JPH081407A - Surface coated cemented carbide cutting tool - Google Patents

Abstract

(57) [Summary] [Object] To provide a surface-coated cemented carbide cutting tool having excellent adhesion of an artificial tire mond coating to a cemented carbide substrate surface. [Structure] The surface of a substrate made of cemented carbide, which is a sintered body having a compounding composition consisting of Co: 3 to 25%, metallic carbon / nitride: 0.05 to 25%, and WC: the balance by weight. A surface-coated cemented carbide cutting tool having an average diamond layer thickness of 1 to 20 μm, (a) Co content of the cemented carbide substrate: 3 to 8%, (b) Average particle size of WC of the cemented carbide substrate: 0.8 to 3 μm, (c) Surface roughness Ra on the bonding surface of the substrate to the artificial diamond film Ra: 0.1 to 3 μm, (d) Artificial body of the substrate The average thickness of the Co-free layer formed on the bonding surface portion with the diamond film: 1 to 15 μm, satisfying the above requirements (a) to (d).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated cemented carbide cutting tool having excellent adhesion of an artificial diamond coating to the surface of a cemented carbide substrate.

[0002]

2. Description of the Related Art Conventionally, a substrate is generally composed of Co: 3 to 25% as a binder phase forming component and Ti, T as a hard phase forming component.
Carbides of a, Nb, and V, and titanium nitride (hereinafter, TiC, TaC, NbC, VC, and T, respectively).
iN), and one or more of these two or more solid solutions (hereinafter collectively referred to as “metal carbon / nitride”): 0.05 to 25%, similarly hard phase Tungsten carbide as a forming component (hereinafter, referred to as WC): Remainder composition composition (above wt%, below%
Is a sintered body of cemented carbide, and an artificial diamond film is formed on the surface of this substrate by a vapor phase synthesis method such as a hot filament method, a microwave method, or a high frequency plasma method. A surface-coated cemented carbide cutting tool is known, which is formed with an average layer thickness of 1 to 20 μm,
It is well known that this is used for continuous cutting of, for example, an Al alloy having a high Si content.

[0003]

On the other hand, in recent years, labor-saving and automation of cutting work in recent years and further speeding up are remarkable, and accordingly, there is a tendency that cutting tools are required to have higher versatility and durability. However, in the above-mentioned conventional surface-coated cemented carbide cutting tool, especially because the adhesion of the artificial diamond film to the cemented carbide substrate surface is not sufficient, further high-speed cutting and heavy cutting, further intermittent cutting etc. When used, the artificial diamond film is liable to peel off and the service life is reached in a relatively short time.

[0004]

Therefore, the present inventors have
From the above viewpoints, focusing on the above-mentioned conventional surface-coated cemented carbide cutting tool, as a result of research to improve the adhesion of the artificial diamond film to the cemented carbide substrate surface, the cemented carbide substrate was found. Co content of 3 to 8%, and the average particle size of WC constituting this is 0.8 to 3
Using a cemented carbide substrate specified to μm, and prior to forming an artificial diamond film on the surface of the substrate, the surface of the cemented carbide substrate is subjected to, for example, electrolytic etching to roughen the surface to obtain a surface roughness Ra. Of 0.1 to 3 μm, and subsequently, this is immersed in, for example, an acid solution to form a Co-free layer on the surface of the substrate at 1 to 15 μm, preferably 2 to 6 μm.
When formed with an average layer thickness of m, the resulting surface-coated cemented carbide cutting tool markedly improves the adhesion of the artificial diamond coating to the cemented carbide substrate surface, resulting in continuous high-speed cutting, continuous heavy cutting, and intermittent cutting. The research results show that the artificial diamond film does not peel off even during cutting and exhibits excellent cutting performance over a remarkably long period of time.

The present invention was made based on the above research results, and Co: 3 was used as a binder phase forming component.
-25%, one or more kinds of metal carbon / nitride as a hard phase forming component: 0.05 to 25%, and WC as a hard phase forming component: the rest, a sintered body having a composition composition In the surface-coated cemented carbide cutting tool, wherein an artificial diamond film is formed on the surface of the cemented carbide substrate having an average layer thickness of 1 to 20 μm, (a) Co of the cemented carbide substrate Content: 3-8%, (b) WC average particle diameter of the cemented carbide substrate: 0.8-3 μm, (c)
Surface roughness Ra on the joint surface of the substrate with the artificial diamond film: 0.1 to 3 μm, (d) Decoupling formed on the joint surface of the substrate with the artificial diamond film.
Average thickness of layer: 1 to 15 μm, a surface-coated cemented carbide cutting tool having excellent adhesion of the artificial diamond coating to the surface of the cemented carbide substrate, which satisfies the requirements (a) to (d) above. It has characteristics.

Next, the reason why the constituent requirements of the cutting tool of the present invention are numerically limited as described above will be described. (A) Co Content of Cemented Carbide Substrate If the content is less than 3%, not only the desired toughness cannot be ensured in the substrate, but also it becomes difficult to form the Co-free layer to a desired thickness. On the other hand, when the content exceeds 8%, the strength of the Co-free layer is reduced, and under severe cutting conditions, a chip caused by this portion is likely to occur in the cutting edge. It was set to 3 to 8%, preferably 4 to 7%.

(B) Average particle size of WC If the average particle size is less than 0.8 μm, it becomes difficult to form a surface roughness of Ra: 0.1 μm or more by electrolytic etching. If the thickness exceeds 3 μm, not only the strength of the substrate decreases but also the strength of the Co-free layer decreases, which causes the occurrence of chipping, and the surface roughness in electrolytic etching exceeds Ra: 3 μm and becomes rough. Therefore, the average particle size is set to 0.8 to 3 μm, preferably 1 to 2 μm.

(C) Surface Roughness of Substrate If the surface roughness Ra is less than 0.1 μm, the desired excellent adhesion cannot be secured to the artificial diamond film, while the surface roughness Ra exceeds 3 μm. Since the surface smoothness of the formed artificial diamond film will be impaired, the surface roughness Ra will be 0.1 to 3 μm.
m, preferably 0.2 to 2 μm.

(D) Average thickness of Co-free layer If the average thickness is less than 1 μm, it is unavoidable that Co suppresses the generation of diamond nuclei, and as a result, it is difficult to form an artificial diamond film having high adhesion. On the other hand, when the average thickness exceeds 15 μm, the cutting edge is likely to be chipped due to this, so that the average thickness is 1 to 15 μm.
μm, preferably 2 to 6 μm.

Regarding the composition of the cemented carbide substrate constituting the conventional surface-coated cemented carbide cutting tool, the proportion of Co is set to 3 to 25% because the proportion is less than 3% in the substrate. This is because the desired toughness cannot be secured, and on the other hand, if the ratio exceeds 25%, the strength suddenly decreases, and the ratio of metallic carbon / nitride is set to 0.05 to 25. % Is based on the reason that if the proportion is less than 0.05%, the desired hardness and strength improving effect cannot be obtained, while if the proportion exceeds 25%, the toughness decreases. In addition, the average layer thickness of the artificial diamond film is similarly set to 1 to 20 μm because the desired abrasion resistance improving effect cannot be obtained when the average layer thickness is less than 1 μm, while the average layer thickness exceeds 20 μm. And artificial diamond film Chipping to the body (micro-chipped)
This is because that is likely to occur.

[0011]

EXAMPLES Next, the cutting tool of the present invention will be specifically described by way of examples. As raw material powder, 0.8-
WC powder having a predetermined average particle size within the range of 5 μm, T
iC powder, TaC powder, NbC powder, VC powder, TiN
Powders and Co powders were prepared, and these raw material powders were blended to the blending composition shown in Table 1, respectively, and then mixed under normal conditions, molded into a green compact, and sintered.
C120 alloy having a tip shape of N120408 and having the Co content and the WC average particle size shown in Table 2
And electrolytically treated under the following conditions: electrolytic solution: 5% NaOH aqueous solution at 30 ° C., anode: the above cemented carbide substrate, cathode: stainless steel, current density: 1 A / dm ² . The electrolytic etching time was adjusted within the range of 1 to 10 minutes, and the surface roughness was similarly set as shown in Table 2. Further, this was immersed in an acid solution consisting of a 5% HNO ₃ aqueous solution at 30 ° C. Is adjusted within the range of 5 to 20 minutes and Table 1 is also shown.
Forming a deCo layer having an average thickness shown on the substrate surface portion,
In this state, a hot filament method is used on the surface of the substrate, and the reaction gas composition: CH ₄ / H ₂ = volume ratio is 1.5 / 10.
0, the distance between the filament and the substrate surface: 15 mm, the atmospheric pressure: 15 torr, the filament temperature: 2000 ° C., to form an artificial diamond film. By making the thickness of the present invention surface-coated cemented carbide cutting tool (hereinafter,
The present invention cutting tools) 1 to 5 and the comparative surface-coated cemented carbide cutting tools (hereinafter referred to as comparative cutting tools) 1 to 7 were manufactured.

The comparative cutting tools 1 to 7 are made of a cemented carbide base material in which any one of the constituent requirements (marked with * in Table 2) is out of the scope of the present invention. is there.

Then, with respect to the cutting tools 1 to 5 of the present invention and the comparative cutting tools 1 to 7 obtained as a result, the work material: a round bar of Al-18 wt% Si alloy, cutting speed: 600 m / min, feed: 0.2 mm / rev., Depth of cut: 0.5 mm, cutting time: 60 minutes, continuous high-speed cutting test of Al alloy with high Si content,
And work material: Round bar made of Al-13% by weight Si alloy with three circumferentially equally spaced flutes, cutting speed: 1000 m / min, feed: 0.2 mm / rev., Depth of cut: 2 mm, cutting time: 60 The intermittent cutting test of the Al alloy having a high Si content was performed under the following conditions, and the flank wear width of the cutting edge was measured in each test.
The results of these measurements are shown in Table 3.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

[0017]

From the results shown in Tables 2 and 3, the cutting tools 1 to 5 of the present invention show that the high Si content of Al, which is one of the difficult-to-cut materials.
It is clear that in both continuous high-speed cutting and interrupted cutting of alloys, the artificial diamond film does not peel, and there is no chipping or chipping on the cutting edge, and it is clear that it exhibits excellent cutting performance. Comparative cutting tool 1
7 to 7, when any of the constituent requirements of the cemented carbide substrate deviates from the scope of the present invention, the artificial diamond film is peeled off, or the cutting edge is chipped or chipped. It is clear that the service life is reached in a relatively short time due to the cause. As described above, the surface-coated cemented carbide cutting tool of the present invention has excellent adhesion of the artificial diamond film to the surface of the cemented carbide substrate, so that the artificial diamond film can be cut even under severe conditions. It does not cause peeling and exhibits excellent cutting performance over a remarkably long period of time.

Claims (1)

[Claims] 1. By weight%, Co: 3 to 25% as a binder phase forming component, Ti, Ta, Nb, and V carbides as a hard phase forming component, and titanium nitride, and a solid solution of two or more of these. One or more of them: 0.05 to 25%, similarly tungsten carbide as the hard phase forming component: the rest,
A surface-coated cemented carbide cutting tool comprising an artificial diamond coating formed on the surface of a substrate made of cemented carbide, which is a sintered body having a compounding composition of, with an average layer thickness of 1 to 20 μm. ) Co content of the cemented carbide substrate: 3 to 8%, (b) Average particle size of tungsten carbide of the cemented carbide substrate: 0.8 to 3 μm, (c) Joining of the substrate with an artificial diamond film Surface roughness Ra on the surface: 0.1 to 3 μm, (d) Average thickness of the Co-free layer formed on the surface of the substrate to be joined to the artificial diamond film: 1 to 15 μm, or more (a) to (d) A surface-coated cemented carbide cutting tool characterized by satisfying the requirements of.