JP2000107906A - Coated head tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the peeling of a film by thinly covering the innermost layer making contact with a base body with a TiN series having good adhesion with the base body, and applying a carbonitride layer thereon. SOLUTION: Since TiN is hard with a hardness of HV 2000 or more, it has the function of moderating the stress of a film, and V (CN) or (TiN) (CN) also has the function of moderating the stress with a proper hardness and is highly adhesive to TiN or (TiAl) N, (TiAlV) (CN). The main purpose of the TiN of the layer making contact with the base body is the adhesion with the base body, and the thickness is set to 0.1-5 μm. With respect to the V (CN) or (TiV) (CN) of the hard film, the proper thickness is 0.1-5 μm. With thickness <0.1 μm, the function as the stress moderating layer is insufficient, and with thickness >5 μm, a plastic flow is often caused according to the cutting condition to remove the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated hard tool having a hard film having particularly excellent adhesion and lubricity, and is a member which is subjected to severe friction and wear, such as various cutting tools, molds, jigs, and machine components. To improve the performance.

[0002]

2. Description of the Related Art TiN, Ti
Coatings such as CN have been used widely and generally, but as the conditions of use have increased, (TiAl) N coatings having more excellent wear resistance and oxidation resistance have come to be used in many cases.
However, recently, in addition to the tendency for cutting speed to be further increased, dry cutting has become more important in the environment, lowering the friction between the tool surface and the workpiece, improving self-lubricating properties, and improving the coating quality. It has become extremely important to improve the resistance to peeling, that is, the adhesion of the coating to the substrate.

[0003]

According to the study of the present inventors, the current TiAlN film has a considerably large friction coefficient with steel of about 0.4 and generates a large amount of heat during cutting. It was confirmed that the drying process had a limit. Therefore, it is considered that improving the lubricating properties of the film and reducing the generation of heat by cutting are indispensable technologies that enable high-speed cutting and dry cutting. In addition, it is most preferable to increase the thickness of the hard coating to increase the wear resistance of the tool and increase the tool life, but the increase in the thickness of the coating causes a large residual stress at the interface between the coating and the substrate, Causes peeling of the film. Therefore, it is considered that the performance is further improved by providing a buffer film having good adhesion between the hard film and the substrate and absorbing the residual stress.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention aims at improving the performance by improving the adhesion of the film and stabilizing the peeling resistance of the film itself. An intermediate layer for relaxing the stress is provided, and the innermost layer in contact with the substrate is coated with a thin TiN-based material with good adhesion to the substrate, and a slightly soft carbonitride layer is coated on it to relieve the internal stress of the film. Is what you do. Further, in order to cope with high-speed cutting and dry cutting, it is effective to increase the lubricity of the coating itself and to suppress an increase in the temperature of the cutting edge.

[0005]

[Function] Since the hardness of TiN is as high as HV2200 or more,
V (CN) or (TiV) (CN) has an appropriate hardness and has a function of relaxing stress, and also has a function of relaxing stress, and TiN, (TiAl) N, (TiAl).
V) It was found that the adhesiveness to (CN) was good. For the wear resistance and heat resistance of the cutting edge, (TiAl) N, (TiAl) (CN) or (TiAlV) (CN) with lubricity taken into account is used. next,
The outer layer is coated with V (CN) having excellent lubricity. V contained in the outer layer coating is oxidized during cutting to form a low-melting oxide layer, which provides a lubricating effect and prevents welding of the work material to protect the hard coating.

Next, reasons for limiting numerical values according to the present invention will be described. Since the main purpose of TiN of the layer in contact with the substrate is to mainly adhere to the substrate, the thickness of the layer may be as small as 0.1 to 5 μm, but is preferably 2 μm or less. V (CN) or (TiV) of hard coating
(CN) has an appropriate thickness. Preferably it is 0.1 to 3 μm. If the thickness is 0.1 μm or less, the function as a stress relaxation layer is not sufficient, and if it is 3 μm or more, depending on the cutting conditions, plastic flow may occur and the film may be removed. The ratio of C to N in (CN) is appropriately adjusted depending on the thickness of the outer layer and cutting conditions. C / N
As the value increases, the material becomes harder and the function of stress relaxation decreases. Similarly, the higher the value of Ti / V in (TiV) (CN), the harder it becomes. (TiV) (CN) to (Ti _1-x
V _x ) (C _1-y N _y ), where x = 0.2-1.
0 and y = about 0.3 to 1.0 are good.

The outer layer (TiA) to provide abrasion resistance
1) It is desirable that (CN) or (TiAlV) (CN) be as thick as possible. If the thickness is 0.5 μm or less, the wear resistance is insufficient.
In consideration of the upper limit thickness of the hard layer,
m. V (CN) of the outer layer is to provide lubricity. If the thickness is less than 0.1 μm, the effect is not sufficient.
If the thickness is 2 μm or more, the effect is not increased, so the upper limit is set to 2 μm. When V (CN) is expressed as V (C _z N _1-z ), z = 0 to z
0.5 is preferred. In (CN), the greater the amount of N, the better the lubricity.

[0008] In the constitution of the present invention, the wear resistance of the film,
In order to sufficiently exhibit peel resistance, the hardness of the film needs to be in the following order. Outer layer {TiAl (CN), TiAlV (CN)}> Inner layer {TiN}> Hard layer {V (CN), TiV (CN)} Hereinafter, the present invention will be described with reference to examples.

[0009]

EXAMPLES Coatings of the present invention and comparative examples were made by using a small-sized arc ion plating apparatus under the conditions shown in Table 1 to produce prototype coated carbide end mills. The composition of the film is Ti
The adjustment was performed using an Al alloy target, a Ti-V target, a pure Ti, and a pure V target.

[0010]

[Table 1]

A cutting test was carried out under the following cutting conditions using a prototype end mill, and cutting was performed until breakage occurred. The cutting length at the time when the breakage occurred is also shown in Table 1. Cutting specifications are
Work material SK using end mill (φ8mm, 6 blades)
D11 (hardness HRC60), cutting speed 150m / mi
n, feed amount 0.06 mm / tooth, cutting amount 12 mm x
0.2 mm, without cutting oil.

From Table 1, it can be seen that the case where the outer layer is coated with V (CN) has a very good result with a low cutting edge temperature of 630 to 650 ° C. and a cutting length of about 50 m during cutting. TiAl containing V in hard coating layer without V (CN) film as outer layer
Those coated with V (CN) have a relatively low cutting edge temperature and a long cutting length of about 40 m. When there is no V (CN) or TiAlV (CN) in the inner layer, which is the internal stress relaxation layer of the coating, the effect on the cutting edge temperature is small, but the cutting length is slightly reduced. In particular, when the thickness of the layer is large as in the example of the sample No. 13, the cutting length is remarkably shortened due to the peeling of the film.

In order to demonstrate the effectiveness of the present invention with a drill, a cemented carbide drill was manufactured by the same manufacturing method as in the above example, and the cutting performance was compared. Drilling specifications are 8mm in diameter.
Drilling 24mm deep using a drill
CM440, cutting speed 80m / min, feed amount 0.2m
m / rev, using water-soluble cutting oil. The cutting performance was compared by the number of holes until breakage. Second test result
It is shown in the table. The sample numbers of the drills having the same manufacturing method as those in Table 1 were the same as those of the end mills in Table 1.

[0014]

[Table 2]

Table 2 shows that the tool life is increased by coating the outer layer with a V (CN) film. Further, even when the outer layer does not have a V (CN) film, it can be seen that the use of a (TiAlV) (CN) layer containing V in the hard coating layer causes a relatively small reduction in life. This is presumably because if a compound layer containing V is present in the outer layer, a low-melting V oxide is generated during cutting, and the lubricating effect reduces the cutting edge temperature, resulting in an extended drill life. V (CN) of outer layer
Alternatively, when there is no (TiV) (CN), the life is relatively shorter than when there is. In particular, V (C
N) is not coated, or when V (CN) is not added to the outer layer as in Sample No. 22 and the hard coating layer is TiAlN containing no V, the decrease is large. In the case where the thickness of the hard coating layer of the sample No. 26 of the comparative example is increased to 10 μm, the drill life is greatly reduced. Observation of the cutting edge after the service life revealed that the cutting edge had been locally largely hollowed out due to peeling of the coating, and that cutting was impossible. The presence of the inner layer of the stress relaxation layer has no direct effect on the wear of the cutting edge, but suppresses local peeling of the film.

[0016]

By applying the present invention, the peeling resistance of the coating is improved by relaxing the internal stress of the coating, and the synergistic effect of lowering the cutting edge temperature during cutting by the lubricating effect of the coating results in a severe cutting condition. The present invention can be applied not only to cemented carbide tools but also to coated hard tools such as high-speed tool steel and TiCN-based cermet.

Claims (5)

[Claims] 1. A coated hard alloy coated with a hard coating composed of a nitride, carbonitride or carbonitride containing Ti and Al as main components, wherein a TiN film is provided as an inner layer between the hard coating and the coated substrate. V is applied to the outer layer of the hard coating.
A coated hard tool coated with a (CN) or (TiV) (CN) film. 2. The coated hard tool according to claim 1, wherein
The coating, wherein the thickness of the hard coating is 0.5 to 5 μm, the thickness of the inner TiN film in contact with the substrate is 0.1 to 5 μm, and the thickness of the outer layer is 0.1 to 3 μm. Hard tool. 3. The coated hard tool according to claim 1, wherein said hard coating is made of (TiAl) (CN) or (Ti).
A coated hard tool made of AlV) (CN). 4. The coated hard tool according to claim 1, wherein the outer layer is V (CN). 5. The coated hard tool according to claim 1, wherein a thickness of the V (CN) film of the outer layer is 0.1 to 2 μm.
m. A coated hard tool characterized in that m.