JP2007245267A - Coated cermet cutting tool having hard coating layer exerting excellent anti-chipping performance in high-speed, intermittent cutting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated cutting tool made of cermet exerting excellent anti-chipping performance in the high-speed, intermittent cutting. <P>SOLUTION: The α-type Al<SB>2</SB>O<SB>3</SB>layer constituting the hard coating layer is formed as a dual layer α-type Al<SB>2</SB>O<SB>3</SB>layer consisting of a reformed layer and a standard layer, and crystal grains having a hexagonal crystal lattice existing within the measuring range on a surface to be polished is irradiated individually with an electron beam using a scanning electron microscope of field emission type, and measurement is conducted for the inclination angle of the normal to the (0001) face as the crystal face of each crystal grain relative to the normal to the surface to be polished, whereupon the measured inclination angles are divided, followed by plotting an inclination angle frequency distribution graph formed by totalizing the frequencies existing in each division, in which the reformed layer exhibits an inclination angle frequency distribution graph having the max. peak in the inclination angle division within the range 0-10 degs. while the standard layer exhibits an inclination angle frequency distribution graph having no peak over the whole measured inclination angle division within the range 0-45 degs. and further has a pattern where the hard coating layer residual stress is reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention has an excellent high-temperature strength, particularly an aluminum oxide layer (hereinafter referred to as an Al ₂ O ₃ layer) that is a constituent layer of a hard coating layer, and can cut various steel and cast iron at high speed. A surface-coated cermet cutting tool that exhibits excellent chipping resistance and excellent wear resistance over a long period of time even under intermittent cutting conditions with mechanical impact (hereinafter referred to as “cutting tools”) , 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) As a lower layer, 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 TiCO) A Ti compound layer consisting of one or two or more layers of carbonitride oxide (hereinafter referred to as TiCNO) layers and having an overall average layer thickness of 3 to 20 μm,
(B) As an upper layer, an aluminum oxide layer (hereinafter referred to as an α-type Al ₂ O ₃ layer) having an average layer thickness of 2 to 15 μm and having an α-type crystal structure in a state of chemical vapor deposition,
A coated cermet tool formed by chemical vapor deposition of the hard coating layer composed of (a) and (b) above is known, and this coated cermet tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. It is well known to be used in

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

In recent years, the performance of cutting machines has been remarkable. On the other hand, there is a strong demand for labor saving and energy saving and further cost reduction for cutting work, and along with this, cutting work tends to be further accelerated. For coated cermet tools, there is no problem if this is used for continuous cutting or interrupted cutting under normal conditions such as steel or cast iron, but this is particularly high-speed interrupted cutting with mechanical impact. When used under conditions, the α-type Al ₂ O ₃ layer constituting the hard coating layer has insufficient high-temperature strength, and the hard coating layer has a tensile stress generated during the cooling process during layer formation. In combination with the remaining, chipping (slight chipping) is likely to occur in the hard coating layer, and this causes the service life in a relatively short time.

The present inventors have, from the viewpoint as described above, focuses on coated cermet tool α type the Al ₂ O ₃ layer described above constituting the upper layer of the hard coating layer, in particular the α-type the Al ₂ O ₃ layer As a result of further research to develop a coated cermet tool that does not generate chipping under high-speed interrupted cutting processing conditions, further reducing the residual tensile stress of the hard coating layer.
(A-1) The α-type Al ₂ O ₃ layer as the hard coating layer of the conventional coated cermet tool is generally 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,
The α-type Al ₂ O ₃ layer (hereinafter referred to as the standard layer) formed under the normal conditions is subjected to a field emission scanning electron microscope as shown in FIG. As shown in the schematic explanatory diagram in (b), each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the normal line of the surface polished surface is obtained. The inclination angle formed by the normal line of the (0001) 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 of the measurement inclination angle is set to a pitch of 0.25 degrees. When the inclination angle number distribution graph is created by dividing each of the areas and counting the frequencies existing in each section, the distribution of the measured inclination angles on the (0001) plane is 0 to 45 degrees as illustrated in FIG. An unbiased inclination angle number distribution graph within the range of.

(A-2) On the other hand, the α-type Al ₂ O ₃ layer was similarly used with a normal chemical vapor deposition apparatus,
Reaction gas composition: volume%, AlCl ₃ : 6 to 10%, CO ₂ : 0.1 to 1%, HCl: 0.3 to 3%, H ₂ S: 0.5 to 1%, Ar: 10 to 10% 35%, H ₂ : remaining,
Reaction atmosphere temperature: 1000 to 1050 ° C.
Reaction atmosphere pressure: 5 to 8 kPa,
If the reaction gas composition is adjusted to the reaction gas composition different from the reaction gas composition of the above normal conditions (the temperature and pressure of the reaction atmosphere are the same as the above normal conditions), this result is obtained. The formed α-type Al ₂ O ₃ layer (hereinafter referred to as a modified layer) was also measured using a field emission scanning electron microscope, as shown in FIGS. 1 (a) and 1 (b). The crystal grains having a hexagonal crystal lattice existing therein are irradiated with electron beams, and the normal of the (0001) plane, which is the crystal plane of the crystal grains, is inclined with respect to the normal of the surface polished surface The angle is measured, and the measured inclination angle within the range of 0 to 45 degrees is divided into 0.25 degree pitches among the measured inclination angles, and the degrees existing in the respective sections are totaled. When expressed in the angle distribution graph, as illustrated in FIG. A sharp maximum peak appears at a specific position in the oblique section. According to the test results, when the reaction atmosphere pressure in the chemical vapor deposition apparatus is changed within the range of 5 to 8 kPa as described above, the sharp maximum peak appears. The position changes within the range of 0 to 10 degrees of the inclination angle section, and the total of the frequencies existing in the range of 0 to 10 degrees represents a ratio of 45 to 65% of the entire frequencies in the inclination angle frequency distribution graph. The reformed layer in which the highest peak of the tilt angle section appears in the range of 0 to 10 degrees in the tilt angle number distribution graph as a result is higher in hardness than the standard layer formed under the normal conditions described above. There is a decrease in height, but it has relatively good high-temperature strength.

(B-1) In general, a hard coating layer in a coated cermet tool is formed by being deposited on the surface of a tool base at a reaction temperature of about 1000 ° C. and cooled to room temperature by a chemical vapor deposition apparatus. In the cooling process, since the thermal expansion coefficient of the hard coating layer is relatively larger than the thermal expansion coefficient of the tool base, tensile stress remains in the hard coating layer. Residual tensile stress in the hard coating layer acts to promote chipping in high-speed intermittent cutting.

(B-2) On the other hand, a single basic shape mark, for example, a single basic shape mark such as a circle, a triangle, and a quadrangle, or a similar shape thereof, is either one of the rake face and flank face of the tool base, Alternatively, as shown in the embodiment in which the single basic shape mark is circular in FIGS. 5 to 11, for example, as shown in FIGS. Either or both of the aggregate marks of the basic shape marks are distributed (in this case, the examples shown in FIGS. 5 to 7 have a relatively thin hard coating layer, and FIGS. 8 and 9 and FIGS. 10 and 11). (Showing a distribution mode when the layer thickness is increased according to the above), and the single basic shape mark is a digging surface where any one of the constituent layers of the hard coating layer is exposed ( Before this case The depth of the exposed surface of the single basic shape mark is individually adjusted according to the layer thickness of the hard coating layer, but corresponds to 5 to 20% of the layer thickness in order to reduce the residual stress efficiently. If the laser beam irradiation pattern is formed at a depth that is a guideline), the residual stress of the hard coating layer is significantly reduced. By forming this hard coating layer residual stress reduction pattern, high-speed intermittent cutting is performed. The occurrence of chipping due to residual stress in the hard coating layer is significantly suppressed.

(C) Therefore, the α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer whose lower layer is a Ti compound layer, is 55 to 80% of the total layer thickness of the Al ₂ O ₃ layer. A top and bottom double layer structure consisting of a modified layer and the rest of the standard layer, and by measuring the surface polished surface, the modified layer has the highest peak in the tilt angle section within the range of 0 to 10 degrees, The inclination angle distribution graph in which the total of the frequencies existing in the range of 0 to 10 degrees occupies a ratio of 45 to 65% of the entire frequencies in the inclination angle distribution graph, and the standard layer is set to 0 to 45 degrees. It is composed of a double layer α-type Al ₂ O ₃ layer showing no inclination angle distribution graph in which there is no peak over the entire measured inclination angle range, and the distribution of the measured inclination angle is unbiased. The coated cermet tool formed with the residual stress reducing pattern is the double Since the α-type Al ₂ O ₃ layer is composed of a modified layer having relatively high temperature strength and a standard layer having high temperature hardness, it has excellent high temperature strength and high temperature as the characteristics of the entire Al ₂ O ₃ layer. Since the tensile stress remaining inside is extremely small due to the hard coating layer residual stress reducing pattern, the above hard coating layer can be obtained even when cutting under high-speed intermittent cutting conditions. The entire upper layer of the single layer α-type Al ₂ O ₃ layer shows an unbiased inclination angle number distribution graph within the range of the measured inclination angle of the (0001) plane corresponding to the standard layer in the range of 0 to 45 degrees. Compared to the conventional coated cermet tool composed of the above, the hard coating layer will exhibit superior wear resistance over a long period of time without the occurrence of chipping.
The research results shown in (a) to (d) above were obtained.

This invention has been made based on the above research results, and it covers the rake face and flank face of the tool base, and the entire surface of the cutting edge ridge line where these both faces meet.
(A) As a lower layer, a Ti compound layer composed of one or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer and having an overall average layer thickness of 3 to 20 μm,
(B) an α-type Al ₂ O ₃ layer having an average layer thickness of ₂ to 15 μm as an upper layer;
In the coated cermet tool formed by chemical vapor deposition of the hard coating layer composed of (a) and (b) above,
The α-type Al ₂ O ₃ layer has an upper and lower double layer structure consisting of 55 to 80% of the modified layer and the remaining standard layer in the ratio of the average layer thickness of the entire Al ₂ O ₃ layer, and a field emission type Using a scanning electron microscope, each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface is irradiated with an electron beam, and the crystal of the crystal grain is normal to the surface polished surface. Measuring the inclination angle formed by the normal line of the (0001) plane, and dividing the measurement inclination angle within the range of 0 to 45 degrees out of the measurement inclination angles every pitch of 0.25 degrees; When expressed in the slope angle distribution graph, which is the sum of the frequencies existing in each category,
(A) The modified layer of the α-type Al ₂ O ₃ layer has the highest peak in the tilt angle section within the range of 0 to 10 degrees, and the sum of the frequencies existing in the range of 0 to 10 degrees. Shows an inclination angle number distribution graph occupying a proportion of 45 to 65% of the entire frequency in the inclination angle number distribution graph,
(B) In the standard layer of the α-type Al ₂ O ₃ layer, there is no peak over the entire measurement inclination angle section in the range of 0 to 45 degrees, and the inclination angle number distribution in which the measurement inclination angle distribution is unbiased. Showing the graph,
It is composed of a double layer α-type Al ₂ O ₃ layer composed of (A) and (B) above.
Furthermore, either one or both of the rake face and the flank face, or the single basic shape mark and the set mark of the single basic shape mark are distributed over the entire surface of both surfaces, The single basic shape mark is formed by irradiating a laser beam with a hard coating layer residual stress reduction pattern in which any one of the constituent layers of the hard coating layer is exposed.
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 double-layer α-type Al ₂ O ₃ layer and contributes to improving the high-temperature strength of the entire hard coating layer by its excellent high-temperature strength. The double-layer α-type Al ₂ O ₃ layer has a function of firmly adhering to any of the _two layers, thereby improving the adhesion of the hard coating layer to the tool substrate. However, when the average layer thickness is less than 3 μm, the above-described effect is sufficiently obtained. On the other hand, if the average layer thickness exceeds 20 μm, it becomes easy to cause thermoplastic deformation especially in high-speed cutting with high heat generation, which causes uneven wear. Was determined to be 3 to 20 μm.

(B) Double layer α-type Al ₂ O ₃ layer (upper layer)
As described above, the highest peak position of the measured tilt angle in the tilt angle number distribution graph of the double layer α-type Al ₂ O ₃ layer is the reaction atmosphere pressure in the chemical vapor deposition apparatus, as described above, in the range of 5 to 8 kPa. And the sum of the frequencies existing within the range of 0 to 10 degrees is 45 to 65 of the entire frequencies in the tilt angle frequency distribution graph. % Of the inclination angle number distribution graph (in this case, even if the reaction atmosphere pressure is adjusted, it is not possible to occupy a frequency ratio of 65% or more). Regardless of whether the atmospheric pressure is out of the above range or out of the above range, the maximum peak position of the measured inclination angle is out of the range of 0 to 10 degrees, and the inclination angle number distribution is corresponding to this. G The ratio of the frequency existing within the range of 0 to 10 degrees in the rough is also less than 45% of the entire frequency, and the desired excellent high-temperature strength cannot be ensured.
The double-layer α-type Al ₂ O ₃ layer has excellent high-temperature strength and high-temperature hardness due to the high-temperature strength of the modified layer and the high-temperature hardness of the standard layer. If the layer thickness of the porous layer is less than 55% of the average layer thickness of the entire Al ₂ O ₃ layer, the desired excellent high-temperature strength cannot be ensured, and chipping is likely to occur. However, if it exceeds 80%, the high-temperature hardness rapidly decreases and the progress of wear accelerates. Therefore, the layer thickness of the modified layer is a ratio of the average layer thickness of the entire Al ₂ O ₃ layer. The upper and lower double layer structure is defined as 55 to 80%, and the remainder is occupied by the standard layer (corresponding to the conventional α-type Al ₂ O ₃ layer).
Furthermore, if the average layer thickness of the entire double-layer α-type Al ₂ O ₃ layer is less than 2 μm, the excellent characteristics of the double layer α-type Al ₂ O ₃ layer cannot be exhibited sufficiently, while the average layer thickness exceeds 15 μm and becomes too thick. Then, since chipping is likely to occur in the cutting edge portion, the overall average layer thickness is set to 2 to 15 μm.

  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.

In the coated cermet tool of the present invention, the double layer α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer has excellent high temperature strength and high temperature hardness, and forms a hard coating layer residual stress reduction pattern. As a result, even when cutting various steels and cast irons at high speed and under intermittent cutting conditions with high mechanical impact, the hard coating layer has excellent wear resistance without occurrence of chipping. It can be used to further extend 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 the raw material powder, both (in mass ratio, TiC / TiN = 50/50 ) TiCN having an average particle diameter of 0.5~2μm powder, Mo ₂ C powder, ZrC powder, NbC powder, TaC powder, WC 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 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: 0.07 mm. Tool bases a to f made of TiCN-based cermet having a chip shape conforming to ISO standards / CNMG 120212 were formed.

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. The Ti compound layer is deposited as a lower layer of the hard coating layer with the combinations and target layer thicknesses shown in Table 5 under the conditions shown in FIG.
(B) Next, under the conditions shown in Table 4, any one of the modified layers (a) to (j) and the standard layers (1) to (8) with the combinations and target layer thicknesses shown in Table 5 A double layer α-type Al ₂ O ₃ layer made of the above is formed by vapor deposition as the upper layer of the hard coating layer,
(C) Furthermore, using a laser beam irradiation device, the hard coating layer,
Laser beam output: 10W
The shape of a single basic shape mark: a circle with a diameter of 0.5 mm,
Hard coating layer residual stress reduction pattern: Table 5 shows any of the implementation patterns shown in FIGS.
Applicable in the combinations shown in
Depth of the exposed surface of the single basic shape mark: the depth shown in Table 5 as a percentage of the total target layer thickness,
The coated cermet tools 1 to 13 of the present invention were produced by forming a hard coating layer residual stress reducing pattern under the conditions described above.

For comparison purposes, the single layer α-type Al ₂ O ₃ layer, which is the upper layer of the hard coating layer, is formed on the formation conditions of the standard layers (1) to (8) shown in Table 4 (as described above, the standard The formation conditions of the layers (1) to (8) are the same as the formation conditions of the single-layer α-type Al ₂ O ₃ layer), with the combinations and target layer thicknesses shown in Table 7, and the hard coating layer remaining Conventional coated cermet tools 1 to 13 were produced under the same conditions as the above-described coated cermet tools 1 to 13 of the present invention except that the stress reduction pattern was not formed.

Subsequently, the double-layer α-type Al ₂ O ₃ layer and the single-layer α-type Al ₂ O ₃ layer constituting the upper layer of the hard coating layer of the above-described coated cermet tool 1 to 13 of the present invention and the conventional coated cermet tool 1 to 13 Using the field emission type scanning electron microscope, an inclination angle number distribution graph was prepared.
That is, the inclination angle number distribution graph shows the modified layer of the double layer α-type Al ₂ O ₃ layer and the standard layer of the above-described coated cermet tools 1 to 13 in a state where each surface is a polished surface. 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 on the polished surface is irradiated with 1 nA within the measurement range of each polished surface. By irradiating each crystal grain having an existing hexagonal crystal lattice and using an electron backscatter diffraction image apparatus, a region of 30 × 50 μm is spaced at a spacing of 0.1 μm / step with respect to 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 crystal grain is measured, and based on the measurement result, the measurement inclination angle within the range of 0 to 45 degrees of the measurement inclination angle is calculated. Divide every 0.25 degree pitch In addition, it was created by counting the frequencies existing in each category.
Further, the surface polished surfaces of the conventional coated cermet tools 1 to 13 of the single layer α-type Al ₂ O ₃ layer (corresponding to any one of the standard layers (1) to (8) as described above) are also subjected to the same conditions. Observed, and created a tilt angle distribution graph under the same conditions.

In the inclination angle number distribution graphs of the various α-type Al ₂ O ₃ layers obtained as a result, as shown in Tables 5 to 7, double-layer α-type Al ₂ O ₃ layers of the coated cermet tools 1 to 13 of the present invention, respectively. The modified layer of (0001) shows a gradient angle distribution graph in which the distribution of the measured inclination angle of the (0001) plane shows the highest peak in the inclination angle section within the range of 0 to 10 degrees, respectively. The standard layer of the double-layer α-type Al ₂ O ₃ layer of the cermet tools 1 to 13 and the single-layer α-type Al ₂ O ₃ layer of the conventional coated cermet tools 1 to 13 have a distribution of measured inclination angles on the (0001) plane. An inclination angle distribution graph that is unbiased within the range of 0 to 45 degrees and does not have the highest peak is shown.
Tables 5 to 7 show the inclination angle numbers of all inclination angle numbers existing in the inclination angle sections in the range of 0 to 10 degrees in the above-mentioned inclination angle number distribution graphs of the various α-type Al ₂ O ₃ layers. The percentage of the entire distribution graph is shown.
2 and 3 are graphs showing the distribution of inclination angle numbers of the double layer α-type Al ₂ O ₃ layer and the standard layer of the coated cermet tool 2 of the present invention, and FIG. 4 is a single layer α of the conventional coated cermet tool 3. the inclination angle frequency distribution graph of the mold 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 two round bars with longitudinal grooves,
Cutting speed: 380 m / min. ,
Incision: 1.5mm,
Feed: 0.25 mm / rev. ,
Cutting time: 10 minutes,
Wet high-speed intermittent cutting test (normal cutting speed is 200 m / min.) Of carbon steel under the conditions (referred to as cutting conditions A),
Work material: JIS / SNCM439 two longitudinally-equipped round bars in the longitudinal direction,
Cutting speed: 360 m / min. ,
Cutting depth: 2mm,
Feed: 0.2 mm / rev. ,
Cutting time: 10 minutes,
Wet high-speed intermittent cutting test (normal cutting speed is 200 m / min.) Of alloy steel under the following conditions (referred to as cutting condition B),
Work material: JIS / FC300 lengthwise equidistant 4 bars with vertical grooves,
Cutting speed: 400 m / min. ,
Incision: 1.5mm,
Feed: 0.25 mm / rev. ,
Cutting time: 10 minutes,
The wet high speed intermittent cutting test (normal cutting speed is 200 m / min.) Of cast iron under the above conditions (referred to as cutting condition C) was performed, 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 5 to 8, the coated cermet tools 1 to 13 of the present invention each have a double layer α-type Al ₂ O ₃ layer upper and lower double layer structure modified layer, which is the upper layer of the hard coating layer. The (0001) plane tilt angle number distribution graph shows the highest peak in the tilt angle section in the range of 0 to 10 degrees, and as a result, it has relatively good high-temperature strength, while the same standard layer is relatively It retains excellent high-temperature hardness, and the hard coating layer is formed with a pattern for reducing residual stress in the hard coating layer, so steel and cast iron are machined at high speed with high mechanical impact. Even when performed under intermittent cutting conditions, chipping does not occur and excellent wear resistance is exhibited. On the other hand, the entire upper layer of the hard coating layer has a measured inclination angle distribution on the (0001) plane of 0 to 45 degrees. Inclination number distribution graph that is unbiased within the range and does not have the highest peak The conventional coated cermet tools 1 to 13 are composed of a single α-type Al ₂ O ₃ layer corresponding to any one of the standard layers (a) to (h) and have no hard coating layer residual stress reducing pattern formed. In both cases, not only the high-temperature strength of the single-layer α-type Al ₂ O ₃ layer is insufficient but also the residual stress in the hard coating layer is relatively high. It is clear that chipping occurs in the layer, leading to a service life 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.

It is a schematic diagram illustrating a measurement range of the inclination angle of the case of measuring the crystal grain of the α-type the Al ₂ O ₃ layer constituting the hard coating layer (0001) plane. It is an inclination angle number distribution graph of the (0001) plane of the modified layer of the double layer 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 standard layer of the double layer α-type Al ₂ O ₃ layer constituting the hard coating layer of the coated cermet tool 2 of the present invention. 4 is an inclination angle number distribution graph of a (0001) plane of a single-layer α-type Al ₂ O ₃ layer (corresponding to a standard layer) constituting a hard coating layer of a conventional coated cermet tool 3. It is a schematic perspective view of this invention coating cutting tip which formed the hard coating layer residual stress reduction pattern as an Example by laser beam irradiation formation. FIG. 6 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reducing pattern as an embodiment other than FIG. 5 is formed by laser beam irradiation. FIG. 7 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reduction pattern as an embodiment other than FIGS. FIG. 8 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reduction pattern as an embodiment other than FIGS. FIG. 9 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reducing pattern as an embodiment other than FIGS. FIG. 10 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reduction pattern as an embodiment other than FIGS. FIG. 11 is a schematic perspective view of a coated cutting tip of the present invention in which a hard coating layer residual stress reducing pattern as an embodiment other than FIGS.

Claims (1)

Over the rake face and flank face of the tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet, and further across the entire surface of the cutting edge ridge line where these both sides intersect,
(A) As a lower layer, it consists of one or more of Ti carbide layer, nitride layer, carbonitride layer, carbonate layer, and carbonitride oxide layer, and has an overall average of 3 to 20 μm A Ti compound layer having a layer thickness,
(B) an α-type aluminum oxide layer having an α-type crystal structure in a chemical vapor deposited state and an average layer thickness of 2 to 15 μm as an upper layer;
In the surface-coated cermet cutting tool formed by chemical vapor deposition of the hard coating layer composed of (a) and (b) above,
The α-type aluminum oxide layer has an upper and lower double layer structure consisting of 55 to 80% of the modified layer and the remaining standard layer in the ratio of the average thickness of the entire aluminum oxide layer, and a field emission scanning electron microscope. The crystal grain of the crystal grain is used with respect to the normal of the surface polished surface by irradiating each crystal grain having a hexagonal crystal lattice existing within the measurement range of the surface polished surface with an electron beam (0001 ) Measure the tilt angle formed by the normal of the surface, and divide the measured tilt angle within the range of 0-45 degrees out of the measured tilt angle by pitch of 0.25 degrees and exist in each section When it is shown in the inclination angle frequency distribution graph obtained by counting the frequencies to be
(A) In the modified layer of the α-type aluminum oxide layer, the highest peak is present in the tilt angle section within the range of 0 to 10 degrees, and the sum of the frequencies existing within the range of 0 to 10 degrees is The inclination angle number distribution graph which occupies the ratio of 45 to 65% of the whole frequency in the inclination angle number distribution graph is shown.
(B) The standard layer of the α-type aluminum oxide layer has an inclination angle number distribution graph in which no peak exists over the entire measurement inclination angle range of 0 to 45 degrees and the distribution of the measurement inclination angle is unbiased. Show,
It is composed of a double layer α-type aluminum oxide layer composed of (A) and (B) above.
Furthermore, either one or both of the rake face and the flank face, or the single basic shape mark and the set mark of the single basic shape mark are distributed over the entire surface of both surfaces, The single basic shape mark was formed by irradiating a laser beam with a hard coating layer residual stress reduction pattern in which any one of the constituent layers of the hard coating layer was exposed.
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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