JP2000218407A - Hard coating covering tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coating covering tool capable of dealing with dry cutting work and a high speed thereof by increasing oxidation resistance without sacrificing the wear resistance and the adhesion of a TiAlN coating. SOLUTION: Any one of high-speed steel, cemented carbide, cermet and ceramic is used as a base material, one or more (a) layers and one or more (b) layers are alternately formed, the (a) layer being made of any one of nitride, carbon nitride, oxide nitride and oxide and carbon nitride containing one, and remaining Ti, two kinds or more of Si, Cr and Nb, >=10% and <=60% with atom % of only metal component, and having a layer thickness of 0.1 μm to 3 μm and the (b) layer being made of any one of nitride, carbon nitride, oxide nitride, and oxide and carbon nitride, and remaining Ti, Al: >40% and <=75% with atom % of only metal component, and the (b) layers are located directly above the base material.

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 a metal material or 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.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and further improves the oxidation resistance without sacrificing the wear resistance and adhesion of the conventional TiAlN film, and makes the cutting process dry. It is an object of the present invention to provide a hard film coated tool corresponding to high speed.

[0006]

Means for Solving the Problems The inventors conducted detailed studies on the effects of various elements on the oxidation resistance, abrasion resistance, and adhesion to a base material of a hard coating and the layer structure of the coating. As a result, a nitride, a carbonitride, an oxynitride, or an oxycarbonitride (hereinafter, referred to as Ti-based nitride, etc.) mainly containing Ti containing one or more of Si, Cr, and Nb in an appropriate amount. ) And a nitride, carbonitride, oxynitride or oxycarbonitride (hereinafter TiAl) containing Ti and Al as main components.
It is referred to as a system nitride or the like. )), A coating in which the metal components contained in a specific value are restricted within a specific value is alternately coated one or more times, and at this time, the above-mentioned coating of TiAl-based nitride or the like is placed directly above the base material surface, whereby dry high-speed cutting is performed. In processing, the present inventors have found that the performance of a cutting tool is extremely good, and have reached the present invention.

That is, the present invention is based on any one of high-speed steel, cemented carbide, cermet, and ceramics, and contains one or more of Si, Cr, and Nb in an atomic% of only the metal component. % To 60%, any one of a nitride, a carbonitride, an oxynitride, and an oxycarbonitride composed of residual Ti, an a layer having a thickness of 0.1 μm to 3 μm, Atomic%: Al: more than 40% and 75% or less, remaining Ti
And a layer b, which is any one of a nitride, a carbonitride, an oxynitride, and an oxycarbonitride, each of which is alternately coated one or more times, and the b layer is directly above the surface of the base material. It is preferable that the hard coating is 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.

In general, when a TiAlN film is subjected to an oxidation test in the atmosphere, 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
Although it functions as an oxidation protection film against the inward diffusion of oxygen, which is the progress of oxidation, in dynamic cutting, the alumina layer on the outermost surface easily peels off from the porous Ti oxide layer immediately below it. Does not exert a sufficient effect on the progress of oxidation.

However, by adding one or more of Si, Cr and Nb to Ti-based nitride or the like in an appropriate amount, not only the oxidation resistance of the film itself is extremely improved, but also the outermost surface has An extremely dense composite oxide layer containing Si, Cr, and Nb serving as an oxidation protection film is formed.
Immediately below it, a porous T which causes the oxidation protective film to peel off
It was confirmed that no i-oxide was formed. To obtain the above effect, one or more of Si, Cr and Nb are
At least 10% of the metal component of the coating must be contained in atomic%. Conversely, if the content exceeds 60%, the ductility or the hardness of the coating is remarkably reduced, and it is difficult to use it as a cutting tool. I can't stand it.

The layer a of the present invention has a thickness of 0.1 μm to
Limited to 3 μm. When the thickness of the a-layer is less than 0.1 μm, the above-described effect of improving the oxidation resistance is not remarkably exhibited because the thickness of the a-layer is insufficient for inward diffusion of oxygen. If the thickness of the layer a exceeds 3 μm, the layer a is broken or peeled off during cutting. Therefore, the thickness of the layer a is 0.1 μm to 3 μm.
m. Desirably, it is 0.3 μm to 2 μm.

Although the a layer has excellent oxidation resistance under static and dynamic conditions, it does not have sufficient adhesion to the base material. For this reason, it is necessary to coat the b layer described in the claim, which is a film having a proper balance of adhesion, abrasion resistance, oxidation resistance, etc., a TiAl-based nitride, etc., immediately above the base material surface. It is. 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. A in the film
The lower the 1 content, the better the adhesion between the base material and the coating. However, if the content of Al is 40% or less in atomic% of only the metal component of the coating, the wear resistance and oxidation resistance of the coating are improved. No effect. However, if the content exceeds 75%, not only the adhesion between the base material and the film is deteriorated, but also the hardness of the film is lowered, and the wear resistance required for a tool cannot be obtained. Therefore, in order to obtain a good balance of adhesion, abrasion resistance, and oxidation resistance, it is important to adjust the Al content of the b layer to be more than 40% and not more than 75% by atomic% of only the metal component of the film. It is.

As described above, in the present invention, a layer b having a good balance of adhesion to the base material, abrasion resistance and oxidation resistance of the film itself is coated directly on the surface of the base material, and an extremely acid-resistant layer is formed thereon. It is extremely important to coat the a layer which is excellent in chemical properties, and as a result, it becomes possible to obtain a cutting tool corresponding to dry high-speed cutting. The same effect can be obtained by a multilayer coating in which a layer b and a layer b are alternately laminated after coating the layer b directly on the surface of the base material.

Further, each layer 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.

The method for coating the hard film-coated tool of the present invention is not particularly limited, but in consideration of the thermal 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 with reference to examples.

[0017]

Embodiment 1 Using a small-sized arc ion plating apparatus, various alloy targets as evaporation sources for metal components, N2 gas, CH4 gas, and Ar / O as reaction gases were used.
(2) Select a coating film from which a target film can be obtained from the mixed gas, and under a condition of a coating substrate temperature of 400 ° C. and a reaction gas pressure of 3.0 Pa, a cemented carbide 6-flute end mill having an outer diameter of 8 mm as a coating substrate; A potential of -150 V was applied to the cemented carbide insert to form a film so that the total thickness of the film was 4 µm.

Using the obtained hard film-coated end mill and insert, 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. Life time. Table 1
The details of the hard coatings according to the present example and the comparative example and the cutting results thereof are shown in FIG. Table 2 also shows cutting results of the conventional example.

(End mill cutting conditions) Tool: Carbide alloy 6-flute end mill Outer diameter 8 mm Cutting method: Side cutting down cut Work material: SKD11 (hardness 60 HRC) Cutting depth: Ad 12 mm × Rd 0.4 mm Cutting speed: 150m / min Feed: 0.03mm / tooth Cutting oil: Air blow

(Insert cutting conditions) Tool: SEE42TN Cutting method: 100 mm width x 250 mm length chamfering Work material: SKD61 (hardness 45 HRC) Cutting: 2.0 mm Cutting speed: 150 m / min Feeding: 0.15 mm / rev Cutting oil: None

[0021]

[Table 1]

[0022]

[Table 2]

From Tables 1 and 2, it can be seen that the example of the present invention has a remarkably improved tool life as compared with the comparative example and the conventional example, and is sufficiently compatible with dry high-speed cutting. In Comparative Example 31, the composition and thickness of the film are included in the present invention. However, since the layer structure of the film is different, in the cutting of the end mill, the insert, and both tools, peeling of the film occurs at an early stage. Short life. In Comparative Example 34, since the Al content of the b layer was extremely large, peeling occurred during the cutting from the b layer, resulting in an extremely short life.

[0024]

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. This is extremely effective in improving productivity in cutting.

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[Procedure amendment]

[Submission date] March 25, 1999 (1999.3.2
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

[0021]

[Table 1]

Claims (2)

[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 one or more of Si, Cr and Nb are 10%
Not less than 60% and any of nitride, carbonitride, oxynitride and oxycarbonitride composed of residual Ti, having a layer thickness of 0.1
a layer having a thickness of 3 μm to 3 μm, and an atomic percentage of only a metal component is more than 40% Al and 75% or less, and nitride, carbonitride, oxynitride,
A hard-coated tool, characterized in that at least one of the oxycarbonitrides is alternately coated with at least one b-layer, and the b-layer is located immediately above the surface of the base material. 2. A tool for coating a hard coating, wherein the hard coating according to claim 1 is coated by a physical vapor deposition method.