JP5239292B2 - Surface-coated cutting tool with excellent fracture resistance due to hard coating layer - Google Patents

Description

  The present invention shows excellent fracture resistance due to the biaxial orientation of the hard coating layer, and therefore severe cutting conditions such as heavy cutting such as steel and cast iron that impose a large mechanical load on the cutting edge. The present invention also relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that can extend the life of the cutting tool.

  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 grooves. 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, Ti (on the surface of a tool base made of tungsten carbide (hereinafter referred to as WC) based cemented carbide or cubic boron nitride (hereinafter referred to as cBN) based ultrahigh pressure sintered material is formed on the surface of Ti ( C _{1 -X} N _X ) (wherein X is 0.40 to 0.98 in atomic ratio) and (111) high orientation of (111) plane carbon nitride [hereinafter referred to as (Ti (C , N)], and a coating tool having a hard coating layer formed by vapor deposition has been proposed, and this coating tool has excellent adhesion to the hard coating layer and excellent wear resistance. Are known.
JP-A-4-103754 JP 2002-346811 A

  In recent years, 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 processing, and accordingly, heavy cutting processing such as high feed and high cutting is required. However, with the above-mentioned conventional coated tools, there are no particular problems when various types of steel and cast iron are machined under normal conditions, but for heavy-duty machining that places a heavy load on the cutting edge. When used, the cutting edge is likely to be damaged, and due to this, the service life is reached in a relatively short time.

In view of the above, the present inventors pay attention to the Ti (C, 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 −300 V,
Cathode electrode: Ti metal,
Arc discharge current between the cathode electrode and the anode electrode: 60 to 100 A,
Gas flow in the apparatus: nitrogen (N ₂ ) gas 600 sccm, methane gas 250 sccm,
In-apparatus gas pressure: 2-3 Pa,
Under the above conditions (hereinafter referred to as normal conditions), the hard coating layer satisfies the above composition formula: Ti (C _1-X N _X ) (where X is 0.40 to 0.98 in atomic ratio). C, N) layer [hereinafter referred to as a conventional Ti (C, N) layer].
However, the formation of the Ti (C, N) layer is performed, for example, on an ion plating apparatus using a pressure gradient type Ar plasma gas, which is one of physical vapor deposition apparatuses schematically shown in FIG. Wearing
Tool substrate temperature: 350 to 500 ° C.
Evaporation source: Metal Ti,
Plasma gun discharge power: 10-15 kW,
Gas flow in the apparatus: Nitrogen (N ₂ ) gas 15-35 sccm, methane gas 5-15 sccm,
In-apparatus gas pressure: 0.04-0.08 Pa,
DC bias voltage applied to tool substrate: -5 to -30 V
And
Ar plasma gun discharge power for plasma assist: 5-10 kW
As a result, the Ti (C, N) layer formed as a result (hereinafter referred to as the modified Ti (C, N) layer) is the conventional Ti (C, N) layer. Excellent fracture resistance in heavy cutting with severe cutting conditions such as high depth of cut and high feed compared to layers.

(B) With respect to the modified Ti (C, N) layer of (a) and the conventional Ti (C, 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. A tilt angle formed by the crystal orientation <112> of the crystal grain with respect to the line, and a measured tilt angle within a range of 0 to 55 degrees between the measured tilt angle and the normal direction. When the pitches of 0.25 degrees are divided and the frequencies existing in each section are tabulated, and the angle θ formed between adjacent crystal grains constituting each crystal grain boundary is measured and tabulated, The Ti (C, N) layer has a crystal orientation <112> of crystal grains with respect to the normal line of the surface polished surface. Even if the tilt angle distribution has a peak in the tilt angle section in the range of 0 to 15 degrees with respect to the normal direction, the angle distribution of the crystal grain boundaries is small angle grain boundaries (0 <θ The distribution of the measured tilt angles of the crystal orientation <112> of the modified Ti (C, N) layer of (a) is illustrated in FIG. 4 while the ratio of ≦ 15 ° is as small as about 10%. As shown, the crystal grain area in which the crystal orientation <112> is present in the tilt angle section within the range of 0 to 15 degrees with respect to the normal direction indicates a crystal orientation in which the crystal grain area ratio is 50% or more of the total crystal grain area, Furthermore, in the angle distribution diagram of the crystal grain boundaries, the ratio of the small-angle grain boundaries (0 <θ ≦ 15 °) is 50% or more (FIG. 4).
Furthermore, the area ratio of the crystal grains in which the crystal orientation <112> exists within a range of 0 to 15 degrees with respect to the normal direction of the surface polished surface, and the ratio of the small-angle grain boundaries in the angular distribution of the crystal grain boundaries Varies depending on the substrate temperature, bias voltage, nitrogen gas flow rate, methane gas flow rate, and plasma assist conditions.

(C) According to many test results, the conditions for physical vapor deposition of the modified Ti (C, N) layer on the tool substrate by the RPD apparatus as described above, for example,
Substrate temperature: 350-500 ° C.,
Bias voltage: -5 to -30V
Nitrogen gas flow rate: 15-35sccm
Methane gas flow rate: 5-15sccm
Ar plasma gun discharge power for plasma assist: 5-10 kW
When adjusted as described above, the area ratio of the crystal grains in which the crystal orientation <112> 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, In the angular distribution of crystal grain boundaries, a crystal arrangement in which a ratio of 0 <θ ≦ 15 ° occupies 50% or more of all grain boundaries is shown, and modified Ti (C, N) showing such a crystal arrangement A coated tool formed by forming a layer as a hard coating layer should exhibit excellent fracture resistance and wear resistance over a long period of time in heavy cutting.
The research results shown in (a) to (c) above were obtained.

This invention was made based on the above research results,
And having an average layer thickness of 1 to 10 μm on the surface of the cutting tool base made of cemented carbide, cermet or cubic boron nitride based ultra high pressure sintered body, and
Composition formula: Ti (C _1-X N _X )
X represents 0.4 to 0.98 (however, the atomic ratio), and a Ti carbonitride layer is formed using an ion plasma using a pressure gradient type Ar plasma gun and a plasma assist Ar plasma gun. In a surface-coated cutting tool formed by physical vapor deposition with a coating device ,
For the Ti carbonitride 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 <112> of the crystal grains with respect to the normal direction of the surface polished surface is measured, and the measurement inclination angle is within a range of 0 to 55 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 having the crystal orientation <112> 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) When the angle formed by adjacent crystal grains constituting the crystal grain boundary is measured, the ratio of the small-angle grain boundary in which the angle formed is more than 0 degree and not more than 15 degrees indicates 50% or more of all the grain boundaries. ,
A surface-coated cutting tool (coated tool), wherein a hard coating layer made of a Ti carbonitride layer that simultaneously satisfies the above (a) and (b) is formed by vapor deposition. "
It has the characteristics.

In the modified Ti (C, N) layer constituting the hard coating layer of the coated tool of the present invention, the Ti component improves the high-temperature strength, the C component improves the hardness of the layer, and the N component There is an action to improve the strength of the layer, and by coexisting these components, it has high hardness and excellent strength, but the content ratio (X value) of the N component in the layer is If the atomic ratio in the total amount with the C component is less than 0.4, the desired strength improvement effect cannot be expected. On the other hand, if the content ratio (X value) also exceeds 0.98, the relative C Since the content ratio of the components becomes too small and the desired high hardness cannot be obtained, the X value was determined to be 0.4 to 0.98 in terms of atomic ratio.
Further, if the average layer thickness of the hard coating layer is less than 1 μm, it is insufficient to ensure the desired wear resistance. On the other hand, if the average layer thickness exceeds 10 μm, peeling or chipping of the film tends to occur. Therefore, the average layer thickness was set to 1 to 10 μm.

Further, as described above, the area ratio of the crystal grains in which the crystal orientation <112> exists within the range of 0 to 15 degrees with respect to the normal line of the surface polished surface of the modified Ti (C, N) layer, the grain boundaries The angle distribution varies depending on the deposition conditions by RPD, such as substrate temperature, bias voltage, nitrogen gas flow rate, methane gas flow rate, and plasma assist conditions. According to many test results, a pressure gradient type Ar plasma gun is used. Deposition conditions by ion plating are as follows: substrate temperature: 350 to 500 ° C
Bias voltage: -5 to -30 V
Nitrogen gas flow rate: 15-35 sccm
Methane gas flow rate: 5-15 sccm
Ar plasma gun discharge power for plasma assist: 5-10 kW
As a result, the area ratio of the crystal grains in which the crystal orientation <112> exists within the range of 0 to 15 degrees with respect to the normal line of the surface polished surface of the modified Ti (C, N) layer is the total crystal grain area And a modified Ti (C, N) layer showing a crystal arrangement in which the ratio of 0 ° <θ ≦ 15 ° occupies 50% or more of all grain boundaries in the angular distribution of crystal grain boundaries Therefore, the area ratio of the crystal grains having the crystal orientation <112> in the range of 0 to 15 degrees with respect to the normal is less than 50%, or the crystal grains In the angular distribution of the boundary, when the ratio of 0 ° <θ ≦ 15 ° is less than 50% of the whole grain boundary, the Ti (C, N) layer cannot be given the above crystal arrangement, As a result, the coated tool cannot be expected to have excellent fracture resistance.

  In the coated tool of the present invention, the modified Ti (C, N) layer constituting the hard coating layer exhibits a special crystal arrangement, and exhibits excellent fracture resistance in 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. Sintered under holding conditions, and after sintering, tool edge A-1 made of WC-based cemented carbide with ISO standard and CNMG120408 insert shape by applying a honing process of R: 0.03 to the cutting edge portion. A-10 was 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 B-1 to B-6 made of TiCN-based cermet having an insert shape of CNMG120408 were formed.

Next, each of the tool bases A-1 to A-10 and B-1 to B-6 was ultrasonically cleaned in acetone and dried, and mounted on the vapor deposition apparatus shown in FIG. As a source, metal Ti was attached. First, the inside of the apparatus was evacuated and the tool base was heated to 400 ° C. while maintaining a vacuum of 1 × 10 ⁻² Pa or less, and then Ar gas was introduced to 0.08 Pa. After that, by applying a bias voltage of −500 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, and then the evaporation source The pressure in the furnace is maintained at 0.08 Pa while the discharge power of the pressure gradient type Ar plasma gun is 12 kW, a bias voltage of −10 V is applied to the tool base, nitrogen gas is supplied at 30 sccm, and methane gas is supplied at 10 sccm. As the plasma assist condition, the discharge power of the Ar plasma gun is set to 8 kW, while the Ar plasma is irradiated to the tool base, the plasma beam is incident on the evaporation source to generate metal Ti vapor, and the tool base is ionized by the plasma beam. The surface-coated insert of the present invention (hereinafter referred to as the present invention) as the coated tool of the present invention is formed by vapor-depositing a modified Ti (C, N) layer having the target composition and target layer thickness shown in Table 3 on the surface as a hard coating layer. Inventive coated inserts) 1-16 were produced respectively.

  For comparison purposes, each of the tool bases A-1 to A-10 and B-1 to B-6 was ultrasonically cleaned in acetone and dried, and then the arc ion plating shown in FIG. Attached to the apparatus, a metal Ti and a tool substrate surface bombard cleaning metal Ti as a cathode electrode (evaporation source) are mounted, and first, the apparatus is evacuated and kept at a vacuum of 0.5 Pa or less with a heater. After heating the inside to 500 ° C., a DC bias voltage of −800 V is applied to the tool base, and a current of 100 A is passed between the bombard cleaning metal Ti and the anode electrode to generate arc discharge, The tool substrate surface is treated with Ti bombardment for 5 minutes, and then a mixed gas of nitrogen gas and methane gas is introduced into the apparatus as a reaction gas, and a predetermined atmosphere within a range of 1 to 6 Pa is introduced. At the same time, the DC bias voltage applied to the tool base is set to a predetermined voltage within a range of −60 to −300 V, and an arc discharge is caused by flowing an electric current of 80 A between the metal Ti as the cathode electrode and the anode electrode. Thus, a conventional coated insert as a conventional coated tool is formed by vapor-depositing a conventional Ti (C, N) layer having a target composition and target layer thickness shown in Table 4 on the surface of the tool base as a hard coating layer. 1 to 16 were produced.

Next, for the above-described coated inserts 1 to 10 and the conventional coated inserts 1 to 10, in the state where this is screwed to the tip of the tool steel tool with a fixing jig,
Work material: JIS / SNCM439 round direction bar with 4 equal intervals in the length direction,
Cutting speed: 210 m / min. ,
Cutting depth: 1.5 mm,
Feed: 0.27 mm / rev. ,
Cutting time: 3 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 1.0 mm and 0.18 mm / rev., Respectively),
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 250 m / min. ,
Cutting depth: 1.8 mm,
Feed: 0.27 mm / rev. ,
Cutting time: 3 minutes,
(Continuous cutting and feed are 1.2 mm and 0.16 mm / rev., Respectively),
Work material: JIS / SUS304 round bar,
Cutting speed: 230 m / min. ,
Incision: 2.4 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 8 minutes,
(Continuous cutting and feeding are 2.0 mm and 0.20 mm / rev., Respectively)
In each cutting test, the flank wear width of the cutting edge was measured.

Moreover, about the said invention covering inserts 11-16 and the conventional covering inserts 11-16, in the state which this was screwed to the front-end | tip part of the tool steel tool bit with a fixing jig,
Work material: JIS / SNCM439 round direction bar with 4 equal intervals in the length direction,
Cutting speed: 260 m / min. ,
Cutting depth: 1.6 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 3 minutes,
Dry interrupted heavy cutting test of alloy steel under the conditions (cutting condition A4) (normal cutting and feeding are 1.0 mm and 0.12 mm / rev., Respectively),
Work material: JIS · S45C lengthwise equal 4 round grooved round bars,
Cutting speed: 325 m / min. ,
Cutting depth: 1.5 mm,
Feed: 0.15 mm / rev. ,
Cutting time: 3 minutes,
(Continuous cutting and feed are 1.0 mm and 0.10 mm / rev., Respectively),
Work material: JIS / SUS304 round bar,
Cutting speed: 265 m / min. ,
Cutting depth: 1.6 mm,
Feed: 0.22 mm / rev. ,
Cutting time: 6 minutes,
(Continuous cutting and feed are 1.2 mm and 0.15 mm / rev., Respectively)
In each cutting test, the flank wear width of the cutting edge was measured.
Table 5 shows the measurement results of the cutting tests A1 to A6.

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 C-1 to C-10 are ultrasonically cleaned in acetone, and in a dry state, the tool bases C-1 to C-10 are attached to the vapor deposition apparatus shown in FIG. 2, and metal Ti is attached as an evaporation source. The tool base is heated to 400 ° C. while the inside of the apparatus is evacuated and kept at a vacuum of 1 × 10 ⁻² Pa or less. After Ar gas is introduced to 0.08 Pa, a bias of −200 V is applied to the tool base. By applying a voltage, the tool base is subjected to Ar bombardment for 20 minutes, and then the inside of the apparatus is once evacuated to about 1 × 10 ⁻³ Pa, and then the discharge power of the pressure gradient type Ar plasma gun for the evaporation source Is set to 12 kW, a bias voltage of −10 V is applied to the tool base, the discharge power of the Ar plasma gun is set to 8 kW as a plasma assist condition, and the tool base is irradiated with Ar plasma. A laser beam is incident to generate a vapor of metal Ti and ionize with a plasma beam, and a modified Ti (C, N) layer having a target composition and target layer thickness shown in Table 7 is used as a hard coating layer on the surface of the tool base. The surface-coated cBN-based insert of the present invention (hereinafter referred to as the present invention-coated insert) 21 to 30 as the present invention-coated tool was produced by vapor deposition.

  For comparison purposes, each of the tool bases C-1 to C-10 is ultrasonically cleaned in acetone and dried, and then loaded into the ordinary arc ion plating apparatus shown in FIG. As the cathode electrode (evaporation source), metal Ti corresponding to the target composition shown in Table 3 was attached. First, the inside of the apparatus was evacuated and kept at a vacuum of 0.1 Pa or less by using a heater. Is heated to 500 ° C., Ar gas is introduced to create an atmosphere of 0.7 Pa, and a DC bias voltage of −200 V is applied to the rotating tool base while rotating on the table, whereby the tool base surface Is bombarded with argon ions, and then nitrogen gas and acetylene gas are introduced as reaction gases into the apparatus to form a reaction atmosphere of 3 Pa and applied to the tool substrate. A bias voltage is set to -30 V, and arc discharge is generated between the cathode electrode and the anode electrode of the metal Ti, so that the target composition and target layer thickness shown in Table 3 are formed on the respective surfaces of the tool bases A to J. Conventional surface-coated cBN-based sintered inserts (hereinafter referred to as conventional coated inserts) 21 to 30 as conventional coated tools were produced by vapor-depositing and forming a hard coating layer composed of a conventional Ti (C, N) layer.

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 lengthwise equidistant 4 round grooved round bars,
Cutting speed: 210 m / min. ,
Cutting depth: 0.25 mm,
Feed: 0.18 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 0.10 mm and 0.10 mm / rev., Respectively),
[Cutting conditions B2]
Work material: JIS · SCr420 lengthwise equally spaced 4 rods with vertical grooves,
Cutting speed: 180 m / min. ,
Cutting depth: 0.22 mm,
Feed: 0.19 mm / rev. ,
Cutting time: 4 minutes,
Dry interrupted heavy cutting test of chrome steel quenching material under the conditions of (normal cutting and feeding are 0.10 mm and 0.10 mm / rev., Respectively),
[Cutting conditions B3]
Work material: JIS · SKD61 lengthwise equidistant four round grooved round bars,
Cutting speed: 180 m / min. ,
Cutting depth: 0.25 mm,
Feed: 0.19 mm / rev. ,
Cutting time: 5 minutes,
Dry interrupted heavy cutting test of die steel hardened material under the conditions (normal cutting and feeding are 0.12 mm and 0.10 mm / rev., Respectively),
[Cutting conditions C1]
Work material: JIS / SCr420 round bar,
Cutting speed: 250 m / min. ,
Cutting depth: 0.26 mm,
Feed: 0.2 mm / rev. ,
Cutting time: 5 minutes,
Dry continuous heavy cutting test of chrome steel quenching material under the conditions of (normal cutting and feeding are 0.15 mm, 0.15 mm / rev., Respectively),
[Cutting conditions C2]
Work material: JIS / SUJ2 round bar,
Cutting speed: 180 m / min. ,
Cutting depth: 0.18 mm,
Feed: 0.25 mm / rev. ,
Cutting time: 8 minutes,
Wet continuous heavy cutting test of a hardened material of bearing steel under the conditions (normal cutting and feeding are 0.15 mm and 0.12 mm / rev., Respectively),
[Cutting conditions C3]
Work material: JIS / SKD61 round bar,
Cutting speed: 220 m / min. ,
Cutting depth: 0.22 mm,
Feed: 0.23 mm / rev. ,
Cutting time: 6 minutes,
Dry continuous high speed heavy cutting test of die steel quenching material under the conditions of (normal cutting and feeding are 0.15 mm and 0.12 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, since the coated inserts 1 to 16 and 21 to 30 of the present invention all have a chipping resistance with an excellent hard coating layer, a large mechanical load is applied to the cutting edge. Even when it is used for such heavy cutting, there is no occurrence of defects in the hard coating layer, and it exhibits excellent wear resistance over a long period of time, whereas the hard coating layer has conventionally been Ti (C, It is apparent that the conventional coated inserts 1 to 16 and 21 to 30 composed of the N) layer have defects in the hard coating layer and reach the service life 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 D- having a shape of a 4-blade square with a diameter x length of the cutting edge 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. 1 to D-8 were produced.

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

  For comparison purposes, the conventional Ti (C, N) layer is vapor-deposited as a hard coating layer under the same conditions as the conventional Ti (C, 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: 125 m / min. ,
Groove depth (cut): 2 mm,
Table feed: 900 mm / min. ,
Die steel dry-type high feed groove cutting test under the conditions (normal cutting speed, cutting and feed are 55 m / min, 2.0 mm, and 330 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: 100 m / min. ,
Groove depth (cut): 6.0 mm,
Table feed: 750 mm / min. ,
Stainless steel dry-type high feed groove cutting test under the conditions (normal cutting speed, cutting and feed are 90 m / min, 4.0 mm, 270 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: 190 m / min. ,
Groove depth (cut): 10 mm,
Table feed: 1000 mm / min. ,
(2) High-groove dry groove cutting test of alloy steel under the following conditions (normal cutting speed, cutting and feed are 120 m / min, 8 mm, and 360 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 manufactured in Example 3 above were 8 mm (carbide substrates D-1 to D-3 for end mills), 13 mm (carbide substrates D-4 to D-6 for end mills), and 26 mm (carbide substrates for end mills). D-7 and D-8) were used, and from these three types of round bar sintered bodies, the diameter x length of the groove forming portion was 4 mm x 13 mm (by grinding). Drilling carbide substrates E-1 to E-3), 8 mm × 22 mm (drilling carbide substrates E-4 to E-6), and 16 mm × 45 mm (drilling carbide substrates E-7 and E-8) And the carbide substrates E-1 to E-8 for drills each having a two-blade shape with a twist angle of 30 degrees were manufactured.

  Next, honing is performed on the cutting blades of these carbide substrates E-1 to E-8 for drilling, and ultrasonic cleaning is performed in acetone together with the above test pieces, and the state is also shown in FIG. In the vapor deposition apparatus, the target composition and the target layer thickness shown in Table 12 are the same as the conditions for forming the modified Ti (C, N) layer in the coated inserts 1 to 16 of the present invention of Example 1 above. By depositing the modified Ti (C, N) layer as a hard coating layer, drills made of the surface coated cemented carbide of the present invention (hereinafter referred to as the present coated drill) 1 to 8 as the coated tool of the present invention are respectively provided. Manufactured.

  For comparison purposes, the conventional Ti (C, N) layer is vapor-deposited as a hard coating layer under the same conditions as the conventional Ti (C, 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 dimension: 100 mm × 250 mm, thickness: 50 mm JIS / SS400 plate material,
Cutting speed: 110 m / min. ,
Feed: 0.20 mm / rev. ,
Hole depth: 6 mm
Wet high feed drilling test of mild steel under the conditions of (normal feed is 0.12 mm / rev.),
About this invention coated drill 4-6 and conventional coated drills 4-6,
Work material: Plane size: 100 mm × 250 mm, thickness: 50 mm JIS / SUS316 plate material,
Cutting speed: 55 m / min. ,
Feed: 0.16 mm / rev. ,
Hole depth: 10 mm
Wet high feed drilling test of stainless steel under normal conditions (normal feed is 0.10 mm / rev.)
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 / SCMnH2 plate material,
Cutting speed: 60 m / min. ,
Feed: 0.16 mm / rev,
Hole depth: 20 mm
Wet high feed drilling test of high manganese cast steel under the conditions of (normal feed is 0.10 mm / rev.),
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.

The present invention coated inserts 1-16, 21-30, the present coated end mills 1-8, and the modified Ti (C, N) layers of the present coated drills 1-8 as the present coated tools obtained as a result, In addition, the composition of the conventional Ti (C, 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 conventional coated tools using an Auger spectroscopic analyzer. When measured, each showed substantially the same composition as the target composition.
Moreover, when the thickness of the modified Ti (C, N) layer and the conventional Ti (C, N) layer of the present coated tool and the conventional coated tool was measured with 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 Ti (C, N) layer of the above-described coated tool of the present invention and the conventional Ti (C, N) layer of the conventional coated tool, the surfaces of both the above Ti (C, N) layers are 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 of the {112} 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 55 degrees. A certain tilt angle is divided into pitches of 0.25 degrees and the frequency existing in each zone is totaled to create a tilt angle number distribution graph. In the same region, all crystal grains Measure the angle between adjacent grains that make up a boundary Then, when a graph showing the angles formed and the respective proportions was created, the conventional Ti (C, N) layer has a tilt angle distribution formed by the crystal orientation <112> of the crystal grains with respect to the normal of the surface polished surface, Even if there is a peak in the tilt angle section within the range of 0 to 15 degrees with respect to the normal direction, the angle distribution of the crystal grain boundaries is such that the ratio of the small-angle grain boundaries (0 ° <θ ≦ 15 °). The distribution of the measured tilt angle of the crystal orientation <112> of the modified Ti (C, N) layer of (a) is as small as about 10% (FIG. 5), as illustrated in FIG. A crystal orientation in which an area ratio of crystal grains having a crystal orientation <112> in an inclination angle section within a range of 0 to 15 degrees with respect to the normal direction is 50% or more of the total area of the crystal grains; In the angular distribution of grain boundaries, the crystal orientation is such that the ratio of 0 ° <θ ≦ 15 ° is 50% or more of all grain boundaries ( 4), the modified Ti (C, N) layer had the crystal arrangement as described above.

FIG. 4 shows the measured tilt angle distribution of the crystal orientation <112> with respect to the normal direction of the surface polished surface of the modified Ti (C, N) layer of the coated tool 1 of the present invention and the angular distribution of the grain boundaries.
FIG. 5 shows the angular distribution of the grain boundaries of the conventional Ti (C, N) layer of the conventional coated tool 1.
As is clear from the comparison between FIG. 4 and FIG. 5, the modified Ti (C, N) layer shows a crystal structure with a high (112) orientation and a high small-angle grain boundary ratio, It is apparent that the conventional Ti (C, N) layer has a crystal structure that is not special in terms of grain boundary character.

  From the results shown in Tables 3, 4, 7, 8, 11, and 12, all of the coated tools of the present invention have the (112) plane highly oriented and small angle of the modified Ti (C, N) layer constituting the hard coating layer. The grain boundary ratio shows a high ratio of crystal structure, and as a result it has excellent fracture resistance, whereas in the above various heavy cutting processing tests, it exhibits excellent fracture resistance and wear resistance. In conventional coated tools, the ratio of small-angle grain boundaries in the hard coating layer is low, and as a result, improvement in fracture resistance is not seen. Therefore, heavy cutting that requires a large mechanical load such as high cutting and high feed Then, it is clear that defects occur in a relatively short time and reach the service life.

  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 under heavy load, the hard coating layer made of the modified Ti (C, N) layer has excellent fracture resistance, and therefore 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 where the normal line of {112} plane which is the crystal plane of the crystal grain in the various Ti (C, 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 modified Ti (C, N) layer which has the special crystal arrangement 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 Ti (C, N) layer which comprises the hard coating layer of the conventional coating tool. The modified Ti (C, N) layer constituting the hard coating layer of the coated insert 1 of the present invention is measured by EBSD, and the measured inclination angle formed by the crystal orientation <112> of the crystal grains with respect to the normal direction of the surface polished surface; It is an angle distribution graph of a grain boundary. The conventional Ti (C, N) layer constituting the hard coating layer of the conventional coated insert 1 is measured by EBSD, and the measured tilt angle formed by the crystal orientation <112> of the crystal grain with respect to the normal direction of the surface polished surface, and the crystal grain It is an angle distribution graph of a field.

Claims (1)

On the surface of the cutting tool base made of cemented carbide, cermet or cubic boron nitride based ultra high pressure sintered body, has an average layer thickness of 1 to 10 μm, and
Composition formula: Ti (C _1-X N _X )
X represents 0.4 to 0.98 (however, the atomic ratio), and a Ti carbonitride layer is formed using an ion plasma using a pressure gradient type Ar plasma gun and a plasma assist Ar plasma gun. In a surface-coated cutting tool formed by physical vapor deposition with a coating device ,
For the Ti carbonitride 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 <112> of the crystal grains with respect to the normal direction of the surface polished surface is measured, and the measurement inclination angle is within a range of 0 to 55 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 having the crystal orientation <112> 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) When the angle formed by adjacent crystal grains constituting the crystal grain boundary is measured, the ratio of the small-angle grain boundary in which the angle formed is more than 0 degree and not more than 15 degrees indicates 50% or more of all the grain boundaries. ,
A surface-coated cutting tool, wherein a hard coating layer composed of a Ti carbonitride layer that simultaneously satisfies the above (a) and (b) is formed by vapor deposition.

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