JP6421934B2 - Surface coated cutting tool with excellent abnormal damage resistance and wear resistance - Google Patents
Surface coated cutting tool with excellent abnormal damage resistance and wear resistance Download PDFInfo
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Description
本発明は、硬質被覆層がすぐれた耐異常損傷性と耐摩耗性を備え、焼き入れ鋼などの高硬度鋼の高速切削加工に用いた場合においても、チッピング、欠損が発生しにくく、長期に亘ってすぐれた切削性能を示す表面被覆切削工具（以下、被覆工具という）に関する。 The present invention has excellent abnormal damage resistance and abrasion resistance with a hard coating layer, and even when used for high-speed cutting of hardened steel such as hardened steel, chipping and chipping are less likely to occur, The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits excellent cutting performance.
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、被削材の穴あけ切削加工などに用いられるドリルやミニチュアドリル、さらに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、またインサートを着脱自在に取り付けて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などが知られている。 In general, coated tools are used for turning and planing of work materials such as various types of steel and cast iron, inserts that can be used detachably attached to the tip of a cutting tool, drilling processing of work materials, etc. There are drills, miniature drills, solid type end mills used for chamfering, grooving, shoulder processing, etc. of the work material, etc. Also, inserts are detachably attached and cutting is performed in the same way as solid type end mills An insert type end mill is known.
本発明は、立方晶窒化硼素（以下、ｃＢＮで示す）を主成分として、これを超高圧、高温下にて焼結成形してなるｃＢＮ焼結体切削工具に関し、特に、合金鋼、軸受鋼等の焼入れ鋼からなる高硬度鋼の高速連続切削加工、高速断続切削加工においても、チッピングや欠損の発生を抑制し得るとともに、すぐれた切削性能を長期の使用に亘って維持し得るｃＢＮ焼結体切削工具に関するものである。 The present invention relates to a cBN sintered body cutting tool comprising cubic boron nitride (hereinafter referred to as cBN) as a main component and sintered and formed at ultrahigh pressure and high temperature, and in particular, alloy steel and bearing steel. CBN sintering that can suppress the occurrence of chipping and chipping and maintain excellent cutting performance over a long period of use in high-speed continuous cutting and high-speed intermittent cutting of hardened steel such as hardened steel The present invention relates to a body cutting tool.
従来、高硬度鋼の切削工具としては、ｃＢＮ焼結体を工具基体としたｃＢＮ焼結体切削工具等が知られており、工具寿命の向上を目的として種々の提案がなされている。
例えば、特許文献１には、超硬合金、サーメット、ｃＢＮ焼結体等の工具基体上に被膜を形成した被覆工具において、被膜の厚み方向に圧縮応力の強度分布を形成し、該強度分布は、上記被膜の表面において最小の圧縮応力を形成するとともに、上記被膜の表面から、上記被膜の表面と上記被膜の底面との間に位置する中間点まで圧縮応力を連続的に増加させ、中間点において極大点を形成し、中間点から上記被膜の底面まで圧縮応力を一定の値とすることにより、切削工具の靭性と耐摩耗性とを両立させ、特に、耐チッピング性を向上させた被覆工具が提案されている。
また、特許文献２には、ｃＢＮ焼結体からなる工具基体表面に、硬質被覆層を蒸着形成した被覆工具であって、工具基体と硬質被覆層との界面における工具基体及び硬質被覆層の残留応力値が、それぞれが−２ＧＰａ以下の残留応力であり、かつ、両者の残留応力の差が０．５ＧＰａ以下であり、好ましくは、硬質被覆層中の残留応力の値が、硬質被覆層の表面に向かって絶対値で次第に小さくなる残留応力分布を形成するように硬質被覆層の残留応力差をコントロールすることにより、長時間断続切削を行った場合でも、優れた耐チッピング性を発揮する被覆工具が提案されている。
Conventionally, cBN sintered body cutting tools using a cBN sintered body as a tool base are known as cutting tools for high hardness steel, and various proposals have been made for the purpose of improving the tool life.
For example, in Patent Document 1, in a coated tool in which a coating is formed on a tool base such as cemented carbide, cermet, cBN sintered body, a strength distribution of compressive stress is formed in the thickness direction of the coating, and the strength distribution is Forming a minimum compressive stress on the surface of the coating, and continuously increasing the compressive stress from the surface of the coating to an intermediate point located between the surface of the coating and the bottom surface of the coating. In this case, it is possible to achieve both the toughness and wear resistance of the cutting tool, and in particular to improve the chipping resistance, by forming a maximum point at the intermediate point and making the compressive stress constant from the intermediate point to the bottom surface of the coating. Has been proposed.
Patent Document 2 discloses a coated tool in which a hard coating layer is vapor-deposited on the surface of a tool substrate made of a cBN sintered body, and the tool substrate and the hard coating layer remain at the interface between the tool substrate and the hard coating layer. Each of the stress values is a residual stress of −2 GPa or less, and the difference between the residual stresses is 0.5 GPa or less. Preferably, the value of the residual stress in the hard coating layer is the surface of the hard coating layer. A tool that exhibits excellent chipping resistance even after long-term intermittent cutting by controlling the residual stress difference of the hard coating layer so as to form a residual stress distribution that gradually decreases in absolute value toward Has been proposed.
上記特許文献１に記載される従来被覆工具は、炭素鋼の連続切削、断続切削において、すぐれた耐欠損性と耐摩耗性を発揮するものの、これを、高硬度鋼の高速切削加工に用いた場合には、耐欠損性と耐摩耗性のいずれも十分であるとはいえない。
また、上記特許文献２に記載される従来被覆工具においては、軸受鋼、クロム鋼の高速断続切削加工において、すぐれた耐欠損性を示すものの、耐摩耗性についてはやはり十分であるとはいえない。
いずれにしても、従来の被覆工具は、高硬度鋼の高速連続切削加工、高速断続切削加工においては、チッピング、欠損などの異常損傷の発生を低減すると同時に、すぐれた耐摩耗性を確保することはできず、そのため、工具寿命が短命であるという問題点があった。
Although the conventional coated tool described in Patent Document 1 exhibits excellent fracture resistance and wear resistance in continuous cutting and intermittent cutting of carbon steel, it was used for high-speed cutting of hardened steel. In some cases, neither fracture resistance nor wear resistance is sufficient.
Further, the conventional coated tool described in Patent Document 2 shows excellent fracture resistance in high-speed intermittent cutting of bearing steel and chromium steel, but it cannot be said that the wear resistance is sufficient. .
In any case, conventional coated tools can reduce the occurrence of abnormal damage such as chipping and chipping and ensure excellent wear resistance in high-speed continuous cutting and high-speed intermittent cutting of high-hardness steel. Therefore, there is a problem that the tool life is short-lived.
本発明者らは、前記課題を解決するため、ｃＢＮ焼結体からなる工具基体上に被覆する硬質被覆層の残留応力に着目し、鋭意研究したところ、次のような知見を得た。 In order to solve the above-mentioned problems, the present inventors paid attention to the residual stress of the hard coating layer coated on the tool substrate made of the cBN sintered body and conducted earnest research, and obtained the following knowledge.
まず、本発明者らは、ｃＢＮ焼結体を、ｃＢＮ粒子とＴｉの窒化物、炭化物、炭窒化物、硼化物およびＡｌの窒化物、酸化物からなる群から選ばれた少なくとも１種以上の粒子と不可避不純物とを含む結合相とから構成し、これをｃＢＮ焼結体からなる工具基体（以下、「ｃＢＮ基体」という）とし、この上に、下部層と上部層の２層構造からなる硬質被覆層を蒸着形成して表面被覆切削工具を作製した。
そして、硬質被覆層の下部層はＴｉＡｌＮ層とし、また、上部層はＴｉＡｌＳｉＮ層とした。
ＴｉＡｌＮ層は、その構成成分であるＴｉ成分によってすぐれた強度と靭性を確保することができ、Ａｌは高温硬さと耐熱性を向上させ、ＡｌとＴｉが共存含有した状態でさらに高温耐酸化性を向上させる作用があり、また、ＴｉＡｌＳｉＮ層は、ＴｉＡｌＮ層にＳｉ成分をさらに含有させることで、一層耐熱性が向上する。
First, the present inventors set the cBN sintered body to at least one selected from the group consisting of cBN particles and Ti nitride, carbide, carbonitride, boride, Al nitride, and oxide. It is composed of a binder phase containing particles and inevitable impurities, and this is used as a tool base made of a cBN sintered body (hereinafter referred to as “cBN base”), and has a two-layer structure of a lower layer and an upper layer thereon. A hard coating layer was formed by vapor deposition to prepare a surface-coated cutting tool.
The lower layer of the hard coating layer was a TiAlN layer, and the upper layer was a TiAlSiN layer.
The TiAlN layer can ensure excellent strength and toughness by the Ti component which is a constituent component thereof, and Al improves high temperature hardness and heat resistance, and further has high temperature oxidation resistance in a state where Al and Ti coexist. The TiAlSiN layer has an effect of improving, and the heat resistance is further improved by further adding a Si component to the TiAlN layer.
本発明者らは、上記ＴｉＡｌＮ層からなる下部層、ＴｉＡｌＳｉＮ層からなる上部層を、物理蒸着装置の一種であるアークイオンプレーティング装置（「ＡＩＰ装置」という）により蒸着形成するにあたり、その蒸着条件である雰囲気ガスの圧力および工具基体に印加する直流バイアス電圧を制御することによって、硬質被覆層に所望の残留応力を付与せしめることができることを見出したのである。 The inventors of the present invention, when forming the lower layer composed of the TiAlN layer and the upper layer composed of the TiAlSiN layer by an arc ion plating apparatus (referred to as “AIP apparatus”) which is a kind of physical vapor deposition apparatus, It has been found that the desired residual stress can be imparted to the hard coating layer by controlling the atmospheric gas pressure and the DC bias voltage applied to the tool substrate.
そして、硬質被覆層の下部層及び上部層に、所定の残留応力を付与せしめることによって、下部層とｃＢＮ基体との界面に発生する界面クラックの進展を抑制し得るとともに、切削加工時に、上部層の表面で発生したクラックが、上部層の内部に進展することを抑制することができるため、高硬度鋼の高速切削加工に供した場合であっても、チッピング、欠損等の異常損傷の発生を防止できることを見出したのである。 And by giving predetermined | prescribed residual stress to the lower layer and upper layer of a hard coating layer, while progressing of the interface crack which generate | occur | produces in the interface of a lower layer and a cBN base | substrate can be suppressed, at the time of a cutting process, an upper layer It is possible to suppress the cracks generated on the surface of the steel from progressing into the upper layer, so that even when subjected to high-speed cutting of high-hardness steel, abnormal damage such as chipping and chipping occurs. They found that it can be prevented.
さらに、本発明者らは、硬質被覆層全体の残留応力と硬質被覆層の下部層の残留応力との差を制御することで、下部層と上部層間での破壊発生を防止し得ることできるため、より一層、耐異常損傷性を高め得ることを見出したのである。 Furthermore, the present inventors can prevent the occurrence of breakage between the lower layer and the upper layer by controlling the difference between the residual stress of the entire hard coating layer and the residual stress of the lower layer of the hard coating layer. They have found that the abnormal damage resistance can be further improved.
本発明は、上記知見に基づいてなされたものであって、
「（１） 切削に使用する刃先が少なくとも立方晶窒化硼素焼結体からなる工具基体上に硬質被覆層を蒸着形成した表面被覆切削工具であって、
前記立方晶窒化硼素焼結体は、立方晶窒化硼素粒子と、Ｔｉの窒化物、炭化物、炭窒化物、硼化物およびＡｌの窒化物、酸化物からなる群から選ばれた少なくとも１種以上の粒子と不可避不純物とを含む結合相とからなり、
前記硬質被覆層は、工具基体直上の少なくとも下部層Ａとその上に形成された上部層Ｂとからなるとともに平均総層厚が１．５〜４．０μｍであり、
前記下部層Ａは、
組成式：Ｔｉ１−ａＡｌａＮ（但し、ａは原子比で０．３≦ａ≦０．７）
を満足する成分系からなり、
前記上部層Ｂは、
組成式：Ｔｉ１−ｘ―ｙＡｌｘＳｉｙＮ（但し、ｘ、ｙは原子比で０．３≦ｘ≦０．７、０．０１≦ｙ≦０．１）
を満足する成分系からなり、
前記表面被覆切削工具の逃げ面の下部層Ａの残留応力をσＡ（ＧＰａ）、前記硬質被覆層全体を総括した残留応力をσＴ（ＧＰａ）としたとき、
σＡ＜σＴ、
−７．０≦σＡ≦−１．０、
−４．０≦σＴ≦−０．５、
｜σＡ−σＴ｜＜４．０
の条件をすべて満たすことを特徴とする表面被覆切削工具。
（２）下部層Ａの平均層厚をｔＡ、上部層Ｂの平均層厚をｔＢとしたとき、
４≦ｔＢ／ｔＡ≦９
であり、下部層Ａの結晶粒の平均粒径が０．１μｍ以下であることを特徴とする前記（１）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 findings,
“(1) A surface-coated cutting tool in which a hard coating layer is vapor-deposited on a tool substrate whose cutting edge used for cutting is made of at least a cubic boron nitride sintered body,
The cubic boron nitride sintered body includes at least one selected from the group consisting of cubic boron nitride particles, Ti nitride, carbide, carbonitride, boride, Al nitride, and oxide. Consisting of a binder phase containing particles and inevitable impurities,
The hard coating layer comprises at least a lower layer A immediately above the tool base and an upper layer B formed thereon, and an average total layer thickness is 1.5 to 4.0 μm,
The lower layer A includes
Composition formula: Ti 1-a Al a N (where a is an atomic ratio of 0.3 ≦ a ≦ 0.7)
Consisting of ingredients that satisfy
The upper layer B is
Composition formula: Ti 1-xy Al x Si y N (where x and y are atomic ratios 0.3 ≦ x ≦ 0.7, 0.01 ≦ y ≦ 0.1)
Consisting of ingredients that satisfy
When the residual stress of the lower layer A on the flank of the surface-coated cutting tool is σ A (GPa), and the residual stress that summarizes the entire hard coating layer is σ T (GPa),
σ A <σ T ,
−7.0 ≦ σ A ≦ −1.0,
−4.0 ≦ σ T ≦ −0.5,
| Σ A −σ T | <4.0
A surface-coated cutting tool characterized by satisfying all of the above conditions.
(2) When the average layer thickness of the lower layer A is t A and the average layer thickness of the upper layer B is t B ,
4 ≦ t B / t A ≦ 9
The surface-coated cutting tool according to (1) above, wherein the average grain size of the crystal grains of the lower layer A is 0.1 μm or less. "
It has the characteristics.
本発明について、以下に詳細に説明する。 The present invention will be described in detail below.
焼結体中のｃＢＮ粒子の平均粒径：
ｃＢＮ焼結体中に、微細で硬質なｃＢＮ粒子が分散していることにより、工具使用中に工具基体表面のｃＢＮ粒子が脱落して生じる刃先の凹凸形状を起点とするチッピングの発生を抑制することができる。その理由は、たとえ、工具基体表面のｃＢＮ粒子が脱落したとしても、その粒子が所定の粒径以下の微細粒子であるためチッピングを誘発するような大きな凹凸形状とならないためである。
また、焼結体中の微細ｃＢＮ粒子が、工具使用中に刃先に加わる応力により生じるｃＢＮ粒子と結合相との界面から進展するクラック、あるいはｃＢＮ粒子が割れて進展するクラックの伝搬を分散・緩消する役割を担うため、被覆工具の耐欠損性向上に寄与する。
しかしながら、ｃＢＮ粒子の平均粒径が０．５μｍ未満になると、微細すぎて硬質粒子としてのｃＢＮ粒子の機能が十分に発揮できない。一方、４．０μｍを超えると、本発明における硬質被覆層の層厚と比べてかなり大きな粒子となるため、工具基体表面に露出するｃＢＮ粒子によって形成される凹凸形状が大きくなり過ぎ、チッピング、欠損発生の原因となる。
したがって、ｃＢＮ粒子の平均粒径は、０．５〜４．０μｍとすることが望ましい。
Average particle size of cBN particles in the sintered body:
By dispersing fine and hard cBN particles in the cBN sintered body, the occurrence of chipping starting from the uneven shape of the cutting edge caused by cBN particles falling off the surface of the tool base during use of the tool is suppressed. be able to. The reason is that even if the cBN particles on the surface of the tool base fall off, the particles are fine particles having a predetermined particle size or less, and thus do not have a large uneven shape that induces chipping.
In addition, the fine cBN particles in the sintered body disperse / relieve the propagation of cracks that develop from the interface between the cBN particles and the binder phase caused by the stress applied to the blade edge during tool use, or the cracks that propagate when the cBN particles break up. Since it plays a role of erasing, it contributes to improving the fracture resistance of the coated tool.
However, when the average particle size of the cBN particles is less than 0.5 μm, the function of the cBN particles as the hard particles cannot be sufficiently exhibited because the particles are too fine. On the other hand, if the thickness exceeds 4.0 μm, the particles are considerably larger than the thickness of the hard coating layer in the present invention, so that the uneven shape formed by the cBN particles exposed on the tool base surface becomes too large, and chipping and defects Causes the occurrence.
Therefore, it is desirable that the average particle size of the cBN particles be 0.5 to 4.0 μm.
ここで、ｃＢＮ粒子の平均粒径は、作製したｃＢＮ焼結体の断面組織を走査型電子顕微鏡（Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｙ：ＳＥＭ）にて観察して得られた二次電子画像内のｃＢＮ粒子の部分を画像処理にて抜き出し、画像解析によって各ｃＢＮ粒子の最大長を求め、それを各ｃＢＮ粒子の直径とし、１画像におけるｃＢＮ粒子の直径の平均値を求め、少なくとも３画像について求めた平均値の平均を、上記でいうｃＢＮの平均粒径［μｍ］とした。画像処理に用いる観察領域は予備観察を行うことによって定めることができるが、ｃＢＮ粒子の平均粒径が０．５〜４．０μｍであることをかんがみ、１５μｍ×１５μｍ程度の視野領域とすることが望ましい。 Here, the average particle size of the cBN particles is the portion of the cBN particles in the secondary electron image obtained by observing the cross-sectional structure of the produced cBN sintered body with a scanning electron microscope (SEM). Is extracted by image processing, the maximum length of each cBN particle is obtained by image analysis, and the diameter of each cBN particle is used as an average value of the diameters of cBN particles in one image, and the average value obtained for at least three images is obtained. The average was the average particle size [μm] of cBN referred to above. The observation area used for image processing can be determined by performing preliminary observation. However, considering that the average particle size of cBN particles is 0.5 to 4.0 μm, the viewing area may be about 15 μm × 15 μm. desirable.
ｃＢＮ焼結体中のｃＢＮ粒子の体積割合：
ｃＢＮ焼結体に占めるｃＢＮ粒子の含有割合が４０体積％未満では、焼結体中に硬質物質が少なく、ｃＢＮ焼結体の硬度が低下するため、耐摩耗性が低下する。一方、７０体積％を超えると、結合相が不足するため、焼結体中にクラックの起点となる空隙が生成し、耐欠損性が低下する。そのため、本発明が奏する効果をより一層発揮するためには、ｃＢＮ焼結体に占めるｃＢＮ粒子の含有割合は、４０〜７０体積％の範囲とすることが好ましい。
ここで、ｃＢＮ焼結体に占めるｃＢＮ粒子の含有割合（体積％）の測定方法は、ｃＢＮ焼結体の断面組織をＳＥＭによって観察して得られた二次電子画像内のｃＢＮ粒子の部分を画像処理によって抜き出し、画像解析によって観察領域におけるｃＢＮ焼結体の全体の面積に対するｃＢＮ粒子が占める面積を算出し、少なくとも３画像を処理し求めた値の平均値をｃＢＮ粒子の含有割合（体積％）とした。画像処理に用いる観察領域は、ｃＢＮ粒子の平均粒径が０．５〜４．０μｍであることをかんがみ、１５μｍ×１５μｍ程度の視野領域とすることが望ましい。
Volume ratio of cBN particles in the cBN sintered body:
When the content ratio of the cBN particles in the cBN sintered body is less than 40% by volume, the hard body is less in the sintered body and the hardness of the cBN sintered body is lowered, so that the wear resistance is lowered. On the other hand, if it exceeds 70% by volume, since the binder phase is insufficient, voids serving as starting points of cracks are generated in the sintered body, and the fracture resistance is lowered. Therefore, in order to further exhibit the effect exhibited by the present invention, the content ratio of the cBN particles in the cBN sintered body is preferably in the range of 40 to 70% by volume.
Here, the measurement method of the content ratio (volume%) of the cBN particles in the cBN sintered body is that the cBN particle portion in the secondary electron image obtained by observing the cross-sectional structure of the cBN sintered body with the SEM is used. The area occupied by the cBN particles with respect to the entire area of the cBN sintered body in the observation region is calculated by image processing, and the average value of the values obtained by processing at least three images is calculated as the content ratio (volume%) of the cBN particles. ). The observation area used for image processing is preferably a visual field area of about 15 μm × 15 μm, considering that the average particle size of cBN particles is 0.5 to 4.0 μm.
結合相を構成する成分粒子：
本発明におけるｃＢＮ焼結体中における主たる硬質成分は、前記平均粒径、体積割合のｃＢＮ粒子であるが、結合相形成成分粒子としては、既によく知られている、Ｔｉの窒化物、炭化物、炭窒化物、硼化物およびＡｌの窒化物、酸化物からなる群から選ばれた少なくとも１種以上の粒子を用いることができる。
Component particles constituting the binder phase:
The main hard component in the cBN sintered body in the present invention is the average particle size and volume proportion of cBN particles, but as the binder phase forming component particles, Ti nitride, carbide, At least one kind of particles selected from the group consisting of carbonitrides, borides, Al nitrides, and oxides can be used.
硬質被覆層の平均総層厚：
図１に示すように、本発明の硬質被覆層は、工具基体直上の少なくともＴｉ１−ａＡｌａＮの成分系からなる下部層Ａと、その上に形成されたＴｉ１−ｘ―ｙＡｌｘＳｉｙＮの成分系からなる上部層Ｂとからなる積層構造を有している。
この硬質被覆層は、下部層ＡであるＴｉＡｌＮ層に含まれるＴｉ成分によってすぐれた強度と靭性を確保し、Ａｌが高温硬さと耐熱性を向上させると共にＡｌとＴｉが共存含有した状態でさらに高温耐酸化性を向上させる作用があるとともに岩塩型結晶構造を有するため、高硬度であり工具基体上に形成することで耐摩耗性を向上させることができる。
また、上部層ＢであるＴｉＡｌＳｉＮ層は、前記ＴｉＡｌＮ層にＳｉ成分を含有させることで、一層耐熱性が向上し、酸化開始温度が高くて高温耐酸化性が高いため、特に切削時に高温となるような高速切削時の耐摩耗性が向上する。
特に平均総層厚が１．５〜４．０μｍのとき、その効果が際立って発揮される。
その理由は、平均総層厚が１．５μｍ未満では、工具基体表面粗さに比べ硬質被覆層の層厚が薄いため、長期の使用に亘っての耐摩耗性を十分確保することができない。一方、その平均総層厚が４．０μｍを越えると、硬質被覆層を構成する複合窒化物の結晶粒が粗大化し易くなり、チッピングを発生しやすくなる。
したがって、硬質被覆層の平均総層厚は、１．５〜４．０μｍと定めた。
Average total thickness of hard coating layer:
As shown in FIG. 1, the hard coating layer of the present invention includes a lower layer A composed of at least a Ti 1-a Al a N component system directly above a tool base, and Ti 1-xy Al formed thereon. It has a laminated structure composed of an upper layer B made of a component system of xSi y N.
This hard coating layer ensures excellent strength and toughness by the Ti component contained in the TiAlN layer which is the lower layer A, Al improves the high-temperature hardness and heat resistance, and at the same time contains Al and Ti at a higher temperature. Since it has the effect of improving oxidation resistance and has a rock salt type crystal structure, it has high hardness and can be formed on a tool base to improve wear resistance.
In addition, the TiAlSiN layer as the upper layer B has a high heat resistance by adding a Si component to the TiAlN layer, and has a high oxidation start temperature and a high temperature oxidation resistance. The wear resistance during high-speed cutting is improved.
In particular, when the average total layer thickness is 1.5 to 4.0 μm, the effect is remarkably exhibited.
The reason is that when the average total layer thickness is less than 1.5 μm, the hard coating layer is thinner than the surface roughness of the tool base, so that sufficient wear resistance cannot be ensured over a long period of use. On the other hand, if the average total layer thickness exceeds 4.0 μm, the crystal grains of the composite nitride constituting the hard coating layer are likely to be coarsened and chipping is likely to occur.
Therefore, the average total layer thickness of the hard coating layer was determined to be 1.5 to 4.0 μm.
ここで、硬質被覆層の平均総層厚は、ＳＥＭにて観察して得られた二次電子画像内の硬質被覆層の部分を画像処理にて抜き出し、画像解析によって画像内の５箇所について硬質被覆層の層厚を求め、その平均値を求め平均総層厚とした。画像処理に用いる観察領域として、期待する硬質被覆層の平均総層厚が１．５〜４．０μｍであることをかんがみ、１５μｍ×１５μｍ程度の視野領域とすることが望ましい。 Here, the average total thickness of the hard coating layer is determined by extracting the portion of the hard coating layer in the secondary electron image obtained by observing with the SEM by image processing, and performing hard analysis at five locations in the image by image analysis. The layer thickness of the coating layer was determined, and the average value was determined as the average total layer thickness. Considering that the expected average total thickness of the hard coating layer is 1.5 to 4.0 μm as the observation region used for image processing, it is desirable that the viewing region be about 15 μm × 15 μm.
硬質被覆層を構成する下部層Ａ：
下部層Ａは、ＡｌのＴｉとＡｌの合量に占める含有割合ａ（但し、ａは原子比）が、０．３≦ａ≦０．７を満足する。
Ａｌ成分の含有量が０．３未満では、Ａｌ成分を含有することによる高温硬さと耐熱性の向上が十分得られず、所望の性能が得られない。また、Ａｌ成分の含有量が０．７を超えると、ＴｉＡｌＮ層が岩塩型結晶構造を維持できず、硬さが極端に低下するため、望ましくない。
また、下部層Ａを構成するＴｉＡｌＮ結晶粒は、その平均粒径を小さくすることによって、ｃＢＮ基体と下部層Ａの界面に生じるクラックを、ＴｉＡｌＮ結晶粒の微細粒界に分散させ、また、微細粒界に沿って伝播させることで、耐チッピング性、耐欠損性を向上させることができるが、その平均粒径が０．１μｍを超えると、耐異常損傷性の改善効果が少ないことから、下部層Ａを構成するＴｉＡｌＮ結晶粒の平均粒径は、０．１μｍ以下とすることが望ましい。
Lower layer A constituting the hard coating layer:
In the lower layer A, the content ratio a (where a is an atomic ratio) of the total amount of Ti and Al in Al satisfies 0.3 ≦ a ≦ 0.7.
When the content of the Al component is less than 0.3, the high temperature hardness and the heat resistance are not sufficiently improved by containing the Al component, and the desired performance cannot be obtained. On the other hand, when the content of the Al component exceeds 0.7, the TiAlN layer cannot maintain the rock salt type crystal structure and the hardness is extremely lowered, which is not desirable.
In addition, the TiAlN crystal grains constituting the lower layer A are dispersed in the fine grain boundaries of the TiAlN crystal grains by reducing the average grain size to disperse cracks generated at the interface between the cBN substrate and the lower layer A. By propagating along the grain boundary, chipping resistance and chipping resistance can be improved. However, if the average particle diameter exceeds 0.1 μm, the effect of improving abnormal damage resistance is small. The average grain size of the TiAlN crystal grains constituting the layer A is desirably 0.1 μm or less.
下部層Ａの残留応力σＡ：
図2に示すように、本発明では、ＡＩＰ装置によって硬質被覆層を蒸着形成するに際して、下部層Ａおよび上部層Ｂのそれぞれに対して、所定の残留応力を付与するが、下部層Ａに対しては、
−７．０≦σＡ≦−１．０
を満たす残留応力を付与する。
なお、マイナスは、残留応力が、圧縮残留応力であることを意味する。
下部層Ａに付与される残留応力値が、―７．０ＧＰａより大きい圧縮残留応力になると、下部層の内部応力が高くなりすぎて、皮膜が自壊してしまい、一方、−１．０ＧＰａより小さな圧縮残留応力になると、ｃＢＮ基体と下部層Ａの界面に生じたクラックの進展を十分に抑制することができず、チッピング、欠損が発生し、耐異常損傷性が低下することから、本発明では、下部層Ａに付与される残留応力を、−７．０（ＧＰａ）≦σＡ≦−１．０（ＧＰａ）と定めた。
Residual stresses of the lower layer A sigma A:
As shown in FIG. 2, in the present invention, when the hard coating layer is formed by vapor deposition using the AIP apparatus, a predetermined residual stress is applied to each of the lower layer A and the upper layer B. The
−7.0 ≦ σ A ≦ −1.0
Residual stress satisfying
The minus sign means that the residual stress is a compressive residual stress.
When the residual stress value applied to the lower layer A is a compressive residual stress greater than -7.0 GPa, the internal stress of the lower layer becomes too high, and the coating is self-destructed, whereas it is smaller than -1.0 GPa. When the compressive residual stress is reached, the progress of cracks generated at the interface between the cBN substrate and the lower layer A cannot be sufficiently suppressed, chipping and defects occur, and the abnormal damage resistance decreases. The residual stress applied to the lower layer A was determined to be −7.0 (GPa) ≦ σ A ≦ −1.0 (GPa).
硬質被覆層を構成する上部層Ｂ：
上部層Ｂは、ＡｌおよびＳｉのＴｉとＡｌとＳｉの合量に占める含有割合ｘ、ｙ（但し、ｘ、ｙはいずれも原子比）が、それぞれ、０．３≦ｘ≦０．７、０．０１≦ｙ≦０．１を満足する。
この条件を満たすとき、上部層Ｂを構成するＴｉ１−ｘ―ｙＡｌｘＳｉｙＮ層は所望の耐酸化性および切削時に高温となるような高速切削時における高い耐摩耗性を発揮する。
一方、Ａｌ成分の含有量が０．３未満では、Ａｌ成分を含有することによる高温硬さと耐熱性の向上が十分得られず、所望の性能が得られない。また、Ａｌ成分の含有量が０．７を超えると、ＡｌＴｉＳｉＮ層が岩塩型結晶構造を維持できず、硬さが極端に低下するため、望ましくない。Ｓｉ成分が０．０１未満では所望の耐摩耗性が発揮されず、０．１を超えると結晶格子の歪みが大きくなり、耐欠損性が低下するため望ましくない。
Upper layer B constituting the hard coating layer:
In the upper layer B, the content ratios x and y (where x and y are atomic ratios) of the total amount of Ti and Al and Si in Al and Si are 0.3 ≦ x ≦ 0.7, respectively. 0.01 ≦ y ≦ 0.1 is satisfied.
When this condition is satisfied, the Ti 1-xy Al x Si y N layer constituting the upper layer B exhibits desired oxidation resistance and high wear resistance during high-speed cutting such that the temperature becomes high during cutting.
On the other hand, if the content of the Al component is less than 0.3, sufficient improvement in high temperature hardness and heat resistance due to the inclusion of the Al component cannot be obtained, and desired performance cannot be obtained. On the other hand, when the content of the Al component exceeds 0.7, the AlTiSiN layer cannot maintain the rock salt type crystal structure and the hardness is extremely lowered, which is not desirable. If the Si component is less than 0.01, the desired wear resistance is not exhibited. If it exceeds 0.1, the distortion of the crystal lattice increases and the fracture resistance decreases, which is not desirable.
硬質被覆層全体を総括した残留応力σＴと下部層Ａの残留応力σＡ：
図2に示すように、本発明では、ｃＢＮ基体と下部層Ａの界面に生じたクラックの進展を十分に抑制するために、−７．０（ＧＰａ）≦σＡ≦−１．０（ＧＰａ）を満足する残留応力を下部層Ａに付与すると同時に、上部層Ｂにも残留応力を付与し、切削加工時に、上部層Ｂの表面から進展するクラックが、硬質被覆層内に伝播・進展することを抑制する。
また、下部層Ａと上部層Ｂに付与する残留応力を制御することで、硬質被覆層に切削加工時の高負荷が作用した場合でも、下部層Ａと上部層Ｂの剥離・破壊を防止する。
上記の観点から、硬質被覆層全体を総括した残留応力をσＴ（ＧＰａ）としたとき、
σＡ＜σＴ、であって、かつ、−４．０≦σＴ≦−０．５、さらに、｜σＡ−σＴ｜＜４．０
を満足するσＴ（ＧＰａ）となるようにする必要がある。
Residual stress σ T for the entire hard coating layer and residual stress σ A for the lower layer A :
As shown in FIG. 2, in the present invention, −7.0 (GPa) ≦ σ A ≦ −1.0 (GPa) in order to sufficiently suppress the progress of cracks generated at the interface between the cBN substrate and the lower layer A. ) Is applied to the lower layer A, and at the same time, residual stress is applied to the upper layer B, and cracks that propagate from the surface of the upper layer B propagate and propagate in the hard coating layer during cutting. To suppress that.
In addition, by controlling the residual stress applied to the lower layer A and the upper layer B, even when a high load is applied to the hard coating layer during the cutting process, the lower layer A and the upper layer B are prevented from peeling or breaking. .
From the above viewpoint, when the residual stress that summarizes the entire hard coating layer is σ T (GPa),
σ A <σ T , and −4.0 ≦ σ T ≦ −0.5, and | σ A −σ T | <4.0
Σ T (GPa) must be satisfied.
ここで、硬質被覆層全体を総括した残留応力をσＴ（ＧＰａ）とは、ＸＲＤピークを用いて残留応力を測定する際に、図４に示すように、下部層Ａと上部層Ｂの重なったＸＲＤピークを一つのピークとして評価して算出した残留応力値をいう。 Here, the total residual stress of the hard coating layer is σ T (GPa). When the residual stress is measured using the XRD peak, the lower layer A and the upper layer B overlap as shown in FIG. The residual stress value calculated by evaluating the XRD peak as one peak.
また、上記の作用効果をさらに一層有効にさせるためには、図3に示すように、下部層Ａの平均層厚をｔＡ、上部層Ｂの平均層厚をｔＢとしたとき、
４≦ｔＢ／ｔＡ≦９
を満足するような下部層の層厚ｔＡ、上部層Ｂの層厚ｔＢとし、さらに、下部層Ａの結晶粒の平均粒径を０．１μｍ以下することが望ましい。
即ち、ｔＡ、ｔＢが上記の関係を満足する場合には、耐摩耗性層である上部層Ｂの下部層Ａに対する層厚比が大きくなることで、上部層Ｂが、長期の使用に亘ってすぐれた耐摩耗性を発揮するようになる。
また、下部層Ａの平均粒径が０．１μｍ以下と小さいために、クラックは微細な結晶粒の結晶粒界に沿って伝播することになるため、耐チッピング性、耐欠損性等の耐異常損傷性を高めることができる。
Further, in order to make the above-described effect even more effective, as shown in FIG. 3, when the average layer thickness of the lower layer A is t A and the average layer thickness of the upper layer B is t B ,
4 ≦ t B / t A ≦ 9
It is desirable that the lower layer thickness t A satisfies the above and the upper layer B layer thickness t B, and the average grain diameter of the lower layer A is 0.1 μm or less.
That is, when t A and t B satisfy the above relationship, the layer thickness ratio of the upper layer B, which is a wear-resistant layer, to the lower layer A is increased, so that the upper layer B can be used for a long time. It exhibits excellent wear resistance throughout.
In addition, since the average grain size of the lower layer A is as small as 0.1 μm or less, cracks propagate along the grain boundaries of fine crystal grains. Damage can be increased.
本発明の被覆工具は、特に、ｃＢＮ基体表面に、Ｔｉ１−ａＡｌａＮ層からなる下部層Ａと、Ｔｉ１−ｘ―ｙＡｌｘＳｉｙＮ層からなる上部層Ｂを備え、下部層Ａの残留応力σＡ（ＧＰａ）が所定範囲に制御され、さらに、硬質被覆層全体を総括した残留応力をσＴ（ＧＰａ）とσＡ（ＧＰａ）との間に、所定の関係を持たせたことにより、高硬度鋼の高速切削加工に供した場合でも、チッピング、欠損、剥離等の異常損傷を発生することがなく、長期の使用に亘って、すぐれた耐摩耗性を発揮するものである。 The coated tool of the present invention includes, in particular, a lower layer A composed of a Ti 1-a Al a N layer and an upper layer B composed of a Ti 1-xy Al x Si y N layer on the surface of a cBN substrate, The residual stress σ A (GPa) of the layer A is controlled within a predetermined range, and the residual stress that summarizes the entire hard coating layer has a predetermined relationship between σ T (GPa) and σ A (GPa). As a result, even when subjected to high-speed cutting of high-hardness steel, it does not cause abnormal damage such as chipping, chipping or peeling, and exhibits excellent wear resistance over a long period of use. It is.
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.
工具基体の作製：
原料粉末として、０．５〜４．０μｍの平均粒径を有するｃＢＮ粒子を硬質相形成用原料粉末として用意するとともに、いずれも０．３〜０．９μｍの範囲内の平均粒径を有するＴｉＮ粉末、ＴｉＣ粉末、ＴｉＣＮ粉末、Ａｌ粉末、ＡｌＮ粉末、Ａｌ２Ｏ３粉末を結合相形成用原料粉末として用意する。
これら中からいくつかの原料粉末とｃＢＮ粒子粉末の合量を１００体積％としたときのｃＢＮ粒子粉末の含有割合が４０〜７０体積％となるように表１に示される配合比で配合する。
次いで、この原料粉末をボールミルで７２時間湿式混合し、乾燥した後、油圧プレスにて成形圧１ＭＰａで直径：５０ｍｍ×厚さ：１．５ｍｍの寸法にプレス成形し、ついでこの成形体を、圧力：１Ｐａ以下の真空雰囲気中、１０００℃で３０分間保持して熱処理し、揮発成分および粉末表面への吸着成分を除去して予備焼結体を作製する。
この予備焼結体をワイヤー放電加工機で所定寸法に切断し、Ｃｏ：５質量％、ＴａＣ：５質量％、ＷＣ：残りの組成およびＩＳＯ規格ＣＮＧＡ１２０４０８のインサート形状をもったＷＣ基超硬合金製インサート本体のろう付け部（コーナー部）に、質量％で、Ｃｕ：２６％、Ｔｉ：５％、Ａｇ：残りからなる組成を有するＡｇ系ろう材を用いてろう付けし、上下面および外周研磨、ホーニング処理を施すことによりＩＳＯ規格ＣＮＧＡ１２０４０８のインサート形状をもった本発明用の工具基体１〜６を製造する。
表１に、粉末の配合比を示す。
Tool substrate production:
As the raw material powder, cBN particles having an average particle diameter of 0.5 to 4.0 μm are prepared as a raw material powder for forming a hard phase, and TiN having an average particle diameter in the range of 0.3 to 0.9 μm. Powder, TiC powder, TiCN powder, Al powder, AlN powder, and Al 2 O 3 powder are prepared as binder phase forming raw material powders.
Among these, the blending ratio shown in Table 1 is blended so that the content of the cBN particle powder is 40 to 70% by volume when the total amount of some raw material powders and the cBN particle powder is 100% by volume.
Next, the raw material powder is wet mixed in a ball mill for 72 hours, dried, and then press-molded with a molding pressure of 1 MPa to a size of diameter: 50 mm × thickness: 1.5 mm with a hydraulic press. A pre-sintered body is produced by removing the volatile components and the components adsorbed on the powder surface by heat treatment by holding at 1000 ° C. for 30 minutes in a vacuum atmosphere of 1 Pa or less.
This pre-sintered body is cut into a predetermined size with a wire electric discharge machine, Co: 5 mass%, TaC: 5 mass%, WC: remaining composition and made of WC-base cemented carbide with ISO standard CNGA120408 insert shape The brazing part (corner part) of the insert body is brazed using an Ag-based brazing material having a composition of Cu: 26%, Ti: 5%, and Ag: the remainder, and polishing the upper and lower surfaces and outer circumference. The tool bases 1 to 6 for the present invention having the ISO standard CNGA120408 insert shape are manufactured by performing the honing process.
Table 1 shows the mixing ratio of the powder.
成膜工程：
前述の工程によって作製した工具基体１〜６に対して、図５に示したようなアークイオンプレーティング装置を用いて、硬質被覆層を形成した。
（ａ）工具基体１〜６を、アセトン中で超音波洗浄し、乾燥した状態で、アークイオンプレーティング装置内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する。また、カソード電極（蒸発源）として、所定組成のＴｉ−Ａｌ合金およびＴｉ−Ａｌ−Ｓｉ合金を配置する。
（ｂ）まず、装置内を排気して１０−２Ｐａ以下の真空に保持しながら、ヒーターで装置内を５００℃に加熱した後、２ＰａのＡｒガス雰囲気に設定し、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−２００〜−６００Ｖの直流バイアス電圧を印加し、もって工具基体表面をアルゴンイオンによってボンバード洗浄する。
（ｃ）次に、装置内に反応ガスとして窒素ガスを導入して、成膜雰囲気温度を４００〜５５０℃、かつ、表２に示す２〜８Ｐａの範囲内の所定窒素ガス圧力とすると共に、前記回転テーブル上で自転しながら回転する工具基体に、表２に示す−２０〜−１００Ｖの範囲内の所定の直流バイアス電圧を印加し、かつ、前記Ｔｉ−Ａｌ合金からなるカソード電極（蒸発源）とアノード電極との間に、表２に示す１００〜２００Ａの範囲内の所定の電流を流してアーク放電を発生させ、前記工具基体の表面に、表２に示される目標平均組成、目標平均層厚の（Ｔｉ，Ａｌ）Ｎ層を蒸着形成する。
（ｄ）次いで、装置内に反応ガスとして窒素ガスを導入して、成膜雰囲気温度を４００〜５５０℃、かつ、同じく表３に示す３〜１０Ｐａの範囲内の所定窒素ガス圧力とすると共に、前記回転テーブル上で自転しながら回転する工具基体に、表３に示す−２０〜−１００Ｖの範囲内の所定の直流バイアス電圧を印加し、かつ、前記Ｔｉ−Ａｌ−Ｓｉ合金からなるカソード電極（蒸発源）とアノード電極との間に、表３に示す９０〜１８０Ａの所定の電流を流してアーク放電を発生させ、前記工具基体の表面に、表３に示される目標平均組成、目標平均層厚の（Ｔｉ，Ａｌ，Ｓｉ）Ｎ層を蒸着形成した。
上記工程（ａ）〜（ｄ）によって、表６に示す本発明被覆工具１〜１０を作製した。
なお、上記工程（ｃ）においては、工程（ｄ）に比して低ガス圧かつ高アーク電流にて成膜することにより、微細な組織を形成し、一方、上記工程（ｄ）においては、工程（ｃ）に比して高ガス圧かつ低アーク電流にて成膜し、成膜時間を調整して、上部層Ｂの層厚が下部層Ａより厚くなるように成膜した。
Film formation process:
A hard coating layer was formed on the tool bases 1 to 6 produced by the above-described process using an arc ion plating apparatus as shown in FIG.
(A) The tool bases 1 to 6 are ultrasonically cleaned in acetone and dried. Then, the tool bases 1 to 6 are arranged along the outer peripheral portion at a predetermined radial distance from the central axis on the rotary table in the arc ion plating apparatus. Install. In addition, as a cathode electrode (evaporation source), a Ti—Al alloy and a Ti—Al—Si alloy having a predetermined composition are disposed.
(B) First, the inside of the apparatus is evacuated and kept at a vacuum of 10 −2 Pa or less, the inside of the apparatus is heated to 500 ° C. with a heater, set to an Ar gas atmosphere of 2 Pa, and rotated on the rotary table. A DC bias voltage of −200 to −600 V is applied to the rotating tool base while the tool base surface is bombarded with argon ions.
(C) Next, nitrogen gas is introduced into the apparatus as a reaction gas, the film formation atmosphere temperature is set to 400 to 550 ° C., and a predetermined nitrogen gas pressure within the range of 2 to 8 Pa shown in Table 2, A predetermined DC bias voltage within a range of −20 to −100 V shown in Table 2 is applied to a tool base that rotates while rotating on the rotary table, and a cathode electrode (evaporation source) made of the Ti—Al alloy is applied. ) And the anode electrode, a predetermined current in a range of 100 to 200 A shown in Table 2 is passed to generate arc discharge, and the target average composition and target average shown in Table 2 are formed on the surface of the tool base. A (Ti, Al) N layer having a layer thickness is formed by vapor deposition.
(D) Next, nitrogen gas is introduced into the apparatus as a reaction gas, the film formation atmosphere temperature is set to 400 to 550 ° C., and a predetermined nitrogen gas pressure within the range of 3 to 10 Pa similarly shown in Table 3, A predetermined DC bias voltage within a range of −20 to −100 V shown in Table 3 is applied to a tool base that rotates while rotating on the rotary table, and a cathode electrode made of the Ti—Al—Si alloy ( A predetermined current of 90 to 180 A shown in Table 3 is passed between the evaporation source) and the anode electrode to generate arc discharge, and the target average composition and target average layer shown in Table 3 are formed on the surface of the tool base. A thick (Ti, Al, Si) N layer was deposited.
By the said process (a)-(d), this invention coated tool 1-10 shown in Table 6 was produced.
In the step (c), a fine structure is formed by forming a film at a lower gas pressure and a higher arc current than in the step (d), while in the step (d), Film formation was performed at a higher gas pressure and lower arc current than in step (c), and the film formation time was adjusted so that the upper layer B was thicker than the lower layer A.
比較のため、上記工具基体１〜６に対して、前記工程（ｃ）における窒素反応雰囲気ガス圧力、直流バイアス電圧を、表４に示す値に変更し、また、前記工程（ｄ）における窒素反応雰囲気ガス圧力、直流バイアス電圧を、表５に示す値に変更して、表７に示す比較例被覆工具１〜１０を作製した。 For comparison, the nitrogen reaction atmosphere gas pressure and DC bias voltage in the step (c) were changed to the values shown in Table 4 for the tool bases 1 to 6, and the nitrogen reaction in the step (d). The atmospheric gas pressure and the DC bias voltage were changed to the values shown in Table 5, and Comparative Example-coated tools 1 to 10 shown in Table 7 were produced.
上記で作製した本発明被覆工具１〜１０、比較例被覆工具１〜１０について、下部層Ａの残留応力σＡ（ＧＰａ）、硬質被覆層全体を総括した残留応力σＴ（ＧＰａ）を測定し、これらの値から、σＴとσＡの大小関係、｜σＡ−σＴ｜の値を求めた。
なお、残留応力σＡ、σＴ（ＧＰａ）の測定は、逃げ面上の超硬合金上にて測定した。ｃＢＮ焼結体からなる刃先は、ＷＣ基超硬合金製インサート本体のろう付け部（コーナー部）にろう付けされていることから、切削に使用される刃先部の皮膜の残留応力と本手法で測定する皮膜の残留応力は同等である。
具体的な残留応力の測定法は、既に良く知られた２θ−ｓｉｎ２ψ法を用いたＸ線回折（ＸＲＤ）法によって行った。その測定原理や測定方法は、例えば、日本材料学会Ｘ線材料強度部門委員会が発行しているＸ線応力測定法標準（１９９７年版）、改著Ｘ線応力測定法（養賢堂、１９９０年）、Ｘ線応力測定法の基礎と最近の発展（材料ｖｏｌ．４７，Ｎｏ．１１，１９９８）などに詳しく述べられているので、ここでは、割愛する。
また、硬質被覆層全体を総括した残留応力σＴ（ＧＰａ）は、図４に示すように、下部層Ａと上部層Ｂの重なったＸＲＤピークを一つのピークとして評価して算出した残留応力値である。下層部Ａの残留応力σＡ（ＧＰａ）については、例えば、成膜後に上部層Ｂを集束イオンビーム（Ｆｏｃｕｓｅｄ Ｉｏｎ Ｂｅａｍ：ＦＩＢ）法などの手法で加工・除去したのち、前述したX線回折法を用いることで測定できる。
For the inventive coated tools 1 to 10 and the comparative example coated tools 1 to 10 produced above, the residual stress σ A (GPa) of the lower layer A and the residual stress σ T (GPa) summing up the entire hard coating layer were measured. From these values, the magnitude relationship between σ T and σ A and the value of | σ A −σ T | were obtained.
The residual stresses σ A and σ T (GPa) were measured on a cemented carbide on the flank. The cutting edge made of a cBN sintered body is brazed to the brazing part (corner part) of the WC-base cemented carbide insert body. The residual stress of the film to be measured is equivalent.
A specific method for measuring the residual stress was performed by an X-ray diffraction (XRD) method using the well-known 2θ-sin 2 ψ method. The measurement principle and measurement method are, for example, X-ray stress measurement standard (1997 version) published by the Japan Society of Materials X-ray Material Strength Division Committee, revised X-ray stress measurement method (Yokendo, 1990) ), Since it is described in detail in the basics of X-ray stress measurement method and recent developments (Materials vol. 47, No. 11, 1998), etc., they are omitted here.
Further, the residual stress σ T (GPa) summing up the entire hard coating layer is calculated by evaluating the XRD peak where the lower layer A and the upper layer B overlap as one peak as shown in FIG. It is. Regarding the residual stress σ A (GPa) of the lower layer part A, for example, after processing and removing the upper layer B by a technique such as a focused ion beam (FIB) method after film formation, the above-mentioned X-ray diffraction method It can be measured by using.
また、上記の本発明被覆工具１〜１０および比較例被覆工具１〜１０について、ＦＩＢを用いた薄片加工により、工具逃げ面から工具基体および硬質被覆層を含む、幅１００μｍ×高さ３００μｍ×厚さ０．２μｍの薄片を切り出し、該薄片のうち、硬質被覆層の厚み領域が全て含まれるよう設定された、工具基体表面に平行な方向の幅が１０μｍである視野について、透過型電子顕微鏡（Ｔｒａｎｓｍｉｓｓｉｏｎ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ：ＴＥＭ）（倍率は２０００００倍から１００００００倍の範囲から適切な値に設定する）による断面観察を行い、硬質被覆層中の下部層Ａの平均粒径と、下部層Ａおよび上部層Ｂの平均層厚を測定した。ここで、工具基体表面とは、基体の硬質被覆層と接する面の面方向に垂直な断面の観察像における、基体と硬質被覆層の界面粗さの基準線とする。
上記下部層Ａの平均粒径は、工具基体表面と平行な方向に長さ１０μｍの範囲に存在するＴｉ１−ａＡｌａＮ結晶粒の工具基体表面と平行な粒子幅を測定し、測定範囲内に存在する粒子についての平均値を算出することにより下部層Ａの平均粒径を求めた。
また、下部層Ａおよび上部層Ｂの層厚については、走査型電子顕微鏡を用いて縦断面測定し、視野内の任意の５箇所にて工具基体表面に垂直な方向の層厚を測定し、測定の平均値から平均層厚を求めた。また下部層Ａおよび上部層Ｂの組成は、ＳＥＭを用いてのエネルギー分散型Ｘ線分光法（Ｅｎｅｒｇｙ Ｄｉｓｐｅｒｓｉｖｅ Ｘ−ｒａｙ Ｓｐｅｃｔｒｏｓｃｏｐｙ：ＥＤＳ）により測定した。
Moreover, about the said this invention coated tool 1-10 and comparative example coated tool 1-10, width 100 micrometers x height 300 micrometers x thickness including a tool base and a hard coating layer from a tool flank by thin piece processing using FIB A thin section having a thickness of 0.2 μm was cut out, and a transmission electron microscope (with a width of 10 μm in the direction parallel to the surface of the tool base, which was set so as to include the entire thickness region of the hard coating layer of the thin section ( Cross-sectional observation by Transmission Electron Microscope (TEM) (magnification is set to an appropriate value from the range of 200,000 to 1,000,000 times), the average particle diameter of the lower layer A in the hard coating layer, the lower layer A and the upper layer The average layer thickness of B was measured. Here, the surface of the tool base is a reference line of the interface roughness between the base and the hard coating layer in an observation image of a cross section perpendicular to the surface direction of the surface in contact with the hard coating layer of the base.
The average particle diameter of the lower layer A is measured by measuring the particle width of the Ti 1-a Al a N crystal grains existing in the range of 10 μm in the direction parallel to the tool substrate surface and parallel to the tool substrate surface. The average particle size of the lower layer A was determined by calculating the average value for the particles present therein.
Further, for the layer thicknesses of the lower layer A and the upper layer B, the longitudinal cross section is measured using a scanning electron microscope, the layer thickness in the direction perpendicular to the tool base surface is measured at any five locations in the field of view, The average layer thickness was determined from the average value of the measurements. The compositions of the lower layer A and the upper layer B were measured by energy dispersive X-ray spectroscopy (EDS) using SEM.
その結果を、表２〜表７に示す。 The results are shown in Tables 2-7.
次に、本発明被覆工具１〜１０および比較品被覆工具１〜１０について、
切削条件Ａ：
被削材：クロム鋼鋼材（ＪＩＳ・ＳＣｒ４２０）の浸炭焼入れ材（ＨＲＣ６０）の丸棒、
切削速度： ２７０ ｍ／ｍｉｎ．、
切り込み： ０．１５ ｍｍ、
送り： ０．１ ｍｍ／ｒｅｖ、
の乾式連続切削、
切削条件Ｂ：
被削材：クロム鋼鋼材（ＪＩＳ・ＳＣｒ４２０）の浸炭焼入れ材（ＨＲＣ６０）の長さ方向等間隔４本縦溝入り丸棒、
切削速度： １２０ ｍ／ｍｉｎ．、
切り込み： ０．２ ｍｍ、
送り： ０．１５ ｍｍ／ｒｅｖ、
の乾式断続切削、
という切削条件で、最大切削長を条件Ａでは９００ｍ、条件Ｂでは１２００ｍとし、切削長１００ｍ毎に刃先のチッピング、剥離等の異常損傷の有無と逃げ面摩耗量を評価した。
なお、異常損傷の有無については、被覆工具の刃先表面をＳＥＭで観察することによって評価した。
その結果を表８、表９に示す。
なお、最大切削長に到達する前に逃げ面摩耗量が０．２５ｍｍ以上になるか、刃先が欠損した場合に使用寿命であると判断した。
Next, about this invention coated tool 1-10 and comparative goods coated tool 1-10,
Cutting condition A:
Work material: Round bar of carburized and quenched material (HRC60) of chrome steel (JIS / SCr420),
Cutting speed: 270 m / min. ,
Cutting depth: 0.15 mm,
Feed: 0.1 mm / rev,
Dry continuous cutting,
Cutting condition B:
Work material: Four longitudinally grooved round bars with equal intervals in the longitudinal direction of carburized and quenched material (HRC60) of chrome steel (JIS / SCr420),
Cutting speed: 120 m / min. ,
Cutting depth: 0.2 mm,
Feed: 0.15 mm / rev,
Of dry interrupted cutting,
The maximum cutting length was 900 m for condition A and 1200 m for condition B, and the presence or absence of abnormal damage such as chipping and peeling of the cutting edge and the amount of flank wear were evaluated for every cutting length of 100 m.
In addition, the presence or absence of abnormal damage was evaluated by observing the cutting edge surface of the coated tool with an SEM.
The results are shown in Tables 8 and 9.
When the flank wear amount reached 0.25 mm or more before reaching the maximum cutting length, or when the cutting edge was missing, it was determined that the service life was reached.
表６、表８に示される結果から、本発明被覆工具は、ｃＢＮ基体表面上の下部層Ａの残留応力σＡ（ＧＰａ）を所定範囲に制御し、さらに、硬質被覆層全体を総括した残留応力をσＴ（ＧＰａ）とσＡ（ＧＰａ）との間に、所定の関係を持たせたことにより、高硬度鋼の高速切削加工に供した場合でも、チッピング、剥離等の異常損傷を発生することがなく、長期の使用に亘って、すぐれた耐摩耗性を発揮することが分かる。
さらに、本発明被覆工具は、下部層Ａの結晶粒を微粒とし、上部層Ｂの層厚ｔＢを厚くし、下部層Ａの層厚ｔＡの４〜９倍とした場合、さらに一段と耐異常損傷性、耐摩耗性が向上することが分かる。
From the results shown in Tables 6 and 8, the coated tool of the present invention controls the residual stress σ A (GPa) of the lower layer A on the cBN substrate surface within a predetermined range, and further summarizes the entire hard coating layer. By giving the stress a predetermined relationship between σ T (GPa) and σ A (GPa), abnormal damage such as chipping and peeling occurs even when subjected to high-speed cutting of high-hardness steel. It can be seen that it exhibits excellent wear resistance over a long period of use.
Furthermore, the present invention coated tool, the crystal grains of the lower layer A and fine, when thickening the thickness t B of the upper layer B, was 4-9 times the thickness t A of the lower layer A, even more resistant It can be seen that abnormal damage and wear resistance are improved.
これに対して、表７、表９に示される結果から、本発明で規定するσＡ（ＧＰａ）、σＴ（ＧＰａ）の関係を満たさない比較例工具においては、チッピング、剥離を発生し易く、また、耐摩耗性に劣り、比較的短時間で使用寿命に至ることが明らかである。 On the other hand, from the results shown in Tables 7 and 9, the comparative tool that does not satisfy the relationship of σ A (GPa) and σ T (GPa) defined in the present invention is likely to cause chipping and peeling. Further, it is apparent that the wear resistance is poor and the service life is reached in a relatively short time.
本発明の表面被覆切削工具は、すぐれた耐異常損傷性および耐摩耗性を発揮し、長期に亘ってすぐれた切削性能を示すものであるから、切削加工装置の高性能化、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。
The surface-coated cutting tool of the present invention exhibits excellent abnormal damage resistance and wear resistance, and exhibits excellent cutting performance over a long period of time. It can be used satisfactorily for labor saving, energy saving, and cost reduction.
Claims (2)
前記立方晶窒化硼素焼結体は、立方晶窒化硼素粒子と、Ｔｉの窒化物、炭化物、炭窒化物、硼化物およびＡｌの窒化物、酸化物からなる群から選ばれた少なくとも１種以上の粒子と不可避不純物とを含む結合相とからなり、
前記硬質被覆層は、工具基体直上の少なくとも下部層Ａとその上に形成された上部層Ｂとからなるとともに平均総層厚が１．５〜４．０μｍであり、
前記下部層Ａは、
組成式：Ｔｉ１−ａＡｌａＮ（但し、ａは原子比で０．３≦ａ≦０．７）
を満足する成分系からなり、
前記上部層Ｂは、
組成式：Ｔｉ１−ｘ―ｙＡｌｘＳｉｙＮ（但し、ｘ、ｙは原子比で０．３≦ｘ≦０．７、０．０１≦ｙ≦０．１）
を満足する成分系からなり、
前記表面被覆切削工具の逃げ面の下部層Ａの残留応力をσＡ（ＧＰａ）、前記硬質被覆層全体を総括した残留応力をσＴ（ＧＰａ）としたとき、
σＡ＜σＴ、
−７．０≦σＡ≦−１．０、
−４．０≦σＴ≦−０．５、
｜σＡ−σＴ｜＜４．０
の条件をすべて満たすことを特徴とする表面被覆切削工具。 A surface-coated cutting tool in which a hard coating layer is deposited on a tool base made of at least a cubic boron nitride sintered body as a cutting edge used for cutting,
The cubic boron nitride sintered body includes at least one selected from the group consisting of cubic boron nitride particles, Ti nitride, carbide, carbonitride, boride, Al nitride, and oxide. Consisting of a binder phase containing particles and inevitable impurities,
The hard coating layer comprises at least a lower layer A immediately above the tool base and an upper layer B formed thereon, and an average total layer thickness is 1.5 to 4.0 μm,
The lower layer A includes
Composition formula: Ti 1-a Al a N (where a is an atomic ratio of 0.3 ≦ a ≦ 0.7)
Consisting of ingredients that satisfy
The upper layer B is
Composition formula: Ti 1-xy Al x Si y N (where x and y are atomic ratios 0.3 ≦ x ≦ 0.7, 0.01 ≦ y ≦ 0.1)
Consisting of ingredients that satisfy
When the residual stress of the lower layer A on the flank of the surface-coated cutting tool is σ A (GPa), and the residual stress that summarizes the entire hard coating layer is σ T (GPa),
σ A <σ T ,
−7.0 ≦ σ A ≦ −1.0,
−4.0 ≦ σ T ≦ −0.5,
| Σ A −σ T | <4.0
A surface-coated cutting tool characterized by satisfying all of the above conditions .
４≦ｔＢ／ｔＡ≦９
であり、下部層Ａの結晶粒の平均粒径が０．１μｍ以下であることを特徴とする請求項１に記載の表面被覆切削工具。 When the average layer thickness of the lower layer A is t A and the average layer thickness of the upper layer B is t B ,
4 ≦ t B / t A ≦ 9
The surface-coated cutting tool according to claim 1, wherein the average grain size of the crystal grains of the lower layer A is 0.1 µm or less.
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| EP3228726A1 (en) * | 2016-04-08 | 2017-10-11 | Seco Tools Ab | Coated cutting tool |
| EP3511097A4 (en) * | 2016-09-06 | 2020-05-13 | Sumitomo Electric Hardmetal Corp. | Cutting tool and method for producing same |
| JPWO2018047734A1 (en) * | 2016-09-06 | 2019-06-24 | 住友電工ハードメタル株式会社 | Cutting tool and method of manufacturing the same |
| US11167355B2 (en) * | 2018-10-15 | 2021-11-09 | Sumitomo Electric Hardmetal Corp. | Cutting tool |
| CN109234677A (en) * | 2018-10-17 | 2019-01-18 | 基准精密工业（惠州）有限公司 | A kind of coating |
| KR102112084B1 (en) * | 2018-11-30 | 2020-05-18 | 한국야금 주식회사 | Hard coating layer for cutting tools |
| EP4052822A4 (en) * | 2019-10-29 | 2023-05-10 | Mitsubishi Materials Corporation | Surface-coated cutting tool |
| CN111500998A (en) * | 2020-05-29 | 2020-08-07 | 华南理工大学 | AlTiN/TiAlSiN gradient nano composite structure coating and integrated preparation method and application thereof |
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| JP2004230515A (en) * | 2003-01-30 | 2004-08-19 | Nachi Fujikoshi Corp | Tool for highly functional processing |
| JP4593994B2 (en) * | 2004-07-23 | 2010-12-08 | 住友電工ハードメタル株式会社 | Surface coated cutting tool |
| JP4634246B2 (en) * | 2004-07-29 | 2011-02-16 | 住友電工ハードメタル株式会社 | Surface coated cutting tool |
| SE528789C2 (en) * | 2004-09-10 | 2007-02-13 | Sandvik Intellectual Property | PVD-coated cemented carbide cutter and way to manufacture it |
| 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 |
| JP5482596B2 (en) * | 2010-09-15 | 2014-05-07 | 三菱マテリアル株式会社 | CBN insert with excellent finished surface roughness |
| US8440328B2 (en) * | 2011-03-18 | 2013-05-14 | Kennametal Inc. | Coating for improved wear resistance |
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