JP3013448B2 - Polycrystalline diamond cutting tool and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycrystalline diamond cutting tool which is most suitable for finishing non-ferrous metals and noble metals and has high fracture resistance, and a method for producing the same.

[0002]

2. Description of the Related Art Diamond is used as a cutting tool or a wear-resistant tool because of its high hardness and thermal conductivity. However, polycrystalline diamond has the disadvantage of being cleaved,
In order to suppress this disadvantage, for example, Japanese Patent Publication No. 52-12
As described in Japanese Patent Publication No. 126, a diamond sintered body obtained by sintering diamonds using an ultra-high pressure sintering technique has been developed.

[0003] However, since these diamond sintered bodies contain 5% to 10% of a binder, there has been a problem that chipping occurs in units of constituent particles.

[0004] Therefore, instead of the diamond sintered compact, a cutting tool using a polycrystalline diamond containing no binder, that is, a polycrystalline diamond formed by a low-pressure vapor phase method as a tool material has been devised by the present inventors. . An example of such a cutting tool made of polycrystalline diamond is disclosed in Japanese Patent Laid-Open No. 1-212767. FIG. 7 is a sectional structural view of a cutting edge portion showing an example of such a polycrystalline diamond cutting tool. In this polycrystalline diamond cutting tool, a polycrystalline diamond chip 3 is fixed on a surface of a tool support 4 via a brazing portion 5.
The chip 3 uses a polycrystalline diamond layer synthesized on the surface of a substrate 1 such as silicon (Si) using a low-pressure vapor phase method. The polycrystalline diamond layer has excellent wear resistance because the polycrystalline material does not contain a binder.

[0005]

However, when the cutting edge 9 of the polycrystalline diamond cutting tool is formed with a sharp edge, there is a problem that initial chipping occurs.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to solve the above-mentioned problems, and an object of the present invention is to provide a polycrystalline diamond cutting tool capable of suppressing the occurrence of initial defects and a method for manufacturing the same.

[0007]

SUMMARY OF THE INVENTION A polycrystalline diamond cutting tool according to the present invention uses polycrystalline diamond formed by a low-pressure vapor phase method as a tool material. The polycrystalline diamond has a rake face and a flank face, and the cutting edge formed along the intersection line of the rake face and the flank face is subjected to honing by laser and covered with a graphite layer.
It has an overturned curved surface.

[0008] A polycrystalline diamond cutting tool according to the present invention is manufactured as follows. First, polycrystalline diamond is deposited on the surface of a substrate by a low-pressure vapor phase method. Next, after cutting the polycrystalline diamond on the base material into a predetermined chip shape, the base material is removed from the polycrystalline diamond chips. Then, the side surface of which has been in contact with the substrate of the polycrystalline diamond tip surface and the tool rake face, forms a by Ri cutting edges to form a flank so as to form the rake face at a predetermined angle . And the blade tip
And honing using a laser, to form a curved surface.

[0009]

[Action] cutting edge of polycrystalline diamond cutting tool according to the present invention, honing treatment using the laser processing is performed. By using laser processing, honing processing of the cutting edge is performed in a state where chipping of the cutting edge is minutely suppressed. The honed edge is made of graphite.
The loss at the initial stage of cutting is suppressed as compared with the coated and sharp edge.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional structural view of a polycrystalline diamond cutting tool according to one embodiment of the present invention and an enlarged view of a cutting edge portion. The polycrystalline diamond tip 3 is firmly attached to a tool support 4 made of cemented carbide or steel via a brazing portion 5. Polycrystalline diamond tip 3
Constitutes a tool rake face 6, and a flank 7 is formed at a predetermined angle with the rake face 6. A cutting edge 9 is formed at a portion along a line of intersection between the rake face 6 and the flank face 7. The cutting edge 9 is formed on a curved surface having a predetermined curvature that has been subjected to honing. A graphite coating layer 8 generated during honing is formed on the surface. Here, the honing amount used in “Claims” is defined. That is, in the enlarged view of the cutting edge in FIG. 1, the honing amount L is a length from the intersection of the extension of the tool rake face 6 and the extension of the flank 7 to the end of the rake face 6 or the end of the flank 7. L. The honing amount L is preferably in the range of 5 to 20 μm. When the honing amount L is 5 μm or less, the improvement of the initial chipping property cannot be obtained, and when it is 20 μm or more, the edge of the cutting edge is damaged and the roughness of the finished surface decreases.

Next, the manufacturing process of the polycrystalline diamond cutting tool shown in FIG. 1 will be described. 1 to 6
FIG. First, referring to FIG. 2, a polycrystalline diamond 2 is formed on a surface of a base material 1 made of a metal or an alloy by using a low-pressure vapor phase method. The surface of the substrate 1 is finished to a mirror surface having a surface roughness of 0.1 μm or less in a maximum height display _Rmax . As a method of depositing polycrystalline diamond on this surface, the following low-pressure vapor phase method is used. That is, a method of decomposing and cooling the source gas using thermionic emission or plasma discharge, or a film forming method using a combustion flame is effective. As the raw material gas, for example, a mixed gas mainly containing an organic carbon compound such as hydrocarbons such as methane, ethane, and propane, alcohols such as methanol and ethanol, and esters, and hydrogen is generally used. In addition, an inert gas such as argon, oxygen, carbon dioxide, water, and the like may be contained in the raw material as long as the synthesis reaction of diamond and its characteristics are not impaired. The polycrystalline diamond is synthesized on the surface of the substrate 1 by such a low-pressure vapor phase method so that the average crystal grain size becomes 0.5 to 15 μm.
When the grain size of the polycrystalline diamond is specified, when used as a cutting tool, the abrasion resistance is reduced when the grain size is finer than 0.5 μm, and when the grain size is coarser than 15 μm. This is because it is easy to lose. In order to reduce the internal pressing force of polycrystalline diamond, the substrate 1 preferably has a coefficient of thermal expansion close to that of diamond. For example, molybdenum (Mo), tungsten (W), silicon (Si) ).

Next, referring to FIG. 3, a cutting line is formed in the polycrystalline diamond layer 2 formed on the base material 1 by a laser beam 10 along a predetermined tool material shape.

Further, referring to FIG. 4, chemical treatment is performed with hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid or a mixture thereof to dissolve base material 1 and remove it from polycrystalline diamond.
If the thickness of the polycrystalline diamond tool material 3a formed in these manners in the laminating direction is 1 mm or more, the blade edge forming process can be performed as it is, and it can be used as a tool by clamping it to a holder. Also, if the thickness is 0.05
If it is １1 mm, it may be used as a cutting tool having a structure joined to a tool support made of cemented carbide or steel. In the case of a cutting tool having a structure joined to such a tool support, the thickness of the polycrystalline diamond tool material 3a is 0.05
When the thickness is smaller than mm, the strength as a tool material is reduced, and the material is easily broken. In such a joining type cutting tool, a thickness of about 1 mm is sufficient for general use. In addition, as shown in FIG. 5, these structures are such that the polycrystalline diamond tool material 3 and the tool support 4 are combined with the tool support 4 such that the surface joined to the base material becomes the rake face 6. It is essential that they be joined after brazing.

Further, referring to FIG. 6, a flank 7 which forms a predetermined angle with the rake face 6 is formed by using a fine diamond grindstone or the like. Then, honing of the cutting edge is performed using a laser beam. Since this laser processing is processing accompanied by a thermochemical reaction, the damage to the cutting edge is less than that of grinding, which is a mechanical removal method. Further, the graphite coating layer 8 is formed on the cutting edge 9 by this laser processing.
The thickness of the graphite coating layer 8 is preferably 0.5 to 10 μm. On the other hand, the thickness of the graphite coating layer 8 is 0.
It is difficult to make the thickness 5 μm, and if it is 10 μm or more, the damage to the cutting edge is increased and the fracture resistance is reduced. Specific Example By microwave plasma CVD method,
S whose surface is a mirror surface of Rmax of 0.05 μm.
Polycrystalline diamond was synthesized on the i-substrate for 10 hours. The synthesis was performed under the following conditions.

[0016] After the synthesis, the substrate was immersed in hydrofluoric acid to dissolve and remove only the Si substrate, so that the average crystal grain size was 5 μm and the thickness was 0.2 mm.
Could be recovered. Also,
The surface of the polycrystalline diamond on the substrate side has a roughness of Rmax.
Was 0.05 μm. This polycrystalline diamond,
The growth surface side was used as a bonding surface to perform brazing with a cemented carbide shank. Next, a throw-away tip (model number: SPGN120304) was produced by grinding the joined body with a # 1500 diamond grindstone. In addition, the obtained indexable insert (A) had a tip of 10 μm.

The cutting edge of the throw-away insert manufactured by the same method as described above was processed with a YAG laser to a processing amount L of 10 μm.
m honing treatment. In the obtained indexable tip (B), a graphite coating layer having a thickness of 3 μm was formed in the honing portion by laser processing, and the chipping of the cutting edge was as good as 2 μm.

Each of these throw-away chips is 10
Each of them was manufactured, and the performance was evaluated under the following conditions.

(Cutting conditions) Work material: A390-T6 (A1-17% Si) Four V-shaped grooves formed in the axial direction of a round bar Cutting speed: 500 m / min Cutting depth: 0 .2 mm Feeding speed: 0.1 mm / rev. Coolant: water-soluble oil As a result, 5 chips (A) are 5 minutes after cutting, and 3
8 minutes after cutting, and the remaining 2 pieces had defects 20 minutes after cutting. On the other hand, the chip (B) according to the present invention did not cause any damage to the cutting edge even after cutting all the chips for 60 minutes, and a good work surface was obtained. From this result, it was clarified that the insert according to the present invention was a cutting tool having high toughness.

[0020]

As described above, by honing the cutting edge of a polycrystalline diamond tool by laser processing, a polycrystalline diamond cutting tool having excellent fracture resistance and high toughness can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of a cutting edge portion of a polycrystalline diamond cutting tool according to the present invention.

FIG. 2 is a first process diagram of a manufacturing process of the polycrystalline diamond cutting tool according to the present invention.

FIG. 3 is a second process diagram of the manufacturing process of the polycrystalline diamond cutting tool according to the present invention.

FIG. 4 is a third process diagram of the manufacturing process of the polycrystalline diamond cutting tool of the present invention.

FIG. 5 is a fourth process chart of the manufacturing process of the polycrystalline diamond cutting tool of the present invention.

FIG. 6 is a fifth process chart of the manufacturing process of the polycrystalline diamond cutting tool of the present invention.

FIG. 7 is a sectional structural view of a cutting edge portion of a conventional polycrystalline diamond cutting tool.

[Explanation of symbols]

 Reference Signs List 1 base material 2 polycrystalline diamond layer 3 diamond tip 4 tool support 5 brazing part 6 rake face 7 flank face 8 graphite coating layer 9 cutting edge part 10 laser beam

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23B 27/20 B23B 27/14 B23P 15/28

Claims (11)

(57) [Claims] 1. A polycrystalline diamond cutting tool using polycrystalline diamond synthesized by a low-pressure vapor phase method , wherein a cutting edge formed along a line of intersection between a rake face and a flank of the tool is a laser. honing by processing is given, the graphite layer
A polycrystalline diamond cutting tool having a curved surface coated with . 2. The honing amount of the cutting edge is 5 μm.
The polycrystalline diamond cutting tool according to claim 1, which is not less than 20 µm. 3. The graphite layer has a thickness of 0.5 μm or more and 10 μm or more.
μm or less, the polycrystalline diamond cutting tool according to claim 1 or claim 2. 4. The polycrystalline diamond cutting tool according to claim 1, wherein the average diameter of the polycrystalline diamond is 0.5 μm or more and 10 μm or less. 5. A polycrystalline diamond cutting tool formed by using polycrystalline diamond synthesized by a low-pressure vapor phase method as a tool material and joining the tool material to a tool support, wherein the rake face of the tool and the relief The cutting edge formed along the line of intersection with the surface is honed by laser and the graphite layer
A polycrystalline diamond cutting tool having a curved surface coated with . 6. The honing amount of the cutting edge is 5 μm.
The polycrystalline diamond cutting tool according to claim 5, having a diameter of not less than m and not more than 20 µm. 7. The graphite layer has a thickness of 0.5 μm to 10 μm.
μm or less, the polycrystalline diamond cutting tool according to claim 5 or claim 6. 8. The polycrystalline diamond has an average particle size of:
The polycrystalline diamond cutting tool according to any one of claims 5 to 7, wherein the diameter is not less than 0.5 µm and not more than 15 µm. 9. The polycrystalline diamond cutting tool according to claim 5, wherein a thickness of the polycrystalline diamond in a direction substantially perpendicular to the rake face is 0.05 mm or more and 1 mm or less. 10. A step of depositing polycrystalline diamond on a surface of a base material by a low-pressure vapor phase method, and cutting the polycrystalline diamond on the base material into a predetermined chip shape. A step of removing from the crystal diamond chip, the surface of the side of the polycrystalline diamond chip which was in contact with the base material is a tool rake surface, and a flank is formed so as to form a predetermined angle with the rake surface. A method for manufacturing a polycrystalline diamond cutting tool, comprising: a step of forming a cutting edge portion by forming; and a step of honing the cutting edge portion to form a curved surface. 11. The method for producing a polycrystalline diamond cutting tool according to claim 10, wherein the honing of the cutting edge is performed using a laser.