JP5036338B2 - Surface-coated cutting tool with excellent fracture resistance due to hard coating layer - Google Patents

Description

  The present invention exhibits excellent fracture resistance due to the biaxial orientation of the hard coating layer, and therefore, even when used under severe cutting conditions such as heavy cutting of steel and cast iron, The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that can extend the service life.

    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 FA of cutting devices has been remarkable, and in addition, there are strong demands for labor saving, energy saving, cost reduction and efficiency for cutting, and with this, high-efficiency heavy cutting such as high feed and high cutting However, in the above-mentioned conventional coated tools, there is no particular problem when various steels and cast irons are machined under normal conditions, but the heavy load on the cutting blade is heavy. When used for cutting, the cutting edge is likely to be damaged, and this causes the service life to be reached in a relatively short time.

In view of the above, the present inventors have focused on the (Al, Cr) N layer, which is a hard coating layer, in order to further extend the service life of the conventional coated tool. , As a result of research,
(A) The above-mentioned conventional coated tool is, for example, mounted on the tool base on an arc ion plating (AIP) apparatus which is one type of physical vapor deposition apparatus schematically shown in FIG.
In-apparatus heating temperature: 300-500 ° C
DC bias voltage applied to the carbide substrate: −60 to −100 V,
Cathode electrode: Al-Cr alloy
Arc discharge current between the cathode electrode and the anode electrode: 60 to 100 A,
Nitrogen gas pressure in the apparatus: 1 to 6 Pa,
(Al _{1 -X} Cr _X ) N (wherein X is 0.30 to 0.60 in atomic ratio) as a hard coating layer under the conditions (hereinafter referred to as normal conditions) (Al , Cr) N layer [hereinafter referred to as a conventional (Al, Cr) N layer].
However, the formation of the (Al, Cr) N layer is performed by, for example, an ion plating apparatus (hereinafter referred to as an RPD apparatus) using a pressure gradient type Ar plasma gun, which is one type of physical vapor deposition apparatus schematically shown in FIG. And attach the above tool base to
Tool substrate temperature: 350 to 500 ° C.
Evaporation source: Al-Cr alloy
Plasma gun discharge power: 10-15 kW,
Nitrogen gas flow rate: 20-40 sccm,
DC bias voltage applied to tool base: -50 to -80 V
(Al, Cr) N layer [hereinafter referred to as a modified (Al, Cr) N layer] formed as a result of the deposition under the conditions of Excellent fracture resistance under heavy cutting conditions with high depth of cut and high feed.

(B) With respect to the modified (Al, Cr) N layer of (a) and the conventional (Al, Cr) N layer, crystals of individual crystal grains using an electron beam backscattering diffractometer (hereinafter referred to as EBSD) When the orientation was analyzed, as shown in the schematic explanatory diagram of FIG. 1, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polishing surface was irradiated with an electron beam, and the method of the surface polishing surface was determined. Measuring the tilt angle formed by the crystal orientation <100> of the crystal grains with respect to the line, and measuring the tilt angle between the measured tilt angle and the normal direction within a range of 0 to 54 degrees. By dividing the pitch into 0.25 degree pitches and counting the frequencies existing in each section, similarly, the modification (a) with respect to an arbitrary direction orthogonal to the normal line of the surface polishing surface (Al, The tilt angle formed by the crystal orientation <100> of the crystal grains of the Cr) N layer is measured, and the measured tilt Among the angles, when the measured inclination angle that is in the range of 0 to 54 degrees with respect to the normal direction is divided into pitches of 0.25 degrees and the frequencies existing in each section are tabulated, In the (Al, Cr) N layer, the distribution of the inclination angle formed by the crystal orientation <100> of the crystal grains with respect to the normal line of the surface polished surface is divided into inclination angle sections within a range of 0 to 15 degrees with respect to the normal direction. Even if it has a peak, the distribution of the measured tilt angle of the crystal orientation <100> with respect to an arbitrary direction orthogonal to the normal of the surface polished surface is unbiased within a range of 0 to 54 degrees, and is a special peak. 4 (FIG. 5), the distribution of the measured tilt angle of the crystal orientation <100> of the modified (Al, Cr) N layer of (a) is normal, as illustrated in FIG. Crystal grain surface having a crystal orientation <100> in a tilt angle section within a range of 0 to 15 degrees with respect to the direction The distribution of the measured tilt angle of the crystal orientation <100> with respect to an arbitrary direction perpendicular to the normal line of the surface polished surface indicates a crystal orientation in which the ratio is 50% or more of the total area of the crystal grains. The area of crystal grains where the highest peak is present and the crystal orientation <100> exists in the tilt angle section within the range of 15 degrees centered on the highest peak (within the range of the maximum peak tilt angle ± 7.5 degrees) The crystal orientation in which the ratio is 50% or more of the total area of the crystal grains (FIG. 4).
Furthermore, the area ratio of the crystal grains in which the crystal orientation <100> exists within the range of 0 to 15 degrees with respect to the normal direction of the surface polished surface, and the highest peak in the direction orthogonal to the normal Within the 15 degree range (within the maximum peak tilt angle ± 7.5 degree range), the area ratio of crystal grains where the crystal orientation <100> exists, and the highest peak appears in the direction perpendicular to the normal line The tilt angle section must be changed according to the substrate temperature, bias voltage, and nitrogen gas flow rate.

(C) According to many test results, the conditions for physical vapor deposition of the modified (Al, Cr) N layer on the tool base as described above by the RPD apparatus are as follows:
Substrate temperature: 350-500 ° C
Bias voltage: -50 to -80 V
Nitrogen gas flow rate: 20-40 sccm
When adjusted as described above, the area ratio of the crystal grains in which the crystal orientation <100> exists in the range of 0 to 15 degrees with respect to the normal of the surface polished surface occupies 50% or more of the total area of the crystal grains, The area ratio of the crystal grains in which the crystal orientation <100> exists within the range of 15 degrees centering on the highest peak existing in the specific inclination angle section perpendicular to the normal occupies 50% or more of the total area of the crystal grains. The coated tool formed by forming a modified (Al, Cr) N layer exhibiting such biaxial orientation as a hard coating layer has been used for a long time in heavy cutting. Exhibit excellent chipping resistance and wear resistance.
The research results shown in (a) to (c) above were obtained.

This invention was made based on the above research results,
“ By ion plating using a pressure gradient type Ar plasma gun on the surface of a cutting tool substrate made of cemented carbide, cermet or cubic boron nitride based ultra high pressure sintered body ,
Composition formula: (Al _1-X Cr _X ) N (where X is 0.30 to 0.60 in atomic ratio)
In a surface-coated cutting tool in which a composite nitride layer of Al and Cr having an average layer thickness of 1 to 10 μm is formed by vapor deposition,
When the crystal orientation of each crystal grain is analyzed using an electron beam backscatter diffraction (EBSD) device for the above-mentioned composite nitride layer of Al and Cr,
(A) The inclination angle formed by the crystal orientation <100> of the crystal grain with respect to the normal direction of the surface-polished surface is measured, and the measurement inclination angle is in the range of 0 to 54 degrees with respect to the normal direction. When the measured tilt angles are divided into pitches of 0.25 degrees and the frequencies existing in each section are tabulated, the crystal grains with crystal orientation <100> exist in the tilt angle sections within the range of 0 to 15 degrees. The crystal orientation in which the area ratio is 50% or more of the total area of the crystal grains,
(B) The inclination angle formed by the crystal orientation <100> of the crystal grains with respect to an arbitrary direction orthogonal to the normal line of the surface-polished surface is measured, and among the measurement inclination angles, 0 to 54 with respect to the normal direction. When the measured inclination angle within the degree range is divided into 0.25 degree pitches and the frequencies existing in each division are tabulated, the highest peak exists in the specific inclination angle division, and the highest peak is the center. A crystal orientation in which the area ratio of the crystal grains in which the crystal orientation <100> exists in the tilt angle section within the range of 15 degrees is 50% or more of the total area of the crystal grains,
Defect resistance with excellent hard coating layer by heavy cutting, characterized in that a hard coating layer composed of a composite nitride layer of Al and Cr showing the biaxial crystal orientation of (a) and (b) above is deposited. Coated tool (surface coated cutting tool)
It has the characteristics.

  In the modified (Al, Cr) N layer constituting the hard coating layer of the coated tool of the present invention, the Cr component improves the high temperature strength, while the Al component improves the high temperature hardness and heat resistance (high temperature characteristics). Therefore, when the X value indicating the content ratio of the Cr component is less than 0.30 in the ratio (atomic ratio) to the total amount with the Al component, the ratio of Al is relatively increased. The decrease in the high-temperature strength of the layer itself is inevitable, and as a result, chipping and the like are likely to occur. On the other hand, if the X value indicating the Cr ratio exceeds 0.60, the Al ratio is relatively decreased. Therefore, the desired excellent high temperature characteristics cannot be ensured, and this causes acceleration of wear. Therefore, the X value is set to 0.30 to 0.60, and the average layer of the hard coating layer If the thickness is less than 1 μm, the desired wear resistance is achieved. It is insufficient to guarantee, whereas when the average layer thickness exceeds 10 [mu] m, since the peeling or chipping of the film is likely to occur, determined the average layer thickness and 1 to 10 [mu] m.

In addition, as described above, the area ratio of crystal grains in which the crystal orientation <100> exists within the range of 0 to 15 degrees with respect to the normal line of the surface polished surface of the modified (Al, Cr) N layer, the normal line, and The area ratio of crystal grains having a crystal orientation <100> within a range of 15 degrees centering on the highest peak existing in a specific inclination angle section in an arbitrary direction orthogonal to each other, and the inclination angle section where the highest peak appears is For example, although it varies depending on the temperature of the substrate, the bias voltage, and the nitrogen gas flow rate, according to many test results, the deposition conditions by ion plating using a pressure gradient type Ar plasma gun
Substrate temperature: 350-500 ° C
Bias voltage: -50 to -80 V
Nitrogen gas flow rate: 20-40 sccm
As a result, the area ratio of the crystal grains in which the crystal orientation <100> exists within the range of 0 to 15 degrees with respect to the normal line of the surface polished surface of the modified (Al, Cr) N layer is the total crystal grain area Of crystal grains in which the crystal orientation <100> exists within a range of 15 degrees centering on the highest peak existing in a specific inclination angle section in an arbitrary direction orthogonal to the normal line Has reached the conclusion that a modified (Al, Cr) N layer exhibiting biaxial orientation that occupies 50% or more of the total area of crystal grains can be obtained. The area ratio of crystal grains having a crystal orientation <100> in the range of degrees is less than 50%, or 15 degrees centered on the highest peak existing in a specific inclination angle section in an arbitrary direction orthogonal to the normal line Area ratio of crystal grains having crystal orientation <100> in the range Is less than 50% of the total area of crystal grains, the (Al, Cr) N layer cannot be imparted with the biaxial orientation, and as a result, the coated tool is expected to have excellent fracture resistance. It can't be done.

  In the coated tool of the present invention, the modified (Al, Cr) N layer constituting the hard coating layer exhibits biaxial orientation, and exhibits excellent fracture resistance when heavy cutting such as steel and cast iron. This contributes to extending the service life.

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

As raw material powders, WC powder, TiC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder, all having an average particle diameter of 1 to 3 μm, were prepared. And then wet-mixed with a ball mill for 72 hours, dried, and press-molded into a green compact at a pressure of 100 MPa. The green compact was vacuumed at 6 Pa at a temperature of 1400 ° C. for 1 hour. Sintering is performed under holding conditions, and after sintering, tool bases A1 to A10 made of WC-base cemented carbide having an ISO standard / CNMG120408 insert shape are subjected to R: 0.03 honing processing on the cutting edge portion. Formed.

Further, as raw material powders, TiCN (mass ratio, TiC / TiN = 50/50) powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC, all having an average particle diameter of 0.5 to 2 μm. Prepare powder, Co powder, and Ni powder, mix these raw material powders into the composition shown in Table 2, wet mix for 24 hours with a ball mill, dry, and press-mold into green compact at 100 MPa pressure The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.03 to meet ISO standards / Tool bases B1 to B6 made of TiCN base cermet having a chip shape of CNMG120408 were formed.

Next, each of the above tool bases A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, and mounted on the vapor deposition apparatus shown in FIG. 2, and various component compositions are used as evaporation sources. First, the tool base was heated to 400 ° C. while evacuating the apparatus and maintaining a vacuum of 1 × 10 ⁻² Pa or less, and Ar gas was introduced. After setting the pressure to 0 Pa, by applying a bias voltage of −1000 V to the tool base, the tool base was treated with Ar bombardment for 20 minutes, and then the inside of the apparatus was once evacuated to about 1 × 10 ⁻³ Pa, The discharge power of the gradient Ar plasma gun is 12 kW, a bias voltage of −60 V is applied to the tool base, the nitrogen gas is supplied at 30 sccm, the pressure in the furnace is kept at 0.08 Pa, and the evaporation source is positive. The beam is incident to generate an Al—Cr alloy vapor and ionized with a plasma beam, and the tool substrate surface is modified (Al, Cr) with the target composition and target layer thickness shown in Table 3 having a biaxial orientation. ) The surface coating inserts of the present invention (hereinafter referred to as the present invention coated inserts) 1 to 16 as the coated tools of the present invention were produced by vapor-depositing the N layer as a hard coating layer, respectively.

  For the purpose of comparison, each of the tool bases A1 to A10 and B1 to B6 is ultrasonically cleaned in acetone and dried, and is attached to the arc ion plating apparatus shown in FIG. As the evaporation source, an Al—Cr alloy having various component compositions and metal Ti for cleaning the tool base surface bombard are mounted. First, the apparatus is evacuated and kept at a vacuum of 0.5 Pa or less with a heater. After heating the inside of the apparatus to 500 ° C., a DC bias voltage of −800 V was applied to the tool base, and an arc discharge was generated by flowing a current of 100 A between the metal Ti of the cathode electrode and the anode electrode. The surface of the tool base is treated with Ti bombardment for 5 minutes, and then nitrogen gas is introduced into the apparatus as a reaction gas, so that a predetermined nitrogen gas atmosphere within a range of 1 to 6 Pa is obtained. In addition, the DC bias voltage applied to the tool base is set to a predetermined voltage in the range of −60 to −100 V, and an arc of 80 A is passed between the cathode electrode Al—Cr alloy and the anode electrode. Conventionally as a conventional coated tool by generating an electric discharge and vapor-depositing a conventional (Al, Cr) N layer having the target composition and target layer thickness shown in Table 4 on the surface of the tool base as a hard coating layer. Coated inserts 1-16 were produced respectively.

First, for the present invention coated inserts 1 to 10 and the conventional coated inserts 1 to 10, in a state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 180 m / min. ,
Cutting depth: 3.5 mm,
Feed: 0.26 mm / rev. ,
Cutting time: 4 minutes,
A dry interrupted heavy cutting test of alloy steel under the following conditions (referred to as cutting conditions A1) (normal cutting and feeding are 1.55 mm and 0.22 mm / rev., Respectively),
Work material: JIS / S55C lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 275 m / min. ,
Infeed: 3.2 mm,
Feed: 0.28 mm / rev. ,
Cutting time: 3 minutes,
(Continuous cutting and feed are 1.5 mm and 0.2 mm / rev., Respectively)
Work material: JIS / SCr420 round bar,
Cutting speed: 200 m / min. ,
Cutting depth: 3.0 mm,
Feed: 0.35 mm / rev. ,
Cutting time: 15 minutes,
Dry continuous heavy cutting test of chrome steel under the conditions (referred to as cutting conditions A3) (normal cutting and feeding are 2.0 mm and 0.2 mm / rev., Respectively),
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are shown in Table 5.

Next, for the above-described coated inserts 11 to 16 and the conventional coated inserts 11 to 16, in a state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 180 m / min. ,
Cutting depth: 2.0 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 2 minutes,
A dry interrupted heavy cutting test of alloy steel under the conditions (referred to as cutting conditions a1) (normal cutting and feeding are 1.5 mm and 0.15 mm / rev., Respectively),
Work material: JIS / S55C lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 220 m / min. ,
Cutting depth: 2.0 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 2 minutes,
Of carbon steel under the following conditions (referred to as cutting conditions a2) (normal cutting and feeding are 1.5 mm and 0.15 mm / rev., Respectively),
Work material: JIS / SUS304 round bar,
Cutting speed: 180 m / min. ,
Cutting depth: 2.5 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 15 minutes,
Dry continuous heavy cutting test of chrome steel under the conditions (referred to as cutting condition a3) (normal cutting and feeding are 2.0 mm and 0.15 mm / rev., Respectively),
In each cutting test, the flank wear width of the cutting edge was measured. The measurement results are also shown in Table 5.

Further, 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 blending composition shown in Table 6, wet-mixed with a ball mill for 80 hours, dried, and then had a size of diameter: 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. Normal super-high in a superposed state After charging into the pressure sintering machine, sintering at ultra high pressure at a predetermined temperature within the range of pressure: 5 GPa, temperature: 1200-1400 ° 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 The brazing part (corner part) of the WC-based cemented carbide insert body having a shape (thickness: 4.76 mm × one side length: 12.7 mm square) is mass%, 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 is applied. The tool substrate C1~C10 having the insert shape of ISO standard SNGA120412 by performing finish polishing was produced, respectively.

Next, the tool bases C1 to C10 are ultrasonically cleaned in acetone and dried, and then mounted on the vapor deposition apparatus shown in FIG. 2, and an Al—Cr alloy having various component compositions is used as an evaporation source. First, the tool base is heated to 400 ° C. while evacuating the apparatus and kept at a vacuum of 1 × 10 ⁻² Pa or less, and then Ar gas is introduced to 2.0 Pa. The tool substrate is subjected to Ar bombardment treatment for 20 minutes by applying a bias voltage of −200 V to the inside, and then the inside of the apparatus is once evacuated to about 1 × 10 ⁻³ Pa, and then the discharge of the pressure gradient type Ar plasma gun is performed. The power is set to 12 kW, the plasma beam is incident on the evaporation source to generate an Al—Cr alloy vapor, and the ionization is performed by the plasma beam. The surface-coated cBN-based insert of the present invention as the coated tool of the present invention (hereinafter referred to as the coated insert of the present invention) is formed by vapor-depositing a modified (Al, Cr) N layer having a biaxial orientation of thickness as a hard coated layer. ) 21-30 were produced respectively.

  For comparison purposes, each of the tool bases C1 to C10 was ultrasonically cleaned in acetone and dried, and then charged into the ordinary arc ion plating apparatus shown in FIG. As the (evaporation source), an Al—Cr alloy having a component composition corresponding to the target composition shown in Table 3 was mounted. First, the apparatus was evacuated and kept at a vacuum of 0.1 Pa or less while being heated. After heating the inside of the apparatus to 500 ° C., Ar gas is introduced to make an atmosphere of 0.7 Pa, and a DC bias voltage of −200 V is applied to the tool base that rotates while rotating on the table. The surface of the tool base is bombarded with argon ions, and then nitrogen gas is introduced into the apparatus as a reaction gas to form a reaction atmosphere of 3 Pa and applied to the tool base. The bias voltage is lowered to -30 V to generate an arc discharge between the cathode electrode and the anode electrode of the Al-Cr alloy, and the target composition shown in Table 3 is formed on each surface of the tool bases A to J. And a conventional surface-coated cBN-based sintered insert (hereinafter referred to as a conventional coated insert) 21 to 30 as a conventional coated tool by vapor-depositing and forming a hard coating layer composed of an (Al, Cr) N layer having a target layer thickness. Manufactured.

Next, of the various coated inserts described above, the present coated inserts 21 to 30 and the conventional coated inserts 21 to 30 of the present invention with the fixing tool fixed to the tip of the tool steel tool. For the inventive coated inserts 21 to 25 and the conventional coated inserts 21 to 25, a cutting test is performed under the following cutting conditions B1 to B3, and for the present coated inserts 26 to 30 and the conventional coated inserts 26 to 30, Similarly, a cutting test was performed under the following cutting conditions C1 to C3.
[Cutting conditions B1]
Work material: JIS / SCM415 quenching material (HRC60), 4 longitudinally spaced round bars with equal intervals in the length direction,
Cutting speed: 200 m / min. ,
Cutting depth: 0.28 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 5 minutes,
Dry interrupted heavy cutting test of hardened material of alloy steel under the conditions (normal cutting and feeding are 0.15 mm and 0.15 mm / rev., Respectively),
[Cutting conditions B2]
Work material: JIS / SUJ2 quenching material (HRC60), 4 longitudinally spaced round bars with equal intervals in the length direction,
Cutting speed: 140 m / min. ,
Cutting depth: 0.2 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 4 minutes,
Dry interrupted heavy cutting test of the hardened material of the bearing steel under the conditions (normal cutting and feeding are 0.1 mm and 0.1 mm / rev., Respectively),
[Cutting conditions B3]
Work material: JIS · SKD61 quenching material (HRC61) in the longitudinal direction, four equally spaced round bars,
Cutting speed: 180 m / min. ,
Cutting depth: 0.2 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 4 minutes,
Dry interrupted heavy cutting test of die steel hardened material under normal conditions (normal cutting and feeding are 0.12 mm and 0.12 mm / rev., Respectively),
[Cutting conditions C1]
Work material: JIS / SCr420H (HRC60) round bar,
Cutting speed: 230 m / min. ,
Cutting depth: 0.28 mm,
Feed: 0.28 mm / rev. ,
Cutting time: 10 minutes,
Dry continuous heavy cutting test of chrome steel quenching material under the conditions of (normal cutting and feeding are 0.2 mm, 0.16 mm / rev., Respectively),
[Cutting conditions C2]
Work material: JIS / SUJ2 hardened material (HRC60) round bar,
Cutting speed: 180 m / min. ,
Cutting depth: 0.28 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 8 minutes,
Dry continuous heavy cutting test of hardened material of bearing steel under the conditions of (normal cutting and feeding are 0.18 mm and 0.14 mm / rev., Respectively),
[Cutting conditions C3]
Work material: JIS SKD61 (HRC61) round bar,
Cutting speed: 200 m / min. ,
Cutting depth: 0.28 mm,
Feed: 0.30 mm / rev. ,
Cutting time: 8 minutes,
Dry continuous heavy cutting test of die steel hardened material under the conditions of (normal cutting and feeding are 0.15 mm and 0.16 mm / rev., Respectively),
In each cutting test, the flank wear width (mm) of the cutting edge was measured. The measurement results are shown in Table 9.

  From the results shown in Tables 5 and 9, the coated inserts 1 to 16 and 21 to 30 of the present invention are all used for heavy cutting because the hard coating layer has excellent fracture resistance. However, no defects occur in the hard coating layer, and excellent wear resistance is exhibited over a long period of time, whereas the conventional coating inserts 1 to 16 in which the hard coating layer is a conventional (Al, Cr) N layer. In Nos. 21 to 30, it is clear that defects occur in the hard coating layer and the service life is reached in a short time.

As raw material powders, medium coarse WC powder having an average particle diameter of 5.5 μm, fine WC powder of 0.8 μm, TaC powder of 1.3 μm, NbC powder of 1.2 μm, ZrC of 1.2 μm Powder, 2.3 μm Cr ₃ C ₂ powder, 1.5 μm VC powder, 1.0 μm (Ti, W) C [50/50 by mass ratio] powder, and 1.8 μm Co Prepare powders, mix each of these raw material powders with the composition shown in Table 10, add wax, ball mill mix in acetone for 24 hours, dry under reduced pressure, and then press various pressures of a predetermined shape at a pressure of 100 MPa. The powder compact is press-molded, and these green compacts are heated to a predetermined temperature in the range of 1370 to 1470 ° C. at a heating rate of 7 ° C./min in a vacuum atmosphere of 6 Pa, and this temperature is maintained for 1 hour. After holding, sintering under the condition of furnace cooling, the diameter is 8 m, 13 mm, and 26 mm round bar sintered bodies for forming a carbide substrate were formed, and further, from the above three kinds of round bar sintered bodies, by grinding, in combinations shown in Table 6, Carbide substrate for end mill D1 having a shape of a four-blade square with a diameter x length of the cutting edge portion of 6 mm x 13 mm, 10 mm x 22 mm, and 20 mm x 45 mm, respectively, and a twist angle of 30 degrees. D8 was produced respectively.

  Then, these end mill carbide substrates D1 to D8 and the test pieces were ultrasonically cleaned in acetone and dried, and charged into the vapor deposition apparatus shown in FIG. The modified (Al, Cr) N layer having the target composition and target layer thickness shown in Table 11 is vapor-deposited as a hard coating layer under the same conditions as those for forming the modified (Al, Cr) N layer in the coated inserts 1-16. By forming, the surface coated cemented carbide end mills (hereinafter referred to as the present invention coated end mills) 1 to 8 as the present coated tools were produced, respectively.

  For comparison purposes, the conventional (Al, Cr) N layer is deposited as a hard coating layer under the same conditions as the conventional (Al, Cr) N layer formation conditions in the conventional coating inserts 1 to 16 of Example 1 above. Thus, conventional surface-coated cemented carbide end mills (hereinafter referred to as conventional coated end mills) 1 to 8 as conventional coated tools as shown in Table 11 were produced.

Next, of the present invention coated end mills 1-8 and the conventional coated end mills 1-8,
About this invention coated end mills 1-3 and conventional coated end mills 1-3,
Work material: Plane dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SKD61 plate material,
Cutting speed: 113 m / min. ,
Groove depth (cut): 2.8 mm,
Table feed: 1350 mm / min,
Tool steel dry high-speed high-feed groove cutting test under normal conditions (normal cutting speed and feed are 50 m / min and 150 mm / min, respectively)
About this invention coated end mills 4-6 and conventional coated end mills 4-6,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SUS304 plate,
Cutting speed: 89 m / min. ,
Groove depth (cut): 5 mm,
Table feed: 950 mm / min,
Stainless steel dry high-speed high-feed groove cutting test (normal cutting speed and feed are 50 m / min and 300 mm / min, respectively),
For the coated end mills 7 and 8 of the present invention and the conventional coated end mills 7 and 8,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SNCM439 plate material,
Cutting speed: 176 m / min. ,
Groove depth (cut): 10 mm,
Table feed: 950 mm / min,
Dry high-speed high-feed grooving cutting test of alloy steel (raw material) under the conditions (normal cutting speed and feed are 100 m / min and 300 mm / min, respectively)
In each groove cutting test, the cutting groove length was measured until the flank wear width of the outer peripheral edge of the cutting edge reached 0.1 mm, which is a guide for the service life. The measurement results are shown in Table 11, respectively.

  The diameters produced in Example 3 were 8 mm (carbide substrates D1 to D3 for end mills), 13 mm (carbide substrates D4 to D6 for end mills), and 26 mm (carbide substrates D7 and D8 for end mills). By using a round bar sintered body, the diameter x length of the groove forming part is 4 mm x 13 mm (carbide substrates E1 to E3 for drills) and 8 mm x by grinding. Carbide substrate for drills having a size of 22 mm (drilled carbide substrates E4 to E6) and 16 mm × 45 mm (carbide substrates for drills E7 and E8), and a two-blade shape with a twist angle of 30 degrees. E1 to E8 were produced.

  Next, honing is applied to the cutting edges of these carbide substrates E1 to E8 for drilling, and ultrasonic cleaning is performed in acetone together with the above-mentioned test pieces, and the dried blades are mounted in the vapor deposition apparatus shown in FIG. The target composition and target layer thickness modification (Al) shown in Table 12 under the same conditions as those for forming the modified (Al, Cr) N layer in the inventive coated inserts 1 to 16 of Example 1 above. , Cr) N layers were vapor-deposited as hard coating layers to produce the surface-coated cemented carbide drills (hereinafter referred to as the present invention-coated drills) 1 to 8 as the present coated tools.

  For comparison purposes, the conventional (Al, Cr) N layer is deposited as a hard coating layer under the same conditions as the conventional (Al, Cr) N layer formation conditions in the conventional coating inserts 1 to 16 of Example 1 above. Thus, conventional surface-coated cemented carbide drills (hereinafter referred to as conventional coated drills) 1 to 8 as conventional coated tools as shown in Table 12 were produced.

Next, of the present invention coated drills 1 to 8 and the conventional coated drills 1 to 8, the present invention coated drills 1 to 3 and the conventional coated drills 1 to 3 are:
Work material: Plane dimensions: 100 mm × 250 mm, thickness: 50 mm JIS / SKD61 plate material,
Cutting speed: 80 m / min. ,
Feed: 0.26 mm / rev,
Hole depth: 10 mm
Wet high-speed high-feed drilling test of tool steel under the following conditions (normal cutting speed and feed are 40 m / min and 0.12 mm / rev., Respectively),
About this invention coated drill 4-6 and conventional coated drills 4-6,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / FCD400 plate material,
Cutting speed: 120 m / min. ,
Feed: 0.35 mm / rev,
Hole depth: 20 mm
Wet high-speed high-feed drilling test of ductile cast iron under the conditions (normal cutting speed and feed are 70 m / min and 0.25 mm / rev., Respectively),
About this invention covering drills 7 and 8 and conventional covering drills 7 and 8,
Work material: Plane dimension: 100 mm × 250 mm, thickness: 50 mm JIS / S50C plate material,
Cutting speed: 162 m / min. ,
Feed: 0.58 mm / rev,
Hole depth: 0.50 mm
Wet high-speed high-feed drilling test of carbon steel under the conditions (normal cutting speed and feed are 65 m / min and 0.30 mm / rev., Respectively),
In each wet drilling cutting test (using water-soluble cutting oil), the number of drilling processes until the flank wear width of the tip cutting edge surface reached 0.3 mm was measured. The measurement results are shown in Table 12.

As a result, the present invention coated inserts 1-16, 21-30, the present coated end mills 1-8, and the modified (Al, Cr) N layers of the present coated drills 1-8 as the present coated tools, In addition, the composition of the conventional (Al, Cr) N layers of the conventional coated inserts 1 to 16, 21 to 30, the conventional coated end mills 1 to 8 and the conventional coated drills 1 to 8 as a conventional coated tool using an Auger spectroscopic analyzer. When measured, each showed substantially the same composition as the target composition.
Further, when the thicknesses of the modified (Al, Cr) N layer and the conventional (Al, Cr) N layer of the present invention coated tool and the conventional coated tool were measured using a scanning electron microscope, both were measured. The average layer thickness (average value of 5-point measurement) substantially the same as the target value was shown.

  Further, with respect to the modified (Al, Cr) N layer of the above-described coated tool of the present invention and the conventional (Al, Cr) N layer of the conventional coated tool, the surfaces of both the (Al, Cr) N layers are used as polished surfaces. In the state, the crystal orientation of each crystal grain was analyzed using an electron beam backscatter diffractometer (EBSD) (i.e., the method 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 of the {100} plane, which is the crystal plane of the crystal grain, is measured with respect to the line. Based on the measurement result, the inclination angle is within the range of 0 to 54 degrees. A certain inclination angle is divided into 0.25 degree pitches, and a frequency distribution graph is created by counting the frequencies existing in each division. Similarly, the normal of the surface polished surface (A) modification (Al, Cr) in any direction orthogonal to The tilt angle formed by the crystal orientation <100> of the crystal grains of the layer is measured, and the measured tilt angle within the range of 0 to 54 degrees among the measured tilt angles and the normal direction is 0.25 degrees. The conventional (Al, Cr) N layer has an inclination angle formed by the crystal orientation <100> of the crystal grains with respect to the normal of the surface polished surface. Even if the distribution may have a peak at an inclination angle within a range of 0 to 15 degrees with respect to the normal direction, the crystal orientation <100> with respect to an arbitrary direction orthogonal to the normal of the surface polishing surface. The distribution of the measured tilt angle is unbiased within the range of 0 to 54 degrees and does not show any particular peak (FIG. 5), whereas the crystal orientation of the modified (Al, Cr) N layer of (a) above. The distribution of the measured inclination angle of <100> is 0 to 1 with respect to the normal direction as illustrated in FIG. The crystal grain orientation in which the crystal orientation <100> exists in the tilt angle section within a range of 5 degrees indicates a crystal orientation in which the crystal grain area is 50% or more of the total crystal grain area, and is orthogonal to the normal line of the surface polished surface. The distribution of the measured tilt angle of the crystal orientation <100> with respect to an arbitrary direction has a maximum peak in a specific tilt angle section, and is within a range of 15 degrees centered on the highest peak (maximum peak tilt angle ± 7.5 The crystal grain orientation in which the crystal orientation <100> exists in the tilt angle section (within the range of degrees) indicates a crystal orientation in which the crystal grain area ratio is 50% or more of the total crystal grain area (FIG. 4), and modification (Al, Cr) The N layer had biaxial crystal orientation as described above.

FIG. 4 shows the measured inclination angle distribution of the crystal orientation <100> with respect to the normal direction of the surface polished surface of the modified (Al, Cr) N layer of the coated tool 3 of the present invention, and the direction orthogonal to the normal of the surface polished surface. 2 shows a measured tilt angle distribution of crystal orientation <100> with respect to.
Further, in FIG. 5, the measured tilt angle distribution of the crystal orientation <100> with respect to the normal direction of the surface polished surface of the conventional (Al, Cr) N layer of the conventional coated tool 2 is orthogonal to the normal of the surface polished surface. The measured tilt angle distribution of crystal orientation <100> with respect to an arbitrary direction is shown.
As is clear from the comparison between FIG. 4 and FIG. 5, the modified (Al, Cr) N layer exhibits biaxial crystal orientation, whereas the conventional (Al, Cr) N layer exhibits surface polishing. In the measurement of the crystal orientation <100> with respect to an arbitrary direction orthogonal to the normal of the surface, it is clear that there is a crystal structure that is not biaxially oriented because there is no measurement inclination angle showing a special peak.

  From the results shown in Tables 3, 4, 7, 8, 11, and 12, all of the coated tools of the present invention have a biaxial crystal orientation in the modified (Al, Cr) N layer constituting the hard coating layer. As a result, it has excellent fracture resistance, so in the various heavy cutting tests described above, it exhibits excellent wear resistance, whereas in conventional coated tools, the hard coating layer has a biaxial crystal. Since there is no orientation and no improvement in fracture resistance is observed as a result, in heavy cutting operations with large mechanical loads such as high cutting and high feed, fractures occur in a relatively short time and the service life is increased. It is clear that

  As described above, the coated tool of the present invention exhibits excellent tool characteristics in continuous cutting and intermittent cutting of various steels and cast irons, and also has a large machine for cutting edges such as high cutting and high feeding. Even under heavy cutting conditions with heavy loads, the hard coating layer made of the modified (Al, Cr) N layer has excellent fracture resistance, so it exhibits excellent cutting performance over a long period of time. It is possible to satisfactorily meet the demands for FA of processing equipment, labor saving and energy saving of cutting, and cost reduction.

It is a schematic explanatory drawing which shows the measurement range of the inclination angle with respect to the normal line of the surface polishing surface, with the normal line of the {100} plane being the crystal plane of the crystal grains in various (Al, Cr) N layers constituting the hard coating layer. It is a schematic explanatory drawing of the ion plating apparatus using the plasma used for vapor deposition formation of the modification | reformation (Al, Cr) N layer which has a biaxial crystal orientation which comprises the hard coating layer of this invention coating tool. It is a schematic explanatory drawing of the arc ion plating (AIP) apparatus used for vapor deposition formation of the conventional (Al, Cr) N layer which comprises the hard coating layer of the conventional coating tool. The modified (Al, Cr) N layer constituting the hard coating layer of the coated insert 3 of the present invention is measured by EBSD, and the measured inclination angle formed by the crystal orientation <100> of the crystal grain with respect to the normal direction of the surface polished surface; The measurement inclination angle formed by the crystal orientation <100> of the crystal grains in the range of 0 to 54 degrees with respect to an arbitrary direction orthogonal to the normal direction of the surface polished surface is divided for each pitch of 0.25 degrees. It is the inclination angle number distribution graph which totaled the frequency which exists in each division. The conventional (Al, Cr) N layer constituting the hard coating layer of the conventional coated insert 2 is measured by EBSD, and the measured inclination angle formed by the crystal orientation <100> of the crystal grain with respect to the normal direction of the surface polished surface, and the surface polishing The measured inclination angle formed by the crystal orientation <100> of the crystal grains in the range of 0 to 54 degrees with respect to an arbitrary direction orthogonal to the normal direction of the surface is divided for each pitch of 0.25 degrees. It is the inclination angle number distribution graph which totaled the frequency which exists in the inside.

Claims (1)

By ion plating using a pressure gradient type Ar plasma gun on the surface of a cutting tool substrate made of cemented carbide, cermet or cubic boron nitride based ultra high pressure sintered body ,
Composition formula: (Al _1-X Cr _X ) N (where X is 0.30 to 0.60 in atomic ratio)
In a surface-coated cutting tool in which a composite nitride layer of Al and Cr having an average layer thickness of 1 to 10 μm is formed by vapor deposition,
For the Al and Cr composite nitride layer, when analyzing the crystal orientation of individual crystal grains using an electron beam backscatter diffractometer,
(A) The inclination angle formed by the crystal orientation <100> of the crystal grain with respect to the normal direction of the surface-polished surface is measured, and the measurement inclination angle is in the range of 0 to 54 degrees with respect to the normal direction. When the measured tilt angles are divided into pitches of 0.25 degrees and the frequencies existing in each section are tabulated, the crystal grains with crystal orientation <100> exist in the tilt angle sections within the range of 0 to 15 degrees. The crystal orientation in which the area ratio is 50% or more of the total area of the crystal grains,
(B) The inclination angle formed by the crystal orientation <100> of the crystal grains with respect to an arbitrary direction orthogonal to the normal line of the surface-polished surface is measured, and among the measurement inclination angles, 0 to 54 with respect to the normal direction. When the measured inclination angle within the degree range is divided into 0.25 degree pitches and the frequencies existing in each division are tabulated, the highest peak exists in the specific inclination angle division, and the highest peak is the center. A crystal orientation in which the area ratio of the crystal grains in which the crystal orientation <100> exists in the tilt angle section within the range of 15 degrees is 50% or more of the total area of the crystal grains,
Defect resistance with excellent hard coating layer by heavy cutting, characterized in that a hard coating layer composed of a composite nitride layer of Al and Cr showing the biaxial crystal orientation of (a) and (b) above is deposited. Surface-coated cutting tool that demonstrates its properties.

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