JP2004299022A - Surface coated cermet cutting tool having hard coated layer exhibiting superior heat and impact resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cermet cutting tool having a hard coated layer exhibiting superior heat and impact resistance. <P>SOLUTION: This cutting tool is so formed that (a) a lower layer, (b) an upper layer and (c) the hard coated layer are formed on the surface of a tool base body comprising WC-group cemented carbide or TiCN-group cermet. The lower layer comprises a single layer or more layers of Ti compound layer formed by chemical vapor deposition and having the mean total layer thickness of 0.5-20 μm. The upper layer comprises a composite double α type Al<SB>2</SB>O<SB>3</SB>layer constituted of a lower side layer, which has a structure having a specific crystal structure under a state formed by the chemical vapor deposition and dispersedly distributed with transformation cracks formed by heating and a heat transformation α type Al<SB>2</SB>O<SB>3</SB>layer with the mean layer thickness of 1-20 μm; and an upper side layer of a vapor deposition α type Al<SB>2</SB>O<SB>3</SB>layer having an α type crystal structure under a state formed by the chemical vapor deposition and having the means layer thickness of 0.1-2 μm. The hard coated layer comprises a surface layer of Ti oxide layer formed by vapor deposition, satisfying a specific composition formula: TiO<SB>x</SB>, and having the mean layer thickness of 0.1-3 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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【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の下側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、特に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ないことから、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、通常の条件での各種鋼や鋳鉄など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ステンレス鋼や軟鋼などの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の硬質被覆層の上部層を構成する下側層に相当する目標層厚が１５μｍの加熱変態α型Ａｌ_２Ｏ_３層の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６の硬質被覆層の上部層を構成する下側層に相当する目標層厚が１０μｍの加熱変態α型Ａｌ_２Ｏ_３層の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９の硬質被覆層の上部層を構成する下側層に相当する目標層厚が５μｍの加熱変態α型Ａｌ_２Ｏ_３層の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の硬質被覆層の上部層を構成する蒸着α型Ａｌ_２Ｏ_３層について、本発明被覆サーメット工具３に対応して目標層厚を１５μｍとした蒸着α型Ａｌ_２Ｏ_３層の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の硬質被覆層の上部層を構成する蒸着α型Ａｌ_２Ｏ_３層について、本発明被覆サーメット工具６に対応して目標層厚を１０μｍとした蒸着α型Ａｌ_２Ｏ_３層の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の硬質被覆層の上部層を構成する蒸着α型Ａｌ_２Ｏ_３層について、本発明被覆サーメット工具９に対応して目標層厚を５μｍとした蒸着α型Ａｌ_２Ｏ_３層の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 having excellent thermal shock resistance against thermal shock repeatedly applied to a cutting edge portion at an extremely short pitch during high-speed intermittent cutting, and a surface in which the hard coating layer is excellent against cutting chips. Used for high-speed intermittent cutting of difficult-to-cut materials such as stainless steel and mild steel, as well as various steels and cast irons, as well as extremely viscous and easily chipped chips are easily welded to the cutting edge surface due to its lubricity. The present invention relates to a surface-coated cermet cutting tool (hereinafter, referred to as a coated cermet tool) that exhibits excellent cutting performance over a long period of time without causing chipping (minute chipping) on the cutting edge.
[0002]
[Prior art]
Conventionally, in general, a surface of a substrate (hereinafter, these are collectively referred to as a tool substrate) made of tungsten carbide (hereinafter, referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter, referred to as TiCN) -based cermet,
(A) All of them are Ti carbide (hereinafter, referred to as TiC) layer, nitride (hereinafter, also referred to as TiN) layer, carbonitride (hereinafter, referred to as TiCN) layer, carbon oxide (hereinafter, referred to as TiCN) formed by chemical vapor deposition. , A Ti compound layer composed of one or more layers of a carbonitride oxide (hereinafter, represented by TiCNO) layer and having a total average layer thickness of 0.5 to 20 μm. Lower layer,
(B) an upper layer composed of a deposited α-type aluminum oxide (hereinafter, referred to as Al ₂ O ₃ ) layer having an α-type crystal structure in a state formed by chemical vapor deposition and having an average layer thickness of 1 to 25 μm;
(C) formed by chemical vapor deposition;
Composition formula: TiO _X ,
When expressed in the formula, the central part in the thickness direction is measured by an Auger spectrometer, and the X value is 1.2 to 1.9 in atomic ratio to Ti,
And a surface layer composed of a Ti oxide layer having an average layer thickness of 0.1 to 3 μm,
A coated cermet tool formed by vapor-depositing a hard coating layer composed of (a) to (c) above is known, and this coated cermet tool has a very high viscosity such as, for example, various steels, particularly stainless steel and mild steel. It is also known that the cutting powder is used for continuous cutting or intermittent cutting of a difficult-to-cut material or cast iron or the like that is easily welded to the cutting blade surface (for example, see Patent Document 1).
[0003]
In addition, generally, a vapor-deposited Ti compound layer or a vapor-deposited α-type Al ₂ O ₃ layer constituting a hard coating layer of the above-mentioned coated cermet tool, and further a Ti oxide layer have a granular crystal structure, and the Ti compound For the purpose of improving the strength of the layer itself, a TiCN layer constituting the layer is mixed with an organic carbonitride, for example, a mixed gas containing CH ₃ CN as a reaction gas at a temperature of 700 to 950 ° C. by a normal chemical vapor deposition apparatus. It is also known to form a vertically elongated crystal structure by chemical vapor deposition in a medium temperature range (for example, see Patent Document 2).
[0004]
[Patent Document 1]
JP 2001-310203 A [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, and on the other hand, there is a strong demand for labor saving, energy saving, and further cost reduction for cutting work.Accordingly, cutting work tends to be even faster, 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 in high-speed interrupted cutting in which thermal shock is repeatedly applied at a very short pitch to the surface, the deposited α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer is hard and has excellent heat resistance, Because of its brittleness, chipping (small chipping) easily occurs in the hard coating layer, and as a result, the service life of the hard coating layer is relatively short in the present situation.
[0006]
[Means for Solving the Problems]
In view of the above, the present inventors have conducted research to improve the thermal shock resistance of the vapor deposited α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the above coated cermet tool. result,
When forming an Al ₂ O ₃ layer constituting an upper layer of a hard coating layer by a normal chemical vapor deposition apparatus, a κ-type crystal structure is formed as a lower layer of the upper layer under normal conditions by vapor deposition. When an Al ₂ O ₃ layer having the following formula is formed by vapor deposition as a relatively thick film and subjected to a heat treatment in a hydrogen atmosphere at a temperature of 1000 to 1100 ° C. and a holding time of 2 to 10 hours, the κ type is obtained. of the Al ₂ O ₃ layer of the crystal structure is transformed into the Al ₂ O ₃ layer of α-type crystal structure, this is the result heat transformation α type the Al ₂ O ₃ layer of now transformation cracks disperse distribution in the layer Then, on the surface of the heat-transformed α-type Al ₂ O ₃ layer in this state, a relatively thin film-deposited α-type Al ₂ O ₃ layer is formed under the same conditions as the upper layer of the upper layer. double α type the Al ₂ O ₃ layer, the upper portion of the hard coating layer of the coated cermet tools In the coated cermet tool formed by forming the hard coating layer as a result, the heat transformation forming the lower layer of the upper layer is performed. Research results show that transformation cracks distributed and distributed in the α-type Al ₂ O ₃ layer absorb and mitigate severe thermal shocks, especially during high-speed interrupted cutting, so that chipping in the hard coating layer is significantly suppressed. I got it.
[0007]
The present invention has been made on the basis of the above research results, and has a tool base made of a WC-based cemented carbide or a TiCN-based cermet,
(A) Each of them comprises one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer and a TiCNO layer formed by chemical vapor deposition, and has a total average layer thickness of 0.5 to 20 μm. A lower layer composed of a Ti compound layer,
(B) A heat treatment is applied to Al ₂ O ₃ having a κ-type crystal structure in a state formed by chemical vapor deposition to transform the crystal structure into an α-type crystal structure, and the transformed cracks generated by the heat treatment are dispersed and distributed. A lower layer of a heat-transformed α-type Al ₂ O ₃ layer having a textured structure and an average layer thickness of 1 to 20 μm, and an average layer of 0.1 to 2 μm having an α-type crystal structure in a state formed by chemical vapor deposition. An upper layer composed of a composite double α-type Al ₂ O ₃ layer comprising an upper layer of a vapor-deposited α-type Al ₂ O ₃ layer having a thickness,
(C) formed by chemical vapor deposition;
Composition formula: TiO _X ,
When expressed in the formula, the central part in the thickness direction is measured by an Auger spectrometer, and the X value is 1.2 to 1.9 in atomic ratio to Ti,
And a surface layer composed of a Ti oxide layer having an average layer thickness of 0.1 to 3 μm,
The present invention is characterized by a coated cermet tool in which the hard coating layer formed of the above (a) to (c) has excellent thermal shock resistance.
[0008]
Next, the reasons for limiting the numerical values of the constituent layers of the hard coating layer of the coated cermet tool of the present invention 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 enables the hard coating layer to have strength. In addition, the tool base and the heat-transformed α-type Al ₂ O ₃ layer which is the lower layer of the upper layer are formed. Although it has an effect of firmly adhering to any of them, and thus has an effect of improving the adhesion of the hard coating layer to the tool base, if the total average layer thickness is less than 0.5 μm, the effect cannot be sufficiently exerted. On the other hand, if the total average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation, especially in high-speed interrupted cutting accompanied by high heat generation, and this tends to cause uneven wear which causes wear promotion. The total average layer thickness was determined to be 0.5-20 μm.
[0009]
The heat transformed α-type the Al ₂ O ₃ layer heated transformed α-type Al ₂ O ₃ layer which is the lower layer of the (b) an upper layer, thereby improving the wear resistance of the hard coating layer, the street upper layer of the It exists under a certain vapor deposited α-type Al ₂ O ₃ layer and absorbs thermal shock due to the effect of transformation cracks dispersed and distributed in the layer, and has the effect of preventing chipping from occurring in the hard coating layer. When the average layer thickness is less than 1 μm, the above-mentioned effect cannot be sufficiently exerted. On the other hand, when the average layer thickness exceeds 20 μm, the strength is reduced, and the effect of suppressing the occurrence of chipping is sharply reduced. Since the occurrence of chipping is promoted, the average layer thickness is set to 1 to 20 μm.
[0010]
(C) The upper layer is a vapor-deposited α-type _Al 2 _{O 3} layer deposited α-type _Al 2 _{O 3} layer of the upper layer, the transformation cracks _three layers during heating transformation α-type _Al 2 _O of the hard coating layer In the built-in state, there is an effect of improving abrasion resistance without causing chipping. However, if the average layer thickness is less than 0.1 μm, the above effect cannot be sufficiently exerted. If the layer thickness exceeds 2 μm and becomes too thick, chipping tends to occur on itself, so the average layer thickness was set to 0.1 to 2 μm.
[0011]
(D) Surface layer (Ti oxide layer)
As described in Patent Literature 1, the Ti oxide layer constituting the surface layer is prepared by using a normal chemical vapor deposition apparatus to change 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),
The central part in the thickness direction was measured with an Auger spectrometer, and the ratio of oxygen to Ti was 1.2 to 1.9 in atomic ratio, that is,
Composition formula: TiO _X ,
Where X is 1.2 to 1.9 in atomic ratio to Ti,
It has a very low affinity for highly viscous and difficult-to-cut materials such as stainless steel and mild steel, and exhibits excellent surface lubricity that does not change even in high-speed cutting with high heat generation. . Therefore, if the X value of oxygen (O) with respect to Ti is less than 1.2 in atomic ratio, the desired excellent surface lubricating property cannot be ensured. The X value is set to 1.2 to 1.9 because the pores are easily formed in the sample, and it is difficult to form a sound surface layer stably. If the average layer thickness is less than 0.1 μm, the desired surface lubricity cannot be ensured, so that chipping is likely to occur, while the effect of the Ti oxide layer is less than 3 μm. Is sufficient, and the average layer thickness is set to 0.1 to 3 μm in consideration of economy.
[0012]
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.
[0013]
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.
[0014]
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.
[0015]
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). The conditions for forming a TiCN layer having a growth crystal structure are shown, and the other conditions are 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 vapor-deposited κ-type Al ₂ O ₃ layer having a κ-type crystal structure was formed under the same conditions as shown in Table 3, and hydrogen was added thereto. A heat treatment is performed in an atmosphere at a temperature of 1050 ° C. for a predetermined time within a range of 2 to 8 hours to transform the κ-type crystal structure of the Al ₂ O ₃ layer into an α-type, and heat transformation Heat-transformed α-type A in which formed cracks are dispersed and distributed in the layer The l ₂ O ₃ layer is formed as the lower layer constituting the upper layer of the hard coating layer with the target layer thickness also shown in Table 5, and further under the conditions shown in Table 3 and the target layer shown in Table 5. A thick vapor deposited α-type Al ₂ O ₃ layer is formed as an upper layer constituting the upper layer, and a Ti oxide layer having a target layer thickness shown in Table 4 and a target layer thickness shown in Table 5 is further formed on the same surface. The coated cermet tools 1 to 12 of the present invention were manufactured by forming them as layers.
For the purpose of comparison, as shown in Table 6, the conventional coating cermet was prepared under the same conditions except that 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. Tools 1 to 12 were manufactured respectively.
[0016]
The resulting heat-transformed α-type Al ₂ O ₃ layer constituting the lower layer of the upper layer of the hard coating layer of the coated cermet tool of the present invention and the upper layer of the hard coating layer of the conventionally coated cermet tool. X-ray diffraction was measured for the purpose of observing the difference between the deposited α-type Al ₂ O ₃ layers.
First, as a sample for X-ray diffraction measurement, a single crystal WC having a diffraction peak only on the (001) plane and the (002) plane on the X-ray diffraction chart was used as a substrate sample. The same conditions as those for forming the heating transformed α-type Al ₂ O ₃ layer having a target layer thickness of 15 μm, 10 μm, and 5 μm, which is the lower layer constituting the hard coating layer of the cermet tools 3, 6, and 9, Then, the heat-transformed α-type Al ₂ O ₃ layers having the target layer thicknesses of 15 μm, 10 μm, and 5 μm, respectively, are directly formed to obtain coating samples A to C of the present invention, and hard coating layers of the conventional coating cermet tools 1 to 12 described above. Under the same conditions as the conditions for forming the vapor-deposited α-type Al ₂ O ₃ layer constituting the upper layer, the target layer thicknesses were set to 15 μm, 10 μm and 5 It was prepared by directly forming a vapor-deposited α-type Al ₂ O ₃ layer having a thickness of μm to obtain conventional coated samples a to c.
[0017]
Next, the X-ray diffraction measurement of the above-mentioned heat-transformed α-type Al ₂ O ₃ layer and the vapor-deposited α-type Al ₂ O ₃ layer of these coated samples was carried out by using a usual X-ray diffractometer, and Cu was placed in an X-ray tube. By irradiating the anode (target) with thermoelectrons generated from the metal W filament under the conditions of voltage: 40 kV and current: 350 mA, characteristic X-rays having a wavelength of 0.154 nm from the Cu anode surface are obtained. X-rays that generate a certain Cu-Kα ray, irradiate the characteristic X-ray to the surface of the coated sample, and diffract at an angle equal to the X-ray incident angle θ with respect to the coated sample surface among the X-rays scattered from the coated sample Was measured with an X-ray detector. 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.
[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, the lower layer of the Ti compound layer, the lower layer of the heat-transformed α-type Al ₂ O ₃ layer in which cracks generated by the heat-transformation are dispersed and distributed in the layer, and the upper layer of the vapor-deposited α-type Al ₂ O ₃ layer And an upper layer composed of a composite double α-type Al ₂ O ₃ layer, and a surface layer of a Ti oxide layer. In the latter case, a lower layer of a Ti compound and a vapor-deposited α-type Al ₂ O ₃ layer are provided. It was confirmed that it was composed of an upper layer and a surface layer of a Ti oxide layer.
Further, for the surface layers of the coated cermet tools 1 to 12 of the present invention and the conventional coated cermet tools 1 to 12, the oxygen content ratio (X value) at the center in the thickness direction was measured using an Auger spectroscopic analyzer. , And substantially the same values as the target values shown in Table 4.
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: 420m / min,
Notch: 1 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: 420m / min,
Cut: 2mm,
Feed: 0.2 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: 420m / min,
Cut: 0.6 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: 420m / min,
1 mm notch,
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.
[0021]
[Table 1]

[0022]
[Table 2]

[0023]
[Table 3]

[0024]
[Table 4]

[0025]
[Table 5]

[0026]
[Table 6]

[0027]
[Table 7]

[0028]
【The invention's effect】
From the results shown in Tables 5 to 7, the coated cermet tools 1 to 12 of the present invention showed that the heat-transformed α-type Al ₂ O ₃ layer dispersed and distributed in the heat-transformed α-type Al ₂ O ₃ layer constituting the lower layer of the hard coating layer Excellent thermal shock absorption due to cracking and excellent surface lubrication for chips of the surface Ti oxide layer, especially for stainless steel and mild steel with extremely high thermal shock and high heat generation. Even in intermittent cutting, the occurrence of chipping of the cutting edge is remarkably suppressed, and excellent wear resistance is exhibited. On the other hand, the conventional coated cermet tools 1 to _{3 in which} the upper layer of the hard coating layer is made of a vapor-deposited α-type Al ₂ O ₃ layer In No. 12, since the vapor deposited α-type Al ₂ O ₃ layer cannot withstand severe thermal shock in high-speed intermittent cutting, it is clear that chipping occurs on the cutting edge and the service life is reached in a relatively short time. .
As described above, the coated cermet tool of the present invention can be used not only for continuous cutting or intermittent cutting of various steels or cast irons under normal conditions, but also for cutting conditions accompanied by extremely high thermal shock and high heat generation. It exhibits excellent chipping resistance even in high-speed interrupted cutting of difficult-to-cut materials such as stainless steel and mild steel, and exhibits excellent cutting performance over a long period of time. Therefore, it is possible to satisfactorily cope with labor and energy savings and cost reduction.
[Brief description of the drawings]
FIG. 1 is a diagram showing an X-ray diffraction chart of a heat-transformed α-type Al ₂ O ₃ layer having a target layer thickness of 15 μm corresponding to the lower layer constituting the upper layer of the hard coating layer of the coated cermet tool 3 of the present invention. is there.
FIG. 2 is a diagram showing an X-ray diffraction chart of a heat-transformed α-type Al ₂ O ₃ layer having a target layer thickness of 10 μm corresponding to the lower layer constituting the upper layer of the hard coating layer of the coated cermet tool 6 of the present invention. is there.
FIG. 3 is a view showing an X-ray diffraction chart of a heat-transformed α-type Al ₂ O ₃ layer having a target layer thickness of 5 μm corresponding to the lower layer constituting the upper layer of the hard coating layer of the coated cermet tool 9 of the present invention. is there.
[4] Conventional coating the cermet tools hard layer deposition α type the Al ₂ O ₃ layer constituting the upper layer of the present invention coated cermet tool 3 deposited α-type to the target layer thickness and 15μm in correspondence with Al ₂ X-ray diffraction chart of the O ₃ layer is a diagram showing a.
[5] Conventional coated cermet for hard coating layer deposited α-type the Al ₂ O ₃ layer constituting the upper layer of the tool, the present invention coated cermet tool 6 in response to the deposition α-type target layer thickness was 10 [mu] m Al ₂ X-ray diffraction chart of the O ₃ layer is a diagram showing a.
[6] Conventional coated cermet for hard coating layer deposited α-type the Al ₂ O ₃ layer constituting the upper layer of the tool, the present invention coated cermet tool 9 corresponds deposited α-type target layer thickness was 5 [mu] m Al ₂ X-ray diffraction chart of the O ₃ layer is a diagram showing a.

Claims (1)

On the surface of a tool substrate made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) each of which is composed of one or more of a carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer of Ti formed by chemical vapor deposition; A lower layer composed of a Ti compound layer having a total average layer thickness of ２０20 μm,
(B) A structure in which aluminum oxide having a κ-type crystal structure is subjected to heat treatment in a state formed by chemical vapor deposition to transform the crystal structure into an α-type crystal structure, and the transformed cracks generated by the heat treatment are dispersed and distributed. And a lower layer of a heat-transformed α-type aluminum oxide layer having an average layer thickness of 1 to 20 μm, and having an α-type crystal structure in a state formed by chemical vapor deposition, and having an average layer thickness of 0.1 to 2 μm. An upper layer composed of a composite double α-type aluminum oxide layer consisting of an upper layer of a vapor-deposited α-type aluminum oxide layer,
(C) formed by chemical vapor deposition;
Composition formula: TiO _X ,
When expressed in the formula, the central part in the thickness direction is measured by an Auger spectrometer, and the X value is 1.2 to 1.9 in atomic ratio to Ti,
And a surface layer composed of a Ti oxide layer having an average layer thickness of 0.1 to 3 μm,
A cutting tool made of a surface-coated cermet having a hard coating layer having excellent thermal shock resistance, wherein the cutting tool is formed by forming the hard coating layer comprising (a) to (c).

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