JP2007160464A - Surface coated cermet cutting tool having hard coating layer exhibiting excellent chipping resistance in high-speed intermittent cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cermet cutting tool having a hard coating layer exhibiting excellent chipping resistance in high speed intermittent cutting. <P>SOLUTION: This coated cermet tool is constituted by forming the hard coating layer having a lower part layer of a Ti compound layer and an upper part layer of the αtype Al<SB>2</SB>O<SB>3</SB>layer by deposition on a surface of a tool base body. The αtype Al<SB>2</SB>O<SB>3</SB>layer is constituted of: an upper rank layer showing an inclination angle frequency distribution graph in which a highest peak exists in an inclination angle section in the range of 30 to 45° and the total of frequencies existing in the range of 30 to 45° occupies the rate of ≥50% of the whole frequency when preparing the inclination angle frequency distribution graph by using a field emission type scanning electron microscope and measuring an inclination angle made by a normal line of a surface (0001) which is a crystal surface of crystal grains; and a lower rank layer showing an inclination angle frequency distribution graph in which a highest peak exists in an inclination angle section in the range of 75 to 90° and the total of frequencies existing in the range of 75 to 90° occupies the rate ≥50% of the whole frequency. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

In the present invention, particularly in a state in which an aluminum oxide layer (hereinafter referred to as an Al ₂ O ₃ layer) that is a constituent layer of a hard coating layer is thickened, various kinds of cutting work such as steel and cast iron can be performed at high speed. Even when performed under intermittent cutting conditions with mechanical impact, the hard coating layer exhibits excellent chipping resistance, and therefore has excellent wear resistance over a long period of time without occurrence of chipping (small chipping). The present invention relates to a surface-coated cermet cutting tool to be exhibited (hereinafter referred to as a coated cermet tool).

Conventionally, generally on the surface of a substrate (hereinafter collectively referred to as a tool substrate) composed of a tungsten carbide (hereinafter referred to as WC) -based cemented carbide or titanium carbonitride (hereinafter referred to as TiCN) -based cermet. ,
(A) The lower layer is a Ti carbide (hereinafter referred to as TiC) layer, a nitride (hereinafter also referred to as TiN) layer, a carbonitride (hereinafter referred to as TiCN) layer, a carbon oxide (hereinafter referred to as TiCO). A Ti compound layer having a total average layer thickness of 3 to 20 μm, including one or two or more of a layer and a carbonitride oxide (hereinafter referred to as TiCNO) layer,
(B) The upper layer usually has an average layer thickness of 1 to 12 μm, an average layer thickness of 20 μm or less including the thickened state, and an α-type crystal structure in the state of chemical vapor deposition. Layer (hereinafter referred to as a deposited α-type Al ₂ O ₃ layer),
There is known a coated cermet tool formed by vapor-depositing a hard coating layer composed of (a) and (b) above, and this coated cermet tool can be used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is well known to be used.

In general, the Ti compound layer and vapor-deposited α-type Al ₂ O ₃ layer constituting the hard coating layer of the above coated cermet tool have a granular crystal structure, and the TiCN layer constituting the Ti compound layer is For the purpose of improving its own strength, it is formed by chemical vapor deposition in a medium temperature range of 700 to 950 ° C using a mixed gas containing organic carbonitrides as a reaction gas in a normal chemical vapor deposition apparatus, and vertically grown. It is also known to have a crystal structure.
Japanese Unexamined Patent Publication No. 6-31503 Japanese Patent Laid-Open No. 6-8010

In recent years, the performance of cutting machines has been remarkably improved. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting work. Accordingly, the vapor deposited α-type Al ₂ O ₃ layer has a maximum thickness of 20 μm. Although thicker films are required and the cutting process tends to be faster, the above-mentioned conventional coated cermet tools were used for continuous cutting and intermittent cutting under normal conditions such as steel and cast iron. In this case, there is no problem, but especially when this is used under high-speed interrupted cutting conditions, the high-temperature hardness and high-temperature strength of the vapor-deposited α-type Al ₂ O ₃ layer constituting the hard coating layer is insufficient. In addition, wear progresses rapidly and chipping is likely to occur, and chipping is more likely to occur by increasing the thickness of the deposited α-type Al ₂ O ₃ layer. Is the current situation

In view of the above, the present inventors paid attention to a coated cermet tool in which the vapor-deposited α-type Al ₂ O ₃ layer constitutes the upper layer of the hard coating layer, and particularly the vapor-deposited α-type Al ₂ O 3. As a result of research to improve chipping resistance of _three layers,
(A) The vapor-deposited α-type Al ₂ O ₃ layer as a hard coating layer of the above-described conventional coated cermet tool is generally used in a normal chemical vapor deposition apparatus.
Reaction gas composition: by _{volume%, AlCl 3: 1~5%,} CO 2: 3~7%, HCl: 0.3~3%, H 2 S: 0.02~0.4%, H 2: remainder ,
Reaction atmosphere temperature: 950-1100 ° C.
Reaction atmosphere pressure: 6-13 kPa,
1 (a), (b) and FIG. 1 using the field emission scanning electron microscope for the deposited α-type Al ₂ O ₃ layer formed under the normal conditions. 2 (a) and (b), as schematically shown in the drawing, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the polished surface parallel to the tool substrate surface is irradiated with an electron beam, The inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal line of the polished surface. Of the measured inclination angles, 0 to 45 degrees and 45 to 90 degrees, respectively. When the measured inclination angle within the range is divided for each pitch of 0.25 degrees, and an inclination angle number distribution graph is created by summing up the frequencies existing in each division, FIG. 45 degrees) and FIG. 6 (measurement tilt angle: 45 to 90 degrees), The distribution of the measured inclination angle of the (0001) plane should be an unbiased inclination angle number distribution graph regardless of the range of 0 to 45 degrees and 45 to 90 degrees.

(B) On the other hand, the vapor-deposited α-type Al ₂ O ₃ layer was similarly used with a normal chemical vapor deposition device,
Reaction gas composition: by _{volume%, AlCl 3: 1~5%,} CO 2: 3~7%, HCl: 0.3~3%, H 2 S: 0.02~0.4%, H 2: remainder ,
Reaction atmosphere temperature: 750 to 900 ° C.
Reaction atmosphere pressure: 20-30 kPa,
2 formed under the relatively low temperature and high pressure conditions (reaction gas composition is the same as the above normal conditions), the deposited α-type Al ₂ O ₃ layer formed as a result is also shown in FIG. As shown in (a) and (b), each crystal grain having a hexagonal crystal lattice that is also present in the measurement range of the polished surface parallel to the tool base surface is irradiated with an electron beam, The inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal line, and the measurement inclination angle within the range of 45 to 90 degrees out of the measurement inclination angles is set to 0. .When divided into 25-degree pitches and represented by an inclination angle number distribution graph in which the frequencies existing in each area are aggregated, as shown in FIG. The highest peak appears and the test results show that When the reaction atmosphere temperature and pressure are changed within the range of 750 to 900 ° C. and 20 to 30 kPa as described above, the position at which the sharpest peak appears changes within the range of 75 to 90 degrees of the inclination angle section. The sum of the frequencies existing in the range of 75 to 90 degrees occupies a ratio of 50% or more of the entire frequencies in the inclination angle distribution graph, and 75 to 90 degrees in the inclination angle distribution graph as a result. The vapor-deposited α-type Al ₂ O ₃ layer in which the highest peak of the tilt angle section appears in the range of the above has a relatively high high-temperature hardness as compared with the vapor-deposited α-type Al ₂ O ₃ layer formed under the above normal conditions thing.

(C) Furthermore, the vapor-deposited α-type Al ₂ O ₃ layer was similarly used with a normal chemical vapor deposition apparatus,
Reaction gas composition:% by volume, AlCl ₃ : 3 to 10%, CO ₂ : 0.5 to 3%, HCl: 0.3 to 3%, SF ₆ : 0.01 to 0.2%, C ₂ H _{4: 0.01~0.3%,} H _2: remainder,
Reaction atmosphere temperature: 950 to 1050 ° C.
Reaction atmosphere pressure: 20-30 kPa,
In other words, the reaction gas composition is adjusted to a reaction gas composition different from the reaction gas composition under the normal conditions described above, and the pressure of the reaction atmosphere under the normal conditions is also relatively high. When formed under the conditions, the vapor-deposited α-type Al ₂ O ₃ layer formed as a result is parallel to the tool base surface as shown in FIGS. 1 (a) and 1 (b) using the same field emission scanning electron microscope. The crystal grains having a hexagonal crystal lattice existing within the measurement range of the polished surface are irradiated with an electron beam, and the method of the (0001) plane that is the crystal plane of the crystal grains with respect to the normal line of the polished surface Measure the tilt angle formed by the line, and divide the measured tilt angles within the range of 0 to 45 degrees out of the measured tilt angles by pitch of 0.25 degrees, and count the frequencies existing in each section Is shown in FIG. 3. As can be seen, a sharp maximum peak appears at a specific position in the tilt angle section, and according to the test results, the formation conditions of the vapor-deposited α-type Al ₂ O ₃ layer, that is, the reaction gas composition and reaction atmosphere conditions described above, When at least one of the conditions is changed within the above range, the position where the sharpest peak appears changes within the range of 30 to 45 degrees of the inclination angle section, and within the range of 30 to 45 degrees. The sum of the frequencies present accounts for 50% or more of the total frequency in the tilt angle distribution graph, and the highest peak of the tilt angle section is in the range of 30 to 45 degrees in the resulting tilt angle distribution graph. The vapor-deposited α-type Al ₂ O ₃ layer in which is shown has relatively superior high-temperature strength as compared with the vapor-deposited α-type Al ₂ O ₃ layer formed under the normal conditions.

(D) Accordingly, the deposited α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer whose lower layer is made of a Ti compound layer, has an average layer thickness of _{2 to} 18 μm (however, the total average layer thickness is 20 μm or less). The upper layer has a highest peak in the inclination angle section within the range of 30 to 45 degrees in the measurement of the polished surface parallel to the tool base surface. In addition, an inclination angle number distribution graph in which the sum of the frequencies existing in the range of 30 to 45 degrees occupies a ratio of 50% or more of the entire frequencies in the inclination angle number distribution graph is shown, and the lower layer is 75 to 90 An inclination angle in which the highest peak exists in the inclination angle section within the range of degrees, and the total of the frequencies existing within the range of 75 to 90 degrees accounts for 50% or more of the entire degrees in the inclination angle frequency distribution graph Number distribution gra Coated cermet tool formed by constituted by depositing α-type the Al ₂ O ₃ layer showing a, since the said deposition α type the Al ₂ O ₃ layer is provided with a relative excellent high-temperature hardness and high-temperature strength, in particular at most layer thickness Even when cutting is performed under high-speed interrupted cutting conditions with the film thickness increased to 20 μm, the upper layer of the hard coating layer has a distribution of measured inclination angles on the (0001) plane of 0 to 45 degrees and 45 to 90 degrees. Compared to the conventional coated cermet tool composed of vapor-deposited α-type Al ₂ O ₃ layer showing an unbiased inclination angle distribution graph within the range of degrees, the hard coating layer has excellent wear resistance without chipping. To show its sexuality over a long period of time.
The research results shown in (a) to (d) above were obtained.

This invention was made based on the above research results, and on the surface of the tool base,
(A) a Ti compound layer in which the lower layer is composed of one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, and has a total average layer thickness of 3 to 20 μm,
(B) a vapor-deposited α-type Al ₂ O ₃ layer whose upper layer has an average layer thickness of 20 μm or less,
In the coated cermet tool formed by vapor-depositing the hard coating layer composed of (a) and (b) above,
The deposited α-type Al ₂ O ₃ layer has an upper and lower two-layer structure composed of a lower layer and an upper layer each having an average layer thickness of _{2 to} 18 μm (however, the total average layer thickness is 20 μm or less), and further, field emission scanning Using an electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the polished surface parallel to the tool substrate surface is irradiated with an electron beam, and the crystal is compared with the normal line of the polished surface. The inclination angle formed by the normal line of the (0001) plane, which is the crystal plane of the grain, is measured. Among the measured inclination angles, the upper layer is in the range of 0 to 45 degrees and the lower layer is in the range of 45 to 90 degrees. When the measurement inclination angle is divided into pitches of 0.25 degrees and the frequency existing in each division is represented by an inclination angle number distribution graph,
(A) The upper layer of the vapor-deposited α-type Al ₂ O ₃ layer has the highest peak in the tilt angle section within the range of 30 to 45 degrees and the total number of frequencies existing within the range of 30 to 45 degrees. Shows an inclination angle number distribution graph occupying a ratio of 50% or more of the entire frequency in the inclination angle number distribution graph,
(B) The lower layer of the deposited α-type Al ₂ O ₃ layer has the highest peak in the inclination angle section within the range of 75 to 90 degrees, and the total of the frequencies existing in the range of 75 to 90 degrees. Is an inclination angle number distribution graph occupying a ratio of 50% or more of the entire frequency in the inclination angle number distribution graph,
The hard coating layer is characterized by a coated cermet tool that exhibits excellent chipping resistance in high-speed intermittent cutting.

The reason why the numerical values of the constituent layers of the hard coating layer of the coated cermet tool of the present invention are limited as described above will be described below.
(A) Ti compound layer (lower layer)
The Ti compound layer basically exists as a lower layer of the vapor-deposited α-type Al ₂ O ₃ layer, and allows the hard coating layer to have high temperature strength by its excellent high temperature strength, It adheres firmly to any of the vapor-deposited α-type Al ₂ O ₃ layers, and thus has an effect of improving the adhesion of the hard coating layer to the tool substrate. However, if the total average layer thickness is less than 3 μm, the above-described effect is sufficient. On the other hand, if the total average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation particularly in high-speed cutting accompanied by high heat generation, which causes uneven wear. The average layer thickness was determined to be 3-20 μm.

(B) Evaporated α-type Al ₂ O ₃ layer (upper layer)
As described above, the maximum peak position and the frequency distribution ratio of the measured inclination angle in the inclination angle number distribution graph of the upper layer and lower layer of the vapor-deposited α-type Al ₂ O ₃ layer are both changed by changing the formation conditions thereof. However, according to the test results, the highest peak position appears in the inclination angle section within the range of 30 to 45 degrees in the upper layer and 75 to 90 degrees in the lower layer, and the 30 to 45 degrees and 75 to 45 degrees. In the case where the total number of frequencies existing in the range of 90 degrees indicates an inclination angle number distribution graph that accounts for 50% or more of the entire frequency in the inclination angle number distribution graph, the upper layer and the lower layer are Each having the desired excellent high-temperature strength and high-temperature hardness, and therefore when the highest peak position and the frequency distribution ratio do not satisfy the above-mentioned conditions. The desired high-temperature strength and high-temperature hardness are not provided.
Further, the deposited α-type Al ₂ O ₃ layer has excellent high temperature strength and high temperature hardness due to excellent high temperature strength of the upper layer and excellent high temperature hardness of the lower layer. If the average layer thickness of each layer is less than 2 μm, the excellent high-temperature strength and high-temperature hardness of each of the two layers cannot be secured, and the average layer thickness of the upper layer and the lower layer is 18 μm, respectively. If the average layer thickness of one layer exceeds 2 μm, which is the minimum average layer thickness, the total average layer thickness exceeds 20 μm. Thus, the average layer thickness of the upper layer and the lower layer exceeds 18 μm. Further, even if the total average layer thickness of the upper layer and the lower layer exceeds 20 μm, chipping is likely to occur. Therefore, the average layer thickness of the upper layer and the lower layer is 2 to 18 μm, respectively. Thickness It was defined as 20μm or less.

  In addition, for the purpose of identification before and after the use of the cutting tool, a TiN layer having a golden color tone may be vapor-deposited as the outermost surface layer of the hard coating layer as necessary, but the average layer thickness in this case is It may be 0.1 to 1 μm, 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 cermet tool of the present invention is a state in which the thickness of the vapor-deposited α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer is increased, and various types of steel and cast iron can be cut at high speed. Even when performed under intermittent cutting conditions with mechanical impact, the vapor-deposited α-type Al ₂ O ₃ layer has excellent high-temperature strength and high-temperature hardness, so that the hard coating layer was excellent without occurrence of chipping. It exhibits wear resistance and enables further extension of the service life.

  Next, the coated cermet 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, and Co powder each having an average particle diameter of 1 to 3 μm are prepared. The raw material powder was blended in the blending composition shown in Table 1, and then added with wax, mixed in a ball mill for 24 hours in acetone, dried under reduced pressure, and then press-molded into a green compact of a predetermined shape at a pressure of 98 MPa. The green compact is 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 is subjected to a honing process of R: 0.07 mm. Thus, tool bases A to F made of a WC-based cemented carbide having a throwaway tip shape specified in ISO · CNMG120408 were manufactured.

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 The green compact was sintered in a nitrogen atmosphere of 1.3 kPa at a temperature of 1540 ° C. for 1 hour, and after sintering, a chamfer width of 0. The tool bases a to f made of TiCN base cermet having a chip shape of ISO standard / CNMG120408 were formed by performing a honing process of mm and chamfer angle: 20 degrees.

Then, each of these tool bases A to F and tool bases a to f is charged into a normal chemical vapor deposition apparatus,
(A) First, Table 3 (l-TiCN in Table 3 indicates the conditions for forming a TiCN layer having a vertically elongated crystal structure described in JP-A-6-8010, and the other conditions are ordinary granularity. Under the conditions shown in Table 4 and 5), the Ti compound layer having the target layer thickness shown in Tables 4 and 5 is deposited as the lower layer of the hard coating layer.
(B) Next, reaction gas composition: volume%, AlCl ₃ : 2.2%, CO ₂ : 5%, HCl: 2%, H ₂ S: 0.15%, H ₂ : remaining,
Reaction atmosphere temperature: 850 ° C.
Reaction atmosphere pressure: a predetermined pressure in the range of 20-30 kPa,
The lower layer of the vapor deposition α-type Al ₂ O ₃ layer, which is the upper layer, is formed by vapor deposition at the target layer thickness shown in Tables 4 and 5 under the conditions of
(C) Furthermore, reaction gas composition: volume%, AlCl ₃ : 3.5%, CO ₂ : 1.5%, HCl: 2%, SF ₆ : 0.1%, C ₂ H ₄ : 0.05 %, H ₂ : remaining,
Reaction atmosphere temperature: 1000 ° C.
Reaction atmosphere pressure: a predetermined pressure in the range of 20-30 kPa,
The coated cermet tools 1 to 13 of the present invention were manufactured by vapor-depositing the upper layer of the vapor deposition α-type Al ₂ O ₃ layer, which is also the upper layer, with the target layer thicknesses shown in Tables 4 and 5 under the same conditions. .

For the purpose of comparison, the formation of a vapor-deposited α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer,
Reaction gas composition: volume%, AlCl ₃ : 2.2%, CO ₂ : 5%, HCl: 2%, H ₂ S: 0.15%, H ₂ : remaining,
Reaction atmosphere temperature: 1020 ° C.
Reaction atmosphere pressure: a predetermined pressure in the range of 6 to 13 kPa,
The conventional coated cermet tools 1 to 13 were produced under the same conditions as those of the present invention coated cermet tools 1 to 13 except that the target layer thicknesses shown in Tables 6 and 7 were used.

Next, for the vapor deposition α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the present invention coated cermet tool 1-13 and the conventional coated cermet tool 1-13, using a field emission scanning electron microscope, Each inclination angle number distribution graph was created.
That is, in the inclination angle number distribution graph, for the upper layer and the lower layer of the vapor deposition α-type Al ₂ O ₃ layer of the coated cermet tools 1 to 13 of the present invention, the surfaces parallel to the tool base surface are respectively polished surfaces. In this state, it is set in a lens barrel of a field emission scanning electron microscope, and an electron beam with 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 measuring range of the polished surface is measured. Irradiate each crystal grain having a hexagonal crystal lattice existing in it, and use an electron backscatter diffraction image apparatus, and a region of 30 × 50 μm at an interval of 0.1 μm / step with respect to the normal of the polished surface Then, the inclination angle formed by the normal line of the (0001) plane which is the crystal plane of the crystal grain is measured, and based on the measurement result, the upper layer of the measurement inclination angle is 0 to 45 degrees, 4 for lower layers The measurement inclination angle within the range of 5 to 90 degrees was divided for each pitch of 0.25 degrees, and the frequency existing in each section was totaled.
In addition, for the deposited α-type Al ₂ O ₃ layers of the conventional coated cermet tools 1 to 13, an arbitrary polished surface parallel to the tool base surface is observed under the same conditions, and an inclination angle number distribution graph is displayed under the same conditions. Created.

In the inclination angle frequency distribution graph of the results obtained various deposition α type the Al ₂ O ₃ layer of, as shown in Tables 4-7, the present invention coated cermet tools 1 to 13 deposited α-type the Al ₂ O ₃ layer of In the upper layer and lower layer, the distribution of the measured inclination angle of the (0001) plane is such that the highest peak appears in the inclination angle section within the range of 30 to 45 degrees in the upper layer and 75 to 90 degrees in the lower layer, respectively. In contrast to the number distribution graph, the deposited α-type Al ₂ O ₃ layer of the conventional coated cermet tools 1 to 13 has a distribution of measured inclination angles on the (0001) plane in the range of 0 to 45 degrees and 45 to 90 degrees. The inclination angle number distribution graph in which the highest peak does not exist is shown.
Tables 4 to 7 show the total inclination existing in the inclination angle sections in the range of 30 to 45 degrees and 75 to 90 degrees, respectively, in the inclination angle number distribution graphs of the various deposited α-type Al ₂ O ₃ layers. The ratio of the number of angles to the entire inclination angle number distribution graph is shown.
3 is an inclination angle number distribution graph of the upper layer of the vapor deposition α-type Al ₂ O ₃ layer of the coated cermet tool 2 of the present invention, FIG. 4 is an inclination angle number distribution graph of the lower layer, and FIGS. the inclination angle frequency distribution graph, respectively showing the inclination angle segment of 0 to 45 degrees and 45-90 degrees coated cermet tool 2 of the deposition α type the Al ₂ O ₃ layer.

  Moreover, when the thickness of the constituent layer of the hard coating layer of the present coated cermet tools 1 to 13 and the conventional coated cermet tools 1 to 13 obtained as a result was measured using a scanning electron microscope (longitudinal section measurement). , Each showed an average layer thickness (average value of 5-point measurement) substantially the same as the target layer thickness.

Next, for the various coated cermet tools of the present invention coated cermet tool 1-13 and the conventional coated cermet tool 1-13, all of them are screwed with a fixing jig to the tip of the tool steel tool,
Work material: JIS-S35C lengthwise equal length 4 round fluted round bars,
Cutting speed: 400 m / min. ,
Incision: 1.5mm,
Feed: 0.2 mm / rev. ,
Cutting time: 5 minutes
Wet intermittent high-speed cutting test (normal cutting speed is 250 m / min.) Of carbon steel under the conditions (referred to as cutting conditions A),
Work material: JIS / SNCM439 round direction bar with four equal intervals in the length direction,
Cutting speed: 360 m / min. ,
Cutting depth: 1mm,
Feed: 0.25 mm / rev. ,
Cutting time: 5 minutes
Wet intermittent high-speed cutting test (normal cutting speed is 180 m / min.) Of alloy steel under the following conditions (referred to as cutting conditions B),
Work material: JIS / FC300 lengthwise equidistant 4 bars with vertical grooves,
Cutting speed: 400 m / min. ,
Incision: 2.5mm,
Feed: 0.2 mm / rev. ,
Cutting time: 5 minutes
Wet intermittent high-speed cutting test (normal cutting speed is 300 m / min.) Of cast iron under the above conditions (referred to as cutting condition C), and the flank wear width of the cutting edge was measured in any cutting test. The measurement results are shown in Table 8.

From the results shown in Tables 4 to 8, the coated cermet tools 1 to 13 of the present invention are the upper layer and lower layer of the upper and lower two-layer structure of the vapor-deposited α-type Al ₂ O ₃ layer that is the upper layer of the hard coating layer. In each of the inclination angle number distribution graphs of the (0001) plane, the highest layer shows the highest peak in the inclination angle range within the range of 3 to 4 degrees and the lower layer within the range of 75 to 90 degrees. Since it has hardness, cutting of steel and cast iron is performed at high speed and with mechanical impact in a state where the thickness of the vapor-deposited α-type Al ₂ O ₃ layer is increased. Even when performed under intermittent cutting conditions, chipping does not occur and excellent wear resistance is exhibited, whereas the entire upper layer of the hard coating layer has a distribution of measured inclination angles of (0001) plane of 0 to 45 degrees and Tilt angle that is unbiased within the range of 45 to 90 degrees and does not have the highest peak In the conventional coated cermet tools 1 to 13, which is composed of vapor-deposited α-type the Al ₂ O ₃ layer showing the distribution graph, both in high temperature strength and high-temperature hardness insufficient cause the deposition α type the Al ₂ O ₃ layer, high speed It is clear that under intermittent cutting conditions, chipping occurs in the hard coating layer and the service life is reached in a relatively short time.

  As described above, the coated cermet tool of the present invention has excellent wear resistance without occurrence of chipping even in continuous cutting and interrupted cutting under normal conditions such as various steels and cast irons, especially in high-speed interrupted cutting. Since it exhibits excellent cutting performance over a long period of time, it can sufficiently satisfactorily cope with higher performance of the cutting device, labor saving and energy saving of cutting, and lower cost.

Is a schematic diagram illustrating a measurement range of the inclination angle in the case of measuring the crystal grains (0001) plane in the upper layer of vapor-deposited α-type the Al ₂ O ₃ layer constituting the hard coating layer. It is a schematic diagram illustrating a measurement range of the inclination angle in the case of measuring the crystal grains (0001) plane in the lower layer of the deposited α-type the Al ₂ O ₃ layer constituting the hard coating layer. It is an inclination angle number distribution graph of the (0001) plane of the upper layer of the vapor-deposited α-type Al ₂ O ₃ layer constituting the hard coating layer of the coated cermet tool 2 of the present invention. It is an inclination angle number distribution graph of the (0001) plane of the lower layer of the vapor-deposited α-type Al ₂ O ₃ layer constituting the hard coating layer of the coated cermet tool 2 of the present invention. The inclination angle frequency distribution graph showing the tilt angle sections of 0 to 45 degrees to the conventional coated cermet deposited α-type the Al ₂ O ₃ layer constituting the hard coating layer of the tool 2. The inclination angle frequency distribution graph showing the tilt angle sections of 45 to 90 degrees to the conventional coated cermet deposited α-type the Al ₂ O ₃ layer constituting the hard coating layer of the tool 2.

Claims (1)

On the surface of the tool base composed of tungsten carbide based cemented carbide or titanium carbonitride based cermet,
(A) The lower 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, and a total average of 3 to 20 μm A Ti compound layer having a layer thickness,
(B) an aluminum oxide layer in which the upper layer has an α-type crystal structure in the state of chemical vapor deposition and has an average layer thickness of 20 μm or less,
In the surface-coated cermet cutting tool formed by vapor-depositing the hard coating layer composed of (a) and (b) above,
The aluminum oxide layer has an upper and lower two-layer structure composed of a lower layer and an upper layer each having an average layer thickness of 2 to 18 μm (however, the total average layer thickness is 20 μm or less), and further using a field emission scanning electron microscope, The crystal grains having a hexagonal crystal lattice existing within the measurement range of the polished surface parallel to the tool substrate surface are irradiated with electron beams, and the crystal plane of the crystal grains is normal to the polished surface. A tilt angle formed by a normal line of a certain (0001) plane is measured, and among the measured tilt angles, the measured tilt angle is in the range of 0 to 45 degrees for the upper layer and 45 to 90 degrees for the lower layer. Are divided into pitches of 0.25 degrees, and the frequency distribution in each section is represented by an inclination angle number distribution graph obtained by tabulating,
(A) The upper layer of the aluminum oxide layer has the highest peak in the inclination angle section within the range of 30 to 45 degrees, and the sum of the frequencies existing within the range of 30 to 45 degrees is the inclination angle number. An inclination angle frequency distribution graph that accounts for 50% or more of the total frequency in the distribution graph,
(B) In the lower layer of the aluminum oxide layer, the highest peak exists in the inclination angle section in the range of 75 to 90 degrees, and the total of the frequencies existing in the range of 75 to 90 degrees is the inclination angle number. Showing an inclination angle frequency distribution graph that occupies 50% or more of the total frequency in the distribution graph;
A surface-coated cermet cutting tool with a hard coating layer that features excellent chipping resistance in high-speed intermittent cutting.

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