined as “the ratio of crystal grain length occupied by fine crystal grains”.
Moreover, the measurement method of the crystal grain size length ratio occupied by crystal grains having a grain size of 0.15 μm or less at the interface uses all measurement data at the three interfaces where the grain size is measured. The sum of the crystal grain sizes with a grain size of 0.15 μm or less relative to the sum of the measured total crystal grain sizes was defined as “the ratio of the crystal grain length occupied by the crystal grains with a grain size of 0.15 μm or less”.
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、切れ刃先端のコーナー部クラック占有率β／αを０．３〜１．０とすることが好ましく、さらに、β／αが０．３〜０．９であることがより好ましい。
その理由は、次のとおりである。
工具基体表面に、アークイオンプレーティング装置（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ため、特に、切削開始初期のチッピング発生等による切削性能の低下を抑制することができる。
ただし、β／αが０．３未満である場合には、圧縮残留応力の集中抑制効果を期待することはできないので、β／αは０．３以上と定めた。
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ので、β／αの値は、０．３〜０．９であることが好ましい。
Further, in the present invention, as shown in FIG. 4, the cutting edge angle of the coated tool is α degrees, and the occupation angle of the continuous cracks formed in the hard coating layer within the angle range of the α degrees is β degrees. In this case, the corner crack occupation ratio β / α at the tip of the cutting edge is preferably 0.3 to 1.0, and more preferably β / α is 0.3 to 0.9.
The reason is as follows.
When a hard coating layer is formed on the surface of a tool base using an arc ion plating apparatus (AIP apparatus), compressive residual stress is accumulated in the layer, and particularly in a layer having a large crystal grain size, Compressive residual stress concentrates on the grain boundary and tends to be the origin 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. A reduction in cutting performance can be suppressed.
However, when β / α is less than 0.3, the effect of suppressing the concentration of compressive residual stress cannot be expected, so β / α is set to 0.3 or more.
From the viewpoint of the effect of suppressing the concentration of compressive residual stress, it is not necessary 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 1. The closer to 0, the easier the interface peeling at the hard coating layer / tool base interface occurs, so the value of β / α is preferably 0.3 to 0.9.
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。
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。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。
なお、本発明被覆工具は、（Ａｌ，Ｃｒ）Ｎ層からなる硬質被覆層は粒状結晶粒と微細結晶粒の混合組織を有し、微細結晶粒の結晶粒径長割合を１０〜５０％を占め、また、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％以下と定めることにより、自ずとクラック占有率β／αが０．３〜１となる。
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).
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. 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 the coated tool of the present invention, the hard coating layer composed of the (Al, Cr) N layer has a mixed structure of granular crystal grains and fine crystal grains, and the crystal grain length ratio of the fine crystal grains is 10 to 50%. In addition, at the interface from the cutting edge on the flank to a position 100 μm away, the crystal grain length ratio occupied by the crystal grains having a grain size of 0.15 μm or less is set to 20% or less, so β / α is 0.3 to 1.
（ｃ）硬質被覆層の蒸着形成
この発明の硬質被覆層は、図２（ａ）、（ｂ）に示すようなアークイオンプレーティング装置（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。
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（カソード電極）を設け、
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し、
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なる磁場を印加し、
ついで、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は、逃げ面の一部又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、本発明の層構造と圧縮残留応力を有する（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。
なお、上記の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又は永久磁石を設置する、あるいは、ＡＩＰ装置の内部、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。
(C) Vapor deposition of hard coating layer The hard coating layer of the present invention uses an arc ion plating apparatus (AIP apparatus) as shown in FIGS. While maintaining the temperature at C, the tool substrate is rotated and revolved in the AIP apparatus, and vapor deposition is performed while applying a predetermined magnetic field (integrated magnetic force is 45 to 100 mT x mm) between the center of the target surface and the tool substrate closest to the target. Can be formed.
For example, one of the AIP devices is provided with a cathode electrode made of a Ti electrode for substrate cleaning, and the other is provided with a target (cathode electrode) made of a 70 at% Al-30 at% Cr alloy,
First, a tool substrate made of tungsten carbide (WC) -based cemented carbide is cleaned and dried, mounted on a rotary table in an AIP apparatus, and 100 A between the Ti electrode and the anode electrode for cleaning the substrate in vacuum. An arc discharge 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 surface center of the Al—Cr alloy target to the tool base closest to the target is applied,
Next, nitrogen gas is introduced into the apparatus as a reaction gas to achieve an atmospheric pressure of 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 A 100 A arc discharge is generated between the alloy target (cathode electrode) and the anode electrode, and when the tool base is closest to the target, a part or all of the flank and the target surface are horizontal. By vapor deposition while supporting and rotating on the substrate, a hard coating layer composed of the (Al, Cr) N layer having the layer structure of the present invention and compressive residual stress can be formed by vapor deposition.
The magnetic field is applied between the Al—Cr alloy target and the tool base, for example, by installing an electromagnetic coil or permanent magnet as a magnetic field generation source around the cathode, or permanently in the center of the AIP apparatus. The magnetic field can be formed by any means such as disposing a magnet.
この発明の被覆工具は、（Ａｌ，Ｃｒ）Ｎ層からなる硬質被覆層を備え、しかも、逃げ面上の刃先から１００μｍ離れた位置までの範囲において、平均粒径０．２〜１μｍの粒状結晶粒と平均粒径０．０８μｍ以下の微細結晶粒との混合組織を有し、また、上記微細結晶粒の結晶粒径長割合は、上記混合組織中の１０〜５０％を占め、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は２０％以下と定めており、また、クラック占有率β／αが０．３〜１．０であることから、ステンレス鋼等の難削材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る。 The coated tool of the present invention includes a hard coated layer composed of an (Al, Cr) N layer, and further has a granular crystal having an average particle size of 0.2 to 1 μm in a range from the cutting edge on the flank to a position 100 μm away A mixed structure of grains and fine crystal grains having an average grain size of 0.08 μm or less, and the crystal grain length ratio of the fine crystal grains occupies 10 to 50% of the mixed structure, At the interface of the hard coating layer, the crystal grain length ratio of the crystal grains having a grain size of 0.15 μm or less is set to 20% or less, and the crack occupation ratio β / α is 0.3 to 1.0. Therefore, in cutting of difficult-to-cut materials such as stainless steel, it exhibits excellent chipping resistance and wear resistance, and excellent cutting performance over a long period of use.
つぎに、この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５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及び、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 5, and then 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 tool base (end mill) 1 to 3 made of a WC-based cemented carbide having a two-blade ball shape with a twist angle of 30 degrees, and the diameter of the cutting edge portion × length is 10 mm × 22 mm. Tool bases (end mills) 4 to 5 made of a WC-base cemented carbide having a square shape were manufactured.
（ａ）上記の工具基体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合金からなるターゲット（カソード電極）を配置し、
（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、もって工具基体表面をボンバード洗浄し、
（ｃ）ついで、上記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し、
（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、逃げ面の一部又は全部と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 described above is ultrasonically cleaned in acetone and dried, at a position spaced apart from the central axis on the rotary table of the AIP apparatus shown in FIG. 2 by a predetermined distance in the radial direction. Attached along the outer periphery, a Ti cathode electrode for bombard cleaning is arranged on one side of the AIP apparatus, and a target (cathode electrode) made of a 70 at% Al-30 at% Cr alloy is arranged 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. And an arc discharge is caused by flowing a current of 100 A between the Ti cathode electrode and the anode electrode, thereby bombarding the surface of the tool substrate,
(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,
(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. By vapor-depositing a hard coating layer comprising an (Al, Cr) N layer of the indicated composition and target average layer thickness,
Surface coated end mills 1 to 5 (hereinafter referred to as the present invention 1 to 5) as the coated tools of the present invention were produced.
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、上記実施例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、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、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 ( The surface-coated end mill 1 as a comparative-coated tool was changed under the same conditions as in Example 1 except that the conditions of d) were changed (that is, the tool substrate was maintained at a temperature of less than 370 ° C. or higher than 450 ° C.). To 5 (hereinafter referred to as Comparative Examples 1 to 5), respectively. Furthermore, the content ratio of Cr in the total amount of Al and Cr in the coating layer from Example 1 is out of the range of 0.2 to 0.5 (however, the atomic ratio), or the average layer thickness of the coating layer is 2 Surface-coated end mills 6 to 10 (hereinafter referred to as Comparative Examples 6 to 10) outside the range of 10 μm were manufactured.
上記で作製した本発明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、結晶粒径を測定し、微細結晶粒の平均粒径、粒状結晶粒の平均粒径、微細結晶粒の結晶粒径長割合、０．１５μｍ以下の結晶粒径長割合を算出するとともに、いずれもアスペクト比が１以上６以下の結晶粒であることを確認した。アスペクト比は、結晶粒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。
また、刃先から１００μｍ離れた位置までの範囲における硬質被覆層に占める微細結晶粒の結晶粒径長割合を測定したところ、微細結晶粒は、混合組織中の１０〜５０％を占めることを確認した。
さらに、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。
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、微細結晶粒の結晶粒径長割合は混合組織中の１０〜５０％の範囲外、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％以上であった。
表２、表３に、上記で測定・算出したそれぞれの値を示す。
About this invention 1-5 produced above, in the range from the cutting edge on the flank to a position 100 μm away, the average layer thickness and crystal grain size of the hard coating layer in the longitudinal section are measured, and the average grain size of the fine crystal grains Calculate the diameter, the average grain size of the granular crystal grains, the crystal grain size length ratio of the fine crystal grains, and the crystal grain size length ratio of 0.15 μm or less, all of which are crystal grains having an aspect ratio of 1 to 6 It was confirmed. The aspect ratio is calculated as the ratio of the length of the longest diameter (long side) to the diameter (short side) perpendicular to the crystal grain cross section, with the long side as the numerator and the short side as the denominator.
Moreover, when the crystal grain length ratio of the fine crystal grains in the hard coating layer in the range from the blade edge to 100 μm was measured, it was confirmed that the fine crystal grains accounted for 10 to 50% in the mixed structure. .
Furthermore, when the crystal grain length ratio of 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 cutting edge was measured, it was confirmed that it was 20% or less. did.
On the other hand, when Comparative Examples 1 to 10 were observed and measured in the same manner as in the present invention, the average thickness of the coating layer was fine except for the surface-coated end mill (Comparative Examples 9 and 10) outside the range of 2 to 10 μm. The crystal grain length ratio of the crystal grains is outside the range of 10 to 50% in the mixed structure, or the crystal grain length ratio of 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 is measured. As a result, it was 20% or more.
Tables 2 and 3 show the values measured and calculated above.
なお、上記平均層厚の測定法、結晶粒径の測定法、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。
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ＳＥＭにて、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にて任意の５箇所とする。
硬質被覆層表面から深さ０．５μｍの領域にて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の領域にて形成されている結晶粒、及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、逃げ面上刃先、及び逃げ面上にて刃先から５０μｍ離れた位置、及び刃先から１００μｍ離れた位置の３箇所、計９箇所にて幅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。ただし、逃げ面上の刃先の箇所においては、刃先から５μｍ離れた位置を中心として、刃先側５μｍ、刃先と逆側５μｍの幅１０μｍの範囲内で測定した。全９箇所の領域で、粒径が０．１μｍ以上の結晶粒の平均値を「粒状結晶粒の平均粒径」と定義する。また、粒径が０．１μｍ未満の結晶粒の平均値を「微細結晶粒の平均粒径」と定義する。
また、粒径が０．１μｍ未満の結晶粒が占める結晶粒径長割合の測定方法は、上記粒径を測定した界面３箇所、表面３箇所、及び中間領域３箇所にて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０．１μｍ未満の結晶粒径の和を「粒径０．１μｍ未満の結晶粒が占める結晶粒径長割合」とした。
また、界面にて粒径が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、上記粒径を測定した界面３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「粒径０．１５μｍ以下の結晶粒が占める結晶粒径長割合」とした。
More specifically, the measurement method of the average layer thickness, the measurement method of the crystal grain size, and the measurement method of the crystal grain length ratio are as follows.
After polishing the cross section of the flank, including the corner portion at the tip of the coated tool, the cross section is observed with an 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. It should be noted that the measurement points are any five locations from the cutting edge on the flank to the position 100 μm away from the cutting edge on the flank.
Crystal grains formed in a region having a depth of 0.5 μm from the surface of the hard coating layer, and crystal grains formed in a region having a thickness of 0.5 μm from the interface between the tool substrate and the hard coating layer in the hard coating layer A straight line is drawn in parallel with the tool base surface in the crystal grains existing in the intermediate region between the hard coating layer surface and the tool base surface, and the distance between the crystal grain boundaries is defined as the grain size. In each region, the average of the flank upper cutting edge, and the crystal existing within a range of 10 μm in width at a total of nine positions, three positions on the flank face, 50 μm away from the cutting edge, and 100 μm away from the cutting edge. Measure crystal grain size. 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. However, at the position of the cutting edge on the flank, the measurement was performed within a range of 10 μm in width of 5 μm on the side of the cutting edge and 5 μm on the opposite side to the cutting edge, with a position 5 μm away from the cutting edge. The average value of crystal grains having a grain size of 0.1 μm or more in all nine regions is defined as “average grain diameter of granular crystal grains”. The average value of crystal grains having a grain size of less than 0.1 μm is defined as “average grain size of fine crystal grains”.
Moreover, the measuring method of the crystal grain size length ratio occupied by crystal grains having a grain size of less than 0.1 μm is the crystal grain size measured at the three interfaces, three surfaces, and three intermediate regions where the particle size was measured. All measured data of are used. The sum of the crystal grain sizes having a grain size of less than 0.1 μm with respect to the sum of the measured total crystal grain sizes was defined as “the ratio of crystal grain length occupied by crystal grains having a grain size of less than 0.1 μm”.
Moreover, the measurement method of the crystal grain size length ratio occupied by crystal grains having a grain size of 0.15 μm or less at the interface uses all measurement data at the three interfaces where the grain size is measured. The sum of the crystal grain sizes with a grain size of 0.15 μm or less relative to the sum of the measured total crystal grain sizes was defined as “the ratio of the crystal grain length occupied by the crystal grains with a grain size of 0.15 μm or less”.
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、上記刃先角度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 cutting 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、上記本発明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・ＳＵＳ３０４の板材、
回転速度： １６０００ 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）でのステンレス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・ＳＵＳ３０４の板材、
回転速度： ３２００ 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）のステンレス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 end mills of the present invention 1-5 and Comparative Examples 1-10,
About this invention 1-3 and Comparative Examples 1-3, 6-8,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Rotational speed: 16000 min. -1 ,
Lateral cut: 2.0 mm,
Longitudinal cut: 0.3 mm,
Feed rate (per blade): 0.06 mm / tooth,
Cutting length: 340m,
A stainless steel groove cutting test was conducted under the above conditions (referred to as cutting condition A),
Moreover, about this invention 4, 5 and comparative examples 4, 5, 9, and 10,
Work material-planar dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Rotational speed: 3200 min. -1 ,
Lateral cut: 10 mm,
Longitudinal cut: 1 mm,
Feed rate (per tooth): 0.07 mm / tooth,
Cutting length: 90m,
Conducting a groove cutting test of stainless 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１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 are blended into the composition shown in Table 1, wet mixed by a ball mill for 72 hours, dried, and then pressed into a green compact at a pressure of 100 MPa. 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、上記実施例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 above. By forming a hard coating layer composed of an (Al, Cr) N layer having the composition shown in Table 6 and a target average layer thickness,
The coated carbide inserts of the present invention (hereinafter referred to as the present inventions 6 to 10) as the coated tools of the present invention were produced.
比較例２：
比較の目的で、上記の工具基体（インサート）６−１０に対して、上記比較例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 tool base (insert) 6-10 is composed of an (Al, Cr) N layer having the composition and the target average layer thickness shown in Table 7 under the same conditions as in Comparative Example 1. By forming a hard coating layer,
Comparative example coated carbide inserts (hereinafter referred to as Comparative Examples 11 to 20) as comparative example coated tools were produced, respectively.
上記で作製した本発明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の縦断面の硬質被覆層の平均層厚、結晶粒径を測定し、微細結晶粒の平均粒径、粒状結晶粒の平均粒径、微細結晶粒の結晶粒径長割合、０．１５μｍ以下の結晶粒径長割合を算出するとともに、いずれもアスペクト比が１以上６以下の結晶粒であることを確認した。アスペクト比は、結晶粒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。
また、硬質被覆層に占める微細結晶粒の結晶粒径長割合を測定したところ、微細結晶粒の結晶粒径長割合は、混合組織中の１０〜５０％を占めることを確認した。
さらに、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。
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、微細結晶粒の結晶粒径長割合は混合組織中の１０〜５０％の範囲外、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％以上であった。
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、上記で測定・算出したそれぞれの値を示す。
About this invention 6-10 produced above, the average layer thickness and crystal grain diameter of the hard coating layer of the longitudinal section in the range to the position away from the cutting edge on the flank 100 μm are measured, and the average grain diameter of the fine crystal grains The average grain size of the granular crystal grains, the crystal grain size length ratio of the fine crystal grains, and the crystal grain size length ratio of 0.15 μm or less are calculated, and all are crystal grains having an aspect ratio of 1 to 6 confirmed. The aspect ratio is calculated as the ratio of the length of the longest diameter (long side) to the diameter (short side) perpendicular to the crystal grain cross section, with the long side as the numerator and the short side as the denominator.
Moreover, when the crystal grain length ratio of the fine crystal grains in the hard coating layer was measured, it was confirmed that the crystal grain length ratio of the fine crystal grains occupied 10 to 50% in the mixed structure.
Furthermore, when the crystal grain length ratio 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 was measured, it was also confirmed that it was 20% or less.
On the other hand, when Comparative Examples 11 to 20 were observed and measured in the same manner as in the present invention, the average thickness of the coating layer was fine except for the surface-coated inserts (Comparative Examples 19 and 20) outside the range of 2 to 10 μm. The crystal grain length ratio of the crystal grains is outside the range of 10 to 50% in the mixed structure, or the crystal grain length ratio of 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 is measured. As a result, it was 20% or more.
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 above.
つぎに、上記本発明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：１００ｍ／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 inventions 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: 100 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、（Ａｌ，Ｃｒ）Ｎ層からなる硬質被覆層が、逃げ面上の刃先から１００μｍ離れた位置までの範囲において、平均粒径０．２〜１μｍの粒状結晶粒と平均粒径０．０８μｍ以下の微細結晶粒との混合組織を有し、また、微細結晶粒の結晶粒径長割合は混合組織中の１０〜５０％を占め、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は２０％以下となっていることから、また、クラック占有率が０．３〜１．０となっていることから、ステンレス鋼等の難削材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 an average particle size of 0. 0 in the range where the hard coating layer composed of the (Al, Cr) N layer is located 100 μm away from the cutting edge on the flank. Having a mixed structure of 2-1 μm granular crystal grains and fine crystal grains having an average grain size of 0.08 μm or less, and the crystal grain length ratio of the fine crystal grains accounts for 10 to 50% of the mixed structure; At the interface between the tool base and the hard coating layer, the crystal grain length ratio of the crystal grains having a grain size of 0.15 μm or less is 20% or less, and the crack occupancy is 0.3 to 1. Since it is 0, it exhibits excellent chipping resistance and wear resistance in cutting of difficult-to-cut materials such as stainless steel.
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.
上述のように、この発明の被覆工具は、ステンレス鋼等の難削材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ＦＡ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 difficult-to-cut materials such as stainless steel. It can fully satisfy the labor-saving and energy-saving of cutting and cost reduction.
Claims (2)
（ａ）硬質被覆層は、ＡｌとＣｒの複合窒化物層からなり、かつ、該層においてＡｌとＣｒの合量に占めるＣｒの含有割合は０．２〜０．５（但し、原子比）であり、
（ｂ）上記表面被覆切削工具の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、硬質被覆層は平均粒径０．２〜１μｍの粒状結晶粒と平均粒径０．０８μｍ以下の微細結晶粒との混合組織を有し、また、粒径０．１μｍ未満の微細結晶粒の結晶粒径長割合は、上記混合組織中の１０〜５０％を占め、
（ｃ）上記表面被覆切削工具の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は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 formed on the surface of a tool base composed of a tungsten carbide-based cemented carbide,
(A) The hard coating layer is composed of a composite nitride layer of Al and Cr, and the content ratio of Cr in the total amount of Al and Cr in the layer is 0.2 to 0.5 (however, atomic ratio) And
(B) In the range from the cutting edge on the flank of the surface-coated cutting tool to a position 100 μm away, the hard coating layer has granular crystal grains having an average grain size of 0.2 to 1 μm and an average grain size of 0.08 μm or less. It has a mixed structure with fine crystal grains, and the crystal grain length ratio of the fine crystal grains with a grain size of less than 0.1 μm accounts for 10 to 50% of the mixed structure,
(C) At the interface between the tool base and the hard coating layer in the range from the cutting edge on the flank of the surface-coated cutting tool to a position 100 μm away, the crystal grain size ratio occupied by crystal grains having a grain size of 0.15 μm or less Is a surface-coated cutting tool characterized by being 20% or less.
When the 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 the α degrees is β degrees, The surface-coated cutting tool according to claim 1, wherein a crack occupancy ratio β / α is 0.3 to 1.0.
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| JP2003165003A (en) * | 2001-11-28 | 2003-06-10 | Hitachi Tool Engineering Ltd | Hard film coated member |
| JP5321975B2 (en) * | 2009-09-24 | 2013-10-23 | 住友電工ハードメタル株式会社 | Surface coated cutting tool |
| JP5515806B2 (en) * | 2010-02-03 | 2014-06-11 | 三菱マテリアル株式会社 | Surface-coated cutting tool with excellent fracture resistance due to hard coating layer |
| US8715838B2 (en) * | 2010-11-10 | 2014-05-06 | Sumitomo Electric Hardmetal Corp. | Surface-coated cutting tool |
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2012
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