JP2533049B2 - Diamond tools - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond tool using polycrystalline diamond.

[0002]

2. Description of the Related Art In precision machining of mechanical parts and the like, there is a case where a machined surface having fine irregularities is required without requiring surface roughness up to a mirror surface. For example,
In order to improve the adhesion of the photoconductor layer, a part of the substrate of the electrophotographic photoconductor requires an uneven surface having a surface roughness of 0.2 μm to 1 μm, which is rougher than the mirror surface. .

Conventionally, a tool using single crystal diamond such as natural diamond has been used as a tool for processing a highly accurate finished surface such as a mirror surface.

However, a tool using this single crystal diamond is extremely expensive, and the cutting edge is sharp and has a very good sharpness, so that when a surface roughness of about 1 μm is to be obtained, the cutting edge shape becomes It is regularly transferred to the work piece along with the feed pitch, and since the pitch of the irregularities is rough, the adhesion of the photoreceptor layer is deteriorated.

On the other hand, a tool using polycrystalline diamond for the cutting edge tip can be formed at a relatively low cost compared to single crystal diamond, but since the tip is composed of many diamond crystals, Large irregularities exist on the cutting edge from the beginning due to the step of the crystal interface or the falling of the crystal. Therefore , when machining a workpiece , the finished surface roughness varies widely from tool to tool and the surface roughness is 1 μm or less. However, there is a problem that it is not stable.

[0006] Also in polycrystalline diamond tools, if we repeat the process, unevenness of the cutting edge is reduced by wear of the cutting edge, there are cases where surface finish is improved, surface roughness from the machining initial Since the surface roughness fluctuates until the surface roughness becomes stable, the processing performance is not stable, and the workpiece until the surface roughness becomes stable is wasted.

On the other hand, as a method for treating a cutting edge of a diamond tool for obtaining a good finished surface, there is a conventional Japanese Patent Publication No. 3-75.
Japanese Patent No. 282 proposes a method of polishing a flank of a diamond tip to a state without polishing marks, and then polishing a rake surface to finish a cutting edge.

However, the above method is effective for a single crystal diamond tip capable of forming a sharp cutting edge by polishing, but a large unevenness is formed on the cutting edge due to a step at the crystal interface like a polycrystalline diamond tip. In the case of a chip having a groove, even if the flank face and the rake face are polished, large irregularities remain on the cutting edge, and good finishing roughness cannot be obtained.

Therefore, an object of the present invention is to provide a diamond tool which can stably obtain a finished surface having a surface roughness of 0.2 to 1 μm by using low-cost polycrystalline diamond.

[0010]

In order to achieve the above object, the present invention is a diamond tool in which a diamond tip made of polycrystalline diamond is held on a shank, and the flank of the cutting edge of the diamond tip has no polishing marks. is formed on the polished surface, as well as smooth the cutting edge chamfered in minute width by grinding to the cutting edge, the
The width of the chamfer is set to the diamond forming diamond tip.
More than twice the average grain size of the crystal and 1-20 μm
The configuration is set within the range.

In this structure, the unevenness of the cutting edge is
It is preferable that the thickness is 0.1 to 0.6 μm.

[0012]

In the above structure, the relief surface is a surface having no polishing marks, so that the minute waviness of the cutting edge is reduced .
By chamfering the cutting edge by a small width, large irregularities on the cutting edge are removed . At this time, the chamfer
The width of is more than twice the average grain size of diamond crystals
Therefore, even if the crystal particles fall off, they will not be transferred to the finished surface.
Difficult to remove, and the unevenness of the finished surface disappears (see below
(See the description of FIG. 5). Therefore, large irregularities due to shedding of the polycrystalline diamond unique crystal interface of a step or crystals, is removed in the cutting edge Rutotomoni, unevenness of the cutting edge transfer
It becomes difficult to be processed, and a finished surface having a uniform surface roughness can be obtained from the beginning of processing.

In the above structure, in order to obtain a surface roughness of about 0.2 to 1 μm, the unevenness of the cutting edge after chamfering should be 0.
It is preferable to set it in the range of 1 to 0.6 μm. Surface roughness of cutting edge
About 2 times the surface roughness of the material to be ground appears.
It

The chamfering width is in the range of 1 to 20 μm.
The reason is that the cutting resistance becomes large when it exceeds 20 μm.
Cause problems with tool life and surface / shape accuracy.
On the other hand, if it is less than 1 μm, the average diamond crystal is
Since the diameter is about 0.5 μm, it meets the above double requirement.
Because I don't get it. It is preferably in the range of 5 to 10 μm
Good.

[0015]

1 and 2 show a diamond tool according to an embodiment. In the figure, reference numeral 1 is a diamond tip made of polycrystalline diamond. The diamond tip 1 is joined to an insert 2 of cemented carbide or the like, and the insert 2 is fixedly held to the tip of a shank 3.

As shown in FIG. 1, the diamond tip 1 has a main cutting edge 5 which is inclined at a required angle with respect to a workpiece 4.
And a sub cutting edge 6 facing the surface of the workpiece 4 at a slight inclination angle α, and a required clearance angle β is formed on the clearance surface 7 as shown in FIG. In addition, the above insert 2
Instead of the method of joining the diamond tip 1 using, the pressing metal fitting may be attached to the shank 3, and the diamond tip may be detachably attached to the shank via the pressing metal fitting.

3 and 4 show a portion of the diamond tip 1 near the cutting edge. The diamond tip 1 is formed by polishing the rake face 8 in advance and then polishing the flank face 7 while holding it on the shank 3 so that no polishing marks remain. This polishing is performed, for example, with grain size # 8.
This is performed by pressing a grinding wheel of No. 00 on the flank and grinding while feeding in a direction different from the polishing direction.

With the flank 7 thus polished,
Although the minute waviness of the cutting edge in the flank is considerably suppressed, microscopically, due to the bonding structure of the diamond crystals forming the diamond tip 1, the cutting edge has a structure as shown in FIG.
As shown in (a) , large unevenness exists due to a step or the like at the crystal interface of each diamond crystal 9.

Therefore, next, the cutting edge of the diamond tip 1 is brought into contact with a grinding wheel with a grain size of # 1500, and the average grain size of the diamond crystal 9 is twice or more, and 1 to 2
The chamfering 10 is performed with a minute width t in the range of 0 μm. By carrying out this chamfering 10, the cutting edge of the chip 1 has the unevenness due to the falling of the respective diamond particles coming in and out as shown by the diagonal lines in FIG. 5 (a) removed, and as shown in FIG. 5 (b).
A smooth cutting edge 11 having no waviness or unevenness is formed at the boundary portion a between the chamfer 10 and the flank 7 by the grinding process.

At this time, the diamond tip 1 is generally
Produced by sintering, the content of diamond crystal 9 is
85 to 90% by volume and containing Co or the like as a binding metal
And a bond between the diamond crystals 9
Only genus intervenes. Therefore, as shown in Figure (c)
The sharper the cutting edge 11 is,
There is less hugging of bonded metal per crystal (abrasive grain) 9.
Therefore, the abrasive grains 9 easily fall off. The dropout point b is the same figure
As shown in (d), it appears as a concave portion of the cutting edge 11, and it appears as a recess.
It is transferred (appears) to the ground surface of the ground object. Be transcribed
In that case, it is not possible to obtain a satisfactory finished surface.

On the other hand, the width t of the chamfer 10 is
If the average grain size of the crystal 9 is twice or more, the result is shown in Fig. 5 (b).
As shown in FIG.
Even if there is a drop, in the direction of the width t on the surface of the chamfer 10,
The crystals 9 almost always exist and perform the grinding action. For this reason,
There is no transfer of the concave portion b, and a smooth finished surface is obtained.

Therefore, the cutting edge 11 is entirely
Since it is almost smooth and there are minute irregularities consisting of many diamond crystal boundaries on the surface, when it is processed, it does not reach a mirror surface but a surface roughness close to it is obtained and a uniform finished surface is obtained. It can be stably formed from the beginning of processing.

Also, the length L of the chamfer 10(See Figure 3)
Depends on the auxiliary cutting edge 6 of the diamond tip 1 and the cutting conditions.
Set within the range that affects the finished surface roughness,
For example, if the feed rate is about 0.1 mm / rev, the chamfer length
The length L is set to about 1.5 mm.

Since the width and length of the chamfer 10 are extremely small as described above , the chamfer 10 does not have to be an accurate linear surface in the polishing process in which the grinding wheel is brought into contact with the cutting edge of the chip for a short time. Instead, as shown in FIG.
And the curved surface 13 are combined. That is, the chamfer 10 mentioned here includes a chamfer formed only by a straight surface and a curved surface, and a chamfer formed by combining a straight surface and a curved surface.

The degree of unevenness of the cutting edge 10 formed by polishing the flank 7 and chamfering 10 is preferably about half the finished surface roughness to be obtained. For example, to obtain a surface roughness of 0.2 μm to 1 μm,
The unevenness of the cutting edge 11 is preferably set in the range of 0.1 μm to 0.6 μm.

<Experimental example> In order to see the effect of the present invention, a cutting comparison test was carried out between the diamond tool of the example and the conventional product.

The product A of the present invention used in the cutting test uses a diamond tip having an average grain size of diamond crystals of about 0.5 μm. In the structure shown in FIGS. 3 and 4, the inclination angle α of the auxiliary cutting edge 6 is The clearance angle β was formed to be 1 to 3 ° and 20 °. In the chamfer 10, the width t was 5 μm, the length L was 1.5 mm, the angle γ was 45 °, and the unevenness of the cutting edge 11 was formed in the range of 0.1 μm to 0.6 μm.

On the other hand, the conventional product has three types (B,
C, D) are prepared, diamond tips each made of polycrystalline diamond having the same average grain size as the product A of the present invention are used, and flanks and rake surfaces of the tips are ground to form cutting edges, Except for the chamfer 10, the cutting edge shape was the same.

The workpiece used for the cutting test was an electrophotographic photosensitive drum (diameter φ80 mm, thickness 1.2 mm, total length 35).
5 mm) and the material was aluminum alloy AL5000 series for the photosensitive drum substrate.

The cutting conditions are as follows: rotation speed 3000 rp
m, feed rate 0.1 mm / rev, and depth of cut 0.01 mm.

FIG. 7 shows changes in the finished surface roughness of the product A of the present invention in the cutting test, and FIG. 8 shows the conventional products (B, C, D).
The test result in is shown.

As shown in FIG. 8, the finished surface roughness of the conventional product B varies widely from the beginning to the end of processing, and the surface roughness of the conventional products (C and D) is stable at a processing distance of 200 km. The work up to that point was wasted, and the productivity was reduced.

On the other hand, as shown in FIG. 7, the product A of the present invention has a value of 0.
It was possible to obtain a stable finished surface roughness of 4 μm to 0.5 μm and perform highly accurate cutting.

[0034]

As is evident from the foregoing description, the present invention is a chamfer with facilities to polishing and cutting edge flank to the tip of polycrystalline diamond, set the width of the chamfer in a certain range <br/> Since a smooth cutting edge is obtained by doing so, a finished surface having a uniform surface roughness can be stably obtained from the beginning of processing. Therefore, the conventional break-in process is no longer required,
Surface processing with a desired surface roughness can be performed by using a low-priced multi-bonded diamond tip, and there is an effect that the processing cost can be reduced and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a diamond tool of an embodiment.

FIG. 2 is a side view of the above.

FIG. 3 is an enlarged plan view showing the vicinity of a cutting edge of a diamond tip.

4 is a sectional view taken along line IV-IV in FIG.

[5] Each view schematically showing the crystal structure of the cutting edge

FIG. 6 is an enlarged sectional view showing a chamfer of a cutting edge .

FIG. 7 is a graph showing changes in finished surface roughness of the product of the present invention in a cutting test.

FIG. 8 is a graph showing changes in finished surface roughness in the conventional product as above.

[Explanation of symbols] 1 diamond tip 3 shank 5 main cutting edge 6 sub cutting edge 7 flank face 8 rake face 9 diamond crystal (abrasive grain) 10 chamfer 11 cutting edge

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masao Hata 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Corporation Hachioji Business Office (72) Inventor Toyoji Toyoji 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Corporation Hachioji Business Office (72) Inventor Takami Hashimoto 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Corporation Hachioji Plant (72) Inventor Kazushi Obata 2-80 Hobokucho, Sakai City Osaka Diamond Industrial Co., Ltd. (72) Inventor Hideo Maeda 2-80 Hohokita-cho, Sakai City, Osaka Diamond Industry Co., Ltd. (56) Reference JP-A-6-194857 (JP, A) JP-A-60-80504 (JP, A) JP-A-59-182005 (JP) , A) JP 63-144903 (JP, A) JP 2-109611 (JP, A) JP 4-240007 (JP, A)

Claims (2)

(57) [Claims] 1. A diamond tool diamond chip 1 held in the shank 3 of polycrystalline diamond, formed on SL cutting edge flank 7 of the diamond tip 1 with no grinding marks a polishing surface, the cutting edge 11 smoothing the cutting edge 11 chamfered 10 of minute width by polishing the
The width t of the chamfer 10 is
The average grain size of the diamond crystals 9 forming the tip 1 is 2
It is more than double and set in the range of 1 to 20 μm.
Diamond tool to collect. 2. The unevenness of the cutting edge 11 is 0.1 to 0.6.
The diamond tool according to claim 1, wherein the diamond tool has a thickness of μm.