JPH0569205A - Ceramic cutting tool - Google Patents

Abstract

PURPOSE:To provide a ceramic cutting tool which is essentially composed of alumina ceramic sintered body and can cut high hardness material efficiently and with a long life. CONSTITUTION:Base material is alumina ceramic sintered body which contains at least one kind of titanum carbide, nitride, carbo-nitride or carbo-nitro-oxide of 10-50 weight percent in the matrix of Al2O3. A ceramic cutting tool is composed of this base material and either (1) at least, one of the carbide, the nitride or the carbo-nitride of the alloy of Ti and Al provided on the surface of this base material, or (2) combination of, at least, one of the carbide, the nitride or the carbo-nitride of the alloy of Ti and Al provided on the base material and, at least, one of the carbide, the nitride or the carbo-nitride of Ti, and has a coating layer of 0.2-10mum in thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a long-life alumina-based ceramics cutting tool capable of cutting highly hard materials such as alloy tool steel with high efficiency.

[0002]

High hardness material such BACKGROUND ART alloy tool steel, 500 kgf / mm ² or more high-hardness material, especially 50 or more Rokkueru C hardness (H _R C) or the Vickers hardness (H _V), the machining is extremely difficult In particular, the cutting process is so difficult that it can hardly be cut with a normal cutting tool such as cemented carbide.

Conventionally, for cutting such a high hardness material, a cutting tool made of a cubic boron nitride (CBN) sintered body or an Al ₂ O ₃ -TiC ceramics sintered body called black ceramic is used as a starting material. A cutting tool made of an alumina (Al ₂ O ₃ ) based sintered body was used.

However, since the CBN sintered body cutting tool requires ultrahigh pressure and ultrahigh temperature in its manufacturing process, its price is extremely higher than that of the cemented carbide cutting tool, and the shape of the tool that can be produced is different. However, there were drawbacks such as significant restrictions. On the other hand, black ceramic cutting tools are inexpensive and have a great deal of freedom in tool shape, but lack of toughness is noticeable when actually cutting high hardness materials, and chipping and flaking are likely to occur, so stable cutting is possible. The reality was that it was difficult to do.

As described above, it is considered that it becomes difficult to cut a high hardness material because the back force component among the three force components of the cutting resistance becomes very large. Therefore, although it is inexpensive, there is concern about the fracture resistance. Regarding an alumina-based ceramics sintered body cutting tool such as black ceramics, it is necessary to improve and improve its strength and toughness.

[0006] Therefore, conventionally, Al for Al ₂ O ₃ based ceramic sintered body such as ₂ O ₃ -TiC based, the HIP treatment Al ₂ O ₃ process for reducing the particle size of the crystal particles and TiC particles (KOKOKU 1-
No. 22223), or Nb, V, Zr, Ta, Hf, etc. in the form of a metal or an oxide to uniformly and finely disperse TiC to improve the strength of the sintered body (Japanese Patent Publication No. 63-35587). Issue). By these methods, it became possible to improve the strength and hardness by eliminating the pores existing in the sintered body, but in the cutting of high hardness material where the back force becomes particularly large, its strength and wear resistance I couldn't say that she had enough sex.

In addition to the above method, there is also adopted a method of reducing cutting resistance by lapping a rake face of a cutting tool to facilitate discharge of chips. Also, a method of reducing cutting resistance by providing a breaker or the like is naturally conceivable, but ceramic cutting tools have not been widely used because of concerns about strength and manufacturing restrictions.

[0008]

In view of the above conventional circumstances, the present invention essentially consists of a low-priced alumina-based ceramics sintered body such as Al ₂ O ₃ —TiC system, in particular, H _R C of 50 or more. Alternatively, it is an object of the present invention to provide a ceramics cutting tool capable of cutting a high hardness material of 500 kgf / mm ² or more with H _V with high efficiency and long life.

[0009]

In order to achieve the above object, in the ceramic cutting tool of the present invention: Al ₂ O ₃
A matrix of an alumina-based ceramics sintered body containing at least one of 10 to 50% by weight of Ti carbide, nitride, carbonitride or carbonitride oxide in a matrix of (1) A coating layer having a total film thickness of 0.2 to 10 μm made of at least one kind of carbide and nitride or carbonitride of Ti and Al alloy provided on the surface, or (2) provided on the surface of the base material T
A coating layer having a total film thickness of 0.2 to 10 μm, which is composed of a combination of at least one kind of carbide, nitride or carbonitride of an alloy of i and Al and at least one kind of carbide, nitride or carbonitride of Ti. It is characterized by having.

In the present invention, the carbide, nitride or carbonitride of an alloy of Ti and Al means the chemical formula shown below.

Embedded image A compound represented by (Ti _1-x Al _x ) (C _1-y N _y ), (wherein 0 <x <1 and 0 ≦ y ≦ 1).

[0011]

In the present invention, the combination of the above-mentioned specific base material and the coating layer causes the surface residual compressive stress in the coating layer due to the difference in the coefficient of thermal expansion, which is the base material of the Al ₂ O ₃ system ceramics sintered body. Improves toughness.

In particular, the coating layer made of a carbide, nitride or carbonitride of an alloy of Ti and Al has the effect of improving the wear resistance of the cutting tool in addition to the effect of improving the toughness described above. The reason for this is not clear, but Al contained in the coating layer causes a partial chemical reaction due to the high temperature generated during cutting to generate Al ₂ O ₃ , and this Al ₂ O ₃ improves wear resistance. Conceivable.

Therefore, the ceramics cutting tool of the present invention has a high toughness and wear resistance as a cutting tool for high hardness material, especially for a high hardness material having an H _R C of 50 or more or an H _V of 500 kgf / mm ² or more. Excellent in performance and does not have a conventional coating layer
It has a life several times longer than that of a ceramics cutting tool made of Al ₂ O ₃ —TiC ceramics sintered body, etc., and can perform stable cutting with high efficiency.

Further, as a coating layer, a carbide of an alloy of Ti and Al,
It was found that Ti carbide, nitride or carbonitride used in combination with nitride or carbonitride has excellent adhesion to the base metal, and TiN has excellent adhesion to the base metal. .. Therefore, the innermost layer of the coating layer that contacts the base metal is
By using the above, it is possible to obtain a coating layer having particularly excellent adhesion to the base material.

Further, Ti carbide, nitride or carbonitride is a carbide, nitride or carbonitride of an alloy of Ti and Al having a friction coefficient, or a conventional Al ₂ O ₃ − ground by a general method. Since it is smaller than the TiC ceramics sintered body, the inclusion of this in the coating layer improves the discharge of cutting chips and reduces the cutting resistance. Among the compounds that can form the coating layer, Ti
Since N has the smallest friction coefficient, if the outermost layer of the coating layer is TiN, the effect of reducing the cutting resistance during cutting of high hardness material is great.

In the ceramic cutting tool of the present invention, it is effective to reduce the cutting resistance by setting the surface roughness at least in the vicinity of the cutting edge to 0.2 S or less, which further reduces the cutting resistance and results in long-term use. It has been found that a usable cutting tool is obtained. In order to improve the surface roughness, methods such as surface polishing using diamond paste with diamond abrasive grains can be used.

The alumina-based ceramics sintered body as a base material contains at least one compound selected from Ti carbide, nitride, carbonitride or carbonitride in a matrix of Al ₂ O _3. Is. These Al ₂ O ₃ based ceramics sintered bodies have high strength and hardness, and have been conventionally used as cutting tools for high hardness materials. However, in order to use as the base material of the cutting tool of the present invention, Ti
Addition amount of carbide, nitride, carbonitride or carbonitride is 10
If it is less than 50% by weight, the strength and hardness of the sintered body will be low, and if it exceeds 50% by weight, the sinterability will be poor, so the range is 10 to 50% by weight.

The above-mentioned alumina-based ceramics sintered body as a base material is known, and is obtained, for example, by sintering a raw material powder composition mixed at a predetermined ratio at a temperature of about 1500 to 1900 ° C. A hot pressing method is preferable as the sintering method, but a normal sintering method or a HIP method can also be adopted.
Further, it is natural that a known sintering aid such as NiO, Y ₂ O ₃ , MgO or the like may be used as an additive at the time of sintering.

The coating layer provided on the surface of the base material is a single layer or multiple layers made of carbide, nitride or carbonitride of an alloy of Al and Ti, or a carbide, nitride or carbonitride of these and Ti. In any case, the total film thickness of the coating layer is in the range of 0.2 to 10 μm. The reason is that if the film thickness is less than 0.2 μm, the effect of improving toughness and wear resistance is small, and if it exceeds 10 μm, the toughness of the coating layer itself decreases. In addition, even if a small amount of 4A, 5A, 6A group elements or iron-based metal elements are contained in the carbide, nitride or carbonitride of the Al-Ti alloy of the coating layer, it will change to the above-mentioned superiority of the coating layer. There is no.

For forming the coating layer, a known physical or chemical thin film forming method such as PVD method or CVD method can be used. When coating a carbide, a nitride or a carbonitride of an alloy of Al and Ti by the PVD method, a target of an alloy of Ti and Al may be used, or a target of Ti and Al may be provided separately. ..

[0021]

Example: Al ₂ O ₃ powder with an average particle size of 0.4 μm has an average particle size of 1.0 μ
After mixing 30% by volume of TiC powder of m, filling the mixed powder in a graphite die, hot press-sintering at 1650 ° C for 1 hour under a pressure of 30 MPa in argon gas.
An Al ₂ O ₃ —TiC sintered body having a cutting tip shape of 120408 was manufactured.

The obtained Al ₂ O ₃ -TiC sintered body is used as a base material, and the coating layers shown in Table 1 are formed on the surface of the base material by the ordinary PVD method. 12 was a comparative example. Also, without forming a coating layer, Al
Cutting tip 13 consisting only of ₂ O ₃ -TiC sintered body (comparative example)
I also prepared.

Next, using each of the cutting tips 1 to 13, a cutting test was conducted under the following conditions. Cutting conditions:.. Workpiece ... SKD11 (H _R C 60) Cutting speed ... 100 m / min feed Ri ... 0.1 mm / rev cuts ... 1.0 mm Holder ... FN11R44A switching cutting oil ... dry cutting time ... 10min.

In the above cutting test, the peeling state of the coating layer of each cutting tip was observed, and the flank wear width of each cutting tip after the test was measured, and the cutting test results are also shown in Table 1.

[0025]

[Table 1] Cutting covering layer structure and film thickness Total film thickness Cutting test resultsTip (Inner layer → outer layer) (μm) (Μm) Flank wear width  1 Ti₃AlC (4.0) 4.0 0.08mm 2 TiAlN (4.0) 4.0 0.07mm 3 Ti₃AlCN (4.5) 4.5 0.07mm 4 Ti₃AlN (4.5) 4.5 0.06mm 5 TiAlN (1.5) → TiAlCN (2.5) 4.0 0.06mm 6 Ti₃AlC (2.0) → TiAlN (1.5) 3.5 0.06mm 7 TiN (0.5) → Ti₃AlCN (3.5) 4.0 0.04mm 8 TiN (0.5) → Ti₃AlC (2.0) → TiAlN (1.5) 4.0 0.04mm 9 TiN (1.0) → TiAlN (3.0) → TiN (0.5) 4.5 0.04mm 10 TiN (1.0) → Ti₃AlCN (3.0) → TiN (0.5) * 4.5 0.03mm 11 (Ti-6wt% Al-4wt% V) N 4.0 0.09mm 12 TiN (3.0) 3.0 0.12mm 13 No coating layer − Defect in 3 minutes (Note) TiAl Is 50at% Ti-50at% Al alloy, Ti₃Al is 75 at
% Ti-25 at% alloy. Also, chips marked with *
Use a diamond abrasive with a grain size of 30-40 μm near the cutting edge.
Use diamond paste to improve surface roughness up to 0.2S.
I let you go up.

[0026]

According to the present invention, a high hardness material such as an alloy tool steel, especially a high hardness material having an H _R C of 50 or more or an H _V of 500 Kgf / mm ² or more can be cut with high efficiency and long life. It is possible to provide a low-cost ceramic cutting tool that has high toughness and excellent wear resistance.

Claims (5)

[Claims] 1. An Al ₂ O ₃ matrix containing 10 to 50% by weight.
And a base material of an alumina-based ceramics sintered body containing at least one of Ti carbide, nitride, carbonitride or carbonitride oxide, and a carbide of Ti and Al alloy provided on the surface of the base material, Film thickness consisting of at least one of nitride or carbonitride
A ceramic cutting tool having a coating layer of 0.2 to 10 μm. _2. 10 to 50% by weight in a matrix of Al ₂ O ₃
And a base material of an alumina-based ceramics sintered body containing at least one of Ti carbide, nitride, carbonitride or carbonitride oxide, and a carbide of Ti and Al alloy provided on the surface of the base material, A ceramic cutting comprising a coating layer having a total film thickness of 0.2 to 10 μm, which is made of a combination of at least one kind of nitride or carbonitride and at least one kind of carbide, nitride or carbonitride of Ti. tool. 3. The ceramic cutting tool according to claim 2, wherein the innermost layer of the coating layer is TiN. 4. The ceramic cutting tool according to claim 2, wherein the outermost layer of the coating layer is TiN. 5. The ceramic cutting tool according to claim 1, wherein the surface roughness at least in the vicinity of the cutting edge is 0.2 S or less.