JP3347687B2 - 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 formed by forming a fine structure such as TiSi-based nitride into a nitride, carbonitride, or oxynitride containing Ti as a main component. Alternatively, one or more layers are alternately coated so that Si3N4 and Si are present as independent phases in the oxycarbonitride, and a nitride layer mainly composed of Ti as a metal component is formed directly on the surface of the base material. By doing so, it was found that the performance of the cutting tool was extremely good in dry high-speed cutting, and the present invention was reached.

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 and less than 10%, remaining: any of nitride, carbonitride, oxynitride, and oxycarbonitride composed of Ti, in which Si ₃ N ₄ and Si are independent phases A layer present in the compound as
1 is more than 40% and 75% or less, B, Si, V, Cr,
One or two of Y, Zr, Nb, Mo, Hf, Ta, W
Species and less than 10%, remainder: nitride composed of Ti,
The b layer, which is any one of carbonitride, oxynitride, and oxycarbonitride, is alternately coated one or more times, and is formed of a nitride mainly composed of Ti as a metal component immediately above the surface of the base material. Has a c layer of not less than 0.1 μm and not more than 1 μm;
Immediately above the layer is a hard film coating tool characterized by a layer b, and 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 microstructure of the a-layer is a nitride, carbonitride, oxynitride or oxycarbonitride containing Ti as a main component.
By adopting a structure in which i3N4 and Si are present as independent phases, high hardness can be achieved, and a film having extremely excellent wear resistance can be obtained. In order to form a film having such a structure, that is, the layer a of the present invention, differences in physical vapor deposition methods such as an arc discharge type ion plating and sputtering, and the basic method of a film forming apparatus even with the same method. Although the absolute value differs depending on the specification, it can be achieved by setting the bias voltage applied to the substrate to a relatively low value such as -10 to -100 V during coating.

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 the a layer having the abrasion resistance and the oxidation resistance of the film itself in good balance. It is extremely important to coat the layer and the layer a, which has remarkably excellent oxidation resistance and wear resistance, and as a result, it becomes possible to obtain a cutting tool corresponding to dry high-speed cutting. Also,
The same effect can be obtained by a multilayer coating in which a layer c is coated immediately above the base material surface and a layer b is coated thereon, and then the layers a and b 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 of coating the hard film-coated tool of the present invention is not particularly limited, but when considering the heat effect on the coated base material, the fatigue strength of the tool, the adhesion of the film, etc. Arc discharge ion plating that can be coated at a relatively low temperature and compressive stress remains in the coated film,
Alternatively, a physical vapor deposition method of applying a bias voltage to the coating base material side such as sputtering is preferable. Hereinafter, the present invention will be described based on examples.

[0019]

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 51, 52, 53, 5
For 4, 55, 56, 57, and 58, a film was formed by applying a bias voltage of -30 V, but for Comparative Example 59, a film was formed by applying a bias voltage of -200 V. 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. The thicknesses of the a-layer and the b-layer of the present invention example and the comparative example are basically about 1: 1. However, in the case where the total number of layers in the table is two, the a-layer is about 0.5 μm. Therefore, the layer b has a 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, machining 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 at that time is determined by the tool length. Life time. Table 1 shows examples of the present invention, Table 2 shows comparative examples, and Table 3 shows details of hard coatings of conventional examples and cutting results thereof. Si _{3 in} a layer
The presence or absence of N ₄ and Si was confirmed by XPS, and the films in which the presence of Si ₃ N ₄ and / or Si was recognized are described in the table.

The cutting conditions of the end mill were as follows: a 6-blade end mill made of cemented carbide, an outer diameter of 8 mm was used as the tool, the side cutting was down cut, and the work material was 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 drill made of cemented carbide as a tool, an outer diameter of 8 mm;
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.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

From Tables 1, 2 and 3, the examples of the present invention are as follows.
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 50, the composition of the coating, the layer structure, and the microstructure of the a-layer were all included in the present invention. Therefore, the tool performance was the most excellent in the comparative examples, but the thickness of the c-layer was too large. In addition, the tool life was inferior to the example of the present invention. In Comparative Example 51, the composition of the film is included in the present invention, but since the layer structure of the film is different,
In cutting of the end mill, the drill, and both tools, peeling of the film occurred early, and the life was extremely short. Comparative Example 5
8 is included in the present invention with respect to the composition and layer structure of the film, but since the a layer contains only the Si phase, sufficient film hardness cannot be obtained, and compared to the examples of the present invention. Short life.

[0027]

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
r, Y, Zr, Nb, Mo, Hf, Ta, 1 kind or less than 10% in more than one W, rest: nitride composed of Ti, carbonitride, oxynitride, oxycarbonitride product S
a layer in which i ₃ N ₄ and Si are present as independent phases in the compound, and the atomic% of the metal component alone is more than 40% and 75% or less, B, Si, V, Cr, Y, Zr, N
b, Mo, Hf, Ta, W or one or more of 10
% Less, rest: composed of Ti nitrides, carbonitrides, oxynitrides, b layer is either oxycarbonitride material is coated alternately one or more layers respectively, and directly above the base metal surface Is a nitride mainly composed of Ti as a metal component and has a layer thickness of 0.1 μm.
A hard-coated tool, comprising a c-layer having a length of m to 1 μm 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.