JP3343727B2 - Hard coating tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard film-coated tool used for cutting metal materials and the like.

[0002]

2. Description of the Related Art Conventionally, cutting tools coated with TiN, TiCN and the like have been widely used. Since TiN has relatively excellent oxidation resistance, it not only exhibits excellent wear resistance against tool rake surface wear caused by heat generated during cutting, but also has good adhesion to the base material. It is.
Moreover, since TiCN has a higher hardness than TiN, it exhibits excellent characteristics with respect to flank wear of a tool. However, in response to the tendency to increase the cutting speed for the purpose of increasing the efficiency of metal working, the hard coating does not exhibit sufficient oxidation resistance and wear resistance. From such a background, studies have been made to further improve the oxidation resistance and abrasion resistance of the coating. As a result, JP-A-62-56565 and JP-A-2-19415 have been studied.
No. 9 has been developed and applied to cutting tools.

[0003]

The TiAlN film has a Vickers hardness of approximately 2300 to 2800, although it varies depending on the component ratio of Ti and Al contained in the film. Since it is superior to TiN and TiCN, it greatly improves the performance of the cutting tool under cutting conditions in which the cutting edge reaches a high temperature. However, in recent years, in addition to the tendency for the cutting speed to be further increased, dry cutting is regarded as important in terms of environmental issues, and the use environment of cutting tools is becoming increasingly severe.

According to the study of the present inventors, the oxidation start temperature of a TiAlN film in the atmosphere is 450 ° C. of TiN.
On the other hand, the temperature increases to 750 to 900 ° C. depending on the amount of Al added. However, in the above-mentioned dry high-speed cutting, the cutting edge temperature of a tool to be used reaches a high temperature of 900 ° C. or more, and therefore, at present, a sufficient tool life cannot be obtained with the TiAlN film.

The present invention has been made in view of the above circumstances, and provides a hard coating capable of improving the oxidation resistance and abrasion resistance of a conventional TiAlN coating, and corresponding to dry cutting and high-speed cutting. The purpose is to provide a tool.

[0006]

The inventors of the present invention have conducted detailed studies on the effects of various elements on the oxidation resistance, abrasion resistance and adhesion of a hard coating and the layer structure of the coating. A nitride mainly containing Ti containing an appropriate amount of
Carbonitride, oxynitride or oxycarbonitride (hereinafter referred to as TiS
i-type nitride, etc.), and nitrides, carbonitrides, oxynitrides or oxycarbonitrides (hereinafter, referred to as nitrides) mainly containing Ti and Al.
A film in which the metal component contained in TiAl-based nitride or the like is limited to a specific value is adjusted so that the lattice constant of TiSi-based nitride or the like becomes 0.417 nm or more and 0.423 nm or less.
By alternately coating one or more layers at that time, by coating a nitride layer mainly composed of Ti as a metal component directly on the surface of the base material, the performance of the cutting tool becomes extremely good in dry high-speed cutting. And arrived at the present invention.

That is, the present invention relates to high-speed steel, cemented carbide,
Either cermet or ceramics as base material, Si is 10% or more and 60% or less in atomic% of metal component only, B,
Al, V, Cr, Y, Zr, Nb, Mo, Hf, Ta,
One or more of W, less than 10%, any of nitride, carbonitride, oxynitride, and oxycarbonitride composed of remaining Ti, having a NaCl-type crystal structure, and a lattice An a layer having a constant of 0.417 nm or more and 0.423 nm or less;
Atomic% of metal component alone: Al: more than 40% and 75% or less, B, Si, V, Cr, Y, Zr, Nb, Mo, H
f, Ta, one or more of W, less than 10%, residual T
a layer b having a NaCl-type crystal structure is alternately coated with at least one layer each of a nitride, a carbonitride, an oxynitride, and an oxycarbonitride composed of i. Is a nitride mainly composed of Ti as a metal component and has a layer thickness of 0.1
There is a c layer of not less than 1 μm and not more than 1 μm, and b
A hard film-coated tool characterized by being a layer, wherein the hard film is preferably coated by a physical vapor deposition method.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION First, the constituent requirements of the layer a described in the claims will be described in detail. Generally Ti
When an oxidation test is performed on the AlN film in the air, Al near the surface of the film diffuses outward to the outermost surface, where an alumina layer is formed. According to the study of the present inventors, this is considered to be the reason for improving the oxidation resistance. At this time, a very porous Ti oxide containing no Al is formed immediately below the alumina layer. In the static oxidation test, the alumina layer formed on the outermost surface functions as an oxidation protective film against the inward diffusion of oxygen, which is the progress of oxidation. The alumina layer is easily separated from the porous Ti oxide layer immediately below the alumina layer, and does not exert a sufficient effect on the progress of oxidation.

However, TiSi-based nitrides and the like not only have extremely high oxidation resistance of the film itself, but also form a very dense composite oxide layer containing Si which serves as an oxide protective film on the outermost surface. It was confirmed that a porous Ti oxide, which would cause peeling of the oxide protective film, was not formed immediately below. In order to obtain the above effect, Si must be contained in an amount of 10% or more in atomic% of only the metal component of the film. Conversely, if it exceeds 60%, the decrease in ductility or hardness of the film is remarkable. And cannot be used as a cutting tool.

B, Al, V, Cr, Y, Zr, Nb, M
o, Hf, Ta, and W act as solid solution strengthening elements in a film such as a TiSi-based nitride, and are effective in increasing the hardness of the film. Therefore, B, Al, V, Cr,
One or two of Y, Zr, Nb, Mo, Hf, Ta, W
It is desirable to add a trace amount of the seed or more. However, if 10% or more of the atomic component of only the metal component of the coating is added, the effect of improving the oxidation resistance due to the Si content described above cannot be obtained. Therefore, B, Al, V, Cr, Y, Zr, Nb, M
o, Hf, Ta, and W are one or more kinds and less than 10%.

The layer a of the present invention has a lattice constant of 0.417.
When the thickness is at least nm and at most 0.423 nm, high hardness can be achieved, and a film having extremely excellent wear resistance can be obtained. According to the study by the inventors, in the component range described in the claims, the lattice constant of the single a layer is 0.424 to 0.426 nm.
And the lattice constant of the single b layer is 0.415 to 0.417.
It has been confirmed that the nm and the single b layer are extremely small. However, the layer a and the layer b are alternately coated one or more times, and the bias voltage applied to the substrate at that time is controlled to an appropriate value. To match. As a result, the crystal lattice of the a layer is smaller than that of a single layer, lattice distortion occurs in the a layer, and the hardness is improved.
When coating the a layer and the b layer, the bias voltage applied to the substrate is different from the physical vapor deposition method such as the arc discharge type ion plating and the sputtering, and the basic specification of the film forming apparatus even if the same method is used. Although the absolute value differs depending on the type, the matching of the crystal lattice at the interface between the a layer and the b layer can be achieved by forming the two layers at an approximate bias voltage.

Next, the constituent requirements of the layer b described in the claims will be described in detail. The role of Al in the b layer, which is a film of a TiAl-based nitride or the like, is to improve the wear resistance and oxidation resistance of the film. The abrasion and oxidation resistance of the coating improves with increasing Al content in the coating. However, if the content exceeds 75%, the hardness of the film is reduced, and the wear resistance required for a tool cannot be obtained. Therefore, in order to obtain a good balance between wear resistance and oxidation resistance, it is important to adjust the Al content in the b layer to be more than 40% and not more than 75% by atomic% of only the metal component of the film. .

B, Si, V, Cr, Y, Zr, Nb, M
o, Hf, Ta, and W act as solid solution strengthening elements in a film such as a TiAl-based nitride and are effective in increasing the hardness of the film. Therefore, B, Si, V, Cr,
One or two of Y, Zr, Nb, Mo, Hf, Ta, W
It is desirable to add a trace amount of the seed or more. However, when 10% or more of the metal component of the coating is added in atomic%, the toughness of the coating is extremely reduced. Therefore, in order to obtain a good balance of wear resistance, oxidation resistance, and toughness, B, Si,
V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W are 1
More than 10% of species or two or more species.

Neither the a layer nor the b layer has sufficient adhesion to the base material. Therefore, just above the surface of the base material, a layer c of a nitride mainly composed of Ti as a metal component having excellent adhesion to the b layer and the base material and having appropriate wear resistance and oxidation resistance is required. is there. The c-layer is preferably made of TiN having a lower hardness than the a-layer and the b-layer. However, TiN is made of a metal belonging to the group IVa, Va, or VIa of the periodic table and Al, S
When a small amount of i, Y, Co, or the like is contained, the same effect can be obtained even when the content is less than 10 at% in atomic% of the metal component alone.

The thickness of the layer c is limited to 0.1 μm or more and 1 μm or less. The greater the thickness of the layer c, the more noticeable the improvement in adhesion. However, in general, during cutting, the coating at the cutting edge wears in the form of an oblique cross section, and therefore oxidation proceeds preferentially over the c layer, which has lower oxidation resistance than the a layer and the b layer. Therefore, when the thickness of the c layer is large, that is, when the exposed area of the c layer due to abrasion during cutting is large, preferential oxidation of the c layer becomes remarkable, and the performance of the cutting tool is not significantly improved. Further, when the thickness of the layer c is extremely thin, the effect of improving the adhesion is not remarkably exhibited. For the reasons described above, the layer thickness of the c layer is set to 0.1 μm or more and 1 μm or less. Preferably, 0.
It is 2 μm or more and 0.4 μm or less.

As described above, in the present invention, a layer c having excellent adhesion to the base material is coated directly on the surface of the base material, and NaCl having a good balance of wear resistance and oxidation resistance of the coating itself is provided thereon. It is extremely important to coat the b-layer having the type crystal structure and the a-layer having remarkably excellent oxidation resistance in the same NaCl type crystal structure as the b-layer, and as a result, a cutting tool corresponding to dry high-speed cutting Can be obtained. A similar effect can be obtained by a multilayer coating in which a layer c is coated immediately above the base material surface, a layer b is coated thereon, and then an a layer and a b layer are alternately laminated.

Each of the layers a and b can be adjusted to any of nitride, carbonitride, oxynitride and oxycarbonitride as required, and the same effect can be obtained with tools coated with them. can get. The method for coating the hard film-coated tool of the present invention is not particularly limited, but the thermal effect on the coated base material, the fatigue strength of the tool, the adhesion of the film, and the matching between the a layer and the b layer are not particularly limited. In consideration of the properties, etc., it can be coated at a relatively low temperature and compressive stress remains in the coated film Arc discharge type ion plating or physical vapor deposition method applying a bias voltage to the coating base material side such as sputtering Is desirable. Hereinafter, the present invention will be described based on examples.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Using a small arc ion plating apparatus, targets made of various alloys as evaporation sources of metal components, N ₂ gas, CH ₄ gas, and Ar / O as reaction gases were used.
₍₂ ) A cemented carbide 6-flute end mill (outer diameter 8 mm), which is a coated substrate, is selected from the mixed gas under the conditions of a coated substrate temperature of 400 ° C. and a reaction gas pressure of 3.0 Pa. And a cemented carbide drill (outside diameter 8mm)
The film was formed so that the thickness of the entire film was 4 μm. In addition, all of the present invention examples and comparative examples 54, 55, 56, 5
Regarding 8, 59, both the a-layer and the b-layer have -100
The same bias voltage of V was applied to form a film.
For 1, 52, 53, and 57, the a layer was set to −30 V, b
The layers were formed by applying different bias voltages to -200V. Further, the c layer of the present invention example and the comparative example and the conventional example were all formed by applying a bias voltage of -150 V. A layer and b of the present invention and comparative examples
The thickness of the layers is basically about 1: 1. However, when the total number of layers in the table is two, the thickness of the a layer is about 0.5.
The layer b is a layer thickness obtained by subtracting the layer a and the layer c (described in the table) from the thickness of the entire coating.

Using the obtained hard film-coated end mill and drill, processing is performed under the following dry high-speed cutting conditions until the tool cannot be cut due to chipping or wear of the cutting edge, and the cutting length and drilling at that time. The number was defined as the tool life. Table 1 shows the details of the hard coatings of the present invention and Table 2 and the cutting results thereof. The lattice constant of the a-layer was calculated from X-ray diffraction. Table 3 also shows the cutting results of the conventional example.

End mill cutting conditions are as follows: a 6-blade end mill made of cemented carbide, an outer diameter of 8 mm is used as a tool, and the side cut is down cut. The work material is SKD11 (HRC6).
0), cutting amount Ad = 12 mm, Rd = 0.2 mm,
Cutting speed = 200m / min, feed amount 0.03mm / t
ooth, cutting oil = none, but using air blow.

Next, the cutting conditions of the drill were as follows: a cemented carbide drill was used as a tool, and an outer diameter of 8 mm was used.
40 (HRC30) drilling, cutting speed = 90m / m
in, feed rate = 0.2 mm / rev, cutting oil = none, but using an air blow to machine a blind hole with a hole depth of 24 mm. In addition, the number of machined holes ended at a maximum of 2000 holes.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

From Tables 1, 2 and 3, the examples of the present invention
The tool life is remarkably improved as compared with the comparative example and the conventional example, and it can be seen that the tool life is sufficiently compatible with dry high-speed cutting. In Comparative Example 51, the coating composition is included in the present invention. However, since the coating has a different layer structure, peeling of the coating occurs early in cutting of the end mill, the drill, and both tools, resulting in a very short life. became. Comparative Examples 53 and 57
Although the composition and layer structure of the film are included in the present invention, since the lattice constant of the a layer is not satisfied, sufficient film hardness cannot be obtained and the life is shorter than that of the examples of the present invention. Was. Also in Comparative Example 59, although a relatively good tool life was exhibited as compared with the conventional example, the layer thickness of the c layer was large.
It has a shorter life than the present invention.

[0026]

As described above, the hard-coated tool of the present invention has superior oxidation resistance and wear resistance as compared with the conventional coated tool, so that the tool life in dry high-speed cutting is significantly longer. It is extremely effective not only for improving productivity in cutting but also for addressing environmental issues.

Claims (2)

(57) [Claims] 1. A high-speed steel, a cemented carbide, a cermet, or a ceramic as a base material, and an atomic% of only a metal component.
And Si is 10% or more and 60% or less, B, Al, V, C
a nitride composed of one or more of r, Y, Zr, Nb, Mo, Hf, Ta, W and less than 10%, with the balance being Ti;
Any of carbonitride, oxynitride and oxycarbonitride;
has an aCl-type crystal structure and a lattice constant of 0.417 n
a layer of not less than m and not more than 0.423 nm, and the atomic% of the metal component alone is more than 40% Al and not more than 75%, B, Si,
V, Cr, Y, Zr, Nb, Mo, Hf, Ta, W
Species or two or more and less than 10%, with a nitride, carbonitride, oxynitride, or oxycarbonitride composed of residual Ti,
A layer b having an NaCl-type crystal structure is alternately coated one or more times, and T
A hard-coated tool, characterized in that there is a c layer having a thickness of 0.1 μm or more and 1 μm or less which is a nitride mainly composed of i and a b layer immediately above the c layer. 2. A tool for coating a hard coating, wherein the hard coating according to claim 1 is coated by a physical vapor deposition method.