JPH0379206A - Single crystal silicon carbide cutting tool - Google Patents

Abstract

PURPOSE:To enable long life without dispersion and give performance which can substitute for diamond by using a single crystal silicon carbide manufactured by a chemical vapor growth method for a cutting edge to be used for cutting of a soft metal. CONSTITUTION:A single crystal SiC used for a single crystal silicon carbide cutting tool which is suitable for precision cutting of a relatively soft material such as an aluminum alloy is a single crystal of an alpha type or a beta type of SiC manufactured by a chemical vapor growth method (CVD), and the size is usually in the range of 5 to 15mm though adjusted according to the dimension of the cutting tool. This CVD SiC is machined to have a SiC cutting edge 1 with the thickness of about 1mm and brazed to a notch part of a table 2 obtained through machining of a cemented carbide (K-10). This is fixed to a cutting tool backing material 3 through a screw 4. This single crystal SiC has a sufficient life for use in cutting and polishing of a soft metal, little dispersion and performance which can substitute for diamond.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a single crystal silicon carbide cutting tool suitable for precision cutting relatively soft materials such as aluminum, aluminum alloys, copper, and copper alloys. .

[Conventional technology]

Conventionally, natural or artificial single-crystal diamond, which has the highest hardness in nature, has been used for precision machining tools.

Since diamond is made of carbon, it has some problems such as being unsuitable for machining ferrous materials that react under high temperatures during cutting, but it has a high hardness that cannot be compared with anything else, so it can be used despite the above drawbacks. used regardless.

Furthermore, recently, the use of highly accurate cutting and polishing of relatively soft materials such as hard disks, polygon mirrors, and reflectors has been rapidly increasing. Diamond is also used as the cutting tool material for these cutting operations because it has sufficient hardness and can produce single crystals of a size suitable for use.The amount of diamond single crystals used for cutting is It is increasing every year.

[Problem to be solved by the invention]

However, as the amount of diamond used increases, there will be a shortage of natural diamond single crystals, and artificial diamond single crystals will cause problems such as the difficulty of producing large ones.

In addition, when the lifespan of a diamond tool is expressed in terms of the number of hard disks processed, the average value is 500 to 1000 pieces/
Regarding books, the individual numbers range from a few pages to 2,000 pages/book.

Although the reason for this is not clear, it is thought that the lifespan is not simply determined by hardness, but that other factors are also involved, such as the presence or absence of defects in the crystal, imperfections in the cutting direction, etc.

The present inventors believed that if the workpiece is made of a relatively soft material such as aluminum or copper, it does not need to be an unnecessarily hard material, and therefore conducted extensive research on materials that could be substituted for diamond. As a result, it was thought that SiC, which has recently been studied as a coating using the CVD method, could be used as a substitute for diamond.

Conventionally, the claw-shaped SiC single crystals produced by the Acheson method cannot be used as cutting tools because they have interfold properties.

The present invention has been made based on the above idea, and an object of the present invention is to provide a single crystal SiC cutting tool that can cut relatively soft metal with a long life and a life with little variation.

[Means to solve the problem]

In order to achieve the above object, the single crystal SiC according to the present invention
In the cutting tool, single crystal SiC manufactured by a vapor phase growth method is used for the cutting edge.

The single-crystal SiC used in the present invention is an α-type or β-type single crystal of SiC grown by chemical vapor deposition (CVD), and the size is adjusted depending on the size of the bite. Usually ranges from 5 to 15 m1+ in diameter.CV
The temperature at which SiC single crystals are grown by method D is 1800℃.
α type at ~2000°C, β type at 1600~1800°C
type of SiC, but especially large ones can be obtained in the α type.

Bits of various sizes are made using the SiC single crystal described above, and examples of them are shown in Fig. 1 (a) and (b).
As shown in the figure, the above CvD-8iC is processed to have a thickness of about 1
A SiC blade l of mm is made, and this is made of cemented carbide (K-10
) is brazed to the cutout part of the processed base 2. This is fixed to the bite base material 3 with screws 4.

In this case, rake face 5 is Q O1 clearance angle 6 is 5° corner 7
is R; 0.4mm, corner 7.7 interval is 1,5v
*m, the width of the base material 3 is 3.51.

The above CvD-8iC is a SiC produced by the conventional Acheson method.
Single crystal exhibits strong interfolding properties and is completely unthinkable for use as a cutting tool blade, whereas it has almost no interfolding properties and can be used as a cutting tool.

In addition, since the SiC mentioned above is made by the CVD method, the impurities are less than 1 ppm, the density of SiC is more than 3.51 (theoretical value is 3.52), and the edge can be cut in any direction with a diamond tool. can be easily polished.

Furthermore, since SiC is oxidation resistant and virtually does not oxidize up to about 1500° C., by obtaining a single crystal SiC tool, it becomes possible to perform cutting under heating if necessary.

An example of producing SiC using the above CVD method is as follows.

That is, as shown in FIG. 2, a graphite container 12' containing a raw material 12 containing graphite mixed with Sin is placed at the bottom of the reaction container 11, and a predetermined interval is placed above this.
A base material 13 made of graphite or sintered SiC is supported and disposed by a support stand or a support rod 13b.

Next, the pressure inside the reaction vessel 11 is reduced to 0.1 to 2.0 Torr, and the raw material chamber 12a containing the raw material 12 is heated to 17
00 to 2000°C, and the temperature of the storage deposition chamber 13a of the base material 13 is set to a predetermined temperature within the range of 1600 to 1900'c.

In this case, to obtain α-type crystals, the base material 13 is positioned at the bottom so that precipitation is carried out at a high temperature, and for β-type crystals, the base material 13 is positioned above as indicated by the two-dot chain line so that the precipitation temperature is slightly lower. Make it lower.

As a result, from the raw material 12 in the raw material chamber 12a, S tO
, +C+S io+cO , the Si source is vaporized.

In the precipitation reaction in the precipitation chamber 13a, when the base material is carbon, the reaction of sio+2c→SiC+CO mainly occurs, but even when the base material is not carbon, Si
Since C is generated, the CO gas generated in the raw material chamber 12a is converted into 2CO, ->C+GO, in the precipitation chamber.

As a result, C is precipitated, and it is presumed that a reaction of 2SiO+2C→2 Si C+ Ot is also occurring.

One method for obtaining SiC single crystals by the CVD method is to use single crystal SiC particles produced by the Acheson method as seeds, for example SiC of about 0.5 to 1a++++, on a substrate and scatter them at intervals of about 10 mm. Then, grow on this seed.

In this manner, by waiting for the reaction for a predetermined period of time, a single crystal of a predetermined size with almost no interfolds can be obtained.

In the above method, α-type SiC is produced at a raw material chamber temperature of 1900 to 2100.
°C1 precipitation chamber temperature 1800-2000°C1β type: raw material chamber temperature 1800-2000°C1 precipitation chamber temperature 1600-2000°C
Obtained at 1800°C.

The ratio of 5iot and C in the raw materials is 5iO-1 mole, C
Approximately 1 mole.

In this case, if high-purity Sin and graphite are used as the raw material 12, single-crystal SiC with a total impurity content of 1 ppm or less can be obtained, and various operating conditions can be kept constant through severe automatic control. As a result, single crystals with few defects can be stably produced.

〔Example〕

α type and β type with a diameter of 5 mm made by the above CVD method.
A cutting tool blade was cut out from the SiC single crystal of the mold so that the specified orientation (orientation of the rake face) could be obtained, and by changing the orientation of the rake face of the blade, the flat blade type cutting tool shown in Figure 1 (a) and (b') was created. was created.

Using this cutting tool, an aluminum (5-inch, hard disk) substrate containing 4 wt% magnesium was machined on a high-precision lathe, and the roughness of the cut surface was Rnax 0.0.
The number of pieces that could be processed to 7 μm was counted as the life of the cutting tool.

The cutting conditions were: ■ Work rotational speed 4,000 rprn ■ Blade depth of cut 15 μm ■ Blade feed 30 μm/Rev.

The life test was conducted using 10 bites each, and the distribution and average were determined. The results are shown in Table 1.

Table 1

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) show an example of a single-crystal SiC tool according to the present invention, and FIG. 1(a) is a plan view,
Figure (b) is a 1-1 line arrow view of Figure 1 (a), Figure 2 is a
FIG. 1 is a schematic explanatory diagram of an apparatus for manufacturing CvD-8iC single crystals. [Effects of the Invention] As described above, the single crystal SiC bit according to the present invention has a sufficient lifespan when used for cutting and polishing soft metals, and
In addition, it has little variation, has performance that can replace diamond, and can be made inexpensively by synthesis, so it will make an extremely large contribution to the field of cutting hard disks, which will continue to grow. 1...SiC blade, 2...pedestal, 3...
...Bite base material, 4...Screw, 5...
...su(face, 6... relief angle, 7...
Corner, 11... Reaction vessel, 12...
Raw material (S iOz + graphite), 12 a---- Raw material room, 12°...Graphite container, 13...
Base material, 13a...Precipitation chamber, 13b...
Support platform or support rod.

Claims (1)

[Claims] A single-crystal silicon carbide cutting tool characterized in that the cutting edge uses single-crystal silicon carbide produced by a chemical vapor deposition method.