KR102638088B1 - Cutting tools with hard coating - Google Patents

Abstract

The present invention relates to a cutting tool in which a hard film is formed on a hard base material such as cemented carbide, cermet, or CBN.
The cutting tool according to the present invention is a cutting tool including a hard base material and a hard film formed on the hard base material. The hard film has a single layer or a multi-layer structure of two or more layers, and the surface layer is Ti _a Al _b Me _c. C _{1- x N} (one or more selected from Si, B and S), the composition of the cutting edge of the cutting tool is 0.6≤a≤0.9, 0.1≤b≤0.3, 0≤c≤0.1, and the clearance surface of the cutting tool is It is characterized in that the central composition is 0.2≤a≤0.55, 0.45≤b≤0.7, and 0≤c≤0.1.

Description

Cutting tools with hard coating {CUTTING TOOLS WITH HARD COATING}

The present invention relates to a hard film formed on hard base materials such as cemented carbide, cermet, ceramic, and cubic boron nitride used in cutting tools, and more specifically, by controlling the composition of the hard film formed on the cutting tool differently for each part. It relates to cutting tools with improved service life.

Cutting tools require various properties such as wear resistance against friction with the workpiece, lubrication, impact resistance, and oxidation resistance. To this end, a technology for forming a hard film made of various ceramics on a cutting tool is being adopted to improve the lifespan of the cutting tool.

TiAlN-based thin films made of nitrides of Ti and Al show a tendency for Pugh's coefficient to decrease as the Al content decreases, and have a value of 0.7 or less when the Al content is 30 at% or less. On the other hand, the hardness of TiAlN-based thin films tends to increase as the Al content increases, and especially when the Al content is more than 45%, the hardness approaches the saturation point.

Meanwhile, in the case of cutting tools, for example, it is required for the cutting edge, which is subject to continuous impact, and the rake face and/or flank face, where friction with chips occurs continuously. The properties of the hard film may vary.

Japanese Patent Publication No. 5066301

The object of the present invention is to provide a hard coating for cutting tools that has improved wear resistance and chipping resistance compared to conventional hard coatings.

The present invention is a cutting tool comprising a hard base material and a hard film formed on the hard base material, wherein the hard film is made of a single layer or a multi-layer structure of two or more layers, and the surface layer is Ti _a Al _b Me _c C _{1-x N _} S), the composition of the edge portion of the cutting tool is 0.6≤a≤0.9, 0.1≤b≤0.3, 0≤c≤0.1, and the composition of the central portion of the relief surface of the cutting tool is 0.2 A cutting tool with ≤a≤0.55, 0.45≤b≤0.7, and 0≤c≤0.1 is provided.

Additionally, the total thickness of the hard film may be 0.5 to 10 ㎛, and the thickness of the surface layer may be 0.1 to 3 ㎛.

Additionally, in the surface layer, C _Al /R _Al , which is the ratio of the Al atomic ratio (C _Al ) in the center of the relief surface to the Al atomic ratio (R Al ) in the edge portion, may be 1.5 to ₇ .

Additionally, in the surface layer, the composition of the inclined surface 500㎛ away from the cutting edge may be 0.2≤a≤0.55, 0.45≤b≤0.7, and 0≤c≤0.1.

The cutting tool according to the present invention improves the chipping resistance of the cutting edge where continuous impact is applied during cutting, and improves the wear resistance of the flank surface where chips and friction continuously occur, so that it is applied locally to the location area of the hard film. By ensuring optimal cutting performance, the life of the cutting tool can be extended.

Figure 1 is a diagram showing the center of the cutting edge, rake surface, relief surface, and relief surface of an insert-shaped cutting tool.
Figure 2 is a diagram showing the cutting edge and the center of the relief surface of a drill-shaped cutting tool.
Figure 3 schematically shows the state of Al content of a hard film according to an embodiment of the present invention.

Hereinafter, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Additionally, when a part is said to 'include' a certain component, this does not mean that other components are excluded, but that it can further include other components, unless specifically stated to the contrary.

The present invention is a cutting tool comprising a hard base material and a hard film formed on the hard base material.

[Hard base material]

The hard base material may be made of various types of materials used in cutting tools. For example, materials such as cemented carbide, cermet, ceramic, and cubic boron nitride may be used.

The hard base material may be molded to fit the shape required for the cutting tool, for example, it may be molded into an insert shape or a drill shape.

As shown in FIG. 1, the cutting tool formed into an insert shape is formed in a substantially rectangular parallelepiped shape and has a fastening hole formed in the center. In the drawing, the upper surface forms a rake face, the side surface in the drawing forms a flank face, the boundary between the rake face and the flank face forms a cutting edge, and the four corners form a nose part. do.

In the case of an insert-shaped cutting tool, the “center” of the relief surface refers to the point where the diagonals of the four corners constituting the relief surface intersect, as shown in FIG. 1.

As shown in Figure 2, the 'central part' of a cutting tool formed in the shape of a drill or endmill is the cutting edge of the blade that is 2 mm or more away from the base edge and the next cutting edge that meets when drawn in the perpendicular direction. It refers to the central part of the street.

[Hard membrane]

A hard film is a film formed on the hard base material.

In one embodiment of the present invention, the hard film is composed of a single layer or a multi-layer structure of two or more layers, and the surface layer is Ti _a Al _b Me _c C _1-x N _x O _y (0.5≤x≤ 1, 0≤y≤0.5, a, b, c, x, y is the atomic ratio, Me is one or more selected from group 4 elements, group 5 elements, group 6 elements of the periodic table, Si, B and S) The composition of the cutting edge of the cutting tool is 0.6≤a≤0.9, 0.1≤b≤0.3, 0≤c≤0.1, and the composition of the central portion of the relief surface of the cutting tool is 0.2≤a≤0.55, 0.45≤b≤ It is characterized by 0.7, 0≤c≤0.1.

In the present invention, the cutting edge area refers to a range within 50㎛ in the direction perpendicular to the cutting edge in the direction of the inclined surface and relief surface based on the cutting edge, and the center of the relief surface refers to the area between the center point and the center point of the relief surface. This refers to the range within a radius of 50㎛.

In the present invention, in the Ti _a Al _b Me _c C _{1- x N} It improves the chipping resistance of the cutting edge by providing toughness that can respond to applied impacts. In addition, in the Ti _a Al _b Me _c C _{1- x N} It improves the wear resistance of the relief surface that occurs due to In other words, the present invention adjusts the Al atomic ratio of the TiAlN-based film constituting the surface layer differently at the cutting edge and the relief surface to respond to the physical properties of the film that are locally preferentially required, thereby further extending the life of the cutting tool. get the effect

In addition, in the surface layer, C _Al /R _Al , which is the ratio of the Al atomic ratio (C Al ) in the center of the relief surface to the Al atomic ratio (R _Al ) in the edge portion, is preferably 1.5 to ₇ . The difference between the Al atomic ratio in the cutting edge and the Al atomic ratio in the center of the flank is at least greater than the above value range, which extends the overall cutting tool life through the local optimization effect of improving the chipping resistance of the cutting edge and improving the wear resistance of the flank. Because it is more desirable.

In addition, the thickness of the hard film is preferably 0.5 to 10㎛. If the thickness of the hard film is less than 0.5㎛, the effect of the hard film is not sufficient, and if it is more than 10㎛, the internal stress increases and the chipping resistance is rather poor. This is because it can deteriorate.

In addition, the thickness of the surface layer is preferably 0.5 to 10㎛. If the thickness of the surface layer, which is a TiAlN-based film, is less than 0.5㎛, the effect of the surface layer is not sufficient, and if it is more than 10㎛, internal stress increases, reducing chipping resistance. This is because it can actually deteriorate.

Additionally, in the inclined surface area more than 500㎛ away from the cutting edge, the surface layer may have a composition of 0.2≤a≤0.55, 0.45≤b≤0.7, and 0≤c≤0.1.

<Example>

In an embodiment of the present invention, two types of surface treatments (ion bombardment and physical vapor deposition (PVD)) are used on the surface of the base material made of cemented carbide to form a single layer or two arc ion plating methods. A hard film composed of more than one layer was formed.

Specifically, arc targets of Ti, Al, TiAl, AlTi, TiAlSi, and AlTiSi were used as targets for coating. The base material was washed with wet microblasting and ultrapure water, then dried and placed on the central axis on the rotary table in the coating furnace. It was installed along the circumference at a predetermined distance in the radial direction, and the initial vacuum pressure in the coating furnace was reduced to below 8.5×10 ^-5 Torr.

After heating to a temperature of 400 to 600°C, a bias voltage of -400 to -200 V is applied to the rotating base material on the rotary table under an Ar gas atmosphere, and an Ar ion bombard is applied for 30 to 90 minutes. Ion bombardment was performed. After that, a bias voltage of -1000 to -600V is applied, and an arc current of 70 to 150A is supplied to the arc target (either Ti or Cr) to perform metal (including semi-metal) ion bombardment for 1 to 20 minutes. ) was performed. Metal ion bombardment may be performed before performing Ar ion bombardment. The gas pressure for coating was maintained at 50 mTorr or less, preferably 40 mTorr or less, and a thin film with a single-layer or two-layer or more multi-layer structure was formed.

The thin film was formed using TiAl, AlCr, and TiAlSi targets under conditions of bias voltage of -100 to -30V, arc current of 100 to 150A, and N ₂ as a reaction gas injected at a pressure of 20 to 40 mtorr.

The second film was formed using TiAl, AlCr, and TiAlSi targets at a bias voltage of -100 to -30V, an arc current of 100 to 150A, and N ₂ as a reaction gas injected at a pressure of 20 to 40 mtorr.

The examples and comparative examples of the present invention were manufactured under the above-mentioned conditions, and basic information on the conditions and thickness of the corresponding hard film is shown in Table 1 below. Coating conditions may vary depending on equipment characteristics and conditions.

division inner layer surface layer target 1
(Composition fee) target 2
(Composition fee) thickness
(um) target
(Composition fee) bias
Voltage
(V) thickness
(um) Example 1 - - 0 TiAl(50:50) -400 3 Example 2 TiAl(50:50) AlCr(3:7) 5.7 TiAl(40:60) -450 One Example 3 AlCr(5:5) TiAl(67:33) 3.2 TiAlSi(5:4:1) -500 1.2 Example 4 - - 0 TiAl(50:50) -200 2.5 Example 5 TiAl(7:3) TiAlSi(7:2:1) 6.1 TiAl(33:67) -350 1.5 Example 6 - - 0 TiAl(2:8) -500 2.7 Example 7 AlCr(5:5) TiAlSi(5:4:1) 3.5 TIAl(3:7) -150 2.3 Comparative Example 1 TiAlSi(7:2:1) TiAl(7:3) 3.8 TiAl(2:8) -100 2.1 Comparative Example 2 TiAl(5:5) TiAl(6:4) 3 TiAlSi(5:4:1) -80 One Comparative Example 3 TiAl(50:50) AlCr(3:7) 4.6 TiAl(5:5) -60 1.8 Comparative Example 4 - - 0 TiAl(6:4) -50 2 Comparative Example 5 TiAl(8:2) TiAlSi(7:2:1) 4.4 TiAl(5:5) -120 1.3 Comparative Example 6 TiAl(5:5) - 2.5 TiAl(3:7) -80 3 Comparative Example 7 - - 0 TiAl(2:8) -40 2.1

The Al content of each part was measured for samples made according to the conditions in Table 1. The cross sections of the hard films of the examples and comparative examples according to Table 1 were analyzed at a magnification of 15,000 with a SEM (Scanning Electron Microscope) and the composition was analyzed with an EDS (Energy Dispersive Spectrometer), and the point where the relief surface of the cutting tool and the inclined surface meet as shown in Figure 1. is called the cutting edge R, the Al atomic ratio of the surface layer film of the cutting edge part is R _Al , the central point of the relief surface is C _Al , and the Al atomic ratio of the surface layer within 50㎛ around C is C _a . The results are shown in Table 2 below. (The Al content at this time is the content excluding non-metals.)

division R _Al (atomic ratio) C _Al (atomic ratio) Example 1 0.20 0.45 Example 2 0.28 0.62 Example 3 0.15 0.57 Example 4 0.25 0.40 Example 5 0.23 0.68 Example 6 0.12 0.57 Example 7 0.26 0.61 Comparative Example 1 0.58 0.70 Comparative Example 2 0.37 0.41 Comparative Example 3 0.43 0.62 Comparative Example 4 0.48 0.55 Comparative Example 5 0.25 0.37 Comparative Example 6 0.60 0.62 Comparative Example 7 0.25 0.85

In the case of the example, as a result of analysis by EDS, the Al content (atomic ratio) of the edge part of the surface layer satisfies 0.1<R _a ≤0.3, and the Al content (atomic ratio) of the center of the relief surface of the surface layer satisfies the range of 0.45≤C _a ≤0.7. You can check that it does. The wear resistance and chipping resistance of the hard film formed in this way were evaluated under the following conditions.

(1) Wear resistance evaluation

Work material: Carbon steel SM45C (300mm*200mm*100mm)

Sample model number: SNMX1206ANN-MM

Cutting speed: 250 m/min

Cutting feed: 0.2 mm/rev

Cutting depth: 2.0 mm

Coolant: Used

(2) Chipping resistance evaluation

Work material: Stainless steel SUS316 (300mm*200mm*100mm)

Sample model number: ADKT170608PESR-MF

Cutting speed: 90 m/min

Cutting feed: 0.25 mm/tooth

Cutting depth: 4mm

Coolant: Not used

The processing results evaluated under the two conditions as described above are shown in Table 3 below.

division SM45C machining results SUS316 processing results Processing length
(mm) Wear type Processing length
(mm) Wear type Example 1 4500 normal wear 2100 Wear/chipping Example 2 7500 normal wear 1800 Edge chipping Example 3 5200 normal wear 2500 Wear/chipping Example 4 4200 normal wear 2200 Wear/chipping Example 5 8100 normal wear 1800 Edge chipping Example 6 4200 normal wear 2400 Wear/chipping Example 7 6700 normal wear 2200 Wear/chipping Comparative Example 1 4500 Excessive wear 1300 Boundary chipping Comparative Example 2 3900 Excessive wear 1500 Wear/chipping Comparative Example 3 4800 Excessive wear 900 Chipping/breakage Comparative Example 4 2500 Excessive wear 1300 Wear/chipping Comparative Example 5 4700 Excessive wear 1100 Boundary chipping Comparative Example 6 4600 Excessive wear 1100 Boundary chipping Comparative Example 7 2100 normal wear 800 Wear/chipping

As shown in the cutting performance evaluation results, Examples 1 to 7 showed superior tool life than Comparative Examples 1 to 7. In particular, as the machining length of SM45C workpiece significantly increased, the machining length of SUS316 workpiece also showed improved results. Through this, it was confirmed that the lifespan of the tool was improved by supplementing wear resistance and chipping resistance through the difference in Al content between the cutting edge, rake surface, and relief surface.

Claims (4)

Hard base material,
A cutting tool comprising a hard film formed on the hard base material,
The hard film has a multi-layer structure of two or more layers,
The surface layer of the hard film composed of the multilayer structure is Ti _a Al _b Me _c C _1-x N _x O _y (0.5≤x≤1, 0≤y≤0.5, a, b, c, x, y are atomic ratios, Me consists of one or more elements selected from Group 4, Group 5, Group 6 elements of the periodic table, Si, B, and S,
The composition of the cutting edge of the cutting tool is 0.6≤a≤0.9, 0.1≤b≤0.3, 0≤c≤0.1, and the composition of the central portion of the relief surface of the cutting tool is 0.2≤a≤0.55, 0.45≤b≤0.7, 0 ≤c≤0.1,
A cutting tool wherein the total thickness of the hard film is 0.5 to 10 ㎛, and the thickness of the surface layer is 0.1 to 3 ㎛.
delete According to claim 1,
In the surface layer, C _Al /R _Al , which is the ratio of the Al atomic ratio (C _Al ) in the center of the relief surface to the Al atomic ratio (R _{Al )} in the cutting tool, is 1.5 to 7.
According to claim 1,
In the surface layer, the composition of the inclined surface 500㎛ away from the cutting edge is 0.2≤a≤0.55, 0.45≤b≤0.7, 0≤c≤0.1.