JPH07223101A - Surface covered sintered hard alloy cutting tool - Google Patents

Abstract

PURPOSE:To provide a surface covered sintered hard alloy cutting tool excellent in adhesiveness of an artificial diamond film to a sintered hard alloy base surface. CONSTITUTION:In a surface covered sintered hard alloy cutting tool, an artificial diamond films having an average layer thickness of 1 to 20mum is formed on the surface of a base formed of a sintered hard alloy made of Co as a connection phase forming component and WC as a hard phase forming component. Then, such conditions may be satisfied, that the content of CO in the sintered hard alloy is 3 to 8w%, the average particle diameter of WC in the sintered hard alloy is 0.8 to 3mum, surface roughness on a surface joined with the artificial diamond film of the base is Ra=0.1 to 3mum and the average thickness of a deCO layer formed on the surface joined with the artificial diamond film of the base is 1 to 15mum.

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 a cemented carbide containing Co as a binder phase forming component and tungsten carbide (hereinafter referred to as WC) as a dispersed phase forming component.
On the surface of this substrate, hot filament method, microwave method,
Further, there is known a surface-coated cemented carbide cutting tool in which an artificial diamond film is formed with an average layer thickness of 1 to 20 μm by using a gas phase synthesis method such as a high frequency plasma method. It is also well known that it is used for continuous cutting of alloys and the like.

[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-mentioned viewpoint, as a result of focusing on the conventional surface-coated cemented carbide cutting tool and conducting a study to improve the adhesion of the artificial diamond coating to the cemented carbide substrate surface, the Co content was changed. Using a cemented carbide substrate having 3 to 8% by weight and an WC average particle size of 0.8 to 3 μm, and prior to forming an artificial diamond film on the surface of the cemented carbide substrate, for example, Electrolytic etching is applied to roughen the surface, and the surface roughness is Ra = 0.1-3.
μm, and subsequently, this is immersed in, for example, an acid solution to form a Co-free layer on the surface of the substrate with an average layer thickness of 1 to 15 μm, preferably 2 to 6 μm. The hard alloy cutting tool has significantly improved adhesion of the artificial diamond coating to the surface of the cemented carbide substrate, and no peeling of the artificial diamond coating occurs during continuous high-speed cutting, continuous heavy cutting, or intermittent cutting. We obtained the research results that show excellent cutting performance.

The present invention has been made based on the above-mentioned research results, and Co as a binder phase forming component has been made.
And 1 to 2 artificial diamond coatings on the surface of the substrate made of cemented carbide containing WC as a hard phase forming component.
In a surface coated cemented carbide cutting tool formed with an average layer thickness of 0 μm, (a) Co content of the cemented carbide:
3 to 8% by weight, (b) average particle size of WC of the above cemented carbide: 0.8 to 3 μm, (c) surface roughness on the joint surface of the above substrate with the artificial diamond film: Ra = 0.1
˜3 μm, (d) Average thickness of the Co-free layer formed on the surface of the substrate to be joined with the artificial diamond film: 1 to 15
The present invention is characterized by a surface-coated cemented carbide cutting tool having excellent adhesion of the artificial diamond film to the surface of the cemented carbide substrate, the cutting tool satisfying the above requirements (a) to (d).

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 If the content is less than 3% by weight, 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. , While its content is 8
When the content is more than 10% by weight, 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, so the content thereof is preferably 3 to 8% by weight. Was determined to be 4 to 7% by weight.

(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 is less than Ra = 0.1 μm, the desired excellent adhesion to the artificial diamond film cannot be secured, while the surface roughness Ra = 3 μm. If it exceeds, the surface smoothness of the formed artificial diamond film will be impaired. Therefore, the surface roughness is Ra = 0.1-3.
μm, preferably Ra = 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.

(E) Average Layer Thickness of Artificial Diamond Film If the average layer thickness is less than 1 μm, desired excellent wear resistance cannot be secured, while the average layer thickness is 20 μm.
If it exceeds the range, chipping (fine chipping) is likely to occur in the artificial diamond film itself, so that the average layer thickness is defined as 1 to 20 μm. 3 to 15 μm
An average layer thickness of

[0011]

EXAMPLES Next, the cutting tool of the present invention will be specifically described by way of examples. A cemented carbide substrate having the shape of SPGN12408 and having the Co content and the WC average particle size shown in Table 1 was prepared, and an electrolyte solution: 5% NaOH aqueous solution at 30 ° C., an anode: the cemented carbide Alloy substrate, cathode:
Electrolytic etching is performed under the conditions of stainless steel and current density: 1 A / dm ² , in which case the electrolytic etching time is 1
The surface roughness is also adjusted within the range of 10 minutes to obtain the surface roughness also shown in Table 1, and this is further dipped in an acid solution consisting of a 5% HNO ₃ aqueous solution at 30 ° C.
A Co-free layer having the same average thickness as shown in Table 1 is formed on the surface of the substrate by adjusting within the range of -30 minutes, and in this state, the hot filament method is used on the surface of the substrate.
CH ₄ / H ₂ = 1.5 / 100 in volume ratio, distance between filament and substrate surface: 15 mm, atmospheric pressure: 15 torr,
An artificial diamond film is formed under the condition of filament temperature: 2000 ° C., and in this case, the treatment time is adjusted to obtain the average layer thickness shown in Table 1 as well. 1 to 5 and comparative surface-coated cemented carbide cutting tools (hereinafter referred to as comparative cutting tools) 1 to 7, respectively.

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 1) is out of the scope of the present invention. .

Next, regarding 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
1-18 wt% Si alloy round bar, cutting speed: 600 m /
min., feed: 0.1 mm / rev., depth of cut: 0.5 mm, cutting time: 30 minutes, dry continuous high-speed cutting test of Al alloy with high Si content, and work material: Al-13 weight % S
i alloy, cutting speed: 1500 m / min., feed: 0.15
mm / blade, depth of cut: 5 mm, cutting time: 30 minutes, wet-milling test of high Si content Al alloy,
In each test, the flank wear width of the cutting edge was measured. The results of these measurements are shown in Table 2.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

From the results shown in Tables 1 and 2, the cutting tools 1 to 5 of the present invention show that high Si-containing Al, which is one of the difficult-to-cut materials, is used.
It is clear that in both continuous high speed cutting and milling of alloys, the artificial diamond film does not peel, and there is no chipping or chipping in the cutting edge, and it is clear that excellent cutting performance is exhibited. As seen in the comparative cutting tools 1 to 7, when any of the constituents 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 occurs, and it is clear that it reaches the end of its service life in a relatively short time. 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. An artificial diamond film is formed on a surface of a substrate composed of a cemented carbide composed of Co as a binder phase forming component and tungsten carbide as a hard phase forming component.
In a surface-coated cemented carbide cutting tool formed with an average layer thickness of 20 μm, (a) Co content of the cemented carbide: 3 to 8% by weight, (b) average tungsten carbide of the cemented carbide. Particle size:
0.8 to 3 μm, (c) Surface roughness on the joint surface of the substrate with the artificial diamond film: Ra = 0.1 to 3 μm, (d) Desorption formed on the joint surface of the substrate with the artificial diamond film. Average thickness of Co layer: 1 to 15 μm, satisfying the above requirements (a) to (d), a surface coated cemented carbide cutting tool.