JP2881876B2 - Diamond coated cutting tool and cutting edge finishing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a diamond-coated cutting tool in which a diamond coating layer is formed on a substrate surface by a vapor phase synthesis method, and a method for finishing a cutting edge portion thereof.

[Conventional technology]

Since diamond has high hardness and has a property of hardly reacting with soft metals such as Al and Cu, these soft metals are used as cutting tools suitable for high-speed cutting of soft materials such as plastics.

As such a diamond cutting tool, a single crystal diamond tool in which a single crystal diamond cutting edge is attached to a base material and a sintered diamond tool obtained by sintering fine diamond at a high temperature and a high pressure have been conventionally put into practical use. It is used heavily for the processing of Al alloys.

However, these diamond cutting tools are disadvantageous in that they are expensive and difficult to apply to cutting tools having complicated shapes such as cutting chips with breakers.

On the other hand, in recent years, it has become possible to synthesize a diamond thin film from a low-pressure gas phase by a gas phase synthesis method. Therefore, instead of single crystal diamond tools and sintered diamond tools that are not suitable for expensive and complicated shaped cutting tools, take advantage of the vapor phase synthesis method that can easily coat diamond thin films on complex shaped substrates, A diamond-coated cutting tool provided with a diamond coating layer on the surface of a tool-shaped substrate is expected as a new inexpensive diamond tool.

However, diamond synthesized by the vapor phase synthesis method has a low content of amorphous carbon and has high crystallinity, so that a crystal face having a clear ridge line (a so-called self-shaped face) appears on the surface, resulting in a rough surface. . For this reason, the cutting edge of the diamond-coated cutting tool is not smooth, and the cutting edge is inferior and the work surface of the work material is also inferior to those of the single crystal diamond tool and the sintered diamond tool.

Even if a diamond tool hardly adheres to a work material of a soft material, a diamond-coated cutting tool in which a crystal face having a clear ridgeline appears on the surface as described above, the ridge and the ridge of the cutting edge surface. Since the work material enters between them, welding is more likely to occur as compared with a single crystal diamond tool or a sintered diamond tool, and the tool life is short.

[Problems to be solved by the invention]

In view of such a conventional situation, the present invention is applicable to a cutting tool having a complicated shape, and the finished surface of a work material is as inexpensive as a single crystal diamond tool or a sintered diamond tool, and at a low cost. An object of the present invention is to provide a diamond-coated cutting tool having a long tool life.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a diamond-coated cutting tool having a diamond coating layer formed on a substrate surface by a vapor phase synthesis method, wherein the edge of the cutting edge other than the rake face and the flank side of the edge are within 0.1 mm. The surface of the diamond coating layer is smoothed to a surface roughness Rmax of 0.5 μm or less.

Further, as a method of finishing the cutting edge portion to obtain such a diamond-coated cutting tool, the edge of the cutting edge other than the rake face and the diamond coating layer surface within 0.1 mm flank side of the edge from the edge, a brush having abrasive abrasive particles attached. The surface is smoothed to a surface roughness Rmax of 0.5 μm or less without exposing the substrate.

[Operation] The disadvantage of the diamond-coated cutting tool, such as that the finished surface of the work material is inferior to a single-crystal diamond tool or a sintered diamond tool, has a clear ridge line that appears on the surface of the diamond coating layer. It is considered that the problem can be solved by smoothing the crystal plane.

As a means for smoothing the surface, it is conceivable to apply a lap finish by skif polishing or the like, as is usually performed for a single crystal diamond tool or a sintered diamond tool, but the processing cost is high, and the diamond coating cutting is expensive. The advantage of low cost that is unique to tools is lost. Furthermore, according to the vapor-phase synthesis method capable of coating even a complex-shaped base material surface, a diamond-coated cutting tool having a complicated shape such as a cutting chip with a breaker or a drill can be provided at a low cost, but the lapping using a lapping machine is not possible. It is difficult to process cutting tools with complicated shapes.

Therefore, the present inventors consider that the edge of the cutting edge and the smoothness of the flank in the vicinity of the edge as a seed determine the superiority of the finished surface of the work material. We concluded that brush polishing is the most suitable means to handle cutting tools with different shapes.

In the present invention, in particular, the edge and the flank side of the edge are brush-polished among the cutting edge portions. However, since the polishing is performed by a brush, the edge 1 and the flank 2 side are actually used as shown in FIG. In addition, the rake face 3 is slightly polished at the same time. However, the polishing of the rake face 3 is essentially unnecessary and is not included in the polishing range or the smoothing range in the present invention.

In the diamond-coated cutting tool of the present invention, at least the edge 1 of the cutting edge and the surface of the diamond coating layer 4 on the flank 2 near the edge are smoothed as described above, so that the finished surface of the work material is made of single-crystal diamond. The finished state is improved to a level almost equal to that of tools and sintered diamond tools.

In order to obtain the effect of the present invention, it is necessary to smooth the edge 1 and at least 0.1 mm of the flank 2 side from the edge 1 to a surface roughness Rmax of 0.5 μm or less.
However, even if the area exceeding 2 mm on the flank 2 side from the edge 1 is polished, ordinary cutting has no effect.

Moreover, not only does the welding with the work material hardly occur,
The effect of suppressing the peeling of the diamond coating layer was also recognized, and it was confirmed that the tool life could be prolonged synergistically. Further, since the brush honing is simple, it is possible to cope with a cutting tool having a complicated shape, and there is an advantage that the processing cost is much lower than that of lapping.

The material of the abrasive grains to be attached to the brush includes diamond, cubic boron nitride (C-BN), alumina (Al
₂ O ₃ ), chromium oxide (Cr ₂ O ₃ ), etc. are preferred, but the use of diamond or C-BN in particular provides good polishing efficiency. Regarding the particle size of the abrasive grains, if the particle size is too fine, the polishing efficiency is poor. Is preferred. In order to efficiently obtain a smooth surface, it is effective to use a coarse-grained brush first and then a fine-grained brush. It is also effective to use brushes having different wire diameters and strengths in accordance with the shape of the cutting tool and to change the depth at which the polishing portion enters the brush in order to perform polishing appropriately and efficiently.

〔Example〕

Example 1 Using a W-filament CVD apparatus, a cutting chip of model number SPGN 12030 containing Si ₃ N ₄ as a main component (manufactured by Sumitomo Electric Industries, Ltd.)
NS 130) was used as a substrate, and a diamond coating layer was formed on the surface thereof to produce a diamond-coated cutting chip. The surface of the substrate is scratched using a # 270 electrodeposition grindstone, the filament temperature is 2200 ° C, the distance between the filament and the substrate is 7 mm, and the surface temperature of the cutting edge of the chip as the substrate is 970 ° C.
H ₂ 1000 SCCM, CH as raw material gas in the reaction vessel
_A film was formed at a pressure of 80 torr while introducing 47 SCCM, and a 7-μm-thick diamond coating layer was obtained by a reaction for 12 hours. The crystal grain size on the surface of the diamond coating layer is 4 to 7 μm,
The surface roughness Rmax was 1.8 μm.

For the purpose of comparison, this diamond coated cutting chip and a sintered diamond cutting chip (Sumidia DA 150 manufactured by Sumitomo Electric Industries, Ltd.) and a single crystal diamond cutting chip (Sumicrystal One Use manufactured by Sumitomo Electric Industries, Ltd.) of the same model number for comparison. Perform a cutting test of pure Al using a chip)
The surface finish of the work material was evaluated. Cutting conditions are V = 40
Dry cutting at 0 m / min, f = 0.1 mm / rev, d = 0.1 mm.
The surface roughness Rmax of the work material after cutting for 1 minute was 5.6 μm for the diamond-coated cutting chip, 4.2 μm for the sintered diamond cutting chip, and 3.1 μm for the single-crystal diamond cutting chip. Also, the finished surface of the work material by the sintered diamond cutting chip and the single crystal diamond cutting chip has a beautiful metallic luster close to a mirror surface, whereas the diamond coated cutting chip has a slightly whitish appearance.

Next, as shown in FIG. 2, the diamond-coated cutting tip 5 is fixed to a revolving turntable 6, and a rotating polishing brush 7 to which diamond abrasive grains of # 400 are adhered is pressed to lightly grind it. Finish polishing was performed with a rotating polishing brush to which 1200 diamond abrasive grains were attached, and the surface of the diamond coating layer including the edge of the cutting blade and the flank near the edge was smoothed while taking care not to expose the substrate. The edge of the obtained cutting edge and the polished surface including at least 0.1 mm on the flank side of the edge became a state close to a glossy mirror surface, and its Rmax was 0.4 μm.

When a cutting test similar to the above was conducted using the diamond-coated cutting tip according to the present invention, the surface roughness Rmax of the work material was 4.1 μm, and the metal was finished to have a beautiful metallic luster close to a mirror surface. A finished surface comparable to that of the chip and the single crystal diamond cutting chip was obtained.

Example 2 Using a W-filament CVD apparatus, a diamond coating layer was formed on a cemented carbide micro drill having a diameter of 2.0 mm (IGETALLOY micro drill TN 200 manufactured by Sumitomo Electric Industries, Ltd.), and six diamond coating drills were formed. Was prepared. Set the filament temperature at 2200 ° C, the distance between the filament and the drill tip at 15mm, and the surface temperature at the drill tip at 980 ° C.
7.5S to 500SCCM and CH ₄ and H ₂ as the raw material gas into the reaction vessel
The film was formed at a pressure of 40 torr for 8 hours while introducing with a CCM to obtain a diamond coating layer having a thickness of about 5 μm at the tip of the drill. The crystal grain size on the surface of the diamond coating layer is 3-5 μm,
The surface roughness Rmax was 1.1 μm.

Of the obtained diamond coating drills, three drill tips were polished with a rotating brush to which # 1500 diamond abrasive particles were adhered so as not to expose the base material, and the edge of the cutting blade and the escape near the edge were removed. The surface of the diamond coating layer including the surface was smoothed. The edge of the obtained cutting edge and the polished surface including at least 0.1 mm on the flank side from the edge are in a state close to a glossy mirror surface, and the Rmax is 0.3.
μm.

Using three diamond-coated drills subjected to the above polishing treatment and three unpolished diamond-coated drills, four glass epoxy multilayer substrates are drilled under cutting conditions of N = 2000 rpm and F = 2000 mm / min. The test was performed. Three uncoated diamond coated drills produced smears (insulation failure on multi-layer substrate) at 1860 hits, 2010 hits and 2130 hits, resulting in tool life, whereas the polished diamond coated drills had 3740 hits. There was no smearing up to 3920 hits and 4060 hits, and the tool life was extended about three times.
In a similar drilling test using a cemented carbide microdrill used as a substrate, the tool life was reached at 400 hits.

〔The invention's effect〕

According to the present invention, it is applicable to a cutting tool having a complicated shape, and the finished surface of the work material is comparable to that of a single crystal diamond tool or a sintered diamond tool. By eliminating the diamond coating layer and suppressing the peeling of the diamond coating layer, a diamond-coated cutting tool having a longer tool life than before can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cutting edge portion of a diamond-coated cutting tool according to the present invention, and FIG. 2 is a schematic perspective view of a brush polishing apparatus used in Example 1. DESCRIPTION OF SYMBOLS 1 ... Edge, 2 ... Flank surface 3 ... Rake surface, 4 ... Diamond coating layer 5 ... Cutting tool, 6 ... Turntable 7 ... Polishing brush

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23B 27/14 B23P 15/28

Claims (3)

(57) [Claims] 1. A diamond-coated cutting tool having a diamond coating layer formed by a vapor phase synthesis method on a substrate surface, wherein the edge of the cutting edge other than the rake face and the diamond coating layer surface within 0.1 mm on the flank side of the edge are: Surface roughness R
The diamond-coated cutting tool as described above, which is smoothed to a maximum of 0.5 μm or less. 2. The edge of the cutting edge and the flank side 2 mm from the edge
The surface of the diamond coating layer within
The diamond-coated cutting tool according to claim 1, wherein the cutting tool is smoothed. 3. A diamond-coated cutting tool having a diamond coating layer formed on a substrate surface by a vapor phase synthesis method, wherein the edge of the cutting edge other than the rake face and the diamond coating layer surface within 0.1 mm on the flank side from the edge are formed by: A method for finishing a cutting edge portion of a diamond-coated cutting tool, wherein the surface is smoothed to a surface roughness Rmax of 0.5 μm or less without using a polishing brush to which abrasive grains are attached.