JP2009090396A - Surface-coated cutting tool having hard coated layer exhibiting excellent chipping resistance in heavy cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool having a hard coated layer exhibiting excellent chipping resistance in heavy cutting. <P>SOLUTION: The surface-coated cutting tool comprises a tool body composed of WC-based hard metal, TiCN-based cermet and a cBN-based super high pressure sintered material, and a hard coating layer having an average thickness of 1-10 μm vapor-deposited on the surface of the tool body. The hard coating layer is composed of a composite nitride carbide layer of Ti which has the highest peak in a gradient angle section of 30-40 degrees in a gradient angle distribution graph created by measuring a gradient angle of a normal line on a ä100} plane with respect to a normal line of a surface ground plane of the coating layer, has a total of the degrees showing 60% or higher of the whole, and satisfies a composition formula: TiC<SB>X</SB>N<SB>1-X</SB>, wherein 0.2≤X≤0.5 in atomic ratio. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In particular, the present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that exhibits a fracture resistance with a hard coating layer excellent in heavy cutting of steel or cast iron that requires a large mechanical load on the cutting edge. Is.

In general, for coated tools, inserts that are detachably attached to the tip of a cutting tool for turning of work materials such as various types of steel and cast iron, and the inserts are detachably attached to be used for chamfering and grooving. An insert type end mill that performs cutting processing in the same manner as a solid type end mill used for processing and shoulder processing is known.
In addition, as a coated tool, tungsten carbide (hereinafter referred to as WC) based cemented carbide, titanium carbonitride (hereinafter referred to as TiCN) based cermet, or various types of cubic boron nitride (hereinafter referred to as cBN) based super A TiCN layer or Ti (CaNbOc) N _Z (however, in terms of atomic ratio, 0.05 <a <0.9, 0.1 <b <1.0, 0.01 ≦ c ≦ 0.2, 0.8 satisfies ≦ z ≦ 1.2) a hard coating layer provided consisting of layers, and (111) plane of the TiCN layer or Ti (CaNbOc) _{N Z} layer Coated tools that improve the strength, fracture resistance, and wear resistance of hard coating layers by increasing the orientation are known, and these coated tools can also be used for cutting various types of steel and cast iron. Are known.
JP-A-8-281502 JP 2002-346811 A

In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving, energy saving, and cost reduction for cutting work, and along with this, cutting work tends to be further accelerated. For coated tools, there is no problem when this is used for cutting under normal conditions such as steel or cast iron, but when this is used for heavy cutting with severe cutting conditions, a hard coating layer is required. TiCN layer having an increased above conventional (111) plane orientation which constitute, Ti (CaNbOc) _{N Z} layer, since high temperature strength is insufficient, notching at the boundary portion of the cutting edge (hereinafter, referred to as edge notching ) And is prone to defects, the service life is currently reached in a relatively short time.

In view of the above, the inventors of the present invention have conducted intensive research focusing on the crystal orientation of the TiCN layer constituting the hard coating layer in order to improve the fracture resistance of the coated tool from the above viewpoint. ,
(A) The conventional TiCN layer constituting the hard coating layer of the conventional coated tool is prepared by, for example, inserting a tool base into an arc ion plating apparatus which is one type of a normal physical vapor deposition apparatus shown in FIG. An arc discharge current of, for example, 60 to 100 A is generated between a cathode electrode (evaporation source) made of a Ti alloy and an anode electrode while the inside of the apparatus is heated to, for example, 300 to 500 ° C., and at the same time as a reaction gas in the apparatus Nitrogen-methane mixed gas is introduced to form a reaction atmosphere of 1 to 6 Pa, for example, while a film is formed on the tool base under a condition that a DC bias voltage of -50 to -100 V is applied from a bias power source, for example (hereinafter referred to as the following). Usually referred to as film formation conditions)
The deposition conditions are changed, for example, the tool substrate in the apparatus is heated to 850 ° C. with a heater to increase the film forming temperature, and further, a bipolar pulse bias is applied to the tool substrate from a bias power source to perform arc ion plating. When performed (hereinafter referred to as a modified film forming condition), a TiCN layer deposited under this condition (hereinafter referred to as a modified TiCN layer) has a crystal grain size as compared with a TiCN layer formed under a normal film forming condition. The field strength is strengthened, and as a result, the high temperature strength of the hard coating layer is further improved, so that the hard coating layer has excellent chipping resistance even in heavy cutting where a heavy mechanical load is applied to the cutting edge. Exhibiting excellent wear resistance over a long period of time.

(B) About the TiCN layer (hereinafter referred to as the conventional TiCN layer) constituting the hard coating layer of the conventional coated tool and the modified TiCN layer of the above (a),
Using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal grain is normal to the surface polished surface. The tilt angle formed by the normal of the {100} 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. At the same time, when an inclination angle distribution graph is created by counting the frequencies existing in each section, for example, as shown in FIG. 2, the highest peak exists in the inclination angle section within the range of 30 to 40 degrees. In addition, since the total number of frequencies existing in the range of 30 to 40 degrees shows an inclination angle number distribution graph that occupies a ratio of 60% or more of the entire degrees in the inclination angle number distribution graph, the modified TiCN layer is With respect to the normal direction of the polished surface (1 2) surface to exhibit crystal orientation that is oriented strongly.

(C) Since the above-mentioned modified TiCN layer has a higher high-temperature strength than the conventional TiCN layer in addition to the high-temperature hardness and high-temperature strength that the conventional TiCN layer itself has, it is deposited as a hard coating layer. The formed coated tool has a hard coating layer as compared with the conventional coated tool formed by vapor deposition of the TiCN layer even when used for heavy cutting where a particularly large mechanical load is applied to the cutting edge. To exhibit even better fracture resistance.
The research results shown in (a) to (c) above were obtained.

This invention was made based on the above research results,
”Ti composite carbonitride having an average layer thickness of 1 to 10 μm on the surface of a tool base made of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultrahigh pressure sintered material In a surface-coated cutting tool formed by vapor-depositing a hard coating layer consisting of a physical layer,
The Ti composite carbonitride layer is:
Composition formula: When expressed by TiC _X N _1-X ,
0.2 ≦ X ≦ 0.5 (where X represents an atomic ratio), and
Using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal grain is normal to the surface polished surface. The tilt angle formed by the normal of the {100} 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 counting the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 30 to 40 degrees, and exists within the range of 30 to 40 degrees. A surface-coated cutting tool (coated tool), characterized in that the total number of frequencies to be displayed shows a tilt angle number distribution graph that accounts for 60% or more of the total frequency in the tilt angle number distribution graph. "
It has the characteristics.

First, the modified TiCN layer of the present invention will be described in detail.
(A) Composition formula: Ti composite carbonitride layer (modified TiCN layer) represented by TiC _X N _1-X
In the modified TiCN layer constituting the hard coating layer of the coated tool of the present invention, the TiC component has the effect of improving the hardness of the layer, and the TiN component has the action of improving the strength of the layer. By coexisting components, it will have high hardness and excellent strength, but if the content ratio (X value) of the C component in the layer is less than 0.2 in terms of the atomic ratio to the total amount with the N component The desired high hardness cannot be obtained. On the other hand, when the content ratio (X value) exceeds 0.5, the content ratio of the N component is relatively decreased, and an effect of improving the strength can be expected. Since X disappeared, X value was determined as 0.2-0.5 by atomic ratio.

(B) Crystal plane orientation ratio With respect to the above-described modified TiCN layer, a field emission scanning electron microscope was used to irradiate each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface with an electron beam. Then, the inclination angle formed by the normal line of the {100} plane that is the crystal plane of the crystal grain is measured with respect to the normal line of the surface-polished surface, and within the range of 0 to 45 degrees of the measurement inclination angle The measured inclination angle is divided into pitches of 0.25 degrees, and the inclination angle number distribution graph formed by summing up the frequencies existing in each division is created. As shown in FIG. An inclination angle in which the highest peak exists in the inclination angle section within the range of degrees, and the total of the frequencies existing within the range of 30 to 40 degrees occupies a ratio of 60% or more of the entire degrees in the inclination angle frequency distribution graph Since the number distribution graph is shown, the modified TiCN It can be seen that the {112} plane is strongly oriented with respect to the normal direction of the surface-polished surface, and such a crystal orientation allows the layer to be compared with a conventional TiCN layer formed under normal film formation conditions. The grain boundary strength of the crystal grains is further improved. As a result, the fracture resistance of the coated tool provided with the modified TiCN layer as the hard coating layer is improved even under heavy cutting conditions.

(C) Average layer thickness If the average layer thickness of the modified TiCN layer is less than 1 μm, the heat resistance, high temperature hardness and high temperature strength possessed by itself cannot be maintained over a long period of time, resulting in a short tool life. On the other hand, if the average layer thickness exceeds 10 μm, peeling or chipping of the film tends to occur, so the average layer thickness was set to 1 to 10 μm.

Next, the film forming conditions for the modified TiCN layer of the present invention will be described in detail.
In producing a coated tool having a modified TiCN layer deposited by arc ion plating as a hard coating layer,
A tool base is disposed on a rotary table in the arc ion plating apparatus, and metal Ti is disposed as a cathode electrode.
After bombarding the tool base disposed on the rotary table in the apparatus with Ar ions in an Ar gas atmosphere,
Introducing nitrogen-methane mixed gas as a reaction gas into the apparatus to make a reaction atmosphere of 1 to 6 Pa, heating the inside of the apparatus, and maintaining the tool base temperature at 750 to 900 ° C., the tool on the rotary table Bipolar pulse bias comprising a negative bias of applied voltage +5 to −15 (v) × application time 2000 to 20000 (ns) and a positive bias of applied voltage +32 to +42 (v) × application time 100 to 5000 (ns) on a substrate And a current of 60 to 200 A is passed between the cathode electrode and the anode electrode made of the metal Ti to generate arc discharge, and the surface of the tool base is represented by the composition formula: TiC _X N _1-X . Then, a modified TiCN layer satisfying 0.2 ≦ X ≦ 0.5 (where X represents an atomic ratio) is formed by vapor deposition.
Among the above deposition conditions, the tool base temperature is less than 750 ° C., because the orientation rate to the {112} plane is extremely small, the intended film cannot be obtained, and the grain boundary strength is insufficient. The tool substrate temperature needs to be 750 ° C. or higher. Although there is no particular upper limit on the tool base temperature, in practice, the tool base temperature is preferably 750 to 900 ° C. from the viewpoint of the specifications of the arc ion plating apparatus. However, this does not mean that the tool substrate temperature should not be raised above 900 ° C.
As for the bipolar pulse bias, a negative bias of applied voltage +5 to −15 (v) × application time 2000 to 20000 (ns) and a positive bias of applied voltage +32 to +42 (v) × application time 100 to 5000 (ns) If the application voltage and application time of the negative bias and the positive bias are out of the above numerical range, the target {112} plane strongly oriented film and Therefore, the conditions for applying a bias to the tool substrate during film formation were determined as described above.

  According to the coated tool and the manufacturing method of the present invention, the modified TiCN layer, which is a hard coating layer, has a superior high-temperature strength even in heavy cutting processing such as steel and cast iron that requires a very large mechanical load on the cutting edge. Thus, it is possible to provide a coated tool that exhibits excellent fracture resistance, and this coated tool exhibits no wear on the hard coating layer and has excellent wear resistance over a long period of time. It is something that demonstrates.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared as raw material powders. These raw material powders were blended into the composition shown in Table 1, added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and pressed into a green compact with a predetermined shape at a pressure of 98 MPa. The green compact was vacuum sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa. After sintering, the cutting edge portion was R: 0.07 mm honing By performing the processing, tool bases A to F made of a WC-base cemented carbide having a throwaway tip shape specified in ISO · CNMG120408 were manufactured.

In addition, as raw material powders, TiCN (mass ratio TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC powder, all 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 by a ball mill for 24 hours, dried, and pressed into a 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 the sintering, the cutting edge portion was subjected to a honing process of R: 0.07 mm. Tool bases G to L made of TiCN-based cermet having a standard / CNMG12041 chip shape were formed.

Furthermore, as raw material powders, cubic boron nitride (cBN) powder, titanium nitride (TiN) powder, Al powder, aluminum oxide (Al ₂ O ₃ ) powder each having an average particle diameter in the range of 0.5 to 4 μm. These raw material powders were blended in the composition shown in Table 3, wet-mixed with a ball mill for 80 hours, dried, and then had a diameter of 50 mm × thickness: 1.5 mm at a pressure of 120 MPa. The green compact is press-molded, and then the green compact is sintered in a vacuum atmosphere at a pressure of 1 Pa at a predetermined temperature within the range of 900 to 1300 ° C. for 60 minutes and pre-baked for cutting edge pieces. A WC-based cemented carbide support piece having a size of Co: 8% by mass, WC: remaining composition, and diameter: 50 mm × thickness: 2 mm was prepared as a sintered body. Super After charging into a high-pressure sintering apparatus, sintering under ultrahigh pressure at a predetermined temperature in the range of pressure: 5 GPa, temperature: 1200 to 1400 ° C., holding time: 0.8 hours, after sintering The upper and lower surfaces are polished with a diamond grindstone and divided into 3 mm regular triangles with a wire electric discharge machine, and Co: 5% by mass, TaC: 5% by mass, WC: remaining composition and CIS standard SNGA120412 In the brazed portion (corner portion) of the WC-based cemented carbide chip body having a shape (thickness: 4.76 mm × one side length: 12.7 mm), the mass percentage is Cu: 26%, Ti: 5%, Ni: 2.5%, Ag: Brazing using a brazing material of an Ag alloy having the remaining composition, and after processing the outer periphery to a predetermined dimension, the width of the cutting edge is 0.13 mm, Angle: 25 ° honing process, The cBN-based ultrahigh pressure sintered material made of tool substrate M~R having a tip shape of ISO standard SNGA120412 by performing finish polishing was produced, respectively.

(A) Each of these tool bases A to F, G to L, and M to R is ultrasonically cleaned in acetone and dried, on a rotary table in the arc ion plating apparatus shown in FIG. A modified TiCN layer having a component composition corresponding to the target composition shown in Tables 5 to 7 as a cathode electrode (evaporation source) is mounted along the outer periphery at a predetermined distance in the radial direction from the central axis of Place the metal Ti for forming,
(B) First, the inside of the apparatus is evacuated and kept at a vacuum of 1 × 10 ⁻² Pa or less, and the inside of the apparatus is heated to 400 ° C. with a heater, and then Ar gas is introduced to adjust the atmosphere to 2.0 Pa. And applying a -200 V DC bias voltage to the rotating tool base while rotating on the table, and bombarding the surface of the tool base with argon ions,
(C) A nitrogen-methane mixed gas is introduced into the apparatus as a reaction gas to make a reaction atmosphere of 2 Pa, the inside of the apparatus is heated, and the tool base temperature is maintained at the temperature shown in Table 4, A bipolar pulse bias having the same conditions as shown in Table 4 is applied from a bias power source to a rotating tool base while rotating at 100 and a current of 100 A is passed between the cathode electrode (metal Ti) and the anode electrode. The present invention coated tools 1 to 18 were respectively produced by generating arc discharge and vapor-depositing the modified TiCN layers having the target compositions and target thicknesses shown in Tables 5 to 7 on the surface of the tool base.

  Further, for the purpose of comparison, the conditions at the time of vapor deposition were set to the tool substrate temperature shown in Table 4 and the applied bias conditions shown in Table 4 as well, and the case of manufacturing the coated tools 1 to 18 of the present invention was completely different. Conventional coated tools 1-18 were produced by depositing a conventional TiCN layer under the same conditions.

Next, an inclination angle number distribution graph was created for each of the modified TiCN layer and the conventional TiCN layer constituting the hard coating layer of the present invention-coated tool and the conventional coated tool using a field emission scanning electron microscope.
First, the inclination angle number distribution graph is set in a lens barrel of a field emission scanning electron microscope in a state where the surfaces of the modified TiCN layer and the conventional TiCN layer are polished surfaces, and 70 degrees on the polished surface. An electron beam with an acceleration voltage of 15 kV at an incident angle of 1 nm is irradiated to each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface with an irradiation current of 1 nA, and an electron backscatter diffraction image apparatus is used. Then, the inclination angle formed by the normal of the {100} plane, which is the crystal plane of the crystal grain, is measured with respect to the normal of the surface-polished surface in a 30 × 50 μm region at an interval of 0.1 μm / step. Based on this measurement result, among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are divided for each pitch of 0.25 degrees, and the frequencies existing in each section are tabulated. Created by.

  In the gradient angle distribution graphs of various modified TiCN layers and conventional TiCN layers obtained as a result, the frequencies existing in the measured gradient angle section of 30 to 40 degrees are shown in Tables 5 to 7, respectively.

In the above-mentioned various inclination angle number distribution graphs, as shown in Tables 5 to 7, the modified TiCN layer of the coated tool of the present invention has a very high orientation ratio of {112} plane (in the inclination angle number distribution graphs). On the other hand, the conventional TiCN layer of the conventional coated tool has a low orientation ratio of {112} planes.
2 shows an inclination angle number distribution graph of the modified TiCN layer of the present coated tool 1, and FIG. 3 shows an inclination angle number distribution graph of the conventional TiCN layer of the conventional coated tool 1, respectively.

  Further, for the above-mentioned coated tools 1-18 of the present invention and the conventional coated tools 1-18, the constituent layers of the hard coating layer were observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analyzer (longitudinal section of the layer). As a result, it was confirmed that both the former and the latter were composed of a TiCN layer having substantially the same composition as the target composition. Moreover, when the thickness of the hard coating layer of these coating tools was measured using a scanning electron microscope (same longitudinal section measurement), the average layer thickness (5 point measurement) was substantially the same as the target layer thickness. Average value).

  Next, with the various coated tools described above, the present coated tools 1 to 18 and the conventional coated tools 1 to 18 in the state where each of the above various coated tools is screwed to the tip of the tool steel tool with a fixing jig, as follows. Cutting tests were conducted.

About this invention coated tools 1-6 and conventional coated tools 1-6,
Cutting conditions (A-1);
Work material: JIS / SNCM439 round direction rods with four equal grooves in the length direction,
Cutting speed: 180 m / min,
Infeed: 3.2 mm,
Feed: 0.35 mm / rev,
Cutting time: 3 minutes,
A dry interrupted heavy cutting test of alloy steel under the conditions of (normal cutting and feeding are 1.5 mm and 0.2 mm / rev, respectively),
Cutting conditions (B-1);
Work material: JIS-S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 280 m / min,
Cutting depth: 3.0 mm,
Feed: 0.35 mm / rev,
Cutting time: 3 minutes,
Carbon steel dry interrupted heavy cutting test under normal conditions (normal cutting and feeding are 1.5 mm and 0.2 mm / rev, respectively),
Cutting conditions (C-1);
Work material: JIS / SUS304 round bar,
Cutting speed: 200 m / min,
Infeed: 3.2 mm,
Feed: 0.32 mm / rev,
Cutting time: 3 minutes,
Stainless steel dry continuous heavy cutting test under the following conditions (normal cutting and feeding are 1.2 mm and 0.15 mm / rev, respectively),
The flank wear width of the cutting blade was measured. The measurement results are shown in Table 8.

Moreover, about this invention coated tool 7-12 and conventional coated tool 7-12,
Cutting conditions (A-2);
Work material: JIS / SNCM439 round direction rods with four equal grooves in the length direction,
Cutting speed: 240 m / min,
Cutting depth: 1.2 mm,
Feed: 0.20 mm / rev,
Cutting time: 5 minutes,
Dry interrupted heavy cutting test of alloy steel under the conditions of (normal cutting speed and feed are 150 m / min and 0.10 mm / rev, respectively),
Cutting conditions (B-2);
Work material: JIS / SCM440 round bar,
Cutting speed: 200 m / min,
Cutting depth: 2.0 mm,
Feed: 0.14 mm / rev,
Cutting time: 5 minutes,
Dry high-speed high-cut continuous cutting test of alloy steel under the following conditions (normal cutting speed and cutting are 150 m / min and 1.5 mm, respectively)
Cutting conditions (C-2);
Work material: JIS / S50C lengthwise equal 4 round grooved round bars,
Cutting speed: 180 m / min,
Cutting depth: 1.3 mm,
Feed: 0.30 mm / rev,
Cutting time: 5 minutes,
Carbon steel dry high feed intermittent cutting test under the conditions of (normal feed is 0.15mm / rev),
The flank wear width of the cutting blade was measured. The measurement results are shown in Table 9.

Moreover, about this invention coated tool 13-18 and conventional coated tool 13-18,
Cutting conditions (A-3);
Work material: JIS · SCr420 (HRC60) lengthwise equal 4 round bars with longitudinal grooves,
Cutting speed: 240 m / min,
Cutting depth: 0.18 mm,
Feed: 0.24 mm / rev,
Cutting time: 5 minutes,
Chrome steel dry high-speed high-feed intermittent cutting test under the following conditions (normal cutting speed and feed are 120 m / min and 0.15 mm / rev, respectively),
Cutting conditions (B-3);
Work material: JIS / SUJ2 quenching material (HRC60), 4 longitudinally spaced round bars with equal intervals in the length direction,
Cutting speed: 150 m / min,
Cutting depth: 0.35 mm,
Feed: 0.16 mm / rev,
Cutting time: 8 minutes,
Dry high-speed high-cut intermittent cutting test of the quenching material of the bearing steel under the conditions (normal cutting speed and cutting are 120 m / min and 0.2 mm, respectively),
Cutting conditions (C-3);
Work material: JIS SKD61 (HRC61) round bar,
Cutting speed: 210 m / min,
Cutting depth: 0.25 mm,
Feed: 0.25 mm / rev,
Cutting time: 4 minutes,
Dry continuous heavy cutting test of die steel hardened material under the following conditions (normal cutting and feeding are 0.15 mm and 0.15 mm / rev, respectively)
The flank wear width of the cutting blade was measured. The measurement results are shown in Table 10.

  From the results shown in Tables 5 to 10, the coated tools 1 to 18 of the present invention have a very high {112} plane orientation ratio (a ratio of 60% or more of the entire frequency in the tilt angle number distribution graph). Even in heavy cutting of steel and cast iron, which has a hard coating layer and has an extremely high mechanical load, the modified TiCN layer has excellent high-temperature strength, so it has excellent fracture resistance and at the same time. In the conventional coated tools 1 to 18 in which the hard coating layer is composed of the conventional TiCN layer having a low {112} plane orientation ratio while exhibiting wear resistance, the high temperature strength of the hard coating layer is not good. Since it is sufficient, it is clear that in the heavy cutting process, defects occur in the hard coating layer and the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention has an excellent hard coating layer not only for continuous cutting and interrupted cutting under normal conditions such as various steels and cast iron, but also for heavy cutting that requires high high-temperature strength. It exhibits excellent chipping resistance and exhibits excellent cutting performance over a long period of time, so that it can sufficiently satisfy high performance cutting equipment, labor saving and energy saving of cutting processing, and cost reduction. It is.

It is a schematic explanatory drawing of the arc ion plating apparatus used in forming a hard coating layer. It is an inclination angle number distribution graph of the modified TiCN layer which comprises the hard coating layer of this invention coated tool 1. It is an inclination angle number distribution graph of the conventional TiCN layer which comprises the hard coating layer of the conventional coating tool 1. FIG.

Claims (1)

Ti composite carbonitride having an average layer thickness of 1 to 10 μm on the surface of a tool base made of tungsten carbide-based cemented carbide, titanium carbonitride-based cermet, or cubic boron nitride-based ultrahigh pressure sintered material In a surface-coated cutting tool formed by vapor-depositing a hard coating layer consisting of layers,
The Ti composite carbonitride layer is:
Composition formula: When expressed by TiC _X N _1-X ,
0.2 ≦ X ≦ 0.5 (where X represents an atomic ratio), and
Using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal grain is normal to the surface polished surface. The tilt angle formed by the normal of the {100} 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 counting the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 30 to 40 degrees, and exists within the range of 30 to 40 degrees. The surface covering cutting tool characterized by showing the inclination angle number distribution graph for which the sum total of frequency to occupy accounts for 60% or more of the whole frequency in an inclination angle number distribution graph.

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