JP3445899B2 - Surface coated end mill - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated end mill having excellent wear resistance and peeling 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, only the improvement of the oxidation resistance of the coating and the improvement of the coating physical properties by the addition of Al were recognized, and in the coating end mill, sufficiently satisfactory adhesion of the coating and abrasion resistance were obtained. I haven't got it. Particularly 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, in the conventional end mill mainly composed of Ti and Al, the The peeling of the coating is likely to occur, the tool life is determined by the peeling, and the wear resistance is insufficient, so that a satisfactory tool life has not been obtained.

[0003]

SUMMARY OF THE INVENTION In order to solve such problems, the inventors of the present invention have evaluated the adhesion of the coating film and the adhesion of the coating film in the cutting processing evaluation of the high hardness steel exceeding Rockwell hardness 50 (C scale). As a result of intensive studies to improve wear resistance, the following facts have been found.

[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 a die is processed. It was found that the optimum film design should differ depending on the difference in Particularly, in the end mill cutting of high hardness steel exceeding HRC50, the cutting stress is extremely high and the film peeling easily occurs, and the cutting temperature is 500 ° C to 8 ° C.
The characteristic is that the temperature reaches over 00 ° C and the high temperature physical properties of the coating determine the tool life. Therefore, in the cutting process of a high hardness material with an end mill, improving the adhesion of the coating and the high temperature physical properties based on these findings will greatly improve the tool life.

[0005]

The second finding is that, in contrast to the first finding, the orientation of the (111) plane in X-ray diffraction of the film governs the apparent adhesion and high temperature physical properties of the film in end mill cutting. It is in. That is, it was concluded that as the orientation of the (111) plane becomes stronger, the columnar crystal grain size of the coating becomes smaller, and the hardness at room temperature can be improved. In the case of an end mill, particularly in cutting of high hardness steel having HRC of 50 or more, it has been found that the harder the coating, the less the peeling of the coating occurs. That is, in the case of a tool having a relatively sharp edge such as an end mill, when a minute cut of several tens of μm is applied to the cutting edge, especially in the case of high hardness steel, the shear stress generated there is high. When the edge is not applied, the wall thickness is small at the sharp edge, and the substrate itself cannot withstand this high shear stress. In other words, it is extremely important to protect the substrate with a hard "color". Therefore, even if the substrate is protected with a soft coating, it cannot withstand high shear stress. The strength of the sharp edge itself increases only after protecting the substrate with a hard color. When the base material is protected by a soft coating, it cannot withstand locally high shear stress, and minute chipping occurs due to plastic deformation of the base material.In this case, cutting stress increases, which leads to peeling of the coating and large chipping. Will be generated. Also, if the hardness of the film at room temperature is hard, it is 5
The hardness at high temperature is high from 00 to 800 ° C., and the hardness of the coating is maintained even at high temperature for end mill cutting, resulting in long tool life.

The third finding that led to the present invention is the above (1)
11) Ti and Al nitrides with more strongly oriented planes,
It is the point that the adhesion of the coating can be further improved by using Ti nitride or carbonitride as the intermediate layer between the carbonitride or carbide coating and the substrate. 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. It is effective to improve the adhesion by avoiding such a decrease and forming a dense film at the initial stage of coating the substrate.
It is preferable to provide an intermediate layer made of a nitride or a carbonitride containing Ti as a main component and not containing Al for improving the adhesion. In particular, Ti oriented in the (111) plane
For the film containing Al and Al, the film containing Ti and Al is epitaxially grown on the intermediate layer by using the intermediate layer which is also oriented in the (111) plane, and the adhesion is further improved.

The fourth finding of the present invention is that the tool life can be further improved by further suppressing the generation of heat during the above-mentioned cutting. The composite nitrides, carbonitrides, and carbides of Ti and Al generally have a high coefficient of friction with steel of 0.40 to 0.45, and the cutting edge is likely to have a high temperature during cutting. By including oxygen in the coating, 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, Ti carbonitride, carbonitride, Al
The coefficient of friction can be further reduced in the order of the oxides, and by using these coatings as the outermost layer, it has been confirmed that the tool life is further improved. Further, the Al oxide has high adhesion when formed by plasma CVD. Furthermore, mechanically wrap the surface of the coating of the end mill groove,
By 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 improve the oxidation resistance. For end mill cutting, the oxidation resistance of the coating is also important, although not as much as throwaway inserts. By adding these components, it is possible to suppress the oxidation of the crystal grain boundaries and suppress the oxidation rate of the coating, and the oxide layer formed on the coating surface during cutting becomes a more dense 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.

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 2.0 or less, the orientation of the (200) plane becomes strong, and when this value exceeds 2.0, the grain size of the columnar crystal layer becomes coarse, resulting in a decrease in room temperature hardness and a decrease in high temperature altitude. Therefore, it was set to 2.0 or less.

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 the improvement of adhesion, and if it exceeds 5.0 μm, the wear resistance of the entire coating is deteriorated. To prevent damage, the thickness is set to 0.05 μm or more and 5.0 μm or less. The components such as Y added to improve the oxidation resistance are 0.0
If it is 5 atomic% or less, the effect on the oxidation resistance is small, and if Ti is replaced to exceed 60 atomic%, the wear resistance is deteriorated, so the content was made 0.05 to 60 atomic%.

[0011]

【Example】

Example 1 Under the conditions shown in Table 1 using a small arc ion plating device, a composite nitride of Ti and Al and carbonitride were mixed with
The coating was performed so as to have a thickness of μm.

[0012]

[Table 1]

Table 1 shows the possible cutting distances until the average flank wear width becomes 0.20 mm when the obtained end mill is milled under the following conditions. As is clear from Table 1, by orienting the film on the (111) plane, in the extremely normal wear mode, a long life can be achieved in end mill cutting.

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 thickness of the composite nitride layer of Ti and Al was unified to 3 μm. The same cutting evaluation as in Example 1 was performed to evaluate the tool life. The results are also shown in Table 2. Al ₂ O ₃ was formed by plasma CVD.

[0015]

[Table 2]

From Table 2, I (200) / I of 2.5 or more
It is recognized that the tool life is further improved by providing the alloy of the present invention having the (111) value with the intermediate layer or the outermost layer. The TiN of the intermediate layer in Table 2 is
I (200) / I (111) was set to 1.0.

Example 3 Using the experimental apparatus used in Example 1, (TiAlX) N films having various compositions shown in Table 3 were prepared. 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.

[0018]

[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.

[0020]

By applying the present invention, the hardness of the coating is improved and a long tool life can be obtained in the cutting of high hardness steel exceeding Rockwell hardness 50 (C scale).
It became so.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuyuki Kubota 2 13-13 Shinizumi, Narita-shi, Chiba Hitachi Tool Co., Ltd. Narita factory (56) Reference JP 9-170068 (JP, A) Patent 3016703 ( JP, B2) Kobe Steel Technical Report Vol. 43, No. 3, pp. 23-26 (1993) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 14/00-14/58 C23C 16/00 -16/56 B23B 27/14 B23P 15/28

Claims (5)

(57) [Claims] 1. A substrate used for cutting high hardness steel exceeding HRC50, wherein the substrate has a thin sharp edge.
Then, in an end mill coated with a composite nitride of Ti and Al, a carbonitride, or a carbide, the diffraction intensity of the (111) plane in the X-ray diffraction of the coating layer protecting the substrate is I (11).
1), when the diffraction intensity of the (200) plane is I (200), the value of I (200) / I (111) is 2.0 or less. 2. The surface-coated end mill according to claim 1, wherein Ti having a film thickness of 0.05 μm or more and 5.0 μm or less is provided between the substrate and the Ti / Al composite nitride, carbonitride, or carbide coating layer. A surface-coated end mill using the above-mentioned nitride and carbonitride as an intermediate layer. 3. The surface-coated end mill according to claim 1 or 2, wherein a Ti / Al composite nitride, carbonitride, or carbide layer is further coated with Ti carbonitride, carbonitride, or Ti / A.
l complex oxynitride, carbonitride, carbonate, oxide, A
A surface-coated end mill characterized by being coated with one single layer or two or more multiple layers of the oxide of 1. 4. The surface-coated end mill of any of claims 1 to 3, a composite nitride of Ti and Al,
Part of Ti in the carbonitride and carbide layers is 0.0 with respect to Ti.
Zr, Hf, Y in the range of 5 at% to 60 at%
A surface-coated end mill characterized by being replaced with one or more of Si, W and Cr. 5. The surface-coated end mill of any of claims 1 to 4, the surface coating end mill, characterized in that the surface roughness of the rake face side of the end mill to 1μm or less.