JPS62230421A - Tool made of synthetic single crystal diamond - Google Patents

Abstract

PURPOSE:To prolong the service life of a wire drawing die and to reduce the price by forming a single crystal whose two parallel facets are a crystal face 110 by cutting a synthetic diamond and boring a hole vertical to the two parallel facets. CONSTITUTION:A small single crystal whose both top and bottom faces are a regular polygon or a circle and parallel crystal faces 110 is formed by cutting a diamond synthesized under superhigh pressure and temp. A die hole is vertically bored through the top and bottom facets, the shape of the facets is formed to be symmetrical to the central axis of the die hole and sides of the facet are formed in parallel with the central axis. In that method, a wear resistance of the crystal is more improved in comparison with a crystal whose parallel facets are a crystal face 100 or 111; the former crystal has symmetrical two facets and parallel sides to the central axis, so that the effect preventing eccentric wear of the hole is obtained and the price per piece is reducible.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a metal wire drawing die, a high aqua regia spray nozzle, etc., in which an object is passed through a hole and processed by receiving surface pressure from the inner surface of the hole. This invention relates to diamond tools, especially tools using synthetic diamond single crystals.

[Conventional technology]

Single crystal diamond has the highest hardness of any existing material and has excellent wear resistance, so it is used in a variety of applications such as cutting tools, dies, and dressers. However, up until now, all natural diamonds had been used. Synthetic diamonds have been strongly requested by the market, and the applicant's commercial launch in 1985 was the first in the world, and is currently the only one in the world.

In addition, Japanese Patent Application Laid-Open No. 59-229227, which was filed by applicant Toyama,
In the publication, a wire drawing die using a synthetic diamond single crystal is proposed, and a wire drawing die that makes holes perpendicular to the crystal plane (100) or (111) is developed. In this case, holes are directly drilled into the synthesized diamond (without cutting it).

[Problem that the invention seeks to solve]

We will discuss the problems when using natural diamonds with respect to wire drawing dies, which are a typical application.

In the wire drawing die, as shown in FIG. 1, a diamond 1 having a through hole 2 is fixedly supported in a die case 3 by a sintered metal 4. To ensure this fixation, two parallel upper and lower surfaces 5.5' are required.

Incidentally, since natural diamonds are subjected to melting action during the production process, they rarely have smooth crystal faces, and generally have rounded, curved surfaces that are irregular in shape. Therefore, when making the two upper and lower surfaces 5.5', an expert usually uses a looper or the like to determine the crystal plane by looking at the condition of the streaks appearing on the surface and the general external shape. However, the shape depends on the ease of polishing, etc., and the actual situation is that the crystal plane is (110
) or (111), it is difficult to align all the upper and lower 5.5' surfaces to a specific crystal plane, and it is difficult to make products with large variations in quality. Ta.

Until now, the wear resistance of natural diamond dies is 5.5 on either the (110) or (111) crystal plane on the upper and lower sides.
', and the die hole 2 is made perpendicular to this, which is considered to be good, and (100) is inferior and is therefore avoided. However, it has not been sufficiently clear which is better, (110) or (111), as there is greater variation.

Next, in a sintered mount that securely supports a natural diamond with sintered metal, thermal stress corresponding to the difference in thermal expansion coefficient between the diamond and the sintered metal occurs during cooling and shrinkage from the sintering temperature to room temperature. As a result, tightening and elongation pressure (external pressure) acts on the diamond part from the sintered metal, and compressive stress is applied to the diamond.

This compressive stress has a reinforcing effect that reduces the tensile stress generated in the diamond part due to the internal pressure (die surface pressure) that acts on the inner surface of the die hole during wire drawing when the die is used as a wire drawing die after processing the die hole. There is.

However, since natural diamonds are irregular in shape, they are not symmetrical with respect to the center axis of the die hole (center axis of the inscribed circle), as shown in Figure 2, and the extra wall area is small with respect to the inscribed circle. There are many, and the distribution is uneven. Therefore, the external pressure mentioned above
When internal pressure is applied, uneven stress and displacement occur,
When used as a wire drawing die, it causes uneven wear and cracking, leading to problems such as shortening and dispersion of die life.

Furthermore, in the above-mentioned patent publication regarding a wire drawing die using a synthetic diamond single crystal, a hole is directly drilled in the synthesized diamond, and one die is made for each synthetic diamond. Therefore, there is a problem that the price becomes high.

Further, in this case, attention is focused exclusively on crystal planes (100) and (111). This is because the parallel planes of the synthetic diamond single crystal are used as they are, and it has not been investigated whether there are other crystal planes that are better than the parallel planes.

Furthermore, the problem of the excess area and the bias in its distribution has not been investigated, and there are problems similar to those of natural diamond.

[Means for solving problems]

In order to solve the above-mentioned problems in tools using natural diamond or synthetic diamond, this invention divides diamond synthesized under ultra-high pressure and high temperature, so that both parallel surfaces are aligned with the crystal plane (110). A certain small single crystal is formed, a hole is provided perpendicular to the above two parallel surfaces, the shape of each surface is formed symmetrically with respect to the central axis of the hole, and the side surface is formed with a shape symmetrical with respect to the central axis. The structure is such that they are formed in parallel.

The details are detailed below.

To create a synthetic diamond single crystal at ultra-high pressure and high temperature, 0
．． If a single crystal that is slightly larger than a 0-seed crystal is grown using a method of growing a seed crystal about the size of a crane, the cost will be high; on the other hand, if the single crystal is too large, the cost will be high. , the optimal size is 4 dragons. The method of dividing this by cutting with a laser or a blade is most advantageous in terms of cost. Since the single crystal shape is uniform, the two parallel upper and lower surfaces of the small single crystals divided during processing can all be arranged into a specific crystal plane (110).

This time, the inventors of this application made the upper and lower two faces of a small single crystal divided into synthetic diamond single crystals square, and produced three types of crystal faces: (110), (111), and (100). As a result of making dies with die holes perpendicular to these and comparing the die life such as wear resistance as wire drawing dies, (110) was the best, followed by (III),
(100) (see Example 1).

There are various possible shapes that are symmetrical to the central axis of the through hole perpendicular to the upper and lower two surfaces of a small single crystal separated from a synthetic diamond single crystal, and the side surfaces are parallel to the central axis. (^) to (C) show representative shapes. In the cutting process of diamond using a laser or the like, a square shape is preferable from the viewpoint of processing technology and cost.

Now, considering the effects of the symmetrical shape, one is the stress generated in the diamond part (circumferential stress) due to the clamping pressure (external pressure) during sintering mounting of the die and the internal pressure during processing with the wire drawing die. There is a distribution of displacement (radial displacement). In particular, stress and displacement are greatest near the die hole, and the greater the stress and displacement at this location, the more wear and tear the die will have, and the more severe it will be in terms of strength, such as cracking.

The second consideration is the size of the extra thickness area (difference between the total area and the inscribed circle area) relative to the inscribed circle in terms of shape, and whether or not the extra thickness is evenly distributed. It is necessary to consider both of these aspects together, and when comparing the effects of symmetry, even if the stress and displacement values and their fluctuation widths are the same or have small differences, if the excess wall area and its distribution state are different, the wear of the die will be uniform. It is thought that it affects sexuality.

The inventors of this application have investigated the case where the upper and lower surfaces of a small single crystal of synthetic diamond are square and regular hexagon.
A comparative study was conducted on the stress, displacement, and extra thickness mentioned above in comparison with natural diamond. It is most appropriate to use the axially symmetrical finite element method to calculate stress and displacement. Therefore, for synthetic diamonds, the models shown in Figures 5 to 8 are set, and for natural diamonds, calculations are complicated due to irregular shapes. Therefore, as shown in Fig. 4, the upper and lower surfaces were made into elliptical models, and the long axis side of the sides was set as a spherical surface, and the short axis side was set as a flat surface. Incidentally, the shapes of the two upper and lower surfaces had the same inscribed circle.

As a result of these calculation studies, the stress, displacement, and their fluctuation range in the square case of the present invention are approximately the same as those values in the elliptical model of natural diamond, but the extra wall area and its distribution are completely different. That is, since the square shape of the present invention has a relatively small area of excess wall thickness and is evenly distributed at the four corners of the square, it is advantageous in terms of uniform wear of the die and stabilization of strength.

In addition, in the case of a regular hexagon, the fluctuation range of stress and displacement is smaller than in the elliptical model of natural diamond, and it is even more advantageous than the case of a square in terms of extra wall area and its distribution. is expected to increase.

The present invention will be specifically described below with reference to Examples.

[Example 1] The cut and divided small single crystal of a diamond single crystal synthesized under ultra-high pressure and high temperature is a hexahedron (see (A) in Figure 3), and its upper and lower two faces are 1.4 mm x 1. .4 It is a crane square with a thickness of 1.1 m, and the upper and lower crystal planes are (110), (111), and (100), respectively.
I built something on the street.

Dice holes were perpendicularly drilled in the upper and lower surfaces of these hexahedral single crystals to produce dice with a diameter of 0.28 mm and a diameter of 0.26 mm. With these dies, stainless steel wire 5US304
When wet wire drawing was performed, the amount of wire drawn until the end of the die life was as shown in Table 1. The natural diamond die used for comparison had the same diameter and was drawn under the same conditions as the synthetic diamond single crystal die. The product of the present invention with the crystal plane (110) exhibited performance approximately 2.0 times that of natural diamond.

Comparison synthetic diamond single crystal dies with crystal faces (111) and (100) have performance approximately 1.5 and 1.1 times that of natural diamond, respectively, and the present invention product using crystal face (110) showed the best results.

□Table 1 [Actual surroundings for stainless steel msu units*
ND...Natural diamond [Example 2] The single crystal body obtained by cutting and dividing the synthetic diamond single crystal similar to that in Example 1 is a hexahedron (see Fig. 3 (^)), with either two upper and lower faces or one .0+ux 1. Ow square, thickness 0
．． The dimensions are 6 cranes, and the upper and lower two crystal planes are each (110).
, (111) and (100) were made.

Dice holes were perpendicularly made in the upper and lower two surfaces of these hexahedral single crystals, and dies with a diameter of 0.09 On were manufactured for each.

When ultra-fine copper wire was wet-drawn using these dies, the amount of wire drawn until the life of the die was reached was as shown in Table 2. The natural diamond die used for comparison had the same diameter and was drawn under the same conditions as the synthetic diamond single crystal die. The product of the present invention with the crystal plane (110) exhibited performance approximately 2.0 times that of natural diamond. In addition, the comparative synthetic diamond single crystal dies with crystal planes (111) and (100) have performance approximately 1.5 times and 0.9 times that of natural diamond, respectively, and the performance of the synthetic diamond single crystal dies of the present invention with crystal planes (110) is about 1.5 times and 0.9 times that of natural diamond, respectively. product showed the best results.

Table 2 The effect of the symmetrical shapes of the square and regular hexagonal shapes shown in Fig. 3 on the upper and lower surfaces of the small single crystals split from the diamond single crystal synthesized under ultra-high pressure and high temperature on the 1-wire wire. We calculated and compared the results with those of asymmetrically shaped natural diamonds to estimate the effects on wear resistance and strength when used as wire drawing dies.

An axially symmetrical finite element is used to calculate the stress and displacement generated when tightening and stretching force (external pressure) acts on the diamond part during sinter mounting of the die, and when internal pressure acts on the diamond part of a wire drawing die. Calculated according to the law. We also calculated and compared the area and distribution of extra thickness with respect to the inscribed circles on the upper and lower surfaces.

First, in order to analyze the stress and displacement using the finite element method and to compare the excess thickness, the following shape models were set up from Figures 3 and 4, respectively.

Figures 5 and 6 are synthetic diamond squares,
Figures 7 and 8 show the model of a regular hexagon when mounted by sintering and with a wire drawing die, respectively, taking into account the calculations for natural diamonds, the upper and lower two sides are oval, and the side is on the long axis side. The model is shown when sintered and mounted with a spherical surface, short axis side or flat surface, and a model with a wire drawing die. In these figures, 6 is a synthetic diamond, 6' is a natural diamond, and 7 is a synthetic diamond.
indicates sintered metal.

In the axially symmetrical limited element method calculation, the external pressure Q at the time of sintering mounting is
= 110 kg/an", and the internal pressure P at the wire drawing die
= 220kg/as”, die hole diameter o, so@
-, circumferential stress σkg/at thickness Z=0.35m
sn" and the radial displacement Ur [ml. The results are shown in Fig. 9 and Fig. 1O. Note that below the O line in each figure, the compressive stress at the time of mounting (Fig. 9) and the displacement (
Figure 10) is shown.

First, during sinter mounting, as the diamond radius becomes smaller, the compressive stress and displacement tend to decrease, but the difference is not very large.

When using wire drawing dies, when the diamond radius becomes smaller,
Stress and displacement tend to increase. Table 3 shows a comparison of stress and displacement near the die hole, where the maximum values are shown near the die hole. Results of comparing the stress and displacement values, that is, the fluctuation range, at the minimum diameter (radius of the inscribed circle) and the maximum diameter (radius of the circumscribed circle) for synthetic diamond squares, regular hexagons, and natural diamond ellipses. , there is not much difference between a square and an ellipse, and when comparing a regular hexagon and an ellipse, the regular hexagon has smaller fluctuation ranges of stress and displacement, and is more uniform.

Similar to Table 3, Table 4 shows a comparison of the area and distribution of excess meat.
It can be seen that in the product of the present invention, the extra wall area and the extra wall area ratio are smaller as compared to the natural diamond ellipse model and become smaller as the shape changes from a square to a regular hexagon and further to a regular polygon closer to a circle.

Regarding the distribution of extra thickness, in a square, it is evenly distributed in the four corners, and in a regular hexagon, it is evenly distributed in the inner corners, so it is difficult to create an irregular shape like a natural diamond or an uneven distribution of extra thickness like in an ellipse model. Stress and displacement are also made more uniform. As a result, there is an effect of preventing uneven wear of the die.

Table 3: Changes in stress and displacement near the chair hole Table 4: [Distribution of extra metal and surface a] [Effects] As described above, the tool of the present invention can be By using a small single crystal, it is possible to use (110) as the two parallel crystal planes for drilling holes, which makes it possible to use other crystal planes (100) or (111). This has the effect of further improving wear resistance.

Furthermore, by forming the two surfaces symmetrically with respect to the central axis and with the side surfaces parallel to the central axis, uneven wear of the hole can be prevented.

Furthermore, since the synthetic diamond is divided into small single crystals, the price per piece can be reduced.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a die using natural diamond, Fig. 2 shows a natural diamond, (a) is a plan view, (b)
) shows a front view, Figures 3 (A) to (C) show a single crystal of synthetic diamond, (a) shows a top view, (b) shows a front view, and Figure 4 shows a model of a natural diamond. , (a) is a plan view, (b) is a front view, FIG. 5 is a cross-sectional view of a model of a sintered synthetic diamond mount, FIG. 6 is a cross-sectional view of a model of a synthetic diamond wire drawing die, and FIG. 7 is a cross-sectional view of a model of a synthetic diamond wire drawing die. is a cross-sectional view of a model of a natural diamond sintered mount, Fig. 8 is a cross-sectional view of a model of a natural diamond wire drawing die, Fig. 9 is a graph of the analysis results of circumferential stress, and Fig. 10 is a radial displacement. This is a graph of the analysis results. 1... Natural diamond, 2... Hole,
3...Dice case, 4...Sintered metal, 5.5'...Face, 6...Synthetic diamond, 6'...・Natural diamond, 7...
...Sintered metal. Patent applicant Sumitomo Electric Industries, Ltd. Agent Kama 1) Text 2 Figure 9 Figure 10

Claims (2)

[Claims] (1) By dividing a single crystal of synthetic diamond, a small single crystal whose two parallel end faces are both crystal planes (110) is formed, and a hole perpendicular to the two parallel end faces is provided, A tool using a synthetic diamond single crystal, characterized in that each surface is formed symmetrically with respect to the central axis of the hole, and the side surfaces are formed parallel to the central axis. (2) A tool using a synthetic diamond single crystal according to claim 1, wherein the end face shape of the small single crystal body is a regular polygon or a circle.