JP2009056563A - Surface-coated cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool with a hard coating layer achieving excellent wear resistance in high-speed intermittent cutting work. <P>SOLUTION: An upper layer of the hard coating layer in the surface-coated cutting tool comprises an aluminum oxide layer, and a lower layer is composed of a tight adhesion Ti compound layer, a modified (Ti<SB>1</SB>-<SB>X</SB>Zr<SB>X</SB>)CN layer (X=0.02-0.25 by atomic ratio), and a modified (Ti<SB>1</SB>-<SB>Y</SB>Cr<SB>Y</SB>)CN layer (Y=0.12-0.20 by atomic ratio). In each of the modified (Ti, Zr)CN layer and the modified (Ti, Cr)CN layer, on an inclination angle frequency distribution graph for ä111} faces, the highest peak exists in an inclination angle section within a range of 0-10 deg., and the total of frequencies existing in the inclination angle section occupies a ratio of 45% or more of all the frequencies. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  This invention is a surface-coated cutting tool that exhibits high wear resistance with a hard coating layer in high-speed intermittent cutting of steel, cast iron, and the like that involves a large amount of heat and a large impact and mechanical load on the cutting edge. (Hereinafter referred to as a coated tool).

Conventionally, on the surface of a base composed of tungsten carbide (hereinafter referred to as WC) base cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) base cermet (hereinafter collectively referred to as a tool base),
(A) Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer formed by chemical vapor deposition of the lower layers. A Ti compound layer consisting of two or more of a carbon oxide (hereinafter referred to as TiCO) layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer and having a total average layer thickness of 3 to 20 μm,
(B) an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer having an average layer thickness of 1 to 15 μm, wherein the upper layer is formed by chemical vapor deposition;
A hard coating layer (hereinafter referred to as a conventional (Ti, Cr) CN layer) in which a part of Ti in the Ti compound layer is replaced with 10 atomic% or less of Cr There is known a coated tool which is provided to further improve the wear resistance.

In addition, on the surface of the tool base made of WC-based cemented carbide or TiCN-based cermet,
(A) As the first layer, a first adhesion bonding layer composed of a TiN layer formed by chemical vapor deposition and a TiCN layer, and having an average layer thickness of 0.1 to 1 μm,
(B) The second layer is formed by chemical vapor deposition,
When represented by the composition formula: (Ti _1-β Zr _β ) CN, the atomic ratio of Ti and Zr satisfying β: 0.02 to 0.25 and an average layer thickness of 2.5 to 15 μm. A composite carbonitride (hereinafter referred to as conventional (Ti, Zr) CN) layer,
(C) As the third layer, a second adhesive bonding layer comprising an TiCO layer and a TiCNO layer and having an average layer thickness of 0.1 to 1 μm,
(D) As the fourth layer, a high-temperature hard layer comprising an Al ₂ O ₃ layer formed by chemical vapor deposition and having an average layer thickness of 1 to 15 μm,
A coated tool formed by forming a hard coating layer composed of the above (a) to (d) is known, and this coated tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is also known that
JP-A-6-31503 JP-A-10-244405 JP 2006-334710 A JP 2001-11632 A

  In recent years, the performance of cutting machines has been remarkable, while there has been a strong demand for labor saving and energy saving in cutting, as well as cost reduction, and along with this, the tendency to increase cutting speed for the purpose of improving cutting efficiency However, in the above-mentioned conventional coated tool, there is no problem when this is used for cutting under normal conditions such as steel and cast iron, but this is particularly accompanied by high heat generation and the cutting edge. When used in high-speed interrupted cutting where a large impact or mechanical load is applied to the part, the high-temperature strength of the hard coating layer is sufficient in the coated tool provided with the conventional (Ti, Cr) CN layer as the lower layer. Therefore, it cannot respond satisfactorily to mechanical impact, and is likely to generate chipping due to mechanical impact force at the time of cutting, and as a lower layer (Ti, Zr) CN layer established Since the coated tool has insufficient heat resistance, the high heat generated during cutting causes thermoplastic deformation and uneven wear, resulting in a decrease in wear resistance. Is the current situation.

In view of the above, the present inventors have proposed a conventional (Ti, Zr) CN layer and a conventional layer constituting the lower layer of the hard coating layer in order to improve the chipping resistance and wear resistance of the coated tool. As a result of conducting research by focusing on the (Ti, Cr) CN layer,
(A) In a hard coating layer of a conventional coated tool, for example, in a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, TiCl 4: 1~5%,} ZrCl 4: 0.1~1%, CH 3 CN: 0.6~5%, N 2: 25~45%, H 2: remainder,
Reaction atmosphere temperature: 750-980 ° C.
Reaction atmosphere pressure: 2.7 to 13.5 kPa,
When vapor deposition is performed under the conditions (referred to as normal conditions), a (Ti, Zr) CN (hereinafter referred to as conventional (Ti, Zr) CN) layer, which is one layer constituting the lower layer, is formed by vapor deposition. this,
Reaction gas composition: by _{volume%, TiCl 4: 10~15%,} ZrCl 4: 0.5~3.5%, CH 3 CN: 3~8%, N 2: 20~40%, HCl: 0.5 ~2%, H _2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 5 to 20 kPa,
In comparison with the above-mentioned conditions, that is, the above-mentioned normal conditions, the content ratio of the reaction gas components TiCl ₄ and CH ₃ CN is increased, and further, vapor deposition is performed under the condition of adding HCl,
When a (Ti, Zr) CN layer satisfying the composition formula: (Ti _1-X Zr _X ) CN (wherein the atomic ratio is X: 0.02 to 0.25) is formed, the resulting (Ti, Zr ) The CN layer (hereinafter referred to as a modified (Ti, Zr) CN layer) has heat resistance that is much higher than that of the conventional (Ti, Zr) CN layer.

(B) The conventional (Ti, Zr) CN layer and the modified (Ti, Zr) CN layer of (a) have the same crystal structure, that is, Ti, Zr, carbon (C) at the lattice points, And a crystal structure of a NaCl type face centered cubic crystal in which constituent atoms composed of nitrogen (N) are present,
Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams of FIGS. 1A and 1B, the electron beam is individually applied to each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface. Is measured with respect to the normal of the surface polished surface, and the tilt angle formed by the normal of the {111} plane that is the crystal plane of the crystal grain is measured. When the measured inclination angle in the range of 0.25 degrees is divided for each pitch of 0.25 degrees and the inclination angle number distribution graph is formed by counting the frequencies existing in each division, the conventional (Ti, Zr) As illustrated in FIG. 3, the CN layer exhibits an unbiased inclination angle number distribution graph in the range of the measured inclination angle of the {111} plane within the range of 0 to 45 degrees, whereas the modification ( As illustrated in FIG. 2, the Ti, Zr) CN layer has a sharp peak at a specific position in the tilt angle section. A peak appears, and in such a case, cooling cracks are uniformly dispersed in the modified (Ti, Zr) CN layer, and thereby the modified (Ti, Zr) CN layer due to an increase in the Zr content. In addition, the sharp maximum peak has a height that appears in the tilt angle section of the horizontal axis of the graph and the position of the tilt angle section in the Zr in the modified (Ti, Zr) CN layer. It changes by adjusting the content ratio.

(C) As described above, when forming the modified (Ti, Zr) CN layer, the Zr content ratio in the layer is 0.02 to 0.25 as a ratio (atomic ratio) to the total amount with Ti. By doing this, in the gradient angle distribution graph of the modified (Ti, Zr) CN layer, a sharp maximum peak appears in the range of 0 to 10 degrees of the tilt angle section, and the range of 0 to 10 degrees In the modified (Ti, Zr) CN layer, the frequency ratio existing in the tilt angle frequency distribution graph occupies a ratio of 45% or more of the entire frequency in the tilt angle frequency distribution graph. Even if the Zr content ratio is out of the above range, the sharp maximum peak in the tilt angle distribution graph is out of the range of 0 to 10 degrees of the tilt angle section, and Within the range of 0 to 10 degrees The frequency ratio is also less than 45%. In this case, not only can the heat resistance improvement effect be further improved, but also the decrease in high-temperature strength due to the increase in the Zr content ratio should be suppressed by uniform distribution of cooling cracks. What you can't do.
That is, the Zr component of the modified (Ti, Zr) CN layer has a desired heat resistance improvement effect when the ratio (atomic ratio) to the total amount with Ti is 0.02 (2 atomic%) or more. When the content ratio exceeds 0.25 (25 atomic%), the modified (Ti, Zr) CN layer softens rapidly during high-speed cutting with high heat generation, and it is likely to cause thermoplastic deformation and uneven wear. Therefore, the content ratio needs to be 0.02 to 0.25 in the ratio (atomic ratio) to the total amount with Ti.

(D) Moreover, in the hard coating layer of the conventional coated tool, the (Ti, Cr) CN layer (conventional (Ti, Cr) CN layer) constituting the lower layer is, for example, in a normal chemical vapor deposition apparatus.
Reaction gas composition: by _{volume%, TiCl 4: 3~10%,} CrF 5: 0.1~0.4%, CH 3 CN: 0.5~3%, N 2: 20~40%, H 2: remaining,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 6-20 kPa,
It is formed by vapor deposition under the conditions (called normal conditions)
this,
Reaction gas composition: by _{volume%, TiCl 4: 1~5%,} CrCl 3: 0.7~2.5%, CH 3 CN: 3~6%, N 2: 20~40%, HCl: 0.5 ~2%, H _2: remainder,
Reaction atmosphere temperature: 800 to 900 ° C.
Reaction atmosphere pressure: 5 to 20 kPa,
In other words, compared with the above normal conditions, a small amount of CrCl ₃ and HCl are added instead of CrF ₅ which is one of the reaction gas components, and the content ratio of TiCl ₄ is reduced, and the content of CH ₃ CN is reduced. When vapor deposition is performed under the condition where the ratio is increased,
(Ti, Cr) CN layer (hereinafter, modified (Ti, Cr) CN satisfying the composition formula: (Ti _1-Y Cr _Y ) CN (wherein Y: 0.12 to 0.20 in atomic ratio)) This modified (Ti, Cr) CN layer has better heat resistance and high temperature strength than the conventional (Ti, Cr) CN layer.

(E) The conventional (Ti, Cr) CN layer and the modified (Ti, Cr) CN layer described above have the same crystal structure, that is, lattice points consisting of Ti, Cr, carbon (C), and nitrogen (N). Although it has a NaCl type face centered cubic crystal structure in which each constituent atom exists, each layer is schematically illustrated in FIGS. 1A and 1B as in the case of the (Ti, Zr) CN layer. As illustrated,
Using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal grain is normal to the surface polished surface. The tilt angle formed by the normal line of the {111} plane, which is the crystal plane, is measured, and, among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are classified for each pitch of 0.25 degrees. In addition, when an inclination angle number distribution graph is created by counting the frequencies existing in each section, the conventional (Ti, Cr) CN layer has a measured inclination of the {111} plane as illustrated in FIG. Whereas the angle distribution shows an unbiased inclination angle number distribution graph in the range of 0 to 45 degrees, the modified (Ti, Cr) CN layer has an inclination angle section as illustrated in FIG. A sharp peak appears at a specific position in the region, and in such a case, modification (T , Cr) CN layer uniformly disperses cooling cracks, which can suppress a decrease in high-temperature strength of the modified (Ti, Cr) CN layer due to an increase in the Cr content. The sharpest peak is that the height appearing in the tilt angle section on the horizontal axis of the graph and the tilt angle section position change by adjusting the Cr content ratio in the modified (Ti, Cr) CN layer.

(F) As described above, when the modified (Ti, Cr) CN layer is formed, the Cr content in the layer is 0.12 to 0.20 in terms of the ratio (atomic ratio) to the total amount with Ti. In the gradient angle distribution graph of the modified (Ti, Cr) CN layer, a sharp maximum peak appears in the range of 0 to 10 degrees of the tilt angle section, and the range of 0 to 10 degrees In the modified (Ti, Cr) CN layer, the frequency ratio existing in the tilt angle frequency distribution graph occupies a ratio of 45% or more of the entire frequency in the tilt angle frequency distribution graph. Even if the Cr content ratio is out of the lower range or higher range, the sharp peak in the tilt angle number distribution graph is out of the range of 0 to 10 degrees of the tilt angle section, and Within the range of 0 to 10 degrees The frequency ratio is also less than 45%. In this case, not only the heat resistance improvement effect cannot be expected, but also the decrease in high-temperature strength due to the increase in the Cr content ratio cannot be suppressed by uniform dispersion of cooling cracks. thing.
That is, the Cr component of the modified (Ti, Cr) CN layer has a desired heat resistance improvement effect at a ratio (atomic ratio) of 0.12 (12 atomic%) or more in the total amount with Ti, When the content ratio exceeds 0.20 (20 atomic%), the modified (Ti, Cr) CN layer is softened rapidly in high-speed intermittent cutting with high heat generation, and chipping is likely to occur. The content ratio needs to be 0.12 to 0.20 as a ratio (atomic ratio) to the total amount with Ti.

(G) The upper layer of the hard coating layer is an Al ₂ O ₃ layer, the lower layer is an adhesive Ti compound layer, a modified (Ti, Zr) CN layer, and a modified (Ti, Cr) CN layer, The modified (Ti, Zr) CN layer has an average layer thickness of 2.5 to 15 μm, and the distribution of the measured inclination angle of the {111} plane is within the range of 0 to 10 degrees, and the highest peak of the inclination angle section is Appearing and the frequency ratio existing in the range of 0 to 10 degrees occupies 45% or more, and the modified (Ti, Cr) CN layer has an average layer thickness of 2.5 to 15 μm, The coated tool in which the distribution of the measured inclination angle of the {111} plane has the highest peak of the inclination angle section in the range of 0 to 10 degrees, and the frequency ratio existing in the range of 0 to 10 degrees occupies 45% or more. In particular, the modified (Ti, Zr) CN layer has a much higher heat resistance than the conventional (Ti, Zr) CN layer, Quality (Ti, Cr) CN layer is conventional (Ti, Cr) in comparison with the CN has excellent high-temperature strength and heat resistance, further, the high-temperature hardness of the Al ₂ O ₃ layer is the top layer is excellent Combined with this, the hard coating layer generates chipping even in high-speed intermittent cutting such as steel and cast iron, which is accompanied by particularly high heat generation and a large impact and mechanical load on the cutting edge. It exhibits excellent heat resistance while suppressing, and does not cause thermoplastic deformation or uneven wear, and therefore exhibits excellent wear resistance over a long period of time.
The research results shown in (a) to (g) above were obtained.

This invention was made based on the above research results,
In a surface-coated cutting tool in which a hard coating layer composed of an upper layer and a lower layer is vapor-deposited on the surface of a tool base composed of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
(A) The upper layer is made of an aluminum oxide layer having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition,
(B) The lower layer has a total average layer thickness of 3 to 20 μm, all of which are an adhesive Ti compound layer formed by chemical vapor deposition, a composite carbonitride layer of Ti and Zr, and Ti and Cr. A composite carbonitride layer,
(C) The adhesive Ti compound layer is composed of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride oxide layer having a total average layer thickness of 0.1 to 5 μm. It consists of one or more layers,
(D) The Ti and Zr composite carbonitride layer has an average layer thickness of 2.5 to 15 μm, and
Composition formula: (Ti _1-X Zr _X ) CN
Is a composite carbonitride layer of Ti and Zr that satisfies 0.02 ≦ X ≦ 0.25 (however, atomic ratio),
Further, by using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the normal line of the surface polishing surface is The inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set every pitch of 0.25 degrees. In the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak is present in the inclination angle section in the range of 0 to 10 degrees, and within the range of 0 to 10 degrees. Is formed of a composite carbonitride layer of Ti and Zr showing a tilt angle number distribution graph that occupies a ratio of 45% or more of the entire frequency in the tilt angle frequency distribution graph,
(E) The Ti and Cr composite carbonitride layer has an average layer thickness of 2.5 to 15 μm, and
Composition formula: (Ti _1-Y Cr _Y ) CN
Is a composite carbonitride layer of Ti and Cr satisfying Y: 0.12 to 0.20 in atomic ratio,
Further, by using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the normal line of the surface polishing surface is The inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set every pitch of 0.25 degrees. In the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak is present in the inclination angle section in the range of 0 to 10 degrees, and within the range of 0 to 10 degrees. Is formed of a composite carbonitride layer of Ti and Cr showing an inclination angle distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle distribution graph.
A surface-coated cutting tool (coated tool). "
It has the characteristics.

  Next, the reason why the constituent layers of the hard coating layer of the coated tool of the present invention are numerically limited as described above will be described below.

(A) Adhesive Ti compound layer of lower layer Adhesive Ti compound layer consists of an Al ₂ O ₃ layer, a modified (Ti, Zr) CN layer, and a modified (Ti, Cr) CN layer that are the tool base and the upper layer. It adheres firmly to any of the above, and thus has the effect of contributing to improved adhesion of the hard coating layer to the tool substrate, but if the total average layer thickness is less than 0.1 μm, the desired excellent adhesion should be ensured. On the other hand, since the total average layer thickness up to 5 μm is sufficient for the adhesion, the total average layer thickness was determined to be 0.1 to 5 μm.

(B) Modified (Ti, Zr) CN layer of lower layer The highest peak position in the inclination angle section of the inclination angle number distribution graph of the modified (Ti, Zr) CN layer and a predetermined inclination where the highest peak exists The frequency ratio existing in the corner section is 0 to 10 by adjusting the Zr content ratio (X value) in the layer to the total amount with Ti as 0.02 to 0.25 as described above. The highest peak exists in the inclination angle section within the range of degrees, and the frequency ratio existing in the range of 0 to 10 degrees can be 45% or more of the entire degrees in the inclination angle distribution graph. Therefore, even if the content ratio is less than 0.02 or exceeds 0.25, the inclination angle section at which the highest peak position appears is out of the range of 0 to 10 degrees, and further the range of 0 to 10 degrees. The frequency ratio that exists in is not 45% As a result, not only can the decrease in high-temperature strength be suppressed by the uniform distribution of cooling cracks, but it will also be impossible to ensure an excellent heat resistance improvement effect in high-speed interrupted cutting. Due to the occurrence of uneven wear or uneven wear, the wear resistance is inferior.
In addition, the C component in the modified (Ti, Zr) CN layer improves the hardness of the layer, while the N component has the effect of improving the high-temperature strength. Therefore, if the content ratio of the N component in the layer is less than 0.35 in terms of the atomic ratio to the total amount with the C component, the desired strength can be secured. On the other hand, if the content ratio similarly exceeds 0.55, the content ratio of the C component is relatively decreased, and the desired high hardness cannot be obtained. Therefore, the N component occupies the total amount with the C component. The content ratio of is desirably 0.35 to 0.55 in atomic ratio.
As described above, the modified (Ti, Zr) CN layer has higher heat resistance than the conventional (Ti, Zr) CN layer, but the average layer thickness is less than 2.5 μm. However, the desired excellent heat resistance improvement effect cannot be sufficiently provided to the hard coating layer. On the other hand, if the average layer thickness exceeds 15 μm, chipping tends to occur. It was determined to be 5 to 15 μm.

(C) Lower layer modified (Ti, Cr) CN layer As for the modified (Ti, Cr) CN layer, as described above, the Cr content ratio (Y value) in the layer accounts for the total amount of Ti By setting the ratio to 0.12 to 0.20, in the inclination angle number distribution graph in which the inclination angles formed by the normal lines of the {111} plane are tabulated, the inclination angle sections within the range of 0 to 10 degrees are included. While the highest peak is present, the total of the frequencies within the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire frequencies in the inclination angle frequency distribution graph, and has excellent heat resistance and high temperature strength. The modified (Ti, Cr) CN layer can be formed by vapor deposition. However, if the average layer thickness is less than 2.5 μm, the desired excellent heat resistance and high temperature strength cannot be improved. If the average layer thickness exceeds 15 μm, it will cause uneven wear. Easily thermal plastic deformation is generated, since it becomes worn accelerates, determined the average layer thickness and 2.5～15Myuemu.

(D) the Al ₂ O ₃ layer the Al ₂ O ₃ layer of the upper layer has excellent high-temperature hardness, contributes to improvement in wear resistance of the hard coating layer, the average layer thickness is less than 1 [mu] m, hard Since the coating layer cannot exhibit sufficient wear resistance, on the other hand, if the average layer thickness exceeds 15 μm, chipping tends to occur. Therefore, the average layer thickness is set to 1 to 15 μm. It was.

  In addition, for the purpose of identification before and after the use of the cutting tool, the TiN layer having a golden color tone may be vapor-deposited as necessary, but the average layer thickness in this case is 0.1 to 1 μm may be sufficient, and if the thickness is less than 0.1 μm, a sufficient discrimination effect cannot be obtained, while the discrimination effect by the TiN layer is sufficient for an average layer thickness of up to 1 μm.

  The coated tool of the present invention is a modification of the lower layer of the hard coating layer even in high-speed intermittent cutting such as steel or cast iron that involves high heat generation and a large impact / mechanical load on the cutting edge ( The Ti, Cr) CN layer and the modified (Ti, Zr) CN layer have excellent heat resistance and high-temperature strength, and the hard coating layer can also generate chipping by suppressing the occurrence of thermoplastic deformation and uneven wear. The wear resistance is further improved.

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

WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 0.5 to 3 μm as raw material powder These raw material powders are blended into the blending composition shown in Table 1, further added with wax, ball milled in acetone for 24 hours, dried under reduced pressure, and then formed into a compact with a predetermined shape at a pressure of 98 MPa. The green compact was press-molded and vacuum-sintered in a vacuum of 5 Pa at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour. After sintering, the cutting edge portion had R: 0.05 mm. The tool bases A to F made of a WC-base cemented carbide having a throwaway tip shape specified in ISO · CNMG12041 were manufactured by performing the honing process.

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, blend these raw material powders into the composition shown in Table 2, wet mix with a ball mill for 24 hours, dry, and press-mold into a green compact at 98 MPa pressure Then, this green compact is sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.09 mm. Tool bases a to f made of TiCN-based cermet having a chip shape conforming to ISO standards / CNMG 120212 were formed.

Next, on the surfaces of the tool bases A to F and the tool bases a to f, an ordinary chemical vapor deposition apparatus is used, and as a lower layer of the hard coating layer, an adhesive Ti compound layer, modified (Ti, Cr) CN. A lower layer composed of a layer and a modified (Ti, Zr) CN layer is formed by vapor deposition under the conditions shown in Tables 3 and 4 with the combinations and target layer thicknesses shown in Table 5, and then in the same conditions as shown in Table 3. Then, the inventive coated tools 1 to 13 were manufactured by vapor-depositing Al ₂ O ₃ layers as upper layers in the same combinations as shown in Table 5 and with a target layer thickness.

For comparison purposes, as the lower layer of the hard coating layer, an adhesive Ti compound layer, a conventional (Ti, Cr) CN layer, and a conventional (Ti, Zr) CN layer are displayed under the conditions shown in Tables 3 and 4. 6 by vapor deposition with the combination and target layer thickness shown in FIG. 6, and further by depositing the Al ₂ O ₃ layer as the upper layer under the conditions shown in Table 3 and with the target layer thickness also shown in Table 6. Comparative coated tools 1 to 13 were produced, respectively.

Next, with respect to the modified (Ti, Zr) CN layer and the conventional (Ti, Zr) CN layer constituting the hard coating layer of the above-described coated tool of the present invention and the comparative coated tool, a gradient is obtained using a field emission scanning electron microscope. Each angle distribution graph was created.
That is, the inclination angle number distribution graph shows the inside of the column of the field emission scanning electron microscope in a state where the surfaces of the modified (Ti, Zr) CN layer and the conventional (Ti, Zr) CN layer are polished surfaces. Irradiating the polished surface with an electron beam with an acceleration voltage of 15 kV at an incident angle of 70 degrees with an irradiation current of 1 nA on each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface Then, using an electron backscatter diffraction image apparatus, a {111} plane which is a crystal plane of the crystal grain with respect to a normal line of the surface-polished surface in a 30 × 50 μm region at an interval of 0.1 μm / step The inclination angle formed by the normal line is measured, and based on the measurement result, among the measurement inclination angles, the measurement inclination angle within the range of 0 to 45 degrees is divided for each pitch of 0.25 degrees, Created by counting the frequencies existing in each category It was.

    In the inclination angle number distribution graphs of the various modified (Ti, Zr) CN layers and conventional (Ti, Zr) CN layers obtained as a result, the inclination angle division in which the {111} plane shows the highest peak, and 0-10 Tables 5 and 6 show the ratio of the number of tilt angles existing in the tilt angle section within the degree range to the number of tilt angles in the entire tilt angle distribution graph.

  The modified (Ti, Cr) CN layer and the conventional (Ti, Cr) CN layer constituting the hard coating layer of the coated tool of the present invention and the comparative coated tool are also the same as in the case of the (Ti, Zr) CN layer. In addition, using a field emission scanning electron microscope, the measurement inclination angle within the range of 0 to 45 degrees is divided into pitches of 0.25 degrees, and the inclinations are counted by counting the frequencies existing in each division. An angle number distribution graph was created.

  In the inclination angle number distribution graphs of the various modified (Ti, Cr) CN layers and conventional (Ti, Cr) CN layers obtained as a result, the inclination angle division in which the {111} plane shows the highest peak, and 0 to 10 Tables 5 and 6 show the ratio of the number of tilt angles existing in the tilt angle section within the degree range to the number of tilt angles in the entire tilt angle distribution graph.

In the above-described various inclination angle number distribution graphs, as shown in Table 5, the modified (Ti, Zr) CN layer and the modified (Ti, Cr) CN layer of the present coated tools 1 to 13 are all { 111}, the highest peak appears in the tilt angle section in the range of 0 to 10 degrees of the measured tilt angle distribution, and the ratio of the tilt angle number existing in the tilt angle section in the range of 0 to 10 degrees is 45. %, The conventional (Ti, Zr) CN layer and the conventional (Ti, Cr) CN layer of the comparative coating tools 1 to 13 are as shown in Table 6. The distribution of the measured inclination angle of the {111} plane is unbiased within the range of 0 to 45 degrees, the highest peak does not exist, and the number of inclination angles existing in the inclination angle section within the range of 0 to 10 degrees. An inclination angle number distribution graph having a ratio of 30% or less was shown.
FIG. 2 is a graph showing the distribution of the tilt angle number of the modified (Ti, Zr) CN layer of the coated tool 3 of the present invention, and FIG. 3 is the distribution of the tilt angle number of the conventional (Ti, Zr) CN layer of the comparative coated tool 3. 4 is a graph showing the distribution of the tilt angle number of the modified (Ti, Cr) CN layer of the coated tool 3 of the present invention, and FIG. 5 is the graph showing the distribution of the tilt angle number of the conventional (Ti, Cr) CN layer of the comparative coated tool 3. Each graph is shown.

Further, for the above-described coated tools 1 to 13 and comparative coated tools 1 to 13 described above, the constituent layers of the hard coating layer were observed using an electron beam microanalyzer (EPMA) and an Auger spectroscopic analyzer (longitudinal section of the layer). Observed), an adhesive Ti compound layer, a modified (Ti, Zr) CN layer, a modified (Ti, Cr) CN layer, a conventional (Ti, It was confirmed to be composed of a Zr) CN layer, a conventional (Ti, Cr) CN layer, and an Al ₂ O ₃ layer. Moreover, when the thickness of the constituent layer of the hard coating layer of these coated tools was measured using a scanning electron microscope (similarly longitudinal section measurement), the average layer thickness (5 The average value of point measurement) was shown.

Next, in the state where each of the above various coated tools is screwed to the tip of the tool steel tool with a fixing jig, the present coated tools 1 to 13 and the comparative coated tools 1 to 13 are as follows:
Work material: JIS · SCr420H lengthwise equidistant 4 round bars with vertical grooves,
Cutting speed: 440 m / min,
Cutting depth: 1.3 mm,
Feed: 0.28 mm / rev,
Cutting time: 10 minutes,
Wet intermittent high-speed cutting test (normal cutting speed is 250 m / min) of alloy steel under the above conditions (referred to as cutting condition A),
Work material: JIS · SUM11 lengthwise equidistant 4 round grooved round bars,
Cutting speed: 435 m / min,
Cutting depth: 1.5 mm,
Feed: 0.29 mm / rev,
Cutting time: 12 minutes,
Wet intermittent high-speed cutting test of free-cutting steel under the conditions (cutting condition B) (normal cutting speed is 200 m / min),
Work material: JIS / FC150 lengthwise equidistantly 4 round bars with flutes,
Cutting speed: 470 m / min,
Cutting depth: 2.0 mm,
Feed: 0.30 mm / rev,
Cutting time: 10 minutes,
Wet intermittent high-speed cutting test (normal cutting speed is 300 m / min) of gray cast iron under the conditions (cutting condition C)
The flank wear width of the cutting edge was measured in any cutting test (using water-soluble cutting oil). The measurement results are shown in Table 7.

  From the results shown in Tables 5 to 7, all of the coated tools 1 to 13 of the present invention have the modified (Ti, Zr) CN layer and the modified (Ti, Cr) CN layer in the lower layer of the hard coating layer. , The inclination angle of the {111} plane has the highest peak in the inclination angle section within the range of 0 to 10 degrees, and the total ratio of the frequencies existing in the inclination angle section range of 0 to 10 degrees is 45% or more. This graph shows the distribution of the number of inclined angles, and the modification (Ti, Zr) even in high-speed intermittent cutting of various steels and cast irons that generate high heat and have a large impact / mechanical load on the cutting edge. CN layer and modified (Ti, Cr) CN layer has excellent heat resistance and high temperature strength, and prevents the occurrence of thermoplastic deformation, partial wear, and chipping, so that the hard coating layer generates chipping. Hard coating while showing excellent wear resistance The (Ti, Zr) CN layer and (Ti, Cr) CN layer in the lower layer of the above are non-biased within the range of the measured inclination angle of the {111} plane within the range of 0 to 45 degrees, and the highest peak exists. In the comparative coating tools 1 to 13 composed of the conventional (Ti, Zr) CN layer and the conventional (Ti, Cr) CN layer showing the inclination angle number distribution graph that does not occur, chipping occurs in the hard coating layer, or the hard It is apparent that the wear resistance of the coating layer is inferior and, as a result, the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention is not only continuous and intermittent cutting under normal conditions such as various steels and cast irons, but also generates a large amount of heat and has a large impact and mechanical load on the cutting edge. In high-speed interrupted machining, the hard coating layer exhibits excellent wear resistance and exhibits excellent cutting performance over a long period of time. It is possible to cope with the reduction of cost and cost.

The modified (Ti, Zr) CN layer, the modified (Ti, Cr) CN layer, the conventional (Ti, Zr) CN layer, and the conventional (Ti, Cr) CN layer constituting the lower layer of the hard coating layer It is a schematic explanatory drawing which shows the measurement range of the inclination angle of a {111} surface. It is an inclination angle number distribution graph of the {111} plane of the modified (Ti, Zr) CN layer constituting the lower layer of the hard coating layer of the present coated tool 3. 4 is a graph showing the distribution of inclination angle numbers of {111} planes of a conventional (Ti, Zr) CN layer constituting the lower layer of the hard coating layer of the comparative coating tool 3. It is an inclination angle number distribution graph of the {111} plane of the modified (Ti, Cr) CN layer constituting the lower layer of the hard coating layer of the present coated tool 3. 4 is a graph showing the distribution of the number of inclination angles of the {111} plane of a conventional (Ti, Cr) CN layer constituting the lower layer of the hard coating layer of the comparative coating tool 3.

Claims (1)

In a surface-coated cutting tool in which a hard coating layer composed of an upper layer and a lower layer is vapor-deposited on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
(A) The upper layer is made of an aluminum oxide layer having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition,
(B) The lower layer has a total average layer thickness of 3 to 20 μm, all of which are an adhesive Ti compound layer formed by chemical vapor deposition, a composite carbonitride layer of Ti and Zr, and Ti and Cr. A composite carbonitride layer,
(C) The adhesive Ti compound layer is composed of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride oxide layer having a total average layer thickness of 0.1 to 5 μm. It consists of one or more layers,
(D) The Ti and Zr composite carbonitride layer has an average layer thickness of 2.5 to 15 μm, and
Composition formula: (Ti _1-X Zr _X ) CN
Is a composite carbonitride layer of Ti and Zr that satisfies 0.02 ≦ X ≦ 0.25 (however, atomic ratio),
Further, by using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the normal line of the surface polishing surface is The inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set every pitch of 0.25 degrees. In the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak is present in the inclination angle section in the range of 0 to 10 degrees, and within the range of 0 to 10 degrees. Is formed of a composite carbonitride layer of Ti and Zr showing a tilt angle number distribution graph that occupies a ratio of 45% or more of the entire frequency in the tilt angle frequency distribution graph,
(E) The Ti and Cr composite carbonitride layer has an average layer thickness of 2.5 to 15 μm, and
Composition formula: (Ti _1-Y Cr _Y ) CN
Is a composite carbonitride layer of Ti and Cr satisfying Y: 0.12 to 0.20 in atomic ratio,
Further, by using a field emission scanning electron microscope, each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polishing surface is irradiated with an electron beam, and the normal line of the surface polishing surface is The inclination angle formed by the normal line of the {111} plane, which is the crystal plane of the crystal grain, is measured, and the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles is set every pitch of 0.25 degrees. In the inclination angle number distribution graph obtained by summing up the frequencies existing in each section, the highest peak is present in the inclination angle section in the range of 0 to 10 degrees, and within the range of 0 to 10 degrees. Is formed of a composite carbonitride layer of Ti and Cr showing an inclination angle distribution graph that occupies a ratio of 45% or more of the entire frequency in the inclination angle distribution graph.
A surface-coated cutting tool characterized by that.

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