JPH08187607A - Cutting tool of surface coated wc based cemented carbide - Google Patents

Abstract

PURPOSE: To prolong the service life of a cutting tool greatly while having normal abrasion, by disposing an inner layer of titanium carbide layer or titanium carbide/nitride layer and an intermediate layer of titanium nitride and then disposing columnar grains grown in direction of layer thickness on the inner/intermediate layers as back. CONSTITUTION: Coating is made with an inner layer as single layer of TiC layer or TiCN layer, or plural two layers of them, having composition containing W and Co diffused from a base, of average crystal diameter up to 0.05μm and average layer thickness 0.05-0.5μm. Then coating is made with an intermediate layer on the inner layer, of TiN layer, of average crystal diameter up to 0.05μm and average layer thickness 0.05-0.5μm. in this coating layer of inner/outer layers as back, the mutual adhesion is excellent. Then, coating is made with an outer layer of TiN layer, on the coating layer, having columnar crystal grains grown in direction of layer thickness, of average layer thickness 2.0-15μm. Thus, a desired cutting tool of surface coated WC based cemented carbide is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a surface-coated WC-based cemented carbide showing excellent cutting performance when performing continuous dry cutting or continuous wet cutting of steel or the like under severe conditions such as high feed and high depth of cut. The present invention relates to an alloy cutting tool.

[0002]

2. Description of the Related Art Generally, a commercially available surface-coated WC-based cemented carbide cutting tool has a WC-based cemented carbide as a base material, and its surface is coated with a carbonitride of Ti (hereinafter referred to as TiC).
N) is coated on the surface of the WC-based cemented carbide cutting tool, and the surface of the WC-based cemented carbide cutting tool is further coated with an aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) layer and a nitriding layer. One of a titanium (hereinafter referred to as TiN) layer and a titanium oxycarbonitride (hereinafter referred to as TiCNO) layer or a plurality of two or more kinds of layers has an average layer thickness of 0.5 to 10 μm.
It is known that coating is performed within the range of m.

However, since the conventional CVD method is performed at a high temperature of about 1000 ° C., the WC cemented carbide substrate and the TiCN are used.
A decarburized layer is formed at the boundary with the layer, and the TiCN layer is easily peeled off from the WC cemented carbide substrate, and therefore the conventional CVD
When continuous dry cutting or continuous wet cutting of steel or the like under severe conditions such as high feed and high depth of cut using a surface-coated WC-based cemented carbide cutting tool produced by the method, peeling of the coating layer occurs, The cutting tool life was not sufficient.

Therefore, in recent years, organic CN has been used, and
A medium-temperature chemical vapor deposition method (hereinafter referred to as MTCVD method) in which chemical vapor deposition is performed at a temperature of 0 to 900 ° C. has been proposed (see Japanese Patent Laid-Open No. 3-87369). It is also known that the coating layer formed by the MTCVD method has columnar crystal grains grown in the thickness direction of the layer (see Japanese Patent Laid-Open No. 6-8008).

[0005]

However, the above-mentioned M
The coating layer formed by the TCVD method does not form a decarburized layer at the boundary between the WC cemented carbide substrate and the TiCN layer, but since a highly reactive organic CN compound is used, it is a component constituting the substrate. Is less diffused into the coating layer and therefore has poor adhesion, and the cutting tool life is still extended when continuous dry cutting or continuous wet cutting of steel, etc. is performed under severe conditions such as high feed and high depth of cut. I couldn't.

[0006]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of conducting a study to improve the adhesion of the coating layer formed by the MTCVD method and extend the life of the cutting tool made of the surface-coated WC-based cemented carbide, the average crystal grain size: 0.05 μm or less, the average layer thickness: A TiC layer and a TiCN layer having a composition containing W and Co diffused from a substrate and having a thickness of 0.05 to 0.5 μm, and coated as an inner layer with one single layer or two or more layers. Average grain size on inner layer: 0.0
When an intermediate layer composed of a TiN layer having a thickness of 5 μm or less and an average layer thickness of 0.05 to 0.5 μm is coated, the coating layer composed of the inner layer and the intermediate layer has particularly excellent adhesion as a base layer. A cutting tool made of a WC-based cemented carbide surface-coated with an outer layer composed of a TiCN layer having an average layer thickness of 2.0 to 15 μm having columnar crystal grains grown in the layer thickness direction on the It was found that the cutting tool made of WC-based cemented carbide having a surface coating has a much longer cutting life.

The present invention has been made on the basis of such findings, and on the surface of a WC-based cemented carbide substrate containing WC and Co as main components, in order from the substrate side, (1) average crystal grain size: 0.05 μm or less, average layer thickness: 0.05-0.
5 μm (preferably 0.05 to 0.18 μm),
T having a composition containing W and Co which are the main components of the substrate
An inner layer consisting of one kind of single layer or two or more kinds of layers among the iC layer and the TiCN layer, an average crystal grain size: 0.05 μm or less, and an average layer thickness: 0.05 to 0.5 μm (preferably 0.
Having an average thickness of 0.5 to 0.18 μm), an intermediate layer consisting of a TiN layer, and columnar crystal grains grown in the layer thickness direction.
Surface-coated WC-based cemented carbide cutting tool coated with an outer layer consisting of a TiCN layer of 2.0 to 15 μm, (2) Al having an average layer thickness of 0.5 to 10 μm outside the outer layer. The surface-coated WC-based cemented carbide cutting tool according to (1) above, which is formed by coating one single layer or a plurality of two or more layers selected from a ₂ O ₃ layer, a TiN layer, and a TiCNO layer. I have.

In order to form the TiC layer and TiCN layer of the inner layer of the surface-coated WC-based cemented carbide cutting tool of the present invention, TiCl ₄ , which is used in a usual CVD reaction at a reaction temperature higher than 900 ° C., To react a gas such as CH ₄ , N ₂ and H ₂ to form an intermediate TiCN layer,
TiCl ₄ , CH ₄ , N ₂ used for the CVD reaction at a reaction temperature of 900 ° C. or less and a low vacuum of 150 torr or more,
It is formed by reacting H _{2 and the} like. Further, in order to form a TiCN layer having columnar crystal grains grown in the layer thickness direction of the outer layer, a reaction temperature of 950 ° C. or higher and 100 to
TiCl ₄ , CH ₄ , N ₂ , H _{2 in} high vacuum below rr
It is formed by the MTCVD method of reacting with a gas such as.

The reason why the inner layer, intermediate layer, outer layer and outermost layer of the WC-based cemented carbide cutting tool of the present invention are limited as described above will be explained. (A) Inner layer When the average crystal grain size of the inner layer is larger than 0.05 μm, the crystal grains of the intermediate layer grow too much, which is not preferable, and the average layer thickness of the inner layer is 0.05 to 0.5 μm.
The reason is that if it is less than 0.05 μm, a sufficient adhesion improving effect cannot be obtained, and if it is more than 0.5 μm, the decarburized layer increases, which is not preferable.

(B) Intermediate layer If the average crystal grain size of the intermediate layer is larger than 0.05 μm,
This is because the crystal grains of the outer TiCN layer grow too much, which is not preferable, and the average layer thickness of the intermediate layer is 0.0
The reason why it is set to 5 to 0.5 μm is that if it is less than 0.05 μm, a sufficient adhesion improving effect cannot be obtained, and if it is more than 0.5 μm, the crystal grains of the TiN layer grow excessively, which is not preferable. is there.

(C) Outer Layer The outer layer has an average layer thickness of 2.0 to 15 μm, which is 2.0.
If it is smaller than μm, sufficient abrasion resistance cannot be obtained, and it is 15 μm.
If it is larger, TiCN crystal grains grow and abnormal wear is likely to occur, which is not preferable.

(D) Outermost layer The outermost layer has an average layer thickness of 0.5 to 10 μm.
If it is less than 5 μm, the crater resistance and welding resistance are not improved, and if it is more than 10 μm, chipping of defects is likely to occur, which is not preferable.

[0013]

EXAMPLES Next, the present invention will be specifically described based on Examples. WC-based cemented carbide substrates A to E having the compositions shown in Table 1 were prepared.

[0014]

[Table 1]

Then, the WC-based cemented carbide substrates A to E shown in Table 1 were loaded into a normal chemical vapor deposition apparatus, and shown in Tables 3, 4, and 5 under the conditions shown in Table 2. The present invention surface-coated WC-based cemented carbide cutting tool (hereinafter referred to as the present invention-coated cutting tool) 1 to 10 having an inner layer, an intermediate layer, an outer layer and, if necessary, an outermost layer, a comparative surface coating WC
Base cemented carbide cutting tools (hereinafter referred to as comparative coated cutting tools) 1 to 7 and conventional surface-coated WC based cemented carbide cutting tools (hereinafter referred to as conventional coated cutting tools) 1 to 5 were prepared.

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

[Table 4]

[0019]

[Table 5]

These surface-coated cutting tools 1 to 10 of the present invention,
Using comparative surface-coated cutting tools 1-7 and conventional surface-coated cutting tools 1-5, work material: SCM440, cutting speed: 300 m / min. , Feed: 0.4 mm / rev. , Depth of cut: 2 mm, cutting time: 10 min. High speed continuous cutting was carried out under the following conditions: cutting oil: none, the amount of wear and the form of wear were examined, and the results are shown in Table 6.

[0021]

[Table 6]

[0022]

From the results shown in Tables 3 to 6, the coated cutting tools 1 to 10 of the present invention maintain normal wear compared with the conventional coated cutting tools 1 to 5, and the life of the cutting tools is significantly improved. I understand that. However, it can also be seen that the comparatively coated cutting tools 1-7, which deviate from the conditions of the invention, do not show normal wear and therefore the cutting tools have a short life.

As described above, the surface-coated WC-based cemented carbide cutting tool of the present invention maintains normal wear as compared with the prior art and can greatly improve the life of the cutting tool, which is an industrially excellent effect. It plays.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C23C 16/40 (72) Inventor Kazuhiro Kono 1511 Furumagi, Ishishita-cho, Yuki-gun, Ibaraki Mitsubishi Materials Stock Company Tsukuba Factory

Claims (2)

[Claims] 1. An average crystal grain size: 0.05 μm or less and an average layer thickness: 0.05 on the surface of a WC-based cemented carbide substrate containing WC and Co as main components in order from the substrate side.
An inner layer consisting of a single layer or two or more layers of a titanium carbide layer and a titanium carbonitride layer having a composition containing W and Co which are the main components of the substrate, Average crystal grain size: 0.05 μm or less, average layer thickness: 0.05
An intermediate layer consisting of a titanium nitride layer having a thickness of 0.5 μm and columnar crystal grains grown in the layer thickness direction, and an average layer thickness: 2.
A surface-coated WC-based cemented carbide cutting tool, characterized by being coated with an outer layer consisting of a titanium carbonitride layer having a thickness of 0 to 15 μm. 2. A single layer or a mixture of two or more of an aluminum oxide layer, a titanium nitride layer, and a titanium oxycarbonitride layer having an average layer thickness of 0.5 to 10 μm further outside the outer layer. The surface-coated WC-based cemented carbide cutting tool according to claim 1, wherein the outermost layer composed of a plurality of layers is coated.