JPH06170435A - Diamond drawing die and manufacture thereof - Google Patents

Abstract

PURPOSE:To make strength, wear resistance and heat resistance excellent by containing vapor phase synthetic diamonds which are precipitated by vapor phase synthesis and having the finest structure in a part where is brought into contact with a wire to be drawn in the vapor phase synthetic diamond. CONSTITUTION:This die is a diamond drawing die 9 containing the diamonds which are provided so as to be brought into contact with the wire to be drawn. The diamonds include the vapor phase synthetic diamonds 7 which are precipitated by vapor phase synthesis and the vapor phase synthetic diamonds have the finest structure in the part where is brought into contact with the wire to be drawn. The diamond drawing die 9 which is obtained in such a manner is excellent in strength, wear resistance and heat resistance. Thus as the diamonds in the center part of the diamond drawing die are synthesized by vapor phase synthesis method, the cost of production is minimized as compared to the case of using a natural diamond and the useful life is longer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond wire drawing die, and more particularly to a diamond wire drawing die containing diamond synthesized by a vapor phase synthesis method and a method for producing the same.

[0002]

2. Description of the Related Art A die is a tool used for wire drawing of metal wires and the like, and generally must have the following characteristics.

Have the strength to withstand the drawing strength. -It has excellent wear resistance.

It can be processed into a suitable structure and shape, and the inner surface can be finished to the maximum. Diamond is an excellent die material having these conditions.

Conventionally, natural diamond or a diamond sintered body has been used as the center of a diamond drawing die.

FIG. 4 is a schematic cross-sectional view showing the internal structure of the hole at the center of a conventional diamond drawing die.

Referring to FIG. 4, the internal structure of the hole portion 15 of the center portion 14 of this diamond wire drawing die is as follows.
6, the throttle unit 17, and the outlet unit 18.

The introduction part 16 comprises a part 19 called an entrance part or a bell part, and an approach part 20. Part 19 called the entrance section or bell section
Is an introduction portion of the wire 21 to be drawn and is provided to facilitate the inflow of the lubricant. The approach portion 20 is provided to stop the vibration of the wire 21 to be drawn, adjust the posture, and facilitate the inflow of the lubricant.

The throttle portion 17 is composed of a reduction portion 22 and a bearing portion 23. The reduction portion 22 is a portion that narrows the wire 21 to be drawn, and is an important portion that determines the performance of the diamond drawing die and the quality of the drawn wire. The bearing portion 23 is a portion that determines the diameter of the wire 21 to be drawn and affects the surface roughness of the drawn wire.

The outlet portion 18 has a back relief portion 24,
And an exit section 25. Back relief 24
Is a portion that reinforces the bearing portion 23 when the wire 21 to be drawn is drawn. The exit part 25 plays a role of a guide work (a work of narrowing the tip of the wire 21 before drawing and passing it through a die).

With reference to FIG. 4, the process of drawing the line 21 to be drawn will be described below.

First, the wire 21 to be drawn is passed through the introduction part 16. The wire 21 to be drawn next comes into contact with the narrowed portion 17, is plastically worked into a wire having a desired shape, wire diameter, and surface roughness, and is drawn out from the outlet 18.

In the wire 21 to be drawn, the wire diameter can be reduced and the physical properties such as the tensile strength of the wire can be improved and the surface roughness of the wire surface can be reduced by this drawing process. It will be improved.

[0014]

However, natural diamond is expensive and its crystal size is limited.
It has the drawback that it is easily cleaved and easily cracked.

Further, although the diamond sintered body overcomes the drawbacks of natural diamond, it has a problem in wear resistance and heat resistance because it contains a binding aid.

For example, when drawing tungsten or molybdenum, tungsten or molybdenum is often drawn at a high temperature in order to improve the drawing workability. However, if the temperature is raised too high, the diamond sintered body has a low heat resistance because it contains a binding aid, and the diamond wire drawing die in which the diamond sintered body is used as the center of the die has a die It is known that the service life of the

Recently, it has become possible to synthesize diamond by a vapor phase synthesis method, and development of applied products making the best use of its characteristics is active. But,
With regard to wire drawing dies, the current situation is that vapor phase synthetic diamond has not been applied in earnest.

When the diamond synthesized by the vapor phase synthesis method is applied to a drawing die, it is generally conceived to simply use the vapor phase synthesized diamond on the substrate as it is.

The diamond wire drawing die using the vapor phase synthetic diamond produced by this method as the central portion of the diamond wire drawing die can be used in a wide range.

However, considering that the vapor-phase synthetic diamond grows in a columnar shape, the narrowed portion of the die has a columnar structure with a relatively large grain size. For this reason,
Like single-crystal diamond, it is likely to be cleaved, has a problem in strength, and is likely to drop diamond grains.

The present invention has been made to solve the above problems, and is excellent in strength, heat resistance and abrasion resistance, and is inexpensive, and a diamond wire drawing die and the manufacture of such a diamond wire drawing die. The purpose is to provide a method.

[0022]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that after the substrate of vapor phase synthesized diamond is removed on the substrate, the diamond plate is used as a substrate. As a result, they have found that a structure suitable for a wire drawing die can be obtained by synthesizing diamond in the direction opposite to the first synthesis, and have completed the present invention.

The structure of the vapor phase synthetic diamond can be controlled to some extent depending on the conditions of the vapor phase synthesis, but a fine grain size uniform structure is realized while maintaining the mechanical properties of diamond. This is extremely difficult to do.

However, when diamond is grown on the substrate by the vapor phase synthesis method, first, minute nuclei are generated, which grow to form a film. The initial diamond grain size can be set to 0.5 μm or less, though it depends largely on the substrate processing conditions and the vapor phase synthesis conditions.

The present inventors have found that this small particle size region is
It has been found that high performance can be expected if the diamond wire drawing die is configured so as to come into contact with the wire to be drawn, and the present invention has been completed.

The diamond wire drawing die of the present invention is
A diamond drawing die comprising diamond provided in contact with a wire to be drawn, the diamond comprising vapor phase synthetic diamond deposited by vapor phase synthesis, the vapor phase synthetic diamond being It is characterized in that the contact portion has the finest structure.

The diamond wire drawing die of the present invention is
Preferably, the average grain size of the vapor-phase synthetic diamond in the portion in contact with the line to be drawn is 30 μm or less.

The method for manufacturing a diamond wire drawing die of the present invention comprises a step of forming a first diamond polycrystal layer on a substrate by a vapor phase synthesis method, a step of removing the substrate, and a first diamond polycrystal body. A second layer is formed on the surface of the layer on the side where the substrate is removed by the substrate removing step by a vapor phase synthesis method.
The step of forming the diamond polycrystal body layer, and the first diamond polycrystal body layer and the second diamond polycrystal body layer in the direction intersecting the bonding surface between the first diamond polycrystal body layer and the second diamond polycrystal body layer. And a step of forming a hole penetrating the diamond polycrystalline layer.

A method for manufacturing a diamond wire drawing die according to the present invention comprises a step of forming a first diamond polycrystal layer on a substrate by a vapor phase synthesis method, a step of removing the substrate, and a first diamond polycrystal body. A second layer is formed on the surface of the layer on the side where the substrate is removed by the substrate removing step by a vapor phase synthesis method.
The step of forming the diamond polycrystal layer, and the first diamond polycrystal with the joint surface as a center plane in the joint surface direction between the first diamond polycrystal layer and the second diamond polycrystal layer. Forming a through hole extending over the body layer and the second polycrystalline diamond layer.

[0030]

The diamond wire drawing die of the present invention contains a vapor phase synthetic diamond in which a diamond provided so as to contact a wire to be drawn is deposited by vapor phase synthesis. This vapor-phase synthetic diamond is
Moreover, since it is made of diamond, it is superior in wear resistance and heat resistance as compared with sintered diamond containing a binding aid, and is less likely to be damaged.

That is, since the vapor-phase synthetic diamond is a diamond containing no binding aid, it can achieve a thermal conductivity close to that of natural diamond, and is therefore superior in heat resistance to a diamond sintered body. Therefore, vapor phase synthetic diamond is suitable as a material for wire drawing dies.

Further, vapor phase synthetic diamond has a fine grain size at the initial stage of growth, but the grain size tends to increase as it grows. Further, according to the present invention, the vapor phase synthetic diamond is configured such that the portion in contact with the wire to be drawn has the finest structure.

However, the area of the part that contacts the line to be drawn varies depending on the thickness of the line to be drawn.

Further, the grain size of diamond at the portion in contact with the line to be drawn also differs depending on the diamond synthesis conditions.

The inventors of the present invention have preferred that the particle size of diamond in the portion in contact with the line to be drawn is smaller, and the average particle size of the vapor phase synthetic diamond in the part in contact with the line to be drawn is 30 μm. In the following cases, it was found that the wire drawing die exhibits excellent performance.
Further, in order to exhibit the performance superior to that of the diamond drawing die in which the diamond sintered body is used, it is preferable that the average particle size of the vapor phase synthetic diamond in the portion in contact with the wire to be drawn is 10 μm or less. We have found that it is preferable.

When diamond is vapor-phase-synthesized, the diamond formed on the substrate has a fine crystal structure at the initial growth stage from the substrate and grows into a columnar shape as it grows to have a large grain size. Tends to become. The diamond wire drawing die of the present invention is a manufacturing method thereof, wherein after forming a first diamond polycrystal layer on a substrate by a vapor phase synthesis method, the substrate is removed and a substrate of the first diamond polycrystal layer is formed. On the surface of the side where
A second diamond polycrystal layer is formed by the vapor phase synthesis method. Therefore, in the first diamond polycrystal layer and the second diamond polycrystal layer, many diamonds having a fine crystal structure are oriented around the bonding surface.

According to the present invention, since the growth of the second diamond polycrystal layer is performed on the surface of the first diamond polycrystal layer on the initial growth side, the second diamond polycrystal layer is Nucleation occurs preferentially at the nucleation position on the surface of the finest fine grain crystal grains of the first diamond polycrystalline layer. Therefore, the second diamond polycrystal layer also starts to grow from fine crystal grains. Therefore,
The first polycrystal diamond layer and the second polycrystal diamond layer are composed of diamond having a fine crystal structure in the vicinity of the bonding surface. Since the diamond is grown on the diamond, the bonding force of this bonding surface is larger than that in the case of sandwiching different kinds of intermediate layers.

In the diamond wire drawing die of the present invention, a large amount of diamond having a fine crystal structure is formed around the joint surface between the first polycrystalline diamond layer and the second polycrystalline diamond layer. However, as a result of forming the hole portion so as to form a portion that contacts the line to be drawn of the narrowed portion, it is hard, and cleavage cracks are less likely to occur,
As a result, scratching wear due to the peeled diamond itself is unlikely to occur, and therefore the wear resistance is excellent.

[0039]

【Example】

Examples 1 and 2 and Comparative Examples 1 and 2 Example 1 FIG. 1 is a process diagram schematically showing an example of a method for manufacturing a diamond wire drawing die of the present invention. Note that FIG.
In each of the steps (101) to (105), the cross-sectional view schematically shows the crystal structure of the vapor-phase synthetic diamond used in the present invention. The shorter the line length, the finer the crystal structure.

With reference to FIG. 1, a method of manufacturing the diamond wire drawing die of the present invention will be described.

In step (101), the first diamond polycrystal layer 2 was formed on the substrate 1 by the vapor phase synthesis method. The first diamond polycrystalline layer 2 was synthesized by the hot filament CVD method using a Si substrate as the substrate 1 and having a film thickness of 500 μm on this substrate. The synthesis was performed under the following conditions.

[0042]

[Table 1]

In step (102), the substrate 1 was removed. The Si substrate on which the first diamond polycrystalline layer 2 was formed was immersed in hydrofluoric nitric acid to dissolve and remove the Si substrate.

In step (103), a second diamond polycrystal layer 4 is synthesized on the surface 3 side of the first diamond polycrystal layer 2 from which the substrate 1 has been removed by a vapor phase synthesis method to form a laminated body. 5 was formed. The second diamond polycrystalline layer 4 is formed on the surface 3 side by the hot filament CVD method.
It was synthesized with a film thickness of 500 μm. The synthesis was performed under the same conditions as those for forming the first diamond polycrystalline layer 2.

In step (104), the laminated body 5 is formed into a desired shape so that the bonding surface 6 between the first polycrystalline diamond layer 2 and the second polycrystalline diamond layer 4 is lateral. The central portion 7 was formed in the size. A laser processing method and a grinding processing method were used for processing the central portion 7.

In step (105), the hole portion 8 is formed in the central portion 7, and the central portion 7 is subjected to laser processing and ultrasonic processing to obtain the first diamond polycrystalline layer 2 and the second diamond polycrystalline layer 2. A hole 8 penetrating the first diamond polycrystal layer 2 and the second diamond polycrystal layer 4 was formed in a direction intersecting the bonding surface with the crystal layer 4.

The central portion 7 of the diamond drawing die formed by the above steps is as shown in FIG.
In the diamond synthesized by the vapor phase synthesis method, the surface side of the narrowed portion 8S of the hole portion 8 penetrating the diamond has the finest structure.

Next, using the center portion 7 having the hole portion 8, a diamond wire drawing die whose cross section is shown in FIG. 2 was prepared.

Referring to FIG. 2, the diamond wire drawing die 9 includes a central portion 7, a reinforcing mount portion 10 and a case 11. The central portion 7 is fixed to the reinforcing mount portion 10, and the reinforcing mount portion 10 is provided. Are brazed and housed in the case 11.

Table 2 shows the standard of the diamond wire drawing die 9.

[0051]

[Table 2]

Embodiment 2 FIG. 3 is a process drawing schematically showing one embodiment of a method for manufacturing a diamond wire drawing die of the present invention.

A method of manufacturing the diamond wire drawing die of the present invention will be described with reference to FIG. Note that FIG.
Example 2 in which the steps are shown in FIG.
Since the steps are the same as those in the first embodiment, the corresponding steps will be designated by the same reference numerals and the description thereof will be omitted.

FIG. 3 shows a second embodiment showing the process, as shown in FIG.
The difference from Example 1 in which the process is shown in FIG. To the desired shape and size so that
This is the point forming the central portion 12.

Then, in step (205), when the hole 13 is formed in the central portion 12, the first layer of the laminated body 5 is formed.
In the direction of the joint surface between the polycrystalline diamond layer 2 of diamond and the second polycrystalline diamond layer 4,
A through hole extending over the first diamond polycrystal layer 2 and the second diamond polycrystal layer 4 is formed to form the hole portion 1
This is the point where 3 is formed.

As is apparent from FIG. 3, the center portion 12 of the diamond wire drawing die formed by the above steps is a diamond synthesized by the vapor phase synthesis method, and the hole portion 13 is provided to penetrate the diamond. The surface side of the narrowed portion 13S has the finest structure. The size and shape of the hole 13 are the same as those of the first embodiment.

Next, a diamond wire drawing die similar to that of Example 1 was prepared except that the central portion 12 having the hole 13 prepared in Example 2 was used. Comparative Example 1 Si was formed by the hot filament CVD method under the same conditions as when the first diamond polycrystalline layer of Example 1 was synthesized.
After synthesizing a diamond polycrystal layer with a thickness of 1 mm on the substrate, dissolving and removing the Si substrate with fluorinated nitric acid, laser processing, grinding processing, and ultrasonic processing were performed to obtain the same shape and size as in Example 1. The center part and the hole part of the diamond drawing die of the standard of the standard were formed, and the same diamond drawing die as in Example 1 was prepared. Comparative Example 2 A diamond wire drawing die similar to that of Example 1 was prepared, except that a sintered diamond having a center portion and a hole portion of a diamond wire drawing die having the same shape and size as those of Example 1 was used.

In order to evaluate the performance of the diamond wire drawing die produced by the above method, a performance test of the diamond wire drawing die was carried out under the following conditions.

As a line to be drawn, a diameter of 0.22
mm stainless steel wire was used.

Drawing was performed at a drawing speed of 50 m / min. Example 1, Example 2, and Comparative Example 2 showed equivalent performance, but Comparative Example 1 lacked.

Next, a more detailed diamond wire drawing die performance test was conducted. As the line to be drawn,
A stainless steel wire having a diameter of 0.22 mm was used and drawn so that the diameter of the stainless steel wire was 0.20 mm.

The drawing speed is 200 m / min,
The extension amount was 4 tons (t). Drawing speed 200m /
At the time when the wire drawing of 4 tons (t) was performed at min, Example 1, Example 2 and Comparative Example 2 exhibited the same performance, but Comparative Example 1 had a defect.

As is clear from the above results, in the diamond wire drawing die of the present invention, the drawn portion of the die is composed of a portion having a finer grain size than that of the diamond wire drawing die in which the vapor phase synthetic diamond is simply used at the center. As a result, it has excellent strength.

Next, drawing was performed at a drawing speed of 80 m / min. In Comparative Example 2, remarkable progress of wear was observed, but in Examples 1 and 2, no problem occurred.

Next, Examples 1, 2 and Comparative Example 2
, A more detailed diamond wire drawing die performance test was conducted.

As a line to be drawn, a diameter of 0.22
Using a stainless steel wire of mm, the diameter of the stainless steel wire was drawn to be 0.20 mm.

The drawing speed is 300 m / min,
The extension amount was 5 tons (t). Drawing speed 300m /
In the comparative example 2, a remarkable progress of wear was recognized at the time when the wire drawing of the drawing amount of 5 tons (t) was performed at min.
In Examples 1 and 2, no problem occurred.

As is clear from the above results, the diamond wire drawing die of the present invention is excellent in heat resistance as a result of not including a bonding aid in the central portion like the diamond sintered body wire drawing die, and the drawing speed It is possible to raise.

Examples 3 to 4 Examples 3 to 4 show examples carried out in order to find a preferable range of the grain size of the vapor phase synthetic diamond in the portion in contact with the line to be drawn of the diamond drawing die. There is.

Example 3 A diamond wire drawing die similar to that in Example 1 was prepared.

First, a first diamond polycrystalline layer having a film thickness of 500 μm was synthesized on a Si substrate. The synthesis was performed on a Si substrate scratched with 0.5 μm diamond powder in order to increase the nucleus generation density under the following conditions.

[0072]

[Table 3]

Next, the Si substrate on which the first diamond polycrystal layer was formed was immersed in hydrofluoric nitric acid to dissolve and remove the Si substrate.

Next, S of the first diamond polycrystalline layer
A second diamond polycrystal layer having a film thickness of 500 μm was synthesized on the surface side from which the i substrate was removed, that is, on the growth initial surface side of the first diamond polycrystal material layer. In addition, the synthesis is
The same conditions were used to form the first diamond polycrystalline layer. As a result, a material (laminate) for wire drawing die having a thickness of 1 mm was obtained.

FIG. 5 shows the material for this wire drawing die (hereinafter referred to as
A type A) particle size distribution chart is shown.

Using type A, processing was performed in the same manner as in Example 1 to prepare a diamond drawing die having the same standard as in Example 1.

Example 4 The same as Example 3 except that the conditions for vapor phase synthesis of the first diamond polycrystal layer and the second diamond polycrystal layer were changed. I made a die.

First, a first diamond polycrystal layer having a film thickness of 500 μm was synthesized on a Si substrate. The synthesis was performed on a Si substrate scratched with 40 μm diamond paste under the following conditions.

[0079]

[Table 4]

Next, the Si substrate on which the first diamond polycrystalline layer was formed was immersed in hydrofluoric nitric acid to dissolve and remove the Si substrate.

Next, S of the first diamond polycrystalline layer
A second diamond polycrystal layer having a film thickness of 500 μm was synthesized on the surface side from which the i substrate was removed, that is, on the growth initial surface side of the first diamond polycrystal material layer. In addition, the synthesis is
The same conditions were used to form the first diamond polycrystalline layer. As a result, a material (laminate) for wire drawing die having a thickness of 1 mm was obtained.

FIG. 6 shows the material for this drawing die (hereinafter referred to as
A type B particle size distribution chart is shown.

Using type B, processing was carried out in the same manner as in Example 1 to prepare a diamond wire drawing die of the same standard as in Example 1.

Referring to FIGS. 5 and 6, the portion where the type A line to be drawn contacts (the region indicated by C in FIG. 5) is the portion where the type B line to be drawn contacts. (A region shown by C in FIG. 6) is composed of a finer diamond.

In order to evaluate the performance of the diamond wire drawing dies produced in Examples 3 and 4, a performance test of the diamond wire drawing dies was carried out under the following conditions.

As a line to be drawn, a diameter of 0.22
Using a stainless steel wire of mm, the diameter of the stainless steel wire was drawn to be 0.20 mm.

The drawing speed is 200 m / min,
The extension amount was 4 tons (t). In the diamond drawing die using type A, the grain size of the diamond at the portion in contact with the line to be drawn was about 5 μm, whereas in the diamond drawing die using type B, the line to be drawn The particle diameter of the diamond at the portion in contact with was about 50 μm.

After completion of the above performance test, there was no problem in the diamond wire drawing die using the type A, but in the diamond wire drawing die using the type B,
A defect was found in a part of the type B diamond grains used in the center.

According to the above performance test, the smaller the diamond grain size of the portion where the wire to be drawn contacts is,
It was found to be preferable as a die material.

As a result of conducting various tests similar to those in Examples 3 and 4, the average grain size of the vapor-phase synthetic diamond in the portion in contact with the line to be drawn is 30 μm.
It has been found that the following is preferable. In addition, it has been found that the average particle size of the vapor phase synthetic diamond in the portion in contact with the wire to be drawn is preferably 10 μm or less in order to exert the performance of the diamond sintered body drawing die or higher.

Also, depending on the line to be drawn, the first
It is important to optimize the crystal structure of the vapor phase synthetic diamond in the portion in contact with the line to be drawn by changing the synthesis conditions of the diamond polycrystal layer of No. 2 and the second polycrystal diamond layer. I found out.

In this embodiment, only the hot filament CVD method is shown as a method for synthesizing diamond by vapor phase synthesis, but various low pressure vapor phase methods can be used for synthesizing such vapor phase synthetic diamond. Can be applied. For example, a method of decomposing / exciting a raw material gas by utilizing thermoelectron radiation or plasma discharge, or a film forming method using a combustion flame can be applied.

As the raw material gas, for example, hydrocarbons such as methane, ethane and propane, alcohols such as methanol and ethanol, or organic carbon compounds such as esters are mixed with hydrogen as a main component. Gas or the like can be used. In addition to these, an inert gas such as argon, oxygen, carbon monoxide, water or the like may be mixed in the raw material within a range that does not impair the synthetic reaction of diamond and its characteristics.

The diamond wire drawing die of the present invention is
In addition to gold, silver, platinum and other precious metal wires, copper, brass, phosphor bronze, brass coated iron wire, nickel wire, stainless wire, tungsten wire, molybdenum wire, etc.
It can also be suitably used for nozzles for chemical fibers and for squeezing tin or vinyl.

Further, in this embodiment, step (102)
In the above, a chemical method is used as the step of removing the substrate 1. However, such a substrate 1 may be separated or removed by mechanical processing or separation / dissolution by a chemical treatment. It is not limited to the embodiment.

Further, in the diamond wire drawing die of the present invention, since the central portion is formed of the vapor phase synthetic diamond, the first portion is formed so that the narrowed portion has the finest structure.
The film thickness of the diamond polycrystal layer and the film thickness of the second diamond polycrystal layer can be adjusted by changing the conditions of vapor phase synthesis. Therefore, according to the material of the wire to be drawn and the shape of the hole at the center, which varies depending on the wire diameter, the crystal structure of the vapor phase diamond in the portion in contact with the wire to be drawn should have the finest structure. Can be configured to have.

The vapor phase synthetic diamond has a non-diamond component (mainly amorphous carbon) depending on its synthesis condition.
Is often included. In such a case, the wear resistance is significantly reduced, and the applicable range of the wire drawing die material is limited. Therefore, it should be noted that care must be taken not to include a large amount of non-diamond components.

[0098]

As described in detail above, according to the present invention, the central part of the diamond drawing die is the vapor phase synthetic diamond, and the vapor phase synthetic diamond is in contact with the line to be drawn. As a result of the parts being configured to have the finest structure, the diamond wire drawing die according to the present invention is excellent in strength, wear resistance and heat resistance.

Further, according to the present invention, the diamond at the center of the diamond drawing die is synthesized by the vapor phase synthesis method, and as a result, the production cost can be kept lower than when natural diamond is used.

Further, the diamond wire drawing die according to the present invention is excellent in strength, abrasion resistance and heat resistance and, as a result, has a long service life.

[Brief description of drawings]

FIG. 1 is a process drawing schematically showing an embodiment of a method for manufacturing a central portion of a diamond wire drawing die according to the present invention.

FIG. 2 is a cross-sectional view schematically showing a diamond wire drawing die prepared in Example 1.

FIG. 3 is a process drawing schematically showing an embodiment of a method for manufacturing the central portion of the diamond wire drawing die according to the present invention.

FIG. 4 is a cross-sectional view schematically showing the internal structure of a hole in the center of a diamond drawing die.

FIG. 5 shows a particle size distribution chart of the material for wire drawing dies prepared in Example 3.

FIG. 6 shows a particle size distribution chart of the material for wire drawing dies prepared in Example 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 First diamond polycrystal layer 3 Side from which substrate 1 is removed 4 Second diamond polycrystal layer 5 Laminated body 6 Bonding surface 7, 12, 14 Center part 8, 13, 15 Hole part 8S, 13S , 17 Drawing part 9 Diamond wire drawing die 10 Reinforcing mount 11 Case 16 Introductory part 18 Exit part 19 Entrance part or bell part 20 Approach part 21 Line to be drawn 22 Reduction part 23 Bearing part 24 Back relief part 25 Exit part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoji Fujimori 1-1-1 Kunyokita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works

Claims (4)

[Claims] 1. A diamond drawing die comprising diamond which is provided so as to come into contact with a line to be drawn, said diamond comprising vapor phase synthetic diamond deposited by vapor phase synthesis, said vapor phase synthetic diamond being , A diamond wire drawing die, characterized in that the part in contact with the wire to be drawn has the finest structure. 2. The diamond drawing die according to claim 1, wherein an average particle size of the vapor-phase synthetic diamond in a portion in contact with the wire to be drawn is 30 μm or less. 3. A step of forming a first diamond polycrystalline layer on a substrate by a vapor phase synthesis method, a step of removing the substrate, a step of removing the substrate of the first diamond polycrystalline layer. A step of forming a second diamond polycrystalline layer on the surface removed by the substrate removing step by a vapor phase synthesis method; the first diamond polycrystalline layer and the second diamond polycrystalline layer; And a step of forming a hole penetrating the first diamond polycrystal layer and the second diamond polycrystal layer in a direction intersecting a bonding surface of the diamond drawing die. 4. A step of forming a first diamond polycrystal layer on a substrate by a vapor phase synthesis method, a step of removing the substrate, and a step of removing the substrate of the first diamond polycrystal layer. A step of forming a second diamond polycrystalline layer on the surface removed by the substrate removing step by a vapor phase synthesis method; the first diamond polycrystalline layer and the second diamond polycrystalline layer; In the direction of the joint surface between the first polycrystalline diamond layer and the second diamond polycrystal layer.
And a step of forming a through hole extending over the diamond polycrystal layer of 1.