JP2009056560A - Surface-coated cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool the hard coating layer of which achieves excellent chipping performance and wear resistance in high-speed intermittent cutting work. <P>SOLUTION: The surface-coated cutting tool comprises: an upper layer comprising an aluminum oxide layer; and a lower layer comprising a Ti compound layer and a modified (Ti, Zr)CN layer formed by deposition. At least one Ti compound layer is composed of a modified TiCN layer, in which, on an inclination angle frequency distribution graph formed by measuring and totalling inclination angles of normal lines of ä112} faces, the highest peak exists in an inclination angle section in a range of 0-10 deg., and the total of frequencies in the section occupies a ratio of 45% or more of all the frequencies. The modified (Ti, Zr)CN layer is composed of a modified (Ti, Zr) CN layer in which, on an inclination angle frequency distribution graph formed by measuring and totalling inclination angles of normal lines for ä111} faces, the highest peak exits in the inclination angle section in the range of 0-10 deg., and the total of the frequencies in the section occupies a ratio of 45% or more of all the frequencies. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  This invention is a surface coating that exhibits excellent chipping resistance and excellent wear resistance, especially in steel and cast iron, with high heat generation and high-speed intermittent cutting that repeatedly applies a large impact load. The present invention relates to a cutting tool (hereinafter referred to as a coated tool).

On the surface of a substrate composed of tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet (hereinafter collectively referred to as a tool substrate),
(A) Ti carbide (hereinafter referred to as TiC) layer, nitride (hereinafter also referred to as TiN) layer, carbonitride (hereinafter referred to as TiCN) layer, carbon oxide (hereinafter referred to as TiC) layer formed by chemical vapor deposition , A lower layer consisting of a Ti compound layer having a total average layer thickness of 4 to 20 μm, and two or more layers of a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) an upper layer made of an aluminum oxide (Al ₂ O ₃ ) layer having an average layer thickness of 1 to 15 μm formed by chemical vapor deposition;
In a coated tool provided with the hard coating layer comprised by the above (a) and (b),
One of the Ti compound layers of the above (a) is a cubic crystal having an average layer thickness of 2 to 10 μm and existing in the measurement range of the surface polished surface using a field emission scanning electron microscope. The crystal grains having a lattice are irradiated with an electron beam, and 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 normal of the surface-polished surface. In the inclination angle number distribution graph formed by dividing the measured inclination angles within the range of 0 to 45 degrees out of the inclination angles for each pitch of 0.25 degrees and totaling the frequencies existing in each section, 0 The highest peak exists in the inclination angle section within the range of -10 degrees, and the total of the frequencies existing within the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire degrees in the inclination angle frequency distribution graph. Has a vertically grown crystal structure showing an inclination angle distribution graph iCN (hereinafter referred to as the reformed TiCN) layer,
It is known that this coated tool exhibits excellent chipping resistance in high-speed intermittent cutting of steel and cast iron.

In addition, on the surface of the tool base composed of WC-based cemented carbide and 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,
Composition formula: (Ti _1-X Zr _X ) CN (wherein X is 0.02 to 0.25 in atomic ratio),
A Ti-based carbonitride (hereinafter referred to as conventional (Ti, Zr) CN) layer having an average layer thickness of 2.5 to 15 μm, comprising a composite carbonitride layer of Ti and Zr satisfying
(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 2006-15426 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 it is used for continuous cutting or intermittent cutting under normal conditions such as steel or cast iron, but this is accompanied by high heat generation, When used in high-speed interrupted cutting conditions where repeated large mechanical impacts are applied, the hard coating layer constituting this has high temperature strength due to the lower Ti compound layer and high temperature hardness due to the upper Al ₂ O ₃ layer. Although provided, the modified TiCN layer is excellent in chipping resistance, but is not sufficient in wear resistance, and the conventional (Ti, Zr) CN layer is also insufficient in heat resistance, so that heat is generated during cutting. In Thermal plastic deformation, uneven wear tends to occur I, therefore, wear resistance at present, leads to reduced relatively short time service life.

In view of the above, the present inventors have conducted research with a particular focus on the Ti-based carbonitride layer constituting the hard coating layer in order to improve the wear resistance of the above-described conventional coated tool. As a result,
(A) The Ti-based carbonitride layer (conventional (Ti, Zr) CN) layer constituting the hard coating layer of the conventional coated tool is, for example, 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,
It is formed by vapor deposition under the conditions (called normal conditions).
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,
_{Formula: (Ti 1-X Zr X} ) CN ( provided that an atomic ratio, X: 0.02 to 0.25) Ti-based carbonitride layer which satisfies (hereinafter modified Ti-based carbonitride layer, Or a modified (Ti, Zr) CN layer) is formed, the resulting modified (Ti, Zr) CN layer has a crystal structure similar to that of the conventional (Ti, Zr) CN layer, that is, a lattice point. Has a crystal structure of NaCl type face-centered cubic crystal in which constituent atoms composed of Ti, Zr, carbon (C), and nitrogen (N) are present, respectively, but compared with the conventional (Ti, Zr) CN layer. Excellent heat resistance.

(B) For the conventional (Ti, Zr) CN layer and the modified (Ti, Zr) CN layer of (a),
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. 4, the CN layer exhibits an unbiased inclination angle number distribution graph within 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. 3, 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 exceeds 0.25 (25 atomic%), the modified (Ti, Zr) CN layer softens suddenly during high-speed interrupted cutting that generates high heat and impact loads, and undergoes thermoplastic deformation and uneven wear. Therefore, the content ratio needs to be 0.02 to 0.25 as a ratio (atomic ratio) to the total amount with Ti.

(D) In the coated tool in which the upper layer of the hard coating layer is composed of an Al ₂ O ₃ layer and the lower layer is composed of a Ti compound layer and a (Ti, Zr) CN layer, at least one of the Ti compound layers is It has an average layer thickness of 2 to 10 μm, and the distribution of the measured inclination angle on the {112} plane is within the range of 0 to 10 degrees, and the highest peak of the inclination angle section appears and is within the range of 0 to 10 degrees. And a Ti carbonitride layer (modified TiCN layer) showing an inclination angle distribution graph in which the frequency ratio is 45% or more,
Furthermore, the above (Ti, Zr) CN layer has an average layer thickness of 2 to 15 μm, and the highest peak of the tilt angle section appears in the range of the measured tilt angle of the {111} plane within the range of 0 to 10 degrees. In addition, the coated tool composed of the modified (Ti, Zr) CN layer in which the frequency ratio existing in the range of 0 to 10 degrees occupies 45% or more, the modified (Ti, Zr) CN layer is conventionally ( The Ti, Zr) CN layer has higher heat resistance, the modified TiCN layer has excellent chipping resistance, and the Al ₂ O ₃ layer, which is the upper layer of the hard coating layer, Combined with having excellent high temperature hardness, the hard coating layer exhibits excellent heat resistance, especially in high-speed cutting with high heat generation, without causing thermoplastic deformation and uneven wear. Excellent tooling characteristics over a long period due to excellent chipping resistance To become.
The research results shown in (a) to (d) 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 4 to 20 μm, each consisting of a Ti compound layer and a modified Ti carbonitride layer formed by chemical vapor deposition,
(C) The Ti compound layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer,
(D) At least one of the Ti compound layers has an average layer thickness of 2 to 10 μm, and a cubic crystal existing within the measurement range of the surface polished surface using a field emission scanning electron microscope The crystal grains having a lattice are irradiated with an electron beam, and 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 normal of the surface-polished surface. In the inclination angle number distribution graph formed by dividing the measured inclination angles within the range of 0 to 45 degrees out of the inclination angles for each pitch of 0.25 degrees and totaling the frequencies existing in each section, 0 The highest peak exists in the inclination angle section within the range of -10 degrees, and the total of the frequencies existing within the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire degrees in the inclination angle frequency distribution graph. Ti carbonitride layer showing an inclination angle distribution graph It is a reformed TiCN layer),
(E) The modified Ti-based carbonitride layer (modified (Ti, Zr) CN layer) has an average layer thickness of 2 to 15 μm, and
Composition formula: (Ti _1-X Zr _X ) CN
Is expressed by a composite carbonitride layer of Ti and Zr satisfying 0.02 ≦ X ≦ 0.25 (however, atomic ratio), and further, the modified Ti-based carbonitride layer (modified ( The Ti, Zr) CN layer) is irradiated with an electron beam to each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface using a field emission scanning electron microscope, and the surface polished surface The inclination angle formed by the normal line of the {111} plane that is the crystal plane of the crystal grain is measured with respect to the normal line, and the measurement inclination angle in the range of 0 to 45 degrees is set to 0 among the measurement inclination angles. In the inclination angle number distribution graph obtained by dividing the pitch every 25 degrees and counting the frequencies existing in each section, the highest peak exists in the inclination angle section in the range of 0 to 10 degrees, and The total frequency within the range of 0 to 10 degrees is the slope angle distribution graph. To indicate an inclination angle frequency distribution graph in a proportion of 45% or more of total power,
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) Lower Ti compound layer Ti compound layer composed of one or more of TiC layer, TiN layer, TiCN layer, TiCO layer, and TiCNO layer (in addition, about the modified TiCN layer among these) (See (b) below) itself has a predetermined high-temperature strength, and the presence of this provides the hard coating layer with a high-temperature strength, as well as a tool base and a modified TiCN layer or modified (Ti , Zr) CN adheres firmly to any of the CN layers, and contributes to improving the adhesion of the hard coating layer to the tool substrate. However, when the total average layer thickness of the lower layer is less than 4 μm, the above-described effect is sufficiently exerted. On the other hand, if the total average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation by high-speed interrupted cutting, and this causes uneven wear. 20μ m.

(B) Modified TiCN layer of the lower layer At least one of the Ti compound layers of the lower layer is composed of a modified TiCN layer. For example, the modified TiCN layer is formed by a normal chemical vapor deposition apparatus.
Reaction gas composition _{(volume%): TiCl 4: 2~10%} , CH 3 CN: 0.5~3%, N 2: 10~30%, H 2: remainder,
Reaction atmosphere temperature: 800-920 ° C.
Reaction atmosphere pressure: 6-20 kPa,
And the content ratio of the film formation start point and film formation end point of the CH ₃ CN constituting the reaction gas is adjusted in accordance with the layer thickness within the above content range, TiCN layer under the condition that the content ratio of CH ₃ CN is gradually or intermittently increased from the film formation start time when the content ratio is lowered to the film formation end time when the content ratio is relatively increased. However, if the average layer thickness is less than 2 μm, the desired excellent high-temperature strength improvement effect cannot be achieved, while if the average layer thickness exceeds 10 μm, uneven wear is not possible. Therefore, the average layer thickness is set to 2 to 10 μm.

(C) Then, the modified TiCN layer is a cubic structure that exists within the measurement range of the surface polished surface by using a field emission scanning electron microscope, as schematically shown in FIGS. 2 (a) and 2 (b). Irradiating each crystal grain having a crystal lattice with an electron beam, and measuring an inclination angle formed by a normal of a {112} plane that is a crystal plane of the crystal grain with respect to a normal of the surface-polished surface; In the inclination angle number distribution graph formed by dividing the measurement inclination angles within the range of 0 to 45 degrees among the measurement inclination angles for each pitch of 0.25 degrees and totaling the frequencies existing in each section. In addition, the highest peak exists in the inclination angle section in the range of 0 to 10 degrees, and the total of the frequencies existing in the range of 0 to 10 degrees is a ratio of 45% or more of the entire degrees in the inclination angle frequency distribution graph. The inclination angle number distribution graph which occupies is shown.

(D) Further, when the modified TiCN layer is formed, the CH ₃ CN content in the reaction gas is set to 0.5 to 3%, and the film formation is started in accordance with the layer thickness within the content range. with adjusting the time and content of CH 3 _CN deposition end point, from said deposition beginning toward the deposition end gradually increase the content of CH 3 _CN (i.e., as thin thickness formed The CH ₃ CN content at the start of film formation and at the end of film formation is set to the lower side within the range of 0.5 to 3%. When the layer thickness is intermediate, CH ₃ CN at the start of film formation and at the end of film formation The content is determined to be an intermediate content within the above range, and as the layer thickness is further increased, the CH ₃ CN content range is determined to be higher, and the content width (ie, CH ₃ at the end of film formation) CN content)-(value of CH ₃ CN content at the start of film formation)) 1 ± 0.15% is desirable. However, when the content width is less than 0.85%, the sum of the frequencies of the highest peaks existing in the range of 0 to 10 degrees becomes less than 45% of the entire frequencies in the tilt angle frequency distribution graph, and TiCN. The desired excellent high-temperature strength cannot be ensured in the layer, and when the content width exceeds 1.15%, the inclination angle section where the highest peak appears is out of the range of 0 to 10 degrees. Therefore, the desired excellent high-temperature strength cannot be ensured in the TiCN layer.

(E) Lower layer modified (Ti, Zr) CN layer The above-mentioned modified (Ti, Zr) CN layer, that is, the highest in the gradient section of the gradient angle distribution graph of the modified (Ti, Zr) CN layer The frequency ratio existing in the predetermined inclination angle section where the peak position and the highest peak exist is the atomic ratio of the Zr content ratio (X value) in the layer to the total amount with Ti as described above, and is 0.00. By setting it to 02 to 0.25, the highest peak is present in the inclination angle section within the range of 0 to 10 degrees, and the frequency ratio existing within the range of 0 to 10 degrees is expressed in the inclination angle number distribution graph. 45% or more of the entire frequency, and therefore, even if the content ratio is less than 0.02 or more than 0.25, the inclination angle section where the highest peak position appears is 0 to 10 degrees. Out of range, and further 0-10 degrees The frequency ratio existing in the range is less than 45%. Therefore, it is not only possible to suppress the decrease in high-temperature strength by uniform distribution of cooling cracks, but also ensures an excellent heat resistance improvement effect in high-speed cutting. It becomes impossible to do so, and the wear resistance is inferior due to the occurrence of thermoplastic deformation or uneven wear.
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 as described above, but the average layer thickness is less than 2 μm. Then, the desired excellent heat resistance improvement effect cannot be sufficiently provided to the hard coating layer, and on the other hand, if the average layer thickness exceeds 15 μm, chipping is likely to occur. It was determined to be 15 μm.

The Al ₂ O ₃ layer the Al ₂ O ₃ layer of (f) 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 has a high-temperature strength with excellent modified TiCN layer in the lower layer of the hard coating layer even in high-speed intermittent cutting such as steel and cast iron that is accompanied by high heat generation and repeatedly receives a large impact load. And the improved (Ti, Zr) CN layer has excellent heat resistance and high temperature strength, and is excellent by suppressing the occurrence of thermoplastic deformation and uneven wear. Since the wear resistance is maintained, excellent tool characteristics are exhibited over a long period of time.

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

As raw material powders, WC powder, TiC powder, ZrC powder, VC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, all having an average particle diameter of 0.5 to 3.5 μm, and Co powder was prepared, and these raw material powders were blended in the blending composition shown in Table 1. Further, wax was added, mixed in a ball mill in acetone for 32 hours, dried under reduced pressure, and then compacted into a predetermined shape at a pressure of 98 MPa. The green compact is press-molded into a body, vacuum-sintered at a predetermined temperature in the range of 1370 to 1470 ° C. for 1 hour in a vacuum of 5 Pa, and after sintering, the cutting edge portion has R: 0 Tool bodies A to F made of a WC-base cemented carbide having a throwaway tip shape defined in ISO · CNMG12041 were manufactured by performing a honing process of .07 mm.

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 for 32 hours with a ball mill, dry, and press-mold into 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, a Ti compound layer (including at least one modified TiCN layer) is used as a lower layer of the hard coating layer on the surfaces of the tool bases A to F and the tool bases a to f using a normal chemical vapor deposition apparatus. And a modified (Ti, Zr) CN layer formed by vapor deposition with the combinations and target layer thicknesses shown in Table 5 under the conditions shown in Table 3 and Table 4, and then under the same conditions as shown in Table 3, The present coated tools 1 to 13 were produced by forming the Al ₂ O ₃ layers as the same in the same manner as shown in Table 5 and by vapor deposition with the target layer thickness.

Further, for the purpose of comparison, as a lower layer of the hard coating layer, a Ti compound layer (including at least one modified TiCN layer) and a conventional (Ti, Zr) CN layer under the conditions shown in Tables 3 and 4, Vapor deposition is performed with the combinations and target layer thicknesses shown in Table 6, and an Al ₂ O ₃ layer as the upper layer is deposited under the conditions shown in Table 3 and with the target layer thicknesses also shown in Table 6. Comparative coated tools 1 to 13 were produced respectively.

Next, a field emission scanning electron microscope is used for the modified (Ti, Zr) CN layer, the conventional (Ti, Zr) CN layer, and the modified TiCN layer constituting the hard coating layer of the above-described coated tool of the present invention and the comparative coated tool. Was used to create a tilt angle number distribution graph.
That is, the modified (Ti, Zr) CN layer and the conventional (Ti, Zr) CN layer are set in a lens barrel of a field emission scanning electron microscope with the surface thereof being a polished surface, An electron beam having an acceleration voltage of 15 kV at an incident angle of 70 degrees is applied to the polished surface with an irradiation current of 1 nA, and each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface is irradiated, Using a scattering diffraction image apparatus, a normal of the {111} plane, which is the crystal plane of the crystal grain, is made with respect to the normal of the surface polished surface in a 30 × 50 μm region at an interval of 0.1 μm / step. Measure the tilt angle, and based on the measurement result, among the measured tilt angles, the measured tilt angles within the range of 0 to 45 degrees are divided for each pitch of 0.25 degrees and exist in each section Inclination angle number distribution by counting the frequency to be It created the rough.
In the same manner as above, the modified TiCN layer is also measured for the inclination angle formed by the normal of the {112} plane, and based on the measurement results, the measurement inclination angle is within the range of 0 to 45 degrees. An inclination angle number distribution graph was created by dividing a certain measurement inclination angle for each pitch of 0.25 degrees and totaling the frequencies existing in each division.

In the inclination angle number distribution graphs of the modified (Ti, Zr) CN layer and the conventional (Ti, Zr) CN layer obtained as a result of this, the inclination angle segment where the {111} plane shows the highest peak, and 0 to 10 degrees Tables 5 and 6 show the ratio of the number of tilt angles existing in the tilt angle section within the range to the number of tilt angles in the entire tilt angle number distribution graph.
Similarly, for the modified TiCN layer, the entire inclination angle distribution graph of the inclination angle number existing in the inclination angle section where the {112} plane has the highest peak, and the inclination angle section within the range of 0 to 10 degrees. Tables 5 and 6 show the proportion of the number of inclination angles.

In the above-mentioned various inclination angle number distribution graphs, as shown in Table 5, each of the modified (Ti, Zr) CN layers of the present coated tools 1 to 10 has a distribution of measured inclination angles on the {111} plane. An inclination angle number distribution graph in which the highest peak appears in the inclination angle section in the range of 0 to 10 degrees, and the ratio of the inclination angle numbers existing in the inclination angle section in the range of 0 to 10 degrees is 45% or more. On the other hand, as shown in Table 6, the conventional (Ti, Zr) CN layers of the comparative coated tools 1 to 10 all have a measured inclination angle distribution on the {111} plane within the range of 0 to 45 degrees. And the inclination angle number distribution graph in which the highest peak does not exist and the ratio of the inclination angle number existing in the inclination angle section within the range of 0 to 10 degrees is 30% or less.
FIG. 3 is a graph showing the distribution of inclination angle numbers of the modified (Ti, Zr) CN layer of the coated tool 2 of the present invention, and FIG. 4 is a graph showing the distribution of inclination angle numbers of the conventional (Ti, Zr) CN layer of the comparative coating tool 2. Each is shown.
As for the modified TiCN layer, any of the inventive coated tools 1 to 13 and the comparative coated tools 1 to 13 has an inclination angle division in which the distribution of measured inclination angles on the {112} plane is in the range of 0 to 10 degrees. An inclination angle number distribution graph is shown in which the highest peak appears and the ratio of the inclination angle number existing in the inclination angle section in the range of 0 to 10 degrees is 45% or more.

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). The former and the latter both have a Ti compound layer (including a modified TiCN layer), a modified (Ti, Zr) CN layer, and a conventional (Ti, Zr) CN layer that have substantially the same composition as the target composition. Further, it was confirmed that the film further comprises 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, with the various coated cermet tools described above, the present coated tool 1 to 13 and the comparative coated tools 1 to 13 in a state where all the above-mentioned coated cermet tools are 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: 410 m / min,
Cutting depth: 1.5 mm,
Feed: 0.24 mm / rev,
Cutting time: 8 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 · S40C lengthwise equal length 4 round bar with round groove,
Cutting speed: 410 m / min,
Cutting depth: 1.5 mm,
Feed: 0.35 mm / rev,
Cutting time: 10 minutes,
Wet intermittent high-speed cutting test (normal cutting speed is 300 m / min) of carbon steel under the conditions (referred to as cutting condition B),
Work material: JIS / FCD350 lengthwise equidistant round bars with 4 vertical grooves,
Cutting speed: 410 m / min,
Cutting depth: 1.5 mm,
Feed: 0.25 mm / rev,
Cutting time: 8 minutes,
We conduct a wet intermittent high-speed cutting test (normal cutting speed is 250 m / min) of ductile cast iron under the above conditions (referred to as cutting conditions C)
In any cutting test (using water-soluble cutting oil), the flank wear width of the cutting edge was measured. The measurement results are shown in Table 7.

  From the results shown in Tables 5 to 7, in the coated tools 1 to 13 of the present invention, the modified (Ti, Zr) CN layer in the lower layer of the hard coating layer has an inclination angle of {111} plane of 0. An inclination angle distribution graph showing the highest peak in an inclination angle section within a range of -10 degrees and an inclination angle number distribution graph in which the total ratio of the frequencies existing in the inclination angle section range of 0 to 10 degrees occupies 45% or more is high. Even in high-speed intermittent cutting of steel or cast iron that is accompanied by heat generation and is repeatedly subjected to a large impact load, the modified (Ti, Zr) CN layer has excellent heat resistance and high-temperature strength, thermoplastic deformation, Since the occurrence of uneven wear is prevented, the hard coating layer exhibits excellent wear resistance as well as excellent chipping resistance, whereas the (Ti, Zr) CN layer of the lower layer of the hard coating layer has , The distribution of the measured inclination angle of the {111} plane is 0 to 45 degrees In comparison coated tools 1 to 13 composed of conventional (Ti, Zr) CN layers showing an inclination angle number distribution graph that is unbiased in the surroundings and does not have the highest peak, all of them are thermoplastic in the hard coating layer by high-speed intermittent cutting. It is clear that the wear resistance of the hard coating layer is very inferior due to the occurrence of deformation or uneven wear, and the service life is reached in a relatively short time.

  As described above, the coated tool of the present invention is not only continuous cutting and intermittent cutting under normal conditions such as various steels and cast irons, but also involves particularly high heat generation and is subjected to repeated large impact loads. Even in high-speed intermittent cutting, the hard coating layer exhibits excellent chipping resistance and excellent wear resistance, and exhibits excellent cutting performance over a long period of time. It can be used satisfactorily for labor saving, energy saving, and cost reduction.

It is a schematic explanatory drawing which shows the measurement range of the inclination angle of the {111} plane of crystal grains in the modified (Ti, Zr) CN layer and the conventional (Ti, Zr) 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 the {112} plane of the crystal grain in the modified TiCN layer which comprises the lower layer of a hard coating layer. 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 2. 6 is a graph showing the inclination angle number distribution of the {111} plane of a conventional (Ti, Zr) CN layer constituting the lower layer of the hard coating layer of the comparative coating tool 2.

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 4 to 20 μm, each consisting of a Ti compound layer and a modified Ti carbonitride layer formed by chemical vapor deposition,
(C) The Ti compound layer is composed of one or more of a Ti carbide layer, a nitride layer, a carbonitride layer, a carbonate layer, and a carbonitride layer,
(D) At least one of the Ti compound layers has an average layer thickness of 2 to 10 μm, and a cubic crystal existing within the measurement range of the surface polished surface using a field emission scanning electron microscope The crystal grains having a lattice are irradiated with an electron beam, and 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 normal of the surface-polished surface. In the inclination angle number distribution graph formed by dividing the measured inclination angles within the range of 0 to 45 degrees out of the inclination angles for each pitch of 0.25 degrees and totaling the frequencies existing in each section, 0 The highest peak exists in the inclination angle section within the range of -10 degrees, and the total of the frequencies existing within the range of 0 to 10 degrees occupies a ratio of 45% or more of the entire degrees in the inclination angle frequency distribution graph. Ti carbonitride layer showing an inclination angle distribution graph Yes,
(E) The modified Ti carbonitride layer has an average layer thickness of 2 to 15 μm, and
Composition formula: (Ti _1-X Zr _X ) CN
In this case, it is composed of a composite carbonitride layer of Ti and Zr that satisfies 0.02 ≦ X ≦ 0.25 (however, the atomic ratio), and the modified Ti-based carbonitride layer further comprises field emission. Using a scanning electron microscope, irradiate each crystal grain having a cubic crystal lattice existing within the measurement range of the surface polished surface with an electron beam, and the crystal of the crystal grain with respect to the normal of the surface polished surface Measuring the inclination angle formed by the normal of the {111} plane that is a surface, and dividing the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles for each pitch of 0.25 degrees; In the slope angle distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the tilt angle section within the range of 0 to 10 degrees, and the frequencies existing in the range of 0 to 10 degrees. Is a ratio of 45% or more of the total frequency in the slope angle distribution graph To indicate an inclination angle frequency distribution graph occupied,
A surface-coated cutting tool characterized by

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