JPH05345976A - Cutting tool made of surface coated titanium carbonitride-based cermet excellent in chipping resistance - Google Patents

Abstract

PURPOSE:To improve the chipping resistance of a cermet cutting tool by specifying the structures and layer thickness of hard coated multiple layers formed on the surface of a cermet substrate. CONSTITUTION:Coated layers formed on the surface of a TiC.N-based cermet substrate are formed of hard layers in which the average layer thickness is regulated to 2 to 20mum, and they are constituted of multiple layers of >= two kinds among the borides, carbides, nitrides and oxides of Ti, Al, Zr and Hf as well as the solid solution of >= two kinds of them. Then, it is constituted of an inside layer group with 0.5 to 5mum average layer thickness having a superfine-grained structure of <=0.05mum average grain size and an outside layer group having a granular structure of 0.1 to 5mum average grain size. In this way, the chipping resistance of the cutting tool made of the surface coated TiC.N base cermet can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a surface-coated titanium carbonitride (hereinafter, referred to as "titanium carbonitride", which exhibits excellent chipping resistance (fine chipping resistance) in cutting under severe conditions such as high-speed cutting of steel.
(Denoted by TiCN) based cermet cutting tool.

[0002]

2. Description of the Related Art Conventionally, as described in, for example, Japanese Patent Application Laid-Open No. 56-62960, a boride of Ti, Al, Zr, and Hf is formed on the surface of a TiCN-based cermet substrate by chemical vapor deposition. Made of a surface-coated TiCN-based cermet, which is formed by forming a hard coating layer made of a carbide, a nitride, an oxide, and a multilayer of two or more of these two or more solid solutions with an average layer thickness of 2 to 20 μm. It is well known that cutting tools are used for cutting steel, for example.

[0003]

On the other hand, in recent years, cutting machines have been remarkably improved in performance and speed, and accordingly,
The cutting tools used for this also tend to be forced to cut under severe conditions.
A cutting tool made of iCN-based cermet, for example, with a cutting speed of 5
When used to cut steel at a high speed of 00 m / min., Chipping (fine chipping) is likely to occur on the cutting edge, and this chipping leads to an extremely short service life, so high-speed cutting of steel The current situation is that it cannot be used for.

[0004]

Therefore, the present inventors have
From the above viewpoints, focusing on the above-mentioned conventional surface-coated TiCN-based cermet cutting tool, and conducting research to improve the chipping resistance thereof, a conventional surface-coated TiCN-based cermet cutting tool is constructed. Each of the hard coating layers is composed of a granular structure having an average particle size of 0.1 to 5 μm, and the inner part of the hard coating layer is formed by using a physical vapor deposition method, and the average particle size is more than 0.05 μm. When the hard coating layer having a fine grain structure is used, the resulting surface-coated TiCN-based cermet cutting tool has a cutting speed of 50.
Even if steel is cut at a high speed of 0 m / min. Or more, chipping does not occur in the cutting edge due to the inclusion of the hard coating layer having the ultrafine grain structure, and excellent wear resistance is exhibited for a long period of time. The result of the research was that

The present invention has been made based on the above-mentioned research results, and boride, carbide, nitride, and oxide of Ti, Al, Zr, and Hf are formed on the surface of a TiCN-based cermet substrate. And a hard coating layer composed of two or more layers of these two or more solid solutions.
Surface-coated TiCN formed with an average layer thickness of ˜20 μm
In the base cermet cutting tool, the hard coating layer,
An inner layer group consisting of one layer or two or more layers, and an outer layer group consisting of one layer or two or more layers, and the inner layer group is an average layer having an ultrafine grain structure with an average grain size of 0.05 μm or less. Thickness: 0.5-5 μm of hard coating layer, while the outer layer group has an average particle size:
It is characterized by a surface-coated TiCN-based cermet cutting tool having excellent chipping resistance, which is composed of a hard coating layer having a granular structure of 0.1 to 5 μm.

Next, in the surface-coated TiCN-based cermet cutting tool of the present invention, the reason for limiting the average layer thickness and the average grain size of the hard coating layer constituting the cutting tool will be described.

(A) Average layer thickness of hard coating layer If the average layer thickness is less than 2 μm, desired excellent wear resistance cannot be secured, while the average layer thickness is 20 μm.
If it exceeds, the cutting edge is likely to be chipped or chipped, so that the average layer thickness is set to 2 to 20 μm.

(B) Average Layer Thickness of Inner Layer Group If the average layer thickness is less than 0.5 μm, desired excellent chipping resistance cannot be secured, while if the average layer thickness exceeds 5 μm, Since the layer thickness of the outer layer group becomes relatively thin and it is not possible to secure the excellent wear resistance brought about by this, the average layer thickness was set to 0.5 to 5 μm.

(B) Average particle size of the inner layer group If the average particle size is larger than 0.05 μm, the chipping resistance will be sharply reduced. Was set to 0.05 μm or less.

(C) Average particle size of the outer layer group If the average particle size is less than 0.1 μm, the wear resistance becomes poor, while if the average particle size exceeds 5 μm, the strength of the hard coating layer itself. Is decreased and chipping is likely to occur.
It was set to 5 μm.

[0011]

EXAMPLES The surface-coated TiCN-based cermet cutting tool of the present invention will be specifically described by way of examples. First of all, raw material powders having an average particle diameter within the range of 1 to 2.5 μm and having various compositions shown in Table 1 were prepared, and these raw material powders were blended into the blending composition also shown in Table 1. By wet-mixing in a ball mill for 72 hours, drying and press forming into a green compact, and sintering the green compact in a nitrogen gas atmosphere of 10 torr at a temperature of 1500 ° C. for 1 hour. TiCN-based cermet substrates (hereinafter referred to as cermet substrates) A to D having the throwaway chip shape of ISO / CNMG120408 were manufactured.

Then, on each surface of the cermet substrates A to D, first, using physical vapor deposition, one or more layers having the compositions, average layer thicknesses and average particle diameters shown in Tables 2 and 3 were formed. An inner layer group consisting of a hard coating layer was formed under the conditions shown in Table 4 (bias voltage: -100 v), and subsequently, by chemical vapor deposition, the composition, average layer thickness, and the like shown in Tables 2 and 3, And the surface-coated Ti of the present invention by forming an outer layer group consisting of one or more hard coating layers having an average particle size under the conditions shown in Table 5.
CN-based cermet cutting tools (hereinafter referred to as the present invention coated cutting tools) 1 to 8 were manufactured.

For the purpose of comparison, a chemical vapor deposition method is used,
Conventional surface-coated Ti under the same conditions, except that the compositions, average layer thicknesses, and one or more hard coating layers having the average layer thicknesses shown in Tables 6 and 7 are formed under the conditions shown in Table 5.
CN-based cermet cutting tools (hereinafter referred to as conventional coated cutting tools) 1 to 8 were manufactured.

Next, regarding the various coated cutting tools obtained as a result, the work material: round bar of JIS SCM440, cutting speed: 300 m / min., Depth of cut: 1 mm, feed: 0.2 mm / rev., Cutting time: 30 minutes, continuous cutting test of steel under the conditions, Work material: JIS SCM440 4 round bar with vertical groove, Cutting speed: 500 m / min., Depth of cut: 0.5 mm, Feed: An intermittent high-speed cutting test of steel was performed under the conditions of 0.1 mm / rev., Cutting time: 5 minutes, and the flank wear width was measured. The results of these measurements are shown in Table 8.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

[Table 4]

[0019]

[Table 5]

[0020]

[Table 6]

[0021]

[Table 7]

[0022]

[Table 8]

[0023]

Table 8 shows that both the coated cutting tools 1 to 8 of the present invention and the conventional coated cutting tools 1 to 8 are chipped at the cutting edge at a cutting speed of 300 m / min. However, the former has been shown to exhibit better wear resistance than the latter, however, in intermittent high speed cutting of steel with a cutting speed of 500 m / min. While all of them show excellent wear resistance without chipping on the cutting edge, all of the conventional coated cutting tools 1-8 chip on the cutting edge and reach the end of their useful life in a short time. Has been shown.

As mentioned above, the surface coated TiC of the present invention.
Since the N-based cermet cutting tool has excellent chipping resistance, chipping does not occur in the cutting edge even under severe conditions such as high-speed cutting of steel with a cutting speed of 500 m / min. It excels in cutting performance over a long period of time.

Claims (1)

[Claims] 1. A titanium carbonitride-based cermet substrate having two or more of Ti, Al, Zr, and Hf borides, carbides, nitrides, and oxides, and two or more of these solid solutions on the surface thereof. 2 to 2 hard coating layers consisting of
A surface-coated titanium carbonitride-based cermet cutting tool formed with an average layer thickness of 20 μm, wherein the hard coating layer comprises an inner layer group consisting of one or more layers, and also one layer or two or more layers. The outer layer group is divided into outer layer groups, and the inner layer group is composed of a hard coating layer having an average particle diameter of 0.5 μm or less and an average layer thickness of 0.5 to 5 μm. Diameter: a surface-coated titanium carbonitride-based cermet cutting tool having excellent chipping resistance, characterized by comprising a hard coating layer having a granular structure of 0.1 to 5 μm.