JPH0446701A - Vapor phase synthetic diamond cutting tool - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a cutting tool using a polycrystalline diamond film formed by a vapor phase synthesis method.

<Prior art> Diamond has properties such as high hardness, low coefficient of friction, high thermal conductivity, and excellent corrosion resistance.Cutting tools using diamond have high hardness, high wear resistance, It is used for machining difficult-to-cut materials because it has excellent adhesion resistance with work materials.

Conventional diamond cutting tools of this type include single-crystal diamond tools in which a single-crystal diamond cutting edge is attached to a base material, and sintered diamond tools in which fine-grained diamond is sintered at high temperature and pressure. It has been put into more practical use.

However, these diamond cutting tools have drawbacks such as being expensive and difficult to apply to cutting tools with complicated shapes.

Recently, it has become possible to synthesize a diamond thin film using a vapor phase synthesis method, and diamond-coated tools have been developed in which a diamond film is directly coated on a tool base. However, in the case of diamond-coated tools, the adhesion between the tool base and the diamond thin film is important. For example, in tools with a diamond thin film formed on a cemented carbide, there is a risk that the diamond thin film will peel off during cutting. be.

<Problems to be Solved by the Invention> In view of the above-mentioned conventional problems, the present inventors have developed a diamond cutting tool that is comparable to single-crystal diamond tools and sintered diamond tools, is inexpensive, and has a long tool life. The purpose is to provide

<Means for Solving the Problems> The present inventors selected a substrate that has good adhesion to vapor phase synthesized diamond and has a thermal expansion coefficient close to that of diamond, and deposited air on the substrate. We have discovered that an excellent diamond cutting tool can be obtained by depositing a polycrystalline diamond film using a phase synthesis method and directly adhering this substrate to the part of the tool base that forms the cutting edge, with the diamond film-formed surface serving as the rake surface. It is something that

<Operation> That is, SiC or 5isN4 is used as a substrate, polycrystalline diamond is deposited on it by vapor phase synthesis, and it is bonded to the cutting edge of a tool base made of hardened steel or cemented carbide, and then the blade is attached. By doing this, it is possible to obtain a diamond cutting tool that has performance comparable to that of single-crystal diamond cutting tools and sintered diamond cutting tools. 1st
The figure is a perspective view of a vapor-phase synthetic diamond cutting tool obtained by this invention, and FIG. 2 is a partially enlarged view of FIG. 1, where 1 is a vapor-phase synthetic diamond film formed on a substrate 2, and 3 is a tool. The base body 4 is an adhesive layer.

Here, as the substrate 2, SiC or 5isN4 is
A sintered body containing these as main components is used, but SiC or 5iJ4 produced by other methods can also be used. Tool base 3 of these substrates 2 on which polycrystalline diamond is deposited
Any method that can withstand the temperature during cutting may be used for adhesion (brazing is preferred, but an adhesive may also be used.

In addition, when W, Mo, Si, etc., which are used as a substrate for vapor phase synthesized diamond, are applied to this invention, W and Mo have poor adhesion and cannot be used as tools.

Further, in the case of Si, it cannot be used because it is easily damaged.

As mentioned above, a vapor phase synthesized diamond cutting tool is fabricated by using SiC or 5isN4 as a substrate, forming a polycrystalline diamond film on the substrate by vapor phase synthesis, and bonding this together with the substrate onto the cutting tool base. can do.

In the case of a coating tool that directly forms a diamond film on a cemented carbide, it is not possible to form a thick diamond film, and the current state is that the diamond film is generally coated with a thickness of several μm. This poses a problem in that for work materials such as high Si-containing M alloy, wear progresses quickly and the cemented carbide base is exposed, making it impossible to expect a long tool life.

Since the coefficient of thermal expansion of SiC and 5isNa is relatively close to that of diamond, it is possible to form a thick diamond film.In addition, by forming a thick film, it is possible to eliminate sharp edges, which are difficult with coated tools. It is now possible to process the cutting edge.

Further, cemented carbide is cheaper than SiC or 5isN4, and according to the present invention, the tool manufacturing cost can be lower than a coated tool formed by directly coating a tool base of SiC or 5isN4. In addition, it is possible to cut the substrate obtained by one film deposition and adhere it to the cutting edge of many tool bases. For this reason, the present invention is more effective for tools with long cutting edges and large dimensions. Regarding the tool base, depending on the cutting conditions, high-speed steel or the like can be used in addition to cemented carbide, and in this case, the tool manufacturing cost can be further reduced.

The thickness of the polycrystalline diamond film to be formed is preferably 20 uyrr or more and 100 μm or less. This is because if the amount of flank wear due to cutting exceeds the thickness of the diamond, it will reach the substrate and the wear will progress rapidly.
The lower limit of the thickness of diamond is 20 μm. 10 more
This is because if the thickness exceeds 0 μm, the adhesion between the substrate and the diamond film decreases and peeling may occur, making it impossible to maintain performance.

Basically, the thickness of the SiC or 5iJ4 substrate may be such that a diamond film can be formed by vapor phase synthesis. If it is too thin, a phenomenon of warping of the substrate will occur during film formation, making it impossible to form a uniform diamond film. On the other hand, if it is too thick, it will cause problems in tool manufacturing. From such a thing,
The thickness of the substrate is preferably 0.5 mm or more and 2 mm or less. More preferably, it is 0.5 mm or more and 1 mm or less.

Furthermore, as for the film quality of the formed polycrystalline diamond, it is preferable that the intensity ratio of the amorphous carbon to the intensity of the crystalline diamond measured by Raman spectroscopy is 0.25 or less. 0
．． When it exceeds 25, the proportion of amorphous carbon components is high (this results in a marked decrease in wear resistance and a large amount of wear during cutting).
This is because the performance as a diamond cutting tool will no longer be recognized.

<Example) Example 1 Next, the present invention will be explained in detail using examples.

Using the microwave plasma CVD method, methane/hydrogen was placed on SiC at a volume ratio of 2/100, and the pressure was 100 Torr.
, 3011 m of polycrystalline diamond was deposited under conditions of a substrate temperature of 850°C. This is a cemented carbide tool base (SP
G422) was vacuum-brazed and the blade was treated to produce a vapor-phase synthetic diamond cutting tool (sample A).

In order to evaluate the performance of this cutting tool, cutting tests were conducted under the following conditions using an Af-17%Si alloy round bar with four axially extending grooves formed on its outer circumferential surface as the workpiece. carried out.

Cutting speed: 400m/min Feed rate: 0.2mm/r
ev.

Depth of cut: 0.1 mm In addition, for comparison, cutting tools made using Si and Mo as substrates in the same manner (Samples B and C), a cemented carbide cutting tool (Sample D), and a diamond sintered cutting tool (Sample E) was prepared and the same cutting test was conducted. The results are summarized and presented in the first review.

As shown in Table 1, the vapor-phase synthetic diamond cutting tip (sample A) according to the present invention exhibited performance equivalent to that of the diamond sintered cutting tool (sample E).

Example 2 Polycrystalline diamond was deposited on a 5isN4 substrate under the two conditions shown in Table 2 using the filament CVD method.
Im film was formed.

As measured by Raman spectroscopy, the ratio of the intensity of amorphous carbon to the intensity of diamond was 0.08 for sample X and 0.31 for sample Y.

A vapor-phase synthetic diamond cutting tool was fabricated by brazing these onto a cemented carbide and attaching a blade. In order to evaluate these cutting performances, a cutting test was conducted under the cutting conditions shown in Table 3. Sample The amount of surface wear was 45 um.

When the surface roughness of the workpiece cut with sample X was measured, it was found that Rmax = 5.5 lIm, and it was visually rough. Therefore, after polishing the diamond film of sample X, a tool was prepared and a cutting test was conducted, and the surface roughness of the workpiece was improved to Rmax=2.3 μm.

Table 1 <Effects of the Invention> As explained above, according to the present invention, the conventional problems such as the adhesion and life of diamond-coated tools can be solved, and the tool can be inexpensive, have a long life, and can be treated with cutting edges. A phase-synthetic diamond cutting tool can be produced, and AN-
It has been found to be particularly effective for cutting light alloys such as Si alloys.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a cutting tool obtained by the present invention, and FIG. 2 is a partially enlarged view of FIG. 1. l... Vapor phase synthesis diamond film 2... Substrate 3... Tool base 4...
Adhesive layer applicant's representative Patent attorney Kazu 1) Showa Figure 2

Claims (5)

[Claims] (1) Using SiC or Si_3N_4 as a substrate, a polycrystalline diamond film was formed on it by vapor phase synthesis, and the substrate was bonded to the cutting edge of the cutting tool base with the diamond film forming surface serving as the rake surface. A characteristic vapor-phase synthetic diamond cutting tool. (2) The thickness of the polycrystalline diamond film is 20 μm or more10
The vapor phase synthesized diamond cutting tool according to claim 1, characterized in that the diameter is 0 μm or less. (3) Claim (1) characterized in that the intensity ratio of the amorphous carbon to the intensity of the diamond is 0.25 or less in the measurement of the polycrystalline diamond film by Raman spectroscopy.
) Vapor-phase synthesized diamond cutting tool described. (4) Thickness of SiC or Si_3N_4 substrate is 0.5
Claim (1) characterized in that the length is not less than mm and not more than 2 mm.
) Vapor-phase synthesized diamond cutting tool described. (5) The vapor-phase synthetic diamond cutting tool according to claim (1), which is capable of processing diamond cutting edges.