JP2008093754A - Surface coated cutting tool with hard coated layer exhibiting excellent chipping resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated cutting tool with a hard coated layer exhibiting excellent chipping resistance in high speed heavy cutting machining. <P>SOLUTION: A lower part layer is constituted of (a) a titanium carbonitride layer, (b) a Ti-Cr composite carbonitride layer an inclusion ratio of chrome of which is 0.01-0.1 (atomic ratio) and a Ti system compound laminated layer constituted by alternately laminating the above (a), (b), an upper layer is constituted of (c) a composite oxide layer of aluminum and chrome an inclusion ratio of chrome of which is 0.01-0.1 (atomic ratio) and additionally, the Ti-Cr composite carbonitride layer of the above (b) is constituted of the Ti-Cr composite carbonitride layer in which the highest peak exists in Σ3 in a constitutive atom covalent lattice point distribution graph formed in accordance with a measuring result of an inclination made by a normal of a (001) face and a (011) face of a crystal grain existing in a measuring area of a surface polishing face and a normal of the surface polishing face and a distribution ratio of Σ3 occupying in the whole of ΣN+1 is more than 60%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  This invention exhibits excellent chipping resistance with a hard coating layer, especially when milling of steel, stainless steel, cast iron, etc. is performed at high speed and under high speed heavy cutting conditions such as high feed and high cutting. The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated 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 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) the upper layer has an average layer thickness of 1 to 15 μm and an α-type crystal structure in the state of chemical vapor deposition;
Composition formula: (Al _{1 -Q} Cr _Q ) ₂ O ₃ (however, in terms of atomic ratio, Q: 0.01 to 0.1),
A composite oxide of Al and Cr satisfying the following conditions (hereinafter referred to as (Al, Cr) ₂ O ₃ )] layer
A coated tool formed by vapor-depositing the hard coating layer constituted by (a) and (b) above is known, and this coated tool is used for continuous cutting and intermittent cutting of various steels and cast irons, for example. This is also well known.

Further, in the above-mentioned coated tool, the constituent layer of the hard coating layer generally has a granular crystal structure, and the TiCN layer constituting the Ti compound layer as the lower layer is used for the purpose of improving the strength of the layer itself. In a normal chemical vapor deposition apparatus, a gas mixture containing organic carbonitride is used as a reaction gas, and it is formed by chemical vapor deposition at an intermediate temperature range of 700 to 950 ° C. so as to have a vertically grown crystal structure. It is also known.
JP 52-66508 A Japanese Patent Laid-Open No. 6-8010

  In recent years, the performance of cutting machines has been remarkable. On the other hand, there are strong demands for labor saving and energy saving of cutting work. In the above conventional coated tool, there is no problem when this is used for milling cutting under normal processing conditions such as steel, stainless steel and cast iron, but when this is used for high-speed high-feed high-cutting, Since the high temperature strength of the TiCN layer of the hard coating layer is not sufficient, it cannot withstand mechanical and thermal loads under high-speed, high-feed, high-cut milling processing, and chipping (small chipping) occurs early. At present, the service life is reached in a short time.

In view of the above, the present inventors have found that the above-described chipping resistance of the coated tool in which the composite oxide layer of aluminum and chromium (Al—Cr composite oxide layer) constitutes the upper layer of the hard coating layer. In order to improve, as shown in the schematic diagram shown in FIG. 1A, a crystal structure of a NaCl type face centered cubic crystal in which constituent atoms consisting of Ti, carbon, and nitrogen are present at lattice points (see FIG. 1). (B) shows a state cut at the (011) plane), and as a result of conducting research by paying attention to a TiCN layer showing a predetermined high-temperature hardness,
(A) The TiCN 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: 2~10%,} CH 3 CN: 1~5%, N 2: 10~30%, H 2: remainder,
Reaction atmosphere temperature: 800-930 ° C.
Reaction atmosphere pressure: 15-25 kPa,
It is formed by vapor deposition under the conditions (called normal conditions)
Under these normal conditions, when CrCl ₃ was added to the above reaction gas at a ratio of 0.02 to 1% by volume, and a layer was formed under the same conditions except for this, titanium (as a result) was formed. Ti) and chromium (Cr) composite carbonitride layer (hereinafter referred to as “Ti-Cr composite carbonitride layer”) is a ratio of 1 to 10 atomic% of Cr in the total amount with Ti. And the same NaCl-type face-centered cubic crystal structure as that of the conventional TiCN layer (see FIG. 1 above), that is, a NaCl-type face-centered cubic crystal structure in which some Ti atoms are replaced by Cr atoms. In addition, the high-temperature strength is further improved by the action of Cr containing substitution, so in the high-speed high-feed, high-cut milling cutting that requires extremely high mechanical and thermal load on the cutting edge, Chipping resistance of hard coating Contribute to improvement of performance.

(B) About the TiCN layer (henceforth a conventional TiCN layer) which comprises the hard coating layer of said conventional coated tool, and the Ti-Cr compound carbonitride layer of said (a),
Using a field emission scanning electron microscope, as illustrated in the schematic explanatory diagrams in FIGS. 2A and 2B, each crystal grain existing within the measurement range of the surface polished surface is irradiated with an electron beam, The inclination angle formed by the normal lines of the (001) plane and the (011) plane, which are the crystal planes of the crystal grains, with respect to the normal line of the surface polished surface (FIG. 2A shows (001) of the crystal planes. When the tilt angle of the surface is 0 degree and the tilt angle of the (011) plane is 45 degrees, the tilt angle of the (001) plane is 45 degrees and the tilt angle of the (011) plane is 0 degree. In this case, all the tilt angles of the crystal grains including these angles are measured. In this case, the crystal grains are at lattice points as described above, and Ti, carbon, And if the constituent atoms consisting of nitrogen and Ti-Cr composite carbonitride layer are further Ti, Cr, carbon and nitrogen Each of the constituent atoms has the crystal structure at the interface between crystal grains adjacent to each other based on the measurement tilt angle obtained as a result. The distribution of lattice points (constituent atom shared lattice points) that share one constituent atom between each other is calculated, and N lattice points that do not share constituent atoms between the constituent atom shared lattice points (N is a NaCl type face center) The form of constituent atomic shared lattice points existing in the cubic crystal structure is represented by ΣN + 1, and each ΣN + 1 occupies the entire ΣN + 1 (however, the upper limit value of N is 28 due to frequency) When a constituent atomic shared lattice point distribution graph showing a distribution ratio is created, the conventional TiCN layer has a relatively low constituent atomic shared lattice point distribution graph with a Σ3 distribution ratio of 30% or less as illustrated in FIG. To show In the Ti—Cr composite carbonitride layer, as shown in FIG. 3, the highest peak exists in Σ3, and the distribution ratio of Σ3 is extremely high with a distribution ratio of Σ3 of 60% or more. In addition, the distribution ratio of Σ3 of the Ti—Cr composite carbonitride layer varies depending on the Cr content in the layer, and the Cr content in the layer is the blending ratio of CrCl _{3 in} the reaction gas. Can be adjusted by.

(C) When forming the Ti—Cr composite nitride layer, the constituent atomic shared lattice point distribution graph is obtained by setting the Cr content ratio in the layer to 1 to 10 atomic% in the ratio to the total amount with Ti. As a result, the Ti—Cr composite carbonitride layer has a further improved high-temperature strength as compared with the conventional TiCN layer. Even if the Cr content ratio in the layer deviates from the above range to the lower side or to the higher side, the distribution ratio of Σ3 in the constituent atom shared lattice point distribution graph becomes less than 60%, and the desired content The effect of improving high-temperature strength cannot be obtained.

(D) The Ti—Cr composite carbonitride layer has a higher high-temperature strength than the conventional TiCN layer in addition to the high-temperature hardness and high-temperature strength of the conventional TiCN layer. The coated tool formed by laminating and depositing a carbonitride layer and a TiCN layer is a chipping-resistant chipping that has an excellent hard coating layer even in high-speed, high-feed, high-cut milling processes that require extremely high mechanical and thermal loads. To show the performance and to show the excellent performance for a long time.
The research results shown in (a) to (d) above were obtained.

This invention was made based on the above research results,
“(1) In a surface-coated cutting tool in which a hard coating layer composed of a lower layer and an upper layer is vapor-deposited on the surface of a tool base made of tungsten carbide-based cemented carbide or titanium carbonitride-based cermet,
The lower layer is
(A) a titanium carbonitride layer having an average layer thickness of 1 to 5 μm,
(B) Titanium having an average layer thickness of 1 to 5 μm and a chromium content ratio (Cr / (Ti + Cr)) of 0.01 to 0.1 in terms of atomic ratio relative to the total amount of titanium and chromium Chromium composite carbonitride layer,
(A) and (b) at least three or more layers are alternately stacked, and a titanium-based compound layer is formed by chemical vapor deposition so that the total average layer thickness is 5 to 15 μm.
The upper layer is
(C) It has an average layer thickness of 0.5 to 5 μm, and the content ratio of chromium to the total amount of aluminum and chromium (Cr / (Al + Cr)) is 0.01 to 0.1 in atomic ratio. A complex oxide layer of aluminum and chromium,
A surface-coated cutting tool that exhibits excellent chipping resistance, wherein the hard coating layer is provided with a hard coating layer.
(2) In the surface-coated cutting tool according to (1),
One of a titanium carbonate layer, a titanium nitride oxide layer, and a titanium carbonitride oxide layer between the lower layer made of the titanium-based compound laminate and the upper layer made of the composite oxide layer of aluminum and chromium, or The surface-coated cutting tool according to (1) above, wherein an intermediate layer having a total average layer thickness of 0.2 to 1 μm composed of two or more kinds is interposed.
(3) In the surface-coated cutting tool according to the above (1) to (2),
The composite carbonitride layer of titanium and chromium of (b) is irradiated with an electron beam on each crystal grain existing within the measurement range of the surface polishing surface using a field emission scanning electron microscope, and the surface polishing surface The tilt angle formed by the normal lines of the (001) plane and (011) plane, which are crystal planes of the crystal grains, is measured. In this case, the crystal grains have titanium, chromium, and carbon at lattice points. Each of the constituent atoms has a crystal structure of NaCl type face centered cubic crystal in which constituent atoms composed of nitrogen and nitrogen are present, respectively, at the interface between adjacent crystal grains based on the measured tilt angle. Calculates the distribution of lattice points that share one constituent atom between the crystal grains (constituent atom shared lattice points), and N lattice points that do not share constituent atoms between the constituent atom shared lattice points (N is N An even number of 2 or more in the crystal structure of the NaCl type face centered cubic crystal When the configuration of existing constituent atomic shared lattice points is expressed by ΣN + 1, the constituent atomic shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 to the entire ΣN + 1 (however, the upper limit is 28 due to the frequency) And Σ3 has a highest peak, and the distribution ratio of the Σ3 to the entire ΣN + 1 is 60% or more. The surface-coated cutting tool (coated tool) according to any one of (1) to (2), which is characterized in that "
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 limited as described above will be described.
(A) Titanium carbonitride (TiCN) layer The TiCN layer itself has a predetermined high-temperature hardness and exhibits wear resistance against wear during cutting, but if its average layer thickness is less than 1 μm, If sufficient wear resistance cannot be exhibited and the average layer thickness is 5 μm or more, sufficient adhesion strength with the adjacent Ti—Cr composite carbonitride layer cannot be ensured and chipping is performed. In order to cause generation, the average layer thickness is set to 1 to 5 μm.
As the TiCN layer, as shown in, for example, JP-A-6-8010 and JP-A-7-328808, as a reactive gas in a normal chemical vapor deposition apparatus for the purpose of improving the high-temperature strength of the layer. A TiCN layer having a vertically grown crystal structure (hereinafter referred to as “1-TiCN layer”) formed by chemical vapor deposition in a middle temperature region of 700 to 950 ° C. using a mixed gas containing organic carbonitrides. Although known, the TiCN layer referred to in the present invention naturally includes the 1-TiCN layer.

(B) Ti-Cr composite carbonitride layer Ti-Cr composite carbonitride layer has the excellent high-temperature hardness and excellent high-temperature strength, this property is a CrCl ₃ to the reaction gas 0.02 In the constituent atomic shared lattice distribution graph, as a result of chemical vapor deposition by adding at a volume percentage, the Cr content in the deposited layer is 1 to 10 atomic% as a percentage of the total amount with Ti. It is obtained when the distribution ratio of Σ3 is 60% or more. On the other hand, when the distribution ratio of Σ3 is less than 60%, the effect of improving high-temperature strength is small, and in high-speed, high-feed, high-cut milling processing, It is inevitable that chipping occurs in the layer, and excellent wear resistance cannot be exhibited. Therefore, the Cr content ratio (Cr / (Ti + Cr)) to the total amount of Ti and Cr is 0.01 to 0. 1 (provided that the atomic ratio) defined as, also, was defined as 60% or more a distribution ratio of [sum] 3.
In addition, when the average layer thickness of the Ti—Cr composite carbonitride layer is less than 1 μm, excellent high temperature characteristics cannot be exhibited. On the other hand, when the average layer thickness exceeds 5 μm, the Ti—Cr composite carbonitride layer is sufficiently thick with the adjacent TiCN layer. Since the adhesion strength could not be ensured, the average layer thickness was determined to be 1 to 5 μm.

(C) Ti-based compound stacking At least three TiCN layers and Ti-Cr composite carbonitride layers are alternately stacked, and Ti-based compound stacking is performed by chemical vapor deposition so that the total average layer thickness is 5 to 15 μm. However, if the total average layer thickness of the Ti-based compound laminate is less than 5 μm, sufficient wear resistance cannot be exhibited in high-speed, high-feed, high-cut milling processing, while the total average layer thickness exceeds 15 μm. Then, since chipping and abnormal wear are likely to occur, the total average layer thickness of the Ti-based compound stack is set to 5 to 15 μm.

(D) Al—Cr composite oxide layer The upper layer made of a composite oxide layer of aluminum and chromium has excellent high-temperature hardness and heat resistance due to its Al component, and excellent high-temperature strength due to its Cr component. Although it contributes to chipping resistance and wear resistance improvement of the coated tool, the content ratio of Cr component in the composite oxide layer (Al-Cr composite oxide layer) is the total amount of Al and Cr contained in the layer The ratio (= Cr / (Al + Cr)) in the range of 0.01 to 0.1 (however, the atomic ratio). When this value indicating the content ratio of the chromium component in the Al—Cr composite oxide layer is less than 0.01, the effect of improving the high-temperature strength of the upper layer is small, whereas when this value exceeds 0.1, The relative decrease in the amount of aluminum component in the upper layer causes a decrease in high-temperature hardness and heat resistance. As a result, there is a tendency for wear resistance to deteriorate, so the content of chromium component in the Al-Cr composite oxide layer (Cr / (Al + Cr) value converted by atomic ratio) is set to a value within the range of 0.01 to 0.1 as described above.
If the average layer thickness is less than 0.5 μm, the desired excellent cutting performance cannot be exhibited over a long period of time. On the other hand, if the average layer thickness exceeds 5 μm, chipping occurs. Since it becomes easy, the average layer thickness was determined to be 0.5 to 5 μm.

(E) Intermediate layer A total average layer thickness of 0.2 to 1 μm consisting of one or more of a titanium carbonate (TiCO) layer, a titanium nitride oxide (TiNO) layer and a titanium carbonitride oxide (TiCNO) layer An intermediate layer is interposed between the Ti-based compound stack composed of a TiCN layer and a Ti—Cr composite carbonitride layer and the Al—Cr composite oxide layer. Since the intermediate layer has excellent adhesion and high adhesion strength to both the Ti-based compound laminate and the Al—Cr composite oxide layer, the bonding strength between the Ti-based compound laminate and the Al—Cr composite oxide layer is high. As a result, there is an effect of increasing the high-temperature strength of the hard coating layer as a whole and improving the chipping resistance, but if the total average layer thickness is less than 0.2 μm, no improvement in bonding strength is observed, and the total When the average layer thickness exceeds 1 μm, abnormal damage such as chipping is likely to occur. Therefore, the total average layer thickness of the intermediate layer is set to 0.2 to 1 μm.

It is generally known that a TiN layer having a gold color is coated on the hard coating layer for the purpose of facilitating identification of a use corner after cutting of the coated tool. Alternatively, a TiN layer may be coated on the upper layer of the Al—Cr composite oxide layer for the purpose of identifying the use corner. In this case, the thickness of the coating layer of the TiN layer is sufficient to be 0.2 to 1 μm.
Also, in recent years, after forming a hard coating layer, a physical method, specifically, a dry or wet blasting process using a grinding wheel, a brush made of nylon, etc., SiC, Al ₂ O ₃ and ZrO ₂ particles as a medium, etc. Thus, it is known that the surface of the hard coating layer is smoothed and the welding resistance is improved, but it is of course possible to apply this to the coated tool of the present invention.

  In the coated tool of the present invention, the hard coating layer includes a lower layer of a Ti-based compound stack composed of an alternately stacked structure of a Ti—Cr composite carbonitride layer and a titanium carbonitride layer, and an upper portion composed of an Al—Cr composite oxide layer. (Claim 1), or an intermediate layer interposed between the Ti-based compound stack and the Al—Cr composite oxide layer (Claim 2), and the Ti— Assuming that the Cr composite carbonitride layer contains 1 to 10 atomic% of Cr in the ratio to the total amount of Ti, and the distribution ratio of Σ3 in the constituent atomic shared lattice distribution graph is extremely high of 60% or more. Since it is configured (Claim 3), not only milling under normal conditions such as various steels, stainless steels and cast irons, in particular, high speed and high mechanical load, high heat load and high heat generation. Even with feed and high cutting depth, Gres chipping resistance, shows the wear resistance, is to exhibit excellent cutting performance 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, TaC powder, NbC powder, Cr ₃ C ₂ powder, TiN powder, TaN powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared. Then, blended into the composition shown in Table 1, added with wax, ball mill mixed in alcohol for 10 hours, dried under reduced pressure, and then press molded into a compact of a predetermined shape at a pressure of 98 MPa. Is 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 a width of 0.15 mm and an angle of 20 degrees Chamfor Honing As a result, tool bases A to F made of a WC-based cemented carbide having a throwaway tip shape specified in ISO · SEEN1203AFTN1 were produced.

Next, on the surface of these tool bases A to F, using a normal chemical vapor deposition apparatus,
Reaction gas composition: by _{volume%, TiCl 4: 2~10%,} CH 3 CN: 1~5%, N 2: 10~30%, H 2: remainder, a predetermined composition within the range of,
Reaction atmosphere temperature: a predetermined temperature within a range of 800 to 930 ° C,
Reaction atmospheric pressure: a predetermined pressure within a range of 15 to 25 kPa,
Then, a TiCN layer having a target average layer thickness shown in Table 7 is formed by vapor deposition under the following conditions (Table 3), and then Ti—Cr composite carbonitriding is performed under the conditions shown in Table 2 and the target average layer thickness shown in Table 7. The material layer is formed by vapor deposition, and a Ti-based compound layer composed of alternating layers of TiCN layers and Ti—Cr composite carbonitride layers is deposited as a lower layer. Next, the conditions shown in Table 4 and Table 7 are shown. By depositing an Al—Cr composite oxide layer as an upper layer with a target average layer thickness to be formed and further forming an intermediate layer with the conditions shown in Table 5 and the target layer thickness shown in Table 7 by the present invention. Coated tools 1-6 were produced.
Note that “target Cr content ratio” in Table 2 is the value of Cr / (Ti + Cr) expressed in atomic ratio, and “target Cr content ratio” in Table 4 is Cr / (Al + Cr) expressed in atomic ratio. ) Value.

For the purpose of comparison, instead of the Ti—Cr composite carbonitride layer, a TiN layer or a TiC layer is formed under the conditions shown in Table 6 and the target average layer thickness shown in Table 8. Further, regarding the TiCN layer Is formed under the same conditions (Table 3) and the same target average layer thickness as the TiCN layer of the above-mentioned coated tool of the present invention, and the intermediate layer is deposited under the conditions shown in Table 5 and the target layer thickness shown in Table 8. By forming, conventionally coated tools 1 to 6 were respectively produced.
(The Al—Cr composite oxide layer and the intermediate layer were formed under the same conditions and the same target average layer thickness as those of the present invention coated tools 1 to 6).

Next, the field emission of the Ti—Cr composite carbonitride layer constituting the lower layer of the hard coating layer of the above-described coated tool of the present invention and the TiCN layer constituting the hard coated layer of the coated tool of the present invention and the conventional coated tool is described. Using a scanning electron microscope, a constituent atom sharing lattice distribution graph was created.
In other words, the constituent atomic shared lattice point distribution graph is shown in the column of the field emission scanning electron microscope in a state where the surfaces of the Ti-Cr composite carbonitride layer of the present invention and the conventional TiCN layer are respectively polished surfaces. Electron backscattering is performed by irradiating the polishing surface with an electron beam having an acceleration voltage of 15 kV at an incident angle of 70 degrees with an irradiation current of 1 nA on each crystal grain within the measurement range of the surface polishing surface. Using a diffraction image apparatus, a region of 30 × 50 μm is spaced at a spacing of 0.1 μm / step and the (001) plane and (011) plane, which are crystal planes of the crystal grains, with respect to the normal line of the surface polishing plane Measure the tilt angle formed by the normal, and based on the measured tilt angle, each of the constituent atoms shares one constituent atom between the crystal grains at the interface between the adjacent crystal grains. Lattice points (constituent atom sharing (Distribution point) distribution, and there are N lattice points that do not share constituent atoms between the constituent atomic shared lattice points (N is an even number of 2 or more in the crystal structure of the NaCl-type face-centered cubic crystal) When the atomic shared lattice point form is represented by ΣN + 1, it was created by determining the distribution ratio of each ΣN + 1 to the entire ΣN + 1 (however, the upper limit value is 28 due to frequency).

In the constituent atomic shared lattice point distribution graph of the Ti—Cr composite carbonitride layer of the present invention obtained as a result, the distribution ratio of Σ3 occupying the entire ΣN + 1 (N is an even number within the range of 2 to 28) is shown. 7 shows.
For comparison, the distribution ratio of Σ3 occupying the entire ΣN + 1 (N is all even numbers in the range of 2 to 28) in the constituent atomic shared lattice point distribution graph of the TiCN layer of the present coated tool and the conventional coated tool. Is shown in Table 8.

In the above-mentioned various constituent atomic share lattice point distribution graphs, as shown in Tables 7 and 8, the Ti—Cr composite carbonitride layers of the present coated tools 1 to 6 each have a distribution ratio of Σ3 of 60. %, The conventional TiCN layer of the conventional coated tools 1 to 6 shows a constituent atom shared lattice point distribution graph in which the distribution ratio of Σ3 is less than 30%. It was a thing.
3 is a constituent atomic shared lattice distribution graph of the Ti—Cr composite carbonitride layer formed under the condition A-4 in the coated tool 4 of the present invention, and FIG. FIG. 5 shows a constituent atomic shared lattice point distribution graph of a conventional TiCN layer formed under the conditions of a-5.

  Further, for the above-described coated tools 1 to 6 of the present invention and the conventional coated tools 1 to 6, the constituent layers of these hard coating layers were observed using an Auger spectroscopic analyzer (the longitudinal section of the layers was observed). And the thickness of the constituent layer of the hard coating layer of these coated tools was measured using a scanning electron microscope (same longitudinal section measurement). The average layer thickness (average value of 5-point measurement) substantially the same as the target layer thickness was shown.

First, for the above-described inventive coated tools 1 to 6 and conventional coated tools 1 to 6, face milling with a single blade was performed under the following cutting conditions A to C.
[Cutting conditions A]
Work material: JIS / SNCM439 block material,
Cutting speed: 350 m / min,
Cutting depth: 4 mm,
Single blade feed amount: 0.42 mm / tooth,
Cutting time: 5 minutes,
Wet high-speed, high-cut, high-feed cutting test (normal cutting speed, cutting, feed are 180 m / min, 1.5 mm, 0.2 mm / blade, respectively)
[Cutting conditions B]
Work material: JIS / SUS316 block material,
Cutting speed: 300 m / min,
Cutting depth: 3.5 mm,
Single blade feed rate: 0.4 mm / tooth,
Cutting time: 3 minutes,
Stainless steel wet high-speed high-cut high-feed cutting test (normal cutting speed, cutting and feed are 150 m / min, 1.5 mm, and 0.2 mm / blade, respectively),
[Cutting conditions C]
Work material: JIS / FCD450 block,
Cutting speed: 380 m / min,
Cutting depth: 4 mm,
Feed: 0.42 mm / tooth,
Cutting time: 5 minutes,
Ductile cast iron dry high-speed high-cut high-feed cutting test (normal cutting speed, cutting and feed are 180 m / min, 1.5 mm, and 0.2 mm / blade, respectively),
The flank wear width of the cutting edge in each of the above cutting tests was measured, and the measurement results are shown in Table 9.

  From the results shown in Table 9, the coated tools 1 to 6 of the present invention are formed of a Ti-based compound laminate in which the lower layer of the hard coating layer is composed of an alternately laminated structure of a Ti—Cr composite carbonitride layer and a titanium carbonitride layer. In addition, the Ti—Cr composite carbonitride layer contains 1 to 10 atomic% of Cr as a proportion of the total amount with Ti, and the distribution ratio of Σ3 in the constituent atomic shared lattice distribution graph is 60. %, And the upper layer of the hard coating layer is composed of an Al—Cr composite oxide layer having excellent high temperature hardness, heat resistance and high temperature strength, and the Ti— Since the Cr composite carbonitride layer and the Al—Cr composite oxide layer constitute a hard coating layer having a very high bonding strength through an intermediate layer, the mechanical and thermal load is large and high. Various steel, stainless steel and cast iron with heat generation In any high-speed, high-feed, high-cut milling cutting, the hard coating layer exhibits excellent chipping resistance and excellent wear resistance, whereas the lower layer of the hard coating layer has a conventional alternating TiCN layer and titanium nitride layer. The conventional coated tools 1 to 6 formed as a laminated structure or an alternately laminated structure of TiCN layers and titanium carbide layers cannot withstand the high mechanical and thermal loads of high-speed, high-feed, high-cut milling, and hard coating layers. It is clear that chipping occurs and wear is accelerated, which leads to a service life in a relatively short time.

  As described above, the coated tool of the present invention is not only milled under normal conditions such as various types of steel, stainless steel, and cast iron, and particularly has a large mechanical and thermal load and is accompanied by high heat generation. Even under high-speed, high-feed, high-cut high-speed heavy cutting conditions, it exhibits excellent chipping resistance and 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 diagram which shows the crystal structure of the NaCl type face centered cubic crystal which the conventional TiCN layer of a hard coating layer has. It is a schematic explanatory drawing which shows the measurement aspect of the inclination angle of the (001) plane and the (011) plane of the crystal grain which has a crystal structure of a NaCl type face centered cubic crystal. It is a constituent atom shared lattice point distribution graph of the Ti-Cr compound carbonitride layer formed on formation condition A-4 of the present invention covering tool 4. It is a constituent atom shared lattice point distribution graph of the conventional TiCN layer formed on the formation condition a-5 of the conventional coated tool 6.

Claims (3)

In a surface-coated cutting tool in which a hard coating layer composed of a lower layer and an upper 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,
The lower layer is
(A) a titanium carbonitride layer having an average layer thickness of 1 to 5 μm,
(B) Titanium having an average layer thickness of 1 to 5 μm and a chromium content ratio (Cr / (Ti + Cr)) of 0.01 to 0.1 in terms of atomic ratio relative to the total amount of titanium and chromium Chromium composite carbonitride layer,
(A) and (b) at least three or more layers are alternately stacked, and a titanium-based compound layer is formed by chemical vapor deposition so that the total average layer thickness is 5 to 15 μm.
The upper layer is
(C) It has an average layer thickness of 0.5 to 5 μm, and the content ratio of chromium to the total amount of aluminum and chromium (Cr / (Al + Cr)) is 0.01 to 0.1 in atomic ratio. A complex oxide layer of aluminum and chromium,
A surface-coated cutting tool that exhibits excellent chipping resistance, wherein the hard coating layer is provided with a hard coating layer. The surface-coated cutting tool according to claim 2,
One of a titanium carbonate layer, a titanium oxynitride layer and a titanium carbonitride oxide layer between the lower layer made of the titanium-based compound laminate and the upper layer made of the composite oxide layer of aluminum and chromium, or The surface-coated cutting tool according to claim 1, wherein an intermediate layer having a total average layer thickness of 0.2 to 1 µm is interposed. The surface-coated cutting tool according to claim 1 or 2,
The composite carbonitride layer of titanium and chromium of (b) is irradiated with an electron beam on each crystal grain existing within the measurement range of the surface polishing surface using a field emission scanning electron microscope, and the surface polishing surface The tilt angle formed by the normal lines of the (001) plane and (011) plane, which are crystal planes of the crystal grains, is measured. In this case, the crystal grains have titanium, chromium, and carbon at lattice points. Each of the constituent atoms has a crystal structure of NaCl type face centered cubic crystal in which constituent atoms composed of nitrogen and nitrogen are present, respectively, at the interface between adjacent crystal grains based on the measured tilt angle. Calculates the distribution of lattice points that share one constituent atom between the crystal grains (constituent atom shared lattice points), and N lattice points that do not share constituent atoms between the constituent atom shared lattice points (N is N An even number of 2 or more in the crystal structure of the NaCl type face centered cubic crystal When the configuration of existing constituent atomic shared lattice points is represented by ΣN + 1, the constituent atomic shared lattice point distribution graph showing the distribution ratio of each ΣN + 1 in the entire ΣN + 1 (however, the upper limit is 28 in terms of frequency) In any of the above, it is a composite carbonitride layer of titanium and chromium that shows a constituent atomic shared lattice point distribution graph in which the highest peak exists in Σ3 and the distribution ratio of the Σ3 in the entire ΣN + 1 is 60% or more. The surface-coated cutting tool according to any one of claims 1 to 2, wherein the surface-coated cutting tool is characterized.

Images