JPH0426961B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a cutting tool for cutting, and particularly to a cutting tool capable of mirror-cutting a highly hard iron-based material.

[Background of the invention]

2. Description of the Related Art Cutting tools using single crystal diamond in the cutting edge are known as cutting tools for precision cutting, mirror cutting, etc. of non-ferrous metal materials such as aluminum and copper.

When cutting ferrous materials such as hardened carbon steel or stainless steel with a diamond-based cutting tool, the cutting heat causes the diamond to react with the iron and form carbide, which causes the diamond to deteriorate. The wear becomes severe and normal cutting becomes impossible.

For this reason, cutting of iron-based materials uses a cutting tool in which a cutting edge is formed in a polycrystalline sintered body obtained by sintering boron nitride crystals. This cutting tool has a structure as shown in FIG. 1, for example.

That is, a chip 3 made of a polycrystalline sintered body is attached to a shank 1 via a base 3. A chamfer 1 and a flank 5 are formed on the cutting edge of the chip 3. With such a cutting tool, even if the flank surface 5, which affects the roughness of the cut surface, is polished to 0.05 μm Rmax or less, the roughness of the cut surface will be 0.1 μm Rmax.
The mirror surface was the limit.

The reason for this is that in the chip 3 made of a polycrystalline sintered body as shown in FIG. This is because the sharpness cannot be ensured due to the microchipping 10 of the binder 9.

[Purpose of the invention]

An object of the present invention is to provide a cutting tool that eliminates the drawbacks of the above-mentioned prior art and enables more advanced mirror cutting of iron-based materials.

[Summary of the invention]

In order to achieve the above object, the present invention has the cutting edge of a cutting tool made of a cubic crystal of single-crystal boron nitride, and the rake face and flank face of the cutting edge are respectively formed to be appropriate crystal planes of the cubic crystal. It is characterized by what it did.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows a typical crystal habit of cubic boron nitride, which has the greatest hardness among the boron nitride single crystals used in the present invention. All triangular and hexagonal faces in these single crystals are {111} planes.

FIG. 4 to FIG. 6 show an example of the manufacturing process of a cutting tool according to the present invention. Shyank 1
A mortar-shaped hole 12 is formed at one end of the hole 1, and a brazing filler metal 13 is supplied to the bottom of the hole 12.
On this brazing material 13, a boron nitride single crystal 14 is placed.
Place. Then, heat the shank 11,
While melting the brazing filler metal 13, the single crystal body 14 is pressurized in the axial direction of the shank 11, and a portion of the single crystal body 14 is press-fitted into the shank 11 (see FIGS. 4 and 5). Next, after cooling the shank 11 and solidifying the brazing filler metal 13, the shank 11 is
At the same time, the single crystal is ground and polished to form a flank face 5 and a rake face 6 so that the cutting direction is in the <100> direction of {110} or the <112> direction of {111}, as shown in FIG. , as a cutting tool.

In the above embodiment, a brazing material 13 such as silver solder is used to bond the boron nitride single crystal 14 and the shank 11, but since the single crystal 14 has poor wettability with metal, It is preferable to form a titanium coating on the single crystal body 14 by means such as plating. Further, the shank 11 may also be formed of a titanium-based material.

7 and 8 are cutting tools that are formed in the same process as the above embodiment and differ only in the shape of the cutting edge from the cutting tool shown in FIG. 6, and in FIG. 7, the cutting direction is {110} The <100> direction of the surface, FIG. 8 shows the cutting tool of the present invention in which the cutting direction is the <112> direction of {111}.

That is, the flank face 5 of the single crystal body 14 attached to the shank 11 is a cylindrical face, and the rake face 9 is a flat face, forming a sharp cutting edge 7.

Using this cutting tool, the hardness of the hardened
As a result of cutting HRC52 chromium alloy stainless tool steel, the cut surface was mirror-finished over 1 m ² with a surface roughness of 0.05 μm Rmax.

This is because the cutting edge of the cutting tool is made of single crystal 14.
The machined surface roughness can be improved by eliminating the microchipping that occurs in conventional cutting tools.

Note that the cubic boron nitride single crystal has a cleavage property similar to the diamond single crystal. The crystal plane that is particularly susceptible to cleavage is the {110} plane. For this reason, if the crystal orientation of the flank surface of the cutting tool is not selected appropriately,
Cleavage of the crystals progresses wear on the flank surface, causing chipping at the edge of the cutting edge, reducing the surface roughness of the cut surface.

That is, if the {100} crystal plane is used as a relief surface, chipping is likely to occur from any direction and it cannot be used as a relief surface.

Also, the <100> direction of the {110} crystal plane,
Since the <112> direction of the {111} plane is the cutting direction that applies compressive force to the {110} plane, which is the cleavage plane, there is less wear and chipping is less likely to occur.

In addition, the expression of the above crystal plane and the direction on the crystal plane is based on the general crystallographic expression method, and when it indicates the direction perpendicular to the crystal plane {XYZ} which is perpendicular to the crystal plane. , the Miller index of the crystal plane {XYZ} is denoted as the <XYZ> direction. That is,
The <100> direction of the {110} plane is the {100} direction on the {110} plane.
The direction perpendicular to the {111} plane is shown.
The 11> direction indicates a direction perpendicular to the {211} plane on the {111} plane.

Therefore, as a cutting tool, assuming that both the clearance angle and the rake angle are approximately 0 degrees, in order to set the cutting direction to the <100> direction of the {110} plane, the rake face should be set to the {100} plane of the crystal plane, The flank face is {110} of the crystal plane.
Or, in order to make the cutting direction the <112> direction of the {111} plane, the rake face is the {211} plane of the crystal plane, and the flank face is the {111} plane of the crystal plane. Compressive force is applied to the {110} plane, which is the cleavage plane of boron nitride, and the type of wear that occurs only on the flank face is not chipping but abrasion wear, and a cutting tool with less wear can be obtained.

Incidentally, a plurality of cutting tools shown in the above embodiments may be attached to a tool holder and several places may be processed simultaneously.

Moreover, it can also be used for milling by being planted in a tool holder like a top-blade face milling cutter.

9 and 10 illustrate the crystal orientation of the cutting tool of the present invention using the diagram of single crystal CBN shown in FIG. 3b. In Figure 9, the rake face 9 is the {100} crystal plane, and the flank face 5 is the {110} crystal plane.
FIG. 10 shows the case where the rake face 9 is the {211} crystal plane, and the flank face 5 is the {111} crystal plane.

[Effects of the Invention] As described above, according to the present invention, iron-based materials can be cut to a good mirror surface with a cut surface roughness of 0.5 μm Rmax.

[Brief explanation of drawings]

FIG. 1 is a side view of a conventional polycrystalline tool, FIG. 2 is an enlarged view of the tip of a conventional polycrystalline tool, and FIG. 3 is an enlarged view showing the crystal habit of a cubic boron nitride single crystal. 4 to 6 show the manufacturing process of a cutting tool according to the present invention, in which FIG. 4 is a perspective view showing a single crystal of boron nitride embedded in the shank, and FIG.
The figure is an enlarged sectional view showing the main part of Fig. 4, Fig. 6 is an enlarged view showing the tip of the cutting blade as a cutting tool, and Fig. 7 is a first embodiment of the cutting tool according to the present invention. An explanatory diagram showing an example, FIG. 8 is an explanatory diagram showing a second embodiment of the cutting tool according to the present invention, and FIGS. 9 and 10 are explanatory diagrams of the crystal orientation of the cutting tool of the present invention. 11...Shank, 14...Boron nitride single crystal.

Claims (1)

[Scope of Claims] 1. A cutting tool comprising a chip on which a cutting edge for cutting is formed and a shank for holding this chip, in which the cutting edge of the chip is made of a cubic crystal of monocrystalline boron nitride. By making the rake face of the cutting edge the {100} plane of the cubic crystal and the flank face of the cutting edge the {110} plane of the cubic crystal, the cutting direction is set to the {110} plane. A cutting tool characterized by being oriented in the 100> direction. 2. A cutting tool consisting of a chip on which a cutting edge for cutting is formed and a shank for holding this chip, in which the cutting edge of the chip is formed of a cubic crystal of monocrystalline boron nitride, and the cutting edge is By making the rake face of the part the {211} plane of the cubic crystal and the flank surface of the cutting edge the {111} plane of the cubic crystal, the cutting direction is made to be the <112> direction of the {111} plane. A cutting tool characterized by: