JP2009056539A - Surface-coated cutting tool having hard coating 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 coating layer exhibiting excellent chipping resistance in heavy cutting. <P>SOLUTION: The surface coated cutting tool has the hard coating layer formed of an (Al<SB>1-X</SB>Cr<SB>X</SB>)N layer (where X=0.3 to 0.6). In an inclination angle frequency distribution graph of the hard coating layer, which is prepared by measuring inclination angles of a normal of a ä100} plane with respect to a normal of a front polishing surface of the surface coated cutting tool, a highest peak is present in an inclination angle zone ranging from 30 to 40 degrees, and the total frequencies in the angle zone amounts 60% or more of the entire frequencies. Further in a constituent atom covalent lattice point distribution graph of the hard coating layer, which is prepared by measuring an inclination angle of a normal of a ä112} plane with respect to the normal of the front polishing surface, a highest peak is present at Σ3, and a distribution percentage at Σ3 amounts 50% or more of the entire distribution. <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.
Further, 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 ultra high pressure. A composite nitride of Al and Cr satisfying (Al _1-X Cr _X ) N (wherein X is 0.30-0.60) on the surface of the tool body made of the sintered material [ Hereinafter, a coated tool formed by physically vapor-depositing a hard coating layer composed of (Al, Cr) N] has been proposed and used for continuous cutting and intermittent cutting of various steels and cast irons.
JP 2004-50381A Japanese Patent No. 3669700 JP 2006-524748 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 high-temperature strength of the (Al, Cr) N layer is insufficient, causing abnormal damage (hereinafter referred to as boundary abnormal damage) to the boundary part of the cutting edge, which tends to cause chipping. Is the current situation.

In view of the above, the present inventors, from the above viewpoint, in order to improve the fracture resistance of the coated tool, the hard coating layer (Al, Cr) N layer, that is, a schematic diagram in FIG. As shown, as a result of conducting extensive research, focusing on the (Al, Cr) N layer having a NaCl-type face-centered cubic crystal structure in which constituent atoms composed of Al, Cr, and nitrogen are present at lattice points,
(A) The conventional (Al, Cr) N layer constituting the hard coating layer of the conventional coated tool is, for example, a tool base mounted on an arc ion plating apparatus which is one type of the normal physical vapor deposition apparatus shown in FIG. An arc discharge current of, for example, 60 to 100 A is applied between a cathode electrode (evaporation source) made of an Al—Cr alloy having a predetermined composition and an anode electrode while the inside of the apparatus is heated to, for example, 300 to 500 ° C. with a heater. At the same time, nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 1 to 6 Pa, for example, while a DC bias voltage of −20 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 inside of 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 base from a bias power source to perform arc ion plating (hereinafter referred to as “arc ion plating”). And the (Al, Cr) N layer (hereinafter referred to as the modified (Al, Cr) N layer) formed by vapor deposition under these conditions are formed under the normal film formation conditions (Al , Cr) N grain layer strength is strengthened compared to the N layer, and as a result, the high temperature strength of the hard coating layer is further improved. However, the hard coating layer exhibits excellent fracture resistance and exhibits excellent wear resistance over a long period of time.

(B) The (Al, Cr) N layer (hereinafter referred to as the conventional (Al, Cr) N layer) constituting the hard coating layer of the conventional coated tool and the modified (Al, Cr) N layer of (a). about,
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, an inclination angle distribution graph in which the total frequency existing in the range of 30 to 40 degrees occupies a ratio of 60% or more of the entire frequencies in the inclination angle distribution graph is shown.

(C) In addition, for the conventional (Al, Cr) N layer and the modified (Al, Cr) N layer,
Using a field emission scanning electron microscope, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal plane of the crystal grain is normal to the surface polished surface { 112} plane normal angle is measured. In this case, the crystal grains have a NaCl-type face-centered cubic crystal structure in which constituent atoms composed of Al, Cr, and nitrogen are present at lattice points as described above. And, based on the measured tilt angle obtained as a result, at the interface between adjacent crystal grains, each of the constituent atoms shares one constituent atom between the crystal grains (constituent atom sharing). (Lattice point) distribution is calculated, and there are N lattice points (N is an even number of 2 or more in the crystal structure of the NaCl-type face-centered cubic crystal) between the constituent atom shared lattice points. The atomic shared lattice point form is represented by ΣN + 1, and each ΣN When a constitutive atomic shared lattice distribution graph showing the distribution ratio of +1 in the entire ΣN + 1 (however, the upper limit value of N is 28 due to the frequency) is created, the highest peak exists in Σ3 in any TiAlN layer However, the conventional (Al, Cr) N layer, as illustrated in FIG. 6, shows a relatively low constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 is 30% or less. The quality (Al, Cr) N layer, as illustrated in FIG. 5, shows a very high constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 is 50% or more.

(D) The above-described modified (Al, Cr) N layer is higher than the conventional (Al, Cr) N layer in addition to the high-temperature hardness and high-temperature strength of the conventional (Al, Cr) N layer itself. Since it has a much higher high-temperature strength, the coated tool formed by vapor deposition as a hard coating layer can be used even in heavy cutting where a particularly large mechanical load is applied to the cutting edge (Al, Compared to a coated tool formed by vapor-depositing a Cr) N layer, the hard coating layer will exhibit even better fracture resistance.
The research results shown in (a) to (d) above were obtained.

This invention was made based on the above research results,
“(1) Al 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 the surface-coated cutting tool formed by vapor-depositing a hard coating layer composed of a composite nitride layer of Cr,
The composite nitride layer of Al and Cr is
Composition formula: When expressed by (Al _1-X Cr _X ) N,
0.3 ≦ X ≦ 0.6 (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 inclination frequency distribution graph in which the total frequency to be used accounts for 60% or more of the entire frequency in the inclination angle distribution graph, and the composite nitride of Al and Cr with respect to the normal direction of the surface polished surface. The {112} plane is strongly oriented A surface-coated cutting tool (coated tool).
(2) In the surface-coated cutting tool according to (1),
Using a field emission scanning electron microscope, the surface polished surface is irradiated with an electron beam on each of the crystal grains having a cubic crystal lattice for the composite nitride of Al and Cr existing within the measurement range of the surface polished surface. The inclination angle formed by the normal of the {112} plane, which is the crystal plane of the crystal grain, is measured. In this case, the crystal grain has constituent atoms composed of Al, Cr, and nitrogen at lattice points. Each of the constituent atoms has a crystal structure of NaCl-type face-centered cubic crystals, and based on the measured inclination angle obtained as a result, each of the constituent atoms is between the crystal grains at the interface between adjacent crystal grains. The distribution of lattice points that share one constituent atom (constituent atom shared lattice point) is calculated, and N lattice points that do not share constituent atoms between the constituent atom shared lattice points (N is a NaCl-type face-centered cubic crystal) (It becomes an even number of 2 or more on the crystal structure) In the constituent atom shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the whole ΣN + 1 (however, the upper limit value of N is 28 in relation to the frequency) when the form of the shared atomic lattice point is represented by ΣN + 1, The surface-coated cutting tool (covered) according to (1) above, wherein a constituent atom shared lattice point distribution graph in which the highest peak exists in Σ3 and the distribution ratio of Σ3 to the entire ΣN + 1 is 50% or more is shown. tool). "
It has the characteristics.

First, the modified (Al, Cr) N layer of the present invention will be described in detail.
(A) the composition formula _{(Al 1-X Cr X)} N
Since the Cr component in the hard coating layer of the component composition represented by the composition formula (Al _1-X Cr _X ) N contributes to maintaining high-temperature strength, and the Al component contributes to improvement in high-temperature hardness and heat resistance, the hard coating layer is Although the layer has a predetermined high-temperature strength, high-temperature hardness, and heat resistance, if the Cr content ratio X is less than 30 atomic%, the high-temperature hardness and heat resistance of the hard coating layer are improved, but the Cr content Due to the relative decrease in the ratio, the high-temperature strength is reduced and defects are likely to occur. On the other hand, when the Cr content ratio X exceeds 60 atomic%, the high-temperature hardness and heat resistance decrease, resulting in wear resistance. Therefore, the Cr content ratio X was determined to be 0.3 to 0.6.

(B) Orientation ratio of crystal plane For the above modified (Al, Cr) 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 Irradiate an electron beam to measure the tilt 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. As shown in FIG. 3, a tilt angle distribution graph was created by dividing the measured tilt angle within the range of 45 degrees into pitches of 0.25 degrees and totaling the frequencies existing in each section. In addition, the highest peak is present 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% or more of the entire degrees in the inclination angle frequency distribution graph. Since the distribution graph of the number of inclination angles occupying the ratio is shown, In the (Al, Cr) 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 Al, Cr) N layer, the grain boundary strength of the crystal grains is further improved. As a result, the coated tool provided with the modified (Al, Cr) N layer as a hard coating layer is subjected to heavy cutting conditions. However, the fracture resistance is further improved.

(C) Distribution ratio of Σ3 Further, for the modified (Al, Cr) N layer, similarly, using a field emission scanning electron microscope, an electron beam is applied to each crystal grain existing within the measurement range of the surface polished surface. Irradiation is performed to measure the inclination angle formed by the normal of the {112} plane, which is the crystal plane of the crystal grain, with respect to the normal of the surface-polished surface. Have a NaCl type face centered cubic crystal structure in which constituent atoms composed of Al, Cr, and nitrogen respectively exist, and based on the measured tilt angle obtained as a result, at the interface between adjacent crystal grains, A distribution of lattice points (constituent atom shared lattice points) in which each constituent atom shares one constituent atom among the crystal grains is calculated, and there are N lattice points that do not share constituent atoms between the constituent atom shared lattice points. (N is 2 on the crystal structure of NaCl type face centered cubic crystal) The constituent atomic shared lattice point form existing (which is an even number above) is represented by ΣN + 1, and each ΣN + 1 represents the distribution ratio of the entire ΣN + 1 (provided that the upper limit of N is 28 due to frequency). When a lattice point distribution graph is created, the modified (Al, Cr) N layer has a very high configuration in which the highest peak exists in Σ3 and the distribution ratio of Σ3 is 50% or more as illustrated in FIG. Since the atomic shared lattice point distribution graph is shown, the modified (Al, Cr) N layer also has improved the grain boundary strength of the crystal grains, and as a result, the fracture resistance has further improved. I understand that.
As illustrated in FIG. 6, the conventional (Al, Cr) N layer also has the highest peak in Σ3, but the distribution ratio of Σ3 is only 30% or less, and the modified (Al, Cr) N layer In comparison, a relatively low constituent atom shared lattice point distribution graph is shown.
As described above, the modified (Al, Cr) N layer has a high {112} plane orientation and a high Σ3 distribution ratio, so that the conventional (Al, Cr) N layer has high temperature hardness and high temperature strength. In addition to heat resistance, it has even higher temperature strength.

(D) Average layer thickness If the average layer thickness of the modified (Al, Cr) 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, resulting in tool life. On the other hand, if the average layer thickness exceeds 10 μm, chipping is likely to occur. Therefore, the average layer thickness is set to 1 to 10 μm.

Next, the film forming conditions for the modified (Al, Cr) N layer of the present invention will be described in detail.
In producing a coated tool having a modified (Al, Cr) N layer formed by arc ion plating as a hard coating layer,
A tool base is arranged on a rotary table in the arc ion plating apparatus, an Al-Cr alloy is arranged 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, A bipolar pulse bias composed of a negative bias of applied voltage +5 to −100 (v) × application time 2000 to 20000 (ns) and a positive bias of applied voltage +32 to +42 (v) × application time 100 to 5000 (ns) is applied. In addition, an arc discharge is generated by flowing a current of 60 to 200 A between the cathode electrode and the anode electrode made of the Al—Cr alloy, and the composition formula: (Al _1-X Cr _X ) N The modified (Al, Cr) N layer satisfying 0.3 ≦ X ≦ 0.6 (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 −100 (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) N layer, which is a hard coating layer, is formed even in heavy cutting processing such as steel and cast iron in which a very large mechanical load is applied to the cutting edge. It is possible to provide a coated tool having excellent high-temperature strength and exhibiting excellent fracture resistance, and this coated tool does not cause a defect in the hard coating layer and is excellent over a long period of time. High 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 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) Al-Cr alloy for forming N layer 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. A bipolar pulse bias having the conditions shown in Table 4 is applied from a bias power source to the rotating tool base, and the cathode electrode (Al-Cr alloy for forming a modified (Al, Cr) N layer) and anode A current of 100 A is passed between the electrodes to generate an arc discharge, and a modified (Al, Cr) N layer having a target composition and a target layer thickness shown in Tables 5 to 7 is deposited on the surface of the tool base. By doing this, this invention coated tool 1-18 was manufactured, respectively.

  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) N layer under the same conditions.

Subsequently, the modified (Al, Cr) N layer and the conventional (Al, Cr) N layer constituting the hard coating layer of the present invention coated tool and the conventional coated tool are tilted using a field emission scanning electron microscope. An angular number distribution graph and a constituent atom shared lattice point distribution graph were prepared.
First, the tilt angle number distribution graph is shown in the column of a field emission scanning electron microscope in a state where the surfaces of the modified (Al, Cr) N layer and the conventional (Al, Cr) N layer are polished surfaces. Irradiating the polished surface with an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees with an irradiation current of 1 nA on each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface Then, using an electron backscatter diffraction image apparatus, a {100} plane which is a crystal plane of the crystal grain with respect to the normal line of the surface polished surface in a 30 × 50 μm region at an interval of 0.1 μm / step The inclination angle formed by the normal line is measured, and based on the measurement result, among the measurement inclination angles, the measurement inclination angle within the range of 0 to 45 degrees is divided for each pitch of 0.25 degrees, Created by counting the frequencies existing in each category.
Further, the constituent atomic shared lattice point distribution graph shows a mirror of a field emission scanning electron microscope in a state where the surfaces of the modified (Al, Cr) N layer and the conventional (Al, Cr) N layer are polished surfaces. An electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees is applied to the polished surface with an irradiation current of 1 nA to each crystal grain existing within the measurement range of the surface polished surface. Using a backscatter diffraction image apparatus, the normal of the {112} plane, which is the crystal plane of the crystal grain, with respect to the normal of the surface-polished surface in a 30 × 50 μm region at an interval of 0.1 μm / step Lattice points at which each of the constituent atoms shares one constituent atom between the crystal grains at the interface between adjacent crystal grains based on the measured inclination angle obtained as a result of the measurement. Calculate the distribution of (constituent atom shared lattice points) When ΣN + 1 represents a constituent atom shared lattice point form in which there are N lattice points that do not share constituent atoms between child shared lattice points (N is an even number of 2 or more in the crystal structure of NaCl type face centered cubic crystal) Each ΣN + 1 was created by determining the distribution ratio of ΣN + 1 in the entire ΣN + 1 (however, the upper limit value of N is 28 in relation to the frequency).

  In the gradient angle distribution graphs of various modified (Al, Cr) N layers and conventional (Al, Cr) N layers obtained as a result, the frequencies existing in the measured gradient angle section of 30 to 40 degrees are shown in Table 5. In addition, in the constituent atomic share lattice distribution graphs of the modified (Al, Cr) N layer and the conventional (Al, Cr) N layer, all of ΣN + 1 (N is in the range of 2 to 28). The distribution ratio of Σ3 in the even number) is shown in Tables 5 to 7, respectively.

In each of the above-mentioned various inclination angle number distribution graphs and constituent atom shared lattice point distribution graphs, as shown in Tables 5 to 7, the modified (Al, Cr) N layer of the coated tool of the present invention has a {112} plane. The orientation ratio is very high (ratio of 60% or more of the whole frequency in the tilt angle distribution graph), and the distribution ratio of Σ3 is also very high (ratio of 50% or more of the whole frequency in the constituent atom sharing lattice distribution graph). In contrast, the conventional (Al, Cr) N layer of the conventional coated tool has a low orientation ratio of {112} plane and a distribution ratio of Σ3.
3 is an inclination angle number distribution graph of the modified (Al, Cr) N layer of the coated tool 1 of the present invention, and FIG. 4 is an inclination angle number distribution of the conventional (Al, Cr) N layer of the conventional coated tool 1. FIG. 5 is a graph showing the distribution of constituent atomic shared lattice points of the modified (Al, Cr) N layer of the coated tool 1 of the present invention, and FIG. 6 is a conventional (Al, Cr) of the conventional coated tool 1. The constituent atomic shared lattice point distribution graph of N layer 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 both the former and the latter were composed of an (Al, Cr) 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: 200 m / min,
Infeed: 3.2 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: 300 m / min,
Cutting depth: 3.0 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: 180 m / min,
Cutting depth: 2.0 mm,
Feed: 0.35 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: 220 m / min,
Cutting depth: 1.5 mm,
Feed: 0.12 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: 220 m / min,
Cutting depth: 1.8 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: 220 m / min,
Cutting depth: 1.3 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: 180 m / min,
Cutting depth: 0.2 mm,
Feed: 0.22 mm / rev,
Cutting time: 8 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: 160 m / min,
Cutting depth: 0.35 mm,
Feed: 0.15 mm / rev,
Cutting time: 10 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: 200 m / min,
Cutting depth: 0.26 mm,
Feed: 0.24 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 orientation ratio of {112} plane (a ratio of 60% or more of the entire frequency in the tilt angle number distribution graph), and Σ3 The distribution ratio of is also very high (a ratio of 50% or more of the total frequency in the constituent atomic shared lattice distribution graph). The hard coating layer is composed of the modified (Al, Cr) N layer, and the mechanical load is extremely high. Even in heavy cutting of cast iron, the modified (Al, Cr) N layer has excellent high-temperature strength, so it exhibits excellent fracture resistance and at the same time exhibits excellent wear resistance. In the conventional coated tools 1 to 18 in which the hard coating layer is composed of the conventional (Al, Cr) N layer, which has a low {112} plane orientation ratio and Σ3 distribution ratio, all of them are hard coated by high-speed intermittent cutting. Insufficient high-temperature strength of the layer Therefore, it is clear that in the heavy cutting process, defects are generated 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 a schematic diagram which shows the crystal structure of the NaCl type face centered cubic crystal which the (Al, Cr) N layer which comprises a hard coating layer has. It is an inclination angle number distribution graph of the modification | reformation (Al, Cr) N layer which comprises the hard coating layer of this invention coated tool 1. FIG. It is an inclination angle number distribution graph of the conventional (Al, Cr) N layer which comprises the hard coating layer of the conventional coating tool 1. FIG. 3 is a constituent atomic shared lattice point distribution graph of a modified (Al, Cr) N layer constituting the hard coating layer of the coated tool 1 of the present invention. 4 is a constituent atomic shared lattice point distribution graph of a conventional (Al, Cr) N layer constituting a hard coating layer of a conventional coated tool 1.

Claims (2)

A composite nitriding of Al and Cr 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 ultra high pressure sintered material In a surface-coated cutting tool formed by vapor-depositing a hard coating layer consisting of a physical layer,
The composite nitride layer of Al and Cr is
Composition formula: When expressed by (Al _1-X Cr _X ) N,
0.3 ≦ X ≦ 0.6 (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. The surface-coated cutting tool according to claim 1,
Using a field emission scanning electron microscope, the surface polished surface is irradiated with an electron beam on each of the crystal grains having a cubic crystal lattice for the composite nitride of Al and Cr existing within the measurement range of the surface polished surface. The inclination angle formed by the normal of the {112} plane, which is the crystal plane of the crystal grain, is measured. In this case, the crystal grain has constituent atoms composed of Al, Cr, and nitrogen at lattice points. Each of the constituent atoms has a crystal structure of NaCl-type face-centered cubic crystals, and based on the measured inclination angle obtained as a result, each of the constituent atoms is between the crystal grains at the interface between adjacent crystal grains. The distribution of lattice points that share one constituent atom (constituent atom shared lattice point) is calculated, and N lattice points that do not share constituent atoms between the constituent atom shared lattice points (N is a NaCl-type face-centered cubic crystal) (It becomes an even number of 2 or more on the crystal structure) In the constituent atom shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the whole ΣN + 1 (however, the upper limit value of N is 28 in terms of frequency) when the atomic atom shared lattice point form is represented by ΣN + 1, 2. The surface-coated cutting tool according to claim 1, which shows a constituent atom shared lattice point distribution graph in which a highest peak exists in Σ3 and a distribution ratio of the Σ3 in the entire ΣN + 1 is 50% or more.

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