JP2018164951A - Surface-coated cutting tool - Google Patents

Abstract

The present invention provides a coated tool that improves adhesion between a hard coating layer and a lower layer and exhibits excellent chipping resistance in high-speed, high-feed intermittent machining of steel milling. A hard coating layer is formed on a surface of a tool base made of any one of a WC-based cemented carbide, a TiCN-based cermet, and a cBN sintered body, and an average layer thickness of 0.1 to 2.0 μm is formed on the surface of the tool base. On the TiN layer, an intermediate layer of TiCxN1-x (provided that 0.85 ≦ x ≦ 1.00) having an average layer thickness of 0.1 to 1.0 μm on the TiN layer, and on the intermediate layer, A surface cutting tool comprising an (AlyTi1-y) N (where 0.7 ≦ y ≦ 0.95) layer having an average layer thickness of 2.0 to 10.0 μm. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a long-life surface-coated cutting tool (hereinafter referred to as a coated tool) in which a hard coating layer exhibits excellent chipping resistance and adhesion to a substrate in high-speed, high-feed intermittent machining of steel milling. It is.

Conventionally, for the purpose of improving the cutting performance of cutting tools, tungsten carbide (hereinafter referred to as WC) based cemented carbide, titanium carbonitride (hereinafter referred to as TiCN) based cermet or cubic boron nitride (hereinafter referred to as cBN). ) A Ti-Al composite nitride layer or the like is deposited on the surface of a tool base composed of a base ultra-high pressure sintered body (hereinafter collectively referred to as a base) by a vapor deposition method as a hard coating layer. There are coated tools that are coated, and these are known to exhibit excellent wear resistance.
The conventional coated tool formed by coating the conventional Ti-Al based composite nitride layer, etc. is relatively excellent in wear resistance, but is likely to cause abnormal wear such as chipping when used under high-speed and high-feed cutting conditions. Various proposals have been made for improving the hard coating layer and improving the adhesion to the substrate.

For example, Patent Document 1 discloses that a portion composed of cubic crystals and a hexagonal crystal are used as an outermost coating layer on a TiC _a N _1-a (a = 0.4 to 0.6) layer deposited in a TiN binder phase. A cutting tool in which an Al _x Ti _1-x N (x = 0.8 to 0.99) layer in which a lamellar structure composed of a portion is present is described.

Further, for example, Patent Document 2 has a plurality of layers coated with a hard material and deposited by CVD, and the outer layer is Ti _1-x Al _x N, Ti _1-x Al _x C and / or Ti _{1. -x} Al _x consists CN (0.65 ≦ x ≦ 0.9) , has a compressive stress in the range this outer layer of 100~1100MPa, TiCN layer or _{the Al} 2 _{O 3} layer is disposed under the outer layer A cutting tool is described.

Special table 2015-509858 gazette Special table 2011-513594 gazette

In recent years, there is a strong demand for labor saving and energy saving in cutting, and it is desirable to perform high-speed and high-feed machining. For coated tools, chipping resistance, chipping resistance, peeling resistance, etc. Therefore, there is a demand for improved abnormal damage resistance and long life as a tool.

However, the coated tool described in Patent Document 1 has a low C concentration in the Al _x Ti _1-x N layer in which the lamellar structure coated at 800 to 830 ° C. and the TiCN layer adjacent to the lower layer are low, Under severe processing conditions such as high-speed and high-feed processing, the adhesion strength between the two layers becomes insufficient, and chipping may occur.

  Further, the coating tool described in Patent Document 2 has an outer layer deposition temperature of 700 to 900 ° C., but does not pay particular attention to the C concentration in the TiCN layer. Under the processing conditions, the adhesion strength between the lower layer is insufficient, and chipping may occur.

  Then, this invention improves the adhesiveness of a hard coating layer and a lower layer, and it aims at providing the coated tool which exhibits the outstanding chipping resistance in the high-speed, high-feed intermittent process of steel milling.

The inventor diffuses C in the TiCN layer into the TiAlN layer, which is a composite nitride layer of Al and Ti, so that the substrate and TiAlN (hereinafter also referred to as (Al _z Ti _1-z ) N) Based on the assumption that the adhesion with the layer is improved, as a result of intensive investigation focusing on the C concentration in addition to the film formation temperature,
Adjacent to the TiTi layer with an average layer thickness within a specific range and an increased C concentration, the TiN layer-TiCN layer-TiAlN layer, which is a hard coating layer, is firmly connected to the AlTiN layer, such as steel milling. The present inventors have newly found that the adhesion between the hard coating layer and the substrate is improved even in high-speed and high-feed intermittent processing, that is, chipping can be prevented.
The reason why the adhesion is improved at this stage is not clear, but it is assumed that the adhesion is improved by the mutual diffusion of C and N in the vicinity of the interface between the TiCN layer and the AlTiN layer with an increased C concentration. doing.

The present invention has been made based on the above findings,
“(1) In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base made of a WC-based cemented carbide, TiCN-based cermet, or cBN sintered body,
Hard coating layer
A TiN layer having an average layer thickness of 0.1 to 2.0 μm on the surface of the tool substrate,
An intermediate layer of TiC _x N _1-x (provided that 0.85 ≦ x ≦ 1.00) having an average layer thickness of 0.1 to 1.0 μm on the TiN layer; and
On the intermediate layer, an (Al _y Ti _1-y ) N (where 0.7 ≦ y ≦ 0.95) layer having an average layer thickness of 2.0 to 10.0 μm,
A surface cutting tool comprising:
(2) The cutting tool according to (1), wherein an Al ₂ O ₃ layer is provided on the (Al _y Ti _1-y ) N layer. "
It is.

  In the surface-coated tool of the present invention, the substrate and the hard coating layer, TiN layer-TiCN layer-TiAlN layer, are strong by adjoining the TiTi layer having an average layer thickness in a specific range and an increased C concentration adjacent to the AlTiN layer. Thus, even in high-speed and high-feed processing such as steel milling, there is a remarkable effect that the adhesion between the hard coating layer and the substrate is improved, that is, chipping can be prevented.

  Next, the hard coating layer of the surface-coated cutting tool of the present invention, that is, the hard coating will be described in more detail.

AlTiN layer The AlTiN layer of the present invention can be expressed as (Al _y Ti _1-y ) N (where 0.70 ≦ y ≦ 0.95) and is formed by vapor deposition using a CVD apparatus.
Here, the reason why the Al content ratio y with respect to the total amount of Al and Ti in (Al _y Ti _1-y ) N is 0.70 to 0.95 is that the average Al content ratio y is less than 0.70. In that case, the (Al _y Ti _1-y ) N layer is inferior in oxidation resistance, and when it is subjected to high-speed high-feed interrupted processing such as steel milling, the wear resistance is not sufficient. If the average content ratio y exceeds 0.95, the precipitation amount of hexagonal crystals inferior in hardness increases and the hardness decreases, so that the wear resistance decreases.
It is assumed that this AlTiN layer has C diffusing from the intermediate layer and N diffusing to the intermediate layer, but the C and N diffusion region is a small region at the interface in contact with the intermediate layer. Therefore, the composition of the AlTiN layer when viewed as a whole layer, can be expressed on the _{(Al y Ti 1-y)} N and facts.

The reason why the average film thickness of the (Al _y Ti _1-y ) N layer is set to 2.0 to 10.0 μm is that the average film thickness is less than 2.0 μm as a protective film during cutting. This is because when the thickness exceeds 10.0 μm, the thickness of the hard coating layer increases and chipping tends to occur.

TiC _x N _1-x layer as an intermediate layer The intermediate layer can be expressed as TiC _x N _1-x (where 0.85 ≦ x ≦ 1.00). Here, the reason for x = 0.85 to 1.00 is that when x is less than 0.85, sufficient adhesion strength between the TiCN layer and the TiAlN layer cannot be obtained, while x is 1. Since the value does not exceed 00, the upper limit of x is set to 1.00.

The average layer thickness of the _{TiC x N 1-x} layer is an intermediate layer is 0.1 to 1.0 [mu] m. The reason for this range is that if it is less than 0.1 μm, the adhesion strength between this upper layer and the TiAlN layer is not sufficient, and if it exceeds 1.0 μm, there is a risk of embrittlement due to the strength of the intermediate layer itself. This is because the entire thickness of the hard coating layer becomes thick and chipping is likely to occur.

TiN layer The TiN layer is for strengthening the bond between the substrate and the hard coating layer, and has an average layer thickness of 0.1 to 2.0 μm. The reason for this range is that if it is less than 0.1 μm, the adhesion to the substrate is insufficient, and if it exceeds 2.0 μm, the entire thickness of the hard coating layer becomes so thick that chipping tends to occur.

Al ₂ O ₃ layer In the present invention, an Al ₂ O ₃ layer may be provided on the TiAlN layer. By providing the Al ₂ O ₃ layer, the wear resistance of the hard coating layer is further improved.

Manufacturing Method of Hard Coating Layer The hard coating layer of the coated tool of the present invention can be manufactured using, for example, the following gas composition and reaction atmosphere using an ordinary CVD apparatus. As the coating of the Al ₂ O ₃ layer, a known one may be adopted as appropriate. Note that “%” below means “capacity%”.

TiN coating layer reaction atmosphere temperature: 700-900 ° C
Reaction atmosphere pressure: 4.0 to 5.0 kPa
Reaction _{gas: TiCl 4: 12.0~18.0%, N} 2: 15.0~25.0%, H 2: remainder

Intermediate layer TiC _x N _1-x (however, 0.85 ≦ x ≦ 1.00)
Reaction atmosphere temperature: 700-900 ° C
Reaction atmosphere pressure: 5.0 to 6.0 kPa
Reaction _{gas: TiCl 4: 11.0~14.5%, CH} 4: 9.0~16.5%, N 2: 0~3.0, H 2: remainder

AlTiN layer _{(Al y Ti 1-y)} N ( where, 0.70 ≦ y ≦ 0.95)
Reaction atmosphere temperature: 700-900 ° C
Reaction atmosphere pressure: 4-5 kPa
Gas Group _{A NH 3: 0.8~1.6%, H} 2: 45~55%
Gas group B AlCl ₃ : 0.5 to 0.7%, TiCl ₄ : 0.1 to 0.3%, N ₂ : 0.0 to 10%, H ₂ : remaining supply cycle: 1 to 5 seconds
Gas supply time per cycle: 0.15 to 0.25 seconds Phase difference between supply of gas group A and supply of gas group B: 0.10 to 0.20 seconds

Next, the coated tool of this invention is demonstrated by an Example.
In the following examples, the case where a WC-based cemented carbide is used as the tool base will be described. However, the same applies when a TiCN-based cermet or cBN-based cemented carbide is used as the tool base.

As raw material powders, WC powder, TiC powder, TaC powder, NbC powder, Cr ₃ C ₂ powder, and Co powder all having an average particle diameter of 1 to 3 μm are prepared, and these raw material powders are shown in Table 1. After blending into the blending composition, adding wax, ball mill mixing in acetone for 24 hours, drying under reduced pressure, press-molding into a compact of a predetermined shape at a pressure of 98 MPa, and this compact in a vacuum of 5 Pa. Vacuum sintering is performed at a predetermined temperature within a range of 1370 to 1470 ° C. for 1 hour, and after sintering, bases A to C made of WC-base cemented carbide having an ISO standard SEEN1203AFSN insert shape are manufactured. did.

Next, the tool 1-10 of this invention and the comparative tools 1-10 were formed into a film on the surface of these tool base | substrates AC by the film-forming conditions described in Tables 2-6 using a normal CVD apparatus. In the coated tools 7 and 9 of the present invention and the comparative coated tools 7 and 9, an Al ₂ O ₃ layer was formed on the (Al _y Ti _1-y ) N layer.
Table 7 shows the composition of each layer of the present invention tools 1 to 10 and the comparative tools 1 to 10 and the average layer thickness of each layer.

  Here, the cross section in the film thickness direction is referred to as a vertical cross section, and the average layer thickness of each layer is an average value obtained by observing the vertical cross section at a plurality of locations with an SEM.

  The composition of each layer was analyzed using an electron probe microanalyzer (EPMA) or a scanning Auger spectrometer (AES). The composition analysis by EPMA or AES was performed at the center position in the film thickness direction.

Next, the following milling test was carried out in a state where the inventive tools 1 to 10 and the comparative tools 1 to 10 were all clamped to the tool steel cutter tip portion having a cutter diameter of 125 mm by a fixing jig.
Cutting test: Dry high-speed face milling, center cutting,
Work material: JIS / SCM440 block material with a width of 100 mm and a length of 400 mm,
Cutting speed: 420 m / min,
Cutting depth: 2.2 mm,
Single blade feed amount: 0.40 mm / tooth,
Cutting time: 15 minutes,
Table 8 shows the results of the processing test.

From the results shown in Table 8, the inventive tools 1 to 10 are TiN layers having an average layer thickness of 0.1 to 2.0 μm, and TiC _x having an average layer thickness of 0.1 to 1.0 μm on the TiN layer. An intermediate layer having N _1-x (0.85 ≦ x ≦ 1.00) is present, and (Al _y Ti _1-y ) having an average layer thickness of 2.0 to 10.0 μm is formed on the intermediate layer. N (however, 0.70 ≦ y ≦ 0.95) layer, that is, by adhering a TiCN layer with an increased C concentration adjacent to the AlTiN layer, excellent hard film adhesion in high-speed milling of steel Demonstrates chipping resistance.
On the other hand, since all of the comparative tools 1 to 10 are not adjacent to the AlTiN layer and the TiCN layer with the C layer having a predetermined average layer thickness defined in the present invention is increased, abnormal damage such as chipping and peeling occurs. In addition, the service life is reached in a relatively short time.

The coated tool of the present invention can be used as a coated tool for various work materials as well as high-speed intermittent machining such as high-speed milling of steel, and exhibits excellent wear resistance over a long period of use. Therefore, it is possible to satisfactorily cope with high performance of the cutting device, labor saving and energy saving of the cutting process, and further cost reduction.

Claims (2)

In a surface-coated cutting tool in which a hard coating layer is provided on the surface of a tool base made of any of a WC-based cemented carbide, a TiCN-based cermet, or a cBN sintered body,
Hard coating layer
A TiN layer having an average layer thickness of 0.1 to 2.0 μm on the surface of the tool substrate,
An intermediate layer of TiC _x N _1-x (provided that 0.85 ≦ x ≦ 1.00) having an average layer thickness of 0.1 to 1.0 μm on the TiN layer; and
On the intermediate layer, an (Al _y Ti _1-y ) N (where 0.7 ≦ y ≦ 0.95) layer having an average layer thickness of 2.0 to 10.0 μm,
A surface cutting tool comprising: Cutting tool according to claim 1 having _{the Al} 2 _{O 3} layer on top of the _{(Al y Ti 1-y)} N layer.
It is.