JP2009090395A - 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 layer of Al, Cr and 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: (Al<SB>1-X-Y</SB>Cr<SB>X</SB>Ti<SB>Y</SB>)N, wherein 0.3≤X≤0.6 and 0.1≤Y≤0.3 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 (AlaCrbTic) N (wherein a is 0.30 to 0.70, b is 0.5 to 0.20, and c is 0.30 on the surface of the tool body made of high pressure sintered material. -0.70) is known as a coated tool formed by physical vapor deposition of a composite nitride layer of Al, Cr and Ti [hereinafter referred to as (Al, Cr, Ti) N layer]. Coated tools that have improved oxidation resistance and lubricity by containing a small amount of oxygen (atomic ratio, 0.01 ≦ O / (N + O) ≦ 0.30) in the hard coating layer have also been proposed. Continuous cutting and intermittent cutting of various types of steel and cast iron It is also known for use in cutting machining.
JP 2001-254187 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, and along with this, cutting has been on the trend of higher speed. 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. The constituent (Al, Cr, Ti) N layer (or one containing a small amount of O (oxygen) therein) has insufficient high-temperature strength, so that the boundary portion of the cutting edge is abnormally damaged (hereinafter referred to as the following) It is the current situation that the service life is reached in a relatively short time because it is likely to cause defects.

In view of the above, the inventors of the present invention, from the above viewpoint, in order to improve the fracture resistance of the coated tool, the (Al, Cr, Ti) N layer, that is, the lattice as shown in the schematic diagram of FIG. As a result of diligent research focusing on the (Al, Cr, Ti) N layer having a NaCl type face centered cubic crystal structure in which constituent atoms composed of Al, Cr, Ti, and nitrogen exist, respectively,
(A) A conventional (Al, Cr, Ti) N layer constituting a hard coating layer of a conventional coated tool is, for example, a tool substrate in an arc ion plating apparatus which is one type of a normal physical vapor deposition apparatus shown in FIG. In a state where the inside of the apparatus is heated to 300 to 500 ° C. with a heater, for example, 60 to 100 A is provided between the cathode electrode (evaporation source) made of an Al—Cr—Ti alloy having a predetermined composition and the anode electrode. An arc discharge current is generated, and simultaneously nitrogen gas is introduced into the apparatus as a reaction gas to create a reaction atmosphere of 1 to 6 Pa, for example, while a DC bias voltage of −50 to −100 V is applied to the tool base from a bias power source, for example. (Hereinafter referred to as normal 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 modified film forming conditions), an (Al, Cr, Ti) N layer (hereinafter referred to as modified (Al, Cr, Ti) N layer) formed by vapor deposition under these conditions is normally formed. Compared with the (Al, Cr, Ti) N layer formed under the conditions, the grain boundary strength of the crystal grains is enhanced, and as a result, the high temperature strength of the hard coating layer is further improved. The hard coating layer exhibits excellent fracture resistance even during heavy cutting with a load, and exhibits excellent wear resistance over a long period of time.

(B) The (Al, Cr, Ti) N layer (hereinafter referred to as the conventional (Al, Cr, Ti) N layer) constituting the hard coating layer of the conventional coated tool and the modification (Al, For the Cr, Ti) N layer,
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, when an inclination angle number distribution graph is created by counting the frequencies existing in each section, for example, as shown in FIG. 3, 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 indicates a tilt angle number distribution graph that occupies a ratio of 60% or more of the entire frequency in the tilt angle number distribution graph, the modification (Al, Cr , Ti) N layer is the normal direction of the polished surface In contrast, to show the crystal orientation is oriented strongly the (112) plane.

(C) The above-described modified (Al, Cr, Ti) N layer is not limited to the conventional (Al, Cr, Ti) N layer itself, in addition to the conventional (Al, Cr, Ti) N layer. Since it has a much higher high-temperature strength than the N layer, the coated tool formed by vapor deposition as a hard coating layer can be used for heavy cutting that requires a particularly large mechanical load on the cutting edge. The hard coating layer exhibits even better fracture resistance than the conventional coating tool formed by vapor deposition of the (Al, Cr, Ti) N layer.
The research results shown in (a) to (c) above were obtained.

This invention was made based on the above research results,
“Al, Cr, and Ti having an average layer thickness of 1 to 10 μm on the surface of a tool base made of tungsten carbide base cemented carbide, titanium carbonitride base cermet, or cubic boron nitride base ultra high pressure sintered material In a surface-coated cutting tool formed by vapor-depositing a hard coating layer composed of a composite nitride layer of
The composite nitride layer of Al, Cr and Ti is
Composition _formula: When expressed in _{(Al 1-X-Y Cr} X Ti Y) N,
0.3 ≦ X ≦ 0.6, 0.1 ≦ Y ≦ 0.3 (where X and Y represent atomic ratios), 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 (Al, Cr, Ti) N layer of the present invention will be described in detail.
(A) the composition formula _{(Al 1-X-Y Cr} X Ti Y) N
Cr component in the hard coating layer represented by chemical composition by the composition formula _{(Al 1-X-Y Cr} X Ti Y) N maintenance of heat resistance, Ti component improves the high temperature strength, Al component high-temperature hardness and high temperature oxidation The hard coating layer is a layer having a predetermined high-temperature strength, high-temperature hardness, and heat resistance because it contributes to improving the chemical conversion. However, if the Cr content ratio X is less than 30 atomic%, the hard coating layer The heat resistance of the layer cannot be maintained. On the other hand, if the Cr content ratio X exceeds 60 atomic%, the high temperature hardness and the high temperature oxidation resistance decrease, and as a result, the wear resistance decreases. Therefore, the value of the Cr content ratio X was determined to be 0.3 to 0.6. Further, when the Ti content ratio Y is less than 10 atomic%, the high-temperature strength decreases. On the other hand, when the Ti content ratio Y exceeds 30 atomic%, the heat resistance and high-temperature oxidation resistance decrease. The content ratio Y was determined to be 0.1 to 0.3.

(B) Orientation ratio of crystal plane Crystal grains having a cubic crystal lattice existing in the measurement range of the surface polished surface using a field emission scanning electron microscope for the modified (Al, Cr, Ti) N layer. Individually irradiating with an electron beam, measuring the inclination angle formed by the normal of the {100} plane, which is the crystal plane of the crystal grain, with respect to the normal of the surface polished surface, The measured inclination angle within the range of 0 to 45 degrees is divided into 0.25 degree pitches, and an inclination angle number distribution graph is created by summing up the frequencies existing in each division. As shown, the highest peak exists in the inclination angle section within the range of 30 to 40 degrees, and the sum of the frequencies existing within the range of 30 to 40 degrees is 60% of the entire degrees in the inclination angle distribution graph. From the graph showing the distribution of the number of inclination angles In the modified (Al, Cr, Ti) N layer, it can be seen that the {112} plane is strongly oriented with respect to the normal direction of the surface polished surface. Compared with the conventional (Al, Cr, Ti) N layer formed in step 1, the grain boundary strength of the crystal grains is further improved. As a result, a modified (Al, Cr, Ti) N layer is provided as a hard coating layer. The coated tool is further improved in fracture resistance even under heavy cutting conditions.

(C) Average layer thickness If the average layer thickness of the modified (Al, Cr, Ti) N 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. The tool life is short-lived. On the other hand, if the average layer thickness exceeds 10 μm, chipping tends to occur. Therefore, the average layer thickness is set to 1 to 10 μm.

Next, the film forming conditions for the modified (Al, Cr, Ti) N layer of the present invention will be described in detail.
In producing a coated tool having a modified (Al, Cr, Ti) N layer deposited by arc ion plating as a hard coating layer,
A tool base is disposed on a rotary table in an arc ion plating apparatus, an Al—Cr—Ti alloy having a predetermined composition 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 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 base on the rotary table, Apply a bipolar pulse bias consisting of 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). In addition, an arc discharge is generated by passing a current of 60 to 200 A between the cathode electrode and the anode electrode made of the Al—Cr—Ti alloy, and the composition formula: (Al _1-XY) Modification (Al) satisfying 0.3 ≦ X ≦ 0.6 and 0.1 ≦ Y ≦ 0.3 (where X and Y indicate atomic ratios) when expressed by Cr _X Ti _Y ) N , Cr, Ti) An N layer 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 of the present invention and the manufacturing method thereof, the modified (Al, Cr, Ti) N which is a hard coating layer even in heavy cutting processing such as steel and cast iron which requires a very large mechanical load on the cutting edge. It is possible to provide a coated tool in which the layer has excellent high-temperature strength and exhibits excellent fracture resistance, and this coated tool does not cause defects in the hard coating layer and can be used for a long time. Exhibits excellent wear resistance.

  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.

Next, each of these tool bases A to F, G to L, and M to R is ultrasonically cleaned in acetone and dried, on the rotary table in the arc ion plating apparatus shown in FIG. Attached along the outer periphery at a position that is a predetermined distance in the radial direction from the central axis of the electrode, and modified as a cathode electrode (evaporation source) with a component composition corresponding to the target composition shown in Tables 5 to 7 (Al , Cr, Ti) Al-Cr-Ti alloy for N layer formation is arranged,
(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) Nitrogen 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, the tool base temperature is maintained at the temperature shown in Table 4, and the table rotates on the rotary table. However, a bipolar pulse bias having the conditions shown in Table 4 is applied to the rotating tool base from the bias power source, and the cathode electrode (Al—Cr—Ti for forming the modified (Al, Cr, Ti) N layer is formed. An arc discharge is generated by flowing a current of 100 A between the alloy) and the anode electrode, and the target composition and target layer thickness modification (Al, Cr, Ti shown in Tables 5 to 7 is applied to the surface of the tool base. ) The coated tools 1 to 18 of the present invention were produced by forming the N layer by vapor deposition.

  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 (Al, Cr, Ti) N layer under the same conditions.

Next, a field emission scanning electron microscope is used for the modified (Al, Cr, Ti) N layer and the conventional (Al, Cr, Ti) N layer constituting the hard coating layer of the present invention coated tool and the conventional coated tool. Each of them was used to create an inclination angle number distribution graph.
First, the inclination angle number distribution graph shows a field emission scanning electron microscope in a state where the surfaces of the modified (Al, Cr, Ti) N layer and the conventional (Al, Cr, Ti) N layer are polished surfaces. A crystal having a cubic crystal lattice existing in the measurement range of the surface polished surface with an electron beam with an acceleration voltage of 15 kV and an irradiation current of 1 nA at an incident angle of 70 degrees on the polished surface. Irradiate each grain, and using an electron backscatter diffraction imaging apparatus, a region of 30 × 50 μm at a spacing of 0.1 μm / step is the crystal plane of the crystal grain with respect to the normal of the surface polished surface The inclination angle formed by the normal line of the {100} plane is measured, and based on the measurement result, the measurement inclination angle within the range of 0 to 45 degrees among the measurement inclination angles is set for each pitch of 0.25 degrees. By classifying and counting the frequencies existing in each class Form was.

  In the gradient angle distribution graphs of various modified (Al, Cr, Ti) N layers and conventional (Al, Cr, Ti) N layers obtained as a result, they exist in the measured tilt angle section of 30 to 40 degrees. The frequencies 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 (Al, Cr, Ti) N layer of the coated tool of the present invention has a very high {112} plane orientation ratio. The conventional (Al, Cr, Ti) N layer of the conventional coated tool has a low orientation ratio of the {112} plane against (the ratio of 60% or more of the entire frequency in the inclination angle distribution graph). .
3 is a graph showing the distribution of the number of inclination angles of the modified (Al, Cr, Ti) N layer of the coated tool 1 of the present invention, and FIG. 4 is a diagram of the conventional (Al, Cr, Ti) N layer of the conventional coated tool 1. An inclination angle number distribution graph is shown 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 the former and the latter consisted of an (Al, Cr, Ti) N 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: 210 m / min,
Cutting depth: 3.0 mm,
Feed: 0.32 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,
Infeed: 3.2 mm,
Feed: 0.32 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: 220 m / min,
Cutting depth: 2.2 mm,
Feed: 0.3 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: 1.8 mm,
Feed: 0.15 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: 210 m / min,
Cutting depth: 2.0 mm,
Feed: 0.12 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: 200 m / min,
Cutting depth: 1.5 mm,
Feed: 0.25 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: 220 m / min,
Cutting depth: 0.25 mm,
Feed: 0.20 mm / rev,
Cutting time: 6 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: 180 m / min,
Cutting depth: 0.32 mm,
Feed: 0.15 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: 190 m / min,
Cutting depth: 0.24 mm,
Feed: 0.26 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 total frequency in the inclination angle distribution graph) (Al , Cr, Ti) N layer is a hard coating layer, and the modified (Al, Cr, Ti) N layer has a higher high-temperature strength even in heavy cutting of steel and cast iron with extremely large mechanical load. Therefore, the hard coating layer is composed of the conventional (Al, Cr, Ti) N layer having a low orientation ratio of {112} plane while exhibiting excellent fracture resistance and at the same time exhibiting excellent wear resistance. In the conventional coated tools 1-18, since the high temperature strength of the hard coating layer is insufficient, the hard coating layer is damaged in heavy cutting, and the service life is reached in a relatively short time. Is clear.

  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 a schematic diagram which shows the crystal structure of the NaCl type face centered cubic crystal which the (Al, Cr, Ti) N layer which comprises a hard coating layer has. It is an inclination angle number distribution graph of the modification | reformation (Al, Cr, Ti) N layer which comprises the hard coating layer of this invention coated tool 1. It is an inclination angle number distribution graph of the conventional (Al, Cr, Ti) N layer which comprises the hard coating layer of the conventional coating tool 1. FIG.

Claims (1)

Al, Cr, and Ti having an average layer thickness of 1 to 10 μm are formed 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 composed of a composite nitride layer,
The composite nitride layer of Al, Cr and Ti is
Composition _formula: When expressed in _{(Al 1-X-Y Cr} X Ti Y) N,
0.3 ≦ X ≦ 0.6, 0.1 ≦ Y ≦ 0.3 (where X and Y represent atomic ratios), 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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