JP2004188501A - Cutting tool of surface-coated cermet with hard coating layer having excellent thermal shock resistance and surface lubrication property - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool of surface-coated cermet with a hard coating layer having excellent thermal shock resistance. <P>SOLUTION: This cutting tool is manufactured by forming surface coating on cemented carbide or a cermet base body. This surface coating is composed of (a) a primer layer of a Ti compound layer comprising one or a lamination of two or more layers among TiC, TiN, TiCN, TiCO, and TiCNO layers, having average thickness of 3-20μm, (b) an upper layer of an Al<SB>2</SB>O<SB>3</SB>layer having texture having an average layer thickness of 3-15μm, with α-type crystal structure formed by applying heat-transformation treatment to Al<SB>2</SB>O<SB>3</SB>of a κ-or θ-type crystal structure, in which cracks generated by heat transformation are dispersed and distributed, (c) a surface part layer of a Ti oxide layer having average layer thickness of 0.5-5μm, with X satisfying an atomic ratio of 1.2-1.9 as measured by an Auger spectrochemical analysis device at a thickness direction center part when represented by a formula: TiOx, and (d) an outermost surface color discrimination layer of a TiN layer having average layer thickness of 0.05-2μm. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００２３】
【表２】

【００２４】
【表３】

【００２５】
【表４】

【００２６】
【表５】

【００２７】
【表６】

【００２８】
【表７】

【００２９】
【発明の効果】
表５〜７に示される結果から、本発明被覆サーメット工具１〜１２は、硬質被覆層の上部層を構成する加熱変態α型Ａｌ_２Ｏ_３層中に分散分布する加熱変態生成クラックによるすぐれた熱衝撃吸収性および表面部層のＴｉ酸化物層のもつ切粉に対するすぐれた表面潤滑性の作用で、熱衝撃がきわめて高く、かつ高い発熱を伴なうステンレス鋼や軟鋼の高速断続切削でも、切刃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発揮するのに対して、硬質被覆層の上部層が蒸着α型Ａｌ_２Ｏ_３層からなる従来被覆サーメット工具１〜１２においては、高速断続切削では前記蒸着α型Ａｌ_２Ｏ_３層が激しい熱衝撃に耐えられず、かつ被削材がステンレス鋼や軟鋼などのきわめて粘性が高く、かつ切粉が切刃表面に溶着し易い難削材であることと相俟って、切刃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。
上述のように、この発明の被覆サーメット工具は、通常の条件での連続切削や断続切削は勿論のこと、特に熱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難削材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。
【図面の簡単な説明】
【図１】本発明被覆サーメット工具３の硬質被覆層を構成する加熱変態α型Ａｌ_２Ｏ_３層（目標層厚：１５μｍ）のＸ線回折チャートを示す図である。
【図２】本発明被覆サーメット工具７の硬質被覆層を構成する加熱変態α型Ａｌ_２Ｏ_３層（目標層厚：１０μｍ）のＸ線回折チャートを示す図である。
【図３】本発明被覆サーメット工具１１の硬質被覆層を構成する加熱変態α型Ａｌ_２Ｏ_３層（目標層厚：５μｍ）のＸ線回折チャートを示す図である。
【図４】従来被覆サーメット工具３の硬質被覆層を構成する蒸着α型Ａｌ_２Ｏ_３層（目標層厚：１５μｍ）のＸ線回折チャートを示す図である。
【図５】従来被覆サーメット工具７の硬質被覆層を構成する蒸着α型Ａｌ_２Ｏ_３層（目標層厚：１０μｍ）のＸ線回折チャートを示す図である。
【図６】従来被覆サーメット工具１１の硬質被覆層を構成する蒸着α型Ａｌ_２Ｏ_３層（目標層厚：５μｍ）のＸ線回折チャートを示す図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a hard coating layer that exhibits excellent thermal shock resistance to thermal shock repeatedly applied to the cutting edge at an extremely short pitch during high-speed interrupted cutting of steel, cast iron, etc., and more particularly, for stainless steel and mild steel. Even in high-speed interrupted cutting of difficult-to-cut materials that are extremely viscous and chips easily adhere to the cutting edge surface, the hard coating layer shows excellent surface lubricity against chips, so ordinary steel and cast iron Needless to say, when used for high-speed intermittent cutting of difficult-to-cut materials such as stainless steel and mild steel, surfaces that exhibit excellent cutting performance over a long period of time without chipping (small chipping) on the cutting edge The present invention relates to a coated cermet cutting tool (hereinafter, referred to as a coated cermet tool).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, generally, a substrate (hereinafter, these are collectively referred to as a tool substrate) formed of a tungsten carbide (hereinafter, referred to as WC) -based cemented carbide or a titanium cermet (hereinafter, referred to as TiCN) -based cermet is generally provided on a surface of the substrate. ,
(A) As a lower layer, a layer of Ti carbide (hereinafter referred to as TiC) having an average layer thickness of 3 to 20 μm, all of which are formed by chemical vapor deposition and / or physical vapor deposition (hereinafter simply referred to as vapor deposition). , A nitride (hereinafter also referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbonate (hereinafter referred to as TiCO) layer, and a carbonitride (hereinafter referred to as TiCNO) layer A Ti compound layer composed of one or two or more layers,
(B) as an upper layer, an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer having an average layer thickness of 3 to 15 μm and having an α-type and / or κ-type crystal structure formed by vapor deposition;
A coated cermet tool formed by vapor-depositing a hard coating layer composed of (a) and (b) above is known, and this coated cermet tool can be used for continuous cutting or intermittent cutting of various types of steel or cast iron, for example. It is also known that it is used (for example, see Patent Document 1).
[0003]
In general, the Ti compound layer and the Al ₂ O ₃ layer constituting the hard coating layer of the above-mentioned coated cermet tool have a granular crystal structure, and the TiCN layer constituting the Ti compound layer is further improved in strength by itself. With the use of a mixed gas containing an organic carbonitride as a reaction gas in a normal chemical vapor deposition apparatus, a chemical vapor deposition is performed at a medium temperature range of 700 to 950 ° C. to form a vertically elongated crystal structure. It is also known to do so (for example, see Patent Document 2).
[0004]
[Patent Document 1]
JP-A-6-31503 [Patent Document 2]
JP-A-6-8010 [0005]
[Problems to be solved by the invention]
In recent years, the performance of cutting equipment has been remarkably improved, but on the other hand, there has been a strong demand for labor saving, energy saving, and further cost reduction for cutting work.Accordingly, cutting work has tended to be further accelerated. In the case of coated cermet tools, there is no problem if this is used for continuous cutting or interrupted cutting under ordinary conditions such as steel or cast iron. When used for high-speed interrupted cutting, in which thermal shock is repeatedly applied at a very short pitch to the surface, the Al ₂ O ₃ layer constituting the upper layer of the hard coating layer is hard and excellent in heat resistance, but is brittle to thermal shock. In addition, chipping (minute chipping) easily occurs in the hard coating layer, and in high-speed interrupted cutting of work materials such as stainless steel and mild steel having extremely high viscosity, the chips of these work materials are hard coated. For particularly high affinity for the Al ₂ O ₃ layer constituting the, easily welded to the cutting edge surface, I the welding behavior the repeated thermal shock phenomenon coupled with the, further chipping occurs in the cutting edge Under the present circumstances, it becomes easy to use, and as a result, the service life is reached in a relatively short time.
[0006]
[Means for Solving the Problems]
In view of the above, the inventors of the present invention have proposed cutting, even in high-speed intermittent cutting of difficult-to-cut materials such as the above-mentioned stainless steel and mild steel, which are extremely viscous and in which cutting chips easily adhere to the cutting blade surface. As a result of conducting research to develop a coated cermet tool with excellent chipping resistance,
After forming the Ti compound layer as a lower layer on the surface of the tool base under normal conditions, an Al ₂ O ₃ layer having a κ-type or θ-type crystal structure is formed by vapor deposition under the same normal conditions. When heat treatment is performed in this state, preferably in an Ar atmosphere at a temperature of 1000 ° C. or higher and maintained for a predetermined time, the κ-type or θ-type crystal structure is transformed into an α-type crystal structure, and the heat transformation is performed. The generated cracks have a structure in which the cracks are dispersed and distributed in the layer. As a result, in the heat-transformed α-type Al ₂ O ₃ layer, the heat-transformed generated cracks are dispersed and distributed in the layer. The type Al ₂ O ₃ layer is used as the upper layer, and the surface of this upper layer is
The reaction gas composition, by volume%,
TiCl _4: 0.2~10%,
CO ₂ : 0.1 to 10%,
Ar: 5 to 60%,
H ₂ : remaining,
And
Reaction atmosphere temperature: 800 to 1100 ° C,
Reaction atmosphere pressure: 4 to 70 kPa (30 to 525 torr),
Under the conditions described above, an average layer thickness of 0.5 to 5 μm was obtained, and the center in the thickness direction was measured by an Auger spectroscopic analyzer, and the ratio of oxygen to Ti was 1.2 to 1. 9, that is,
Composition formula: TiO _X ,
When represented by
X: 1.2 to 1.9 in atomic ratio to Ti;
When a Ti oxide layer satisfying the following conditions is formed by vapor deposition as a surface portion layer, the Ti oxide layer sufficiently penetrates into the heat transformation generation crack at the interface with the heat transformation α-type Al ₂ O ₃ layer, and In addition to maintaining the heat transformation cracks in a significantly stabilized state, it also has a very low affinity for highly viscous and difficult-to-cut materials such as stainless steel and mild steel. Therefore, a coated cermet tool in which the lower layer of the hard coating layer is composed of the Ti compound layer, and the upper layer and the surface layer are composed of the above-mentioned heat-transformed α-type Al ₂ O ₃ layer and the Ti oxide layer in the heating transformation product cracks dispersed distributed heating transformation α type the Al ₂ O ₃ layer which constitutes the top layer, in particular absorb severe thermal shock during high-speed intermittent cutting, loose this In addition, since the Ti oxide layer of the surface layer has a property that chips are not easily welded, that is, has excellent surface lubricity, it has been found that chipping in the hard coating layer is significantly suppressed. It was.
[0007]
In the resulting coated cermet tool, the heat-transformed α-type Al ₂ O ₃ layer of the upper layer and the Ti oxide layer of the surface layer, both of which constitute the hard coating layer, have a gray-black color tone. Since it is difficult to visually identify the tool before and after using the tool, a titanium nitride (hereinafter, referred to as TiN) layer having a golden color tone as its outermost surface color discriminating layer is set to 0. It is also necessary to vapor-deposit with an average layer thickness of 0.05 to 2 μm so that color discrimination before and after use of the tool can be easily performed.
[0008]
The present invention has been made on the basis of the above research results, and has a tool base formed of a WC-based cemented carbide or a TiCN-based cermet,
(A) The lower layer has an average layer thickness of 3 to 20 μm, and is a stack of one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, all of which are formed by vapor deposition. A Ti compound layer comprising:
(B) As the upper layer, Al ₂ O ₃ having an average layer thickness of 3 to 15 μm and having a κ-type or θ-type crystal structure in a vapor-deposited state is subjected to a heat transformation treatment to change the crystal structure to an α-type crystal. A heat-transformed α-type Al ₂ O ₃ layer having a structure and a structure in which heat-transformed cracks are dispersed and distributed;
(C) The surface layer has an average layer thickness of 0.5 to 5 μm, and
Composition formula: TiO _X ,
When represented by, the center in the thickness direction is measured with an Auger spectrometer,
X: 1.2 to 1.9 in atomic ratio to Ti;
A Ti oxide layer that satisfies
(D) a vapor-deposited TiN layer having an average layer thickness of 0.05 to 2 μm as an outermost surface color identification layer;
The coated cermet tool having the excellent thermal shock resistance and surface lubricity of the hard coating layer formed by forming the hard coating layer composed of (a) to (d) above is characterized.
[0009]
Next, the reason why the average thickness of the constituent layers of the hard coating layer of the coated cermet tool of the present invention is limited as described above will be described.
(A) Lower layer (Ti compound layer)
The Ti compound layer itself has strength, and the presence of the Ti compound layer allows the hard coating layer to have strength. In addition, the Ti compound layer is firmly attached to both the tool base and the heating-transformed α-type Al ₂ O ₃ layer as the upper layer. Has a function of contributing to the improvement of the adhesion of the hard coating layer to the tool base, but if the average layer thickness is less than 3 μm, the above effect cannot be sufficiently exerted. If it exceeds 20 μm, it becomes easy to cause thermoplastic deformation especially in high-speed interrupted cutting accompanied by high heat generation, which causes uneven wear. Therefore, the average layer thickness is set to 3 to 20 μm.
[0010]
(B) Upper layer (heat-transformed α-type Al ₂ O ₃ layer)
The heat-transformed α-type Al ₂ O ₃ layer improves the abrasion resistance of the hard coating layer due to the high hardness and excellent heat resistance of Al ₂ O ₃ itself, and as described above, the heat transformed dispersed and distributed in the layer. The effect of the generated cracks absorbs the thermal shock and has the effect of significantly suppressing the occurrence of chipping in the hard coating layer. However, if the average layer thickness is less than 3 μm, the above effect cannot be sufficiently exerted. On the other hand, if the average layer thickness exceeds 15 μm and becomes too thick, the cracks generated by the heat transformation may cause chipping. Therefore, the average layer thickness is set to 3 to 15 μm.
[0011]
(C) Surface layer (Ti oxide layer)
As described above, the Ti oxide layer sufficiently penetrates into the heat transformation generation cracks at the interface with the heat transformation α-type Al ₂ O ₃ layer to maintain the heat transformation formation cracks in a significantly stabilized state. In addition to having the effect of sufficiently exhibiting the improvement in thermal shock resistance brought about by the above-mentioned heat-transformed α-type Al ₂ O ₃ layer, it also has excellent surface lubricity, but if its average layer thickness is less than 0.5 μm, In addition, the stabilization of cracks generated by heating transformation in the heating transformed α-type Al ₂ O ₃ layer is not only insufficient, but the desired surface lubricity cannot be secured, so that chipping is likely to occur, On the other hand, the effect of the Ti oxide layer is sufficient when the average layer thickness is up to 5 μm, and the average layer thickness is determined to be 0.1 to 5 μm in consideration of economy.
Further, the atomic ratio (X value) of oxygen (O) to Ti in the Ti oxide layer constituting the surface layer is set to 1.2 to 1.9 when the value is less than 1.2. When the value exceeds 1.9, pores are apt to be formed in the layer, and it is difficult to form a sound surface layer stably. It is.
[0012]
(D) Outermost surface color identification layer (TiN layer)
As described above, since the TiN layer has a golden color tone, if this is formed by vapor deposition as the outermost surface layer, after the tool is used, if the tool has, for example, a throw-away tip shape, it is mainly cut off. The cutting edge ridge where the rake face and flank of the blade intersect and the hard coating layer of the flank and rake face near the cutting edge ridge are worn by cutting, the TiN layer disappears, and other The portion not directly involved in cutting does not wear, and the TiN layer having the golden color tone is present, so that it is easy to visually discriminate before and after use of the tool. If it is less than 0.05 μm, the desired color tone cannot be ensured, while if the average layer thickness exceeds 2 μm and becomes too thick, the above-mentioned surface layer (Ti oxide layer) improves the surface lubricity. Is rapidly spoiled Therefore, the average layer thickness was determined to be 0.05 to 2 μm.
[0013]
Further, when the Ti oxide layer constituting the hard coating layer of the coated cermet tool of the present invention was observed by X-ray diffraction, Ti ₂ O ₃ and Ti ₃ O ₅ were obtained in accordance with the X value of the composition formula: TiO _X. , Ti ₄ O ₇ , and Ti ₅ O ₉ show a diffraction pattern in which a main peak appears in at least one of them. From these diffraction results, the Ti oxide layer is composed of a material called a Magneli phase, and is generally it is clear that those represented by Ti _n O _2n-1.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the coated cermet tool of the present invention will be specifically described with reference to examples.
As raw material powders, WC powder, TiC powder both having an average particle size of 1 to 3 [mu] m, ZrC powder, VC powder, TaC powder, NbC powder, _Cr 3 _{C 2} powder, TiN powder, prepared TaN powder and Co powder, Then, these raw material powders were blended into the blending composition shown in Table 1, further added with wax, ball-milled in acetone for 24 hours, dried under reduced pressure, and then pressed into a green compact of a predetermined shape at a pressure of 98 MPa. Then, this green compact is vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour, and after sintering, the cutting edge is honed with R: 0.07 mm. By processing, tool bases A to F made of a WC-based cemented carbide having a throw-away tip shape specified in ISO-CNMG120408 were manufactured, respectively.
[0015]
Further, as raw material powders, TiCN (TiC / TiN = 50/50 by mass ratio) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder each having an average particle diameter of 0.5 to 2 μm , Co powder, and Ni powder are prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet-mixed in a ball mill for 24 hours, dried, and pressed into a green compact at a pressure of 98 MPa. The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after sintering, the cutting edge was subjected to a honing process of R: 0.07 mm to obtain an ISO. Tool bases a to f made of TiCN-based cermet having a tip shape of standard CNMG120412 were formed.
[0016]
Then, on the surfaces of the tool bases A to F and the tool bases a to f, a conventional chemical vapor deposition apparatus was used, and Table 3 (l-TiCN in Table 3 is a vertically long sheet described in JP-A-6-8010). It shows the conditions for forming a TiCN layer having a growth crystal structure, and the other conditions show the conditions for forming a normal granular crystal structure.) A compound layer was formed by vapor deposition as a lower layer of the hard coating layer, and then a κ-type or θ-type Al ₂ O ₃ layer was formed by vapor deposition under the same conditions as shown in Table 3, and the layer was formed in an Ar atmosphere at a temperature of: A heat transformation treatment is performed at a temperature of 1050 ° C. for a predetermined time within a range of 2 to 10 hours to transform the κ-type or θ-type crystal structure into an α-type. also the heating transformation α-type _Al 2 _{O 3} layer distributed Forming the upper layer of the hard coating layer with the target layer thickness shown in Table 5, and further forming the Ti oxide layer having the target layer thickness shown in Table 4 under the conditions shown in Table 4 as the same surface layer Produced the coated cermet tools 1 to 12 of the present invention.
Also, for comparison purposes, as shown in Table 6, the upper layer of the hard coating layer was an evaporated α-type Al ₂ O ₃ layer having an average layer thickness also shown in Table 6, and the surface layer was not formed. Manufactured the conventional coated cermet tools 1 to 12 under the same conditions.
[0017]
Further, X-ray diffraction was performed to observe the difference between 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 coated cermet tool of the present invention and the conventional coated cermet tool. It was measured.
In the measurement of these X-ray diffractions, a single crystal WC having diffraction peaks only on the (001) plane and the (002) plane on the X-ray diffraction chart was used as a substrate sample, and the surface of the substrate sample was coated with the coated cermet of the present invention. The target layer thickness of the tools 3, 7, and 11 is 15 μm, 10 μm, and 5 μm, and the heat-transformed α-type Al ₂ O ₃ layer, and the target layer thickness of the conventional coated cermet tools 3, 7, and 11 are also 15 μm, 10 μm. and under the same conditions as the conditions for forming the deposited α-type _{the Al} 2 _{O 3} layer of 5 [mu] m, the target layer thickness each 15 [mu] m, 10 [mu] m, and 5 [mu] m heating transformation α type _{the Al} 2 _{O 3} layer and deposition α type _{the Al} 2 _{O 3} layer of Are directly formed to produce the coated samples A to C of the present invention and the conventionally coated samples a to c, and the X-ray diffraction of the heat-transformed α-type Al ₂ O ₃ layer and the vapor-deposited α-type Al ₂ O ₃ layer of these coated samples To It was carried out by a constant. The measurement results are shown in FIGS.
FIGS. 1 to 3 show X-ray diffraction charts of the heat-transformed α-type Al ₂ O ₃ layers of coating samples A to C of the present invention, and X-ray diffraction charts of vapor-deposited α-type Al ₂ O ₃ layers of conventional coating samples a to c. 4 to 6, the heating-transformed α-type Al ₂ O ₃ layer shows clear diffraction peaks on the (006) plane and the (018) plane, whereas the vapor-deposited α-type Al ₂ the O ₃ layer is clear that these (006) plane and (018) diffraction peak at a surface are not present.
Further, a heat-transformed α-type Al ₂ O ₃ layer and a vapor-deposited α-type Al ₂ O ₃ layer having target layer thicknesses of 15 μm, 10 μm, and 5 μm, respectively, are directly formed on the surface of the base sample composed of the single crystal WC. Each of the heat-transformed α-type Al ₂ O ₃ layer and the vapor-deposited α-type Al ₂ O ₃ layer of the coated samples A to C of the present invention and the conventionally coated samples a to c, Electron backscatter diffraction (EBSD) of the crystal plane was performed using a thermal field emission scanning electron microscope (manufactured by JEOL Ltd.) and an azimuthal diffractometer (manufactured by Texem Laboratories, Inc.). In each of the heat-transformed α-type Al ₂ O ₃ layers, the crystal orientation map shows a dark red color tone, which is due to the hexagonal (0001) plane (hexagonal parallel plane), which is the crystal structure of Al ₂ O _3. said Al Indicates that the relative O ₃ layer surface (the substrate surface of the sample) are oriented parallel to very strong, whereas the in the deposition α type the Al ₂ O ₃ layer, either green or blue crystal orientation map, further yellow and pink Various color tones, such as colors, appear, indicating that the crystal planes constituting the hexagonal crystal have no specific orientation.
[0018]
Further, with respect to the coated cermet tools 1 to 12 of the present invention and the conventional coated cermet tools 1 to 12 obtained as a result, the constituent layers of the hard coating layer were observed using a scanning electron microscope (observing the longitudinal section of the layers). As a result, in the former, all consisted of a Ti compound layer, a heat-transformed α-type Al ₂ O ₃ layer in which cracks generated by heat transformation were dispersed and distributed in the layer, a Ti oxide layer, and a TiN layer. And a vapor-deposited α-type Al ₂ O ₃ layer. When the TiN layer of the outermost surface color discrimination layer was observed using an Auger spectroscopic analyzer, the diffusion oxygen from the Ti oxide layer of the surface layer was found.
Further, the oxygen content ratio (X value) of the surface layer of the above-mentioned coated cermet tools 1 to 12 of the present invention in the center in the thickness direction was measured using an Auger spectrometer, and the target shown in Table 4 was obtained. The value was substantially the same as the value.
In addition, when the thicknesses of the constituent layers of the hard coating layer of these coated cermet tools were measured using a scanning electron microscope (also in the longitudinal section), the average layer thickness was substantially the same as the target layer thickness. (Average value of five-point measurements).
[0019]
Next, the above coated cermet tools 1 to 6 of the present invention and the conventional coated cermet tools 1 to 6 in a state where each of the above various coated cermet tools was screwed to the tip of a tool steel tool with a fixing jig, ,
Work material: Round bar with four vertical grooves at equal intervals in the length direction of JIS / SUS304,
Cutting speed: 350m / min,
Cut: 1.5 mm,
Feed: 0.15 mm / rev,
Cutting time: 3 minutes,
Dry high-speed intermittent cutting test of stainless steel under the conditions of
Work material: JIS S15C lengthwise round bar
Cutting speed: 350m / min,
Cut: 2.5mm,
Feed: 0.15 mm / rev,
Cutting time: 3 minutes,
A dry high-speed interrupted cutting test of mild steel was performed under the following conditions.
[0020]
Further, for the coated cermet tools 7 to 12 of the present invention and the conventional coated cermet tools 7 to 12,
Work material: Round bar with four vertical grooves at equal intervals in the length direction of JIS / SUS304,
Cutting speed: 350m / min,
Cut: 1.0 mm,
Feed: 0.15 mm / rev,
Cutting time: 3 minutes,
Dry high-speed intermittent cutting test of stainless steel under the conditions of
Work material: JIS S15C lengthwise round bar
Cutting speed: 350m / min,
Cut: 1.5 mm,
Feed: 0.15 mm / rev,
Cutting time: 3 minutes,
A dry high-speed intermittent cutting test was performed on mild steel under the following conditions, and the flank wear width of the cutting edge was measured in each cutting test. Table 7 shows the measurement results.
[0022]
[Table 1]

[0023]
[Table 2]

[0024]
[Table 3]

[0025]
[Table 4]

[0026]
[Table 5]

[0027]
[Table 6]

[0028]
[Table 7]

[0029]
【The invention's effect】
From the results shown in Tables 5 to 7, the coated cermet tools 1 to 12 of the present invention were excellent due to the heat transformation generation cracks distributed and distributed in the heat transformation α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer. The effect of thermal shock absorption and excellent surface lubrication on the chips of the Ti oxide layer on the surface layer makes it possible to cut stainless steel and mild steel with extremely high thermal shock and high heat even at high-speed interrupted cutting. The conventional coated cermet tools 1 to 12 in which the upper layer of the hard coating layer is formed of a vapor-deposited α-type Al ₂ O ₃ layer, while chipping of the cutting edge is significantly suppressed and exhibit excellent wear resistance, In high-speed intermittent cutting, the deposited α-type Al ₂ O ₃ layer cannot withstand severe thermal shock, the work material is extremely viscous, such as stainless steel or mild steel, and it is difficult for chips to adhere to the cutting blade surface. In cutting materials What it coupled with, chipping occurs in the cutting edge, it is clear that lead to a relatively short time service life.
As described above, the coated cermet tool of the present invention can be used not only for continuous cutting and interrupted cutting under normal conditions, but also for particularly difficult cutting materials with extremely high thermal shock and cutting conditions accompanied by high heat generation. It shows excellent chipping resistance even in high-speed interrupted cutting, and exhibits excellent cutting performance over a long period of time. It can be satisfied enough.
[Brief description of the drawings]
FIG. 1 is a view showing an X-ray diffraction chart of a heat-transformed α-type Al ₂ O ₃ layer (target layer thickness: 15 μm) constituting a hard coating layer of the coated cermet tool 3 of the present invention.
FIG. 2 is a view showing an X-ray diffraction chart of a heat-transformed α-type Al ₂ O ₃ layer (target layer thickness: 10 μm) constituting a hard coating layer of the coated cermet tool 7 of the present invention.
FIG. 3 is an X-ray diffraction chart of a heat-transformed α-type Al ₂ O ₃ layer (target layer thickness: 5 μm) constituting a hard coating layer of the coated cermet tool 11 of the present invention.
FIG. 4 is an X-ray diffraction chart of a vapor-deposited α-type Al ₂ O ₃ layer (target layer thickness: 15 μm) constituting a hard coating layer of the conventional coated cermet tool 3.
FIG. 5 is an X-ray diffraction chart of a vapor-deposited α-type Al ₂ O ₃ layer (target layer thickness: 10 μm) constituting a hard coating layer of the conventional coated cermet tool 7.
FIG. 6 is a diagram showing an X-ray diffraction chart of a vapor-deposited α-type Al ₂ O ₃ layer (target layer thickness: 5 μm) constituting a hard coating layer of the conventional coated cermet tool 11.

Claims (1)

On the surface of a tool substrate composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) As a lower layer, it has an average layer thickness of 3 to 20 μm, and is formed of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer, all of which are formed by evaporation. A Ti compound layer composed of one or two or more layers of
(B) As an upper layer, aluminum oxide having an average layer thickness of 3 to 15 μm and having a κ-type or θ-type crystal structure in a vapor-deposited state is subjected to a heat transformation treatment to change the crystal structure to an α-type crystal structure. Heat transformation α-type aluminum oxide layer having a structure in which heat transformation generated cracks are dispersed and distributed,
(C) The surface layer has an average layer thickness of 0.5 to 5 μm, and
Composition formula: TiO _X ,
When represented by, the center in the thickness direction is measured with an Auger spectrometer,
X: 1.2 to 1.9 in atomic ratio to Ti;
A Ti oxide layer that satisfies
(D) a vapor-deposited titanium nitride layer having an average layer thickness of 0.05 to 2 μm as an outermost surface color identification layer;
A cutting tool made of a surface-coated cermet having a hard coating layer having excellent thermal shock resistance and surface lubricity, wherein the cutting tool is formed by forming the hard coating layer constituted by (a) to (d) above.

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