JP4427729B2 - Cutting tool made of surface-coated cubic boron nitride based sintered material with excellent chipping resistance with hard coating layer - Google Patents
Cutting tool made of surface-coated cubic boron nitride based sintered material with excellent chipping resistance with hard coating layer Download PDFInfo
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この発明は、通常の鋼や鋳鉄などの被削材は勿論のこと、特に浸炭焼入れ鋼や熱処理硬化鋼などの各種の高硬度鋼の高速断続切削においても、切刃部にきわめて短いピッチで繰り返し付加される機械的熱的衝撃に対して硬質被覆層がすぐれた耐チッピング性を発揮する表面被覆立方晶窒化硼素系焼結材料製切削工具（以下、被覆ＢＮ系工具という）に関するものである。 This invention is not only for work materials such as normal steel and cast iron, but also for high-speed intermittent cutting of various hardened steels such as carburized and hardened steel and heat-treated hardened steel. The present invention relates to a surface-coated cubic boron nitride-based sintered material cutting tool (hereinafter referred to as a coated BN-based tool) in which a hard coating layer exhibits excellent chipping resistance against an applied mechanical thermal shock.
従来、一般に、立方晶窒化硼素系焼結材料で構成された基体（以下、工具基体という）の表面に、
（ａ）下部層として、いずれも蒸着形成されたＴｉの炭化物（以下、ＴｉＣで示す）層、窒化物（以下、同じくＴｉＮで示す）層、炭窒化物（以下、ＴｉＣＮで示す）層、炭酸化物（以下、ＴｉＣＯで示す）層、および炭窒酸化物（以下、ＴｉＣＮＯで示す）層のうちの１層または２層以上からなり、かつ２〜１５μｍの合計平均層厚を有するＴｉ化合物層、
（ｂ）上部層として、蒸着形成した状態でα型の結晶構造を有し、かつ０．５〜１０μｍの平均層厚を有する蒸着α型酸化アルミニウム（以下、Ａｌ2Ｏ3で示す）層、
以上（ａ）および（ｂ）で構成された硬質被覆層を形成してなる被覆ＢＮ系工具が知られており、この被覆ＢＮ系工具が、例えば各種の鋼や鋳鉄などの連続切削や断続切削に用いられていることも知られている。
Conventionally, in general, on the surface of a base body (hereinafter referred to as a tool base body) made of cubic boron nitride-based sintered material,
(A) As a lower layer, Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, carbonic acid layer formed by vapor deposition A Ti compound layer comprising one or more of a chemical compound (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer and having a total average layer thickness of 2 to 15 μm,
(B) a vapor-deposited α-type aluminum oxide (hereinafter referred to as Al 2 O 3 ) layer having an α-type crystal structure in a vapor-deposited state and an average layer thickness of 0.5 to 10 μm as an upper layer;
A coated BN-based tool formed by forming a hard coating layer composed of the above (a) and (b) is known, and this coated BN-based tool is, for example, continuous cutting or intermittent cutting of various types of steel and cast iron. It is also known that it is used in
また、一般に、上記の被覆ＢＮ系工具の硬質被覆層を構成するＴｉ化合物層やＡｌ2Ｏ3層が粒状結晶組織を有し、さらに、前記Ｔｉ化合物層を構成するＴｉＣＮ層を、層自身の強度向上を目的として、通常の化学蒸着装置にて、反応ガスとして有機炭窒化物、例えばＣＨ3ＣＮを含む混合ガスを使用し、７００〜９５０℃の中温温度域で化学蒸着することにより形成して縦長成長結晶組織をもつようにすることも知られている。
近年の切削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、切削加工は一段と高速化の傾向にあるが、上記の従来被覆ＢＮ系工具においては、これを鋼や鋳鉄などの通常の条件での連続切削や断続切削に用いた場合には問題はないが、特に浸炭焼入れ鋼や熱処理硬化鋼などの各種の高硬度鋼などを切削条件の最も厳しい高速断続切削、すなわち切刃部にきわめて短いピッチで繰り返し機械的熱的衝撃が付加される高速断続切削に用いた場合、硬質被覆層の下部層であるＴｉ化合物層は高い高温強度を有し、すぐれた耐衝撃性を示すものの、同上部層を構成する蒸着α型Ａｌ2Ｏ3層は、高温硬さおよび耐熱性にすぐれるものの、相対的に高温強度が低く、機械的熱的衝撃に対してきわめて脆いものであるために、これが原因で硬質被覆層にはチッピング（微小欠け）が発生し易くなり、この結果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 machines has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting work. For coated BN-based tools, there is no problem when this is used for continuous cutting and intermittent cutting under normal conditions such as steel and cast iron, but various hardened steels such as carburized and hardened steel and heat-treated hardened steel. Is used for high-speed intermittent cutting with the severest cutting conditions, that is, high-speed intermittent cutting in which mechanical thermal shock is repeatedly applied to the cutting edge at an extremely short pitch, the Ti compound layer that is the lower layer of the hard coating layer is Although it has high high-temperature strength and excellent impact resistance, the deposited α-type Al 2 O 3 layer that constitutes the upper layer has excellent high-temperature hardness and heat resistance, but relatively low high-temperature strength. , Mechanical and thermal Since it is extremely fragile to impact, it is easy for chipping (minute chipping) to occur in the hard coating layer due to this, and as a result, the service life is reached in a relatively short time.
そこで、本発明者等は、上述のような観点から、上記の被覆ＢＮ系工具の硬質被覆層の上部層を構成するＡｌ2Ｏ3層の耐チッピング性向上をはかるべく研究を行った結果、
（ａ）上記の通り、硬質被覆層としての蒸着α型Ａｌ2Ｏ3層は、高温硬さおよび耐熱性にすぐれるものの、高温強度が十分でなく、満足な耐チッピング性を発揮することは困難であり、一方蒸着形成した状態でκ型またはθ型の結晶構造を有するＡｌ2Ｏ3層は、前記蒸着α型Ａｌ2Ｏ3層に比して、相対的に高い高温強度を有し、耐チッピング性にすぐれるものの、高温硬さおよび耐熱性の点で劣り、摩耗進行が相対的に速いという性質があること。
Therefore, from the above viewpoint, the present inventors conducted research to improve the chipping resistance of the Al 2 O 3 layer constituting the upper layer of the hard coating layer of the coated BN-based tool,
(A) As described above, the vapor-deposited α-type Al 2 O 3 layer as the hard coating layer is excellent in high-temperature hardness and heat resistance, but does not have sufficient high-temperature strength and exhibits satisfactory chipping resistance. On the other hand, an Al 2 O 3 layer having a κ-type or θ-type crystal structure in a vapor-deposited state has a relatively high high-temperature strength compared to the vapor-deposited α-type Al 2 O 3 layer. Although it has excellent chipping resistance, it is inferior in terms of high-temperature hardness and heat resistance, and has a property that wear progress is relatively fast.
（ｂ）工具基体の表面に、通常の化学蒸着装置で、下部層として、通常の条件で、上記Ｔｉ化合物層を形成した後、同じく通常の条件で、蒸着形成した状態でκ型またはθ型の結晶構造を有するＡｌ2Ｏ3層を形成し、ついで、これに加熱処理、望ましくは圧力：７〜５０ｋＰａのＡｒ雰囲気中、温度：１０００〜１２００℃に５〜８０分保持の条件で加熱処理を施すと、前記Ｔｉ化合物層に結晶構造上変化は起らないが、前記κ型またはθ型の結晶構造を有するＡｌ2Ｏ3層はα型結晶構造のＡｌ2Ｏ3層に変態し、この変態に際して、体積収縮による割れ（クラック）が発生し、この変態割れは変態後のα型Ａｌ2Ｏ3層に大きな割れとして存在し、切削加工時のチッピング発生の原因となること。 (B) After forming the Ti compound layer as a lower layer under normal conditions on the surface of the tool base with a normal chemical vapor deposition apparatus, the κ-type or θ-type is formed under the same normal conditions. An Al 2 O 3 layer having the following crystal structure is formed, followed by heat treatment, desirably heat treatment in an Ar atmosphere at a pressure of 7 to 50 kPa, and a temperature of 1000 to 1200 ° C. for 5 to 80 minutes. However, the Ti compound layer does not change in the crystal structure, but the Al 2 O 3 layer having the κ-type or θ-type crystal structure is transformed into an α-type crystal structure Al 2 O 3 layer, During this transformation, a crack due to volume shrinkage occurs, and this transformation crack exists as a large crack in the α-type Al 2 O 3 layer after transformation, which causes chipping during cutting.
（ｃ）上記（ｂ）のＴｉ化合物層の表面に蒸着形成した状態でκ型またはθ型の結晶構造を有するＡｌ2Ｏ3層に、上記条件での加熱処理を施さずに、引き続いて、同じく化学蒸着装置にて、
反応ガス組成：体積％で、ＴｉＣｌ４：０．２〜３％、ＣＯ２：０．２〜１０％、Ａｒ：５〜５０％、Ｈ２：残り、
反応雰囲気温度：８００〜１１００℃、
反応雰囲気圧力：４〜７０ｋＰａ、
時間：１５〜６０分、
の条件で処理して、前記蒸着κ型またはθ型Ａｌ2Ｏ3層の表面に、酸化チタン（以下、ＴｉＯＸで示す）層を０．０５〜１μｍの平均層厚で形成し、この状態で、上記（ｂ）の条件での加熱処理を施して、前記蒸着κ型またはθ型の結晶構造のＡｌ2Ｏ3層をα型結晶構造のＡｌ2Ｏ3層に変態させると、前記変態前のＡｌ2Ｏ3層の表面に形成したＴｉＯＸ層が、前記変態をＡｌ2Ｏ3層の表面全面に亘って同時的に開始するように作用し、経時的にＡｌ2Ｏ3層の表面部から内部に進行する変態形態をとるようになることから、前記Ａｌ2Ｏ3層のκ型またはθ型の結晶構造からα型結晶構造への変態による体積収縮に伴なって発生する割れは、きわめて微細に、かつ層全体に亘って一様に分散分布した状態となるほか、変態後のＡｌ2Ｏ3層における結晶配向も変態前のκ型またはθ型Ａｌ2Ｏ3層のもつ結晶配向と同等、あるいは結晶配向に変化があってもきわめて小さなものとなり、この結果形成された加熱変態α型Ａｌ2Ｏ3層は、α型結晶構造のもつすぐれた高温硬さと耐熱性と共に、加熱変態前のκ型またはθ型Ａｌ2Ｏ3層のもつ高温強度と同等のすぐれた高温強度を具備するようになり、したがって、硬質被覆層の上部層が前記加熱変態α型Ａｌ2Ｏ3層、下部層が上記Ｔｉ化合物層で構成された被覆ＢＮ系工具においては、特に激しい機械的熱的衝撃を伴なう高速断続切削加工でも前記加熱変態α型Ａｌ2Ｏ3層が、すぐれた高温硬さと耐熱性に加えて、すぐれた耐チッピング性を発揮することから、高い高温強度を有する前記Ｔｉ化合物層との共存と相俟って、硬質被覆層におけるチッピング発生が著しく抑制され、長期に亘ってすぐれた耐摩耗性を示すようになること。
(C) Without subjecting the Al 2 O 3 layer having a κ-type or θ-type crystal structure to the surface of the Ti compound layer of (b) above, without performing heat treatment under the above conditions, In the same chemical vapor deposition system,
Reaction gas composition: by volume%, TiCl 4: 0.2~3%, CO 2: 0.2~10%, Ar: 5~50%, H 2: remainder,
Reaction atmosphere temperature: 800-1100 ° C.
Reaction atmosphere pressure: 4 to 70 kPa,
Time: 15-60 minutes,
In this state, a titanium oxide (hereinafter referred to as TiO X ) layer is formed with an average layer thickness of 0.05 to 1 μm on the surface of the vapor-deposited κ-type or θ-type Al 2 O 3 layer. in is subjected to a heat treatment under the conditions of the above (b), when the transforming the the Al 2 O 3 layer of the deposition κ-type or θ-type crystal structure in the Al 2 O 3 layer of α-type crystal structure, the transformation TiO X layer formed on the surface of the front of the Al 2 O 3 layer, the transformation and acts to simultaneously start over the entire surface of the Al 2 O 3 layer, the over time the Al 2 O 3 layer Cracks that occur due to volume shrinkage due to transformation from the κ-type or θ-type crystal structure to the α-type crystal structure of the Al 2 O 3 layer because it takes a transformation form that proceeds from the surface to the inside. is, extremely fine, and in addition to a state of being uniformly dispersed distributed throughout the layer, the the Al 2 O 3 layer after metamorphosis Kicking equivalent crystal orientation having crystal orientation even κ type before transformation or θ type the Al 2 O 3 layer, or a change in crystal orientation becomes extremely small, the heating transformation α-type Al 2 O This result formed The three layers have excellent high-temperature strength equivalent to the high-temperature strength of κ-type or θ-type Al 2 O 3 layers before heat transformation as well as excellent high-temperature hardness and heat resistance of α-type crystal structure. Therefore, in a coated BN-based tool in which the upper layer of the hard coating layer is composed of the heat-transformed α-type Al 2 O 3 layer and the lower layer is composed of the Ti compound layer, a particularly severe mechanical and thermal shock is involved. Since the heat-transformed α-type Al 2 O 3 layer exhibits excellent chipping resistance in addition to excellent high-temperature hardness and heat resistance even in high-speed intermittent cutting, it is possible to achieve high-temperature strength with the Ti compound layer. Combined with coexistence, hard coating layer Occurrence of chipping is significantly suppressed, and excellent wear resistance is exhibited over a long period of time.
（ｄ）上記の従来蒸着α型Ａｌ2Ｏ3層および上記（ｃ）の加熱変態α型Ａｌ2Ｏ3層について、
電界放出型走査電子顕微鏡を用い、図１（ａ），（ｂ）に概略説明図で示される通り、表面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、前記表面研磨面の法線に対して、前記結晶粒の結晶面である（０００１）面の法線がなす傾斜角を測定し、前記測定傾斜角のうち、０〜４５度の範囲内にある測定傾斜角を０．２５度のピッチ毎に区分すると共に、各区分内に存在する度数を集計してなる傾斜角度数分布グラフを作成した場合、前記従来の蒸着α型Ａｌ2Ｏ3層は、図３に例示される通り、（０００１）面の測定傾斜角の分布が０〜４５度の範囲内で不偏的な傾斜角度数分布グラフを示すのに対して、前記加熱変態α型Ａｌ2Ｏ3層は、図２に例示される通り、傾斜角区分の特定位置にシャープな最高ピークが現れ、このシャープな最高ピークは、ＴｉＯＸ層の平均層厚を変化させることによりグラフ横軸の傾斜角区分に現れる位置および高さが変わること。
(D) About the above-mentioned conventional vapor deposition α-type Al 2 O 3 layer and the heat-transformed α-type Al 2 O 3 layer of (c) above,
Using a field emission scanning electron microscope, as shown in the schematic explanatory diagrams in FIGS. 1A and 1B, an electron beam is individually applied to each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface. Irradiation is performed to measure the inclination angle formed by the normal line of the (0001) plane that is the crystal plane of the crystal grain with respect to the normal line of the surface-polished surface. When the measured inclination angle within the range is divided for each pitch of 0.25 degrees and the inclination angle number distribution graph is created by summing up the frequencies existing in each division, the conventional vapor deposition α-type Al 2 As illustrated in FIG. 3, the O 3 layer exhibits an unbiased inclination angle number distribution graph in the range of the measured inclination angle of the (0001) plane within the range of 0 to 45 degrees, whereas the heating transformation the α-type the Al 2 O 3 layer, sharp street, in a specific position of the tilt angle segment illustrated in FIG. 2 It appears high peak, the sharp highest peak changes that the position and height appear on the tilt angle sections of the graph the horizontal axis by changing the average layer thickness of the TiO X layer.
（ｅ）試験結果によれば、上記ＴｉＯＸ層を、上記の通り０．０５〜１μｍの平均層厚にすると、上記シャープな最高ピークが傾斜角区分の０〜１０度の範囲内に現れると共に、前記０〜１０度の範囲内に存在する度数の合計（この度数合計と前記最高ピークの高さは比例関係にある）が、傾斜角度数分布グラフにおける度数全体の４５％以上の割合を占める傾斜角度数分布グラフを示すようになり、この結果の傾斜角度数分布グラフで０〜１０度の範囲内の傾斜角度数の割合が４５％以上を占め、かつ前記０〜１０度の範囲内に傾斜角区分の最高ピークが現れる加熱変態α型Ａｌ2Ｏ3層を硬質被覆層の上部層として、下部層のＴｉ化合物層と共存した状態で蒸着形成してなる被覆ＢＮ系工具は、上記の従来被覆ＢＮ系工具に比して、特に高速断続切削で切刃部にチッピングの発生なく、一段とすぐれた耐摩耗性を発揮するようになること。
以上（ａ）〜（ｅ）に示される研究結果を得たのである。
(E) According to the test results, when the TiO X layer has an average layer thickness of 0.05 to 1 μm as described above, the sharp maximum peak appears in the range of 0 to 10 degrees of the tilt angle section. The total of the frequencies existing in the range of 0 to 10 degrees (the total frequency and the height of the highest peak are in a proportional relationship) occupy a ratio of 45% or more of the total frequencies in the inclination angle frequency distribution graph. An inclination angle number distribution graph is shown. In the resulting inclination angle number distribution graph, the ratio of the inclination angle number in the range of 0 to 10 degrees occupies 45% or more, and the range of 0 to 10 degrees is included. The coated BN-based tool formed by vapor deposition in the state of coexisting with the lower Ti compound layer, with the heat-transformed α-type Al 2 O 3 layer in which the highest peak of the tilt angle section appears as the upper layer of the hard coating layer, Especially high compared to conventional coated BN tools With high-speed interrupted cutting, there is no chipping at the cutting edge, and it has excellent wear resistance.
The research results shown in (a) to (e) above were obtained.
この発明は、上記の研究結果に基づいてなされたものであって、工具基体の表面に、
（ａ）下部層が、いずれも蒸着形成されたＴｉＣ層、ＴｉＮ層、ＴｉＣＮ層、ＴｉＣＯ層、およびＴｉＣＮＯ層のうちの１層または２層以上からなり、かつ２〜１５μｍの合計平均層厚を有するＴｉ化合物層、
（ｂ）上部層が、蒸着形成した状態でκ型またはθ型の結晶構造および０．５〜１０μｍの平均層厚を有するＡｌ2Ｏ3層の表面に、ＴｉＯＸ層を０．０５〜１μｍの平均層厚で蒸着形成した状態で、加熱処理を施して、前記κ型またはθ型の結晶構造を有するＡｌ2Ｏ3層の結晶構造をα型結晶構造に変態してなると共に、
電界放出型走査電子顕微鏡を用い、表面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、前記表面研磨面の法線に対して、前記結晶粒の結晶面である（０００１）面の法線がなす傾斜角を測定し、前記測定傾斜角のうち、０〜４５度の範囲内にある測定傾斜角を０．２５度のピッチ毎に区分すると共に、各区分内に存在する度数を集計してなる傾斜角度数分布グラフにおいて、０〜１０度の範囲内の傾斜角区分に最高ピークが存在すると共に、前記０〜１０度の範囲内に存在する度数の合計が、傾斜角度数分布グラフにおける度数全体の４５％以上の割合を占める傾斜角度数分布グラフを示す加熱変態α型Ａｌ2Ｏ3層、
以上（ａ）および（ｂ）で構成された硬質被覆層を形成してなる、硬質被覆層がすぐれた耐チッピング性を有する被覆ＢＮ系工具に特徴を有するものである。
This invention was made based on the above research results, and on the surface of the tool base,
(A) The lower layer is composed of one or more of the deposited TiC layer, TiN layer, TiCN layer, TiCO layer, and TiCNO layer, and has a total average layer thickness of 2 to 15 μm. Having a Ti compound layer,
(B) On the surface of an Al 2 O 3 layer having a κ-type or θ-type crystal structure and an average layer thickness of 0.5 to 10 μm in a state where the upper layer is formed by vapor deposition, a TiO X layer is 0.05 to 1 μm. In the state of vapor deposition with an average layer thickness of, heat treatment is performed to transform the crystal structure of the Al 2 O 3 layer having the κ-type or θ-type crystal structure into an α-type crystal structure,
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. A heat-transformed α-type Al 2 O 3 layer showing an inclination angle distribution graph in which the total frequency is 45% or more of the entire frequency in the inclination angle distribution graph,
The present invention is characterized by a coated BN-based tool having a hard chipping layer with excellent chipping resistance, which is formed by forming the hard cover layer formed of (a) and (b) above.
つぎに、この発明の被覆ＢＮ系工具の硬質被覆層の構成層について、上記の通りに数値限定した理由を以下に説明する。
（ａ）Ｔｉ化合物層（下部層）の平均層厚
Ｔｉ化合物層は、自体がα型Ａｌ2Ｏ3層に比して、相対的に高い高温強度を有し、これの存在によって硬質被覆層が高温強度を具備するようになるほか、工具基体と上部層である加熱変態α型Ａｌ2Ｏ3層のいずれにも強固に密着し、よって硬質被覆層の工具基体に対する密着性向上に寄与する作用をもつが、その合計平均層厚が２μｍ未満では、前記作用を十分に発揮させることができず、一方その合計平均層厚が１５μｍを越えると、特に高熱発生を伴なう高速断続切削で熱塑性変形を起し易くなり、これが偏摩耗の原因となることから、その合計平均層厚を２〜１５μｍと定めた。
Next, the reason why the constituent layers of the hard coating layer of the coated BN tool of the present invention are numerically limited as described above will be described below.
(A) Average thickness of the Ti compound layer (lower layer) The Ti compound layer itself has a relatively high high-temperature strength as compared with the α-type Al 2 O 3 layer, and the hard coating layer due to its presence. In addition to having high-temperature strength, it firmly adheres to both the tool base and the heat-transformed α-type Al 2 O 3 layer that is the upper layer, thereby contributing to improved adhesion of the hard coating layer to the tool base. However, if the total average layer thickness is less than 2 μm, the above-mentioned effect cannot be fully exerted. On the other hand, if the total average layer thickness exceeds 15 μm, the high-speed intermittent cutting accompanied by the generation of high heat is particularly important. Since it becomes easy to cause thermoplastic deformation, which causes uneven wear, the total average layer thickness was set to 2 to 15 μm.
（ｂ）ＴｉＯＸ層の平均層厚
ＴｉＯＸ層には、上記の通り蒸着κ型またはθ型Ａｌ2Ｏ3層の加熱変態α型Ａｌ2Ｏ3層への加熱変態に際して、前記変態をＡｌ2Ｏ3層表面全面に亘って同時的に開始させ、経時的にＡｌ2Ｏ3層の表面部から内部に進行する変態形態をとるようにする作用があるので、加熱変態時に体積収縮に伴なって発生する割れが層全体に亘って微細化および均一化するほか、変態後のＡｌ2Ｏ3層における結晶配向が変態前のκ型またはθ型Ａｌ2Ｏ3層のもつ結晶配向と同等、あるいは結晶配向に変化があってもきわめて小さなものとなり、さらに、前記ＴｉＯＸ層には、平均層厚を０．０５〜１μｍにすると、試験結果によれば、これに対応して、傾斜角度数分布グラフにおける０〜１０度の傾斜角区分範囲内に測定傾斜角の最高ピークが現れ、かつ前記０〜１０度の傾斜角区分内に存在する度数の合計割合が、傾斜角度数分布グラフにおける度数全体の４５％以上となる傾斜角度数分布グラフを示す作用があり、したがって、前記平均層厚が０．０５未満では、前記加熱変態α型Ａｌ2Ｏ3層の傾斜角度数分布グラフの０〜１０度の範囲内に現れるピーク高さが不十分、すなわち、前記０〜１０度の範囲内に存在する度数の合計割合が、傾斜角度数分布グラフにおける度数全体の４５％未満となってしまい、この場合上記の通り、前記加熱変態α型Ａｌ2Ｏ3層に所望のすぐれた高温強度を確保することができず、この結果耐チッピング性に所望の向上効果が得られず、一方その平均層厚が１μｍを越えると、最高ピークの現れる傾斜角区分が０〜１０度の範囲から外れてしまい、この場合も前記加熱変態α型Ａｌ2Ｏ3層に所望のすぐれた高温強度を確保することができないことから、その平均層厚を０．０５〜１μｍと定めた。
(B) The average layer thickness TiO X layer of TiO X layer, upon heating transformation to heat transformation α type the Al 2 O 3 layer of the street deposition κ type or θ-type the Al 2 O 3 layer, the transformation Al 2 O 3 layer starts over the entire surface at the same time, and has the effect of taking a transformation form that progresses from the surface of the Al 2 O 3 layer to the inside over time. In addition to the refinement and uniformity of cracks that occur throughout the layer, the crystal orientation in the Al 2 O 3 layer after transformation is equivalent to the crystal orientation of the κ-type or θ-type Al 2 O 3 layer before transformation. Or, even if there is a change in the crystal orientation, it becomes extremely small. Further, when the average layer thickness is 0.05 to 1 μm for the TiO X layer, according to the test result, the inclination angle is Inclination measured within 0 to 10 degree inclination angle range in number distribution graph An action of the inclination angle distribution graph in which the highest peak of the inclination angle appears and the total ratio of the frequencies existing in the inclination angle section of 0 to 10 degrees is 45% or more of the entire frequency in the inclination angle distribution graph. Therefore, when the average layer thickness is less than 0.05, the peak height that appears in the range of 0 to 10 degrees in the inclination angle number distribution graph of the heat-transformed α-type Al 2 O 3 layer is insufficient. The total ratio of the frequencies existing in the range of 0 to 10 degrees is less than 45% of the entire frequencies in the inclination angle distribution graph. In this case, as described above, the heat-transformed α-type Al 2 O 3 The desired excellent high-temperature strength cannot be ensured in the layer, and as a result, the desired improvement effect in chipping resistance cannot be obtained. On the other hand, when the average layer thickness exceeds 1 μm, the inclination angle section where the highest peak appears is 0-10 degree range In this case, too, the desired excellent high-temperature strength cannot be ensured in the heat-transformed α-type Al 2 O 3 layer, so the average layer thickness was set to 0.05 to 1 μm.
（ｃ）蒸着κ型またはθ型Ａｌ2Ｏ3層（上部層）の平均層厚
蒸着κ型またはθ型Ａｌ2Ｏ3層は、上記の通り加熱変態後にすぐれた高温硬さと耐熱性、さらに傾斜角区分：０〜１０度の範囲内に最高ピークが現れる傾斜角度数分布グラフを示し、すぐれた高温強度を具備する加熱変態α型Ａｌ2Ｏ3層となり、高速断続切削加工でもチッピングの発生なく、すぐれた耐摩耗性を発揮するが、その平均層厚が０．５μｍ未満では、所望の耐摩耗性を確保することができず、一方その平均層厚が１０μｍを越えて厚くなりすぎると、チッピングが発生し易くなることから、その平均層厚を０．５〜１０μｍと定めた。
(C) Average layer thickness of vapor-deposited κ-type or θ-type Al 2 O 3 layer (upper layer) The vapor-deposited κ-type or θ-type Al 2 O 3 layer has excellent high-temperature hardness and heat resistance after heat transformation as described above. Inclination angle classification: Shows an inclination angle number distribution graph in which the highest peak appears in the range of 0 to 10 degrees, and becomes a heat-transformed α-type Al 2 O 3 layer with excellent high-temperature strength, and chipping occurs even in high-speed intermittent cutting However, if the average layer thickness is less than 0.5 μm, the desired wear resistance cannot be ensured, while if the average layer thickness exceeds 10 μm, it is too thick. Since the chipping easily occurs, the average layer thickness is set to 0.5 to 10 μm.
なお、切削工具の使用前後の識別を目的として、黄金色の色調を有するＴｉＮ層を、必要に応じて硬質被覆層の最表面層として蒸着形成してもよいが、この場合の平均層厚は０．１〜１μｍでよく、これは０．１μｍ未満では、十分な識別効果が得られず、一方前記ＴｉＮ層による前記識別効果は１μｍまでの平均層厚で十分であるという理由からである。 In addition, for the purpose of identification before and after the use of the cutting tool, a TiN layer having a golden color tone may be vapor-deposited as the outermost surface layer of the hard coating layer as necessary, but the average layer thickness in this case is It may be 0.1 to 1 μm, and if the thickness is less than 0.1 μm, a sufficient discrimination effect cannot be obtained, while the discrimination effect by the TiN layer is sufficient for an average layer thickness of up to 1 μm.
この発明被覆ＢＮ系工具は、機械的熱的衝撃がきわめて高く、かつ高い発熱を伴なう鋼の高速断続切削でも、硬質被覆層の上部層を構成する加熱変態α型Ａｌ2Ｏ3層が、すぐれた高温硬さおよび耐熱性に加えて、すぐれた耐チッピング性を発揮することから、長期に亘ってすぐれた耐摩耗性を示すものである。 This invention-coated BN-based tool has a heat-transformed α-type Al 2 O 3 layer that constitutes the upper layer of the hard coating layer even in high-speed intermittent cutting of steel with extremely high mechanical thermal shock and high heat generation. Since it exhibits excellent chipping resistance in addition to excellent high temperature hardness and heat resistance, it exhibits excellent wear resistance over a long period of time.
つぎに、この発明の被覆ＢＮ系工具を実施例により具体的に説明する。 Next, the coated BN-based tool of the present invention will be specifically described with reference to examples.
原料粉末として、いずれも０．４〜５μｍの範囲内の平均粒径を有する立方晶窒化硼素（以下、ｃ−ＢＮで示す）粉末、炭化チタン（以下、ＴｉＣで示す）粉末、窒化チタン（以下、ＴｉＮで示す）粉末、炭窒化チタン（以下、ＴｉＣＮで示す）粉末、炭化タングステン（以下、ＷＣで示す）粉末、Ａｌ粉末、Ｃｏ粉末、ＴｉとＡｌの金属間化合物粉末であるＴｉ3Ａｌ粉末、ＴｉＡｌ粉末、およびＴｉＡｌ3粉末、さらに組成式：Ｔｉ2ＡｌＮを有する複合金属窒化物粉末、ＴｉＢ2粉末、窒化アルミニウム（以下、ＡｌＮで示す）粉末、硼化アルミニウム（以下、ＡｌＢ2で示す）粉末、酸化アルミニウム（Ａｌ2Ｏ3で示す）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８５時間湿式混合し、乾燥した後、１００ＭＰａの圧力で直径：５０ｍｍ×厚さ：１．５ｍｍの寸法をもった圧粉体にプレス成形し、ついでこの圧粉体を、圧力：１Ｐａの真空雰囲気中、９００〜１３００℃の範囲内の所定温度に６０分間保持の条件で焼結して切刃片用予備焼結体とし、この予備焼結体を、別途用意した、Ｃｏ：８質量％、ＷＣ：残りの組成、並びに直径：５０ｍｍ×厚さ：２ｍｍの寸法をもったＷＣ基超硬合金製支持片と重ね合わせた状態で、通常の超高圧焼結装置に装入し、通常の条件である圧力：５ＧＰａ、温度：１２００〜１４００℃の範囲内の所定温度に保持時間：０．８時間の条件で超高圧焼結し、焼結後上下面をダイヤモンド砥石を用いて研摩し、ワイヤー放電加工装置にて一辺３ｍｍの正三角形状に分割し、さらにＣｏ：５質量％、ＴａＣ：５質量％、ＷＣ：残りの組成およびＣＩＳ規格ＣＮＧＡ１２０４１２の形状（厚さ：４．７６mm×一辺長さ：１２．７mmの正三角形の各角部に中心角：８０°の円弧加工を施したもの）をもったＷＣ基超硬合金製チップ本体のろう付け部（コーナー部）に、質量％で、Ｃｕ：３０％、Ｚｎ：２８％、Ｎｉ：２％、Ａｇ：残りからなる組成を有するＡｇ合金のろう材を用いてろう付けし、所定寸法に外周加工した後、切刃部に幅：０．１５ｍｍ、角度：３５°のホーニング加工を施し、さらに仕上げ研摩を施すことによりＩＳＯ規格ＣＮＧＡ１２０４１２のチップ形状をもった工具基体Ａ〜Ｍをそれぞれ製造した。 As raw material powders, cubic boron nitride (hereinafter referred to as c-BN) powder, titanium carbide (hereinafter referred to as TiC) powder, titanium nitride (hereinafter referred to as “c-BN”) having an average particle diameter in the range of 0.4 to 5 μm. , TiN) powder, titanium carbonitride (hereinafter referred to as TiCN) powder, tungsten carbide (hereinafter referred to as WC) powder, Al powder, Co powder, Ti 3 Al intermetallic compound powder Ti 3 Al powder , TiAl powder, and TiAl 3 powder, further composition formula: composite metal nitride powder having Ti 2 AlN, TiB 2 powder, aluminum nitride (hereinafter referred to as AlN) powder, aluminum boride (hereinafter referred to as AlB 2 ) Powder and aluminum oxide (shown as Al 2 O 3 ) powder were prepared, these raw material powders were blended into the blending composition shown in Table 1, wet-mixed with a ball mill for 85 hours, and dried. Then, it was press-molded into a green compact having a diameter of 50 mm × thickness: 1.5 mm at a pressure of 100 MPa, and this green compact was then subjected to a pressure range of 900 to 1300 ° C. in a vacuum atmosphere of 1 Pa. The pre-sintered body for cutting edge pieces was sintered under the condition of holding at a predetermined temperature for 60 minutes, and this pre-sintered body was prepared separately, Co: 8% by mass, WC: remaining composition, and diameter : 50 mm x thickness: WC based cemented carbide support piece having a dimension of 2 mm, and placed in a normal ultra high pressure sintering apparatus, pressure: 5 GPa, temperature: Super high pressure sintering at a predetermined temperature in the range of 1200 to 1400 ° C. under the condition of holding time: 0.8 hour, and after sintering, the upper and lower surfaces are polished with a diamond grindstone, and 3 mm on a side by a wire electric discharge machine. Divided into equilateral triangles, Co: 5% by mass, TaC : 5 mass%, WC: remaining composition and shape of CIS standard CNGA120412 (thickness: 4.76 mm × one side length: 12.7 mm) Each corner of an equilateral triangle was subjected to arc machining with a central angle of 80 ° The brazing part (corner part) of the WC-based cemented carbide chip main body with a material has a composition consisting of Cu: 30%, Zn: 28%, Ni: 2%, and Ag: the rest. After brazing using a brazing material of Ag alloy and peripheral processing to a predetermined dimension, the cutting edge portion is subjected to honing processing with a width of 0.15 mm and an angle of 35 °, and further subjected to final polishing, thereby performing ISO polishing CNGA120204. Tool bases A to M having the following chip shapes were manufactured.
まず、これらの工具基体Ａ〜Ｍ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４に概略説明図で示される通常の物理蒸着装置であるアークイオンプレーティング装置に装入し、カソード電極（蒸発源）として金属Ｔｉを装着し、まず、装置内を排気して０．５Ｐａ以下の真空に保持しながら、ヒーターで装置内を３５０℃に加熱した後、Ａｒガスを装置内に導入して、４ＰａのＡｒ雰囲気とし、この状態で前記工具基体に−９５０Ｖの直流パルスバイアス電圧を印加し、前記工具基体表面をＡｒボンバード洗浄し、引続いて装置内に反応ガスとして窒素ガスを導入して２Ｐａの反応雰囲気とすると共に、前記工具基体に−４００Ｖの直流パルスバイアス電圧を印加し、前記カソード電極である金属Ｔｉ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、目標層厚：１μｍのＴｉＮ層を蒸着する表面予備処理を行った。
ついで、上記の表面予備処理後の工具基体Ａ〜Ｍのそれぞれの表面に、通常の化学蒸着装置を用い、表２（表２中のｌ−ＴｉＣＮは特開平６−８０１０号公報に記載される縦長成長結晶組織をもつＴｉＣＮ層の形成条件を示すものであり、これ以外は通常の粒状結晶組織の形成条件を示すものである）に示される条件にて、硬質被覆層の下部層としてＴｉ化合物層を、表３に示される組み合わせで、かつ目標層厚で蒸着形成し、ついで同じく表２に示される条件にて、結晶構造がκ型またはθ型のＡｌ2Ｏ3層を同じく表３に示される組み合わせで、かつ目標層厚で蒸着形成し、ついで前記蒸着κ型またはθ型のＡｌ2Ｏ3層の表面に、ＴｉＯＸ層を同じく表３に示される条件で表３に示される組み合わせで、かつ目標層厚で蒸着形成した状態で、これに１０ｋＰａのＡｒ雰囲気中、温度：１０７５℃に１０〜６０分の範囲内の所定の時間保持の条件で加熱処理を施して、前記κ型またはθ型の結晶構造のＡｌ2Ｏ3層をα型結晶構造のＡｌ2Ｏ3層に変態させて加熱変態α型Ａｌ2Ｏ3層としてなる上部層を形成することにより本発明被覆ＢＮ系工具１〜１３をそれぞれ製造した。
First, each of these tool bases A to M is ultrasonically cleaned in acetone and dried, and then loaded into an arc ion plating apparatus, which is a normal physical vapor deposition apparatus shown schematically in FIG. Then, metal Ti was attached as a cathode electrode (evaporation source), and the inside of the apparatus was first heated to 350 ° C. with a heater while maintaining a vacuum of 0.5 Pa or less, and then Ar gas was supplied to the apparatus. Introduced into a 4 Pa Ar atmosphere, a DC pulse bias voltage of −950 V is applied to the tool base in this state, the tool base surface is cleaned with Ar bombardment, and subsequently nitrogen as a reactive gas in the apparatus. A gas is introduced to form a reaction atmosphere of 2 Pa, a DC pulse bias voltage of −400 V is applied to the tool base, and the metal electrode Ti between the cathode electrode and the anode electrode is applied. By flowing a 100A current to generate arc discharge on the surface of the tool substrate with a target layer thickness: it was subjected to a surface pre-treatment of depositing a TiN layer of 1 [mu] m.
Next, a normal chemical vapor deposition apparatus was used for each surface of the tool bases A to M after the above surface pretreatment, and Table 2 (l-TiCN in Table 2 is described in JP-A-6-8010). Ti compound as a lower layer of the hard coating layer under the conditions shown in (1) shows the conditions for forming a TiCN layer having a vertically grown crystal structure, and (2) shows conditions for forming a normal granular crystal structure. The layers are formed by vapor deposition in the combinations shown in Table 3 and with the target layer thickness. Then, under the conditions shown in Table 2, Al 2 O 3 layers having a crystal structure of κ type or θ type are also shown in Table 3. The combinations shown in Table 3 were formed by vapor deposition with the target layer thickness and with the target layer thickness, and then the TiO X layer was formed on the surface of the vapor-deposited κ-type or θ-type Al 2 O 3 layer. And with the target layer thickness deposited. Then, the Al 2 O 3 layer having the κ-type or θ-type crystal structure is subjected to a heat treatment in a 10 kPa Ar atmosphere at a temperature of 1075 ° C. for a predetermined time within a range of 10 to 60 minutes. Were transformed into an Al 2 O 3 layer having an α-type crystal structure to form an upper layer as a heat-transformed α-type Al 2 O 3 layer, thereby producing the coated BN tools 1 to 13 of the present invention.
また、比較の目的で、表５に示される通り、硬質被覆層の上部層として同じく表２に示される条件で、同じく表４に示される目標層厚の蒸着α型Ａｌ2Ｏ3層を形成し、かつ上記のＴｉＯＸ層の形成および上記条件での加熱処理を行わない以外は同一の条件で従来被覆ＢＮ系工具１〜１３をそれぞれ製造した。 For the purpose of comparison, as shown in Table 5, an evaporated α-type Al 2 O 3 layer having the target layer thickness shown in Table 4 is also formed as the upper layer of the hard coating layer under the same conditions as shown in Table 2. In addition, conventionally coated BN-based tools 1 to 13 were manufactured under the same conditions except that the formation of the TiO X layer and the heat treatment under the above conditions were not performed.
ついで、上記の本発明被覆ＢＮ系工具と従来被覆ＢＮ系工具の硬質被覆層を構成する加熱変態α型Ａｌ2Ｏ3層と蒸着α型Ａｌ2Ｏ3層について、電界放出型走査電子顕微鏡を用いて、傾斜角度数分布グラフをそれぞれ作成した。
すなわち、上記傾斜角度数分布グラフは、上記の加熱変態α型Ａｌ2Ｏ3層および蒸着α型Ａｌ2Ｏ3層の表面を研磨面とした状態で、電界放出型走査電子顕微鏡の鏡筒内にセットし、前記研磨面に７０度の入射角度で１５ｋＶの加速電圧の電子線を１ｎＡの照射電流で、前記表面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に照射して、電子後方散乱回折像装置を用い、３０×５０μｍの領域を０．１μｍ／ｓｔｅｐの間隔で、前記表面研磨面の法線に対して、前記結晶粒の結晶面である（０００１）面の法線がなす傾斜角を測定し、この測定結果に基づいて、前記測定傾斜角のうち、０〜４５度の範囲内にある測定傾斜角を０．２５度のピッチ毎に区分すると共に、各区分内に存在する度数を集計することにより作成した。
Next, a field emission scanning electron microscope was used for the heat-transformed α-type Al 2 O 3 layer and the vapor-deposited α-type Al 2 O 3 layer constituting the hard coating layer of the above-described coated BN tool of the present invention and the conventional coated BN tool. Each of them was used to create an inclination angle number distribution graph.
That is, the inclination angle number distribution graph shows the inside of the column of the field emission scanning electron microscope in a state where the surfaces of the heat-transformed α-type Al 2 O 3 layer and the vapor-deposited α-type Al 2 O 3 layer are polished surfaces. And irradiating the polished surface with an electron beam having an acceleration voltage of 15 kV at an incident angle of 70 degrees with an irradiation current of 1 nA on each crystal grain having a hexagonal crystal lattice existing within the measurement range of the polished surface. Then, using an electron backscatter diffraction image apparatus, a region of 30 × 50 μm at a spacing of 0.1 μm / step is a (0001) plane which is the crystal plane of the crystal grain with respect to the normal line of the polished surface The inclination angle formed by the normal line is measured, and based on the measurement result, among the measurement inclination angles, the measurement inclination angle within the range of 0 to 45 degrees is divided for each pitch of 0.25 degrees, Created by counting the frequencies that exist in each category .
この結果得られた各種の加熱変態α型Ａｌ2 Ｏ3 層および蒸着α型Ａｌ2Ｏ3層の傾斜角度数分布グラフにおいて、（０００１）面が最高ピークを示す傾斜角区分、並びに０〜１０度の範囲内の傾斜角区分内に存在する傾斜角度数の傾斜角度数分布グラフ全体の傾斜角度数に占める割合をそれぞれ表３，４にそれぞれ示した。 In the inclination angle number distribution graphs of the various heat-transformed α-type Al 2 O 3 layers and vapor-deposited α-type Al 2 O 3 layers obtained as a result, the inclination angle division in which the (0001) plane shows the highest peak, and 0 to 10 Tables 3 and 4 show the ratio of the number of inclination angles existing in the inclination angle section within the degree range to the inclination angle number of the entire inclination angle number distribution graph, respectively.
上記の各種の傾斜角度数分布グラフにおいて、表３，４にそれぞれ示される通り、本発明被覆ＢＮ系工具の加熱変態α型Ａｌ2Ｏ3層は、いずれも（０００１）面の測定傾斜角の分布が０〜１０度の範囲内の傾斜角区分に最高ピークが現れ、かつ０〜１０度の範囲内の傾斜角区分内に存在する傾斜角度数の割合が４５％以上である傾斜角度数分布グラフを示すのに対して、従来被覆ＢＮ系工具の蒸着α−Ａｌ2Ｏ3層は、いずれも（０００１）面の測定傾斜角の分布が０〜４５度の範囲内で不偏的で、最高ピークが存在せず、０〜１０度の範囲内の傾斜角区分内に存在する傾斜角度数の割合も２５％以下である傾斜角度数分布グラフを示すものであった。
なお、図２は、本発明被覆ＢＮ系工具５の加熱変態α型Ａｌ2Ｏ3層の傾斜角度数分布グラフ、図３は、従来被覆ＢＮ系工具５の蒸着α型Ａｌ2Ｏ3層の傾斜角度数分布グラフをそれぞれ示すものである。
In the above-mentioned various inclination angle distribution graphs, as shown in Tables 3 and 4, each of the heat-transformed α-type Al 2 O 3 layers of the coated BN tool of the present invention has a measured inclination angle of the (0001) plane. An inclination angle number distribution in which the highest peak appears in the inclination angle section within the range of 0 to 10 degrees and the ratio of the inclination angle numbers existing in the inclination angle section within the range of 0 to 10 degrees is 45% or more. In contrast to the graph, the vapor deposition α-Al 2 O 3 layer of the conventional coated BN-based tool is all unbiased in the range of the measured inclination angle of the (0001) plane within the range of 0 to 45 degrees. The inclination angle number distribution graph in which no peak is present and the ratio of the inclination angle number existing in the inclination angle section within the range of 0 to 10 degrees is 25% or less is shown.
2 is an inclination angle number distribution graph of the heat-transformed α-type Al 2 O 3 layer of the coated BN-based tool 5 of the present invention, and FIG. 3 is a diagram of the deposited α-type Al 2 O 3 layer of the conventional coated BN-based tool 5. An inclination angle number distribution graph is shown, respectively.
また、この結果得られた本発明被覆ＢＮ系工具１〜１３および従来被覆ＢＮ系工具１〜１３について、これの硬質被覆層の構成層をオージェ分光分析装置で測定（層の縦断面を観察）したところ、前者ではいずれも目標組成と実質的に同じ組成を有するＴｉ化合物層と加熱変態α型Ａｌ2Ｏ3層、さらにＴｉＯＸ層からなることが確認された。一方後者でも、いずれも同じく目標組成と実質的に同じ組成を有するＴｉ化合物と蒸着α型Ａｌ2Ｏ3層からなることが確認された。さらに、これらの被覆ＢＮ系工具の硬質被覆層の構成層の厚さを走査型電子顕微鏡を用いて測定（同じく縦断面測定）したところ、いずれも目標層厚と実質的に同じ平均層厚（５点測定の平均値）を示した。 Moreover, about the present invention coated BN type tools 1 to 13 and the conventional coated BN type tools 1 to 13 obtained as a result, the constituent layers of the hard coating layer were measured with an Auger spectroscopic analyzer (observation of the longitudinal section of the layer). As a result, it was confirmed that the former consisted of a Ti compound layer having substantially the same composition as the target composition, a heat-transformed α-type Al 2 O 3 layer, and a TiO X layer. On the other hand, it was confirmed that both of the latter consisted of a Ti compound having the same composition as the target composition and a vapor-deposited α-type Al 2 O 3 layer. Furthermore, when the thickness of the constituent layer of the hard coating layer of these coated BN-based tools was measured using a scanning electron microscope (same longitudinal section measurement), the average layer thickness substantially the same as the target layer thickness ( Average value of 5-point measurement) was shown.
つぎに、上記の各種の被覆ＢＮ系工具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、本発明被覆ＢＮ系工具１〜１３および従来被覆ＢＮ系工具１〜１３について、
被削材：ＪＩＳ・ＳＣＭ４１５の浸炭焼入れ鋼（表面硬さ：ＨＲＣ５８）の長さ方向等間隔８本縦溝入り丸棒、
切削速度：２２０ｍ／ｍｉｎ、
切り込み：０．０５ｍｍ、
送り：０．１０ｍｍ／ｒｅｖ、
切削時間：１０分、
の条件（切削条件Ａ）での合金鋼の乾式高速断続切削試験（通常の切削速度は１２０ｍ／ｍｉｎ）、
被削材：ＪＩＳ・ＳＵＪ２の熱処理硬化鋼（表面硬さ：ＨＲＣ５７）の長さ方向等間隔８本縦溝入り丸棒、
切削速度：２００ｍ／ｍｉｎ、
切り込み：０．０８ｍｍ、
送り：０．０７ｍｍ／ｒｅｖ、
切削時間：１０分、
の条件（切削条件Ｂ）での高炭素鋼の乾式高速断続切削試験（通常の切削速度は１００ｍ／ｍｉｎ）、
被削材：ＪＩＳ・ＳＣｒ４２０の浸炭焼入れ鋼（表面硬さ：ＨＲＣ５３）の長さ方向等間隔８本縦溝入り丸棒、
切削速度：２１０ｍ／ｍｉｎ、
切り込み：０．０７ｍｍ、
送り：０．０５ｍｍ／ｒｅｖ、
切削時間：１２分、
の条件（切削条件Ｃ）でのＣｒ鋼の乾式高速断続切削試験（通常の切削速度は１２０ｍ／ｍｉｎ）を行い、いずれの切削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５に示した。
Next, the coated BN tools 1 to 13 of the present invention and the conventional coated BN tools 1 to 13 and the conventional coated BN tools 1 to 13 in the state where each of the various coated BN tools is screwed to the tip of the tool steel tool with a fixing jig. For 13,
Work material: JIS / SCM415 carburized hardened steel (surface hardness: HRC58), 8 longitudinally spaced round bars with equal intervals in the length direction,
Cutting speed: 220 m / min,
Cutting depth: 0.05mm,
Feed: 0.10 mm / rev,
Cutting time: 10 minutes,
Dry high-speed intermittent cutting test (normal cutting speed is 120 m / min) of alloy steel under the above conditions (cutting condition A),
Work material: JIS / SUJ2 heat-treated hardened steel (Surface hardness: HRC57) Eight equally spaced round bars with longitudinal grooves,
Cutting speed: 200 m / min,
Cutting depth: 0.08mm,
Feed: 0.07mm / rev,
Cutting time: 10 minutes,
Dry high-speed intermittent cutting test (normal cutting speed is 100 m / min) of high carbon steel under the above conditions (cutting condition B),
Work material: JIS / SCr420 carburized hardened steel (surface hardness: HRC53), 8 longitudinally spaced round bars with equal intervals in the length direction,
Cutting speed: 210 m / min,
Cutting depth: 0.07mm,
Feed: 0.05mm / rev,
Cutting time: 12 minutes,
The dry high-speed intermittent cutting test (normal cutting speed is 120 m / min) of Cr steel under the above conditions (cutting condition C), and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 5.
表４〜５に示される結果から、本発明被覆ＢＮ系工具１〜１３は、いずれも硬質被覆層の上部層が、（０００１）面の傾斜角が０〜１０度の範囲内の傾斜角区分で最高ピークを示すと共に、前記０〜１０度の傾斜角区分範囲内に存在する度数の合計割合が４５％以上を占める傾斜角度数分布グラフを示す加熱変態α型Ａｌ2Ｏ3層で構成され、機械的熱的衝撃がきわめて高く、かつ高い発熱を伴なう高硬度鋼の高速断続切削でも、硬質被覆層の上部層を構成する加熱変態α型Ａｌ2Ｏ3層が、すぐれた高温硬さおよび耐熱性に加えて、すぐれた耐チッピング性を発揮することから、切刃部のチッピング発生が著しく抑制され、すぐれた耐摩耗性を示すのに対して、硬質被覆層の上部層が、（０００１）面の測定傾斜角の分布が０〜４５度の範囲内で不偏的で、最高ピークが存在しない傾斜角度数分布グラフを示す蒸着α−Ａｌ2Ｏ3層で構成された従来被覆ＢＮ系工具１〜１３においては、いずれも高速断続切削では前記蒸着α−Ａｌ2Ｏ3層が激しい機械的熱的衝撃に耐えられず、切刃部にチッピングが発生し、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 to 5, according to the present invention coated BN-based tools 1 to 13, the upper layer of the hard coating layer has an inclination angle category in which the inclination angle of the (0001) plane is in the range of 0 to 10 degrees. In addition, it is composed of a heat-transformed α-type Al 2 O 3 layer showing an inclination angle number distribution graph in which the total ratio of frequencies existing in the 0 to 10 degree inclination angle range is 45% or more. Even in high-speed intermittent cutting of high-hardness steel with extremely high mechanical and thermal shock and high heat generation, the heat-transformed α-type Al 2 O 3 layer that forms the upper layer of the hard coating layer has excellent high-temperature hardness. In addition to the thickness and heat resistance, it exhibits excellent chipping resistance, so that the occurrence of chipping at the cutting edge is remarkably suppressed and excellent wear resistance is shown, whereas the upper layer of the hard coating layer is The distribution of the measured inclination angle of the (0001) plane is in the range of 0 to 45 degrees. In a unbiased manner, in the conventional coated BN type tool 1 to 13, which is composed of vapor-deposited α-Al 2 O 3 layers showing the inclination angle frequency distribution graph in which the highest peak does not exist, either the deposition in a high-speed intermittent cutting α- It is apparent that the Al 2 O 3 layer cannot withstand severe mechanical thermal shock, chipping occurs at the cutting edge, and the service life is reached in a relatively short time.
上述のように、この発明の被覆ＢＮ系工具は、各種鋼や鋳鉄などの通常の条件での連続切削や断続切削は勿論のこと、特に機械的熱的衝撃がきわめて高く、かつ高い発熱を伴なう切削条件の最も厳しい高硬度鋼などの高速断続切削でもすぐれた耐チッピング性を示し、長期に亘ってすぐれた切削性能を発揮するものであるから、切削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。 As described above, the coated BN-based tool of the present invention has extremely high mechanical thermal shock and high heat generation, as well as continuous cutting and intermittent cutting under normal conditions such as various steels and cast iron. It exhibits excellent chipping resistance even in high-speed interrupted cutting such as high-hardness steel with the most severe cutting conditions, 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 (1)
（ａ）下部層が、いずれも蒸着形成されたＴｉの炭化物層、窒化物層、炭窒化物層、炭酸化物層、および炭窒酸化物層のうちの１層または２層以上からなり、かつ２〜１５μｍの合計平均層厚を有するＴｉ化合物層、
（ｂ）上部層が、蒸着形成した状態でκ型またはθ型の結晶構造および０．５〜１０μｍの平均層厚を有する酸化アルミニウム層の表面に、酸化チタン層を０．０５〜１μｍの平均層厚で蒸着形成した状態で、加熱処理を施して、前記κ型またはθ型の結晶構造を有する酸化アルミニウム層の結晶構造をα型結晶構造に変態してなると共に、
電界放出型走査電子顕微鏡を用い、表面研磨面の測定範囲内に存在する六方晶結晶格子を有する結晶粒個々に電子線を照射して、前記表面研磨面の法線に対して、前記結晶粒の結晶面である（０００１）面の法線がなす傾斜角を測定し、前記測定傾斜角のうち、０〜４５度の範囲内にある測定傾斜角を０．２５度のピッチ毎に区分すると共に、各区分内に存在する度数を集計してなる傾斜角度数分布グラフにおいて、０〜１０度の範囲内の傾斜角区分に最高ピークが存在すると共に、前記０〜１０度の範囲内に存在する度数の合計が、傾斜角度数分布グラフにおける度数全体の４５％以上の割合を占める傾斜角度数分布グラフを示す加熱変態α型酸化アルミニウム層、
以上（ａ）および（ｂ）で構成された硬質被覆層を形成してなる硬質被覆層がすぐれた耐チッピング性を有する表面被覆立方晶窒化硼素系焼結材料製切削工具。 On the surface of the tool base made of cubic boron nitride-based sintered material,
(A) the lower layer is composed of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer formed by vapor deposition; and A Ti compound layer having a total average layer thickness of 2 to 15 μm,
(B) On the surface of an aluminum oxide layer having a kappa-type or θ-type crystal structure and an average layer thickness of 0.5 to 10 μm in the state where the upper layer is vapor-deposited, an average of 0.05 to 1 μm of titanium oxide layer In the state of vapor deposition with a layer thickness, heat treatment is performed to transform the crystal structure of the aluminum oxide layer having the κ-type or θ-type crystal structure into an α-type crystal structure,
Using a field emission scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the crystal grain is compared with the normal line of the surface polishing surface. The tilt angle formed by the normal line of the (0001) plane, which is the crystal plane, is measured, and among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, in the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 10 degrees and also exists within the range of 0 to 10 degrees. A heat-transformed α-type aluminum oxide layer showing a tilt angle number distribution graph in which the total frequency to be used occupies a ratio of 45% or more of the entire frequency in the tilt angle frequency distribution graph,
A cutting tool made of a surface-coated cubic boron nitride-based sintered material, wherein the hard coating layer formed by the hard coating layer constituted by (a) and (b) has excellent chipping resistance.
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