JPH06170611A - Surface coating tungsten carbide base cemented carbide cutting tool - Google Patents

Abstract

PURPOSE:To provide a surface coating WC base cemented carbide cutting tool in which the adhesive strength of a hard coating layer to a base surface is strong. CONSTITUTION:A surface coating WC base cemented carbide cutting tool is formed of a WC base cemented carbide composed of substantially a hard phase of mainly WC and a metallic bond phase of mainly Co. Also a hard coating layer which is composed of one type of single layer or two or more types of multiple layers among TiC, TiN, TiCN, TiCNO, and Al2O3 and in which a first layer made in contact with a demetalization layer which is formed on the surface of a base is formed of TiN or TiCN is deposited on the surface of the base on which rough demetalization layer formed with substantially hard phase is formed in the depth of less than 1 to 2mum from the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a remarkably high adhesion strength of a hard coating layer to a surface of a substrate, and therefore has a high adhesion strength particularly to a hard coating layer for heavy cutting such as high feed and high depth cutting of steel and finish cutting. Surface-coated tungsten carbide (hereinafter referred to as WC) that exhibits excellent cutting performance over an extremely long period even when used for required cutting
The present invention relates to a base cemented carbide cutting tool.

[0002]

2. Description of the Related Art Conventionally, 4a, 5a and 6a of the periodic table
For example, a hard phase mainly composed of one or more members selected from the group consisting of carbides of group metals, nitrides of group 4a and group 6a metals, and solid solutions of two or more of these metals, for example, 80 to 9
5% by weight, the balance being one or two of the iron group metals
Or more, or a super-hard sintered alloy composed of a metal-bonded phase mainly composed of one or more iron group metals and one or more chromium group metals. Using physical vapor deposition or chemical vapor deposition on the surface,
Carbides of metals a, 5a, and 6a, 4a and 6
Group a metal nitrides, Group 4a and group 5a metal oxides,
And a hard coating layer composed of two or more kinds of solid solutions thereof, and a single layer of aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) or two or more kinds of multilayers, for example, 2 to 15 μm. The surface-coated ultra-hard sintered alloy cutting tool formed with the average layer thickness of is known and is widely used in practice.

[0003]

However, in the above-mentioned conventional surface-coated ultra-hard sintered alloy cutting tool, when the hard coating layer is formed on the surface of the ultra-hard sintered alloy substrate, the hard surface of the substrate surface is hardened. At the interface with the coating layer, M ₁₂ C or M
_Since low-grade carbides such as ₆ C type will be formed,
Due to the presence of this low-grade carbide and the large difference in the coefficient of thermal expansion existing between the substrate and the hard coating layer, for example, this is high feed, heavy cutting with high load, and small feed and cut. That is, when used for finish cutting under the condition that the hard coating layer is removed, the hard coating layer is easily peeled off, and the service life is relatively short.

[0004]

Therefore, the present inventor pays attention to the above-mentioned conventional surface-coated ultra-hard sintered alloy cutting tool from the above-mentioned viewpoint, and adheres the hard coating layer to the surface of the substrate. As a result of conducting a study to improve the properties, the base material is specified to be a WC-based cemented carbide substantially composed of a hard phase mainly composed of WC and a metal binding phase mainly composed of Co,
And, in a state where a rough demetallized layer is formed on the surface portion of the substrate over a depth of 1 to less than 2 μm from the surface, which is substantially composed of the hard phase and in which the metal binding phase does not exist,
On the surface of this, Ti carbide, nitride, carbonitride, and carbonitride oxide (hereinafter, respectively TiC, TiN, TiC
N and TiCNO), and a single layer of Al ₂ O ₃ or two or more layers of Al ₂ O ₃ , and the first layer in contact with the substrate surface is made of either TiN or TiCN. When the hard coating layer is formed by a chemical vapor deposition method or a physical vapor deposition method, the resulting surface-coated WC-based cemented carbide cutting tool is composed of a hard layer mainly consisting of WC in the above-mentioned substrate during vapor deposition. The demetallized layer and the TiN layer and the TiCN layer forming the hard coating layer react with each other to have a strong adhesive strength, and further, the TiN layer and the TiCN layer of the first layer and the second and subsequent layers are formed. TiC layer, TiN, which is a hard coating layer
Layer, TiCN layer, TiCNO layer, and Al ₂ O ₃ layer also have extremely high adhesion strength, so this is required for high adhesion strength in hard coating layers, such as for heavy cutting and finishing cutting of steel. Even when it was used, the research results obtained showed that the hard coating layer did not peel and exhibited excellent cutting performance for a remarkably long time.

The present invention has been made based on the above-mentioned research results, and is composed of a WC-based cemented carbide substantially consisting of a hard phase mainly composed of WC and a metal bonded phase mainly composed of Co. In this case, the weight ratio of the hard phase and the metal binding phase may be the same as that of the conventional one, that is, the hard phase: 80 to 95%, the metal binding phase: the rest, and 1 to 1 from the surface.
On the surface of the substrate on which the rough demetallized phase substantially composed of the above hard phase is formed, the Ti layer is formed over a depth of less than 2 μm.
C, TiN, TiCN, TiCNO, and Al ₂ O ₃
Hard coating in which the first layer, which is composed of one single layer or two or more multi-layers of the above, and which is in contact with the demetallized layer formed on the surface of the substrate, is made of either TiN or TiCN. The layer is 2-15 μm, which is the same as the conventional one
This is characterized by a surface-coated WC-based cemented carbide cutting tool having a significantly high adhesion strength of the hard coating layer to the surface of the substrate, which is formed by vapor deposition with an average layer thickness of.

In the cutting tool of the present invention, the depth (thickness) of the demetallized layer on the surface of the base body is limited to less than 1 to 2 μm, because the depth of less than 1 μm causes the hard coating layer to be removed. If the desired excellent bond strength cannot be secured in the meantime, and if the depth becomes 2 μm or more, chipping or tipping (fine chipping) caused by the demetallization layer, especially during finish cutting of steel, may occur at the tip of the cutting edge. This is because it is more likely to occur.

[0007]

EXAMPLES Next, the surface-coated WC-based cemented carbide cutting tool of the present invention will be specifically described by way of examples. In each case, raw material powders having a predetermined average particle diameter within the range of 1 to 3.2 μm were used, and these raw material powders were blended to the blending composition shown in Table 1, wet-blended in a ball mill for 48 hours, and dried, Press-molded into a green compact with a pressure of 1 ton / cm ² , and sinter these green compacts in a vacuum of 10 ^-2 torr at 1390 ° C for 1 hour, and finish-polish this sintered body. Give me I
WC-based cemented carbide substrates A to F having the SO standard SNMN432 slow-away tip shape are formed, and then these substrates are immersed in a 5% HNO ₃ aqueous solution for an appropriate time,
A rough demetallized layer consisting essentially of only the hard phase of the substrate is formed on the surface over the depth (thickness) from the surface shown in Table 2, and subsequently on the surface of this substrate. , A chemical vapor deposition method and a physical vapor deposition method are used to form a hard coating layer having the same composition and average layer thickness as shown in Table 2 under ordinary conditions. The present invention coated cutting tools) 1 to 6 were manufactured respectively.

Further, for the purpose of comparison, as shown in Table 2, a comparative surface-coated WC-based cemented carbide cutting tool (hereinafter referred to as "Comparative Comparison") is used under the same conditions except that the demetallizing layer is not formed on the surface of the substrate. 1 to 6 are referred to as coated cutting tools.

Next, regarding the various coated cutting tools obtained as a result, the work material: JIS / SNCM439 (hardness: H _B 230)
Round bar, cutting speed: 150 m / min., Feed: 0.55 mm / rev., Depth of cut: 2 mm, cutting time: 15 minutes, high feed high depth continuous cutting test of steel
The flank wear width and rake face wear depth of the cutting edge were measured. The results of these measurements are shown in Table 2.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

From the results shown in Table 2, all of the coated cutting tools 1 to 6 of the present invention show excellent wear resistance without peeling in the hard coating layer, whereas the coated cutting tools of the present invention have excellent wear resistance. In the comparative coated cutting tools 1 to 6, in which the hard coating layer was formed on the surface of the substrate where the hard phase and the metal binding phase coexisted without forming the demetallized layer, peeling occurred in the hard coating layer during cutting, It is clear that it exhibits only a very short service life. As described above, the surface-coated WC-based cemented carbide cutting tool of the present invention is formed on the surface of a WC-based cemented carbide substrate and is substantially composed of only a hard phase, and does not have a metal binding phase. Depending on the demetalization layer on the surface, especially TiN or Ti
Since the adhesion strength of the hard coating layer made of CN to the surface of the substrate becomes extremely high, even when this is required for the hard coating layer to have high adhesion strength, for example, when it is used for heavy cutting or finishing cutting of steel, it is hard. The coating layer does not peel, and exhibits excellent cutting performance for a very long period of time.

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Claims (1)

[Claims] 1. A tungsten carbide-based cemented carbide composed of a hard phase essentially consisting of tungsten carbide and a metallic binder phase mainly consisting of Co, and 1 to 2 from the surface.
Carbide, nitride, carbonitride, and carbonitride of Ti are formed on the surface of the substrate on which the rough demetallized layer substantially composed of the hard phase is formed over a depth of less than μm. And a first layer formed of a single layer of aluminum oxide or a multi-layer of two or more types of aluminum oxide, which is in contact with the demetallized layer formed on the surface portion of the substrate, among Ti nitride and carbonitride. A surface-coated tungsten carbide-based cemented carbide cutting tool formed by vapor-depositing a hard coating layer composed of any of the above.