JPH09295204A - Surface coating throw away insert - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the sufficient adhesiveness of a film even in a cutting process of a steel, of which hardness is higher than the Rockwell hardness at 40 (scale C), by setting the diffraction intensity of a surface (200) at the time of X-ray diffraction of a coating layer at a value larger than a value of the diffraction intensity of a surface (111). SOLUTION: Surface of a throw away insert is coated with the compound nitride of Ti and Al, carbon nitride, and carbide. In this throw away insert, in the case where diffraction intensity of a surface (111) at the time of X-ray diffraction of a coating layer is expressed with I (111) and diffraction intensity of a surface (200) is expressed with I (200), both the diffraction intensity are set so that a value of I (200)/I (111) becomes 1 or more. For example, a compact arc ion plating device is used so that coating of a film of (Ti0.5 Al0.5 ) N is performed at 5μm of thickness in the condition of bias voltage at 60 V, vacuum degree at 2.0×10<-2> mbar, arc current at 150 A. A coating layer at 1.5 of I (200)/I (111) is thereby formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated throw-away insert having excellent fracture resistance and peel resistance.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 4-53642 and Japanese Patent Publication No.
There are many reports confirming the effect of Al addition to the TiN film as seen in each of the publications of -67705. However, in these inventions, the improvement of the oxidation resistance of the coating by the addition of Al and the improvement of the physical properties of the coating were only recognized, and in the coated throw-away insert,
It has not been possible to obtain a sufficiently satisfactory film adhesion.
In particular, in recent years, there is a strong tendency for the die to be processed after heat treatment in die processing, and in the case of processing high hardness steel after heat treatment, cutting processing is required in the conventional throw-away insert mainly composed of Ti and Al. Peeling of the coating easily occurs inside, and the tool life is determined by peeling, and a satisfactory tool life has not yet been obtained.

[0003]

SUMMARY OF THE INVENTION In order to solve such problems, the present inventors have improved the adhesion of a coating in the evaluation of cutting processing of high hardness steel exceeding Rockwell hardness 40 (C scale). As a result of earnest research,
We came to the following facts.

[0004]

The first finding that has led to the present invention is that various tools such as a throw-away insert, an end mill, and a drill are used when machining a die. It was found that the optimum film design should differ depending on the difference in For throw-away inserts,
In general, the feed amount per blade often exceeds 0.1 mm, and particularly in the cutting of high hardness steel, the cutting stress is extremely high and the film peeling easily occurs. Further, the cutting temperature reaches 800 ° C. or higher, the high temperature physical properties of the coating determine the tool life, and the oxidation resistance of the coating is of course an important factor because the cutting edge becomes hot. Therefore, in cutting processing of throw-away inserts of high hardness materials, improving the adhesion, high temperature physical properties and oxidation resistance of the coating based on these findings will significantly improve the tool life. .

[0005]

The second finding is that in contrast to the first finding, the orientation of the (200) plane in the X-ray diffraction of the coating adheres to the coating and controls the high temperature physical properties and the oxidation resistance. . That is, it was concluded that as the orientation of the (200) plane becomes stronger than that of the (111) plane, the columnar crystal grain size of the film increases, and the toughness at room temperature can be improved. The peeling of the coating is often caused by the internal fracture of the coating due to the extremely high impact force when the throw-away insert hits the work piece. Since the throw-away insert bites into the work material at a relatively low temperature, increasing the toughness of the coating at room temperature suppresses internal fracture of the coating, which is one of the prerequisites for cutting high hardness materials described above.
It has been found that it is extremely important for improving the adhesion of the coating film. Further, by orienting the film on the (200) plane, the grain size of the columnar crystal grains is increased, so that the total grain boundary area in the film can be reduced.

According to the research conducted by the inventors of the present invention, it has been confirmed that the oxidation of the coating progresses through grain boundaries, and reducing the grain boundary area is another factor for cutting hard materials.
It goes without saying that it is extremely important for improving the oxidation resistance of the film, which is one of the necessary conditions. Furthermore, the film is (20
It has been found that when the grains are oriented in the (0) plane, the number of defects at the grain boundaries is reduced, and it is considered that the number of these defects is further improving the oxidation resistance of the film. Also,
It has been found that coarsening the columnar crystal grains suppresses the plastic deformation of the coating at high temperature and consequently increases the high temperature hardness. As a result, it is possible to greatly improve high-temperature physical properties, which is another necessary condition for cutting high hardness materials.

The third finding that led to the present invention is the above (2)
(00) plane oriented Ti and Al nitrides, carbonitrides, and Ti nitrides and carbonitrides used as an intermediate layer between the carbide coating and the substrate to further improve the adhesion of the coating. This is the point that we found that it was possible. In general, when a film containing Al is vapor-deposited by a physical vapor deposition method, particularly an arc ion plating method, coarse particles rich in Al component scatter from the target due to the low melting point of Al, which deteriorates the surface roughness of the film. There is a tendency. At the initial stage of coating of the substrate, it is effective to improve the adhesion by avoiding such a decrease and forming a dense film. From the nitride or carbonitride whose main component is Ti containing no Al, It is preferable to provide the intermediate layer to improve the adhesion. Especially Ti and Al oriented in the (200) plane
For a film containing Ti, by using an intermediate layer which is also oriented in the (200) plane, there is a high probability that the film containing Ti and Al will grow epitaxially with respect to the intermediate layer, and the adhesion can be further improved.

A fourth finding of the present invention is to find out that it is possible to further improve the tool life by suppressing the generation of heat during the cutting.
The composite nitrides of Ti and Al, carbonitrides, and carbides generally have a high friction coefficient of 0.40 to 0.45 with respect to steel, and the cutting edge is likely to have a high temperature during cutting.
By including oxygen in these coatings, it was possible to reduce the friction coefficient, and by using it in the outermost layer, it was confirmed that the tool life was further improved by reducing the cutting heat. Furthermore, the friction coefficient can be further reduced in the order of Ti carbonitride, carbonitride, and Al oxide. By using these coatings as the outermost layer, it has been confirmed that the tool life is further improved. It was Further, by mechanically wrapping the surface of the coating and setting the surface roughness to 1 μm or less, the friction coefficient can be further reduced and the tool life can be improved.

The fifth finding that led to the present invention is that Ti and Al
Compound nitrides, carbonitrides, and carbides of Zr, Hf, Y, S
One or more of i, W, and Cr are used as Ti
On the other hand, by substituting in the range of 0.05 at% to 60 at%, it is possible to further improve the oxidation resistance. By adding these components, the results of grain boundaries are limited, and it is possible to suppress the oxidation rate of the film, and the oxide layer formed on the film surface during cutting becomes a denser structure, and It is possible to suppress the diffusion into the inside of the film and to make the oxidation rate of the film extremely slow.
Further investigation of these reasons is underway.

The sixth finding that has led to the present invention is that the apparent adhesion force (σ ₁ ) of the film against peeling that occurs during cutting.
However, when σ ₂ is the adhesive force at the base material-film interface and σ ₃ residual compressive stress, it is found that σ ₁ = σ ₂ −k · σ ₃ (k is a constant). Therefore, if the residual stress of the film is too high, the apparent adhesion will be reduced. Therefore, controlling the residual stress within a certain range prevents deterioration of the adhesion of the film.

Next, the reason for limiting the numerical values will be described. (20
When the diffraction intensity of the (0) plane I (200) (111) plane is I (111), I (200) / I (111)
Is set to 1 or more, the orientation of the (111) plane becomes strong, and when this value is less than 1, the grain size of the columnar crystal layer becomes finer, and deterioration in room temperature toughness, deterioration in oxidation resistance, and decrease in high temperature altitude are caused. It was set to 1 or more to bring it.

If the thickness of the nitride or carbonitride layer of Ti used as the intermediate layer is less than 0.05 μm, there is no effect on improving the adhesion, and if it exceeds 5 μm, the wear resistance of the entire coating is impaired. It was set to 0.05 μm or more and 5 μm or less. The components such as Y added to improve the oxidation resistance are 0.05 atomic%
Below, the effect on the oxidation resistance is small, and if Ti is replaced in excess of 60 atomic%, the wear resistance is deteriorated.
It was set to be at least 05 atom% and at most 60 atom%.

When the residual compressive stress exceeds 5 GPa, the adhesiveness is less than the required limit under the use condition of the throw-away insert, and when it is 1 GPa or less, thermal cracking is likely to occur, so that it is set to 1 GPa or more and 5 GPa or less. Less than,
The present invention will be described based on examples.

[0014]

【Example】

Example 1 Using a compact arc ion plating apparatus, under the conditions shown in Table 1, a composite nitride of Ti and Al and a carbonitride were used.
The coating was performed so as to have a thickness of μm.

[0015]

[Table 1]

Table 1 shows possible cutting distances until peeling occurs when the obtained insert is milled under the following conditions.
It was also described in. The coating conditions shown in Table 1 are I (200) / I (111) and 1 depending on the size of the apparatus.
It does not correspond to one-to-one. The cutting specifications are for the work material SKD.
61 (HRC45), cutting speed: 100 m / min, feed:
0.1 mm / blade, depth of cut: 2.0 mm, insert shape: SEE42TN (G9). From Table 1, I
It is recognized that the coated throw-away insert of the present invention having (200) / I (111) of 1 or more is extremely effective for peeling.

Example 2 Using the experimental apparatus used in Example 1, coating was performed so that the film structure shown in Table 2 was obtained. The film thickness was unified to 5 μm. The same cutting evaluation as in Example 1 was performed to evaluate the tool life. The results are also shown in Table 2.

[0018]

[Table 2]

From Table 2, one or more I (200) / I (1
It is recognized that by providing the alloy of the present invention having the value 11) with the intermediate layer or the outermost layer, the tool life is further improved. Al ₂ O ₃ is the most effective as the outermost layer. Al ₂ O ₃ of the present embodiment is formed by coating a TiAl layer and then forming a film of 0.5 μm by plasma CVD.

Example 3 (TiAlX) N films having various compositions shown in Table 3 were prepared using the experimental apparatus used in Example 1. The coated test piece was held in an atmospheric furnace at 750 ° C. for 30 minutes, and the thickness of the formed oxide layer was measured. The results are also shown in Table 3.

[0021]

[Table 3]

As is clear from Table 3, Y, Si, W,
The addition of Cr, Zr and Hf can improve the oxidation resistance of the film.

[0023]

EFFECTS OF THE INVENTION By applying the present invention, it is possible to maintain sufficient film adhesion even in the cutting of high hardness steel having a Rockwell hardness of 40 (C scale) and in the case of processing a die. It can be applied to various tools such as face milling cutters, end mills and drills that use the applicable indexable inserts.

Claims (6)

[Claims] 1. In a throwaway insert coated with a composite nitride of Ti and Al, carbonitride, or carbide, the diffraction intensity of the (111) plane in the X-ray diffraction of the coating layer is I.
A surface-coated throw-away insert, wherein the value of I (200) / I (111) is 1 or more when the diffraction intensity of the (111) and (200) planes is I (200). 2. The surface-coated throw-away insert according to claim 1, wherein the substrate and a composite nitride of Ti and Al,
0.05 μm or more between the carbonitride and carbide coating layers
A surface coated throw-away insert, characterized by using Ti nitride or carbonitride having a film thickness of 0 μm or less as an intermediate layer. 3. A composite nitride of Ti and Al, which is inserted into the surface-coated throwaway according to claim 1 or 2,
On top of the carbonitride and carbide layers, one of Ti carbonitride, carbonitride, Ti-Al composite oxynitride, carbonitride, carbonate, oxide, and Al oxide is used. A surface coated throw-away insert characterized by coating a layer or two or more kinds of coating layers. 4. The surface-coated indexable insert according to claim 1, wherein a part of Ti is contained in the range of 0.05 at% to 60 at% with respect to Ti.
A surface-coated throw-away insert characterized by being replaced with one or more of f, Y, Si, W, and Cr. 5. The surface coated throw-away insert according to claim 1, wherein a composite nitride of Ti and Al,
A surface-coated throw-away insert characterized in that the compressive stress remaining in carbonitride and carbide is 1 Gpa or more and 5 Gpa. 6. The surface-coated indexable insert according to any one of claims 1 to 4, wherein the surface roughness of the indexable insert on the rake face side is 1 μm or less.