JP2003145307A - Physical vapor deposition hard film-coated tool having excellent crater abrasion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-layer hard film-coated tool having excellent crater abrasion resistance comprising a composite of hard film having excellent adhesion performance, and a hard layer having lubricity, restricting chemical reaction with a material to be cut, and having excellent crater abrasion resistance to cope with a dry-type and high-speed cutting work. SOLUTION: In this multi-layer hard film-coated tool coated with multi-layers of hard film on the surface of a substrate, more than one layer of each of hard film having excellent adhesion performance and Ti hard film comprising fine boron nitride grains dispersed in the film, having high hardness and lubricity, restricting chemical reaction with a workpiece, and having excellent crater abrasion resistance are coated.

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, and particularly to a physical vapor deposition hard film coated tool having excellent crater wear resistance applied to high speed cutting and dry cutting. It is a thing.

[0002]

2. Description of the Related Art In cutting heat-treated steel for the purpose of improving the efficiency of metal working, a TiAlN coating represented by JP-A-62-56565 and JP-A-2-194159 has been developed and a cutting tool has been developed. Has been applied to. The TiAlN film has better oxidation resistance than TiN and TiCN.
In the cutting of heat-treated steel whose cutting edge reaches a high temperature, the performance of the cutting tool is remarkably improved.

However, in recent years, in order to meet the demands for higher efficiency and higher accuracy of machining, dry machining is regarded as important in view of environmental problems and machining cost reduction in addition to high cutting speed. There is. Under such a cutting environment, a chemical reaction occurs between the wear-resistant coating on the surface of the cutting tool and the material to be cut, and the tool life is not limited to the scrape wear of the flank but also the crater of the rake face. The tendency to be strongly controlled by wear has become stronger. Under the severe cutting environment, the TiN, TiCN, and TiAlN coatings up to now have a sufficient cutting life due to the increase in crater wear caused by the chemical reaction with the work piece as the cutting temperature rises. The reality is that it cannot be done.
In particular, when applying a PVD coating in lathe processing which is relatively continuous cutting and milling processing at high speed and high feed, it is extremely important to suppress this crater wear.

In order to solve such a problem, special table 1
Molybdenum disulfide shown in 1-502775, and a lubricating coating made of tungsten carbide and diamond-like carbon shown in JP-A 7-164211, a hard coating having wear resistance is laminated on the outermost surface,
Cutting tools have been developed that try to suppress the diffusion phenomenon between the coating and the work piece based on the suppression of the cutting temperature rise, but in both cases the adhesion to the underlying hard coating is poor and the coating itself is very brittle. However, these lubricating coatings easily peel or break during cutting, and have no effect in the above cutting environment. In addition, JP-A-11
A tool coated with a Cr-based lubricating film, which is disclosed in Japanese Patent No. 156992, has been proposed, but the Cr-based film has low hardness itself and extremely poor wear resistance, and has not yet improved crater wear resistance.

[0005]

In view of these circumstances, the present invention is capable of coping with dry and high-speed cutting, has less chemical reaction with the work, and has excellent lubricity and A layer [A] containing Ti as a main component, which has significantly improved crater wear resistance that suppresses diffusion with the coating, and a layer [B] having excellent adhesion and adhesion are combined to improve crater wear resistance. An object is to provide an excellent physical vapor deposition hard coating tool.

[0006]

Means for Solving the Problems As a result of intensive studies of the hard layer containing Ti as a main component, the inventors have found that the hardness of the hard layer containing Ti as a main component can be improved by interposing a BN phase in the layer. And the lubricity of the BN phase improves the lubricity of the hard layer containing Ti as a main component, and as a result, the crater wear resistance was significantly improved. As a result, it has been confirmed that the diffusion phenomenon is small in the dry type and high speed cutting process, the crater wear resistance is excellent, and the life as a cutting tool is extremely good, and the present invention has been achieved.

As a result of intensive studies on the effects of various additive components using the TiN-based coating as an example, the present inventors have found that the crater wear resistance of TiN can be remarkably improved by adding boron and optimizing the coating conditions. I got it. As a result of investigating the cause, boron nitride is extremely finely dispersed inside the TiN film, the hardness of the TiN film is significantly increased from 2200 to 2800 by Vickers, and the boron nitride is originally excellent in lubricity. It was confirmed that the friction coefficient of TiN was drastically reduced from 0.8 to 0.4 by the effect of. That is, the surprising fact that it is possible to disperse and strengthen a ceramic hard coating and at the same time impart the lubricity of the dispersed phase to the hard coating, and the method thereof have been discovered.

FIGS. 1 and 2 show ESCA analysis results of a TiBN film coated with a TiB target at a substrate bias of 300 V and a reaction pressure of 0.5 Pa. The binding energy diffraction peaks of Ti and N of FIG. 1 and B and N of FIG.
The binding energy diffraction peak with is confirmed, and the film is Ti
It was confirmed that it consisted of N phase and BN phase. In this case, the BN phase was a nanocrystal having a size of several nanometers to several tens of nanometers according to the TEM observation result, and it was confirmed that the hardness of the TiN layer was significantly increased due to the occurrence of lattice strain. The result was that the crater wear resistance was significantly improved compared to TiN. It is considered that this is because the BN phase itself has excellent lubricity. When boron is added and the ion energy is small under the coating conditions, nano-B
The appearance of N phase was not observed. Therefore, it can be said that the optimization of coating conditions is also important in order to achieve high hardness by interposing nanocrystals.

However, there are cases where the desired results cannot be obtained with the TiN layer single layer in which the fine crystals are interposed. The reason is that the residual compressive stress of the coating tends to increase with the inclusion of fine BN crystals, and in the TiN layer single layer in which the fine particles are dispersed, peeling of the coating occurs and the tool life becomes unstable. There is. Therefore, in order to suppress this phenomenon, it is indispensable to use a hard coating having excellent adhesion in combination with a multilayer structure or the like.

As described above, as a result of greatly improving the crater wear resistance, the multilayer hard coating tool according to the present invention is effective for tools used for high speed, high feed milling cutting, Furthermore, it can be applied to the lathe processing field where the CVD coated tool having the alumina coating has been used conventionally. Since turning is relatively continuous cutting, tool life is often dominated by crater wear. Also in the present invention, if the film thickness is thin, the crater wear resistance will be inferior to the CVD film, but by coating the squeeze surface where crater wear occurs at 3 μm or more, crater wear resistance comparable to that of the CVD film It was confirmed that it is possible to have sex. Further, in terms of the fracture resistance of the tool, the present invention is based on the PVD method. Compared with a CVD-coated tool in which compressive stress remains in the coating, cracks are less likely to occur, and residual tensile stress is present in the coating. As a result, the chipping resistance was over 10 times overwhelmingly excellent. When the film thickness exceeds 15 μ, peeling may occur, and it can be said that the film thickness is more preferably 3 μ to 15 μ.

The hard coating tool of the present invention is not particularly limited in its coating method, but in consideration of the heat effect on the coating base material, the fatigue strength of the tool, the adhesion of the coating, etc., The arc discharge type ion plating physical vapor deposition method is desirable.

(Embodiment 1) The present invention will be described based on an embodiment. Using an arc ion plating device,
Targets made of various alloys that are evaporation sources of metal components, and those that obtain the target film from the reaction gases nitrogen gas, oxygen gas, and methane gas are selected. Under the conditions of a coated substrate temperature of 400 ° C., a reaction gas pressure of 1.0 Pa, and a substrate applying bias voltage of 150 V, a tool was prepared by coating the respective coatings shown in Table 1 on a carbide insert for milling as a coated substrate. In the comparative example, each film was also coated under the same conditions. In the present invention, the Ti-based hard layer was coated under the same temperature at a bias potential of 300 V and a reaction gas pressure of 0.5 Pa with a phase having a BN bond interposed. Boron was contained in the film by adding a required amount of Ti to the target. The cemented carbide used for the insert is JIS-
P40 grade cemented carbide

[0013]

[Table 1]

A cutting test was carried out using the obtained hard coating-coated insert. The tool life is defined as the cutting time when the tool becomes uncutable due to crater wear, because if the coating does not peel under this cutting condition, crater wear dominates the life. The cutting specifications are shown below. In milling where the feed per blade exceeds 1 mm, the cutting temperature locally rises and crater wear tends to occur.

The insert cutting conditions are the tool shape RDMW.
Round piece insert 1604 MOTN, width 100mm
Chamfering with a length of 250 mm, the work material is SKD61 (hardness HR) in which φ10 mm drill holes are provided at 20 mm intervals.
C45), notch 1.0 mm, cutting speed 200 m / m
in, feed 1.5 mm / blade, dry cutting. The cutting of such a work material is a particularly strong interrupted cutting, and the coating tends to peel off. Table 1 also shows the cutting length leading to the chipping. The film thickness shown in Table 1 shows the film thickness on the squeeze surface.

As is clear from Table 1, the examples of the present invention show remarkable improvement in life. Since all of these comparative examples had a short life due to crater wear and film peeling,
It can be said that it is largely due to improvement in adhesion and crater abrasion resistance.

Example 2 Table 1 is based on the method of Example 1.
The coatings of the examples of the present invention and comparative examples described were coated on a cermet insert for turning, and turning was performed. The composition of the cermet alloy used is 60TiCN-10WC-1 in weight percent.
_0TaC-5Mo a 2 C-5Ni-10Co.

The cutting conditions are S53 with four grooves as the work material.
Using C, the cutting speed is 200 m / min, the incision is 1 mm, the feed is 0.12 mm / rev, and it is water-soluble. Since the cutting is intermittent cutting, the coating tends to peel off, and when it does not peel off, heat generation increases due to the progress of crater wear, and flank wear tends to increase. Flank wear value is 0.1
The time when it reached mm was determined to be the life. The cutting time to the end of life is shown in Table 2. Chip shape is TNGG11030
2R.

[0019]

[Table 2]

As is clear from the results shown in Table 2, the present invention example has a long life even in intermittent high-speed turning, does not cause film peeling, and can realize extremely stable cutting.

[0021]

INDUSTRIAL APPLICABILITY As described above, the multilayer hard coating tool of the present invention is superior in crater wear resistance as compared with the conventional coated tool, and has a remarkably long tool life in dry high speed cutting, and is produced in cutting. It is extremely effective in improving the productivity, reducing the cost, and improving the environment.

[Brief description of drawings]

FIG. 1 is a result of ESCA analysis of a TiBN film of an example of the present invention, showing a binding energy diffraction peak of Ti and N.

FIG. 2 is a result of ESCA analysis of the film of the present invention, showing the binding energy diffraction peaks of B and N.

Claims (3)

[Claims] 1. C, N, O containing Ti as a main component on the surface of a substrate.
A hard layer [A] composed of one or more elements selected from the following, one or more metal components selected from the groups 4a, 5a, 6a and Si, and 1 selected from C, N and O In a physical vapor deposition coated tool in which two or more hard layers [B] composed of one or more elements are coated in multiple layers, a boron nitride phase is interposed in the [A] layers. Physical vapor deposition hard film coated tool with excellent crater wear. 2. The physical vapor deposition hard film coated tool according to claim 1, wherein the [B] layer is coated directly on the substrate, which has excellent crater wear resistance. 3. The physical vapor deposition hard coating tool according to claim 1, wherein the substrate is a cemented carbide or cermet alloy insert, and the total coating thickness is 3 μ to 15 μ on the squeeze surface. A physical vapor deposition hard film coated tool with excellent crater wear resistance.