JP5287019B2 - Surface-coated cutting tool with excellent fracture resistance due to hard coating layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool with a hard coating layer demonstrating superior chipping resistance in heavy cutting. <P>SOLUTION: The hard coating layer is composed of a composite nitride layer of Cr and Al satisfying a composition formula (Cr<SB>1-x</SB>Al<SB>x</SB>)N (X is 0.40-0.70 by atomic ratio) on a cutting tool substrate surface consisting of cemented carbide, cermet, and a cubic boron nitride-based ultra high pressure sintered body. When a crystal orientation analysis by EBSD is carried out in regard to the composite nitride layer, an area portion of crystal grains having a crystal orientation of &lt;110&gt; within a range of 0-15 degrees from the normal direction of a surface polishing surface is 50% or more. The composite nitride layer of Cr and Al indicates such a crystal arrangement that the portion of the small angle grain boundary (0&lt;&theta;&le;15&deg;) is 50% or more when the angle of the adjacent crystal grains is measured. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention shows excellent chipping resistance due to the controlled crystal orientation and grain boundary character of the hard coating layer, and therefore heavy cutting such as steel and cast iron that imposes a large mechanical load on the cutting edge. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) that can extend the life of a cutting tool even when used under severe cutting conditions such as machining.

  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 Cr and Al satisfying (Cr _1−X Al _X ) N (wherein X is 0.40 to 0.70 in atomic ratio) 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 (Cr, Al) N] has been proposed and used for continuous cutting and intermittent cutting of various steels and cast iron.
JP 2004-50381A Japanese Patent No. 3669700 JP 2006-524748 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 (Cr, Al) 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: Cr-Al 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,
(Cr, Al) N layer satisfying the composition formula: (Cr _1-X Al _X ) N (wherein X is 0.40 to 0.70 in atomic ratio) It is manufactured by forming [hereinafter referred to as a conventional (Cr, Al) N layer].
However, the formation of the (Cr, Al) N layer is performed, for example, on an ion plating apparatus using a pressure gradient type Ar plasma gun, which is a kind of physical vapor deposition apparatus schematically shown in FIG. Wearing
Tool substrate temperature: 350 to 500 ° C.
Evaporation source: Cr-Al alloy,
Plasma gun discharge power: 3-6 kW,
Nitrogen gas flow rate: 50-70 sccm,
In-apparatus gas pressure: 0.04-0.08 Pa,
DC bias voltage applied to tool base: +5 to +10 V
When the Ar plasma gun discharge power for plasma assist is set to 2 to 4.5 kW and the substrate is irradiated with plasma to increase the ionization rate of the deposited particles, vapor deposition is performed as a result (Cr , Al) N layer [hereinafter referred to as a modified (Cr, Al) N layer] is superior to the conventional (Cr, Al) N layer in heavy cutting with severe cutting conditions such as high depth of cut and high feed. Show flaw resistance.

(B) With respect to the modified (Cr, Al) N layer of (a) and the conventional (Cr, Al) N layer, crystals of individual crystal grains using an electron beam backscatter 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 <110> of the crystal grains with respect to the line, and measuring the tilt angle within the range of 0 to 55 degrees with respect to the normal direction among the measured tilt angles. 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 (Cr, Al) N layer has a crystal grain orientation <11 with respect to the normal of the surface polished surface. Even if the inclination angle distribution formed by> has a peak in the inclination angle section within the range of 0 to 15 degrees with respect to the normal direction, the angle distribution of the crystal grain boundary is small-angle grain boundary (0 The distribution of the measured tilt angle of the crystal orientation <110> of the modified (Cr, Al) N layer of (a) is shown in FIG. 4 while the ratio of <θ ≦ 15 ° is as small as about 10%. As illustrated, the crystal orientation in which the area ratio of the crystal grains in which the crystal orientation <110> exists in the tilt angle section within the range of 0 to 15 degrees with respect to the normal direction is 50% or more of the total area of the crystal grains. Further, in the graph of the angle distribution between the crystal orientations <110> of adjacent crystal grains (hereinafter also referred to as “ angle distribution of crystal grain boundaries ”) , the small-angle grain boundary (0 <θ ≦ 15 °) The ratio is 50% or more (FIG. 4).
Furthermore, the area ratio of the crystal grains in which the crystal orientation <110> 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, and plasma assist conditions.

(C) According to many test results, the conditions for physical vapor deposition of the modified (Cr, Al) N layer on the tool base by the RPD apparatus as described above are, for example,
Substrate temperature: 350-500 ° C
Bias voltage: +5 to +10 V
Nitrogen gas flow rate: 50-70 sccm
Plasma assist conditions: Ar plasma gun discharge power 2 to 4.5 kW
When adjusted as described above, the area ratio of the crystal grains in which the crystal orientation <110> 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 the ratio of 0 <θ ≦ 15 ° occupies 50% or more of all grain boundaries is shown, and modified (Cr, Al) N showing such 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: (Cr _1-X Al _X ) N
In the surface-coated cutting tool in which a composite nitride layer of Cr and Al satisfying 0.40 to 0.70 (however, atomic ratio) is formed by vapor deposition,
For the composite nitride layer of Cr and Al, when analyzing the crystal orientation of individual grains using an electron beam backscattering diffractometer,
(A) The inclination angle formed by the crystal orientation <110> of the crystal grains 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 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 <110> 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 between the crystal orientations <110> of adjacent crystal grains constituting the crystal grain boundary is measured, the proportion of small-angle grain boundaries in which the formed angle is greater than 0 degree and equal to or less than 15 degrees is the total grain boundary 50% or more of
A surface-coated cutting tool (coated tool), wherein a hard coating layer composed of a composite nitride layer of Cr and Al that satisfies the above (a) and (b) at the same time is formed by vapor deposition. "
It has the characteristics.

  In the modified (Cr, Al) 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 Al component is less than 0.40 in the ratio (atomic ratio) to the total amount with the Cr component, the ratio of Cr is relatively increased. The high-temperature hardness of the layer decreases, and as a result, the wear resistance also decreases. On the other hand, when the X value indicating the Al ratio exceeds 0.70, the Cr ratio is relatively decreased. The decrease in the high-temperature strength of the layer is unavoidable and causes chipping and chipping. Therefore, the X value is set to 0.40 to 0.70, and the average thickness of the hard coating layer is If it is less than 1 μm, it is insufficient to ensure the desired wear resistance. There, 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 <110> exists in the range of 0 to 15 degrees with respect to the normal line of the surface polished surface of the modified (Cr, Al) N layer, the grain boundaries The angle distribution varies depending on the deposition conditions by RPD, for example, the temperature of the substrate, the bias voltage, the nitrogen gas flow rate, and the plasma assist conditions. However, according to many test results, an ion plate using a pressure gradient type Ar plasma gun is used. Deposition conditions by coating substrate temperature: 350-500 ° C
Bias voltage: +5 to +10 V
Nitrogen gas flow rate: 50-70 sccm
Plasma assist conditions: Ar plasma gun discharge power 2 to 4.5 kW
Thus, the area ratio of the crystal grains in which the crystal orientation <110> exists in the range of 0 to 15 degrees with respect to the normal line of the surface polished surface of the modified (Cr, Al) N layer is the total crystal grain area (Cr, Al) 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 <110> 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 total grain boundary, the (Cr, Al) 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 (Cr, Al) 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, Cr—Al alloys having various component compositions were mounted, and first the tool base was heated to 400 ° C. while evacuating the apparatus and maintaining a vacuum of 1 × 10 ⁻² Pa or less. After introducing Ar gas to 2.0 Pa, by applying a bias voltage of −1000 V to the tool base, the tool base is subjected to Ar bombardment for 20 minutes, and then the inside of the apparatus is temporarily 1 × 10 ⁻³ Pa. After applying a vacuum of a certain level, the discharge power of the pressure gradient type Ar plasma gun is 5 kW, a bias voltage of +5 V is applied to the tool base, and the pressure in the furnace is kept at 0.15 Pa while flowing nitrogen gas at 60 sccm. The gun discharge power is set to 3 kW, Ar plasma is irradiated onto the substrate, a plasma beam is incident on the evaporation source to generate Cr-Al alloy vapor, and ionization is performed with the plasma beam. The surface coating insert of the present invention (hereinafter referred to as the present invention coated insert) 1 as a coated tool of the present invention is formed by vapor-depositing a modified (Cr, Al) N layer having a target composition and a target layer thickness as a hard coating layer. ~ 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, as a cathode electrode (evaporation source), a Cr—Al alloy having various component compositions and a tool substrate surface bombardment cleaning metal Ti were attached. First, the inside of the apparatus was evacuated to 0.5 Pa or less. While maintaining the vacuum, the apparatus was heated to 500 ° C. with a heater, a DC bias voltage of −800 V was applied to the tool base, and a current of 100 A was applied between the bombard cleaning metal Ti and the anode electrode. An arc discharge is generated to flow, and the tool base surface is treated with Ti bombardment for 5 minutes. Then, nitrogen gas is introduced into the apparatus as a reaction gas, and a predetermined atmosphere within a range of 1 to 6 Pa is obtained. In addition, a DC bias voltage applied to the tool base is set to a predetermined voltage within a range of −60 to −100 V, and a current of 80 A is passed between the Cr—Al alloy as the cathode electrode and the anode electrode. Arc discharge is generated, and a conventional (Cr, Al) N layer having a target composition and target layer thickness shown in Table 4 is deposited on the surface of the tool base as a hard coating layer. Conventionally coated inserts 1-16 were produced, respectively.

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 · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 215 m / min. ,
Cutting depth: 1.0 mm,
Feed: 0.28 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 1.5 mm and 0.15 mm / rev., Respectively),
Work material: JIS / S50C lengthwise equal 4 round grooved round bars,
Cutting speed: 225 m / min. ,
Cutting depth: 1.4 mm,
Feed: 0.29 mm / rev. ,
Cutting time: 3 minutes,
(Continuous cutting and feeding are 1.5 mm and 0.15 mm / rev., Respectively),
Work material: JIS / SCr420 round bar,
Cutting speed: 265 m / min. ,
Incision: 2.4 mm,
Feed: 0.26 mm / rev. ,
Cutting time: 10 minutes,
Dry continuous heavy cutting test of chrome steel under the conditions (referred to as cutting conditions A3) (normal cutting and feeding are 1.5 mm and 0.18 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 · SCM440 lengthwise equidistant 4 vertical grooved round bar,
Cutting speed: 215 m / min. ,
Cutting depth: 1.2 mm,
Feed: 0.21 mm / rev. ,
Cutting time: 3 minutes,
A dry interrupted heavy cutting test of an 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 / S55C lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 250 m / min. ,
Cutting depth: 1.2 mm,
Feed: 0.18 mm / rev. ,
Cutting time: 3 minutes,
(Continuous cutting and feed are 1.0 mm and 0.12 mm / rev., Respectively),
Work material: JIS / SUJ2 round bar,
Cutting speed: 245 m / min. ,
Cutting depth: 1.4 mm,
Feed: 0.26 mm / rev. ,
Cutting time: 8 minutes,
Dry continuous heavy cutting test of bearing steel under the conditions (cutting condition A6) (normal cutting and feeding are 1.5 mm and 0.2 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 above tool bases C-1 to C-10 are ultrasonically cleaned in acetone and dried, and then mounted on the vapor deposition apparatus shown in FIG. 2, and Cr having various component compositions is used as an evaporation source. -Aluminum alloy was mounted, and first the tool base was heated to 400 ° C. while evacuating the apparatus and kept at a vacuum of 1 × 10 ⁻² Pa or less, and then Ar gas was introduced to 2.0 Pa. After that, by applying a bias voltage of −200 V to the tool base, 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 pressure gradient type Ar The plasma gun discharge power is set to 5 kW, a bias voltage of +8 V is applied to the tool base, the Ar plasma gun discharge power is set to 3.5 kW, and Ar plasma is irradiated onto the base while a plasma beam is introduced into the evaporation source. Cr-Al alloy vapor is generated and ionized with a plasma beam, and a modified (Cr, Al) N layer with a target composition and target layer thickness shown in Table 7 is deposited as a hard coating layer on the surface of the tool substrate. By forming, the present surface-coated cBN-based inserts (hereinafter referred to as the present invention-coated inserts) 21 to 30 as the present invention-coated tools were produced, respectively.

  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. Then, as the cathode electrode (evaporation source), a Cr—Al alloy having a component composition corresponding to the target composition shown in Table 3 is mounted, and the inside of the apparatus is first evacuated and kept at a vacuum of 0.1 Pa or less. However, after heating the inside of the apparatus to 500 ° C. with a heater, Ar gas was introduced to create an atmosphere of 0.7 Pa, and a DC bias voltage of −200 V was applied to the rotating tool base while rotating on the table. Then, 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 -30V to generate an arc discharge between the cathode electrode and the anode electrode of the Cr-Al alloy. Conventional surface-coated cBN-based sintered inserts (hereinafter referred to as conventional coated inserts) 21 to 30 as conventional coated tools are formed by vapor-depositing a hard coating layer composed of a conventional (Cr, Al) N layer having a composition and a target layer thickness. Were manufactured respectively.

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: 205 m / min. ,
Cutting depth: 0.24 mm,
Feed: 0.16 mm / rev. ,
Cutting time: 7 minutes,
Dry interrupted heavy cutting test of hardened material of alloy steel under the conditions (normal cutting and feeding are 0.2 mm and 0.12 mm / rev., Respectively),
[Cutting conditions B2]
Work material: JIS / SUJ2 lengthwise equidistant four round grooved round bars,
Cutting speed: 165 m / min. ,
Cutting depth: 0.22 mm,
Feed: 0.20 mm / rev. ,
Cutting time: 3 minutes,
Dry interrupted heavy cutting test of the hardened material of the bearing steel under the conditions (normal cutting and feeding are 0.2 mm and 0.12 mm / rev., Respectively),
[Cutting conditions B3]
Work material: JIS · SKD61 lengthwise equidistant four round grooved round bars,
Cutting speed: 170 m / min. ,
Cutting depth: 0.3 mm,
Feed: 0.19 mm / rev. ,
Cutting time: 4 minutes,
Dry interrupted heavy cutting test of die steel quenching material under the conditions (normal cutting and feeding are 0.15 mm and 0.10 mm / rev., Respectively),
[Cutting conditions C1]
Work material: JIS / SCr420 round bar,
Cutting speed: 205 m / min. ,
Cutting depth: 0.30 mm,
Feed: 0.20 mm / rev. ,
Cutting time: 8 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: 1905 m / min. ,
Cutting depth: 0.20 mm,
Feed: 0.23 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 0.15 mm and 0.12 mm / rev., Respectively),
[Cutting conditions C3]
Work material: JIS / SKD61 round bar,
Cutting speed: 225 m / min. ,
Cutting depth: 0.20 mm,
Feed: 0.19 mm / rev. ,
Cutting time: 8 minutes,
Dry continuous high speed heavy cutting test of die steel hardened material under the conditions of (normal cutting and feed are 0.15 mm and 0.18 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 used for such heavy cutting, the hard coating layer does not cause chipping or chipping and exhibits excellent wear resistance over a long period of time. , Al) The conventional coated inserts 1-16, 21-30 made of an N layer clearly show that chipping and chipping occur 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 (Cr, Al) N layer having the target composition and the target layer thickness shown in Table 11 is hard under the same conditions as those for forming the modified (Cr, Al) N layer in the coated inserts 1 to 16 of the present invention 1 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 (Cr, Al) N layer is formed by vapor deposition as a hard coating layer under the same conditions as the conventional (Cr, Al) 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: 110 m / min. ,
Groove depth (cut): 2.5 mm,
Table feed: 890 mm / min. ,
Die steel dry high feed groove cutting test under the conditions of (normal cutting and feed are 2.0 mm and 500 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: 105 m / min. ,
Groove depth (cut): 5.5 mm,
Table feed: 905 mm / min. ,
Stainless steel dry high feed groove cutting test under normal conditions (normal cutting and feed are 3.5 mm 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: 160 m / min. ,
Groove depth (cut): 8.5 mm,
Table feed: 850 mm / min. ,
(2) High-feed groove cutting test of alloy steel under the conditions (normal cutting and feed are 7 mm and 250 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. The vapor deposition apparatus was charged, and the target composition and the target layer thickness shown in Table 12 were the same as the conditions for forming the modified (Cr, Al) N layer in the inventive coated inserts 1 to 16 of Example 1 above. By forming the modified (Cr, Al) N layer as a hard coating layer, the surface-coated cemented carbide drills (hereinafter referred to as the present invention-coated drills) 1 to 8 as the present invention-coated tools are respectively provided. Manufactured.

  For comparison purposes, the conventional (Cr, Al) N layer is formed by vapor deposition as a hard coating layer under the same conditions as the conventional (Cr, Al) 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: 100 m / min. ,
Feed: 0.23 mm / rev. ,
Hole depth: 5 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: 60 m / min. ,
Feed: 0.11 mm / rev. ,
Hole depth: 12 mm
Stainless steel wet high feed drilling test (normal feed is 0.08 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: 75 m / min. ,
Feed: 0.14 mm / rev,
Hole depth: 18 mm
Wet high feed drilling test of high manganese steel under normal conditions (normal feed is 0.08 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 (Cr, Al) 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 (Cr, Al) 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 (Cr, Al) N layer and the conventional (Cr, Al) N layer of the present invention coated tool and the conventional coated tool were 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 (Cr, Al) N layer of the above-described coated tool of the present invention and the conventional (Cr, Al) N layer of the conventional coated tool, the surfaces of both of the above (Cr, Al) N layers were 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 {110} plane, which is the crystal plane of the crystal grain, is measured with respect to the line, and 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 for Industry, crystal grains of the crystal orientation adjacent its constituent <110> measuring the angle formed between, was created a graph showing the percentage of each and the angle, the conventional (Cr, Al) N layer, the crystal orientation of the crystal grains relative to the normal of the surface polishing plane < Even if the inclination angle distribution formed by 110> may have a peak in the inclination angle section within the range of 0 to 15 degrees with respect to the normal direction, the angle distribution of the grain boundaries is small angle boundaries (0 The distribution of the measured tilt angle of the crystal orientation <110> of the modified (Cr, Al) N layer of (a), whereas the ratio of ° <θ ≦ 15 °) is as small as about 20% (FIG. 5). As illustrated in FIG. 4, the area ratio of the crystal grains in which the crystal orientation <110> is present in the tilt angle section within the range of 0 to 15 degrees with respect to the normal direction is 50% or more of the total area of the crystal grains Furthermore, in the angular distribution of the crystal grain boundaries, the ratio of 0 ° <θ ≦ 15 ° is the total grain boundary. And the modified (Cr, Al) N layer had a crystal arrangement as described above.

FIG. 4 shows the measured tilt angle distribution of the crystal orientation <110> with respect to the normal direction of the surface polished surface of the modified (Cr, Al) 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 crystal grain boundaries of the conventional (Cr, Al) N layer of the conventional coated tool 1.
As is clear from the comparison between FIG. 4 and FIG. 5, the modified (Cr, Al) N layer shows a high orientation of (110) plane and a crystal structure with a high small-angle grain boundary ratio. It is apparent that the conventional (Cr, Al) N layer has a crystal structure that has no particular characteristics in the 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 a (110) plane highly oriented and small angle in the modified (Cr, Al) 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 according to the present invention exhibits excellent tool characteristics in continuous cutting and intermittent cutting of various steels and cast irons. Even under heavy cutting conditions where mechanical load is applied, the hard coating layer made of the modified (Cr, Al) 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 measuring range of the inclination angle with respect to the normal line of the surface polished surface where the normal line of the {110} plane which is the crystal plane of the crystal grains in various (Cr, Al) N layers constituting the hard coating layer. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing of the ion plating apparatus using the plasma used for vapor deposition formation of the modification | reformation (Cr, Al) N layer which has the favorable crystal arrangement which comprises the hard coating layer of this invention coating tool, (a) Is a front view, and (b) is a plan view. It is a schematic explanatory drawing of the arc ion plating (AIP) apparatus used for vapor deposition formation of the conventional (Cr, Al) N layer which comprises the hard coating layer of the conventional coating tool. The modified (Cr, Al) 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 <110> of the crystal grain with respect to the normal direction of the surface polished surface; It is an angle distribution graph of a grain boundary. The conventional (Cr, Al) N layer constituting the hard coating layer of the conventional coated insert 1 is measured by EBSD, and the measured inclination angle formed by the crystal orientation <110> 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: (Cr _1-X Al _X ) N
In the surface-coated cutting tool in which a composite nitride layer of Cr and Al satisfying 0.40 to 0.70 (however, atomic ratio) is formed by vapor deposition,
For the composite nitride layer of Cr and Al, when analyzing the crystal orientation of individual grains using an electron beam backscattering diffractometer,
(A) The inclination angle formed by the crystal orientation <110> of the crystal grains 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 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 <110> 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 between the crystal orientations <110> of adjacent crystal grains constituting the crystal grain boundary is measured, the proportion of small-angle grain boundaries in which the formed angle is greater than 0 degree and equal to or less than 15 degrees is the total grain boundary 50% or more of
A surface-coated cutting tool, characterized in that a hard coating layer composed of a composite nitride layer of Cr and Al satisfying the above (a) and (b) is formed by vapor deposition.

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